Safety Operating Procedures for Electrolysis and Primary Brine
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This post was last edited by sunjl1981 on 2013-1-6 at 20:46. I urgently need the safety procedures for electrolysis and primary brine handling; I hope someone can help me as soon as possible! # + + .
Safety Technical Regulations for Ion-Exchange Membrane Caustic Soda Production Chapter 1 General Provisions Article 1 These regulations apply to the production of caustic soda through the electrolysis of salt using the ion-exchange membrane method. Chapter 2: Safety Requirements for Materials Article 2: The ammonium content in the water used for dissolving salts, raw salt, and soda ash must be analyzed regularly to ensure that the ammonium level in the brine used for electrolysis remains at ≤1ppm. Article 3: Auxiliary materials: Barium chloride is a toxic substance and should be stored in designated locations, under the responsibility of designated personnel. Article 4: The water content in chlorine shall be ≤100 ppm. Chapter 3: Technical Regulations for Production Safety Article 5: Key Safety Indicators 1. Requirements and control limits for the analysis of ammonium content in crude salt: (1) Inorganic ammonium content ≤ 15ppb ； (2) Iron ion content ≤ 900ppb ； (3) Sodium chloride content: 308–314 g/l ； (4) Ca+Mg≤5ppm. 2. Quality requirements for the secondary brine: (1) Ca+Mg≤20ppb ； (2) Sr≤200ppb (3) Iron ion content≤500ppb ； (4) Ni≤10ppb ； (5) Ba≤500ppb. 3. Quality requirements for the anode solution: sodium chloride content of 220–230 g/l. 4. Free chlorine in high-purity acid ≤300ppb. 5. The chlorine-hydrogen pressure difference should be controlled at 40 mbar. 6. The hydrogen content in single-tank chlorine is ≤0.4%. 7. The oxygen content in the hydrogen main pipe shall be ≤0.4%. 8. Before and after shutting down or starting up the electrolysis system, the hydrogen system must be purged with an inert gas (if nitrogen is used, its purity should be greater than 99%, with oxygen content ≤0.5%) ； Before driving, the oxygen content in the hydrogen pipeline should be less than 1%. Article 6 Safety requirements during production: 1. The nitrogen flow rate in the anode solution is 5 Nm3/h. 2. During the operation of the electrolyzer, it is necessary to ensure that the direct current remains stable, the secondary brine is stable continuously, the catholyte is stable continuously, and the pressures of chlorine and hydrogen as well as the pressure differences remain steady. 3. During the chlorohydrogen treatment process in the electrolysis system, it is necessary to maintain a positive pressure in the hydrogen system; a large negative pressure is strictly prohibited in the drying tower, and negative pressure is also strictly prohibited in the hydrogen main pipeline. 4. During the operation of the electrolyzer, it is prohibited to release hydrogen gas inside the plant. 5. Install venting and drainage devices on the hydrogen pipeline. 6. The outlet flow rate of the turbine is ≥1000 Nm3/h; the fuel injection pressure is 1.0–1.5 MPa, the oil temperature is 30–55°C, and the motor current is ≤280 A. 7. During the operation of the electrolytic cell, all personnel must wear insulated shoes, and it is prohibited to touch the electrolytic cell with one hand while touching other grounded components to prevent electric shock. Article 7: Special requirements in emergency handling. In the event of a fire in the hydrogen system, it is strictly prohibited to create negative pressure within the system during handling, and shutting off the direct current supply must not be used as a solution. Chapter 4: Safety Technical Regulations for Mechanical and Electrical Equipment Article 8: Safety Devices 1. If underground equipment is used in the salt-chemical system, protective measures such as guardrails must be installed. 2. The hydrogen main pipe of the electrolysis system should be equipped with an automatic pressure relief device ； A flame arrester must be installed on the hydrogen vent pipeline. 3. The electrolysis system should be equipped with devices to handle chlorine leakage accidents. 4. The buildings housing the electrolysis and hydrogen systems must be equipped with lightning protection measures. 5. The upper structure of the electrolysis plant must not have any dead zones for ventilation, and it must have good ventilation to prevent hydrogen from accumulating inside the plant. 6. In departments that use hydrogen, hydrogen pipelines should be equipped with water seals, and hydrogen systems (including cooling and drying equipment) must have burst disks. 7. A leakage prevention device must be installed at the flanges of high-temperature alkaline liquid pipelines. 8. Sulfuric acid pipelines must be equipped with anti-spray protection devices. Article 9: Special requirements for mechanical and electrical equipment 1. An anti-static device must be installed in the hydrogen system ； The grounding resistance value for static electricity prevention should be less than 100 ohms. 2. The lighting fixtures used in the electrolysis plant shall meet the explosion-proof requirements for Class Q-2 areas. The vehicle does not need to be explosion-proof, but the hook needs to be demagnetized. 3. The design and construction standards of the hydrogen system shall meet the requirements for Class A fire hazard ； The electrical equipment used shall meet the explosion protection requirements for Class Q-1 areas. 4. The chlorine delivery system shall be equipped with two power supplies. 5. The chlorine delivery system must be equipped with a check valve. Article 10: In case of emergencies such as material leakage, spillage, or accidental pipe perforation, it is necessary to remain calm. First, shut down the pipeline as well as the valves and cocks located near the equipment. If a shutdown is required, carry out an emergency shutdown to prevent excessive loss of material due to improper handling. Article 11 Safety devices such as safety valves, alarms, pressure gauges, thermometers, vacuum gauges, and protective covers must always be complete, sensitive, and reliable, and should be calibrated regularly. Article 12: Safety Provisions for Maintenance 1. Maintenance personnel must strictly follow the maintenance operation tickets when conducting inspections. 2. Clear pipes or open pressurized steam, liquid, or water streams; it is prohibited to direct the pipe outlet at human bodies. 3. When multiple people are working together in overlapping tasks, it is important to take care of one another and stay in touch. 4. In outdoor areas affected by toxic and harmful gas pollution, it is necessary to consider the wind direction when carrying out maintenance work, and stand in the upwind area. 5. Before carrying out any welding or maintenance work on the hydrogen system, it is necessary to cut off the gas supply and replace it with nitrogen; furthermore, a gas detector must be used to check the hydrogen level – welding can only proceed when the hydrogen concentration is below 0.5%. 6. Before carrying out hot work on the sulfuric acid system, the materials must be cleaned thoroughly, and the hydrogen content must be below 0.5% before hot work can proceed. Chapter 5 Regulations on Labor Protection and Safety in the Working Environment Article 13 Operators at their posts must wear the prescribed labor protection equipment. Article 14 Personal Protection 1. Workers who are exposed to acids and alkalis must use protective glasses and other protective equipment. 2. Production workers who are in direct contact with chlorine must have gas masks or protective respirators available at their workstations. Article 15: The chlorine content in the air of production areas shall be regularly monitored, with the maximum allowable concentration being 1 mg/m3. Article 16 Other industrial hygiene requirements: Near the areas where acids and alkalis are produced and used, facilities for rinsing in case of acid or alkali burns, as well as eye wash stations, must be installed. Chapter 6 Supplementary Provisions Article 17 Use of Fire-Fighting Equipment 1. Appropriate fire-fighting equipment must be readily available at production stations, and the operators there must know how to use it. Fire extinguishing agents such as foam, carbon dioxide, and dry powder should be used. 2. In the event of a fire involving electrical equipment, carbon dioxide and dry powder fire extinguishers should be used; water must never be used to extinguish such fires. Article 18: Wind vane shall be installed in the production area. Article 19: First aid at the scene of personal injuries 1. Acid or alkali burns: Immediately rinse with plenty of water; seek medical attention promptly in severe cases. 2. Chlorine inhalation poisoning: Immediately remove the poisoned person from the scene and take them to a place with fresh air to rest; administer dimethicone via inhalation. In severe cases, provide oxygen or transport the patient to a medical facility for treatment.
Trial Operating Procedures for the HVM Membrane Process in Brine Production 1 Scope These standards specify the process flow for the HVM membrane process in brine production as well as the format for the original records related to this process. They define the tasks associated with this position, the organizational coordination relationships, the equipment under management, the production control parameters, the requirements for operation monitoring and inspection, daily management tasks, procedures for starting up and shutting down the system, methods for handling faults, and safety precautions. This standard applies to the operations in the HVM membrane method saltwater production process. 2 Normative reference documents: Refer to Q/NHGF F03 012—2004, the regulations for drafting process procedures and job operation instructions. 3 Terms and Definitions HVM membrane • Made of polytetrafluoroethylene, it possesses extremely stable chemical properties and a wide range of applications ； • Low friction coefficient, heat resistance, toughness, and resistance to aging ； • Tubular monolithic structure, free from membrane peeling, tearing, corrosion, and other issues; highly efficient and long-lasting ； • The pore size ranges from 0.22 to 0.5 microns, enabling surface filtration. 4 Job Responsibilities: Responsible for using the brine returned from electrolysis and distillation, recycled water, as well as other miscellaneous waters in the system to dissolve raw salt. After removing inorganic impurities such as Ca2+, Mg2+, and SO42- as well as mechanical impurities from the crude brine, a brine of the appropriate concentration that meets the process requirements is obtained, which is then sent to the electrolysis process. 5 Production Organization and Coordination Relationships 5.1 Production Organization It is under the leadership of the factory management, workshop supervisors, and shift leaders; production activities during a shift are carried out under the unified command of the shift supervisor and the company’s dispatch team. 5.2 Cooperative Relationships 5.2.1 Work closely with the electrolysis team to supply qualified brine to the electrolysis workshop. 5.2.2 Coordinate with the personnel of the old brine system to properly regulate water distribution and the transportation of concentrated brine. 5.2.3 Provide compressed air in coordination with the old brine system, evaporation centrifuges, electrolytic cell maintenance, ion membrane secondary brine purification, and the pure water unit in the power plant. 5.2.4 Keep in timely contact with the analysis staff to monitor the quality of the refined brine. 6 Production Principle and Process 6.1 Production Principle 6.1.1 Removal of bacteria, algae, and other organic substances Bacteria and algae in saltwater are killed by sodium hypochlorite, while organic substances such as humic acid are oxidized and broken down into smaller molecules by sodium hypochlorite. 6.1.2 To remove Ca2+, sodium carbonate solution is added to the saline solution, where it reacts with the Ca2+ present to form an insoluble calcium carbonate precipitate. The reaction equation is as follows: Ca + CO32- → CaCO3↓. In order to remove all the Ca2+, the amount of sodium carbonate added must be slightly greater than the theoretical amount required by the reaction equation ； However, when the alkalinity of the brine is too high and the pH value exceeds 12, calcium carbonate dissolves again. Control the excess alkali level at 0.2 g/L to 0.8 g/L. 6.1.3 To remove Mg2+, NaOH solution is added to the saline solution, where it reacts with the Mg2+ present to form an insoluble Mg(OH)2 precipitate. The reaction equation is as follows: Mg2+ + 2OH- → Mg(OH)2↓. In order to completely remove Mg2+, the amount of NaOH added must be slightly greater than the theoretical amount required by the reaction equation ； Mg2+ and OH- begin to react at a pH of around 8; the reaction is completed rapidly at pH values of 10.5–12, resulting in the formation of gel-like flocs. When there is about 0.2 g/L excess of NaOH, the concentration of Mg2+ in the brine can be less than 1 ppm. However, if the brine is too alkaline, with a pH greater than 12, magnesium hydroxide will dissolve again. Control the excess alkali level at 0.1 g/L to 0.8 g/L. 6.1.4 Removal of organic matter and insoluble mechanical impurities: Since industrial raw salt contains various impurities that enter the brine during the salt production process, natural organic substances such as bacteria, algae, and humic acid in the brine are oxidized and broken down into smaller molecules by sodium hypochlorite. These substances are subsequently removed in the pre-treatment unit through the adsorption and coprecipitation action of iron salts such as FeCl3; some insoluble mechanical impurities are also removed at the same time. 6.1.5 Free chlorine: Free chlorine in brine generally exists in the form of ClO-. During the production process, ClO- is removed by adding Na2SO3; the ionic reaction is as follows: ClO- + Na2SO3 → Na2SO4 + Cl-. 6.2 Description of the process flow 6.2.1 Salt preparation: Fresh brine from ion-exchange membrane electrolysis, brine recovered through evaporation, filtrate from plate and frame filters, industrial water, and brine recovered from the regeneration system – all such types of water are fed into the water distribution tank V0103 for mixing. After the water from the various sections mentioned above is mixed in the water distribution tank V0103, the SO42- concentration in the water is adjusted to ≤2 g/L through control mechanisms. This solution, which serves as brine, is then pumped by the brine feeding pump P0102 and passed through the preheater E0101 for heat exchange; at a temperature of 50 ℃ to 60 ℃, it is fed into the brine tank V0104. There, the water dissolves the raw salt, resulting in saturated crude brine ； The concentration of the brine is then adjusted to between 305 g/L and 318 g/L by adding river water. Before it flows into the reaction tank, the additives sodium hydroxide and sodium hypochlorite are added in the pre-baffle tank R0102 according to the process requirements, in order to adjust the pH value to between 10.5 and 12; the excess amount of NaOH is kept between 0.1 g/L and 0.8 g/L, while the residual amount of NaClO in the brine remains between 5 mg/L and 15 mg/L. Subsequent thorough mixing takes place in the pre-reaction tank R0103, during which the magnesium ions in the brine react with sodium hydroxide to form magnesium hydroxide, while organic substances such as bacteria, algae, and humic acid are oxidized and broken down into smaller organic molecules by sodium hypochlorite. 6.2.2 Pretreatment: The brine in the pre-reactor tank R0103 is pumped by the pressure pump P0103 into the air-water mixer R0105. There, it mixes with air before entering the pressurized dissolved air tank V0112 (where the air pressure is 0.25 MPa to 0.3 MPa). It then proceeds to the pretreater V0105, where FeCl3 is added in the venturi mixer R0104 located at the inlet of the pretreater. FeCl3 acts as a flocculant; when the brine enters the pretreater, the pressure drops suddenly, causing the air present in the brine to come out as numerous tiny bubbles. These bubbles attach themselves to the particles formed by the combination of the flocculant and Mg(OH)2, thereby reducing the specific gravity of the mechanical impurities in the brine and allowing them to float to the surface of the pretreater. This sludge is then removed through the upper sludge discharge outlet. Some of the heavier particles sink to form sediment, which is discharged through the lower sludge discharge outlet, while the clear liquid flows out through the outlet. 6.2.3 HVM Membrane Filtration: The pretreated brine still contains a small amount of mechanical impurities, trace amounts of magnesium hydroxide, and a large amount of calcium ions. Before it enters the reaction tank R0107, sodium carbonate is added, with the excess amount of Na2CO3 being controlled between 0.2 g/L and 0.8 g/L. This allows the calcium ions in the brine to react with sodium carbonate to form calcium carbonate precipitate, which is then removed; this precipitate also serves as a filtering aid for the HVM membrane filtration process. After full reaction, the brine flows automatically into the feed tank V0122. Sodium sulfite solution is then added to remove free chlorine from the brine, after which it flows automatically into the HVM filter X0101 for filtration. The clear liquid overflows from the upper chamber of the HVM membrane filter. After filtering for a certain period of time, once the thickness of the filter cake reaches a certain level, the system automatically switches to backwash mode, causing the filter cake to detach from the membrane and settle at the conical bottom of the filter. The system then returns to filtration mode. When the thickness of the residue at the bottom reaches a certain level, the system automatically opens the residue discharge valve, allowing the residue to be discharged into the salt sludge tank V0117. The filtered, qualified brine flow into the refined brine storage tank V0120, and is then sent to the electrolysis process via the refined brine pump P0110. After the membrane has been in operation for a certain period of time, to maintain high filtration capacity and low filtration pressure, the HVM membrane is chemically regenerated using approximately 15% hydrochloric acid. 6.2.4 Filtration: The brine sludge in the brine sludge tank is pumped out using a brine sludge pump and sent to a plate and frame filter press for filtration. The salt sludge is washed and dehydrated through pressure filtration, and then dried with compressed air to produce a filter cake with a moisture content of less than 50%, which is then sent out of the processing area ； The filtrate flows by gravity into the debris tank, where it is pumped back to the distribution tank by a debris pump. 6.3 Process Flow Diagram with Control Points The process flow diagram with control points is shown in Appendix A. 7 Equipment under management: A list of the equipment under management is provided in Appendix B. 8 Process Control Parameters The list of production process control parameters is provided in Appendix C. 9 Production Operation Methods 9.1 Preparations before startup 9.1.1 Check whether the lubrication and turning systems of all pumps are functioning properly. 9.1.2 Check whether the compressed air supply is unobstructed. 9.1.3 Check whether the refining agents used meet the production requirements and the required quantities, as well as ensure that the pipelines are unobstructed. 9.1.4 Check whether each valve opens and closes smoothly and properly. 9.1.5 Check whether the control instruments are functioning properly and whether the automatic control devices are sensitive. 9.1.6 Once everything is ready, notify all positions to prepare for departure. 9.2 Operation During Driving 9.2.1 For preparing the saline solution, first open the valves for the recycled water such as the brackish water produced by ion-exchange electrolysis in water preparation tanks V0103b/c, the saltwater recovered through evaporation, and miscellaneous water. Adjust the ratio of the recycled liquid as appropriate using FIC102, and make manual adjustments to ensure that the SO42- concentration in the prepared water is ≤2 g/L and that the alkalinity level is within acceptable limits. 9.2.2 Open the cooling water valves and inlet valves of the centrifugal pumps that need to be activated; if there is a suction vacuum tank, it must be depressurized first and filled with water. 9.2.3 Open the inlet and outlet valves of the metering pump to be activated, as well as the outlet valve of the refining tank, and check whether the system pipelines are unobstructed. 9.2.4 Open the outlet valve of the rotameter to be activated, the manual valves on both sides of the automatic valve, and close its bypass valve. 9.2.5 Open the steam trap or open the circulating water return valve. 9.2.6 Check and start the air compressor. 9.2.7 When the liquid level in the water distribution tank V0103 reaches about more than 1/2, open the compressed air valve to initiate stirring, and at the same time inform the analysis team to conduct tests for alkali and SO42- content in the water ； When the water distribution meets the requirements, open the water distribution outlet valve and inform the salt station to add salt. 9.2.8 When the desalination tanks V0104a/b are filled with salt, open the inlet valves of these tanks, activate the pump associated with the water supply system, and start the pumps P0102a/b used for supplying water to the desalination tanks; then slowly open the outlet valves ； Based on the indications of the salt dissolution temperature and the temperature of the brine in the preprocessor, the temperature of the brine used for dissolution is controlled by opening the steam inlet valve or the circulating water control valve of the brine heat exchanger E0101. 9.2.9 When saline overflows into the front reaction tank R0103, slowly open the NaOH and NaClO rotameters FI110 and FI111, and add NaOH and NaClO to the baffled tank according to the intermediate control parameters and analysis data (while starting the mixer for stirring), maintaining the pH value between 10.5 and 12, with the excess amount of NaOH ranging from 0.1 g/L to 0.8 g/L ； Control the content of NaClO in the brine between 5 mg/L and 15 mg/L. 9.2.10 When the salting temperature reaches the specified range, set the automatic control valve of the brine heat exchanger to automatic mode in order to maintain the salting temperature at 55°C ± 5°C (for the baffle tank) ； And adjust the saltwater concentration properly. 9.2.11 When the liquid level in the current reaction tank R0103 reaches above 1/2, confirm that the inlet valves of the rotameter FI112 leading to the gas-water mixer and the pressurized dissolved air tank have been fully opened. Connect the series of pressure pumps and start the pressure pumps P0103a/b; at the same time, open the air automatic valve to supply air to the gas-water mixer through the air buffer, adjusting the pressure in the pressurized dissolved air tank to between 0.25 Mpa and 0.3 Mpa. 9.2.12 When the liquid level in the pressurized dissolved air tank reaches the second sight glass, open the pressure relief valve FIC105 ； Start the FeCl3 metering pump P0113a/b, adjust the metering pump’s control knob according to the intermediate control parameters, and add FeCl3 to the venturi R0104 ； After being mixed with crude brine, FeCl3 enters the preprocessor V0105 (the stop valve must be opened in advance). 9.2.13 Adjust the pressure relief valve FIC105 to the appropriate position so that the preprocessor V0105 can operate at an appropriate upward flow rate; after confirming the stability of the automatic level control system for the pre-reactor and the pressurized gas dissolution tank, set the pressure relief valve FIC105 to automatic mode. 9.2.14 During this period, pay close attention to the mixing of compressed air with saline water; simultaneously observe the color and floating behavior of the salt sludge in the saline water at the upper sludge discharge port, and make adjustments to the rotameter feeding into the gas-water mixer, as well as to the amount of compressed air used and to the quantity of FeCl3 added. 9.2.15 And adjust the control of excessive NaOH content in the brine of the salt crystallization tank based on the NaOH content in the effluent. 9.2.16 Open the vent valve of the reaction tank to exhaust air. 9.2.17 Once the pre-treated brine enters the rear reaction tank R0107, start the Na2CO3 metering pump; according to the process requirements, adjust the control valve of this pump to add Na2CO3 to the rear reaction tank in order to precipitate the Ca2+ ions present in the solution, keeping the excess amount of Na2CO3 between 0.2 g/L and 0.8 g/L. 9.2.18 When brine flows out from the release valve of the rear reaction tank, close the vent valve. 9.2.19 When the liquid level in the rear reaction tank R0107 rises to a high level and overflows into the feed high-level tank V0122, Na2SO3 solution is added by adjusting the Na2SO3 rotameter FI121 to remove free chlorine. 9.2.20 When the liquid level in the feed tank reaches 1/3, open the manual valve at the inlet of filter X0101 and the manual valve of the backwash tank; ensure that all other valves of the filter are closed. Also, open the valve for returning fluid to the water distribution tank, and open the main sludge discharge valve of the filter. 9.2.21 Start the filter; when brine enters the clear liquid chamber, switch the HVM membrane controller to automatic filtration mode. 9.2.22 After the process is connected, allocate the appropriate flow rate of brine to the filter. 9.2.23 Once all the control parameters of the filter meet the required standards and the system is stable, close the valve leading to the water distribution tank V0103, allowing the brine to overflow into the brine tank V0120. 9.2.24 When the liquid level in the brine storage tank is about 1/2 full, notify the ion-exchange membrane electrolysis section to start up. 9.3 Normal Operation 7.3.1 Salt Dissolution and Refining 9.3.1.1 Adjust the outlet temperature of the brine in the brine heat exchanger as needed, keeping it between 50 ℃ and 60 ℃, and ensure that the temperature variation is less than 5℃. 9.3.1.2 Control the liquid level in the water distribution tank to prevent vacuum conditions, pay attention to the liquid levels in the pre-treatment tank and the pressurized aeration tank, and strengthen the inspection of pumps. 9.3.1.3 Adjust the excess amount of NaOH to between 0.1 g/L and 0.8 g/L based on the pH value and analysis data. 9.3.1.4 Based on the analysis data and evaluations, the NaClO content in the brine is controlled to be between 5 mg/L and 15 mg/L. 9.3.1.5 Based on the analysis data, by controlling the salt layer height and adjusting the opening degree of the water pipe valves, the concentration of the brine is adjusted to between 305 g/L and 318 g/L. 9.3.1.6 Keep the compressed air pressure between 0.25 MPa and 0.3 MPa. 9.3.1.7 Control FIC105 to ensure stable flow of brine from the air dissolution tank into the pretreated salt water stream. 9.3.1.8 Control the flow rate of FeCl3 based on the flow rate of the brine, with the aim of keeping the concentration of ferric trichloride in the brine between 5 mg/L and 30 mg/L. Adjustments are made by analyzing the data and observing the color of the brine as well as its sedimentation behavior. 9.3.1.9 Adjust the amount and frequency of sludge discharge based on the condition of each discharge; if the sludge is too thin, reduce the amount or frequency of discharge accordingly, and vice versa. 9.3.1.10 Control the temperature difference between the brine in the salt pond and the desalinated water from the preprocessor. 9.3.1.11 Stabilize the flow rate into the reaction tank to ensure that the excess amount of Na2CO3 remains within the range of 0.2 g/L to 0.8 g/L. 9.3.1.12 Adjust the amount of Na2SO3 added based on the intermediate indicators to keep the free chlorine in the brine at ≤2 mg/L. 9.3.1.13 Regularly clean the debris around the desalination tank to ensure the proper operation of the system. 9.3.1.14 Constantly monitor the mixing conditions in the front and rear reaction tanks to ensure continuous mixing without interruption. 9.3.1.15 Regularly check the addition of various refining agents to prevent pipeline blockages or flow interruptions due to a lack of such agents in the sump tanks. 9.3.1.16 Refuel operating equipment in fixed quantities, at fixed locations, and of fixed quality. 9.3.1.17 Resolutely prevent engine oil from falling into saltwater. 9.3.1.18 Work the first shift during the day to switch the pump, preventing crystallization and blockages in the pump and pipelines as well as facilitating maintenance. 9.3.2 HVPM Membrane Filtration 9.3.2.1 Regularly check the operation of the filter ； 9.3.2.2 Regularly check the transparency of the liquid level at the filter outlet deck; if the brine becomes turbid, stop the machine immediately ； Remove the membrane module for inspection; if any cracks are found, replace it with a new spare part promptly ； If there are no spare parts, cover it with a lid ； After restarting, first open the inlet valve of the water distribution tank. Once the impurities in the outlet tray of the filter have been removed and the brine meets the required standards, close the inlet valve of the water distribution tank, allowing the brine to flow back into the concentrated brine tank. 9.3.2.3 The appropriate filtration cycle and slag discharge cycle of the filter can be adjusted as necessary based on the conditions of the brine. 9.3.2.4 When situations that may render the brine at the filter outlet substandard are detected, such as low alkali level, membrane rupture, just after acid washing, or just upon startup, the brine at the filter outlet should be immediately diverted back to the water distribution tank. 9.3.2.5 Ensure the normal liquid level in the brine storage tank and the proper operation of the brine pump, so as to guarantee the proper supply of brine to the electrolysis process. 9.4 Shutdown Procedure 9.4.1 Upon receiving the instruction, contact the relevant department to initiate the shutdown. 9.4.2 Stop the brine water pump (to cut off the supply of brine water to the ion-exchange membrane electrolysis section). 9.4.3 Stop adding salt, close the valves for river water or condensed water supply; when the saltwater concentration is below 305 g/L, close the preheater steam valve or the circulating water flow control valve TIC101, stop the water distribution valve in the salt dissolution tank, and close the water inlet valve of the salt evaporation tank. 9.4.4 Close the addition valves for the refining agents NaOH and NaClO. 9.4.5 The mixer may not be stopped during short-term shutdowns. 9.4.6 Stop the pressure pump, close the compressed air pipeline valve of the pressure gasification tank, close the automatic valve feeding into the pretreater, and stop adding the iron salt pretreatment agent. 9.4.7 Once overflow of the liquid from the pretreater’s outlet ceases, stop adding the refining agent Na2CO3. 9.4.8 Stop the filter. 9.4.9 When shutting down filter X0101, first press the stop button while it is in operation; once the HVM membrane filter enters the shutdown state, then stop the flow of liquid to the filter. 9.4.10 After stopping the filter, fill the HVM membrane filter with pure water up to above the top plate, maintain a certain liquid level, and close the main valve for discharging sludge from the filter. 9.4.11 If the shutdown period is long, it is necessary to drain the brine from the pressurized dissolved air tank and to fill the overflow outlet of the pretreater with a certain amount of water to prevent salt buildup in the pipeline equipment. 9.4.12 Enter the reason and time of parking on the report. 9.5 Emergency Shutdown: In the event of a sudden power outage while saltwater is being processed, the on-duty dispatcher must be notified immediately. The stop buttons for the pumps should be pressed to prevent the pumps from starting up suddenly once power is restored. Meanwhile, the outlet valves of all pumps, the outlet valve of the pressurized dissolved air tank, the valve for FeCl3, and the valves for other refining agents should also be closed. The inlet valve of the filter should be closed once the instrumented pressure drops to 0.3 MPa. 9.6 Operations at Other Operating Points 7.6.1 Steps for Starting and Stopping Centrifugal Pumps 9.6.1.1 Starting the Pump Check the oil level and rotate the pump’s drive wheel 3–4 times. Check whether there are any noises or signs of jamming in the pump or motor. Once everything is normal, turn on the pump’s cooling water, open the pump’s inlet valve, press the start button, and then slowly open the pump’s outlet valve. 9.6.1.2 Shutdown procedure: Close the pump outlet valve, press the button to stop the pump, then close the inlet valve and turn off the cooling water for the pump. 9.6.2 Operating procedures for starting and stopping the metering pump 9.6.2.1 Starting procedure Check the oil level and manually rotate the coupling to make the pump run for more than two reciprocations, checking for any obstacles that could affect its operation ； Open the valves on the discharge pipe and suction pipe fully; once it is confirmed that the system is unobstructed and everything is ready, start the motor and adjust the flow rate by using the control gauge. 9.6.2.2 Shutdown Procedure: Press the stop button; once the pump has stopped running, close the inlet and outlet valves if necessary. 9.6.3 Preprocessor Operations 9.6.3.1 Sludge Discharge Operation 9.6.3.1.1 Close the outlet disc valve of the preprocessor to raise its liquid level. 9.6.3.1.2 Allow the floating sludge to flow into the sludge collection hopper and then into the salt sludge tank. 9.6.3.1.3 After sludge discharge, open the disc valve for normal clean water flow. 9.6.3.2 Lower sludge discharge operation: After the upper sludge discharge is completed, open the lower sludge discharge valve; close it once saline water is observed to be discharged. 9.6.4 Operation of the air compressor 9.6.4.1 Pre-startup preparations 9.6.4.1.1 Check that the oil level in the air compressor’s oil-gas tank is at the upper limit indicated by the gauge. Slightly turn the drain valve at the bottom of the oil-gas tank to release the condensed water inside, then tighten it again. When releasing the condensed water from the tank, make sure the machine has been shut down and left stationary for 2 to 3 days or more; if oil spills out during this process, immediately close the drain valve. Open the drain valve slightly, adjusting it so that only a slight amount of air flows out. 9.6.4.1.2 Open the air compressor outlet valve and rotate the compressor’s idler wheel to check if it moves smoothly and freely. 9.6.4.1.3 Check that the threaded joints, flanges of the air and oil pipelines inside and outside the air compressor, as well as the electrical connections, are all properly secured, with no leaks or looseness or other abnormalities. 9.6.4.1.4 Check whether the electrical equipment meets the startup requirements. 9.6.4.1.5 During the first start-up, it is necessary to operate the motor briefly to check whether its rotation direction is correct; otherwise, reverse rotation of the motor can cause severe damage to the compressor. 9.6.4.2 Methods and steps for normal operation 9.6.4.2.1 Press the Run button to start the air compressor. 9.6.4.2.2 Check whether the air compressor can operate properly under load; verify that it can shut down properly when the exhaust pressure reaches the set upper limit (0.65 MPa), and that it can restart automatically when the pressure drops to the set lower limit (~0.3 MPa) ； The exhaust temperature of the host should be below 100°C, and no abnormal signals should be displayed on the control panel. 9.6.4.2.3 Check the operation of the air pipeline; there should be no leaks, and the air flow rate and pressure should meet the operational requirements. 9.6.4.3 Methods and steps for normal shutdown: Press the stop button to halt the operation of the air compressor, close the outlet valve of the air compressor, and turn off the power supply. 9.6.4.4 Methods for handling long-term shutdowns: If the compressor will not be used for several weeks, it only needs to be operated once a week for about half an hour each time. If the compressor is not used for an extended period of time, all openings should be sealed to prevent moisture and dust from entering. Move the compressor to a place with less dust and that is cleaner, as much as possible. When reused, the lubricating oil should be replaced, and the original startup procedure should be followed. 9.6.4.5 Methods and steps for normal operation 9.6.4.5.1 Conduct inspections once per hour to check the exhaust temperature, outlet pressure, and other operating conditions. 9.6.4.5.2 The first shift of each shift must switch to use another unit. 9.6.4.5.3 Do not open the air compressor door during operation if there are no abnormal conditions, to avoid burns. 9.6.4.5.4 During operation, if it is detected that the oil level is low, the machine must be stopped, and refueling can only be carried out once the pressure in the air compressor system is zero. 9.6.4.5.5 Handling and maintenance of the interior of the air compressor must be carried out with the machine stopped, and only when the pressure in the air compressor system is zero. 9.6.4.6 Emergency shutdown procedure: In the event of abnormal noises, unusual vibrations, air leaks, oil leaks, or other such issues during operation, immediately press the emergency shutdown button of the air compressor to shut it down promptly, and close the outlet valve of the air compressor. 9.6.4.7 Operation after emergency shutdown or sudden power outage: When restarting after an emergency shutdown or sudden power outage, it is necessary to operate the device 2–3 times in pulse mode, and only after confirming normal operation can it be used normally. 9.6.5 Acid cleaning operation 9.6.5.1 Preparation for acid cleaning 9.6.5.1.1 Check whether the hydrochloric acid tank is filled with approximately 15% hydrochloric acid, and whether the hydrochloric acid pump and delivery pipes are functioning properly. 9.6.5.1.2 Press the filter shutdown button ； Open valve 12# for reflux, and close valve 11# for discharge. 9.6.5.2 Acid washing a) After the filter is shut down, perform a manual backwash until the liquid level drops below the deck plate; after opening one or two blanking caps, open valve 8# to drain all the brine from the filter, then close valve 8#. b) Open the pure water valves KV109 and KV107 to use pure water to clean the filter. Once cleaning water starts flowing from KV107, keep it flowing for 5 minutes, then close valves KV109 and KV107. Open the slag discharge valve KV106 to drain the cleaning water from the filter, and then close valve KV106. c) Open the KV102 acid inlet valve, valve 13#, and valve 9# for acid discharge; start the hydrochloric acid pump to feed acid in. Once acid begins to flow out from valve 9#, stop the hydrochloric acid pump, close valve KV102, and open valve 10# at the bottom of the filter. Adjust the air flow to an appropriate level and stir for one hour (small bubbles should be released; continuous bubbling should not occur). d) After the acid washing is complete, close valve 10#, open the KV105 acid discharge valve to drain all the acid, then close KV105 as well. Finally, close valve 13# and valve 9#. e) After cleaning is complete, open valve No. 12 that allows flow back to the water distribution tank, press the start button for the filter to enable it to operate properly, and monitor changes in the pH value of the saline solution. Once the pH value reaches above 9, analyze the various parameters of the filtered liquid; once these parameters are within acceptable limits, close valve No. 12 for reflux, and the filter will enter its normal operating mode, with the filtered saline being sent to the brine storage tank. 9.6.6 Procedure for preparing FeCl3 solution: 10 kg of solid FeCl3 is dissolved in water to make 1 m3 of solution with a FeCl3 concentration of 1%. On-site preparation: Weight of FeCl3 (kg) = 10V, where V is the volume of the FeCl3 preparation tank, in m3. For adding the FeCl3 solution, adjust the rotameter settings and calculate the required amount using the following formula: Q1 (L/h) = Q2 (based on 10 mg/L). Here, Q1 represents the amount of FeCl3 solution to be added, in L/h, while Q2 represents the volume of brine to be treated, in m3/h.
9.6.7 Preparation of NaClO solution: Take 100 kg of 12% NaClO solution (with a specific gravity of 1.05), add 100 kg of water to it, to obtain an approximately 6% NaClO solution. To add this solution, adjust the rotameter settings and calculate the required amount using the formula: Q1 (L/h) = 0.17Q2 (based on 10 mg/L). Here, Q1 is the amount of NaClO solution to be added, in L/h, and Q2 is the volume of brine to be treated, in m3/h. While adding the NaClO solution, monitor the free chlorine concentration in the brine entering the filter; an ideal range is 1 mg/L to 3 mg/L. Adjust the amount of NaClO solution added accordingly. 9.6.8 Operation of adding NaOH: Estimate the amount of NaOH to be added, and after checking whether the NaOH content in the brine is within the controlled range, adjust the rotor; generally, an electrolyte concentration of around 10% is used for NaOH. Measure the pH of the saline in the reaction tank before testing, and keep it between 10.5 and 12. The analysis shows that the NaOH content in the brine ranges from 0.1 g/L to 0.6 g/L. 9.6.9 Procedures for preparing Na2CO3 solution a) 125 kg of solid Na2CO3 is mixed with water to produce 1 m3 of solution, with a Na2CO3 concentration of 12.5 %. Weight of Na2CO3 (kg) = 125V, where: V is the volume of the Na2CO3 preparation tank, in m3. b) The electrolyte supplied for electrolysis is directly carbonated using CO2 gas. For the reaction with Na2CO3, estimate the amount of Na2CO3 to be added; after determining that the level of Na2CO3 in the brine is within the desired range, adjust the rotor and add Na2CO3 to the subsequent reaction tank. Ensure that the concentration of Na2CO3 in the brine entering the filter is between 0.2 g/L and 0.6 g/L. 9.6.10 Procedure for preparing Na2SO3 solution: Dissolve 5 kg of solid Na2SO3 in water to obtain 1 m3 of solution with a Na2SO3 concentration of 0.5%. Weight of Na2SO3 (kg) = 5V, where: V is the volume of the Na2SO3 preparation tank, in m3. For the reaction involving Na2SO3, the setting on the rotameter is adjusted according to the amount of free chlorine in the brine. The amount of Na2SO3 solution to be added is calculated using the following formula: Q1 (L/h) = 1 × Q2 (based on 5 mg/l). Here, Q1 represents the amount of Na2SO3 solution added, in L/h, while Q2 represents the volume of brine to be treated, in m3/h. 10 Abnormal conditions and their handling: Abnormal conditions that may occur during production and how to deal with them are outlined in Appendix D. 11 Shift handover: 11.1 The person taking over the shift should arrive at the post in advance and conduct a preliminary inspection along the designated route. After that, a pre-shift meeting is held, during which any issues identified during the preliminary inspection are discussed. The person handing over the shift then takes these concerns back to their team members so that they can address the problems promptly. 11.2 During shift handover, conduct the transfer carefully following the \"three ones\" principle (handing over item by item, one by one); the \"four senses\" principle (seeing, hearing, touching, smelling); and the \"five reports\" principle (reporting the item number, name, issues, measures, and current status). The person conducting the handover must create favorable conditions for the person leaving the shift. 11.3 The shift handovers assist each other in addressing major issues that arise during the handover process. 11.4 Strictly enforce the “Five Handovers” and “Five Non-Acceptances” system 11.4.1 The “Five Handovers” system: 11.4.1.1 Hand over production tasks and their completion status ； 11.4.1.2 Operating process conditions of the equipment and existing problems ； 11.4.1.3 Past quality and safety issues, and measures proposed to address them ； 11.4.1.4 Deliver all tools and equipment ； 11.4.1.5 Hand over record materials and equipment. 11.4.2 The “Five No-Acceptances” system: 11.4.2.1 Do not accept tasks if they have not been completed or issues have not been resolved as stipulated by the post responsibility system ； 11.4.2.2 Do not accept tasks if they are not completed and the reason is unknown ； 11.4.2.3 Quality and safety issues that remain unresolved or for which no corrective actions have been proposed will not be accepted ； 11.4.2.4 Tools and equipment that are lost or missing will not be replaced ； 11.4.2.5 Records that are incomplete or poor hygiene will result in rejection. 11.5 Accidents that occur during the handover process are the responsibility of the person handing over, while accidents that occur after the handover are the responsibility of the person taking over. In cases where it is unclear who is responsible, the person taking over bears primary responsibility, but the person handing over should also learn from the experience. If the accident is exacerbated due to the concealment of information, the person handing over duty bears full responsibility. 12 Inspection Tour System 12.1.1 Requirements for inspection tours 12.1.2 Strengthen inspection tours in accordance with the routes and contents specified. 12.1.3 The person on duty shall check once before taking over the shift, and once every hour after taking over. 12.1.4 Fill in the inspection details carefully and truthfully, and implement the labeling and re-labeling system. 12.1.5 When abnormal conditions are detected during inspections, it is necessary to contact the relevant personnel promptly, report to the team leader or the workshop, and take timely action to address them. 12.1.6 When there are problems with instruments or electrical equipment, it is necessary to notify the instrument technicians and electricians promptly so that they can handle the issue. 12.1.7 When problems occur with equipment, pipelines, or valves, they should be addressed promptly. If it is not possible to resolve the issue, it is necessary to report to the shift leader, duty supervisor, dispatcher, or workshop manager so that mechanical maintenance and relevant departments can handle it ； 12.1.8 The operator should promptly carry out preliminary treatment and protective measures. 12.1.9 Points to Note During Routine Inspections ； 12.1.9.1 Production and safety conditions ； 12.1.9.2 Control ranges for each process control point ； 12.1.9.3 Operation status of equipment and valves ； 12.1.9.4 Sealing condition of pipes and valves.
9.6.7 Preparation of NaClO solution: Take 100 kg of 12% NaClO solution (with a specific gravity of 1.05), add 100 kg of water to it, to obtain an approximately 6% NaClO solution. To add this solution, adjust the rotameter settings and calculate the required amount using the formula: Q1 (L/h) = 0.17Q2 (based on 10 mg/L). Here, Q1 is the amount of NaClO solution to be added, in L/h, and Q2 is the volume of brine to be treated, in m3/h. While adding the NaClO solution, monitor the free chlorine concentration in the brine entering the filter; an ideal range is 1 mg/L to 3 mg/L. Adjust the amount of NaClO solution added accordingly. 9.6.8 Operation of adding NaOH: Estimate the amount of NaOH to be added, and after checking whether the NaOH content in the brine is within the controlled range, adjust the rotor; generally, an electrolyte concentration of around 10% is used for NaOH. Measure the pH of the saline in the reaction tank before testing, and keep it between 10.5 and 12. The analysis shows that the NaOH content in the brine ranges from 0.1 g/L to 0.6 g/L. 9.6.9 Procedures for preparing Na2CO3 solution a) 125 kg of solid Na2CO3 is mixed with water to produce 1 m3 of solution, with a Na2CO3 concentration of 12.5 %. Weight of Na2CO3 (kg) = 125V, where: V is the volume of the Na2CO3 preparation tank, in m3. b) The electrolyte supplied for electrolysis is directly carbonated using CO2 gas. For the reaction with Na2CO3, estimate the amount of Na2CO3 to be added; after determining that the level of Na2CO3 in the brine is within the desired range, adjust the rotor and add Na2CO3 to the subsequent reaction tank. Ensure that the concentration of Na2CO3 in the brine entering the filter is between 0.2 g/L and 0.6 g/L. 9.6.10 Procedure for preparing Na2SO3 solution: Dissolve 5 kg of solid Na2SO3 in water to obtain 1 m3 of solution with a Na2SO3 concentration of 0.5%. Weight of Na2SO3 (kg) = 5V, where: V is the volume of the Na2SO3 preparation tank, in m3. For the reaction involving Na2SO3, the setting on the rotameter is adjusted according to the amount of free chlorine in the brine. The amount of Na2SO3 solution to be added is calculated using the following formula: Q1 (L/h) = 1 × Q2 (based on 5 mg/l). Here, Q1 represents the amount of Na2SO3 solution added, in L/h, while Q2 represents the volume of brine to be treated, in m3/h. 10 Abnormal conditions and their handling: Abnormal conditions that may occur during production and how to deal with them are outlined in Appendix D. 11 Shift handover: 11.1 The person taking over the shift should arrive at the post in advance and conduct a preliminary inspection along the designated route. After that, a pre-shift meeting is held, during which any issues identified during the preliminary inspection are discussed. The person handing over the shift then takes these concerns back to their team members so that they can address the problems promptly. 11.2 During shift handover, conduct the transfer carefully following the \"three ones\" principle (handing over item by item, one by one); the \"four senses\" principle (seeing, hearing, touching, smelling); and the \"five reports\" principle (reporting the item number, name, issues, measures, and current status). The person conducting the handover must create favorable conditions for the person leaving the shift. 11.3 The shift handovers assist each other in addressing major issues that arise during the handover process. 11.4 Strictly enforce the “Five Handovers” and “Five Non-Acceptances” system 11.4.1 The “Five Handovers” system: 11.4.1.1 Hand over production tasks and their completion status ； 11.4.1.2 Operating process conditions of the equipment and existing problems ； 11.4.1.3 Past quality and safety issues, and measures proposed to address them ； 11.4.1.4 Deliver all tools and equipment ； 11.4.1.5 Hand over record materials and equipment. 11.4.2 The “Five No-Acceptances” system: 11.4.2.1 Do not accept tasks if they have not been completed or issues have not been resolved as stipulated by the post responsibility system ； 11.4.2.2 Do not accept tasks if they are not completed and the reason is unknown ； 11.4.2.3 Quality and safety issues that remain unresolved or for which no corrective actions have been proposed will not be accepted ； 11.4.2.4 Tools and equipment that are lost or missing will not be replaced ； 11.4.2.5 Records that are incomplete or poor hygiene will result in rejection. 11.5 Accidents that occur during the handover process are the responsibility of the person handing over, while accidents that occur after the handover are the responsibility of the person taking over. In cases where it is unclear who is responsible, the person taking over bears primary responsibility, but the person handing over should also learn from the experience. If the accident is exacerbated due to the concealment of information, the person handing over duty bears full responsibility. 12 Inspection Tour System 12.1.1 Requirements for inspection tours 12.1.2 Strengthen inspection tours in accordance with the routes and contents specified. 12.1.3 The person on duty shall check once before taking over the shift, and once every hour after taking over. 12.1.4 Fill in the inspection details carefully and truthfully, and implement the labeling and re-labeling system. 12.1.5 When abnormal conditions are detected during inspections, it is necessary to contact the relevant personnel promptly, report to the team leader or the workshop, and take timely action to address them. 12.1.6 When there are problems with instruments or electrical equipment, it is necessary to notify the instrument technicians and electricians promptly so that they can handle the issue. 12.1.7 When problems occur with equipment, pipelines, or valves, they should be addressed promptly. If it is not possible to resolve the issue, it is necessary to report to the shift leader, duty supervisor, dispatcher, or workshop manager so that mechanical maintenance and relevant departments can handle it ； 12.1.8 The operator should promptly carry out preliminary treatment and protective measures. 12.1.9 Points to Note During Routine Inspections ； 12.1.9.1 Production and safety conditions ； 12.1.9.2 Control ranges for each process control point ； 12.1.9.3 Operation status of equipment and valves ； 12.1.9.4 Sealing condition of pipes and valves.
13 Safety Technologies and Labor Protection 13.1 Permissible Emission Standards for Toxic and Hazardous Substances 11.1.1 The pH value of wastewater discharged into the main drainage channel should be between 6 and 9. 11.1.2 The allowable concentration of suspended solids is not more than 200 mg/l. 11.1.3 The oil emission standard shall not exceed 10 mg/l. 13.2 Hazards to health caused by toxic and harmful substances 13.2.1 Caustic soda solutions are highly corrosive; when they come into contact with the skin, especially the mucous membranes, they can cause soft scabs to form and penetrate deep into the tissues ； Direct contact with the skin and eyes can cause burns, while accidental ingestion can lead to burns in the digestive tract, as well as mucosal erosion, bleeding, and shock. 13.2.2 Hydrochloric acid is corrosive to human skin; prolonged contact can cause severe ulcers, and its vapors are highly irritating to the eyes, nose, and trachea ； Accidental ingestion can cause burns to the digestive tract, mucosal erosion, bleeding, and shock. 13.3 Measures for preventing disasters and accidents 13.3.1 Equipment and pipelines in operation cannot be maintained; if maintenance is required, the system must be shut down first, and any remaining materials and residual pressure inside must be removed ； When maintaining pump machinery, the power supply must be disconnected and a “Do Not Close” sign must be placed. 13.3.2 When entering the equipment for maintenance or cleaning, at least two persons must work together, with one person staying at the manhole to supervise. 13.3.3 All storage tanks must be covered, and stairway handrails, equipment guardrails, and motor backwheel covers must be in good condition; any safety hazards identified must be eliminated promptly. 13.3.4 Instruments and electrical equipment shall be adjusted and maintained by professionals; other personnel are not allowed to touch them. 13.3.5 Strictly follow the process operation procedures and all relevant performance criteria. 13.3.6 Do not use wet hands or go without wearing rubber shoes to operate electrical switches; do not pile up miscellaneous items on the control panels, electrical equipment, or start switches ； Electrical faults must be handled by an electrician. When checking the motor temperature, one must use the back of the hand to avoid electric shock. 13.3.7 Operators of pressure vessels must have completed training in the operation of pressure pipelines and hold a ‘Pressure Pipeline Operation Permit’ before they can take up their duties. 13.3.8 The pipelines and oil/gas tanks involved in the operation of air compressors are under high pressure; some components generate high temperatures, while the electrical circuits are subject to high voltages. Therefore, it is necessary to keep the valves of the air compressor closed under normal circumstances. When performing maintenance on the pipelines, it is essential to ensure that the air within them has been completely removed and that the system is at zero pressure. It is strictly prohibited to repair equipment, pipelines, and valves under pressure. 13.3.9 Smoking is completely forbidden within the factory premises. 13.3.10 It is strictly prohibited to cause disturbances, sleep, engage in personal tasks, leave one’s post, or drink alcohol before or during the shift. 13.4 Methods for dealing with disasters 13.4.1 If electrical equipment catches fire, use a carbon tetrachloride or carbon dioxide fire extinguisher; water should not be used as it can cause electric shock. 13.4.2 In the event of severe leaks of sodium hydroxide or acids, the contaminated area should be isolated to restrict access ； In the event of a small leak, it can be flushed with large amounts of water; the diluted water can then be discharged into the wastewater system. 13.5 Personal protective equipment to be worn: During production operations, personal protective equipment must be worn as required. The necessary PPE includes work clothes, work shoes, safety helmets, acid- and alkali-resistant gloves, and protective goggles. 13.6 First aid measures for injuries 13.6.1 Direct contact of caustic soda and hydrochloric acid with the skin or eyes can cause burns. In the event of skin contact with caustic soda, remove the contaminated clothing immediately and rinse the affected area with plenty of flowing water; do not rub the area. In severe cases, seek medical attention at an emergency clinic. 13.6.2 In the event of eye contact with acids or bases, lift the eyelids immediately and rinse the eyes with plenty of flowing water; do not rub the eyes. In severe cases, seek medical attention at an emergency clinic. 13.6.3 Seek medical attention at the first aid station after being scalded by condensed water. 13.7 Environmental Hygiene 13.7.1 The discharge of alkali solutions and oils into sewers is strictly prohibited. 13.7.2 When the work area is contaminated by acids, alkalis, or salts, it should be rinsed clean with river water. 13.7.3 The operation site must be kept dry, with no standing water or waste present. 14 Maintenance of major equipment 14.1 Pumps and other equipment – Maintenance items, operating time, and maintenance contents: Pumps: Every shift (8 hours) 1. Start, operate, and shut down the pumps in strict accordance with the operating procedures, and keep records of their operation. 2. Check the lubrication status of all lubricated parts at the end of each shift; also check the exhaust temperature and pressure of the air compressor. 3. Regularly monitor the bearing temperature, which should not be higher than the ambient temperature by 35 degrees℃ ； Maximum temperature of bearings: Rolling bearings shall not exceed 75°C, and sliding bearings shall not exceed 65°C. Regularly check whether the pump pressure and motor current are normal and stable, as well as whether there are any abnormal noises or vibrations during operation; address any issues that arise promptly. 4. It is strictly prohibited to adjust the inlet valve to control flow rate in order to avoid cavitation. 5. The pump must not operate for extended periods at a flow rate lower than 30% of its designed value. 6. Keep the pump and its surrounding area clean at all times, and promptly fix any leaks or spills. The sealing meets the requirements. The pump has new bearings and has been in operation for 100 hours; it has been cleaned and its oil replaced. The storage tank is made of fiberglass. Operation time: 8 hours per shift. 1. The equipment’s exterior should be painted with anti-corrosion paint from time to time, as necessary, to prevent corrosion and rusting. 2. No other heavy objects or vibrating components beyond those specified in the design shall be placed on the container. 3. Contact between the container and open flames is prohibited. 4. The container should be inspected once a year after use. If leakage or seepage occurs during use, it must be stopped from being used immediately; the affected area should be cleaned with acetone, and after it dries, repairs should be carried out. The supplier should be notified promptly to provide repair methods. 14.2 Maintenance of HVDM membrane filters Maintenance tasks Operating time Maintenance details Filter bags: Every shift (8 hours) 1. The filter bags must not be contaminated by oil; oil-containing liquid must not be allowed to enter the filter. 2. After coming into contact with water, the filter bags must remain moist, and when the filter is shut down, the liquid level must stay above the tube sheet. 3. When the filter is shut down for an extended period (48 hours in summer, over 72 hours in winter), the water used to soak the filter bags should contain 10% NaClO to prevent the growth of bacteria and algae due to swelling. 4. If the filter liquid contains substances that can cause scaling on the filter bags, it is necessary to ensure that these scaling agents turn into solid forms before they enter the filter, thereby reducing scaling on the filter bags. 5. When scaling occurs on the filter bags, they must be cleaned regularly while the scale is not yet hard, in order to prevent the filter bags from breaking after they become hardened. 6. When there is no scaling on the filter bags, they should be cleaned when their filtering capacity drops to a level that can no longer meet the requirements of the production process. Controller: Every shift (8 hours) 1. The controller must be kept clean; no heavy objects should be placed on the control box. 2. The controller’s casing must not come into contact with organic solvents such as benzene, gasoline, chloroform, and propane. Pneumatic flexible valve: Every shift (8 hours) 1. If there is a large amount of gas in the exhaust pipe of the pneumatic flexible valve or if the valve is tightly closed, it indicates that the inner lining of the valve is damaged and leaking; in such cases, the machine must be stopped immediately for replacement. 2. Do not use large or irregular compressed air. 3. When replacing the inner tank, check the diamond-shaped seal strip; if it is damaged, replace it. Solenoid valve: per shift (8 hours) 1. This device uses a dual-control modular solenoid valve; such valves have a memory function – even after the electrical signal that triggers the valve to change position disappears, the valve remains in its current position. It is only when the electrical signal from the other side is applied that the valve changes direction. 2. It is necessary to ensure regular drainage from the air filter feeding the solenoid valve, as well as regular inspection of the oil mister, to prevent a shortage of oil. 14.3 Maintenance of Air Compressors Maintenance Tasks Operating Time Maintenance Content Air Compressor: Every shift (8 hours) 1. Drain the condensate water in the oil-gas tank before starting up. 2. Check and top up the lubricating oil in the oil-gas tank. 3. Check the exhaust temperature and pressure of the air compressor. 4. Check the loading and unloading pressures of the air compressor. 5. Adjust the water drainage at the outlet of the air compressor. Air Buffer Tank: Every shift (8 hours) Drain water from the bottom drain outlet once per shift. All Equipment: Every shift (8 hours) Clean the air inlet screen and the equipment. Air Compressor: Every 3 months (500 hours) 1. Clean the air filter. 2. Replace the lubricating oil and the oil filter element after 600 hours of operation for new machines. Air Compressor: After 2000 hours Replace the oil filter element. Air Compressor: After 3000 hours Replace the lubricating oil and air filter, as well as the oil-gas separator element. 15 Requirements for Filling Out Original Records 15.1.1 When filling out original records, it is necessary to ensure accuracy, timeliness, no alterations, no destruction, no fraud, no omissions, and no errors. After making the record, the recorder should sign. Proxy signing is not allowed. 15.1.2 Original records shall be kept in the prescribed chronological order; it is not allowed to record memories or predictions. Arriving early or 15 minutes late is considered a failure to record on time. 15.1.3 Original records shall be filled in with carbon or blue-black ink. The font should be SimSun, with clear handwriting and neat arrangement. 15.1.4 A diagonal line should be drawn in the space marked with a symbol for no data or no specified record. The diagonal direction is from the lower left corner to the upper right corner. If a single cell is blank, it is marked with a line; if multiple adjacent cells are blank, a diagonal line is drawn for that item. The blank spaces marked with a line can be filled in with concise words to describe the reason for no record, such as: parking, waiting for materials, etc. Blank spaces are not allowed, nor is it permissible to have both lines and filled-in data or the symbols specified for recording. 15.1.5 The surface of the recording paper must be clean and free from any alterations; if changes need to be made, they can only be done by drawing lines through the text, with a signature placed at the point of alteration. 15.1.6 The requirements for the format of original records are provided in Appendix E. 16 Storage and Use of Tools 16.1 Tools used at a particular position should be registered, and their specifications, models, and quantities should be handed over during shift changes. 16.2 Tools should be neatly placed in the tool box as specified. 16.3 Use tools properly; do not throw them around or strike them harshly to avoid damaging them. 16.4 In the event of abnormal damage or loss of tools, the responsible person or team shall be punished in accordance with relevant regulations. 17 Systems for the use and storage of fire-fighting equipment and protective gear 17.1 Fire-fighting equipment and facilities within the jurisdiction must be strictly managed, and it is strictly prohibited to use them for other purposes. 17.2 Fire-fighting equipment and facilities require the same level of inspection, maintenance, and handover as production equipment, in order to ensure their cleanliness and the integrity of other components; it is strictly prohibited to use fire-fighting equipment or activate its switch mechanisms outside of fire-fighting situations ； In the event of a fire, it must be reported to the safety officer promptly after normal use, so that it can be replaced in a timely manner. 17.3 Requirements for the maintenance, cleaning, and upkeep of fire hydrants and fire extinguishers. 17.3.1 Fire-fighting equipment should be placed at fixed locations that are dry, well-ventilated, and easily accessible; it must not be moved without permission, and storage in direct sunlight or in areas with high temperatures and humidity is strictly prohibited. 17.3.2 It is strictly prohibited to pile up miscellaneous items within 2 m of the fire hydrant, and the fire access roads must remain unobstructed. 17.3.3 Fire hydrants must be maintained regularly, and the valve covers should be greased to ensure they can open smoothly. 17.3.4 The surface of the fire hydrant must be kept clean, free of obvious stains and dust accumulation. 17.3.5 Only fire extinguishers may be placed in the fire extinguisher cabinet; no other items are allowed inside or outside it ； The fire extinguisher should be covered with a plastic bag to prevent corrosion. 17.4 Used fire-fighting equipment must not be discarded carelessly or left unattended, nor must it be damaged arbitrarily. 17.5 Usage of dry powder fire extinguishers: Pull out the pin of the extinguisher, aim it at the source of the fire, and press the switch.
Operating Procedures for Caustic Soda Production by Ion-Exchange Membrane Process – Part 2: Electrolysis 1 Scope This standard specifies the process flow for the electrolysis stage in caustic soda production using the ion-exchange membrane method, as well as the formats for the original records related to this stage. It defines the tasks involved, the organizational structure and coordination mechanisms, identifies the equipment under control, the production control parameters, the procedures for monitoring and inspection during operation, the aspects of daily management, the steps for starting up and shutting down the process, methods for handling faults, and the precautions necessary for safe production. This standard applies to the operation of caustic soda electrolysis processes using the ion-exchange membrane method. 2 Job Responsibilities The main tasks of this position are to feed the second-stage refined brine from the brine sump into the electrolyzer, to send the 32% alkali produced by electrolysis to the intermediate alkali storage tank, and to deliver the fresh brine generated by electrolysis to the dechlorination unit. 3 Production Organization and Coordination Relationships 3.1 Production Organization Shift workers are supervised by the factory management, workshop supervisors, and team leaders; production activities during a shift are carried out under the unified command of the factory’s shift supervisor and the company’s dispatch team. 3.2 Collaboration Relationships 3.2.1 The operators at the relevant positions maintain communication with those in charge of concentration and dechlorination processes, in order to keep track of the flow rate of the alkaline solution as well as the level of the alkaline solution in the intermediate tanks. 3.2.2 Contact the secondary brine purification unit to understand the quality of the purified brine and its flow rate. 4 Description of the production process and equipment under control 4.1 Description of the production process The refined secondary brine flows from the brine sump (D-170) into the electrolyzer (R-230) ； 32% alkali flows by gravity from the alkali solution high-level tank (D-273) due to the difference in elevation; after mixing with pure water, it enters the electrolytic cell (R-230). The 32% alkali generated then flows by gravity to the caustic soda tank (D-270), where it is transported by the alkali solution pump (P-274) to the caustic soda high-level tank (D-273) and the intermediate caustic soda storage tank (D-610). The brine generated flows by gravity into (D-260), and it is pumped by the brine pump (P-264) to the dechlorination tower (T-312). 4.2 Process Flow Diagram The process flow diagram for this position is shown in Appendix A. 4.3 Equipment under Management The list of equipment under the responsibility of this position is provided in Appendix B. 5 Production control indicators: The list of production control indicators for this position is provided in Appendix C. 6 Startup and Shutdown Procedures: 6.1 Preparation Work 6.1.1 Air displacement of the cathode system (refer to Figure D.1) 6.1.1.1 Before starting up, the cathode system should be displaced with nitrogen; generally, it takes more than 10 hours to completely displace the air from the system. This is an important step to prevent explosions in the hydrogen pipelines. After air displacement is complete, nitrogen continues to be injected to prevent pressure drops in the catholyte pipes and hydrogen pipelines until electrolysis begins. 6.1.1.2 Situations where air displacement is necessary: a) Before the first operation of the electrolysis equipment. b) When the electrolysis equipment is taken out of service for maintenance and before it is restarted. c) After a short period of downtime followed by restart. d) When welding work needs to be done on the hydrogen pipelines and before they are put back into use. 6.1.1.3 Formation and confirmation of the displacement pipeline: a) Close the hydrogen outlet valves 10 and 12. b) Open the hydrogen discharge valve 14. c) Close the caustic soda outlet valves 4 and 6. d) Open the discharge port (1) on the downstream side of the hydrogen pipeline. e) Manually open valves Q and R. f) Keep the liquid level in the catholyte tank (D-270) at 10%. 6.1.1.4 Degree of air displacement: a) Catholyte discharge tank: ① Inject pure water or caustic soda into (D-290) until the liquid level reaches 90%. ② Allow nitrogen to flow at a rate of 10 m3/h into (D-290) continuously until the procedures specified in 6.1.1.4 are completed. b) Catholyte circulation tank (D-270): ① Allow nitrogen to flow through at a rate of 50 Nm3/h for more than 20 minutes. ② Circuit: →(D-270)→Hydrogen pipeline→Discharge port (1). c) Catholyte outlet pipeline: ① Allow nitrogen to flow through at a reduced rate of 20 Nm3/h. ② Open valves 6 and 8, and close valve Q. ③ Allow nitrogen to flow through at 20 Nm3/h into (D-270) for more than 10 minutes. ④ Circuit: —→(D-270)—→NaOH pipeline—→Valve 6—→Valve 8—→Discharge port (2). d) Main hydrogen pipeline and pipelines above the catholyte circulation tank: ① Open valve 12, and ensure that valve 14 is also open ； ② Close valve 6 and valve 8 ； ③ Pass nitrogen through at a rate of 20 Nm3/h for 2 hours ； ④ At the same time, pass nitrogen through and inject it at 20 Nm3/h into outlet (2) ； ⑤ Loop: —→(D-270)—→hydrogen pipeline—→valve 12—→14—→exit (2) Loop: —→exit (2) ⑥ Sample nitrogen from valve 56 to determine the oxygen content. e) Hydrogen main pipelines and hydrogen treatment equipment: ① Open valves Q and S, and confirm that valve R and the outlet (1) are open ； ② Close valve 12 ； ③ Reduce the nitrogen flow rate to 5 Nm3/h and continue injecting ； ④ Increase the flow rate of nitrogen to 50 Nm3/h, and feed it into circuit D-270 ⑤: —→(D-270)—→hydrogen pipeline—→—→exit (1)—→—→exit (2). f) Circulation pipeline for the catholyte tank: ① Feed caustic soda into the catholyte tank through valve 84 until a concentration of 70% is achieved ； ② Next, in automatic mode, operation (P-274A/B) is initiated to start the caustic soda circulation via valve 86. g) Caustic soda concentration meter pipeline: Circulation is initiated via valve 44 and valve 48. 6.1.1.5 Confirmation of air displacement completion: Nitrogen is sampled from valve 56 and the sampling valve (valve P) at the exhaust port (1) to confirm that the O2/N2 ratio is below 1 %. 6.1.1.6 Continued nitrogen injection: Once the O2/N2 ratio falls below 1%, the flow rate of nitrogen injection can be reduced, until electrolysis begins. Loop: 10 Nm3/h → (D-270) → hydrogen pipeline → outlet (1); 5 Nm3/h → (D-290) → outlet (1); 1 Nm3/h → outlet (2). 6.1.1.7 Nitrogen injection when the electrolysis equipment is shut down for a short period of time within 24 hours: a) Inject nitrogen into D-270 at a rate of 10 Nm3/h ； Loop: —→(D-270)—→hydrogen pipeline —→ —→exit (1) b) Measure O2/N2 from valve P ； c) Confirm that O2/N2 is below 1 %. 6.1.2 Brine Circulation 6.1.2.1 Overview Before starting electrolytic operation, brine is circulated in the electrolyzer bypass circuit through bypass valve 85. Brine storage tank (brine process) → Primary brine storage tank → Primary brine pump → Brine filter → Filtered brine tank → Filtered brine pump → Ion exchange tower → High-level brine tank → Valve 85 → Diluted brine tank → Diluted brine pump → Dechlorination tower → Dechlorinated brine tank → Dechlorinated brine pump → Water distribution tank (brine process) 6.1.2.2 Preparation a) The main chlorine pipeline shall be opened manually (to prevent the formation of a closed system) ； b) Confirm that the chlorine main pipeline has been connected to the chlorine absorption tower ； c) Open the bypass valve 85 to the brackish water tank. Refer to the brine circulation circuit diagram 6.2 – Commissioning 6.2.1 Electrolyte injection (refer to Figure D.3). Before the electrolyzer starts operating, the electrolyte (caustic soda and brine) is injected into it. Fill the electrolyte completely up to the upper part of the electrolyzer. 6.2.1.1 Confirmation a) Status of the cathode system: The cathode system has been purged with nitrogen, and caustic soda is ready for injection ； b) Status of the anode system: Ready for saline injection ； c) Quality of saltwater: The quality of the refined saltwater meets the standards for secondary saltwater ； d) Electrolyte temperature: The ideal temperature for the electrolyte used in injection is above 55 °C. 6.2.1.2 Preparation a) Operation valves: Open 13, 17, and 21 of the anode system. Open 4, 10, 14, 18, 22 of the cathode system. b) Confirm the nitrogen flow rate: Set the nitrogen flow rate to 5 Nm3/h. c) Adjust oil pressure: Set the oil pressure to 7.5 MPa. d) Adjust the fixing position: Move the fixing nut about 20 mm away. 6.2.1.3 Injection of electrolyte a) Injection of NaOH: Open valve 38 to achieve a NaOH flow rate of 15 m3/h ； b) Injecting saline: Open valve 41 to achieve a saline flow rate of 15 m3/h ； Maintain the pressure difference in the tubular differential manometer at 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O). c) NaOH flow rate: After caustic soda overflows from the outlet pipe of the electrolyzer, reduce valve 38 to keep the NaOH flow rate at 5 m3/h ； d) Brine flow rate: After the brine overflows from the outlet pipe of the electrolyzer, reduce valve 41 to adjust the brine flow rate to 5 m3/h ； e) Stop injection: After NaOH overflows through valve 16, close valve 38; after brine overflows through valve 17, close valve 41 ； f) Run when appropriate: After the electrolyte injection is complete, although the electrolyzer can start operating, if starting it is delayed for certain reasons, keep valves 16 and 17 open. 6.2.2 Connection of the gas main, electrolyte circulation, and start of electrolysis operation. (See Figure D.3) 6.2.2.1 Verification a) Gas treatment equipment: The equipment for treating chlorine and hydrogen is either in operation or ready for operation b) Electrolyte injection into the electrolyzer: The electrolyte has been injected into the electrolyzer c) Purified brine equipment: The secondary brine is in circulation (Procedure 6.1.2.2) d) Rectifier equipment: The power supply preparation for the rectifier is complete ； e) Injection of nitrogen: When only one electrolyzer is in operation (that is, when the electrolyzers have all stopped and one starts operating), nitrogen is fed into D-270 via FI-279 at a rate of 50 m3/h, flowing toward the hydrogen main pipe ； f) Contact relevant departments: Reach out to the relevant departments to initiate operation and confirm that their preparatory work is complete. 6.2.2.2 Preparation for starting up a tank and connection of the main pipes a) Level gauge valves: Close valves 21 and 22 of the tubular differential pressure gauge b) Check oil pressure: Ensure that the oil pressure reaches 7.5 MPa c) Position fixing: Move the fixing nut by 20 mm d) Anode system pipes: Open valves 5 and 11 of the anode system, and close valves 13 and 17 ； e) Cathode system pipes: Open valves 4, 6, 10, 12 of the cathode system, and close valves 8, 14, 16. The next step is to continue with procedure 6.2.2.4. 6.2.2.3 When existing electrolyzers are in operation, preparation for bringing other electrolyzers online and connection to the gas main (when adding new units for operation): When existing electrolyzers are running, it is necessary to prevent any changes in pressure; when adding new units, they should be connected to the main at the same operating pressure. a) Level gauge valves: Close valves 21, 22 of the tubular differential pressure gauge ； b) Check oil pressure: Verify that the oil pressure reaches 7.5 MPa. c) Fix the position: Move the fixing nut by 20 mm. d) Check the nitrogen setting value: Set the control value using DCS to 0 kPa (0 mH2O), and verify it ； e) Verify nitrogen pressure: When the pressure on site is below 25 kPa (2.5 mH2O), verify the water level height of (DP-248). f) Connection of nitrogen pipelines: Connect the two hoses used for pressurization in the nitrogen pipeline connected to the electrolyzer to valve 55 and valve 56 ； g) Confirm operating pressure: Verify the gas pressure in the chlorine main pipe during operation, which is 20 kPa (2.0 mH2O) or 24 kPa (2.4 mH2O), with a pressure difference of 4 kPa (0.4 mH2O). h) Forming a channel: Anode system: Close valves 13 and 17; Cathode system: Open valves 4 and 10, close valves 14 and 16. i) Injecting nitrogen: Open valves 55 and 56, slowly open the nitrogen valve ； j) Nitrogen pressure increase: Use the DCS to gradually increase the set value to 20 kPa (2 mH2O). There should be good communication between DCS and the field, and excessive pressure must be avoided at all costs. k) Stop nitrogen: Close valves 55, 56 ； l) Connect the gas pipelines: While maintaining a pressure difference of 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O), slowly open valves 11 and 12 alternately ； m) Connect the liquid pipeline: While maintaining a pressure difference of 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O), slowly open valve 5 and valve 6. After all the liquid in the outlet main pipe has been drained, slowly open valves 5 and 6 fully. For the next step, proceed to procedure 6.2.2.4. 6.2.2.4 Circulation of the electrolyte: a) Prepare the saline solution: Use the DCS to manually close the anode fluid flow control valve, and open valves 1 and 3 (valve 1 is always open) ； b) Cathode flow adjustment: On-site, adjust the cathode flow control valve 2 to set the catholyte flow rate (FIZA-232) at approximately 19.6 m3/h ； c) Anode flow adjustment: Use the DCS to manually adjust the flow rate of the anode fluid flow control valve FICZA-231 to 8 m3/h ； d) Gas sampling tube at the anode solution inlet main pipe: Open the gas sampling valves 31 and 27 at the end of the anode solution inlet main pipe, and then check the flow of the electrolyte through the sight glass ； When the supply to the anode solution is stopped, the fluid level flowing through valve 5 decreases. 6.2.2.5 Start of electrolysis a) EDIA release: Release sequence ； b) Ground setting: Adjust the scale of the rectifier’s ground relay to ±40 V ； c) Compressor startup: Press the switch of the compressor ； d) Adjusting gas pressure: Set the hydrogen pressure regulator to process control mode (to maintain the pressure difference between hydrogen and chlorine, continue feeding nitrogen into D-270 at a rate of 50 Nm3/h). e) Increase the electrolytic current: Slowly increase the electrolytic current (at a rate of 0.5 kA/2.5 minutes) to 5.0 kA. Especially in the early stages of increasing the current, since the gas generation condition inside the electrolyzer is not stable and the pressure fluctuates, extra care is required when increasing the current to 2.0 kA ； f) Adjusting brine injection: Switch the anode solution flow control valve to process control mode ； g) Intermediate inspection: After the electrolysis current is increased to 5.0 kA, inspections and verifications must be carried out according to the following items ； ① Measure the voltage of each cell slot to check for any abnormalities in the voltage ； ② Are there any abnormalities in the flow condition of the elastic hoses at the cathode and anode outlets? ； ③ Are there any abnormalities in the flow of the material inside the elastic hose at the anode outlet (color, flow rate, flow condition)? ； ④ Check for any leakage of electrolyte and gas in the electrolyzer. h) Inject brackish water: Use the brackish water injection valve to manually inject the specified amount of brackish water, after which it switches to process control mode ； i) Injection of hydrochloric acid: Slowly inject hydrochloric acid manually using the hydrochloric acid injection valve. The rate is such that pH slowly changes from 4 to 2.5 within 1 hour. Next, switch to the process control mode. (The amount of hydrochloric acid added is determined to maintain the current efficiency of the membrane; therefore, when the current efficiency changes in the early stages of use of a new membrane, it is added in small amounts manually. During normal fluctuations in efficiency, it is controlled by the process control method). j) Increase the electrolytic current: Increase the electrolytic current to the set value at a specified rate ； k) Normalization of monitoring values: Once the current, voltage, and temperature have stabilized, adjust the scale of the grounding relay to ±20 V, and activate the interlock ； l) Fixed electrolyzer: Once the temperature at the catholyte outlet reaches the specified value of 85 ℃, after 2 hours, secure the fixing nut to maintain an oil pressure of 7.5 MPa ； m) Stop nitrogen injection: Once the electrolytic current exceeds 5 kA, stop injecting nitrogen (D-270). 6.2.3 Normal State and Procedure: After confirming that the cell slot voltage is normal, increase the gas pressure to the reference value and raise the current to the set value. That is, 20 kPa (2 mH2O), 24 kPa (2.4 mH2O), 4 kPa (0.4 mH2O). When the electrolyte temperature is low, its resistance is high, and it is not suitable to increase the current. At this point, the current should be increased gradually until the temperature rises and the voltage drops. 6.2.3.1 Pressurization of Cl2 and H2 a) Verify that the chlorine regulator is in automatic mode; b) Verify that the hydrogen regulator is in process control mode, adjusted based on the chlorine pressure plus the gas pressure difference ； c) Use a chlorine regulator to slowly increase the pressures of chlorine and hydrogen to the set reference values correctly ； Chlorine pressure: 0 kPa to 20 kPa (0 mH2O to 2.0 mH2O); Hydrogen pressure: 4 kPa to 24 kPa (0.4 mH2O to 2.4 mH2O). Gas pressure difference: 4 kPa (0.4 mH2O). Allowable membrane pressure difference: 7 kPa ± 1 kPa (0.7 mH2O ± 0.1 mH2O). 6.2.3.2 Gradual increase of current (1 kA stage) and items for inspection and adjustment: a) Gas pressure difference: 4 kPa (0.4 mH2O); b): 0; c) DC ammeter: d) Voltmeter: e) Chlorine pressure and hydrogen pressure: reference values; f): 85 ± 1 ℃ ； g) NaCl concentration: 18.1 %±0.5 % (205 g/L±7 g/L at 25 ℃) h) NaOH concentration: 32.2 %±0.2 % i) Electrolysis current (process control) j) Acidity at the anode solution outlet: within the specified range. 6.2.3.3 Adjustment of the oil pressure fixing nut: Once the temperature of the cathode solution outlet reaches 80 ℃, to facilitate quick fixation in emergency situations, the gap between the oil pressure fixing nut and the rear cover plate is adjusted to 1 mm–2 mm. 6.2.3.4 Fixing with the hydraulic fixing nut: Once the temperature of the electrolyte reaches the specified value (85 °C) or the temperature at the catholyte outlet remains stable for 2 hours, the movable cover is fixed using a hydraulic fixing nut. Maintain the oil pressure at 7.5 MPa. 6.2.3.5 Re-fixing of the hydraulic fixing nut – Sequence for re-fixing: a) 7.5 MPa b) Check the distance between the fixing nut and the rear cover plate ； c) Fix the movable cover with a set screw ； d) 7.5 MPa 6.2.3.6 Inspection of chlorine purity: If the chlorine purity is insufficient, inspect the pipes in the dechlorination process. 6.2.3.7 Check of hydrogen purity If the hydrogen purity is insufficient, inspect the pipelines in the hydrogen purification process. 6.2.3.8 Inspection of caustic soda quality: Be careful not to use caustic soda with too high a concentration (although the caustic soda concentrator is calibrated in advance, more analytical checks should be carried out during the initial stage of operation). Check items 6.2.3.6, 6.2.3.7, and 6.2.3.8 before the electrolysis process becomes stable. 6.3 Parking (refer to Figure D.3) 6.3.1 Overview 6.3.1.1 Standard procedure a) Verify fixation: Confirm that the fixing nuts of the hydraulic pressure device are secured; if not, secure them ； b) EDIZA release: Release interlock ； c) Nitrogen increment: Increase the nitrogen flow rate to the exhaust outlet (2) to 20 m3/h ； d) Stop injecting hydrochloric acid: cease the injection of hydrochloric acid into the anode solution ； e) Stop the electrolytic current: After the electrolytic current becomes 0, turn off the switch of the rectifier ； f) Stop injecting pure water: Once all rectifiers have stopped operating, cease the injection of pure water ； g) Nitrogen purging: After the rectifier stops operating, to prevent air from mixing into the hydrogen main pipeline, nitrogen is injected into (D-270) ； h) Replace the chlorine pipeline: As required, pump the chlorine from the main chlorine pipeline into the chlorine removal tower ； i) Gas displacement in the cell: To displace the residual gas inside the electrolyzer, continue to inject the anode solution and cathode solution into the electrolyzer for 15 minutes ； j) Stop feeding the electrolyte: cease injecting the anode solution and cathode solution into the electrolytic cell ； k) Reduce gas pressure: Lower the gas pressure in the anode chamber and the cathode chamber ； l) Displacing residual gas: Injecting the electrolyte into the anode chamber and cathode chamber to completely displace the gas in the main pipes and separators on both sides ； m) Discharge of electrolyte: Discharge the electrolyte from the anode chamber and the cathode chamber ； n) Clean the inside of the electrolyzer with pure water ； o) Wetting the membrane: During long periods of downtime, wet the membrane with pure water once a week to prevent it from drying out. 6.3.1.2 Treatment of the electrolyzer after shutdown – Discharging the electrolyte and cleaning the electrolyzer (× = not performed, ○ = performed) Duration of shutdown: Within 2 hours, More than 2 hours, More than one week Remarks: Discharging the electrolyte (anode solution and cathode solution) × ○ ○ ① Cleaning the electrolyzer (immediately after discharging the electrolyte) × ○ ○ ② Wetting the membrane (once a week) × × ○ ③ Maintaining a level of pure water in the pipes (at the inlet main pipe and hoses) × ○ ○ ④ Remarks: ① If the electrolyzer is expected to be shut down for more than 2 hours, the electrolyte inside it should be discharged promptly after shutdown. ② During maintenance, when the electrolyzer frame needs to be removed, the electrolyte must be discharged first, followed by cleaning the electrolyzer twice ； ③ To prevent the membrane from drying out, it needs to be wetted once a week ； ④ To prevent the membrane from drying out, pure water is injected to reach a water level of 1/2 of the height in both the inlet main pipes and the inlet flexible hoses ； Procedure: After completely draining the pure water from the electrolyte tank (or wetting membrane), refill it with pure water to the specified level, and then drain the pure water completely. 6.3.2 Planned shutdown of the electrolyzer (refer to Figure D.3) 6.3.2.1 Overview a) Verify fixation: Confirm that the fixing nuts of the hydraulic pressure device are secured; if not, secure them. Maintain the oil pressure at 7.5 MPa ； b) EDIZA removal: Remove the EDIZA linkage ； c) Nitrogen increment: Increase the nitrogen flow rate to the exhaust outlet (2) to 20 m3/h ； d) Adjust the pressure of the pest control system: Adjust the pressure of the chlorine absorption system to -2 kPa (-200 mmH2O) ； e) DP-234 nitrogen flow rate: Nitrogen is injected into the water seal (DP-234) at a rate of 30 m3/h via FI-234. 6.3.2.2 Stop the electrolytic current and stop feeding the electrolyte a) Stop feeding hydrochloric acid: Reduce the valve for feeding hydrochloric acid to 0 to cease its injection. Valves 33, 35 that are closed on-site after shutdown ； b) Reduce the electrolysis current: Slowly lower the electrolysis current to 3 kA. c) Adjust the gas pressure: As needed, switch the chlorine pressure control valve and the hydrogen pressure control valve to manual mode ； d) Stop the electrolytic current: Reduce the electrolytic current to 0, and then turn off the switch of the rectifier. e) Purging the cathode with nitrogen: After the rectifier is completely stopped, to prevent air from mixing into the hydrogen pipeline, nitrogen is injected at a rate of 50 m3/h (D-270) ； f) Replace the anode air: Connect the chlorine main pipeline to the chlorine absorption pipeline as needed to absorb air and effect replacement ； g) Maintain the electrolyzer pressure difference: Keep the pressure difference between 2 kPa and 10 kPa (0.2 mH2O to 1.0 mH2O) ； h) Stop injecting pure water: Close the adjustment valve for pure water injection into the electrolyzer ； i) Continue injecting electrolyte: To displace the residual gases in the electrolyzer, continue to pour anode solution and cathode solution into the electrolyzer for 15 minutes ； j) Close valves 27, 31 of the gas extraction pipeline in the anode solution inlet main pipe. 6.3.2.3 Stop injecting electrolyte and separate the electrolyzer a) Separation inlet pipeline: Close valve 3 of the anode system, close valve 2 of the cathode system ； b) Separate outlet pipeline: Close valve 5 of the anode system, close valves 4 and 6 of the cathode system, open valve 8 ； c) Isolate the gas pipelines: Close valve 11 of the anode system and close valve 12 of the cathode system. 6.3.2.4 Reducing gas pressure a) Connect the exhaust pipeline: Maintain the pressure difference across the membrane at 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O), and slowly open valve 13 of the anode system and valve 14 of the cathode system ； b) H2 pipeline: After the pressure in the cathode chamber decreases and after confirming that valve 18 is closed, open valve 16 and inject nitrogen into the main catholyte outlet pipe at a rate of 30 m3/h ； c) Chlorine pipeline: Using the procedure described in a) above, the (chlorine) from the anode chamber is sent to the chlorine absorption tower via valve 13 ； d) Reduce nitrogen flow: Decrease the nitrogen flow passing through the exhaust port (2) to 1 m3/h. 6.3.2.5 Displacement gas (injecting electrolyte into the outlet manifolds on both pole sides) a) Cathode pipeline: Open valve 18 of the cathode system and close valve 10 ； b) Injection of cathode solution: Open valve 38 of the cathode system to allow caustic soda to be injected at a rate of 5 m3/h ； c) Injection of anode solution: Open valve 41 of the anode system to allow brine to be injected at a rate of 5 m3/h ； d) Stop the cathode solution: After overflow from valve 16 in the cathode system, close valve 38 ； e) Stop the anode solution: After overflow from valve 17 in the anode system, close valve 41. 6.3.3 Discharge of electrolyte (see D.3) 6.3.3.1 Preparation a) Confirm the discharge tanks: Verify the two electrolyte discharge tanks (D-280), (D-290) ； b) Discharge tank valve: Confirm that the inlet valve 81 of the anode solution discharge tank is open and the drain valve 71 is closed ； Confirm that the inlet valve 80 of the catholyte discharge tank is open and the drain valve 70 is closed ； c) Verify nitrogen flow rate: Confirm that the amount of nitrogen injected into the catholyte discharge tank (D-290) via FI-299 is 5 m3/h ； d) Verify nitrogen flow rate: Confirm that the amount of nitrogen injected into the water seal (DP-234) via FI-234 is 30 m3/h ； e) Cathode system pipes: Close valve 18 of the cathode system, and open valves 8, 14, 16 ； f) Anode system pipes: Open valve 17 of the anode system and close valve 13. 6.3.3.2 Discharging the electrolyte a) Level gauge valves: Open valves 21 and 22 of the tubular differential pressure level gauge ； b) Discharge of outlet liquids: Open the discharge valves 29 and 30 for the anode and cathode fluids, then close valves 29 and 30 after 5 minutes. c) Discharge from within the electrolyzer (liquid): Slightly open the discharge valves 23, 24 for the anode and cathode fluids ； d) Adjusting the discharge volume: Adjust the discharge valves 23 and 24 for the anode and cathode fluids, ensure that nitrogen is discharged from the water seal (DP-234), and maintain the membrane pressure difference in the tubular differential pressure level system at 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O) ； e) Discharge completion: When the pressure in the inlet manifolds on both poles is 0, and the membrane pressure difference in the tubular differential pressure level system is also close to 0, close the discharge valves 23 and 24 ； f) Reduce nitrogen flow: Instruct FI-234 to reduce the nitrogen flow into the water seal (DP-234) to 5 m3/h. 6.3.4 Cleaning the electrolyzer and membrane (refer to D.3) 6.3.4.1 Preparation a) Pure water pump: Operate the pure water pump ； b) Verify the pipelines: Open valve 17 of the anode system, and open valves 8, 14, 16, and 18 of the cathode system. Form channels to the discharge ditch as needed (close valves 70, 80, open valves 71, 81) ； 6.3.4.2 First cleaning a) Check the level gauge valves: Verify that valves 21 and 22 of the tubular differential pressure level gauge are open ； b) Start injecting pure water: Maintain the membrane pressure difference at 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O), and open valves 32 and 31. 15 m3/h, 15 m3/h. c) Adjusting pure water injection: After pure water overflows from the electrolyzer, adjust valves 32 and 31 to reduce the flow rate of pure water. 5 m3/h, 5 m3/h. d) Stop injecting pure water: After pure water overflows from each of valves 16 and 17, close valves 32 and 31 ； e) Maintain nitrogen injection: To inject nitrogen into the cathode chamber in order to press the membrane against the anode side, close valve 18 and increase the nitrogen flow rate to the water seal injector (DP-232) via FI-234 to 30 m3/h ； f) Discharge of outlet liquid: Open the valves 29 and 30 for the anode and cathode respectively; after 5 minutes, close valves 29 and 30 ； g) Discharging the liquid from the electrolyzer: Slightly open the discharge valves 23, 24 for the anode and cathode fluids ； h) Adjusting the discharge volume: Adjust the discharge valves 23 and 24 for the anode and cathode fluids to maintain nitrogen flow to the water seal (DP-234), and keep the membrane pressure difference in the tubular differential pressure level system between 2 kPa and 10 kPa (0.2 mH2O to 1.0 mH2O) ； i) Discharge completion: When the pressure in the inlet manifolds on both poles is 0 and the membrane pressure difference in the tubular differential pressure level system is also close to 0, close the discharge valves 23 and 24 ； j) Reduce nitrogen flow rate: Use FI-234 to reduce the nitrogen flow rate into the water seal (DP-234) to 5 m3/h. 6.3.4.3 Second washing → Same as the first washing in 6.3.4.2 above. 6.3.4.4 Wait for operation to resume a) Prevent drying: Until it is decided whether to remove the electrolyzer frame, pure water is injected through valves 32 and 31 to reach a water level of 1/2 of the height of the inlet flexible hose ； b) Shutdown procedure: Anode chamber —→ Connect to the chlorine absorption tower to pump in air; Cathode chamber —→ Pressurize with nitrogen. Open valves —→ Anode system valves 13, 17; Cathode system valves 8, 14, 16, 60, 62 (FI-234 supplies nitrogen at 5 m3/h). Close valves —→ Cathode system valve 18. 6.3.5 Wetting membrane (refer to D.3) 6.3.5.1 Preparation a) Verify nitrogen injection: Confirm that the flow rate of nitrogen injected into the water seal (DP-234) is 5 m3/h ； b) Confirm the pipelines: Valve 17 of the anode system is open, and valves 8, 14, 16, and 18 of the cathode system are open. 6.3.5.2 Wetting a) Verify the level gauge valves: Ensure that valves 21 and 22 of the tubular differential pressure level gauge are open ； b) Start injecting pure water: Maintain the membrane pressure difference at 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O), and open valves 32 and 31. 15 m3/h 15 m3/h ； c) Stop injecting pure water: After pure water overflows from the electrolyzer, close valves 32 and 31 ； d) Maintain nitrogen injection: To inject nitrogen into the cathode chamber in order to press the membrane against the anode side, close valve 18 and increase the nitrogen flow rate to the water seal injector (DP-234) via FI-234 to 30 m3/h ； e) Discharge of the outlet liquid: Open the valves 29 and 30 for the anode and cathode respectively; after 5 minutes, close valves 29 and 30 ； f) Discharging the liquid from the electrolyzer: Slightly open the discharge valves 23, 24 for the anode and cathode fluids ； g) Adjusting the discharge volume: Adjust the discharge valves 23 and 24 for the anode and cathode fluids to maintain nitrogen emission from the water seal, and keep the membrane pressure difference in the tubular differential pressure level system between 2 kPa and 10 kPa (0.2 mH2O to 1.0 mH2O) ； h) Completion of drainage: When the pressure in the inlet manifolds on both poles is 0, and the membrane pressure difference in the tubular differential level system is also close to 0, close the drain valves 23 and 24 ； i) Reduce nitrogen flow rate: Use FI-234 to lower the nitrogen flow rate into the water seal (DP-234) to 5 m3/h. j) During the waiting period, the remaining tasks shall be carried out in accordance with procedure 6.3.4.4 described earlier. 6.3.6 Emergency shutdown (refer to Figure D.3) The emergency shutdown of the electrolyzer is carried out through an interlock system. The reason for the shutdown is confirmed using the alarm panel in the control room. 6.3.6.1 All electrolyzers cease operation. 6.3.6.1.1 The pump operation status, such as (P-154), (P-264), and (P-274), continues to operate. a) Maintain membrane pressure difference: Keep the gas pressure difference at 2 kPa to 5 kPa (0.2 mH2O to 0.5 mH2O) ； —→Nitrogen is injected to keep the cathode system pressurized. Connected to the chlorine absorption tower to maintain reduced pressure in the anode system. b) Confirm the fixing position: Check the location of the fixing nuts on the electrolyzer; if it isn’t fixed yet, do so immediately, with a hydraulic pressure of 7.5 MPa ； c) All electrolyzers stop operating: —→ Proceed in accordance with the aforementioned procedure 6.3.3.2 for planned shutdown of electrolyzers. ① Stop injecting hydrochloric acid: It is automatically shut off by the interlock system. Close the front and rear valves 33, 35 ； ② Adjust gas pressure difference: Maintain the membrane pressure difference as specified in item a) above ； ③ Stop pure water injection: Close the pure water injection control valve ； ④ Circulating electrolyte: To displace the residual gases in the electrolyzer, continue to inject the anode solution and cathode solution into the electrolyzer for 15 minutes ； ——Wait in this state before running again. However, when the shutdown time is expected to be over 2 hours, it is necessary to carry out the procedure of draining the electrolyte and cleaning the electrolyzer and membrane. ⑤ Stop injecting the electrolyte and separate the electrolyzer: Refer to procedure 6.3.2.3 mentioned earlier ； ⑥ Replacement gas: Refer to the aforementioned procedure 6.3.2.5 ； ⑦ Discharge of electrolyte: Refer to the procedure 6.3.3 mentioned earlier ； ⑧ Wash the electrolyzer and membrane: Follow procedure 6.3.4 mentioned earlier. 6.3.6.1.2 Conditions where the pump stops (P-154), (P-264), (P-274), etc. stop: a) Maintain the membrane pressure difference: Keep the gas pressure difference at 2 kPa～5 kPa (0.2 mH2O～0.5 mH2O) ； —→Nitrogen is injected to keep the cathode system pressurized. Connected to the chlorine absorption tower to maintain reduced pressure in the anode system. b) Confirm the fixed position: Verify the location of the fixing nuts of the electrolyzer. If not secured, please secure it; the oil pressure should be 7.5 MPa ； c) All electrolyzers cease operation: The following is carried out in accordance with the aforementioned procedure 6.3.2.2 for planned shutdown of electrolyzers. ① Stop injecting hydrochloric acid: It is automatically shut off by the interlock system, which closes valves 33 and 35 before and after ； ② Adjust gas pressure difference: Maintain the membrane pressure difference as specified in item a) above ； ③ Stop pure water injection: Close the pure water injection control valve ； ④ Injecting pure water into the electrolyzer: To displace the residual gases in the electrolyzer, open the pure water valves 32 and 31 and inject pure water until it overflows from the electrolyzer. Wait in this state before running again. However, when the shutdown time is expected to be over 2 hours, it is necessary to carry out the procedure of draining the electrolyte and cleaning the electrolyzer and membrane. ⑤ Stop injecting the electrolyte and separate the electrolyzer —→ Refer to procedure 6.3.2.3 mentioned earlier ； ⑥ Replacement gas: Refer to the aforementioned procedure 6.3.2.5 ； ⑦ Discharge of electrolyte: Refer to the procedure 6.3.3 mentioned earlier ； ⑧ Wash the electrolyzer and membrane: Follow procedure 6.3.4 mentioned earlier. 6.3.6.2 When a single electrolyzer is shut down, the procedure outlined in 6.3.6.1.1 above shall be followed. Note: The nitrogen flow rate specified in this manual is given in Appendix E. Based on the nitrogen supply capacity, the injection volume and time can be adjusted accordingly. 6.4 Normal operation of the electrolyzer: Refer to 6.6 for standard operating conditions. 6.4.1 Adjustment of electrolysis load The maximum current supplied to the electrolyzer is 10.8 kA (4.0 kA/m2). The maximum operating value set on the control panel is 10.0 kA; the level for an extreme alarm is 10.5 kA, at which point the interlock device activates, while the level for a high alarm is 10.2 kA. 6.4.1.1 Normal operation a) Check the following items every 4 hours: ① EDIZA-230: Should be in a stable state near 0 (interlock connection) ； ② DC ammeter: Set the current to a stable level ； ③ Voltmeter: In a stable state b) The voltage of each cell slot should be measured weekly and whenever there is a change in operation. In other aspects, when an abnormality in the electrolyzer is anticipated, it is necessary to measure the voltage of each individual cell. ① Voltage measurement point: Due to the position of the flexible hose at the outlet of the natural circulation tank, the measurement is taken at the screw mounting location at the lower part of the unit tank ； ② Record voltage: Read the voltage value from the small voltmeter and make a record of it. 6.4.1.2 Changing current 6.4.1.2.1 Disabling EDIZA interlocking ； 6.4.1.2.2 Confirm the following items: a) Pressure difference: Pressure difference in the inlet main = (7±1) kPa (0.7 mH2O±0.1 mH2O); b) Voltage difference: Stable around 0 ； c) Direct current: Stabilized at the set value ； d) Voltmeter: Stable ； e) Chlorine pressure: stabilized at = 20 kPa (2.0 mH2O) ； f) Hydrogen pressure: stabilized at = 24 kPa (2.4 mH2O) ； g) Catholyte outlet temperature: ≤ 88 ℃ ； h) Anode solution outlet concentration: =18.1 %±0.5 % (205 g/L±7 g/L at 25 ℃) ； i) Concentration at the catholyte outlet: =32.2 %±0.2 % 6.4.2 Adjustment of the electrolyte flow rate 6.4.2.1 Checking the flow rates of the anolyte and catholyte Check the flow rates of the anolyte and catholyte every 1 hour. 6.4.2.2 Adjusting the anolyte flow rate Make adjustments when the flow rate deviates from the set value that is proportional to the direct current electrolysis current. FICA-231 is proportional to the direct current electrolysis current. 6.4.2.3 Adjusting the flow rate of the cathode solution: Make adjustments when the flow rate deviates from the set value. =19.6 m3/h 6.4.2.4 Check the flow condition of the outlet flexible hose. Conduct a visual inspection of the outlet flexible hose every hour; once any abnormalities are detected, take action accordingly. 6.4.3 Adjusting the pressure difference 6.4.3.1 Verifying gas pressure and gas pressure difference Check the chlorine pressure, hydrogen pressure, and the value of the pressure difference every hour. Chlorine pressure: = 20 kPa (2.0 mH2O) Hydrogen pressure: = 24 kPa (2.4 mH2O) Pressure difference: = 4 kPa (0.4 mH2O) 6.4.3.2 Adjusting gas pressures and pressure differences Adjustments are made when the pressures deviate from the set values. Using the chlorine pressure as a basis, process control is employed to regulate the hydrogen pressure. 6.4.4 Adjusting temperature The temperature of the catholyte in the electrolyzer is adjusted by the flow rate of cooling water in the heat exchanger installed in the catholyte circulation system. 6.4.4.1 Verify the temperature of the catholyte: Check the temperature at the catholyte outlet every hour. Catholyte outlet temperature: ≤ 88 ℃ 6.4.4.2 Adjusting the catholyte temperature Set the setting value of the temperature recorder as the reference value. 6.4.5 Adjusting the electrolyte concentration 6.4.5.1 Anode solution concentration The concentration of the anode solution is adjusted by controlling the supply volume of refined brine, and it is controlled by process control based on the direct current electrolysis current. 6.4.5.1.1 Verify the concentration at the anode solution outlet: Check the sodium chloride concentration at the outlet of the anode solution every hour ； Anode solution outlet concentration: =18.1 %±0.5 % (205 g/L±7 g/L at 25 ℃) 6.4.5.1.2 Adjusting the anode solution outlet concentration When the anode solution outlet concentration deviates from the set value, the set value is changed to adjust the concentration at the anode solution outlet of the electrolyzer to within the specified range. Anode solution outlet concentration: = 18.1 % ± 0.5 % (205 g/L ± 7 g/L at 25 ℃). 6.4.5.1.3 Regular analysis of the anode solution outlet concentration – The sodium chloride concentration in the anode solution outlet is analyzed daily, and this value is compared with the set value; adjustments are made when there is a significant difference. 6.4.5.2 Catholyte Concentration The concentration of the catholyte is automatically adjusted based on the flow rate of pure water injected into the catholyte circulation system at the inlet of the electrolyzer. The pure water flow rate is adjusted through process control based on the combined direct current electrolysis current and the concentration of the catholyte solution. a) Adjust the outlet concentration of the catholyte: Set the calibration value of the catholyte concentration meter to the reference value, and adjust the concentration of the catholyte. Catholyte concentration = 32.2 % ± 0.2 %. b) Regularly analyze the concentration at the catholyte outlet; measure the NaOH concentration at the catholyte outlet daily and compare it with the set value; if there is a significant difference, adjust the DRA-274. 6.4.6 Fixed Electrolyzer 6.4.6.1 Overview 6.4.6.1.1 Normal Condition The electrolyzer is fixed using fixing nuts, and the oil pressure in the actuation cylinder is maintained at 7.5 MPa. 6.4.6.1.2 Purpose of fixing the electrolyzer The purpose of fixation is to prevent the electrolyzer from being subjected to excessive pressure during an emergency stop. Excessive pressure can cause the gaskets and membranes to break, leading to hydrogen and chlorine leaking between the unit cells and potentially causing a fire. 6.4.6.1.3 Maintaining oil pressure when temperature drops: After fixing the electrolyzer with an oil pressure of 7.5 MPa, if the temperature drops by more than 5 °C, there is a possibility of electrolyte, hydrogen, and chlorine leaking from the gaps between the unit cells and the gaskets. These leaks, when exposed to sources of ignition such as electrical short circuits and static electricity, have the potential to cause fires. Therefore, when the temperature of the electrolyzer drops by more than 5 °C, the oil pressure must be maintained at 7.5 MPa. 6.4.6.1.4 Re-applying pressure: If the gasket has been in use for a long time, it gradually deforms and shrinks; therefore, it is necessary to reapply pressure and re-fix it periodically. 6.4.6.2 Fixed electrolyzer 6.4.6.2.1 Check the electrolyzer temperature Check the temperature of the thermometer for the catholyte temperature. 6.4.6.2.2 Adjust the position of the fixing nut Once the catholyte temperature reaches the normal level, reduce the distance between the fixing nut and its position to 1 mm–2 mm. 6.4.6.2.3 Fixing of the fixing nut: Two hours after the catholyte temperature reaches its normal level, the fixing nut is secured using an oil pressure of 7.5 MPa. 6.4.6.2.4 When the electrolyzer temperature drops, maintain the oil pressure at 7.5 MPa. When the set screw is moved away from its normal position, bring it to a position approximately 1 mm to 2 mm away. 6.4.6.2.5 Re-pressurization during the initial first week: During the initial first week, the electrolyzer must be re-pressurized and re-secured on a daily basis. 6.4.6.2.6 Re-pressurization during the first month: During the initial first month, the electrolyzer must be re-pressurized and re-secured on a weekly basis. 6.4.6.2.7 Subsequent monthly repressurization: After 2 months, the electrolyzer is repressurized and resecured once a month. 6.5 Operation of hydraulic equipment Generally, after a hydraulic system is put into operation, it is necessary to set the pressure properly and carry out appropriate adjustment and management. Hydraulic equipment includes: an oil pump (oil supply device), an oil circuit control plate, and hydraulic cylinders. 6.5.1 Operation of the oil pump and adjustment of main pressure 6.5.1.1 Check the oil level in the tank: Verify the level of oil in the tank; if it is low, add oil as appropriate ； 6.5.1.2 Confirm the switch valves: Ensure that all switch valves on the oil circuit control panel are in the retracted position (the valves before and after the filter, as well as the valve at the inlet of the oil circuit control panel, are open). 6.5.1.3 Safety verification: Verify that there is no one inside the electrolyzer ； 6.5.1.4 Oil pump operation: Start the oil pump of the oil supply unit ； 6.5.1.5 Adjustment of the safety valve of the oil supply device: a) Increase the pressure of the oil pump to 10.5 MPa～11 MPa ； b) Adjust the safety valve of the fuel supply device to the set value = 10 MPa ； c) Tighten the fixing nut of the safety valve on the fuel supply device. 6.5.1.6 Adjusting the output pressure of the oil pump: a) The pressure of the oil pump is gradually reduced until it reaches the set value of 9 MPa ； b) Tighten the fixing nut of the pressure control valve for the oil pump. 6.5.1.7 Pass cooling water through the oil cooler to adjust the oil temperature. Set value = below 60 ℃. 6.5.2 Adjustment of valves related to the oil circuit control plate 6.5.2.1 Preparation for adjustment work a) Set the switching valve to the forward position, and ensure that when the movable cover is extended to its maximum extent, it does not touch the unit groove ； b) Once the unit slot has been installed, verify that the guide rails of the unit slot bracket are in proper contact with the side panels ； 6.5.2.2 Removing air from the discharge cylinder a) Close the pressure relief valve ； b) Repeat the operation of moving the switch valve forward and backward several times. 6.5.2.3 Adjusting the flow control valve a) Open the pressure relief valve and adjust the operating pressure to 7.5 MPa ； b) Adjust the flow control valve so that the moving speed of the movable cover plate is set according to the reference value. Moving speed reference value = approximately 40 cm/min ； c) After adjusting the flow control valve, secure the fixing nut. 6.5.2.4 Adjustment of the safety valve a) Slightly close the pressure control valve to adjust the operating pressure and cylinder pressure to 8 MPa ； b) Turn the safety valve on and off several times, and by listening for the sound of oil leakage, confirm that 8 MPa corresponds to the location where the oil is leaking ； c) After adjusting the safety valve, secure the fixing nut. 6.5.2.5 Setting of normal operating conditions a) Adjust the pressure control valve to set the operating pressure at 7.5 MPa ； b) For safety, position the switch valve in the reverse direction and secure it. 6.5.3 Operation of oil pressure: At each operating stage, the oil pressure in the cylinder is adjusted to the specified value using the pressure control valve on the oil circuit control panel. 6.5.3.1 During maintenance operations on the electrolyzer: 1 MPa or 7.5 MPa 6.5.3.2 During membrane leakage inspection: 7.5 MPa 6.5.3.3 During electrolyzer leakage inspection: 7.5 MPa 6.5.3.4 During electrolyte circulation: 7.5 MPa 6.5.3.5 At the start of operation: 7.5 MPa 6.5.3.6 During normal operation: 7.5 MPa a) When not fixed: 7.5 MPa; maintain an oil pressure of 7.5 MPa until the electrolyzer is secured ； b) After the electrolyzer temperature reaches stability: 7.5 MPa ； If the electrolyzer temperature remains close to a constant value (±5 ℃), reduce the gap at the fixed nut to 1 mm–2 mm. c) After fixing: 7.5 MPa – After the electrolyzer temperature has stabilized for two hours, the fixing nuts are tightened, with the oil pressure maintained at 7.5 MPa. 6.5.3.7 After the fixing nut is secured, when operation is stopped (including emergency shutdown), it is not a problem for the hydraulic pressure system to cease operating ； 6.5.3.8 Before fixing the nut, when stopping operation (including emergency stop), it is necessary to immediately verify that the oil pressure is at 7.5 MPa ； 6.5.3.9 Before fixing the fixing nut, stop the power supply to the oil pump and immediately fix the fixing nut ； 6.5.3.10 Every hour, verify the following items: a) Main oil pressure: 9 MPa ； b) Oil temperature: below 60 ℃ ； c) Oil level in the oil tank: within the specified range ； d) Nut position: fixed, unfixed, or with a gap of 1 mm to 2 mm ； e) Operating pressure of the oil circuit control plate: 7.5 MPa. The oil circuit control panel includes: a flow control valve, a pressure control valve, a switching valve, a check valve, a safety valve, a pressure gauge valve, a pressure gauge, a switch valve, an operating lever, and fixing fixtures. 6.5.4 Management of oil supply: The switching valve on the oil circuit control panel allows the direction of oil flow to be changed from forward to backward through operation. During the operation of the electrolyzer, the oil flows in the forward direction; when the electrolyzer is disassembled for maintenance, it must flow in the reverse direction. Do not place the switch valve in the neutral position. The reason is to prevent danger caused by internal leakage in the oil circuit control plate and the operation check valve over time. 6.6 Standard operating conditions for the electrolysis station The standard operating conditions for the electrolysis station are listed in Appendix F. 6.7 Membrane Leak Inspection (Refer to Figure D.3) 6.7.1 Overview Membrane leak inspection is carried out to determine whether there are any pinholes or damages in the membrane. This leakage test is conducted with the anode chamber emptied, nitrogen is introduced into the cathode chamber to increase the pressure, and then the nitrogen that leaks through the membrane is measured. When the leakage rate through the membrane exceeds the specified limit, the membrane should be repaired or replaced with a new one. Leak checks of the membrane should be conducted in the following situations: a) when the membrane is installed (when a new membrane is installed, when the membrane is replaced, or when the gasket is replaced), b) before operating an empty electrolyzer ； c) When membrane leakage is suspected ； d) Perform a membrane leak check before removing all membranes. 6.7.2 Preparation for membrane leakage inspection (refer to Figure D.3) 6.7.2.1 Remove the wires of EDIZA-230 (only perform when moving it as a whole) ； 6.7.2.2 Open the valve below ； a) Anode side 13, 17, 21 ； b) Cathode side: 8, 14, 18, 21 6.7.2.3 Verify that the oil pressure is at 7.5 MPa ； 6.7.2.4 Prepare the cleaning solution, small flow meter, torque wrench, and paper for recording leakage inspection results ； 6.7.2.5 Remove the elastic hose at the anode solution outlet of the unit cell ； 6.7.2.6 Open valve 31, fill pure water to 1/2 of the length of the elastic hose at the anode inlet, then close valve 31. 6.7.3 Pressurizing the cathode chamber by filling with nitrogen (refer to Figure D.3) 6.7.3.1 Verify that the tube manometer gauge is filled with water. When it mixes into the air, remove the air ； 6.7.3.2 The indicated pressure is below 5 kPa (0.5 mH2O); the level indicated by DP-247 shows that it is full ； 6.7.3.3 Slowly open the nitrogen valve leading to (DP-247) ； 6.7.3.4 Hose connecting DP-247 to the nitrogen supply valve 20 ； 6.7.3.5 Open valve 20 to introduce nitrogen, and gradually increase the pressure indicated by the DCS until it reaches 5 kPa (0.5 mH2O). Maintain close communication at the site and in the DCS room to prevent overpressurization. 6.7.4 Membrane leakage inspection 6.7.4.1 After the pressure in the cathode chamber of the tubular manometer stabilizes, apply soapy water to the outlet tube of the anode chamber using a brush to check for bubbles; observe each tube opening for 10 seconds ； 6.7.4.2 When a leak is confirmed using the bubble test, a small flow meter is installed at the outlet of the anode chamber to measure and record the amount of nitrogen leaking out ； 6.7.4.3 The above procedure 6.7.4.2 shall be applied to all membranes ； 6.7.4.4 After the membrane leakage check is completed, close valve 20, then open valve 16 to allow the pressure to drop. Remove the hose used for supplying nitrogen, and adjust the indicator to 0 by using the adjustments via the DCS ； 6.7.4.5 Open valve 19 to drain the water contained in the anode solution inlet main pipe, and then close valve 19 after drainage ； 6.7.4.6 Membranes for which the nitrogen leakage rate, as measured using a small flow meter, is 50 L/h or more, must be replaced. After the replacement, conduct a membrane leakage check on all membranes again ； 6.7.4.7 Installed wires (when the wires have been removed) ； 6.7.4.8 Install the flexible hose on the outlet pipe of the anode chamber. 6.7.5 Necessity of membrane leakage inspection If membranes with pinholes are used, accidents such as the following may occur: a) When the hydrogen content in chlorine increases to excessive levels, an explosion can occur in the chlorine drying tower and electrolyzer due to the mixture of chlorine and hydrogen. b) Caustic soda flowing through the pinholes in the membrane damages the anode. In excess amounts: The anode is damaged (the coating is lost); the damage to the anode affects the membrane; the cell frame is damaged (causing caustic soda to leak into the anode chamber); the lifespan of both the anode and the cell frame is reduced. c) The cathode was damaged due to chlorine passing through the pores in the membrane ； In excess, it damages the cathode (causes corrosion), reducing its lifespan. d) Increase NaCl in the caustic soda product ； In excess, it reduces the quality of the caustic soda product. e) In the parts of the membrane where there are pinholes, the frame and sealing gaskets are eroded by the generated sodium hypochlorite (NaClO). When in excess, it causes the electrolyte to leak, reducing the lifespan of the frame and sealing gaskets. 6.7.6 When performing a membrane leakage check, in order to prevent the problems mentioned in the previous 5 points, a membrane leakage check should be carried out under the following circumstances. 6.7.6.1 When the membrane is installed: a) At the initial installation of the membrane. b) When replacing the membrane. c) When replacing the unit slot or the sealing gasket of the unit slot. 6.7.6.2 Before starting operation after a long period of shutdown a) During a long period of shutdown. b) During the annual scheduled shutdown. 6.7.6.3 During procedures such as stopping/starting the electrolyzer, draining/adding electrolyte, and checking for leaks, as well as when the following phenomena occur and membrane leakage is suspected. a) High pressure difference: When the membrane is subjected to excessive air pressure, hydraulic pressure, or a pressure difference of over 20 kPa (2.0 mH2O). b) Reverse pressure difference: When the membrane is subjected to an excessively low air pressure, hydraulic pressure, or pressure difference (reverse pressure difference) of less than -2 kPa (-0.2 mH2O). c) Anode solution overflow: When the outlet valve of the electrolyzer is opened before the electrolyte circulation, liquid continues to flow in the flexible hose at the anode solution outlet. Note: Since reverse pressure difference can easily cause membrane damage and cathode deformation, it is absolutely necessary to prevent its occurrence. 6.7.6.4 Methods for detecting membrane leakage during electrolyzer operation: a) Color change of the material in the flexible hose: The color of the material in the flexible hose at the anode solution outlet changes to pink, purple, or transparent ； b) pH changes, hydrochloric acid fluctuations: As the pH of the anode solution changes, there is abnormal consumption of hydrochloric acid or fluctuations in its flow rate ； c) Increase in H2/Cl2: The hydrogen content in chlorine is above 0.3% ； d) Voltage variation: The voltage of each cell is unstable or varies within a range of ±0.1 V ； e) High gas pressure difference: When the membrane is subjected to an excessive pressure difference ； A few minutes at over 20 kPa (2.0 mH2O) ； f) Low gas pressure difference: When the membrane is subjected to an excessively low pressure difference ； A few minutes at below -2 kPa (-0.2 mH2O) ； g) Changes in EDIZA: The EDIZA value has changed significantly compared to previous values ； h) Slow discoloration of the material in the elastic hose: At the start of operation, the yellowing of the material in the elastic hose at the anode solution outlet occurs much more slowly compared to that in other hoses ； i) Changes in the flow of material within the flexible hose: when the flow of material in the flexible hose at the anode solution outlet changes from turbulent to laminar flow ； 6.8 Leak inspection of the electrolyzer and air replacement (refer to Figure D.3) 6.8.1 Overview After completing the leak inspection of the membrane, a leak inspection is conducted on the assembly parts surrounding the electrolyzer, namely the electrolyzer leak inspection. The electrolyzer leakage check is performed by pressurizing the anode chamber and cathode chamber with pure water, and then checking for leaks on the outside. After the leak check is completed, nitrogen is introduced into the cathode chamber while pure water is discharged. There is no need to remove air from the catholyte main pipe; continue to introduce nitrogen until the electrolyte is injected. 6.8.2 Preparation for electrolyzer leakage inspection 6.8.2.1 Anode pipeline system: Open valves 17 and 21 ； 6.8.2.2 Cathode pipeline system: Open valves 8, 14, 16, 18, 22 ； 6.8.2.3 Verification of oil pressure: Verify that the oil pressure is at 7.5 MPa. 6.8.3 Injection of pure water 6.8.3.1 Injection of pure water: Open valve 32, then open valve 31. Maintain the pressure difference at 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O). (Adjust to 15 m3/h, adjust to 15 m3/h) ； 6.8.3.2 Pure water volume adjustment: After pure water overflows from the outlet pipe of the electrolyzer, control valves 32 and 31 are used to reduce the amount of pure water injected. (Adjust to 5 m3/h, adjust to 5 m3/h). 6.8.3.3 Cathode side shutdown: After pure water overflows through valve 16, close valve 32 ； 6.8.3.4 Anode side stop: After pure water overflows through valve 17, close valve 31. 6.8.4 Inspection for leaks in the electrolyzer 6.8.4.1 Creating a sealed system: Close valves 17 and 21 of the anode system, and close valves 16 and 22 of the cathode system ； 6.8.4.2 Pressurizing pure water: Slightly open valve 32, then slightly open valve 31. Raise the pressure at the inlet to 0.04 MPa (the outlet pressure is 0.02 MPa), and close valves 32 and 31 ； 6.8.4.3 Leak inspection: Check for water leaks around the electrolyzer ； 6.8.4.4 Pressure reduction: After the leak check is completed, open valves 17 and 16 slowly and fully at the same time (valve 17 can be opened slightly earlier than valve 16). 6.8.5 Discharge of pure water 6.8.5.1 Liquid level system pipes: Open valves 21, 22 ； 6.8.5.2 Anode outlet pipeline: After confirming that valve 17 is open, open valve 13 ； 6.8.5.3 Cathode outlet pipeline: After confirming that valve 16 is open, close valve 18 ； 6.8.5.4 Ensure nitrogen supply: Open valves 60 and 62, and set FI-234 to 30 Nm3/h ； 6.8.5.5 Liquid discharge from outlet pipe: Open valves 29 and 30, then close valves 29 and 30 after 5 minutes ； 6.8.5.6 Purified water discharge: Open valve 23, then open valve 24 ； 6.8.5.7 Emission adjustment: Maintain nitrogen injection (DP-234); confirm that nitrogen is bubbling at (DP-234), and adjust valves 23 and 24 to keep the pressure difference between 2 kPa and 10 kPa (0.2 mH2O to 1.0 mH2O) ； 6.8.5.8 Exhausting pure water: After the pure water in the anode chamber and cathode chamber has been exhausted (this is confirmed by the differential pressure gauge connected to the inlet via a flexible hose showing a value close to 0, with the inlet value being 0), close valves 23 and 24 ； 6.8.5.9 Reduce nitrogen flow rate: Adjust valve 60 to reduce the nitrogen flow rate to 5 Nm3/h. 6.8.6 Air replacement in the cathode chamber and second injection and discharge of pure water 6.8.6.1 Pipe formation: Confirm that valves 13, 17, and 16 are open, then open valve 18 ； 6.8.6.2 Pure water injection: First open valve 32, then open valve 31 ； Maintain a pressure difference of 2 kPa to 10 kPa (0.2 mH2O to 1.0 mH2O) ； Adjust to 15 m3/h, at 15 m3/h ； 6.8.6.3 Pure water volume adjustment: After pure water overflows from the pipeline at the electrolyzer outlet, adjust valves 32 and 31 to reduce the amount of pure water injected ； Adjust to 5 m3/h, set it at 5 m3/h ； 6.8.6.4 Stop injecting pure water: After pure water flows out through valve 16, close valve 32 ； After pure water flows out through valve 17, close valve 31 ； 6.8.6.5 Increase chlorine flow rate: Close valve 18 and adjust valve 60 to increase the amount of nitrogen injected through (DP-234) to 30 Nm3/h ； 6.8.6.6 Liquid discharge from outlet pipe: Open valves 29 and 30, then close valves 29 and 30 after 5 minutes ； 6.8.6.7 Purified water discharge: Open valve 23, then open valve 24 ； 6.8.6.8 Emission adjustment: Maintain nitrogen injection (DP-234), adjust valves 23 and 24 to keep the pressure difference at 2 kPa～10 kPa (0.2 mH2O～1.0 mH2O) ； 6.8.6.9 Exhausting pure water: After the pure water in the anode chamber and cathode chamber has been exhausted, close valves 23 and 24. 6.8.6.10 Reduce nitrogen flow rate: Adjust valve 60 to reduce the nitrogen flow rate to 5 Nm3/h. 7 Causes of Abnormal Phenomena and Handling Methods The causes of abnormal phenomena and handling methods are listed in Appendix G. 8 Shift Handover 8.1 The person taking over should arrive at the post in advance and conduct a preliminary inspection along the scheduled route. After that, a pre-shift meeting is held, during which any issues identified during the preliminary inspection are discussed. The person handing over the shift takes these concerns back to their subordinates, who are then instructed to address the problems promptly. 8.2 During shift handover, it is necessary to carry out the handover carefully in accordance with the \"three ones\" principle (handing over item by item, checking each item one by one, and communicating in detail), the \"four senses\" principle (seeing, hearing, touching, smelling), and the \"five reports\" principle (reporting the item number, name, issues, measures taken, and current status). The person conducting the handover must create favorable conditions for the person leaving the shift. 8.3 The shift handovers assist each other in addressing major issues that arise during the handover process. 8.4 Strictly enforce the “Five Handovers” and “Five Non-Acceptances” system 8.4.1 The “Five Handovers” system: 8.4.1.1 Hand over production tasks and their completion status ； 8.4.1.2 Operating process conditions of the equipment and existing problems ； 8.4.1.3 Issues that have occurred regarding quality and safety, and measures proposed to address these issues ； 8.4.1.4 Deliver all tools and equipment ； 8.4.1.5 Hand over record materials and equipment. 8.4.2 The “Five No-Acceptances” Policy: 8.4.2.1 Do not accept tasks if they have not been completed as specified in the post responsibility system, nor issues if they have not been resolved ； 8.4.2.2 Do not accept tasks if they are not completed and the reason is unknown ； 8.4.2.3 Do not accept if there are unresolved quality or safety issues or no measures have been proposed ； 8.4.2.4 Tools and equipment that are lost or missing will not be replaced ； 8.4.2.5 Orders will not be accepted if the records are incomplete or the hygiene is poor. 8.5 Accidents that occur during the handover process are the responsibility of the person handing over, while accidents that occur after the handover are the responsibility of the person taking over. In cases where it is unclear who is responsible, the person taking over bears primary responsibility, but the person handing over should also learn from the experience. If the accident is exacerbated due to the concealment of information, the person handing over duty bears full responsibility. 9 Routine Inspections 9.1 Requirements for Routine Inspections 9.1.1 Strengthen routine inspections in accordance with the designated inspection routes and contents. 9.1.2 The person on duty shall check once before taking over the shift, and once every hour after taking over. 9.1.3 Fill in the inspection details carefully and truthfully, and implement the labeling and re-labeling system. 9.1.4 When abnormal conditions are detected during inspections, it is necessary to contact the relevant personnel promptly, report to the team leader or the workshop, and take timely action to address them. 9.1.5 Points to Note During Routine Inspections ； 9.1.5.1 Production and safety conditions ； 9.1.5.2 Control ranges for each process control point ； 9.1.5.3 Operation status of equipment and valves ； 9.1.5.4 Sealing condition of pipes and valves. 9.2 Route Map for Routine Inspections – Inspection Items for Electrical Tanks Inspection Items for the Hydraulic System: 1. Sealing points related to this system. 2. Whether the inlet and outlet pipes of the electrical tank are in good condition; operating conditions, oil temperature, oil level, oil pressure. 3. Various pressures and flow rates at the site; condition of each pressure regulating valve. 4. Condition of valve openings and closings. 5. Condition of each water seal. 6. Condition of various automatic valves and instruments. Inspection Items for Pumps: D-260: 1. Sealing points related to this pump. D-270: 2. Liquid level in the tank; operating conditions, foot screws. D-280: 3. Condition of valve openings and closings; lubricant level, pump outlet pressure, cooling water pressure. D-290: 4. Condition of various instruments; 3. Condition of valve openings and closings. Figure 1: Route Map for Routine Inspections 10 Safety Techniques and Labor Protection 10.1 Allowable Limits for Toxic and Hazardous Substances 10.1.1 The maximum allowable concentration of chlorine in the air should not exceed 1 mg/m3. 10.1.2 The suspended solids emission standard shall not exceed 200 mg/L. 10.1.3 The petroleum-based substances emission standard shall not exceed 10 mg/L. 10.1.4 The pH value of wastewater discharged shall be between 6 and 9. 10.2 Hazards to health caused by toxic and harmful substances 10.2.1 Hazards to health caused by chlorine Chlorine is highly irritating to the eyes and the mucous membranes of the respiratory system. When the concentration of chlorine in the air reaches a certain level, it can cause breathing difficulties instantly, and even lead to death immediately. It also has a strong irritating effect on the skin. In cases of acute poisoning, mild symptoms include tearing, coughing, a small amount of phlegm production, and chest tightness, with signs of tracheitis and bronchitis. Skin contact with high concentrations of chlorine can cause burns or acute dermatitis in the affected areas. 10.2.2 Health hazards of caustic soda: When an alkaline solution splashes on the skin, especially on mucous membranes, it can cause soft scabs to form and penetrate deep into the tissues. Direct contact with the skin and eyes can cause burns ； Accidental ingestion can cause burns to the digestive tract, mucosal erosion, bleeding, and shock. 10.2.3 Hazards of hydrochloric acid to health Hydrochloric acid can dissolve most metals, forming a white mist in the air. Gaseous hydrogen chloride reacts with water vapor in the air to form hydrochloric acid mist, which can cause poisoning. Hydrochloric acid vapor can irritate the mucous membranes of the eyes, nose, throat, and skin. In cases of acute poisoning, symptoms such as headache, dizziness, nausea, eye pain, coughing, blood in sputum, hoarseness, difficulty breathing, chest tightness, and chest pain may occur. In severe cases, pneumonia, pulmonary edema, atelectasis, and other conditions may occur. Ulcers or turbidity may be visible in the cornea. Direct skin contact can result in millet-like red papules, accompanied by flushing, pain, and heat. 10.3 Measures to prevent disasters and accidents 10.3.1 Operate strictly in accordance with the operating procedures. 10.3.2 Personal protective equipment must be worn before starting work. 10.3.3 Smoking is strictly prohibited throughout the factory premises. 10.3.4 Leaks of electrolyte or chlorine are strictly prohibited in the entire area to prevent environmental contamination. 10.3.5 Hydrogen is highly flammable; when mixed with air or chlorine, it can form explosive gases. The explosive ranges are as follows: 4.1%–74.2% (by volume) for hydrogen in air, 5%–87.5% (by volume) for hydrogen in chlorine, and 5%–95.0% for chlorine in hydrogen. Therefore, it is required that: a) normal operations must be carried out strictly in accordance with the prescribed procedures ； b) After parking, decide whether to fill with nitrogen based on the length of parking time ； 10.3.6 It is prohibited to stack tools and miscellaneous items on the copper conductors, and it is prohibited for one end of a metal conductor to be in contact with the battery cell while the other end is in contact with the ground or other conductors. 10.3.7 A fire work permit must be obtained before carrying out any maintenance work in fire-prohibited areas, and work may only proceed after the analysis shows it is safe to do so. Before working on chlorine pipelines and equipment, the area must be purged with air to remove any hydrogen; similarly, before working on hydrogen and ammonia pipelines and equipment, they must be purged with nitrogen or filled with water, and appropriate preventive measures must be taken. 10.3.8 Motor vehicles are strictly prohibited from entering the electrolysis chamber, shoes with nails are strictly prohibited, and impact by iron tools is strictly prohibited. 10.3.9 The operator on duty must have a gas mask ready, and be sure to have a flashlight available at night. 10.3.10 It is strictly prohibited for people to walk or operate under the load held by a crane. All types of hooks, steel wires, brake pads, and other lifting equipment must be inspected regularly to ensure safety. 10.3.11 It is prohibited to strike various pressure vessels and pipes with iron tools. 10.3.12 Pipes of operating equipment cannot be inspected or repaired. The machine must be stopped, and the remaining contents and residual pressure inside must be drained. When maintaining pump machinery, the power supply must be disconnected and a “Do Not Close” sign must be placed. 10.3.13 Instruments and electrical equipment must be adjusted and maintained by qualified professionals; other personnel are not allowed to touch them. 10.3.14 All storage tanks must be covered, stairways and walkways should be equipped with railings, and the protective covers on motor back wheels must be in good condition; any safety hazards identified must be eliminated promptly. 10.3.15 When operating electrical equipment, your hands must be dry; to check the motor temperature, use the back of your hand. Prevent electric shock. 10.3.16 Strictly comply with the safety and technical requirements for hot work, working at heights, and working inside tanks. 10.4 Methods for dealing with disasters and accidents 10.4.1 If electrical equipment catches fire, use a carbon tetrachloride or carbon dioxide fire extinguisher; water should not be used as it may cause electric shock. 10.4.2 In the event of a chlorine leak, wear a gas mask and address it promptly. If the leakage is too severe to handle, it should be reported promptly to the shift supervisor and the dispatcher. 10.4.3 When dealing with sodium hydroxide leaks, the contaminated area should be isolated to restrict access. Emergency responders should wear self-contained breathing apparatus and acid-alkali resistant protective clothing; they must not come into direct contact with the spill. In the case of a small spill, it can be washed down with large amounts of water, and the resulting diluted water should then be discharged into the wastewater system. 10.4.4 When dealing with hydrochloric acid leaks, personnel in the contaminated area should be quickly evacuated to a safe zone, and the area should be isolated with strict access controls. It is recommended that emergency responders wear self-contained positive-pressure breathing apparatus and acid-alkali resistant protective clothing; they should avoid direct contact with the leakage material and try to shut off the source of the leak as much as possible. 10.5 Personal protective equipment to be worn: During production operations, it is necessary to wear the required personal protective equipment, such as work clothes, safety helmets, protective goggles, gas masks, rubber gloves, and insulating shoes. 10.6 First aid measures for injuries 10.6.1 Chlorine gas injuries 10.6.1.1 Skin contact: Immediately remove contaminated clothing and rinse with plenty of flowing water. Seek medical attention. 10.6.1.2 Eye contact: Immediately lift the upper and lower eyelids and rinse with flowing water or saline for at least 15 minutes, then seek medical attention. 10.6.1.3 Inhaling: Quickly move away from the polluted area in the opposite direction to areas with fresh air, keep the respiratory tract unobstructed; if breathing is difficult, seek medical attention and receive oxygen therapy. 10.6.2 Damage from electrolytes 10.6.2.1 Caustic soda is highly corrosive; direct contact with the skin or eyes can cause burns. 10.6.2.2 If skin comes into contact with caustic soda, remove the contaminated clothing immediately and rinse the area with plenty of flowing water; do not rub the affected area, and seek medical attention at an emergency clinic if the injury is severe. 10.6.2.3 If eyes come into contact with caustic soda, lift the eyelids immediately and rinse them with plenty of flowing water; do not rub the eyes, and seek medical attention at an emergency clinic if the injury is severe. 10.7 Environmental Hygiene 10.7.1 The direct discharge of saline water and electrolytes into sewers is strictly prohibited. 10.7.2 When saline or electrolyte contaminates the operation area, it should be rinsed clean with river water. 10.7.3 The operation site and its surroundings should be kept dry, with no standing water or waste present. 11 Maintenance of Major Equipment 11.1 Maintenance of Ion-Exchange Membrane Cells 11.1.1 Regularly check whether there are any leaks in the gaskets of various parts of the cell. 11.1.2 Regularly check whether the flow of the anode and cathode fluids in the cell is unobstructed. 11.1.3 Regularly check whether the outlet hose for the anode solution in the cell slot has any discoloration. 11.1.4 Regularly check the static and dynamic sealing points of the electrolyzer and process pipelines for any signs of leakage. 11.1.5 Measure the slot voltages of each unit on time to check for any abnormalities. 11.1.6 Regularly check whether the oil pump and motor are operating properly. 11.1.7 Take samples on time for analysis of the control voltages for various process technologies, and keep proper original records. 11.1.8 Regularly clean and lubricate the electrolysis device. 11.1.9 Carry out the addition or replacement of lubricating oil for the hydraulic pressure device in accordance with the equipment’s “five fixed” schedule. 11.1.10 The operators shall keep records of regular inspections of the electrolytic cells, while the maintenance staff shall maintain daily inspection records and maintenance logs for them. 11.1.11 Promptly address various abnormalities identified during routine inspections; report those that cannot be resolved immediately, shut down the tank for handling, and keep proper records. 12 Original Records 12.1 When filling in original records, operators should ensure accuracy, timeliness, and avoid making alterations, destroying documents, engaging in fraud, omitting any items, or committing errors. After making the record, the recorder shall sign it; signing on behalf of others is not permitted. 12.2 Original records shall be kept in the prescribed chronological order; it is not allowed to record memories or predictions. Recording before the specified time or 15 minutes after it is considered untimely recording. 12.3 Original records shall be filled in with carbon or blue-black ink, using Fangsong font, with clear handwriting and neat arrangement. 12.4 A diagonal line should be drawn in the space marked with a symbol for no data or no specified record. The slant direction is from lower left to upper right; if a single cell is empty, it is marked with a line, while if multiple adjacent cells are empty, a single slant line is drawn for those cells. The blank spaces marked with a line can be filled in with concise words to describe the reason for no record, such as: parking, waiting for materials, etc. Blank spaces are not allowed, nor is it permissible to use dashes to enter data or specified symbols for recording. 12.5 The surface of the recording paper must be clean, with no alterations; if changes are necessary, they can only be made by making corrections, and a signature must be placed at the point of correction. 12.6 The requirements for the format of original records are listed in Appendix H. 13 Systems for the storage and use of raw materials, components, and tools 13.1 System for the use of raw materials 13.1.1 Before starting operation, it is necessary to confirm whether the brine can be supplied in the required quality and on time. 13.1.2 It is prohibited for saltwater from the electrolyzer to overflow from the level gauge. 13.2 Storage and Use of Materials 13.2.1 Materials needed for daily life should be neatly arranged by category in the material room. 13.2.2 Regularly inspect and maintain the materials to keep them in good condition. 13.2.3 Regularly inventory the materials, and report any shortages promptly. 13.2.4 After the materials have been replaced, they should be maintained promptly. The replaced materials that can be repaired should be repaired as soon as possible, while those that cannot be repaired should be stored in the waste area. 13.3 Storage and Use of Tools 13.3.1 Tools used at a specific position shall be registered, and their specifications, models, and quantities shall be handed over during shift changes. 13.3.2 Tools should be neatly placed in the tool box as specified. 13.3.3 Use tools properly; do not discard them carelessly, and under no circumstances strike the tools to avoid damaging them. 13.3.4 In the event of abnormal damage or loss of tools, the responsible person or team shall be punished in accordance with relevant regulations. 14 Use and storage of fire-fighting equipment and protective gear 14.1 Fire-fighting equipment and facilities within the jurisdiction must be strictly managed; it is strictly prohibited to use such equipment and facilities for other purposes. 14.2 Fire-fighting equipment and facilities require the same level of inspection, maintenance, and handover as production equipment, in order to ensure that they remain clean and that all other components are in good condition. It is strictly prohibited to use fire-fighting equipment or activate its switches outside of fire suppression situations ； In the event of a fire, it must be reported to the safety officer promptly after normal use, so that it can be replaced in a timely manner. 14.3 Requirements for the maintenance, cleaning, and hygiene of fire hydrants and fire extinguishers. 14.3.1 Fire-fighting equipment should be placed at fixed locations that are dry, well-ventilated, and easily accessible; it must not be moved without permission, and storage in direct sunlight or in areas with high temperatures and humidity is strictly prohibited. 14.3.2 It is strictly prohibited to pile up miscellaneous items within 2 m around the fire hydrant, and the fire access roads must remain unobstructed. 14.3.3 Fire hydrants must be maintained regularly, and the valve covers should be greased to ensure they can open smoothly. 14.3.4 The surface of the fire hydrant must be kept clean, free of obvious stains and dust accumulation. 14.3.5 Only fire extinguishers may be placed in the fire extinguisher cabinet; no other items are allowed inside or outside it ； The fire extinguisher should be covered with a plastic bag to prevent corrosion. 14.4 Used fire-fighting equipment must not be discarded carelessly or left unattended, nor must it be damaged arbitrarily. 14.5 Fire extinguishers used in this position: carbon dioxide fire extinguishers and dry powder fire extinguishers. How to use a fire extinguisher: Pull out the pin on the fire extinguisher, aim it at the source of the fire, and press the switch.
It’s so comprehensive – exactly what I needed. Thank you, I’ve learned a lot