Request for methanol production operating procedures
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As the title says, I am extremely grateful. Thank you! ! !
What kind of procedures? Methanol production from coke oven gas, or from gasification, or from natural gas?
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Reply 1# WYM2 Operating Procedures for Low-Pressure Alcohol Synthesis I. Job Responsibilities The main tasks of the low-pressure alcohol production unit are: first, to synthesize crude methanol; second, to recover the steam generated as a by-product of the reaction heat. The fresh gas supplied in five stages is compressed, and under appropriate pressure (≤6.0 MPa) and temperature (210–260°C), a certain amount of CO, CO2, and H2 are combined into crude methanol through the action of a methanol catalyst. When the production load is low, additional circulators can be added; in this case, the raw material gas from the fifth stage mixes with the circulating gas before entering the methanol synthesis system. The gas after alcohol separation is partially recycled through a recycler when the recycler is in operation, while another portion is sent to the subsequent process stage after being washed with alcohol to remove any residual methanol from the gas. The demineralized water between the tubes of the methanol synthesis tower is heated by the heat of reaction to produce steam, which is sent to the drum; after the pressure is reduced to 1.3 MPa, it is fed into the steam distribution network. II. Production principle: In the low-pressure alcohol process, CO and CO2 in the gas react with H2 under the action of copper-based catalysts to produce crude methanol, accompanied by various side reactions. Main reaction: CO + 2H2 → CH3OH + Q
CO2 + 3H2 → CH3OH + H2O + Q
Side reactions:
2CO + 4H2 → CH3OCH3 + H2O + Q
CO + 3H2 → CH4 + H2O + Q
4CO + 8H2 → C4H9OH + 3H2O + Q
CO2 + H2 → CO + H2O – Q
nCO + 2nH2 → (CH2)n + nH2O + Q
The main reaction for methanol formation is a reversible exothermic reaction; the volume decreases during this reaction, and it can proceed rapidly only in the presence of a catalyst. Therefore, the reaction is carried out at higher pressures and appropriate temperatures so that CO and CO2 can achieve higher conversion rates. III. Process flow: The semi-water gas, which has been treated by the gas purification system, is pressurized to ≤6.0 MPa using a compressor in five stages. It is then mixed in an oil-water separator with recycled gas that has also been pressurized to ≤6.0 MPa, resulting in gas fed into the tower with a pressure of ≤6.0 MPa and a temperature of around 60°C. The mixed gas entering the tower goes into the shell side of the heat exchanger, where it is heated to 200°C by the gas exiting the methanol tower after reaction. From there, it enters the catalyst layer at the top of the methanol tower, where under conditions of ≤6.0 MPa and 210–260°C, CO, CO2, and H2 react to form methanol while releasing a large amount of heat. Most of the heat released is carried away by the boiling water on the shell side of the methanol tower; the temperature of the catalyst layer and the outlet temperature of the methanol tower are controlled by regulating the pressure in the drum. The hot reaction gas exiting the methanol tower enters the tube side of the heat exchanger, where it exchanges heat counter-currently with the gas entering the tower, and is cooled to around 90°C. The gas exiting this tower is further condensed in an evaporation condenser, cooled to ≤40°C, and then fed into a methanol separator to isolate crude methanol. After the crude methanol is separated, the gas with a pressure of approximately 4.4–5.0 MPa and a temperature of around 40°C is used: part of it is circulated using a recirculation pump, while another part enters from the bottom of the alcohol washing tower, where it comes into countercurrent contact with deionized water coming from the top of the tower in the packing layer. A small amount of methanol in the gas is absorbed; the gas containing this absorbed methanol is then sent to the methanol storage tank after depressurization. The gas, after having had any remaining methanol removed through alcohol washing, returns to the inlet of the sixth stage of the compressor. The annular gap between the tubes of the methanol synthesis tower is continuously filled with boiler feedwater via the drum feedwater. The drum and the shell side of the methanol tower are connected by two water drain pipes and four vapor-liquid rising pipes, forming a natural circulation boiler that produces medium-pressure steam at 2.5 MPa; this steam is then reduced to 1.3 MPa before being sent to the steam distribution network. To ensure water quality, continuous and intermittent drain valves are installed at both the drum and the lower part of the methanol tower. IV. Specifications and Technical Characteristics of Main Equipment
1. Methanol Synthesis Tower
Diameter of methanol tower/mm: Φ2400
Medium:
Shell side: Boiler feed water/medium-pressure steam
Tube side: H2, N2, CH3OH, Ar, CH4, H2O, CO2, CO
Maximum operating temperature/°C: Shell side: 260, Tube side: 275
Maximum operating pressure/MPa: Shell side: 4.0 (usually 2.5), Tube side: 6.0
Design temperature/°C: Shell side: 265, Tube side: 280
Design pressure/MPa: Shell side: 4.0, Tube side: 6.4
Design pressure difference between tube and shell sides/MPa: 2.5
Heat exchange area/m2: ~1360
Diameter of heat exchange tubes/mm: Φ38×2, total 1740 tubes
Empty mass of equipment/kg: ~67775
Mass when filled with water/kg: ~111555
2. Drum of Methanol Synthesis Tower
Design pressure/MPa: 5.0
Operating pressure/MPa: 4.0
Design temperature/°C: 265
Operating temperature/°C: 250
Name of material: Boiler water
Total volume/m3: 6.54
Hydrostatic test pressure/MPa: 7.58
3. Methanol Separator
Diameter of separator/mm: Φ1600
Design pressure/MPa: 6.3
Maximum operating pressure/MPa: 6.0
Design temperature/°C: 60
Maximum operating temperature/°C: 50
Hydrostatic test pressure/MPa: 7.88
Airtightness test pressure/MPa: 6.3
Opening pressure of safety valve/MPa: 6.1
Volume/m3: 14
Name of materials: H2, N2, CH3OH, Ar, CH4, H2O, CO2, CO
Net weight of equipment/kg: 17852
Weight when filled with water/kg: 31852
4. Methanol Heat Exchanger
Diameter of heat exchanger/mm: Φ1400
Design pressure/MPa: Tube side: 6.4, Shell side: 6.4
Design pressure difference between tube and shell sides/MPa: 1.0
Operating pressure/MPa: Tube side: 6.0, Shell side: 6.0
Design temperature/°C: Tube side: 280, Shell side: 240
Operating temperature/°C: Tube side: 265/100, Shell side: 35/220
Heat exchange area/m2: 1500 (mean diameter)
6. Methanol Scrubber
Diameter of scrubber/mm: Φ1600
Medium: H2, N2, CH3OH, CH4, H2O, CO2, CO
Design temperature/°C: 50
Operating temperature/°C: 40
Design pressure/MPa: 6.0
Operating pressure/MPa: 6.0
Hydrostatic test pressure/MPa: 7.88
Total volume/m3: 18
Net weight of equipment/kg: 21295
7. Soft Water Tank
Diameter of soft water tank/mm: Φ1000
Design pressure/MPa: Atmospheric pressure
Operating pressure/MPa: Atmospheric pressure
Design temperature/°C: Room temperature
Operating temperature/°C: Room temperature
Total volume/m3: 2.0
8. Oil-Water Separator
Diameter of oil-water separator/mm: Φ1400
Design pressure/MPa: 6.3
Maximum operating pressure/MPa: 6.0
Design temperature/°C: 60
Operating temperature/°C: <60
Hydrostatic test pressure/MPa: 7.88
Airtightness test pressure/MPa: 6.3
Opening pressure of safety valve/MPa: 6.1
Volume/m3: 9.0
Name of materials: H2, N2, CH4, H2O, CO2, CO, oil
Net weight of equipment/kg: 16375
Weight when filled with water/kg: 28305
9. Evaporative Condenser
Area: 324m2
Inlet gas temperature: <80°C
Outlet gas temperature: <35°C
Operating pressure: 6.0MPa
V. Process Operation Parameters
1. Temperature parameters
Inlet temperature of methanol tower: 190–220°C
Outlet temperature of methanol tower: A ± 0.5°C
Inlet temperature of water cooler: ≤90°C
Outlet temperature of water cooler: ≤40°C
Temperature rise and fall rate: <15°C/h
2. Pressure parameters
Inlet pressure of low-pressure alcohol system: ≤6.0MPa
System pressure difference: ≤0.6MPa
Pressure difference in methanol tower: ≤0.2MPa
Pressure change rate: ≤0.1MPa/min
Steam pressure in drum: 2.5–4.0MPa
3. Level parameters
Liquid level in drum: 1/3–1/2
Liquid level in alcohol separation tank: 1/2–2/3
Liquid level in alcohol scrubber: 1/2–2/3
VI. Operation Control Principles and Key Points during Normal Production
1. Pressure control
Under a certain production load in the low-pressure alcohol system, factors such as the temperature of the catalyst layer in the methanol tower (drum pressure), gas composition, and space velocity can all cause changes in the system pressure. It is necessary to make accurate judgments and make timely adjustments to ensure that operations remain within the specified parameters. When the conditions for methanol synthesis deteriorate and system pressure rises, it is possible to contact the dispatch team to appropriately reduce the production load; if necessary, the vent valve can be opened to ensure that the system pressure does not exceed safe levels, thus maintaining normal production. To reduce the system load, it is necessary to increase the drum pressure promptly, adjust the circulation rate, and keep the temperature within the specified range. When adjusting the pressure, it must be done slowly to ensure that the temperature of the methanol tower remains normal. If pressure changes suddenly, it can damage the flange joints of equipment and pipelines as well as the packing seals of pumps. The general pressure rise and fall rate can be controlled at ≤0.3 MPa/min. 2. Control of the catalyst layer temperature: The boiler water on the shell side of the methanol tower absorbs the heat generated during methanol synthesis in the tube side, turning into boiling water at a specific temperature. This boiling water rises to the upper part of the drum, where it creates a saturated vapor pressure corresponding to its temperature; this is the steam pressure controlled by the drum. The temperature of the catalyst in the methanol tower is regulated by adjusting this drum pressure. Therefore, by adjusting the drum pressure, the catalyst layer temperature can be adjusted accordingly. Generally, for every 0.1 MPa change in the drum pressure, the bed temperature changes by 1.5°C accordingly. In addition, the production load, gas composition, and circulation rate can all cause changes in the temperature of the catalyst layer. If necessary, the drum pressure should be adjusted promptly to maintain its normal operating temperature and avoid significant fluctuations. 3. Level control 1) Drum level: To ensure that the heat generated during the methanol synthesis reaction can be removed promptly and smoothly, the drum must maintain a certain liquid level. At the same time, in order to ensure timely discharge of steam from the drum and prevent water from entering the steam outlet pipe, the drum level must not exceed a certain upper limit. In normal operation, the drum liquid level is generally maintained between 1/3 and 1/2 of the drum’s volume. Both the water supply pressure to the boiler and the opening degree of the water supply valve can affect the drum’s liquid level. When the level becomes abnormal, it is necessary to conduct inspections promptly, report the issue immediately, and restore normal conditions as soon as possible. The amount of blowdown from the drum can also be used to fine-tune its pressure and liquid level; if necessary, increasing the blowdown rate can rapidly reduce the drum’s liquid level and pressure, thereby adjusting the temperature of the catalyst in the methanol tower. 2) The amount of liquid crude methanol separated by the methanol separator/level separator varies depending on the production load, the temperature at the outlet of the water cooler, and the efficiency of the reactions taking place inside the tower. Excessively high or low level control can affect the proper operation of the methanol tower and even lead to accidents. Therefore, the operator must conduct regular inspections to detect issues early and make adjustments promptly, keeping the liquid level within the specified range. If the liquid level in the separator is too high, with the circulation pump operating, liquid methanol will be carried into the pump along with the gas. This causes the temperature of the packing to drop; in severe cases, liquid will enter the pump, resulting in liquid slugging and damage to the machine ； Furthermore, the increased methanol content in the gas entering the tower deteriorated the reactions within the methanol tower, accelerated the occurrence of side reactions in methanol synthesis, and reduced the quality of crude methanol. If the liquid level is too low, air ingress is likely to occur, with high pressure entering the low-pressure equipment system and causing accidents such as **. 4. The water quality parameters for feedwater to the drum are provided for reference (pH 7.0–10.5, Cl— 5 ppm). The drum should be drained once per shift, and its water quality should be analyzed daily; the discharged water should meet the following standards: pH 8.5–10, alkalinity 0.5–2 mmol/l, and Cl— 20 ppm. VII. Process Operating Procedures 1. Initial Startup 1) Preparations before startup A. Ensure that fire-fighting equipment, protective gear, instruments, tools, spare parts, as well as the necessary personnel for startup are available. B. Development of operating procedures, process parameters, and startup plans. C. Completion of the construction project ； Remove temporary wires, cables, and scaffolding to ensure a clean site once work is completed ； The walkways are clear, and the platform railings are safe and reliable. 2) Systematically examine the control design as well as the manufacturing and installation techniques of the equipment, to check for any omissions or missing items. Check in detail according to the process flow diagram to ensure that pipes, valves, instruments, electrical systems, equipment, and lighting are installed correctly. 3) System purging and cleaning/leak testing of the methanol tower and drum. During purging, the main task is to remove debris remaining in the equipment pipes from the installation process. The purge gas is nitrogen. 4) Conduct individual tests on each piece of equipment before starting up the plant, and inspect the pressure vessels in the methanol synthesis unit. 5) Develop a loading plan for catalyst loading. It is required to fill as much, completely, and evenly as possible within the designated filling space, in order to ensure the design capacity of the methanol tower. After loading, blow the catalyst powder clean with nitrogen. 6) Nitrogen is used as an intermediate medium for system purging, reducing the oxygen content in the system to less than 0.1%, ensuring satisfactory exhaust purification. 7) The catalyst is heated for regeneration using low-hydrogen reduction in this system. After the pressure testing is completed, the system is depressurized. Pressurize with nitrogen to 0.8 MPa. For temperature-driven reduction, a proper reduction scheme should be established, and the reduction conditions must be strictly controlled to ensure the quality of catalyst reduction. 2. Short-term parking: Parking that is expected to last within 12 hours is considered short-term parking, during which the low-pressure alcohol system is kept insulated and under pressure in preparation for operation. 1) Contact the dispatcher, and prepare to stop after receiving the dispatcher’s instructions. 2) Cut off the fresh air supply, stop adding water to the drum, and close the external steam supply valve. Reduce the circulation volume, activate the steam ejector, open the heating line valve, and use the drain valve to control the drum liquid level. Maintain the outlet temperature above 210°C and cycle. 3) When the gas circulation at the tower outlet results in zero CO+CO2 levels, shut off the steam injector, close the heating line valve, and close the drum drain valve to maintain the drum liquid level; then stop the circulation pump. 4) The system is maintained at its current pressure and temperature levels, waiting to be started up again. 3. Long-term parking 1) Contact the dispatcher and prepare to park after receiving instructions from them. 2) Cut off the fresh air supply, stop adding water to the drum, close the external steam supply valve, reduce the circulation rate, activate the steam ejector, open the heating line valve, and adjust the drum liquid level using the drain valve. Maintain the circulation with the outlet temperature above 210°C. 3) When the gas in the system circulating to the tower outlet results in zero CO+CO2 levels, gradually reduce the steam injector to lower the circulation rate, with a cooling rate of 10–15°C/h. 4) When the temperature in the synthesis tower is 150°C, shut off the steam injector, close the valve on the heating line, and open the vent valve at the back of the system tower to relieve pressure; the pressure reduction rate should be 0.3 Mpa/mm. 5) When the temperature of the methanol tower drops to ≤50°C, stop the circulator. 6) If the water in the shell side of the methanol column is to be discharged, it is necessary to use N2 to displace it in order to protect the shell side from oxidation. 7) If the system equipment needs to be opened for maintenance, the system pressure must be completely released and replaced with N2 to ensure it is suitable. 8) Precautions: A. After the supply of fresh gas is stopped, the alcohol release valve should be gradually closed until the liquid level reaches zero, at which point the valve should be fully closed. B. During system maintenance, the crude methanol from the alcohol fractionation unit and the dilute methanol from the alcohol washing tower are sent to the alcohol tank, and then to the refined alcohol unit. 4. Emergency Shutdown 1) Under what circumstances should the system be shut down in an emergency? A. In the event of massive leaks from equipment and pipelines, resulting in **fires or serious hazards at the relevant locations. B: Power off, cut off cooling water, cut off instrument air. C. Interruption of water supply to the drum. D. Shutdown is caused by a low drum level or a high alcohol level. 2) Emergency shutdown step A: Contact the dispatch and compression team promptly to prepare for shutdown. B. Immediately cut off the fresh gas or other sources that caused the accident. C. Depending on the accident that occurred, take measures such as short-term or long-term shutdown. D. During the parking process, pay attention to controlling the level of the drum liquid and the level of the alcohol fraction. 5. Driving after short-term parking 1) Preparation work A: The methanol system is shut down for no more than 12 hours. B. The methanol system is under N2 protection. C. The reaction temperature in the methanol tower is maintained above 210°C. D. The device control system and interlock system are normal. E. The compressor is ready to supply air. F. Turn on the coolant water and start the alcohol washing pump. G. Control the drum liquid level, alcohol separation tank liquid level, alcohol washing tower liquid level, and steam pressure. 2) Driving steps A: Keep the system at 0.5 MPa, start the circulator, and operate it with a low circulation volume. B. Start the ejector, open the heating line valve to adjust the steam volume and maintain the outlet temperature of the methanol tower at ≥210°C, and use the drain valve to control the level of liquid in the drum. C. The circulation rate can be increased when the outlet temperature of the methanol tower is between 210–230°C. D. During the addition of fresh gas, monitor the outlet temperature of the methanol tower at all times; by adjusting the amount of steam and the circulation rate used in the ejector, maintain the outlet temperature of the methanol tower between 210–230°C, with the liquid level in the drum kept at 50%. E. Once it is detected that the outlet temperature is below 210°C, the supply of fresh gas should be stopped, the fresh gas should be vented, the circulation volume should be reduced, and the supply of fresh gas should be resumed only after the injector temperature rises again. F. When the system pressure reaches 4.0 MPa, opening the vent maintains the stability of the gas composition entering the tower. When approaching the target pressure, releasing air is used to prevent the system pressure from increasing any further. G. Gradually increase the circulation rate; stop increasing it when a cooling trend appears, and slowly increase the fresh gas flow until the outlet temperature rises again. H: Alternating dose increases, with intermittent stabilization until full volume is reached. I. After the alcohol level is normal, set 50% for automatic control. J. Once the steam pressure in the drum reaches the specified value, it is connected to the pipeline network and put under automatic control. K. Gradually adjust various parameters to reach a normal operating state. 6. Starting up after long-term parking: When the low-methanol system has been shut down for more than 12 hours, for any reason, except in cases where the catalyst needs to be replaced, the pressure in the low-methanol system should be reduced to 0.1 MPa; it should then be purged with nitrogen until the levels of CO + CO2 + H2 are less than 1%. After that, the pressure should be maintained at 0.3–0.4 MPa using nitrogen, and the system should be cooled down before attempting to restart it. If there is no nitrogen, the gas supply can be cut off, and the system’s circulation pump can be used to maintain heat until the CO level at the outlet of the tower reaches zero; after that, the temperature should be reduced to 80°C and the pressure lowered to 0.3 MPa. 1) Preparations before driving: A. Check that all blind flanges on the system have been removed and that all connections are properly made. B. Check all instruments by contacting them to ensure that they and the alarms are all in working order. C. The utility facilities are ready; whether water, gas, electricity, and steam can be supplied properly. D. Contact the dispatcher to get ready for departure. 2) The maintenance area is purged with nitrogen at a pressure of ≤0.8 MPa, until it is free of water and impurities. 3) The airtightness test has passed. 4) Purging is required before starting up the system after maintenance; the specific areas to be purged and the methods used depend on the nature of the maintenance work. Nitrogen is generally used for displacement, making sure no dead corners remain; the equipment, pipelines, and instruments are appropriately opened to facilitate drainage and exhaust for displacement. Samples are taken from each discharge point for analysis, and two consecutive analyses showing an O2 level of less than 0.5% indicate compliance. Close the bypasses for all drain valves and control valves. B. Precautions a) Gas in the methanol tower must not flow in reverse. b) When the methanol tower has no catalyst installed nor is it passivated, the vent gas must not enter the methanol tower. 5) Adjust the valves of the methanol system to their normal positions. 6) Start the steam supply and the temperature/pressure reduction devices to warm the pipes. 7) Driving steps A: Contact the dispatcher to fill the methanol system with pure nitrogen and hydrogen up to 0.8 MPa. B. Start the high-pressure pump to add water to the alcohol washing tower ； Open the water supply valve for the evaporative condenser. C. Open the drum vent valve, fill the methanol column shell side with deionized water until the drum liquid level reaches 50%, then close the drum steam vent valve. D. Start the circulation pump to enable internal circulation of the system. E. Open the ejector control valve and the heating line valve to inject saturated steam into the methanol tower in order to heat the catalyst, raising the temperature at a rate of 15°C/h until the outlet temperature of the methanol tower reaches 190°C. F. During the heating process, when the drum liquid level is at 1/3–1/2, intermittent manual drainage of the drum is carried out to maintain the drum liquid level at 1/3–1/2. Once the temperature rise is complete and the system stabilizes, the drum level is placed under automatic control. G. When the outlet temperature of the methanol tower reaches 210°C, the compression section supplies fresh gas to the system. H. When the pressure is raised to match the system pressure, open the outlet valve of this system and connect it to the main system. I. As the reaction heat increases, the injector control valve can be gradually closed down until the reaction in the methanol tower can generate heat by itself; at that point, the injector control valve should be fully closed, as well as the steam valve used for heating. J. As the reaction heat increases, water can be added by opening the water supply valve in the drum; when the steam pressure in the drum reaches 2.5 Mpa–3.0 Mpa, the degree to which the steam supply valve outside the drum is opened is determined based on the temperature of the methanol column bed. K, the circulation rate is determined by the CO content in the tower, with the temperature of the methanol column bed influencing this circulation rate. L. Pay attention to the alcohol level. 7. Catalyst discharge A: The methanol system is at atmospheric pressure. B. The catalyst has been oxidized. C. Open the manhole on the methanol tower and the outlet pipe of the methanol tower. D. Prepare the container for transporting and unloading the catalyst. E. If cooling the catalyst is necessary, have the fire-fighting water hose ready for use. F. Open the unloading device at the lower part of the methanol tower to unload the catalyst. G. Check from the upper tube sheet to confirm that the catalyst in all tubes has been removed. H. Use a vacuum cleaner to remove the catalyst remaining in the methanol column and within individual columns of the methanol plant. I. After removing the catalyst, the methanol tower is purged with nitrogen to remove dust and oil residues. J. If the catalyst generates excessive heat during unloading, it can be cooled using cooling water. 8. Judgment and handling of common accident causes 1) Sudden rise in the temperature of the methanol tower: Common causes and treatment methods – A sudden decrease in the circulation rate; increase the circulation rate. An increase in the pressure in the drum: Adjust the drum pressure; if necessary, increase the amount of waste discharged or adjust the circulation rate to bring the temperature down as quickly as possible. In the event of a dry pan accident due to a failed alarm, an emergency shutdown must be initiated immediately to prevent the accident from worsening. Changes in the gas composition, such as an increase in CO levels, are related to scheduling efforts aimed at adjusting the CO level back to normal values so that the temperature can return to normal as quickly as possible. If the amount of fresh gas increases too rapidly, adjust the circulation rate or drum pressure in a timely manner to match the load. The steam control valve failed, causing the drum pressure to rise suddenly; the control valve was repaired, and a bypass valve was used for control. Avoid operational errors and excessive adjustment ranges; operate carefully and adjust various process parameters meticulously to minimize large fluctuations ； Depending on the bed temperature, reduce the system pressure appropriately; if necessary, release the pressure in the methanol system and proceed with an emergency shutdown. 2) Sudden drop in the temperature of the methanol tower: Common causes and solutions. Sudden increase in circulation rate – reduce the circulation rate appropriately; decrease in drum pressure – increase the drum pressure to restore it to normal levels. Changes in the composition of the fresh gas, with a decrease in CO levels, are related to scheduling adjustments; the gas composition is modified to restore the CO level to normal values. A high level in the methanol separator or a false level causes methanol to flow into the methanol tower, which in turn triggers the opening of the methanol discharge valve in order to restore the normal level. The circulation rate is reduced to control the temperature, and the instrumentation should be checked to verify the level indication. Due to operational errors, the adjustment range was too large; careful operation is required, with precise tuning of various process parameters to minimize excessive fluctuations. 3) Rising system pressure: Common causes and solutions. Excessive system load – contact the dispatch control team to adjust the production load appropriately. Low catalyst temperature, resulting in poor reaction performance – increase the catalyst temperature. Poor catalyst activity – protect the catalyst’s activity by raising the heat source temperature; replace the catalyst if necessary. If the instrument malfunctions, notify the maintenance team for repair. If the alcohol level is too high, the reaction quality deteriorates rapidly; therefore, reduce the alcohol level. If the water cooling effect is poor, contact the dispatch team to increase the cooling water pressure or clean the water filter. The system uses wax to maintain production; it is cleaned during shutdown. 4) Drop in system pressure: Common causes and solutions. Low system load – increase the system load; Improper operation of the alcohol handling process, low liquid level in the alcohol washing tower – reduce the alcohol discharge valve to prevent air from entering the system. System leakage: Locate and eliminate the leak points. 5) Increased pressure difference in the methanol tower – Common causes and solutions: Excessive system load: Reduce the system load; Excessive circulation volume: Decrease the circulation volume; Severe contamination of the gas entering the tower: Improve the quality of the purified gas; Severe wax buildup in the system: Continue production and clean it when shutting down the system. The methanol tower and heat exchangers were shut down for maintenance due to blockages; the catalysts became aged and were replaced. When instruments stopped functioning, maintenance was requested. 6) Drop in the level of water in the drum: Common causes and solutions – If the amount of demineralized water supplied is low, contact the dispatch team to increase the water supply promptly. The automatic control valve is faulty: its opening degree is low or it cannot open. Use the bypass to control the drum pressure, and notify the instrumentation team for repair. If the instrument malfunctions, adjustment is carried out using the on-site level gauge, and the instrument maintenance team is notified. 7) Sudden increase in drum pressure: Common causes and treatment methods. If the drum liquid level is high, quickly reduce the boiler feed water valve, open the drum drain valve, and maintain a normal drum liquid level. In the event of a failure in the steam outlet self-regulating valve, the drum pressure is quickly controlled using a bypass or vent valve.
CO2 + 3H2 → CH3OH + H2O + Q
Side reactions:
2CO + 4H2 → CH3OCH3 + H2O + Q
CO + 3H2 → CH4 + H2O + Q
4CO + 8H2 → C4H9OH + 3H2O + Q
CO2 + H2 → CO + H2O – Q
nCO + 2nH2 → (CH2)n + nH2O + Q
The main reaction for methanol formation is a reversible exothermic reaction; the volume decreases during this reaction, and it can proceed rapidly only in the presence of a catalyst. Therefore, the reaction is carried out at higher pressures and appropriate temperatures so that CO and CO2 can achieve higher conversion rates. III. Process flow: The semi-water gas, which has been treated by the gas purification system, is pressurized to ≤6.0 MPa using a compressor in five stages. It is then mixed in an oil-water separator with recycled gas that has also been pressurized to ≤6.0 MPa, resulting in gas fed into the tower with a pressure of ≤6.0 MPa and a temperature of around 60°C. The mixed gas entering the tower goes into the shell side of the heat exchanger, where it is heated to 200°C by the gas exiting the methanol tower after reaction. From there, it enters the catalyst layer at the top of the methanol tower, where under conditions of ≤6.0 MPa and 210–260°C, CO, CO2, and H2 react to form methanol while releasing a large amount of heat. Most of the heat released is carried away by the boiling water on the shell side of the methanol tower; the temperature of the catalyst layer and the outlet temperature of the methanol tower are controlled by regulating the pressure in the drum. The hot reaction gas exiting the methanol tower enters the tube side of the heat exchanger, where it exchanges heat counter-currently with the gas entering the tower, and is cooled to around 90°C. The gas exiting this tower is further condensed in an evaporation condenser, cooled to ≤40°C, and then fed into a methanol separator to isolate crude methanol. After the crude methanol is separated, the gas with a pressure of approximately 4.4–5.0 MPa and a temperature of around 40°C is used: part of it is circulated using a recirculation pump, while another part enters from the bottom of the alcohol washing tower, where it comes into countercurrent contact with deionized water coming from the top of the tower in the packing layer. A small amount of methanol in the gas is absorbed; the gas containing this absorbed methanol is then sent to the methanol storage tank after depressurization. The gas, after having had any remaining methanol removed through alcohol washing, returns to the inlet of the sixth stage of the compressor. The annular gap between the tubes of the methanol synthesis tower is continuously filled with boiler feedwater via the drum feedwater. The drum and the shell side of the methanol tower are connected by two water drain pipes and four vapor-liquid rising pipes, forming a natural circulation boiler that produces medium-pressure steam at 2.5 MPa; this steam is then reduced to 1.3 MPa before being sent to the steam distribution network. To ensure water quality, continuous and intermittent drain valves are installed at both the drum and the lower part of the methanol tower. IV. Specifications and Technical Characteristics of Main Equipment
1. Methanol Synthesis Tower
Diameter of methanol tower/mm: Φ2400
Medium:
Shell side: Boiler feed water/medium-pressure steam
Tube side: H2, N2, CH3OH, Ar, CH4, H2O, CO2, CO
Maximum operating temperature/°C: Shell side: 260, Tube side: 275
Maximum operating pressure/MPa: Shell side: 4.0 (usually 2.5), Tube side: 6.0
Design temperature/°C: Shell side: 265, Tube side: 280
Design pressure/MPa: Shell side: 4.0, Tube side: 6.4
Design pressure difference between tube and shell sides/MPa: 2.5
Heat exchange area/m2: ~1360
Diameter of heat exchange tubes/mm: Φ38×2, total 1740 tubes
Empty mass of equipment/kg: ~67775
Mass when filled with water/kg: ~111555
2. Drum of Methanol Synthesis Tower
Design pressure/MPa: 5.0
Operating pressure/MPa: 4.0
Design temperature/°C: 265
Operating temperature/°C: 250
Name of material: Boiler water
Total volume/m3: 6.54
Hydrostatic test pressure/MPa: 7.58
3. Methanol Separator
Diameter of separator/mm: Φ1600
Design pressure/MPa: 6.3
Maximum operating pressure/MPa: 6.0
Design temperature/°C: 60
Maximum operating temperature/°C: 50
Hydrostatic test pressure/MPa: 7.88
Airtightness test pressure/MPa: 6.3
Opening pressure of safety valve/MPa: 6.1
Volume/m3: 14
Name of materials: H2, N2, CH3OH, Ar, CH4, H2O, CO2, CO
Net weight of equipment/kg: 17852
Weight when filled with water/kg: 31852
4. Methanol Heat Exchanger
Diameter of heat exchanger/mm: Φ1400
Design pressure/MPa: Tube side: 6.4, Shell side: 6.4
Design pressure difference between tube and shell sides/MPa: 1.0
Operating pressure/MPa: Tube side: 6.0, Shell side: 6.0
Design temperature/°C: Tube side: 280, Shell side: 240
Operating temperature/°C: Tube side: 265/100, Shell side: 35/220
Heat exchange area/m2: 1500 (mean diameter)
6. Methanol Scrubber
Diameter of scrubber/mm: Φ1600
Medium: H2, N2, CH3OH, CH4, H2O, CO2, CO
Design temperature/°C: 50
Operating temperature/°C: 40
Design pressure/MPa: 6.0
Operating pressure/MPa: 6.0
Hydrostatic test pressure/MPa: 7.88
Total volume/m3: 18
Net weight of equipment/kg: 21295
7. Soft Water Tank
Diameter of soft water tank/mm: Φ1000
Design pressure/MPa: Atmospheric pressure
Operating pressure/MPa: Atmospheric pressure
Design temperature/°C: Room temperature
Operating temperature/°C: Room temperature
Total volume/m3: 2.0
8. Oil-Water Separator
Diameter of oil-water separator/mm: Φ1400
Design pressure/MPa: 6.3
Maximum operating pressure/MPa: 6.0
Design temperature/°C: 60
Operating temperature/°C: <60
Hydrostatic test pressure/MPa: 7.88
Airtightness test pressure/MPa: 6.3
Opening pressure of safety valve/MPa: 6.1
Volume/m3: 9.0
Name of materials: H2, N2, CH4, H2O, CO2, CO, oil
Net weight of equipment/kg: 16375
Weight when filled with water/kg: 28305
9. Evaporative Condenser
Area: 324m2
Inlet gas temperature: <80°C
Outlet gas temperature: <35°C
Operating pressure: 6.0MPa
V. Process Operation Parameters
1. Temperature parameters
Inlet temperature of methanol tower: 190–220°C
Outlet temperature of methanol tower: A ± 0.5°C
Inlet temperature of water cooler: ≤90°C
Outlet temperature of water cooler: ≤40°C
Temperature rise and fall rate: <15°C/h
2. Pressure parameters
Inlet pressure of low-pressure alcohol system: ≤6.0MPa
System pressure difference: ≤0.6MPa
Pressure difference in methanol tower: ≤0.2MPa
Pressure change rate: ≤0.1MPa/min
Steam pressure in drum: 2.5–4.0MPa
3. Level parameters
Liquid level in drum: 1/3–1/2
Liquid level in alcohol separation tank: 1/2–2/3
Liquid level in alcohol scrubber: 1/2–2/3
VI. Operation Control Principles and Key Points during Normal Production
1. Pressure control
Under a certain production load in the low-pressure alcohol system, factors such as the temperature of the catalyst layer in the methanol tower (drum pressure), gas composition, and space velocity can all cause changes in the system pressure. It is necessary to make accurate judgments and make timely adjustments to ensure that operations remain within the specified parameters. When the conditions for methanol synthesis deteriorate and system pressure rises, it is possible to contact the dispatch team to appropriately reduce the production load; if necessary, the vent valve can be opened to ensure that the system pressure does not exceed safe levels, thus maintaining normal production. To reduce the system load, it is necessary to increase the drum pressure promptly, adjust the circulation rate, and keep the temperature within the specified range. When adjusting the pressure, it must be done slowly to ensure that the temperature of the methanol tower remains normal. If pressure changes suddenly, it can damage the flange joints of equipment and pipelines as well as the packing seals of pumps. The general pressure rise and fall rate can be controlled at ≤0.3 MPa/min. 2. Control of the catalyst layer temperature: The boiler water on the shell side of the methanol tower absorbs the heat generated during methanol synthesis in the tube side, turning into boiling water at a specific temperature. This boiling water rises to the upper part of the drum, where it creates a saturated vapor pressure corresponding to its temperature; this is the steam pressure controlled by the drum. The temperature of the catalyst in the methanol tower is regulated by adjusting this drum pressure. Therefore, by adjusting the drum pressure, the catalyst layer temperature can be adjusted accordingly. Generally, for every 0.1 MPa change in the drum pressure, the bed temperature changes by 1.5°C accordingly. In addition, the production load, gas composition, and circulation rate can all cause changes in the temperature of the catalyst layer. If necessary, the drum pressure should be adjusted promptly to maintain its normal operating temperature and avoid significant fluctuations. 3. Level control 1) Drum level: To ensure that the heat generated during the methanol synthesis reaction can be removed promptly and smoothly, the drum must maintain a certain liquid level. At the same time, in order to ensure timely discharge of steam from the drum and prevent water from entering the steam outlet pipe, the drum level must not exceed a certain upper limit. In normal operation, the drum liquid level is generally maintained between 1/3 and 1/2 of the drum’s volume. Both the water supply pressure to the boiler and the opening degree of the water supply valve can affect the drum’s liquid level. When the level becomes abnormal, it is necessary to conduct inspections promptly, report the issue immediately, and restore normal conditions as soon as possible. The amount of blowdown from the drum can also be used to fine-tune its pressure and liquid level; if necessary, increasing the blowdown rate can rapidly reduce the drum’s liquid level and pressure, thereby adjusting the temperature of the catalyst in the methanol tower. 2) The amount of liquid crude methanol separated by the methanol separator/level separator varies depending on the production load, the temperature at the outlet of the water cooler, and the efficiency of the reactions taking place inside the tower. Excessively high or low level control can affect the proper operation of the methanol tower and even lead to accidents. Therefore, the operator must conduct regular inspections to detect issues early and make adjustments promptly, keeping the liquid level within the specified range. If the liquid level in the separator is too high, with the circulation pump operating, liquid methanol will be carried into the pump along with the gas. This causes the temperature of the packing to drop; in severe cases, liquid will enter the pump, resulting in liquid slugging and damage to the machine ； Furthermore, the increased methanol content in the gas entering the tower deteriorated the reactions within the methanol tower, accelerated the occurrence of side reactions in methanol synthesis, and reduced the quality of crude methanol. If the liquid level is too low, air ingress is likely to occur, with high pressure entering the low-pressure equipment system and causing accidents such as **. 4. The water quality parameters for feedwater to the drum are provided for reference (pH 7.0–10.5, Cl— 5 ppm). The drum should be drained once per shift, and its water quality should be analyzed daily; the discharged water should meet the following standards: pH 8.5–10, alkalinity 0.5–2 mmol/l, and Cl— 20 ppm. VII. Process Operating Procedures 1. Initial Startup 1) Preparations before startup A. Ensure that fire-fighting equipment, protective gear, instruments, tools, spare parts, as well as the necessary personnel for startup are available. B. Development of operating procedures, process parameters, and startup plans. C. Completion of the construction project ； Remove temporary wires, cables, and scaffolding to ensure a clean site once work is completed ； The walkways are clear, and the platform railings are safe and reliable. 2) Systematically examine the control design as well as the manufacturing and installation techniques of the equipment, to check for any omissions or missing items. Check in detail according to the process flow diagram to ensure that pipes, valves, instruments, electrical systems, equipment, and lighting are installed correctly. 3) System purging and cleaning/leak testing of the methanol tower and drum. During purging, the main task is to remove debris remaining in the equipment pipes from the installation process. The purge gas is nitrogen. 4) Conduct individual tests on each piece of equipment before starting up the plant, and inspect the pressure vessels in the methanol synthesis unit. 5) Develop a loading plan for catalyst loading. It is required to fill as much, completely, and evenly as possible within the designated filling space, in order to ensure the design capacity of the methanol tower. After loading, blow the catalyst powder clean with nitrogen. 6) Nitrogen is used as an intermediate medium for system purging, reducing the oxygen content in the system to less than 0.1%, ensuring satisfactory exhaust purification. 7) The catalyst is heated for regeneration using low-hydrogen reduction in this system. After the pressure testing is completed, the system is depressurized. Pressurize with nitrogen to 0.8 MPa. For temperature-driven reduction, a proper reduction scheme should be established, and the reduction conditions must be strictly controlled to ensure the quality of catalyst reduction. 2. Short-term parking: Parking that is expected to last within 12 hours is considered short-term parking, during which the low-pressure alcohol system is kept insulated and under pressure in preparation for operation. 1) Contact the dispatcher, and prepare to stop after receiving the dispatcher’s instructions. 2) Cut off the fresh air supply, stop adding water to the drum, and close the external steam supply valve. Reduce the circulation volume, activate the steam ejector, open the heating line valve, and use the drain valve to control the drum liquid level. Maintain the outlet temperature above 210°C and cycle. 3) When the gas circulation at the tower outlet results in zero CO+CO2 levels, shut off the steam injector, close the heating line valve, and close the drum drain valve to maintain the drum liquid level; then stop the circulation pump. 4) The system is maintained at its current pressure and temperature levels, waiting to be started up again. 3. Long-term parking 1) Contact the dispatcher and prepare to park after receiving instructions from them. 2) Cut off the fresh air supply, stop adding water to the drum, close the external steam supply valve, reduce the circulation rate, activate the steam ejector, open the heating line valve, and adjust the drum liquid level using the drain valve. Maintain the circulation with the outlet temperature above 210°C. 3) When the gas in the system circulating to the tower outlet results in zero CO+CO2 levels, gradually reduce the steam injector to lower the circulation rate, with a cooling rate of 10–15°C/h. 4) When the temperature in the synthesis tower is 150°C, shut off the steam injector, close the valve on the heating line, and open the vent valve at the back of the system tower to relieve pressure; the pressure reduction rate should be 0.3 Mpa/mm. 5) When the temperature of the methanol tower drops to ≤50°C, stop the circulator. 6) If the water in the shell side of the methanol column is to be discharged, it is necessary to use N2 to displace it in order to protect the shell side from oxidation. 7) If the system equipment needs to be opened for maintenance, the system pressure must be completely released and replaced with N2 to ensure it is suitable. 8) Precautions: A. After the supply of fresh gas is stopped, the alcohol release valve should be gradually closed until the liquid level reaches zero, at which point the valve should be fully closed. B. During system maintenance, the crude methanol from the alcohol fractionation unit and the dilute methanol from the alcohol washing tower are sent to the alcohol tank, and then to the refined alcohol unit. 4. Emergency Shutdown 1) Under what circumstances should the system be shut down in an emergency? A. In the event of massive leaks from equipment and pipelines, resulting in **fires or serious hazards at the relevant locations. B: Power off, cut off cooling water, cut off instrument air. C. Interruption of water supply to the drum. D. Shutdown is caused by a low drum level or a high alcohol level. 2) Emergency shutdown step A: Contact the dispatch and compression team promptly to prepare for shutdown. B. Immediately cut off the fresh gas or other sources that caused the accident. C. Depending on the accident that occurred, take measures such as short-term or long-term shutdown. D. During the parking process, pay attention to controlling the level of the drum liquid and the level of the alcohol fraction. 5. Driving after short-term parking 1) Preparation work A: The methanol system is shut down for no more than 12 hours. B. The methanol system is under N2 protection. C. The reaction temperature in the methanol tower is maintained above 210°C. D. The device control system and interlock system are normal. E. The compressor is ready to supply air. F. Turn on the coolant water and start the alcohol washing pump. G. Control the drum liquid level, alcohol separation tank liquid level, alcohol washing tower liquid level, and steam pressure. 2) Driving steps A: Keep the system at 0.5 MPa, start the circulator, and operate it with a low circulation volume. B. Start the ejector, open the heating line valve to adjust the steam volume and maintain the outlet temperature of the methanol tower at ≥210°C, and use the drain valve to control the level of liquid in the drum. C. The circulation rate can be increased when the outlet temperature of the methanol tower is between 210–230°C. D. During the addition of fresh gas, monitor the outlet temperature of the methanol tower at all times; by adjusting the amount of steam and the circulation rate used in the ejector, maintain the outlet temperature of the methanol tower between 210–230°C, with the liquid level in the drum kept at 50%. E. Once it is detected that the outlet temperature is below 210°C, the supply of fresh gas should be stopped, the fresh gas should be vented, the circulation volume should be reduced, and the supply of fresh gas should be resumed only after the injector temperature rises again. F. When the system pressure reaches 4.0 MPa, opening the vent maintains the stability of the gas composition entering the tower. When approaching the target pressure, releasing air is used to prevent the system pressure from increasing any further. G. Gradually increase the circulation rate; stop increasing it when a cooling trend appears, and slowly increase the fresh gas flow until the outlet temperature rises again. H: Alternating dose increases, with intermittent stabilization until full volume is reached. I. After the alcohol level is normal, set 50% for automatic control. J. Once the steam pressure in the drum reaches the specified value, it is connected to the pipeline network and put under automatic control. K. Gradually adjust various parameters to reach a normal operating state. 6. Starting up after long-term parking: When the low-methanol system has been shut down for more than 12 hours, for any reason, except in cases where the catalyst needs to be replaced, the pressure in the low-methanol system should be reduced to 0.1 MPa; it should then be purged with nitrogen until the levels of CO + CO2 + H2 are less than 1%. After that, the pressure should be maintained at 0.3–0.4 MPa using nitrogen, and the system should be cooled down before attempting to restart it. If there is no nitrogen, the gas supply can be cut off, and the system’s circulation pump can be used to maintain heat until the CO level at the outlet of the tower reaches zero; after that, the temperature should be reduced to 80°C and the pressure lowered to 0.3 MPa. 1) Preparations before driving: A. Check that all blind flanges on the system have been removed and that all connections are properly made. B. Check all instruments by contacting them to ensure that they and the alarms are all in working order. C. The utility facilities are ready; whether water, gas, electricity, and steam can be supplied properly. D. Contact the dispatcher to get ready for departure. 2) The maintenance area is purged with nitrogen at a pressure of ≤0.8 MPa, until it is free of water and impurities. 3) The airtightness test has passed. 4) Purging is required before starting up the system after maintenance; the specific areas to be purged and the methods used depend on the nature of the maintenance work. Nitrogen is generally used for displacement, making sure no dead corners remain; the equipment, pipelines, and instruments are appropriately opened to facilitate drainage and exhaust for displacement. Samples are taken from each discharge point for analysis, and two consecutive analyses showing an O2 level of less than 0.5% indicate compliance. Close the bypasses for all drain valves and control valves. B. Precautions a) Gas in the methanol tower must not flow in reverse. b) When the methanol tower has no catalyst installed nor is it passivated, the vent gas must not enter the methanol tower. 5) Adjust the valves of the methanol system to their normal positions. 6) Start the steam supply and the temperature/pressure reduction devices to warm the pipes. 7) Driving steps A: Contact the dispatcher to fill the methanol system with pure nitrogen and hydrogen up to 0.8 MPa. B. Start the high-pressure pump to add water to the alcohol washing tower ； Open the water supply valve for the evaporative condenser. C. Open the drum vent valve, fill the methanol column shell side with deionized water until the drum liquid level reaches 50%, then close the drum steam vent valve. D. Start the circulation pump to enable internal circulation of the system. E. Open the ejector control valve and the heating line valve to inject saturated steam into the methanol tower in order to heat the catalyst, raising the temperature at a rate of 15°C/h until the outlet temperature of the methanol tower reaches 190°C. F. During the heating process, when the drum liquid level is at 1/3–1/2, intermittent manual drainage of the drum is carried out to maintain the drum liquid level at 1/3–1/2. Once the temperature rise is complete and the system stabilizes, the drum level is placed under automatic control. G. When the outlet temperature of the methanol tower reaches 210°C, the compression section supplies fresh gas to the system. H. When the pressure is raised to match the system pressure, open the outlet valve of this system and connect it to the main system. I. As the reaction heat increases, the injector control valve can be gradually closed down until the reaction in the methanol tower can generate heat by itself; at that point, the injector control valve should be fully closed, as well as the steam valve used for heating. J. As the reaction heat increases, water can be added by opening the water supply valve in the drum; when the steam pressure in the drum reaches 2.5 Mpa–3.0 Mpa, the degree to which the steam supply valve outside the drum is opened is determined based on the temperature of the methanol column bed. K, the circulation rate is determined by the CO content in the tower, with the temperature of the methanol column bed influencing this circulation rate. L. Pay attention to the alcohol level. 7. Catalyst discharge A: The methanol system is at atmospheric pressure. B. The catalyst has been oxidized. C. Open the manhole on the methanol tower and the outlet pipe of the methanol tower. D. Prepare the container for transporting and unloading the catalyst. E. If cooling the catalyst is necessary, have the fire-fighting water hose ready for use. F. Open the unloading device at the lower part of the methanol tower to unload the catalyst. G. Check from the upper tube sheet to confirm that the catalyst in all tubes has been removed. H. Use a vacuum cleaner to remove the catalyst remaining in the methanol column and within individual columns of the methanol plant. I. After removing the catalyst, the methanol tower is purged with nitrogen to remove dust and oil residues. J. If the catalyst generates excessive heat during unloading, it can be cooled using cooling water. 8. Judgment and handling of common accident causes 1) Sudden rise in the temperature of the methanol tower: Common causes and treatment methods – A sudden decrease in the circulation rate; increase the circulation rate. An increase in the pressure in the drum: Adjust the drum pressure; if necessary, increase the amount of waste discharged or adjust the circulation rate to bring the temperature down as quickly as possible. In the event of a dry pan accident due to a failed alarm, an emergency shutdown must be initiated immediately to prevent the accident from worsening. Changes in the gas composition, such as an increase in CO levels, are related to scheduling efforts aimed at adjusting the CO level back to normal values so that the temperature can return to normal as quickly as possible. If the amount of fresh gas increases too rapidly, adjust the circulation rate or drum pressure in a timely manner to match the load. The steam control valve failed, causing the drum pressure to rise suddenly; the control valve was repaired, and a bypass valve was used for control. Avoid operational errors and excessive adjustment ranges; operate carefully and adjust various process parameters meticulously to minimize large fluctuations ； Depending on the bed temperature, reduce the system pressure appropriately; if necessary, release the pressure in the methanol system and proceed with an emergency shutdown. 2) Sudden drop in the temperature of the methanol tower: Common causes and solutions. Sudden increase in circulation rate – reduce the circulation rate appropriately; decrease in drum pressure – increase the drum pressure to restore it to normal levels. Changes in the composition of the fresh gas, with a decrease in CO levels, are related to scheduling adjustments; the gas composition is modified to restore the CO level to normal values. A high level in the methanol separator or a false level causes methanol to flow into the methanol tower, which in turn triggers the opening of the methanol discharge valve in order to restore the normal level. The circulation rate is reduced to control the temperature, and the instrumentation should be checked to verify the level indication. Due to operational errors, the adjustment range was too large; careful operation is required, with precise tuning of various process parameters to minimize excessive fluctuations. 3) Rising system pressure: Common causes and solutions. Excessive system load – contact the dispatch control team to adjust the production load appropriately. Low catalyst temperature, resulting in poor reaction performance – increase the catalyst temperature. Poor catalyst activity – protect the catalyst’s activity by raising the heat source temperature; replace the catalyst if necessary. If the instrument malfunctions, notify the maintenance team for repair. If the alcohol level is too high, the reaction quality deteriorates rapidly; therefore, reduce the alcohol level. If the water cooling effect is poor, contact the dispatch team to increase the cooling water pressure or clean the water filter. The system uses wax to maintain production; it is cleaned during shutdown. 4) Drop in system pressure: Common causes and solutions. Low system load – increase the system load; Improper operation of the alcohol handling process, low liquid level in the alcohol washing tower – reduce the alcohol discharge valve to prevent air from entering the system. System leakage: Locate and eliminate the leak points. 5) Increased pressure difference in the methanol tower – Common causes and solutions: Excessive system load: Reduce the system load; Excessive circulation volume: Decrease the circulation volume; Severe contamination of the gas entering the tower: Improve the quality of the purified gas; Severe wax buildup in the system: Continue production and clean it when shutting down the system. The methanol tower and heat exchangers were shut down for maintenance due to blockages; the catalysts became aged and were replaced. When instruments stopped functioning, maintenance was requested. 6) Drop in the level of water in the drum: Common causes and solutions – If the amount of demineralized water supplied is low, contact the dispatch team to increase the water supply promptly. The automatic control valve is faulty: its opening degree is low or it cannot open. Use the bypass to control the drum pressure, and notify the instrumentation team for repair. If the instrument malfunctions, adjustment is carried out using the on-site level gauge, and the instrument maintenance team is notified. 7) Sudden increase in drum pressure: Common causes and treatment methods. If the drum liquid level is high, quickly reduce the boiler feed water valve, open the drum drain valve, and maintain a normal drum liquid level. In the event of a failure in the steam outlet self-regulating valve, the drum pressure is quickly controlled using a bypass or vent valve.
Very good, very powerful. I’ve learned it; please post more often.