Boiler room operating procedures

Table of Contents Section 1: Job Responsibilities Section 2: Principles of Production Section 3: Brief Description of the Process Section 4: Preparations Before Starting Up Heating the Boiler 1. Purpose of heating the boiler: 2. Preparations for heating the boiler: 3. Methods and requirements for heating the boiler: 4. Criteria for determining successful boiler heating Boiling the Boiler 1. Purpose of boiling the boiler: 2. The boiling process can be divided into three stages 3. Criteria for determining successful boiler boiling: 4. After boiling the boiler, the feed water pump should be started to flush the boiler with water at a pressure of 0.3~0.4 MPa. Section 5: Startup Procedures – Ignition and Voltage Raising; Normal Operation of the Boiler. Section 7: Shutdown Procedures – Operations for Shutting Down the Boiler. Section 8: Handling of Abnormal Conditions; Handling of Common Boiler Accidents. Section 9: List of Major Equipment. Section 10: Key Control Parameters

Operating Procedures for the 100,000 tons/year methanol SHS20-3.82-Q type boiler at Hebei Xuyang Coking Company
Compiled by: Reviewed by: Approved by: Methanol Workshop

Table of Contents
Job Responsibilities
Production Principle
Brief Description of the Process
Preparations Before Startup
Startup Steps
Operation During Normal Boiler Operation
Shutdown Steps
Handling Abnormal Conditions
List of Major Equipment
Key Control Parameters
Process Flow Diagram

Section 1: Job Responsibilities
To supply qualified steam to the methanol workshop, with a temperature of 249°C and a pressure of 3.82 MPa.

Section 2: Production Principle
During boiler operation, the combustible substances in the fuel burn when mixed with air supplied to the furnace through the ventilation system at an appropriate temperature. This process releases heat, which is transferred to the boiler water via various heating surfaces, causing the water temperature to rise. Saturation steam is then generated, and this steam is sent to the main steam valve through a steam-water separation device for use. Section 3: Brief Description of the Process – Water Vapor Flow: This product model is SHS20-3.82-Q, a horizontal double-drum natural circulation water-tube boiler. The deoxygenated water coming from the deaerator has a temperature of 105°C; after being preheated by the economizer, it is sent to the upper drum. The pressure difference resulting from the lower density and lighter weight of the steam-water mixture in the rising tubes, as compared to the higher density and greater weight of the water in the descending tubes, disrupts the balance between the two columns of water, thereby causing the boiler water to flow and circulate. After separation, the steam with a pressure of 3.82 MPa and a temperature of 249°C is sent to the external piping system. Fuel gas flow: Air is drawn in by a blower and preheated in an air preheater; thereafter, it mixes with coke oven gas in a burner before entering the furnace to burn. The high-temperature flue gas rises from the furnace chamber through the furnace outlet flue window, which is formed by the water-cooled wall tubes on the rear wall; it then passes through the convective tube bank, the economizer, and the air preheater. After its temperature drops to 150°C, it is discharged into the atmosphere via an exhaust fan through the chimney, with dust emission concentrations of less than 50 mg/m3. Section 4: Preparations Before Operation – Boiler Drying I. Purpose of boiler drying: In newly installed boilers, the brick walls and mortar joints contain a significant amount of moisture. If these are not dried before the boiler is put into use, then when the boiler is ignited and heated, the moisture will evaporate in large quantities to form steam, causing the brick walls to deform due to volume expansion. Therefore, it is necessary to remove moisture by baking the furnace. II. Preparation work for furnace drying: 1. All components and associated equipment have been assembled and tested in a cold state, and they have passed the hydraulic test. 2. After bricklaying and insulation work are completed, the doors and openings should be opened to allow natural drying for a period of time. 3. The interior of the furnace, flue ducts, and air ducts should be cleaned thoroughly. 4. Add treated soft water to the boiler up to the low level indicated on the water gauge, and clean the water gauge. 5. Fill the economizer with softened water, and connect the economizer’s recirculation pipe. 6. Organize the furnace drying process properly, and establish operating procedures for it based on the structure of the furnace chamber. A dedicated person should be in charge throughout the furnace drying process. III. Oven drying methods and requirements: Oven drying should be carried out in accordance with the specific conditions on site; details can be found in the oven drying plan. IV. Criteria for successful furnace drying: 1. The furnace walls should show no cracks or deformation during the drying process; it is considered successful when one of the following conditions is met: 2. Samples of mortar taken from the intersections of red bricks at the middle portion of the walls on both sides of the combustion chamber, in amounts of about 50 grams each, should have a moisture content of less than 2.5%. 3. At the middle of the side walls of the combustion chamber, the temperature reaches 50°C 100 mm inside the outer surface of the red brick wall, and this temperature is maintained for 48 hours. Chimney drying: Both newly built brick chimneys and concrete chimneys must be dried before they can be used. A chimney built simultaneously with the boiler furnace wall can be dried using the heat source from furnace drying. Boiler cleaning I. Purpose of boiler cleaning: Boiler cleaning is carried out on newly installed boilers before they are put into operation, in order to remove rust, grease, and dirt that have accumulated inside the boiler during its manufacturing, repair, and installation processes. This is done to prevent deterioration in the quality of the steam and to avoid damage to the heating surfaces due to overheating. The cooking process is carried out at the later stage of drying, that is, simultaneously with the drying process, once the moisture content in the furnace wall mortar drops to 10% or the temperature of the red brick walls reaches 50 degrees, in order to reduce time and save fuel. Boiler treatment chemicals and dosages: Chemical name; Dosage (kilograms per cubic meter of water). Thin rust layer; Thick rust layer: Sodium hydroxide – 2–3; 3–4. Trisodium phosphate – 2–3; 2–3. During boiler treatment, an alkaline solution is first added to the boiler, causing the grease present in it to react with the alkali and precipitate. The impurities are then removed through a waste discharge method. II. The boiler heating process can be divided into three stages: adding chemicals, lighting the fire to start heating, and allowing the boiler water temperature to rise to 99 degrees, a process that takes three days. Keep the water in the boiler at 99 degrees without it boiling; regularly open the vent valve to release steam over a period of 1–2 days. As the temperature of the boiler water gradually drops, turn off the boiler. Once the temperature falls below 50 degrees, drain the water from the boiler. III. Criteria for successful boiler boiling: There is no oil residue on the inner walls of the boiler drum and header. After removing the deposits, there are no rust spots on the metal surface. IV. After the boiler is boiled, the feed water pump should be started to flush the boiler with water at a pressure of 0.3~0.4 MPa. Inspections and preparations before boiler operation: Before putting the boiler into operation, it should be inspected both internally and externally. In particular, new or repaired boilers require the following inspections and preparatory actions: 1. Internal inspection of the boiler and preparation for use; 2. 1. Internal inspection of the boiler – Check whether there are any deposits or residual debris inside the boiler drum and headers. Close the access holes: All manholes and handholes must be sealed, and gaskets should be replaced if necessary to prevent leaks. Water filling test: When filling the boiler with water, open the air valve to remove the air from inside the boiler during this process. The water should be added to the boiler slowly, and the water temperature should not be too high. When filling with water, check the manholes, handholes, all flange joints, and the drain valves. If any leakage is detected, tighten the screws. If leakage persists despite taking these measures, stop filling with water, lower the water level to an appropriate level, replace the sealing gaskets, and then resume filling with water once there is no more leakage. As the boiler water level rises, at the appropriate level, check whether the high and low water level alarms of the boiler, the low water level fuel cut-off function, and the blower interlock device are operating properly. 3. Inspections inside the furnace and flue 1. Inspection inside the furnace: Conduct a trial operation check of the combustion equipment to ensure there are no obstacles, without feeding in fuel. Inspection inside the flue: Check the dampers of the air preheater and the exhaust fan to ensure there are no abnormalities. Sealing of the flue: After confirming that there are no abnormalities in all parts, seal the access doors and openings of the flue. III. Inspection of the water pipeline system: 1. All valves in the water pipeline system should be intact, operate smoothly, be airtight without leaks, and the direction of rotation of the handwheels should correspond to the indicated markings. 2. Check whether the safety valve of the boiler itself is within its calibration period and operates smoothly ； Is the pressure gauge within its calibration period, and is the three-way valve operating smoothly? 3. The air duct leads to the atmosphere, and there are no blind plates at the flange connections of the piping ； Check whether all flange screws are tightened properly, and whether there are any abnormalities such as misalignment. 4. Verify that the drum and all the manhole and handhole covers of the header boxes are fully and tightly closed. IV. Inspection of the gas system: 1. The tightness of valves, flange connections, etc., shall be subject to strength tests and tightness tests as specified. 2. Check whether the cut-off valves, control valves, solenoid valves, drain valves, and other accessories are functioning properly; the manual operation of these valves or their actuation mechanisms should be smooth. Verify whether the opening indication of electric control valves and other valves matches their actual opening degree ； Is the operating power supply for the solenoid valve motor in operation? Check the operating switch, as well as to ensure that the interlock protection devices are functional and reliable. 3. The gas pressure gauge and the pipe sections connecting to it must be unobstructed, with no leaks at the connection points ； The ignition device is in good condition and reliable, and the flame detector should be in good condition as well. All equipment, components, and instruments related to automatic control systems should be thoroughly inspected, and necessary cold-state performance tests should be conducted. Moreover, the boiler operation parameters indicate that the small data acquisition system developed works reliably. The fuel outer pipe continuously and steadily supplies gas with a pressure of not less than 4–8 KPa to the boiler room. The fuel gas must be replaced, and only after passing the detonation test can the next steps be carried out. Drain the water accumulated in the fuel gas pipe through the drain pipeline. 6. The gas system can be put into use only after the above checks confirm it is in order. V. Inspection and testing of electrical instruments: Electrical and instrumentation technicians conduct a thorough inspection of all electrical equipment. Each electric facility operates properly when tested individually; the insulation of motors is in good condition, and all display instruments, signal indicators, control modules, alarm devices, and operation switches are intact and functional. Individual debugging was successful; it operates within the specified operating parameters, with accurate and error-free display. Check the position of the pointer on the pressure gauge being used. When there is no pressure, the pointer of a pressure gauge equipped with a limit pin should be at that limit pin; for pressure gauges without such a limit pin, the value of the pointer away from zero should not exceed the allowable error specified by the gauge. Those that do not meet the requirements should be replaced promptly. And make sure the valve on the pressure gauge connector is in the open position. VI. Inspection of boiler accessories: 1. Safety valves, relief valves, and relief pipes – Whether the safety valves have been adjusted to the specified initial discharge pressure, and whether the installation of the steam exhaust pipes and relief pipes is proper. Check whether the drain pipe is blocked and whether there are anti-freezing measures in place. 2. Check the main steam valve, feed water stop valve, and check valve for any abnormalities in their opening and closing conditions, as well as to ensure that there is sufficient packing on the valve covers. 3. The air valve must remain open from after the hydrostatic test until the tank is filled with water, and from when heating begins until steam is generated. 4. Blowdown valve: Before operation, the boiler’s blowdown valve should be tested; once it is confirmed to be functioning properly, the valve must be closed completely, with no leaks allowed. 5. After inspection, the explosion-proof door should operate smoothly and tightly. VII. Inspection of boiler auxiliary equipment: 1. Inspection and interlock testing of blowers and exhaust fans: The anchor bolts and nuts of the fans and their motors must not be loose, and protective covers should be installed on the drive gears ； The bearing oil level should be normal; when the fan is rotated by hand, there should be no abnormal sounds such as collisions or friction. The fan’s control device for adjusting the dampers should function properly. The protective screens and noise-reduction devices installed on the inlet duct of the blower should be firmly fixed, with proper installation. 2. Inspection of the water supply equipment: Check whether the direction of rotation of the motor is correct, whether the shaft is eccentric or loose, and whether the rubber gaskets of the coupling are worn out. During the trial run, check whether the feed water pump exhibits significant vibration or abnormal noises, and whether the motor’s operating current is normal and stable. Check the packing seal for any water leakage or abnormal temperature rise, as well as whether the rate of water dripping is normal. Check the oil supply to the bearings and whether the oil quality is good. Turn the coupling by hand to check if it works properly. Check that all connections are tight. Check the water supply pipes and valves for any abnormalities, and verify that the water pressure is normal. VIII. Inspection of the economizer: Check for any signs of corrosion inside and outside the economizer. After cleaning it, seal it tightly. A hydrostatic test can be conducted on it if necessary. The specific method is to open the air valve of the outlet header, fill it with water, and allow all air to be expelled until it is completely filled with water. Close the air valve and conduct a water pressure test to ensure that there are no leaks anywhere, especially near the pipe ends. During the hydrostatic test, the safety valve (relief valve) of the economizer can be tested simultaneously; when it is checked or adjusted to the specified opening pressure, the economizer safety valve will activate and discharge. After the aforementioned inspection tests are completed, open the economizer outlet valve. IX. Adjustment of boiler water level: Adjust the water level using the boiler water level gauge. Water should be added when the boiler’s water level is below the normal level, and the drain valve should be opened to release water when the level is above the normal level, so that it reaches the specified normal level. The water level when the boiler is filled with water for the first time should not exceed the normal water level line. Because after the boiler is ignited, the water inside the boiler expands due to heat, causing the water level to rise, and it may even exceed the highest safe water level. Once this occurs, the water level should be adjusted by discharging water. Check whether the water levels indicated by the two sets of gauges are consistent; if not, inspect each set of gauges separately to identify the cause and resolve the fault. If the glass tube of the water level gauge is contaminated and has poor clarity, it must be cleaned or replaced. Section 5: Steps for Starting the Engine – Ignition and Voltage Raising. I. Precautions for ignition: The boiler should be ventilated for 10 to 20 minutes before ignition. Start the exhaust fan; once it is operating normally, start the supply fan and adjust the negative pressure inside the furnace to 30 to 50 Pa. After 10 to 20 minutes of furnace ventilation, the negative pressure in the furnace is adjusted to 20 to 30 Pa before ignition begins. When lighting a boiler, it is prohibited to use oils with high volatility or explosive substances as kindling. The heating rate should not be too fast, especially in boilers with large water volumes and poor water circulation, where the furnace temperature should rise more gradually. The heating time is over 4 hours. When the temperature rises, adjust the water supply in a timely manner according to changes in water level. Pay attention to the cooling protection of the economizer when raising the temperature. During the heating up of the boiler, the expansion values of various pressure-bearing components should be recorded in accordance with the following rules: 1. Record once before filling the boiler with water, after it has been moved or after any maintenance work has been done on its pressure-bearing elements. 2. Record once when a large amount of steam is emitted from the air valve of the boiler drum after ignition. 3. Raise the pressure to 0.2 to 0.3 Mpa, tighten the screws thermally, and record the value once after draining waste from each circulation system. 4. Record once after reaching the working pressure and vaporization. It was found that there were differences in the expansion of each header; the method of draining water from the headers was applied to gradually achieve uniform expansion. II. Pressure raising operation: Steps and methods for pressure raising: 1. After the boiler is ignited, allow a large amount of steam to emerge from the air valve in the boiler drum; then close the air valve to enter the pressure raising phase. When the steam pressure rises to 0.1 Mpa, the water level gauge should be flushed. The steps for flushing the level gauge are as follows: Open the water supply valve to flush the steam and water pathways as well as the glass plate (tube). Close the water supply valve, then flush only the steam pathway and the glass plate (tube). First open the water supply valve and then close the steam valve to flush only the water pathway. Open the steam valve and close the water supply valve. When flushing the level gauge, do not close both the steam and water valves at the same time, to prevent the glass plate (tube) from cooling down rapidly and breaking. After flushing the water level gauge in the above sequence, the water level should rise rapidly with slight fluctuations; otherwise, it should be flushed and checked again. 2. When the air pressure rises to 0.2 to 0.3 Mpa, tighten the bolts of any loose manholes or access holes once more. When tightening bolts, one should turn sideways; the length of all wrenches must not exceed 20 times the diameter of the bolt, and excessive force should be avoided to prevent the bolt from breaking. After tightening the bolts, the water supply system should be tested depending on the water level. If nothing abnormal is detected, the drainage system should be used for inspection; the drainage valves of the boiler drum and each lower header should be opened in sequence to check whether they operate smoothly and tightly. 3. Once the boiler’s operating pressure reaches the desired level, flush the water level gauge once again. The drum safety valve is used to maintain a constant pressure. The setting of the pressure for the safety valve should be carried out by maintenance personnel (or the installation unit), with the assistance of operating staff and the participation of the person in charge of safety and technology; the results of this pressure setting should be recorded and archived. III. Steps and methods for steam supply operation: During the process of raising the boiler pressure to the level required for steam supply, it is necessary to warm the pipes. This warming is usually carried out when the boiler pressure reaches two-thirds of the operating pressure (when the boiler is operating alone, warming the pipes and raising the pressure can be done simultaneously). The operation steps are as follows: 1. First, open all the drain valves on the main steam pipeline and the steam drum to discharge the condensed water accumulated in the pipeline. 2. Slowly open the main steam valve of the boiler; once it is fully open, turn it back half a turn to prevent it from getting stuck due to thermal expansion. 3. When dry steam is seen being discharged from the steam trap, the pipe warming process can be completed, and the steam trap should be closed. During the pipe warming process, it is necessary to check the condition of the pipe supports and expansion joints. If any abnormalities are detected, the warming process should be stopped to identify the cause; the fault must be resolved before continuing with the warming process. The warming time for pipes depends on the type of pipe and the actual conditions; for steam pipes in a cold state, the warming time is generally not less than 2 hours ； The heating time for hot steam pipes is generally 0.5 to 1 hour. The heating rate of high-pressure steam pipes can be controlled at 2 to 3 degrees per minute. Once the pipe warming process is complete, steam supply can begin: steam supply is possible when the boiler’s steam pressure is 0.05 Mpa lower than the system’s steam pressure, and the water level is at the normal level. After the second main steam valve (near the steam drum) is slowly opened to full position, it should be turned half a turn, and finally the drain valve should be closed. After steam is supplied, an automatic water supply device is activated to control the water level. For the boiling economizer, open the recirculation valve when filling water before supplying air to the boiler. Close the recirculation valve only after steam supply is normal and continuous water feeding has resumed. Operation of a boiler during normal operation: When a boiler is running normally, the most important aspect of operation is to maintain a stable water level in the boiler and keep the pressure inside it constant; it is also necessary to adjust the combustion process regularly. To achieve the above objectives, even with complete automatic control devices, operators must continuously monitor the operating condition of the boiler. Adjustments during operation: I. Adjustment of boiler water level: 1. The boiler feedwater should be supplied evenly, and the boiler water level must always be maintained within the specified range for the upper drum. There should be slight fluctuations in the water level, with the upper and lower limits defined in the boiler’s operating instructions. Under normal operation, it is generally not allowed to interrupt the boiler feed water. When switching feed water pumps, the standby pump should be started first and confirmed to be operating properly before shutting down the faulty pump. 2. The boiler feed water should be adjusted according to the indication of the upper drum level gauge. The boiler water level can be adjusted based on the indication of the low-level gauge only when the feedwater automatic regulator, the two low-level gauges, and the water level alarm are functioning properly. 3. When the feedwater automatic regulator is in operation, it is still necessary to regularly monitor the water level changes in the upper drum, and check whether the feedwater flow rate matches the steam flow rate. 4. During operation, it is necessary to ensure that both level gauges remain in good condition, showing accurate readings, being clearly visible, and having adequate lighting ； According to the regulations, the water level gauges should be flushed at least once or twice per shift. After flushing, both gauges should indicate the same value; otherwise, the cause must be identified and addressed ； The low-level gauge and the drum water level gauge should be compared at least once per hour ； The high and low water level alarms should be sensitive and reliable. II. Adjustment of steam pressure: Adjust combustion in a timely manner according to changes in load, in order to maintain stable steam pressure. When increasing or decreasing the fuel in the boiler, the air volume should be adjusted accordingly to maintain optimal combustion conditions. When the boiler is in operation, there should be records of the safety valves opening due to overpressure. For safety valves that fail to reach their operating pressure over an extended period (more than three months), a regular manual test to release steam should be conducted. Maintain manual testing of the safety valve once a week. When the load increases, the steam pressure drops and the water level rises, it is necessary to closely monitor the water level, increase the amount of fuel and air to enhance combustion, raise the evaporation rate, and thus stabilize the steam pressure and water level ； When the load increases, the steam pressure drops and the water level is low, it is necessary to first increase the amount of fuel and air supplied, gradually raising the water supply volume to maintain normal steam pressure and water level. When the load decreases and the steam pressure rises, and when the water level is low, it is necessary to closely monitor the water level and adjust the water supply in a timely manner to maintain a normal and stable water level; the amount of fuel and water supplied should be adjusted according to the steam pressure and load conditions ； When the load decreases, the steam pressure rises and the water level is high, the feedwater supply is first reduced while adjusting the fuel and air supply amounts to weaken combustion. a) Adjustment of combustion: Combustion is the key operational process for maintaining stability in steam pressure, steam temperature, and evaporation rate. When adjusting combustion, pay attention to the following points: 1. When increasing the boiler’s evaporation rate, air should be added first, followed by fuel ； When reducing the boiler’s evaporation rate, fuel should be reduced first, followed by air. 2. During normal combustion, the flue gas temperatures on both sides of the boiler furnace should be balanced. 3. During normal operation, the negative pressure in the combustion chamber of a negative-pressure boiler should be maintained between 10 and 30 Pa (as indicated by the absence of smoke at the top of the boiler); operation at positive pressure is not allowed. 4. During operation, it is necessary to regularly monitor the changes in the temperature of various parts of the boiler as well as the flue gas resistance. During operation, it is also necessary to regularly check for air leaks in the boiler; all viewing doors, manholes, etc. must be closed tightly, and any air leaks detected must be addressed by taking appropriate measures. 5. During the operation adjustment of boilers, three practices should be followed: frequent inspections, frequent communication, and frequent adjustments. Four stabilities: stable temperature, stable evaporation rate, stable pressure, and stable water level. IV. Boiler blowdown: To maintain cleanliness inside the heating surfaces and prevent deterioration in the quality of the boiler water from affecting the quality of steam, blowdown should be carried out as follows: 1. The timing of blowdown and the amount of water to be drained should be determined based on the results of tests. 2. When discharge is required (periodic discharge), the isolation valve (the valve located near the boiler or header) should be opened first, followed by slightly opening the control valve (the second valve) in order to preheat the discharge pipeline; after preheating, the control valve can be gradually opened further. The drainage time for a single operation of a drain valve shall not exceed 30 seconds. After discharging waste, close the adjustment door first, then the isolation door. 3. When draining wastewater, close attention should be paid to the water level in the boiler; if any abnormality is detected in the water level, drainage should be stopped immediately. 4. One must stay focused during the waste discharge process, and after it is complete, check the tightness of each waste discharge valve individually. 5. After the discharge is completed, detailed records of the discharge time and the operator should be kept. Section 7: Parking Procedures – Operation for Shutting Down the Furnace. I. The operation for normal shutdown (planned shutdown) is carried out as follows: 1. Inform all departments that use steam and the relevant personnel. Inspect the boiler and its auxiliary equipment, and record the inspection details thoroughly. 2. Gradually stop the fuel supply at the specified time, and reduce the volume of supply air and exhaust air. 3. Open the circulating water valve at the economizer outlet, but assign a dedicated person to monitor the water level and keep it slightly above the normal level. For those with a recirculation pipe from the boiler drum to the economizer, open the recirculation water valve; close it during water filling, and open it immediately after the water has been filled. Prevent the economizer from being damaged due to overheating. 4. Stop the supply and exhaust fans based on the temperature drop inside the furnace, to prevent the combustion equipment from being damaged due to lack of cooling. After the exhaust fan stops, it is necessary to tightly close the flue dampers and the furnace door. Once the temperature has dropped naturally and the temperature of the furnace water is below 70 degrees, the furnace water can be drained. II. Situations requiring emergency shutdown of the boiler and methods for handling them: An emergency shutdown of the boiler is required in any of the following situations: 1. The steam pressure in the boiler rises rapidly, exceeding the maximum allowable pressure; despite measures such as reducing combustion and the use of safety valves to release steam, the pressure continues to rise ； 2. When the boiler water level drops rapidly, and it cannot be maintained even though the feed water supply is increased. 3. When the boiler water level is below the lowest visible edge of the water gauge, and the water level cannot be seen even after calling for water. 4. When the boiler water level rises rapidly and exceeds the maximum allowable level, and continues to rise even despite increased drainage efforts ； 5. When all water supply facilities fail ； 6. When the water level gauge, safety valve, and pressure gauge are completely malfunctioning ； 7. When the combustion equipment is damaged, the furnace wall collapses, the boiler frame gets red-hot, etc., posing a serious threat to the safe operation of the boiler ； 8. When serious deformation, tube rupture, leakage is detected in the pressure-bearing components of the boiler, posing a threat to safe operation ； 9. When a gas explosion or secondary combustion occurs in the flue, posing a serious threat to the safety of the boiler and the operators ； 10. In the event of a fire in the boiler room or in an area nearby that could spread to the boiler room, the boiler should be shut down immediately. 11. Other abnormalities pose a threat to the safe operation of the boiler. The emergency shutdown of the furnace should be carried out in the following order: 1. Quickly cut off the fuel, stop the supply fan, and reduce the speed of the exhaust fan (increase the exhaust fan speed in case of a tube rupture); if necessary, slightly open the furnace door to lower the temperature inside the furnace. 2. In the event of a shutdown that is not due to severe water shortage, the normal water level should be maintained ； In case of severe water shortage, the furnace must be shut down urgently; feedwater supply is strictly prohibited ； 3. Close the main steam valve and open the relief valve to release steam and reduce pressure (reducing pressure by releasing steam should not be done in cases of severe water shortage). 4. Make detailed records after the emergency shutdown procedure is completed. Section 8: Handling of Abnormal Conditions – Handling of Common Boiler Accidents. Common boiler accidents include: 1. Economizer failures. When an economizer is damaged, the following symptoms occur: 1. The water level indicated by the boiler gauge drops, or the water supply volume is abnormally high compared to the evaporation rate ； 2. There are noises near the economizer; steam leakage and moisture occur at the cracks in the furnace wall as well as at the bottom of the economizer ； 3. The temperature difference of the flue gas on both sides of the economizer increases (the temperature on the leaking side is lower). Handling when the economizer is damaged: 1. Isolate the economizer by opening the bypass flue damper and closing the flue gas inlet damper of the economizer. Water can be supplied directly into the furnace without going through the economizer; to do this, open the boiler’s direct feed water valve and close the economizer’s feed water valve ； 2. After using the economizer bypass flue, ventilation should be adjusted to maintain an appropriate negative pressure in the furnace ； 3. For a faulty economizer, once it is isolated from both flue gas and feedwater, water should be drained promptly if necessary ； 4. If the smoke inlet and outlet dampers of the economizer are airtight and leak-free, repairs to the economizer can be carried out while the boiler is in operation; however, these repairs must be done under conditions that ensure personal safety, and the economizer should then be put back into use. If repairs cannot be carried out while the boiler is running, it should be shut down as soon as possible for maintenance. II. Water shortage incidents: Symptoms of water shortage incidents: 1. The water level is below the minimum safe level, or the water level is not visible; the glass tube of the water gauge turns white ； 2. The high and low water level alarms emit alarm signals. 3. The water supply is less than the evaporation rate. If water shortage occurs due to the rupture of furnace tubes or economizer tubes, the opposite phenomenon occurs ； 4. A burnt smell can be detected in cases of severe water shortage ； Reasons for water shortage incidents: 1. Inadequate monitoring of water level by operators, along with errors in judgment and operation. 2. The steam-water connection pipe of the water level gauge became blocked, resulting in a failure of the water level alarm; as a result, the operators failed to detect the false water level in time. 3. Failure of water supply machinery, malfunction of automatic water supply regulation ； 4. Leakage in the drain valve or improper operation of the drain function. Method for handling water shortage incidents: In cases where the water level in the gauge is below the lower visible edge and the level cannot be seen even after calling for water, an emergency shutdown of the boiler should be carried out. If the water level does not drop below the lower edge of the gauge, increase the water supply to restore the level to normal. III. Flood Accident Symptoms of a flood accident: 1. The water level is above the maximum level mark, and the water level alarm emits a high-level alarm signal ； 2. The water supply volume is abnormally higher than the steam flow rate. In severe cases, water hammer occurs in the steam pipes. Reasons for full water level: 1. Inadequate monitoring of the water level by the operators, incorrect adjustments, or the occurrence of a false water level reading ； 2. The water level alarm is malfunctioning, and the automatic water supply control system is also malfunctioning. Methods for dealing with a full-water accident: 1. Immediately flush the water level gauge; if a full-water accident is confirmed, quickly close the feedwater valve and open the economizer recirculation valve or the bypass flue to prevent damage to the economizer. 2. Open the drain valve to increase drainage, but the water release time should not exceed 30 seconds (for one valve). When releasing water, pay close attention to the water level in the gauge to prevent water shortage accidents caused by excessive discharge. 3. Close the air damper to reduce fuel and air supply, thereby weakening combustion. 4. Open the drain valves on the steam cylinders and steam main pipes. 5. Once the water level returns to normal, resume normal combustion and bring the system back into normal operation. IV. Azeotrope formation in soda water: Phenomena of azeotrope formation: 1. The water level inside the gauge fluctuates violently, with a large number of bubbles and foam appearing, making it impossible to see the actual water level. 2. Water hammer occurs in the steam pipeline, resulting in steam leakage and water leakage at the flange connections. Reasons for soda water azeotropy: 1. Poor quality of boiler water, with excessive levels of oil, salts, and suspended impurities ； 2. Wastewater was not discharged in accordance with regulations ； 3. When the load increases suddenly or units are connected, the steam pressure in the new boiler is higher than that in the steam main, causing a large amount of steam to escape from the boiler. Treatment methods for soda water azeotropy: 1. Water treatment personnel should take effective measures to improve the quality of boiler water and increase the frequency of analyses of it. The boiler load shall not be increased until the quality of the boiler water improves ； 2. Fully open the surface blowdown valve of the boiler drum; at the same time, carry out appropriate bottom blowdown, increase the feed water supply, and maintain a normal water level in order to reduce the salt content in the boiler water ； 3. Open the drain valves on the steam lines and steam distributors. 4. After the accident is resolved, the water level gauge should be flushed to restore normal operation. If the accident persists despite the above measures, it is necessary to report it immediately to the relevant supervisors in order to decide whether to shut down the furnace. V. Damage to the water level gauge glass tube (plate) Causes of damage: 1. Poor quality of the glass tube (plate). When cutting the glass tube, fine cracks were formed at the end. 2. The upper and lower packing on the glass tube is too tight, or the upper and lower packing glands are not aligned during installation. 3. When using a new glass tube, it was not properly preheated, and the operation for adjusting the flushing water level was incorrect. 4. During normal operation, when exposed to cold water droplets or suddenly in contact with cold air. Handling methods and precautions: 1. When preheating new glass tubes, first slightly open the steam and water valves. Once moisture appears inside the tube, then slightly open the water valve to discharge the mixture of steam and water. After that, slowly close the water valve, gradually moving the steam and water valves to their normal positions ； 2. If both level gauges are damaged at the same time, the furnace should be shut down urgently, and new glass tubes should be installed. 3. If one gauge is damaged, the other gauge should be used to monitor the water level, and emergency measures should be taken to repair the damaged gauge. 4. When replacing the glass tube of the water level gauge, the steam and water valves should be closed, and the drain valve should be opened. VI. Secondary combustion in the flue: Phenomena of secondary combustion in the flue: 1. A sharp increase in exhaust gas temperature, a decrease in negative pressure in the flue or the formation of positive pressure; sometimes the explosion-proof door at the rear operates ； 2. The smoke turns abnormally black, and in severe cases, sparks are emitted. Reasons for secondary combustion in the flue: 1. Improper adjustment of fuel and air volume ； 2. Improper ignition or shutdown procedures led to the accumulation of large amounts of combustible material in the furnace and flue ducts ； 3. Prolonged operation at low load results in a very low flue gas flow rate, leading to the accumulation of large amounts of combustible material within the flues ； 4. Excessive negative pressure in the furnace causes unburned combustible materials to be drawn into the flue. Handling method: 1. Immediately stop feeding fuel into the furnace and shut down the furnace urgently ； 2. Close the flue dampers, air dampers, and all access doors; ventilation is strictly prohibited ； 3. Steam can be injected into the flue, or a carbon dioxide fire extinguisher can be used to put out the fire ； 4. After the accident is resolved, carefully inspect the equipment; if nothing is abnormal, ventilate it for 10–20 minutes first, then ignite it in accordance with the operating procedures. VII. Water hammer in the boiler drum, pipes, and economizer. Symptoms of water hammer: 1. Knocking sounds and vibrations inside the boiler drum or pipes. 2. When water hammer occurs in the economizer or water pipes, the gauge pointer moves rapidly and significantly. Reasons for water hammer in the boiler drum: 1. The water level in the boiler drum is too low, or the flange connections between the feed water pipes and the water tank are not secure; the check valves on the feed water pipes are malfunctioning or not properly sealed, allowing steam to flow into the feed water pipes. 2. The flanges connecting the steam heating tubes inside the boiler drum are loose, or they are installed in an incorrect position. Solutions: 1. Check the water level in the boiler drum; if it is too low, increase the feed water volume to the normal level ； 2. Water should be added to the boiler drum in a uniform and steady manner ； 3. During shutdown inspections or maintenance, pay attention to eliminating defects in the steam heating equipment inside the lower drum and in the flanges of the feed water tank in the upper drum. Causes of water hammer in the water supply pipes: 1. Air or steam present in the water supply pipes, and malfunctioning of the water supply check valve; 2. Excessively high water supply temperature or vaporization. Solution: 1. Activate the backup water supply pipeline and repair the faulty check valve on the main water supply pipeline to ensure its proper functioning ； 2. Reduce the feedwater temperature. Reasons for water hammer in steam pipes: 1. Insufficient pipe warming and drainage before steam is supplied ； 2. The main air valve or the valve in the air supply pipeline is opened too quickly when supplying steam ； 3. An excessive rapid increase in load, or a full boiler and steam-liquid azeotrope, cause steam to carry water into the pipes. Solution: 1. Turn on the steam trap on the steam pipeline to drain water ； 2. Check the water level in the boiler; if it exceeds the specified limit, it should be reduced to the normal level ； 3. Improve the quality of the feed water, increase wastewater discharge appropriately, and prevent azeotrope formation. Reasons for water impact in the economizer: 1. The air inside the economizer was not exhausted when starting the fire ； 2. The outlet temperature of the economizer is too high, resulting in localized vaporization ； 3. The check valve on the economizer feedwater pipeline is not functioning properly, causing inertial shock to the feedwater. Solution: 1. Close the main flue and open the bypass flue ； 2. Slowly open the economizer air valve to discharge the air ； 3. Optimize the economizer recirculation conditions; the boiler uses continuous feedwater ； 4. Repair the check valve to ensure it functions properly. VIII. Sudden Power Outage: In the event of a sudden power outage, the emergency shutdown procedure should be followed. Close the main steam valve and maintain the water level. Monitoring during boiler operation: The main tasks of monitoring boiler operation are: (1) to maintain the boiler’s evaporation rate within the rated value, and (2) to meet the required demands. (3) Maintain normal steam pressure (operating under overpressure is strictly prohibited). (4) Balance the inflow water to maintain a normal water level. (5) Ensure that the quality of saturated steam is satisfactory. (6) Maintain good combustion, (7) improve thermal efficiency. Section 9: List of Main Equipment 1. Drum and Steam-Water Separation Device: The system uses a double-drum design; the inner diameter of the upper drum is Φ1400mm with a wall thickness of 42mm, while the inner diameter of the lower drum is Φ900mm with a wall thickness of 30mm. The primary separation device inside the upper drum is an underwater orifice plate, while the secondary separation device is a corrugated plate separator. The normal water level in the boiler drum is 50 millimeters below the center line of the drum; the highest and lowest water levels are 75 millimeters above or below the normal water level. 2. Furnace chamber and water wall: The cross-section of the furnace chamber is square, with dimensions of 3500×3500 mm. The burners are located on the front wall, and the membrane-type water wall on each wall is composed of Φ51 tubes and flat steel. Water is drawn out from the lower drum through 12 Φ108×4.5 downcomers, passes through the membrane water wall in the furnace, and then is introduced into the upper drum via 12 Φ108×4.5 steam guides. 3. Combustion equipment: Two burners are provided to ensure the temperature field and combustion conditions required for complete combustion of furnace gas. 4. Convection tube bank: The convection tube bank is arranged in a straight row and consists of tubes with a diameter of Φ51×3; the tubes in this bank are joined to the upper and lower drum sections by expansion joints. 5. Economizer: A steel tube economizer is used, consisting of tubes with a diameter of Φ32×4. Water enters the economizer from the water inlet header in the opposite direction to the flue gas flow, and then flows into the upper drum via the water outlet header. 6. The air preheater is arranged in a single stage, with a tube diameter of Φ50×1.5; the flow directions of the air and flue gas are perpendicular to each other. A maintenance space along with corresponding door openings are provided between the economizer and the air preheater to facilitate maintenance. 7. Blower: Model 9-26 No12.5D; Flow rate = 22206–30533 m3/h; Pressure = 4179–3921 Pa; Motor power N = 45 KW, 1 unit.
8. Exhaust fan: Model YG20-12.4D; Flow rate = 83013–45104 m3/h; Pressure = 4120–2780 Pa; Motor power = 110 KW, 1 unit.
9. Water pumps: Model DG25-50*10; Flow rate = 15–30 m3/h; Head = 525–475 m; Motor power = 75 KW, 2 units.
10. Chimney: Diameter Φ1000 mm, height 20 meters.

Section 10: Main control parameters
Rated evaporation capacity: 20 t/h
Rated evaporation pressure: 3.82 MPa
Rated steam temperature: 249°C
Feedwater temperature: 105°C
Flue gas temperature: 150°C
Water test pressure: 4.78 MPa
Dust emission concentration: <50 mg/m3
Oxygen content in feedwater: Below 15 micrograms/liter