Methanol Cracking Hydrogen Production Technology Operating Procedures

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Operating procedures 1 Preparation before start-up 1.1 General preparation and inspection 1. Check the supply of water, electricity, steam, soft water, instrument air, nitrogen, hydrogen, fuel, etc., and contact relevant departments to implement supply quantity and quality requirements. 2. Close all drain valves, drain valves, vent valves, feed valves, and sampling valves. Open the main valve of the cooling water, instrument air, etc. inlet section. 3. Notify the thermal oil boiler room to prepare for start-up, and contact to determine the specific start-up time and quality and quantity requirements (pressure, temperature, flow, etc.). 4. Notify the analysis room to prepare for production control analysis work. 5. Check the integrity of the power equipment and check whether the power supply, air source and signal of all instruments are normal. 6. Identify product users. Because the conversion catalyst does not want to stop frequently midway, if the user does not confirm, do not rush to drive. 7. Check whether the fire protection and safety facilities are complete and complete. 8. Operators, analysts, management and maintenance personnel must undergo technical training and pass the assessment before they can take up their posts. 2 Start-up operation procedure The feed start-up procedure should be carried out after the catalyst reduction is completed, without any time interval. The driving sequence is generally: The water tower is started, the gasification tower is started, the reformer is started, and the system is boosted. After the reduction is completed, close the reduction system valve, open the reformer until all valves between the vent lines are vented, close the relevant valves, and prepare the system to start up. Notice: The starting load is generally 30% to 60% full load, and will be gradually increased to full load after the system stabilizes. 2.1 Preparation 1. Check whether the tools and protective equipment are complete. 2. Check whether the power equipment is normal, refuel the lubrication points according to regulations, and turn the engine several times. 3. Check whether all measurement and control instruments are malfunctioning, accurate and intact, and turn on the power supply and air source switch of the instrument. 4. Notify the methanol warehouse and desalted water station to send raw materials to this device. Let the liquid level of the methanol intermediate tank and desalted water intermediate tank reach ~90%, and stop feeding. 5. All valves and instruments of the catalyst reduction system remain in their original driving state. 6. Inform the thermal oil furnace process and prepare for start-up. 7. Determine the amount of material to be fed during startup and clarify the relationship between the amount of material to be fed and each parameter. 2.2 Start up the water tower 1. Open the discharge valve of the desalted water intermediate tank, the inlet valve of the desalted water feed pump, and the bypass valve, and start the feed pump to make the desalted water pump operate normally. 2. Open the desalted water feed and outlet valve of the pump, close the desalted water feed bypass valve, and use the regulating valve to adjust the return flow so that the flow reaches the required value. 3. When the liquid level appears in the water washing tower kettle, open the bypass valve of the tower kettle discharge regulating valve, send desalted water to the circulating liquid storage tank, and then open the front and rear regulating valves to control the water washing tower liquid level at 30 to 40%. 2.3 Start up the vaporization tower 1. Open the outlet valve of the methanol intermediate tank, the front and rear valves of the methanol flow meter, and the outlet valve of the circulating liquid storage tank to mix water and methanol. Open the inlet valve of the methanol feed pump, the bypass valve, and start the pump to make the methanol feed pump operate normally. 2. Open the outlet valve of the methanol feed pump, close the bypass valve of the methanol feed pump, and adjust the feed pump scale to deliver water methanol to the system. Take samples for analysis at the sampling point, and adjust the flow rate of raw methanol to make the water-to-methanol ratio reach the required value. 3. When the liquid level in the vaporization tower kettle reaches 10%, open the vent valve at the top of the vaporization tower, slowly open the bypass valve, front and rear valves of the heat transfer oil inlet valve of the vaporization tower, and use the regulating valve to adjust the amount of heat transfer oil entering the vaporization tower. When the exhaust gas volume at the top of the tower is stable, open the blowdown valve at the bottom of the superheater. When no liquid beads are discharged, close the blowdown valve and then transfer to the reformer and start up. 2.4 Start up the reformer 1. Open the inlet valve of the reformer and close the vent valve at the top of the vaporization tower to send water, methanol and raw gas to the reformer. 2. Stabilize the temperature of the thermal oil furnace to 230°C, check whether the equipment, pipelines, valves, instruments, etc. are operating normally, and observe the relationship between various process parameters. If there are no abnormalities, the system can be boosted. 2.5 System pressure increase 1. Open the front and rear valves of the flow meter, close the bypass valve, open the system pressure regulating valve and its front and rear valves, and close the bypass valve. Slowly close the valve to increase the system pressure until it reaches 1.1MPa. Notice: It is necessary to ensure that the raw material gas passes through the catalyst bed in an appropriate amount, so the system pressure regulating valve cannot be fully closed. 2. Adjust the opening of the system pressure regulating valve to stabilize the system pressure and converted gas volume. 3. Check the feed amount of raw material liquid and its water-to-methanol ratio to ensure that it reaches the required value. ； Check the amount of converted gas, adjust the flow of heat transfer oil into the lower part through the valve, and control the liquid level of the tower kettle at 15-40%. 4. Adjust to stabilize the desalted water volume of the inlet water washing tower and reach the required value to stabilize the liquid level. At this time, the system feeding and start-up work has been completed. Observe the operation of the entire system. If there are no abnormalities, you can perform the following operations to bring the system to normal operation. 2.6 System stability 1. Check the cooling water volume of the cooler to ensure that the temperature of the converted gas entering the water washing tower is ≤40°C. 2. Check the composition of the converted gas at the outlet of the buffer tank, adjust the water-to-methanol ratio, and control the carbon monoxide, methanol, water and other components in the converted gas outlet to reach the required values. 3. After the operation of the whole system is stable, the reformed gas can be delivered to the PSA-H2 device in the rear section. 3. Normal operation After the whole system is started, it can be gradually transferred to normal operation. 7.3.1 Establishment and maintenance of normal operating status 1. Make appropriate adjustments to each control parameter based on the feed volume of raw material liquid, conversion gas flow, water-to-methanol ratio, evaporation tower liquid level, heat transfer oil temperature, conversion gas composition, circulating liquid composition and parameters of each control point, so that the system operation is within the normal range. 2. Determine the methanol flow rate according to the required conversion gas volume and water-to-methanol ratio, and put the regulating valve into automatic adjustment. 3. According to the required desalted water flow, put the regulating valve into automatic adjustment. 4. According to the required conversion gas volume and water-methanol ratio, adjust the raw liquid feed pump flow. 5. According to the circulating fluid flow, put the regulating valve into automatic adjustment. 6. Adjust the water inlet valve of the cooler so that the temperature of the converted gas is below 40°C. 7. When the system conversion air flow is stable, put the system pressure regulating valve into automatic adjustment. 8. According to the required conversion gas volume and composition, appropriately adjust the temperature of the heat transfer oil entering the system. 9. A small amount of wastewater is continuously discharged from the drain valve at the bottom of the vaporization tower, and the discharge volume is controlled at 15.0~20.0Kg/h. The whole system is in normal and stable operation. When the system is in normal operation, record all operating parameters on time and patrol to check whether each control point, equipment, instruments, valves, etc. are in normal condition. If any abnormality is found, the cause should be identified immediately, handled in a timely manner, troubleshooting, and maintain the normal operating status of the system. 3.2 Normal shutdown operation 1. Stop the heating of the thermal oil furnace and maintain the circulation of the thermal oil. After the reaction temperature drops below 200°C, the thermal oil furnace room stops sending thermal oil to the gas generating device, that is, the internal short-circuit valve of the thermal oil device is opened. Thermal oil furnace parking shall be carried out according to the thermal oil furnace parking requirements. 2. While the thermal oil furnace is cooling down, manually adjust the system pressure regulating valve to slowly reduce the pressure of the system to 0.4Mpa (or open the gas buffer tank, the converted gas can be replaced by the spare reformer, and open the vent valve at the top of the water washing tower to reduce the pressure). 3. Close the valve entering the reformer, slowly open the vent valve at the top of the vaporization tower, and reduce the pressure of the system in front of the vaporization tower to normal pressure. 4. While depressurizing the vaporization tower system, stop the raw material feed pump and stop feeding the system. 5. The system after the reforming furnace continues to reduce the pressure. When it drops to 0.2Mpa, close the front and rear valves and bypass valves of the reforming furnace. 6. Stop the desalted water pump and stop sending desalted water to the water washing tower. Close the drain valve of the water washing tower kettle. 7. Use nitrogen or gas buffer tank reforming gas to replace the front and rear sections of the reformer. Considering the impact of cooling on the system pressure, it is best to use nitrogen or hydrogen to maintain the pressure of the system to 0.2Mpa. After the heat transfer oil drops to a certain temperature as required, stop the heat transfer oil circulation pump. If the system is shut down for a long time, use pressurized nitrogen to press the thermal oil from the system back to the thermal oil storage tank. 8. Perform protective operations or passivation treatment on the catalyst. 3.3 Emergency stop operation 1. Emergency stop operation should be carried out in any of the following situations:: ⑴ power failure. ⑵ Stop the cooling water. ⑶ Equipment and pipelines exploded, broke, and caught fire. ⑷ Serious air or liquid leaks from equipment, pipes or flanges cannot be dealt with. ⑸ Important control instruments failed. 2. Operation steps ⑴ Urgently notify the heat transfer oil device to stop heating, open the internal short-circuit valve of the heat transfer oil device, and stop sending heat transfer oil to the gas generating device. ⑵ Close the front valve of the reformer and cut off the vaporization tower system and reaction system. The system should be properly depressurized after the reformer. The vaporization system maintains pressure stability. ⑶ Stop the raw material feed pump. ⑷ Stop the desalted water feed pump. ⑸ Implement special protection operations for the catalyst. ⑹ Further processing will be carried out after the cause of the accident is identified.