Ammonia synthesis tower operation method or procedures

Synthetic tower post operation procedures 1. Position operation method (1) Tasks of the post This post is the last process in the production of synthetic ammonia. A certain proportion of purified and refined hydrogen and nitrogen mixed gas will be synthesized into ammonia through the catalytic action of the catalyst under high temperature and high pressure. (2) Brief description of the process flow: The gas comes from the cycle machine, is cooled by the 1# condensation tower, enters the new ammonia cooler, enters and exits the original ammonia cooler for cooling, comes out and merges with the fresh gas, enters the 2# condensation tower to separate the residual liquid ammonia, enters the 1# condensation tower for heat exchange, the temperature rises, and enters the synthesis tower body in two streams. The primary exit enters the heat exchanger outside the tower, and the secondary exit enters the synthesis tower. The synthetic gas comes out from the secondary outlet of the tower and enters the middle pot for heat exchange. The middle pot comes out and enters the heat exchanger outside the tower. It comes out and enters the water cooler for cooling. After cooling, the gas enters the ammonia component to separate most of the liquid ammonia. It comes out and enters the circulation machine for the next circulation machine. The separated liquid ammonia is decompressed by the manual regulating valve (or automatic regulating valve) of the liquid level gauge and enters the ammonia main pipe and flows into the ammonia storage for measurement. (3) Chemical reaction 3H+N2======NH3+Q occurs in the synthesis tower (high temperature, high pressure, catalyst, exothermic, reversible) (4) Main equipment specifications serial number name specification remarks 1 diameter of the shell of the synthesis tower: Φ1000mm, effective height: 13800mm catalyst basket diameter: Φ934×16, upper catalyst height: 5582mm, lower: 578mm cold pipe diameter: Φ44×2.5, Φ29×2.5, Φ22×1 each with 62 heat exchange areas: E=40m2, heat exchange height: 236mm, 3084 tubes Φ10×1.5, heat exchange area: 224m2, voltage regulator power: 650V, 710A, 800KVA, catalyst loading capacity: 15t, 3m3 2 condensation tower shell diameter Φ900, height: 8210, double-layer tube heat exchanger F=165m2 1# condensing tower 2# only plays a separation role 3 Ammonia cooler 628 Φ25×4 tubes, tubes with header, heat exchanger F=226m2 2 units 4 ammonia separator shell diameter Φ1000 height H=4625mm 1 unit 5 water cooler horizontal casing heat exchanger F=199m2 3 units (5) Operation method 1. Normal start-up (1) Preparation work Check whether the system equipment, pipes, and valves are firmly connected, whether the blind panels are disassembled and assembled correctly, and whether water, electricity, and gas can be supplied normally. Contact an electrician or instrument technician to check whether the electrical appliances and instruments are in good standby condition. Check whether the protection, fire-fighting equipment is complete and usable, and whether the lighting is suitable for driving. (2) Exhaust replacement inspection valve: Oil filter outlet large valve, high pressure machine section water cooler inlet and return valve (more than two valves), gas ammonia production, main pipe large valve, fresh gas vent valve. Valve should be closed: Fresh balloon valve, fresh gas large valve, system short-circuit valve, synthesis tower inlet main and auxiliary valves, ammonia separator inlet ball valve, 1#, 2#, 3# cycle machine inlet and outlet large valves, vent valves before and after the tower, ammonia delivery valves and ammonia adding valves. Contact the high-pressure machine and 8.13 to send the six-stage gas. First, exhaust the fresh gas main pipe, and then close the fresh gas vent valve. Open the fresh balloon valve, the large fresh gas valve and the vent valve in front of the tower, exhaust the air in front of the tower, take an O2 analysis of ≤0.2% to pass, and then close the vent valve in front of the tower. Open the main inlet valve of the synthesis tower, the ammonia separator inlet ball valve and the post-tower vent valve to vent the post-tower exhaust. The purge pressure should not exceed 2.0Mpa and the purge time should be 5 minutes. During pressurization and exhaust, when the pressure is greater than 2.1 MPa, open the ammonia delivery ball valve and notify the ammonia warehouse to open the main ammonia delivery inlet. Check for leaks at the same time. (3) Leak test: After the exhaust replacement is qualified, close each vent valve and use fresh air to perform a leak test on the entire system. Check for leaks at 10, 20, 25, 31.5 MPa, and pressurize 4 MPa per minute. If a leak is found, the pressure must be relieved to below 5 MPa before being handed over to the maintenance workshop fitter to tighten the bolts and re-test for leaks until it is qualified. After passing the leak test, use the vent valve behind the same tower to relieve the system pressure to 6-8 MPa, and prepare the circulation machine and electric furnace for temperature rise. (4) The temperature rise makes the system valve in the following state: Valve should be closed: Synthesis tower inlet auxiliary valve, fresh gas valve, ball valve, ammonia delivery stop valve, ammonia adding valve, vent valve and oil and water drain valve, circulation machine ball valve. Valve should be opened: Synthesis tower inlet main valve, system short-circuit valve, ammonia separation inlet ball valve, cycle machine inlet and outlet valve, cycle machine auxiliary valve. Open the inlet and outlet ball valves of the circulation machine, put the circulation machine into the system, and use the circulation machine line valve and the system short-circuit valve to check the circulation volume. When the electrician turns on the electric furnace, the first voltage increase is less than 50V, and each subsequent voltage increase cannot exceed 20V. When using the electric furnace, pay attention to whether it is grounded or short-circuited. Feel free to get in touch with your electrical staff. If any abnormality is found in the electric furnace, the voltage should be stopped immediately, or the voltage should be reduced until the electric furnace is stopped. It is absolutely necessary to ensure that the electric furnace has enough safe gas volume to prevent the furnace wire from overheating and burning out. When the cycle machine trips, immediately cut off the power supply to the electric furnace. Strictly control the heating rate within the index range. The temperature difference between the same plane of the catalyst shall not exceed 10℃. The temperature rise of the electric furnace should, in principle, be operated with large circulation volume and large electric furnace power to ensure sufficient safe gas volume. When the hot spot temperature reaches 100°C, add water to the water cooler. When the hot spot temperature reaches 350°C, add ammonia to the ammonia cooler. At the same time, pay attention to the fact that the liquid ammonia level in the ammonia cooler cannot exceed the indicator. After the temperature reaches 400℃, you can use a high-pressure machine to start air supply or slowly open the "69" communication valve connected to 8.13 until the pressure is balanced and then fully open the valve for production. During the process of opening the valve, the central catalyst temperature rises sharply and exceeds the target, which is controlled by the circulation volume. The pressure is charged and the electric furnace load begins to be reduced at the same time. After the reduction is completed, the electric furnace is stopped after the catalyst and temperature are all normal and normal production is resumed. (5) Operation method of pressurizing and heating up. After short-term parking, the hot spot temperature is above 380°C. Depending on the catalyst activity, fresh gas can be used for pressurization, and the reaction heat can be used to raise the catalyst temperature to normal. (If the tower is shut down due to trace amounts of poisoning, it is forbidden to pressurize and raise the temperature.) The valves in the system are in the following states: Valve should be opened: Fresh gas inlet ball valve, gas ammonia main pipe large valve, ammonia delivery valve (open this ball valve when the system pressure is equal to 2.0Mpa, and notify the ammonia warehouse to open the ammonia delivery main inlet valve) high-pressure machine section water cooler inlet and outlet valve (more than two), circulation machine, outlet ball valve. Valve should be closed: Fresh gas valve, synthesis tower main and auxiliary valves, system short-circuit valve, fresh gas vent valve, cycle machine inlet and outlet valve, ammonia separator inlet ball valve, tower front and tower vent valves, ammonia delivery valves and ammonia adding valves. Add water to the water cooler and add ammonia to the ammonia cooler. Open the large fresh gas valve to pressurize the front of the tower. When the pressure in front of the tower is higher than the pressure in the tower, open the main valve of the tower display slightly and slowly pressurize the tower. Prepare the circulation machine and start the pressure to be equal to the pressure in the tower. The line valve is fully open and the inlet and outlet ball valves are fully closed. When the temperature rise stagnates, the inlet ball valve of the ammonia separator can be opened slightly, and the vent valve behind the tower can be slightly opened according to the operating conditions to vent part of the gas so that the temperature in the tower can continue to rise in a balanced manner. When the temperature of the catalyst hot spot is close to the target, the cycler can be put into the system, and the load can be gradually increased, and then the circulation volume can be gradually increased according to the catalyst temperature and put into normal production. Control the ammonia delivery pressure. 2. Shutdown (1), short-term shutdown (prepare to resume production in the short term). Before shutting down, raise the catalyst temperature to the upper limit of the indicator) and notify the high-pressure machine to gradually reduce the load. At the same time, turn off the tower valve and reduce circulation. Try to keep the catalyst temperature from falling, and pay attention to the ammonia content and secondary cooling liquid level. After all the fresh gas is stopped, the circulation machine cuts off the system and closes the following valves: Synthetic tower inlet main and auxiliary valves, ammonia separator display inlet ball valve, fresh gas valve, vent valve before and after the tower, each ammonia delivery valve and ammonia adding valve. When the system pressure is less than 2.5 MPa, the ammonia ball valve is allowed to be closed, and the ammonia warehouse is notified to close the main inlet valve. Otherwise, the above valves are not allowed to be closed. (2) Long-term shutdown (production cannot be resumed temporarily and the system equipment needs maintenance). The ammonia cooler should stop adding ammonia 4 hours before shutdown. The high-pressure machine gradually reduces the load, cooperates with the controlled circulation volume to cool down, and strictly controls the cooling rate within the target. After the high-pressure machine stops supplying air, the circulation machine continues to cooperate with the cooling and at the same time pressurizes the liquid ammonia from the ammonia separator and condensation tower to the ammonia storage. When the temperature drops to 100°C, the circulation machine can be cut out, the water cooler stops adding water, and the pressure is relieved by the vent valve behind the tower. If the synthesis tower itself is to be dismantled and inspected, the catalyst must be passivated or the ammonia gas pressure must be maintained. (3) Emergency stop informs the high-pressure machine to stop air supply and cut off the circulation machine. Quickly close the following valves:: Synthesis tower sub-line, main valve, ammonia separator inlet ball valve, each ammonia adding valve and ammonia releasing valve, system short-circuit valve, fresh gas valve. Carry out post-stop processing work, including moving the condensing tower, ammonia fraction, and liquid ammonia to the ammonia warehouse. 3. Operation precautions (1) The synthesis tower position is one of the most important positions in production. The temperature of the synthesis tower must be controlled during operation to prevent collapse and over-temperature. (2) Pay attention to the ammonia content and liquid level in the condensation tower to prevent ammonia from damaging the circulation machine or causing the synthesis tower to collapse. (3) The safety of the electric furnace must be maintained during the heating of the electric furnace. The circulation volume must be adjusted according to the power of the electric furnace. It is strictly forbidden to heat up the electric furnace with small circulation volume and high power. When the circulation volume is interrupted (such as the full cycle machine jumps), the electric furnace must be stopped immediately to avoid ring burning. (4) Contact the ammonia warehouse. When the system pressure is greater than 2.5Mpa, the ammonia delivery ball valve and the ammonia delivery main inlet cannot be closed. (5) Contact 8.13 well, and be absolutely clear about the switching status of the "69" connecting valve. (6) Control the ammonia delivery pressure and strictly prevent high pressure from causing low pressure. (7) Accident handling number Phenomenon Cause Treatment Method Remarks 1 The temperature of the catalyst layer dropped 1. The circulation process was too large 2. The ammonia content in the synthesis tower entering the tower body was too high: A. The amount of ammonia added to the ammonia cooler is too small. B. The pressure of the gas ammonia main pipe is too high. C. There is too much oil and water in the ammonia cooler. D. The water cooling effect is low. Reduce the circulation volume of the valve 2. Reduce the inlet ammonia content A. Open the ammonia adding valve B. Increase the ice machine C. Drain oil and water D. Increase the cooling water volume appropriately The opening and closing degree of the valve should not be too large, and the starting time should be 3-5 minutes apart. 2. The temperature of the catalyst layer rises. 1. The circulating gas volume is too small. 2. The main valve of the synthesis tower is opened too large or the auxiliary valve is opened too small. 3. Increase the amount of fresh gas. 1. Close the system short circuit or circulation machine auxiliary valve. 2. Close the main valve or open the auxiliary valve. 3. Increase the amount. If it is at full load, reduce the amount appropriately. 3 The pressure of the synthesis tower drops 1. Insufficient air volume of the compressor 2. There is a leak in the system 3. Excessive exhaust 4. Low liquid level and leakage 1. Contact the compressor for inspection 2. Serious shutdown for maintenance 3. Control the exhaust volume 4. Control the liquid level 4 Synthesis tower pressure rises 1. Catalyst temperature drops 2. Circulating gas volume is too small 3. Ammonia content in tower gas is too high 4. Heavy load 5. Hydrogen-nitrogen ratio is out of balance 6. Inert gas is high 1. Contact compressor for inspection 2. Serious shutdown for maintenance 3. Control exhaust volume 4. Control liquid level 5 The system resistance is too large 1. The pressure gauge (gauge) is inaccurate 2. The pipeline is not smooth or the valve is not in place 3. The circulation volume is too large 4. The nitrogen content is too high 1. Reduce the circulation volume, open the system shortcut 2. Enlarge the circulation gas volume 3. Reduce the gas ammonia content 4. Reduce the load when the indicator is exceeded 5. Notify dispatch 6. Send to hydrogen recovery or venting 6 Synthetic tower wall temperature is high 1. Circulation volume is too small, tower sub valve is opened too large 2. Internal parts are broken 1. Increase circulation volume 2. Stop for maintenance as appropriate 7 Synthesis tower outlet temperature is too high 1. Circulation volume is too small 2. Tower main valve is opened too small, tower sub valve is opened too large 3. Inert gas content is low 4. Heavy load 1. Increase circulation volume 2. Open the main valve appropriately and close auxiliary valve 3. Reduce or stop gas leakage and reduce emissions and send it to hydrogen recovery 4. Reduce load as appropriate 8 The temperature of the catalyst layer drops, and the tower pressure suddenly rises. 1. CO+CO2 is high, and the catalyst is poisoned. 2. Copper liquid or ammonia water enters the tower, and the catalyst is poisoned. 3. The secondary cooling liquid level is high, and liquid gas enters the tower. 1. The high-pressure machine is reduced according to regulations. This position controls the circulation volume and maintains the temperature. If the pressure is high, the tower is vented. If CO+CO2 reaches 100PPm, the tower should be shut down for processing. 2. Emergency shutdown of the tower 3. Control the liquid level. 9 Water cut off 1. Soft water cut off in the middle pot 2. Water cut off in the water cooler 1. The tower secondary inlet temperature control cycle is one, or load reduction or tower shutdown 2. Reduce the ammonia cooler temperature. See that the inlet temperature of the cycle machine does not exceed the indicator. If the water cut off time is long, the tower will be shut down urgently. 10 If the power supply is interrupted or the electrical equipment fails, it shall be handled as an emergency shutdown. 11 Cycle machine trip or emergency shutdown 1. Distribution station failure or interlock action 2. Cycle machine failure emergency shutdown 1. Reduction as required 2. Full-jump emergency shutdown of the tower 12 Explosion, fire, large air leakage or other emergency shutdown of the tower 13 Stop of fresh gas supply 1. Gas failure 2. High pressure machine failure 3. Purification or copper washing failure, shutdown of the tower 14 The system pressure suddenly increases 1. The valve head in the system is damaged or falls off or the connection is loose. 2. The valve is installed backwards, the air flow is blocked or other reasons. 1. Reduce the circulation volume, maintain the temperature, maintain the system pressure difference not to exceed the indicator, and reduce the pressure of the high pressure machine accordingly. 2. Identify the cause. 15. All or part of the instrument fails. The instrument is interrupted or the instrument fails. Maintain the original operating status. Contact the instrument for processing or shut down the tower. 8. Work contact 1. Closely contact the circulation machine position to adjust the circulation volume. 2. The addition and subtraction are closely related to the high pressure machine position. 3. Close contact with copper washing according to temperature changes. 4. Control of ammonia delivery and ammonia adding pressure is closely linked to the ammonia reservoir. 5. When there is an emergency and the foreman and shift director are not present, you can go directly to the dispatch room to contact the dispatch room for timely handling and report promptly afterwards. 2. Equipment maintenance system (1) Management scope 1. Synthesis tower and its connecting pipes, fittings, valves, etc. 2. 1#, 2# condensation towers and their connecting pipe fittings, etc. 3. 1#, 2#, 3# water cooling towers and their connecting pipe fittings, etc. 4. New or original ammonia coolers, gas ammonia demisters and their connecting pipe fittings, valves, etc. 5. Ammonia separator and its connecting pipe fittings, valves, etc. 6. The heat exchanger outside the tower and its connecting pipe fittings, valves, etc. 7. Central boiler and its connecting pipe fittings, valves, etc. 8. Ammonia transmission and ammonia adding pipelines, etc. (2) Maintenance of equipment 1. Strictly implement the job responsibility system and technical operating procedures, and strictly prevent over-temperature, over-pressure, and over-load operation. 2. The synthesis tower raises and lowers the pressure and temperature in strict accordance with the prescribed rate. The load should be added and dropped slowly to avoid violent fluctuations. During normal operation, the temperature of the catalyst layer should be controlled to be stable and the fluctuation range should not be too large. 3. After the catalyst is installed in the synthesis tower, it is strictly forbidden for the gas in the tower to flow back, so care should be taken when opening the inlet and outlet valves of the synthesis tower. (1) When the pressure inside the tower is high, open the outlet valve first, and when the pressure outside the tower is high, open the inlet valve first. (2) The main valve and auxiliary valve of the tower are not closed and cannot be vented before opening the tower. 4. When using an electric furnace, the circulation machine must be turned on first to supply air. When the air supply volume of the circulation machine reaches a certain level, the electric furnace can be turned on. When using an electric furnace, you should follow the regulations on the use of electric furnaces. 5. When the synthesis tower is stopped, the positive pressure in the tower must be maintained to prevent air from entering the tower and damaging and burning the catalyst. 6. When the tower is shut down due to copper liquid entering the tower or trace poisoning, it is not allowed to use the pressure charging and heating operation method. 7. All equipment, pipes, instruments, etc. are not allowed to be knocked casually. It is necessary to frequently check the vibration of high-pressure pipelines and whether there are leaks or ruptures in various equipment and valves, report them in time, and eliminate them in time. 8. Eliminate running, popping, dripping and leaking as much as possible. 9. Carry out careful inspection and listing according to regulations. 10. Carry out sanitary cleaning according to regulations. 11. Control the liquid level well to prevent accidents such as high level and low level, liquid entering the tower and cylinder. I don’t know if this is what you want, and I have a few suggestions.: This topic already exists in this forum. It is recommended to check if there is a related topic in the future. If not, post the topic. Let us all consciously safeguard the overall interests of the ammonia technology exchange area of ​​this forum. Because the same or similar topics not only occupy the space of our limited main service machine, but are also inconvenient for comrades with the same requirements to search. Thank you for your cooperation!

I had checked on the forum before, but could not find the "operation method or procedures for the Casali 300,000 t/a ammonia synthesis tower" that I wanted.