Original start-up data for ammonia synthesis

Technical upgrades and operation of the shift system in 80 kt/a ammonia synthesis plants; Analysis of typical accidents in similar ammonia synthesis plants abroad; Production and technology of ammonia synthesis catalysts; Online analysis in ammonia synthesis industrial production; Analysis of explosion causes in the shift and desorption systems of ammonia synthesis plants and preventive measures; Selection of process plans for modifying the raw material routes in ammonia synthesis plants; How to achieve optimized operation of ammonia synthesis towers; Summary of technical upgrades for intelligent interlock protection systems; Analysis of reasons for uneven temperature distribution in ammonia synthesis towers and improvement measures; Environmental protection measures in ammonia synthesis plants; Study on the relationship between the activity of ammonia synthesis catalysts and reduction pressure; Technical upgrades and problem resolution in ammonia synthesis; Rapid startup of ammonia synthesis plants; Ultra-efficient oil removal and purification of syngas; Exploration of ways to reduce the time required for the initial startup of ammonia synthesis plants. The following are all the articles related to ammonia synthesis: Analysis of causes and prevention of nitrogen compressor failures; Improvements to the gas generation process in ammonia synthesis plants; Technical advancements and industrial applications of ammonia synthesis catalysts; Analysis of risks during the operation of the first-stage conversion furnace in ammonia synthesis plants and preventive measures; Discussion on issues related to rapid startup of ammonia synthesis plants; How to achieve the highest equilibrium yield in gas reactions; Analysis of causes and prevention of a waste heat boiler leakage accident

Please check if this link is helpful: Technical documentation on the installation and commissioning of internals in DN1200 synthesis towers; Comprehensive commissioning plan for ammonia synthesis plants in Hainan; Complete information on the initial commissioning and performance testing of 450t/a ammonia synthesis units. This post was last edited by snowdfr on 2009-3-10 at 19:43

I’m asking for the original operation data for the synthesis position

This post was last edited by Huang Xinhui on 2009-6-13 at 15:34. There are actually quite a few sections containing such information; perhaps the guys above didn’t pay attention to searching for them. Below, I’ve compiled relevant posts related to driving, hoping it will be useful to them. I also suggest that everyone get familiar with the forum rules as soon as possible so they can progress faster. Let’s all work together to contribute to the Haichuan Ammonia Synthesis section and add value to it. 1. How to carry out chemical cleaning during the initial startup of decarbonization processes. 2. Summary of the initial startup of an 180,000 t/year medium-high pressure methanol synthesis system. 3. 4. Initial startup plan for the synthesis tower; large rewards available. 5. Purging plan for the initial startup of the shift converter unit. 6. How do you organize the steps for the initial startup of a fertilizer plant? 7. Interlocking test plan during the initial startup of ammonia synthesis. 8. Purging plan for the initial startup of the shift converter unit. 9. Initial startup plan for the shift converter unit; large rewards available. 10. Source of hydrogen for the initial startup of an ammonia synthesis plant using natural gas as feedstock. 11. Purging steps during the initial startup of the ammonia synthesis unit. 12. Differences in valve positions during initial startup, startup while maintaining temperature and pressure, and maintenance shutdowns in the ammonia synthesis unit. 13. Discussion on the steps required to thoroughly purge the system during initial startup. 14. Seeking an initial startup plan for an ammonia synthesis plant. 15. Several issues related to initial startup... 1 2 16. How to calculate the amount of methanol required for the initial startup of a low-temperature methanol washing process? 17. Purging and flushing plan for the initial startup of raw gas shift

A catalytic heating and reduction scheme for the synthesis process is now provided, in the hope that it will be useful to the team on the 4th floor. Catalytic heating and reduction scheme for synthesizing XA201 catalyst: I. Preparation work 1. The equipment has completed pressure testing, purging, gas displacement, and airtightness tests, and is now ready for heating. 2. The circulating water in the synthetic water cooler is circulating normally. The demineralized water required for the waste heat boiler is supplied properly. 3. The chiller is operating normally, and ammonia can be supplied to the synthetic ammonia cold flash drum and ammonia cooler at any time. 4. The electric heater and voltage regulation device are in good condition, and professional personnel are present to supervise their use. 5. All analysis sampling points are unobstructed, the analysis instruments are in good condition, and all necessary analysis equipment is available. 6. The DCS, control valves, and related instruments have been tuned and meet the requirements for commissioning. 7. The test run of the turbine cycle machine is complete, and it is ready for use. 8. The liquid ammonia tank area is equipped to receive the ammonia water and liquid ammonia discharged as a result of catalytic heating and reduction. 9. The alcoholization and hydrocarbonation systems are operating normally, with CO+CO2 in the gas after hydrocarbonation ≤ 25 PPm. 10. On the ammonia and cold transfer ammonia pipelines, a temporary drain pipe is connected (water discharged at temperatures below 300°C is directed into the gutter, while ammonia water discharged at temperatures above 300°C is sent to Tank No. 7 for liquid ammonia storage). 11. Fill the system that has been replaced and subjected to a gas-tightness test with ammonia, so that the ammonia content in the circulating gas is >1%. 12. Supply qualified fresh gas to the system at a pressure of 4.0 MPa. II. Water output: The theoretical water output is 22,907 kg. III. Requirements for heating and reduction: 1. For this process of heating and reduction, a high H2 content, high furnace power, high gas velocity (for the reduction of the catalyst in the middle and lower sections), high hydrogen levels, low temperature, low water vapor concentration, low ammonia cooling temperature, and appropriate pressure are required. The heating rate is determined based on the requirement that the water vapor concentration does not exceed specified limits; during the main reduction phase, the water vapor concentration is controlled at ≤2.5 g/Nm3, and during the later stage of reduction, it is controlled at ≤1.5 g/Nm3. 2. Throughout the reduction process, close attention should be paid to the temperature difference within the same plane of the bed layer as well as to the temperature distribution. If the temperature difference within the same plane is too large (>15°C) or the temperature distribution is unreasonable, the reasons must be analyzed promptly; only after identifying the causes can the temperature be increased further. IV. Operation of heating and reduction 1. After the system has been properly purged, a small amount of liquid ammonia is fed into the ammonia separation unit and the heat exchanger in the reverse direction, from the liquid ammonia tank area. 2. Steam is introduced, with the pressure maintained at 1.0–1.5 Mpa. During the main reduction phase, the level of the waste boiler liquid should be kept as low as possible; during the later stages of reduction, water can be added to the waste boiler gradually in intermittent amounts. 3. Open the system pressurization valve to introduce qualified hydrocarbon gas, with a pressure of 5.0 Mpa. 4. Run a turbine cycle for 20–30 minutes, and take samples after the synthesis tower to analyze the NH3 content in the gas, which is around 1%. 5. The temperature increase for the catalyst is carried out in a systematic manner, while reduction is done in a layered fashion (with the main reduction periods for each layer staggered as much as possible). The specific temperature divisions are shown in the “Temperature Increase and Reduction Schedule” (attached below). 6. Heating phase (room temperature to 380°C) 6.1 Valve operation: (1) Close the system bypass valve ； (2) Thermal auxiliary valve open 2 clicks ； (3) The cold auxiliary valve (gap valve) is opened 2 notches ； (4) Cold tube valve (gas valve for entering the cold tube bundle, at the top of the tower) closed ； (5) Zero-meter cold shock valve fully closed ； (6) Inter-segment chill valve fully closed ； (7) Main line inlet and outlet valves fully open ； 6.2 Process conditions: (1) System pressure: 4.0 Mpa ； (2) Circulation volume: 12 m3/min ； (3) Circulating H2: >72% ； 6.3 Key operating points: (1) Maintain stable system pressure and a constant circulation rate; use an electric furnace to control the catalyst’s heating rate at 40–45°C/h. (2) When the temperature at the hot spot reaches 330°C, ammonia is added to the flash tank and ammonia cooler to gradually control the temperature of the ammonia-cooled gas between 0 and 5°C. (3) When the water-cooling outlet temperature reaches 30°C, start the circulating water of the water cooler. (4) When the hotspot temperature rises to the 120–130°C range, if a large number of sensors fail due to high temperatures, it is necessary to decide whether to carry out constant-temperature treatment or temporarily shut down the system in order to remove moisture from the thermocouples. (5) When the temperature at the hot spot rises to 300°C, water drainage should begin; this process must be carried out once per hour, with the amount of water drained being recorded. When there is a certain ammonia concentration, a sample should be taken for analysis of the ammonia concentration every time water is discharged. Based on the ammonia concentration, its specific gravity is determined, and the weights of water and ammonia are calculated respectively to facilitate the verification of water vapor concentration analysis and the assessment of catalyst water release. (4) The heating phase at a hotspot temperature of 330°C has ended. (5) Ammonia-free water is sent to the gutter through temporary pipes, while ammonia-containing water is delivered to Tank No. 7 via ammonia release pipelines. 7. Upper reduction stage; see “Heating and Reduction Schedule”. 7.1 Process conditions: (1) System pressure maintained at 4.0 Mpa; (2) Circulation rate: 12 m3/min to 15 m3/min ； (3) Circulating H2: >72% ； (4) Circulating CH4: < 3% ； (5) Ammonia cooling temperature: -5℃～ -10℃ ； 7.2 Valve operation: (1) The two cold tube valves (valves for the gas entering the cold tube bundle, located at the top of the tower) shall be opened 2 turns ； (2) The cold auxiliary valve (gap valve) is opened 2–3 notches ； (3) Thermal auxiliary valve fully closed ； (4) System bypass valve closed ； (5) Zero-meter cold shock valve fully closed ； (6) Inter-segment chill valve fully closed ； (7) Main line inlet and outlet valves fully open ； 7.3 Key operating points: (1) Maintain stable system pressure and a constant circulation rate; use an electric heater to control the heating rate of the catalyst, as specified in the “Heating and Reduction Schedule”. (2) Due to the increased shunting, the temperature at zero meter will rise; use an electric furnace to control the temperature increase: 380°C–430°C at hot spots: 5°C/h ； Hot spot 430℃～465℃: 2℃/h ； Hot spot 465℃～495℃: ~3℃/h ； Hot spot 495℃～500℃: 1～0℃/h ； (3) Upper-layer reduction involves fully reducing the upper-layer catalyst from the initial stage, the main stage to the final stage in one go; once the zero-temperature of the upper-layer catalyst reaches 480–490°C, it is maintained at that temperature for 8 hours. The temperature in the middle of the upper layer remains at 495°C for more than 8 hours, with a temperature difference within the same plane of less than 10°C. The system pressure gradually increases, causing the hot spot to shift to the lower part of the upper-layer catalyst. (4) When the temperature at the upper and lower layers reaches 495°C, further increase the pressure and the space velocity to shift the hot spot to the upper and lower layers, thereby initiating the reduction of the catalyst in the middle layer. (5) Analyze the water vapor concentration once per hour; the increase in temperature and pressure should be determined based on the water vapor concentration, in order to prevent it from rising too rapidly and causing the concentration to exceed the allowable level. (6) The discharged ammonia water is sent through the ammonia discharge pipeline and then to the 7# liquid ammonia storage tank via the ammonia release pipeline. 8. Intermediate catalyst reduction phase ； 8.1 Process conditions: (2) Circulation rate: 15–18 m3/min ； (3) Circulating H2: 68～72% ； (4) Circulating CH4: < 3% ； (5) Ammonia cooling temperature: -10℃～ -15℃ ； 8.2 Valve operation: (1) The cold auxiliary valve (gap valve) shall be opened 2–3 notches ； (2) The two cold pipe valves are gradually closed to reduce the air flow into the cold pipe bundle ； (3) The thermal auxiliary valve is gradually opened to 2–3 turns ； (4) Zero-meter cold shock valve fully closed ； 8.3 Key operation points: (1) Set the power of the electric furnace to its maximum level, maintain a stable main inlet temperature and stable circulating hydrogen, make fine adjustments to the system’s pathways, and keep the temperature at the upper heating zone at 495°C. (2) Gradually increase the pressure; when there is an upward trend in the temperature at the upper layer, slowly raise the circulation rate to increase the space velocity. Gradually increase the temperature at each point in the middle layer. (3) Gradually close the cold tube valve to reduce the amount of gas flowing into the cold tube bundle, thereby raising the temperature of the catalyst in the middle layer. The degree to which the cooling valve is closed should be small, so as to allow the temperature of the catalyst in the middle layer to rise gradually and prevent the water vapor concentration from exceeding the limit. Closing the cold pipe valve and increasing pressure must be done alternately; they cannot be carried out simultaneously. When the temperature of the annular gap gas (i.e., the tower wall temperature) rises significantly, the thermal auxiliary valve is then opened, with its opening degree being increased gradually. (4) The amount of catalyst loaded in the middle layer is large, and during the reduction phase, it is easy for the water vapor concentration to exceed the specified limits. When the water vapor concentration exceeds the limit, promptly lower the temperature at the hot spot by 2°C to 3°C and maintain a constant temperature. Only when the water vapor concentration or water output drops significantly to within the normal range should the reduction process be continued according to the procedure. The temperature at each point is required to reach 495°C. (5) The ammonia released during the temperature-raising reduction process in the intermediate catalyst layer is sent to the ammonia recovery dilute ammonia storage tank through the ammonia discharge pipeline. 9. Lower catalyst reduction stage ； 9.1 Process conditions: (1) System pressure 12.0 Mpa ； (2) Circulation volume: 28 m3/min ； (3) Circulating H2: 68～72% ； (4) Circulating CH4: < 3% ； (5) Ammonia cooling temperature: -10℃～ -15℃ ； 9.2 Valve operation: (1) Continue to gradually close the two cold pipe valves until they are fully closed 24 hours before the end of the reduction process ； (2) Gradually open the thermal auxiliary valve by 2–3 turns to keep the tower wall temperature below 120℃ ； (3) Zero-meter cold shock valve fully closed ； 9.3 Key operating points: (1) Maintain stable power of the electric furnace, keep the main feed temperature stable, and stabilize the circulating hydrogen (so that H2/N2 is equal to or slightly less than 3); fine-tune the system parameters to keep the hot spots in the upper or middle layers within the range of 495°C. (2) Continue to increase the pressure gradually, by 0.2 MPa each time, in order to steadily increase the reaction heat in the upper or middle layer, thereby allowing the circulation volume to increase step by step and raising the temperature of the catalyst in the lower layer gradually. (3) The operations of increasing pressure and closing the cold pipe valves should be carried out alternately to prevent the steam concentration from exceeding the limit. (4) The amount of catalyst filled in the lower layer is also large; attention should be paid to changes in its water vapor concentration during reduction. As the air velocity increases, the mixture of ammonia and water produced as a result of this reaction increases rapidly; it is necessary to discharge water on time to prevent accidents caused by water entering the tower. (5) When the temperature at the lowest point of the bottom layer reaches 475°C or above, stable conditions are also required, with the temperature remaining constant for more than 8 hours. 10. Determination of the reduction endpoint: (1) The temperature at the bottom of the catalyst layer should be above 475°C, and this condition must be maintained for 8 hours ； (2) Maintain the temperature at zero meter at 485°C to 490°C or above for 8 hours ； (3) The remaining points (except those at zero meters and on the bottom layer) reach 495°C and remain at that temperature for more than 8 hours ； (4) Temperature difference within the same plane of the axial section < 10℃ ； (5) Judgment of completion of reduction: At a bottom temperature of 475°C for 4 hours, the water vapor concentration remains below 0.2 g/m3. V. Precautions: 1. The startup and shutdown of the turbine cycle machine must be carried out in strict accordance with the operating procedures; especially during the process of increasing or decreasing pressure, the speed should be slow, with no sudden changes. 2. When the turbine cycle machine emits abnormal noises or other faults, the operator can first shut it down before reporting. a) The maximum adjustable current of the electric furnace shall not exceed 1528A. b) The compressor must inform the control room before shutting down, and large pressure fluctuations should be avoided during the shutdown process. c) A reciprocating circulator is operated in the hydrocarbonization system to maintain the catalyst bed temperature, with the system pressure kept below 13.0 Mpa. d) The pressure of the protective gas should be 0.1–0.5 MPa higher than that of the synthesis system, with a flow rate controlled at 500–700 Nm3/h. VI. Handling in Special Circumstances 1. If all three turbine circulators shut down suddenly: an emergency stop must be initiated, and the electric furnace should be turned off immediately. Close the gas supply valve; the gas is vented at the back of the tower, carrying away water vapor and also discharging water. 2. If one of the three operating turbine cycles suddenly shuts down, reduce the load on the electric furnace depending on the temperature of the catalyst, and maintain a constant temperature once the catalyst temperature stabilizes. Continue the heating and reduction process once the turbine cycle machine returns to normal. 3. If one of the two operating turbine cycles suddenly shuts down, reduce the load on the furnace depending on the temperature of the catalyst to stabilize its temperature, and at the same time start the other turbine cycle. 4. If a single turbine cycle machine shuts down suddenly during operation: immediately cut off the electric furnace and increase the venting at the tower. Start another turbine cycle machine at the same time. 5. Power outage: Close the make-up gas valve, open the vent at the top of the tower to reduce the water vapor concentration, and drain the water. At the same time, turn on the computer’s backup power supply and observe the changes in catalyst temperature. 6. Shutdown of the compressor: The supply of gaseous hydrocarbons to the synthesis system is stopped, and the synthesis system is appropriately depressurized depending on the water vapor concentration and temperature. It should be noted that the pressure of the shielding gas must be 0.1–0.5 MPa higher than the pressure in the synthesis system, with a flow rate of 500–700 Nm3/h. Appendix: 1. Schedule for heating and reduction of the synthetic catalyst ； 2. Diagram of internal components in the synthesis tower and locations of temperature measurement points ； 3. Catalyst loading diagram of the synthesis tower ； 4. Process flow diagram ；