A method for the synthesis of ammonia in a bipolar single cycle

Abstract

This application discloses a bipolar single-cycle ammonia synthesis method, comprising the following steps: (1) Gas exiting the circulator enters ammonia synthesis tower A to react and generate reaction gas A; (2) The generated reaction gas A enters the A series heat exchanger for cooling and heat recovery, and then enters the cold recovery unit; (3) After cold recovery, reaction gas A enters separator A, and the separated gas enters ammonia synthesis tower B to react and generate reaction gas B; (4) The generated reaction gas B enters the B series heat exchanger for cooling and heat recovery, and then enters the cold recovery unit; (5) After cold recovery, reaction gas B enters separator B, and the separated gas enters the circulator inlet; (6) Fresh raw material gas enters the compressor to increase pressure, and a portion is added to the primary ammonia synthesis reaction; the other portion is added to the secondary ammonia synthesis reaction. The method of this invention has low ammonia circulation volume, high synthesis tower operating efficiency, high catalyst reaction efficiency, and low circulation power consumption.

Description

Technical Field

[0001] This invention relates to the field of ammonia synthesis technology, and more specifically to a bipolar single-cycle ammonia synthesis method. Background Technology

[0002] The synthesis of ammonia involves the formation of two NH3 molecules from one N2 molecule and three H2 molecules. This reaction requires high pressure (currently 13.0 MPa–32.0 MPa for iron-based catalysts), high temperature (350°C–520°C), and the presence of a catalyst. It is a reversible exothermic reaction; increasing the pressure, temperature, or decreasing the reactant concentration can all favor the reaction. Since the amount of ammonia produced during each gas-catalyst contact is limited (generally less than 20%), a cyclic reaction process is necessary.

[0003] In engineering, we generally use appropriate low temperatures, appropriate operating pressures, and lower circulation rates to achieve a comprehensive balance between efficiency and energy saving. In actual operation, under certain catalyst conditions, we aim to minimize the ammonia content in the inlet gas and maximize the ammonia content at the outlet of the ammonia synthesis tower to achieve maximum catalyst reaction efficiency. Therefore, using more catalyst, improving catalyst efficiency, and reducing the gas circulation rate (or circulation ratio) are common engineering optimization methods.

[0004] Existing ammonia synthesis methods generally employ a single-tower circulation system. For example, Chinese patent CN105883852A discloses an ammonia synthesis reaction system comprising: an ammonia synthesis tower, a combined waste heat boiler, a feedwater heater, a circulating gas heat exchanger, a water cooler, a combined ammonia cooler, a diammonium cooler, an ammonia separator, a liquid ammonia tank, and a circulating machine. Gas preheated in the circulating gas heat exchanger enters the ammonia synthesis tower, and the reacted gas directly enters the combined waste heat boiler from the bottom of the ammonia synthesis tower. The gas circulation ratio in a single-tower process is typically 3.0–3.8, resulting in a large gas circulation volume, low ammonia net value in the synthesis tower, and low operating efficiency.

[0005] Furthermore, the ammonia content in the inlet gas is mainly determined by the condensation temperature and separation efficiency during ammonia separation. The lower the condensation temperature and the better the separation effect, the lower the ammonia content in the inlet gas. Currently, ammonia is the most widely used refrigerant for cooling and condensing the ammonia synthesis cycle, which can generally reduce the ammonia content in the circulating gas to about 3.8 mol%. To further reduce the inlet ammonia content, refrigerants with lower vaporization temperatures, such as CO2 and propylene, should be used. This can further improve the reaction efficiency of the synthesis tower, but CO2 and propylene pose environmental problems and the risk of explosion. Summary of the Invention

[0006] To address the aforementioned technical problems of large gas circulation volume, low ammonia net value of the synthesis tower, and low operating efficiency in existing single-tower circulating ammonia synthesis methods, this invention proposes a bipolar single-cycle ammonia synthesis method.

[0007] The technical solution adopted in this invention is as follows:

[0008] A bipolar single-cycle ammonia synthesis method includes the following steps:

[0009] (1) The gas coming out of the circulating machine enters the shell side of the heat exchanger A and is heated, then enters the ammonia synthesis tower A to carry out the first-stage ammonia synthesis reaction and generate reaction gas A.

[0010] (2) The generated reaction gas A enters the tube side of the steam superheater A, the tube side of the steam generator A, the tube side of the feedwater preheater A, the tube side of the heat exchanger A, and the shell side of the water cooler A in sequence. After cooling and completing heat recovery, it enters the combined cooling condenser for cold energy recovery.

[0011] (3) After the cold energy recovery is completed, the reaction gas A enters the separator A for gas-liquid separation. The separated gas returns to the combined cooling condenser to exchange heat with the reaction gas A and then enters the shell side of the heat exchanger B. After the temperature is raised, the gas enters the ammonia synthesis tower B for secondary ammonia synthesis reaction to generate reaction gas B.

[0012] (4) The generated reaction gas B enters the tube side of the steam superheater B, the tube side of the steam generator B, the tube side of the feedwater preheater B, the tube side of the heat exchanger B, and the shell side of the water cooler B in sequence. After cooling and completing heat recovery, it enters the combined cooling condenser for cold energy recovery.

[0013] (5) After the cold energy recovery is completed, the reaction gas B enters the separator B for gas-liquid separation. The separated gas returns to the combined cooling condenser to exchange heat with the reaction gas B and then enters the inlet of the circulating machine.

[0014] (6) The crude ammonia separated by separator A and separator B enters the flash tank for flash evaporation. After the flash vapor enters the compressor to increase the pressure, part of it enters the inlet of the circulating machine and is fed into the primary ammonia synthesis reaction; the other part enters the shell side of heat exchanger B and is fed into the secondary ammonia synthesis reaction.

[0015] (7) Fresh raw gas from the purified and refined process also enters the compressor to increase the pressure, and part of it is fed into the primary ammonia synthesis reaction; the other part is fed into the secondary ammonia synthesis reaction.

[0016] Furthermore, fresh feed gas is added to the primary ammonia synthesis reaction and the secondary ammonia synthesis reaction in a 1:1 ratio.

[0017] By adopting the above technical solution, the fresh gas is added to the two series of synthesis towers in a ratio of 0.5:0.5, which can make the ammonia production, catalyst load and synthesis efficiency of the two synthesis towers basically the same, thereby achieving a high ammonia synthesis efficiency.

[0018] Furthermore, the boiler feedwater from the boiler workshop enters the shell side of feedwater preheater A, where its temperature is increased, and then enters the shell side of steam generator A to generate saturated steam A. The generated saturated steam A then enters the shell side of steam superheater A to generate superheated steam A before being discharged. The other path enters the shell side of feedwater preheater B, where its temperature is increased, and then enters the shell side of steam generator B to generate saturated steam B. The generated saturated steam B then enters the shell side of steam superheater B to generate superheated steam B before being discharged.

[0019] By adopting the above technical solution, the reaction heat generated by the two synthesis towers can be recovered by producing steam (either superheated steam or saturated steam). To recover more steam, a boiler feedwater preheater is installed in both reaction systems.

[0020] Furthermore, cooling water A and cooling water B are respectively introduced into the shell side of water cooler A and water cooler B. Since water coolers are relatively prone to clogging and leakage, each reaction system is equipped with a separate "water cooler" for easy maintenance.

[0021] Furthermore, the combined cooling condenser includes a cold exchange unit, a first cooling unit, and a second cooling unit. Reaction gas A and reaction gas B enter the cold exchange unit, the first cooling unit, and the second cooling unit sequentially, and after being condensed and cooled individually, they enter separator A and separator B respectively. The gases separated by separator A and separator B enter the cold exchange unit and exchange heat with reaction gas A and reaction gas B respectively. Liquid refrigerant is introduced into the first cooling unit and the second cooling unit respectively. The liquid refrigerant is heated by reaction gas A and reaction gas B to form gaseous refrigerant, which is then discharged from the first cooling unit and the second cooling unit respectively.

[0022] This application utilizes a dual-stream "combined cooling condenser" to separate the reaction gases from the two reaction series after ammonia synthesis. This dual-stream "evaporation and freezing" process, where each gas undergoes "two-stage cooling," "two-stage cold exchange," and refrigerant exchange in a single combined device, reduces the ammonia content at the inlet of both synthesis towers to approximately 2.6 mol%, further improving ammonia synthesis efficiency and reducing refrigeration power consumption.

[0023] Furthermore, the flow rate of the feed gas at the inlet of ammonia synthesis tower A is 600–650 kNm³. 3The flow rate is 14–15 MPaG / h, pressure is 175–185℃, temperature is 420–430℃ for the reaction gas at the outlet of ammonia synthesis tower A, and the flow rate of the raw material gas at the inlet of ammonia synthesis tower B is 600–650 kNm³ / h. 3 / h, pressure is 13~14MPaG, temperature is 165~175℃%; the temperature of the reaction gas B at the outlet of ammonia synthesis tower B is 410~420℃.

[0024] By adopting the above technical solutions, the recycling ratio can be further reduced, the net ammonia value can be increased, and the reaction efficiency of ammonia synthesis can be improved.

[0025] Furthermore, the total flow rate of the recycle gas and fresh feed gas added to the primary ammonia synthesis reaction is 190–200 kNm. 3 The flow rate is 190–200 kNm³ / h, the pressure is 13–14 MPaG, and the temperature is 105–115 °C. 3 The flow rate is 13–14 MPaG / h, pressure is 13–14 MPaG, temperature is 105–115℃; the total flow rate of fresh feed gas is 370–380 kNm³. 3 / h.

[0026] By adopting the above technical solutions, the recycling ratio can be further reduced, the net ammonia value can be increased, and the reaction efficiency of ammonia synthesis can be improved.

[0027] Furthermore, the temperature of the raw gas A entering separator A is -5 to -15℃, and the temperature of the raw gas B entering separator B is -5 to -15℃; the temperature of the gas exiting the combined cooling condenser and exchanging heat with the reaction gas A is 30 to 40℃; the temperature of the gas exiting the combined cooling condenser and exchanging heat with the reaction gas B is 30 to 40℃.

[0028] By adopting the above technical solutions, the inlet temperature and inlet ammonia content of the ammonia synthesis tower can be further reduced, the refrigeration power consumption can be reduced, and the ammonia synthesis efficiency can be improved.

[0029] The beneficial effects of this invention are:

[0030] 1. This invention employs two ammonia synthesis towers and one circulating unit. Each of the two ammonia synthesis towers is connected in series with a "heat recovery" unit, a "freezing / condensation" unit, and a "cold recovery" unit, respectively. This achieves a process flow where the circulating gas is "connected in series," the supplementary gas is "connected in parallel," and the supply is adjusted as needed. This significantly improves the catalyst efficiency of the two ammonia synthesis towers (especially the catalyst efficiency of the second-stage synthesis tower). The ammonia content at the inlet of both the first-stage and second-stage synthesis towers can reach approximately 2.6V mol%, with the net ammonia value of the first-stage synthesis tower reaching 17.11% and the net ammonia value of the second-stage synthesis tower reaching 17.45%. The circulation ratios of the first-stage and second-stage synthesis towers can reach 1.6481 and 1.6868, respectively. Both synthesis towers exhibit high ammonia synthesis efficiencies.

[0031] 2. This application divides the replenished fresh gas into two streams, which are then fed into two synthesis towers respectively, thus realizing a "parallel" process flow for gas replenishment. At the same time, the flow rates of the two replenished gas streams entering the synthesis towers can be adjusted according to different requirements to achieve a relative balance in the load and reaction efficiency of the two ammonia synthesis towers; and the process method of replenishing the "replenished gas" at the inlet of the circulating machine when entering the first synthesis tower can greatly reduce the compression power consumption. Attached Figure Description

[0032] Figure 1 This is a process flow diagram of the bipolar single-cycle ammonia synthesis method of the present invention.

[0033] Figure 2 This is a process structure diagram of the combined cooling condenser evaporator of the present invention. Detailed Implementation

[0034] See Figures 1-2 This embodiment provides a bipolar single-cycle ammonia synthesis method, including the following steps:

[0035] (1) The gas coming out of the CO2 outlet of the circulating machine enters the shell side of the heat exchanger E04A and is heated, then enters the ammonia synthesis tower R01A to carry out the first-stage ammonia synthesis reaction and generate reaction gas A.

[0036] (2) The generated reaction gas A enters the tube side of the steam superheater E01A, the tube side of the steam generator E02A, the tube side of the feedwater preheater E03A, the tube side of the heat exchanger E04A, and the shell side of the water cooler E05A in sequence. After cooling and completing heat recovery, it enters the combined cooling condenser E06 for cold energy recovery.

[0037] (3) After the cold energy recovery is completed, the reaction gas A enters the separator V01A for gas-liquid separation. The separated gas returns to the combined cooling condenser E06 to exchange heat with the reaction gas A and then enters the shell side of the heat exchanger E04B. After the temperature is raised, the gas enters the ammonia synthesis tower R02B for secondary ammonia synthesis reaction to generate reaction gas B.

[0038] (4) The generated reaction gas B enters the tube side of the steam superheater E01B, the tube side of the steam generator E02B, the tube side of the feedwater preheater E03B, the tube side of the heat exchanger E04B, and the shell side of the water cooler E05B in sequence. After cooling and completing heat recovery, it enters the combined cooling condenser E06 for cold energy recovery.

[0039] (5) After the cold energy recovery is completed, the reaction gas B enters the separator V01B for gas-liquid separation. The separated gas returns to the combined cooling condenser E06 to exchange heat with the reaction gas B and then enters the inlet of the circulating machine C02.

[0040] (6) The crude ammonia separated from the bottom of separators V01A and V01B enters flash tank V02 for flash evaporation. After the flash vapor enters compressor CO1 to increase the pressure, part of it enters the inlet of circulating machine CO2 and is added to the primary ammonia synthesis reaction; the other part enters the shell side of heat exchanger E04B and is added to the secondary ammonia synthesis reaction. The liquid ammonia at the bottom of flash tank V02 enters the tube side of heat exchanger E07 to reduce the temperature and is discharged as finished ammonia.

[0041] (7) Fresh raw material gas from purification and refining also enters the compressor CO1 to increase the pressure. Part of it is fed into the first-stage ammonia synthesis reaction after the flow rate is adjusted by valve F01; the other part is fed into the second-stage ammonia synthesis reaction after the flow rate is adjusted by valve F02.

[0042] In this embodiment, boiler feedwater from the boiler room enters the shell side of feedwater preheater E03A after its flow rate is regulated by valve F03. After its temperature is increased, it enters the shell side of steam generator E02A to generate saturated steam A. The generated saturated steam A then enters the shell side of steam superheater E01A to generate superheated steam A before being discharged. The other feedwater enters the shell side of feedwater preheater E03B after its flow rate is regulated by valve F04. After its temperature is increased, it enters the shell side of steam generator E02B to generate saturated steam B. The generated saturated steam B then enters the shell side of steam superheater E01B to generate superheated steam B. Superheated steam B and saturated steam A together enter the shell side of steam superheater E01A to generate superheated steam A before being discharged. This design allows for higher heat recovery efficiency.

[0043] Cooling water CWS1 and cooling water CWS2 are introduced into the shell side of water cooler E05A and water cooler E05B, respectively. After the cooling water CWS1 and cooling water CWS2 are heated, they are discharged from water cooler E05A and water cooler E05B, respectively.

[0044] The combined cooling condenser E06 includes a cold exchange unit E061, a first cooling unit E062, and a second cooling unit E063. The cold exchange unit E061 has two non-communicating heat exchange chambers A and B, with a first heat exchange tube and a second heat exchange tube respectively installed in heat exchange chambers A and B. The first cooling unit E062 has one heat exchange chamber C, with two non-communicating third and fourth heat exchange tubes installed in heat exchange chamber C. The second cooling unit E063 has one heat exchange chamber D, with two non-communicating fifth and sixth heat exchange tubes installed in heat exchange chamber D. The first, third, and fifth heat exchange tubes are connected in sequence, as are the second, fourth, and sixth heat exchange tubes.

[0045] Reactant gas A enters the first heat exchange tube, the third heat exchange tube, and the fifth heat exchange tube in sequence. After condensation and cooling, it enters the separator V01A. The separator V01A and the separated gas enter the shell side of the heat exchange chamber A to exchange heat with the reactant gas A, and then enter the shell side of the heat exchanger E04B.

[0046] The reaction gas B passes through the second, fourth, and sixth heat exchange tubes in sequence, and after condensation and cooling, it enters the separator V01B. The separator V01B and the separated gas enter the shell side of the heat exchange chamber B to exchange heat with the reaction gas B, and then enter the inlet of the circulating machine CO2.

[0047] The liquid ammonia refrigerant first enters the shell side of heat exchanger E07 to exchange heat with the finished ammonia, and then enters heat exchange chambers C and D respectively to exchange heat with reaction gas A and reaction gas B. After forming gaseous refrigerant, it is discharged from the combined cooling condenser E06.

[0048] The process flow of this invention is applicable to process systems with a single ammonia synthesis capacity exceeding 900 Kt / a (hourly liquid ammonia production exceeding 112.5 tons).

[0049] By controlling the following process parameters, the process flow of this invention can reduce the synthesis cycle volume by 45% to 50% compared to the existing single-tower circulation method, thereby saving cycle power consumption.

[0050] The flow rate of the feed gas at the inlet of the ammonia synthesis tower R01A is 600–650 kNm³. 3 The flow rate is 14–15 MPaG / h, pressure is 175–185℃, temperature is 420–430℃ for the reaction gas at the outlet of ammonia synthesis tower A, and the flow rate of the raw material gas at the inlet of ammonia synthesis tower B is 600–650 kNm³ / h. 3 / h, pressure is 13~14MPaG, temperature is 165~175℃; the temperature of the reaction gas B at the outlet of ammonia synthesis tower B is 410~420℃.

[0051] The total flow rate of the recycle gas and fresh feed gas added to the primary ammonia synthesis reaction is 190–200 kNm. 3 The flow rate is 190–200 kNm³ / h, the pressure is 13–14 MPaG, and the temperature is 105–115 °C. 3 The flow rate is 13–14 MPaG / h, pressure is 13–14 MPaG, temperature is 105–115℃; the total flow rate of fresh feed gas is 370–380 kNm³. 3 / h.

[0052] The temperature of the raw gas A entering separator A is -5 to -15℃, and the temperature of the raw gas B entering separator B is -5 to -15℃; the temperature of the gas exiting the combined cooling condenser after exchanging heat with the reaction gas A is 30 to 40℃; the temperature of the gas exiting the combined cooling condenser after exchanging heat with the reaction gas B is 30 to 40℃.

[0053] For example, in this embodiment,

[0054] The flow rate of the feed gas at the inlet of the ammonia synthesis tower R01A is 620.00 kNm³. 3 / h, pressure is 14.45MPaG, temperature is 180℃; the temperature of the reaction gas A at the outlet of R01A of the ammonia synthesis tower is 422.7℃;

[0055] The flow rate of the feed gas at the inlet of the ammonia synthesis tower R01B is 634.56 kNm. 3 / h, pressure is 13.78MPaG, temperature is 170℃; the temperature of the reaction gas B at the outlet of R01B of the ammonia synthesis tower is 416.8℃;

[0056] The total flow rate of the recycle gas and fresh feed gas added to the primary ammonia synthesis reaction is 193.36 kNm. 3 The flow rate is 193.36 kNm³ / h, the pressure is 13.88 MPaG, and the temperature is 110℃. The total flow rate of the recycle gas and fresh feed gas added to the secondary ammonia synthesis reaction is 193.36 kNm³. 3 / h, pressure is 13.88MPaG, temperature is 110℃;

[0057] The total flow rate of fresh feed gas is 376 kNm. 3 / h; the temperature of the feed gas A entering separator V01A is -10℃, and the flow rate is 531.40 kNm³ / h. 3 The feed gas B entering separator V01B has a temperature of -10℃ and a flow rate of 542.33 kNm³ / h. 3 / h;

[0058] The gas exiting the combined cooling condenser E06, after exchanging heat with reaction gas A, has a temperature of 35℃ and a flow rate of 441.20 kNm³.3 / h; The temperature of the gas exiting the combined cooling condenser E06 after exchanging heat with the reaction gas B is 35℃, and the flow rate is 426.64KNm³ / h. 3 / h.

[0059] By controlling the above process parameters, the technical effects of achieving an ammonia content of 2.6424Vmol% at the inlet of ammonia synthesis tower R01A, a net ammonia value of 17.11%, and a recycle ratio of 1.6481, and an ammonia content of 2.6027Vmol% at the inlet of ammonia synthesis tower R01B, a net ammonia value of 17.45%, and a recycle ratio of 1.6868 can be achieved.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A bipolar single-cycle ammonia synthesis method, characterized in that, Includes the following steps: (1) The gas coming out of the circulating machine enters the shell side of the heat exchanger A and is heated, and then enters the ammonia synthesis tower A to carry out the first-stage ammonia synthesis reaction, generating reaction gas A; (2) The generated reaction gas A enters the tube side of the steam superheater A, the tube side of the steam generator A, the tube side of the feedwater preheater A, the tube side of the heat exchanger A, and the shell side of the water cooler A in sequence. After cooling and completing heat recovery, it enters the combined cooling condenser for cold energy recovery. (3) After the cold energy recovery is completed, the reaction gas A enters the separator A for gas-liquid separation. The separated gas returns to the combined cooling condenser to exchange heat with the reaction gas A, and then enters the shell side of the heat exchanger B. After the temperature is raised, the gas enters the ammonia synthesis tower B for secondary ammonia synthesis reaction to generate reaction gas B. (4) The generated reaction gas B enters the tube side of the steam superheater B, the tube side of the steam generator B, the tube side of the feedwater preheater B, the tube side of the heat exchanger B, and the shell side of the water cooler B in sequence. After cooling and completing heat recovery, it enters the combined cooling condenser for cold energy recovery. (5) After the cold energy recovery is completed, the reaction gas B enters the separator B for gas-liquid separation. The separated gas returns to the combined cooling condenser to exchange heat with the reaction gas B and then enters the inlet of the circulating machine. (6) The crude ammonia separated by separator A and separator B enters the flash tank for flash evaporation. After the flash vapor enters the compressor to increase the pressure, part of it enters the inlet of the circulating machine and is fed into the primary ammonia synthesis reaction; the other part enters the shell side of heat exchanger B and is fed into the secondary ammonia synthesis reaction. (7) Fresh raw gas from the purified and refined process also enters the compressor to increase the pressure, and part of it is fed into the primary ammonia synthesis reaction; the other part is fed into the secondary ammonia synthesis reaction. The combined cooling condenser includes a cold exchange unit, a first cooling unit, and a second cooling unit. Reactant gas A and reactant gas B enter the cold exchange unit, the first cooling unit, and the second cooling unit in sequence, and after being condensed and cooled separately, they enter separator A and separator B respectively.

2. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, Fresh raw material gas is added to the primary ammonia synthesis reaction and the secondary ammonia synthesis reaction in a 1:1 ratio.

3. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, Boiler feedwater from the boiler workshop enters the shell side of feedwater preheater A, where its temperature is increased before entering the shell side of steam generator A to generate saturated steam A. The generated saturated steam A then enters the shell side of steam superheater A to generate superheated steam A before being discharged. The other stream enters the shell side of feedwater preheater B, where its temperature is increased before entering the shell side of steam generator B to generate saturated steam B. The generated saturated steam B then enters the shell side of steam superheater B to generate superheated steam B before being discharged.

4. The bipolar single-cycle ammonia synthesis method according to claim 3, characterized in that, The superheated steam B discharged from the superheater B enters the shell side of the superheater A together with the saturated steam A.

5. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, Cooling water A and cooling water B are respectively introduced into the shell side of water cooler A and water cooler B.

6. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, The gases separated by separators A and B enter the cold exchange unit and exchange heat with reaction gas A and reaction gas B respectively. Liquid refrigerant is introduced into the first cooling unit and the second cooling unit respectively. The liquid refrigerant is heated by reaction gas A and reaction gas B to form gaseous refrigerant, which is then discharged from the first cooling unit and the second cooling unit respectively.

7. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, The flow rate of the feed gas at the inlet of ammonia synthesis tower A is 600–650 kNm³. 3 The flow rate is 14–15 MPaG / h, pressure is 175–185℃, and temperature is 420–430℃ for the reaction gas at the outlet of ammonia synthesis tower A; the flow rate of the raw material gas at the inlet of ammonia synthesis tower B is 600–650 kNm³ / h. 3 / h, pressure is 13~14MPaG, temperature is 165~175℃; the temperature of the reaction gas B at the outlet of ammonia synthesis tower B is 410~420℃.

8. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, The total flow rate of the recycle gas and fresh feed gas added to the primary ammonia synthesis reaction is 190–200 kNm. 3 The flow rate is 190–200 kNm³ / h, the pressure is 13–14 MPaG, and the temperature is 105–115 °C. 3 The flow rate is 13–14 MPaG / h, pressure is 13–14 MPaG, temperature is 105–115℃; the total flow rate of fresh feed gas is 370–380 kNm³. 3 / h.

9. The bipolar single-cycle ammonia synthesis method according to claim 1, characterized in that, The temperature of the raw gas A entering separator A is -5 to -15℃, and the temperature of the raw gas B entering separator B is -5 to -15℃; the temperature of the gas exiting the combined cooling condenser after exchanging heat with the reaction gas A is 30 to 40℃; the temperature of the gas exiting the combined cooling condenser after exchanging heat with the reaction gas B is 30 to 40℃.

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