System and process for coupling synthetic ammonia with downstream ammonia processing device

Abstract

The invention provides a system and process for coupling synthesis ammonia with a downstream ammonia processing device, the system comprises a primary ammonia cooler and a secondary ammonia cooler, synthesis gas is cooled by a tube pass of the primary ammonia cooler and then enters a tube pass of the secondary ammonia cooler, and liquid ammonia is produced after secondary cooling; the system further comprises an ammonia receiving tank, after liquid ammonia in the ammonia receiving tank is gasified through a shell pass of the first-stage ammonia cooler, liquid-phase output enters a shell pass of the second-stage ammonia cooler, gas ammonia is output after secondary gasification, and gas-phase output enters the ammonia receiving tank after being pressurized and cooled; and gas ammonia produced by a shell pass of the second-stage ammonia cooler and gas ammonia pressurized by the gas ammonia supercharger and from low-temperature methanol washing are conveyed to a downstream ammonia processing device taking the gas ammonia as a raw material. An ammonia evaporator required by a downstream device in the traditional process is omitted, and the equipment investment is reduced; and moreover, ammonia synthesis low-grade heat is fully utilized, energy consumption required by liquid ammonia gasification of a downstream device is saved, and the energy consumption is remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic ammonia and ammonia chemical processing, and in particular relates to a system and process for coupling synthetic ammonia with a downstream ammonia processing device. Background Art

[0002] In the existing production process of synthetic ammonia combined with downstream chemical plants (nitric acid plants, caprolactam plants, hydrocyanic acid plants, acrylonitrile plants, hydrazine hydrate plants, ammonium phosphate plants, soda ash plants, etc.), the gaseous ammonia produced by the primary ammonia cooler, secondary ammonia cooler and low-temperature methanol washing ammonia cooler of ammonia synthesis is compressed to 1.7MPaA in the ammonia synthesis refrigeration station, and then a large amount of circulating water is used to cool the gaseous ammonia into liquid ammonia for recycling; while in downstream chemical plants (such as nitric acid, caprolactam, etc.), gaseous ammonia is required as raw material, and liquid ammonia storage tanks and ammonia evaporators are required to gasify the liquid ammonia produced by ammonia synthesis and use it as a reaction raw material. This traditional process does not make rational use of the energy of the entire plant, the energy consumption of the device is large, and the operating cost is high. In addition, the equipment is set up repeatedly, which increases equipment investment. Summary of the invention

[0003] In view of this, the present invention aims to propose a system and process for coupling synthetic ammonia with a downstream ammonia processing device. In addition to the output of liquid ammonia, gaseous ammonia is separated and sent to a downstream ammonia processing device using gaseous ammonia as raw material, so as to reduce energy consumption and save equipment investment.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A system for coupling ammonia synthesis with a downstream ammonia processing device, used for processing gaseous ammonia from low-temperature methanol washing and synthesis gas from an ammonia synthesis cold exchanger, the system comprising a primary ammonia cooler and a secondary ammonia cooler, the synthesis gas is cooled through the tube side of the primary ammonia cooler and then enters the tube side of the secondary ammonia cooler, and liquid ammonia is produced after secondary cooling;

[0006] The system also includes an ammonia receiving tank, wherein the liquid ammonia in the ammonia receiving tank is gasified through the shell side of the first-stage ammonia cooler, and the liquid phase output enters the shell side of the second-stage ammonia cooler, and after secondary gasification, gaseous ammonia is output, and the gas phase output enters the ammonia receiving tank after being pressurized and cooled;

[0007] The gaseous ammonia produced by the shell side of the secondary ammonia cooler and the gaseous ammonia from the low-temperature methanol wash pressurized by the gaseous ammonia booster are transported to the downstream ammonia processing device using gaseous ammonia as raw material.

[0008] Furthermore, a pipeline is additionally provided on the gas phase output pipeline of the shell side of the first-stage ammonia cooler, which can transport the ammonia gas generated by gasification to a downstream ammonia processing device using gaseous ammonia as raw material.

[0009] Furthermore, the gaseous ammonia produced in the shell side of the secondary ammonia cooler is pressurized by the gaseous ammonia booster and then transported to the downstream ammonia processing device.

[0010] Furthermore, the system of the synthetic ammonia coupled to the downstream ammonia processing device also includes an ammonia compressor, a final outlet water-cooled cooler and a water condenser. Part of the gas phase output of the shell side of the first-stage ammonia cooler enters the ammonia receiving tank after being pressurized and cooled by the ammonia compressor, the final outlet water-cooled cooler and the water condenser.

[0011] Furthermore, the system for coupling the synthetic ammonia to the downstream ammonia processing device also includes an ammonia synthesis water cooler and a cold exchanger, and the synthetic gas enters the tube side of the primary ammonia cooler after being cooled by the ammonia synthesis water cooler and the cold exchanger.

[0012] Furthermore, the system of the synthetic ammonia coupled to the downstream ammonia processing device also includes a high-pressure ammonia separator and a low-pressure ammonia separator. After the liquid phase produced by the tube side of the secondary ammonia cooler is separated into circulating gas by the high-pressure ammonia separator, the remaining ammonia is further purified by the low-pressure ammonia separator to produce liquid ammonia.

[0013] Furthermore, the downstream ammonia processing device includes at least one of a hydrocyanic acid device, an acrylonitrile device, a hydrazine hydrate device, a diammonium phosphate device or a soda ash device.

[0014] A system for synthesizing ammonia coupled with a downstream nitric acid device comprises the above system.

[0015] A system for coupling a synthetic ammonia with a downstream caprolactam device, the system comprising the above system.

[0016] According to the above-mentioned operation process of the system of synthetic ammonia coupled with a downstream ammonia processing unit, when the operating pressure of the reactor of the downstream ammonia processing unit is 0-0.2MPaG, it is only necessary to pressurize the low-temperature methanol scrubber ammonia to a pressure higher than the operating pressure of the downstream ammonia processing unit, and then according to the amount of gas ammonia required by the downstream unit, part of the low-temperature methanol scrubber ammonia is produced, or all of it is produced, or after all of it is produced, the gas ammonia of the secondary ammonia cooler and the gas ammonia of the primary ammonia cooler are used to supplement the gas ammonia gap required by the downstream ammonia processing unit;

[0017] Or, when the operating pressure of the reactor of the downstream ammonia processing unit is higher than 0.2MPaG but lower than 0.8MPaG, the low-temperature methanol scrubber ammonia and the gas ammonia of the secondary ammonia cooler need to be pressurized to a pressure higher than the operating pressure of the downstream ammonia processing unit, and then the pressurized low-temperature methanol scrubber ammonia and the gas ammonia of the secondary ammonia cooler are partially or fully produced, or the gas ammonia of the primary ammonia cooler is used to supplement the gas ammonia gap required by the downstream ammonia processing unit after all the gas ammonia is produced;

[0018] Alternatively, when the operating pressure of the reactor of the downstream ammonia processing unit is higher than 0.8MPaG, the low-temperature methanol scrubber ammonia, the secondary ammonia cooler ammonia and the primary ammonia cooler ammonia are required to be pressurized to a pressure higher than the operating pressure of the downstream chemical unit, and then the required amount of ammonia for the downstream ammonia processing unit is extracted from the compressor interstage.

[0019] Compared with the prior art, the system and process of the synthetic ammonia coupled with the downstream ammonia processing device created by the present invention have the following advantages:

[0020] 1. The invention provides a system and process for coupling ammonia synthesis with a downstream ammonia processing device. The ammonia synthesis device is coupled with the downstream ammonia processing device. Low-temperature methanol-washed ammonia, secondary ammonia cooler gas ammonia or primary ammonia cooler gas ammonia is used as a raw material for the downstream device and sent to the downstream ammonia processing device using gas ammonia as a raw material, thereby eliminating the ammonia evaporator required for the downstream device in the traditional process and reducing equipment investment. In addition, the low-grade heat of ammonia synthesis is fully utilized, eliminating the energy consumption required for gasification of liquid ammonia in the downstream device, and significantly reducing energy consumption.

[0021] 2. The invention provides a system and process for coupling ammonia synthesis with a downstream ammonia processing device. The gaseous ammonia part of the ammonia synthesis device is sent out of the boundary area as the raw material of the downstream device, so that the amount of gaseous ammonia required to be processed by the ammonia compressor of the ammonia synthesis refrigeration station is reduced, and the equipment cost of the ammonia compressor is reduced. At the same time, the energy consumption of the ammonia compressor and the circulating water consumption of the final outlet water cooler and water condenser of the ammonia compressor are reduced, thereby reducing the energy consumption of the ammonia synthesis device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 It is a schematic diagram of the overall structure of a scheme 1 of a system for coupling ammonia synthesis with a downstream ammonia processing device according to the present invention;

[0024] Figure 2 This is a schematic diagram of the overall structure of Scheme 2 of a system for coupling ammonia synthesis with a downstream ammonia processing device according to the present invention.

[0025] Description of reference numerals:

[0026] 1- ammonia compressor; 2- gas ammonia booster; 3- final outlet water-cooled cooler; 4- water condenser; 5- ammonia synthesis water cooler; 6- cold exchanger; 7- primary ammonia cooler; 8- secondary ammonia cooler; 9- high-pressure ammonia separator; 10- low-pressure ammonia separator; 11- ammonia receiving tank. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0029] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0030] The present embodiment provides a system for coupling ammonia synthesis with a downstream ammonia processing device, which is used to process gaseous ammonia from low-temperature methanol washing and synthesis gas from an ammonia synthesis cold exchanger 6. The system includes a primary ammonia cooler 7 and a secondary ammonia cooler 8. The synthesis gas is cooled through the tube side of the primary ammonia cooler 7 and then enters the tube side of the secondary ammonia cooler 8. After secondary cooling, liquid ammonia is produced. The system also includes an ammonia receiving tank 11. After the liquid ammonia in the ammonia receiving tank 11 is gasified through the shell side of the primary ammonia cooler 7, liquid phase is produced, that is, the remaining liquid ammonia enters the shell side of the secondary ammonia cooler 8, and after secondary gasification, diammonia cold gas ammonia (AG2) is produced. The gas phase is produced, that is, the monoammonia cold gas ammonia (AG1) generated by gasification in the primary ammonia cooler 7 enters the ammonia receiving tank 11 after being pressurized and cooled. The gaseous ammonia produced from the shell side of the secondary ammonia cooler 8 and the gaseous ammonia (AG3) from the low-temperature methanol washing that is pressurized by the gaseous ammonia booster 2 are transported to a downstream ammonia processing device using gaseous ammonia as a raw material.

[0031] In the system of synthetic ammonia coupled with a downstream ammonia processing device provided in this embodiment, a pipeline is additionally provided on the gas phase output pipeline of the shell side of the primary ammonia cooler 7, which can transport the ammonia gas generated by gasification to the downstream ammonia processing device using gas ammonia as raw material. In the actual production process, when the demand for ammonia consumption of the downstream equipment is high, part of the ammonia cooling gas ammonia (AG1) can be extracted and sent to the downstream, otherwise all of it is cooled and liquefied and then enters the ammonia receiving tank 11.

[0032] The system of synthetic ammonia coupled with downstream ammonia processing device provided in this embodiment includes two structural forms: one is as follows: Figure 1 As shown, the gaseous ammonia produced by the shell side of the secondary ammonia cooler 8 is pressurized by the gaseous ammonia booster 2 and then transported to the downstream ammonia processing device. Figure 2 As shown, the gaseous ammonia produced by the shell side of the secondary ammonia cooler 8 is directly transported to the downstream ammonia processing device. In the actual production process, when the downstream ammonia demanding device has a high pressure requirement for gaseous ammonia, the diammonia cooler gaseous ammonia (AG2) can be pressurized by the gaseous ammonia booster 2 and then transported to the downstream, otherwise it can be directly transported to the downstream without being pressurized.

[0033] As a preferred method, in this system, the system of synthetic ammonia coupled with the downstream ammonia processing device also includes an ammonia compressor 1, a final outlet water-cooled cooler 3 and a water condenser 4. Part of the gas phase output of the shell side of the first-stage ammonia cooler 7 is pressurized and cooled by the ammonia compressor 1, the final outlet water-cooled cooler 3 and the water condenser 4 before entering the ammonia receiving tank 11.

[0034] The system of synthetic ammonia coupled with the downstream ammonia processing device also includes an ammonia synthesis water cooler 5 and a cold exchanger 6. The synthetic gas enters the tube side of the primary ammonia cooler 7 after being cooled by the ammonia synthesis water cooler 5 and the cold exchanger 6.

[0035] The system of synthetic ammonia coupled with downstream ammonia processing equipment also includes a high-pressure ammonia separator 9 and a low-pressure ammonia separator 10. The liquid phase material produced by the tube side of the secondary ammonia cooler 8 is separated into circulating gas by the high-pressure ammonia separator 9, and the remaining ammonia is further purified by the low-pressure ammonia separator 10 to produce liquid ammonia.

[0036] In the system of synthetic ammonia coupled with downstream ammonia processing devices provided in this embodiment, the primary ammonia cooler 7, the secondary ammonia cooler 8, and the low-temperature methanol scrubber ammonia from the ammonia synthesis can be partially or completely extracted according to the needs of the downstream devices and used as the reaction raw materials for the downstream chemical devices, thereby reducing the amount of gas ammonia that needs to be processed by the ammonia compressor 1 in the process flow of the ammonia synthesis refrigeration station. In addition, according to the reaction pressure and the required gas ammonia flow rate of the downstream chemical device, the heat load of the water cooler, the cold exchanger 6, the primary ammonia cooler 7, and the secondary ammonia cooler 8 of the ammonia synthesis device and the operating pressure of the primary ammonia cooler 7 and the secondary ammonia cooler 8 can be adjusted, thereby minimizing the equipment investment and energy consumption required for the entire chemical device.

[0037] The system of synthetic ammonia coupled with a downstream ammonia processing device provided in this embodiment, when the operating pressure of the reactor of the downstream chemical device is 0-0.2MPaG, it is only necessary to increase the pressure of the low-temperature methanol scrubbing ammonia by 50kPa higher than the operating pressure of the downstream chemical device, and then according to the amount of gas ammonia required by the downstream device, the low-temperature methanol scrubbing ammonia is partially produced, or all produced, or all produced and then the gas ammonia of the secondary ammonia cooler 8 and the gas ammonia of the primary ammonia cooler 7 are used to supplement the gas ammonia gap required by the downstream chemical device;

[0038] When the operating pressure of the reactor of the downstream chemical plant is higher than 0.2MPaG but lower than 0.8MPaG, the low-temperature methanol scrubber ammonia and the secondary ammonia cooler 8 gas ammonia need to be pressurized to 50kPa higher than the operating pressure of the downstream chemical plant, and then the pressurized low-temperature methanol scrubber ammonia and the secondary ammonia cooler 8 gas ammonia are partially or fully produced, or the gas ammonia of the primary ammonia cooler 7 is used to supplement the gas ammonia gap required by the downstream chemical plant after all the gas ammonia is produced;

[0039] When the operating pressure of the reactor of the downstream chemical plant is higher than 0.8MPaG, the low-temperature methanol-washed ammonia, the secondary ammonia cooler 8 ammonia and the primary ammonia cooler 7 ammonia are required to be pressurized to 50kPa higher than the operating pressure of the downstream chemical plant, and then the required ammonia for the downstream chemical plant is extracted from the compressor section, and the remaining ammonia is further compressed.

[0040] In actual production, you can choose according to the pressure requirements Figure 1 or Figure 2 The system provided.

[0041] The present invention proposes a novel process flow, coupling an ammonia synthesis unit with a downstream ammonia processing unit, using low-temperature methanol-washed ammonia from the ammonia synthesis unit, gaseous ammonia from a secondary ammonia cooler 8 or gaseous ammonia from a primary ammonia cooler 7 as raw materials for the downstream unit, and delivering them to the reactor of the downstream unit, thereby eliminating the need for a liquid ammonia storage tank and an ammonia evaporator of the downstream ammonia processing unit.

[0042] The novel ammonia synthesis coupled with downstream chemical plant process described in the present invention reduces the equipment investment and energy consumption of the downstream chemical plant, and also reduces the operating load, equipment investment and energy consumption of the refrigeration station of the ammonia synthesis plant, and makes full use of the heat of the whole plant, streamlines the equipment and improves the energy utilization efficiency.

[0043] The novel ammonia synthesis coupled downstream chemical plant process flow of the present invention is characterized in that the heat load of the ammonia synthesis plant water cooler, cold exchanger 6, primary ammonia cooler 7, and secondary ammonia cooler 8 and the operating pressure of the primary ammonia cooler 7 and secondary ammonia cooler 8 can be adjusted according to the different gas ammonia flow rates and pressures required by the reactors of the downstream chemical plants using ammonia as raw materials, thereby minimizing the equipment investment and energy consumption of the entire plant.

[0044] The new process of ammonia synthesis coupled with downstream nitric acid device of the present invention is characterized in that: the pressure of gas ammonia required by the downstream nitric acid device (300,000 tons / year) is about 0.4MPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13MPaG, and the pressure of low-temperature methanol scrubber ammonia is about -0.02MPaG; adopting the new process flow of the present invention, after the low-temperature methanol scrubber ammonia and the gas ammonia of the second-stage ammonia cooler 8 are pressurized to 0.45MPaG, the gas ammonia required by the downstream nitric acid device is extracted as the raw material of the downstream device, and the remaining gas ammonia is mixed with the gas ammonia of the first-stage ammonia cooler 7 and enters the high-pressure section of the ammonia compressor 1 for further compression. Calculation shows that the power of the ammonia compressor 1 of the new process flow is reduced by 860kW, and the circulating water consumption is reduced by 417404kg / h.

[0045] The new process of ammonia synthesis coupled with downstream caprolactam device of the present invention is characterized in that: the pressure of gas ammonia required by the downstream caprolactam device (300,000 tons / year) is about 0.4MPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13MPaG, and the pressure of low-temperature methanol scrubbing ammonia is about -0.02MPaG; the new process of the present invention is adopted, and the low-temperature methanol scrubbing ammonia and the gas ammonia of the second-stage ammonia cooler 8 are pressurized to 0.45MPaG, and the gas ammonia required by the downstream caprolactam device is extracted as the raw material of the downstream device, and the remaining gas ammonia is mixed with the gas ammonia of the first-stage ammonia cooler 7 and enters the high-pressure section of the compressor for further compression. Calculation shows that the power of the ammonia compressor 1 of the new process of ammonia synthesis is reduced by 1530kW, and the circulating water consumption is reduced by 728593kg / h.

[0046] The new process of ammonia synthesis coupled with downstream hydrocyanic acid device (Ansler process) of the present invention is characterized in that: the pressure of gas ammonia required by the downstream hydrocyanic acid device (300,000 tons / year) is 10-50 kPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45 MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13 MPaG, and the pressure of low-temperature methanol scrubbing ammonia is -0.02 MPaG; the new process of the present invention is adopted, the low-temperature methanol scrubbing ammonia is pressurized to 0.1 MPaG and then all extracted, the gas ammonia of the second-stage ammonia cooler 8 is directly extracted, the gas ammonia of the first-stage ammonia cooler 7 is partially extracted, and the remaining gas ammonia of the first-stage ammonia cooler 7 enters the first-stage ammonia cooler 7 compressor for compression. Calculation shows that the power of the ammonia compressor 1 of the new process of ammonia synthesis is reduced by 4280 kW, and the circulating water consumption is reduced by 1237451 kg / h.

[0047] The new process of ammonia synthesis coupled with a downstream acrylonitrile device (ammonia oxidation method) of the present invention is characterized in that: the pressure of gas ammonia required by the downstream acrylonitrile device (300,000 tons / year) is 10-60 kPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45 MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13 MPaG, and the pressure of low-temperature methanol scrubbing ammonia is about -0.02 MPaG; the new process flow of the present invention is adopted, the low-temperature methanol scrubbing ammonia is pressurized to 0.1 MPaG and then all extracted, the gas ammonia of the second-stage ammonia cooler 8 is directly extracted, the gas ammonia of the first-stage ammonia cooler 7 is partially extracted, and the remaining gas ammonia of the first-stage ammonia cooler 7 enters the first-stage ammonia cooler 7 compressor for compression. Calculation shows that the power of the ammonia compressor 1 of the new process flow can be reduced by 3600 kW, and the circulating water consumption can be reduced by 918617 kg / h.

[0048] The new process of ammonia synthesis coupled with a downstream hydrazine hydrate device (hydrogen peroxide method) of the present invention is characterized in that: the pressure of gas ammonia required by the downstream hydrazine hydrate device (50,000 tons / year) is 10-60 kPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45 MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13 MPaG, and the pressure of low-temperature methanol scrubbing ammonia is about -0.02 MPaG; using the new process of the present invention, it is necessary to pressurize the low-temperature methanol scrubbing ammonia to 0.1 MPaG and then partially extract it, and the remaining gas ammonia and the gas ammonia of the second-stage ammonia cooler 8 are compressed to 0.45 MPaG, and then continue to be compressed with the gas ammonia of the first-stage ammonia cooler 7. Calculation shows that the power of the ammonia compressor 1 of the new process of ammonia synthesis is reduced by 511 kW, and the circulating water consumption is reduced by 138476 kg / h.

[0049] The new process of ammonia synthesis coupled with downstream diammonium phosphate device of the present invention is characterized in that: the pressure of gas ammonia required by the downstream diammonium phosphate device (600,000 tons / year) is 0.2MPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13MPaG, and the pressure of low-temperature methanol scrubber ammonia is about -0.02MPaG; the new process of the present invention is adopted, the low-temperature methanol scrubber ammonia and the gas ammonia of the second-stage ammonia cooler 8 are pressurized to 0.25MPaG and then partially extracted, and the remaining gas ammonia is compressed to 0.45MPaG and then mixed with the gas ammonia of the first-stage ammonia cooler 7 for further compression. Calculation shows that the power of the ammonia compressor 1 of the new process of ammonia synthesis is reduced by 1630kW, and the circulating water consumption is reduced by 788877kg / h.

[0050] The new process of ammonia synthesis coupled with downstream soda ash device of the present invention is characterized in that: the pressure of gas ammonia required by the downstream soda ash device (700,000 tons / year) is 0.01MPaG; the gas ammonia pressure of the first-stage ammonia cooler 7 of the upstream ammonia synthesis device (350,000 tons / year) is 0.45MPaG, the gas ammonia pressure of the second-stage ammonia cooler 8 is 0.13MPaG, and the pressure of low-temperature methanol scrubbing ammonia is about -0.02MPaG; the new process of the present invention is adopted to pressurize the low-temperature methanol scrubbing ammonia to 0.1MPaG, and then all the gas ammonia is produced, the gas ammonia of the second-stage ammonia cooler 8 is directly produced, and the gas ammonia of the first-stage ammonia cooler 7 is compressed. Calculation shows that the power of the ammonia compressor 1 of the new process of ammonia synthesis is reduced by 3206kW, and the circulating water consumption is reduced by 904023kg / h.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for ammonia synthesis coupled with a downstream ammonia processing unit, for processing gaseous ammonia from low temperature methanol wash and synthesis gas from an ammonia synthesis cold exchanger (6), characterized in that: The system comprises a primary ammonia cooler (7) and a secondary ammonia cooler (8); the synthesis gas is cooled through the tube side of the primary ammonia cooler (7) and then enters the tube side of the secondary ammonia cooler (8); and liquid ammonia is produced after secondary cooling; The system further comprises an ammonia receiving tank (11), wherein the liquid ammonia in the ammonia receiving tank (11) is gasified in the shell side of the first ammonia cooler (7), and the liquid phase output enters the shell side of the second ammonia cooler (8), and after secondary gasification, gaseous ammonia is output, and the gas phase output enters the ammonia receiving tank (11) after being pressurized and cooled; The gaseous ammonia produced by the shell side of the secondary ammonia cooler (8) and the gaseous ammonia from the low-temperature methanol wash pressurized by the gaseous ammonia booster (2) are transported to a downstream ammonia processing device that uses gaseous ammonia as raw material.

2. The system of synthetic ammonia coupled with downstream ammonia processing equipment according to claim 1, characterized in that: The gas phase output pipeline of the shell side of the first-stage ammonia cooler (7) is further provided with a pipeline, which can transport the ammonia gas generated by gasification to the downstream ammonia processing device using gaseous ammonia as raw material.

3. The system of synthetic ammonia coupled with downstream ammonia processing equipment according to claim 1, characterized in that: The gaseous ammonia produced in the shell side of the secondary ammonia cooler (8) is pressurized by the gaseous ammonia booster (2) and then transported to the downstream ammonia processing device.

4. The system of synthetic ammonia coupled with downstream ammonia processing equipment according to claim 1, characterized in that: It also includes an ammonia compressor (1), a final outlet water-cooled cooler (3) and a water condenser (4); part of the gas phase output of the shell side of the first-stage ammonia cooler (7) enters the ammonia receiving tank (11) after being pressurized and cooled by the ammonia compressor (1), the final outlet water-cooled cooler (3) and the water condenser (4).

5. The system of synthetic ammonia coupled with downstream ammonia processing equipment according to claim 1, characterized in that: It also includes an ammonia synthesis water cooler (5) and a cold exchanger (6). The synthesis gas is cooled by the ammonia synthesis water cooler (5) and the cold exchanger (6) and then enters the tube side of the first-stage ammonia cooler (7).

6. The system of synthetic ammonia coupled with downstream ammonia processing equipment according to claim 1, characterized in that: It also includes a high-pressure ammonia separator (9) and a low-pressure ammonia separator (10). After the liquid phase material produced by the tube side of the secondary ammonia cooler (8) is separated into circulating gas by the high-pressure ammonia separator (9), the remaining ammonia is further purified by the low-pressure ammonia separator (10) to produce liquid ammonia.

7. The system of synthetic ammonia coupled with downstream ammonia processing equipment according to claim 1, characterized in that: The downstream ammonia processing unit includes at least one of a hydrocyanic acid unit, an acrylonitrile unit, a hydrazine hydrate unit, a diammonium phosphate unit or a soda ash unit.

8. A system for coupling ammonia synthesis with a downstream nitric acid unit, characterized in that: The system comprises the system according to any one of claims 1-6.

9. A system for coupling ammonia synthesis with a downstream caprolactam unit, characterized in that: The system comprises the system according to any one of claims 1-6.

10. The operating process of the system of synthetic ammonia coupled with a downstream ammonia processing unit according to any one of claims 1 to 6, characterized in that: When the operating pressure of the reactor of the downstream ammonia processing unit is 0-0.2MPaG, it is only necessary to pressurize the low-temperature methanol scrubber ammonia to a pressure higher than the operating pressure of the downstream ammonia processing unit, and then according to the amount of gas ammonia required by the downstream unit, part of the low-temperature methanol scrubber ammonia is produced, or all of it is produced, or all of it is produced and then the gas ammonia of the secondary ammonia cooler and the gas ammonia of the primary ammonia cooler are used to supplement the gas ammonia gap required by the downstream ammonia processing unit; Or, when the operating pressure of the reactor of the downstream ammonia processing unit is higher than 0.2MPaG but lower than 0.8MPaG, the low-temperature methanol scrubber ammonia and the gas ammonia of the secondary ammonia cooler need to be pressurized to a pressure higher than the operating pressure of the downstream ammonia processing unit, and then the pressurized low-temperature methanol scrubber ammonia and the gas ammonia of the secondary ammonia cooler are partially or fully produced, or the gas ammonia of the primary ammonia cooler is used to supplement the gas ammonia gap required by the downstream ammonia processing unit after all the gas ammonia is produced; Alternatively, when the operating pressure of the reactor of the downstream ammonia processing unit is higher than 0.8MPaG, the low-temperature methanol scrubber ammonia, the secondary ammonia cooler ammonia and the primary ammonia cooler ammonia are required to be pressurized to a pressure higher than the operating pressure of the downstream chemical unit, and then the required amount of ammonia for the downstream ammonia processing unit is extracted from the compressor interstage.

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