Synthetic ammonia plant acid gas comprehensive utilization device and comprehensive utilization method

Abstract

The application belongs to a synthetic ammonia device acid gas comprehensive utilization device and a comprehensive utilization method; including a gasification system acid gas unit, a low-temperature methanol washing system acid gas unit and a shift stripping tower acid gas unit, the gasification system acid gas unit is connected with the heat tracing gas import of the Claus combustion furnace and the heat tracing gas import of the waste gas combustion furnace in the sulfur preparation unit respectively; the low-temperature methanol washing system acid gas unit is connected with the import of the Claus combustion furnace, the shift stripping tower acid gas unit is connected with the import of the waste gas combustion furnace; the top tail gas outlet of the waste gas combustion furnace is connected with a tail gas treatment unit, the tail gas treatment unit is coupled with an ammonium sulfite solution preparation unit, the ammonium sulfite solution preparation unit is connected with an ammonium sulfate preparation unit; having comprehensive treatment of the acid gas in the synthetic ammonia device, and realizing the circulating operation of the whole system, not only solving the environmental protection emission problem of the enterprise, but also bringing great profit to the enterprise.

Description

Technical Field

[0001] This invention belongs to the field of acid gas treatment technology, and particularly relates to a comprehensive utilization device and method for acid gas from a synthetic ammonia unit. Background Technology

[0002] In existing technologies, acidic gases generated by the high-temperature hot water tower in the gasification system are condensed and directly discharged into a flare for combustion. These gases are industrial gases, and while flare combustion can reduce the direct emission of harmful substances, it cannot completely eliminate environmental pollution. The combustion process may produce secondary pollutants such as sulfur dioxide and nitrogen oxides, which pose potential hazards to the environment and human health. Furthermore, these industrial gases may contain flammable and explosive components, posing safety risks if directly discharged into a flare. Improper gas mixing ratios could lead to explosions. Moreover, based on environmental requirements and the company's own understanding, how to treat this gas has become an urgent technical problem to be solved. Simultaneously, the acidic gas components in ammonia synthesis units vary, and conventional operations involve separate treatment for each component. This approach suffers from high investment and operating costs, hindering the development of such enterprises. Therefore, how to achieve comprehensive treatment of the aforementioned acidic gases and improve the company's economic efficiency has become a pressing issue. Summary of the Invention

[0003] This invention provides a device and method for the comprehensive utilization of acid gas from an ammonia synthesis plant, which addresses the technical problems mentioned in the background section.

[0004] The technical solution of this invention is as follows:

[0005] A comprehensive utilization device for acid gas from a synthetic ammonia plant includes an acid gas unit for a gasification system, an acid gas unit for a low-temperature methanol washing system, and an acid gas unit for a shift stripping tower. The acid gas unit for the gasification system is connected to the heat tracing gas inlet of the Claus combustion furnace and the heat tracing gas inlet of the waste gas combustion furnace in the sulfur preparation unit, respectively. The acid gas unit for the low-temperature methanol washing system is connected to the inlet of the Claus combustion furnace, and the acid gas unit for the shift stripping tower is connected to the inlet of the waste gas combustion furnace. The top tail gas outlet of the waste gas combustion furnace is connected to a tail gas treatment unit, which is coupled to an ammonium sulfite solution preparation unit, which is connected to an ammonium sulfate preparation unit.

[0006] The beneficial effects of this invention are as follows: This invention provides a system capable of comprehensively treating acidic gases in ammonia synthesis plants. Specifically, it can treat acidic gases from the gasification system acidic gas unit, the low-temperature methanol washing system acidic gas unit, and the shift stripping tower acidic gas unit. Research shows that the acidic gas in the gasification system acidic gas unit contains 31.6% CO (molar concentration), 19.3% H2 (molar concentration), and 46% carbon dioxide (molar concentration). The high CO and H2 content and high calorific value make it suitable as fuel gas for incinerators and Claus combustion furnaces, thus saving on natural gas and other fuels and reducing operating costs. Simultaneously, it ensures stable operation of the incinerator and Claus combustion furnace. The exhaust gas after combustion is treated by the exhaust gas treatment unit, achieving compliant emissions and environmental friendliness. Furthermore, the absorbent from the treated exhaust gas can be used to prepare ammonium sulfate, preparing for the production of new multi-element fertilizers. This achieves a cyclical operation of the entire system, solving the environmental emission problems of enterprises and bringing significant profits.

[0007] Preferably, the exhaust gas treatment unit includes an ammonia absorption tower connected to the exhaust gas outlet of the waste gas combustion furnace. The gas phase outlet at the top of the ammonia absorption tower is connected to the inlet of the water washing tower, and the gas phase outlet at the top of the water washing tower is connected to the atmosphere. The ammonium sulfite solution preparation unit includes a demineralized water storage tank, which is connected to the water washing tower via a demineralized water makeup pump and an eighth regulating valve. The bottom outlet of the water washing tower is connected to the circulation port at the top of the water washing tower via a bottom pump. A fifth three-way valve is provided between the bottom pump and the circulation port at the top of the water washing tower. The third end of the fifth three-way valve is connected to the inlet of the ammonia absorption tower via a seventh regulating valve. The bottom outlet of the ammonia absorption tower is connected to the circulation port at the top of the ammonia absorption tower via a bottom pump. A fourth three-way valve is provided between the bottom pump and the circulation port at the top of the ammonia absorption tower. The third end of the fourth three-way valve is connected to the ammonium sulfate concentration oxidation tower via a sixth regulating valve.

[0008] Preferably, the ammonia absorption tower is provided with an ammonia absorption tower replenishment port, which is connected to an ammonia tank with an ammonia pipeline via an ammonia pump.

[0009] Preferably, the ammonium sulfate preparation unit includes an ammonium sulfate concentration oxidation tower, which is connected to the waste nitrogen exhaust pipe and the hot air pipe in the air separation system, respectively. The bottom outlet of the ammonium sulfate concentration oxidation tower is connected to the crystallizer, the solid phase outlet of the crystallizer is connected to the compound fertilizer production unit, and the liquid phase outlet of the crystallizer is connected to the replenishment port of the ammonia water tank. The top gas phase outlet of the ammonium sulfate concentration oxidation tower is connected to the inlet of the water washing tower.

[0010] Preferably, the compound fertilizer production unit includes a compound fertilizer granulation tower, a urea solution storage tank, and a potassium chloride warehouse. The compound fertilizer granulation tower includes granulation nozzles located in the upper part of the tower. The inlets of the granulation nozzles are connected to the outlets of the potassium chloride dissolving tank and the ammonium sulfate dissolving tank via fourth and fifth regulating valves, respectively. The solid phase inlet of the potassium chloride dissolving tank is connected to the potassium chloride warehouse via a first elevator and a first weighing scale. The solid phase inlet of the ammonium sulfate dissolving tank is connected to the solid phase outlet of the crystallizer via a second elevator and a second weighing scale. The liquid phase inlets of the potassium chloride dissolving tank and the ammonium sulfate dissolving tank are connected to a first three-way valve via their respective first and second regulating valves, respectively. The third end of the first three-way valve is connected to the outlet of the urea solution storage tank via a urea solution pump. The potassium chloride dissolving tank is installed at a greater height than the ammonium sulfate dissolving tank, and the outlet of the potassium chloride dissolving tank is connected to the inlet of the ammonium sulfate dissolving tank via a third regulating valve.

[0011] Preferably, the acid gas unit of the gasification system includes a high-temperature flash gasifier, the top gas phase outlet of the high-temperature flash gasifier is connected to the bottom gas phase inlet of the high-temperature hot water tower, the upper part of the high-temperature hot water tower is connected to a low-temperature ash water pipeline, the top gas phase outlet of the high-temperature hot water tower is connected to a first acid gas cooler, the liquid phase outlet of the first acid gas cooler is connected to a gasification clarification tank, and the gas phase outlet of the first acid gas cooler is connected to the heat tracing gas inlet of the Claus combustion furnace and the heat tracing gas inlet of the waste gas combustion furnace respectively through a third tee.

[0012] Preferably, a second three-way valve and a tenth regulating valve are sequentially provided between the gas phase outlet of the first acid gas cooler and the third three-way valve. The third end of the second three-way valve is sequentially connected to the converter in the conversion system through the ninth regulating valve and the fuel gas compressor. An eleventh regulating valve is provided between the third three-way valve and the heat tracing gas inlet of the Claus combustion furnace.

[0013] Preferably, the acid gas unit of the low-temperature methanol washing system includes a methanol washing thermal regenerator, the gas phase outlet of which is connected to an acid gas separator via a second acid gas cooler, and the gas phase outlet of the acid gas separator is connected to the feed gas inlet of the Claus combustion furnace; the acid gas unit of the shift stripping tower includes a low-pressure flash tank, the gas phase outlet of which is connected to the gas phase inlet at the bottom of the shift stripping tower, the upper inlet of the shift stripping tower is connected to the waste liquid pipeline of the shift ammonia washing tower, and the gas phase outlet at the top of the shift stripping tower is connected to the inlet of the waste gas combustion furnace.

[0014] Preferably, the sulfur preparation unit includes a Claus combustion furnace, the outlet of which is connected to the inlet of a Claus reactor, the liquid phase outlet of the Claus reactor is connected to a sulfur warehouse through a sulfur granulation device, and the gas phase outlet of the Claus reactor is connected to the inlet of a waste gas combustion furnace.

[0015] The present invention also provides a method for comprehensive utilization of acid gas from an ammonia synthesis plant, the method comprising the following steps:

[0016] Step 1: The high-temperature black water in the gasification system enters the high-temperature flash tank for flash evaporation. The flashed gas phase enters the high-temperature hot water tower for mass and heat transfer with the low-temperature ash water from the low-temperature ash water pipeline. The unabsorbed non-condensable gas and some water vapor enter the first acid gas cooler for condensation. The condensed liquid phase enters the gasification clarification tank for reuse as gasification circulating water. The uncondensed acid gas enters the second three-way valve. One path is sent to the fuel gas compressor for pressurization through the ninth regulating valve. After the pressure rises to 6.3 MPa (G), it is sent to the shift furnace in the shift system as raw material for recycling. The other path enters the third three-way valve through the tenth regulating valve and enters the waste gas combustion furnace and Claus combustion furnace respectively as fuel gas.

[0017] Step 2: Low-pressure steam from the low-pressure flash tank of the gasification system enters the shift stripping tower as the stripping heat source of the shift stripping tower. It comes into countercurrent contact with the waste liquid from the shift ammonia washing tower waste liquid pipeline to strip out the acidic gas in the shift ammonia washing tower waste liquid. The stripped acidic gas enters the waste gas combustion furnace for incineration.

[0018] Step 3: The acidic gas from the methanol washing heat regenerator enters the second acidic gas cooler for condensation, condensing out the methanol and water in the acidic gas. The condensed acidic gas enters the acidic gas separator for separation, and the separated gas phase enters the Claus combustion furnace for combustion.

[0019] Step 4: The acidic gas from Step 1 and Step 3 above enters the Claus combustion furnace for combustion, converting part of the hydrogen sulfide into sulfur dioxide. Then, it enters the Claus reactor to react hydrogen sulfide and sulfur dioxide to produce liquid sulfur. The liquid sulfur enters the sulfur granulation unit for granulation, and the granulated sulfur enters the sulfur warehouse for packaging and sale.

[0020] The exhaust gas produced in the Claus reactor is incinerated in a waste gas combustion furnace; the exhaust gas produced in the Claus reactor contains some unreacted carbon monoxide and sulfur dioxide.

[0021] Step 5: The acidic gas from Step 1, the acidic gas from Step 2, and the tail gas produced in the Claus reactor in Step 4 are all fed into the waste gas combustion furnace for complete combustion. The tail gas from the waste gas combustion furnace then enters the ammonia absorption tower, where ammonia absorbs the sulfur dioxide in the tail gas. The tail gas passes through the ammonia absorption tower and is then washed in a water washing tower before being discharged in compliance with emission standards.

[0022] Step 6: The demineralized water in the demineralized water storage tank is pressurized by the demineralized water makeup pump and sent to the water washing tower to wash the tail gas after ammonia absorption. The amount of demineralized water entering the water washing tower is regulated by the eighth regulating valve. The solution at the bottom of the water washing tower is pressurized by the bottom pump and then returned to the water washing tower through the circulation port at the top of the water washing tower. This is to control the mass concentration of ammonia in the solution to within 5% while saving water, so as to ensure that the tail gas emission meets the requirements and can be easily entered into the subsequent ammonia absorption tower. When demineralized water needs to be added, the demineralized water makeup pump and the eighth regulating valve are turned on.

[0023] Step 7: When the solution in Step 6 reaches the predetermined threshold, open the seventh regulating valve to allow the solution in the fifth three-way valve to enter the ammonia absorption tower as absorbent. The solution at the bottom of the ammonia absorption tower is pressurized by the bottom pump and then returned to the ammonia absorption tower for recycling through the circulation port at the top of the ammonia absorption tower. This lays the foundation for entering the subsequent ammonium sulfate concentration and oxidation tower under the premise of absorbent. When absorbent needs to be added and the solution in Step 6 has not reached the predetermined threshold, turn on the ammonia pump to add ammonia water to the ammonia absorption tower through the ammonia water tank with ammonia water pipeline as absorbent.

[0024] Step 8: When the solution in Step 7 reaches the predetermined threshold, open the sixth regulating valve to allow the ammonium sulfite solution in the fourth three-way valve to enter the ammonium sulfate concentration oxidation tower for oxidation and crystallization. The hot air in the hot air pipe carries away some water vapor while oxidizing the ammonium sulfite, thus concentrating the ammonium sulfate. The waste nitrogen in the waste nitrogen exhaust pipe enters the ammonium sulfate concentration oxidation tower for secondary concentration of the ammonium sulfate. After secondary concentration, the ammonium sulfate enters the crystallizer for crystallization. The mother liquor after crystallization enters the ammonia water tank and is used as the absorbent in the ammonia water absorption tower.

[0025] Step 9: The solid phase crystallized in the crystallizer in Step 8 is fed into the ammonium sulfate dissolving tank inside the compound fertilizer granulation tower via the second weighing scale and the second elevator to prepare compound fertilizer;

[0026] Step 10: When it is necessary to prepare sulfur-nitrogen binary compound fertilizer, close the first regulating valve, the fourth regulating valve and the third regulating valve, and open the second regulating valve and the fifth regulating valve. The urea solution in the urea solution storage tank enters the ammonium sulfate dissolving tank through the urea solution pump, so that the 99% urea solution dissolves the ammonium sulfate. After dissolution, it enters the granulation nozzle for granulation.

[0027] Step 11: When preparing sulfur-nitrogen-potassium ternary compound fertilizer, open the first, second, third, and fifth regulating valves, and close the fourth regulating valve. Potassium chloride in the potassium chloride warehouse enters the potassium chloride dissolving tank through the first weighing scale and the first elevator. Urea solution in the urea solution storage tank enters the potassium chloride dissolving tank and the ammonium sulfate dissolving tank respectively through the urea solution pump, so that the 99% urea solution dissolves the potassium chloride and ammonium sulfate respectively. After dissolution, the urea solution containing potassium chloride enters the ammonium sulfate dissolving tank by the height difference for mixing, and a compound fertilizer slurry is obtained. The compound fertilizer slurry enters the granulation nozzle for granulation.

[0028] Step 12: When it is necessary to prepare nitrogen-potassium binary compound fertilizer, the solid phase crystallized by the crystallizer in step 8 is dried and then sold externally; close the second, third and fifth regulating valves, open the first and fourth regulating valves, and the urea solution in the urea solution storage tank enters the potassium chloride dissolving tank through the urea solution pump, so that the 99% urea solution dissolves the potassium chloride, and after dissolution, it enters the granulation nozzle for granulation.

[0029] According to the above scheme, a comprehensive utilization device and method for acid gas from a synthetic ammonia unit is provided. This invention offers a system capable of comprehensively treating acid gas from a synthetic ammonia unit. Specifically, it can treat acid gas from the gasification system acid gas unit, the low-temperature methanol washing system acid gas unit, and the shift stripping tower acid gas unit. Different components of different acid gases are treated separately. For the acid gas from the gasification system, which has a high CO and H2 content, it can be fed into the shift reactor in the shift system as raw material for the shift reaction, thus saving energy. Furthermore, its high calorific value allows it to be used as fuel gas for incinerators and Claus combustion furnaces, saving on natural gas and other fuels and reducing operating costs, while simultaneously ensuring stable operation of the incinerators and Claus combustion furnaces. For the acid gas from the low-temperature methanol washing system, it is used... The Claus reactor produces sulfur, but the tail gas still contains trace amounts of sulfur dioxide. Direct venting does not meet environmental requirements. Therefore, an incinerator is used to incinerate the sulfur dioxide along with acidic gas from a shift stripping process before sending it to the tail gas treatment unit. The sulfur dioxide is absorbed to form ammonium sulfite, which is then oxidized to ammonium sulfate. The ammonium sulfate crystallizes and is used as a raw material for compound fertilizer production, forming a closed-loop treatment of the acidic gas. This achieves both profit and environmental benefits for the enterprise. In summary, the device and process provide good environmental and economic benefits. Furthermore, the tail gas treatment unit described in this invention is coupled with the ammonium sulfite solution preparation unit, enabling the treatment of the tail gas and achieving compliant emissions. Simultaneously, the step-by-step absorption process prepares ammonium sulfite solution, laying the foundation for subsequent ammonium sulfate preparation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention.

[0031] Numbered in the diagram: 1. High-temperature flash tank for gasification; 2. Low-temperature ash water pipeline for gasification; 3. High-temperature hot water tower for gasification; 4. Low-pressure flash tank; 5. First acid gas cooler; 6. Gasification clarifier; 7. Shift stripping tower; 8. Waste liquid pipeline for shift washing ammonia tower; 9. Methanol washing heat regenerator; 10. Second acid gas cooler; 11. Second tee; 12. Ninth regulating valve; 13. Fuel gas compressor; 14. Shift furnace; 15. Tenth regulating valve; 16. Third tee; 17. Eleventh regulating valve; 18. Claus combustion furnace; 19. Claus reactor; 20. Sulfur warehouse; 21. Waste gas combustion furnace; 22. Eighth regulating valve; 23. Demineralized water makeup pump; 24. Ammonia water tank; 25. Water washing tower; 26. Fifth tee; 27. Bottom pump of water washing tower; 28. Seventh regulating valve; 29. ​​Ammonia water suction... 30. Demineralized water storage tank; 31. Sixth regulating valve; 32. Fourth tee; 33. Ammonia absorption tower bottom pump; 34. Waste nitrogen exhaust pipeline; 35. Ammonia pump; 36. Ammonium sulfate concentration oxidation tower; 37. Crystallizer; 38. Second weighing scale; 39. Second elevator; 40. Compound fertilizer granulation tower; 41. Granulation nozzle; 42. Fourth regulating valve; 43. Potassium chloride dissolving tank; 44. Third regulating valve; 45. Ammonium sulfate dissolving tank; 46. Fifth regulating valve; 47. First regulating valve; 48. Second regulating valve; 49. First tee; 50. Urea solution pump; 51. Urea solution storage tank; 52. Potassium chloride warehouse; 53. First weighing scale; 54. First elevator; 55. Hot air pipeline; 56. Sulfur granulation device; 57. Ammonia pipeline; 58. Acid gas separator. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0033] like Figure 1As shown, this invention relates to a comprehensive utilization device and method for acid gas from a synthetic ammonia unit. The device includes an acid gas unit for a gasification system, an acid gas unit for a low-temperature methanol washing system, and an acid gas unit for a shift stripping tower. The acid gas unit for the gasification system is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 in the sulfur preparation unit, respectively. The acid gas unit for the low-temperature methanol washing system is connected to the inlet of the Claus combustion furnace 18, and the acid gas unit for the shift stripping tower is connected to the inlet of the waste gas combustion furnace 21. The top tail gas outlet of the waste gas combustion furnace 21 is connected to a tail gas treatment unit, which is coupled to an ammonium sulfite solution preparation unit, which is connected to an ammonium sulfate preparation unit. This invention provides a device for the comprehensive centralized treatment of multiple streams of acidic gases in a synthetic ammonia plant. Specifically, it is used for acidic gases produced in the gasification system acidic gas unit, the low-temperature methanol washing system acidic gas unit, and the shift stripping tower acidic gas unit. By treating these acidic gases, the defects caused by production gases entering the flare can be avoided, and emission standards can be met, resulting in environmental friendliness and the production of ammonium sulfate as a byproduct, thus improving enterprise profits. This invention conducts in-depth research on the aforementioned acidic gases, treating them separately according to their different compositions, specifically targeting the acidic gases from the gasification system. Its composition has a high CO and H2 content and a high calorific value, making it suitable as fuel gas for incinerators and Claus combustion furnaces. This saves on operating costs by reducing the use of natural gas and other fuels, while ensuring stable operation of the incinerators and Claus combustion furnaces. For the acidic gas from the low-temperature methanol washing system, it is used to produce sulfur using a Claus reactor. Furthermore, in this invention, the tail gas treatment unit is coupled with the ammonium sulfite solution preparation unit to treat the tail gas and achieve compliant emissions while simultaneously preparing the ammonium sulfite solution, laying the foundation for subsequent ammonium sulfate production.

[0034] Furthermore, the exhaust gas treatment unit includes an ammonia absorption tower 29 connected to the exhaust gas outlet of the waste gas combustion furnace 21. The gas phase outlet at the top of the ammonia absorption tower 29 is connected to the inlet of the water washing tower 25, and the gas phase outlet at the top of the water washing tower 25 is connected to the atmosphere. The ammonium sulfite solution preparation unit includes a demineralized water storage tank 30, which is connected to the water washing tower 25 via a demineralized water makeup pump 23 and an eighth regulating valve 22. The bottom outlet of the water washing tower 25 is connected to the circulation port at the top of the water washing tower 25 via a bottom pump 27. A fifth three-way valve 26 is provided between the bottom pump 27 of the water washing tower and the circulation port at the top of the water washing tower 25. The third end of the fifth three-way valve 26 is connected to the inlet of the ammonia absorption tower 29 through the seventh regulating valve 28. The bottom outlet of the ammonia absorption tower 29 is connected to the circulation port at the top of the ammonia absorption tower 29 through the bottom pump 33 of the ammonia absorption tower 29. A fourth three-way valve 32 is provided between the bottom pump 33 of the ammonia absorption tower 29 and the circulation port at the top of the ammonia absorption tower 29. The third end of the fourth three-way valve 32 is connected to the ammonium sulfate concentration oxidation tower 36 through the sixth regulating valve 31. The coupling in this invention refers to using the ammonia absorption tower 29 and the water washing tower 25 in the tail gas treatment unit to treat the tail gas to achieve the standard emission of the tail gas. At the same time, during the process of removing ammonia and sulfur by the water washing tower 25 and the ammonia absorption tower 29, the demineralized water is gradually absorbed and concentrated to generate ammonium sulfite solution, laying the foundation for the subsequent preparation of ammonium sulfate. Furthermore, the demineralized water storage tank 30 is used to store demineralized water. When the absorbent circulating in the water washing tower 25 is insufficient, it can be replenished through the demineralized water storage tank 30 to meet the operating needs of the water washing tower 25 and ensure that the exhaust gas can meet emission standards and is environmentally friendly.

[0035] Furthermore, the ammonia absorption tower 29 is provided with an ammonia absorption tower replenishment port, which is connected to an ammonia tank 24 with an ammonia pipeline 57 via an ammonia pump 35. This invention specifically provides an ammonia absorption tower replenishment port for use when the washing tower 25 cannot supply absorbent to the ammonia absorption tower 29, and the amount of absorbent in the ammonia absorption tower 29 is too small to operate normally. Specifically, this can be achieved by turning on the ammonia pump 35 to allow the ammonia in the ammonia tank 24 to enter the ammonia absorption tower 29. The ammonia in the ammonia tank 24 can originate from the ammonia pipeline 57.

[0036] Furthermore, the ammonium sulfate preparation unit includes an ammonium sulfate concentration oxidation tower 36, which is connected to the waste nitrogen exhaust pipe 34 and the hot air pipe 55 in the air separation system. The bottom outlet of the ammonium sulfate concentration oxidation tower 36 is connected to the crystallizer 37, the solid phase outlet of the crystallizer 37 is connected to the compound fertilizer production unit, and the liquid phase outlet of the crystallizer 37 is connected to the liquid replenishment port of the ammonia water tank 24. The top gas phase outlet of the ammonium sulfate concentration oxidation tower 36 is connected to the inlet of the water washing tower 25. The aforementioned ammonium sulfite solution enters the ammonium sulfate concentration oxidation tower 36 for oxidation and crystallization. The hot air in the hot air pipe 55 carries away some water vapor while oxidizing the ammonium sulfite, thus concentrating the ammonium sulfate. The waste nitrogen gas in the waste nitrogen exhaust pipe 34 enters the ammonium sulfate concentration oxidation tower 36 to further concentrate the ammonium sulfate. This allows the ammonium sulfate to enter the crystallizer 37 for crystallization after secondary concentration. At the same time, the mother liquor after crystallization in the crystallizer 37 can be sent to the ammonia water tank 24 through the liquid phase outlet for recycling. The tail gas produced in the ammonium sulfate concentration oxidation tower 36 can enter the water washing tower 25 for washing before being discharged, thus achieving environmentally friendly characteristics.

[0037] Further, the compound fertilizer production unit includes a compound fertilizer granulation tower 40, a urea solution storage tank 51, and a potassium chloride warehouse 52; the compound fertilizer granulation tower 40 includes granulation nozzles 41 located in the upper part of the compound fertilizer granulation tower 40, the inlet of the granulation nozzles 41 being connected to the outlets of the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 respectively through a fourth regulating valve 42 and a fifth regulating valve 46, the solid phase inlet of the potassium chloride dissolving tank 43 being connected to the potassium chloride warehouse 52 through a first elevator 54 and a first weighing scale 53, and the solid phase inlet of the ammonium sulfate dissolving tank 45 .... The second elevator 39 and the second weighing scale 38 are connected to the solid phase outlet of the crystallizer 37; the liquid phase inlets of the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 are respectively connected to the first three-way valve 49 through their respective first regulating valve 47 and second regulating valve 48, and the third end of the first three-way valve 49 is connected to the outlet of the urea solution storage tank 51 through the urea solution pump 50; the setting height of the potassium chloride dissolving tank 43 is greater than the setting height of the ammonium sulfate dissolving tank 45, and the outlet of the potassium chloride dissolving tank 43 is connected to the inlet of the ammonium sulfate dissolving tank 45 through the third regulating valve 44. After ammonium sulfate is prepared in this invention, it can be sent to a compound fertilizer production unit for the preparation of compound fertilizer. The above-mentioned device is equipped to prepare sulfur-nitrogen binary compound fertilizer, nitrogen-potassium binary compound fertilizer, and sulfur-nitrogen-potassium ternary compound fertilizer. When preparing sulfur-nitrogen binary compound fertilizer and sulfur-nitrogen-potassium ternary compound fertilizer, the ammonium sulfate produced can be applied to reduce the cost of compound fertilizer production for enterprises and achieve the characteristics of circular economy. When applied to produce nitrogen-potassium binary compound fertilizer, the ammonium sulfate can be sold externally to increase the enterprise's profits.

[0038] Furthermore, the acid gas unit of the gasification system includes a high-temperature flash gasification tank 1. The top gas phase outlet of the high-temperature flash gasification tank 1 is connected to the bottom gas phase inlet of the high-temperature hot water tower 3. The upper part of the high-temperature hot water tower 3 is connected to a low-temperature ash water pipeline 2. The top gas phase outlet of the high-temperature hot water tower 3 is connected to a first acid gas cooler 5. The liquid phase outlet of the first acid gas cooler 5 is connected to a gasification clarification tank 6. The gas phase outlet of the first acid gas cooler 5 is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 respectively through a third tee 16. The acid gas in the gasification system's acid gas unit contains sulfur. If it is directly fed into the flare for combustion, it will cause pollution problems. However, it has the characteristics of high calorific value. In the process of treating the tail gas after combustion in the waste gas combustion furnace 21, it can be absorbed during the desulfurization process, and after absorption, it forms ammonium sulfite. At the same time, this acid gas has the characteristics of high calorific value, which can replace conventional heat-traced combustible gas to achieve the characteristic of reducing costs.

[0039] Furthermore, a second three-way valve 11 and a tenth regulating valve 15 are sequentially provided between the gas phase outlet of the first acid gas cooler 5 and the third three-way valve 16. The third end of the second three-way valve 11 is sequentially connected to the converter 14 in the conversion system through the ninth regulating valve 12 and the fuel gas compressor 13. An eleventh regulating valve 17 is provided between the third three-way valve 16 and the heat tracing gas inlet of the Claus combustion furnace 18. The acid gas component of the acid gas unit in the gasification system has a high CO and H2 content, which can be fed into the converter in the conversion system by the fuel gas compressor 13 as raw material for conversion reaction, thereby achieving the characteristics of saving coal consumption and reducing production costs.

[0040] Furthermore, the acid gas unit of the low-temperature methanol washing system includes a methanol washing thermal regenerator 9. The gas phase outlet of the methanol washing thermal regenerator 9 is connected to the acid gas separator 58 through a second acid gas cooler 10. The gas phase outlet of the acid gas separator 58 is connected to the raw material gas inlet of the Claus combustion furnace 18. The acid gas unit of the shift stripping tower includes a low-pressure flash tank 4. The gas phase outlet of the low-pressure flash tank 4 is connected to the gas phase inlet at the bottom of the shift stripping tower 7. The upper inlet of the shift stripping tower 7 is connected to the waste liquid pipeline 8 of the shift ammonia washing tower. The gas phase outlet at the top of the shift stripping tower 7 is connected to the inlet of the waste gas combustion furnace 21. The acid gas from the low-temperature methanol washing system is used to produce sulfur in a Claus reactor. The tail gas after sulfur production still contains trace amounts of sulfur dioxide. Direct venting does not meet environmental protection requirements. Therefore, it is incinerated in an incinerator and then sent to the ammonia absorption unit to absorb the sulfur dioxide, forming ammonium sulfite. The ammonium sulfite is then oxidized to ammonium sulfate.

[0041] Furthermore, the sulfur preparation unit includes a Claus combustion furnace 18, the outlet of which is connected to the inlet of a Claus reactor 19. The liquid phase outlet of the Claus reactor 19 is connected to a sulfur warehouse 20 via a sulfur granulation device 56, and the gas phase outlet of the Claus reactor 19 is connected to the inlet of a waste gas combustion furnace 21. The acidic gas from the low-temperature methanol washing system is used to produce sulfur in the Claus reactor. The tail gas after sulfur production still contains trace amounts of sulfur dioxide, and direct venting does not meet environmental protection requirements. Therefore, it is incinerated in an incinerator along with shift stripping acidic gas before being sent to the tail gas treatment unit. The sulfur dioxide is absorbed, forming ammonium sulfite.

[0042] The present invention also provides a method for comprehensive utilization of acid gas from an ammonia synthesis plant, the method comprising the following steps:

[0043] Step 1: The high-temperature black water in the gasification system enters the high-temperature flash evaporator 1 for flash evaporation. The flashed gas phase enters the high-temperature hot water tower 3 and undergoes mass and heat transfer with the low-temperature ash water from the low-temperature ash water pipeline 2. The unabsorbed non-condensable gas and some water vapor enter the first acid gas cooler 5 for condensation. The condensed liquid phase enters the gasification clarification tank 6 as gasification circulating water for reuse. The uncondensed acid gas enters the second three-way valve 11. One path is sent to the fuel gas compressor 13 through the ninth regulating valve 12 for pressurization. After the pressure rises to 6.3 MPa (G), it is sent to the converter 14 in the conversion system as raw material for recycling. The other path enters the third three-way valve 16 through the tenth regulating valve 15 and enters the waste gas combustion furnace 21 and Claus combustion furnace 18 respectively as fuel gas.

[0044] Step 2: Low-pressure steam from the low-pressure flash tank 4 of the gasification system enters the shift stripping tower 7 as the stripping heat source of the shift stripping tower 7, and comes into countercurrent contact with the waste liquid from the shift ammonia washing tower from the waste liquid pipeline 8, stripping out the acidic gas in the waste liquid of the shift ammonia washing tower. The stripped acidic gas enters the waste gas combustion furnace 21 for incineration.

[0045] Step 3: The acidic gas from the methanol washing heat regenerator 9 enters the second acidic gas cooler 10 for condensation, condensing out the methanol and water in the acidic gas. The condensed acidic gas enters the acidic gas separator 58 for separation, and the separated gas phase enters the Claus combustion furnace 18 for combustion.

[0046] Step 4: The acidic gas from Steps 1 and 3 above enters the Claus combustion furnace 18 for combustion, converting some of the hydrogen sulfide into sulfur dioxide. Then, it enters the Claus reactor 19 to react with the hydrogen sulfide to produce liquid sulfur. The liquid sulfur enters the sulfur granulation device 56 for granulation, and the granulated sulfur enters the sulfur warehouse 20 for packaging and sale. The tail gas produced in the Claus reactor 19 enters the waste gas combustion furnace 21 for incineration. The tail gas produced in the Claus reactor 19 contains some unreacted carbon monoxide and sulfur dioxide.

[0047] Step 5: The acidic gas from Step 1, the acidic gas from Step 2, and the tail gas produced in the Claus reactor 19 in Step 4 are all fed into the waste gas combustion furnace 21 for complete combustion. The tail gas from the waste gas combustion furnace 21 then enters the ammonia absorption tower 29, where ammonia absorbs the sulfur dioxide in the tail gas. The tail gas passes through the ammonia absorption tower 29 and is then washed in the water washing tower 25 before being discharged in compliance with emission standards.

[0048] Step 6: The demineralized water in the demineralized water storage tank 30 is pressurized by the demineralized water makeup pump 23 and sent to the water washing tower 25 to wash the tail gas after ammonia absorption. The amount of demineralized water entering the water washing tower 25 is regulated by the eighth regulating valve 22. The solution at the bottom of the water washing tower 25 is pressurized by the bottom pump 27 and then returned to the water washing tower 25 through the circulation port at the top of the water washing tower 25. This is to control the mass concentration of ammonia in the solution to within 5% while saving water, so as to facilitate the entry of the tail gas into the subsequent ammonia absorption tower 29 while ensuring that the tail gas emission is qualified. When demineralized water needs to be added, the demineralized water makeup pump 23 and the eighth regulating valve 22 are turned on.

[0049] Step 7: When the solution in Step 6 reaches the predetermined threshold, open the seventh regulating valve 28 to allow the solution in the fifth three-way valve 26 to enter the ammonia absorption tower 29 as the absorbent. The solution at the bottom of the ammonia absorption tower 29 is pressurized by the bottom pump 33 and then returned to the ammonia absorption tower 29 through the circulation port at the top of the ammonia absorption tower 29 for recycling. This lays the foundation for entering the subsequent ammonium sulfate concentration oxidation tower 36 under the premise of absorbent. When absorbent needs to be added and the solution in Step 6 has not reached the predetermined threshold, turn on the ammonia pump 35 to add ammonia water to the ammonia absorption tower 29 through the ammonia tank 24 with ammonia water pipe 57 as the absorbent.

[0050] Step 8: When the solution in Step 7 reaches the predetermined threshold, open the sixth regulating valve 31 to allow the ammonium sulfite solution in the fourth three-way valve 32 to enter the ammonium sulfate concentration oxidation tower 36 for oxidation and crystallization. The hot air in the hot air pipe 55 carries away some water vapor while oxidizing the ammonium sulfite, thus concentrating the ammonium sulfate. The waste nitrogen gas in the waste nitrogen exhaust pipe 34 enters the ammonium sulfate concentration oxidation tower 36 to further concentrate the ammonium sulfate. After secondary concentration, the ammonium sulfate enters the crystallizer 37 for crystallization. The mother liquor after crystallization enters the ammonia water tank 24 and is used as the absorbent in the ammonia water absorption tower 29.

[0051] Step 9: The solid phase crystallized by the crystallizer 37 in step 8 enters the ammonium sulfate dissolving tank 45 inside the compound fertilizer granulation tower 40 through the second weighing scale 38 and the second elevator 39 for the preparation of compound fertilizer.

[0052] Step 10: When it is necessary to prepare sulfur-nitrogen binary compound fertilizer, close the first regulating valve 47, the fourth regulating valve 42 and the third regulating valve 44, and open the second regulating valve 48 and the fifth regulating valve 46. The urea solution in the urea solution storage tank (51) enters the ammonium sulfate dissolving tank 45 through the urea solution pump 50, so that the urea solution with a concentration of 99% dissolves the ammonium sulfate. After dissolution, it enters the granulation nozzle 41 for granulation.

[0053] Step 11: When preparing sulfur-nitrogen-potassium ternary compound fertilizer, open the first regulating valve 47, the second regulating valve 48, the third regulating valve 44, and the fifth regulating valve 46, and close the fourth regulating valve 42. Potassium chloride in the potassium chloride warehouse 52 enters the potassium chloride dissolving tank 43 through the first weighing scale 53 and the first elevator 54. Urea solution in the urea solution storage tank 51 enters the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 through the urea solution pump 50, respectively, so that the 99% urea solution dissolves the potassium chloride and ammonium sulfate. After dissolution, the urea solution containing potassium chloride enters the ammonium sulfate dissolving tank 45 by the height difference for mixing, and a compound fertilizer slurry is obtained. The compound fertilizer slurry enters the granulation nozzle 41 for granulation.

[0054] Step 12: When it is necessary to prepare nitrogen-potassium binary compound fertilizer, the solid phase crystallized by crystallizer 37 in step 8 is dried and sold externally; close the second regulating valve 48, the third regulating valve 44 and the fifth regulating valve 46, open the first regulating valve 47 and the fourth regulating valve 42, and the urea solution in the urea solution storage tank 51 enters the potassium chloride dissolving tank 43 through the urea solution pump 50, so that the 99% urea solution dissolves the potassium chloride, and after dissolution, it enters the granulation nozzle 41 for granulation.

[0055] This invention integrates different acid gas treatment devices from existing ammonia synthesis plants into this system. This not only facilitates operation and control but also ensures that different acid gases ultimately meet emission standards. Furthermore, it utilizes the different compositions of various acid gases for targeted design. The acid gas from the gasification system has a high CO and H2 content and contains sulfur. Based on these characteristics, it can be used as a feedstock in a shift converter, saving coal consumption; it can also be used as fuel gas in incinerators and Claus combustion furnaces; and it can absorb sulfur during the tail gas treatment process, forming ammonium sulfite. Further, in the process of preparing sulfur from acid gas using a low-temperature methanol washing system, the tail gas still contains trace amounts of sulfur dioxide. Direct venting does not meet environmental requirements. Therefore, it is incinerated in an incinerator and combined with shift-stripped acid gas before being sent to an ammonia absorption unit to absorb the sulfur dioxide, forming ammonium sulfite, which is then oxidized to ammonium sulfate. All of the above processes utilize the different characteristics of the different components of the acid gases. In this invention, all acidic gases can be treated by recycling or combustion. All exhaust gases are treated to meet emission standards, and waste liquids are also recycled. In particular, by coupling the exhaust gas treatment unit with the ammonium sulfite solution preparation unit, a foundation is laid for the preparation of ammonium sulfate, which can also be used to prepare compound fertilizer, thus realizing a circular economy model.

[0056] To explain the present invention in more detail, the invention will now be further described with reference to embodiments. Specific embodiments are as follows:

[0057] Example 1

[0058] A comprehensive utilization device for acid gas from a synthetic ammonia plant includes an acid gas unit for a gasification system, an acid gas unit for a low-temperature methanol washing system, and an acid gas unit for a shift stripping tower. The acid gas unit for the gasification system is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 in the sulfur preparation unit, respectively. The acid gas unit for the low-temperature methanol washing system is connected to the inlet of the Claus combustion furnace 18, and the acid gas unit for the shift stripping tower is connected to the inlet of the waste gas combustion furnace 21. The top tail gas outlet of the waste gas combustion furnace 21 is connected to a tail gas treatment unit, which is coupled to an ammonium sulfite solution preparation unit, which is connected to an ammonium sulfate preparation unit. The exhaust gas treatment unit includes an ammonia absorption tower 29 connected to the exhaust gas outlet of the waste gas combustion furnace 21. The gas phase outlet at the top of the ammonia absorption tower 29 is connected to the inlet of the water scrubbing tower 25, and the gas phase outlet at the top of the water scrubbing tower 25 is open to the atmosphere. The ammonium sulfite solution preparation unit includes a demineralized water storage tank 30, which is connected to the water scrubbing tower 25 via a demineralized water makeup pump 23 and an eighth regulating valve 22. The bottom outlet of the water scrubbing tower 25 is connected to the circulation port at the top of the water scrubbing tower 25 via a bottom pump 27. A fifth three-way valve 26 is provided between the bottom pump 27 of the washing tower and the circulation port at the top of the water washing tower 25. The third end of the fifth three-way valve 26 is connected to the inlet of the ammonia absorption tower 29 through the seventh regulating valve 28. The bottom outlet of the ammonia absorption tower 29 is connected to the circulation port at the top of the ammonia absorption tower 29 through the bottom pump 33 of the ammonia absorption tower. A fourth three-way valve 32 is provided between the bottom pump 33 of the ammonia absorption tower and the circulation port at the top of the ammonia absorption tower 29. The third end of the fourth three-way valve 32 is connected to the ammonium sulfate concentration oxidation tower 36 through the sixth regulating valve 31. The ammonia absorption tower 29 is provided with an ammonia absorption tower replenishment port, which is connected to the ammonia tank 24 with an ammonia pipeline 57 through the ammonia pump 35. The ammonium sulfate preparation unit includes an ammonium sulfate concentration and oxidation tower 36, which is connected to the waste nitrogen exhaust pipe 34 and the hot air pipe 55 in the air separation system. The bottom outlet of the ammonium sulfate concentration and oxidation tower 36 is connected to the crystallizer 37, the solid phase outlet of the crystallizer 37 is connected to the compound fertilizer production unit, and the liquid phase outlet of the crystallizer 37 is connected to the replenishment port of the ammonia water tank 24. The top gas phase outlet of the ammonium sulfate concentration and oxidation tower 36 is connected to the inlet of the water washing tower 25.The compound fertilizer production unit includes a compound fertilizer granulation tower 40, a urea solution storage tank 51, and a potassium chloride warehouse 52. The compound fertilizer granulation tower 40 includes granulation nozzles 41 located in the upper part of the tower. The inlet of the granulation nozzles 41 is connected to the outlets of a potassium chloride dissolving tank 43 and an ammonium sulfate dissolving tank 45 via a fourth regulating valve 42 and a fifth regulating valve 46, respectively. The solid phase inlet of the potassium chloride dissolving tank 43 is connected to the potassium chloride warehouse 52 via a first elevator 54 and a first weighing scale 53. The solid phase inlet of the ammonium sulfate dissolving tank 45 is connected to the potassium chloride warehouse 52 via a second elevator 54. The elevator 39 and the second metering scale 38 are connected to the solid phase outlet of the crystallizer 37; the liquid phase inlets of the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 are respectively connected to the first three-way valve 49 through their respective first regulating valve 47 and second regulating valve 48, and the third end of the first three-way valve 49 is connected to the outlet of the urea solution storage tank 51 through the urea solution pump 50; the setting height of the potassium chloride dissolving tank 43 is greater than the setting height of the ammonium sulfate dissolving tank 45, and the outlet of the potassium chloride dissolving tank 43 is connected to the inlet of the ammonium sulfate dissolving tank 45 through the third regulating valve 44. The acid gas unit of the gasification system includes a high-temperature flash gasifier 1. The top gas phase outlet of the high-temperature flash gasifier 1 is connected to the bottom gas phase inlet of the high-temperature hot water tower 3. The upper part of the high-temperature hot water tower 3 is connected to a low-temperature ash water pipeline 2. The top gas phase outlet of the high-temperature hot water tower 3 is connected to a first acid gas cooler 5. The liquid phase outlet of the first acid gas cooler 5 is connected to a gasification clarification tank 6. The gas phase outlet of the first acid gas cooler 5 is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 via a third three-way valve 16. A second three-way valve 11 and a tenth regulating valve 15 are sequentially provided between the gas phase outlet of the first acid gas cooler 5 and the third three-way valve 16. The third end of the second three-way valve 11 is sequentially connected to the converter 14 in the conversion system via a ninth regulating valve 12 and a fuel gas compressor 13. An eleventh regulating valve 17 is provided between the third three-way valve 16 and the heat tracing gas inlet of the Claus combustion furnace 18. The acid gas unit of the low-temperature methanol washing system includes a methanol washing thermal regenerator 9. The gas phase outlet of the methanol washing thermal regenerator 9 is connected to an acid gas separator 58 via a second acid gas cooler 10. The gas phase outlet of the acid gas separator 58 is connected to the feed gas inlet of the Claus combustion furnace 18. The acid gas unit of the shift stripping tower includes a low-pressure flash tank 4. The gas phase outlet of the low-pressure flash tank 4 is connected to the gas phase inlet at the bottom of the shift stripping tower 7. The upper inlet of the shift stripping tower 7 is connected to the waste liquid pipeline 8 of the shift ammonia washing tower. The gas phase outlet at the top of the shift stripping tower 7 is connected to the inlet of the waste gas combustion furnace 21. The sulfur preparation unit includes a Claus combustion furnace 18. The outlet of the Claus combustion furnace 18 is connected to the inlet of the Claus reactor 19. The liquid phase outlet of the Claus reactor 19 is connected to the sulfur warehouse 20 via a sulfur granulation device 56. The gas phase outlet of the Claus reactor 19 is connected to the inlet of the waste gas combustion furnace 21.

[0059] The present invention also provides a method for comprehensive utilization of acid gas from an ammonia synthesis plant, the method comprising the following steps:

[0060] Step 1: The high-temperature black water in the gasification system enters the high-temperature flash evaporator 1 for flash evaporation. The flashed gas phase enters the high-temperature hot water tower 3 and undergoes mass and heat transfer with the low-temperature ash water from the low-temperature ash water pipeline 2. The unabsorbed non-condensable gas and some water vapor enter the first acid gas cooler 5 for condensation. The condensed liquid phase enters the gasification clarification tank 6 as gasification circulating water for reuse. The uncondensed acid gas enters the second three-way valve 11. One path is sent to the fuel gas compressor 13 through the ninth regulating valve 12 for pressurization. After the pressure rises to 6.3 MPa (G), it is sent to the converter 14 in the conversion system as raw material for recycling. The other path enters the third three-way valve 16 through the tenth regulating valve 15 and enters the waste gas combustion furnace 21 and Claus combustion furnace 18 respectively as fuel gas.

[0061] Step 2: Low-pressure steam from the low-pressure flash tank 4 of the gasification system enters the shift stripping tower 7 as the stripping heat source of the shift stripping tower 7, and comes into countercurrent contact with the waste liquid from the shift ammonia washing tower from the waste liquid pipeline 8, stripping out the acidic gas in the waste liquid of the shift ammonia washing tower. The stripped acidic gas enters the waste gas combustion furnace 21 for incineration.

[0062] Step 3: The acidic gas from the methanol washing heat regenerator 9 enters the second acidic gas cooler 10 for condensation, condensing out the methanol and water in the acidic gas. The condensed acidic gas enters the acidic gas separator 58 for separation, and the separated gas phase enters the Claus combustion furnace 18 for combustion.

[0063] Step 4: The acidic gas from Steps 1 and 3 above enters the Claus combustion furnace 18 for combustion, converting some of the hydrogen sulfide into sulfur dioxide. Then, it enters the Claus reactor 19 to react with the hydrogen sulfide to produce liquid sulfur. The liquid sulfur enters the sulfur granulation device 56 for granulation, and the granulated sulfur enters the sulfur warehouse 20 for packaging and sale. The tail gas produced in the Claus reactor 19 enters the waste gas combustion furnace 21 for incineration. The tail gas produced in the Claus reactor 19 contains some unreacted carbon monoxide and sulfur dioxide.

[0064] Step 5: The acidic gas from Step 1, the acidic gas from Step 2, and the tail gas produced in the Claus reactor 19 in Step 4 are all fed into the waste gas combustion furnace 21 for complete combustion. The tail gas from the waste gas combustion furnace 21 then enters the ammonia absorption tower 29, where ammonia absorbs the sulfur dioxide in the tail gas. The tail gas passes through the ammonia absorption tower 29 and is then washed in the water washing tower 25 before being discharged in compliance with emission standards.

[0065] Step 6: The demineralized water in the demineralized water storage tank 30 is pressurized by the demineralized water makeup pump 23 and sent to the water washing tower 25 to wash the tail gas after ammonia absorption. The amount of demineralized water entering the water washing tower 25 is regulated by the eighth regulating valve 22. The solution at the bottom of the water washing tower 25 is pressurized by the bottom pump 27 and then returned to the water washing tower 25 through the circulation port at the top of the water washing tower 25. This is to control the mass concentration of ammonia in the solution to within 5% while saving water, so as to facilitate the entry of the tail gas into the subsequent ammonia absorption tower 29 while ensuring that the tail gas emission is qualified. When demineralized water needs to be added, the demineralized water makeup pump 23 and the eighth regulating valve 22 are turned on.

[0066] Step 7: When the solution in Step 6 reaches the predetermined threshold, open the seventh regulating valve 28 to allow the solution in the fifth three-way valve 26 to enter the ammonia absorption tower 29 as the absorbent. The solution at the bottom of the ammonia absorption tower 29 is pressurized by the bottom pump 33 and then returned to the ammonia absorption tower 29 through the circulation port at the top of the ammonia absorption tower 29 for recycling. This lays the foundation for entering the subsequent ammonium sulfate concentration oxidation tower 36 under the premise of absorbent. When absorbent needs to be added and the solution in Step 6 has not reached the predetermined threshold, turn on the ammonia pump 35 to add ammonia water to the ammonia absorption tower 29 through the ammonia tank 24 with ammonia water pipe 57 as the absorbent.

[0067] Step 8: When the solution in Step 7 reaches the predetermined threshold, open the sixth regulating valve 31 to allow the ammonium sulfite solution in the fourth three-way valve 32 to enter the ammonium sulfate concentration oxidation tower 36 for oxidation and crystallization. The hot air in the hot air pipe 55 carries away some water vapor while oxidizing the ammonium sulfite, thus concentrating the ammonium sulfate. The waste nitrogen gas in the waste nitrogen exhaust pipe 34 enters the ammonium sulfate concentration oxidation tower 36 to further concentrate the ammonium sulfate. After secondary concentration, the ammonium sulfate enters the crystallizer 37 for crystallization. The mother liquor after crystallization enters the ammonia water tank 24 and is used as the absorbent in the ammonia water absorption tower 29.

[0068] Step 9: The solid phase crystallized by the crystallizer 37 in step 8 enters the ammonium sulfate dissolving tank 45 inside the compound fertilizer granulation tower 40 through the second weighing scale 38 and the second elevator 39 for the preparation of compound fertilizer.

[0069] Step 10: When it is necessary to prepare sulfur-nitrogen binary compound fertilizer, close the first regulating valve 47, the fourth regulating valve 42 and the third regulating valve 44, and open the second regulating valve 48 and the fifth regulating valve 46. The urea solution in the urea solution storage tank (51) enters the ammonium sulfate dissolving tank 45 through the urea solution pump 50, so that the urea solution with a concentration of 99% dissolves the ammonium sulfate. After dissolution, it enters the granulation nozzle 41 for granulation.

[0070] Example 2

[0071] A comprehensive utilization device for acid gas from a synthetic ammonia plant includes an acid gas unit for a gasification system, an acid gas unit for a low-temperature methanol washing system, and an acid gas unit for a shift stripping tower. The acid gas unit for the gasification system is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 in the sulfur preparation unit, respectively. The acid gas unit for the low-temperature methanol washing system is connected to the inlet of the Claus combustion furnace 18, and the acid gas unit for the shift stripping tower is connected to the inlet of the waste gas combustion furnace 21. The top tail gas outlet of the waste gas combustion furnace 21 is connected to a tail gas treatment unit, which is coupled to an ammonium sulfite solution preparation unit, which is connected to an ammonium sulfate preparation unit. The exhaust gas treatment unit includes an ammonia absorption tower 29 connected to the exhaust gas outlet of the waste gas combustion furnace 21. The gas phase outlet at the top of the ammonia absorption tower 29 is connected to the inlet of the water scrubbing tower 25, and the gas phase outlet at the top of the water scrubbing tower 25 is open to the atmosphere. The ammonium sulfite solution preparation unit includes a demineralized water storage tank 30, which is connected to the water scrubbing tower 25 via a demineralized water makeup pump 23 and an eighth regulating valve 22. The bottom outlet of the water scrubbing tower 25 is connected to the circulation port at the top of the water scrubbing tower 25 via a bottom pump 27. A fifth three-way valve 26 is provided between the bottom pump 27 of the washing tower and the circulation port at the top of the water washing tower 25. The third end of the fifth three-way valve 26 is connected to the inlet of the ammonia absorption tower 29 through the seventh regulating valve 28. The bottom outlet of the ammonia absorption tower 29 is connected to the circulation port at the top of the ammonia absorption tower 29 through the bottom pump 33 of the ammonia absorption tower. A fourth three-way valve 32 is provided between the bottom pump 33 of the ammonia absorption tower and the circulation port at the top of the ammonia absorption tower 29. The third end of the fourth three-way valve 32 is connected to the ammonium sulfate concentration oxidation tower 36 through the sixth regulating valve 31. The ammonia absorption tower 29 is provided with an ammonia absorption tower replenishment port, which is connected to the ammonia tank 24 with an ammonia pipeline 57 through the ammonia pump 35. The ammonium sulfate preparation unit includes an ammonium sulfate concentration and oxidation tower 36, which is connected to the waste nitrogen exhaust pipe 34 and the hot air pipe 55 in the air separation system. The bottom outlet of the ammonium sulfate concentration and oxidation tower 36 is connected to the crystallizer 37, the solid phase outlet of the crystallizer 37 is connected to the compound fertilizer production unit, and the liquid phase outlet of the crystallizer 37 is connected to the replenishment port of the ammonia water tank 24. The top gas phase outlet of the ammonium sulfate concentration and oxidation tower 36 is connected to the inlet of the water washing tower 25.The compound fertilizer production unit includes a compound fertilizer granulation tower 40, a urea solution storage tank 51, and a potassium chloride warehouse 52. The compound fertilizer granulation tower 40 includes granulation nozzles 41 located in the upper part of the tower. The inlet of the granulation nozzles 41 is connected to the outlets of a potassium chloride dissolving tank 43 and an ammonium sulfate dissolving tank 45 via a fourth regulating valve 42 and a fifth regulating valve 46, respectively. The solid phase inlet of the potassium chloride dissolving tank 43 is connected to the potassium chloride warehouse 52 via a first elevator 54 and a first weighing scale 53. The solid phase inlet of the ammonium sulfate dissolving tank 45 is connected to the potassium chloride warehouse 52 via a second elevator 54. The elevator 39 and the second metering scale 38 are connected to the solid phase outlet of the crystallizer 37; the liquid phase inlets of the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 are respectively connected to the first three-way valve 49 through their respective first regulating valve 47 and second regulating valve 48, and the third end of the first three-way valve 49 is connected to the outlet of the urea solution storage tank 51 through the urea solution pump 50; the setting height of the potassium chloride dissolving tank 43 is greater than the setting height of the ammonium sulfate dissolving tank 45, and the outlet of the potassium chloride dissolving tank 43 is connected to the inlet of the ammonium sulfate dissolving tank 45 through the third regulating valve 44. The acid gas unit of the gasification system includes a high-temperature flash gasifier 1. The top gas phase outlet of the high-temperature flash gasifier 1 is connected to the bottom gas phase inlet of the high-temperature hot water tower 3. The upper part of the high-temperature hot water tower 3 is connected to a low-temperature ash water pipeline 2. The top gas phase outlet of the high-temperature hot water tower 3 is connected to a first acid gas cooler 5. The liquid phase outlet of the first acid gas cooler 5 is connected to a gasification clarification tank 6. The gas phase outlet of the first acid gas cooler 5 is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 via a third three-way valve 16. A second three-way valve 11 and a tenth regulating valve 15 are sequentially provided between the gas phase outlet of the first acid gas cooler 5 and the third three-way valve 16. The third end of the second three-way valve 11 is sequentially connected to the converter 14 in the conversion system via a ninth regulating valve 12 and a fuel gas compressor 13. An eleventh regulating valve 17 is provided between the third three-way valve 16 and the heat tracing gas inlet of the Claus combustion furnace 18. The acid gas unit of the low-temperature methanol washing system includes a methanol washing thermal regenerator 9. The gas phase outlet of the methanol washing thermal regenerator 9 is connected to an acid gas separator 58 via a second acid gas cooler 10. The gas phase outlet of the acid gas separator 58 is connected to the feed gas inlet of the Claus combustion furnace 18. The acid gas unit of the shift stripping tower includes a low-pressure flash tank 4. The gas phase outlet of the low-pressure flash tank 4 is connected to the gas phase inlet at the bottom of the shift stripping tower 7. The upper inlet of the shift stripping tower 7 is connected to the waste liquid pipeline 8 of the shift ammonia washing tower. The gas phase outlet at the top of the shift stripping tower 7 is connected to the inlet of the waste gas combustion furnace 21. The sulfur preparation unit includes a Claus combustion furnace 18. The outlet of the Claus combustion furnace 18 is connected to the inlet of the Claus reactor 19. The liquid phase outlet of the Claus reactor 19 is connected to the sulfur warehouse 20 via a sulfur granulation device 56. The gas phase outlet of the Claus reactor 19 is connected to the inlet of the waste gas combustion furnace 21.

[0072] The present invention also provides a method for comprehensive utilization of acid gas from an ammonia synthesis plant, the method comprising the following steps:

[0073] Step 1: The high-temperature black water in the gasification system enters the high-temperature flash evaporator 1 for flash evaporation. The flashed gas phase enters the high-temperature hot water tower 3 and undergoes mass and heat transfer with the low-temperature ash water from the low-temperature ash water pipeline 2. The unabsorbed non-condensable gas and some water vapor enter the first acid gas cooler 5 for condensation. The condensed liquid phase enters the gasification clarification tank 6 as gasification circulating water for reuse. The uncondensed acid gas enters the second three-way valve 11. One path is sent to the fuel gas compressor 13 through the ninth regulating valve 12 for pressurization. After the pressure rises to 6.3 MPa (G), it is sent to the converter 14 in the conversion system as raw material for recycling. The other path enters the third three-way valve 16 through the tenth regulating valve 15 and enters the waste gas combustion furnace 21 and Claus combustion furnace 18 respectively as fuel gas.

[0074] Step 2: Low-pressure steam from the low-pressure flash tank 4 of the gasification system enters the shift stripping tower 7 as the stripping heat source of the shift stripping tower 7, and comes into countercurrent contact with the waste liquid from the shift ammonia washing tower from the waste liquid pipeline 8, stripping out the acidic gas in the waste liquid of the shift ammonia washing tower. The stripped acidic gas enters the waste gas combustion furnace 21 for incineration.

[0075] Step 3: The acidic gas from the methanol washing heat regenerator 9 enters the second acidic gas cooler 10 for condensation, condensing out the methanol and water in the acidic gas. The condensed acidic gas enters the acidic gas separator 58 for separation, and the separated gas phase enters the Claus combustion furnace 18 for combustion.

[0076] Step 4: The acidic gas from Steps 1 and 3 above enters the Claus combustion furnace 18 for combustion, converting some of the hydrogen sulfide into sulfur dioxide. Then, it enters the Claus reactor 19 to react with the hydrogen sulfide to produce liquid sulfur. The liquid sulfur enters the sulfur granulation device 56 for granulation, and the granulated sulfur enters the sulfur warehouse 20 for packaging and sale. The tail gas produced in the Claus reactor 19 enters the waste gas combustion furnace 21 for incineration. The tail gas produced in the Claus reactor 19 contains some unreacted carbon monoxide and sulfur dioxide.

[0077] Step 5: The acidic gas from Step 1, the acidic gas from Step 2, and the tail gas produced in the Claus reactor 19 in Step 4 are all fed into the waste gas combustion furnace 21 for complete combustion. The tail gas from the waste gas combustion furnace 21 then enters the ammonia absorption tower 29, where ammonia absorbs the sulfur dioxide in the tail gas. The tail gas passes through the ammonia absorption tower 29 and is then washed in the water washing tower 25 before being discharged in compliance with emission standards.

[0078] Step 6: The demineralized water in the demineralized water storage tank 30 is pressurized by the demineralized water makeup pump 23 and sent to the water washing tower 25 to wash the tail gas after ammonia absorption. The amount of demineralized water entering the water washing tower 25 is regulated by the eighth regulating valve 22. The solution at the bottom of the water washing tower 25 is pressurized by the bottom pump 27 and then returned to the water washing tower 25 through the circulation port at the top of the water washing tower 25. This is to control the mass concentration of ammonia in the solution to within 5% while saving water, so as to facilitate the entry of the tail gas into the subsequent ammonia absorption tower 29 while ensuring that the tail gas emission is qualified. When demineralized water needs to be added, the demineralized water makeup pump 23 and the eighth regulating valve 22 are turned on.

[0079] Step 7: When the solution in Step 6 reaches the predetermined threshold, open the seventh regulating valve 28 to allow the solution in the fifth three-way valve 26 to enter the ammonia absorption tower 29 as the absorbent. The solution at the bottom of the ammonia absorption tower 29 is pressurized by the bottom pump 33 and then returned to the ammonia absorption tower 29 through the circulation port at the top of the ammonia absorption tower 29 for recycling. This lays the foundation for entering the subsequent ammonium sulfate concentration oxidation tower 36 under the premise of absorbent. When absorbent needs to be added and the solution in Step 6 has not reached the predetermined threshold, turn on the ammonia pump 35 to add ammonia water to the ammonia absorption tower 29 through the ammonia tank 24 with ammonia water pipe 57 as the absorbent.

[0080] Step 8: When the solution in Step 7 reaches the predetermined threshold, open the sixth regulating valve 31 to allow the ammonium sulfite solution in the fourth three-way valve 32 to enter the ammonium sulfate concentration oxidation tower 36 for oxidation and crystallization. The hot air in the hot air pipe 55 carries away some water vapor while oxidizing the ammonium sulfite, thus concentrating the ammonium sulfate. The waste nitrogen gas in the waste nitrogen exhaust pipe 34 enters the ammonium sulfate concentration oxidation tower 36 to further concentrate the ammonium sulfate. After secondary concentration, the ammonium sulfate enters the crystallizer 37 for crystallization. The mother liquor after crystallization enters the ammonia water tank 24 and is used as the absorbent in the ammonia water absorption tower 29.

[0081] Step 9: The solid phase crystallized by the crystallizer 37 in step 8 enters the ammonium sulfate dissolving tank 45 inside the compound fertilizer granulation tower 40 through the second weighing scale 38 and the second elevator 39 for the preparation of compound fertilizer.

[0082] Step 10: When preparing sulfur-nitrogen-potassium ternary compound fertilizer, open the first regulating valve 47, the second regulating valve 48, the third regulating valve 44, and the fifth regulating valve 46, and close the fourth regulating valve 42. Potassium chloride in the potassium chloride warehouse 52 enters the potassium chloride dissolving tank 43 through the first weighing scale 53 and the first elevator 54. Urea solution in the urea solution storage tank 51 enters the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 through the urea solution pump 50, respectively, so that the 99% urea solution dissolves the potassium chloride and ammonium sulfate. After dissolution, the urea solution containing potassium chloride enters the ammonium sulfate dissolving tank 45 by the height difference for mixing to obtain a compound fertilizer slurry. The compound fertilizer slurry enters the granulation nozzle 41 for granulation.

[0083] Example 3

[0084] A comprehensive utilization device for acid gas from a synthetic ammonia plant includes an acid gas unit for a gasification system, an acid gas unit for a low-temperature methanol washing system, and an acid gas unit for a shift stripping tower. The acid gas unit for the gasification system is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 in the sulfur preparation unit, respectively. The acid gas unit for the low-temperature methanol washing system is connected to the inlet of the Claus combustion furnace 18, and the acid gas unit for the shift stripping tower is connected to the inlet of the waste gas combustion furnace 21. The top tail gas outlet of the waste gas combustion furnace 21 is connected to a tail gas treatment unit, which is coupled to an ammonium sulfite solution preparation unit, which is connected to an ammonium sulfate preparation unit. The exhaust gas treatment unit includes an ammonia absorption tower 29 connected to the exhaust gas outlet of the waste gas combustion furnace 21. The gas phase outlet at the top of the ammonia absorption tower 29 is connected to the inlet of the water scrubbing tower 25, and the gas phase outlet at the top of the water scrubbing tower 25 is open to the atmosphere. The ammonium sulfite solution preparation unit includes a demineralized water storage tank 30, which is connected to the water scrubbing tower 25 via a demineralized water makeup pump 23 and an eighth regulating valve 22. The bottom outlet of the water scrubbing tower 25 is connected to the circulation port at the top of the water scrubbing tower 25 via a bottom pump 27. A fifth three-way valve 26 is provided between the bottom pump 27 of the washing tower and the circulation port at the top of the water washing tower 25. The third end of the fifth three-way valve 26 is connected to the inlet of the ammonia absorption tower 29 through the seventh regulating valve 28. The bottom outlet of the ammonia absorption tower 29 is connected to the circulation port at the top of the ammonia absorption tower 29 through the bottom pump 33 of the ammonia absorption tower. A fourth three-way valve 32 is provided between the bottom pump 33 of the ammonia absorption tower and the circulation port at the top of the ammonia absorption tower 29. The third end of the fourth three-way valve 32 is connected to the ammonium sulfate concentration oxidation tower 36 through the sixth regulating valve 31. The ammonia absorption tower 29 is provided with an ammonia absorption tower replenishment port, which is connected to the ammonia tank 24 with an ammonia pipeline 57 through the ammonia pump 35. The ammonium sulfate preparation unit includes an ammonium sulfate concentration and oxidation tower 36, which is connected to the waste nitrogen exhaust pipe 34 and the hot air pipe 55 in the air separation system. The bottom outlet of the ammonium sulfate concentration and oxidation tower 36 is connected to the crystallizer 37, the solid phase outlet of the crystallizer 37 is connected to the compound fertilizer production unit, and the liquid phase outlet of the crystallizer 37 is connected to the replenishment port of the ammonia water tank 24. The top gas phase outlet of the ammonium sulfate concentration and oxidation tower 36 is connected to the inlet of the water washing tower 25.The compound fertilizer production unit includes a compound fertilizer granulation tower 40, a urea solution storage tank 51, and a potassium chloride warehouse 52. The compound fertilizer granulation tower 40 includes granulation nozzles 41 located in the upper part of the tower. The inlet of the granulation nozzles 41 is connected to the outlets of a potassium chloride dissolving tank 43 and an ammonium sulfate dissolving tank 45 via a fourth regulating valve 42 and a fifth regulating valve 46, respectively. The solid phase inlet of the potassium chloride dissolving tank 43 is connected to the potassium chloride warehouse 52 via a first elevator 54 and a first weighing scale 53. The solid phase inlet of the ammonium sulfate dissolving tank 45 is connected to the potassium chloride warehouse 52 via a second elevator 54. The elevator 39 and the second metering scale 38 are connected to the solid phase outlet of the crystallizer 37; the liquid phase inlets of the potassium chloride dissolving tank 43 and the ammonium sulfate dissolving tank 45 are respectively connected to the first three-way valve 49 through their respective first regulating valve 47 and second regulating valve 48, and the third end of the first three-way valve 49 is connected to the outlet of the urea solution storage tank 51 through the urea solution pump 50; the setting height of the potassium chloride dissolving tank 43 is greater than the setting height of the ammonium sulfate dissolving tank 45, and the outlet of the potassium chloride dissolving tank 43 is connected to the inlet of the ammonium sulfate dissolving tank 45 through the third regulating valve 44. The acid gas unit of the gasification system includes a high-temperature flash gasifier 1. The top gas phase outlet of the high-temperature flash gasifier 1 is connected to the bottom gas phase inlet of the high-temperature hot water tower 3. The upper part of the high-temperature hot water tower 3 is connected to a low-temperature ash water pipeline 2. The top gas phase outlet of the high-temperature hot water tower 3 is connected to a first acid gas cooler 5. The liquid phase outlet of the first acid gas cooler 5 is connected to a gasification clarification tank 6. The gas phase outlet of the first acid gas cooler 5 is connected to the heat tracing gas inlet of the Claus combustion furnace 18 and the heat tracing gas inlet of the waste gas combustion furnace 21 via a third three-way valve 16. A second three-way valve 11 and a tenth regulating valve 15 are sequentially provided between the gas phase outlet of the first acid gas cooler 5 and the third three-way valve 16. The third end of the second three-way valve 11 is sequentially connected to the converter 14 in the conversion system via a ninth regulating valve 12 and a fuel gas compressor 13. An eleventh regulating valve 17 is provided between the third three-way valve 16 and the heat tracing gas inlet of the Claus combustion furnace 18. The acid gas unit of the low-temperature methanol washing system includes a methanol washing thermal regenerator 9. The gas phase outlet of the methanol washing thermal regenerator 9 is connected to an acid gas separator 58 via a second acid gas cooler 10. The gas phase outlet of the acid gas separator 58 is connected to the feed gas inlet of the Claus combustion furnace 18. The acid gas unit of the shift stripping tower includes a low-pressure flash tank 4. The gas phase outlet of the low-pressure flash tank 4 is connected to the gas phase inlet at the bottom of the shift stripping tower 7. The upper inlet of the shift stripping tower 7 is connected to the waste liquid pipeline 8 of the shift ammonia washing tower. The gas phase outlet at the top of the shift stripping tower 7 is connected to the inlet of the waste gas combustion furnace 21. The sulfur preparation unit includes a Claus combustion furnace 18. The outlet of the Claus combustion furnace 18 is connected to the inlet of the Claus reactor 19. The liquid phase outlet of the Claus reactor 19 is connected to the sulfur warehouse 20 via a sulfur granulation device 56. The gas phase outlet of the Claus reactor 19 is connected to the inlet of the waste gas combustion furnace 21.

[0085] The present invention also provides a method for comprehensive utilization of acid gas from an ammonia synthesis plant, the method comprising the following steps:

[0086] Step 1: The high-temperature black water in the gasification system enters the high-temperature flash evaporator 1 for flash evaporation. The flashed gas phase enters the high-temperature hot water tower 3 and undergoes mass and heat transfer with the low-temperature ash water from the low-temperature ash water pipeline 2. The unabsorbed non-condensable gas and some water vapor enter the first acid gas cooler 5 for condensation. The condensed liquid phase enters the gasification clarification tank 6 as gasification circulating water for reuse. The uncondensed acid gas enters the second three-way valve 11. One path is sent to the fuel gas compressor 13 through the ninth regulating valve 12 for pressurization. After the pressure rises to 6.3 MPa (G), it is sent to the converter 14 in the conversion system as raw material for recycling. The other path enters the third three-way valve 16 through the tenth regulating valve 15 and enters the waste gas combustion furnace 21 and Claus combustion furnace 18 respectively as fuel gas.

[0087] Step 2: Low-pressure steam from the low-pressure flash tank 4 of the gasification system enters the shift stripping tower 7 as the stripping heat source of the shift stripping tower 7, and comes into countercurrent contact with the waste liquid from the shift ammonia washing tower from the waste liquid pipeline 8, stripping out the acidic gas in the waste liquid of the shift ammonia washing tower. The stripped acidic gas enters the waste gas combustion furnace 21 for incineration.

[0088] Step 3: The acidic gas from the methanol washing heat regenerator 9 enters the second acidic gas cooler 10 for condensation, condensing out the methanol and water in the acidic gas. The condensed acidic gas enters the acidic gas separator 58 for separation, and the separated gas phase enters the Claus combustion furnace 18 for combustion.

[0089] Step 4: The acidic gas from Steps 1 and 3 above enters the Claus combustion furnace 18 for combustion, converting some of the hydrogen sulfide into sulfur dioxide. Then, it enters the Claus reactor 19 to react with the hydrogen sulfide to produce liquid sulfur. The liquid sulfur enters the sulfur granulation device 56 for granulation, and the granulated sulfur enters the sulfur warehouse 20 for packaging and sale. The tail gas produced in the Claus reactor 19 enters the waste gas combustion furnace 21 for incineration. The tail gas produced in the Claus reactor 19 contains some unreacted carbon monoxide and sulfur dioxide.

[0090] Step 5: The acidic gas from Step 1, the acidic gas from Step 2, and the tail gas produced in the Claus reactor 19 in Step 4 are all fed into the waste gas combustion furnace 21 for complete combustion. The tail gas from the waste gas combustion furnace 21 then enters the ammonia absorption tower 29, where ammonia absorbs the sulfur dioxide in the tail gas. The tail gas passes through the ammonia absorption tower 29 and is then washed in the water washing tower 25 before being discharged in compliance with emission standards.

[0091] Step 6: The demineralized water in the demineralized water storage tank 30 is pressurized by the demineralized water makeup pump 23 and sent to the water washing tower 25 to wash the tail gas after ammonia absorption. The amount of demineralized water entering the water washing tower 25 is regulated by the eighth regulating valve 22. The solution at the bottom of the water washing tower 25 is pressurized by the bottom pump 27 and then returned to the water washing tower 25 through the circulation port at the top of the water washing tower 25. This is to control the mass concentration of ammonia in the solution to within 5% while saving water, so as to facilitate the entry of the tail gas into the subsequent ammonia absorption tower 29 while ensuring that the tail gas emission is qualified. When demineralized water needs to be added, the demineralized water makeup pump 23 and the eighth regulating valve 22 are turned on.

[0092] Step 7: When the solution in Step 6 reaches the predetermined threshold, open the seventh regulating valve 28 to allow the solution in the fifth three-way valve 26 to enter the ammonia absorption tower 29 as the absorbent. The solution at the bottom of the ammonia absorption tower 29 is pressurized by the bottom pump 33 and then returned to the ammonia absorption tower 29 through the circulation port at the top of the ammonia absorption tower 29 for recycling. This lays the foundation for entering the subsequent ammonium sulfate concentration oxidation tower 36 under the premise of absorbent. When absorbent needs to be added and the solution in Step 6 has not reached the predetermined threshold, turn on the ammonia pump 35 to add ammonia water to the ammonia absorption tower 29 through the ammonia tank 24 with ammonia water pipe 57 as the absorbent.

[0093] Step 8: When the solution in Step 7 reaches the predetermined threshold, open the sixth regulating valve 31 to allow the ammonium sulfite solution in the fourth three-way valve 32 to enter the ammonium sulfate concentration oxidation tower 36 for oxidation and crystallization. The hot air in the hot air pipe 55 carries away some water vapor while oxidizing the ammonium sulfite, thus concentrating the ammonium sulfate. The waste nitrogen gas in the waste nitrogen exhaust pipe 34 enters the ammonium sulfate concentration oxidation tower 36 to further concentrate the ammonium sulfate. After secondary concentration, the ammonium sulfate enters the crystallizer 37 for crystallization. The mother liquor after crystallization enters the ammonia water tank 24 and is used as the absorbent in the ammonia water absorption tower 29.

[0094] Step 9: When it is necessary to prepare nitrogen-potassium binary compound fertilizer, the solid phase crystallized by crystallizer 37 in step 8 is dried and then sold externally; close the second regulating valve 48, the third regulating valve 44 and the fifth regulating valve 46, open the first regulating valve 47 and the fourth regulating valve 42, and the urea solution in the urea solution storage tank 51 enters the potassium chloride dissolving tank 43 through the urea solution pump 50, so that the 99% urea solution dissolves the potassium chloride, and after dissolution, it enters the granulation nozzle 41 for granulation.

[0095] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0096] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, changes, or combinations, or the direct application of the inventive concept and technical solution to other occasions without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A device for the comprehensive utilization of acidic gas from an ammonia synthesis plant, characterized in that: This includes the acid gas unit of the gasification system, the acid gas unit of the low-temperature methanol washing system, and the acid gas unit of the shift stripping tower. The acid gas unit of the gasification system is connected to the heat tracing gas inlet of the Claus combustion furnace (18) and the heat tracing gas inlet of the waste gas combustion furnace (21) in the sulfur preparation unit, respectively. The acid gas unit of the low-temperature methanol washing system is connected to the inlet of the Claus combustion furnace (18), and the acid gas unit of the shift stripping tower is connected to the inlet of the waste gas combustion furnace (21). The top tail gas outlet of the waste gas combustion furnace (21) is connected to the tail gas treatment unit, the tail gas treatment unit is coupled to the ammonium sulfite solution preparation unit, and the ammonium sulfite solution preparation unit is connected to the ammonium sulfate preparation unit. The exhaust gas treatment unit includes an ammonia water absorption tower (29) connected to the exhaust gas outlet of the waste gas combustion furnace (21). The gas phase outlet at the top of the ammonia water absorption tower (29) is connected to the inlet of the water washing tower (25), and the gas phase outlet at the top of the water washing tower (25) is connected to the atmosphere. The ammonium sulfite solution preparation unit includes a demineralized water storage tank (30), which is connected to a water washing tower (25) via a demineralized water replenishment pump (23) and an eighth regulating valve (22). The bottom outlet of the water washing tower (25) is connected to the circulation port at the top of the water washing tower (25) via a water washing tower bottom pump (27). A fifth three-way valve (26) is provided between the water washing tower bottom pump (27) and the circulation port at the top of the water washing tower (25). The third end of the fifth three-way valve (26) is connected to the inlet of the ammonia absorption tower (29) via a seventh regulating valve (28). The bottom outlet of the ammonia absorption tower (29) is connected to the circulation port at the top of the ammonia absorption tower (29) via an ammonia absorption tower bottom pump (33). A fourth three-way valve (32) is provided between the ammonia absorption tower bottom pump (33) and the circulation port at the top of the ammonia absorption tower (29). The third end of the fourth three-way valve (32) is connected to the ammonium sulfate concentration oxidation tower (36) via a sixth regulating valve (31).

2. The ammonia synthesis unit acid gas comprehensive utilization device according to claim 1, characterized in that: The ammonia absorption tower (29) is provided with an ammonia absorption tower replenishment port, which is connected to an ammonia tank (24) with an ammonia pipeline (57) via an ammonia pump (35).

3. The ammonia synthesis unit acid gas comprehensive utilization device according to claim 2, characterized in that: The ammonium sulfate preparation unit includes an ammonium sulfate concentration oxidation tower (36), which is connected to the waste nitrogen exhaust pipe (34) and the hot air pipe (55) in the air separation system. The bottom outlet of the ammonium sulfate concentration oxidation tower (36) is connected to the crystallizer (37), the solid phase outlet of the crystallizer (37) is connected to the compound fertilizer production unit, and the liquid phase outlet of the crystallizer (37) is connected to the liquid replenishment port of the ammonia water tank (24). The top gas phase outlet of the ammonium sulfate concentration oxidation tower (36) is connected to the inlet of the water washing tower (25).

4. The ammonia synthesis unit acid gas comprehensive utilization device according to claim 3, characterized in that: The compound fertilizer production unit includes a compound fertilizer granulation tower (40), a urea solution storage tank (51), and a potassium chloride warehouse (52). The compound fertilizer granulation tower (40) includes a granulation nozzle (41) located in the upper part of the compound fertilizer granulation tower (40). The inlet of the granulation nozzle (41) is connected to the outlet of the potassium chloride dissolving tank (43) and the ammonium sulfate dissolving tank (45) through the fourth regulating valve (42) and the fifth regulating valve (46), respectively. The solid phase inlet of the potassium chloride dissolving tank (43) is connected to the potassium chloride warehouse (52) through the first elevator (54) and the first weighing scale (53). The solid phase inlet of the ammonium sulfate dissolving tank (45) is connected to the solid phase outlet of the crystallizer (37) through the second elevator (39) and the second weighing scale (38). The liquid phase inlets of the potassium chloride dissolving tank (43) and the ammonium sulfate dissolving tank (45) are connected to the first three-way valve (49) through their respective first regulating valve (47) and second regulating valve (48), respectively. The third end of the first three-way valve (49) is connected to the outlet of the urea solution storage tank (51) through the urea solution pump (50). The potassium chloride dissolving tank (43) is set at a greater height than the ammonium sulfate dissolving tank (45), and the outlet of the potassium chloride dissolving tank (43) is connected to the inlet of the ammonium sulfate dissolving tank (45) through a third regulating valve (44).

5. A comprehensive utilization device for acidic gas from a synthetic ammonia unit according to claim 1, characterized in that: The gasification system acid gas unit includes a gasification high-temperature flash tank (1), the top gas phase outlet of the gasification high-temperature flash tank (1) is connected to the bottom gas phase inlet of the gasification high-temperature hot water tower (3), the upper part of the gasification high-temperature hot water tower (3) is connected to a gasification low-temperature ash water pipe (2), the top gas phase outlet of the gasification high-temperature hot water tower (3) is connected to a first acid gas cooler (5), the liquid phase outlet of the first acid gas cooler (5) is connected to a gasification clarification tank (6), and the gas phase outlet of the first acid gas cooler (5) is connected to the heat tracing gas inlet of the Claus combustion furnace (18) and the heat tracing gas inlet of the waste gas combustion furnace (21) respectively through a third tee (16).

6. The ammonia synthesis unit acid gas comprehensive utilization device according to claim 5, characterized in that: A second three-way valve (11) and a tenth regulating valve (15) are sequentially provided between the gas phase outlet of the first acid gas cooler (5) and the third three-way valve (16). The third end of the second three-way valve (11) is connected to the converter (14) in the conversion system via the ninth regulating valve (12) and the fuel gas compressor (13). An eleventh regulating valve (17) is provided between the third three-way valve (16) and the combustion gas inlet of the Claus combustion furnace (18).

7. The ammonia synthesis unit acid gas comprehensive utilization device according to claim 1, characterized in that: The acid gas unit of the low-temperature methanol washing system includes a methanol washing heat regenerator (9). The gas phase outlet of the methanol washing heat regenerator (9) is connected to the acid gas separator (58) through the second acid gas cooler (10). The gas phase outlet of the acid gas separator (58) is connected to the raw material gas inlet of the Claus combustion furnace (18). The acid gas unit of the shift stripping tower includes a low-pressure flash tank (4). The gas phase outlet of the low-pressure flash tank (4) is connected to the gas phase inlet at the bottom of the shift stripping tower (7). The upper inlet of the shift stripping tower (7) is connected to the waste liquid pipeline (8) of the shift ammonia washing tower. The gas phase outlet at the top of the shift stripping tower (7) is connected to the inlet of the waste gas combustion furnace (21).

8. A comprehensive utilization device for acidic gas from a synthetic ammonia unit according to claim 1, characterized in that: The sulfur preparation unit includes a Claus combustion furnace (18), the outlet of which is connected to the inlet of a Claus reactor (19), the liquid phase outlet of the Claus reactor (19) is connected to a sulfur warehouse (20) via a sulfur granulation device (56), and the gas phase outlet of the Claus reactor (19) is connected to the inlet of a waste gas combustion furnace (21).

9. A method for comprehensive utilization of acidic gas from an ammonia synthesis unit, characterized in that: This comprehensive utilization method includes the following steps: Step 1: The high-temperature black water in the gasification system enters the gasification high-temperature flash tank (1) for flash evaporation. The gas phase after flash evaporation enters the gasification high-temperature hot water tower (3) and undergoes mass and heat transfer with the gasification low-temperature ash water from the gasification low-temperature ash water pipeline (2). The unabsorbed non-condensable gas and some water vapor enter the first acid gas cooler (5) for condensation. The condensed liquid phase enters the gasification clarification tank (6) as gasification circulating water for reuse. The uncondensed acid gas enters the second three-way valve (11). One path is sent to the fuel gas compressor (13) for pressurization through the ninth regulating valve (12). After the pressure rises to 6.3MPa (G), it is sent to the converter (14) in the conversion system as raw material for recycling. The other path enters the third three-way valve (16) through the tenth regulating valve (15) and enters the waste gas combustion furnace (21) and Claus combustion furnace (18) respectively as fuel gas. Step 2: Low-pressure steam from the low-pressure flash tank (4) of the gasification system enters the shift stripping tower (7) as the stripping heat source of the shift stripping tower (7), and comes into countercurrent contact with the waste liquid from the shift ammonia washing tower from the waste liquid pipeline (8) to strip out the acidic gas in the waste liquid of the shift ammonia washing tower. The stripped acidic gas enters the waste gas combustion furnace (21) for incineration. Step 3: The acid gas from the methanol washing heat regenerator (9) enters the second acid gas cooler (10) for condensation, condensing out the methanol and water in the acid gas. The condensed acid gas enters the acid gas separator (58) for separation, and the separated gas phase enters the Claus combustion furnace (18) for combustion. Step 4: The acidic gas from Step 1 and Step 3 above enters the Claus combustion furnace (18) for combustion, converting part of the hydrogen sulfide into sulfur dioxide, and then enters the Claus reactor (19) to react hydrogen sulfide and sulfur dioxide to produce liquid sulfur. The liquid sulfur enters the sulfur granulation device (56) for granulation, and the granulated sulfur enters the sulfur warehouse (20) for packaging and sale. The tail gas produced in the Claus reactor (19) enters the waste gas combustion furnace (21) for incineration; the tail gas produced in the Claus reactor (19) contains some unreacted carbon monoxide and sulfur dioxide; Step 5: The acidic gas from Step 1, the acidic gas from Step 2, and the tail gas produced in the Claus reactor (19) in Step 4 are all fed into the waste gas combustion furnace (21) for complete combustion. The tail gas from the waste gas combustion furnace (21) then enters the ammonia absorption tower (29) to absorb the sulfur dioxide in the tail gas. The tail gas passes through the ammonia absorption tower (29) and is then washed in the water washing tower (25) before being discharged in compliance with standards. Step 6: The demineralized water in the demineralized water storage tank (30) is pressurized by the demineralized water makeup pump (23) and sent to the water washing tower (25) to wash the tail gas after ammonia absorption. The amount of demineralized water entering the water washing tower (25) is adjusted by the eighth regulating valve (22). The solution at the bottom of the water washing tower (25) is pressurized by the bottom pump (27) and then returned to the water washing tower (25) through the circulation port at the top of the water washing tower (25) to achieve the goal of controlling the mass concentration of ammonia in the solution to within 5% while saving water, so as to facilitate the entry of the tail gas into the subsequent ammonia absorption tower (29) under the premise of ensuring that the tail gas emission is qualified. When demineralized water needs to be added, the demineralized water makeup pump (23) and the eighth regulating valve (22) are turned on. Step 7: When the solution in step 6 reaches the predetermined threshold, open the seventh regulating valve (28) to allow the solution in the fifth three-way valve (26) to enter the ammonia absorption tower (29) as the absorbent. The solution at the bottom of the ammonia absorption tower (29) is pressurized by the bottom pump (33) and then flows back to the ammonia absorption tower (29) through the circulation port at the top of the ammonia absorption tower (29) for circulation. This lays the foundation for entering the subsequent ammonium sulfate concentration oxidation tower (36) under the premise of absorbent. When absorbent needs to be added and the solution in step 6 has not reached the predetermined threshold, turn on the ammonia pump (35) to allow the ammonia tank (24) with ammonia pipe (57) to add ammonia to the ammonia absorption tower (29) as the absorbent. Step 8: When the solution in step 7 reaches the predetermined threshold, open the sixth regulating valve (31) to allow the ammonium sulfite solution in the fourth three-way valve (32) to enter the ammonium sulfate concentration oxidation tower (36) for oxidation and crystallization. The hot air in the hot air pipe (55) carries away some water vapor while oxidizing the ammonium sulfite, which can concentrate the ammonium sulfate. The waste nitrogen in the waste nitrogen exhaust pipe (34) enters the ammonium sulfate concentration oxidation tower (36) to concentrate the ammonium sulfate for a second time. After the second concentration, the ammonium sulfate enters the crystallizer (37) for crystallization. The mother liquor after crystallization enters the ammonia water tank (24) and is used as the absorbent in the ammonia water absorption tower (29). Step 9: The solid phase crystallized by the crystallizer (37) in step 8 is fed into the ammonium sulfate dissolving tank (45) inside the compound fertilizer granulation tower (40) through the second weighing scale (38) and the second elevator (39) to prepare compound fertilizer; Step 10: When it is necessary to prepare sulfur-nitrogen binary compound fertilizer, close the first regulating valve (47), the fourth regulating valve (42) and the third regulating valve (44), and open the second regulating valve (48) and the fifth regulating valve (46). The urea solution in the urea solution storage tank (51) enters the ammonium sulfate dissolving tank (45) through the urea solution pump (50) to dissolve the ammonium sulfate with a concentration of 99%. After dissolution, it enters the granulation nozzle (41) for granulation. Step 11: When it is necessary to prepare sulfur-nitrogen-potassium ternary compound fertilizer, open the first regulating valve (47), the second regulating valve (48), the third regulating valve (44) and the fifth regulating valve (46), and close the fourth regulating valve (42). The potassium chloride in the potassium chloride warehouse (52) enters the potassium chloride dissolving tank (43) through the first weighing scale (53) and the first elevator (54). The urea solution in the urea solution storage tank (51) enters the potassium chloride dissolving tank (43) and the ammonium sulfate dissolving tank (45) through the urea solution pump (50) respectively, so that the urea solution with a concentration of 99% dissolves the potassium chloride and ammonium sulfate respectively. After dissolution, the urea solution containing potassium chloride enters the ammonium sulfate dissolving tank (45) by the height difference for mixing to obtain compound fertilizer slurry. The compound fertilizer slurry enters the granulation nozzle (41) for granulation. Step 12: When it is necessary to prepare nitrogen-potassium binary compound fertilizer, the solid phase crystallized by the crystallizer (37) in step 8 is dried and then sold externally; close the second regulating valve (48), the third regulating valve (44) and the fifth regulating valve (46), open the first regulating valve (47) and the fourth regulating valve (42), and the urea solution in the urea solution storage tank (51) enters the potassium chloride dissolving tank (43) through the urea solution pump (50) so that the urea solution with a concentration of 99% dissolves the potassium chloride. After dissolution, it enters the granulation nozzle (41) for granulation.

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