Ammonia-containing tail gas treatment system and method for ultra-pure ammonia production

Abstract

The system comprises an ammonia-containing tail gas pretreatment system and a normal-pressure gas ammonia absorption system, the ammonia-containing tail gas pretreatment system comprises a high-pressure buffer tank, a low-pressure buffer tank and an ammonia gas condenser, the high-pressure buffer tank is used for receiving ammonia sources of high-pressure ammonia-containing tail gas of an ultra-pure ammonia production system, and the low-pressure buffer tank is used for receiving ammonia sources of the high-pressure ammonia-containing tail gas of the ultra-pure ammonia production system; the tube pass liquid outlet end of the ammonia gas condenser is communicated with the high-pressure buffer tank through a condensed liquid ammonia return pipeline; the low-pressure buffer tank is used for receiving low-pressure ammonia-containing tail gas ammonia sources of the ultra-pure ammonia production system and is communicated with a tube pass gas outlet end of the ammonia condenser, and gas ammonia in the low-pressure buffer tank is conveyed to the normal-pressure gas ammonia absorption system for absorption treatment; overpressure ammonia gas generated by the high-pressure buffer tank and the low-pressure buffer tank is discharged emergently for system pressure relief, and liquid ammonia generated by the system serves as a refrigerant for heat exchange. According to the invention, the ammonia-containing tail gas of the ultra-pure ammonia production system can be recovered in the whole process, so that zero emission of the ultra-pure ammonia tail gas is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-pure ammonia production, and in particular relates to a system and method for treating ammonia-containing tail gas in ultra-pure ammonia production. Background Art

[0002] The main processes for producing soda ash include the combined soda process, the ammonia soda process and the natural soda process. The combined soda process adopts the concentrated gas alkali production process. The process is described as carbon dioxide reacts with ammonia, salt and water in a carbonization tower to generate a slurry of sodium bicarbonate and ammonium chloride, which is then filtered and calcined to produce soda ash. The filtrate is cooled and salted out to produce ammonium chloride, which is then dried to produce dry ammonium. The raw materials are NaCl (wet salt), NH3 (liquid ammonia), H2O, and CO2 (gas). The process has one salt addition, two ammonia absorption, one carbonization, and the mother liquor system is circulated to form a ring reaction system. In the combined alkali process, single salt addition means that in the entire circulation process, raw salt (NaCl) is only added at a specific step. This step usually occurs after the carbonization process and is used to generate ammonium chloride. Specifically, during the carbonization process, ammoniacal brine (obtained by further treatment of ammonia, water and carbon dioxide to generate ammonium carbonate) reacts with carbon dioxide to generate sodium bicarbonate precipitate and ammonium chloride. At this time, in order to replenish the chloride ions consumed in the generation of ammonium chloride, raw salt needs to be added to maintain the ion balance in the solution and ensure the continuation of the cycle. The two ammonia absorptions are a key step in the combined alkali process, which helps to optimize the reaction conditions and improve the purity and yield of the product. Specifically, the two ammonia absorptions are carried out in two different stages: the first ammonia absorption is before or during the carbonization process to add a part of ammonia to the mother liquor. The main purpose of this step is to increase the ammonia concentration in the mother liquor and provide sufficient ammonia source for the subsequent carbonization reaction. By increasing the ammonia concentration in the mother liquor, the formation of ammonium bicarbonate can be promoted, which is beneficial to the precipitation and precipitation of sodium bicarbonate. After the carbonization process is completed, the second ammonia absorption is to add ammonia to the mother liquor obtained by filtration and separation (which already contains ammonium chloride). The main purpose of this step is to supplement the ammonia consumed in the formation of ammonium chloride and adjust the ammonia concentration in the mother liquor to prepare for the subsequent circulation production. The second ammonia absorption can ensure that the ammonia concentration in the mother liquor is kept within an appropriate range, thereby ensuring the stability and efficiency of the entire circulation production.

[0003] The raw materials for the combined alkali process are CO2, NH3, NaCl, and H2O; the main reaction equation is: NaCl (liquid) + NH3 (liquid) + H2O (liquid) + CO2 (gas) = ​​NaHCO3 (solid) + NH4Cl (liquid); 2NaHCO3(solid)=Na2CO3(solid)+CO2(vapor)+H2O↑(vapor).

[0004] The combined alkali production process is generally equipped with a thermal power system for heating and power supply, a synthetic ammonia system for supplying raw gas CO2 (gas) and raw material NH3, and a vacuum salt production system for supplying raw material NaCl. Our company further extends the industrial chain by deep processing of raw material NH3, and further purifies the NH3 with a content of 99.9% in the component to produce electronic-grade ammonia with a raw material NH3 content of more than 99.99999%. Electronic-grade ultra-pure ammonia is an important raw material in optoelectronic and microelectronic fields such as semiconductor lighting, integrated circuits, flat panel display panels, and solar cells. In the process of producing solar cells and LED chips, ultra-pure ammonia is required as a nitrogen source. Especially in the growth process of LED chips, the higher the ammonia purity of the raw materials, the lower the power consumption and the greater the luminous intensity of the prepared LED. In addition, ultra-pure ammonia is also an important basic material for the preparation of gallium nitride (GAN) using MOCVD technology. As an important material for the third-generation semiconductors, gallium nitride has a wide range of scenarios. 7N electronic grade ultra-pure ammonia is also widely used in optoelectronic fields such as liquid crystal display (LCD) and organic electric laser display (OLED). Its quality directly affects the optical and electrical properties of the material and even the service life of the device. It is an important link in the development of the industrial chain.

[0005] The existing ultra-pure ammonia tail gas treatment process: the ammonia-containing tail gas first enters the first tail gas absorption tower and is sprayed and absorbed by the circulating pump. The high-concentration (below 20%) ammonia water is pumped into the ammonia water storage tank by the circulating ammonia water pump and transported to the alkali ammonia water tank by the delivery pump; the ammonia that is not completely absorbed is absorbed by the second tail gas absorption tower. The tower function is designed as a packing and spraying grouping and grading type. The ammonia-containing tail gas is first fully contacted and absorbed with the tower bottom liquid phase, and then enters the first-level packing functional section. The first-level circulation spray is carried out by the circulating liquid, so that the gas-liquid two-phase is fully contacted for the third time, and through continuous circulation absorption, the low-concentration ammonia water (below 5%) is transported to the first tail gas absorption tower as make-up water by the circulating ammonia water pump; the waste gas after multiple treatments enters the second-level packing desalted water spraying functional section, and then the waste gas is subjected to a more sufficient gas-liquid two-phase contact reaction, while effectively suppressing the volatilization of ammonia water, and the tail gas of the absorption tower is discharged from the exhaust pipe in compliance with the standards.

[0006] The main problem with the above-mentioned ammonia-containing tail gas treatment process is that the two tail gas absorption towers in series are cooled by circulating water to promote the absorption of ammonia tail gas. The absorption of ammonia by water in the tail gas treatment system is an exothermic reaction, and 87.8 kcal (Note: 1kcal=4.17kJ) of solution heat will be released for every 1kg of ammonia absorbed. Therefore, this part of the heat must be transferred in time during the treatment process, and the ammonia absorption temperature must be controlled according to the equilibrium curve of water absorption of ammonia to ensure the efficient reaction of ammonia and water so that the ammonia water reaches the target concentration; in the current tail gas circulation washing and absorption process, circulating water is used to transfer this part of the solution heat through a shell and tube heat exchanger to produce ammonia water with a concentration of 20% for desulfurization and denitrification in thermal power plants. The tail gas treatment system requires that the ammonia content in the exhaust gas discharged after the tail gas is treated can meet the national emission standards. According to the emission standard for odor pollutants (GB 14554-93), the emission standard for ammonia organized emission chimneys is ≤4.9kg / h when the height is 15m. However, the tail gas treatment system has a high circulating water temperature and poor heat exchange effect in summer operation, and the treatment capacity of the two tail gas absorption towers decreases. This requires reducing the treatment intensity of the ammonia absorption tower and increasing the intensity of the heat exchange process to ensure that various indicators during operation meet the process requirements, which will greatly increase the energy consumption of the tail gas treatment system and there is a risk of excessive ammonia content in the tail gas. Summary of the invention

[0007] Technical problem to be solved: In view of the problems existing in the treatment process of ammonia-containing tail gas in the background technology, the present invention provides an ammonia-containing tail gas treatment system and method for ultra-pure ammonia production, which recovers the ammonia-containing tail gas of the ultra-pure ammonia production system throughout the entire process, thereby achieving zero emission of ultra-pure ammonia tail gas.

[0008] Technical solution: The ammonia-containing tail gas treatment system for ultra-pure ammonia production described in the present invention comprises an ammonia-containing tail gas pretreatment system and a normal pressure gas ammonia absorption system; The ammonia-containing tail gas pretreatment system comprises a high-pressure buffer tank, a low-pressure buffer tank, and an ammonia condenser; the high-pressure buffer tank is provided with a plurality of connection ends connected to the ammonia sources of each high-pressure ammonia-containing tail gas of the ultra-pure ammonia production system, one of which is connected to the tube-side air inlet end of the ammonia condenser through the high-pressure buffer tank evaporation gas ammonia pipeline, and the tube-side liquid outlet end of the ammonia condenser is connected to one of the connection ends of the high-pressure buffer tank through the condensate ammonia return pipeline; The low-pressure buffer tank is provided with a connection end connected to each low-pressure ammonia-containing tail gas ammonia source of the ultra-pure ammonia production system, one of the connection ends is connected to the pipe-side gas outlet end of the ammonia condenser through the ammonia condenser gas ammonia to low-pressure buffer tank pipeline, and the low-pressure buffer tank gas ammonia is transported to the atmospheric pressure gas ammonia absorption system for absorption treatment; The overpressure gaseous ammonia produced by the high-pressure buffer tank and the low-pressure buffer tank is discharged to the ultra-pure ammonia production system or the combined alkali production system as a gaseous ammonia raw material for emergency use, and the liquid ammonia produced by the high-pressure buffer tank and the low-pressure buffer tank is transported to the external cooler of the combined alkali crystallization process as a refrigerant for heat exchange.

[0009] Preferably, the atmospheric pressure gas ammonia absorption system comprises a jet ammonia absorber, an ammonia induced draft fan, an ammonia II distribution tank and at least one ammonia II clarification tank; The liquid inlet end of the jet ammonia absorber is connected to the mother II delivery pipeline and receives the mother II liquid, and the air inlet end of the jet ammonia absorber is connected to the ammonia induced draft fan and receives the gas ammonia from the low-pressure buffer tank; The liquid outlet end of the jet ammonia absorber is connected to the ammonia II distribution tank through a delivery pipeline, and the liquid outlet end of the ammonia II distribution tank is connected to the ammonia II clarification tank through a delivery pipeline.

[0010] Preferably, the atmospheric pressure gas ammonia absorption system comprises a first ammonia II clarification tank and a second ammonia II clarification tank, the liquid inlet end of the first ammonia II clarification tank is connected to the liquid outlet end of the ammonia II distribution tank, the liquid inlet end of the first ammonia II clarification tank is connected to the liquid inlet end of the second ammonia II clarification tank through an overflow pipe, and the liquid outlet end of the second ammonia II clarification tank is connected to the ammonia II carbon filtration process pipeline.

[0011] Preferably, the delivery pipeline from the ammonia induced draft fan to the jet ammonia absorber is also connected to the ammonia source pipeline of the crystallization process external cooling system.

[0012] The present invention also discloses a method for treating ammonia-containing tail gas of an ultrapure ammonia production system, the method comprising: Step 1: transporting the ammonia source that produces high-pressure ammonia-containing tail gas in the ultra-pure ammonia production system to a high-pressure buffer tank through a corresponding delivery pipeline, and transporting the ammonia source that produces low-pressure ammonia-containing tail gas in the ultra-pure ammonia production system to a low-pressure buffer tank through a corresponding delivery pipeline to separate ammonia; Step 2: The evaporated gas ammonia in the high-pressure buffer tank is transported to the ammonia condenser, and the condensed liquid ammonia generated after cooling by the refrigerant is returned to the high-pressure buffer tank through the condensed liquid ammonia return pipeline. The ammonia condenser gas ammonia produced after the ammonia condenser is depressurized is transported to the low-pressure buffer tank through the ammonia condenser gas ammonia to low-pressure buffer tank pipeline for ammonia separation; Step 3: The liquid ammonia separated and produced by the high-pressure buffer tank and the low-pressure buffer tank is pumped to the external cooler of the crystallization process of the alkali plant as the refrigerant of the crystallization system; Step 4: The atmospheric pressure low-pressure buffer tank gas ammonia produced by the low-pressure buffer tank is pressurized by the ammonia induced draft fan and then enters the jet ammonia absorber to react with the mother II liquid to form ammonia II liquid. The ammonia II liquid flows through the ammonia II distribution tank, the first ammonia II clarification tank, the overflow pipe and the second ammonia II clarification tank in sequence, and is transported to the carbon filtration system through the ammonia II carbon filtration process pipeline.

[0013] Preferably, in step 4, the gaseous ammonia produced by the external cooling system of the crystallization process enters the jet ammonia absorber together with the gaseous ammonia in the low-pressure buffer tank through the gaseous ammonia source pipeline of the external cooling system of the crystallization process to carry out ammonia absorption reaction.

[0014] Preferably, the ammonia source for the high-pressure ammonia-containing tail gas in step 1 includes one or more of a high boiling tower receiving tank ammonia source, a low boiling tower receiving tank ammonia source, a high boiling tower ammonia source, a low boiling tower ammonia source, and a low boiling tower condenser ammonia source.

[0015] Preferably, the ammonia source for the low-pressure ammonia-containing tail gas in step 1 includes one or more of a safety valve ammonia source, an ammonia buffer tank drainage ammonia source, a cylinder tail gas ammonia source, an ammonia recovery tank ammonia source, a workshop online analysis tail gas ammonia source, and a tank area online analysis tail gas ammonia source.

[0016] Preferably, in step 4, the pressure of the gaseous ammonia in the low-pressure buffer tank is 0.3-0.5 MPa after being pressurized by the ammonia induced draft fan.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The ultra-pure ammonia production system of the present invention can achieve "zero emission" of ammonia tail gas without the need to add an additional tail gas treatment system. There is no more discharge of odorous pollutants such as ammonia. It also reduces the difficulty of the traditional double-tower water washing system for ammonia preparation in summer operation and the subsequent ammonia sales problem, and there is no need to explore the process conditions for combining other uses in the factory; 2. On the basis of controlling the reasonable ultra-pure ammonia yield, the workload of the ammonia condenser can be reduced to reduce the power consumption of the refrigerant circulation system to achieve energy saving; 3. The double-tower absorption system used in the industry to prepare ammonia water for sale or self-use has been cancelled. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the ammonia source flow of the ammonia-containing tail gas treatment system of the present invention; Figure 2 It is a schematic flow diagram of the absorption section of the ammonia-containing tail gas treatment system of the present invention; Figure 3 It is a schematic diagram of the existing alkali production process by the combined alkali process.

[0019] Figure numerals: 1, high-pressure buffer tank; 2, high-boiling tower receiving tank ammonia source; 3, low-boiling tower receiving tank ammonia source; 4, high-boiling tower ammonia source; 5, low-boiling tower ammonia source; 6, low-boiling tower condenser ammonia source; 7, high-pressure buffer tank evaporation gas ammonia pipeline; 8, ammonia condenser; 9, circulating water pipeline; 10, circulating return water pipeline; 11, condensed liquid ammonia return pipeline; 12, liquid ammonia; 13, overpressure gas ammonia; 14, ammonia condenser gas ammonia to low-pressure buffer tank pipeline; 15, low-pressure buffer tank; 16, safety valve ammonia source; 17, Ammonia source for liquid discharge from ammonia buffer tank; 18. Ammonia source for tail gas from cylinder; 19. Ammonia source for ammonia recovery tank; 20. Ammonia source for online analysis of tail gas from workshop; 21. Ammonia source for online analysis of tail gas from tank area; 22. Ammonia in low-pressure buffer tank; 23. Ammonia induced draft fan; 24. Ammonia source pipeline for the external cooling system of the crystallization process; 25. Mother II delivery pipeline; 26. Jet ammonia absorber; 27. Ammonia II liquid; 28. Ammonia II distribution tank; 29. ​​The first ammonia II clarification barrel; 30. Overflow pipe; 31. The second ammonia II clarification barrel; 32. Ammonia II pipeline for carbon filtration process. DETAILED DESCRIPTION

[0020] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the attached Figures 1 to 3 The technical scheme of the embodiment of the present invention is clearly and completely described as shown. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0021] Example 1: Figure 1~2 As shown, an ammonia-containing tail gas treatment system for ultra-pure ammonia production of the present invention includes an ammonia-containing tail gas pretreatment system and a normal pressure gas ammonia absorption system. The ammonia-containing tail gas pretreatment system includes a high-pressure buffer tank 1, a low-pressure buffer tank 15, and an ammonia condenser 8. The high-pressure buffer tank 1 is provided with a plurality of connection ends connected to the ammonia sources of each high-pressure ammonia-containing tail gas of the ultra-pure ammonia production system. The ammonia source of the high-pressure ammonia-containing tail gas includes one or more of a high-boiling tower receiving tank ammonia source 2, a low-boiling tower receiving tank ammonia source 3, a high-boiling tower ammonia source 4, a low-boiling tower ammonia source 5, and a low-boiling tower condenser ammonia source 6, which are specifically regulated according to the various types of ammonia-containing tail gas output by the production system. One connection end of the high-pressure buffer tank 1 is connected to the air inlet end of the tube side of the ammonia condenser 8 through the high-pressure buffer tank evaporated gas ammonia pipeline 7, and the liquid outlet end of the tube side of the ammonia condenser 8 is connected to one connection end of the high-pressure buffer tank 1 through the condensate liquid ammonia return pipeline 11. The shell side of the ammonia condenser 8 is connected to the cooling circulating water through the circulating water pipeline 9 and the circulating return water pipeline 10 respectively, so as to realize the cooling and liquefaction of the gaseous ammonia of the ammonia condenser 8. The evaporated gas ammonia of the high-pressure buffer tank 1 produced by the high-pressure buffer tank 1 in the ammonia separation process is converted into condensed liquid ammonia after passing through the ammonia condenser 8 and returns to the high-pressure buffer tank 1, and the gaseous ammonia of the ammonia condenser enters the low-pressure buffer tank 15 through the conveying pipeline to participate in the ammonia separation.

[0022] The low-pressure buffer tank 15 is provided with a connection end for connecting various low-pressure ammonia-containing tail gas ammonia sources of the ultra-pure ammonia production system. The low-pressure ammonia-containing tail gas ammonia source includes one or more of a safety valve ammonia source 16, an ammonia buffer tank drainage ammonia source 17, a cylinder tail gas ammonia source 18, an ammonia recovery tank ammonia source 19, a workshop online analysis tail gas ammonia source 20, and a tank area online analysis tail gas ammonia source 21. The ammonia-containing tail gas is specifically regulated according to the various types of ammonia-containing tail gas produced by the production system. One of the connection ends of the low-pressure buffer tank 15 is connected to the pipe-side gas outlet end of the ammonia condenser 8 through the ammonia condenser gas ammonia to low-pressure buffer tank pipeline 14, and receives the low-pressure gas ammonia produced by the ammonia condenser 8; the low-pressure buffer tank 15 collects the gas ammonia produced during the ammonia separation process and transports it to the atmospheric pressure gas ammonia absorption system for absorption treatment, thereby realizing the full-process recovery of ammonia-containing tail gas in the ultra-pure ammonia production system and achieving zero emission of ultra-pure ammonia tail gas.

[0023] Among them, the overpressure gas ammonia 13 produced by the high-pressure buffer tank 1 and the low-pressure buffer tank 15 is discharged to the ultra-pure ammonia production system or the combined alkali production system as a gas ammonia raw material for emergency use. If the high-pressure buffer tank 1 and the low-pressure buffer tank 15 are overloaded with ammonia-containing tail gas and tripped during the treatment process, the overpressure gas ammonia can be used as the gas ammonia raw material of the ultra-pure ammonia production system or the combined alkali production system, thereby realizing the full process recovery of the system. The liquid ammonia 12 produced by the high-pressure buffer tank 1 and the low-pressure buffer tank 15 is transported to the external cooler of the combined alkali crystallization process as a refrigerant for heat exchange.

[0024] The atmospheric pressure gas ammonia absorption system includes a jet ammonia absorber 26, an ammonia induced draft fan 23, an ammonia II distribution tank 28 and at least one ammonia II clarification tank; the liquid inlet end of the jet ammonia absorber 26 is connected to the mother II conveying pipeline 25 and receives the mother II liquid, and the air inlet end of the jet ammonia absorber 26 is connected to the ammonia induced draft fan 23 and receives the low-pressure buffer tank gas ammonia 22; the conveying pipeline from the ammonia induced draft fan 23 to the jet ammonia absorber 26 is also connected to the crystallization process external cooling system gas ammonia source pipeline 24, and the gas ammonia produced by the crystallization process external cooling system and the gas ammonia produced by the low-pressure buffer tank 15 enter the jet ammonia absorber 26 together to participate in the absorption reaction.

[0025] The liquid outlet of the jet ammonia absorber 26 is connected to the ammonia II distribution tank 28 through a delivery pipeline, and the liquid outlet of the ammonia II distribution tank 28 is connected to the ammonia II clarification tank through a delivery pipeline. Specifically, the atmospheric pressure gas ammonia absorption system includes a first ammonia II clarification tank 29 and a second ammonia II clarification tank 31, the liquid inlet of the first ammonia II clarification tank 29 is connected to the liquid outlet of the ammonia II distribution tank 28, the liquid inlet of the first ammonia II clarification tank 29 is connected to the liquid inlet of the second ammonia II clarification tank 31 through an overflow pipe 30, and the liquid outlet of the second ammonia II clarification tank 31 is connected to the ammonia II carbon filtration process pipeline 32.

[0026] Embodiment 2: The present invention also discloses a method for treating ammonia-containing tail gas of an ultrapure ammonia production system, the method comprising: 1 The ammonia source producing high-pressure ammonia-containing tail gas in the ultra-pure ammonia production system is transported to the high-pressure buffer tank 1 through the corresponding delivery pipeline, and the ammonia source producing low-pressure ammonia-containing tail gas in the ultra-pure ammonia production system is transported to the low-pressure buffer tank 15 through the corresponding delivery pipeline to separate the ammonia; the high-pressure ammonia-containing tail gas ammonia source includes one or more of a high-boiling tower receiving tank ammonia source 2, a low-boiling tower receiving tank ammonia source 3, a high-boiling tower ammonia source 4, a low-boiling tower ammonia source 5, and a low-boiling tower condenser ammonia source 6, and the low-pressure ammonia-containing tail gas ammonia source includes one or more of a safety valve ammonia source 16, an ammonia buffer tank drainage ammonia source 17, a cylinder tail gas ammonia source 18, an ammonia recovery tank ammonia source 19, a workshop online analysis tail gas ammonia source 20, and a tank area online analysis tail gas ammonia source 21. The specific type of ammonia source is determined according to what kind of ammonia-containing tail gas is produced in the production process.

[0027] The evaporated gas ammonia in the high-pressure buffer tank 1 is transported to the ammonia condenser 8, and the condensed liquid ammonia generated after being cooled by the refrigerant is returned to the high-pressure buffer tank 1 through the condensed liquid ammonia return pipe 11. The ammonia condenser gas ammonia produced after the ammonia condenser 8 is depressurized is transported to the low-pressure buffer tank 15 through the ammonia condenser gas ammonia to low-pressure buffer tank pipe 14 to participate in the ammonia separation process.

[0028] The liquid ammonia 12 separated and produced by the high-pressure buffer tank 1 and the low-pressure buffer tank 15 is pumped to the external cooler of the crystallization process of the alkali plant as the refrigerant of the crystallization system, and can also be used as an ammonia source in the alkali plant system or the ultra-pure ammonia system.

[0029] The atmospheric pressure low-pressure buffer tank gas ammonia 22 produced by the low-pressure buffer tank 15 is pressurized by the ammonia induced draft fan 23 and enters the jet ammonia absorber 26 together with the gas ammonia produced by the external cooling system of the crystallization process for ammonia absorption reaction. The pressure of the low-pressure buffer tank gas ammonia 22 is 0.3-0.5MPa after being pressurized by the ammonia induced draft fan 23; it enters the jet ammonia absorber 26 for absorption reaction with the mother II liquid to form ammonia II liquid 27, and the ammonia II liquid 27 flows through the ammonia II distribution tank 28, the first ammonia II clarification tank 29, the overflow pipe 30 and the second ammonia II clarification tank 31 in sequence, and is transported to the carbon filtration system through the ammonia II carbon filtration process pipeline 32.

[0030] The ammonia-containing tail gas treatment system and method of the present invention are suitable for the second ammonia absorption of the ammonia-containing tail gas produced by the ultra-pure ammonia production system in the combined alkali system. At present, there are about 17 domestic manufacturers of soda ash by combined alkali process, with a minimum production capacity of 250,000 tons / year. According to the material balance diagram of the combined alkali process (such as Figure 3 As shown in Table 1, the mother II ammonia absorption capacity is basically consistent with the actual production situation. Using the material balance diagram data of 210.4kg / t, the mother II ammonia absorption capacity of the domestic minimum alkali-solvent system is 52,600 tons / year, and its gaseous ammonia demand far exceeds the possible output of any ultra-pure ammonia production system in China, and is fully capable of processing the ammonia tail gas produced by the ultra-pure ammonia device system.

[0031] Table 1 Material balance of combined alkali process:

[0032] .

[0033] The following are the operating data of our factory in June, July and August 2024 to illustrate the technical effects of the implementation of the present invention; among them, June and July are the production data before the implementation of the ammonia-containing exhaust gas treatment system of the present invention, and August is the production data after the implementation of the ammonia-containing exhaust gas treatment system of the present invention. By comparison, it can be seen that significant economic benefits have been generated after the implementation of the treatment system of the present invention.

[0034] 1In June 2024, it ran for 24 days, with raw ammonia of 344.61t, ultra-pure ammonia output of 234.42t, organized tail gas emission volume of 5.52t, residual liquid industrial ammonia volume of 57.08t, and 20% ammonia water volume (already converted according to the raw ammonia concentration): 47.59t. The residual liquid industrial ammonia has too many impurities in the light and heavy components discharged from the system and can no longer be returned to the system as raw ammonia. It is sent to the thermal power plant together with the prepared 20% ammonia water and the 20% ammonia water from the tail gas treatment part for use in ammonia-based desulfurization and denitrification, with a power consumption of 1372.63KWH / T.

[0035] It ran for 31 days in July 2024, with raw ammonia of 309.38t, ultra-pure ammonia output of 231.29t, organized tail gas emission volume of 3.89t, residual liquid industrial ammonia volume of 36.74t, and 20% ammonia water volume converted according to the raw ammonia concentration of 37.46t. Among them, the residual liquid industrial ammonia has too many impurities in the light and heavy components discharged from the system and can no longer be returned to the system as raw ammonia for use. It is sent to the thermal power plant together with the prepared 20% ammonia water and the 20% ammonia water of the tail gas treatment part for use in ammonia-based desulfurization and denitrification, with a power consumption of 1069.11KWH / T.

[0036] 32024 August operation for 31 days, raw ammonia: 396.69t, ultra-pure ammonia output: 341.98t, organized tail gas emission volume: 0t, residual liquid industrial ammonia volume: 54.71t. After debugging, the gaseous ammonia is directly sent by the ammonia induced draft fan 23 to the jet ammonia absorber of the crystallization process of the alkali plant for ammonia absorption, and the residual liquid industrial ammonia is directly sent to the alkali crystallization process as cold ammonia for system cooling, with a power consumption of 1033.11KWH / T.

[0037] According to the operating conditions of the above three months, the output rate of ultra-pure ammonia was 68.02% in June, 74.76% in July, and 86.21% in August. After the implementation of the present invention, the output rate of ultra-pure ammonia was significantly improved, and no ammonia water was produced. The double-tower absorption and ammonia water preparation system stopped operating, and the electricity consumption of the entire ultra-pure ammonia production system decreased from 1372.63 KWH / T in June to 1033.11 KWH / T in August.

[0038] According to the operating results under different loads provided by the test and production operation data in August 2023, the ultra-pure ammonia products produced are qualified (as shown in Table 2), and their overall quality is better than the group standard T∕CCGA 30001-2019, meeting user needs and having stable quality.

[0039] Table 2 Ultrapure ammonia product testing data:

[0040] .

[0041] According to the on-site measurement data report number: LTJ24014-3 of the third-party company Jiangsu Blue Sky Environmental Testing Technology Co., Ltd. on July 30, 2024, the emission rates are 0.018kg / h, 0.020kg / h, and 0.017kg / h. The emission rate of the organized ammonia-containing tail gas emission outlet is reduced from 0.018kg / h before implementation to 0kg / h after implementation ("Emission Standards for Odor Pollutants" (GB14554-1993≦0.6kg / h, emission outlet height 15m). Calculated based on the annual operation of the ultra-pure ammonia production system for 8,000 hours, the tail gas emission recovery alone can achieve an ammonia emission reduction of 144Kg / a in the ultra-pure ammonia system.

[0042] The ultra-pure ammonia production system of the present invention can also achieve "zero emission" of ammonia tail gas without the need to add an additional tail gas treatment system. There is no more discharge of odorous pollutants such as ammonia, and the traditional double-tower water washing system for preparing ammonia water is difficult to control in summer operation and the subsequent sale of ammonia water. There is no need to explore the process conditions for combining other uses in the factory. On the basis of controlling a reasonable ultra-pure ammonia yield, the workload of the ammonia condenser 8 can be reduced to reduce the power consumption of the refrigerant circulation system to achieve energy saving. In addition, the double-tower absorption system for preparing ammonia water for sale or self-use adopted in the industry has been eliminated.

[0043] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An ammonia-containing tail gas treatment system for ultrapure ammonia production, characterized in that: It includes an ammonia-containing tail gas pretreatment system and a normal pressure gas ammonia absorption system; The ammonia-containing tail gas pretreatment system comprises a high-pressure buffer tank (1), a low-pressure buffer tank (15), and an ammonia condenser (8); the high-pressure buffer tank (1) is provided with a plurality of connection ends connected to ammonia sources of high-pressure ammonia-containing tail gases of an ultra-pure ammonia production system, one of the connection ends being connected to a tube-side gas inlet end of an ammonia condenser (8) via a high-pressure buffer tank evaporation gas ammonia pipeline (7), and a tube-side liquid outlet end of the ammonia condenser (8) being connected to a connection end of the high-pressure buffer tank (1) via a condensate ammonia return pipeline (11); The low-pressure buffer tank (15) is provided with a connection end connected to each low-pressure ammonia-containing tail gas ammonia source of the ultra-pure ammonia production system, one of the connection ends is connected to the pipe-side gas outlet end of the ammonia condenser (8) through the ammonia condenser gas ammonia to low-pressure buffer tank pipeline (14), and the low-pressure buffer tank gas ammonia (22) is transported to the atmospheric pressure gas ammonia absorption system for absorption treatment; The overpressure gaseous ammonia (13) produced by the high-pressure buffer tank (1) and the low-pressure buffer tank (15) is discharged to an ultrapure ammonia production system or a combined alkali production system as a gaseous ammonia raw material for emergency use, and the liquid ammonia (12) produced by the high-pressure buffer tank (1) and the low-pressure buffer tank (15) is transported to an external cooler of the combined alkali crystallization process as a refrigerant for heat exchange.

2. The ammonia-containing tail gas treatment system for ultrapure ammonia production according to claim 1, characterized in that: The atmospheric pressure gas ammonia absorption system comprises a jet ammonia absorber (26), an ammonia induced draft fan (23), an ammonia II distribution tank (28) and at least one ammonia II clarification tank; The liquid inlet end of the jet ammonia absorber (26) is connected to the mother II delivery pipeline (25) and receives the mother II liquid, and the gas inlet end of the jet ammonia absorber (26) is connected to the ammonia induced draft fan (23) and receives the gas ammonia (22) from the low-pressure buffer tank; The liquid outlet end of the jet ammonia absorber (26) is connected to the ammonia II distribution tank (28) through a delivery pipeline, and the liquid outlet end of the ammonia II distribution tank (28) is connected to the ammonia II clarification tank through a delivery pipeline.

3. The ammonia-containing tail gas treatment system for ultrapure ammonia production according to claim 2, characterized in that: The atmospheric pressure gas ammonia absorption system comprises a first ammonia II clarification tank (29) and a second ammonia II clarification tank (31), wherein the liquid inlet end of the first ammonia II clarification tank (29) is connected to the liquid outlet end of the ammonia II distribution tank (28), the liquid inlet end of the first ammonia II clarification tank (29) is connected to the liquid inlet end of the second ammonia II clarification tank (31) through an overflow pipe (30), and the liquid outlet end of the second ammonia II clarification tank (31) is connected to the ammonia II carbon filtration process pipeline (32).

4. The ammonia-containing tail gas treatment system for ultrapure ammonia production according to claim 2, characterized in that: The delivery pipeline from the ammonia induced draft fan (23) to the jet ammonia absorber (26) is also connected to the ammonia source pipeline (24) of the crystallization process external cooling system.

5. A method for treating ammonia-containing tail gas in an ultrapure ammonia production system, characterized in that: Using the processing system according to any one of claims 1 to 4, the processing method comprises: Step 1: The ammonia source producing high-pressure ammonia-containing tail gas in the ultra-pure ammonia production system is transported to the high-pressure buffer tank (1) through a corresponding transport pipeline, and the ammonia source producing low-pressure ammonia-containing tail gas in the ultra-pure ammonia production system is transported to the low-pressure buffer tank (15) through a corresponding transport pipeline to separate the ammonia; Step 2: The evaporated gas ammonia in the high-pressure buffer tank (1) is transported to the ammonia condenser (8). The condensed liquid ammonia generated after cooling by the refrigerant is returned to the high-pressure buffer tank (1) through the condensed liquid ammonia return pipe (11). The ammonia condenser gas ammonia generated after the ammonia condenser (8) is depressurized is transported to the low-pressure buffer tank (15) through the ammonia condenser gas ammonia to low-pressure buffer tank pipe (14) for ammonia separation; Step 3: the liquid ammonia (12) separated and produced by the high-pressure buffer tank (1) and the low-pressure buffer tank (15) is pumped to the external cooler of the crystallization process of the alkali plant as a refrigerant for the crystallization system; Step 4: The atmospheric low-pressure buffer tank gas ammonia (22) produced by the low-pressure buffer tank (15) is pressurized by the ammonia induced draft fan (23) and then enters the jet ammonia absorber (26) to react with the mother II liquid to form ammonia II liquid. The ammonia II liquid flows through the ammonia II distribution tank (28), the first ammonia II clarification tank (29), the overflow pipe (30) and the second ammonia II clarification tank (31) in sequence and is transported to the carbon filtration system through the ammonia II carbon filtration process pipeline (32).

6. The method for treating ammonia-containing tail gas in an ultrapure ammonia production system according to claim 5, characterized in that: In step 4, the gaseous ammonia produced by the external cooling system of the crystallization process enters the jet ammonia absorber (26) together with the gaseous ammonia (22) of the low-pressure buffer tank through the gaseous ammonia source pipeline (24) of the external cooling system of the crystallization process to perform an ammonia absorption reaction.

7. The method for treating ammonia-containing tail gas in an ultrapure ammonia production system according to claim 5, characterized in that: In step 1, the ammonia source of the high-pressure ammonia-containing tail gas includes one or more of a high boiling tower receiving tank ammonia source (2), a low boiling tower receiving tank ammonia source (3), a high boiling tower ammonia source (4), a low boiling tower ammonia source (5), and a low boiling tower condenser ammonia source (6).

8. The method for treating ammonia-containing tail gas in an ultrapure ammonia production system according to claim 5, characterized in that: In step 1, the low-pressure ammonia-containing tail gas ammonia source includes one or more of a safety valve ammonia source (16), an ammonia buffer tank discharge ammonia source (17), a cylinder tail gas ammonia source (18), an ammonia recovery tank ammonia source (19), a workshop online analysis tail gas ammonia source (20), and a tank area online analysis tail gas ammonia source (21).

9. The method for treating ammonia-containing tail gas in an ultrapure ammonia production system according to claim 5, characterized in that: In step 4, the pressure of the low-pressure buffer tank gas ammonia (22) is raised by the ammonia induced draft fan (23) to a pressure of 0.3-0.5 MPa.

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