A flare gas ammonia recovery enrichment system

Abstract

The utility model discloses a kind of ammonia recovery enrichment systems of bleeder gas, in view of the problems of low ammonia recovery rate of traditional system, unstable operation, high energy consumption and big security risk, the system includes ammonia absorption two towers, high-pressure sealing water system, circulating system etc.;Ammonia absorption two towers are two-stage design and top is provided with wire mesh demister, circulating system contains one open one spare circulating pump, concentration accurate control is realized by matching online ammonia water concentration detector, safety valve is provided at key node to ensure operation safety, finally improve ammonia recovery rate and stabilize product concentration. The system can improve ammonia recovery rate, stabilize the 20% concentration ammonia water made, reduce energy consumption and safety environmental protection risk, ensure continuous operation, applicable to industrial bleeder gas ammonia recovery scene.

Description

Technical Field

[0001] This utility model relates to the field of ammonia recovery technology in chemical production, and in particular to a system for recovering and concentrating ammonia from purge gas. Background Technology

[0002] In industrial fields such as synthetic ammonia and fertilizer production, purge gas is a mixture of gases that needs to be discharged to maintain the inert gas balance of the system. If the ammonia contained in it (usually <5%) is directly discharged or burned, it will not only waste resources, but also pollute the environment due to the irritation and corrosiveness of ammonia, which does not meet environmental protection requirements. Effectively recovering and concentrating ammonia can reduce costs and pollution, thus achieving both economic and environmental benefits.

[0003] Currently, the mainstream industrial technology for recovering ammonia from purge gas is the absorption method, which utilizes the water-soluble properties of ammonia to achieve gas-liquid mass transfer and produce ammonia water through an absorption tower. However, existing absorption systems have significant shortcomings in practical applications and cannot meet the demands for efficient and stable production. 1. Traditional absorption towers are mostly single-stage structures, and the released gas is prone to "deviation", resulting in insufficient gas-liquid contact and some ammonia escaping directly; in addition, there is a lack of effective gas-liquid separation devices, and the mist droplets are emitted with the exhaust gas, which further causes ammonia loss; 2. Most circulating pumps are single-pump designs, and they will stop immediately if they fail; the liquid level in the absorption tower is monitored only by local instruments, without remote alarms, and is prone to imbalance due to liquid level fluctuations; the ammonia concentration cannot be detected in real time, resulting in unstable product quality. 3. To improve the recovery rate, conventional absorption methods require multi-stage circulation, resulting in high heat exchange load and high energy consumption; although technologies such as cryogenic separation can achieve high-purity recovery, the investment and energy consumption are extremely high, and the applicability is limited. 4. Key nodes lack adequate protection, such as the lack of precise control over the pressure at the top of the absorption tower and the lack of reliable overpressure protection for heat exchange equipment, which can easily lead to safety risks due to imbalance in operating conditions. Summary of the Invention

[0004] Given the technical problems existing in the background technology, current purge gas ammonia recovery technologies still have many shortcomings in terms of absorption efficiency, operational stability, energy consumption control, and safety assurance. There is an urgent need to develop a structurally optimized, precisely controlled, highly efficient, low-consumption, safe, and reliable ammonia recovery and concentration system to overcome the deficiencies of existing technologies and meet the increasingly stringent requirements of industrial production for resource recovery and environmental compliance. To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A purge gas ammonia recovery and concentration system includes an ammonia absorption tower 2, a high-pressure sealing water system and an ammonia station purge gas system. The high-pressure sealing water output from the high-pressure sealing water system is connected to the ammonia absorption tower 1 through a pipeline and to the ammonia absorption tower 2 through another pipeline. The dilute ammonia water output from the ammonia absorption tower 1 is connected to the ammonia absorption tower 2 through one pipeline and to the ammonia water storage tank through another pipeline. The ammonia vent gas output from the ammonia station vent gas system is combined with the liquid discharge from the low-pressure ammonia separator, and then connected to the ammonia absorption tower 2 through one pipeline and to the ammonia flare through another pipeline. The ammonia water discharged from the bottom outlet of the second ammonia absorption tower is connected to the circulation system through a pipeline. The output end of the circulation system is connected to the heat exchange system. The output end of the heat exchange system is connected to the second ammonia absorption tower through one pipeline and to the ammonia water storage tank through another pipeline. The gas phase output from the top outlet of the ammonia absorption tower merges with the liquid discharge from the liquid ammonia receiving tank and is then discharged into the ammonia flare. The liquid phase outlet of the liquid ammonia receiving tank is connected to the ammonia heater through a pipeline.

[0005] In the preferred embodiment, the ammonia absorption tower is a two-section design, with the upper and lower sections being cylindrical structures that are connected vertically. The upper section of the ammonia absorption tower is filled with an upper packing layer, and the lower section is filled with a lower packing layer. A wire mesh demister is installed at the outlet inside the top end cap of the ammonia absorption tower.

[0006] In the preferred embodiment, the bottom liquid accumulation section of the ammonia absorption tower is equipped with a local level gauge and a remote level gauge. The remote level gauge is equipped with upper and lower limit alarm functions and is connected to the remote control center.

[0007] In a preferred embodiment, the circulation system is located between the bottom outlet of the ammonia absorption tower and the heat exchange system. The circulation system includes a first circulation pump and a second circulation pump. The first circulation pump and the second circulation pump are connected in parallel, and the working state is one on and one on standby.

[0008] In a preferred embodiment, the heat exchange system includes an ammonia water cooler; the inlet of the ammonia water cooler is connected to the circulating water supply pipe, and the outlet of the ammonia water cooler is connected to the circulating water return pipe; the circulating water supply pipe and the circulating water return pipe are respectively connected to the circulating water system; a safety valve is installed on the ammonia water cooler.

[0009] In the preferred embodiment, a flow regulating valve is installed on the connecting pipe between the high-pressure sealing water system and the ammonia absorption tower 1; a remote control valve is installed on the connecting pipe between the high-pressure sealing water system and the ammonia absorption tower 2.

[0010] In the preferred embodiment, a pressure control valve and a safety valve are installed on the connecting pipe from the top gas phase outlet of the ammonia absorption tower to the point where the gas phase and the liquid ammonia receiving tank merge.

[0011] In the preferred embodiment, a control valve is installed on both the pipeline leading from the ammonia absorption tower to the ammonia absorption tower 2 and the pipeline leading to the ammonia water storage tank; a venting pressure control valve is installed on the venting gas system and the draining confluence pipeline of the low-pressure ammonia separator, and the venting pressure control valve is equipped with a flow meter and a pressure remote transmission meter.

[0012] In the preferred embodiment, an ammonia concentration detector is installed on the connecting pipe between the bottom outlet of the ammonia absorption tower and the circulation system.

[0013] In the preferred embodiment, a two-tower liquid level control valve is installed on the connecting pipeline between the heat exchange system and the ammonia storage tank.

[0014] A purge gas ammonia recovery and concentration system, which achieves the following beneficial effects in practical use: 1. This system adopts a two-stage ammonia absorption tower design, combined with a top wire mesh demister, which prolongs the contact time between the purge gas and the absorbent liquid and prevents ammonia from escaping with the droplets. The ammonia recovery rate is significantly improved compared with the traditional system, and it can stably produce 20% concentration ammonia water, completely solving the problem of ammonia waste caused by direct discharge of purge gas into the flare. 2. The ammonia water circulation pump adopts a one-on-one standby design to avoid shutdown due to single pump failure; equipped with an online ammonia water concentration detector and remote liquid level gauge alarm function, process parameters can be dynamically adjusted to ensure stable finished ammonia water concentration, solving the problems of concentration fluctuation and reliance on manual sampling in traditional systems; 3. Optimize heat exchange through ammonia water cooler to prevent ammonia escape while recovering heat and reducing system energy consumption; reduce ammonia flare combustion, saving flare maintenance and fuel costs, as well as environmental treatment costs, thus reducing the company's overall operating costs. 4. Safety valves are installed at key points such as the top of the ammonia absorption tower and the ammonia water cooler to prevent overpressure risks; priority is given to recovering ammonia rather than direct combustion to reduce harmful gas emissions, extend the service life of the ammonia flare, and ensure safety. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a diagram showing the overall material flow of the system in this utility model. Figure 2 This is a detailed connection diagram of the circulation system and heat exchange system of this utility model; Figure 3 This is an enlarged view of the internal structure of the ammonia absorption tower of this utility model.

[0016] In the diagram: 1. High-pressure sealing water system; 2. Flow regulating valve; 3. Ammonia absorption tower 1; 4. Remote control valve; 5. Tower 2 pressure control valve; 6. Ammonia flare; 7. Liquid ammonia receiving tank; 8. Ammonia heater; 9. Ammonia absorption tower 2; 9. Wire mesh demister; 9-1. Upper packing layer; 9-2. Lower packing layer; 9-3. Remote level gauge; 9-4. Local level gauge; 9-5. Ammonia water cooler; 10. Dilute ammonia water; 11. Tower 1 control valve; 12. Circulating water return pipe; 13. Circulating water supply pipe; 14. Ammonia station venting system; 15. Low-pressure ammonia separator; 16. Venting pressure control valve; 17. First circulation pump; 18. Second circulation pump; 19. Ammonia water concentration detector; 20. Tower 2 level control valve; 21. Ammonia water storage tank; 22. Detailed Implementation

[0017] like Figure 1 As shown, a purge gas ammonia recovery and concentration system includes an ammonia absorption tower 9, a high-pressure sealing water system 1, and an ammonia station purge gas system 15. The high-pressure sealing water system 1 outputs high-pressure sealing water at a pressure of 0.8-1.0 MPaG. This high-pressure sealing water is connected to an ammonia absorption tower 3 with a diameter of φ300 mm via a pipeline. The ammonia absorption tower 3 is filled with φ50 mm ceramic packing material with a height of 2500 mm to ensure the initial absorption effect of low-pressure purge gas. Simultaneously, the high-pressure sealing water is connected to the ammonia absorption tower 9 via another pipeline. After the high-pressure sealing water in the ammonia absorption tower 3 comes into contact with a small amount of purge gas, it outputs dilute ammonia water 11 with a concentration of 5%-8%. This dilute ammonia water 11 is connected to the ammonia absorption tower 9 via one pipeline for further concentration and is also connected to a 100 m³ atmospheric pressure ammonia water storage tank 22 for temporary storage via another pipeline. The ammonia station venting system 15 outputs ammonia venting gas with an output pressure of 0.7-0.9 MPaG and an ammonia volume fraction of 3%-5%. This venting gas is combined with the discharge from the low-pressure ammonia separator 16. The low-pressure ammonia separator 16 is used to separate the liquid ammonia entrained in the venting gas, and the separation pressure is controlled at 0.6-0.8 MPaG. The combined medium is connected to the ammonia absorption tower 9 through one pipeline and to the ammonia flare 6 through another pipeline. A flame arrester is installed at the inlet of the ammonia flare 6 to prevent the risk of backfire. The bottom outlet of ammonia absorption tower 9 discharges ammonia water with an initial concentration of 8%-12%. This ammonia water is connected to a circulation system via a pipeline. The output of the circulation system is connected to a heat exchange system, which cools the ammonia water to 35-40℃ to prevent ammonia volatilization loss. The output of the heat exchange system is connected to ammonia absorption tower 9 via one pipeline for secondary absorption and to ammonia water storage tank 22 via another pipeline. The top outlet of ammonia absorption tower 9 outputs a gas phase (mainly inert gas) with an ammonia volume fraction of <0.1%. This gas phase is combined with the discharge (containing a small amount of liquid ammonia) from liquid ammonia receiving tank 7 and then discharged into ammonia flare 6 for combustion treatment. The operating pressure of liquid ammonia receiving tank 7 is 0.5-0.7 MPaG. The liquid ammonia output from its liquid phase outlet is connected to an ammonia heater 8 with a heat exchange area of ​​15㎡ via a pipeline. The heating medium of ammonia heater 8 is saturated steam with a heat exchange area of ​​0.3 MPaG. After being heated to 40-45℃ and vaporized, the liquid ammonia is sent to subsequent processes.

[0018] Preferred solutions include Figure 3 As shown, the ammonia absorption tower 9 is a two-section cylindrical structure, with the upper and lower sections interconnected. The upper tower has a diameter of φ219mm, and the lower tower has a diameter of φ500mm. The upper section of the ammonia absorption tower 9 is filled with a 3500mm high upper packing layer 9-2, using φ25mm stainless steel Pall rings, which are resistant to ammonia corrosion and improve gas-liquid mass transfer accuracy. The lower section is filled with a 5000mm high lower packing layer 9-3, using φ38mm stainless steel stepped rings, further increasing the gas-liquid contact area to improve mass transfer efficiency. A 100-120 mesh stainless steel wire mesh demister 9-1 is installed at the outlet of the top end cap of the ammonia absorption tower 9 to trap ammonia droplets entrained in the gas phase, preventing ammonia escape and loss.

[0019] Preferred solutions include Figure 3 As shown, the effective volume of the bottom liquid accumulation section of ammonia absorption tower 9 is 0.5 m³. This liquid accumulation section is equipped with a glass tube local level gauge 9-5 and a differential pressure remote level gauge 9-4. The glass tube local level gauge 9-5 has a measurement range of 0-1000 mm, facilitating on-site inspection personnel to visually observe liquid level changes. The differential pressure remote level gauge 9-4 has a measurement accuracy of ±1 mm, enabling precise liquid level monitoring. The remote level gauge 9-4 is equipped with upper and lower limit alarm functions, with the high limit alarm value set at 840 mm and the low limit alarm value set at 300 mm. The remote level gauge 9-4 is connected to the remote DCS control center. When the liquid level reaches the high limit, the control center automatically triggers the ammonia absorption tower 9 to decrease the opening of the valve; when the liquid level reaches the low limit, it automatically triggers the opening of the valve to increase the opening. Through automatic liquid level adjustment, the liquid accumulation in the tower can be stabilized, avoiding problems such as dry tower or overflow.

[0020] Preferred solutions include Figure 2As shown, the circulation system is located between the bottom outlet of the ammonia absorption tower 9 and the heat exchange system. This circulation system includes a first circulation pump 18 and a second circulation pump 19. Both the first circulation pump 18 and the second circulation pump 19 are model IHF50-32-160, made of 316L stainless steel to withstand ammonia corrosion. The two pumps are connected in parallel, with one operating and the other on standby. Each pump has a design flow rate of 50-80 m³ / h and a head of 30-40 m, suitable for the ammonia circulation requirements within the tower. The circulation pumps are equipped with double-end mechanical seals, using demineralized water as the sealing fluid with a pressure control of 0.2 MPaG, effectively preventing ammonia leakage. When the outlet pressure of the operating circulation pump drops below 25 m or the current fluctuates abnormally, the remote control center automatically triggers the standby pump to start, while simultaneously closing the inlet and outlet valves of the faulty pump. The switching time is less than 10 seconds. This rapid automatic switching avoids circulation interruptions and ensures continuous ammonia absorption.

[0021] Preferred solutions include Figure 2 As shown, the heat exchange system includes an ammonia water cooler 10, which has dimensions of φ400×2000mm and a heat exchange area of ​​20㎡. The tube side of the ammonia water cooler 10 is made of 316L stainless steel, which is resistant to ammonia corrosion; the shell side is made of Q235-B, which reduces manufacturing costs while ensuring equipment strength. The heat exchange end inlet of the ammonia water cooler 10 is connected to the circulating water supply pipe 14, and the heat exchange end outlet is connected to the circulating water return pipe 13. The circulating water temperature in the circulating water supply pipe 14 is 32-35℃, and the circulating water temperature in the circulating water return pipe 13 is 38-42℃. Both the circulating water supply pipe 14 and the circulating water return pipe 13 are connected to the plant's circulating water system, and the plant's circulating water pressure is controlled at 0.4-0.6MPaG. Through circulating water heat exchange, the ammonia water can be cooled to 35-40℃, effectively suppressing ammonia volatilization loss. A spring-loaded safety valve is installed at the top of the shell side of the ammonia cooler. The safety valve model is A42Y-16C, and the set pressure is 0.8MPaG. When the shell side pressure exceeds the limit, the safety valve will automatically open to release pressure and prevent ammonia leakage caused by tube rupture.

[0022] Preferred solutions include Figure 2 As shown, a flow regulating valve 2 is installed on the connecting pipe between the high-pressure sealing water system 1 and the ammonia absorption tower 3. The flow regulating valve 2 is a pneumatic diaphragm type, model ZJHP-16C, with a nominal diameter of DN50 and an adjustment range of 10-50 m³ / h. This flow regulating valve can automatically adjust its opening according to the liquid level at the bottom of the ammonia absorption tower 3 (set value 500 mm) to ensure a stable supply of sealing water required for initial absorption. A remote control valve 4 is installed on the connecting pipe between the high-pressure sealing water system 1 and the ammonia absorption tower 9. The remote control valve 4 is an electric type, model Z941H-16C, with a nominal diameter of DN40. This remote control valve can remotely adjust its opening according to the gaseous ammonia concentration at the top of the ammonia absorption tower 9 (set value <0.1%), thereby improving ammonia absorption efficiency by replenishing sealing water.

[0023] Preferred solutions include Figure 2 As shown, a pressure control valve 5 and a spring-loaded safety valve are installed on the connecting pipe from the top gas phase outlet of the ammonia absorption tower 9 to the point where the gas phase and liquid ammonia receiving tank 7 merge. The pressure control valve 5 is a pneumatic diaphragm type, model ZJHP-16C, with a nominal diameter of DN80 and a set pressure of 0.6MPaG. It automatically opens to release pressure when the pressure inside the ammonia absorption tower 9 exceeds 0.65MPaG. The safety valve is model A42Y-16C, with a set pressure of 1.2MPaG. If the pressure inside the tower continues to rise to 1.2MPaG, the safety valve will open to release pressure and prevent damage to the tower due to overpressure.

[0024] Preferred solutions include Figure 2 As shown, a control valve 12 is installed on both the pipeline connecting ammonia absorption tower 3 to ammonia absorption tower 9 and the pipeline connecting to ammonia storage tank 22. The control valve 12 is made of cast steel, model J41H-16C, with a nominal diameter of DN50. This valve is adjusted according to the concentration of dilute ammonia solution 11: when the concentration is <5%, the valve to ammonia storage tank 22 is closed, and the valve to ammonia absorption tower 9 is fully opened to ensure sufficient concentration of the dilute ammonia solution; when the concentration is >8%, the valve to ammonia storage tank 22 is partially opened to divert the dilute ammonia solution, preventing excessively high concentrations from affecting subsequent absorption. A venting pressure control valve 17 is installed on the drain merging pipeline between the ammonia station venting system 15 and the low-pressure ammonia separator 16. The venting pressure control valve 17 is a pneumatic diaphragm type, model ZJHP-16C, with a nominal diameter of DN100 and a set pressure of 0.7 MPaG. A vortex flow meter and a pressure remote transmission meter are installed on the venting pressure control valve 17. The flow meter has a range of 0-500 Nm³ / h and an accuracy of ±1.5%, while the pressure remote transmission meter has a range of 0-1.0 MPaG and an accuracy of ±0.2%. The real-time data from the flow meter and pressure remote transmission meter allows for adjustment of the venting gas intake, preventing fluctuations in the intake volume from impacting the ammonia absorption tower 9 and ensuring stable absorption conditions.

[0025] Preferred solutions include Figure 2 As shown, an ammonia concentration detector 20 is installed on the connecting pipe between the bottom outlet of the ammonia absorption tower 9 and the circulation system. The ammonia concentration detector 20 is an online refractive type, model ATAGO PRM-100α, with a detection range of 0-30% and an accuracy of ±0.5%. This detector collects ammonia concentration data in real time and transmits it to a remote control center: when the concentration is <20%, the valve at the output end of the heat exchange system leading to the ammonia absorption tower 9 is fully opened, and the valve leading to the ammonia storage tank 22 is closed, so that the ammonia continues to circulate and concentrate; when the concentration reaches 20%±0.5%, the valve leading to the ammonia storage tank 22 is opened to collect the finished ammonia, ensuring the stability of the finished product concentration.

[0026] Preferred solutions include Figure 2 As shown, a second-tower level control valve 21 is installed on the connecting pipe between the heat exchange system and the ammonia storage tank 22. The second-tower level control valve 21 is a pneumatic diaphragm type, model ZMBQ-16, with a nominal diameter of DN65. The valve adjusts its opening based on real-time data from the remote level gauge 9-4 at the bottom of the ammonia absorption tower 9: when the liquid level is higher than 700mm, the valve opens wider to increase the discharge rate to the ammonia storage tank 22; when the liquid level is lower than 400mm, the valve closes less to reduce the discharge rate. By adjusting the liquid level, the valve maintains a stable liquid level in the tower, ensuring a continuous and efficient absorption process.

[0027] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A purge gas ammonia recovery and concentration system, comprising an ammonia absorption tower (9), a high-pressure sealing water system (1), and an ammonia station purge gas system (15), characterized in that: The high-pressure sealing water output by the high-pressure sealing water system (1) is connected to the ammonia absorption tower (3) through one pipe and to the ammonia absorption tower (9) through another pipe. The dilute ammonia water (11) output from the ammonia absorption tower (3) is connected to the ammonia absorption tower (9) through a pipe and to the ammonia water storage tank (22) through another pipe. After the ammonia station vent gas output from the ammonia station vent gas system (15) merges with the liquid discharge from the low-pressure ammonia separator (16), it is connected to the ammonia absorption tower (9) through one pipeline and to the ammonia flare (6) through another pipeline. The ammonia water discharged from the bottom outlet of the ammonia absorption tower (9) is connected to the circulation system through a pipeline. The output end of the circulation system is connected to the heat exchange system. The output end of the heat exchange system is connected to the ammonia absorption tower (9) through one pipeline and to the ammonia water storage tank (22) through another pipeline. The gas phase output from the top outlet of the ammonia absorption tower (9) merges with the liquid discharge from the liquid ammonia receiving tank (7) and is discharged into the ammonia torch (6). The liquid phase outlet of the liquid ammonia receiving tank (7) is connected to the ammonia heater (8) through a pipeline.

2. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: The ammonia absorption tower (9) is a two-section design, with the upper and lower sections being cylindrical structures and connected vertically. The upper section of the ammonia absorption tower (9) is filled with an upper packing layer (9-2), and the lower section is filled with a lower packing layer (9-3). A wire mesh demister (9-1) is installed at the outlet of the top end cap of the ammonia absorption tower (9).

3. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: The bottom liquid accumulation section of the ammonia absorption tower (9) is equipped with a local liquid level gauge (9-5) and a remote liquid level gauge (9-4). The remote liquid level gauge (9-4) is equipped with upper and lower limit alarm functions and is connected to the remote control center signal.

4. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: The circulation system is located between the liquid outlet at the bottom of the ammonia absorption tower (9) and the heat exchange system. The circulation system includes a first circulation pump (18) and a second circulation pump (19). The first circulation pump (18) and the second circulation pump (19) are connected in parallel and operate in a one-on-one standby mode.

5. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: The heat exchange system includes an ammonia water cooler (10); the heat exchange end inlet of the ammonia water cooler (10) is connected to the circulating water supply pipe (14), and the heat exchange end outlet is connected to the circulating water return pipe (13); the circulating water supply pipe (14) and the circulating water return pipe (13) are respectively connected to the circulating water system; a safety valve is installed on the ammonia water cooler (10).

6. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: A flow regulating valve (2) is installed on the connecting pipe between the high-pressure sealing water system (1) and the ammonia absorption tower (3); a remote control valve (4) is installed on the connecting pipe between the high-pressure sealing water system (1) and the ammonia absorption tower (9).

7. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: A pressure control valve (5) and a safety valve are installed on the connecting pipe from the top gas phase outlet of the ammonia absorption tower (9) to the point where the gas phase and liquid ammonia receiving tank (7) merge.

8. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: A tower control valve (12) is installed on the pipeline from the ammonia absorption tower (3) to the ammonia absorption tower (9) and on the pipeline to the ammonia water storage tank (22); a venting pressure control valve (17) is installed on the venting gas system (15) and the draining pipe of the low-pressure ammonia separator (16), and a flow meter and a pressure remote transmission meter are installed on the venting pressure control valve (17).

9. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: An ammonia concentration detector (20) is installed on the connecting pipe between the bottom outlet of the ammonia absorption tower (9) and the circulation system.

10. The ammonia recovery and concentration system for purge gas according to claim 1, characterized in that: A two-tower liquid level control valve (21) is installed on the connecting pipe between the heat exchange system and the ammonia water storage tank (22).

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