Experimental device for cyclic absorption and desorption of ammonia-containing mixed gas and ammonia separation method

Abstract

The invention discloses an experimental device for cyclic absorption and desorption of ammonia-containing mixed gas and an ammonia separation method.The device comprises an absorption tower system, a desorption tower system, an absorbent configuration system, a vacuum system, an analysis system and a control system, and the absorption-desorption performance of an absorbent can be evaluated by regulating and controlling parameters such as pressure, temperature and flow. The absorption tower system adopts a sleeve type structure and is provided with a preheater, and the desorption tower system realizes ammonia gas separation under a vacuum condition; the absorbent configuration system is suitable for absorbents with different viscosities, and the vacuum system is used for recovering high-purity ammonia gas. The ammonia separation method comprises the following steps: the ammonia-containing mixed gas is in countercurrent contact with the eutectic solvent in the absorption tower, and the rich solution is subjected to vacuum desorption by the desorption tower to be regenerated into the barren solution for recycling. The problems that a traditional solvent absorption method is irreversible and high in corrosivity are solved, efficient separation and recycling of low-concentration ammonia are achieved, and the net value and yield of ammonia synthesis reaction are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonia separation, and particularly relates to an experimental device for cyclic absorption and desorption of ammonia-containing mixed gas and an ammonia separation method, aiming to solve the problems of low-concentration ammonia separation and absorbent performance evaluation in the process of ammonia synthesis. Background Art

[0002] In the ammonia synthesis industry, ammonia separation technology is crucial. At present, the physical condensation method is a commonly used NH 3 separation means in ammonia synthesis plants. However, restricted by the liquid ammonia vapor-liquid equilibrium, about 3% of NH 3 will still remain in the recycle gas. This part of the residual ammonia not only causes waste of ammonia products, increases the system recycle volume, but also hinders the forward progress of the ammonia synthesis reaction due to the influence of equilibrium conversion.

[0003] In addition to the physical condensation method, solvent absorption methods such as water washing and acid washing are also relatively common. However, water has high volatility, and the recycle gas is easily entrained with water, resulting in poisoning of the ammonia synthesis catalyst; under high pressure, the recycle gas will also dissolve in water, causing loss of the recycle gas. Although inorganic strong acids can absorb ammonia, they have strong corrosiveness and undergo irreversible reactions with NH 3 , and the absorbed NH 3 cannot be desorbed, making it difficult to meet the separation requirements of low-concentration NH 3 in the recycle gas during the ammonia synthesis process.

[0004] At the same time, the existing ammonia synthesis separation devices cannot flexibly adjust process parameters such as pressure, temperature, inlet gas volume, inlet liquid volume, and recycle volume, making it difficult to comprehensively evaluate the absorption and desorption effects of absorbents under different working conditions, severely restricting the research and development and performance evaluation of new absorbents, and being unfavorable to the efficient development of the ammonia synthesis industry. Summary of the Invention

[0005] The present invention aims to solve the technical problem that the existing ammonia synthesis separation devices cannot meet the performance evaluation of low-concentration NH3 absorbents, and provides an experimental device for cyclic absorption and desorption of ammonia-containing mixed gas and a corresponding separation method, which are used to evaluate the absorption and desorption effects of absorbents under different working conditions, and further screen out new and efficient absorbents. At the same time, a method for absorption, desorption, and separation of low-concentration NH3 in the recycle gas is provided to increase the ammonia net value of the ammonia synthesis reaction and the ammonia production of the ammonia synthesis plant.

[0006] The present invention adopts the following technical solutions:

[0007] An experimental device for cyclic absorption and desorption of ammonia-containing mixed gas, comprising: an absorption tower system, a desorption tower system, an absorbent preparation system, a vacuum system, and an analysis system;

[0008] The absorption tower system includes a mass flowmeter, a gas preheater, an absorption tower, and a first liquid inlet preheater. The structure of the absorption tower from bottom to top is sequentially an absorption tower bottom kettle, an absorption tower body, and an absorption tower condenser. The inlet of the mass flowmeter is connected to the recycle gas of an external synthetic ammonia plant, and the outlet is connected to the bottom of the absorption tower body through the gas preheater. A back pressure valve is provided between the outlet of the absorption tower condenser and the inlet of the recycle compressor of the external synthetic ammonia plant. The first liquid inlet preheater is connected to the top of the absorption tower body.

[0009] The stripping tower system includes a second liquid inlet preheater, a stripping tower, and a gas-liquid separator. The structure of the stripping tower from bottom to top is sequentially a stripping tower bottom kettle, a stripping tower body, and a stripping tower condenser. The inlet of the second liquid inlet preheater is connected to the absorption tower bottom kettle, and the outlet is connected to the top of the stripping tower body. The stripping tower condenser is connected to the gas-liquid separator, and the outlet of the gas-liquid separator is connected to a vacuum buffer tank.

[0010] The absorbent preparation system includes an absorbent storage tank, a first material pump group, a second material pump group, and a condenser. The inlet of the absorbent storage tank is connected to the outlet of the condenser, and the outlet is connected to the first liquid inlet preheater through the second material pump group. The inlet of the condenser is connected to the outlet of the stripping tower bottom kettle. The inlet of the first material pump group is connected to the outlet of the absorption tower bottom kettle, and its outlet is connected to the inlet of the second liquid inlet preheater.

[0011] The vacuum system includes a vacuum buffer tank, a vacuum pump, and a high-purity ammonia storage tank. The inlet of the vacuum buffer tank is connected to the gas-liquid separator, and the outlet is connected to the high-purity ammonia storage tank through the vacuum pump.

[0012] The analysis system includes a real-time ammonia analyzer, and the ammonia analyzer is respectively connected to the inlet and outlet of the absorption tower system.

[0013] Preferably, both the absorption tower body and the stripping tower body are of a double-pipe structure and are heated by a constant-temperature oil bath. A first solenoid valve, a first material pump group, and a first back pressure valve are sequentially connected in series between the absorption tower system and the stripping tower system. A first differential pressure transmitter is also provided between the absorption tower bottom kettle and the first solenoid valve. The differential pressure value transmitted by the first differential pressure transmitter is used to control the opening and closing of the first solenoid valve. One end of the first solenoid valve is connected to the absorption tower bottom kettle, and the other end is connected to the inlet of the second liquid inlet preheater through the first material pump group and the first back pressure valve. The first solenoid valve, the first differential pressure transmitter, and the first material pump group are linked and adjusted.

[0014] Preferably, stainless steel triangular spiral rings or mesh ring packings are installed inside both the absorption tower body (132) and the stripping tower body (222).

[0015] Preferably, a second solenoid valve and a second differential pressure transmitter are provided between the bottom of the stripping column and the condenser, and the differential pressure value transmitted by the second differential pressure transmitter is used to control the opening and closing of the second solenoid valve (25), thereby automatically adjusting the absorbent liquid level in the bottom of the stripping column.

[0016] Preferably, the first material pump group includes a first plunger metering pump and a first advection pump arranged in parallel, and the second material pump group includes a second plunger metering pump and a second advection pump arranged in parallel; wherein, the first plunger metering pump and the second plunger metering pump are used to transport absorbent with viscosity > 10 CP, and the first advection pump and the second advection pump are used to transport absorbent with viscosity ≤ 10 CP.

[0017] Preferably, the experimental device further includes a control system for the whole-process control and real-time monitoring of the temperature, pressure, differential pressure, absorbent flow rate and gas flow rate of the experimental device.

[0018] The ammonia analyzer continuously monitors the ammonia concentrations at the inlet and outlet of the absorption tower, and feeds the monitoring data back to the control system to optimize the operation parameters.

[0019] A method for ammonia separation using an experimental device for cyclic absorption and stripping of ammonia-containing mixed gas includes the following steps:

[0020] S1. After being metered by a mass flowmeter, the ammonia-containing mixed gas is heated by a gas preheater and enters the bottom of the absorption tower; the lean absorbent from the absorbent preparation system is metered by the second material pump group, heated by the first liquid inlet preheater and enters the top of the absorption tower, contacts the mixed gas countercurrently, absorbs ammonia to form rich liquid; the unabsorbed gas returns to the external synthetic ammonia device through the top condenser for continued use.

[0021] S2. After being regulated by the first solenoid valve, the first material pump group and the first back pressure valve, the rich liquid is heated by the second liquid inlet preheater and enters the top of the stripping column, ammonia is stripped under vacuum conditions, and enters the vacuum buffer tank through a gas-liquid separator, and then enters the high-purity ammonia storage tank through a vacuum pump; the stripped lean liquid enters the bottom of the stripping column by gravity, and then enters the absorbent storage tank through the second pressure solenoid valve and the condenser for recycling.

[0022] The absorbent is a deep eutectic solvent containing weakly acidic groups and hydrogen bond groups; the operating pressure of the absorption tower (13) is 0 - 15 MPa, and the temperature is room temperature - 80 °C; the operating pressure of the stripping column (22) is 2 - 3 kPa, and the temperature is room temperature - 120 °C.

[0023] The vacuum condition of the stripping column is maintained by a vacuum pump, and the vacuum buffer tank is used to stabilize the system pressure fluctuation.

[0024] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0025] A. The experimental device of the present invention can flexibly adjust the pressure, temperature, air inlet flow rate, liquid inlet flow rate and other parameters of the absorption tower and the desorption tower. By changing these process conditions, the absorption and desorption effects of the absorbent can be comprehensively and comprehensively evaluated. Based on this, high-efficiency absorbents can be quickly and accurately screened out, providing a scientific basis for the selection of absorbents in the synthetic ammonia process and promoting the development of absorbents towards high efficiency.

[0026] B. The present invention can conduct an in-depth study on the process parameters of the absorbent and simulate different working conditions to obtain rich data. These data build a bridge for the absorbent to move from the laboratory to industrial application, help optimize the use conditions of the absorbent in actual production, reduce technical barriers to industrial application, and accelerate the promotion of new absorbents.

[0027] C. Achieve efficient separation and recycling of low-concentration ammonia: The absorption and analytical separation method invented is used to separate low-concentration NH 3 , the separation effect is remarkable. On the one hand, low concentration NH 3 The efficient separation reduces the residual ammonia in the circulating gas; on the other hand, both the circulating gas and the absorbent can be recycled, which improves resource utilization, reduces raw material waste and reduces production costs.

[0028] D. The present invention uses a low eutectic solvent containing functional groups such as weakly acidic groups and hydrogen bonding groups as an absorbent, and cooperates with specific operating conditions of the absorption tower and the desorption tower to efficiently realize the cyclic absorption and desorption of low-concentration ammonia. This effectively improves the net ammonia value of the synthetic ammonia reaction, significantly increases the ammonia output of the synthetic ammonia device, and enhances the production efficiency and market competitiveness of the synthetic ammonia enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of the overall structure of the experimental device for circulating absorption and analysis of ammonia-containing mixed gas in the present invention.

[0031] The following are marked in the figure:

[0032] 1 - Absorption tower system, 11 - Mass flowmeter, 12 - Gas preheater, 13 - Absorption tower, 131 - Absorption tower bottom, 132 - Absorption tower body, 133 - Absorption tower condenser, 14 - First feed liquid preheater, 15 - First solenoid valve, 16 - First back pressure valve, 17 - First differential pressure transmitter;

[0033] 2 - Desorption tower system, 21 - Second feed liquid preheater, 22 - Desorption tower, 221 - Desorption tower bottom, 222 - Desorption tower body, 223 - Desorption tower condenser, 23 - Gas - liquid separator, 24 - Second solenoid valve, 25 - Second differential pressure transmitter;

[0034] 3 - Absorbent preparation system, 31 - Absorbent storage tank, 32 - First material pump group, 321 - First plunger metering pump, 322 - First advection pump, 33 - Second material pump group, 331 - Second plunger metering pump, 332 - Second advection pump, 34 - Condenser;

[0035] 4 - Vacuum system, 41 - Vacuum buffer tank, 42 - Vacuum pump, 43 - High - purity ammonia storage tank;

[0036] 5 - Analysis system, 51 - Ammonia analyzer. Detailed implementation manners

[0037] The present invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0038] Such as Figure 1As shown in the figure, this embodiment provides an experimental device for cyclic absorption and desorption of ammonia-containing mixed gas, including an absorption tower system 1, a desorption tower system 2, an absorbent preparation system 3, a vacuum system 4, an analysis system 5, and a control system. The absorption tower system 1 includes a mass flowmeter 11, a gas preheater 12, an absorption tower 13, and a first liquid inlet preheater 14. The structure of the absorption tower 13 from bottom to top is successively an absorption tower bottom kettle 131, an absorption tower body 132, and an absorption tower condenser 133. The inlet of the mass flowmeter 11 is connected to the recycle gas of an external synthetic ammonia plant, and the outlet is connected to the bottom of the absorption tower body 132 through the gas preheater 12. A back pressure valve is provided between the outlet of the absorption tower condenser 133 and the inlet of the recycle compressor of the external synthetic ammonia plant. The first liquid inlet preheater 14 is connected to the top of the absorption tower body 132. The desorption tower system 2 includes a second liquid inlet preheater 21, a desorption tower 22, and a gas-liquid separator 23. The structure of the desorption tower 22 from bottom to top is successively a desorption tower bottom kettle 221, a desorption tower body 222, and a desorption tower condenser 223. The inlet of the second liquid inlet preheater 21 is connected to the absorption tower bottom kettle 131, and the outlet is connected to the top of the desorption tower body 222. The desorption tower condenser 223 is connected to the gas-liquid separator 23, and the outlet of the gas-liquid separator 23 is connected to the vacuum buffer tank 41. The absorbent preparation system 3 includes an absorbent storage tank 31, a first material pump group 32, a second material pump group 33, and a condenser 34. The inlet of the absorbent storage tank 31 is connected to the outlet of the condenser 34, and the outlet is connected to the first liquid inlet preheater 14 through the second material pump group 33. The inlet of the condenser 34 is connected to the outlet of the desorption tower bottom kettle 221. The inlet of the first material pump group 32 is connected to the outlet of the absorption tower bottom kettle 131, and its outlet is connected to the inlet of the second liquid inlet preheater 21. The vacuum system 4 includes a vacuum buffer tank 41, a vacuum pump 42, and a high-purity ammonia storage tank 43. The inlet of the vacuum buffer tank 41 is connected to the gas-liquid separator 23, and the outlet is connected to the high-purity ammonia storage tank 43 through the vacuum pump 42. The analysis system 5 includes a real-time ammonia analyzer 51. The ammonia analyzer 51 is respectively connected to the inlet and outlet of the absorption tower system 1, and is used for continuously monitoring the ammonia concentration at the inlet and outlet of the absorption tower 13, and feeding back the monitoring data to the control system to optimize the operation parameters. The control system is used for the whole-process control and real-time monitoring of the temperature, pressure, pressure difference, absorbent flow rate, and gas flow rate of the experimental device.

[0039] Further, both the absorption tower body 132 and the stripping tower body 222 are of a casing structure and are heated by a constant-temperature oil bath. Both the absorption tower body 132 and the stripping tower body 222 are internally filled with stainless steel triangular spiral rings or wire mesh packing. A first solenoid valve 15, a first material pump group 32, and a first back pressure valve 16 are sequentially connected in series between the absorption tower system 1 and the stripping tower system 2. A first differential pressure transmitter 17 is further provided between the absorption tower bottom 131 and the first solenoid valve 15. The differential pressure value transmitted by the first differential pressure transmitter 17 is used to control the opening and closing of the first solenoid valve 15 (the first solenoid valve 15 can automatically open after the differential pressure transmitted by the first differential pressure transmitter 17 exceeds the set value, and the rich liquid enters the first material pump group 32); one end of the first solenoid valve 15 is connected to the absorption tower bottom 131, and the other end is connected to the inlet of the second liquid inlet preheater 21 through the first material pump group 32 and the first back pressure valve 16. A linkage adjustment is achieved among the first solenoid valve 15, the first differential pressure transmitter 17, and the first material pump group 32. A second solenoid valve 24 and a second differential pressure transmitter 25 are provided between the stripping tower bottom 221 and the condenser 34. The differential pressure value transmitted by the second differential pressure transmitter 25 is used to control the opening and closing of the second solenoid valve 24, thereby automatically adjusting the absorbent liquid level in the stripping tower bottom 221.

[0040] The first material pump group 32 includes a first plunger metering pump 321 and a first peristaltic pump 322 connected in parallel. The second material pump group 33 includes a second plunger metering pump 331 and a second peristaltic pump 332 connected in parallel; wherein, the first plunger metering pump 321 and the second plunger metering pump 331 are used to transport absorbent with a viscosity > 10 CP, and the first peristaltic pump 322 and the second peristaltic pump 332 are used to transport absorbent with a viscosity ≤ 10 CP.

[0041] This embodiment also provides a method for ammonia separation using an experimental device for cyclic absorption and stripping of ammonia-containing mixed gas, including the following steps:

[0042] S1. After being metered by the mass flowmeter 11, the ammonia-containing mixed gas is heated by the gas preheater 12 and enters the bottom of the absorption tower 13; the lean liquid of the absorbent from the absorbent preparation system 3 is metered by the second material pump group 33, heated by the first liquid inlet preheater 14 and enters the top of the absorption tower 13, where it contacts the mixed gas countercurrently to absorb ammonia and form rich liquid; the unabsorbed gas returns to the external ammonia synthesis device through the top condenser 133 for continued use;

[0043] After the rich liquid is regulated by the first solenoid valve 15, the first material pump group 32 and the first back-pressure valve 16, it is heated by the second liquid inlet preheater 21 and enters the top of the stripping tower 22. Ammonia gas is stripped under vacuum conditions, enters the vacuum buffer tank 41 through the gas-liquid separator 23, and then enters the high-purity ammonia storage tank 43 through the vacuum pump 42; the lean liquid after stripping enters the bottom of the stripping tower 221 by gravity, and then enters the absorbent storage tank 31 through the second solenoid valve 24 and the condenser 34 for recycling.

[0044] The absorbent is a deep eutectic solvent containing weakly acidic groups and hydrogen bond groups; the operating pressure of the absorption tower 13 is 0 - 15 MPa, and the temperature is room temperature - 80 °C; the operating pressure of the stripping tower 22 is 2 - 3 kPa, and the temperature is room temperature - 120 °C. The vacuum condition of the stripping tower 22 is maintained by the vacuum pump 42, and the vacuum buffer tank 41 is used to stabilize the system pressure fluctuation.

[0045] Application Example 1:

[0046] In this application example, a deep eutectic solvent containing weakly acidic groups and hydrogen bond groups (prepared from choline chloride and ethylene glycol in a molar ratio of 1:3) is used as the absorbent. The experimental device is connected and debugged as follows Figure 1 and the specific operation steps are as follows:

[0047] P1. Absorption stage:

[0048] The ammonia-containing mixed gas (ammonia concentration 3.5%, pressure 5 MPa, temperature 40 °C) is metered by the mass flowmeter 11, heated to 60 °C by the gas preheater 12, and enters the bottom of the absorption tower 13;

[0049] The lean absorbent liquid (viscosity 8 CP) is transported at a flow rate of 20 L / h by the second peristaltic pump 332, heated to 50 °C by the first liquid inlet preheater 14, and sprayed from the top of the absorption tower;

[0050] After the gas-liquid countercurrent contact, the rich liquid (ammonia loading 0.25 mol / L) enters the bottom of the absorption tower 131, and the unabsorbed gas returns to the synthetic ammonia plant through the back-pressure valve for recycling.

[0051] P2. Stripping stage:

[0052] The rich liquid is monitored for pressure difference by the first differential pressure transmitter 15 and transported to the top of the stripping tower 22 at a flow rate of 15 L / h by the first peristaltic pump 322;

[0053] The stripping tower 22 maintains a pressure of 2.5 kPa and a temperature of 90 °C under the action of the vacuum pump 42; after the ammonia gas is stripped, it enters the high-purity ammonia storage tank 43 through the gas-liquid separator 23, and the purity reaches 99.6%;

[0054] The lean liquid after stripping returns to the absorbent storage tank 31 for recycling. After 5 cycles, the ammonia absorption efficiency still remains at 98.2%.

[0055] Application Example 2:

[0056] This application example examines the influence of different viscosities of absorbents on the separation efficiency. Two absorbents are used:

[0057] Absorbent A: Choline chloride / urea eutectic solvent (viscosity 12 CP, weak acidic group content 15%).

[0058] Absorbent B: Choline chloride / glycerol eutectic solvent (viscosity 5 CP, weak acidic group content 10%).

[0059] The operating conditions are fixed as follows: the pressure in the absorption tower is 8 MPa and the temperature is 60 °C; the pressure in the stripping tower is 3 kPa and the temperature is 100 °C.

[0060] Experimental results:

[0061] The ammonia loading of Absorbent A is 0.28 mol / L, and the ammonia purity after stripping is 99.5%, but a plunger metering pump 321 is required for pumping.

[0062] The ammonia loading of Absorbent B is 0.22 mol / L, and the ammonia purity after stripping is 99.3%. A peristaltic pump 332 is used for pumping.

[0063] It shows that high-viscosity absorbents need to be matched with plunger pumps, and the higher the content of weak acidic groups, the stronger the ammonia absorption capacity.

[0064] Application Example 3:

[0065] This application example tests the separation performance of the device for low-concentration ammonia. The ammonia concentrations in the ammonia-containing mixed gas are 1%, 2%, and 3% respectively, and other conditions are the same as in Application Example 1.

[0066] Experimental results:

[0067] When the ammonia concentration is 1%, the absorption efficiency is 92.5%;

[0068] When the ammonia concentration is 2%, the absorption efficiency is 96.8%;

[0069] When the ammonia concentration is 3%, the absorption efficiency is 98.5%.

[0070] It shows that the device still has high separation ability for low-concentration ammonia (1% - 3%), and the absorption efficiency increases significantly with the increase of ammonia concentration.

[0071] The above application examples further verify the flexibility, high efficiency and repeatability of the device and method of the present invention, and provide a reliable experimental basis for absorbent screening and process optimization.

[0072] Matters not described in the present invention are applicable to the prior art.

[0073] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. An experimental device for circulating absorption and analysis of ammonia-containing mixed gas, characterized in that: include: Absorption tower system (1), analytical tower system (2), absorbent preparation system (3), vacuum system (4) and analysis system (5); The absorption tower system (1) comprises a mass flow meter (11), a gas preheater (12), an absorption tower (13) and a first liquid inlet preheater (14); the structure of the absorption tower (13) is, from bottom to top, an absorption tower kettle (131), an absorption tower body (132) and an absorption tower condenser (133); the inlet of the mass flow meter (11) is connected to the circulating gas of an external ammonia synthesis device, and the outlet is connected to the bottom of the absorption tower body (132) through the gas preheater (12); a back pressure valve is provided between the outlet of the absorption tower condenser (133) and the air inlet of the circulating compressor of the external ammonia synthesis device; the first liquid inlet preheater (14) is connected to the top of the absorption tower body (132); The analytical tower system (2) comprises a second liquid inlet preheater (21), an analytical tower (22) and a gas-liquid separator (23); the structure of the analytical tower (22) is, from bottom to top, a analytical tower kettle (221), a analytical tower body (222) and an analytical tower condenser (223); the inlet of the second liquid inlet preheater (21) is connected to the absorption tower kettle (131), and the outlet is connected to the top of the analytical tower body (222); the analytical tower condenser (223) is connected to the gas-liquid separator (23), and the outlet of the gas-liquid separator (23) is connected to a vacuum buffer tank (41); The absorbent configuration system (3) comprises an absorbent storage tank (31), a first material pump group (32), a second material pump group (33) and a condenser (34); the inlet of the absorbent storage tank (31) is connected to the outlet of the condenser (34), and the outlet is connected to the first liquid inlet preheater (14) through the second material pump group (33); the inlet of the condenser (34) is connected to the outlet of the analytical tower kettle (221); the inlet of the first material pump group (32) is connected to the outlet of the absorption tower kettle (131), and the outlet is connected to the inlet of the second liquid inlet preheater (21); The vacuum system (4) comprises a vacuum buffer tank (41), a vacuum pump (42) and a high-purity ammonia storage tank (43); the inlet of the vacuum buffer tank (41) is connected to the gas-liquid separator (23), and the outlet is connected to the high-purity ammonia storage tank (43) through the vacuum pump (42); The analysis system (5) comprises a real-time ammonia analyzer (51), and the ammonia analyzer (51) is respectively connected to the inlet and the outlet of the absorption tower system (1).

2. The experimental device according to claim 1, characterized in that: The absorption tower body (132) and the analysis tower body (222) are both of sleeve-type structure and are heated by constant temperature oil bath; a first electromagnetic valve (15), a first material pump group (32) and a first back pressure valve (16) are sequentially connected in series between the absorption tower system (1) and the analysis tower system (2); a first differential pressure transmitter (17) is also provided between the absorption tower kettle (131) and the first electromagnetic valve (15); the differential pressure value transmitted by the first differential pressure transmitter (17) is used to control the opening and closing of the first electromagnetic valve (15); one end of the first electromagnetic valve (15) is connected to the absorption tower kettle (131), and the other end is connected to the inlet of the second liquid inlet preheater (21) through the first material pump group (32) and the first back pressure valve (16); the first electromagnetic valve (15), the first differential pressure transmitter (17) and the first material pump group (32) are linked and regulated.

3. The experimental device according to claim 2, characterized in that: The absorption tower body (132) and the analytical tower body (222) are both filled with stainless steel triangular spiral rings or mesh ring fillers.

4. The experimental device according to claim 1, characterized in that: A second solenoid valve (24) and a second differential pressure transmitter (25) are provided between the analytical tower kettle (221) and the condenser (34). The differential pressure value transmitted by the second differential pressure transmitter (25) is used to control the opening and closing of the second solenoid valve (24), thereby automatically adjusting the absorbent liquid level in the analytical tower kettle (221).

5. The experimental device according to claim 2, characterized in that: The first material pump group (32) includes a first plunger metering pump (321) and a first horizontal flow pump (322) arranged in parallel, and the second material pump group (33) includes a second plunger metering pump (331) and a second horizontal flow pump (332) arranged in parallel; wherein the first plunger metering pump (321) and the second plunger metering pump (331) are used to convey absorbent with a viscosity greater than 10CP, and the first horizontal flow pump (322) and the second horizontal flow pump (332) are used to convey absorbent with a viscosity less than or equal to 10CP.

6. The experimental device according to any one of claims 1 to 5, characterized in that: The experimental device also includes a control system for full-process control and real-time monitoring of the temperature, pressure, pressure difference, absorbent flow rate and gas flow rate of the experimental device.

7. The experimental device according to claim 6, characterized in that: The ammonia analyzer (51) continuously monitors the ammonia concentration at the inlet and outlet of the absorption tower (13), and feeds back the monitoring data to the control system to optimize the operating parameters.

8. A method for separating ammonia by using an experimental device for circulating absorption and analysis of ammonia-containing mixed gas, characterized in that: The following steps are involved: S1, the ammonia-containing mixed gas is metered by a mass flow meter (11), heated by a gas preheater (12) and enters the bottom of an absorption tower (13); the absorbent lean liquid from the absorbent configuration system (3) is metered by a second material pump group (33), heated by a first liquid inlet preheater (14) and enters the top of the absorption tower (13), where it countercurrently contacts the mixed gas and absorbs ammonia to form a rich liquid; the unabsorbed gas is returned to an external ammonia synthesis device through a tower top condenser (133) for continued use; S2, the rich liquid is pressure-regulated by the first electromagnetic valve (15), the first material pump group (32) and the first back pressure valve (16), and then heated by the second liquid inlet preheater (21) and enters the top of the desorption tower (22), where ammonia is desorbed under vacuum conditions, and enters the vacuum buffer tank (41) through the gas-liquid separator (23), and then enters the high-purity ammonia storage tank (43) through the vacuum pump (42); the lean liquid after desorption enters the desorption tower kettle (221) by gravity, and then enters the absorbent storage tank (31) through the second electromagnetic valve (24) and the condenser (34) for recycling.

9. The method according to claim 8, characterized in that The absorbent is a low eutectic solvent containing weak acidic groups and hydrogen bonding groups; the operating pressure of the absorption tower (13) is 0-15MPa, and the temperature is room temperature-80°C; the operating pressure of the analysis tower (22) is 2-3kPa, and the temperature is room temperature-120°C.

10. The method according to claim 8, characterized in that The vacuum condition of the analytical tower (22) is maintained by a vacuum pump (42), and the vacuum buffer tank (41) is used to stabilize the pressure fluctuation of the system.

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