Liquid ammonia level experiment loop device and experiment method thereof

Abstract

The invention discloses a liquid ammonia level experiment loop device and an experiment method thereof. The liquid ammonia level experiment loop device comprises a gas supply and pressurization system, a circulation power system, a data acquisition system and a relief pressure reduction system. Parameters such as fluid temperature, pressure and flow in the pipe can be monitored in real time, fluid circulation, loop temperature compensation and cooling are achieved, research on sensitive parameters such as ammonia feeding temperature, flow and pressure can be met, meanwhile, the loop platform is provided with an emergency cut-off valve, and it can be ensured that the experiment safety risk is controllable. Through matching and cooperation of high-precision and high-stability instruments and equipment, accurate control over initial conditions of liquid ammonia is achieved, and the collection precision of flow parameters such as temperature and pressure in a pipe is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of NH3 pipelines, in particular to a liquid ammonia horizontal experimental loop device and an experimental method thereof. Background Technique

[0002] As a carbon-free hydrogen-rich energy carrier, liquid ammonia shows great potential in the green energy transformation. Its volumetric hydrogen storage density is as high as 13 MJ / L, its safety is better than that of hydrogen, and its production process is mature. It has become a key medium in the fields of maritime shipping, coal-fired power blending, hydrogen energy storage and transportation, etc. The liquid ammonia pipeline system, as an economical and safe way for large-scale liquid ammonia transportation, can effectively solve the problem of regional supply-demand mismatch of hydrogen / ammonia energy. Traditional loop platforms are difficult to achieve precise control of the liquid ammonia phase state, and there is insufficient acquisition of high-precision dynamic parameters (such as pressure fluctuations, temperature drop rates, etc.). Numerical simulations rely on the expansion of oil and gas modules of software (OLGA, PIPESIM), lack a special state equation for liquid ammonia and a two-phase flow pattern identification algorithm, and the model error generally exceeds 15%.

[0003] For liquid ammonia pipeline transportation, it is necessary to ensure that the pressure inside the pipe is always higher than its saturated vapor pressure to avoid vaporization. However, existing hydrodynamic and thermodynamic models (such as the Darcy-Weisbach formula, LPG friction correction model) have insufficient prediction accuracy for the unsteady flow of liquid ammonia in the gas-liquid two-phase state, and lack data support for transient conditions dominated by phase change such as leakage. Data such as heat loss during the liquid ammonia pipeline transportation process is unknown, resulting in conservative design parameters and excessive redundancy in safety protection.

[0004] To address the above challenges, it is urgent to build a liquid ammonia loop platform, integrate functions of high-precision temperature and pressure control, phase state regulation and relief simulation, cover working conditions such as steady state and leakage, carry out research on NH3 pipeline transportation, and provide a basis for revealing the variation law of hydraulic state parameters of pipeline-transported NH3 and formulating a pipeline flow assurance plan. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a liquid ammonia horizontal experimental loop device and an experimental method thereof. This device can accurately control the initial temperature, initial pressure and its phase state of liquid ammonia under set working conditions, accurately measure the changes in temperature, pressure and mass flow rate inside the pipeline, and realize the dynamic visualization of the flow process, and observe the phase state and flow changes of the fluid inside the pipeline in real time.

[0006] To achieve the above purpose, the present invention adopts the following technical scheme: A liquid ammonia horizontal experimental loop device includes a gas supply and pressurization system, a circulation power system, a data acquisition system, and a relief and decompression system, wherein: The described air supply and pressurization system includes an air compressor (1), an ammonia gas cylinder (2), a first manual ball valve (3-1), a second manual ball valve (3-2), a pneumatic booster pump (4), a first check valve (5), a first regulating valve (6-1), and a liquid ammonia storage tank (19); there are two branches at the inlet of the pipeline connected to the pneumatic booster pump (4), and the two branches of the pipeline connected to the pneumatic booster pump (4) are respectively connected to the first manual ball valve (3-1) and the second manual ball valve (3-2); the inlet direction of the first manual ball valve (3-1) is connected to the air compressor (1); the inlet direction of the manual ball valve (3-2) is connected to the ammonia gas cylinder (2); the exhaust port of the pneumatic booster pump (4) is connected to the first gate valve (7-1). The described circulation power system includes a first gate valve (7-1), a second regulating valve (6-2), a second check valve (5-2), a circulation pump (8), a frequency converter (9), a third check valve (5-3), a second gate valve (7-2), a third regulating valve (6-3), a third manual ball valve (3-3), a heat tracing tape (13), a pre-cooling section (17), a refrigerating machine (18), a second gate valve (7-2), a first electro-pneumatic quick shut-off and quick opening valve (14-1), a second electro-pneumatic quick shut-off and quick opening valve (14-2), a third electro-pneumatic quick shut-off and quick opening valve (14-3), a fourth electro-pneumatic quick shut-off and quick opening valve (14-4), a fifth electro-pneumatic quick shut-off and quick opening valve (14-5), a sixth electro-pneumatic quick shut-off and quick opening valve (14-6), a seventh electro-pneumatic quick shut-off and quick opening valve (14-7); the circulation pump (8) is connected to the first regulating valve (6-1), and the first gate valve (7-1) is provided between the circulation pump (8) and the first regulating valve (6-1); the circulation pump (8) is connected to the inlet of the heat tracing tape (13), and a frequency converter (9), a second check valve (5-2), a second gate valve (7-2), a second regulating valve (6-2), and a third manual ball valve (3-3) are provided between the circulation pump (8) and the heat tracing tape (13); the heat tracing tape (13) is connected to the inlet of the pre-cooling section (17), and the first electro-pneumatic quick shut-off and quick opening valve (14-1), the second electro-pneumatic quick shut-off and quick opening valve (14-2), the third electro-pneumatic quick shut-off and quick opening valve (14-3), the fourth electro-pneumatic quick shut-off and quick opening valve (14-4), the fifth electro-pneumatic quick shut-off and quick opening valve (14-5), the sixth electro-pneumatic quick shut-off and quick opening valve (14-6), and the refrigerating machine (18) are provided between the pre-cooling section (17) and the heat tracing tape (13). The data acquisition system includes a first temperature transmitter (12-1), a second temperature transmitter (12-2), a third temperature transmitter (12-3), a fourth temperature transmitter (12-4), a fifth temperature transmitter (12-5), a sixth temperature transmitter (12-6), a seventh temperature transmitter (12-7), an eighth temperature transmitter (12-8), a ninth temperature transmitter (12-9), a tenth temperature transmitter (12-10), an eleventh temperature transmitter (12-11), a first pressure transmitter (10-1), a second pressure transmitter (10-2), a third pressure transmitter (10-3), a fourth pressure transmitter (10-4), a first differential pressure transmitter (16-1), a second differential pressure transmitter (16-2), a third differential pressure transmitter (16-3), a fourth differential pressure transmitter (16-4), a fifth differential pressure transmitter (16-5), a sixth differential pressure transmitter (16-6), a visual window (15), a first mass flowmeter (11), and a second mass flowmeter (11-2); the first pressure transmitter (10-1) is connected to the outlet of the circulation pump (8), the second pressure transmitter (10-2) is connected to the inlet of the pipe section of the tracing heater (13), and a first temperature transmitter (12-1) and a first mass flowmeter (11) are provided between the first pressure transmitter (10-1) and the second pressure transmitter (10-2); the second temperature transmitter (12-2) is connected to the outlet of the tracing heater (13) in the heating section; the third pressure transmitter (10-3) is connected to the inlet of the first pneumatic quick-opening and quick-closing valve (14-1), the starting point of the measurement of the first differential pressure transmitter (16-1) is the third pressure transmitter (10-3), and the ending point is the middle pipe section between the first pneumatic quick-opening and quick-closing valve (14-1) and the second pneumatic quick-opening and quick-closing valve (14-2), and the third temperature transmitter (12-3) is provided in this pipe section; the starting point of the measurement of the second differential pressure transmitter (16-2) is the first differential pressure transmitter (16-1), and the ending point is the middle pipe section between the second pneumatic quick-opening and quick-closing valve (14-2) and the third pneumatic quick-opening and quick-closing valve (14-3), and the fourth temperature transmitter (12-4) is provided in this pipe section; the starting point of the measurement of the third differential pressure transmitter (16-3) is the second differential pressure transmitter (16-2), and the ending point is the middle pipe section between the third pneumatic quick-opening and quick-closing valve (14-3) and the fourth pneumatic quick-opening and quick-closing valve (14-4), and the fifth temperature transmitter (12-5) is provided in this pipe section; the starting point of the measurement of the fourth differential pressure transmitter (16-4) is the third differential pressure transmitter (16-3), and the ending point is the middle pipe section between the fourth pneumatic quick-opening and quick-closing valve (14-4) and the fifth pneumatic quick-opening and quick-closing valve (14-5), and the sixth temperature transmitter (12-6) is provided in this pipe section;The starting point of the fifth differential pressure transmitter (16-5) is the fourth differential pressure transmitter (16-4), and the ending point is the middle pipe section between the fifth pneumatic quick-opening and quick-closing valve (14-5) and the sixth pneumatic quick-opening and quick-closing valve (14-6). The seventh temperature transmitter (12-7) is provided on this pipe section; the starting point of the sixth differential pressure transmitter (16-6) is the fifth differential pressure transmitter (16-5), and the ending point is the middle pipe section between the sixth pneumatic quick-opening and quick-closing valve (14-6) and the precooling section (17). The eighth temperature transmitter (12-8) is provided on this pipe section; the ninth temperature transmitter (12-9) is connected to the inlet of the precooling section (17), the tenth temperature transmitter (12-10) is connected to the inlet of the electric ball valve (20), the second mass flowmeter (11-2) is connected to the outlet of the electric ball valve (20), and the eleventh temperature transmitter (12-11) is provided between the second mass flowmeter (11-2) and the electric ball valve (20). The pressure relief and discharge system includes: the fourth manual ball valve (3-4), the fifth manual ball valve (3-5), the sixth manual ball valve (3-6), the seventh manual ball valve (3-7), the eighth manual ball valve (3-8), the ninth manual ball valve (3-9), the tenth manual ball valve (3-10), the eleventh manual ball valve (3-11), the third gate valve (7-3), the electric ball valve (20), and the absorption tower (21); the third gate valve (7-3) is connected to the inlet of the first mass flowmeter (11-1), the fifth manual ball valve (3-5) is connected between the first pneumatic quick-opening and quick-closing valve (14-1) and the second pneumatic quick-opening and quick-closing valve (14-2) in the measurement section, the sixth manual ball valve (3-6) is connected between the third pneumatic quick-opening and quick-closing valve (14-3) and the second pneumatic quick-opening and quick-closing valve (14-2), the seventh manual ball valve (3-7) is connected between the third pneumatic quick-opening and quick-closing valve (14-3) and the fourth pneumatic quick-opening and quick-closing valve (14-4), the eighth manual ball valve (3-8) is connected between the fifth pneumatic quick-opening and quick-closing valve (14-5) and the fourth pneumatic quick-opening and quick-closing valve (14-4), the ninth manual ball valve (3-9) is connected between the fifth pneumatic quick-opening and quick-closing valve (14-5) and the sixth pneumatic quick-opening and quick-closing valve (14-6), the tenth manual ball valve (3-10) is connected between the sixth pneumatic quick-opening and quick-closing valve (14-6) and the inlet of the electric ball valve (20), the absorption tower (21) is connected to the end of the discharge section, and the tenth temperature transmitter (12-10), the electric ball valve (20), the tenth temperature transmitter (12-10), the second mass flowmeter (11-2), and the eleventh manual ball valve (3-11) are provided between the absorption tower (21) and the fourth pressure transmitter (10-4).

[0007] The present invention also provides an experimental method for a liquid ammonia horizontal pipeline experimental device. Based on the described liquid ammonia horizontal pipeline experimental device, the method includes the following steps: Step S1: Open the second manual ball valve (3-2), the first regulating valve (6-1), the first gate valve (7-1), the second gate valve (7-2), the second regulating valve (6-2), and the third manual ball valve (3-3). At the same time, ensure that the eighth pneumatic quick-opening and quick-closing valve (14-8), the ninth pneumatic quick-opening and quick-closing valve (14-9), the third gate valve (7-3), and the fifth manual ball valve (3-5) to the tenth manual ball valve (3-10) of the pressure relief and decompression part are all closed. The gaseous NH3 in the gas cylinder (2) enters the circulation pump (8) through the pneumatic booster pump (4), then enters the main pipeline, and then enters the pre-cooling section (17). Step S2: Start the refrigerator (18) to control the temperature of NH3 in the pipeline. Step S3: Start the booster pump (4), set the first regulating valve (6-1) to the predetermined opening for the experiment, observe the flow state and phase change of NH3 inside the pipeline through the viewing window (15) until the liquid ammonia in the pipe is observed to be in a full-flow state through the viewing window. Step S4: Start the circulation pump (8), set the frequency of the circulation pump (8) to 30 Hz through the frequency converter (9); control the rotation speed of the circulation pump through the frequency converter (9) to control the flow rate of NH3 in the pipeline. Step S5: Record the pipeline pressure, temperature, and flow rate through the first temperature transmitter (12-1), the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), the first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), the sixth differential pressure transmitter (16-6), and the first mass flowmeter (11-1). Step S6: When the temperature displayed by the ninth temperature transmitter (12-9) is the first temperature and the first pressure transmitter (10-1), the second pressure transmitter (10-2), and the third pressure transmitter (10-3) display 3 MPa, close the pneumatic booster pump (4), the second manual ball valve (3-2), and the first regulating valve (6-1). Step S7: Turn on the tracing heater (13), set the power of the tracing heater to a constant value, heat the liquid ammonia in the pipeline, record the temperature before heating through the first temperature transmitter (12-1), and record the temperature changes of each pipe section after heating through the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), and the ninth temperature transmitter (12-9). The first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), the sixth differential pressure transmitter (16-6), and the first mass flowmeter (11-1) collect the pipeline pressure and flow rate. Step S8: Change the frequency of the circulation pump (8) through the frequency converter (9), repeat Step S7, and explore the change of the heat exchange situation of liquid ammonia at different flow rates. The pipe section where the tracing heater (13) is located is wrapped with a heat insulation layer. If the pressure in the pipeline is too high, relieve the pressure of the pipeline by opening the eighth pneumatic quick-opening and quick-closing valve (14-8) and the ninth pneumatic quick-opening and quick-closing valve (14-9), so as to finely adjust the temperature and pressure of NH3 in the pipeline. Step S9: Turn off the tracing heater (13) and wait for the temperature and pressure of NH3 in the pipeline to stabilize. Step S10: Open the sixth manual ball valve (3-6) and the eleventh manual ball valve (3-11), close the first pneumatic quick-opening and quick-closing valve (14-1) and the fifth pneumatic quick-opening and quick-closing valve (14-5), perform an 80-meter pipe section pressure relief operation on the test pipe section, control the pressure relief rate by adjusting the opening of the electric ball valve (20), record and collect the flow rate through the second mass flowmeter (11-2), and collect the pipeline pressure and temperature changes through the first temperature transmitter (12-1), the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), the first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), and the sixth differential pressure transmitter (16-6). Step S11: Keep the eleventh manual ball valve (3-11) open, open the first pneumatic quick-opening and quick-closing valve (14-1) and the fifth pneumatic quick-opening and quick-closing valve (14-5), and fully open the electric ball valve (20) to relieve the pressure of NH3 in the pipeline. Step S12: Turn off the circulation pump 8, the eleventh manual ball valve (3-11), the fifth manual ball valve (3-5), the sixth manual ball valve (3-6), the seventh manual ball valve (3-7), the eighth manual ball valve (3-8), the ninth manual ball valve (3-9), the tenth manual ball valve (3-10), and the third gate valve (7-3), save the experimental data, and end the experimental test.

[0008] In a preferred embodiment, in step 2, set the temperature of the refrigerator (18) to 20 °C.

[0009] In a preferred embodiment, in step 4, the circulation pump (8) is a sliding vane pump, which provides power for the circulating flow of liquid ammonia in the loop.

[0010] In a preferred embodiment, in step 5, the acquisition time step is 0.1 s.

[0011] In a preferred embodiment, in step 6, the first temperature is 20 °C.

[0012] In a preferred embodiment, in step 7, the acquisition time step is 0.1 s.

[0013] In a preferred embodiment, in step 10, collect the flow rate and temperature changes, and the acquisition time step is 0.1 s for both.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention can achieve precise control of the NH3 phase state, simulate the real flow conditions of the fluid in the NH3 pipeline under steady-state flow, heat transfer, and relief pressure reduction conditions, and reflect the spatio-temporal evolution characteristics of the hydraulic and thermal parameters in the pipeline. Especially under the relief pressure reduction condition, it can accurately observe and record the temperature, pressure, mass flow rate, and phase state changes of NH3 in the pipeline, and can analyze the influence of initial conditions such as pressure, temperature, and relief aperture on the phase change mechanism and flow characteristics in the pipeline. It can automatically collect various test data through a computer automatic acquisition system and draw parameter change curves. It has the advantages of high measurement accuracy, intuitive experimental results, good safety performance, and convenient operation, and is of great significance for formulating pipeline flow assurance plans. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the general process diagram of the NH3 loop experimental device of the present invention; Figure 2 is the detailed process diagram of the relief system.

[0016] In the figure: 1. Air compressor; 2. Ammonia gas cylinder; 3-1. First manual ball valve; 3-2. Second manual ball valve; 3-3. Third manual ball valve; 3-4. Fourth manual ball valve; 3-5. Fifth manual ball valve; 3-6. Sixth manual ball valve; 3-7. Seventh manual ball valve; 3-8. Eighth manual ball valve; 3-9. Ninth manual ball valve; 3-10. Tenth manual ball valve; 3-11. Eleventh manual ball valve; 4. Pneumatic booster pump; 5-1. First check valve; 5-2. Second check valve; 6-1. First regulating valve; 6-2. Second regulating valve; 6-3. Third regulating valve; 8. Circulation pump; 9. Frequency converter; 10-1. First pressure transmitter; 10-2. Second pressure transmitter; 10-3. Third pressure transmitter; 10-4. Fourth pressure transmitter; 11-1. First mass flowmeter; 11-2. Second mass flowmeter; 12-1. First temperature transmitter; 12-2. Second temperature transmitter; 12-3. Third temperature transmitter; 12-4. Fourth temperature transmitter; 12-5. Fifth temperature transmitter; 12-6. Sixth temperature transmitter; 12-7. Seventh temperature transmitter; 12-8. Eighth temperature transmitter; 12-9. Ninth temperature transmitter; 12-10. Tenth temperature transmitter; 12-11. Eleventh temperature transmitter; 13. Heat tracing tape; 14-1. First electro-pneumatic quick shut-off (open) valve; 14-2. Second electro-pneumatic quick shut-off (open) valve; 14-3. Third electro-pneumatic quick shut-off (open) valve; 14-4. Fourth electro-pneumatic quick shut-off (open) valve; 14-5. Fifth electro-pneumatic quick shut-off (open) valve; 14-6. Sixth electro-pneumatic quick shut-off (open) valve; 14-7. Seventh electro-pneumatic quick shut-off (open) valve; 14-8. Eighth electro-pneumatic quick shut-off (open) valve; 14-9. Ninth electro-pneumatic quick shut-off (open) valve; 15. Visual window; 16-1. First differential pressure transmitter; 16-2. Second differential pressure transmitter; 16-3. Third differential pressure transmitter; 16-4. Fourth differential pressure transmitter; 16-5. Fifth differential pressure transmitter; 16-6. Sixth differential pressure transmitter; 17. Pre-cooling section; 18. Refrigerator; 19. Liquid ammonia storage tank; 20. Electric ball valve; 21. Absorption tower. Detailed implementation mode

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] Taking the steady-state flow of ammonia in pipe infusion, heat transfer experiment, and relief and pressure reduction as examples below, the loop is composed of pipelines with an inner diameter of 26 mm and a length of 108 m. The viewing window is made of transparent plexiglass, and the other pipe sections are all made of 304 stainless steel. Aluminum foil insulation sleeves with a thickness of 2 mm are laid on the outer wall surfaces of the pipe sections. The experiment uses a 100 L high-purity (99.8%) ammonia gas cylinder as the gas source. The pipeline pressurization process is realized by a pneumatic booster pump. The saturated ammonia vapor at 0.8 MPa in the ammonia gas cylinder at room temperature enters the pipeline after being pressurized and liquefied by the pneumatic booster pump.

[0021] Reference Figure 1-2 , a liquid ammonia horizontal experimental loop device includes a gas supply and pressurization system, a circulation power system, a data acquisition system, and a relief and pressure reduction system.

[0022] The gas supply and pressurization system includes an air compressor 1, an ammonia gas cylinder 2, a first manual ball valve 3-1, a second manual ball valve 3-2, a pneumatic booster pump 4, a first check valve 5, a first regulating valve 6-1, and a liquid ammonia storage tank 19. The pneumatic booster pump 4 has two branches connecting to the pipeline inlet. The two branches of the pneumatic booster pump 4 connecting to the pipeline are respectively connected to the first manual ball valve 3-1 and the second manual ball valve 3-2; the inlet direction of the first manual ball valve 3-1 is connected to the air compressor 1; the inlet direction of the manual ball valve 3-2 is connected to the ammonia gas cylinder 2; the exhaust port of the pneumatic booster pump 4 is connected to the first gate valve 7-1; The described circulation power system includes a first gate valve 7-1, a second regulating valve 6-2, a second check valve 5-2, a circulation pump 8, a frequency converter 9, a third check valve 5-3, a second gate valve 7-2, a third regulating valve 6-3, a third manual ball valve 3-3, a tracing heater 13, a pre-cooling section 17, a refrigerating machine 18, a second gate valve 7-2, a first pneumatic quick-opening and quick-closing valve 14-1, a second pneumatic quick-opening and quick-closing valve 14-2, a third pneumatic quick-opening and quick-closing valve 14-3, a fourth pneumatic quick-opening and quick-closing valve 14-4, a fifth pneumatic quick-opening and quick-closing valve 14-5, a sixth pneumatic quick-opening and quick-closing valve 14-6, and a seventh pneumatic quick-opening and quick-closing valve 14-7. The circulation pump 8 is connected to the first regulating valve 6-1, and the first gate valve 7-1 is provided between the circulation pump 8 and the first regulating valve 6-1; the circulation pump 8 is connected to the inlet of the tracing heater 13, and a frequency converter 9, a second check valve 5-2, a second gate valve 7-2, a second regulating valve 6-2, and a third manual ball valve 3-3 are provided between the circulation pump 8 and the tracing heater 13; the tracing heater 13 is connected to the inlet of the pre-cooling section 17, and the first pneumatic quick-opening and quick-closing valve 14-1, the second pneumatic quick-opening and quick-closing valve 14-2, the third pneumatic quick-opening and quick-closing valve 14-3, the fourth pneumatic quick-opening and quick-closing valve 14-4, the fifth pneumatic quick-opening and quick-closing valve 14-5, the sixth pneumatic quick-opening and quick-closing valve 14-6, and the refrigerating machine 18 are provided between the pre-cooling section 17 and the tracing heater 13; The data acquisition system includes the first temperature transmitter 12-1, the second temperature transmitter 12-2, the third temperature transmitter 12-3, the fourth temperature transmitter 12-4, the fifth temperature transmitter 12-5, the sixth temperature transmitter 12-6, the seventh temperature transmitter 12-7, the eighth temperature transmitter 12-8, the ninth temperature transmitter 12-9, the tenth temperature transmitter 12-10, the eleventh temperature transmitter 12-11, the first pressure transmitter 10-1, the second pressure transmitter 10-2, the third pressure transmitter 10-3, the fourth pressure transmitter 10-4, the first differential pressure transmitter 16-1, the second differential pressure transmitter 16-2, the third differential pressure transmitter 16-3, the fourth differential pressure transmitter 16-4, the fifth differential pressure transmitter 16-5, the sixth differential pressure transmitter 16-6, the visual window 15, the first mass flowmeter 11, and the second mass flowmeter 11-2. The first pressure transmitter 10-1 is connected to the outlet of the circulation pump 8. The second pressure transmitter 10-2 is connected to the inlet of the pipe section of the tracing heating tape 13. Between the first pressure transmitter 10-1 and the second pressure transmitter 10-2, there are the first temperature transmitter 12-1 and the first mass flowmeter 11. The second temperature transmitter 12-2 is connected to the outlet of the tracing heating tape 13 in the heating section. The third pressure transmitter 10-3 is connected to the inlet of the first pneumatic quick-opening and quick-closing valve 14-1. The starting point of the measurement of the first differential pressure transmitter 16-1 is the third pressure transmitter 10-3, and the ending point is the middle pipe section between the first pneumatic quick-opening and quick-closing valve 14-1 and the second pneumatic quick-opening and quick-closing valve 14-2. The third temperature transmitter 12-3 is arranged on this pipe section. The starting point of the measurement of the second differential pressure transmitter 16-2 is the first differential pressure transmitter 16-1, and the ending point is the middle pipe section between the second pneumatic quick-opening and quick-closing valve 14-2 and the third pneumatic quick-opening and quick-closing valve 14-3. The fourth temperature transmitter 12-4 is arranged on this pipe section. The starting point of the measurement of the third differential pressure transmitter 16-3 is the second differential pressure transmitter 16-2, and the ending point is the middle pipe section between the third pneumatic quick-opening and quick-closing valve 14-3 and the fourth pneumatic quick-opening and quick-closing valve 14-4. The fifth temperature transmitter 12-5 is arranged on this pipe section. The starting point of the measurement of the fourth differential pressure transmitter 16-4 is the third differential pressure transmitter 16-3, and the ending point is the middle pipe section between the fourth pneumatic quick-opening and quick-closing valve 14-4 and the fifth pneumatic quick-opening and quick-closing valve 14-5. The sixth temperature transmitter 12-6 is arranged on this pipe section. The starting point of the measurement of the fifth differential pressure transmitter 16-5 is the fourth differential pressure transmitter 16-4, and the ending point is the middle pipe section between the fifth pneumatic quick-opening and quick-closing valve 14-5 and the sixth pneumatic quick-opening and quick-closing valve 14-6. The seventh temperature transmitter 12-7 is arranged on this pipe section. The starting point of the measurement of the sixth differential pressure transmitter 16-6 is the fifth differential pressure transmitter 16-5, and the ending point is the middle pipe section between the sixth pneumatic quick-opening and quick-closing valve 14-6 and the pre-cooling section 17. The eighth temperature transmitter 12-8 is arranged on this pipe section.The described ninth temperature transmitter 12-9 is connected to the inlet of the pre-cooling section 17. The tenth temperature transmitter 12-10 is connected to the inlet of the electric ball valve 20. The second mass flowmeter 11-2 is connected to the outlet of the electric ball valve 20. An eleventh temperature transmitter 12-11 is provided between the second mass flowmeter 11-2 and the electric ball valve 20. The differential pressure transmitter measures the pressure change between the pipe segments.

[0023] The relief and pressure reduction system includes: a fourth manual ball valve 3-4, a fifth manual ball valve 3-5, a sixth manual ball valve 3-6, a seventh manual ball valve 3-7, an eighth manual ball valve 3-8, a ninth manual ball valve 3-9, a tenth manual ball valve 3-10, an eleventh manual ball valve 3-11, a third gate valve 7-3, an electric ball valve 20, and an absorption tower 21. The third gate valve 7-3 is connected to the inlet of the first mass flowmeter 11-1. The fifth manual ball valve 3-5 is connected between the first electro-pneumatic quick-opening and quick-closing valve 14-1 and the second electro-pneumatic quick-opening and quick-closing valve 14-2 in the measurement section. The sixth manual ball valve 3-6 is connected between the third electro-pneumatic quick-opening and quick-closing valve 14-3 and the second electro-pneumatic quick-opening and quick-closing valve 14-2. The seventh manual ball valve 3-7 is connected between the third electro-pneumatic quick-opening and quick-closing valve 14-3 and the fourth electro-pneumatic quick-opening and quick-closing valve 14-4. The eighth manual ball valve 3-8 is connected between the fifth electro-pneumatic quick-opening and quick-closing valve 14-5 and the fourth electro-pneumatic quick-opening and quick-closing valve 14-4. The ninth manual ball valve 3-9 is connected between the fifth electro-pneumatic quick-opening and quick-closing valve 14-5 and the sixth electro-pneumatic quick-opening and quick-closing valve 14-6. The tenth manual ball valve 3-10 is connected between the sixth electro-pneumatic quick-opening and quick-closing valve 14-6 and the inlet of the electric ball valve 20. The absorption tower 21 is connected to the end of the relief section. Between the absorption tower 21 and the fourth pressure transmitter 10-4, there are a tenth temperature transmitter 12-10, an electric ball valve 20, a tenth temperature transmitter 12-10, a second mass flowmeter 11-2, and an eleventh manual ball valve 3-11. The tenth temperature transmitter 12-10 is used to measure the temperature of the liquid ammonia in the relief pipe segment. The eleventh temperature transmitter 12-11 is used to measure the temperature of the liquid ammonia after relief. The second mass flowmeter 11-2 is used to measure the flow rate of the relieved liquid ammonia. The electric ball valve 20 is used to control the speed of relief and pressure reduction.

[0024] In this embodiment, by controlling the power of the refrigerator 18 and the power of the heating plate 14, the temperature control of the liquid ammonia fluid can be achieved, and further the control research on the phase change of the liquid ammonia can be carried out. The pneumatic booster pump 4 is a plunger pump whose reciprocating motion is controlled by a two-position four-way pilot valve. The pressure ratio is generated by the area ratio of two pistons, and the driving air pressure is generated by an air compressor. The output air pressure is steplessly adjusted by the driving air pressure. The circulation pump 8 uses a sliding vane pump, which has good self-priming performance and can better handle gas-containing liquids, providing power for the circulating flow of liquid ammonia in the loop.

[0025] In this embodiment, the first electro-pneumatic quick-opening and quick-closing valve 14-1, the second electro-pneumatic quick-opening and quick-closing valve 14-2, the third electro-pneumatic quick-opening and quick-closing valve 14-3, the fourth electro-pneumatic quick-opening and quick-closing valve 14-4, the fifth electro-pneumatic quick-opening and quick-closing valve 14-5, the sixth electro-pneumatic quick-opening and quick-closing valve 14-6, the seventh electro-pneumatic quick-opening and quick-closing valve 14-7, the eighth electro-pneumatic quick-opening and quick-closing valve 14-8, and the ninth electro-pneumatic quick-opening and quick-closing valve 14-9 are of the Q611M-63P model. The valve body and sealing materials have been specially treated for low temperature resistance and have a maximum pressure-bearing capacity of 6.3 MPa. To ensure that the liquid ammonia in the pipeline can be quickly cut off and opened in case of emergency, a plate-type two-position five-way solenoid valve is additionally equipped. The electric ball valve 20 is used to control the discharge rate of the liquid ammonia. The valve is driven by a 24 VDC input voltage and has a rated torque of 20 N·m. By inputting a control signal through an external signal generator, precise adjustment of the valve opening can be achieved.

[0026] In this embodiment, the phase characteristics and phase changes of NH3 under steady-state conditions and during discharge and decompression can be observed through the high-pressure-resistant viewing window 15.

[0027] In this embodiment, a 100 L high-purity (99.8%) ammonia cylinder is used as the gas source. Since the temperature rise process caused by ammonia compression and condensation occurs in the tank during the filling process, the tank needs to be cooled to ensure the filling efficiency.

[0028] In this embodiment, the temperature transmitter, pressure sensor, booster pump, differential pressure sensor, and mass flowmeter can all be connected to the computer through data lines, enabling real-time data recording and the formation of corresponding pressure curves, temperature curves, and flow curves, and controlling the opening and operating frequency of each device.

[0029] In this embodiment, since ammonia is very easy to react with the residual air in the pipe, it is necessary to adopt a purging method of nitrogen first and then ammonia to ensure that the pipeline system is in a pure ammonia environment during the formal experiment. The specific operation steps include: controlling the outlet pressure reducing valve of the nitrogen bottle, passing 0.4 MPa low-pressure nitrogen, opening and closing the equipment instrument and the discharge valve of the main pipeline in turn according to the flow direction, and the purging time of each pipe section depends on the size of the cavity, and it is necessary to ensure that all moisture and impurities in the system are completely discharged. A white cloth is set at the outlet of the discharge section to determine whether the purging is completed by whether there are water marks and impurities on the white cloth for 10 consecutive minutes. By adjusting the back pressure of the ammonia bottle outlet valve to 0.8MPa, ammonia with a relatively higher pressure is passed for purging, and the operation steps are the same as nitrogen purging. The nitrogen content of the gas sample at the outlet of the discharge section is less than 0.5% as the standard to judge whether the nitrogen in the pipe is completely discharged.

[0030] In this embodiment, an insulation test is performed on electrical equipment such as a data acquisition system, a frequency converter, and a sensor to prevent electromagnetic interference or abnormal operation of the equipment from affecting the accuracy of the experimental results.

[0031] The present invention can accurately measure and observe the temperature, pressure, mass flow rate and phase change in the pipeline under set working conditions, and specifically includes the following steps: Step S1: Open the second manual ball valve 3-2, the first regulating valve 6-1, the first gate valve 7-1, the second gate valve 7-2, the second regulating valve 6-2, and the third manual ball valve 3-3, while ensuring that the eighth electric pneumatic fast closing and opening valve 14-8, the ninth electric pneumatic fast closing and opening valve 14-9, the third gate valve 7-3, and the fifth manual ball valve 3-5 to the tenth manual ball valve 3-10 of the relief and pressure relief part are all closed; the gaseous NH3 in the gas cylinder 2 enters the circulation pump 8 through the pneumatic booster pump 4, and then enters the main pipeline, and then enters the pre-cooling section 17.

[0032] Step S2: Turn on the refrigerator 18, set the refrigerator temperature to 20° C., and control the temperature of NH3 in the pipeline.

[0033] Step S3: Start the booster pump 4, set the first regulating valve 6-1 to a predetermined opening for the experiment, and observe the flow state and phase change of NH3 inside the pipeline through the visual window 15 until the liquid ammonia in the pipeline is observed to be in a full flow state through the visual window.

[0034] Step S4: Turn on the circulation pump 8, and set the frequency of the circulation pump 8 to 30 Hz through the frequency converter 9. It should be noted that the circulation pump 8 adopts a vane pump, which has good self-priming performance, can better handle gas-containing liquids, and provide power for the circulation of liquid ammonia in the loop. The circulation pump speed is controlled by the frequency converter 9, thereby controlling the NH3 flow rate in the pipeline.

[0035] Step S5: Record the pipeline pressure, temperature, and flow rate through the first temperature transmitter 12-1, second temperature transmitter 12-2, third temperature transmitter 12-3, fourth temperature transmitter 12-4, fifth temperature transmitter 12-5, sixth temperature transmitter 12-6, seventh temperature transmitter 12-7, eighth temperature transmitter 12-8, first differential pressure transmitter 16-1, second differential pressure transmitter 16-2, third differential pressure transmitter 16-3, fourth differential pressure transmitter 16-4, fifth differential pressure transmitter 16-5, sixth differential pressure transmitter 16-6, and first mass flowmeter 11-1. The acquisition time step is 0.1 s.

[0036] Step S6: When the temperature displayed by the ninth temperature transmitter 12-9 is 20 °C and the first pressure transmitter 10-1, second pressure transmitter 10-2, and third pressure transmitter 10-3 display 3 MPa, turn off the pneumatic booster pump 4, second manual ball valve 3-2, and first regulating valve 6-1.

[0037] Step S7: Turn on the tracing heater 13, set the power of the tracing heater to a constant value, heat the liquid ammonia in the pipeline, record the temperature before heating through the first temperature transmitter 12-1, and record the temperature changes of each pipe section after heating through the second temperature transmitter 12-2, third temperature transmitter 12-3, fourth temperature transmitter 12-4, fifth temperature transmitter 12-5, sixth temperature transmitter 12-6, seventh temperature transmitter 12-7, eighth temperature transmitter 12-8, and ninth temperature transmitter 12-9. The first differential pressure transmitter 16-1, second differential pressure transmitter 16-2, third differential pressure transmitter 16-3, fourth differential pressure transmitter 16-4, fifth differential pressure transmitter 16-5, sixth differential pressure transmitter 16-6, and first mass flowmeter 11-1 collect the pipeline pressure and flow rate. The acquisition time step is 0.1 s. Through the above data, the heat exchange situation of the liquid ammonia in the test pipe section can be obtained.

[0038] Step S8: Change the frequency of the circulation pump 8 through the frequency converter 9, and repeat Step S7 to explore the change of the heat exchange situation of the liquid ammonia at different flow rates. It should be noted that the pipe section where the tracing heater 13 is located is wrapped with a heat insulation layer, and the external heat loss can be ignored. If the pipeline pressure is too high, the pipeline can be depressurized by opening the eighth pneumatic quick-opening and quick-closing valve 14-8 and the ninth pneumatic quick-opening and quick-closing valve 14-9, so as to finely adjust the temperature and pressure of NH3 in the pipeline.

[0039] Step S9: Turn off the tracing heater 13 and wait for the temperature and pressure of NH3 in the pipeline to stabilize.

[0040] Step S10: Open the sixth manual ball valve 3-6 and the eleventh manual ball valve 3-11, close the first pneumatic quick-opening and quick-closing valve 14-1 and the fifth pneumatic quick-opening and quick-closing valve 14-5, perform a pressure relief operation on an 80-meter pipe section of the test pipe section. Control the pressure relief rate by adjusting the opening of the electric ball valve 20, record and collect the flow rate through the second mass flowmeter 11-2, with a collection time step of 0.1 s. Collect the changes in pipeline pressure and temperature through the first temperature transmitter 12-1, the second temperature transmitter 12-2, the third temperature transmitter 12-3, the fourth temperature transmitter 12-4, the fifth temperature transmitter 12-5, the sixth temperature transmitter 12-6, the seventh temperature transmitter 12-7, the eighth temperature transmitter 12-8, the first differential pressure transmitter 16-1, the second differential pressure transmitter 16-2, the third differential pressure transmitter 16-3, the fourth differential pressure transmitter 16-4, the fifth differential pressure transmitter 16-5, and the sixth differential pressure transmitter 16-6, with a collection time step of 0.1 s.

[0041] Step S11: Keep the eleventh manual ball valve 3-11 open, open the first pneumatic quick-opening and quick-closing valve 14-1 and the fifth pneumatic quick-opening and quick-closing valve 14-5, fully open the electric ball valve 20, and relieve the pressure of NH3 in the pipeline.

[0042] Step S12: Close the circulation pump 8, the eleventh manual ball valve 3-11, the fifth manual ball valve 3-5, the sixth manual ball valve 3-6, the seventh manual ball valve 3-7, the eighth manual ball valve 3-8, the ninth manual ball valve 3-9, the tenth manual ball valve 3-10, and the third gate valve 7-3, save the experimental data, and end the experimental test.

[0043] Advantages of the present invention: The present invention adjusts the temperature and pressure of liquid ammonia by using a refrigerating machine, a booster pump, an electric heating device, and a circulation pump to achieve precise control of the temperature and pressure in the NH3 pipeline, and at the same time study the phase change state. Connect the computer to the thermocouple, pressure sensor, mass flowmeter, circulation pump, booster pump, and electric heating device through a data cable, and the computer can directly control the start, stop, and power of the circulation pump, booster pump, and electric heating device, collect and process data, which provides great convenience for researchers and significantly improves the safety of the experimental process. Generally speaking, the present invention can carry out steady-state transportation and pressure relief experiments on liquid ammonia pipelines with different temperatures, pressures, phase states, and pressure relief rates by injecting liquid ammonia into the pipeline. The experimental period is short, the test efficiency is high, and the test accuracy is high, which can guide the safety design and flow assurance research of C0, transportation pipelines.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A liquid ammonia level experimental loop device, characterized in that: It includes a gas supply and boosting system, a circulating power system, a data acquisition system, and a relief and pressure reduction system, where: The gas supply and boosting system includes an air compressor (1), an ammonia gas cylinder (2), a first manual ball valve (3-1), a second manual ball valve (3-2), a pneumatic booster pump (4), a first check valve (5), a first regulating valve (6-1), and a liquid ammonia storage tank (19); there are two branches at the inlet of the pipeline connected to the pneumatic booster pump (4), and the two branches of the pipeline connected to the pneumatic booster pump (4) are respectively connected to the first manual ball valve (3-1) and the second manual ball valve (3-2); the inlet direction of the first manual ball valve (3-1) is connected to the air compressor (1); the inlet direction of the manual ball valve (3-2) is connected to the ammonia gas cylinder (2); the exhaust port of the pneumatic booster pump (4) is connected to the first gate valve (7-1); The circulating power system includes a first gate valve (7-1), a second regulating valve (6-2), a second check valve (5-2), a circulating pump (8), a frequency converter (9), a third check valve (5-3), a second gate valve (7-2), a third regulating valve (6-3), a third manual ball valve (3-3), a heat tracing tape (13), a pre-cooling section (17), a refrigerator (18), a second gate valve (7-2), a first electro-pneumatic quick shut-off and quick opening valve (14-1), a second electro-pneumatic quick shut-off and quick opening valve (14-2), a third electro-pneumatic quick shut-off and quick opening valve (14-3), a fourth electro-pneumatic quick shut-off and quick opening valve (14-4), a fifth electro-pneumatic quick shut-off and quick opening valve (14-5), a sixth electro-pneumatic quick shut-off and quick opening valve (14-6), and a seventh electro-pneumatic quick shut-off and quick opening valve (14-7); the circulating pump (8) is connected to the first regulating valve (6-1), and the first gate valve (7-1) is provided between the circulating pump (8) and the first regulating valve (6-1); the circulating pump (8) is connected to the inlet of the heat tracing tape (13), and a frequency converter (9), a second check valve (5-2), a second gate valve (7-2), a second regulating valve (6-2), and a third manual ball valve (3-3) are provided between the circulating pump (8) and the heat tracing tape (13); the heat tracing tape (13) is connected to the inlet of the pre-cooling section (17), and the first electro-pneumatic quick shut-off and quick opening valve (14-1), the second electro-pneumatic quick shut-off and quick opening valve (14-2), the third electro-pneumatic quick shut-off and quick opening valve (14-3), the fourth electro-pneumatic quick shut-off and quick opening valve (14-4), the fifth electro-pneumatic quick shut-off and quick opening valve (14-5), the sixth electro-pneumatic quick shut-off and quick opening valve (14-6), and the refrigerator (18) are provided between the pre-cooling section (17) and the heat tracing tape (13); The data acquisition system includes the first temperature transmitter (12-1), the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), the ninth temperature transmitter (12-9), the tenth temperature transmitter (12-10), the eleventh temperature transmitter (12-11), the first pressure transmitter (10-1), the second pressure transmitter (10-2), the third pressure transmitter (10-3), the fourth pressure transmitter (10-4), the first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), the sixth differential pressure transmitter (16-6), a visual window (15), the first mass flowmeter (11), and the second mass flowmeter (11-2); the first pressure transmitter (10-1) is connected to the outlet of the circulation pump (8), the second pressure transmitter (10-2) is connected to the inlet of the pipe section of the tracing heating tape (13), and between the first pressure transmitter (10-1) and the second pressure transmitter (10-2), there are the first temperature transmitter (12-1) and the first mass flowmeter (11); the second temperature transmitter (12-2) is connected to the outlet of the tracing heating tape (13) of the heating section; the third pressure transmitter (10-3) is connected to the inlet of the first pneumatic quick-opening and quick-closing valve (14-1), and the starting point of the measurement of the first differential pressure transmitter (16-1) is the third pressure transmitter (10-3), and the ending point is the middle pipe section between the first pneumatic quick-opening and quick-closing valve (14-1) and the second pneumatic quick-opening and quick-closing valve (14-2), and the third temperature transmitter (12-3) is provided on this pipe section; the starting point of the measurement of the second differential pressure transmitter (16-2) is the first differential pressure transmitter (16-1), and the ending point is the middle pipe section between the second pneumatic quick-opening and quick-closing valve (14-2) and the third pneumatic quick-opening and quick-closing valve (14-3), and the fourth temperature transmitter (12-4) is provided on this pipe section; the starting point of the measurement of the third differential pressure transmitter (16-3) is the second differential pressure transmitter (16-2), and the ending point is the middle pipe section between the third pneumatic quick-opening and quick-closing valve (14-3) and the fourth pneumatic quick-opening and quick-closing valve (14-4), and the fifth temperature transmitter (12-5) is provided on this pipe section; the starting point of the measurement of the fourth differential pressure transmitter (16-4) is the third differential pressure transmitter (16-3), and the ending point is the middle pipe section between the fourth pneumatic quick-opening and quick-closing valve (14-4) and the fifth pneumatic quick-opening and quick-closing valve (14-5), and the sixth temperature transmitter (12-6) is provided on this pipe section;The measurement starting point of the fifth differential pressure transmitter (16-5) is the fourth differential pressure transmitter (16-4), and the end point is the middle pipe section between the fifth pneumatic quick-opening and quick-closing valve (14-5) and the sixth pneumatic quick-opening and quick-closing valve (14-6). The seventh temperature transmitter (12-7) is provided on this pipe section; the measurement starting point of the sixth differential pressure transmitter (16-6) is the fifth differential pressure transmitter (16-5), and the end point is the middle pipe section between the sixth pneumatic quick-opening and quick-closing valve (14-6) and the pre-cooling section (17). The eighth temperature transmitter (12-8) is provided on this pipe section; the ninth temperature transmitter (12-9) is connected to the inlet of the pre-cooling section (17), the tenth temperature transmitter (12-10) is connected to the inlet of the electric ball valve (20), the second mass flowmeter (11-2) is connected to the outlet of the electric ball valve (20), and the eleventh temperature transmitter (12-11) is provided between the second mass flowmeter (11-2) and the electric ball valve (20); The pressure relief and decompression system includes: the fourth manual ball valve (3-4), the fifth manual ball valve (3-5), the sixth manual ball valve (3-6), the seventh manual ball valve (3-7), the eighth manual ball valve (3-8), the ninth manual ball valve (3-9), the tenth manual ball valve (3-10), the eleventh manual ball valve (3-11), the third gate valve (7-3), the electric ball valve (20), and the absorption tower (21); the third gate valve (7-3) is connected to the inlet of the first mass flowmeter (11-1), the fifth manual ball valve (3-5) is connected between the first pneumatic quick-opening and quick-closing valve (14-1) and the second pneumatic quick-opening and quick-closing valve (14-2) in the measurement section, the sixth manual ball valve (3-6) is connected between the third pneumatic quick-opening and quick-closing valve (14-3) and the second pneumatic quick-opening and quick-closing valve (14-2), the seventh manual ball valve (3-7) is connected between the third pneumatic quick-opening and quick-closing valve (14-3) and the fourth pneumatic quick-opening and quick-closing valve (14-4), the eighth ball valve (3-8) is connected between the fifth pneumatic quick-opening and quick-closing valve (14-5) and the fourth pneumatic quick-opening and quick-closing valve (14-4), the ninth manual ball valve (3-9) is connected between the fifth pneumatic quick-opening and quick-closing valve (14-5) and the sixth pneumatic quick-opening and quick-closing valve (14-6), the tenth manual ball valve (3-10) is connected between the sixth pneumatic quick-opening and quick-closing valve (14-6) and the inlet of the electric ball valve (20), the absorption tower (21) is connected to the end of the pressure relief section, and a tenth temperature transmitter (12-10), an electric ball valve (20), a tenth temperature transmitter (12-10), a second mass flowmeter (11-2), and an eleventh manual ball valve (3-11) are provided between the absorption tower (21) and the fourth pressure transmitter (10-4).

2. The experimental method of an experimental device for a horizontal liquid ammonia pipeline, characterized in that A liquid ammonia horizontal pipeline experimental device according to claim 1 above, comprising the following steps: Step S1: Open the second manual ball valve (3-2), the first regulating valve (6-1), the first gate valve (7-1), the second gate valve (7-2), the second regulating valve (6-2), and the third manual ball valve (3-3), and at the same time ensure that the eighth pneumatic quick-opening and quick-closing valve (14-8), the ninth pneumatic quick-opening and quick-closing valve (14-9), the third gate valve (7-3), and the fifth manual ball valve (3-5) to the tenth manual ball valve (3-10) in the pressure relief and decompression part are all closed; the gaseous NH3 in the gas cylinder (2) enters the circulation pump (8) through the pneumatic booster pump (4), then enters the main pipeline, and then enters the pre-cooling section (17); Step S2: Start the refrigerator (18) to control the temperature of NH3 in the pipeline; Step S3: Start the booster pump (4), set the first regulating valve (6-1) to the predetermined opening for the experiment, observe the flow state and phase change of NH3 inside the pipeline through the viewing window (15) until the liquid ammonia in the pipeline is observed to be in a full-flow state through the viewing window; Step S4: Turn on the circulation pump (8), set the frequency of the circulation pump (8) to 30 Hz through the frequency converter (9); control the rotation speed of the circulation pump through the frequency converter (9), so as to control the flow rate of NH3 in the pipeline; Step S5: Record the pipeline pressure, temperature and flow rate through the first temperature transmitter (12-1), the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), the first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), the sixth differential pressure transmitter (16-6), and the first mass flowmeter (11-1); Step S6: When the temperature displayed by the ninth temperature transmitter (12-9) is the first temperature and the first pressure transmitter (10-1), the second pressure transmitter (10-2), and the third pressure transmitter (10-3) display 3 MPa, turn off the pneumatic booster pump (4), the second manual ball valve (3-2), and the first regulating valve (6-1); Step S7: Turn on the tracing heater (13), set the power of the tracing heater to a constant value, heat the liquid ammonia in the pipeline, record the temperature before heating through the first temperature transmitter (12-1), and record the temperature changes of each pipe section after heating through the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), and the ninth temperature transmitter (12-9). The first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), the sixth differential pressure transmitter (16-6), and the first mass flowmeter (11-1) collect the pipeline pressure and flow rate; Step S8: Change the frequency of the circulation pump (8) through the frequency converter (9), repeat Step S7, and explore the changes in the heat exchange of liquid ammonia under different flow rates; the pipe section where the tracing heater (13) is located is wrapped with a heat insulation layer. If the pressure in the pipeline is too high, relieve the pressure of the pipeline by opening the eighth pneumatic quick-opening and quick-closing valve (14-8) and the ninth pneumatic quick-opening and quick-closing valve (14-9), so as to finely adjust the temperature and pressure of NH3 in the pipeline; Step S9: Turn off the tracing heater (13) and wait for the temperature and pressure of NH3 in the pipeline to stabilize; Step S10: Open the sixth manual ball valve (3-6) and the eleventh manual ball valve (3-11), close the first pneumatic quick-opening and quick-closing valve (14-1) and the fifth pneumatic quick-opening and quick-closing valve (14-5), perform a pressure relief operation on an 80-meter test pipe section. Control the pressure relief rate by adjusting the opening of the electric ball valve (20). Record and collect the flow rate through the second mass flowmeter (11-2). Collect the changes in pipeline pressure and temperature through the first temperature transmitter (12-1), the second temperature transmitter (12-2), the third temperature transmitter (12-3), the fourth temperature transmitter (12-4), the fifth temperature transmitter (12-5), the sixth temperature transmitter (12-6), the seventh temperature transmitter (12-7), the eighth temperature transmitter (12-8), the first differential pressure transmitter (16-1), the second differential pressure transmitter (16-2), the third differential pressure transmitter (16-3), the fourth differential pressure transmitter (16-4), the fifth differential pressure transmitter (16-5), and the sixth differential pressure transmitter (16-6). Step S11: Keep the eleventh manual ball valve (3-11) open, open the first pneumatic quick-opening and quick-closing valve (14-1) and the fifth pneumatic quick-opening and quick-closing valve (14-5), fully open the electric ball valve (20), and perform a pressure relief on NH3 in the pipeline. Step S12: Close the circulation pump 8, the eleventh manual ball valve (3-11), the fifth manual ball valve (3-5), the sixth manual ball valve (3-6), the seventh manual ball valve (3-7), the eighth manual ball valve (3-8), the ninth manual ball valve (3-9), the tenth manual ball valve (3-10), and the third gate valve (7-3), save the experimental data, and end the experimental test.

3. The experimental method of a liquid ammonia horizontal pipeline experimental device according to claim 2, characterized in that In Step 2, set the temperature of the refrigerator (18) to 20°C.

4. The experimental method of a liquid ammonia horizontal pipeline experimental device according to claim 2, characterized in that In Step 4, the circulation pump (8) is a sliding vane pump, which provides power for the circulation of liquid ammonia in the loop.

5. The experimental method of a liquid ammonia horizontal pipeline experimental device according to claim 2, characterized in that In Step 5, the acquisition time step is 0.1 s.

6. The experimental method of a liquid ammonia horizontal pipeline experimental device according to claim 2, characterized in that, In Step 6, the first temperature is 20°C.

7. The experimental method of a liquid ammonia horizontal pipeline experimental device according to claim 2, characterized in that, In Step 7, the acquisition time step is 0.1 s.

8. The experimental method of a liquid ammonia horizontal pipeline experimental device according to claim 2, characterized in that, In Step 10, collect the flow rate and temperature changes, and the acquisition time step is 0.1 s for both.

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