A volatile gas treatment system and method for liquid ammonia storage and transportation

Abstract

The present invention relates to a volatile gas treatment system and method for liquid ammonia storage and transportation, including an insulated storage tank, a gas-liquid separator, a volatile gas compressor, a heat exchanger, a high-pressure liquid ammonia storage tank, a throttle valve, and a low-pressure liquid ammonia storage tank. A volatile gas collection pipeline is connected between the upper end of the insulated storage tank and the gas-liquid separator. The gas-liquid separator includes a gas outlet and a liquid outlet. The gas outlet of the gas-liquid separator, the volatile gas compressor, the heat exchanger, the high-pressure liquid ammonia storage tank, and the low-pressure liquid ammonia storage tank are sequentially connected by pipelines. The throttle valve is installed on the pipeline between the high-pressure liquid ammonia storage tank and the low-pressure liquid ammonia storage tank; the low-pressure liquid ammonia storage tank is connected to the inside of the insulated storage tank through a second return pipeline, and the liquid outlet of the gas-liquid separator is connected with a first return pipeline, and the first return pipeline is connected to the second return pipeline. The treatment system and method of the present invention treat the ammonia gas generated by volatilization and then return it to the insulated storage tank to prevent the cabin pressure in the insulated storage tank from exceeding the set safety value.

Description

Technical Field

[0001] The present invention relates to the technical field of ship engineering equipment, and particularly relates to a volatile gas treatment system and method for liquid ammonia storage and transportation. Background Art

[0002] Ammonia is easy to liquefy. Under one atmospheric pressure, gaseous ammonia can be cooled to -33°C, or pressurized to 0.7 - 0.8 MPa at room temperature, and ammonia gas can be liquefied into a colorless liquid (liquid ammonia). The volume of liquid ammonia is about 1 / 922 of the volume of the same amount of gaseous ammonia. Therefore, ammonia is mainly stored and transported in liquid form. The methods of storing and transporting ammonia can be divided into three types: full-pressure type, semi-cooled and semi-pressurized type, and full-cooled type. For different transportation methods, liquid ammonia storage tanks of different types, different design pressures, and different design temperatures need to be selected.

[0003] The full-cooled storage and transportation method has the characteristics of low cabin pressure and large single-cabin volume. The design pressure of its storage tank is usually 0.25 bar, and the maximum does not exceed 0.7 bar. Compared with storage tanks with higher design pressures of other types, the full-cooled storage tank is the most sensitive to pressure changes during operation. Therefore, it is necessary to control the storage tank pressure within the design range to prevent ammonia gas from overpressuring and causing emission accidents. An effective liquid ammonia storage and transportation volatile gas treatment system is required to effectively treat the volatile gas generated during the storage and transportation process to ensure the safety of facilities and personnel during the liquid ammonia storage and transportation process. Summary of the Invention

[0004] In order to control the cabin pressure during the liquid ammonia storage and transportation process, avoid overpressure of the cabin pressure, and ensure the safety of equipment and personnel, the present invention provides a volatile gas treatment system and method for liquid ammonia storage and transportation, which compresses and recirculates the volatile gas generated during the storage and transportation process to achieve the control of the cabin pressure.

[0005] The technical object of the present invention is achieved through the following technical solutions:

[0006] A volatile gas treatment system for liquid ammonia storage and transportation includes an insulated storage tank, a gas-liquid separator, a volatile gas compressor, a heat exchanger, a high-pressure liquid ammonia storage tank, a throttle valve, and a low-pressure liquid ammonia storage tank.

[0007] A volatile gas collection pipeline is connected between the upper end of the insulated storage tank and the gas-liquid separator. The gas-liquid separator includes a gas outlet and a liquid outlet. The gas outlet of the gas-liquid separator, the volatile gas compressor, the heat exchanger, the high-pressure liquid ammonia storage tank, and the low-pressure liquid ammonia storage tank are connected in sequence through pipelines. The throttle valve is installed on the pipeline between the high-pressure liquid ammonia storage tank and the low-pressure liquid ammonia storage tank;

[0008] The low-pressure liquid ammonia storage tank is connected to the inside of the insulated storage tank through a second return pipeline to the cabin. The liquid outlet of the gas-liquid separator is connected with a first return pipeline to the cabin, and the first return pipeline to the cabin is connected with the second return pipeline to the cabin.

[0009] Furthermore, the high-pressure liquid ammonia storage tank is also connected with a high-pressure pressure balance pipeline. One end of the high-pressure pressure balance pipeline is connected to the high-pressure liquid ammonia storage tank, and the other end of the high-pressure pressure balance pipeline is connected to the pipeline between the volatile gas compressor and the heat exchanger.

[0010] Furthermore, a low-pressure pressure balance pipeline is also connected between the low-pressure liquid ammonia storage tank and the gas-liquid separator.

[0011] Furthermore, the heat exchanger includes a first heat exchanger and a second heat exchanger. The first heat exchanger and the second heat exchanger are arranged in parallel, and one of the first heat exchanger and the second heat exchanger is selected. The first heat exchanger is an air-cooled heat exchanger, and the second heat exchanger is a liquid-cooled heat exchanger.

[0012] Furthermore, a three-way valve is installed on the pipeline between the volatile gas compressor and the heat exchanger. The three-way valve includes an inlet O, an outlet a, and an outlet b. The volatile gas compressor is connected to the inlet O through a pipeline, and the first heat exchanger and the second heat exchanger are respectively connected to the outlet a and the outlet b through pipelines.

[0013] Furthermore, the insulated storage tank is also provided with a pressure detection device for monitoring the pressure inside the insulated storage tank. The volatile gas compressor adjusts its load according to the pressure detected by the pressure detection device; when the pressure inside the insulated storage tank exceeds the set value, the volatile gas compressor operates, and when the pressure inside the insulated storage tank increases, the load of the volatile gas compressor increases; when the pressure inside the insulated storage tank decreases, the load of the volatile gas compressor decreases.

[0014] Furthermore, a liquid level control valve and a one-way check valve are also provided on the first return cabin pipeline. The liquid level control valve is also connected to a liquid level detection device for monitoring the liquid level height inside the gas-liquid separator. The liquid level control valve opens when the liquid level inside the gas-liquid separator exceeds the set value.

[0015] Furthermore, one end of the second return cabin pipeline extends to a position near the bottom of the insulated storage tank inside the insulated storage tank.

[0016] The present invention also provides a method for treating volatile gas for liquid ammonia storage and transportation, and the method includes:

[0017] Step 1: Separating the volatilized liquid ammonia from the upper inner end of the insulated storage tank storing liquid ammonia. The separated liquid ammonia flows back to the insulated storage tank, and the separated ammonia gas is pressurized and compressed;

[0018] Step 2: Cooling the pressurized and compressed ammonia gas through a heat exchanger to form liquid ammonia;

[0019] Step 3: After the liquid ammonia is depressurized, it flows back to the insulated storage tank.

[0020] Furthermore, in Step 2, air cooling or liquid cooling is used for heat exchange during heat exchange. When air cooling is performed for heat exchange, the generated wind during heat exchange is used for external heat supply.

[0021] Further, in step 3, liquid ammonia is temporarily stored in a high-pressure liquid ammonia storage tank. After being discharged from the high-pressure liquid ammonia storage tank, the pressure is reduced and then it is temporarily stored in a low-pressure liquid ammonia storage tank. Then, the liquid ammonia is refluxed from the low-pressure liquid ammonia storage tank into the insulation storage tank.

[0022] Further, when liquid ammonia enters the high-pressure liquid ammonia storage tank and the low-pressure liquid ammonia storage tank, air pressure balance is respectively carried out to reduce the resistance when the liquid ammonia enters.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The treatment system and treatment method of the present invention treat the ammonia gas generated by volatilization and then reflux it into the insulation storage tank, avoiding the cabin pressure in the insulation storage tank exceeding the set safety value.

[0025] 2. The refluxed liquid ammonia enters from the bottom of the insulation storage tank, and the static pressure of the liquid level height in the insulation storage tank is utilized to effectively reduce the rapid volatilization of the liquid ammonia returning to the insulation storage tank again, realizing the control of the cabin pressure in the insulation storage tank.

[0026] 3. In the present invention, different heat exchange media are adopted for the first heat exchanger and the second heat exchanger, and the hot air generated by air-cooled heat exchange can also be used for external heating, realizing the full utilization of energy. Description of the Drawings

[0027] Figure 1 is a schematic diagram of the composition of the volatilized gas treatment system for liquid ammonia storage and transportation of the present invention.

[0028] In the figure, 1. Insulation storage tank; 2. Gas-liquid separator; 3. Volatile gas compressor; 4. Three-way valve; 5. First heat exchanger; 6. Second heat exchanger; 7. High-pressure liquid ammonia storage tank; 8. Throttle valve; 9. Low-pressure liquid ammonia storage tank; 10. Liquid level sensor; 11. Liquid level control valve; 12. Check valve; 13. Pressure detection device;

[0029] L1. Volatile gas collection pipeline; L2. High-pressure pressure balance pipeline; L3. Low-pressure pressure balance pipeline; L4. First return cabin pipeline; L5. Second return cabin pipeline. Embodiment

[0030] The technical solution of the present invention will be further described below in conjunction with specific embodiments:

[0031] In this embodiment, the high pressure and low pressure mentioned are all relative pressures. After pressurization, it is high pressure relative to before pressurization, and low pressure before pressurization compared with after pressurization. After depressurization, it is low pressure compared with before depressurization, and high pressure before depressurization compared with after depressurization.

[0032] A volatilized gas treatment system for liquid ammonia storage and transportation, as Figure 1As shown in the figure, it includes an insulated storage tank 1, a gas-liquid separator 2, a volatile gas compressor 3, a heat exchanger, a high-pressure liquid ammonia storage tank 7, a throttle valve 8, and a low-pressure liquid ammonia storage tank 9.

[0033] Among them, the insulated storage tank 1 can be any one of the A-type, B-type, C-type, and thin-film type containment systems defined by the IMO (International Maritime Organization). The insulated storage tank 1 is arranged inside the hull structure for storing liquid ammonia. The gas-liquid separator 2 is coated with insulation and is used to collect and separate the volatile gas generated from the insulated storage tank. The volatile gas compressor 3 adopts variable frequency control and adjusts the speed and displacement of the compressor according to the pressure inside the insulated storage tank 1. The volatile gas compressor 3 can be a screw type or a piston type, with or without oil lubrication. When an oil-lubricated compressor is used, an oil-gas separator is arranged at the outlet of the compressor to prevent the lubricating oil from entering the insulated storage tank.

[0034] Preferably, the insulated storage tank 1 is also provided with a pressure detection device 13 for monitoring the pressure inside the insulated storage tank. The pressure detection device 13 is installed on the insulated storage tank 1. The pressure detection device is such as a pressure sensor. The volatile gas compressor 3 adjusts the load according to the pressure detected by the pressure detection device; when the pressure inside the insulated storage tank 1 exceeds the set value, the volatile gas compressor works. When the pressure inside the insulated storage tank 1 increases, the load of the volatile gas compressor 3 increases; when the pressure inside the insulated storage tank 1 decreases, the load of the volatile gas compressor 3 decreases.

[0035] A volatile gas collection pipeline L1 is connected between the upper end of the insulated storage tank 1 and the gas-liquid separator 2. The gas-liquid separator 2 includes a gas outlet and a liquid outlet. The gas outlet of the gas-liquid separator, the volatile gas compressor 3, the heat exchanger, the high-pressure liquid ammonia storage tank 7, and the low-pressure liquid ammonia storage tank 9 are connected in sequence through pipelines. The throttle valve is installed on the pipeline between the high-pressure liquid ammonia storage tank 7 and the low-pressure liquid ammonia storage tank 9.

[0036] The low-pressure liquid ammonia storage tank 9 is connected to the inside of the insulated storage tank 1 through a second return pipeline L5. The liquid outlet of the gas-liquid separator 2 is connected with a first return pipeline L4, and the first return pipeline L4 is connected with the second return pipeline L5.

[0037] The volatile ammonia gas inside the insulated storage tank 1 enters the gas-liquid separator 2 through the volatile gas collection pipeline L1 for gas-liquid separation. The separated volatile gas (ammonia gas) is pressurized and compressed after passing through the volatile gas compressor 3, and then cooled down through heat exchange in the heat exchanger to form high-pressure liquid ammonia and flow into the high-pressure liquid ammonia storage tank 7. The liquid ammonia in the high-pressure liquid ammonia storage tank 7 flows out through the pipeline and is throttled and depressurized by the throttle valve 8 to form low-pressure liquid ammonia. After the low-pressure liquid ammonia flows into the low-pressure liquid ammonia storage tank 9, it then flows back into the insulated storage tank 1. Preferably, one end of the second return pipeline L5 extends to a position near the bottom of the insulated storage tank 1 inside the insulated storage tank 1, and the low-pressure liquid ammonia flows back to the bottom inside the insulated storage tank 1. Under the static pressure of the liquid ammonia inside the insulated storage tank 1, the volatilization of the returned liquid ammonia can be reduced.

[0038] The high-pressure liquid ammonia storage tank 7 is also connected to a high-pressure pressure balance pipeline L2. One end of the high-pressure pressure balance pipeline L2 is connected to the high-pressure liquid ammonia storage tank 7, and the other end of the high-pressure pressure balance pipeline L2 is connected to the pipeline between the volatile gas compressor 3 and the heat exchanger, which can balance the air pressure at both ends of the high-pressure pressure balance pipeline and is conducive to the inflow of liquid ammonia into the high-pressure liquid ammonia storage tank 7.

[0039] Similarly, a low-pressure pressure balance pipeline L3 is also connected between the low-pressure liquid ammonia storage tank 9 and the gas-liquid separator 2, which can balance the air pressure at both ends of the low-pressure pressure balance pipeline L3 and is conducive to the inflow of liquid ammonia into the low-pressure insulated storage tank 9, and the low-pressure liquid ammonia reaches a saturated state in the low-pressure liquid ammonia storage tank 9.

[0040] Preferably, a liquid level control valve 11 and a one-way check valve 12 are also provided on the first return pipeline L4. The liquid level control valve 11 is also connected to a liquid level detection device for monitoring the liquid level height in the gas-liquid separator 2. When the liquid level in the gas-liquid separator exceeds the set value, the liquid level control valve 11 opens. The liquid level detection device such as the liquid level sensor 10 can be installed on the gas-liquid separator 2, and can be a float type liquid level sensor, a radar type liquid level sensor, etc. The liquid level control valve 11 can be a pneumatic valve or an electric valve, and is designed to be fail-open to ensure the safe operation of the system; the one-way check valve 12 can be a lift type, swing type or swing check valve to prevent the liquid ammonia from flowing back from the first return pipeline L4 to the gas-liquid separator 2.

[0041] Preferably, the heat exchanger includes a first heat exchanger 5 and a second heat exchanger 6. The first heat exchanger 5 and the second heat exchanger 6 are arranged in parallel, and the first heat exchanger 5 and the second heat exchanger 6 are selected alternatively. The first heat exchanger 5 is an air-cooled heat exchanger, and the second heat exchanger 6 is a liquid-cooled heat exchanger. A three-way valve 4 is installed on the pipeline between the volatile gas compressor 3 and the heat exchanger. The three-way valve includes an inlet O, an outlet a, and an outlet b. The volatile gas compressor 3 is connected to the inlet O through a pipeline, and the first heat exchanger and the second heat exchanger are respectively connected to the outlet a and the outlet b through pipelines. At this time, one end of the high-pressure pressure balance pipeline L2 is connected to the high-pressure liquid ammonia storage tank, and the other end of the high-pressure pressure balance pipeline L2 is connected to the pipeline between the volatile gas compressor 3 and the three-way valve 4.

[0042] When the first heat exchanger 5 is selected for heat exchange, the inlet O - outlet a is connected, and the fan is used to blow the air flow to take away the heat in the compressed volatile gas. The heat-exchanged air flow can be used for external heating. For example, when the temperature in the cabin is lower than 15°C, the heat-exchanged air flow is sent into the cabin for heating.

[0043] When the second heat exchanger 6 is selected for heat exchange, the inlet O - outlet b is connected, and the compressed volatile gas is cooled by the coolant. The coolant can be fresh water, seawater or ethylene glycol solution.

[0044] Based on the volatile gas treatment system for liquid ammonia storage and transportation in the above embodiments, this embodiment also provides a method for treating volatile gas for liquid ammonia storage and transportation, which includes:

[0045] Step 1: Liquid ammonia is loaded into the insulated storage tank 1. Under the action of the internal and external temperature difference, heat is introduced into the insulated storage tank 1 to generate volatile gas; the volatile gas accumulates in the upper space of the insulated storage tank 1, resulting in an increase in the gas space pressure in the insulated storage tank 1;

[0046] Under the action of the pressure difference, the volatile gas enters the gas-liquid separator 2 through the upper volatile gas collection pipeline L1 for gas-liquid separation. The separated ammonia gas is transported to the volatile gas compressor 3 for pressurization and compression treatment. The separated liquid ammonia is temporarily stored in the gas-liquid separator 2. When the liquid level height in the gas-liquid separator 2 reaches or exceeds the set value, the liquid level control valve 11 of the first return pipeline L4 opens, and the liquid ammonia in the gas-liquid separator 2 flows back to the bottom of the insulated storage tank 1 through the second return pipeline L5. When the liquid level height in the gas-liquid separator 2 is lower than the set value, the liquid level control valve 11 of the first return pipeline L4 closes.

[0047] After being compressed and pressurized by the volatile gas compressor 3, the pressure of the volatile gas increases (rises to about 20 bar) and its internal energy increases. If the compressor is an oil-lubricated type, an oil-gas separator needs to be set at the outlet of the volatile gas compressor 3 to add an oil removal operation.

[0048] Step II: The ammonia gas after pressurization and compression is cooled to form liquid ammonia through a heat exchanger; during heat exchange, air cooling or liquid cooling is used for heat exchange. When air cooling is used for heat exchange, the generated air is used for external heating, for example:

[0049] When the cabin temperature is low (the cabin ambient temperature is lower than 15°C), the first heat exchanger 5 cools the volatile gas by air cooling, and the hot air after heat exchange can be used to heat the cabin temperature;

[0050] When the cabin temperature is high (the cabin ambient temperature is not lower than 15°C), the second heat exchanger 6 cools the volatile gas by liquid cooling.

[0051] Step 3: The liquid ammonia returns to the insulated storage tank after pressure reduction, specifically including:

[0052] After heat exchange in the heat exchanger, the gaseous volatile gas is transformed into high-pressure liquid ammonia, which is in a subcooled state under the current pressure. The high-pressure liquid ammonia is temporarily stored in the high-pressure liquid ammonia storage tank 7;

[0053] After being discharged from the high-pressure liquid ammonia storage tank 7, it passes through the throttle valve 8 for throttle pressure reduction and is temporarily stored in the low-pressure liquid ammonia storage tank 9. When the liquid ammonia enters the high-pressure liquid ammonia storage tank 7 and the low-pressure liquid ammonia storage tank 9, gas pressure balance is carried out respectively to reduce the resistance when the liquid ammonia enters.

[0054] The low-pressure liquid ammonia in the low-pressure liquid ammonia storage tank 9 flows back into the insulated storage tank 1. The liquid ammonia is sent to the bottom inside the insulated storage tank 1 through the second return pipeline L5. Under the action of the liquid static pressure inside the insulated storage tank 1, the pressure at the bottom of the insulated storage tank 1 is higher than the pressure inside the low-pressure liquid ammonia storage tank 9. The pressure of the liquid ammonia returning to the insulated storage tank 1 increases and it is in a subcooled state, which can effectively reduce the re-evaporation of the liquid ammonia during the return voyage.

[0055] The processing system and method in this embodiment can not only be used for the storage and transportation of ammonia, but also for substances with boiling points similar to that of ammonia, such as propane, butane, etc.

[0056] This embodiment is only a further explanation of the present invention, rather than a limitation to the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A volatile gas treatment system for liquid ammonia storage and transportation, characterized in that, It includes an insulated storage tank, a gas-liquid separator, a volatile gas compressor, a heat exchanger, a high-pressure liquid ammonia storage tank, a throttle valve, and a low-pressure liquid ammonia storage tank. A volatile gas collection pipeline is connected between the upper end of the insulated storage tank and the gas-liquid separator. The gas-liquid separator includes a gas outlet and a liquid outlet. The gas outlet of the gas-liquid separator, the volatile gas compressor, the heat exchanger, the high-pressure liquid ammonia storage tank, and the low-pressure liquid ammonia storage tank are sequentially connected and arranged through pipelines. The throttle valve is installed on the pipeline between the high-pressure liquid ammonia storage tank and the low-pressure liquid ammonia storage tank. The low-pressure liquid ammonia storage tank is connected to the inside of the insulated storage tank through a second return pipeline. The liquid outlet of the gas-liquid separator is connected with a first return pipeline, and the first return pipeline is connected to the second return pipeline. The high-pressure liquid ammonia storage tank is also connected with a high-pressure pressure balance pipeline. One end of the high-pressure pressure balance pipeline is connected to the high-pressure liquid ammonia storage tank, and the other end of the high-pressure pressure balance pipeline is connected to the pipeline between the volatile gas compressor and the heat exchanger. A low-pressure pressure balance pipeline is also connected between the low-pressure liquid ammonia storage tank and the gas-liquid separator. The insulated storage tank is also provided with a pressure detection device for monitoring the pressure inside the insulated storage tank, and the volatile gas compressor adjusts the load according to the pressure detected by the pressure detection device.

2. The volatile gas treatment system for liquid ammonia storage and transportation according to claim 1, wherein The heat exchanger includes a first heat exchanger and a second heat exchanger. The first heat exchanger and the second heat exchanger are arranged in parallel, and one of the first heat exchanger and the second heat exchanger is selected. The first heat exchanger is an air-cooled heat exchanger, and the second heat exchanger is a liquid-cooled heat exchanger.

3. The volatile gas treatment system for liquid ammonia storage and transportation according to claim 2, wherein, A three-way valve is installed on the pipeline between the volatile gas compressor and the heat exchanger. The three-way valve includes an inlet O, an outlet a, and an outlet b. The volatile gas compressor is connected to the inlet O through a pipeline, and the first heat exchanger and the second heat exchanger are respectively connected to the outlet a and the outlet b through pipelines.

4. A volatile gas treatment system for liquid ammonia storage and transportation according to claim 1, characterized in that, After the pressure inside the insulated storage tank exceeds the set value, the volatile gas compressor works. When the pressure inside the insulated storage tank increases, the load of the volatile gas compressor increases; when the pressure inside the insulated storage tank decreases, the load of the volatile gas compressor decreases.

5. A volatile gas treatment system for liquid ammonia storage and transportation according to claim 1, characterized in that, A liquid level control valve and a one-way check valve are also provided on the first return pipeline. The liquid level control valve is also connected with a liquid level detection device for monitoring the liquid level height inside the gas-liquid separator. The liquid level control valve opens after the liquid level inside the gas-liquid separator exceeds the set value.

6. A volatile gas treatment system for liquid ammonia storage and transportation according to claim 1, characterized in that, One end of the second return pipeline extends to a position near the bottom of the insulated storage tank inside the insulated storage tank.

7. A method for treating volatile gas during liquid ammonia storage and transportation, which is implemented by using the volatile gas treatment system for liquid ammonia storage and transportation described in any one of claims 1-6, characterized in that The method includes: Step 1: Gas-liquid separation is carried out on the volatilized liquid ammonia from the upper end inside the insulated storage tank storing liquid ammonia. The separated liquid ammonia flows back to the insulated storage tank, and the separated ammonia gas is pressurized and compressed. Step 2: The pressurized and compressed ammonia gas is cooled through the heat exchanger to form liquid ammonia. Step 3: The liquid ammonia flows back to the insulated storage tank after pressure reduction.

8. A method for treating volatile gas for liquid ammonia storage and transportation according to claim 7, characterized in that, In Step 2, air cooling or liquid cooling is used for heat exchange during heat exchange. When air cooling is carried out for heat exchange, the generated air is used for external heat supply.

9. A method for treating volatile gas for liquid ammonia storage and transportation according to claim 7, characterized in that, In Step 3, the liquid ammonia is temporarily stored in the high-pressure liquid ammonia storage tank, discharged from the high-pressure liquid ammonia storage tank, then pressure-reduced and temporarily stored in the low-pressure liquid ammonia storage tank, and then the liquid ammonia flows back to the insulated storage tank from the low-pressure liquid ammonia storage tank.

10. A method for treating volatile gas for liquid ammonia storage and transportation according to claim 9, characterized in that, When the liquid ammonia enters the high-pressure liquid ammonia storage tank and the low-pressure liquid ammonia storage tank, air pressure balance is carried out respectively to reduce the resistance when the liquid ammonia enters.

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