Liquid ammonia filling system with overpressure protection and quantitative control and control method

Abstract

This application discloses a liquid ammonia refueling system and control method with overpressure protection and quantitative control. The system includes a liquid ammonia storage tank, a liquid ammonia supply valve, a liquid ammonia pump, a filling CNC valve, a gas-liquid separator, a liquid flow meter, a liquid ammonia receiving bottle, and a control system. The liquid ammonia storage tank is connected to the inlet of the liquid ammonia supply valve and the liquid ammonia pump. The outlet of the liquid ammonia pump is connected to the gas-liquid separator through the filling CNC valve. The separated liquid ammonia is fed into the liquid ammonia receiving bottle. A liquid flow meter is installed between the gas-liquid separator and the liquid ammonia receiving bottle. A gas ammonia CNC valve and a gas flow meter are installed between the liquid ammonia receiving bottle and the liquid ammonia storage tank. The control system is electrically connected to the filling CNC valve and the gas ammonia CNC valve, and can control the actual amount of liquid ammonia injected into the liquid ammonia receiving bottle. This invention improves refueling efficiency and achieves precise control of the refueling amount. Furthermore, it can address situations where there is a surge in pipeline pressure due to pump shutdown delays after pump shutdown or system blockage during liquid ammonia refueling.

Description

Technical Field

[0001] This invention relates to the field of ammonia energy equipment technology, specifically to a liquid ammonia filling system and control method with overpressure protection and quantitative control for filling liquid ammonia. Background Technology

[0002] Hydrogen's low energy density and difficulty in liquefaction lead to high costs in its storage and transportation, hindering the development of hydrogen energy technology. Ammonia, on the other hand, is an ideal hydrogen carrier due to its carbon-free composition, high hydrogen content (17.6 wt%), high mass energy density (22.5 MJ / kg), high volumetric energy density (11.5 MJ / L), low boiling point, and easy liquefaction under pressure at room temperature. Therefore, using ammonia as a "zero-carbon" technology route for energy or hydrogen storage is an important technological approach to achieving the "dual-carbon" goal. In 2023, GAC Group released the world's first ammonia engine for passenger vehicles, which uses liquid ammonia as fuel and technically achieves reliable in-cylinder ignition and stable engine operation. In 2024, China's first "ammonia-hydrogen" fuel cell-powered environmentally friendly ship successfully completed its maiden voyage. In the same year, the Norwegian Citizen Safety Authority granted a safety permit for a planned ammonia refueling facility at its Floresfjord base in Norway, approving the world's first ammonia refueling terminal. Against the backdrop of the booming development of ammonia energy applications, ammonia storage and transportation systems, characterized by safety, reliability, continuity, and low energy consumption, will usher in new development opportunities. This also places higher demands on the refueling process during ammonia storage and transportation. Most existing liquid ammonia refueling technologies use single-phase liquid pipelines with vent valves. Due to the characteristics of liquid ammonia, the existence of liquid ammonia vaporization can affect the accuracy of metering during the refueling process and poses a risk of overpressure in the refueling pipeline. Therefore, there is an urgent need to develop and implement a liquid ammonia filling scheme that can accurately meter while ensuring safety.

[0003] Chinese patent CN117739619A discloses a ship ammonia vapor reliquefaction system and its control method, including a liquid ammonia storage tank, a heat exchanger, a liquid ammonia pump unit, and a condensation system. The BOG outlet of the liquid ammonia storage tank is connected to the ammonia inlet of the heat exchanger, the liquid ammonia outlet of the heat exchanger is connected to the liquid ammonia pump unit, the liquid ammonia pump unit is connected to the liquid ammonia storage tank, and the condensation system is connected to the heat exchanger. The condensation system is used to cool the ammonia vapor in the heat exchanger, so that the ammonia vapor in the heat exchanger condenses into liquid ammonia. The liquid ammonia pump unit is used to transport the liquid ammonia in the heat exchanger to the liquid ammonia storage tank and reduce the pressure in the heat exchanger, so that the ammonia vapor in the liquid ammonia storage tank is drawn into the heat exchanger under the action of pressure difference. The ship's ammonia vapor reliquefaction system eliminates the need for an ammonia compressor, reducing equipment and operating costs while offering high reliquefaction efficiency. However, the system cannot precisely control the amount of liquid ammonia or ammonia gas added during the preparation and reflux processes. Furthermore, it cannot simultaneously prevent and mitigate potential safety hazards, such as pipeline overpressure, during the preparation and reflux processes. Summary of the Invention

[0004] To address the shortcomings of existing ammonia vapor liquefaction systems and ammonia storage and transportation processes, such as the inability to accurately control the amount of liquid ammonia and ammonia gas used, and the lack of synchronous safety precautions and hazard monitoring during the filling process, this paper provides a liquid ammonia filling system and control method that can accurately calculate the amount of liquid ammonia and ammonia gas added during the filling process, and simultaneously prevent and monitor potential safety hazards, featuring overpressure protection and quantitative control.

[0005] The technical solution adopted by this invention to solve its technical problem is: a liquid ammonia filling system with overpressure protection and quantitative control, comprising a liquid ammonia storage tank, a liquid ammonia supply valve, a liquid ammonia pump, a filling CNC valve, a gas-liquid separator, a liquid flow meter, a liquid ammonia receiving bottle, and a control system. The liquid ammonia outlet of the liquid ammonia storage tank is connected sequentially to the inlet of the liquid ammonia supply valve and the liquid ammonia pump. The outlet of the liquid ammonia pump is connected to the gas-liquid separator through the filling CNC valve. The gas-liquid separator is used to separate ammonia gas and liquid ammonia. The separated liquid ammonia is then fed into the gas-liquid separator. A liquid ammonia receiving bottle is introduced into the liquid ammonia receiving bottle, and a liquid flow meter is installed between the gas-liquid separator and the liquid ammonia receiving bottle; the gas phase outlet of the liquid ammonia receiving bottle is connected to the gas phase reflux port of the liquid ammonia storage tank; a gas ammonia digital control valve and a gas flow meter are installed between the gas phase outlet of the liquid ammonia receiving bottle and the gas phase reflux port of the liquid ammonia storage tank; the control system is electrically connected to the filling digital control valve and the gas ammonia digital control valve, and the control system can control the flow rate of liquid ammonia discharged from the liquid ammonia pump, as well as the actual amount of liquid ammonia added into the liquid ammonia receiving bottle after separation by the gas-liquid separator.

[0006] Furthermore, a first gaseous ammonia check valve is installed between the gas phase outlet of the gas-liquid separator and the gas phase reflux port of the liquid ammonia storage tank, and a second gaseous ammonia check valve is installed between the gas flow meter and the gas phase reflux port of the liquid ammonia storage tank.

[0007] Furthermore, the control system is electrically connected to the liquid flow meter and the gas flow meter. The control system can control the actual amount of liquid ammonia added to the liquid ammonia receiving bottle by adjusting the opening degree of the corresponding filling control valve and the gas ammonia control valve based on the data difference between the liquid flow meter and the gas flow meter.

[0008] Furthermore, the outlet of the liquid ammonia pump is connected to the liquid phase reflux port of the liquid ammonia storage tank, and a reflux control valve and a liquid ammonia check valve are sequentially installed between the outlet of the liquid ammonia pump and the liquid phase reflux port of the liquid ammonia storage tank.

[0009] Furthermore, the control system is electrically connected to the reflux control valve. The control system can control the flow rate of the liquid phase reflux port that is discharged from the outlet of the liquid ammonia pump and returned to the liquid ammonia storage tank by adjusting the opening degree of the reflux control valve based on the data difference between the liquid flow meter and the gas flow meter.

[0010] Furthermore, it also includes a first safety valve, a second safety valve, a third safety valve, and a pipeline overpressure treatment device; the liquid flow meter is also connected to the pipeline overpressure device, a first safety valve is installed between the liquid flow meter and the pipeline overpressure device, the gas phase outlet of the liquid ammonia receiving bottle is connected to the pipeline overpressure device, a second safety valve is installed between the gas phase outlet of the liquid ammonia receiving bottle and the pipeline overpressure device, a reflux CNC valve is connected to the pipeline overpressure device, and a third safety valve is installed between the reflux CNC valve and the pipeline overpressure treatment device.

[0011] Furthermore, the gas phase outlet of the gas-liquid separator is connected to the gas phase reflux port of the liquid ammonia storage tank.

[0012] This invention also discloses a control method for a liquid ammonia refueling system with overpressure protection and quantitative control, comprising the following steps:

[0013] Step 1: Open the liquid ammonia supply valve to allow liquid ammonia to flow from the liquid ammonia storage tank and into the liquid ammonia pump; set the preset filling volume of the liquid ammonia receiving bottle;

[0014] Step 2: Open the filling control valve, and the liquid ammonia pump will guide the liquid ammonia flowing from the liquid ammonia storage tank into the gas-liquid separator;

[0015] Step 3: The gas-liquid separator separates the liquid ammonia from the residual gaseous ammonia, and the separated liquid ammonia flows through the liquid flow meter and is discharged into the liquid ammonia receiving bottle;

[0016] Step 4: The liquid ammonia receiving bottle further discharges the residual gaseous ammonia and returns it to the gas phase reflux port of the liquid ammonia storage tank after passing through the gas ammonia digital control valve and gas flow meter;

[0017] Step 5: Subtract the value of the gas flow meter from the value of the liquid flow meter in Step 3 to obtain the actual amount of liquid ammonia added. Compare the actual amount of ammonia added with the preset amount of ammonia added in Step 1.

[0018] Step Six: Based on the comparison results between the actual filling amount and the preset filling amount in Step Five, adjust the opening of the filling control valve and the gaseous ammonia control valve respectively until the actual filling amount is equal to the preset filling amount.

[0019] Furthermore, in step three, the separated gaseous ammonia is discharged from the gas-liquid separation bottle and reintroduced into the gas phase reflux port of the liquid ammonia storage tank.

[0020] This invention discloses a liquid ammonia filling system with overpressure protection and quantitative control. By simultaneously controlling the filling CNC valve, the gaseous ammonia CNC valve, and the reflux CNC valve, the flow direction and flow rate of liquid and gaseous ammonia within the system are adjusted respectively. Combined with liquid and gas flow meters, the filling amount of liquid ammonia is accurately controlled, reducing damage and waste caused by overfilling. Excess liquid ammonia is also effectively reused, reducing system energy consumption. By connecting the gas-liquid separator, the liquid ammonia receiving bottle, and the gas phase reflux port of the liquid ammonia storage tank to the pipeline overpressure treatment equipment, the liquid ammonia is... The ammonia reflux protection pipeline is connected to the pipeline overpressure treatment equipment, and the liquid ammonia flow meter 6 is connected to the pipeline overpressure treatment equipment through the liquid ammonia filling pipeline overpressure treatment pipeline. Correspondingly, a first safety valve, a second safety valve, and a third safety valve are installed. While accurately controlling the liquid ammonia injection volume, it effectively prevents damage caused by excessive liquid ammonia or gaseous ammonia pressure. It also allows excess liquid ammonia or gaseous ammonia to flow back to the liquid ammonia storage tank when the liquid ammonia or gaseous ammonia pressure is too high, thereby improving the reuse rate of ammonia, improving the overall liquid ammonia collection efficiency of the system, and ensuring the safe operation of the system. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the liquid ammonia refueling system with overpressure protection and quantitative control described in this invention. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, the liquid ammonia filling system with overpressure protection and quantitative control according to the present invention includes a liquid ammonia storage tank 1, a liquid ammonia supply valve 2, a liquid ammonia pump 3, a filling CNC valve 4, a gas-liquid separator 5, a liquid flow meter 6, a liquid ammonia receiving bottle 7, and a control system.

[0025] The liquid ammonia outlet of the liquid ammonia storage tank 1 is sequentially connected to the liquid ammonia supply valve 2 and the inlet of the liquid ammonia pump 3. The outlet of the liquid ammonia pump 3 is connected to the gas-liquid separator 5 through the filling CNC valve 4. The gas-liquid separator 5 is used to separate ammonia gas and liquid ammonia. The separated liquid ammonia is fed into the liquid ammonia receiving bottle 7. A liquid flow meter 6 is installed between the gas-liquid separator 5 and the liquid ammonia receiving bottle 7. The gas phase outlet of the liquid ammonia receiving bottle 7 is connected to the gas phase reflux port of the liquid ammonia storage tank 1. A gas ammonia CNC valve 8 and a gas flow meter 9 are installed between the gas phase outlet of the liquid ammonia receiving bottle and the gas phase reflux port of the liquid ammonia storage tank 1.

[0026] The control system is electrically connected to the filling CNC valve 4 and the gaseous ammonia CNC valve 8. The control system can control the flow direction and flow rate of liquid ammonia discharged from the liquid ammonia pump 3, as well as the amount of liquid ammonia that enters the liquid ammonia receiving bottle 7 after being separated by the gas-liquid separator 5.

[0027] This liquid ammonia filling system, equipped with overpressure protection and quantitative control, simultaneously controls the filling CNC valve, the gaseous ammonia CNC valve, and the reflux CNC valve to regulate the flow direction and flow rate of liquid ammonia and gaseous ammonia in the system. Combined with liquid flow meters and gas flow meters, it achieves accurate control of the liquid ammonia filling amount, reducing damage and waste caused by overfilling. At the same time, it also enables effective reuse of excess liquid ammonia, reducing system energy consumption.

[0028] like Figure 1As shown, the liquid ammonia storage tank 1 has its liquid ammonia outlet connected to the liquid ammonia supply valve 2, which in turn connects to the inlet of the liquid ammonia pump 3. By adjusting the opening of the liquid ammonia supply valve 2, the amount of liquid ammonia discharged from the liquid ammonia outlet of the liquid ammonia storage tank 1 and entering the liquid ammonia pump 3 is controlled. The outlet of the liquid ammonia pump 3 is connected to the filling numerical control valve 4 and the gas-liquid separator 5 via a liquid ammonia filling pipeline. Both the filling numerical control valve 4 and the gas-liquid separator 5 are located on the liquid ammonia filling pipeline. The liquid ammonia discharged from the liquid ammonia storage tank 1, after being pressurized by the liquid ammonia pump 3, enters the gas-liquid separator 5 via the liquid ammonia filling pipeline and the filling numerical control valve 4. The gas-liquid separator 5 is used to separate the gaseous ammonia and liquid ammonia in the introduced liquid ammonia. The liquid ammonia flows out from the liquid phase outlet of the gas-liquid separator 5 and enters the liquid phase port of the liquid ammonia receiving bottle 7 via the liquid flow meter 6 connected to the liquid phase outlet, thus completing the collection of liquid ammonia. A small amount of gaseous ammonia in the separated liquid ammonia is discharged from the gas phase outlet of the gas-liquid separator 5. In order to improve the reuse rate of gaseous ammonia and reduce the energy consumption of the system, preferably, the gas phase outlet of the gas-liquid separator 5 is connected to the gas phase return port of the liquid ammonia storage tank 1, and a first gaseous ammonia one-way valve 10 is provided between the gas phase outlet of the gas-liquid separator 5 and the gas phase return port of the liquid ammonia storage tank 1, so that the gaseous ammonia discharged after separation can re-enter the liquid ammonia storage tank 1 for further liquid ammonia circulation.

[0029] To better utilize the gaseous ammonia from the separation and collection process of liquid ammonia, promote the rational recovery and utilization of ammonia, and reduce energy waste and loss, specifically, the gas phase outlet of the liquid ammonia receiving bottle 7 is connected to the gas phase reflux port of the liquid ammonia storage tank 1. A gaseous ammonia digital control valve 8 and a gas flow meter 9 are sequentially installed between the gas phase outlet of the liquid ammonia receiving bottle 7 and the gas phase reflux port of the liquid ammonia storage tank 1. The gas phase outlet of the liquid ammonia receiving bottle 7 is connected to the gas phase reflux port of the liquid ammonia storage tank 1 through a gaseous ammonia reflux and quantitative control pipeline. The gaseous ammonia digital control valve 8 and the gas flow meter 9 are connected in series. All gas flow meters 9 are installed on the gaseous ammonia reflux and quantitative control pipeline; more specifically, a second gaseous ammonia one-way valve 11 is installed between the gas flow meter 9 and the gas phase reflux port of the liquid ammonia storage tank 1. The residual gaseous ammonia discharged from the liquid ammonia receiving bottle 7 flows out from the gas phase outlet of the liquid ammonia receiving bottle 7, passes through the gaseous ammonia reflux and quantitative control pipeline, and after passing through the gaseous ammonia digital control valve 8 and the gas flow meter 9, it flows into the gas phase reflux port of the liquid ammonia storage tank 1 after passing through the second gaseous ammonia one-way valve 11, thus completing the effective recovery and reuse of gaseous ammonia in the liquid ammonia receiving bottle 7.

[0030] To more accurately control the amount of liquid ammonia added from the gas-liquid separator 5 into the liquid ammonia receiving bottle 7, reducing damage and energy waste caused by excessive pressure due to overfilling, and low separation efficiency due to insufficient filling, the control system is specifically electrically connected to the liquid flow meter 6 and the gas flow meter 9. When the liquid ammonia separated by the gas-liquid separator 5 is discharged from the separator 5, passes through the liquid flow meter 6, and enters the liquid ammonia receiving bottle 7, the residual gaseous ammonia in the liquid ammonia is discharged through the gas phase outlet of the liquid ammonia receiving bottle 7 and passes through the gas flow meter 9. The control system can adjust the flow rate based on the liquid flow meter readings. The data corresponding to the liquid flow meter 6 and the gas flow meter 9 are used to calculate the actual liquid ammonia filling amount of the liquid ammonia receiving bottle 7 by the data difference between the liquid flow meter 6 and the gas flow meter 9. Based on the comparison between the calculated actual liquid ammonia filling amount and the preset liquid ammonia filling amount, the control system adjusts the opening degree of the electrically connected filling numerical control valve 4 and the gas ammonia numerical control valve 8 to simultaneously adjust the flow rate of liquid ammonia discharged from the liquid ammonia pump 3 into the gas-liquid separator 5 and the flow rate of gas ammonia discharged from the liquid ammonia receiving bottle 7, thereby realizing quantitative control of the liquid ammonia filling situation in the liquid ammonia receiving bottle 7 and improving the accuracy of liquid ammonia filling amount.

[0031] In order to reduce equipment damage caused by excessive pressure during the liquid ammonia filling process and effectively prevent safety hazards, when the liquid ammonia filling volume reaches or exceeds the preset filling volume, the outlet of the liquid ammonia pump 3 is also connected to the liquid phase reflux port of the liquid ammonia storage tank 1. A reflux control valve 12 and a liquid ammonia one-way valve 13 are sequentially installed between the outlet of the liquid ammonia pump 3 and the liquid phase reflux port of the liquid ammonia storage tank 1. The outlet of the liquid ammonia pump 3 and the liquid phase reflux port of the liquid ammonia storage tank 1 are connected through a liquid ammonia reflux protection pipeline. The liquid ammonia reflux protection pipeline is also connected to the liquid ammonia filling pipeline used to connect the filling control valve 4 and the gas-liquid separator 5. Both the control valve 12 and the liquid ammonia check valve 13 are installed on the liquid ammonia reflux protection pipeline. When the actual liquid ammonia filling amount reaches or even exceeds the preset liquid ammonia filling amount, the control system closes the filling control valve 4 and simultaneously opens the reflux control valve 12. The excess liquid ammonia in the liquid ammonia filling pipeline between the liquid ammonia pump 3 and the filling control valve 4 during the pump stop delay after the liquid ammonia pump 3 is shut down is refluxed back to the liquid phase reflux port of the liquid ammonia storage tank 1 through the liquid ammonia reflux protection pipeline, after flowing through the reflux control valve 12 and the liquid ammonia check valve 13. This prevents overpressure in the liquid ammonia filling pipeline to ensure system safety. While ensuring system safety, the excess liquid ammonia can be reused, thus improving the liquid ammonia reuse rate.

[0032] To reduce pipeline blockage and damage caused by excessive internal pressure during liquid ammonia flow collection or reflux, preferably, the liquid ammonia filling system with overpressure protection and quantitative control further includes three safety valves and a pipeline overpressure treatment device 17. An overpressure treatment pipeline for liquid ammonia filling is also provided in the middle of the pipeline connecting the liquid flow meter 6 and the liquid ammonia receiving bottle 7. This overpressure treatment pipeline is connected to the pipeline overpressure treatment device 17, and a first safety valve 13 is installed on the liquid ammonia filling pipeline overpressure treatment pipeline. The gaseous ammonia reflux and quantitative control... The ammonia recirculation and metering control pipeline is connected to the overpressure treatment pipeline of the ammonia recirculation and metering control pipeline. The overpressure treatment pipeline of the ammonia recirculation and metering control pipeline is connected to the overpressure treatment device 17. A second safety valve 14 is installed on the ammonia recirculation and metering control pipeline overpressure treatment pipeline. The liquid ammonia recirculation protection pipeline is connected to the overpressure treatment device 17 through the liquid ammonia recirculation protection pipeline overpressure treatment pipeline. A third safety valve 15 is installed on the liquid ammonia recirculation protection pipeline overpressure treatment pipeline. The liquid ammonia discharged from the gas-liquid separator and entering the liquid ammonia receiving bottle 7 is pressurized. When the pressure is too high, the first safety valve 13 located on the overpressure treatment pipeline of the liquid ammonia filling pipeline is opened, allowing the excess liquid ammonia to be discharged from the liquid flow meter 6 through the overpressure treatment pipeline and enter the connected pipeline overpressure treatment equipment 17, reducing the damage to the equipment caused by excessive liquid ammonia pressure; when the pressure of the gaseous ammonia discharged from the liquid ammonia receiving bottle 7, flowing through the gaseous ammonia reflux and metering control pipeline into the gas phase reflux port of the liquid ammonia storage tank 1, is too high, the second safety valve 14 located on the overpressure treatment pipeline of the ammonia reflux and metering control pipeline is opened. Excess ammonia gas is allowed to enter the ammonia reflux and metering control pipeline overpressure treatment line through the second safety valve 14, and finally enter the pipeline overpressure treatment equipment 17. When the liquid ammonia pressure in the liquid phase reflux port of the liquid ammonia storage tank 1 through the liquid ammonia reflux protection line is too high, the third safety valve 15 located on the liquid ammonia reflux protection pipeline overpressure treatment line is opened, allowing some of the liquid ammonia in the liquid ammonia reflux protection line to enter the pipeline overpressure treatment equipment 17 through the liquid ammonia reflux protection pipeline overpressure treatment line, ensuring the safety of system components.

[0033] By connecting the gas-liquid separator 5, the liquid ammonia receiving bottle 7, and the liquid ammonia storage tank 1 to the pipeline overpressure treatment equipment, connecting the liquid ammonia reflux protection pipeline to the pipeline overpressure treatment equipment, and connecting the liquid ammonia flow meter 6 to the pipeline overpressure treatment equipment through the liquid ammonia filling pipeline overpressure treatment pipeline, and by setting up a first safety valve 13, a second safety valve 14, and a third safety valve 15 accordingly, the liquid ammonia injection volume is accurately controlled, and damage caused by excessive liquid ammonia or gaseous ammonia pressure is effectively prevented. Furthermore, when the liquid ammonia or gaseous ammonia pressure is too high, excess liquid ammonia or gaseous ammonia can flow back to the liquid ammonia storage tank, improving the ammonia reuse rate and the overall system's liquid ammonia collection efficiency while ensuring safe system operation.

[0034] This application also discloses a control method for a liquid ammonia refueling system with overpressure protection and quantitative control, characterized by comprising the following steps:

[0035] Step 1: Open the liquid ammonia supply valve to allow liquid ammonia to flow from the liquid ammonia storage tank and into the liquid ammonia pump; set the preset filling volume of the liquid ammonia receiving bottle;

[0036] Step 2: Open the filling control valve, and the liquid ammonia pump will guide the liquid ammonia flowing from the liquid ammonia storage tank into the gas-liquid separator;

[0037] Step 3: The gas-liquid separator separates the liquid ammonia from the residual gaseous ammonia and directs the separated gaseous ammonia into the gas phase reflux port of the liquid ammonia storage tank. The separated liquid ammonia then flows through the liquid flow meter and is discharged into the liquid ammonia receiving bottle.

[0038] Step 4: The liquid ammonia receiving bottle further discharges the residual gaseous ammonia and returns it to the gas phase reflux port of the liquid ammonia storage tank through the gaseous ammonia digital control valve;

[0039] Step 5: Subtract the value of the gas flow meter from the value of the liquid flow meter in Step 3 to obtain the actual amount of liquid ammonia added. Compare the actual amount of ammonia added with the preset amount of ammonia added in Step 1.

[0040] Step Six: Based on the comparison results between the actual filling amount and the preset filling amount in Step Five, adjust the opening of the filling control valve and the gaseous ammonia control valve respectively until the actual filling amount is equal to the preset filling amount.

[0041] In step three, the separated gaseous ammonia is discharged from the gas-liquid separator bottle and reintroduced into the gas phase reflux port of the liquid ammonia storage tank. An overpressure treatment pipeline for liquid ammonia filling is installed between the gas-liquid separator and the liquid ammonia receiving bottle. A first safety valve is installed on this pipeline, which is connected to an overpressure treatment device. When the pressure of the liquid ammonia in the receiving bottle discharged from the gas-liquid separator is too high, the first safety valve on the overpressure treatment pipeline is opened, allowing some liquid ammonia to be discharged through the pipeline and introduced into the overpressure treatment device, thereby reducing the damage to the system caused by excessive liquid ammonia pressure. In step three or four, the gas phase reflux port of the liquid ammonia storage tank is connected to the gaseous ammonia reflux and quantitative control pipeline. This pipeline is connected to the overpressure treatment device, and a second safety valve is installed on the gaseous ammonia reflux and quantitative control pipeline. When the separated gaseous ammonia is introduced into the liquid ammonia storage tank, if the gaseous ammonia pressure is too high during the introduction process, in order to reduce the damage to the equipment caused by excessive pressure during the introduction of gaseous ammonia, the second safety valve located on the gaseous ammonia reflux and quantitative control pipeline is opened, and part of the gaseous ammonia is introduced into the pipeline overpressure treatment equipment. In step six, the outlet of the liquid ammonia pump is also connected to the liquid phase reflux port of the liquid ammonia storage tank. A reflux digital control valve and a liquid ammonia one-way valve are sequentially installed between the outlet of the liquid ammonia pump and the liquid phase reflux port of the liquid ammonia storage tank. If the actual filling amount is greater than the preset filling amount, the opening degree of the reflux digital control valve is increased, and the opening degree of the filling digital control valve and the gaseous ammonia digital control valve is decreased or closed, so that part of the liquid ammonia discharged from the liquid ammonia pump is reintroduced into the liquid ammonia reflux port of the liquid ammonia storage tank through the reflux digital control valve. This reduces the damage to the equipment and also improves the liquid ammonia reuse rate of the system, and also ensures that the actual filling amount of liquid ammonia in the liquid ammonia receiving bottle is equal to the preset filling amount.

[0042] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A liquid ammonia filling system with overpressure protection and quantitative control, comprising a liquid ammonia storage tank, a liquid ammonia supply valve, a liquid ammonia pump, a filling CNC valve, a gas-liquid separator, a liquid flow meter, a liquid ammonia receiving bottle, and a control system, characterized in that: The liquid ammonia outlet of the liquid ammonia storage tank is sequentially connected to the liquid ammonia supply valve and the inlet of the liquid ammonia pump. The outlet of the liquid ammonia pump is connected to the gas-liquid separator through the filling CNC valve. The gas-liquid separator is used to separate ammonia gas and liquid ammonia. The separated liquid ammonia is fed into the liquid ammonia receiving bottle. A liquid flow meter is installed between the gas-liquid separator and the liquid ammonia receiving bottle. The gas phase outlet of the liquid ammonia receiving bottle is connected to the gas phase reflux port of the liquid ammonia storage tank. A gas ammonia CNC valve and a gas flow meter are installed between the gas phase outlet of the liquid ammonia receiving bottle and the gas phase reflux port of the liquid ammonia storage tank. The control system is electrically connected to the filling CNC valve and the gaseous ammonia CNC valve. The control system can control the flow rate of liquid ammonia discharged from the liquid ammonia pump, as well as the actual amount of liquid ammonia added into the liquid ammonia receiving bottle after separation by the gas-liquid separator. The control system is also electrically connected to the liquid flow meter and the gas flow meter. The control system can control the amount of liquid ammonia added to the liquid ammonia receiving bottle by adjusting the opening degree of the filling CNC valve and the gas ammonia CNC valve according to the data difference between the liquid flow meter and the gas flow meter. The gas phase outlet of the gas-liquid separator is connected to the gas phase reflux port of the liquid ammonia storage tank.

2. The liquid ammonia refueling system with overpressure protection and quantitative control according to claim 1, characterized in that: A first ammonia check valve is provided between the gas phase outlet of the gas-liquid separator and the gas phase reflux port of the liquid ammonia storage tank, and a second ammonia check valve is provided between the gas flow meter and the gas phase reflux port of the liquid ammonia storage tank.

3. The liquid ammonia refueling system with overpressure protection and quantitative control according to claim 1, characterized in that: The outlet of the liquid ammonia pump is connected to the liquid phase reflux port of the liquid ammonia storage tank, and a reflux control valve and a liquid ammonia check valve are sequentially installed between the outlet of the liquid ammonia pump and the liquid phase reflux port of the liquid ammonia storage tank.

4. A liquid ammonia refueling system with overpressure protection and quantitative control according to claim 3, characterized in that: The control system is also electrically connected to the reflux control valve. The control system can control the flow rate of the liquid phase reflux port that is discharged from the outlet of the liquid ammonia pump and flows back to the liquid ammonia storage tank by adjusting the opening degree of the reflux control valve based on the data difference between the liquid flow meter and the gas flow meter.

5. A liquid ammonia refueling system with overpressure protection and quantitative control according to claim 3, characterized in that: It also includes a first safety valve, a second safety valve, a third safety valve, and a pipeline overpressure treatment device; the liquid flow meter is also connected to the pipeline overpressure treatment device, a first safety valve is provided between the liquid flow meter and the pipeline overpressure treatment device, the gas phase outlet of the liquid ammonia receiving bottle is connected to the pipeline overpressure treatment device, a second safety valve is provided between the gas phase outlet of the liquid ammonia receiving bottle and the pipeline overpressure treatment device, the reflux CNC valve is connected to the pipeline overpressure treatment device, and a third safety valve is provided between the reflux CNC valve and the pipeline overpressure treatment device.

6. A control method for a liquid ammonia refueling system with overpressure protection and quantitative control as described in any one of claims 1 to 5, characterized in that: Includes the following steps: Step 1: Open the liquid ammonia supply valve to allow liquid ammonia to flow from the liquid ammonia storage tank and into the liquid ammonia pump; set the preset filling volume of the liquid ammonia receiving bottle; Step 2: Open the filling control valve, and the liquid ammonia pump will guide the liquid ammonia flowing from the liquid ammonia storage tank into the gas-liquid separator; Step 3: The gas-liquid separator separates the liquid ammonia from the residual gaseous ammonia, and the separated liquid ammonia flows through the liquid flow meter and is discharged into the liquid ammonia receiving bottle; Step 4: The liquid ammonia receiving bottle further discharges the residual gaseous ammonia and returns it to the gas phase reflux port of the liquid ammonia storage tank after passing through the gas ammonia digital control valve and gas flow meter; Step 5: Subtract the value of the gas flow meter from the value of the liquid flow meter in Step 3 to obtain the actual amount of liquid ammonia added. Compare the actual amount of ammonia added with the preset amount of ammonia added in Step 1. Step Six: Based on the comparison results between the actual filling amount and the preset filling amount in Step Five, adjust the opening of the filling CNC valve and the gaseous ammonia CNC valve respectively until the actual filling amount is equal to the preset filling amount; In step three, the separated gaseous ammonia is discharged from the gas-liquid separation bottle and reintroduced into the gas phase reflux port of the liquid ammonia storage tank.

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