High-pressure liquid ammonia-dimethyl ether mixed fuel supply system and control method

Abstract

The invention provides a high-pressure liquid ammonia-dimethyl ether mixed fuel supply system and a control method, and the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system comprises a gas supply system for providing ammonia gas and dimethyl ether, a gas mixing system for uniformly mixing the ammonia gas and dimethyl ether gas, and a pressurization system for pressurizing the mixed ammonia-dimethyl ether to liquefy the mixed ammonia-dimethyl ether, and an injection system for introducing liquefied ammonia-dimethyl ether into the engine. The mixed ammonia gas and dimethyl ether are used as fuel, the dimethyl ether is used for reducing the ignition energy of the fuel, and the combustion efficiency of the fuel is improved. And meanwhile, the characteristic that liquid ammonia and liquid dimethyl ether are good in mutual solubility is utilized, and an original double-injection system is changed into a single-injection system, so that the pipeline structure is simplified, and the manufacturing and maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of engines, and in particular to a high-pressure liquid ammonia-dimethyl ether mixed fuel supply system and a control method. Background Art

[0002] Under the dual pressures of global warming and the depletion of oil resources, research on renewable, clean, zero-carbon energy has become an important way to achieve energy conservation and emission reduction in internal combustion engines. Ammonia fuel will play an important role in the future energy system due to its zero-carbon emissions, high energy density, convenient storage and transportation, environmental protection characteristics, technological maturity and economic advantages. These advantages make ammonia fuel an ideal choice to replace traditional fossil fuels, and it will show great potential and value in a variety of application scenarios.

[0003] There are indeed a series of challenges when using ammonia as a fuel in internal combustion engines. First, ammonia has a higher ignition energy, which means that more energy is required to ignite ammonia, which increases the complexity and cost of the combustion process. Secondly, ammonia has a slower combustion rate, which leads to poor burnout performance, that is, ammonia cannot be completely burned, leaving unburned substances, which not only affects the efficiency of the engine, but may also cause pollution to the environment. In addition, due to these characteristics, in the current mainstream experimental schemes, the fuel supply method of ammonia engines mostly adopts intake injection, but this method cannot accurately control the concentration and stratification of the fuel, thereby limiting the application potential of ammonia in the engine.

[0004] In contrast, direct injection technology is easier to achieve a high ammonia substitution rate, improve combustion performance, and reduce emissions than intake port injection. This is because direct injection can more accurately control the supply and mixing of fuel, thereby optimizing the combustion process, improving efficiency, and reducing emissions of harmful substances. Currently, most ammonia engines use intake port premixed combustion and dual direct injection combustion modes, that is, they use highly active fuels such as hydrogen and diesel to ignite them. In this mode, two injection systems are often required, resulting in complex pipeline layout and increased costs, which is not conducive to the development and application of ammonia engines. Summary of the invention

[0005] In order to solve the problem that ammonia fuel has high ignition energy and cannot be completely burned, the present invention provides a high-pressure liquid ammonia-dimethyl ether mixed fuel supply system and control method, which uses the mixed ammonia and dimethyl ether as fuel and utilizes dimethyl ether to reduce the ignition energy of the fuel and improve the combustion efficiency of the fuel.

[0006] On the other hand, in order to address the problems of complex piping, high manufacturing and maintenance costs caused by the current dual-injection system, the present invention utilizes the good miscibility of liquid ammonia and liquid dimethyl ether to change the original dual-injection system into a single-injection system, thereby simplifying the piping structure and reducing manufacturing and maintenance costs.

[0007] The present invention achieves the above technical objectives through the following technical means.

[0008] A high-pressure liquid ammonia-dimethyl ether mixed fuel supply system, characterized in that it includes an air supply system, an air mixing system, a pressurization system and an injection system;

[0009] The gas supply system includes an ammonia storage tank, a dimethyl ether storage tank, an ammonia branch pipeline and a dimethyl ether branch pipeline; the inlet of the ammonia branch pipeline is connected to the ammonia storage tank, and the inlet of the dimethyl ether branch pipeline is connected to the dimethyl ether storage tank;

[0010] The gas mixing system includes a gas mixing tank inlet pipeline, a gas mixing tank, a gas mixing tank outlet pipeline, a first solenoid valve and a third solenoid valve; the ammonia branch pipeline and the dimethyl ether branch pipeline are both connected to the gas mixing tank through the gas mixing tank inlet pipeline, and the outlet of the gas mixing tank is connected to the gas mixing tank outlet pipeline; the first solenoid valve and the third solenoid valve are respectively arranged on the gas mixing tank inlet pipeline and the gas mixing tank outlet pipeline;

[0011] The boosting system comprises a first boosting pump, a second boosting pump, a cooling box and a second high-pressure outlet valve which are sequentially connected to the gas outlet pipeline of the gas mixing tank, and an air compressor which is connected to the first boosting pump and the second boosting pump;

[0012] The injection system includes a high-pressure common rail, an injector and a third high-pressure outlet valve; the high-pressure common rail is connected to a second boost pump, and the second high-pressure outlet valve is arranged on a connecting pipeline between the high-pressure common rail and the second boost pump; the injector is placed in an inner cavity of the constant volume combustion bomb, and is connected to the high-pressure common rail through the third high-pressure outlet valve.

[0013] Furthermore, it also includes an unloading system, which includes an absorption chamber, a fan, a vacuum pump, a first unloading valve, a second unloading valve, a third unloading valve, a second solenoid valve, a fifth ball valve and a fourth solenoid valve; the fan is connected to the mixing tank pipeline through the first unloading valve, the fan is connected to the cooling box pipeline through the second unloading valve, the fan is connected to the high-pressure common rail pipeline through the third unloading valve, and the fan is connected to the absorption chamber pipeline; the air inlet of the vacuum pump is connected to the mixing tank air inlet pipeline through the second solenoid valve, the air inlet of the vacuum pump is connected to the high-pressure common rail pipeline through the fourth solenoid valve, the air inlet of the vacuum pump is connected to the absorption chamber pipeline through the fifth ball valve, and the air outlet of the vacuum pump is connected to the absorption chamber pipeline; the connecting channel between the vacuum pump and the mixing tank air inlet pipeline is recorded as a vacuum pump branch pipeline, and the connection position of the vacuum pump branch pipeline and the mixing tank air inlet pipeline is located between the inlet of the mixing tank air inlet pipeline and the first solenoid valve.

[0014] Furthermore, a first vacuum gauge is also provided on the vacuum pump branch pipeline.

[0015] Furthermore, the gas supply system also includes an ammonia pressure reducing valve and a first ball valve sequentially arranged on the ammonia branch pipeline along the flow direction of ammonia, and a dimethyl ether pressure reducing valve and a second ball valve sequentially arranged on the dimethyl ether branch pipeline along the flow direction of dimethyl ether.

[0016] Furthermore, the gas mixing system also includes a gas mixing tank branch pipeline connected to the gas mixing tank intake pipeline, and a third ball valve and an intake pressure gauge sequentially arranged on the gas mixing tank branch pipeline along the flow direction of ammonia / dimethyl ether.

[0017] Furthermore, the gas mixing system also includes an electromagnetic agitator arranged in the gas mixing tank, a tank pressure gauge for detecting the internal pressure of the gas mixing tank, a fourth ball valve arranged on the connecting pipeline between the tank pressure gauge and the gas mixing tank, a second vacuum gauge for detecting the vacuum degree inside the gas mixing tank, and a gas mixing tank pressure limiting valve for explosion prevention.

[0018] Furthermore, the boosting system further comprises a first low-pressure gas inlet valve, a first high-pressure outlet valve, a gas-liquid separator, a first drive switch, a first drive pressure regulating valve, a first drive pressure gauge, a second drive switch, a second drive pressure regulating valve, a second drive pressure gauge, a first high-pressure gauge and a second high-pressure gauge; the first low-pressure gas inlet valve is arranged on the connecting pipeline between the third solenoid valve and the first boosting pump (28); the first high-pressure outlet valve and the gas-liquid separator are arranged in sequence on the connecting pipeline between the cooling box and the second boosting pump along the flow direction of ammonia-dimethyl ether, and the gas outlet of the gas-liquid separator is connected to the inlet pipeline of the first boosting pump, and the liquid outlet of the gas-liquid separator is connected to the inlet pipeline of the second boosting pump; the first drive switch, the first drive pressure regulating valve and the first drive pressure gauge are arranged in sequence on the connecting pipeline between the air compressor and the first boosting pump along the flow direction of the drive gas; the second drive switch, the second drive pressure regulating valve and the second drive pressure gauge are arranged in sequence on the connecting pipeline between the air compressor and the second boosting pump along the flow direction of the drive gas; the first high-pressure gauge and the second high-pressure gauge are used to detect the pressure at the outlet of the first boosting pump and the outlet of the second boosting pump respectively.

[0019] Furthermore, the air pressure adjustment ranges of the first driving pressure regulating valve and the second driving pressure regulating valve are both 0.1-0.8MPa; the compression ratio of the first booster pump is 5:1, and the compression ratio of the second booster pump is 100:1; the first high pressure gauge reading range is 0.5-4.0MPa, and the second high pressure gauge 42 reading range is 10-80MPa.

[0020] Furthermore, the injection system also includes an injector adapter connected to the inlet of the injector, and a third high-pressure gauge for detecting the internal pressure of the high-pressure common rail.

[0021] The control method of the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to any one of the above items is characterized by comprising the following steps:

[0022] S1: Keep the ammonia storage tank, the dimethyl ether storage tank, the third ball valve, the fourth ball valve, the third solenoid valve, the fifth ball valve, the mixing tank pressure limiting valve, the first unloading valve, the second unloading valve, the third unloading valve, the second high-pressure outlet valve and the third high-pressure outlet valve in a closed state, open the ammonia pressure reducing valve, the dimethyl ether pressure reducing valve, the first ball valve, the second ball valve, the first solenoid valve, the second solenoid valve and the fourth solenoid valve, and then start the vacuum pump to evacuate; then close the first solenoid valve, the second solenoid valve, the fourth solenoid valve, the ammonia pressure reducing valve, the dimethyl ether pressure reducing valve, the first ball valve and the second ball valve, and open the fifth ball valve;

[0023] S2: Open the ammonia storage tank, the ammonia pressure reducing valve, the first ball valve, the third ball valve, the first solenoid valve and the fourth ball valve, and pass ammonia into the mixing tank. During this period, the ammonia pressure reducing valve is regulated by monitoring the indication of the air intake pressure gauge; after the tank pressure indication reaches a predetermined value, the ammonia storage tank, the ammonia pressure reducing valve, the first ball valve, the first solenoid valve and the fifth ball valve are closed, the second solenoid valve is opened and the vacuum pump is started to evacuate, then the vacuum pump and the second solenoid valve are closed, and the fifth ball valve is opened; then the dimethyl ether storage tank, the dimethyl ether pressure reducing valve, the second ball valve and the first solenoid valve are opened, and dimethyl ether is passed into the mixing tank. During this period, the dimethyl ether pressure reducing valve is regulated by monitoring the indication of the air intake pressure gauge; after the tank pressure indication reaches a predetermined value, the dimethyl ether storage tank, the dimethyl ether pressure reducing valve, the second ball valve, the third ball valve, the first solenoid valve and the fifth ball valve are closed, the second solenoid valve is opened and the vacuum pump is started to evacuate, then the vacuum pump and the second solenoid valve are closed, and the fifth ball valve is opened;

[0024] Alternatively, open the dimethyl ether storage tank, the dimethyl ether pressure reducing valve, the second ball valve, the third ball valve, the first solenoid valve and the fourth ball valve, and pass dimethyl ether into the mixing tank, during which the dimethyl ether pressure reducing valve is regulated by monitoring the indication of the air inlet pressure gauge; after the tank pressure indication reaches a predetermined value, close the dimethyl ether storage tank, the dimethyl ether pressure reducing valve, the second ball valve, the first solenoid valve and the fifth ball valve, open the second solenoid valve and start the vacuum pump to evacuate, then close the vacuum pump and the second solenoid valve, and open the fifth ball valve; then open the ammonia storage tank, the ammonia pressure reducing valve, the first ball valve and the first solenoid valve, and pass ammonia into the mixing tank, during which the ammonia pressure reducing valve is regulated by monitoring the indication of the air inlet pressure gauge; after the tank pressure indication reaches a predetermined value, close the ammonia storage tank, the ammonia pressure reducing valve, the first ball valve, the third ball valve, the first solenoid valve and the fifth ball valve, open the second solenoid valve and start the vacuum pump to evacuate, then close the vacuum pump and the second solenoid valve, and open the fifth ball valve;

[0025] S3: Start the electromagnetic stirrer to fully mix the ammonia gas and dimethyl ether. The mixing process lasts for at least 12 hours.

[0026] S4: after the mixing process in step S3 is completed, the third solenoid valve, the first low-pressure gas inlet valve, the first high-pressure outlet valve, the gas-liquid separator and the second high-pressure outlet valve are opened, while the first unloading valve, the second unloading valve, the third unloading valve, the fourth solenoid valve and the third high-pressure outlet valve are kept in a closed state; then the air compressor is started, the first drive switch is turned on, the first drive pressure regulating valve is adjusted until the first drive air pressure gauge reaches a predetermined value, and then the first booster pump is turned on to boost the ammonia-dimethyl ether for the first time, until the pressure reading of the first high-pressure gauge is not less than 1MPa; then the second drive switch is turned on, the second drive pressure regulating valve is adjusted until the second drive air pressure gauge reaches a predetermined value, and then the second booster pump is turned on to boost the ammonia-dimethyl ether for the second time, until the pressure readings of the second high-pressure gauge and the third high-pressure gauge reach the pressure value required for injection;

[0027] S5: opening the third high-pressure outlet valve, and the liquid ammonia-dimethyl ether that has been pressurized twice enters the inner cavity of the constant volume combustion bomb through the high-pressure common rail and the injector, thereby realizing the spraying and combustion of the liquid ammonia-dimethyl ether;

[0028] S6: After the injection work in step S5 is completed, the electromagnetic stirrer, the third electromagnetic valve, the third high-pressure outlet valve, the first drive switch and the second drive switch are closed, and the first drive pressure regulating valve and the second drive pressure regulating valve are adjusted until the readings of the first drive pressure gauge and the second drive pressure gauge are both reduced to below 0.1MPa, then the air compressor is closed and the fan, the first unloading valve, the second unloading valve and the third unloading valve are opened, and the mixing tank, the first boosting pump, the cooling box, the second boosting pump, the high-pressure common rail and the corresponding connecting pipelines are exhausted and unloaded, so that the residual ammonia-dimethyl ether enters the absorption chamber and is recovered; then the fan, the first unloading valve, the second unloading valve, the third unloading valve, the first low-pressure gas inlet valve, the first high-pressure outlet valve and the second high-pressure outlet valve are closed.

[0029] The present invention utilizes dimethyl ether to reduce the ignition energy of fuel, improve combustion efficiency, and realize the principle of a single injection system as follows: First, dimethyl ether as a fuel has excellent environmental performance, good economy, wide substitution, can improve thermal efficiency and reduce noise, high technical maturity and good market prospects. Dimethyl ether is an oxygen-containing fuel with an oxygen content of nearly 35%. The fuel has a high cetane number, which means that it has a lower ignition delay and a smaller premixed combustion phase, as well as lower peak cylinder pressure and NOx generation. The cetane number of dimethyl ether is greater than 55, which makes it very suitable for compression ignition engines and improves the combustion efficiency and performance of the engine. At the same time, it has a higher energy density, which makes it more advantageous in volume, and is particularly suitable for application scenarios that require high energy density. Secondly, ammonia and dimethyl ether are both polar molecules with similar boiling points and close saturated vapor pressures at the same temperature and pressure. At the same time, ammonia and dimethyl ether are both gaseous at room temperature and can be miscible without adding emulsifiers after being pressurized into liquid form. This ensures that ammonia and dimethyl ether can share a common mixed boost injection system, thus providing a prerequisite for the realization of the in-cylinder ammonia-dimethyl ether mixed fuel direct injection compression ignition technology route and providing a reference for the development and application of ammonia fuel engines.

[0030] The beneficial effects of the present invention are as follows:

[0031] 1. The present invention uses mixed ammonia and dimethyl ether as fuel, and uses dimethyl ether to reduce the ignition energy of the fuel, improve the combustion efficiency of the fuel, reduce the generation of incomplete combustion products, and reduce harmful emissions and fuel consumption. On the other hand, since ammonia and dimethyl ether are both polar molecules with similar boiling points, their saturated vapor pressures are relatively close at the same temperature and pressure, and liquid ammonia and liquid dimethyl ether have good mutual solubility, the present invention changes the original dual injection system into a single injection system based on the above characteristics, which not only simplifies the system structure, reduces the manufacturing cost and maintenance cost, but also improves the overall reliability and stability of the system.

[0032] 2. The present invention sets two branch pipelines so that the two fuels enter the mixing tank respectively through independent pipelines, and uses a vacuum pump to evacuate the gas before mixing, thereby ensuring the accuracy of the ratio of the ammonia-dimethyl ether mixed gas and eliminating the influence of residual gas on the mixing effect. At the same time, the vacuum pump adopts an explosion-proof motor to avoid the risk of explosion of the motor during the vacuum pumping of the ammonia-dimethyl ether mixed gas.

[0033] 3. The driving gas of the first booster pump and the second booster pump in the present invention is provided by an air compressor. Since the ammonia-dimethyl ether mixed gas and mixed liquid are both flammable, the first booster pump and the second booster pump in the present invention use gas-driven booster pumps instead of electric-driven booster pumps to avoid arcs and sparks generated by the electric drive during the boosting process and cause fire.

[0034] 4. The present invention sets a cooling box between the first booster pump and the second booster pump. Since the internal energy of the ammonia-dimethyl ether gas increases after being pressurized and compressed by the first booster pump, the temperature of the ammonia-dimethyl ether mixed liquid increases and the saturated vapor pressure increases. When the pressure of liquid ammonia-dimethyl ether is lower than the saturated vapor pressure of the mixed liquid, it is easy to vaporize. Therefore, the temperature of the mixed liquid is further reduced by the cooling box to achieve the purpose of reducing the saturated vapor pressure of the ammonia-dimethyl ether mixed liquid, thereby reducing the loss of liquid ammonia-dimethyl ether.

[0035] 5. The present invention is provided with a gas-liquid separator between the cooling box and the second booster pump. Bubbles may be generated in the ammonia-dimethyl ether mixed liquid after being pressurized by the first booster pump. The function of the gas-liquid separator is to separate the ammonia-dimethyl ether mixed gas and the mixed liquid in the mixed liquid after the initial pressurization, and to recover the separated mixed gas at the same time, thereby avoiding the influence of bubbles on the secondary pressurization of the high-pressure liquid ammonia-dimethyl ether and the waste of the mixed gas.

[0036] 6. The unloading system of the present invention unloads the residual ammonia-dimethyl ether gas in the mixing tank, the first booster pump, the second booster pump, the cooling box and the high-pressure common rail through the fan, and absorbs the residual ammonia-dimethyl ether mixed gas through the absorption chamber, thereby avoiding the corrosion and wear of the pipeline, the booster pump and the high-pressure common rail by the high-pressure liquid ammonia-dimethyl ether after long-term non-operation, and the pollution to the environment caused by the leakage of the ammonia-dimethyl ether mixed liquid under abnormal circumstances.

[0037] 7. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system of the present invention is not limited to the use of ammonia and dimethyl ether, two types of mixed, pressurized and liquefied gas fuels, but is also applicable to other engine fuels with good miscibility in liquid state. This also makes the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system of the present invention have broader application prospects.

[0038] 8. The present invention realizes the conversion of ammonia-dimethyl ether from gaseous fuel to high-pressure liquid fuel through mixed supercharging, and finally enters the injector through the high-pressure common rail to realize high-pressure jet injection, thereby meeting the demand for providing fuel supply for the spray combustion of the ammonia-dimethyl ether mixed fuel in a visualized constant volume combustion bomb, and at the same time exploring the development and application of new combustion modes for ammonia engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic structural diagram of the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system of the present invention.

[0040] The reference numerals are as follows:

[0041] 1. Ammonia storage tank; 2. Dimethyl ether storage tank; 3. Ammonia pressure reducing valve; 4. Dimethyl ether pressure reducing valve; 5. First ball valve; 6. Second ball valve; 7. Third ball valve; 8. Inlet pressure gauge; 9. First vacuum gauge; 10. First solenoid valve; 11. Tank pressure gauge; 12. Fourth ball valve; 13. Second vacuum gauge; 14. Second solenoid valve; 15. Third solenoid valve; 16. Fifth ball valve; 17. Vacuum pump; 18. Mixing tank; 19. Electromagnetic stirrer; 20. Mixing tank pressure limiting valve; 21. First unloading valve; 22. Ammonia branch pipeline; 23. Dimethyl ether branch pipeline; 24. Mixing tank inlet pipeline; 25. Vacuum pump branch pipeline; 26. Mixing tank outlet pipeline; 27. Air compressor; 28. The first boost pump; 29, the second boost pump; 30, the first low-pressure gas inlet valve; 31, the first drive switch; 32, the first drive pressure regulating valve; 33, the first drive pressure gauge; 34, the first high-pressure gauge; 35, the cooling box; 36, the second unloading valve; 37, the first high-pressure outlet valve; 38, the gas-liquid separator; 39, the second drive switch; 40, the second drive pressure regulating valve; 41, the second drive pressure gauge; 42, the second high-pressure gauge; 43, the second high-pressure outlet valve; 44, the third unloading valve; 45, the high-pressure common rail; 46, the fourth solenoid valve; 47, the third high-pressure gauge; 48, the third high-pressure outlet valve; 49, the injector adapter; 50, the injector; 51, the constant-volume combustion bomb; 52, the fan; 53, the absorption chamber. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0043] The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system described in this embodiment includes an air supply system, an air mixing system, a pressurization system, an injection system and an unloading system. Figure 1 This is a schematic diagram of the structure of the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system described in this embodiment.

[0044] The gas supply system includes an ammonia storage tank 1, a dimethyl ether storage tank 2, an ammonia branch pipeline 22, a dimethyl ether branch pipeline 23, an ammonia pressure reducing valve 3, a first ball valve 5, a dimethyl ether pressure reducing valve 4 and a second ball valve 6. The inlet of the ammonia branch pipeline 22 is connected to the ammonia storage tank 1, and the inlet of the dimethyl ether branch pipeline 23 is connected to the dimethyl ether storage tank 2. The ammonia pressure reducing valve 3 and the first ball valve 5 are sequentially arranged on the ammonia branch pipeline 22 along the flow direction of ammonia, and the dimethyl ether pressure reducing valve 4 and the second ball valve 6 are sequentially arranged on the dimethyl ether branch pipeline 23 along the flow direction of dimethyl ether.

[0045] The gas mixing system includes a gas mixing tank inlet pipeline 24, a gas mixing tank 18, a gas mixing tank outlet pipeline 26, a first solenoid valve 10, a third solenoid valve 15, a gas mixing tank 18 branch pipeline, a third ball valve 7, an inlet pressure gauge 8, an electromagnetic stirrer 19, a tank pressure gauge 11, a fourth ball valve 12, a second vacuum gauge 13 and a gas mixing tank pressure limiting valve 20. The ammonia branch pipeline 22 and the dimethyl ether branch pipeline 23 are both connected to the gas mixing tank 18 through the gas mixing tank inlet pipeline 24, and the outlet of the gas mixing tank 18 is connected to the gas mixing tank outlet pipeline 26. The first solenoid valve 10 and the third solenoid valve 15 are respectively arranged on the gas mixing tank inlet pipeline 24 and the gas mixing tank outlet pipeline 26. The gas mixing tank branch pipeline is connected to the gas mixing tank inlet pipeline 24, and the third ball valve 7 and the inlet pressure gauge 8 are sequentially arranged on the gas mixing tank branch pipeline along the flow direction of ammonia / dimethyl ether. The inlet pressure gauge 8 is used to monitor the inlet pressure of ammonia / dimethyl ether, and is adjusted by the ammonia pressure reducing valve 3 / dimethyl ether pressure reducing valve 4. The electromagnetic stirrer 19 is arranged in the mixing tank 18, and is used to fully mix the ammonia and dimethyl ether entering the mixing tank 18. The tank pressure gauge 11 is used to detect the internal pressure of the mixing tank 18. The fourth ball valve 12 is arranged on the connecting pipeline between the tank pressure gauge 11 and the mixing tank 18, and is used to protect the tank pressure gauge 11. The second vacuum gauge 13 is used to detect the vacuum degree inside the mixing tank 18. The mixing tank pressure limiting valve 20 plays an explosion-proof role for the mixing tank 18.

[0046] The boosting system includes a first low-pressure gas inlet valve 30 connected to the gas outlet pipeline 26 of the mixing tank in sequence, a first boosting pump 28, a cooling box 35, a first high-pressure outlet valve 37, a gas-liquid separator 38, a second boosting pump 29 and a second high-pressure outlet valve 43, an air compressor 27 connected to the first boosting pump 28 and the second boosting pump 29, a first driving switch 31, a first driving pressure regulating valve 32 and a first driving air pressure gauge arranged in sequence on the connecting pipeline between the air compressor 27 and the first boosting pump 28 along the flow direction of the driving gas, a second driving switch 39, a second driving pressure regulating valve 40 and a second driving air pressure gauge 41 arranged in sequence on the connecting pipeline between the air compressor 27 and the second boosting pump 29 along the flow direction of the driving gas, and a first high-pressure gauge 34 and a second high-pressure gauge 42 for respectively detecting the pressure at the outlet of the first boosting pump 28 and the outlet of the second boosting pump 29. The first low-pressure gas inlet valve 30 is arranged on the connecting pipeline between the third solenoid valve 15 and the first boosting pump 28. The gas outlet of the gas-liquid separator 38 is connected to the inlet pipeline of the first booster pump 28, and the liquid outlet of the gas-liquid separator 38 is connected to the inlet pipeline of the second booster pump 29. The gas pressure adjustment range of the first driving pressure regulating valve 32 and the second driving pressure regulating valve 40 is 0.1-0.8MPa. The compression ratio of the first booster pump 28 is 5:1, and the compression ratio of the second booster pump 29 is 100:1. The reading range of the first high-pressure gauge 34 is 0.5-4.0MPa, and the reading range of the second high-pressure gauge 4242 is 10-80MPa.

[0047] The injection system includes a high-pressure common rail 45, an injector adapter 49, an injector 50 and a third high-pressure gauge 47. The high-pressure common rail 45 is connected to the second boost pump 29, and the second high-pressure outlet valve 43 is arranged on the connecting pipeline between the high-pressure common rail 45 and the second boost pump 29. The injector 50 is placed in the inner cavity of the constant volume combustion bomb 51, and is connected to the high-pressure common rail 45 through the third high-pressure outlet valve 48, and the inlet of the injector is installed with an injector adapter 49. The third high-pressure gauge 47 is used to detect the internal pressure of the high-pressure common rail 45.

[0048] The unloading system includes an absorption chamber 53 , a fan 52 , a vacuum pump 17 , a first unloading valve 21 , a second unloading valve 36 , a third unloading valve 44 , a second solenoid valve 14 , a fifth ball valve 16 and a fourth solenoid valve 46 .

[0049] The fan 52 is connected to the mixing tank 18 pipeline through the first unloading valve 21, the fan 52 is connected to the cooling box 35 pipeline through the second unloading valve 36, the fan 52 is connected to the high-pressure common rail 45 pipeline through the third unloading valve 44, and the fan 52 is connected to the absorption chamber 53 pipeline; the air inlet of the vacuum pump 17 is connected to the mixing tank air inlet pipeline 24 through the second solenoid valve 14, the air inlet of the vacuum pump 17 is connected to the high-pressure common rail 45 pipeline through the fourth solenoid valve 46, the air inlet of the vacuum pump 17 is connected to the absorption chamber 53 pipeline through the fifth ball valve 16, and the air outlet of the vacuum pump 17 is connected to the absorption chamber 53 pipeline. The connection channel between the vacuum pump 17 and the mixing tank air inlet pipeline 24 is recorded as a vacuum pump branch pipeline 25, and the connection position between the vacuum pump branch pipeline 25 and the mixing tank air inlet pipeline 24 is located between the entrance of the mixing tank air inlet pipeline 24 and the first solenoid valve 10, and a first vacuum gauge 9 is also arranged on the vacuum pump branch pipeline 25.

[0050] The control method of the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system comprises the following steps:

[0051] S1: Keep the ammonia storage tank 1, the dimethyl ether storage tank 2, the third ball valve 7, the fourth ball valve 12, the third solenoid valve 15, the fifth ball valve 16, the gas mixing tank pressure limiting valve 20, the first unloading valve 21, the second unloading valve 36, the third unloading valve 44, the second high-pressure outlet valve 43 and the third high-pressure outlet valve 48 in a closed state, open the ammonia pressure reducing valve 3, the dimethyl ether pressure reducing valve 4, the first ball valve 5, the second ball valve 6, the first solenoid valve 10, the second solenoid valve 14 and the fourth solenoid valve 46, and then start the vacuum pump 17 to evacuate. Then close the first solenoid valve 10, the second solenoid valve 14, the fourth solenoid valve 46, the ammonia pressure reducing valve 3, the dimethyl ether pressure reducing valve 4, the first ball valve 5 and the second ball valve 6, and open the fifth ball valve 16.

[0052] S2: Open the ammonia storage tank 1, the ammonia pressure reducing valve 3, the first ball valve 5, the third ball valve 7, the first solenoid valve 10 and the fourth ball valve 12, and pass ammonia into the mixing tank 18. During this period, the ammonia pressure reducing valve 3 is regulated by monitoring the reading of the intake pressure gauge 8. After the reading of the tank pressure gauge 11 reaches a predetermined value, close the ammonia storage tank 1, the ammonia pressure reducing valve 3, the first ball valve 5, the first solenoid valve 10 and the fifth ball valve 16, open the second solenoid valve 14 and start the vacuum pump 17 to evacuate, then close the vacuum pump 17 and the second solenoid valve 14, and open the fifth ball valve 16. Then open the dimethyl ether storage tank 2, the dimethyl ether pressure reducing valve 4, the second ball valve 6 and the first solenoid valve 10, and pass dimethyl ether into the mixing tank 18. During this period, the dimethyl ether pressure reducing valve 4 is regulated by monitoring the reading of the intake pressure gauge 8. After the tank pressure gauge 11 shows a predetermined value, close the dimethyl ether storage tank 2, the dimethyl ether pressure reducing valve 4, the second ball valve 6, the third ball valve 7, the first solenoid valve 10 and the fifth ball valve 16, open the second solenoid valve 14 and start the vacuum pump 17 to evacuate the vacuum, then close the vacuum pump 17 and the second solenoid valve 14, and open the fifth ball valve 16.

[0053] Alternatively, the dimethyl ether storage tank 2, the dimethyl ether pressure reducing valve 4, the second ball valve 6, the third ball valve 7, the first solenoid valve 10 and the fourth ball valve 12 are opened to pass the dimethyl ether into the gas mixing tank 18, and the dimethyl ether pressure reducing valve 4 is regulated by monitoring the reading of the intake pressure gauge 8. After the reading of the tank pressure gauge 11 reaches a predetermined value, the dimethyl ether storage tank 2, the dimethyl ether pressure reducing valve 4, the second ball valve 6, the first solenoid valve 10 and the fifth ball valve 16 are closed, the second solenoid valve 14 is opened and the vacuum pump 17 is started to evacuate, then the vacuum pump 17 and the second solenoid valve 14 are closed, and the fifth ball valve 16 is opened; then the ammonia storage tank 1, the ammonia pressure reducing valve 3, the first ball valve 5 and the first solenoid valve 10 are opened, and the ammonia gas is passed into the gas mixing tank 18, and the ammonia pressure reducing valve 3 is regulated by monitoring the reading of the intake pressure gauge 8. After the tank pressure gauge 11 shows a predetermined value, close the ammonia storage tank 1, the ammonia pressure reducing valve 3, the first ball valve 5, the third ball valve 7, the first solenoid valve 10 and the fifth ball valve 16, open the second solenoid valve 14 and start the vacuum pump 17 to evacuate the air, then close the vacuum pump 17 and the second solenoid valve 14, and open the fifth ball valve 16.

[0054] S3: Start the electromagnetic stirrer 19 to fully mix the ammonia gas and the dimethyl ether. The mixing process lasts for at least 12 hours.

[0055] S4: After the mixing process in step S3 is completed, the third solenoid valve 15, the first low-pressure gas inlet valve 30, the first high-pressure outlet valve 37, the gas-liquid separator 38 and the second high-pressure outlet valve 43 are opened, and the first unloading valve 21, the second unloading valve 36, the third unloading valve 44, the fourth solenoid valve 46 and the third high-pressure outlet valve 48 are kept in a closed state. Then, the air compressor 27 is started, the first drive switch 31 is opened, and the first drive pressure regulating valve 32 is adjusted until the first drive air pressure gauge reaches a predetermined value, and then the first booster pump 28 is turned on to boost the ammonia-dimethyl ether for the first time, until the pressure reading of the first high-pressure gauge 34 is not less than 1MPa. Then, the second drive switch 39 is opened, and the second drive pressure regulating valve 40 is adjusted until the second drive air pressure gauge 41 reaches a predetermined value, and then the second booster pump 29 is turned on to boost the ammonia-dimethyl ether for the second time, until the pressure readings of the second high-pressure gauge 42 and the third high-pressure gauge 47 reach the pressure value required for injection.

[0056] S5: Open the third high-pressure outlet valve 48, and the liquid ammonia-dimethyl ether that has been pressurized twice enters the inner cavity of the constant volume combustion bomb 51 through the high-pressure common rail 45 and the injector, thereby realizing the spraying and combustion of the liquid ammonia-dimethyl ether.

[0057] S6: After the spraying work in step S5 is completed, the electromagnetic stirrer 19, the third electromagnetic valve 15, the third high-pressure outlet valve 48, the first drive switch 31 and the second drive switch 39 are closed, and the first drive pressure regulating valve 32 and the second drive pressure regulating valve 40 are adjusted until the readings of the first drive pressure gauge and the second drive pressure gauge 41 are both reduced to below 0.1MPa, and then the air compressor 27 is closed and the fan 52, the first unloading valve 21, the second unloading valve 36 and the third unloading valve 44 are opened, and the mixing tank 18, the first boosting pump 28, the cooling box 35, the second boosting pump 29, the high-pressure common rail 45 and the corresponding connecting pipelines are exhausted and unloaded, so that the residual ammonia-dimethyl ether enters the absorption chamber 53 and is recovered. Then the fan 52, the first unloading valve 21, the second unloading valve 36, the third unloading valve 44, the first low-pressure gas inlet valve 30, the first high-pressure outlet valve 37 and the second high-pressure outlet valve 43 are closed.

[0058] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A high-pressure liquid ammonia-dimethyl ether mixed fuel supply system, characterized in that: Including air supply system, air mixing system, boost system and injection system; The gas supply system comprises an ammonia storage tank (1), a dimethyl ether storage tank (2), an ammonia branch pipeline (22) and a dimethyl ether branch pipeline (23); the inlet of the ammonia branch pipeline (22) is connected to the ammonia storage tank (1), and the inlet of the dimethyl ether branch pipeline (23) is connected to the dimethyl ether storage tank (2); The gas mixing system comprises a gas mixing tank inlet pipeline (24), a gas mixing tank (18), a gas mixing tank outlet pipeline (26), a first solenoid valve (10) and a third solenoid valve (15); the ammonia branch pipeline (22) and the dimethyl ether branch pipeline (23) are both connected to the gas mixing tank (18) through the gas mixing tank inlet pipeline (24), and the outlet of the gas mixing tank (18) is connected to the gas mixing tank outlet pipeline (26); the first solenoid valve (10) and the third solenoid valve (15) are respectively arranged on the gas mixing tank inlet pipeline (24) and the gas mixing tank outlet pipeline (26); The boosting system comprises a first boosting pump (28), a second boosting pump (29), a cooling box (35) and a second high-pressure outlet valve (43) which are sequentially connected to the gas mixing tank outlet pipeline (26), and an air compressor (27) which is connected to the first boosting pump (28) and the second boosting pump (29); The injection system comprises a high-pressure common rail (45), an injector (50) and a third high-pressure outlet valve (48); the high-pressure common rail (45) is connected to a second boost pump (29), and the second high-pressure outlet valve (43) is arranged on a connecting pipeline between the high-pressure common rail (45) and the second boost pump (29); the injector (50) is placed in an inner cavity of a constant-volume combustion bomb (51), and is connected to the high-pressure common rail (45) through the third high-pressure outlet valve (48).

2. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 1, characterized in that: The invention also includes an unloading system, wherein the unloading system includes an absorption chamber (53), a fan (52), a vacuum pump (17), a first unloading valve (21), a second unloading valve (36), a third unloading valve (44), a second solenoid valve (14), a fifth ball valve (16) and a fourth solenoid valve (46); the fan (52) is connected to the gas mixing tank (18) pipeline through the first unloading valve (21), the fan (52) is connected to the cooling box (35) pipeline through the second unloading valve (36), the fan (52) is connected to the high-pressure common rail (45) pipeline through the third unloading valve (44), and the fan (52) is connected to the absorption chamber (53) pipeline; the vacuum pump (17) The air inlet of the vacuum pump (17) is connected to the air inlet pipeline (24) of the mixing tank through the second solenoid valve (14), the air inlet of the vacuum pump (17) is connected to the high-pressure common rail (45) pipeline through the fourth solenoid valve (46), the air inlet of the vacuum pump (17) is connected to the absorption chamber (53) pipeline through the fifth ball valve (16), and the air outlet of the vacuum pump (17) is connected to the absorption chamber (53) pipeline; the connection channel between the vacuum pump (17) and the air inlet pipeline (24) of the mixing tank is recorded as the vacuum pump branch pipeline (25), and the connection position of the vacuum pump branch pipeline (25) and the air inlet pipeline (24) of the mixing tank is located between the inlet of the air inlet pipeline (24) of the mixing tank and the first solenoid valve (10).

3. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 2, characterized in that: A first vacuum gauge (9) is also provided on the vacuum pump branch pipeline (25).

4. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 1, characterized in that: The gas supply system further comprises an ammonia pressure reducing valve (3) and a first ball valve (5) which are arranged in sequence on an ammonia branch pipeline (22) along the flow direction of ammonia, and a dimethyl ether pressure reducing valve (4) and a second ball valve (6) which are arranged in sequence on a dimethyl ether branch pipeline (23) along the flow direction of dimethyl ether.

5. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 1, characterized in that: The gas mixing system further comprises a gas mixing tank branch pipeline connected to the gas mixing tank intake pipeline (24), and a third ball valve (7) and an intake pressure gauge (8) sequentially arranged on the gas mixing tank branch pipeline along the flow direction of ammonia / dimethyl ether.

6. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 1, characterized in that: The gas mixing system further comprises an electromagnetic stirrer (19) arranged in a gas mixing tank (18), a tank pressure gauge (11) for detecting the internal pressure of the gas mixing tank (18), a fourth ball valve (12) arranged on a connecting pipeline between the tank pressure gauge (11) and the gas mixing tank (18), a second vacuum gauge (13) for detecting the internal vacuum degree of the gas mixing tank (18), and a gas mixing tank pressure limiting valve (20) for explosion prevention.

7. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 1, characterized in that: The boosting system further comprises a first low-pressure gas inlet valve (30), a first high-pressure outlet valve (37), a gas-liquid separator (38), a first drive switch (31), a first drive pressure regulating valve (32), a first drive pressure gauge (33), a second drive switch (39), a second drive pressure regulating valve (40), a second drive pressure gauge (41), a first high-pressure gauge (34) and a second high-pressure gauge (42); the first low-pressure gas inlet valve (30) is arranged on a connecting pipeline between a third solenoid valve (15) and a first boosting pump (28); the first high-pressure outlet valve (37) and the gas-liquid separator (38) are arranged in sequence on a connecting pipeline between a cooling box (35) and a second boosting pump (29) along a flow direction of ammonia-dimethyl ether, and a gas outlet of the gas-liquid separator (38) is connected to the first The inlet pipeline of the booster pump (28) is connected, and the liquid outlet of the gas-liquid separator (38) is connected to the inlet pipeline of the second booster pump (29); the first drive switch (31), the first drive pressure regulating valve (32) and the first drive air pressure gauge (33) are arranged in sequence on the connecting pipeline between the air compressor (27) and the first booster pump (28) along the flow direction of the drive gas; the second drive switch (39), the second drive pressure regulating valve (40) and the second drive air pressure gauge (41) are arranged in sequence on the connecting pipeline between the air compressor (27) and the second booster pump (29) along the flow direction of the drive gas; the first high-pressure gauge (34) and the second high-pressure gauge (42) are used to detect the pressure at the outlet of the first booster pump (28) and the outlet of the second booster pump (29), respectively.

8. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 7, characterized in that: The air pressure adjustment ranges of the first driving pressure regulating valve (32) and the second driving pressure regulating valve (40) are both 0.1-0.8 MPa; the compression ratio of the first booster pump (28) is 5:1, and the compression ratio of the second booster pump (29) is 100:1; the reading range of the first high-pressure gauge (34) is 0.5-4.0 MPa, and the reading range of the second high-pressure gauge (42) is 10-80 MPa.

9. The high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to claim 1, characterized in that: The injection system further comprises an injector adapter (49) connected to the inlet of the injector (50), and a third high pressure gauge (47) for detecting the internal pressure of the high pressure common rail (45).

10. The control method of the high-pressure liquid ammonia-dimethyl ether mixed fuel supply system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Keep the ammonia storage tank (1), the dimethyl ether storage tank (2), the third ball valve (7), the fourth ball valve (12), the third solenoid valve (15), the fifth ball valve (16), the gas mixing tank pressure limiting valve (20), the first unloading valve (21), the second unloading valve (36), the third unloading valve (44), the second high-pressure outlet valve (43) and the third high-pressure outlet valve (48) in a closed state, open the ammonia pressure reducing valve (3), the dimethyl ether pressure reducing valve (4), the first ball valve (5), the second ball valve (6), the first solenoid valve (10), the second solenoid valve (14) and the fourth solenoid valve (46), then start the vacuum pump (17) to evacuate; then close the first solenoid valve (10), the second solenoid valve (14), the fourth solenoid valve (46), the ammonia pressure reducing valve (3), the dimethyl ether pressure reducing valve (4), the first ball valve (5) and the second ball valve (6), and open the fifth ball valve (16); S2: Open the ammonia storage tank (1), the ammonia pressure reducing valve (3), the first ball valve (5), the third ball valve (7), the first solenoid valve (10) and the fourth ball valve (12), and let the ammonia gas flow into the mixing tank (18). During this period, the ammonia pressure reducing valve (3) is regulated by monitoring the reading of the intake pressure gauge (8); after the reading of the tank pressure gauge (11) reaches a predetermined value, close the ammonia storage tank (1), the ammonia pressure reducing valve (3), the first ball valve (5), the first solenoid valve (10) and the fifth ball valve (16), open the second solenoid valve (14) and start the vacuum pump (17) to evacuate the air, then close the vacuum pump (17) and the second solenoid valve (14), and open the fifth ball valve (16). ); then, the dimethyl ether storage tank (2), the dimethyl ether pressure reducing valve (4), the second ball valve (6) and the first solenoid valve (10) are opened, and the dimethyl ether is introduced into the mixing tank (18). During this period, the dimethyl ether pressure reducing valve (4) is regulated by monitoring the reading of the intake pressure gauge (8); after the reading of the tank pressure gauge (11) reaches a predetermined value, the dimethyl ether storage tank (2), the dimethyl ether pressure reducing valve (4), the second ball valve (6), the third ball valve (7), the first solenoid valve (10) and the fifth ball valve (16) are closed, the second solenoid valve (14) is opened and the vacuum pump (17) is started to evacuate, then the vacuum pump (17) and the second solenoid valve (14) are closed, and the fifth ball valve (16) is opened; Alternatively, the dimethyl ether storage tank (2), the dimethyl ether pressure reducing valve (4), the second ball valve (6), the third ball valve (7), the first solenoid valve (10) and the fourth ball valve (12) are opened to allow dimethyl ether to flow into the gas mixing tank (18), during which the dimethyl ether pressure reducing valve (4) is regulated by monitoring the reading of the intake pressure gauge (8); after the reading of the tank pressure gauge (11) reaches a predetermined value, the dimethyl ether storage tank (2), the dimethyl ether pressure reducing valve (4), the second ball valve (6), the first solenoid valve (10) and the fifth ball valve (16) are closed, the second solenoid valve (14) is opened and the vacuum pump (17) is started to evacuate, then the vacuum pump (17) and the second solenoid valve (14) are closed, and the third solenoid valve (10) is opened. The ammonia storage tank (1), the ammonia pressure reducing valve (3), the first ball valve (5) and the first solenoid valve (10) are then opened to allow ammonia to flow into the mixing tank (18). During this period, the ammonia pressure reducing valve (3) is regulated by monitoring the reading of the intake pressure gauge (8); after the reading of the tank pressure gauge (11) reaches a predetermined value, the ammonia storage tank (1), the ammonia pressure reducing valve (3), the first ball valve (5), the third ball valve (7), the first solenoid valve (10) and the fifth ball valve (16) are closed, the second solenoid valve (14) is opened and the vacuum pump (17) is started to evacuate the air, then the vacuum pump (17) and the second solenoid valve (14) are closed, and the fifth ball valve (16) is opened; S3: starting the electromagnetic stirrer (19) to fully mix the ammonia gas and the dimethyl ether, and the mixing process lasts for at least 12 hours; S4: After the mixing process in step S3 is completed, the third solenoid valve (15), the first low-pressure gas inlet valve (30), the first high-pressure outlet valve (37), the gas-liquid separator (38) and the second high-pressure outlet valve (43) are opened, while the first unloading valve (21), the second unloading valve (36), the third unloading valve (44), the fourth solenoid valve (46) and the third high-pressure outlet valve (48) are kept in a closed state; then the air compressor (27) is started, the first drive switch (31) is turned on, and the first drive pressure regulating valve (3 2) After the first driving air pressure gauge (33) reaches a predetermined value, the first boosting pump (28) is turned on to boost the pressure of the ammonia-dimethyl ether for the first time, until the pressure reading of the first high-pressure gauge (34) is not less than 1 MPa; then the second driving switch (39) is turned on, and the second driving pressure regulating valve (40) is adjusted until the second driving air pressure gauge (41) reaches a predetermined value, and then the second boosting pump (29) is turned on to boost the pressure of the ammonia-dimethyl ether for the second time, until the pressure readings of the second high-pressure gauge (42) and the third high-pressure gauge (47) reach the pressure values ​​required for injection; S5: opening the third high-pressure outlet valve (48), and the liquid ammonia-dimethyl ether that has been pressurized twice enters the inner cavity of the constant volume combustion bomb (51) through the high-pressure common rail (45) and the injector, thereby achieving the spraying and combustion of the liquid ammonia-dimethyl ether; S6: After the spraying operation in step S5 is completed, the electromagnetic stirrer (19), the third electromagnetic valve (15), the third high-pressure outlet valve (48), the first drive switch (31) and the second drive switch (39) are closed, and the first drive pressure regulating valve (32) and the second drive pressure regulating valve (40) are adjusted until the readings of the first drive pressure gauge (33) and the second drive pressure gauge (41) are both reduced to below 0.1 MPa, and then the air compressor (27) is closed and the fan (52), the first unloading valve (21) and the second unloading valve (3 6) and the third unloading valve (44), exhaust and unload the gas mixing tank (18), the first boosting pump (28), the cooling box (35), the second boosting pump (29), the high-pressure common rail (45) and the corresponding connecting pipelines, so that the residual ammonia-dimethyl ether enters the absorption chamber (53) and is recovered; then the fan (52), the first unloading valve (21), the second unloading valve (36), the third unloading valve (44), the first low-pressure gas inlet valve (30), the first high-pressure outlet valve (37) and the second high-pressure outlet valve (43) are closed.

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