Marine liquid ammonia fuel supply system and method with tank pressure control function

Abstract

The present invention relates to a marine liquid ammonia fuel supply system and method with a cabin pressure control function, comprising: an insulated storage tank, a buffer tank, a pressurizing device, a heat exchanger, an ammonia fuel device, a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a fifth pipeline, a sixth pipeline, and a seventh pipeline; the buffer tank, the pressurizing device, and the heat exchanger are sequentially connected by pipelines; the liquid ammonia in the insulated storage tank is sent to the buffer tank via the first pipeline, and then pressurized and cooled by the pressurizing device and the heat exchanger in sequence, and a portion is sent to the ammonia fuel device for use via the second pipeline, and the remaining portion is returned to the insulated storage tank via the third pipeline through the fourth or fifth pipeline. The liquid ammonia returned from the ammonia fuel device is returned to the buffer tank via the sixth pipeline. The system of the present invention is reliable and efficient, and there is no phase change during the entire process. While providing liquid ammonia as fuel, the excess liquid ammonia is cryogenically cooled and returned to the insulated storage tank, reducing the evaporation of the liquid ammonia, thereby controlling the cabin pressure.

Description

Technical Field

[0001] The present invention relates to the field of ship design, and in particular to a marine liquid ammonia fuel supply system and method with a cabin pressure control function. Background Art

[0002] Because ammonia is carbon-free, it is considered, along with hydrogen, to be the most promising fuel for the future decarbonized shipping industry and is gaining increasing attention from shipping companies.

[0003] Ammonia is easy to liquefy. Under one atmosphere of pressure, if gaseous ammonia is cooled to -33°C, or pressurized to 0.7-0.8MPa at room temperature, ammonia can be liquefied into a colorless liquid. The volume of liquid ammonia is about 1 / 922 of the volume of the same amount of gaseous ammonia. Therefore, storing ammonia fuel in liquid form on ships can save fuel storage space and effectively increase the ship's range and endurance.

[0004] Currently foreseeable ammonia dual-fuel engines all use liquid ammonia as fuel and cannot directly utilize the ammonia that evaporates during storage. Therefore, it is necessary to effectively handle and control the evaporation of liquid ammonia to prevent the cabin pressure from increasing, avoid the danger of ammonia emissions, and ensure the safety of people on board. Summary of the Invention

[0005] In order to effectively control the evaporation of liquid ammonia and the increase of tank pressure during the use of liquid ammonia as a ship fuel, the present invention provides a ship liquid ammonia fuel supply system and method with a tank pressure control function.

[0006] The technical objectives of the present invention are achieved through the following technical solutions:

[0007] A marine liquid ammonia fuel supply system with a tank pressure control function, comprising:

[0008] Insulated storage tank, buffer tank, booster device for boosting the pressure of liquid ammonia, heat exchanger for cooling the temperature of liquid ammonia, ammonia fuel equipment using liquid ammonia as fuel; the buffer tank, booster device, and heat exchanger are connected in sequence through pipelines;

[0009] A first pipeline is connected between the insulating storage tank and the buffer tank for transporting liquid ammonia in the insulating storage tank to the buffer tank;

[0010] A second pipeline for conveying liquid ammonia to the ammonia fuel device is connected between the heat exchanger and the ammonia fuel device;

[0011] The heat exchanger is also connected to a third pipeline for returning liquid ammonia not consumed by the ammonia fuel device to the insulated storage tank. One end of the third pipeline is connected to the heat exchanger, and the other end of the third pipeline is connected to a fourth pipeline and a fifth pipeline. The fourth pipeline includes an atomizer injector. The third pipeline is provided with a pressure reducing device for reducing the pressure of the liquid ammonia and a subcooling device for reducing the temperature of the liquid ammonia.

[0012] The third pipeline, the fourth pipeline, and the insulating storage tank are connected to form a first liquid ammonia return path, and the third pipeline, the fifth pipeline, and the insulating storage tank are connected to form a second liquid ammonia return path. When the liquid ammonia in the insulating storage tank is less than a set value, the liquid ammonia in the third pipeline is returned to the insulating storage tank via the first liquid ammonia return path. When the liquid ammonia in the insulating storage tank is not less than the set value, the liquid ammonia in the third pipeline is returned to the insulating storage tank via the second liquid ammonia return path.

[0013] A sixth pipeline is also connected between the ammonia fuel device and the buffer tank, through which liquid ammonia refluxed from the ammonia fuel device flows back to the buffer tank.

[0014] Furthermore, the second pipeline includes a pressure control valve for adjusting the pressure of liquid ammonia in the second pipeline to adapt to the ammonia fuel equipment, and also includes a first pressure detection device for detecting the pressure of liquid ammonia in the second pipeline.

[0015] Furthermore, the supercooling device includes a supercooling unit and a supercooling heat exchanger. The supercooling unit provides refrigerant for the supercooling heat exchanger, and the third pipeline is connected to the supercooling heat exchanger.

[0016] Furthermore, the insulating storage tank is also provided with a second pressure detection device for detecting the pressure inside the insulating storage tank. The supercooling unit adjusts the power of the supercooling unit according to the cabin pressure inside the insulating storage tank detected by the second pressure detection device. When the cabin pressure increases, the power of the supercooling unit increases, and when the cabin pressure decreases, the power of the supercooling unit decreases.

[0017] Furthermore, a first temperature sensor and a second temperature sensor are respectively provided on the inlet side and the outlet side of the subcooling heat exchanger, and the first temperature sensor and the second temperature sensor are respectively connected to the subcooling unit, and the subcooling unit controls the power of the subcooling unit according to the temperature difference between the first temperature sensor and the second temperature sensor.

[0018] Furthermore, the priority of the supercooling unit controlling the power of the supercooling unit according to the temperature difference is higher than the priority of the supercooling unit adjusting the power of the supercooling unit according to the cabin pressure in the insulated storage tank.

[0019] Furthermore, a first valve for opening and closing the fourth pipeline is provided on the fourth pipeline, and a second valve for opening and closing the fifth pipeline is provided on the fifth pipeline.

[0020] Furthermore, both the first valve and the second valve are remote-controlled valves.

[0021] Furthermore, a one-way valve is installed on the sixth pipeline.

[0022] Furthermore, the atomizer injector is arranged in the insulating tank at a position close to the top of the insulating tank.

[0023] Furthermore, the fifth pipeline also includes a mixing injector arranged at one end of the fifth pipeline. The mixing injector is placed in the insulating tank near the bottom of the insulating tank, and the mixing injector injects liquid ammonia horizontally or obliquely upward.

[0024] Furthermore, the first pressure detection device is arranged downstream of the pressure control valve, and the first pressure detection device is arranged close to the pressure control valve.

[0025] Furthermore, the boosting device includes a boosting pump, which is connected to the lower end of the buffer tank through a pipeline.

[0026] Furthermore, the first pipeline includes a liquid ammonia delivery pump, through which the liquid ammonia in the insulating storage tank flows to the buffer tank through the first pipeline.

[0027] The present invention also provides a method for supplying marine liquid ammonia fuel with a tank pressure control function. By means of the above-mentioned marine liquid ammonia fuel supply device with a tank pressure control function, the method comprises:

[0028] Step 1: Liquid ammonia in the insulating storage tank is transported to a buffer tank through a first pipeline, and the lower end of the buffer tank is connected to a pressurizing device through a pipeline;

[0029] Step 2: The booster device boosts the pressure of the liquid ammonia, and the boosted liquid ammonia passes through a heat exchanger and is cooled;

[0030] Step 3: After heat exchange and cooling in the heat exchanger, a portion of the liquid ammonia is transported to the ammonia fuel device for consumption through the second pipeline, and the liquid ammonia returned from the ammonia fuel device is returned to the buffer tank through the sixth pipeline; another portion of the liquid ammonia is returned through the third pipeline;

[0031] When the liquid ammonia flows back to the third pipeline, it passes through the pressure reducing device and the subcooling device in sequence, after being reduced in pressure by the pressure reducing device, it passes through the subcooling device to reduce in temperature;

[0032] If the liquid ammonia in the insulating storage tank is less than the set value, the liquid ammonia in the third pipeline flows back to the insulating storage tank through the first liquid ammonia reflux path; if the liquid ammonia in the insulating storage tank is not less than the set value, the liquid ammonia in the third pipeline flows back to the insulating storage tank through the second liquid ammonia reflux path.

[0033] Furthermore, the amount of liquid ammonia outputted by the heat exchanger is greater than the maximum consumption of the ammonia fuel device.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The marine liquid ammonia fuel supply system with a cabin pressure control function of the present invention is reliable and efficient. There is no phase change in the entire process. While providing liquid ammonia as fuel, the excess liquid ammonia is cryogenically cooled and returned to the insulated storage tank, bringing in cold energy, balancing the heat transmitted from the outside to the insulated storage tank, and reducing the evaporation of liquid ammonia, thereby controlling the cabin pressure, avoiding the emission of toxic ammonia, and protecting personnel safety.

[0036] 2. Utilizing the decompression and cooling characteristics of liquid ammonia, the excess liquid ammonia in a high-pressure and room-temperature state (the temperature rises after pressurization and needs to be cooled to room temperature of 25-40°C for use in ammonia fuel equipment) is decompressed to initially lower the temperature of the liquid ammonia, effectively reducing the cooling energy required for the next step of supercooling heat exchange.

[0037] 3. The pressure monitoring of the insulated storage tank provides a basis for the power control of the subcooling unit, achieving precise control of the cooling energy output of the subcooling unit and ensuring optimal energy efficiency.

[0038] 4. The setting of the fourth and fifth pipelines provides flexible options for the return of liquid ammonia to the tank, rationally and efficiently utilizes the cold energy brought by the returning liquid ammonia, effectively treats the ammonia in the insulating tank, reduces the evaporation of liquid ammonia, and ensures the balance and controllability of the pressure in the insulating tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the composition of the marine liquid ammonia fuel supply system with a tank pressure control function in the present invention.

[0040] In the figure, 1. Insulated storage tank; 2. Liquid ammonia delivery pump; 3. Buffer tank; 4. Booster pump; 5. Heat exchanger; 6. Pressure control valve; 7. First pressure detection device; 8. Pressure reducing control valve; 9. Subcooling heat exchanger; 10. Subcooling unit; 11. First valve; 12. Second valve; 13. Atomizer injector; 14. Mixing injector; 15. Second pressure detection device; 16. First temperature detection device; 17. Second temperature detection device; 18. One-way valve; 19. Ammonia fuel equipment; L1. First pipeline; L2. Second pipeline; L3. Third pipeline; L4. Fourth pipeline; L5. Fifth pipeline; L6. Sixth pipeline. Implementation Method

[0041] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0042] A marine liquid ammonia fuel supply system with a tank pressure control function, such as Figure 1 Shown, including:

[0043] Insulated storage tank 1, buffer tank 3, a pressurizing device for pressurizing liquid ammonia, a heat exchanger 5 for cooling liquid ammonia, and ammonia fuel equipment 19 using liquid ammonia as fuel; the buffer tank 3, the pressurizing device, and the heat exchanger 5 are sequentially connected by pipelines;

[0044] The insulating storage tank 1 may be a type A, type B, type C or membrane type containment system defined by the IMO (International Maritime Organization). The insulating storage tank 1 is arranged inside the hull structure or on the deck for storing liquid ammonia.

[0045] A first pipeline L1 is connected between the insulating storage tank 1 and the buffer tank 3 to transport the liquid ammonia in the insulating storage tank 1 to the buffer tank 3; the first pipeline L1 includes a liquid ammonia delivery pump 2, which extracts the liquid ammonia in the insulating storage tank 1. The outlet pressure of the liquid ammonia delivery pump 2 is about 23 bar gauge pressure. The liquid ammonia delivery pump 2 is installed in the insulating storage tank 1, such as a submersible pump or a deep well pump; it can also be a horizontal or vertical centrifugal pump, installed outside the insulating storage tank 1.

[0046] Buffer tank 3 is insulated and designed to operate at a pressure no less than the maximum operating pressure of liquid ammonia delivery pump 2. The boosting device includes a booster pump 4, connected to the lower end of buffer tank 3 via a pipeline. This ensures that the suction port of booster pump 4 maintains a constant pressure to prevent cavitation. The outlet pressure of booster pump 4 is approximately 83 barg. The boosted liquid ammonia meets the requirements of the ammonia fuel system. The designed displacement of booster pump 4 is the same as that of the liquid ammonia delivery pump, both exceeding the maximum consumption of the ammonia fuel system.

[0047] Heat exchanger 5 can be a plate and shell heat exchanger, shell and tube heat exchanger, or coiled-wound heat exchanger. It is connected to the outlet of booster pump 4 via piping to cool the pressurized liquid ammonia, bringing it down to room temperature (25-40°C) to meet the requirements of the ammonia fuel system. Heat exchanger 5 uses a room-temperature cooling source, which can be air-cooled or liquid-cooled. The liquid cooling medium can be fresh water, seawater, or an ethylene glycol solution.

[0048] A second pipeline L2, used to deliver liquid ammonia to the ammonia fueling device, is connected between the heat exchanger 5 and the ammonia fueling device 19. This second pipeline L2 includes a pressure control valve 6 for adjusting the pressure of the liquid ammonia within the second pipeline L2 to match the ammonia fueling device's load. It also includes a first pressure sensing device 7 for detecting the pressure of the liquid ammonia within the second pipeline L2. The first pressure sensing device 7 is located downstream of and adjacent to the pressure control valve 6. The first pressure sensing device 7 monitors the pressure fluctuations of the liquid ammonia within the second pipeline L2 caused by changes in the load of the ammonia fueling device 19, controls the opening of the pressure control valve 6, and adjusts the pressure of the liquid ammonia at the inlet of the ammonia fueling device 19 to meet the operating pressure requirements of the ammonia fueling device under different operating conditions.

[0049] The heat exchanger 5 is also connected to a third pipeline L3 for returning liquid ammonia not consumed by the ammonia fuel equipment to the insulated storage tank. One end of the third pipeline L3 is connected to the heat exchanger 5, and the other end of the third pipeline L3 is connected to a fourth pipeline L4 and a fifth pipeline L5. The fourth pipeline L4 includes an atomizer injector 13; the third pipeline L3 is provided with a pressure reducing device for reducing the pressure of liquid ammonia and a supercooling device for reducing the temperature of liquid ammonia, and the pressure reducing device is such as a pressure reducing control valve 8.

[0050] The subcooling device includes a subcooling unit 10 and a subcooling heat exchanger 9. The subcooling unit 10 provides refrigerant for the subcooling heat exchanger 9, and a third pipeline L3 connects to the subcooling heat exchanger 9. Excess high-pressure liquid ammonia (pressurized by the booster pump) is reduced in pressure by the pressure-reducing control valve 8 to 5 bar gauge, which also reduces the temperature of the liquid ammonia. The subcooling heat exchanger 9, installed downstream of the pressure-reducing control valve 8, further cools the depressurized liquid ammonia, achieving a subcooled state.

[0051] The subcooling heat exchanger 9 can be a plate and shell heat exchanger, a shell and tube heat exchanger or a coiled heat exchanger. The cold source comes from the subcooling unit 10. The subcooling unit 10 is composed of a refrigerant compressor, a refrigerant cooler, an expansion valve and other equipment. The refrigerant compressor is frequency-controlled and the expansion valve opening is adjustable. The subcooling unit 10 compresses and cools the gaseous refrigerant into a high-pressure, liquid refrigerant. After the high-pressure, liquid refrigerant is decompressed by the expansion valve, it enters the subcooling heat exchanger to absorb heat and evaporate, completing the heat exchange with the decompressed liquid ammonia. Refrigerants such as ammonia and Freon are used.

[0052] The third and fourth pipelines L3 and L4 are connected to the insulated storage tank 1 to form a first liquid ammonia return path. The third and fifth pipelines L3 and L5 are connected to the insulated storage tank 1 to form a second liquid ammonia return path. When the liquid ammonia level in the insulated storage tank 1 is less than a set value, the liquid ammonia in the third pipeline L3 flows back to the insulated storage tank 1 via the first liquid ammonia return path. When the liquid ammonia level in the insulated storage tank 1 is not less than the set value, the liquid ammonia in the third pipeline L3 flows back to the insulated storage tank 1 via the second liquid ammonia return path.

[0053] The insulating storage tank 1 is also equipped with a second pressure detection device 15, such as a pressure sensor, for detecting the pressure within the insulating storage tank 1. The second pressure detection device 15 is mounted on the top of the insulating storage tank 1 to monitor the pressure within the insulating storage tank 1 in real time. The subcooling unit 10 adjusts its power based on the cabin pressure within the insulating storage tank 1 detected by the second pressure detection device 15. The power of the subcooling unit 10 increases when the cabin pressure increases, and decreases when the cabin pressure decreases.

[0054] A first temperature sensor 16 and a second temperature sensor 17 are respectively provided on the inlet side and the outlet side of the subcooling heat exchanger 9, and the temperature change of the liquid ammonia after passing through the subcooling heat exchanger 9 is monitored by the first temperature sensor 16 and the second temperature sensor 17; the first temperature sensor 16 and the second temperature sensor 17 are respectively connected to the subcooling unit 10, and the subcooling unit 10 controls the power of the subcooling unit according to the temperature difference between the first temperature sensor 16 and the second temperature sensor 17.

[0055] The priority of controlling the power of the supercooling unit 10 according to the temperature difference is higher than the priority of adjusting the power of the supercooling unit 10 according to the cabin pressure in the insulated storage tank 1 .

[0056] The fourth pipeline L4 is also provided with a first valve 11 for opening and closing the fourth pipeline, and the fifth pipeline L5 is also provided with a second valve 12 for opening and closing the fifth pipeline. Both the first valve 11 and the second valve 12 are remote control valves, which are driven electrically or hydraulically and have an emergency manual switch function.

[0057] An atomizer injector 13 is provided at the end of the fourth pipeline L4. Atomizer injectors 13 are located within the insulating storage tank 1, near the top of the insulating storage tank 1. There may be one or more atomizer injectors 13, and the atomizer injectors 13 are always within the gas space within the insulating storage tank 1. The fifth pipeline L5 also includes a mixing injector 14 provided at one end of the fifth pipeline. Mixing injector 14 is located within the insulating storage tank 1, near the bottom of the insulating storage tank. Mixing injector 14 sprays liquid ammonia horizontally or obliquely upward.

[0058] A sixth pipeline L6 is also connected between the ammonia fuel device 19 and the buffer tank 3 for returning liquid ammonia from the ammonia fuel device to the buffer tank 3. One end of the sixth pipeline L6 is connected to the top of the buffer tank 3, and a one-way valve 18 is also installed on the sixth pipeline L6.

[0059] This embodiment further provides a method for supplying liquid ammonia fuel for a ship with a tank pressure control function. By using the liquid ammonia fuel supply device for a ship with a tank pressure control function in the above embodiment, the method includes:

[0060] Step 1: Liquid ammonia in the insulating storage tank 1 is transported to the buffer tank 3 through the first pipeline L1, and the lower end of the buffer tank 3 is connected to the boosting device through a pipeline;

[0061] Step 2: The booster device boosts the pressure of the liquid ammonia to 83 bar gauge. The temperature of the liquid ammonia rises after the boosting. The boosted liquid ammonia passes through the heat exchanger 5 and is cooled to 25-40°C.

[0062] Step 3: After heat exchange and cooling in the heat exchanger 5, a portion of the liquid ammonia is transported to the ammonia fuel device 19 for consumption through the second pipeline L2. The first pressure detection device 7 installed on the second pipeline L2 is used to adjust the opening of the pressure control valve 6 to ensure that the pressure at the inlet of the ammonia fuel device 19 always meets the requirements of the device under different load conditions. The liquid ammonia returning from the ammonia fuel device 19 is returned to the buffer tank 3 through the sixth pipeline L6. A one-way valve 18 is installed on the sixth pipeline L6 to prevent the gas and liquid ammonia in the buffer tank 3 from flowing back into the ammonia fuel device 19.

[0063] Since the designed displacement of the liquid ammonia delivery pump 2 and the booster pump 4 is greater than the maximum consumption of the ammonia fuel equipment 19 during the design and selection, there is always excess high-pressure liquid ammonia returning to the insulated storage tank 1 and refluxed through the third pipeline L3; the deep-cold liquid ammonia returns to the insulated storage tank 1, bringing in cold energy, balancing the heat from the outside of the insulated storage tank 1 and the heat generated by the operation of the liquid ammonia delivery pump 2 in the insulated storage tank 1 (when the liquid ammonia delivery pump is installed in the insulated storage tank), thereby reducing the generation of volatile gas and controlling the internal pressure of the insulated storage tank 1.

[0064] In the third pipeline L3, it passes through the pressure reducing device and the subcooling device in sequence, and is reduced to 5 bar gauge pressure by the pressure reducing device (pressure reducing control valve), and is in a subcooled state; the subcooled liquid ammonia enters the subcooling heat exchanger 9 and completes heat exchange with the refrigerant from the subcooling unit 10, and is further cooled to -36°C. At this time, the pressure of the liquid ammonia is 5 bar, and it is in a deep cold state.

[0065] Since the liquid ammonia in the insulating storage tank 1 is continuously consumed, if the liquid ammonia in the insulating storage tank 1 is less than the set liquid level height value, the liquid ammonia in the third pipeline L3 flows back to the insulating storage tank 1 through the first liquid ammonia return path; when the liquid level is lower than the set liquid level height value, the gas space in the insulating storage tank 1 is larger, and the atomizer injector 13 is set in the fourth pipeline L4. The atomizer injector can effectively increase the contact area between the deep-cold liquid ammonia and the gas in the insulating storage tank 1, thereby enhancing the heat exchange effect. During the descent process, the atomized deep-cold liquid ammonia exchanges heat with the volatile gas in the insulating storage tank 1. The atomized liquid ammonia releases cold energy and its temperature rises to the saturation temperature. After absorbing the cold energy, the volatile gas in the insulating storage tank 1 turns into liquid again, reducing the volatile gas in the insulating storage tank 1 and achieving the purpose of controlling the cabin pressure.

[0066] If the liquid ammonia level in insulating tank 1 is at least the set level, indicating a relatively high level of liquid ammonia, the liquid ammonia in third pipeline L3 will flow back to insulating tank 1 via the second liquid ammonia return path. The mixing ejector 14 in fifth pipeline L5 ejects cryogenically cooled liquid ammonia from mixing ejector 4 into insulating tank 1 at a predetermined pressure, creating convection within the liquid space and effectively transferring cold energy into the liquid ammonia in insulating tank 1. This reduces volatile gas generation and controls the pressure within insulating tank 1. This requires that the liquid level of mixing ejector 14 within insulating tank 1 must not be lower than the installation location of mixing ejector 14.

[0067] In the third pipeline L3, the load control of the subcooling unit 10 is achieved through the first temperature sensor 16, the second temperature sensor 17 and the second pressure detection device 15, specifically including:

[0068] First, the second pressure detection device 15 monitors the pressure inside the insulating tank 1. When the pressure inside the insulating tank 1 increases, the second pressure detection device 15 sends an instruction to the subcooling unit 10 through the integrated control system to increase the workload of the subcooling unit 10; when the pressure inside the insulating tank 1 decreases, the workload of the subcooling unit 10 is reduced. The workload adjustment of the subcooling unit 10 can be achieved by adjusting the speed of the refrigerant compressor and the opening of the expansion valve.

[0069] Secondly, the capacity of the liquid ammonia transfer pump 2 and booster pump 4 is designed based on the maximum fuel consumption of the ammonia fuel system, plus the amount of liquid ammonia returned to the insulated storage tank 1 to control its pressure. The amount of liquid ammonia returned to the insulated storage tank is calculated based on the temperature difference between the inlet and outlet of the subcooling heat exchanger 9 (i.e., the temperature difference between the temperatures measured by the first temperature sensor 16 and the second temperature sensor 17). This is the amount of liquid ammonia required to bring cooling energy into the insulated storage tank 1 to control its pressure. The formula for calculating the amount of liquid ammonia returned to the insulated storage tank is as follows:

[0070] M 返 =Q 冷 / (C 压 (T 入 -T 出 ))

[0071] In the above formula:

[0072] M 返 : The amount of liquid ammonia required to return to the tank to maintain the pressure of the insulation tank (unit: kg / h)

[0073] Q 冷 : The cooling energy brought into the cabin by the liquid ammonia returning to the cabin is equal to the heat from the outside entering the insulated storage tank (unit: KW);

[0074] C 压 : Specific heat capacity of liquid ammonia at constant pressure (unit: kj / kg*K)

[0075] T 入 : Liquid ammonia inlet temperature of subcooling heat exchanger (unit: K)

[0076] T 出 : Liquid ammonia outlet temperature of the subcooling heat exchanger (unit: K)

[0077] First and second temperature sensors 16, 17 monitor the temperature changes of liquid ammonia passing through subcooling heat exchanger 9 in real time. When the temperature difference reaches a set value, an alarm is issued, prompting operator intervention. The current load of subcooling unit 10 is locked to prevent further increase in the temperature difference, which could threaten system safety. Considering system safety and the pressure range of the insulated tank, subcooling unit load control prioritizes temperature differential control over tank pressure control.

[0078] This embodiment is only a further explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A marine liquid ammonia fuel supply system with a tank pressure control function, characterized in that: include: An insulating storage tank, a buffer tank, a pressurizing device for pressurizing liquid ammonia, a heat exchanger for cooling liquid ammonia, and an ammonia fuel device using liquid ammonia as fuel; the buffer tank, the pressurizing device, and the heat exchanger are sequentially connected by pipelines; A first pipeline for transporting liquid ammonia in the insulating storage tank to the buffer tank is connected between the insulating storage tank and the buffer tank; A second pipeline for conveying liquid ammonia to the ammonia fuel device is connected between the heat exchanger and the ammonia fuel device; The heat exchanger is further connected to a third pipeline for returning liquid ammonia not consumed by the ammonia fuel device to the insulated storage tank. One end of the third pipeline is connected to the heat exchanger, and the other end of the third pipeline is connected to a fourth pipeline and a fifth pipeline. The fourth pipeline includes an atomizer injector. The third pipeline is provided with a pressure reducing device for reducing the pressure of the liquid ammonia and a subcooling device for reducing the temperature of the liquid ammonia. The third pipeline, the fourth pipeline, and the insulating storage tank are connected to form a first liquid ammonia return path, and the third pipeline, the fifth pipeline, and the insulating storage tank are connected to form a second liquid ammonia return path. When the liquid ammonia in the insulating storage tank is less than a set value, the liquid ammonia in the third pipeline flows back to the insulating storage tank through the first liquid ammonia return path. When the liquid ammonia in the insulating storage tank is not less than the set value, the liquid ammonia in the third pipeline flows back to the insulating storage tank through the second liquid ammonia return path. A sixth pipeline is further connected between the ammonia fuel device and the buffer tank, for returning liquid ammonia from the ammonia fuel device to the buffer tank; The subcooling device includes a subcooling unit and a subcooling heat exchanger. The subcooling unit provides refrigerant for the subcooling heat exchanger. The third pipeline is connected to the subcooling heat exchanger. The insulating tank is also provided with a second pressure detection device for detecting the pressure inside the insulating tank. The subcooling unit adjusts the power of the subcooling unit according to the cabin pressure inside the insulating tank detected by the second pressure detection device. When the cabin pressure increases, the power of the subcooling unit increases, and when the cabin pressure decreases, the power of the subcooling unit decreases. A first temperature sensor and a second temperature sensor are respectively provided on the inlet side and the outlet side of the subcooling heat exchanger. The first temperature sensor and the second temperature sensor are respectively connected to the subcooling unit. The subcooling unit controls the power of the subcooling unit according to the temperature difference between the first temperature sensor and the second temperature sensor. The priority of the subcooling unit controlling the power of the subcooling unit according to the temperature difference is higher than the priority of the subcooling unit adjusting the power of the subcooling unit according to the cabin pressure inside the insulating tank.

2. A marine liquid ammonia fuel supply system with a tank pressure control function according to claim 1, characterized in that: The second pipeline includes a pressure control valve for adjusting the pressure of liquid ammonia in the second pipeline to adapt to the ammonia fuel equipment, and also includes a first pressure detection device for detecting the pressure of liquid ammonia in the second pipeline.

3. A marine liquid ammonia fuel supply system with a tank pressure control function according to claim 1, characterized in that: The fourth pipeline is further provided with a first valve for opening and closing the fourth pipeline, and the fifth pipeline is further provided with a second valve for opening and closing the fifth pipeline.

4. A marine liquid ammonia fuel supply system with a tank pressure control function according to claim 3, characterized in that: The first valve and the second valve are both remote-controlled valves.

5. The marine liquid ammonia fuel supply system with tank pressure control function according to claim 1, characterized in that: A one-way valve is also installed on the sixth pipeline.

6. A marine liquid ammonia fuel supply system with a tank pressure control function according to claim 1, characterized in that: The atomizer injector is arranged in the insulating storage tank at a position close to the top of the insulating storage tank.

7. The marine liquid ammonia fuel supply system with tank pressure control function according to claim 1, characterized in that: The fifth pipeline further includes a mixing injector arranged at one end of the fifth pipeline. The mixing injector is placed in the insulating tank near the bottom of the insulating tank, and the mixing injector injects liquid ammonia horizontally or obliquely upward.

8. The marine liquid ammonia fuel supply system with a tank pressure control function according to claim 2, characterized in that: The first pressure detection device is arranged downstream of the pressure control valve, and the first pressure detection device is arranged close to the pressure control valve.

9. The marine liquid ammonia fuel supply system with tank pressure control function according to claim 1, characterized in that: The boosting device includes a boosting pump, and the boosting pump is connected to the lower end of the buffer tank through a pipeline.

10. The marine liquid ammonia fuel supply system with a tank pressure control function according to claim 1, characterized in that: The first pipeline includes a liquid ammonia delivery pump.

11. A method for supplying marine liquid ammonia fuel with a tank pressure control function, characterized in that: By means of the marine liquid ammonia fuel supply system with a tank pressure control function according to any one of claims 1 to 10, the method comprises: Step 1: The liquid ammonia in the insulating storage tank is transported to the buffer tank through a first pipeline, and the lower end of the buffer tank is connected to the boosting device through a pipeline; Step 2: The booster device boosts the pressure of the liquid ammonia, and the boosted liquid ammonia passes through a heat exchanger and is cooled; Step 3: After heat exchange and cooling in the heat exchanger, a portion of the liquid ammonia is transported to the ammonia fuel device for consumption through the second pipeline, and the liquid ammonia returned from the ammonia fuel device is returned to the buffer tank through the sixth pipeline; another portion of the liquid ammonia is returned through the third pipeline; When the liquid ammonia flows back to the third pipeline, it passes through the pressure reducing device and the subcooling device in sequence, after being reduced in pressure by the pressure reducing device, it passes through the subcooling device to reduce in temperature; If the liquid ammonia in the insulating storage tank is less than the set value, the liquid ammonia in the third pipeline flows back to the insulating storage tank through the first liquid ammonia reflux path; if the liquid ammonia in the insulating storage tank is not less than the set value, the liquid ammonia in the third pipeline flows back to the insulating storage tank through the second liquid ammonia reflux path.

12. A method for supplying marine liquid ammonia fuel with a tank pressure control function according to claim 11, characterized in that: The amount of liquid ammonia output by the heat exchanger is greater than the maximum consumption of the ammonia fuel equipment.

Images