Marine liquid ammonia fuel filling system and cabin pressure control method

Abstract

The invention discloses a marine liquid ammonia fuel filling system and a cabin pressure control method.The filling system comprises a liquid adding system, an ammonia gas backflow system, an ammonia gas recovery system and a liquid ammonia gasification system, the liquid adding system comprises a first cabin and a second cabin, and the first cabin fills liquid ammonia into the second cabin; the ammonia gas backflow system transfers gaseous ammonia in the second cabin to the first cabin, so that the purpose of controlling the pressure of the two cabins is achieved; the ammonia gas recovery system is used for liquefying and returning excessive ammonia gas from the second cabin to the cabin or absorbing and storing the excessive ammonia gas; and the liquid ammonia gasification system performs the function of controlling the pressure of the first cabin by gasifying part of liquid ammonia injected into the second cabin from the first cabin and then returning the liquid ammonia to the first cabin. By means of the liquid ammonia fuel filling system and the cabin pressure control method, the problem of safe and efficient filling of marine fuel liquid ammonia is solved, emission of poisonous gas in the filling process is prevented, resource waste and environmental pollution are avoided, and development of green ships is effectively assisted.

Description

Technical Field

[0001] The present application relates to the technical field of ship engineering equipment, and particularly relates to a marine liquid ammonia fuel filling system and a cabin pressure control method. Background Art

[0002] Currently, the International Maritime Organization (IMO) has established a relatively complete greenhouse gas emission reduction target system, and the emission reduction targets are becoming increasingly stringent. In its latest emission reduction strategy, IMO proposed to quickly peak the greenhouse gas emissions of international shipping and achieve "net zero emissions" of greenhouse gases by or around 2050, taking into account different national conditions.

[0003] As an inorganic compound composed of hydrogen and nitrogen, ammonia, due to its carbon-free nature, is considered one of the most promising fuels in the future decarbonized shipping industry together with hydrogen, and has attracted increasing attention from shipping companies.

[0004] With the installation and application of the world's first dual-fuel low-speed engine powered by liquid ammonia on a ship in 2024, ammonia fuel ships have entered a stage of substantial development.

[0005] With the development of ammonia fuel ships, the problem of how to efficiently and safely fill ammonia fuel for ships will become increasingly prominent. Currently, there is no mature and efficient solution. The conventional method is to transport liquid ammonia to the wharf by tank trucks and fill ammonia fuel for ships through a filling skid block installed on the wharf. This method has low filling efficiency and long filling time. The overly long filling time greatly increases the risk of filling operations. How to efficiently and safely fill liquid ammonia fuel for ships has become an important factor restricting the development of ammonia fuel ships. Summary of the Invention

[0006] To solve the above problems, the present invention provides a marine liquid ammonia fuel filling system and a cabin pressure control method to solve technical problems such as cabin pressure control, excessive ammonia gas treatment, and prevention of toxic gas emissions during the filling process of liquid ammonia fuel ships, and meet the requirements of ships for large-scale, safe, and efficient filling of liquid ammonia fuel.

[0007] In a first aspect, an embodiment of the present invention provides a marine liquid ammonia fuel filling system, including: a liquid filling system, an ammonia gas reflux system, an ammonia gas recovery system, and a liquid ammonia gasification system

[0008] The liquid filling system includes a first chamber and a second chamber, and the first chamber fills liquid ammonia into the second chamber;

[0009] The ammonia gas reflux system transfers the gaseous ammonia in the second chamber to the first chamber to achieve the purpose of controlling the pressures of the two chambers;

[0010] The ammonia recovery system liquefies and returns the excess ammonia from the second chamber to the chamber or absorbs and stores it.

[0011] The liquid ammonia vaporization system controls the pressure in the first chamber by vaporizing a part of the liquid ammonia filled from the first chamber into the second chamber and then returning it to the first chamber.

[0012] In some embodiments, a filling pump is provided in the first chamber.

[0013] The outlet of the filling pump is connected to a filling pipe, the other end of the filling pipe is connected to a liquid filling hose, and the liquid filling hose is connected to a receiving pipe.

[0014] The other end of the receiving pipe opens in the second chamber, and its opening position includes the bottom or / and the top.

[0015] In some embodiments, one end of the gas collecting pipe opens at the top of the second chamber, the other end is connected to a return air hose, the return air hose is connected to a return air pipe, and the other end of the return air pipe opens at the top of the first chamber, and a gas recovery pipe and a vaporization branch pipe are connected thereto.

[0016] In some embodiments, the liquid filling hose and the return air hose include: a composite material cryogenic hose, a vacuum insulated hose or a marine filling arm.

[0017] In some embodiments, the vaporization branch pipe is provided on the filling pipe.

[0018] One end of the vaporization branch pipe is connected to the filling pipe, the other end is connected to the return air pipe, and a fourth pressure control valve is provided thereon. The fourth pressure control valve is controlled by a second pressure sensor to open and close.

[0019] The second pressure sensor is installed on the top of the first chamber for monitoring the pressure in the gas phase space in the first chamber.

[0020] The outlet of the fourth pressure control valve is connected to a vaporizer for vaporizing liquid ammonia, and the vaporized ammonia is returned to the first chamber through the return air pipe.

[0021] In some embodiments, the vaporizer includes a plate type, a shell and tube type or a printed circuit board type heat exchanger, and the heat exchange medium includes seawater, fresh water or ethylene glycol water.

[0022] In some embodiments, a first pressure control valve and a pressure regulating valve are installed in parallel on the return air pipe. The first pressure control valve is controlled by a first pressure sensor to open and close.

[0023] The pressure regulating valve can control the return air pressure within a set range.

[0024] The first pressure sensor is installed downstream of the first pressure control valve and the pressure regulating valve connected in parallel;

[0025] A second pressure control valve is further installed on the return air pipe. The second pressure control valve is installed downstream of the first pressure sensor and its opening and closing are controlled by the second pressure sensor.

[0026] In some embodiments, the gas recovery pipe is connected to the return air pipe on the pipeline between the first pressure sensor and the second pressure control valve.

[0027] In some embodiments, a third pressure control valve is provided on the gas recovery pipe;

[0028] The opening and closing of the third pressure control valve are controlled by the second pressure sensor;

[0029] The downstream of the third pressure control valve is respectively connected to a liquefied return pipe and an ammonia absorption pipe, and one of them can be selected by operating the opening and closing of the first isolation valve and the second isolation valve.

[0030] In a second aspect, an embodiment of the present invention provides a method for controlling the cabin pressure for liquid ammonia filling, which is used to control the marine liquid ammonia filling system described in any embodiment of the first aspect. The method includes:

[0031] Step 1: Use a filling pump to fill liquid ammonia from the first cabin to the second cabin. As the liquid ammonia transfers from the first cabin to the second cabin, the liquid levels of the two cabins change accordingly. The liquid level in the first cabin drops, the gas phase space increases, the liquid level in the second cabin rises, and the gas phase space decreases;

[0032] Step 2: The ammonia gas returned from the second cabin passes through the first pressure control valve and the pressure regulating valve installed in parallel. When the first pressure sensor monitors that the pressure is less than the set value, the first pressure control valve opens. Since the resistance of the pressure regulating valve is large, at this time, the returned ammonia gas preferentially returns to the first cabin through the first pressure control valve with smaller resistance; when the pressure monitored by the first pressure sensor reaches or exceeds the set value, the first pressure control valve is closed. At this time, the returned ammonia gas flows through the pressure regulating valve and returns to the first cabin after decompression;

[0033] Step 3: When the ammonia gas pressure in the first cabin monitored by the second pressure sensor does not reach the high-pressure set value, the second pressure control valve opens, and the third pressure control valve on the gas recovery pipe remains closed. The decompressed returned ammonia gas returns to the first cabin; when the ammonia gas pressure monitored by the second pressure sensor reaches or exceeds the set value, the second pressure control valve is closed, and the third pressure control valve is opened. At this time, the amount of the returned ammonia gas exceeds the amount required to maintain the pressure in the cabin, and the excessive returned ammonia gas enters the ammonia gas recovery system;

[0034] Step 4: Recovery of the excessive ammonia gas returned by the ammonia recovery system;

[0035] Step 5: During the filling process, when the pressure in the first compartment monitored by the second pressure sensor installed on the top of the first compartment reaches or is lower than the low-pressure set value, the fourth pressure control valve is opened, and the liquid ammonia filled into the second compartment is shunted through the gasification branch pipe. The shunted liquid ammonia is gasified by the gasifier, and the gasified ammonia gas is returned to the first compartment through the gas return pipe to increase the pressure in the gas phase space of the first compartment; when the pressure monitored by the second pressure sensor reaches the reset set value, the fourth pressure control valve is closed, and the liquid ammonia gasification process ends.

[0036] Compared with the prior art, the marine liquid ammonia fuel filling system and the cabin pressure control method of the above embodiments of the present invention have the following technical advantages:

[0037] Utilizing the characteristics of high cargo capacity of the ship, realizing large-batch and efficient filling of liquid ammonia fuel, effectively saving the filling operation time and improving the operation efficiency of the ship;

[0038] By installing a pressure regulating valve in parallel on the gas return pipe, the applicability of the liquid ammonia filling system is effectively enhanced, and fuel compartments with different designed cabin pressures (high-pressure cabins, low-pressure cabins) are compatible, greatly improving the versatility of the filling system;

[0039] According to the actual filling operation situation, the set value of the pressure sensor is flexibly adjusted to accurately control the cabin pressure during the filling process, ensuring the efficient and safe implementation of the filling operation;

[0040] Designing multiple application processes, and the return gas can be processed through different processes according to the pressure of the return gas and the first compartment, effectively improving the flexibility of the system of the present invention. Description of the Drawings

[0041] The drawings generally show, by way of example and not limitation, the various embodiments discussed herein.

[0042] Figure 1 It is a schematic structural diagram of the marine liquid ammonia fuel filling system of the present invention;

[0043] Figure 2 It is a division diagram of the marine liquid ammonia fuel filling system of the present invention.

[0044] Symbol Explanation:

[0045] The first compartment 1, the second compartment 2, the filling pump 3, the liquid filling hose 4, the return air hose 5, the first pressure control valve 6, the pressure regulating valve 7, the first pressure sensor 8, the second pressure control valve 9, the third pressure control valve 10, the second pressure sensor 11, the first isolation valve 12, the ammonia compressor 13, the liquefaction device 14, the second isolation valve 15, the ammonia absorption tank 16, the ammonia water circulation and delivery pump 17, the liquid level measuring instrument 18, the liquid level control valve 19, the check valve 20, the nozzle 21, the first remote control valve 22, the second remote control valve 23, the hose 24, the ammonia water storage tank 25, the ammonia water concentration measuring instrument 26, the liquid level gauge 27, the fourth pressure control valve 28, the vaporizer 29, the filling pipe L1, the receiving pipe L2, the gas collecting pipe L3, the return air pipe L4, the gas recovery pipe L5, the liquefaction return pipe L6, the ammonia absorption pipe L7, the vaporization branch pipe L8, the pressure balance pipe L9, the absorption liquid supply pipe L10, the I liquid filling system, the II ammonia return system, the III ammonia recovery system, and the IV liquid ammonia vaporization system. Specific embodiments

[0046] In order to be able to understand the features and technical content of the embodiments of the present application in more detail, the implementation of the embodiments of the present application will be described in detail below in conjunction with the attached drawings. The attached drawings are only for reference and illustration purposes and are not used to limit the embodiments of the present application.

[0047] In the description of the embodiments of the present application, it should be noted that unless otherwise stated and defined, the term "connection" should be understood in a broad sense. For example, it can be an electrical connection, or it can be the communication inside two components. It can be directly connected, or it can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms can be understood according to the specific situation.

[0048] It should be noted that the terms "first / second / third" involved in the embodiments of the present application are only used to distinguish similar objects and do not represent a specific order for the objects. It can be understood that "first / second / third" can be interchanged with a specific order or sequence when permitted. It should be understood that the objects distinguished by "first / second / third" can be interchanged under appropriate circumstances so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here.

[0049] The technical solutions of the present invention will be further described below in conjunction with the specific embodiments:

[0050] A marine liquid ammonia fuel filling system, as Figure 2 shown, includes: the liquid filling system I, the ammonia return system II, the ammonia recovery system III, and the liquid ammonia vaporization system IV. As Figure 1As shown in the figure, the liquid filling system I includes a first chamber 1 and a second chamber 2. The first chamber 1 fills the second chamber 2 with liquid ammonia; the ammonia gas reflux system II transfers the gaseous ammonia in the second chamber 2 to the first chamber 1 to achieve the purpose of controlling the pressures of the two chambers; the ammonia gas recovery system III liquefies and returns or absorbs and stores the excessive ammonia gas from the second chamber 2; the liquid ammonia vaporization system IV controls the pressure of the first chamber 1 by vaporizing part of the liquid ammonia filled from the first chamber 1 to the second chamber 2 and then returning it to the first chamber 1.

[0051] Specifically, a filling pump 3 is provided in the first chamber 1. The filling pump 3 can be a submersible pump or a deep well pump, and its outlet is connected to a filling pipe L1; the other end of the filling pipe L1 is connected to a filling hose 4, and the filling hose 4 is connected to a receiving pipe L2; the other end of the receiving pipe L2 opens in the second chamber 2, and its opening position can be at the bottom or / and the top.

[0052] Specifically, one end of a gas collecting pipe L3 opens at the top of the second chamber 2, and the other end is connected to a return air hose 5. The return air hose 5 is connected to a return air pipe L4, and the other end of the return air pipe L4 opens at the top of the first chamber 1. A gas recovery pipe L5 and a vaporization branch pipe L8 are connected to the return air pipe L4.

[0053] Specifically, the filling hose 4 and the return air hose 5 can be composite material cryogenic hoses or vacuum insulated hoses, or they can also be marine filling arms.

[0054] Specifically, the vaporization branch pipe L8 is arranged on the filling pipe L1. One end of the vaporization branch pipe L8 is connected to the filling pipe L1, and the other end is connected to the return air pipe L4. A fourth pressure control valve 28 is provided on it. The fourth pressure control valve 28 is controlled by a second pressure sensor 11 to switch; the second pressure sensor 11 is installed on the top of the first chamber 1 to monitor the pressure in the gas phase space of the first chamber 1; the outlet of the fourth pressure control valve 28 is connected to a vaporizer 29 for vaporizing liquid ammonia, and the vaporized ammonia gas is returned to the first chamber 1 through the return air pipe L4.

[0055] Specifically, the vaporizer 29 can be a plate type, shell and tube type or printed circuit board type heat exchanger, and the heat exchange medium can be seawater, fresh water or ethylene glycol water.

[0056] Specifically, a first pressure control valve 6 and a pressure regulating valve 7 are installed in parallel on the return air pipe L4. The first pressure control valve 6 is controlled by a first pressure sensor 8 to switch; the pressure regulating valve 7 can control the return air pressure within a set range; the first pressure sensor 8 is installed downstream of the parallel first pressure control valve 6 and pressure regulating valve 7; a second pressure control valve 9 is also installed on the return air pipe L4. The second pressure control valve 9 is installed downstream of the first pressure sensor 8 and is controlled by the second pressure sensor 11 to switch.

[0057] Specifically, a gas recovery pipe L5 is connected to the return air pipe L4, and the gas recovery pipe L5 is connected to the return air pipe L4 on the pipeline between the first pressure sensor 8 and the second pressure control valve 9.

[0058] Specifically, a third pressure control valve 10 is provided on the gas recovery pipe L5; the third pressure control valve 10 is controlled to open and close by the second pressure sensor 11; the downstream of the third pressure control valve 10 is respectively connected to the liquefied return pipe L6 and the ammonia absorption pipe L7, and one of them can be selected by operating the switches of the first isolation valve 12 and the second isolation valve 15.

[0059] Specifically, a first isolation valve 12 is provided on the liquefied return pipe L6. The first isolation valve 12 can be manual or remote control. The recycled ammonia enters the ammonia compressor 13 through the first isolation valve 12. The ammonia compressor 13 boosts the pressure of the ammonia to 8 bar. The pressurized ammonia enters the liquefaction device 14 for normal temperature liquefaction. The refrigerant of the liquefaction device 14 can be fresh water, seawater or ethylene glycol water. The liquefied liquid ammonia is returned to the first cabin 1 through the liquefied return pipe L6. The liquefied return pipe L6 opens at the bottom of the first cabin 1.

[0060] Specifically, a second isolation valve 15 is provided on the ammonia absorption pipe L7. The second isolation valve 15 can be manual or remote control. The recycled ammonia enters the ammonia absorption tank 16 through the second isolation valve 15, and the ammonia is absorbed by using the absorbent to form ammonia water; the absorbent can be water or sodium chloride solution; the ammonia absorption tank 16 is made of a material resistant to ammonia water corrosion or has a coating resistant to ammonia water corrosion inside, and is provided with a plurality of interfaces, which are respectively connected to the ammonia absorption pipe L7, the absorbent supply pipe L10, the ammonia water outlet pipe, the pressure balance pipe L9 and the ammonia water circulation pipe; the ammonia absorption tank 16 is also equipped with a liquid level measuring instrument 18.

[0061] Specifically, a liquid level control valve 19 is installed on the absorbent supply pipe L10. The liquid level control valve 19 is controlled to open and close by the liquid level measuring instrument 18 installed on the ammonia absorption tank 16. A one-way valve 20 is also installed on the absorbent supply pipe L10 to prevent ammonia from flowing back into the absorbent supply system; the absorbent supply pipe L10 enters the ammonia absorption tank 16 from the top and is arranged in a ring shape or a "Z" shape in the tank, and a plurality of spray nozzles 21 are evenly arranged. The material of the spray nozzles 21 can withstand the corrosion of ammonia water and has an atomization effect. The absorbent is sprayed into the ammonia absorption tank 16 through the spray nozzles 21 and fully contacts with the ammonia entering from the lower part to form ammonia water, which is collected at the bottom of the ammonia absorption tank 16. As the ammonia water is continuously formed, the liquid level of the ammonia water in the ammonia absorption tank 16 continuously rises and is monitored in real time by the liquid level measuring instrument 18. When the measured liquid level reaches the set value, the liquid level measuring instrument 18 controls the liquid level control valve 19 to close and cuts off the entry of the absorbent; at the same time, the ammonia water circulation and delivery pump 17 is started.

[0062] Specifically, an ammonia water outlet is provided at the bottom of the ammonia absorption tank 16. The ammonia water outlet is connected to the suction port of the ammonia water circulation transfer pump 17. The ammonia water circulation transfer pump 17 can be a centrifugal pump or a positive displacement pump. An ammonia water concentration measuring instrument 26 is provided on its outlet pipeline. The ammonia water concentration measuring instrument 26 can monitor the ammonia water concentration in real time, and its downstream is respectively connected to the ammonia water transfer pipeline and the ammonia water circulation pipeline.

[0063] Specifically, a first remote control valve 22 is provided on the ammonia water circulation pipe. The first remote control valve 22 can be a hydraulic, pneumatic or electric valve, and its opening and closing are controlled by the ammonia water concentration monitor. The ammonia water circulation pipe is connected to enter the interior of the ammonia absorption tank 16.

[0064] Specifically, a second remote control valve 23 is provided on the ammonia water transfer pipe. The second remote control valve 23 can be a hydraulic, pneumatic or electric valve, and its opening and closing are controlled by the ammonia water concentration monitor; the ammonia water transfer pipe is connected to the ammonia water storage tank 25 through a hose 24; the ammonia water storage tank 25 can be a fixed type or a detachable type, and a liquid level gauge 27 is installed thereon to monitor the liquid level change in the ammonia water storage tank 25. When the liquid level exceeds the set value, the ammonia water circulation transfer pump 17 is controlled to stop. At the top of the ammonia water storage tank 25, a pressure balance pipe L9 is provided, and the other end of the pressure balance pipe L9 is open at the top of the ammonia absorption tank 16 to balance the pressures in the ammonia water storage tank 25 and the ammonia absorption tank 16 and reduce the back pressure of ammonia water transfer.

[0065] Specifically, when the ammonia water concentration measured by the ammonia water concentration monitor is less than the saturation concentration, the first remote control valve 22 is opened and the second remote control valve 23 is closed. At this time, the unsaturated ammonia water returns to the ammonia absorption tank 16 through the ammonia water circulation pipe and the spray head 21 to absorb ammonia gas again; when the ammonia water concentration reaches or exceeds the saturation concentration, the first remote control valve 22 is closed and the second remote control valve 23 is opened, and the saturated ammonia water is transported to the ammonia water storage tank 25.

[0066] Combined with the marine liquid ammonia fuel filling system of the above embodiments, the present embodiment also provides a method for controlling the cabin pressure for liquid ammonia filling, and the method includes:

[0067] Step 1: Use the filling pump 3 to fill liquid ammonia from the first cabin 1 to the second cabin 2. As the liquid ammonia is transferred from the first cabin 1 to the second cabin 2, the liquid levels of the two cabins change accordingly. The liquid level in the first cabin 1 drops, the gas phase space increases, the liquid level in the second cabin 2 rises, and the gas phase space decreases. This process applies the ideal gas state equation PV = MRT. Where: P is the gas phase space pressure in the cabin; V is the gas phase space volume in the cabin; M is the gas mass; R is the gas constant; T is the gas phase space temperature.

[0068] Before and after the liquid ammonia filling, the temperature change in the cabin is stable and is not the main factor affecting the establishment of the equation, so it can be regarded as an isothermal change; the gas constant R is only related to the type of gas and remains unchanged before and after filling. The variables are P, V, and M. Therefore, according to the ideal gas state equation, during the process of the volume change of the gas phase space in the cabin, to maintain the cabin pressure stable, it is necessary to adjust the gas mass to make the equation hold.

[0069] During the liquid ammonia filling process, the volume of the gas phase space in the first cabin 1 increases. To keep the pressure constant, it is necessary to increase the gas mass in the first cabin 1; the volume of the gas phase space in the second cabin 2 decreases. To keep the pressure constant, it is necessary to reduce the gas mass in the second cabin 2. That is, part of the ammonia gas in the second cabin 2 will transfer to the first cabin 1 under the action of the pressure difference to achieve pressure balance. This phenomenon is called the piston effect.

[0070] Step 2: The ammonia gas returned from the second cabin 2 passes through the first pressure control valve 6 and the pressure regulating valve 7 installed in parallel. When the first pressure sensor 8 monitors that the pressure is less than the set value, the first pressure control valve 6 opens. Since the resistance of the pressure regulating valve 7 is large, at this time, the returned ammonia gas preferentially returns to the first cabin 1 through the first pressure control valve 6 with smaller resistance. When the pressure monitored by the first pressure sensor 8 reaches or exceeds the set value, the first pressure control valve 6 is closed. At this time, the returned ammonia gas flows through the pressure regulating valve 7 and returns to the first cabin 1 after decompression.

[0071] Step 3: When the ammonia gas pressure in the first cabin 1 monitored by the second pressure sensor 11 does not reach the high-pressure set value, the second pressure control valve 9 opens, while the third pressure control valve 10 on the gas recovery pipe L5 remains closed. The decompressed returned ammonia gas returns to the first cabin 1; when the ammonia gas pressure monitored by the second pressure sensor 11 reaches or exceeds the set value, the second pressure control valve 9 is closed and the third pressure control valve 10 is opened. At this time, the amount of the returned ammonia gas exceeds the amount required for the cabin to maintain pressure, and the excessive returned ammonia gas enters the ammonia gas recovery system III.

[0072] Step 4: There are two methods for the ammonia gas recovery system III to recover the excessive returned ammonia gas:

[0073] Method 1: Use a compressor to increase the pressure of the ammonia gas, and after normal-temperature liquefaction by the liquefaction device 14, it returns to the first cabin 1;

[0074] Method 2: Utilize the characteristic that ammonia gas is easily soluble in water. In the ammonia gas absorption tank 16, the ammonia gas is fully contacted with the atomized absorption liquid to form ammonia water, and the ammonia water is transported to the ammonia water storage tank 25 for storage by the ammonia water circulation pump 17.

[0075] Step 5: During the filling process, when the pressure in the first chamber 1 monitored by the second pressure sensor 11 installed on the top of the first chamber 1 reaches or is lower than the low-pressure set value, the fourth pressure control valve 28 is opened, and the liquid ammonia filled into the second chamber 2 is shunted through the vaporization branch pipe L8. The shunted liquid ammonia is vaporized by the vaporizer 29, and the vaporized ammonia gas is returned to the first chamber 1 through the return gas pipe L4 to increase the pressure in the gas phase space of the first chamber 1; when the pressure monitored by the second pressure sensor 11 reaches the reset set value, the fourth pressure control valve 28 is closed, and the liquid ammonia vaporization process ends.

[0076] Specifically, in Steps 2, 3, and 5, the pressure set value can be set according to the actual operation conditions.

[0077] Specifically, in Step 4, either of the two ammonia recovery methods can be used, and the stored ammonia water can be transferred to the shore by pipeline transportation or by overall lifting of the ammonia water storage tank 25 at a specific terminal.

[0078] Specifically, in Step 4, the pressure of the ammonia gas after being compressed by the compressor can be adjusted according to the temperature of the refrigerant (such as seawater) of the liquefaction device 14, so that the pressure of the compressed ammonia gas meets the liquefaction requirement at the current temperature. The set value of the saturated ammonia water concentration can be adjusted according to the temperature of the ammonia gas absorption liquid.

[0079] In another specific embodiment, a liquid ammonia carrier with a filling function equipped with an IMO type B first chamber 1 performs a filling operation for a container chamber equipped with an IMO type C second chamber 2. Among them, the design pressure of the first chamber 1 is 0.7 bar; the design pressure of the second chamber 2 is 4.5 bar. The specific operation of ammonia gas reflux during the filling operation is as follows:

[0080] The first pressure sensor 8 is used to monitor the pressure of the returned gas, and its high-pressure set value is 0.65 bar; the low-pressure set value is 0.45 bar. When the return gas pressure monitored by the first pressure sensor 8 is less than 0.65 bar, the returned gas returns to the first chamber 1 through the first pressure control valve 6. When the return gas pressure monitored by the first pressure sensor 8 reaches or exceeds 0.65 bar, at this time, the returned gas directly returns to the first chamber 1, and there is a risk that the pressure in the first chamber 1 exceeds the design pressure. Therefore, the first pressure sensor 8 controls the closing of the first pressure control valve 6, and the returned gas passes through the pressure regulating valve 7 and returns to the first chamber 1 after decompression. The set value of the pressure regulating valve 7 is 0.6 bar, that is, when the returned gas passes through the pressure regulating valve 7, its pressure will be controlled at 0.6 bar. When the return gas pressure monitored by the first pressure sensor 8 drops to 0.45 bar, the first pressure control valve 6 is opened again, and the returned gas returns to the first chamber 1 through the first pressure control valve 6 with a smaller pressure drop.

[0081] The second pressure sensor 11 is used to monitor the pressure in the first chamber 1. Its high-pressure set value is 0.6 bar, and the low-pressure reset pressure is set at 0.35 bar. When the pressure in the first chamber 1 monitored by the second pressure sensor 11 reaches 0.6 bar, it means that the amount of the recycled gas is about to exceed the demand for maintaining the pressure in the first chamber 1. At this time, the second pressure control valve 9 is controlled to close, cutting off the path for the recycled gas to return to the first chamber 1. Meanwhile, the third pressure control valve 10 is opened, and the excessive recycled gas enters the ammonia recovery process through the third pressure control valve 10. When the pressure in the first chamber 1 monitored by the second pressure sensor 11 drops to 0.35 bar, the third pressure control valve 10 is controlled to close, and the second pressure control valve 9 is opened, and the recycled gas returns to the first chamber 1 again to maintain the pressure in the first chamber 1.

[0082] The second pressure sensor 11 is also used to control the liquid ammonia gasification system IV. Its low-pressure set value is 0.1 bar; the high-pressure reset pressure is set at 0.3 bar. When the pressure in the first chamber 1 monitored by the second pressure sensor 11 drops to 0.1 bar, it indicates that the amount of the recycled gas is insufficient to maintain the pressure in the first chamber 1. At this time, the fourth pressure control valve 28 is controlled to open, guiding a part of the liquid ammonia for filling into the liquid ammonia gasification system IV. After being gasified by the gasifier 29, it returns to the first chamber 1. When the pressure in the first chamber 1 rises to the high-pressure reset pressure of 0.3 bar, the fourth pressure control valve 28 closes, and the liquid ammonia gasification process ends.

[0083] In another embodiment, when excessive ammonia enters the liquefaction reflux process, the outlet pressure of the ammonia compressor 13 can be adjusted according to the refrigerant temperature of the liquefaction device 14, so that the compressed ammonia can be completely liquefied at the current refrigerant temperature.

[0084] In another embodiment, when excessive ammonia enters the ammonia absorption process, according to the type of the absorption liquid and the temperature of the ammonia water, the saturated concentration of the ammonia water is determined, and accordingly, the set value of the ammonia water concentration measuring instrument 26 is adjusted (which can be set at 33% at normal temperature) to control the first remote control valve 22 and the second remote control valve 23, and further control the circulation reflux or external transportation of the ammonia water.

[0085] Among the technical solutions described in the embodiments of the present application, they can be arbitrarily combined without conflict.

[0086] As mentioned above, it is only the specific implementation manners of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claimed rights.

Claims

1. A marine liquid ammonia fuel filling system, characterized in that, Including: A liquid filling system, an ammonia gas reflux system, an ammonia gas recovery system and a liquid ammonia gasification system The liquid filling system includes a first chamber and a second chamber, and the first chamber fills the second chamber with liquid ammonia; The ammonia gas reflux system transfers the gaseous ammonia in the second chamber to the first chamber to control the pressures of the two chambers; The ammonia gas recovery system liquefies and returns to the chamber or absorbs and stores the excessive ammonia gas from the second chamber; The liquid ammonia gasification system controls the pressure of the first chamber by gasifying a part of the liquid ammonia filled from the first chamber into the second chamber and then returning it to the first chamber.

2. The marine ammonia fuel filling system according to claim 1, wherein A filling pump is provided in the first chamber; The outlet of the filling pump is connected to a filling pipe, the other end of the filling pipe is connected to a liquid filling hose, and the liquid filling hose is connected to a receiving pipe; The other end of the receiving pipe opens in the second chamber, and its opening position includes the bottom or / and the top.

3. The marine ammonia fuel filling system according to claim 2, characterized in that, One end of the gas collecting pipe opens at the top of the second chamber, the other end is connected to a return air hose, the return air hose is connected to a return air pipe, the other end of the return air pipe opens at the top of the first chamber, and a gas recovery pipe and a gasification branch pipe are connected thereto.

4. The marine ammonia fuel filling system according to claim 3, wherein The liquid filling hose and the return air hose include: a composite material cryogenic hose, a vacuum insulation hose or a marine filling arm.

5. The marine ammonia fuel filling system according to claim 3, wherein The gasification branch pipe is arranged on the filling pipe; One end of the gasification branch pipe is connected to the filling pipe, the other end is connected to the return air pipe, and a fourth pressure control valve is provided thereon. The fourth pressure control valve is controlled to open and close by a second pressure sensor; The second pressure sensor is installed on the top of the first chamber for monitoring the pressure in the gas phase space of the first chamber; The outlet of the fourth pressure control valve is connected to a gasifier for gasifying liquid ammonia, and the gasified ammonia gas is returned to the first chamber through the return air pipe.

6. The marine ammonia fuel filling system according to claim 5, characterized in that, The gasifier includes a plate type, a shell and tube type or a printed circuit board type heat exchanger, and the heat exchange medium includes seawater, fresh water or ethylene glycol water.

7. The marine ammonia fuel filling system according to claim 3, characterized in that, A first pressure control valve and a pressure regulating valve are installed in parallel on the return air pipe, and the first pressure control valve is controlled to open and close by a first pressure sensor; The pressure regulating valve can control the return air pressure within a set range; The first pressure sensor is installed downstream of the first pressure control valve and the pressure regulating valve connected in parallel; A second pressure control valve is also installed on the return air pipe. The second pressure control valve is installed downstream of the first pressure sensor and is controlled to open and close by the second pressure sensor.

8. The marine ammonia fuel filling system according to claim 7, characterized in that, The gas recovery pipe is connected to the return air pipe on the pipeline between the first pressure sensor and the second pressure control valve.

9. The marine ammonia fuel filling system according to claim 8, characterized in that, A third pressure control valve is provided on the gas recovery pipe; The third pressure control valve is controlled to open and close by the second pressure sensor; The downstream of the third pressure control valve is respectively connected to a liquefaction return pipe and an ammonia gas absorption pipe, and one of them can be selected by operating the first isolation valve and the second isolation valve.

10. A method for controlling the cabin pressure for liquid ammonia filling, which is used to control the marine liquid ammonia filling system according to any one of claims 1 to 9 above, characterized in that, The method includes: Step 1: Use a filling pump to fill liquid ammonia from the first chamber to the second chamber. As the liquid ammonia transfers from the first chamber to the second chamber, the liquid levels in the two chambers change accordingly. The liquid level in the first chamber drops, and the gas phase space increases; the liquid level in the second chamber rises, and the gas phase space decreases. Step 2: The ammonia gas recycled from the second chamber passes through the first pressure control valve and the pressure regulating valve installed in parallel. When the first pressure sensor detects that the pressure is less than the set value, the first pressure control valve opens. Since the resistance of the pressure regulating valve is relatively large, at this time, the recycled ammonia gas preferentially returns to the first chamber through the first pressure control valve with less resistance. When the pressure detected by the first pressure sensor reaches or exceeds the set value, the first pressure control valve is closed. At this time, the recycled ammonia gas flows through the pressure regulating valve and returns to the first chamber after decompression. Step 3: When the ammonia gas pressure in the first chamber detected by the second pressure sensor does not reach the high-pressure set value, the second pressure control valve opens, while the third pressure control valve on the gas recovery pipe remains closed. The recycled ammonia gas after decompression returns to the first chamber. When the ammonia gas pressure detected by the second pressure sensor reaches or exceeds the set value, the second pressure control valve is closed, and the third pressure control valve is opened. At this time, the amount of recycled ammonia gas exceeds the amount required to maintain the pressure in the chamber, and the excessive recycled ammonia gas enters the ammonia gas recovery system. Step 4: The ammonia gas recovery system recovers the excessive recycled ammonia gas. Step 5: During the filling process, when the pressure in the first chamber detected by the second pressure sensor installed at the top of the first chamber reaches or is lower than the low-pressure set value, the fourth pressure control valve opens. The liquid ammonia filled into the second chamber is shunted through the gasification branch pipe. The shunted liquid ammonia is gasified by the gasifier, and the gasified ammonia gas returns to the first chamber through the gas return pipe to increase the pressure in the gas phase space of the first chamber. When the pressure detected by the second pressure sensor reaches the reset set value, the fourth pressure control valve is closed, and the liquid ammonia gasification process ends.

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