Ship LNG (Liquefied Natural Gas) fuel supply and tail gas carbon dioxide capture system

Abstract

The invention provides a ship LNG fuel supply and tail gas carbon dioxide capture system. The ship LNG fuel supply and tail gas carbon dioxide capture system comprises an LNG storage tank, a CO2 separation device, a CO2 compressor, an ejector, an LNG vaporization heater, a mixed gas heat exchanger, a flash tank, a liquid CO2 storage tank, a flue gas heat exchanger and an engine. According to the system, LNG cold energy and engine tail gas heat energy can be effectively utilized, and the energy consumption of the system is reduced.

Description

Technical Field

[0001] The present invention relates to the field of ship technology, and in particular to a ship LNG fuel supply and tail gas carbon dioxide capture system. Background Art

[0002] As global warming continues, climate change has become a significant challenge facing human development. Greenhouse gas emissions are the primary driver of long-term climate change. Of the various greenhouse gases contributing to climate change, CO2 (carbon dioxide) has the greatest impact on warming. For the shipping industry, reducing carbon emissions is imperative.

[0003] Currently, zero-carbon fuels such as ammonia and hydrogen face challenges such as immature application technology and high costs, while clean fuels such as LNG (liquefied natural gas), methanol, and LPG (liquefied petroleum gas) cannot achieve net-zero CO2 emissions. Using carbon capture technology to capture CO2 from the exhaust of ships burning carbon-containing fuels is an important way to achieve net-zero CO2 emissions.

[0004] The currently common flue gas CO2 capture process uses chemical absorption to absorb CO2 from exhaust gases. It is then compressed by a compressor and condensed by a liquefaction unit, converting the CO2 into a liquid form for storage in a tank. This process is highly applicable and widely used in the field of exhaust gas carbon capture, but it suffers from high energy consumption. In LNG-powered ships, LNG fuel must be heated and vaporized during use, a process that releases a large amount of high-quality cold energy. Currently, LNG vaporization is typically heated with jacket water or boiler hot water, which wastes LNG cold energy. Summary of the Invention

[0005] The purpose of the present invention is to provide a ship LNG fuel supply and exhaust gas carbon dioxide capture system, which can effectively utilize the cold energy of LNG and the heat energy of engine exhaust gas and reduce the energy consumption of the system.

[0006] The present invention provides a ship LNG fuel supply and tail gas carbon dioxide capture system, including an LNG storage tank, a CO2 separation device, a CO2 compressor, an ejector, an LNG vaporization heater, a mixed gas heat exchanger, a flash tank, a liquid CO2 storage tank, a flue gas heat exchanger and an engine;

[0007] The LNG storage tank is connected to the LNG inlet of the mixed gas heat exchanger through a liquid infusion pipeline, the LNG outlet of the mixed gas heat exchanger is connected to the inlet of the LNG vaporization heater, and the outlet of the LNG vaporization heater is connected to the low-pressure inlet of the ejector;

[0008] The exhaust gas outlet of the engine is connected to the exhaust gas inlet of the flue gas heat exchanger, the exhaust gas outlet of the flue gas heat exchanger is connected to the inlet of the CO2 separation device, the CO2 outlet of the CO2 separation device is connected to the inlet of the CO2 compressor, the outlet of the CO2 compressor is connected to the high-pressure inlet of the ejector, the mixed fluid outlet of the ejector is connected to the mixed fluid inlet of the mixed gas heat exchanger, the mixed fluid outlet of the mixed gas heat exchanger is connected to the inlet of the flash tank, the liquid CO2 outlet of the flash tank is connected to the liquid CO2 storage tank, the natural gas outlet of the flash tank is connected to the natural gas inlet of the flue gas heat exchanger, and the natural gas outlet of the flue gas heat exchanger is connected to the fuel inlet of the engine.

[0009] In one achievable manner, the CO2 separation device includes a lean liquid cooler, an absorption tower, a rich liquid pump, a lean and rich liquid heat exchanger, a first lean liquid pump, a desorption tower, a second lean liquid pump and a lean liquid heater;

[0010] The tail gas outlet of the flue gas heat exchanger is connected to the bottom inlet of the absorption tower, and the top of the absorption tower is provided with a tail gas outlet; the bottom outlet of the absorption tower is connected to the inlet of the rich liquid pump, the outlet of the rich liquid pump is connected to the rich liquid inlet of the lean-rich liquid heat exchanger, the rich liquid outlet of the lean-rich liquid heat exchanger is connected to the top inlet of the desorption tower, and the top outlet of the desorption tower is connected to the inlet of the CO2 compressor;

[0011] The bottom outlet of the desorption tower is divided into two routes. One bottom outlet of the desorption tower is connected to the inlet of the first lean liquid pump, the outlet of the first lean liquid pump is connected to the lean liquid inlet of the lean-rich liquid heat exchanger, the lean liquid outlet of the lean-rich liquid heat exchanger is connected to the inlet of the lean liquid cooler, and the outlet of the lean liquid cooler is connected to the top inlet of the absorption tower; the other bottom outlet of the desorption tower is connected to the inlet of the second lean liquid pump, the outlet of the second lean liquid pump is connected to the lean liquid inlet of the lean liquid heater, and the lean liquid outlet of the lean liquid heater is connected to the desorption tower.

[0012] In one achievable manner, a first filler is provided in the absorption tower, and the first filler is located between the bottom inlet and the top inlet of the absorption tower;

[0013] A second filler is provided in the analytical tower, and the second filler is located between the bottom outlet and the top inlet of the analytical tower; a lean liquid inlet is provided on the analytical tower at a position corresponding to the second filler, and the lean liquid outlet of the lean liquid heater is connected to the lean liquid inlet of the analytical tower.

[0014] In one feasible manner, a flue gas fan is provided on the pipeline between the exhaust gas outlet of the flue gas heat exchanger and the bottom inlet of the absorption tower.

[0015] In one feasible embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a CO2 cooler, a gas-liquid separation tank and a CO2 drying device; the top outlet of the decomposition tower is connected to the inlet of the CO2 cooler, the outlet of the CO2 cooler is connected to the inlet of the gas-liquid separation tank, the CO2 outlet of the gas-liquid separation tank is connected to the inlet of the CO2 drying device, and the outlet of the CO2 drying device is connected to the inlet of the CO2 compressor.

[0016] In one feasible manner, a first regulating valve is provided on the infusion pipeline, a first temperature sensor is provided on the flash tank, and the first temperature sensor is signal-connected to the first regulating valve.

[0017] In one feasible embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system further includes a natural gas heater; the natural gas outlet of the flash tank is divided into two routes, one natural gas outlet of the flash tank is connected to the natural gas inlet of the flue gas heat exchanger, and the other natural gas outlet of the flash tank is connected to the inlet of the natural gas heater, and the outlet of the natural gas heater is connected to the fuel inlet of the engine.

[0018] In one feasible embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system further includes a second natural gas buffer tank; the natural gas outlet of the flue gas heat exchanger is connected to the inlet of the second natural gas buffer tank, and the outlet of the second natural gas buffer tank is connected to the fuel inlet of the engine; a second temperature sensor is provided on the second natural gas buffer tank, a third regulating valve is provided on the pipeline between the exhaust gas outlet of the engine and the exhaust gas inlet of the flue gas heat exchanger, and the second temperature sensor is signal-connected to the third regulating valve.

[0019] In one feasible embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system further includes a BOG heater, a methane cracking unit, a hydrogen purification unit, a hydrogen fuel cell, and a ship DC power grid; the BOG outlet of the LNG storage tank is connected to the inlet of the BOG heater, the outlet of the BOG heater is connected to the inlet of the methane cracking unit, the outlet of the methane cracking unit is connected to the inlet of the hydrogen purification unit, the outlet of the hydrogen purification unit is connected to the inlet of the hydrogen fuel cell, and the hydrogen fuel cell is electrically connected to the ship DC power grid.

[0020] In one achievable manner, the ship LNG fuel supply and tail gas carbon dioxide capture system further comprises a CO2 gas cylinder, and the CO2 gas cylinder is connected to the inlet of the CO2 compressor;

[0021] Alternatively, the ship LNG fuel supply and exhaust carbon dioxide capture system further comprises a CO2 delivery pump and a CO2 heater, an inlet of the CO2 delivery pump is connected with the liquid CO2 storage tank, an outlet of the CO2 delivery pump is connected with an inlet of the CO2 heater, and an outlet of the CO2 heater is connected with an inlet of the CO2 compressor.

[0022] The ship LNG fuel supply and exhaust carbon dioxide capture system provided by the application can realize effective utilization of LNG cold energy and engine exhaust heat energy on the basis of stable supply of LNG to the engine, reduce energy consumption of the system, save low-temperature submerged pumps, natural gas boosters, CO2 liquefaction devices, flue gas pretreatment towers and other equipment, and is favorable for reducing equipment cost and operation cost.

[0023] 1. Natural gas is boosted by using an ejector to reduce system investment and operation cost: by arranging a CO2 compressor and an ejector, high-pressure CO2 is formed by pressurizing CO2 by using the CO2 compressor, and LNG in the LNG storage tank is automatically ejected out by using the high-pressure CO2 through the ejector, which on the one hand replaces the function of the high-investment low-temperature submerged pump, reduces system equipment cost and maintenance difficulty, and on the other hand realizes energy exchange between natural gas and high-pressure CO2 in the ejector, completes natural gas boosting, and can save natural gas boosting equipment.

[0024] 2. CO2 is liquefied by using low-temperature LNG to realize cold energy recovery: according to the different condensation temperature characteristics of natural gas and CO2, CO2 is liquefied by using low-temperature LNG, and separation of natural gas and liquid CO2 is realized through a flash tank, so that CO2 liquefaction and LNG cold energy utilization are realized at the same time, the overall energy consumption of the system is reduced, and a CO2 liquefaction device is saved.

[0025] 3. Waste heat utilization is realized to improve total energy efficiency of the system: by arranging a flue gas heat exchanger, natural gas is heated by using engine exhaust, which on the one hand realizes recycling of ship waste heat, and on the other hand realizes flue gas cooling by heat exchange with low-temperature natural gas, replaces the function of a traditional flue gas pretreatment tower, and reduces system investment cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is a structural schematic diagram of a ship LNG fuel supply and exhaust carbon dioxide capture system in an embodiment of the application.

[0027] Figure 2 FIG. 2 is a structural schematic diagram of a ship LNG fuel supply and exhaust carbon dioxide capture system in another embodiment of the application. DETAILED DESCRIPTION

[0028] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0029] The terms "first," "second," "third," "fourth," and the like (if any) in the description and claims of the present invention are used to distinguish similar objects and are not necessarily used to describe a particular sequential order or sequence.

[0030] The directional terms "up," "down," "left," "right," "front," "back," "top," and "bottom" (if any) used in the specification and claims of the present invention are defined by the positions of the structures in the drawings and the positions of the structures relative to each other, and are intended only for clarity and convenience in expressing the technical solution. It should be understood that the use of directional terms should not limit the scope of protection claimed in the present invention.

[0031] like Figure 1 As shown, an embodiment of the present invention provides a ship LNG (Liquefied Natural Gas) fuel supply and tail gas carbon dioxide capture system, including an LNG storage tank 2, a CO2 separation device 100, a CO2 compressor 27, an ejector 30, an LNG vaporization heater 31, a mixed gas heat exchanger 32, a flash tank 44, a liquid CO2 storage tank 25, a flue gas heat exchanger 34, and an engine 41. The engine 41 can be a ship main engine, a ship auxiliary engine, etc., and the engine 41 can use LNG as fuel.

[0032] The LNG storage tank 2 is connected to the LNG inlet of the mixed gas heat exchanger 32 through the infusion pipeline 101, and one end of the infusion pipeline 101 extends to the bottom of the LNG storage tank 2 so as to absorb the LNG in the LNG storage tank 2; the LNG outlet of the mixed gas heat exchanger 32 is connected to the inlet of the LNG vaporization heater 31, and the outlet of the LNG vaporization heater 31 is connected to the low-pressure inlet of the ejector 30.

[0033] The exhaust gas outlet of the engine 41 is connected to the exhaust gas inlet of the flue gas heat exchanger 34, the exhaust gas outlet of the flue gas heat exchanger 34 is connected to the inlet of the CO2 separation device 100, the CO2 outlet of the CO2 separation device 100 is connected to the inlet of the CO2 compressor 27, the outlet of the CO2 compressor 27 is connected to the high-pressure inlet of the ejector 30, the mixed fluid outlet of the ejector 30 is connected to the mixed fluid inlet of the mixed gas heat exchanger 32, the mixed fluid outlet of the mixed gas heat exchanger 32 is connected to the inlet of the flash tank 44, the liquid CO2 outlet of the flash tank 44 (i.e., the bottom outlet of the flash tank 44) is connected to the liquid CO2 storage tank 25, the natural gas outlet of the flash tank 44 (i.e., the top outlet of the flash tank 44) is connected to the natural gas inlet of the flue gas heat exchanger 34, and the natural gas outlet of the flue gas heat exchanger 34 is connected to the fuel inlet of the engine 41.

[0034] Specifically, the LNG storage tank 2 is used for storing LNG; the CO2 separation device 100 is used for separating CO2 in the engine exhaust gas (i.e. decarbonizing the engine exhaust gas) and discharging the decarbonized exhaust gas; the CO2 compressor 27 is used for pressurizing the CO2, so as to pressurize the low-pressure CO2 into high-pressure CO2; the ejector 30 is used for ejecting the LNG in the LNG storage tank 2 by the high-pressure CO2, so as to save the traditional cryogenic submerged pump, and the natural gas is pressurized by the high-pressure CO2 in the ejector 30, so as to save the natural gas pressurizing equipment; the LNG vaporization heater 31 is used for heating the LNG, so as to vaporize the LNG into natural gas; the mixed gas heat exchanger 32 is used for exchanging heat between the mixed gas of the natural gas and the CO2 and the LNG, so as to liquefy the CO2, and facilitate the separation of the natural gas and the CO2; the flash tank 44 is used for separating the natural gas and the liquid CO2, and further liquefying the CO2 by the flash effect, so as to improve the separation effect of the natural gas and the liquid CO2 (i.e. improve the complete degree of the separation); the liquid CO2 storage tank 25 is used for storing the liquid CO2; and the flue gas heat exchanger 34 is used for exchanging heat between the engine exhaust gas and the natural gas, so as to cool the engine exhaust gas and heat the natural gas.

[0035] During normal operation of the system, the high-temperature exhaust gas generated by the engine 41 passes through the flue gas heat exchanger 34 for heat exchange and cooling, and then enters the CO2 separation device 100. The CO2 separation device 100 separates the CO2 from the engine exhaust gas and discharges the decarbonized exhaust gas. The separated CO2 enters the CO2 compressor 27, which pressurizes the CO2, converting the low-pressure CO2 into high-pressure CO2. The high-pressure CO2 enters the ejector 30. When the high-pressure CO2 flows through the receiving chamber of the ejector 30, suction is generated, creating a sufficient pressure differential between the interior of the LNG storage tank 2 and the interior of the ejector 30. Through the ejection action of the ejector 30, the LNG in the LNG storage tank 2 is automatically extracted (the structure and working principle of the ejector 30 can be referred to the existing technology and will not be repeated here). LNG drawn from LNG storage tank 2 is heated by mixed gas heat exchanger 32 before entering LNG vaporizer 31, which heats the LNG and vaporizes it into natural gas. The natural gas is then ejected into ejector 30, where it mixes with high-temperature, high-pressure CO2 and exchanges energy, raising both its temperature and pressure, ultimately bringing its pressure to the required supply pressure for engine 41. The natural gas and CO2 mixture then exchanges heat with the low-temperature LNG in mixed gas heat exchanger 32, cooling the mixture. Because the condensation temperature of natural gas is much lower than that of CO2 at the same pressure, after cooling, the natural gas remains in a gaseous state, while the CO2 condenses into a liquid. The gas-liquid mixture of natural gas / liquid CO2 cooled by the mixed gas heat exchanger 32 enters the flash tank 44, and the separation of natural gas and liquid CO2 is achieved through the gas-liquid separation effect of the flash tank 44. At the same time, the flash evaporation effect of the flash tank 44 further liquefies a small amount of unliquefied CO2 in the gas-liquid mixture into liquid CO2 (after cooling by the mixed gas heat exchanger 32, a small amount of CO2 may not be completely liquefied; when the high-pressure natural gas / liquid CO2 gas-liquid mixture enters the low-pressure flash tank 44, the sudden drop in pressure will cause the unliquefied CO2 to be further liquefied into liquid CO2. For the structure and working principle of the flash tank 44, please refer to the existing technology and will not be repeated here), thereby improving the separation effect of natural gas and CO2. The separated liquid CO2 flows into the liquid CO2 storage tank 25 through the bottom outlet of the flash tank 44 for storage, and the separated natural gas is discharged from the top outlet of the flash tank 44 in gaseous form. After the natural gas enters the flue gas heat exchanger 34, the low-temperature natural gas and the high-temperature engine exhaust gas are heat exchanged in the flue gas heat exchanger 34 to achieve cooling of the engine exhaust gas and heating of the natural gas, so that the temperature of the natural gas reaches the gas supply temperature required by the engine 41, and then the natural gas is transported to the engine 41 for combustion by the engine 41.

[0036] like Figure 1As shown, as one embodiment, both the mixed gas heat exchanger 32 and the flue gas heat exchanger 34 are shell-and-tube heat exchangers. The LNG storage tank 2 is connected to the tube-side inlet of the mixed gas heat exchanger 32 via a liquid infusion line 101. The tube-side outlet of the mixed gas heat exchanger 32 is connected to the inlet of the LNG vaporizer heater 31. The mixed fluid outlet of the ejector 30 is connected to the shell-side inlet of the mixed gas heat exchanger 32, which is connected to the inlet of the flash tank 44. The exhaust outlet of the engine 41 is connected to the shell-side inlet of the flue gas heat exchanger 34, which is connected to the inlet of the CO2 separation device 100. The natural gas outlet of the flash tank 44 is connected to the tube-side inlet of the flue gas heat exchanger 34, which is connected to the fuel inlet of the engine 41. Of course, in other embodiments, the mixed gas heat exchanger 32 and the flue gas heat exchanger 34 may also be other types of heat exchangers.

[0037] like Figure 1 As shown, as an embodiment, the CO2 separation device 100 is an absorption-desorption type CO2 separation device. The CO2 separation device 100 includes a lean liquid cooler 14, an absorption tower 15, a rich liquid pump 16, a lean and rich liquid heat exchanger 17, a first lean liquid pump 18, a desorption tower 19, a second lean liquid pump 20, and a lean liquid heater 21.

[0038] The exhaust gas outlet of the flue gas heat exchanger 34 is connected to the bottom inlet of the absorption tower 15. Specifically, a flue gas fan 47 is installed in the pipeline between the exhaust gas outlet of the flue gas heat exchanger 34 and the bottom inlet of the absorption tower 15. The exhaust gas outlet of the flue gas heat exchanger 34 is connected to the inlet of the flue gas fan 47, and the outlet of the flue gas fan 47 is connected to the bottom inlet of the absorption tower 15. An exhaust gas outlet 150 is provided at the top of the absorption tower 15, through which the decarbonized exhaust gas is discharged. The bottom outlet of the absorption tower 15 is connected to the inlet of the rich liquid pump 16, the outlet of the rich liquid pump 16 is connected to the rich liquid inlet of the lean-rich liquid heat exchanger 17, the rich liquid outlet of the lean-rich liquid heat exchanger 17 is connected to the top inlet of the desorption tower 19, and the top outlet of the desorption tower 19 is connected to the inlet of the CO2 compressor 27. A first packing 151 is installed in the absorption tower 15, located between the bottom and top inlets of the absorption tower 15.

[0039] The bottom outlet of the desorption tower 19 is divided into two routes. One of the bottom outlets of the desorption tower 19 is connected to the inlet of the first lean liquid pump 18, which is connected to the lean liquid inlet of the lean-rich liquid heat exchanger 17. The lean liquid outlet of the lean-rich liquid heat exchanger 17 is connected to the inlet of the lean liquid cooler 14, and the outlet of the lean liquid cooler 14 is connected to the top inlet of the absorption tower 15. The other bottom outlet of the desorption tower 19 is connected to the inlet of the second lean liquid pump 20, which is connected to the lean liquid inlet of the lean liquid heater 21, and the lean liquid outlet of the lean liquid heater 21 is connected to the desorption tower 19. A second packing 191 is provided in the desorption tower 19, located between the bottom outlet and the top inlet of the desorption tower 19. A lean liquid inlet 192 is provided on the desorption tower 19 at a position corresponding to the second packing 191. The lean liquid outlet of the lean liquid heater 21 is connected to the lean liquid inlet 192 of the desorption tower 19, allowing the alkanolamine solution to enter the second packing 191 through the lean liquid inlet 192. In this embodiment, the lean liquid heater 21 is a heat exchanger, and the lean liquid heater 21 heats the alcoholamine solution through steam from a ship boiler.

[0040] A first spray device 152 is provided at the top of the absorption tower 15, and the outlet of the lean liquid cooler 14 is connected to the first spray device 152 in the absorption tower 15 (specifically, the first spray device 152 includes a spray pipe and a plurality of nozzles provided on the spray pipe, and the outlet of the lean liquid cooler 14 is connected to the spray pipe in the first spray device 152). A second spray device 193 is provided at the top of the desorption tower 19, and the rich liquid outlet of the lean-rich liquid heat exchanger 17 is connected to the second spray device 193 in the desorption tower 19 (specifically, the second spray device 193 includes a spray pipe and a plurality of nozzles provided on the spray pipe, and the rich liquid outlet of the lean-rich liquid heat exchanger 17 is connected to the spray pipe in the second spray device 193).

[0041] At the same time, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a CO2 cooler 22, a gas-liquid separation tank 23 and a CO2 drying device 24; the top outlet of the analysis tower 19 is connected to the inlet of the CO2 cooler 22, the outlet of the CO2 cooler 22 is connected to the inlet of the gas-liquid separation tank 23, the CO2 outlet of the gas-liquid separation tank 23 (that is, the top outlet of the gas-liquid separation tank 23) is connected to the inlet of the CO2 drying device 24, and the outlet of the CO2 drying device 24 is connected to the inlet of the CO2 compressor 27.

[0042] Specifically, the CO2 separation device 100 uses an alcohol amine solution as an absorbent for circulation to achieve absorption and desorption of CO2, and then achieve decarbonization of the tail gas and separation of CO2.

[0043] During operation, the engine exhaust gas passes through the flue gas heat exchanger 34 for heat exchange and cooling (cooling of the engine exhaust gas is conducive to the subsequent absorption of the exhaust gas by the alcoholamine solution), and is pressurized by the flue gas fan 47 (on the one hand, the engine exhaust gas can be smoothly discharged into the absorption tower 15, and on the other hand, the contact efficiency between the alcoholamine solution and the engine exhaust gas can be improved, thereby improving the absorption of the exhaust gas by the alcoholamine solution). The pressurized exhaust gas enters the absorption tower 15; the alcoholamine solution is sprayed from the first spray device 152 at the top of the absorption tower 15 from top to bottom. The tail gas flows from bottom to top in the absorption tower 15, and the alcoholamine solution and the tail gas are fully contacted and reacted in a countercurrent manner in the first filler 151, so that the alcoholamine solution absorbs CO2 in the tail gas, and the clean gas (i.e., decarbonized tail gas) with CO2 removed is discharged from the tail gas outlet 150 at the top of the absorption tower 15, and the alcoholamine rich liquid that absorbs CO2 is discharged from the bottom outlet of the absorption tower 15, and after being pressurized by the rich liquid pump 16 and heated by heat exchange in the rich liquid heat exchanger 17, it is sprayed from top to bottom from the second spray device 193 at the top of the decomposition tower 19. The amine solution at the bottom of the desorption tower 19 is divided into two paths. One path of the amine solution is pressurized by the second lean liquid pump 20 and then enters the lean liquid heater 21 for heating (it should be noted that the temperature of the heated amine solution needs to be greater than the desorption temperature of CO2). The heated amine solution enters the second filler 191 in the desorption tower 19 to provide heat for the desorption of CO2. Specifically, the amine rich liquid sprayed by the second spraying device 193 contacts the heated amine solution in the second filler 191, so that the CO2 in the amine rich liquid escapes due to heat. The separated CO2 gas is discharged from the top outlet of the desorption tower 19 and finally transported to the CO2 compressor 27. The amine solution after removing CO2 flows downward to the bottom of the desorption tower 19; the other path of the amine solution is pressurized by the first lean liquid pump 18, cooled in turn by the lean and rich liquid heat exchanger 17 and the lean liquid cooler 14, and then sprayed again by the first spraying device 152 to realize the recycling of the amine solution.

[0044] Since the CO2 gas discharged from the top outlet of desorption tower 19 is rich in water vapor, it is cooled by CO2 cooler 22, condensing the water vapor in the CO2. The CO2 then enters gas-liquid separator 23, where it undergoes preliminary separation from the condensed water. The separated condensed water is discharged from the bottom outlet of gas-liquid separator 23, while the separated CO2 is discharged from the top outlet of gas-liquid separator 23 to CO2 drying unit 24. The CO2 further removes water in CO2 drying unit 24, lowering its dew point to below -40°C to prevent ice blockage when the CO2 subsequently comes into contact with low-temperature natural gas. The dried CO2 is then transported to CO2 compressor 27. A first CO2 buffer tank 26 is installed in the pipeline between the outlet of CO2 drying unit 24 and the inlet of CO2 compressor 27. A second CO2 buffer tank 28 is installed in the pipeline between the outlet of CO2 compressor 27 and the high-pressure inlet of ejector 30. Both the first CO2 buffer tank 26 and the second CO2 buffer tank 28 serve as buffers, pressure stabilizers, and temporary storage.

[0045] like Figure 1 As shown, as an embodiment, a first regulating valve 3 is provided on the liquid infusion pipeline 101. By adjusting the opening of the first regulating valve 3, the flow rate of LNG flowing from the LNG storage tank 2 to the mixed gas heat exchanger 32 can be adjusted. A first temperature sensor 33 is provided on the flash tank 44. The first temperature sensor 33 is used to detect the temperature of the fluid in the flash tank 44. The first temperature sensor 33 is signal-connected to the first regulating valve 3 (specifically, the first temperature sensor 33 is electrically signal-connected to the controller of the first regulating valve 3). The first regulating valve 3 is used to adjust the valve opening of the first regulating valve 3 based on the temperature value detected by the first temperature sensor 33.

[0046] Specifically, since the temperature of the LNG output from the LNG storage tank 2 is very low (the storage temperature of LNG is generally around -163°C), if the LNG flow rate flowing to the mixed gas heat exchanger 32 is too large, it may cause the mixed gas of natural gas and CO2 to solidify (i.e., change from liquid to solid) after entering the mixed gas heat exchanger 32, resulting in ice blockage; therefore, this embodiment sets a first temperature sensor 33 on the flash tank 44, and uses the temperature value detected by the first temperature sensor 33 to control the opening of the first regulating valve 3, and then controls the LNG flow rate entering the mixed gas heat exchanger 32, so as to avoid ice blockage caused by the temperature of the liquid CO2 being lower than the freezing point, thereby ensuring the safe operation of the system. Specifically, when the temperature value detected by the first temperature sensor 33 is lower than the freezing temperature (freezing point) of CO2, the opening of the first regulating valve 3 is reduced to reduce the LNG flow entering the mixed gas heat exchanger 32, thereby increasing the temperature of CO2; when the temperature value detected by the first temperature sensor 33 is higher than the vaporization temperature of CO2, the opening of the first regulating valve 3 is increased to increase the LNG flow entering the mixed gas heat exchanger 32, thereby lowering the temperature of CO2, so that the temperature of the liquid CO2 is maintained between the freezing temperature and the vaporization temperature, thereby keeping the CO2 stably in liquid form.

[0047] like Figure 1 As shown, as an embodiment, the ship LNG fuel supply and exhaust CO2 capture system also includes a natural gas heater 46. The natural gas outlet of the flash tank 44 is divided into two routes. One natural gas outlet of the flash tank 44 is connected to the natural gas inlet of the flue gas heat exchanger 34, and the other natural gas outlet of the flash tank 44 is connected to the inlet of the natural gas heater 46. The outlet of the natural gas heater 46 is connected to the fuel inlet of the engine 41. In other words, the natural gas heater 46 and the flue gas heat exchanger 34 are arranged in parallel. The natural gas heater 46 is used to heat the natural gas to the gas supply temperature required by the engine 41, and then the natural gas is transported to the engine 41 for combustion.

[0048] A first control valve 48 is provided on the pipeline between the natural gas outlet of the flash tank 44 and the inlet of the natural gas heater 46. A second control valve 49 is provided on the pipeline between the natural gas outlet of the flash tank 44 and the natural gas inlet of the flue gas heat exchanger 34. By switching the first and second control valves 48 and 49, natural gas can be directed to the natural gas heater 46 or the flue gas heat exchanger 34, thereby heating the natural gas. Specifically, during initial system operation or when the engine 41 has not yet stabilized, the engine 41 does not generate sufficient exhaust gas. Therefore, the exhaust gas heat cannot meet the heat requirement for natural gas heating. In this case, the first control valve 48 is opened and the second control valve 49 is closed, allowing the natural gas in the flash tank 44 to flow to the natural gas heater 46 for heating. When the system stabilizes, the engine 41 generates sufficient exhaust gas. At this point, the exhaust gas heat can meet the heat requirement for natural gas heating. Therefore, the first control valve 48 is closed and the second control valve 49 is opened, allowing the natural gas in the flash tank 44 to flow to the flue gas heat exchanger 34 for heating.

[0049] like Figure 1 As shown in the figure, as one embodiment, the ship LNG fuel supply and exhaust gas CO2 capture system also includes a first natural gas buffer tank 29 and a second natural gas buffer tank 38. The first natural gas buffer tank 29 is installed in the pipeline between the outlet of the LNG vaporizer heater 31 and the low-pressure inlet of the ejector 30. That is, the outlet of the LNG vaporizer heater 31 is connected to the inlet of the first natural gas buffer tank 29, and the outlet of the first natural gas buffer tank 29 is connected to the low-pressure inlet of the ejector 30. The second natural gas buffer tank 38 is installed in the pipeline between the natural gas outlet of the flue gas heat exchanger 34 and the outlet of the natural gas heater 46, and the fuel inlet of the engine 41. That is, the natural gas outlets of the flue gas heat exchanger 34 and the outlet of the natural gas heater 46 are both connected to the inlet of the second natural gas buffer tank 38, and the outlet of the second natural gas buffer tank 38 is connected to the fuel inlet of the engine 41. The first and second natural gas buffer tanks 29 and 38 both serve as buffers, pressure stabilizers, and temporary storage.

[0050] The second natural gas buffer tank 38 is equipped with a second temperature sensor 36 for detecting the temperature of the natural gas within the second natural gas buffer tank 38. A third regulating valve 39 is installed in the pipeline between the exhaust gas outlet of the engine 41 and the exhaust gas inlet of the flue gas heat exchanger 34. The second temperature sensor 36 is signal-connected to the third regulating valve 39 (specifically, the second temperature sensor 36 is electrically signal-connected to the controller of the third regulating valve 39). The third regulating valve 39 is configured to adjust its valve opening based on the temperature detected by the second temperature sensor 36, thereby regulating the exhaust gas flow entering the flue gas heat exchanger 34 so that the temperature of the heated natural gas meets the supply temperature requirement of the engine 41. Specifically, when the second temperature sensor 36 detects that the temperature of the natural gas in the second natural gas buffer tank 38 is lower than a preset range, the third regulating valve 39 increases its opening to increase the exhaust gas flow entering the flue gas heat exchanger 34, thereby increasing the heating temperature of the natural gas; when the second temperature sensor 36 detects that the temperature of the natural gas in the second natural gas buffer tank 38 is higher than the preset range, the third regulating valve 39 decreases its opening to reduce the exhaust gas flow entering the flue gas heat exchanger 34, thereby lowering the heating temperature of the natural gas.

[0051] like Figure 1 As shown, as an embodiment, a flue gas filter 40 is further provided on the pipeline between the exhaust gas outlet of the engine 41 and the exhaust gas inlet of the flue gas heat exchanger 34. The flue gas filter 40 is used to remove dust from the engine exhaust gas to remove dust and impurities in the engine exhaust gas.

[0052] like Figure 1 As shown, as one embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a BOG (Boiled Off Gas) heater 4, a methane cracker 6, a hydrogen purification unit 7, a hydrogen fuel cell 8, and a ship DC power grid 12. The BOG outlet of the LNG storage tank 2 is connected to the inlet of the BOG heater 4, which is connected to the inlet of the methane cracker 6, which is connected to the inlet of the hydrogen purification unit 7, which is connected to the inlet of the hydrogen purification unit 7, which is connected to the inlet of the hydrogen fuel cell 8, which is electrically connected to the ship DC power grid 12. Furthermore, a BOG buffer tank 5 is provided in the pipeline between the outlet of the BOG heater 4 and the inlet of the methane cracker 6 to provide buffering, pressure stabilization, and temporary storage.

[0053] The ship's LNG fuel supply and exhaust CO2 capture system also includes a battery 10, a first DC inverter 9, a second DC inverter 11, and an AC-DC converter 13. The hydrogen fuel cell 8 is electrically connected to the ship's DC grid 12 via the first DC inverter 9, the battery 10 is electrically connected to the ship's DC grid 12 via the second DC inverter 11, and the AC-DC converter 13 is electrically connected to the ship's DC grid 12. The methane cracking unit 6 and hydrogen purification unit 7 are also electrically connected to the ship's DC grid 12.

[0054] Specifically, during the vessel's voyage, as the LNG in LNG tank 2 continuously evaporates into BOG, the pressure in LNG tank 2 gradually increases. To prevent overpressure in LNG tank 2, when the pressure in LNG tank 2 reaches a certain limit, the BOG gas is discharged from the top pipeline of LNG tank 2, heated by BOG heater 4, and then enters BOG buffer tank 5. Since the BOG gas in LNG tank 2 is primarily composed of methane, after being transported to methane cracking unit 6, the BOG gas is catalytically cracked by the methane cracking unit 6 to form a mixed gas of hydrogen and nitrogen. The mixed gas is then purified by hydrogen purification unit 7 to remove nitrogen, resulting in pure hydrogen. The hydrogen is then transported to hydrogen fuel cell 8, which converts the chemical energy of the hydrogen into electrical energy. This energy is then converted by first DC inverter 9 and supplied to the ship's DC power grid 12. A portion of the electrical energy is converted to AC power by an AC-DC converter 13 to power the ship's electrical equipment and the methane cracking unit 6 and hydrogen purification unit 7. The excess electrical energy is converted by a first DC inverter 11 and then transferred to a battery 10 for energy storage. In this embodiment, the battery 10 is a lithium battery.

[0055] like Figure 1As shown in FIG. 1 , as an embodiment, the ship LNG fuel supply and exhaust gas CO2 capture system further includes a discharge pipeline 103. One end of the discharge pipeline 103 is connected to the second natural gas buffer tank 38, and the other end of the discharge pipeline 103 is connected to the pipeline between the BOG outlet of the LNG storage tank 2 and the inlet of the BOG heater 4. A second regulating valve 35 is provided on the discharge pipeline 103. The second natural gas buffer tank 38 is provided with a pressure sensor 37 for detecting the pressure of the natural gas within the second natural gas buffer tank 38. The pressure sensor 37 is signal-connected to the second regulating valve 35 (specifically, the pressure sensor 37 is electrically signal-connected to the controller of the second regulating valve 35). The second regulating valve 35 is configured to adjust the valve opening and / or open and close the second regulating valve 35 based on the pressure value detected by the pressure sensor 37. In order to ensure that the pressure of the natural gas entering the engine 41 meets the gas supply pressure requirement, the second regulating valve 35 is controlled by the pressure sensor 37; when the gas supply pressure exceeds the requirement (that is, when the pressure value detected by the pressure sensor 37 exceeds the preset range), the second regulating valve 35 opens to transport the natural gas to the methane cracking unit 6 for processing.

[0056] like Figure 1 As shown, as an embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a filling unit 1, which includes a filling valve group. The filling unit 1 is connected to the LNG storage tank 2. The filling unit 1 is used to connect to an external filling device (such as a filling device on a filling ship or an onshore filling station) to fill LNG into the LNG storage tank 2. Specifically, the outlet of the filling unit 1 is connected to the inlet of the LNG storage tank 2 through a first liquid injection pipeline (not numbered in the figure), and the inlet of the filling unit 1 is connected to the outlet of the LNG storage tank 2 through a first return air pipeline (not numbered in the figure); the filling unit 1 fills LNG into the LNG storage tank 2 through the first liquid injection pipeline, and at the same time, the gas in the LNG storage tank 2 is discharged to the filling unit 1 through the first return air pipeline to maintain the pressure in the LNG storage tank 2 stable.

[0057] like Figure 1As shown, as an embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a CO2 transfer pump 42 and a CO2 transfer unit 43. The CO2 transfer pump 42 can specifically be a deep well pump. The CO2 transfer unit 43 includes a transfer valve group. The inlet of the CO2 transfer pump 42 is connected to the liquid CO2 storage tank 25, and the outlet of the CO2 transfer pump 42 is connected to the CO2 transfer unit 43. The CO2 transfer unit 43 is used to connect to an external CO2 storage device (such as a barge ship or a CO2 storage device on a shore barge station) to transfer the liquid CO2 in the liquid CO2 storage tank 25 to the CO2 storage device through the CO2 transfer pump 42 and the CO2 transfer unit 43. Specifically, the inlet of the CO2 transfer unit 43 is connected to the outlet of the CO2 delivery pump 42 through a second liquid injection pipeline (not numbered in the figure), and the outlet of the CO2 transfer unit 43 is connected to the inlet of the liquid CO2 storage tank 25 through a second return air pipeline (not numbered in the figure); the CO2 delivery pump 42 transports the liquid CO2 in the liquid CO2 storage tank 25 to the CO2 transfer unit 43 and the CO2 storage equipment through the second liquid injection pipeline, and at the same time, the gas in the CO2 storage equipment is discharged to the CO2 storage tank 25 through the second return air pipeline to maintain the pressure inside the CO2 storage tank 25 stable.

[0058] like Figure 1 As shown, as an embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a CO2 cylinder 45, which is used to store CO2 gas. The CO2 cylinder 45 is connected to the inlet of the CO2 compressor 27 (specifically, the CO2 cylinder 45 can be connected to the pipeline between the outlet of the CO2 drying device 24 and the inlet of the CO2 compressor 27). Specifically, when the system is initially running or the engine 41 has not yet stably operated, the engine 41 does not produce enough exhaust gas, so the system cannot supply enough CO2. At this time, the valve of the branch where the CO2 cylinder 45 is located is opened (not shown in the figure), and the CO2 cylinder 45 is used to supply CO2 to the system; when the system is running stably, the engine 41 produces enough exhaust gas, and the system can supply enough CO2. At this time, the valve of the branch where the CO2 cylinder 45 is located is closed, and the engine exhaust gas is used to supply CO2 to the system. At the same time, when the natural gas supply of the engine 41 does not match the amount of CO2 captured from the exhaust gas, the CO2 cylinder 45 can also be used to adjust the CO2 gas volume to ensure stable operation of the system.

[0059] like Figure 2As shown, as another embodiment, the ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a CO2 delivery pump 42 and a CO2 heater 50. The inlet of the CO2 delivery pump 42 is connected to the liquid CO2 storage tank 25, and the outlet of the CO2 delivery pump 42 is connected to the inlet of the CO2 heater 50 (that is, the outlet of the CO2 delivery pump 42 is divided into two outlets, one outlet is connected to the CO2 transfer unit 43, and the other outlet is connected to the inlet of the CO2 heater 50). The outlet of the CO2 heater 50 is connected to the inlet of the CO2 compressor 27 (specifically, the outlet of the CO2 heater 50 can be connected to the pipeline between the CO2 outlet of the gas-liquid separation tank 23 and the inlet of the CO2 drying device 24). The CO2 delivery pump 42 is used to pump out the liquid CO2 stored in the liquid CO2 storage tank 25, and then heated and vaporized into gaseous CO2 by the CO2 heater 50, thereby replacing the function of the above-mentioned CO2 cylinder 45. Specifically, when the system is initially running or the engine 41 has not yet stabilized, the engine 41 does not produce enough exhaust gas, so the system cannot supply enough CO2. At this time, the CO2 delivery pump 42 and the CO2 heater 50 are turned on, and the liquid CO2 storage tank 25 is used to supply CO2 to the system. When the system stabilizes, the engine 41 produces enough exhaust gas, and the system is able to supply enough CO2. At this time, the CO2 delivery pump 42 and the CO2 heater 50 are turned off, and the engine exhaust gas is used to supply CO2 to the system. At the same time, when the natural gas supply of the engine 41 does not match the amount of CO2 captured from the exhaust gas, the liquid CO2 in the liquid CO2 storage tank 25 can also be heated and vaporized to adjust the CO2 gas volume to ensure stable operation of the system.

[0060] An embodiment of the present invention further provides a ship, comprising the above-mentioned ship LNG fuel supply and exhaust gas carbon dioxide capture system.

[0061] As an implementation method, the working process of the ship LNG fuel supply and tail gas carbon dioxide capture system is as follows:

[0062] When the system begins operation, CO2 cylinder 45 is opened. The CO2 output from CO2 cylinder 45 is stabilized by the first CO2 buffer tank 26 before entering the CO2 compressor 27 for high-pressure compression. The compressed, high-pressure CO2 is then stabilized by the second CO2 buffer tank 28 before entering the ejector 30. As the high-pressure CO2 flows through the receiving chamber of the ejector 30, it creates a suction force, creating a sufficient pressure differential between the interior of the LNG storage tank 2 and the interior of the ejector 30, allowing LNG to be automatically extracted from the LNG storage tank 2. The LNG extracted from the LNG storage tank 2 is heated by the mixed gas heat exchanger 32 before entering the LNG vaporizer 31. After passing through the LNG vaporizer 31, the LNG is heated to natural gas. The natural gas and the high-temperature, high-pressure CO2 mix within the ejector 30, exchanging energy and increasing both the temperature and pressure of the natural gas, ultimately raising the pressure to the required supply pressure for the engine 41. The natural gas and CO2 mixture exchanges heat with low-temperature LNG in the mixed gas heat exchanger 32, cooling the mixture. Because the condensation temperature of natural gas is much lower than that of CO2 at the same pressure, the natural gas remains in a gaseous state after being cooled, while the CO2 condenses into a liquid state. The natural gas / liquid CO2 mixture, cooled by the mixed gas heat exchanger 32, enters the flash tank 44. The gas-liquid separation function of the flash tank 44 separates the natural gas and liquid CO2. Simultaneously, the flash evaporation of the flash tank 44 further liquefies the small amount of unliquefied CO2 in the gas-liquid mixture into liquid CO2, improving the separation efficiency of the natural gas and CO2. The separated liquid CO2 flows through the bottom outlet of the flash tank 44 into the liquid CO2 storage tank 25 for storage, while the separated natural gas is discharged from the top outlet of the flash tank 44 in gaseous form. Since the engine 41 does not produce enough exhaust gas at this time, the heat of the exhaust gas cannot meet the heat demand for natural gas heating. At this time, the first control valve 48 is controlled to open and the second control valve 49 is controlled to close, allowing the natural gas in the flash tank 44 to flow to the natural gas heater 46 for heating. After the natural gas is heated to the gas supply temperature of the engine 41 by the natural gas heater 46, it is delivered to the engine 41 for combustion. To prevent the liquid CO2 temperature from being too low and causing ice blockage, the temperature value detected by the first temperature sensor 33 on the flash tank 44 is used to control the opening of the first regulating valve 3, and then control the flow of LNG entering the mixed gas heat exchanger 32 to prevent the liquid CO2 temperature from being below the freezing point and causing ice blockage, thereby ensuring the safe operation of the system. When the ship docks at the port, the liquid CO2 in the liquid CO2 storage tank 25 is pressurized by the CO2 transfer pump 42 and then transported to the shore for processing through the CO2 transfer unit 43, thereby achieving the capture and utilization of CO2 and achieving the ship's carbon emission reduction goals.

[0063] When the system is operating stably, the high-temperature exhaust gas generated by engine 41 passes through flue gas filter 40 for dust removal before entering flue gas heat exchanger 34. At this point, the valve on the natural gas heater 46 pipeline (i.e., first control valve 48) is cut off, and the valve on the natural gas pipeline to flue gas heat exchanger 34 (i.e., second control valve 49) is opened. The engine exhaust gas is then used to heat the natural gas, thereby recovering the waste heat from the engine exhaust. The third regulating valve 39 on the flue gas pipeline is controlled by the second temperature sensor 36 on the second natural gas buffer tank 38 to ensure that the gas supply temperature meets the engine's requirements. After heat exchange with the natural gas, the engine exhaust gas cools down and is further pressurized by the flue gas blower 47 before entering the absorption tower 15. The alcoholamine solution is sprayed from top to bottom from the first spray device 152 at the top of the absorption tower 15, and the tail gas flows from bottom to top in the absorption tower 15. The alcoholamine solution and the tail gas are fully contacted and reacted in countercurrent in the first filler 151, so that the alcoholamine solution absorbs CO2 in the tail gas, and the clean gas (i.e., decarbonized tail gas) from which CO2 has been removed is discharged from the tail gas outlet 150 at the top of the absorption tower 15. The alcoholamine rich liquid that absorbs CO2 is discharged from the bottom outlet of the absorption tower 15, and after being pressurized by the rich liquid pump 16 and heated by heat exchange in the rich liquid heat exchanger 17, it is sprayed from top to bottom from the second spray device 193 at the top of the decomposition tower 19. The amine solution at the bottom of the desorption tower 19 is divided into two paths. One path of the amine solution is pressurized by the second lean liquid pump 20 and then enters the lean liquid heater 21 for heating. The heated amine solution enters the second filler 191 in the desorption tower 19 to provide heat for the desorption of CO2. The amine rich liquid sprayed by the second spray device 193 contacts the heated amine solution in the second filler 191, so that the CO2 in the amine rich liquid escapes due to heat. The separated CO2 gas is discharged from the top outlet of the desorption tower 19 and finally transported to the CO2 compressor 27. The amine solution after removing CO2 flows downward to the bottom of the desorption tower 19; the other path of the amine solution is pressurized by the first lean liquid pump 18, cooled in turn by the lean and rich liquid heat exchanger 17 and the lean liquid cooler 14, and then sprayed again by the first spray device 152 to realize the recycling of the amine solution. Since the CO2 gas discharged from the top outlet of the analysis tower 19 is rich in water vapor, it is cooled by the CO2 cooler 22 to condense the water vapor in the CO2, and then enters the gas-liquid separation tank 23 to achieve preliminary separation of CO2 and condensed water. The separated condensed water is discharged from the bottom outlet of the gas-liquid separation tank 23, and the separated CO2 is discharged from the top outlet of the gas-liquid separation tank 23 to the CO2 drying device 24. The CO2 is further dehydrated by the CO2 drying device 24, so that the dew point of CO2 is reduced to below -40°C to avoid ice blockage when the CO2 subsequently contacts the low-temperature natural gas. The dried CO2 is then transported to the CO2 compressor 27. After being compressed by the CO2 compressor 27, it enters the ejector 30 to extract LNG from the LNG storage tank 2, thereby realizing the simultaneous start-up of the LNG gas supply system and the tail gas CO2 capture system.When both systems are operating normally, close the valve on the CO2 cylinder 45. When the natural gas supply from the engine 41 does not match the amount of CO2 captured from the flue gas, use the CO2 cylinder 45 to adjust the CO2 gas volume to ensure stable operation of the system.

[0064] During the vessel's voyage, as the LNG in LNG tank 2 continuously evaporates into BOG, the pressure in LNG tank 2 gradually increases. To prevent overpressure in LNG tank 2, when the pressure in LNG tank 2 reaches a certain limit, the BOG gas is discharged from the top pipeline of LNG tank 2, heated by BOG heater 4, and then enters BOG buffer tank 5. Since the BOG gas in LNG tank 2 is primarily composed of methane, it is catalytically cracked by methane cracker 6 to form a mixture of hydrogen and nitrogen. This mixture is then purified by hydrogen purification unit 7 to remove nitrogen, resulting in pure hydrogen. The hydrogen is then transported to hydrogen fuel cell 8, which converts the chemical energy of the hydrogen into electrical energy. This energy is then converted by first DC inverter 9 and supplied to the ship's DC power grid 12. A portion of this electrical energy is converted to AC power by the AC-DC converter 13 and supplied to the ship's electrical equipment, while also providing power to the methane cracker 6 and hydrogen purification unit 7. Excess electrical energy is converted by the first DC inverter 11 and then transferred to the battery 10 for storage. Furthermore, to ensure that the natural gas pressure entering the engine 41 meets the required supply pressure, a pressure sensor 37 on the second natural gas buffer tank 38 controls the second regulating valve 35. When the supply pressure exceeds the required pressure, the second regulating valve 35 opens, transferring the natural gas from the second natural gas buffer tank 38 to the methane cracker 6 for processing.

[0065] The ship LNG fuel supply and exhaust CO2 capture system provided by the embodiment of the present invention realizes the organic combination of the LNG supply system and the exhaust CO2 capture system through reasonable design. It can realize the effective utilization of LNG cold energy and engine exhaust heat energy on the basis of stable LNG supply to the engine 41, thereby reducing the energy consumption of the system. At the same time, it can save equipment such as cryogenic submersible pumps, natural gas superchargers, CO2 liquefaction equipment, flue gas pretreatment towers, etc., which is conducive to reducing equipment costs and operating costs. The advantages of this system include:

[0066] 1. Use the ejector 30 to realize natural gas supercharging, reduce system investment and operation cost: by setting CO2 compressor 27 and ejector 30, using CO2 compressor 27 to pressurize CO2 to form high pressure CO2, and then using high pressure CO2 to automatically eject LNG in LNG storage tank 2 through ejector 30, on the one hand, it replaces the function of low temperature submerged pump with high investment, reduces the cost of system equipment and maintenance difficulty, on the other hand, it realizes the energy exchange of natural gas and high pressure CO2 in the ejector 30, completes the supercharging of natural gas, and can save the natural gas supercharging equipment.

[0067] 2. Use low temperature LNG to realize CO2 liquefaction and realize cold energy recovery: according to the different characteristics of natural gas and CO2 condensation temperature, use low temperature LNG to liquefy CO2, separate natural gas and liquid CO2 through flash tank 44, so as to realize CO2 liquefaction and LNG cold energy utilization at the same time, reduce the overall energy consumption of the system, and save the CO2 liquefaction device.

[0068] 3. Realize waste heat utilization and improve the total energy efficiency of the system: by setting up the flue gas heat exchanger 34, use the engine exhaust gas to heat the natural gas, on the one hand, realize the recycling of ship waste heat, on the other hand, through heat exchange with low temperature natural gas, realize the flue gas cooling, replace the function of traditional flue gas pretreatment tower, reduce the investment cost of the system.

[0069] 4. Use hydrogen fuel cell 8 to supply power for the ship, which is more green and environmental protection: the hydrogen produced by natural gas cracking is transported to hydrogen fuel cell 8 to convert into electric energy to supply the electric equipment of the ship, without using traditional diesel generator, which is more green and environmental protection.

[0070] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A ship LNG fuel supply and tail gas carbon dioxide capture system, characterized in that: It comprises an LNG storage tank (2), a CO2 separation device (100), a CO2 compressor (27), an ejector (30), an LNG vaporization heater (31), a mixed gas heat exchanger (32), a flash tank (44), a liquid CO2 storage tank (25), a flue gas heat exchanger (34) and an engine (41); The LNG storage tank (2) is connected to the LNG inlet of the mixed gas heat exchanger (32) via a liquid infusion pipeline (101); the LNG outlet of the mixed gas heat exchanger (32) is connected to the inlet of the LNG vaporization heater (31); and the outlet of the LNG vaporization heater (31) is connected to the low-pressure inlet of the ejector (30); The exhaust gas outlet of the engine (41) is connected to the exhaust gas inlet of the flue gas heat exchanger (34), the exhaust gas outlet of the flue gas heat exchanger (34) is connected to the inlet of the CO2 separation device (100), the CO2 outlet of the CO2 separation device (100) is connected to the inlet of the CO2 compressor (27), the outlet of the CO2 compressor (27) is connected to the high-pressure inlet of the ejector (30), the mixed fluid outlet of the ejector (30) is connected to the mixed fluid inlet of the mixed gas heat exchanger (32), the mixed fluid outlet of the mixed gas heat exchanger (32) is connected to the inlet of the flash tank (44), the liquid CO2 outlet of the flash tank (44) is connected to the liquid CO2 storage tank (25), the natural gas outlet of the flash tank (44) is connected to the natural gas inlet of the flue gas heat exchanger (34), and the natural gas outlet of the flue gas heat exchanger (34) is connected to the fuel inlet of the engine (41).

2. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 1, characterized in that: The CO2 separation device (100) includes a lean liquid cooler (14), an absorption tower (15), a rich liquid pump (16), a lean and rich liquid heat exchanger (17), a first lean liquid pump (18), a desorption tower (19), a second lean liquid pump (20) and a lean liquid heater (21); The tail gas outlet of the flue gas heat exchanger (34) is connected to the bottom inlet of the absorption tower (15), and the top of the absorption tower (15) is provided with a tail gas outlet (150); the bottom outlet of the absorption tower (15) is connected to the inlet of the rich liquid pump (16), the outlet of the rich liquid pump (16) is connected to the rich liquid inlet of the lean-rich liquid heat exchanger (17), the rich liquid outlet of the lean-rich liquid heat exchanger (17) is connected to the top inlet of the decomposition tower (19), and the top outlet of the decomposition tower (19) is connected to the inlet of the CO2 compressor (27); The bottom outlet of the analytical tower (19) is divided into two routes. One bottom outlet of the analytical tower (19) is connected to the inlet of the first lean liquid pump (18), the outlet of the first lean liquid pump (18) is connected to the lean liquid inlet of the lean-rich liquid heat exchanger (17), the lean liquid outlet of the lean-rich liquid heat exchanger (17) is connected to the inlet of the lean liquid cooler (14), and the outlet of the lean liquid cooler (14) is connected to the top inlet of the absorption tower (15); the other bottom outlet of the analytical tower (19) is connected to the inlet of the second lean liquid pump (20), the outlet of the second lean liquid pump (20) is connected to the lean liquid inlet of the lean liquid heater (21), and the lean liquid outlet of the lean liquid heater (21) is connected to the analytical tower (19).

3. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 2, characterized in that: A first filler (151) is provided in the absorption tower (15), and the first filler (151) is located between the bottom inlet and the top inlet of the absorption tower (15); A second filler (191) is provided in the analytical tower (19), and the second filler (191) is located between the bottom outlet and the top inlet of the analytical tower (19); a lean liquid inlet (192) is provided on the analytical tower (19) at a position corresponding to the second filler (191), and the lean liquid outlet of the lean liquid heater (21) is connected to the lean liquid inlet (192) of the analytical tower (19).

4. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 2, characterized in that: A flue gas blower (47) is provided on the pipeline between the tail gas outlet of the flue gas heat exchanger (34) and the bottom inlet of the absorption tower (15).

5. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 2, characterized in that: The ship LNG fuel supply and tail gas carbon dioxide capture system also includes a CO2 cooler (22), a gas-liquid separation tank (23) and a CO2 drying device (24); the top outlet of the analysis tower (19) is connected to the inlet of the CO2 cooler (22), the outlet of the CO2 cooler (22) is connected to the inlet of the gas-liquid separation tank (23), the CO2 outlet of the gas-liquid separation tank (23) is connected to the inlet of the CO2 drying device (24), and the outlet of the CO2 drying device (24) is connected to the inlet of the CO2 compressor (27).

6. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 1, characterized in that: A first regulating valve (3) is provided on the infusion pipeline (101), a first temperature sensor (33) is provided on the flash tank (44), and the first temperature sensor (33) is signal-connected to the first regulating valve (3).

7. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 1, characterized in that: The ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a natural gas heater (46); the natural gas outlet of the flash tank (44) is divided into two routes, one natural gas outlet of the flash tank (44) is connected to the natural gas inlet of the flue gas heat exchanger (34), and the other natural gas outlet of the flash tank (44) is connected to the inlet of the natural gas heater (46), and the outlet of the natural gas heater (46) is connected to the fuel inlet of the engine (41).

8. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 1, characterized in that: The ship LNG fuel supply and exhaust gas carbon dioxide capture system also includes a second natural gas buffer tank (38); the natural gas outlet of the flue gas heat exchanger (34) is connected to the inlet of the second natural gas buffer tank (38), and the outlet of the second natural gas buffer tank (38) is connected to the fuel inlet of the engine (41); a second temperature sensor (36) is provided on the second natural gas buffer tank (38), and a third regulating valve (39) is provided on the pipeline between the exhaust gas outlet of the engine (41) and the exhaust gas inlet of the flue gas heat exchanger (34), and the second temperature sensor (36) is connected to the third regulating valve (39) for signal transmission.

9. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to claim 1, characterized in that: The ship LNG fuel supply and tail gas carbon dioxide capture system further comprises a BOG heater (4), a methane cracking device (6), a hydrogen purification device (7), a hydrogen fuel cell (8) and a ship DC power grid (12); the BOG outlet of the LNG storage tank (2) is connected to the inlet of the BOG heater (4), the outlet of the BOG heater (4) is connected to the inlet of the methane cracking device (6), the outlet of the methane cracking device (6) is connected to the inlet of the hydrogen purification device (7), the outlet of the hydrogen purification device (7) is connected to the inlet of the hydrogen fuel cell (8), and the hydrogen fuel cell (8) is electrically connected to the ship DC power grid (12).

10. The ship LNG fuel supply and exhaust gas carbon dioxide capture system according to any one of claims 1 to 9, characterized in that: The ship LNG fuel supply and tail gas carbon dioxide capture system further comprises a CO2 gas cylinder (45), wherein the CO2 gas cylinder (45) is connected to the inlet of the CO2 compressor (27); Alternatively, the ship LNG fuel supply and exhaust gas carbon dioxide capture system further includes a CO2 delivery pump (42) and a CO2 heater (50), wherein the inlet of the CO2 delivery pump (42) is connected to the liquid CO2 storage tank (25), the outlet of the CO2 delivery pump (42) is connected to the inlet of the CO2 heater (50), and the outlet of the CO2 heater (50) is connected to the inlet of the CO2 compressor (27).

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