Carbon capture and cold-heat energy cascade utilization system suitable for dynamic working condition of LNG ship

Abstract

The application discloses a carbon capture and cold-heat energy cascade utilization system suitable for LNG ship dynamic working conditions and belongs to the technical field of cold-heat energy comprehensive utilization. It comprises an LNG cold energy dynamic utilization unit, a dynamic low-temperature liquefied CO2 storage unit and a control center unit. The LNG cold energy dynamic utilization unit is divided into two paths. One path comprises an LNG storage tank, an LNG gas supply valve, a first-stage LNG heat exchanger, a first-stage working medium storage tank, a first-stage throttle valve, a first-stage working medium pump, a first-stage CO2 heat exchanger and a first-stage expander. The application aims to realize the following functions: when the ship working condition changes and the user power demand changes, the LNG cold energy and the main engine waste heat utilization demand under the variable working condition can be adapted by controlling the refrigerant flow, the matching between the user power demand and the supply amount is realized, and perfect CO2 capture is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of comprehensive utilization of cold and heat energy, and relates to an energy utilization system of an LNG power ship, in particular to a carbon capture and cold and heat energy cascade utilization system suitable for dynamic working conditions of an LNG ship. BACKGROUND

[0002] In order to achieve the goal of the Paris climate agreement, the carbon emissions of the maritime sector need to be greatly reduced. To this end, the International Maritime Organization (IMO) has set a target of reducing the total amount of greenhouse gas emissions in the maritime sector by at least 50% by 2050, which requires a reduction of about 85% of carbon dioxide emissions per ship. In addition, a large amount of cold energy is wasted when the existing LNG power ship LNG is gasified and warmed up, and the low-temperature seawater is discharged into the sea.

[0003] In the patent document with the authorized publication number CN115263466A, a LNG power ship low-temperature carbon capture coupled cold energy and waste heat cascade utilization system is proposed, which constructs an oxygen-enriched combustion system of the main engine under the condition of meeting the air intake condition of the ship, can fully recover and utilize the cold energy and waste heat of large ships, and at the same time, efficiently captures the exhaust gas carbon dioxide, achieving the purpose of energy saving and emission reduction, but the system does not consider the changes of LNG cold energy and ship flue gas when the ship is running dynamically. When the LNG cold energy and the ship flue gas change, the system cannot realize dynamic cold and heat energy utilization, resulting in a large amount of energy waste.

[0004] In the patent document with the authorized publication number CN115540498A, a cold and heat energy utilization device and carbon capture method suitable for LNG ships are proposed, which uses the cold source provided by the evaporation of liquefied natural gas to liquefy and store CO2, reduces the refrigeration process, and consumes less energy for CO2 capture, but the system does not consider that the exhaust gas discharged after absorption by the absorption tower still has a large amount of waste heat that can be utilized, and the flue gas is changing with the running of the ship, and cannot realize the full utilization of the flue gas waste heat under dynamic conditions.

[0005] Therefore, in view of the above problems, it is necessary to design a carbon capture and cold and heat energy cascade utilization system suitable for dynamic working conditions of an LNG ship to solve the above problems. SUMMARY

[0006] The present application aims to realize the matching of user's demand and supply of electric quantity by controlling the flow of refrigerant when the working condition of the ship changes and the user's demand for electric quantity changes, to realize the utilization of LNG cold energy and main engine waste heat under variable working conditions, and to realize perfect CO2 capture. The following technical solutions are used to realize the above purposes:

[0007] The application discloses a carbon capture and cold-heat energy cascade utilization system suitable for LNG ship dynamic conditions.

[0008] The LNG cold energy dynamic utilization unit is divided into two paths, one of which comprises an LNG storage tank, an LNG gas supply valve, a first-stage LNG heat exchanger, a first-stage working medium storage tank, a first-stage throttling valve, a first-stage working medium pump, a first-stage CO2 heat exchanger and a first-stage expander.

[0009] The outlet of the LNG storage tank, the LNG gas supply valve, the cold end inlet of the first-stage LNG heat exchanger, the first-stage working medium storage tank, the first-stage throttling valve, the inlet end of the first-stage working medium pump and the cold side inlet of the first-stage CO2 heat exchanger are connected in communication, the cold side outlet of the first-stage CO2 heat exchanger is connected in communication with the inlet of the first-stage expander, the outlet of the first-stage expander is connected in communication with the hot side inlet of the first-stage LNG heat exchanger, and the first-stage working medium sequentially passes through the first-stage throttling valve, is pressurized by the first-stage working medium pump, absorbs heat and is heated by the first-stage CO2 heat exchanger, does work by the first-stage expander, is cooled by the first-stage LNG heat exchanger and then returns to the first-stage working medium storage tank, thereby forming a first-stage organic Rankine cycle.

[0010] The other path comprises a second-stage LNG heat exchanger, a second-stage working medium storage tank, a second-stage throttling valve, a second-stage working medium pump, a cylinder liner water heat exchanger and a second-stage expander, the cold side inlet of the second-stage LNG heat exchanger is connected in communication with the cold side outlet of the first-stage LNG heat exchanger, the hot side outlet of the second-stage LNG heat exchanger, the second-stage working medium storage tank, the second-stage throttling valve, the second-stage working medium pump and the cold side inlet of the cylinder liner water heat exchanger are sequentially connected in communication, the cold side outlet of the cylinder liner water heat exchanger is connected in communication with the inlet of the second-stage expander, and the outlet of the second-stage expander is sequentially connected in communication with the hot side inlet of the second-stage LNG heat exchanger, so that the second-stage working medium sequentially passes through the second-stage throttling valve, is pressurized by the second-stage working medium pump, absorbs heat and is heated by the cylinder liner water heat exchanger, does work by the second-stage expander, is cooled by the second-stage LNG heat exchanger and then returns to the second-stage working medium storage tank, thereby forming a second-stage organic Rankine cycle.

[0011] The dynamic low-temperature liquefied CO2 storage unit comprises a separator, a third-stage CO2 heat exchanger, a third-stage working medium pump, a third-stage throttling valve, a third-stage working medium tank, a second-stage seawater heat exchanger, a third-stage expander and a CO2 storage tank.

[0012] The inlet of the separator is communicated with the gas outlet above the absorption tower; the outlet of the separator is communicated with the hot side inlet of the third CO2 heat exchanger, the hot side outlet of the third CO2 heat exchanger is communicated with the hot side inlet of the first CO2 heat exchanger, and the hot side outlet of the first CO2 heat exchanger is communicated with the inlet of the CO2 storage tank; the cold side outlet of the third CO2 heat exchanger is communicated with the inlet of the third expander, the outlet of the third expander is communicated with the hot side inlet of the second seawater heat exchanger, the hot side outlet of the second seawater heat exchanger, the third working medium storage tank, the third throttling valve and the third working medium pump are sequentially communicated, and the outlet of the third working medium pump is communicated with the hot side inlet of the third CO2 heat exchanger; the pure CO2 separated by the separator is stored in the CO2 storage tank after being cooled by the third CO2 heat exchanger and the first CO2 heat exchanger; the working medium sequentially passes through the third throttling valve, is pressurized by the third working medium pump, is heated and warmed by the third CO2 heat exchanger, does work by the third expander, and is cooled by the second seawater heat exchanger and then returns to the third working medium storage tank, thereby forming the third organic Rankine cycle.

[0013] The control center unit comprises a control center; and the control center is electrically connected with the LNG supply valve, the first throttling valve, the second throttling valve and the third throttling valve respectively.

[0014] Preferably, the temperature range of the first organic Rankine cycle working medium is-120-18℃, and the temperature range of the second organic Rankine cycle working medium is-130-85℃.

[0015] As a preferred example, the first working medium and the second working medium are R290, the third working medium is R134a, and the first working medium, the second working medium and the third working medium all serve as refrigerants.

[0016] As a preferred example, the marine main engine combustion unit comprises an engine main engine; the LNG in the LNG storage tank is sequentially gasified into natural gas by passing through the LNG supply valve, the first LNG heat exchanger and the second LNG heat exchanger through pipelines, and then enters the marine engine main engine, so that the natural gas does work in the engine main engine by burning with air.

[0017] As a preferred example, the ship waste heat dynamic utilization carbon capture power generation unit comprises a waste heat recovery device, a first seawater heat exchanger, a heat transfer working medium tank, a fourth throttling valve, a heat transfer working medium pump, an absorption tower, a rich liquid pump, a lean-rich liquid heat exchanger, a stripping tower, a reboiler, a lean liquid heat exchanger, a mixer and a multi-effect distillation reverse electrodialysis heat engine.

[0018] The end of the engine host is connected with the hot side inlet of the waste heat recovery device, the hot side outlet of the waste heat recovery device is connected with the hot side inlet of the first seawater heat exchanger, the hot side outlet of the first seawater heat exchanger is connected with the outlet of the absorption tower, for the flue gas discharged after combustion of the engine host to enter the waste heat recovery device through the hot side inlet of the waste heat recovery device, then the flue gas after heat exchange enters the first seawater heat exchanger through the hot side outlet of the waste heat recovery device for cooling, the flue gas after cooling enters the absorption tower through the hot side outlet of the first seawater heat exchanger, the bottom outlet of the absorption tower is connected with the inlet of the rich liquid pump, the outlet of the rich liquid pump is connected with the cold side inlet of the lean-rich liquid heat exchanger, the cold side outlet of the lean-rich liquid heat exchanger is connected with the inlet of the stripping tower, for the rich liquid at the bottom outlet of the absorption tower to enter the rich liquid pump through the inlet of the rich liquid pump, the rich liquid after pressure boosting enters the lean-rich liquid heat exchanger through the outlet of the rich liquid pump and the cold side inlet of the lean-rich liquid heat exchanger for heat absorption, the rich liquid after heat absorption enters the stripping tower through the cold side outlet of the lean-rich liquid heat exchanger and the inlet of the stripping tower for CO2 stripping, the bottom outlet of the stripping tower is connected with the hot side inlet of the lean-rich liquid heat exchanger, the hot side outlet of the lean-rich liquid heat exchanger is connected with the lean liquid heat exchanger, the hot side outlet of the lean liquid heat exchanger is connected with the inlet of the mixer, the outlet of the mixer is connected with the inlet of the absorption tower, for the lean liquid in the stripping tower to enter the lean-rich liquid heat exchanger through the bottom outlet of the stripping tower and the hot side inlet of the lean-rich liquid heat exchanger for heat exchange, the lean liquid after heat exchange enters the lean liquid heat exchanger through the hot side outlet of the lean-rich liquid heat exchanger and the hot side inlet of the lean liquid heat exchanger for cooling, the lean liquid after cooling enters the mixer through the hot side outlet of the lean liquid heat exchanger and the inlet of the mixer, and the lean liquid is mixed with the MEA supplement liquid and then enters the absorption tower through the outlet of the mixer and the inlet of the absorption tower;

[0019] The cold side outlet of the flue gas waste heat recovery device is connected with the inlet of the heat transfer medium tank, the outlet of the heat transfer medium tank, the fourth throttling valve and the inlet of the heat transfer medium pump are connected, the outlet of the heat transfer medium pump is connected with the hot side inlet of the reboiler, the hot side outlet of the reboiler is connected with the cold side inlet of the flue gas waste heat recovery device, for the heat transfer medium to enter the heat transfer medium pump through the fourth throttling valve, then enter the reboiler for heat exchange, the heat transfer medium after heat exchange enters the flue gas waste heat recovery device through the hot side outlet of the reboiler and the cold side inlet of the flue gas waste heat recovery device, the heat transfer medium after temperature rising enters the heat transfer medium tank through the cold side outlet of the flue gas waste heat recovery device and the inlet of the heat transfer medium tank, to complete the first stage of waste heat recovery of the flue gas waste heat; the cold side outlet of the reboiler is connected with the side wall of the stripping tower, and the bottom of the stripping tower is connected with the cold side inlet of the reboiler;

[0020] The top of the absorption tower is connected with the inlet of the multi-effect distillation reverse electrodialysis heat engine, to complete the second stage of flue gas waste heat recovery, and the outlet of the multi-effect distillation reverse electrodialysis heat engine is connected with the atmosphere.

[0021] Further, the heat transfer working medium is heavy fuel oil or other heat transfer fluid with good heat transfer characteristics; the third-stage organic Rankine cycle working medium temperature range is 10-96 DEG C.

[0022] As a preferred example, the control center is further electrically connected with a fourth-stage throttle valve.

[0023] As a preferred example, a ship power supply unit is further included, and the ship power supply unit includes a storage battery; input ends of the storage battery are electrically connected with input sides of the first-stage expander, the second-stage expander, the multi-effect distillation reverse electrodialysis heat engine and the third-stage expander respectively; and an output side of the storage battery is connected with a ship user demand side.

[0024] The present application has the following beneficial effects:

[0025] 1. The present application solves the problem of insufficient utilization of LNG and flue gas under dynamic changes of LNG and flue gas during ship operation through the LNG cold energy dynamic utilization unit, the ship waste heat dynamic utilization carbon capture power generation unit and the dynamic low-temperature liquefied CO2 power generation unit, and realizes dynamic cascade utilization of LNG cold energy and ship waste heat.

[0026] 2. The present application realizes the matching of user's power demand and supply when the ship working condition changes and the user power demand changes through the LNG cold energy dynamic utilization unit, the ship waste heat dynamic utilization carbon capture power generation unit and the dynamic low-temperature liquefied CO2 power generation unit, and controls the refrigerant flow to adapt to the demand of LNG cold energy and main engine waste heat utilization under variable working conditions, realizes the matching of user's power demand and supply, and realizes perfect CO2 capture.

[0027] 3. The present application realizes cascade utilization of waste heat generated in the carbon capture process through the multi-effect distillation reverse electrodialysis heat engine in the dynamic low-temperature liquefied CO2 power generation unit. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The present application is a process flow schematic diagram;

[0029] In the diagram: LNG storage tank 1; LNG supply valve 2; first-stage LNG heat exchanger 3; first-stage working fluid storage tank 4; first-stage throttle valve 5; first-stage working fluid pump 6; first-stage CO2 heat exchanger 7; first-stage expander 8; second-stage LNG heat exchanger 9; second-stage working fluid storage tank 10; second-stage throttle valve 11; second-stage working fluid pump 12; cylinder liner water heat exchanger 13; second-stage expander 14; main engine 15; waste heat recovery device 16; first-stage seawater heat exchanger 17; heat transfer working fluid tank 1 8; Fourth-stage throttling valve 19; Heat transfer working fluid pump 20; Absorption tower 21; Rich liquid pump 22; Lean and rich liquid heat exchanger 23; Desorption tower 24; Reboiler 25; Lean liquid heat exchanger 26; Mixer 27; Multi-effect distillation reverse electrodialysis heat engine 28; Separator 29; Third-stage CO2 heat exchanger 30; Third-stage working fluid pump 31; Third-stage throttling valve 32; Third-stage working fluid tank 33; Second-stage seawater heat exchanger 34; Third-stage expander 35; CO2 storage tank 36; Battery 37; Control center 38. Detailed Implementation

[0030] To facilitate a clear understanding of the technical means, creative features, objectives, and effects of this invention, the invention will be further described below in conjunction with specific illustrations.

[0031] like Figure 1 As shown, a carbon capture and thermal energy cascade utilization system suitable for dynamic operating conditions of LNG ships includes an LNG cold energy dynamic utilization unit, a dynamic cryogenic liquefied CO2 storage unit, and a control center unit:

[0032] The LNG cold energy dynamic utilization unit is divided into two paths. One path includes LNG storage tank 1, LNG gas supply valve 2, first-stage LNG heat exchanger 3, first-stage working fluid storage tank 4, first-stage throttle valve 5, first-stage working fluid pump 6, first-stage CO2 heat exchanger 7, and first-stage expander 8.

[0033] The outlet of LNG storage tank 1, LNG supply valve 2, cold end inlet of first-stage LNG heat exchanger 3, first-stage working fluid storage tank 4, first-stage throttle valve 5, inlet of first-stage working fluid pump 6, and cold side inlet of first-stage CO2 heat exchanger 7 are connected. The cold side outlet of first-stage CO2 heat exchanger 7 is connected to the inlet of first-stage expander 8. The outlet of first-stage expander 8 is connected to the hot side inlet of first-stage LNG heat exchanger 3. This allows the first-stage working fluid to pass through first-stage throttle valve 5, be pressurized by first-stage working fluid pump 6, absorb heat and heat up in first-stage CO2 heat exchanger 7, perform work in first-stage expander 8, and return to first-stage working fluid storage tank 4 after cooling in first-stage LNG heat exchanger 3, thus forming the first-stage organic Rankine cycle.

[0034] Another path includes the second stage LNG heat exchanger 9, the second stage working medium storage tank 10, the second stage throttling valve 11, the second stage working medium pump 12, the cylinder jacket water heat exchanger 13, and the second stage expander 14; the cold side inlet of the second stage LNG heat exchanger 9 is in communication with the cold side outlet of the first stage LNG heat exchanger 3, the hot side outlet of the second stage LNG heat exchanger 9, the second stage working medium storage tank 10, the second stage throttling valve 11, the second stage working medium pump 12, and the cold side inlet of the cylinder jacket water heat exchanger 13 are sequentially in communication, the cold side outlet of the cylinder jacket water heat exchanger 13 is in communication with the inlet of the second stage expander 14, and the outlet of the second stage expander 14 is sequentially in communication with the hot side inlet of the second stage LNG heat exchanger 9; the second stage working medium sequentially passes through the second stage throttling valve 11, is pressurized by the second stage working medium pump 12, absorbs heat and is heated by the cylinder jacket water heat exchanger 13, does work by the second stage expander 14, is cooled by the second stage LNG heat exchanger 9, and then returns to the second stage working medium storage tank 10 to form the second stage organic Rankine cycle;

[0035] The dynamic low-temperature liquefied CO2 storage unit includes a separator 29, a third stage CO2 heat exchanger 30, a third stage working medium pump 31, a third stage throttling valve 32, a third stage working medium tank 33, a second stage seawater heat exchanger 34, a third stage expander 35, and a CO2 storage tank 36;

[0036] The inlet of the separator 29 is in communication with the gas outlet above the resolving column 24; the outlet of the separator 29 is in communication with the hot side inlet of the third stage CO2 heat exchanger 30, the hot side outlet of the third stage CO2 heat exchanger 30 is in communication with the hot side inlet of the first stage CO2 heat exchanger 7, the hot side outlet of the first stage CO2 heat exchanger 7 is in communication with the inlet of the CO2 storage tank 36; the cold side outlet of the third stage CO2 heat exchanger 30 is in communication with the inlet of the third stage expander 35, the outlet of the third stage expander 35 is in communication with the hot side inlet of the second stage seawater heat exchanger 34, the hot side outlet of the second stage seawater heat exchanger 34, the third stage working medium storage tank 33, the third stage throttling valve 32, and the third stage working medium pump 31 are sequentially in communication, and the outlet of the third stage working medium pump 31 is in communication with the hot side inlet of the third stage CO2 heat exchanger 30; the pure CO2 obtained by the separator 29 is stored in the CO2 storage tank 36 after being cooled by the third stage CO2 heat exchanger 30 and the first stage CO2 heat exchanger 7; the working medium sequentially passes through the third stage throttling valve 32, is pressurized by the third stage working medium pump 31, absorbs heat and is heated by the third stage CO2 heat exchanger 30, does work by the third stage expander 35, is cooled by the second stage seawater heat exchanger 34, and then returns to the third stage working medium storage tank 33 to form the third stage organic Rankine cycle;

[0037] The control center unit includes a control center 38; the control center 38 is electrically connected with the LNG gas supply valve 2, the first stage throttling valve 5, the second stage throttling valve 11, and the third stage throttling valve 32, respectively, for directly controlling the opening degree of the LNG gas supply valve 2, the first stage throttling valve 5, the second stage throttling valve 11, and the third stage throttling valve 32 by the control center 38.

[0038] The first working medium and the second working medium are R290, the third working medium is R134a, and the first working medium, the second working medium and the third working medium all serve as refrigerants.

[0039] The marine main engine combustion unit comprises an engine main engine 15, LNG in the LNG storage tank 1 is gasified into natural gas by pipeline in sequence through the LNG gas supply valve 2, the first stage LNG heat exchanger 3 and the second stage LNG heat exchanger 9 and is introduced into the marine engine main engine 15, and the natural gas is used for heat combustion with air in the engine main engine 15.

[0040] The marine waste heat dynamic utilization carbon capture power generation unit comprises a waste heat recovery device 16, a first stage seawater heat exchanger 17, a heat transfer working medium tank 18, a fourth stage throttling valve 19, a heat transfer working medium pump 20, an absorption tower 21, a rich liquid pump 22, a lean and rich liquid heat exchanger 23, a stripping tower 24, a reboiler 25, a lean liquid heat exchanger 26, a mixer 27 and a multi-effect distillation reverse electrodialysis heat engine 28.

[0041] One end of the engine main machine 15 is connected with the hot side inlet of the waste heat recovery device 16, the hot side outlet of the waste heat recovery device 16 is connected with the hot end inlet of the first seawater heat exchanger 17, the hot end outlet of the first seawater heat exchanger 17 is connected with the outlet of the absorption tower 21, for the flue gas discharged after the engine main machine 15 combustion to enter the waste heat recovery device 16 through the hot side inlet of the waste heat recovery device 16 to exchange heat, then the flue gas after heat exchange enters the first seawater heat exchanger 17 to cool, the flue gas after cooling enters the absorption tower 21 through the outlet of the first seawater heat exchanger 17, the bottom outlet of the absorption tower 21 is connected with the inlet of the rich liquid pump 22, the outlet of the rich liquid pump 22 is connected with the cold side inlet of the lean-rich liquid heat exchanger 23, the cold side outlet of the lean-rich liquid heat exchanger 23 is connected with the inlet of the analysis tower 24, for the rich liquid at the bottom outlet of the absorption tower 21 to enter the rich liquid pump 22 through the inlet of the rich liquid pump 22, the rich liquid after pressure boosting enters the lean-rich liquid heat exchanger 23 to absorb heat through the outlet of the rich liquid pump 22 and the cold side inlet of the lean-rich liquid heat exchanger 23, the rich liquid after heat absorption enters the analysis tower 24 to analyze CO2 through the cold side outlet of the lean-rich liquid heat exchanger 23 and the inlet of the analysis tower 24, the bottom outlet of the analysis tower 24 is connected with the hot side inlet of the lean-rich liquid heat exchanger 23, the hot side outlet of the lean-rich liquid heat exchanger 23 is connected with the hot side inlet of the lean liquid heat exchanger 26, the hot side outlet of the lean liquid heat exchanger 26 is connected with the inlet of the mixer 27, the outlet of the mixer 27 is connected with the inlet of the absorption tower 21, for the lean liquid in the analysis tower 24 to enter the lean-rich liquid heat exchanger 23 to exchange heat through the bottom outlet of the analysis tower 24 and the hot side inlet of the lean-rich liquid heat exchanger 23, the lean liquid after heat exchange enters the lean liquid heat exchanger 26 to cool through the hot side outlet of the lean-rich liquid heat exchanger 23 and the hot side inlet of the lean liquid heat exchanger 26, the lean liquid after cooling enters the mixer 27 through the hot side outlet of the lean liquid heat exchanger 26 and the inlet of the mixer 27, the lean liquid is mixed with the MEA supplement liquid (it needs to be explained that the MEA supplement liquid is an ethanolamine solution) to enter the absorption tower 21 through the outlet of the mixer 27 and the inlet of the absorption tower 21;

[0042] The cold side outlet of the flue gas waste heat recovery device 16 is connected with the inlet of the heat transfer medium tank 18, the outlet of the heat transfer medium tank is connected with the inlet of the fourth stage throttling valve 19 and the inlet of the heat transfer medium pump 20, the outlet of the heat transfer medium pump 20 is connected with the hot side inlet of the reboiler 25, the hot side outlet of the reboiler 25 is connected with the cold side inlet of the flue gas waste heat recovery device 16, and the heat transfer medium enters the reboiler 25 for heat exchange after passing through the fourth stage throttling valve 19 and the heat transfer medium pump 20, the heat transfer medium after heat exchange enters the flue gas waste heat recovery device 16 through the hot side outlet of the reboiler 25 and the cold side inlet of the flue gas waste heat recovery device 16, the heat transfer medium after temperature rise enters the heat transfer medium tank 18 through the cold side outlet of the flue gas waste heat recovery device 16 and the inlet of the heat transfer medium tank 18, and one-stage waste heat recovery of the flue gas waste heat is completed; the cold side outlet of the reboiler 25 is connected with the side wall of the stripping tower 24, and the bottom of the stripping tower 24 is connected with the cold side inlet of the reboiler 25;

[0043] The top of the absorption tower 21 is connected with the inlet of the multi-effect distillation reverse electrodialysis heat machine 28, and the second-stage flue gas waste heat recovery is completed.

[0044] The control center 38 is also electrically connected with the fourth stage throttling valve 19, and the opening size of the fourth stage throttling valve 19 is directly controlled through the control center 38.

[0045] The ship power supply unit also includes a storage battery 37, the input ends of the storage battery 37 are electrically connected with the first stage expander 8, the second stage expander 14, the multi-effect distillation reverse electrodialysis heat machine 28 and the third stage expander 35, and the output side of the storage battery 37 is connected with a ship user demand side.

[0046] The temperature range of the first stage organic Rankine cycle working medium is -120-18℃, and the temperature range of the second stage organic Rankine cycle working medium is -130-85℃.

[0047] The heat transfer medium is a heavy fuel oil or other heat transfer fluid with good heat transfer characteristics, and the temperature range of the third stage organic Rankine cycle working medium is 10-96℃.

[0048] Working principle: during the uniform speed running of the ship, LNG (outlet flow is 3370kg / h, pressure is 3bar, and temperature is -162℃) in the LNG storage tank 1 enters the engine main machine 15 of the ship through the LNG supply valve 2, the first stage LNG heat exchanger 3 and the second stage LNG heat exchanger 9 (heat exchange to 9℃);

[0049] The circulating working medium (mainly R290, temperature -120℃, pressure 2bar, flow 1200kg / h) in the first stage circulating working medium tank 4 is passed through the first stage throttle valve 5 into the first stage circulating working medium pump 6 (temperature -119℃, pressure 8bar), then into the first stage CO2 heat exchanger 7 to exchange heat and increase temperature (temperature 18℃, pressure 8bar), then into the first stage expander 8 to generate electricity (temperature -28℃, pressure 2bar), then the circulating working medium after generating electricity is passed through the first stage LNG heat exchanger 3 to exchange heat and cool (temperature -120℃, pressure 2bar), and finally into the first stage circulating working medium tank 4 to complete the first stage organic Rankine cycle;

[0050] The circulating working medium (mainly R290, temperature -130℃, pressure 2bar, flow 3000kg / h) in the second stage circulating working medium tank 10 is passed through the second stage throttle valve 11 into the second stage circulating working medium pump 12 (temperature -129℃, pressure 8bar), then into the cylinder liner water heat exchanger 13 to exchange heat and increase temperature (temperature 85℃, pressure 8bar), then into the second stage expander 14 to generate electricity (temperature 39℃, pressure 2bar), then the circulating working medium after generating electricity is passed through the second stage LNG heat exchanger 9 to exchange heat and cool (temperature -130℃, pressure 2bar), and finally into the second stage circulating working medium tank 10 to complete the second stage organic Rankine cycle;

[0051] The flue gas (flue gas flow 130000kg / h, temperature 350℃, pressure 1.4bar) discharged by the engine main engine 15 of the ship is passed through the waste heat recovery device 16 (temperature 140℃ after heat exchange, pressure 1.4bar) and then through the first stage seawater heat exchanger 17 to exchange heat (temperature 40℃ after heat exchange, pressure 1.4bar) and enters the absorption tower 21, the heat transfer medium (mainly heavy fuel oil and other heat transfer fluids with good heat transfer characteristics) in the heat transfer medium tank 18 is passed through the fourth stage throttle valve 19 into the heat transfer medium pump 20, then into the reboiler 25 to exchange heat, and then back to the heat transfer medium tank 18 after being heated by the waste heat recovery device 16;

[0052] The rich liquid (flow 226663kg / h, temperature and pressure 46℃, 1bar) absorbed by the absorption tower 21 is pressurized by the rich liquid pump 22 (temperature 46℃ after pressurization, pressure 2.9bar) and passed through the rich-lean liquid heat exchanger 23, the rich liquid after heat exchange (temperature 122℃ after heat exchange, pressure 2.9bar) is directly passed into the stripping tower 24 to strip CO2. The exhaust gas absorbed by the absorption tower 21 is passed into the multi-effect distillation reverse electrodialysis heat engine 28 to generate electricity. The lean liquid after stripping CO2 is passed through the rich-lean liquid heat exchanger 23 to exchange heat, then cooled by the lean liquid heat exchanger 26, and then mixed with the MEA supplement liquid by the mixer 27 and returned to the absorption tower 21;

[0053] The released carbon dioxide is separated into pure CO2 by separator 29 (temperature 119℃, pressure 3 bar, flow rate 8900 kg / h) and then fed into the third-stage CO2 heat exchanger 30 for heat exchange (temperature 36℃, pressure 3 bar), and then into the first-stage CO2 heat exchanger 7 for further cooling (temperature -69℃, pressure 3 bar), and finally into CO2 storage tank 36.

[0054] The circulating working fluid (mainly R134a, temperature 10℃, pressure 7 bar, flow rate 3000 kg / h) in the third-stage circulating working fluid storage tank 10 is fed into the third-stage circulating working fluid pump 31 (temperature 12℃, pressure 37 bar) through the third-stage throttle valve 32, then into the third-stage CO2 heat exchanger 30 for heat exchange and temperature increase (temperature 96℃, pressure 37 bar), then into the third-stage expander 35 for power generation (temperature 17℃, pressure 7 bar), then into the second-stage seawater heat exchanger 34 for heat exchange and cooling (temperature 10℃, pressure 7 bar), and finally into the third-stage circulating working fluid tank 33 to complete the third-stage organic Rankine cycle;

[0055] The function of the multi-effect distillation reverse electrodialysis heat engine 28 is to realize the power generation utilization of low-grade heat energy below 100℃, i.e., the exhaust gas discharged after absorption by the absorption tower.

[0056] The function of battery 37 is to store the electricity generated by the system and connect it to the user end to meet the ship's power demand.

[0057] In the entire system, the output side of the first-stage expander 8, the second-stage expander 14, the third-stage expander 35, and the multi-effect distillation reverse electrodialysis heat engine 28 are connected to the input side of the storage battery 37, and the output side of the storage battery 37 is connected to the user.

[0058] The power generation of the first-stage expander 8 and the second-stage expander 14 is prioritized to meet the daily needs of users. The power generation of the third-stage expander 35 and the multi-effect distillation reverse electrodialysis heat engine 28 is used as backup energy and connected to the storage battery 37 to achieve energy storage.

[0059] 2. During the ship's acceleration phase, the ship's power requirements increase, thus increasing the LNG demand of the ship's main engine 15. At this time, the control center controls the LNG supply valve 2 to increase the LNG supply flow. With the increase in LNG flow, the cooling capacity of the LNG as a cold source in the first-stage organic Rankine cycle increases, and at the same time, the heat generated by the CO2 released as a heat source in the first-stage organic Rankine cycle also increases. In order to cope with the change in the heat source of the first-stage organic Rankine cycle and to achieve efficient power generation and full liquefaction of CO2, the control center 38 controls the first-stage throttle valve 5 to increase the flow rate of the circulating working fluid out of the first-stage circulating working fluid tank 4.

[0060] With the increase of LNG flow, the cold energy brought by LNG as the cold source in the second stage organic Rankine cycle also increases, and at the same time, the cylinder jacket water can be regarded as a constant temperature heat source due to the huge flow;

[0061] To cope with the increase of cold source heat in the second stage organic Rankine cycle, and realize the full use of LNG cold energy by the second stage organic Rankine cycle, the control center 38 controls the second stage throttle valve 11 to increase the flow of circulating working medium out of the first stage circulating working medium tank 10.

[0062] With the increase of the flow of flue gas discharged by the ship engine main engine 15, the amount of CO2 required to be resolved increases, in order to realize the full capture of CO2 and make full use of the waste heat of flue gas, the control center 38 controls the fourth throttle valve 19 to increase the flow of heat transfer working medium out of the heat transfer working medium tank 18; With the increase of flue gas flow, the flow of exhaust gas after being absorbed by the absorption tower 21 increases, so the power generation of the multi-effect distillation reverse osmosis heat engine 28 increases;

[0063] With the increase of CO2 flow, the heat brought by CO2 as the heat source in the third stage organic Rankine cycle also increases, and at the same time, seawater can be regarded as a constant temperature heat source due to the huge flow. To cope with the increase of heat source heat in the third stage organic Rankine cycle, and realize the full use of CO2 waste heat by the third stage organic Rankine cycle, the control center 38 controls the second stage throttle valve 11 to increase the flow of circulating working medium out of the third stage circulating working medium tank 33.

[0064] When the ship accelerates, the user's power demand is stable and unchanged or decreases, the excess power generated by the first stage expander 8, the second stage expander 14, the third stage expander 35 and the multi-effect distillation reverse osmosis heat engine 28 is stored through the storage battery 37. When the ship accelerates and the user's power demand increases at the same time, the power generation of the first stage expander 8 and the second stage expander 14 is preferentially used to meet the user's demand, and when the power generation is insufficient to meet the user's demand, the power generation of the third stage expander 35 and the multi-effect distillation reverse osmosis heat engine 28 is used as a supplement to meet the user's power demand;

[0065] 3. In the stage of ship deceleration, the power required by the ship is reduced, so the LNG required by the main engine 15 of the ship is reduced, at this time the control center 38 controls the LNG supply valve 2 to reduce the LNG supply flow. With the reduction of LNG flow, the cold source brought by LNG in the first organic Rankine cycle is reduced, at the same time the heat brought by the resolved CO2 as the heat source of the first organic Rankine cycle is also reduced. In order to cope with the change of cold and heat sources in the first organic Rankine cycle, realize the efficient power generation of the first organic Rankine cycle and the full liquefaction of CO2, the control center 38 controls the first throttle valve 5 to reduce the circulation working medium flow from the first circulation working medium tank 4. With the reduction of LNG flow, the cold source brought by LNG in the second organic Rankine cycle is also reduced, at the same time the cylinder sleeve water can be regarded as a constant temperature heat source due to its large flow. In order to cope with the reduction of cold source heat in the second organic Rankine cycle, realize the full use of LNG cold energy in the second organic Rankine cycle, the control center 38 controls the second throttle valve 11 to reduce the circulation working medium flow from the first circulation working medium tank 10.

[0066] With the reduction of the flow of flue gas discharged by the ship's main engine 15, the amount of CO2 required to be resolved is reduced, in order to realize the full capture of CO2 and the full use of waste heat, the control center 38 controls the fourth throttle valve 19 to reduce the heat transfer working medium flow from the heat transfer working medium tank 18. With the reduction of flue gas flow, the exhaust gas flow after being absorbed by the absorption tower 21 is reduced, so the power generation of the multi-effect distillation reverse electrodialysis heat engine 28 is reduced.

[0067] With the reduction of CO2 flow, the heat brought by CO2 as the heat source in the third organic Rankine cycle is also reduced, at the same time the seawater can be regarded as a constant temperature heat source due to its large flow. In order to cope with the reduction of heat source heat in the third organic Rankine cycle, realize the full use of CO2 waste heat in the third organic Rankine cycle, the control center 38 controls the second throttle valve 11 to reduce the circulation working medium flow from the third circulation working medium tank 33.

[0068] When the ship decelerates and the user's power demand is stable and unchanged or increases, the power generated by the first expander 8, the second expander 14, the third expander 35 and the multi-effect distillation reverse electrodialysis heat engine 28 is all supplied to the user through the battery 37, when the power generated at this time is insufficient to meet the user's demand, the stored electric energy of the battery can also be used as energy supplement to meet the user's power demand. When the ship decelerates and the user's power demand is reduced, the power generated by the first expander 8 and the second expander 14 is preferentially used to meet the user's demand, when the power generated at this time is insufficient to meet the user's demand, the power generated by the third expander 35 and the multi-effect distillation reverse electrodialysis heat engine 28 is used as a supplement to meet the user's power demand.

[0069] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A carbon capture and thermal energy cascade utilization system suitable for dynamic operating conditions of LNG ships, characterized in that: It includes an LNG cold energy dynamic utilization unit, a dynamic cryogenic liquefied CO2 storage unit, a ship waste heat dynamic utilization carbon capture and power generation unit, and a control center unit: The LNG cold energy dynamic utilization unit is divided into two paths. One path includes an LNG storage tank, an LNG supply valve, a first-stage LNG heat exchanger, a first-stage working fluid storage tank, a first-stage throttle valve, a first-stage working fluid pump, a first-stage CO2 heat exchanger, and a first-stage expander. The outlet of the LNG storage tank, the LNG supply valve, the cold end inlet of the first-stage LNG heat exchanger, the first-stage working fluid storage tank, the first-stage throttle valve, the inlet of the first-stage working fluid pump, and the cold side inlet of the first-stage CO2 heat exchanger are connected. The cold side outlet of the first-stage CO2 heat exchanger is connected to the inlet of the first-stage expander, and the outlet of the first-stage expander is connected to the hot side inlet of the first-stage LNG heat exchanger. This allows the first-stage working fluid to pass through the first-stage throttle valve, be pressurized by the first-stage working fluid pump, absorb heat and heat up in the first-stage CO2 heat exchanger, perform work in the first-stage expander, and return to the first-stage working fluid storage tank after cooling in the first-stage LNG heat exchanger, thus forming the first-stage organic Rankine cycle. The other path includes a second-stage LNG heat exchanger, a second-stage working fluid storage tank, a second-stage throttle valve, a second-stage working fluid pump, a cylinder-casing water heat exchanger, and a second-stage expander. The cold-side inlet of the second-stage LNG heat exchanger is connected to the cold-side outlet of the first-stage LNG heat exchanger. The hot-side outlet of the second-stage LNG heat exchanger, the second-stage working fluid storage tank, the second-stage throttle valve, the second-stage working fluid pump, and the cold-side inlet of the cylinder-casing water heat exchanger are sequentially connected. The cold-side outlet of the cylinder-casing water heat exchanger is connected to the inlet of the second-stage expander, and the outlet of the second-stage expander is sequentially connected to the hot-side inlet of the second-stage LNG heat exchanger. This allows the second-stage working fluid to pass through the second-stage throttle valve, be pressurized by the second-stage working fluid pump, absorb heat and heat up in the cylinder-casing water heat exchanger, perform work in the second-stage expander, and return to the second-stage working fluid storage tank after cooling in the second-stage LNG heat exchanger, thus forming a second-stage organic Rankine cycle. The ship waste heat dynamic utilization carbon capture power generation unit includes an absorption tower, a rich liquor pump, a lean-rich liquor heat exchanger, a desorption tower, a lean liquor heat exchanger, and a mixer. The bottom outlet of the absorption tower is connected to the inlet of the rich liquor pump, the outlet of the rich liquor pump is connected to the cold-side inlet of the lean-rich liquor heat exchanger, and the cold-side outlet of the lean-rich liquor heat exchanger is connected to the inlet of the desorption tower. The rich liquor from the bottom outlet of the absorption tower enters the rich liquor pump through the rich liquor pump inlet, and the pressurized rich liquor enters the lean-rich liquor heat exchanger through the rich liquor pump outlet and the cold-side inlet of the lean-rich liquor heat exchanger to absorb heat. The heated rich liquor then enters the desorption tower through the cold-side outlet of the lean-rich liquor heat exchanger and the desorption tower inlet to desorb CO2. The bottom outlet of the desorption tower... The system is connected to the hot-side inlet of the lean-rich liquid heat exchanger, and the hot-side outlet of the lean-rich liquid heat exchanger is connected to the lean liquid heat exchanger. The hot-side outlet of the lean liquid heat exchanger is connected to the inlet of the mixer, and the outlet of the mixer is connected to the inlet of the absorption tower. The lean liquid in the desorption tower enters the lean-rich liquid heat exchanger for heat exchange through the bottom outlet of the desorption tower and the hot-side inlet of the lean-rich liquid heat exchanger. After heat exchange, the lean liquid enters the lean liquid heat exchanger for cooling through the hot-side outlet of the lean-rich liquid heat exchanger and the hot-side inlet of the lean liquid heat exchanger. After cooling, the lean liquid enters the mixed gas through the hot-side outlet of the lean liquid heat exchanger and the inlet of the mixer. After the lean liquid is mixed with the MEA makeup liquid, it enters the absorption tower through the outlet of the mixer and the inlet of the absorption tower. The dynamic cryogenic liquefied CO2 storage unit includes a separator, a third-stage CO2 heat exchanger, a third-stage working fluid pump, a third-stage throttle valve, a third-stage working fluid tank, a second-stage seawater heat exchanger, a third-stage expander, and a CO2 storage tank. The separator inlet is connected to the gas outlet above the stripping tower; the separator outlet is connected to the hot-side inlet of the third-stage CO2 heat exchanger, the third-stage CO2 heat exchanger hot-side outlet is connected to the hot-side inlet of the first-stage CO2 heat exchanger, the first-stage CO2 heat exchanger hot-side outlet is connected to the inlet of the CO2 storage tank; the third-stage CO2 heat exchanger cold-side outlet is connected to the inlet of the third-stage expander, the third-stage expander outlet is connected to the hot-side inlet of the second-stage seawater heat exchanger, and the second-stage seawater heat exchanger hot-side outlet... The system consists of a third-stage working fluid storage tank, a third-stage throttling valve, and a third-stage working fluid pump connected in sequence. The outlet of the third-stage working fluid pump is connected to the hot-side inlet of the third-stage CO2 heat exchanger. The pure CO2 obtained from the separator passes through the third-stage CO2 heat exchanger and is stored in the CO2 storage tank after being cooled by the first-stage CO2 heat exchanger. The third-stage working fluid passes through the third-stage throttling valve, is pressurized by the third-stage working fluid pump, absorbs heat and heats up in the third-stage CO2 heat exchanger, performs work in the third-stage expander, and returns to the third-stage working fluid storage tank after being cooled by the second-stage seawater heat exchanger, thus forming a third-stage organic Rankine cycle. The control center unit includes a control center; the control center is electrically connected to the LNG supply valve, the first-stage throttle valve, the second-stage throttle valve, and the third-stage throttle valve, respectively.

2. The carbon capture and thermal energy cascade utilization system for LNG ships under dynamic operating conditions according to claim 1, characterized in that: The first and second stage working fluids are R290, and the third stage working fluid is R134a. All three stages are used as refrigerants.

3. The carbon capture and thermal energy cascade utilization system for LNG ships under dynamic operating conditions according to claim 1, characterized in that: It also includes a marine main engine combustion unit, which includes an engine main unit. The LNG in the LNG storage tank is vaporized into natural gas through pipelines, passing through an LNG supply valve, a first-stage LNG heat exchanger, and a second-stage LNG heat exchanger. This natural gas is then introduced into the marine engine main unit for combustion and heat generation of the natural gas in the engine main unit.

4. The carbon capture and thermal energy cascade utilization system for LNG ships under dynamic operating conditions according to claim 3, characterized in that: The ship's waste heat dynamic utilization carbon capture power generation unit includes a waste heat recovery device, a first-stage seawater heat exchanger, a heat transfer working fluid tank, a fourth-stage throttling valve, a heat transfer working fluid pump, and a multi-effect distillation reverse electrodialysis heat engine. One end of the main engine is connected to the hot-side inlet of the waste heat recovery device, and the hot-side outlet of the waste heat recovery device is connected to the hot-side inlet of the first-stage seawater heat exchanger. The hot-side outlet of the first-stage seawater heat exchanger is connected to the outlet of the absorption tower. After combustion, the exhaust gas from the main engine enters the waste heat recovery device through its hot-side inlet for heat exchange. The heat-exchanged exhaust gas then enters the first-stage seawater heat exchanger through its hot-side outlet for cooling. Finally, the cooled exhaust gas enters the absorption tower through the hot-side outlet of the first-stage seawater heat exchanger. The cold-side outlet of the flue gas waste heat recovery device is connected to the inlet of the heat transfer medium tank. The outlet of the heat transfer medium tank, the fourth-stage throttling valve, and the inlet of the heat transfer medium pump are connected. The outlet of the heat transfer medium pump is connected to the hot-side inlet of the reboiler. The hot-side outlet of the reboiler is connected to the cold-side inlet of the flue gas waste heat recovery device. The heat transfer medium enters the hot side of the reboiler for heat exchange after passing through the fourth-stage throttling valve and the heat transfer medium pump. After heat exchange, the heat transfer medium enters the flue gas waste heat recovery device through the hot-side outlet of the reboiler and the cold-side inlet of the flue gas waste heat recovery device. The heated heat transfer medium enters the heat transfer medium tank through the cold-side outlet of the flue gas waste heat recovery device and the inlet of the heat transfer medium tank, completing the first stage of waste heat recovery from the flue gas. The cold-side outlet of the reboiler is connected to the side wall of the desorption tower, and the bottom of the desorption tower is connected to the cold-side inlet of the reboiler. The top of the absorption tower is connected to the inlet of a multi-effect distillation reverse electrodialysis heat engine to complete the second stage of flue gas waste heat recovery, and the outlet of the multi-effect distillation reverse electrodialysis heat engine is connected to the atmosphere.

5. The carbon capture and thermal energy cascade utilization system for LNG ships under dynamic operating conditions according to claim 4, characterized in that: The control center is also electrically connected to the fourth-stage throttle valve.

6. The carbon capture and thermal energy cascade utilization system for LNG ship dynamic operating conditions according to claim 4, characterized in that: It also includes a ship power supply unit, which includes a battery; the input end of the battery is electrically connected to the input side of the first-stage expander, the second-stage expander, the multi-effect distillation reverse electrodialysis heat engine, and the third-stage expander, respectively; the output side of the battery is connected to the ship user's demand side.

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