Equipment for generating power and treating BOG (Boil Off Gas) by utilizing LNG (Liquefied Natural Gas) cold energy and near-zero emission method

Abstract

The invention relates to equipment for power generation and BOG treatment by using LNG cold energy and a near-zero emission method, and the equipment combines a BOG treatment system, a gas turbine exhaust carbon dioxide capture system, an LNG cold energy power generation system and a BOG gas turbine power generation system, so that the complementary energy of an LNG receiving station is cooperatively recovered; the problem of energy waste caused by large BOG load fluctuation quantity in the prior art is solved, and the energy utilization rate of the LNG receiving station is increased; according to the difference of the output of the LNG receiving station and the BOG output, the equipment is provided with a high-pressure compression process and a re-condensation liquefaction process to cooperatively recover BOG, meanwhile, flue gas waste heat generated after BOG combustion power generation is used for heating heat conduction oil, the heat conduction oil is used for providing a heat source for the LNG cold energy power generation system, the efficiency of the cold energy power generation system is improved, and the energy consumption of the cold energy power generation system is reduced. And meanwhile, the problem of carbon emission of discharged tail gas is solved by utilizing an efficient carbon dioxide trapping technology, so that the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy utilization, and in particular relates to a device for generating electricity and treating BOG using cold energy of LNG and a near-zero emission method. Background Art

[0002] Natural gas is an important energy source for achieving diversified and high-quality energy supply. With the rapid development of the economy, the gap between domestic natural gas demand and supply is getting bigger and bigger. Accelerating the development of imported liquefied natural gas (LNG) is a powerful measure to improve the current energy structure and development environment. The construction and development of LNG receiving stations and improving the storage and gasification capacity of LNG receiving stations are inevitable trends for future development.

[0003] In the storage tanks of the receiving station, a large amount of boil-off gas (BOG) will be generated due to system heat leakage, energy transfer of power equipment, unloading and external transmission. If the generated BOG is not handled in time, it may cause overpressure of the storage tanks and pipelines, resulting in production accidents. Generally, the daily BOG ratio of above-ground storage tanks is 0.05%, and that of underground storage tanks is about 0.1%. The BOG treatment process of the LNG receiving station is usually divided into a high-pressure compression process and a recondensation liquefaction process. In the high-pressure compression process, BOG enters the compressor for initial compression, and the compressed gas is re-pressurized by the booster compressor. After reaching the external transmission pressure standard, it is combined with the natural gas in the external transmission pipeline and transported to downstream users. The operation is simple, the power consumption is high, and it can be used when the external transmission volume is low; in the recondensation liquefaction process, BOG enters the recondenser through the compressor and is mixed with the LNG separated from the low-pressure output main pipe at a ratio of 1:9 for heat exchange, and the BOG is liquefied into LNG, and then enters the vaporizer through a high-pressure pump for gasification and external transmission. The gasification process can be combined with the utilization of LNG cold energy, which is economical and energy-saving, with high processing efficiency, and is suitable for working conditions with high external transmission volume.

[0004] The recondenser is crucial in the recondensation liquefaction process. It not only liquefies BOG, but also serves as the inlet buffer container of the high-pressure pump, and the liquid level inside it can meet the requirements of the high-pressure pump inlet NPSH value. The recondenser consists of two parts, the upper part is the feed tower, BOG and LNG enter from the top of the recondenser for heat exchange, and BOG is liquefied; the lower part serves as a buffer tank for the high-pressure pump. The recondenser is equipped with a flow ratio control system, which controls the LNG flow entering the recondenser according to the flow of BOG to ensure that the LNG entering the high-pressure pump is in a supercooled state, and at the same time ensure that the high-pressure pump does not cavitation.

[0005] The name is a system for the combined utilization of LNG cold energy and BOG combustion energy and a near-zero emission method. The high-temperature steam generated by BOG combustion is used to generate electricity through a generator. Part of the exhaust steam after power generation is used to heat the working fluid after LNG cooling, and the other part of the exhaust steam provides heat for the heating subsystem, thereby achieving the purpose of improving the power generation efficiency of the system. Limited by the load range of the BOG gas turbine, the flexibility is low. When the BOG load of the LNG receiving station fluctuates greatly, it will exceed the load range of the BOG gas turbine, and the system cannot handle it well, resulting in energy waste.

[0006] Therefore, it is urgent to develop a device that uses an effective process to recover LNG cold energy and BOG at the receiving station, overcome the energy waste problem caused by large BOG load fluctuations and poor handling, and improve energy utilization. Summary of the invention

[0007] In view of at least one of the problems in the above-mentioned prior art, the purpose of the present invention is to provide a device and a near-zero emission method utilizing LNG cold energy for power generation and BOG treatment, combining a BOG treatment system, a gas turbine exhaust carbon dioxide capture system, an LNG cold energy power generation system and a BOG gas turbine power generation system to achieve coordinated recovery of surplus energy at the LNG receiving station, thereby overcoming the energy waste problem caused by the large BOG load fluctuation in the prior art and improving the energy utilization rate of the LNG receiving station.

[0008] To achieve the above object, the present invention adopts the following technical solutions: An apparatus for generating electricity and treating BOG using LNG cold energy, comprising a BOG treatment system, a BOG gas turbine power generation system, a gas turbine exhaust carbon dioxide capture system and an LNG cold energy power generation system which are interconnected; The BOG processing system recovers BOG and separates LNG by means of multi-stage compression, inter-stage cooling and recondensation; The BOG gas turbine power generation system receives part of the BOG from the BOG processing system as fuel, and the medium-temperature mixed flue gas generated by the BOG gas turbine power generation system provides heat for the LNG cold energy power generation system by heating the heat transfer oil; The gas turbine exhaust carbon dioxide capture system captures carbon dioxide gas from the BOG gas turbine power generation system and transports LNG from the BOG processing system to the LNG cold energy power generation system; The LNG cold energy power generation system gasifies LNG by using the waste heat of the heat transfer oil, and the gasified LNG and the BOG from the BOG processing system are combined into a third mixer for external transmission.

[0009] Preferably, the BOG processing system comprises an LNG storage tank, a BOG compressor, a first splitter, a first multi-stage compression interstage cooling device, a BOG recondenser, a low-pressure output pump, a second splitter, a pressure regulating valve and a first mixer. The BOG and LNG in the LNG storage tank are respectively delivered to the first splitter and the second splitter by the BOG compressor and the low-pressure delivery pump; the first splitter divides the BOG into three streams for output, the first stream BOG is delivered to the first multi-stage compression interstage cooling device for connection, and the third stream BOG is delivered to the recondenser for connection; the second splitter divides the LNG into two streams, the first stream LNG is delivered to the BOG recondenser, and the second stream LNG passes through the pressure regulating valve and merges with the outlet stream LNG of the BOG recondenser into the first mixer.

[0010] Preferably, the BOG gas turbine power generation system comprises an air separation device, a second mixer, a compressor, a regenerator, a combustion chamber, an expansion generator and a thermal oil heater; the combustion chamber is connected to the first flow divider, the second stream BOG is transported to the combustion chamber to be used as fuel, the high-temperature mixed flue gas generated by the combustion chamber is transported to the expansion generator, and the medium-temperature flue gas generated by the expansion generator sequentially enters the regenerator and the thermal oil heater for heat exchange; the high-purity oxygen separated from the air separation device and the diluent are merged into the second mixer, and the mixed gas of the high-purity oxygen and the diluent enters the combustion chamber through the compressor and the regenerator to assist combustion; The second mixer is connected to the compressor, the regenerator, the combustion chamber, the expansion generator and the thermal oil heater in sequence.

[0011] Preferably, the gas turbine exhaust carbon dioxide capture system includes a water removal device and a second multi-stage compression interstage cooling device, the upstream of the second multi-stage compression interstage cooling device is connected to the first mixer, and the downstream is connected to the secondary bottom cycle condenser of the LNG cold energy power generation system; the upstream of the water removal device is connected to the thermal oil heater, and the downstream is connected to the second multi-stage compression interstage cooling device.

[0012] Preferably, an LNG high-pressure output pump is provided between the upstream of the second multi-stage compression inter-stage cooling device and the first mixer.

[0013] Preferably, the LNG cold energy power generation system includes a primary power generation cycle device, a secondary power generation cycle device, a thermal oil booster pump, an LNG vaporizer and the third mixer, the thermal oil heater is connected to the primary power generation cycle device, the secondary power generation cycle device, the thermal oil booster pump and the LNG vaporizer in sequence; the second multi-stage compression interstage cooling device is connected to the secondary power generation cycle device, the primary power generation cycle device and the LNG vaporizer in sequence; the LNG vaporizer is connected to the third mixer.

[0014] Preferably, the first-stage power generation cycle device includes a first-stage top circulation evaporator, a first-stage top circulation expansion generator, a first heat exchanger, a first-stage top circulation working fluid pump, a first-stage bottom circulation expansion generator, a first-stage bottom circulation condenser and a first-stage bottom circulation working fluid pump. The first-stage top circulation evaporator, the first-stage top circulation expansion generator, the first heat exchanger and the first-stage top circulation working fluid pump are connected in a cycle in sequence, and the first-stage top circulation evaporator is connected to the thermal oil heater; the first heat exchanger, the first-stage bottom circulation expansion generator, the first-stage bottom circulation condenser and the first-stage bottom circulation working fluid pump are connected in a cycle in sequence; the first-stage bottom circulation condenser is connected to the LNG gasifier.

[0015] Preferably, the secondary power generation cycle device includes a secondary top cycle evaporator, a secondary top cycle expansion generator, a second heat exchanger, a secondary top cycle working fluid pump, a secondary bottom cycle expansion generator, a secondary bottom cycle condenser and a secondary bottom cycle working fluid pump. The secondary top cycle evaporator, the secondary top cycle expansion generator, the second heat exchanger and the secondary top cycle working fluid pump are connected in a cycle in sequence, and the secondary top cycle evaporator is respectively connected to the primary top cycle evaporator and the thermal oil booster pump; the second heat exchanger, the secondary bottom cycle expansion generator, the secondary bottom cycle condenser and the secondary bottom cycle working fluid pump are connected in a cycle in sequence, and the secondary bottom cycle condenser is respectively connected to the second multi-stage compression interstage cooling device and the primary bottom cycle condenser.

[0016] A near-zero emission method for power generation and BOG treatment using LNG cold energy is implemented based on any of the above-mentioned devices for power generation and BOG treatment using LNG cold energy, comprising the following steps: When the LNG output volume is large, the BOG compressor and the low-pressure output pump are operated at the same time, and the third stream BOG and the first stream LNG enter the recondenser, and the BOG is treated by the cold energy of LNG. After the BOG is condensed, it is merged with the second stream LNG into the first mixer and then enters the high-pressure output pump; Running the high-pressure output pump to allow the LNG outputted from the first mixer to enter a second multi-stage compression interstage cooling device, and using cold energy of the LNG entering the second multi-stage compression interstage cooling device to capture carbon dioxide in the second multi-stage compression interstage cooling device; The high-pressure LNG outputted from the second multi-stage compression interstage cooling device sequentially enters the secondary bottom cycle condenser and the primary bottom cycle condenser to release cold energy and condense the working fluid in the primary power generation cycle device and the secondary power generation cycle device; The high-pressure LNG output from the primary bottom cycle condenser enters the LNG vaporizer, and the LNG is vaporized by the waste heat of the heat transfer oil in the LNG vaporizer. After the LNG is vaporized to ambient temperature, the vaporized LNG and the BOG at the outlet of the first multi-stage compression interstage cooling device are merged into the third mixer for external transmission.

[0017] Preferably, in the step of capturing carbon dioxide in the second multi-stage compression interstage cooling device by utilizing the cold energy of the LNG entering the second multi-stage compression interstage cooling device, the carbon dioxide is generated by the BOG gas turbine power generation system and input into the second multi-stage compression interstage cooling device through a water removal device.

[0018] The present invention adopts the above technical solution, which has the following advantages: 1. The equipment for utilizing LNG cold energy for power generation and BOG treatment provided by the present invention combines a BOG treatment system, a gas turbine exhaust carbon dioxide capture system, an LNG cold energy power generation system and a BOG gas turbine power generation system to achieve coordinated recovery of surplus energy at the LNG receiving station, thereby overcoming the energy waste problem caused by large BOG load fluctuations in the prior art and improving the energy utilization rate of the LNG receiving station.

[0019] 2. The equipment for power generation and BOG treatment using LNG cold energy provided by the present invention improves the problem of unstable and large fluctuations in BOG generation in LNG storage tanks at LNG receiving stations, making recovery difficult, improves the efficiency of LNG cold energy power generation and the comprehensive energy utilization rate of the receiving station, and enables the system to achieve energy self-sufficiency.

[0020] 3. The equipment for utilizing LNG cold energy power generation and BOG treatment provided by the present invention utilizes the waste heat of the medium-temperature flue gas after BOG combustion power generation to heat the heat transfer oil to provide a heat source for the LNG cold energy power generation cycle, thereby realizing LNG cold energy power generation while reducing the waste of BOG.

[0021] 4. The equipment for power generation using LNG cold energy and BOG treatment provided by the present invention, the BOG treatment system, the gas turbine exhaust carbon dioxide capture system and the LNG cold energy power generation system, enable the cold energy of LNG gasification and the heat energy of the CO2 capture process to be used in coordination.

[0022] 5. The near-zero emission method for utilizing LNG cold energy for power generation and BOG treatment provided by the present invention, according to the difference in the external transmission volume of the LNG receiving station and the amount of BOG generated, the equipment is respectively provided with a high-pressure compression process and a recondensation liquefaction process for collaboratively recovering BOG, and at the same time, the waste heat of the flue gas after BOG combustion power generation is used to heat the heat transfer oil, and the heat transfer oil is used to provide a heat source for the LNG cold energy power generation system, thereby improving the efficiency of the cold energy power generation system, and at the same time, the efficient carbon dioxide capture technology is used to solve the problem of carbon emissions from exhaust gas, thereby achieving the purpose of energy conservation and emission reduction; it can realize the efficient complementary utilization of BOG and LNG cold energy, significantly improve the thermal efficiency and power generation efficiency of the equipment, and has the advantages of reasonable structure, energy saving and high efficiency, and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a connection diagram of equipment for power generation using LNG cold energy and BOG treatment provided in the first embodiment of the present invention.

[0024] Figure 2 It is a flowchart of the steps of the near-zero emission method for power generation using LNG cold energy and BOG treatment provided by this embodiment of the present invention.

[0025] Markings in the accompanying drawings: 1 is an LNG storage tank, 2 is a BOG compressor, 3 is a first flow divider, 4 is a first multi-stage compression interstage cooling device, 5 is a BOG recondenser, 6 is a low-pressure output pump, 7 is a second flow divider, 8 is a pressure regulating valve, 9 is a first mixer, 10 is a high-pressure output pump, 11 is a second multi-stage compression interstage cooling device, 12 is a secondary bottom cycle condenser, 13 is a primary bottom cycle condenser, 14 is an air separation device, 15 is a second mixer, 16 is a compressor, 17 is a regenerator, 18 is a combustion chamber, 19 is an expansion generator, and 20 is a heat transfer oil heater. 21 is a water removal device, 22 is a primary top circulation evaporator, 23 is a secondary top circulation evaporator, 24 is a first heat exchanger, 25 is a second heat exchanger, 26 is a primary top circulation expansion generator, 27 is a secondary top circulation expansion generator, 28 is a primary top circulation working fluid pump, 29 is a secondary top circulation working fluid pump, 30 is a primary bottom circulation expansion generator, 31 is a primary bottom circulation working fluid pump, 32 is a secondary bottom circulation expansion generator, 33 is a secondary bottom circulation working fluid pump, 34 is a heat transfer oil booster pump, 35 is an LNG vaporizer and 36 is a third mixer. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "front", "backward", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. The arrows in the accompanying drawings represent the flow direction of the substance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "assembly", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] The present invention provides a device and a near-zero emission method for generating electricity using LNG cold energy and treating BOG, which combines a BOG treatment system, a gas turbine exhaust carbon dioxide capture system, an LNG cold energy power generation system and a BOG gas turbine power generation system to achieve coordinated recovery of surplus energy of an LNG receiving station, overcome the energy waste problem caused by large BOG load fluctuation in the prior art, and improve the energy utilization rate of the LNG receiving station; according to the difference between the external output volume of the LNG receiving station and the BOG generation volume, the device is respectively provided with a high-pressure compression process and a recondensation liquefaction process to coordinately recover BOG, and at the same time, utilizes the flue gas waste heat after BOG combustion power generation to heat the heat transfer oil, utilizes the heat transfer oil to provide a heat source for the LNG cold energy power generation system, improves the efficiency of the cold energy power generation system, and utilizes the efficient carbon dioxide capture technology to solve the problem of carbon emission of exhaust gas, thereby achieving the purpose of energy saving and emission reduction; the efficient complementary utilization of BOG and LNG cold energy can be achieved, and the thermal efficiency and power generation efficiency of the equipment are significantly improved, and the device has the advantages of reasonable structure, energy saving and high efficiency, and strong practicality. The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] Example 1 Please refer to Figure 1 , the present embodiment provides a device for power generation and BOG treatment using LNG cold energy, including a BOG treatment system, a BOG gas turbine power generation system, a gas turbine exhaust carbon dioxide capture system and an LNG cold energy power generation system connected to each other; The BOG treatment system recovers BOG and separates LNG through multi-stage compression, inter-stage cooling and recondensation; The BOG gas turbine power generation system receives part of the BOG from the BOG processing system as fuel. The medium-temperature mixed flue gas generated by the BOG gas turbine power generation system heats the heat transfer oil to provide heat for the LNG cold energy power generation system. The gas turbine exhaust carbon dioxide capture system captures carbon dioxide gas from the BOG gas turbine power generation system and transports LNG from the BOG processing system to the LNG cold energy power generation system; The LNG cold energy power generation system gasifies LNG by using the waste heat of the heat transfer oil, and the gasified LNG and the BOG from the BOG treatment system are combined into the third mixer 36 for external transmission.

[0031] The BOG processing system includes an LNG storage tank 1, a BOG compressor 2, a first flow divider 3, a first multi-stage compression interstage cooling device 4, a BOG recondenser 5, a low-pressure output pump 6, a second flow divider 7, a pressure regulating valve 8 and a first mixer 9. The upper end of the LNG storage tank 1 is connected to the BOG compressor 2, the first flow divider 3 and the first multi-stage compression interstage cooling device 4 in sequence; the lower end of the LNG storage tank 1 is connected to the low-pressure output pump 6, the second flow divider 7, the pressure regulating valve 8 and the mixer 9 in sequence, and the BOG recondenser 5 is connected to the first flow divider 3 and the second flow divider 7 respectively; The BOG and LNG are respectively delivered to the first splitter 3 and the second splitter 7 by the BOG compressor 2 and the low-pressure delivery pump 6; the first splitter 3 divides the BOG in the BOG output main pipe into three streams for output, the first stream BOG is delivered to the first multi-stage compression interstage cooling device 4 for connection, and the third stream BOG is delivered to the recondenser 5 for connection; the second splitter 7 divides the LNG in the LNG low-pressure output main pipe into two streams, the first stream LNG is delivered to the BOG recondenser 5, and the second stream LNG passes through the pressure regulating valve 8 and merges with the outlet stream LNG of the BOG recondenser 5 into the first mixer 9.

[0032] Specifically, the LNG in the LNG storage tank 1 at -164 to -161°C and 1.1 bar is pressurized to 0.8 to 1.2 MPa by the low-pressure output pump 6 at the bottom of the storage tank and then divided into two streams of LNG, one of which enters the BOG recondenser 5 to condense the BOG, and the other enters the LNG high-pressure output pump 10 after being mixed with the LNG in the BOG recondenser 5; the BOG in the storage tank at -164 to -161°C and 1.1 bar is pressurized to 0.8 to 1.2 MPa by the BOG compressor 2 and then divided into three streams, the first stream enters the first multi-stage compression interstage cooling device 4 to be pressurized and heated to 5 to 15°C and 7 MPa for external transmission, the second stream enters the combustion chamber 18 of the BOG gas turbine power generation system as fuel, and the third stream enters the BOG recondenser 5 to be cooled to -158 to -155°C by the LNG.

[0033] The BOG processing system includes a high-pressure compression process and a recondensation liquefaction process. When the external output is low, only the high-pressure compression process can be enabled. When the external output is high, the two processes can be operated simultaneously, making full use of the cold energy of LNG and reducing the power consumption of the first multi-stage compression interstage cooling device 4. The two methods of processing BOG solve the problem of large BOG load fluctuations.

[0034] LNG is liquefied natural gas, the main component of which is methane. LNG is colorless, odorless, non-toxic and non-corrosive. It produces less carbon dioxide when burned than other fossil fuels, causing a lower greenhouse effect. It is a clean, environmentally friendly, high-quality energy source. Its volume is about 1 / 600 of the volume of the same amount of gaseous natural gas. During the liquefaction process of natural gas, about 850kW•h / t of electricity is consumed. When LNG at normal pressure is vaporized and heated from -162°C to 5°C, about 230kW•h / t of cold energy is released; BOG is liquid natural gas boil-off gas. BOG is produced by the evaporation of LNG in the LNG storage tank and gathers at the upper part of the LNG storage tank 1. In the equipment, BOG is extracted from the LNG storage tank 1 by the BOG compressor 2; among them, the low-pressure output pump 6 is a submersible pump, which transports the LNG stored in the LNG storage tank 1.

[0035] The BOG gas turbine power generation system includes an air separation device 14, a second mixer 15, a compressor 16, a regenerator 17, a combustion chamber 18, an expansion generator 19 and a thermal oil heater 20; the air separation device 14 is connected to the second mixer 15, the compressor 16, the regenerator 17 and the combustion chamber 18 in sequence, the combustion chamber 18 is connected to the expansion generator 19, the regenerator 17 and the thermal oil heater 20 in sequence; the combustion chamber 18 is connected to the first splitter 3, the second stream BOG is transported to the combustion chamber 18 as fuel, the oxygen-rich gas is used as the combustion-supporting gas, and part of the carbon dioxide is added to prevent the temperature in the combustion chamber 18 from being too high as a diluent; the high-temperature mixed flue gas generated in the combustion chamber 18 is transported to the expansion generator 19 to be used as a heat source for power generation, and the high-temperature mixed flue gas passes through the medium-temperature flue gas generated by the expansion generator 19 and enters the regenerator 17 and the thermal oil heater 20 in turn for heat exchange; the air separation device 14 is used to separate oxygen from the air, and the high-purity oxygen and diluent carbon dioxide separated in the air separation device 14 are merged into the second mixer 15, and the mixed gas of high-purity oxygen and diluent carbon dioxide enters the combustion chamber 18 through the compressor 16 and the regenerator 17, and the high-purity oxygen and diluent carbon dioxide are sent to the combustion chamber 18 to assist combustion.

[0036] Among them, the high-temperature mixed flue gas generated by BOG combustion is used for expansion generator 19 to generate electricity. The medium-temperature flue gas discharged by expansion generator 19 is heated by thermal oil heater 20 to heat the thermal oil. The heated thermal oil is used as the heat source of the LNG cold energy power generation system. The electricity generated by the expansion generator 19 can be used for the power supply of the LNG receiving station, and can also be connected to the power grid for sale.

[0037] The temperature of the medium-temperature flue gas of the BOG gas turbine power generation system after passing through the regenerator 17 is 300-400°C, and the temperature to which the heat transfer oil is heated is 200-320°C.

[0038] The gas turbine exhaust carbon dioxide capture system includes a dehydration device 21 and a second multi-stage compression interstage cooling device 11. The upstream of the second multi-stage compression interstage cooling device 11 is connected to the first mixer 9, and an LNG high-pressure output pump 10 is arranged between the upstream of the second multi-stage compression interstage cooling device 11 and the first mixer 9. The inlet side of the upstream of the second multi-stage compression interstage cooling device 11 is connected to the NG high-pressure output pump 10, and the outlet side of the downstream is connected to the secondary bottom cycle condenser 12 of the LNG cold energy power generation system; the upstream of the dehydration device 21 is connected to the thermal oil heater 20, and the mixed flue gas passing through the thermal oil heater 20 is transported to the dehydration device 21, and the downstream is connected to the second multi-stage compression interstage cooling device 11. The dehydration device 21 is externally cooled by water.

[0039] The equipment reaches near-zero emissions through CO2 capture from gas turbine exhaust. The CO2 capture methods of gas turbine exhaust CO2 capture system are divided into absorption method and cryogenic method. The absorption method can use chemical solvents such as ethanolamine solution to capture the CO2 in the mixed flue gas transmitted from the BOG gas turbine power generation system. The cryogenic method uses condensation to remove H2 in the flue gas in turn. 2 O and carbon dioxide, in order to avoid low-temperature freezing in the secondary bottom cycle condenser 12, the exhaust gas temperature in the dehydration device 21 and the second multi-stage compression inter-stage cooling device 11 should be higher than H 2 The triple point temperature of O and CO2, the flue gas pressure should be higher than the triple point pressure of CO2, and the cold energy of LNG is used to condense H 2 O and carbon dioxide, the low temperature method does not require an absorption tower and chemical solvents, saving the cost of absorption tower equipment and absorption solvents.

[0040] The gas turbine exhaust carbon dioxide capture system adopts multi-stage compression and inter-stage cooling to capture. The multi-stage compression and inter-stage cooling process can achieve efficient carbon dioxide recovery under the premise of low power consumption, and can make full use of LNG cold energy. The cooling process utilizes high-grade LNG cold energy to reduce the power consumption of the device.

[0041] Among them, the captured by-product carbon dioxide can be used in a carbon dioxide refrigeration system or a carbon dioxide power generation system, and the compression heat generated by the second multi-stage compression interstage cooling device 11 can be used as a heat source for other industrial applications. The LNG that is used to liquefy carbon dioxide and releases part of the cold energy enters the downstream as a cold source for the LNG cold energy power generation system.

[0042] The LNG cold energy power generation system includes a primary power generation cycle device, a secondary power generation cycle device, a thermal oil booster pump 34, an LNG vaporizer 35 and a third mixer 36. The thermal oil heater 20 is connected to the primary power generation cycle device, the secondary power generation cycle device, the thermal oil booster pump 34 and the LNG vaporizer 35 in sequence; the second multi-stage compression interstage cooling device 11 is connected to the secondary power generation cycle device, the primary power generation cycle device and the LNG vaporizer 35 in sequence; the LNG vaporizer 35 is connected to the third mixer 36.

[0043] The primary power generation cycle device includes a primary top circulation evaporator 22, a primary top circulation expansion generator 26, a first heat exchanger 24, a primary top circulation working fluid pump 28, a primary bottom circulation expansion generator 30, a primary bottom circulation condenser 13 and a primary bottom circulation working fluid pump 31. The primary top circulation evaporator 22, the primary top circulation expansion generator 26, the first heat exchanger 24 and the primary top circulation working fluid pump 28 are connected in a cycle in sequence. The primary top circulation evaporator 22 is connected to the thermal oil heater 20; the first heat exchanger 24, the primary bottom circulation expansion generator 30, the primary bottom circulation condenser 13 and the primary bottom circulation working fluid pump 31 are connected in a cycle in sequence; the primary bottom circulation condenser 13 is connected to the LNG vaporizer 35.

[0044] The secondary power generation cycle device includes a secondary top cycle evaporator 23, a secondary top cycle expansion generator 27, a second heat exchanger 25, a secondary top cycle working fluid pump 29, a secondary bottom cycle expansion generator 32, a secondary bottom cycle condenser 12 and a secondary bottom cycle working fluid pump 33. The secondary top cycle evaporator 23, the secondary top cycle expansion generator 27, the second heat exchanger 25 and the secondary top cycle working fluid pump 29 are connected in a circular manner in sequence. The secondary top cycle evaporator 23 is respectively connected to the primary top cycle evaporator 22 and the thermal oil booster pump 34; the second heat exchanger 25, the secondary bottom cycle expansion generator 32, the secondary bottom cycle condenser 12 and the secondary bottom cycle working fluid pump 33 are connected in a circular manner in sequence, and the secondary bottom cycle condenser 12 is respectively connected to the second multi-stage compression interstage cooling device 11 and the primary bottom cycle condenser 13.

[0045] Specifically, the outlet of the first-stage top cycle expansion generator 26 is connected to the hot fluid side inlet of the first heat exchanger 24, the outlet of the second-stage top cycle expansion generator 27 is connected to the hot fluid side inlet of the second heat exchanger 25, the outlet of the first-stage bottom cycle working fluid pump 31 is connected to the cold fluid side inlet of the first heat exchanger 24, and the second-stage bottom cycle working fluid pump 33 is connected to the cold fluid side inlet of the second heat exchanger 25; The heat transfer oil heated by the heat transfer oil heater 20 is used as the heat source of the top cycle of the primary power generation cycle device and the secondary power generation cycle device, and the cold source of the top cycle is used as the heat source of the bottom cycle; the primary bottom cycle condenser 13 is connected to the LNG vaporizer 35, and the waste heat of the heat transfer oil is used to vaporize the LNG. The vaporized LNG and the BOG that have passed through the first multi-stage compression interstage cooling device 4 are merged into the third mixer 36 for external transmission.

[0046] There are circulating working fluids in the primary power generation cycle device and the secondary power generation cycle device. The LNG cold energy power generation system transfers the cold energy of LNG to the working fluid after power generation to liquefy the working fluid and heat the LNG to -10°C. After absorbing the heat energy, the LNG is close to the external transmission condition.

[0047] The working fluid is not limited to water, isopentane, propane, tetrafluoroethane and ethane.

[0048] The outlet side of the third mixer 36 is directly connected to the long-distance pipeline, and the mixed gas of the gasified LNG and the BOG passing through the first multi-stage compression inter-stage cooling device 4 is transported out.

[0049] Example 2 Please refer to Figure 2 The near-zero emission method for power generation using LNG cold energy and BOG treatment provided in this embodiment is completed using the equipment for power generation using LNG cold energy and BOG treatment in Example 1, and includes the following steps: S01, when the LNG output volume is large, the BOG compressor 2 and the low-pressure output pump 6 are operated simultaneously, the third stream BOG and the first stream LNG enter the recondenser 5, and the BOG is treated by the cold energy of LNG. After being condensed, the BOG and the second stream LNG are merged into the first mixer 9 and then enter the high-pressure output pump 10; S02, operating the high-pressure output pump 10, so that the LNG output from the first mixer 9 enters the second multi-stage compression interstage cooling device 11, and using the cold energy of the LNG entering the second multi-stage compression interstage cooling device 11 to capture the carbon dioxide in the second multi-stage compression interstage cooling device 11; S03, the high-pressure LNG outputted from the second multi-stage compression interstage cooling device 11 enters the secondary bottom cycle condenser 12 and the primary bottom cycle condenser 13 in sequence to release cold energy, and condense the working fluid in the primary power generation cycle device and the secondary power generation cycle device; S04, the high-pressure LNG output from the primary bottom cycle condenser 13 enters the LNG vaporizer 35, and the LNG is vaporized by the waste heat of the heat transfer oil in the LNG vaporizer 35. After the LNG is vaporized to the ambient temperature at this stage, the vaporized LNG and the BOG at the outlet of the first multi-stage compression interstage cooling device 4 are merged into the third mixer 36 for external transmission. Specifically, in step S01, this stage uses the cold energy of the first temperature range of LNG (-160°C to -147°C); in step S02, this stage uses the cold energy of the second temperature range of LNG (-147°C to -90°C); in step S03, this stage uses the cold energy of the third temperature range of LNG (-90°C to -10°C); in step S04, the ambient temperature is 15°C. to 20°C.

[0050] In the step of capturing carbon dioxide in the second multi-stage compression interstage cooling device 11 by utilizing the cold energy of the LNG entering the second multi-stage compression interstage cooling device 11, carbon dioxide is generated by the BOG gas turbine power generation system and is input into the second multi-stage compression interstage cooling device 11 through the water removal device 21.

[0051] In this example, a LNG receiving station is used as an example. A LNG receiving station supplies 7MPa high-pressure natural gas to downstream high-pressure natural gas users. The LNG uses typical LNG components, and its molar composition is as follows: methane 88.8%, carbon dioxide 6.54%, ethane 3.11%, propane 0.51%, butane 0.054%, isobutane 0.135%, isopentane 0.4%, normal pentane 0.046%, hexane 0.296% and nitrogen 0.109%. The LNG receiving station is equipped with four 160,000 cubic meter LNG storage tanks 1. Taking the boiling point of LNG at normal pressure of -162℃ and the density of 456kg / m3 as an example, assuming that each LNG storage tank 1 is full, the total amount of LNG in each LNG storage tank 1 is 72960t. According to the daily evaporation of the ground LNG storage tank 1 is less than or equal to 0.05%, the amount of boil-off gas generated in the four LNG storage tanks 1 is 6.08t / h. The internal pressure of the LNG storage tank 1 is 0.15MPa, and the output volume of LNG is 150t / h. The BOG at the top of the LNG storage tank 1 is pressurized to 1.2MPa by the BOG compressor 2 and enters the first splitter 3. The first stream BOG at the first split outlet enters the first multi-stage compressor intercooler 4. The flow rate of the first stream BOG is 1t / h. The first multi-stage compressor intercooler 4 pressurizes the BOG by 3MPa, 5MPa and 7MPa respectively and then enters the third mixer 36. The compression heat generated between the stages is cooled by the air cooler between the compressors. The flow rate of the second stream BOG at the outlet of the first splitter 3 is 0.08t / h. The second stream BOG enters the combustion chamber 18 and serves as the fuel of the BOG gas turbine power generation system. The flow rate of the third stream BOG at the outlet of the first splitter 3 is 5 t / h. The third stream BOG enters the BOG recondenser 5 to be prepared for heat exchange and condensation with LNG. The LNG is pressurized to 1.2 MPa by a low-pressure submersible pump and enters the low-pressure output main pipe. The LNG is heated to -158°C and then enters the second splitter 7. The second splitter 7 splits the LNG into a first stream LNG of 50 t / h and a second stream LNG of 100 t / h at a ratio of 1:2. The first stream LNG enters the BOG recondenser 5 to exchange heat with BOG and heat it to -147°C. Assuming that no pressure drop occurs during the recondensation process, the second stream LNG and the LNG at the outlet of the recondenser 5 are combined in the first mixer 9 and then enter the high-pressure output pump 10 after reaching -150°C.

[0052] The second stream BOG and the oxygen-rich gas separated by the air separation device 14 are burned in the combustion chamber 18 to generate high-temperature steam of 700-800°C, which enters the expansion generator 19 to generate electricity. After the steam temperature drops to 300 to 400°C after power generation, it enters the regenerator 17 to complete the complete BOG gas turbine power generation process. The medium-temperature flue gas at the outlet of the regenerator 17 enters the thermal oil heater 20 to heat the thermal oil to 200 to 300°C. The thermal oil enters the LNG cold energy power generation system as a heat source. According to the temperature characteristics of the thermal oil itself, the power generation cycle is divided into two stages. After passing through the first-stage top cycle evaporator 22, the thermal oil is cooled to 150 to 220°C. After passing through the second-stage top cycle evaporator 23, the thermal oil is cooled to 50-90°C. At this time, the thermal energy quality of the thermal oil is relatively low, and it enters the LNG vaporizer 35 to completely vaporize the LNG.

[0053] Thermal oil is a heat transfer oil, which is an organic compound and is normally liquid. It is a high-temperature, low-pressure medium and is commonly used in the chemical and power generation fields to indirectly transfer heat. Compared with the traditional steam boiler system, it is safer during use and has a much lower working pressure than the steam boiler system. In this embodiment, the thermal oil used is biphenyl-biphenyl ether. The biphenyl-biphenyl ether organic heat carrier is a relatively mature heat transfer medium with a maximum operating temperature of 400 ° C and excellent characteristics of high temperature and low pressure. Its components include 26.5% biphenyl and 73.5% biphenyl ether.

[0054] In the LNG cold energy power generation system, the heat transfer oil at 200°C to 300°C enters the hot fluid side of the first-level top circulation evaporator 22 to exchange heat with the water cooled by the first-level bottom circulation organic working fluid. The water is heated by the heat transfer oil to 280°C to 290°C high-temperature water vapor and then enters the first-level top circulation expansion generator 26 to generate electricity; the heat transfer oil with a temperature reduced to 150°C to 220°C enters the hot fluid side of the second-level top circulation evaporator 23 to exchange heat with the organic working fluid cooled by the second-level bottom circulation organic working fluid. The organic working fluid is heated by the heat transfer oil to 150°C to 160°C high-temperature steam and then enters the second-level top circulation expansion generator 27 to generate electricity; the first-level top circulation working fluid enters the first heat exchanger 24 on the hot fluid side to heat the first-level bottom circulation organic working fluid after generating electricity through the expansion generator. The first-level bottom circulation organic working fluid is heated to 80°C to 90°C and then enters the first-level bottom circulation expansion generator 30 to generate electricity. The organic working fluid at the outlet of the expansion generator enters the hot fluid side of the first-level bottom circulation condenser 13 to absorb 0°C to 40°C LNG cold energy; the secondary top cycle organic working fluid enters the second heat exchanger 25 on the hot fluid side to provide heat for the secondary bottom cycle organic working fluid after passing through the expansion generator to generate electricity. The secondary bottom cycle organic working fluid is heated to 10°C to 20°C and then enters the secondary bottom cycle expansion generator 33 to generate electricity. The organic working fluid at the outlet of the expansion generator enters the secondary bottom cycle condenser 12 on the hot fluid side to absorb -80°C to 40°C LNG cold energy, and the above cycle is repeated to generate electricity.

[0055] The working fluid of the power generation cycle can be water, isopentane, propane, tetrafluoroethane and ethane, or a mixture of the above organic working fluids with other organic working fluids. The advantage of the mixed working fluid is that its cooling curve is better matched with the vaporization curve of LNG, making its heat exchange efficiency higher.

[0056] In the gas turbine exhaust carbon dioxide capture system, LNG at -147°C enters the second multi-stage compression interstage cooling device 11 to exchange heat with the high-concentration carbon dioxide after water removal. According to the carbon dioxide gasification curve, in order to avoid carbon dioxide condensation to form dry ice, the liquefaction pressure should be higher than the triple point pressure (517.8kPa) and the temperature should be higher than the triple point temperature (-56.6°C). The liquefaction pressure of carbon dioxide is 0.54MPa and the liquefaction temperature is -55°C. LNG is heated to -100°C, -95°C, and -90°C through the three heat exchangers in the second multi-stage compression interstage cooling device 11, and then enters the LNG cold energy power generation system for gasification and external transmission. The carbon dioxide is first pre-cooled to -20°C, compressed to 0.2MPa by the first compressor in the second multi-stage compression interstage cooling device 11, and then enters the heat exchanger to be cooled to -45°C, and then compressed to 0.54MPa by the second compressor in the second multi-stage compression interstage cooling device 11, and then enters the heat exchanger in the second multi-stage compression interstage cooling device 11 to be condensed and liquefied into liquid carbon dioxide, achieving near-zero emissions. Liquid carbon dioxide can be stored in a low-pressure storage tank for other uses.

[0057] The equipment and near-zero emission method for power generation and BOG treatment using LNG cold energy in this embodiment overcomes the problem of large BOG load fluctuation caused by large LNG export volume in the existing process, which leads to energy waste, improves the energy utilization rate of the LNG receiving station, and can not only efficiently process BOG and provide electricity and heat energy for the entire station, but also liquefy and recover carbon dioxide in the flue gas, reducing carbon and steam emissions, so that the system reaches the level of environmental protection and energy self-sufficiency.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for generating electricity and treating BOG using LNG cold energy, characterized in that: It includes a BOG treatment system, a BOG gas turbine power generation system, a gas turbine exhaust carbon dioxide capture system and an LNG cold energy power generation system which are interconnected with each other; The BOG processing system recovers BOG and separates LNG by means of multi-stage compression, inter-stage cooling and recondensation; The BOG gas turbine power generation system receives part of the BOG from the BOG processing system as fuel, and the medium-temperature mixed flue gas generated by the BOG gas turbine power generation system provides heat for the LNG cold energy power generation system by heating the heat transfer oil; The gas turbine exhaust carbon dioxide capture system captures carbon dioxide gas from the BOG gas turbine power generation system and transports LNG from the BOG processing system to the LNG cold energy power generation system; The LNG cold energy power generation system gasifies LNG by using the waste heat of the heat transfer oil, and the gasified LNG and the BOG from the BOG treatment system are combined into a third mixer (36) for external transmission.

2. The device for generating electricity and treating BOG by utilizing cold energy of LNG according to claim 1, characterized in that: The BOG processing system comprises an LNG storage tank (1), a BOG compressor (2), a first flow splitter (3), a first multi-stage compression interstage cooling device (4), a BOG recondenser (5), a low-pressure output pump (6), a second flow splitter (7), a pressure regulating valve (8) and a first mixer (9). The BOG and LNG in the LNG storage tank (1) are respectively delivered to the first flow splitter (3) and the second flow splitter (7) by the BOG compressor (2) and the low-pressure delivery pump (6); the first flow splitter (3) divides the BOG into three streams for output, the first stream BOG is delivered to the first multi-stage compression interstage cooling device (4) and connected, and the third stream BOG is delivered to the recondenser (5) and connected; the second flow splitter (7) divides the LNG into two streams, the first stream LNG is delivered to the BOG recondenser (5), and the second stream LNG passes through the pressure regulating valve (8) and then merges with the outlet stream LNG of the BOG recondenser (5) into the first mixer (9).

3. The equipment for power generation and BOG treatment using LNG cold energy according to claim 2 is characterized in that: The BOG gas turbine power generation system comprises an air separation device (14), a second mixer (15), a compressor (16), a regenerator (17), a combustion chamber (18), an expansion generator (19) and a thermal oil heater (20); the combustion chamber (18) is connected to the first flow divider (3); the second stream BOG is transported to the combustion chamber (18) to be used as fuel; the high-temperature mixed flue gas generated by the combustion chamber (18) is transported to the expansion generator (19); the medium-temperature flue gas generated by the expansion generator (19) sequentially enters the regenerator (17) and the thermal oil heater (20) for heat exchange; the high-purity oxygen separated in the air separation device (14) and the diluent are introduced into the second mixer (15); the mixed gas of the high-purity oxygen and the diluent enters the combustion chamber (18) through the compressor (16) and the regenerator (17) to assist combustion; The second mixer (15) is connected in sequence to the compressor (16), the regenerator (17), the combustion chamber (18), the expansion generator (19) and the thermal oil heater (20).

4. The device for generating electricity and treating BOG by utilizing cold energy of LNG according to claim 3 is characterized in that: The gas turbine exhaust carbon dioxide capture system comprises a dewatering device (21) and a second multi-stage compression interstage cooling device (11); the upstream of the second multi-stage compression interstage cooling device (11) is connected to the first mixer (9), and the downstream is connected to the secondary bottom cycle condenser (12) of the LNG cold energy power generation system; the upstream of the dewatering device (21) is connected to the thermal oil heater (20), and the downstream is connected to the second multi-stage compression interstage cooling device (11).

5. The device for generating electricity and treating BOG by utilizing cold energy of LNG according to claim 4 is characterized in that: An LNG high-pressure output pump (10) is provided upstream of the second multi-stage compression inter-stage cooling device (11) and between the first mixer (9).

6. The equipment for power generation and BOG treatment using LNG cold energy according to claim 4 is characterized in that: The LNG cold energy power generation system comprises a primary power generation cycle device, a secondary power generation cycle device, a heat transfer oil booster pump (34), an LNG vaporizer (35) and the third mixer (36); the heat transfer oil heater (20) is connected to the primary power generation cycle device, the secondary power generation cycle device, the heat transfer oil booster pump (34) and the LNG vaporizer (35) in sequence; the second multi-stage compression interstage cooling device (11) is connected to the secondary power generation cycle device, the primary power generation cycle device and the LNG vaporizer (35) in sequence; and the LNG vaporizer (35) is connected to the third mixer (36).

7. The device for generating electricity and treating BOG by utilizing cold energy of LNG according to claim 6, characterized in that: The primary power generation cycle device comprises a primary top circulation evaporator (22), a primary top circulation expansion generator (26), a first heat exchanger (24), a primary top circulation working fluid pump (28), a primary bottom circulation expansion generator (30), a primary bottom circulation condenser (13) and a primary bottom circulation working fluid pump (31); the primary top circulation evaporator (22), the primary top circulation expansion generator (26), the first heat exchanger (24) and the primary top circulation working fluid pump (28) are connected in a cycle in sequence; the primary top circulation evaporator (22) is connected to the thermal oil heater (20); the first heat exchanger (24), the primary bottom circulation expansion generator (30), the primary bottom circulation condenser (13) and the primary bottom circulation working fluid pump (31) are connected in a cycle in sequence; and the primary bottom circulation condenser (13) is connected to the LNG vaporizer (35).

8. The device for generating electricity and treating BOG by utilizing cold energy of LNG according to claim 7, characterized in that: The secondary power generation cycle device comprises a secondary top cycle evaporator (23), a secondary top cycle expansion generator (27), a second heat exchanger (25), a secondary top cycle working fluid pump (29), a secondary bottom cycle expansion generator (32), a secondary bottom cycle condenser (12) and a secondary bottom cycle working fluid pump (33). The secondary top cycle evaporator (23), the secondary top cycle expansion generator (27), the second heat exchanger (25) and the secondary top cycle working fluid pump (29) are connected in a circular manner in sequence. The secondary top cycle evaporator (23) is connected to the primary top cycle evaporator (22) and the heat transfer oil booster pump (34) respectively. The second heat exchanger (25), the secondary bottom cycle expansion generator (32), the secondary bottom cycle condenser (12) and the secondary bottom cycle working fluid pump (33) are connected in a circular manner in sequence. The secondary bottom cycle condenser (12) is connected to the second multi-stage compression interstage cooling device (11) and the primary bottom cycle condenser (13) respectively.

9. A near-zero emission method for power generation using LNG cold energy and BOG treatment, characterized in that: The equipment for power generation and BOG treatment using LNG cold energy according to any one of claims 1 to 8 is completed, comprising the following steps: When the LNG output volume is large, the BOG compressor (2) and the low-pressure output pump (6) are operated simultaneously, and the third stream BOG and the first stream LNG enter the recondenser (5), and the BOG is treated by using the cold energy of the LNG. After the BOG is condensed, it is merged with the second stream LNG into the first mixer (9) and then enters the high-pressure output pump (10); operating the high-pressure output pump (10) to allow the LNG output from the first mixer (9) to enter the second multi-stage compression interstage cooling device (11), and utilizing the cold energy of the LNG entering the second multi-stage compression interstage cooling device (11) to capture the carbon dioxide in the second multi-stage compression interstage cooling device (11); The high-pressure LNG outputted from the second multi-stage compression interstage cooling device (11) sequentially enters the secondary bottom cycle condenser (12) and the primary bottom cycle condenser (13) to release cold energy and condense the working fluid in the primary power generation cycle device and the secondary power generation cycle device; The high-pressure LNG output from the primary bottom cycle condenser (13) enters the LNG vaporizer (35), and the LNG is vaporized by the waste heat of the heat transfer oil in the LNG vaporizer (35). After the LNG is vaporized to ambient temperature, the vaporized LNG and the BOG at the outlet of the first multi-stage compression interstage cooling device (4) are combined into a third mixer (36) for external transmission.

10. The near-zero emission method for power generation and BOG treatment using LNG cold energy according to claim 9, characterized in that: In the step of capturing carbon dioxide in the second multi-stage compression interstage cooling device (11) by utilizing cold energy of LNG entering the second multi-stage compression interstage cooling device (11), carbon dioxide is generated by the BOG gas turbine power generation system and is input into the second multi-stage compression interstage cooling device (11) through a water removal device (21).

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