A centralized BOG and LNG gasification cold energy comprehensive utilization system and method

Abstract

The present application relates to a kind of centralized BOG and LNG gasification cold energy comprehensive utilization system and method, system includes LNG storage tank group, BOG storage and transportation pipeline, gas internal combustion engine generator set, LNG delivery pipeline, heat exchange device, CO2 processing device and turbine generator set.The present application utilizes BOG storage and transportation pipeline to realize the transportation and storage of BOG gas, compared with the existing storage tank cost is lower, more efficient, and BOG storage and transportation pipeline with LNG storage tank group, compared with single LNG storage tank, LNG storage tank group will continuously produce more BOG gas, the combination of LNG storage tank group and BOG storage and transportation pipeline can realize the continuous utilization of fluctuation output BOG gas;And utilize the gasification cold energy of LNG to convert gaseous CO2 into liquid CO2, not only can provide cold energy to user side, also can be used for power generation, or store up and supply externally, also heat exchange high-temperature flue gas and liquid CO2 in CO2 processing device, make it convert into supercritical CO2, can make full use of the combustion heat energy of BOG gas.

Description

Technical Field

[0001] This invention relates to the field of LNG (liquefied natural gas) application technology, and in particular to a centralized BOG and LNG gasification cold energy integrated utilization system and method. Background Technology

[0002] Liquefied natural gas (LNG) cryogenic storage tanks cannot achieve absolute insulation, inevitably producing boil-off gas (BOG). The presence of BOG threatens the safety of the system's production and must be properly handled. Current methods generally involve combustion, which fails to achieve adequate recycling and results in energy waste. Furthermore, LNG (approximately -162°C) needs to be vaporized to ambient temperature before being supplied to users. Existing vaporization processes typically employ seawater baths or combustion heating methods, causing environmental problems and significant energy waste.

[0003] The reason why the heat of combustion of BOG and the cold energy of LNG cannot be matched is that the production of BOG gas is directly related to the ambient temperature and fluctuates greatly, failing to meet the stable temperature requirements for LNG vaporization. Adopting effective technical means to achieve the comprehensive utilization of the cold energy from BOG and LNG vaporization is of great significance for LNG application and reducing energy waste. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a centralized BOG and LNG gasification cold energy integrated utilization system and method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A centralized BOG and LNG vaporization cold energy integrated utilization system includes an LNG storage tank group, BOG storage and transportation pipelines, a gas internal combustion engine generator set, an LNG transportation pipeline, a heat exchange device, a CO2 processing device, and a turbine generator set.

[0007] The LNG storage tank group is connected to the BOG storage and transportation pipeline and the LNG transportation pipeline, respectively.

[0008] The BOG storage and transportation pipeline is used to transport and store BOG gas and is connected to the gas internal combustion engine generator set for delivering BOG gas to the gas internal combustion engine generator set for power generation.

[0009] The heat exchange device includes a first heat exchange mechanism and a second heat exchange mechanism. The CO2 processing device is connected to the LNG transportation pipeline for heat exchange through the first heat exchange mechanism. After heat exchange, the LNG in the LNG transportation pipeline is vaporized into LNG, and the gaseous CO2 in the CO2 processing device is converted into liquid CO2 after heat exchange.

[0010] The flue gas outlet of the gas-fired internal combustion engine generator set is connected to the second heat exchange mechanism. The CO2 treatment device exchanges heat with the flue gas of the gas-fired internal combustion engine generator set through the second heat exchange mechanism to convert liquid CO2 into supercritical CO2. The CO2 treatment device is also connected to the turbine generator set to transport supercritical CO2 into the turbine generator set for power generation.

[0011] Preferably, the starting end of the BOG storage and transportation pipeline is provided with a first pump group, which is connected to the LNG storage tank group and is used to pressurize the BOG gas to a first set value and input it into the BOG storage and transportation pipeline.

[0012] Preferably, the starting end of the BOG storage and transportation pipeline is also equipped with a metering device for measuring the amount of BOG gas entering the BOG storage and transportation pipeline.

[0013] Preferably, the BOG storage and transportation pipeline includes a main pipe and at least one branch pipe, the two ends of the branch pipe being closable connected to the main pipe, the gas storage capacity of the branch pipe being greater than the gas storage capacity of the main pipe between the two ends of the branch pipe, and the main pipe connecting the LNG storage tank group and the gas internal combustion engine generator set.

[0014] The two ends of the branch pipe are respectively provided with a first on-off valve and a second on-off valve at the connection between them and the main pipe. The first on-off valve and the second on-off valve are communicatively connected to the metering device. The first on-off valve is opened when the amount of BOG gas entering the BOG storage and transportation pipeline is greater than a first threshold, so that some BOG gas enters the branch pipe. The first on-off valve is closed and the second on-off valve is opened when the amount of BOG gas entering the BOG storage and transportation pipeline is less than a second threshold.

[0015] Preferably, the branch pipe also contains a drive pump for delivering BOG gas from the branch pipe to the main pipe.

[0016] Preferably, a second pump set is provided at the end of the BOG storage and transportation pipeline to regulate the pressure of the BOG gas to a second set value and input it into the gas internal combustion engine generator set.

[0017] Preferably, the CO2 processing device includes a CO2 storage module, a CO2 conveying module, and a gas-liquid separation module; the CO2 conveying module is connected to the CO2 storage module and the gas-liquid separation module respectively, and exchanges heat with the first heat exchange mechanism, so that at least a portion of the gaseous CO2 therein is cooled into liquid CO2; the gas-liquid separation module is used to separate the gaseous CO2 and the liquid CO2;

[0018] The liquid outlet of the gas-liquid separation module is connected to the third pump set.

[0019] Preferably, the CO2 processing device further includes a third pump set and a distribution module; the liquid outlet of the gas-liquid separation module is connected to the distribution module through the third pump set, the third pump set is used to increase the pressure of liquid CO2, and the distribution module includes at least three connection ports, one of which is connected to the user side for delivering a portion of the liquid CO2 to the user side to provide cooling energy.

[0020] Preferably, the CO2 treatment device further includes a fourth pump set and a delivery pipeline. The fourth pump set is connected to another connection port of the distribution module and is used to increase the pressure of the liquid CO2 to 10-20 MPa.

[0021] The conveying pipeline is connected to the fourth pump set and exchanges heat with the flue gas of the gas internal combustion engine generator set through the second heat exchange mechanism to convert the pressurized liquid CO2 into supercritical CO2; and the conveying pipeline is connected to the turbine generator set to convey at least a portion of the supercritical CO2 to the turbine generator set.

[0022] The CO2 processing device also includes a supercritical CO2 storage tank, and the delivery pipeline is also connected to the supercritical CO2 storage tank.

[0023] To achieve the above objectives, the present invention also employs the following technical solution:

[0024] A centralized method for the integrated utilization of BOG and LNG vaporization cold energy, employing the aforementioned centralized BOG and LNG vaporization cold energy integrated utilization system, includes the following steps:

[0025] BOG utilization steps: BOG gas generated in the LNG storage tank group is pressurized to a first set value and then input into the BOG storage and transportation pipeline; the amount of BOG gas input into the BOG storage and transportation pipeline is measured, and when the amount of BOG gas entering the BOG storage and transportation pipeline is greater than a first threshold, the inlet end of the branch pipe is opened, allowing some BOG gas to enter the branch pipe for storage; when the amount of BOG gas entering the BOG storage and transportation pipeline is less than a second threshold, the inlet end of the branch pipe is closed, and the outlet end of the branch pipe is opened, inputting the gas stored in the branch pipe into the main pipe; after the BOG gas in the main pipe is pressurized to meet the pressure requirements of the gas internal combustion engine generator set, it is input into the gas internal combustion engine generator set for power generation.

[0026] LNG vaporization cold energy utilization steps: LNG taken from the LNG storage tank group is heat exchanged through the first heat exchange mechanism. After heat exchange, the LNG is vaporized into NG. The gaseous CO2 in the CO2 processing device is converted into liquid CO2 after heat exchange. After the liquid CO2 is pressurized, part of it is used for cooling on the user side, and the other part is further pressurized and heat exchanged with the flue gas of the gas internal combustion engine generator set to convert it into supercritical CO2. The supercritical CO2 is then transported into the turbine generator set for power generation or storage.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The centralized BOG and LNG vaporization cold energy integrated utilization system and method provided in the above technical solution realizes the transportation and storage of BOG gas by using BOG storage and transportation pipelines. Compared with existing storage tanks, it has lower cost and higher efficiency. Moreover, compared with a single LNG storage tank, the LNG storage tank group will continuously generate more BOG gas. Combining the LNG storage tank group with the BOG storage and transportation pipeline can realize the continuous utilization of fluctuating BOG gas production.

[0029] 2. In the above technical solution, the gaseous CO2 is converted into liquid CO2 by the vaporization cold energy of LNG, thus avoiding the waste of LNG vaporization cold energy. Liquid CO2 has many uses, including providing cold energy to users, generating electricity, or storing it for external supply.

[0030] 3. In the above technical solution, BOG gas is transported to the gas internal combustion engine generator set for combustion and power generation, and the generated flue gas is exchanged with liquid CO2 in the CO2 treatment device to convert it into supercritical CO2. This can make full use of the combustion heat energy of BOG gas. Moreover, the supercritical CO2 can not only be input into the turbine generator set for power generation, but can also be stored and supplied to the outside world, thereby improving the energy utilization rate. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the centralized BOG and LNG gasification cold energy integrated utilization system according to an embodiment of the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. LNG storage tank group; 11. LNG storage tank; 12. LNG transmission pipeline;

[0035] 2. BOG storage and transportation pipeline; 21. Main pipe; 22. Branch pipe; 221. Inlet end; 222. Outlet end; 223. First on / off valve; 224. Second on / off valve; 225. Drive pump; 23. First pump set; 24. Metering device; 25. Second pump set;

[0036] 3. Gas-fired internal combustion engine generator set;

[0037] 4. First heat exchange mechanism;

[0038] 5. Second heat exchange mechanism;

[0039] 6. CO2 processing unit; 61. CO2 storage module; 62. CO2 conveying module; 63. Gas-liquid separation module; 64. Third pump set; 65. Distribution module; 66. Fourth pump set; 67. Conveying pipeline; 68. Supercritical CO2 storage tank;

[0040] 7. Turbine generator set. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] As attached Figure 1As shown, this embodiment of the invention provides a centralized BOG and LNG vaporization cold energy integrated utilization system, including an LNG storage tank group 11, a BOG storage and transportation pipeline 22, a gas-fired internal combustion engine generator set 3, an LNG transportation pipeline 12, a heat exchange device, a CO2 treatment device 6, and a turbine generator set 7; the LNG storage tank group 1 refers to a number of LNG (liquefied natural gas) storage tanks centrally distributed. Each LNG storage tank 11 produces a variable amount of BOG gas (evaporation gas), so these BOG gases are collected and input into the BOG storage and transportation pipeline 2. The BOG storage and transportation pipeline 2 is used to transport and store BOG gas, including a main pipe 21 and at least one branch pipe 22. One end of the main pipe 21 is connected to One end of the branch pipe 22 connects to the LNG storage tank group 1, and the other end connects to the gas internal combustion engine generator set 3. The main function of the branch pipe 22 is to store the excess BOG gas when the LNG storage tank group 1 produces a large amount exceeding the BOG gas required by the gas internal combustion engine generator set 3. Therefore, both ends of the branch pipe 22 are closable to the main pipe 21. The gas storage capacity of the branch pipe 22 is greater than the gas storage capacity of the main pipe 21 between the two ends of the branch pipe 22. The two ends of the branch pipe 22 are divided into an inlet end 221 and an outlet end 222. The amount of BOG gas entering the gas internal combustion engine generator set 3 can be controlled by switching the two ends of the branch pipe 22, thus achieving continuous utilization of fluctuating BOG gas production. The number of branch pipes 22 can be set according to the number of LNG storage tanks. Theoretically, the more LNG storage tanks there are, the more branch pipes 22 connected to the main pipe 21. Part of the combustion heat energy of the BOG gas is converted into electrical energy. To further improve utilization, the high-temperature flue gas generated by the gas internal combustion engine generator set 3 is used for heat exchange. Specifically, the heat exchange device includes a first heat exchange mechanism 4 and a second heat exchange mechanism 5. The CO2 processing device is connected to the LNG transportation pipeline through the first heat exchange mechanism 4 for heat exchange. After heat exchange, the LNG in the LNG transportation pipeline is vaporized into LNG. The gaseous CO2 in the CO2 processing device is converted into liquid CO2 after heat exchange, so as to utilize the cold energy of LNG vaporization. The generated liquid CO2 has many uses. It can not only provide cold energy to the user side, but also be used for power generation, or stored for external supply. When at least a portion of the liquid CO2 is used for power generation, the second heat exchange mechanism 5 makes full use of the heat of the high-temperature flue gas to convert the pressurized liquid CO2 into supercritical CO2, which can be used for power generation by the turbine generator set 7.

[0045] For details, see attached. Figure 1 As shown, the starting end of the BOG storage and transportation pipeline 2 is equipped with a first pump set 23, which is connected to the LNG storage tank group 1. This first pump set 23 is used to pressurize the BOG gas to a first set value and input it into the BOG storage and transportation pipeline 2. The first set value is approximately 2 MPa, allowing the main pipe 21 and branch pipe 22 to store more BOG gas while maintaining low energy consumption of the first pump. The shape of the branch pipe 22 is not fixed; it only needs to be able to store BOG gas pressurized to 2 MPa.

[0046] A metering device 24 is also installed at the beginning of the BOG storage and transportation pipeline 2 to measure the amount of BOG gas entering the BOG storage and transportation pipeline 2. Since each LNG storage tank produces BOG gas and the amount of gas produced is variable, the metering device 24 is installed at the beginning of the main pipe 21, that is, at the location where the BOG gas produced by all LNG storage tanks is collected. The metering device 24 can be a flow meter to record the total amount of BOG gas produced by the LNG storage tank group 1.

[0047] To enable the connection and disconnection between the two ends of the branch pipe 22 and the main pipe 21, a first on-off valve 223 and a second on-off valve 224 are respectively installed at the connection points of the two ends of the branch pipe 22 and the main pipe 21. Correspondingly, the first on-off valve 223 is located at the air inlet end 221 of the branch pipe 22, and the second on-off valve 224 is located at the air outlet end 222 of the branch pipe 22. The first on-off valve 223 and the second on-off valve 224 are communicatively connected to the metering device 24 and are used to open the first on-off valve 223 when the amount of BOG gas entering the BOG storage and transportation pipeline 2 is greater than a first threshold, so that some BOG gas enters the branch pipe 22. When there are many branch pipes 22, and the amount of BOG gas entering the BOG storage and transportation pipeline 2 just exceeds the first threshold, the first on / off valve 223 of one branch pipe 22 can be opened first, and the second on / off valve 224 can be opened. This delays the entry of some BOG gas into the main pipe 21. If the amount of BOG gas entering the BOG storage and transportation pipeline 2 continues to exceed the first threshold, the first on / off valves 223 of more branch pipes 22 can be opened, and the second on / off valves 224 can be closed. This temporarily halts the entry of some BOG gas into the main pipe 21, at which point the branch pipes 22 function as storage pipes. When the amount of BOG gas entering the BOG storage and transportation pipeline 2 is less than the second threshold, the first on / off valve 223 is closed, preventing further BOG gas from entering the branch pipes 22, and the second on / off valve 224 is activated to input the BOG gas stored in the branch pipes 22 into the main pipe 21 as a supplement. Preferably, the branch pipe 22 also contains a drive pump 225 for transporting the BOG gas from the branch pipe 22 to the main pipe 21.

[0048] The gas-fired internal combustion engine generator set 3 has certain requirements for the input gas pressure. The BOG gas in the main pipe 21 of the BOG storage and transportation pipeline 2 needs to be pressurized to a second set value by the second pump set 25 to meet the pressure requirements of the gas-fired internal combustion engine generator set 3 before being input into the gas-fired internal combustion engine generator set 3. The specific value of the second set value is set according to the type of gas-fired internal combustion engine generator set 3.

[0049] As attached Figure 1As shown, the CO2 processing device includes a CO2 storage module 61, a CO2 conveying module 62, and a gas-liquid separation module 63. The CO2 conveying module 61 is connected to both the CO2 storage module 62 and the gas-liquid separation module 63, and exchanges heat with the first heat exchange mechanism 4, thereby cooling at least a portion of the gaseous CO2 within it into liquid CO2. The gas-liquid separation module 63 is used to separate gaseous CO2 and liquid CO2. The liquid outlet of the gas-liquid separation module 63 is connected to a third pump set 64. The CO2 storage module 61 can be a gaseous CO2 storage tank. The CO2 transport module 62 is a transport pipe, the gas-liquid separation module 63 is a gas-liquid separator, and the first heat exchange mechanism 4 is a conventional heat exchanger. It is connected to the LNG output end of the LNG storage tank group 1 and the transport pipe to achieve heat exchange, transferring the vaporization cold energy of LNG to gaseous CO2, so that at least part of the gaseous CO2 is cooled into liquid CO2. Therefore, the gas-liquid separation module 63 is needed to separate gaseous CO2 and liquid CO2, returning the gaseous CO2 to the CO2 storage module 61 and using the liquid CO2 separately.

[0050] The CO2 treatment unit also includes a third pump group 64 and a distribution module 65. Liquid CO2 is fed into the third pump group 64 through the liquid outlet for pressurization. The pressurized liquid CO2 has a temperature of approximately -40°C and a pressure of approximately 2 MPa. At this point, the liquid CO2 can be used for cooling or further pressurization. The distribution module 65 is a three-way valve, with one of its ports connected to the user side to deliver a portion of the liquid CO2 to the user side for cooling.

[0051] The CO2 processing device in this embodiment also includes a fourth pump group 66 and a delivery pipeline 67. The fourth pump group 66 is connected to another connection port of the distribution module 65 to increase the pressure of liquid CO2 to 10-20 MPa. Then, the delivery pipeline 67 is connected to the fourth pump group 66 and exchanges heat with the flue gas of the gas internal combustion engine generator set 3 through the second heat exchange mechanism 5 to convert the pressurized liquid CO2 into supercritical CO2. The delivery pipeline is also connected to the turbine generator set 7 to deliver at least a portion of the supercritical CO2 to the turbine generator set 7. Supercritical carbon dioxide working fluid power generation refers to a power generation technology that uses supercritical carbon dioxide (sCO2) as a working fluid to convert heat energy into electrical energy during the thermal power generation process. It has the characteristics of high efficiency, flexibility, environmental protection, and low cost. In this embodiment, BOG gas is delivered to the gas internal combustion engine generator set 3 for combustion and power generation, and the generated flue gas exchanges heat with the liquid CO2 in the CO2 processing device 6 to convert it into supercritical CO2, which can fully utilize the combustion heat energy of BOG gas. The CO2 processing device 6 also includes a supercritical CO2 storage tank 68, and a conveying pipeline 67 is connected to the supercritical CO2 storage tank 68 to store supercritical CO2 for external supply, with a wide range of applications.

[0052] Based on the above system, this invention also provides a method for the comprehensive utilization of centralized BOG and LNG gasification cold energy, comprising the following steps:

[0053] BOG Utilization Steps: BOG gas generated in LNG tank group 1 is pressurized to a first set value and then input into BOG storage and transportation pipeline 2. Specifically, the BOG gas generated in LNG tank group 1 is pressurized to approximately 2 MPa by the first pump group 23 and then enters BOG storage and transportation pipeline 2. Simultaneously, the amount of BOG gas input into BOG storage and transportation pipeline 2 is measured. Specifically, a flow meter is used to measure the amount of BOG gas input into BOG storage and transportation pipeline 2 and determine whether it matches the amount of BOG gas required by the gas-fired internal combustion engine generator set 3. The first and second thresholds set by the system are both related to the amount of BOG gas required by the gas-fired internal combustion engine generator set 3. When the amount of BOG gas entering BOG storage and transportation pipeline 2 exceeds the first threshold, the inlet end 221 of branch pipe 22 is opened, allowing some BOG gas to enter and be stored in branch pipe 22. Specifically, when there are many branch pipes 22 and the amount of BOG gas entering BOG storage and transportation pipeline 2 just exceeds the first threshold, one of them can be opened first. When the first shut-off valve 223 of a branch pipe 22 is opened and the second shut-off valve 224 is opened, some BOG gas entering the branch pipe 22 is only delayed in entering the main pipe 21. If the amount of BOG gas entering the BOG storage and transportation pipeline 2 continuously exceeds the first threshold, the first shut-off valve 223 of more branch pipes 22 is opened and the second shut-off valve 224 is closed, so that some BOG gas entering the branch pipe 22 is suspended from entering the main pipe 21. At this time, the branch pipe 22 plays a storage role. When the amount of BOG gas entering the BOG storage and transportation pipeline 2 is less than the second threshold, the first shut-off valve 223 is closed, so that BOG gas no longer enters the branch pipe 22, and the second shut-off valve 224 is activated to input the BOG gas stored in the branch pipe 22 into the main pipe 21 as a supplement. Then, the pressure of the BOG gas in the main pipe 21 is adjusted to meet the pressure requirements of the gas internal combustion engine generator set 3, and then input into the gas internal combustion engine generator set 3 to generate electricity. The power generation process of the gas internal combustion engine generator set 3 is a conventional technology and will not be described in detail here.

[0054] The method in this embodiment also includes an LNG vaporization cold energy utilization step: LNG taken from LNG storage tank group 1 is heat exchanged through the first heat exchange mechanism 4. After heat exchange, LNG is vaporized into NG. The gaseous CO2 in the CO2 processing device is transformed into liquid CO2 after heat exchange. After the liquid CO2 is pressurized, part of it is used for cooling on the user side, and the other part is further pressurized and heat exchanged with the flue gas of the gas internal combustion engine generator set 3 to transform into supercritical CO2. The supercritical CO2 is then transported into the turbine generator set 7 for power generation or storage.

[0055] Specifically, the CO2 processing device 6 includes a CO2 storage module 61, a CO2 conveying module 62, a gas-liquid separation module 63, a third pump group 64, a distribution module 65, a fourth pump group 66, and a conveying pipeline 67. The CO2 storage module can be a gaseous CO2 storage tank, the CO2 conveying module is a transport pipe, the gas-liquid separation module 63 is a gas-liquid separator, and the first heat exchange mechanism 4 is a conventional heat exchanger. The first heat exchange mechanism 4 is connected to the LNG output end of the LNG storage tank group 1 and the transport pipe to achieve heat exchange, transferring the vaporization cold energy of LNG to the gaseous CO2, so that at least part of the gaseous CO2 is cooled into liquid CO2. Therefore, the gas-liquid separation module 63 is needed to separate the gaseous CO2 and liquid CO2, returning the gaseous CO2 to the CO2 storage module and using the liquid CO2 separately. Then, the liquid CO2 is sent to the third pump group 64 through the liquid outlet for pressurization. The temperature of the pressurized liquid CO2 is about -40℃, and the pressure is about 2MPa. At this point, the liquid CO2 can be used for cooling or further pressurization. The distribution module 65 is a three-way valve, with one of its ports connected to the user side to deliver a portion of the liquid CO2 to the user side for cooling. The fourth pump group 66 is connected to the other port of the distribution module 65 to increase the pressure of the liquid CO2 to 10-20 MPa. Then, the delivery pipeline is connected to the fourth pump group and exchanges heat with the flue gas of the gas internal combustion engine generator set 3 through the second heat exchange mechanism 5 to convert the pressurized liquid CO2 into supercritical CO2. The delivery pipeline is also connected to the turbine generator set 7 to deliver at least a portion of the supercritical CO2 to the turbine generator set 7.

[0056] The method of this invention enables continuous utilization of fluctuating BOG gas production, and fully utilizes the cold energy from LNG vaporization and the heat energy from BOG gas combustion, thus avoiding energy waste.

[0057] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A centralized BOG and LNG gasification cold energy integrated utilization system, characterized in that, This includes LNG storage tank groups, BOG storage and transportation pipelines, gas-fired internal combustion engine generator sets, LNG transportation pipelines, heat exchange devices, CO2 processing devices, and turbine generator sets. The LNG storage tank group is connected to the BOG storage and transportation pipeline and the LNG transportation pipeline, respectively. The BOG storage and transportation pipeline is used to transport and store BOG gas and is connected to the gas internal combustion engine generator set for delivering BOG gas to the gas internal combustion engine generator set for power generation. The BOG storage and transportation pipeline includes a main pipe and at least one branch pipe. One end of the main pipe is connected to the LNG storage tank group, and the other end is connected to the gas internal combustion engine generator set. The branch pipe is used to store excess BOG gas when the amount of BOG gas generated by the LNG storage tank group is greater than the amount of BOG gas required by the gas internal combustion engine generator set. Both ends of the branch pipe are closable connected to the main pipe, and the gas storage capacity of the branch pipe is greater than the gas storage capacity of the main pipe between the two ends of the branch pipe. The heat exchange device includes a first heat exchange mechanism and a second heat exchange mechanism. The CO2 processing device is connected to the LNG transportation pipeline for heat exchange through the first heat exchange mechanism. After heat exchange, the LNG in the LNG transportation pipeline is vaporized into LNG, and the gaseous CO2 in the CO2 processing device is converted into liquid CO2 after heat exchange. The flue gas outlet of the gas internal combustion engine generator set is connected to the second heat exchange mechanism. The CO2 treatment device exchanges heat with the flue gas of the gas internal combustion engine generator set through the second heat exchange mechanism to convert liquid CO2 into supercritical CO2. The CO2 treatment device is also connected to the turbine generator set to transport supercritical CO2 into the turbine generator set for power generation. The BOG storage and transportation pipeline is equipped with a first pump set at its starting end. The first pump set is connected to the LNG storage tank group and is used to pressurize the BOG gas to a first set value and input it into the BOG storage and transportation pipeline.

2. The system according to claim 1, characterized in that, The starting end of the BOG storage and transportation pipeline is also equipped with a metering device for measuring the amount of BOG gas entering the BOG storage and transportation pipeline.

3. The system according to claim 2, characterized in that, The two ends of the branch pipe are respectively provided with a first on-off valve and a second on-off valve at the connection between them and the main pipe. The first on-off valve and the second on-off valve are communicatively connected to the metering device. The first on-off valve is opened when the amount of BOG gas entering the BOG storage and transportation pipeline is greater than a first threshold, so that some BOG gas enters the branch pipe. The first on-off valve is closed and the second on-off valve is opened when the amount of BOG gas entering the BOG storage and transportation pipeline is less than a second threshold.

4. The system according to claim 3, characterized in that, The branch pipe also contains a drive pump, which is used to transport BOG gas in the branch pipe to the main pipe.

5. The system according to any one of claims 1 to 4, characterized in that, The BOG storage and transportation pipeline is equipped with a second pump set at its end, which is used to regulate the pressure of the BOG gas to a second set value and input it into the gas internal combustion engine generator set.

6. The system according to claim 1, characterized in that, The CO2 processing device includes a CO2 storage module, a CO2 conveying module, and a gas-liquid separation module; the CO2 conveying module is connected to the CO2 storage module and the gas-liquid separation module respectively, and exchanges heat with the first heat exchange mechanism, so that at least a portion of the gaseous CO2 therein is cooled into liquid CO2; the gas-liquid separation module is used to separate the gaseous CO2 and the liquid CO2.

7. The system according to claim 6, characterized in that, The CO2 processing device also includes a third pump set and a distribution module; the liquid outlet of the gas-liquid separation module is connected to the distribution module through the third pump set, the third pump set is used to increase the pressure of liquid CO2, and the distribution module includes at least three connection ports, one of which is connected to the user side to deliver a portion of the liquid CO2 to the user side to provide cooling energy.

8. The system as described in claim 7, characterized in that, The CO2 processing device also includes a fourth pump set and a delivery pipeline. The fourth pump set is connected to another connection port of the distribution module and is used to increase the pressure of liquid CO2 to 10-20MPa. The conveying pipeline is connected to the fourth pump set and exchanges heat with the flue gas of the gas internal combustion engine generator set through the second heat exchange mechanism to convert the pressurized liquid CO2 into supercritical CO2; and the conveying pipeline is connected to the turbine generator set to convey at least a portion of the supercritical CO2 to the turbine generator set. The CO2 processing device also includes a supercritical CO2 storage tank, and the delivery pipeline is also connected to the supercritical CO2 storage tank.

9. A centralized method for the integrated utilization of cold energy from BOG and LNG gasification, characterized in that, The centralized BOG and LNG gasification cold energy integrated utilization system as described in any one of claims 1 to 8 includes the following steps: BOG utilization steps: BOG gas generated in the LNG storage tank group is pressurized to a first set value and then input into the BOG storage and transportation pipeline; the amount of BOG gas input into the BOG storage and transportation pipeline is measured, and when the amount of BOG gas entering the BOG storage and transportation pipeline is greater than a first threshold, the inlet end of the branch pipe is opened, allowing some BOG gas to enter the branch pipe for storage; when the amount of BOG gas entering the BOG storage and transportation pipeline is less than a second threshold, the inlet end of the branch pipe is closed, and the outlet end of the branch pipe is opened, inputting the gas stored in the branch pipe into the main pipe; after the BOG gas in the main pipe is pressurized to meet the pressure requirements of the gas internal combustion engine generator set, it is input into the gas internal combustion engine generator set for power generation. LNG vaporization cold energy utilization steps: LNG taken from the LNG storage tank group is heat exchanged through the first heat exchange mechanism. After heat exchange, the LNG is vaporized into NG. The gaseous CO2 in the CO2 processing device is converted into liquid CO2 after heat exchange. After the liquid CO2 is pressurized, part of it is used for cooling on the user side, and the other part is further pressurized and heat exchanged with the flue gas of the gas internal combustion engine generator set to convert it into supercritical CO2. The supercritical CO2 is then transported into the turbine generator set for power generation or storage.

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