A system and method for comprehensive utilization of gas excess pressure and LNG cold energy

Abstract

A comprehensive system for utilizing residual gas pressure and LNG cold energy includes: a residual gas pressure utilization system for utilizing the pressure energy of residual gas pressure, with its inlet being high-pressure gas from upstream; a vortex tube, with its inlet connected to the outlet of the high-pressure gas, converting the high-pressure gas into hot and cold gas streams, wherein the cold gas stream provides cooling for users; and an LNG cold energy comprehensive utilization system that uses the hot gas stream output from the vortex tube as heat for power generation and heating. This invention can improve the energy utilization rate of high-pressure residual gas pressure, maximize the energy utilization of the entire system, solve users' electricity, cooling, heating, and gas needs, and reduce fossil fuel consumption and greenhouse gas emissions.

Description

Technical Field

[0001] This invention belongs to the field of energy technology, and relates to the fields of high-pressure gas waste pressure utilization, vortex tube refrigeration and organic Rankine cycle (ORC), and particularly relates to a system and method based on the comprehensive utilization of high-pressure gas waste energy and LNG cold energy. Background Technology

[0002] The environmental pollution and energy crisis caused by the consumption of fossil fuels are becoming increasingly prominent. Energy is a constraint on the country's energy use. The utilization of renewable energy technologies such as construction site thermal energy, biomass energy, and waste pressure and heat will become an important measure to improve energy efficiency.

[0003] In current industries such as manufacturing, steel, metallurgy, and chemicals, a large amount of redundant pressure energy is often generated during the production process. Since traditional throttling and pressure reduction methods involve direct discharge without utilization, this results in the waste of residual pressure energy. When high-pressure gas is cooled and depressurized, it loses a large amount of pressure and temperature difference, causing a great waste of resources. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a system and method for the comprehensive utilization of gas residual pressure and LNG cold energy, so as to improve the energy utilization rate of high-pressure gas residual pressure, maximize the energy utilization of the entire system, solve the user's electricity, cooling, heating and gas problems, and reduce the consumption of fossil fuels and greenhouse gas emissions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A system for the comprehensive utilization of residual gas pressure and LNG cold energy includes a vortex tube, a first heat exchanger, an expander, a second heat exchanger, and a third heat exchanger; the first heat exchanger, the expander, and the second heat exchanger form a loop; the inlet of the vortex tube is connected to high-pressure gas, which converts the high-pressure gas into cold gas and hot gas.

[0007] The hot gas flow is sent into the first heat exchanger. In the circuit, the organic working medium absorbs the heat exchanged by the first heat exchanger and expands in the expander to do work. After doing work, the organic working medium exchanges heat with the low-temperature LNG in the second heat exchanger. After the heat exchange, the organic working medium enters the first heat exchanger to absorb heat again. After the heat exchange, the low-temperature LNG exchanges heat with the gas exiting the first heat exchanger in the third heat exchanger to obtain the terminal gas, realizing the comprehensive utilization of gas residual pressure and LNG cold energy.

[0008] In one embodiment, the system further includes a fourth heat exchanger; the fourth heat exchanger is connected between the first heat exchanger and the third heat exchanger, and exchanges heat between the cold gas flow and the gas exiting the first heat exchanger. The heated cold gas flow merges into or serves as terminal gas, and the cooled gas is sent to the third heat exchanger to exchange heat with the low-temperature LNG after heat exchange.

[0009] In one embodiment, the system further includes a cryogenic LNG tank for storing and pumping cryogenic LNG into a second heat exchanger to exchange heat with the organic working fluid after work has been performed.

[0010] In one embodiment, the system further includes a turbine connected between a second heat exchanger and a third heat exchanger, wherein the cryogenic LNG performs work to generate electricity in the turbine after heat exchange, and then enters the turbine.

[0011] In one embodiment, the first heat exchanger, the second heat exchanger, the third heat exchanger, and the fourth heat exchanger constitute a heat exchanger assembly; the expander and the turbine constitute a turbine expander assembly; the heat exchanger assembly and the turbine expander assembly constitute a gas waste pressure utilization system; the heat exchanger assembly and the turbine expander assembly adopt a multi-stage heat exchange and energy-stage utilization method, wherein the first heat exchanger performs the first stage of heat exchange, the second and fourth heat exchangers perform the second stage of heat exchange, and the third heat exchanger performs the third stage of heat exchange.

[0012] In one embodiment, the first heat exchanger, the expander, and the second heat exchanger constitute an LNG cold energy integrated utilization system; wherein the heat source side inlet of the first heat exchanger is connected to the hot gas outlet of the vortex tube, which is the heat source inlet of the LNG cold energy integrated utilization system, the organic working fluid outlet of the first heat exchanger is connected to the inlet of the expander, the gaseous organic working fluid expands and does work in the expander, the outlet of the expanded and work-doping organic working fluid is connected to the heat source side inlet of the second heat exchanger, the cold source side inlet of the second heat exchanger is connected to the cryogenic LNG, and the working fluid after heat exchange in the second heat exchanger is pumped into the first heat exchanger to participate in the heat exchange cycle.

[0013] In one embodiment, depending on the spatial layout of the entire system, the expander, turbine, and pump components may be coaxial or non-coaxial, or partially coaxial and partially non-coaxial.

[0014] The present invention also provides a method for comprehensive utilization of residual gas pressure and LNG cold energy based on the method described in claim 1, the process of which is as follows:

[0015] High-pressure gas is sent into the vortex tube through a gas pipeline and split into two fluid streams: a cold stream and a hot stream. The cold stream is used for cooling, while the hot stream is used for heating the circuit, causing the expander to expand and do work. After doing work, the organic working fluid exchanges heat with the low-temperature LNG in the second heat exchanger. After the heat exchange, the organic working fluid enters the first heat exchanger to absorb heat again. The gas exiting the first heat exchanger exchanges heat with the low-temperature LNG after the heat exchange in the third heat exchanger to obtain the terminal gas, realizing the comprehensive utilization of gas residual pressure and LNG cold energy.

[0016] In one embodiment, the comprehensive utilization of LNG cold energy firstly involves using the hot gas flow to heat the organic working fluid into a gaseous state, which then expands and performs work in an expander, driving a generator to produce electricity. The cooled organic working fluid is then supplied to a second heat exchanger, where it condenses from a gaseous state into a liquid state. The heat released is absorbed by the LNG. The heated organic working fluid is then pumped into a first heat exchanger for reheating before being sent to the expander for further expansion and work. During the comprehensive utilization of LNG cold energy, the heat released by the cooled organic working fluid after expansion and work in the expander is transferred to the turbine via the second heat exchanger for further work.

[0017] In one embodiment, the pressure range of the high-pressure gas is between 0.8 and 2.5 MPa, the temperature range of the cold gas flow is between -50°C and -10°C, the temperature range of the hot gas flow is above 200°C, the temperature range of the three terminal gas sources is between 15°C and 25°C, and the pressure range is between 2000 Pa and 10000 Pa.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. Utilizing the characteristic of vortex tubes to generate vortexes in high-pressure gas to separate cold and hot gas streams, the hot gas stream is used to provide heat to the LNG cold energy comprehensive utilization system, while the cold gas stream is used for heat exchange and supplied to downstream users. An organic working fluid is used as the circulating working fluid in the LNG cold energy comprehensive utilization system to drive the expander to expand and generate electricity, thereby realizing the utilization of gas residual pressure and the comprehensive utilization of LNG cold energy.

[0020] 2. In the process of utilizing residual pressure, the present invention reuses the heat released by the high-temperature compressed gas through a heat exchanger.

[0021] 3. This invention utilizes the principle of energy cascade utilization to efficiently utilize the hot airflow at the outlet of the vortex tube. The hot airflow provides heat to the LNG cold energy integrated utilization system, causing the gas to expand and do work in the expander, thereby driving the generator to generate electricity. Finally, the heat from each part is rationally utilized through each heat exchanger.

[0022] 4. This invention simultaneously utilizes the residual heat of the hot airflow to further heat the cold airflow and deliver it to the user. It satisfies the user's electricity, cooling, heating, and gas needs while achieving good economic and environmental benefits.

[0023] 5. This invention utilizes the residual pressure energy during the gas transmission process and the LNG cold energy in the LNG cold energy integrated utilization system, thereby achieving full utilization of the energy contained in the high-pressure gas, maximizing the energy utilization of the entire system, and reducing greenhouse gas emissions without the need for additional fossil fuels.

[0024] 6. The system of this invention couples the vortex tube with the gas residual pressure utilization system and the LNG cold energy comprehensive utilization system. The structure is compact, and the diversity of choices in components and forms makes the whole system more adaptable. At the same time, the reasonable distribution of flow makes the system operation more flexible.

[0025] 7. The heat exchanger added in this invention can reduce the cold source loss of the LNG cold energy comprehensive utilization system and further increase the cycle efficiency.

[0026] In summary, compared with conventional waste energy utilization technologies, this invention has a high energy utilization rate, can combine gas waste pressure and LNG cold energy, reduces energy loss emissions, and can also solve users' electricity and gas consumption problems. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] 1 is a vortex tube; 2 is the first heat exchanger; 3 is a working fluid pump; 4 is an expander; 5 is a cryogenic LNG tank; 6 is an LNG pump; 7 is the second heat exchanger; 8 is a turbine; 9 is the third heat exchanger; and 10 is the fourth heat exchanger. Detailed Implementation

[0029] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0030] like Figure 1 As shown, the present invention is a gas waste pressure and LNG cold energy integrated utilization system, which mainly includes a vortex tube 1, a gas waste pressure utilization system and an LNG cold energy integrated utilization system. The vortex tube 1 converts high-pressure gas into hot and cold gas flow. The gas waste pressure utilization system utilizes the pressure energy of the high-pressure gas. The LNG cold energy integrated utilization system uses the obtained hot gas flow as heat to generate electricity and supply gas, and is coupled with the gas waste pressure utilization system.

[0031] The above is the subject matter and technical route of the present invention. Based on this, the following details or further optimizations are provided.

[0032] 1. Vortex tube 1.

[0033] The vortex tube 1 is an important component of this invention. Its inlet is connected to the high-pressure gas outside the system, which converts the high-pressure gas into cold gas and hot gas, with the hot gas serving as a heat source for heat exchange.

[0034] 2. Cryogenic LNG tank 5.

[0035] The cryogenic LNG tank 5 is used to store and supply cryogenic LNG to the system of the present invention, so as to realize the comprehensive utilization of cryogenic LNG cold energy. The energy source of the LNG cold energy comprehensive utilization system of the present invention comes from the cryogenic LNG tank 5. Of course, where feasible, cryogenic LNG can also be stored and supplied using other equipment.

[0036] 3. Gas residual pressure utilization system.

[0037] The gas residual pressure utilization system is an important part of this invention, which uses high-pressure gas as the source of residual pressure to utilize the residual pressure.

[0038] 4. LNG cold energy integrated utilization system.

[0039] The LNG cold energy integrated utilization system is an important part of the present invention. It uses the hot gas flow output from the vortex tube 1 as heat to generate electricity and provide heat.

[0040] In addition, to achieve the above-mentioned utilization, the present invention also sets up an ORC subsystem, which uses an organic working fluid with a low boiling point (such as R245fa) as the circulating working fluid.

[0041] In the system of this invention, the main components include a vortex tube 1, a first heat exchanger 2, an expander 4, a second heat exchanger 7, and a third heat exchanger 9. Among them, the first heat exchanger 2, the expander 4, and the second heat exchanger 7 form a loop, namely the aforementioned ORC subsystem, which can be referred to as the ORC loop.

[0042] The hot gas flow from the vortex tube 1 is first sent to the first heat exchanger 2 to heat the aforementioned circuit, while the cryogenic LNG is sent to the second heat exchanger 7 to cool the aforementioned circuit. In the aforementioned circuit, the circulating organic working medium absorbs the heat exchanged in the first heat exchanger 2, expands and does work in the expander 4, and after doing work, the organic working medium exchanges heat with the cryogenic LNG in the second heat exchanger 7. After the heat exchange, the organic working medium enters the first heat exchanger 2 again to absorb heat, and then enters the expander 4 again to expand and do work, completing the cycle.

[0043] For example, to achieve the above-described cycle, a working fluid pump 3 can be installed in the loop. Specifically, the working fluid pump 3 can be placed on the organic working fluid pipeline between the second heat exchanger 7 and the first heat exchanger 2. Correspondingly, cryogenic LNG can be pumped into the second heat exchanger 7 from the cryogenic LNG tank 5 via the LNG pump 6, which can be placed on the LNG pipeline between the outlet of the cryogenic LNG tank 5 and the cold source side inlet of the second heat exchanger 7.

[0044] On the other hand, the low-temperature LNG that has completed heat exchange in the second heat exchanger 7 can enter the third heat exchanger 9 and exchange heat again with the high-pressure gas that has completed heat exchange in the first heat exchanger 2. Terminal gas is obtained from both the cold source side outlet and the heat source side outlet of the third heat exchanger 9, ultimately realizing the comprehensive utilization of gas residual pressure and LNG cold energy.

[0045] Furthermore, in some embodiments of the present invention, to process the cold gas flow obtained from the vortex tube 1, the system further includes a fourth heat exchanger 10. The fourth heat exchanger 10 is connected between the first heat exchanger 2 and the third heat exchanger 9. The cold gas flow exiting the vortex tube 1 enters the cold source side inlet of the fourth heat exchanger 10, and the gas flow exiting the first heat exchanger 2 enters the heat source side inlet of the fourth heat exchanger 10. The two gas flows exchange heat in the fourth heat exchanger 10. After the cold gas flow is heated, it is discharged from its cold source side outlet and merged into the terminal gas or directly used as the terminal gas. The cooled gas flow is discharged from its heat source side outlet and sent to the third heat exchanger 9 to exchange heat with the cooled LNG. This embodiment processes the cold gas flow to meet the parameter requirements of the terminal gas for application.

[0046] Furthermore, in some embodiments of the present invention, in order to improve the utilization efficiency of heat energy and pressure, the system further includes a turbine 8; the turbine 8 is connected between the second heat exchanger 7 and the third heat exchanger 9, and after heat exchange, the cryogenic LNG first performs work to generate electricity in the turbine 8, and then enters the third heat exchanger 9 to exchange heat with the gas exiting the first heat exchanger 2.

[0047] In the above embodiments, the combination of the first heat exchanger 2, the second heat exchanger 7, the third heat exchanger 9, and the fourth heat exchanger 10 can be referred to as a heat exchanger assembly, and the combination of the expander 4 and the turbine 8 can be referred to as a turbine expander assembly. This heat exchanger assembly and turbine expander assembly constitute a specific structure and component form of the gas waste pressure utilization system. That is, the entire gas waste pressure utilization system includes the first heat exchanger 2, the expander 4, the second heat exchanger 7, the turbine 8, the third heat exchanger 9, and the fourth heat exchanger 10. This heat exchanger assembly and turbine expander assembly adopt a multi-stage heat exchange and energy-stage utilization method, wherein the first heat exchanger 2 performs the first stage of heat exchange, the second heat exchanger 7 and the fourth heat exchanger 10 perform the second stage of heat exchange, and the third heat exchanger 9 performs the third stage of heat exchange.

[0048] Specifically, the high-pressure gas is the inlet of the gas residual pressure utilization system. The heat source side inlet of the first heat exchanger 2 is connected to the hot gas outlet of the vortex tube 1, and the heat source side outlet of the first heat exchanger 2 is connected to the inlet of the fourth heat exchanger 10, transferring heat to the gas at the cold end outlet of the vortex tube 1. Part of the gas is supplied to the user, and the other part enters the third heat exchanger 9 for further heat exchange.

[0049] The outlet of the first heat exchanger 2 on the other heat source side is connected to the inlet of the expander 4. The organic working fluid expands and does work in the expander 4, driving the generator to produce electricity. The outlet of the expanded organic working fluid is connected to the heat source side inlet of the second heat exchanger 7. The heat source side outlet of the second heat exchanger 7 is high-temperature gas connected to the turbine 8. The gas expands and does work in the turbine 8. The gas at the outlet of the turbine 8 is then reheated in the third heat exchanger 9 and supplied to the user.

[0050] Similarly, in the above embodiments, the first heat exchanger 2, the expander 4, and the second heat exchanger 7 constitute a specific structure and component form of the LNG cold energy integrated utilization system of the present invention. That is, the LNG cold energy integrated utilization system includes the first heat exchanger 2, the expander 4, the second heat exchanger 7; and, if necessary, also includes a cryogenic LNG tank 5, an LNG pump 6, and a working fluid pump 3.

[0051] The heat source side inlet of the first heat exchanger 2 is connected to the hot gas outlet of the vortex tube 1, the heat source side outlet of the first heat exchanger 2 (i.e. the organic working fluid outlet) is the heat source inlet of the LNG cold energy integrated utilization system, and the heat source side outlet of the first heat exchanger 2 is connected to the inlet of the expander 4. The gaseous organic working fluid expands and does work in the expander 4, driving the generator to generate electricity.

[0052] The outlet of the organic working fluid after expansion and work is connected to the heat source side inlet of the second heat exchanger 7. The cold source side inlet of the second heat exchanger 7 is cryogenic LNG, which is provided by the cryogenic LNG tank 5. The cold source side outlet of the second heat exchanger 7 is connected to the cold source side inlet of the working fluid pump 3. The organic working fluid after heat exchange in the second heat exchanger 7 is preheated and reheated by the hot gas flow in the first heat exchanger 2 under the transportation of the working fluid pump 3, and participates in the heat exchange cycle.

[0053] The present invention can add a common regenerator between expander 4 and turbine 8 and between working fluid pump 3 and LNG pump 6. The exhaust gas of expander 4 and the pressurized LNG of LNG pump 6 are respectively introduced into the two sides of the regenerator. The liquid organic working fluid is heated by the exhaust gas of expander 10 and enters turbine 8. The exhaust gas of expander 4 is cooled by the liquid organic working fluid and enters working fluid pump 3.

[0054] Based on the above system, the workflow of the present invention is as follows:

[0055] First, high-pressure gas (generally between 0.8 and 2.5 MPa) is transported from an upstream high-pressure gas pipeline and introduced into vortex tube 1. The high-pressure gas is separated into two streams: a cold stream and a hot stream. The temperature range of the cold stream is -50℃ to -10℃, while the temperature range of the hot stream is above 200℃. The temperatures of the two streams can be adjusted by regulating the valve at the hot stream end. The cold stream is used to supply cooling to users, while the hot stream flows into the first heat exchanger 2 as a heat source to provide heat for the LNG cold energy integrated utilization system. In the first heat exchanger 2, the organic working fluid is heated to a high-temperature, high-pressure gaseous state and then enters the expander 4 to expand and perform work, thereby driving the generator to generate electricity. The expanded organic working fluid enters the second heat exchanger 7 to exchange heat with the low-temperature LNG, is condensed into a liquid state, and is then pumped back to the first heat exchanger 2 via the working fluid pump 3 for preheating using the hot flow from the outlet of vortex tube 1. The preheated organic working fluid then enters the expander 4 for the next cycle. The hot gas, which consumes some heat during the preheating process, is then supplied to heat users. Simultaneously, the heat released by the condensation of the expanded organic working fluid in the second heat exchanger 7 is absorbed by the cryogenic LNG, which is then heated and enters the turbine 8 to perform work. The gas exiting the turbine 8 further passes through the third heat exchanger 9 for waste energy utilization, with the surplus gas supplied to the user end. The outlet temperature of the cold source of the first heat exchanger 2 can be adjusted according to the thermodynamic properties of the LNG used to generate a high-temperature, high-pressure gaseous organic working fluid that enters the expander 4 to expand and perform work. Similarly, the outlet temperature of the cold source of the second heat exchanger 7 can also be adjusted according to the organic working fluid used and the specific requirements of the system. The final result of this invention is a gas temperature range of 15℃ to 25℃ and a pressure range of 2000Pa to 10000Pa at the three terminals.

[0056] In this invention, the LNG pump 6, working fluid pump 3, turbine 8 and expander 4 can be coaxial or non-coaxial depending on the spatial layout of the entire system. Alternatively, some pumps and expanders can be coaxial, while others can be non-coaxial. The expander 4 is coaxially connected to the generator.

[0057] This invention features control valves at the inlet and between certain pipes in the system, all of which are electromagnetic and may include radio frequency control devices. The working fluid pump of this invention may be equipped with frequency converters and may be fitted with radio frequency control devices.

[0058] In summary, this invention utilizes the characteristics of vortex tubes to couple them with a gas waste pressure utilization system and an LNG cold energy comprehensive utilization system, resulting in a compact structure. The cold gas outlet of the vortex tube is used for cooling. Based on the principle of cascaded energy utilization, the energy of the hot gas outlet of the vortex tube is effectively utilized for the LNG cold energy comprehensive utilization system. LNG expansion generates electricity, and the waste heat of the hot gas is used to reheat the cold gas, providing gas for users. Simultaneously, LNG absorbs the heat released during the interstage cooling process of the cold energy comprehensive utilization system, maximizing the overall system's energy utilization rate. Furthermore, the diversity of the gas waste pressure utilization system and the LNG cold energy comprehensive utilization system means the system can be flexible and adaptable. The energy supply method can be adjusted according to actual needs by regulating the valves at the hot gas end of the vortex tube, the gas flow rate, and the LNG pump flow rate. The system described in this invention has a high energy utilization rate, using high-pressure gas as an energy source. While reducing carbon emissions, it meets users' electricity, cooling, heating, and gas needs. The system configuration can be flexibly changed according to actual needs, and it is environmentally friendly, saving energy and reducing emissions.

Claims

1. A system for the comprehensive utilization of residual gas pressure and LNG cold energy, characterized in that, It includes a vortex tube (1), a first heat exchanger (2), an expander (4), a second heat exchanger (7), a turbine (8), a third heat exchanger (9), and a fourth heat exchanger (10); the first heat exchanger (2), the expander (4), and the second heat exchanger (7) form a loop; the turbine (8) is connected between the second heat exchanger (7) and the third heat exchanger (9), and the fourth heat exchanger (10) is connected between the first heat exchanger (2) and the third heat exchanger (9); the inlet of the vortex tube (1) is connected to high-pressure gas, which converts the high-pressure gas into cold gas and hot gas; The hot gas flow is sent into the first heat exchanger (2). In the circuit, the organic working medium absorbs the heat exchanged by the first heat exchanger (2), expands and does work in the expander (4), and after doing work, the organic working medium exchanges heat with the low-temperature LNG in the second heat exchanger (7). After the heat exchange, the organic working medium enters the first heat exchanger (2) to absorb heat again. After the heat exchange, the low-temperature LNG does work and generates electricity in the turbine (8). The cold gas flow is sent into the fourth heat exchanger (10) to exchange heat with the outlet gas of the first heat exchanger (2). The gas cooled by the fourth heat exchanger (10) is sent into the third heat exchanger (9) to exchange heat with the low-temperature LNG after power generation. Both the gas and LNG after heat exchange are used as terminal gas. The cold gas flow heated by the fourth heat exchanger (10) is merged into the terminal gas obtained by the third heat exchanger (9), or it can be used as terminal gas alone.

2. The gas waste pressure and LNG cold energy integrated utilization system according to claim 1, characterized in that, The system also includes a cryogenic LNG tank (5), which is used to store and pump cryogenic LNG into a second heat exchanger (7) to exchange heat with the organic working fluid after work.

3. The gas waste pressure and LNG cold energy integrated utilization system according to claim 1, characterized in that, The heat source side inlet of the first heat exchanger (2) is connected to the hot gas outlet of the vortex tube (1), which is the heat source inlet of the LNG cold energy integrated utilization system. The organic working fluid outlet of the first heat exchanger (2) is connected to the inlet of the expander (4). The gaseous organic working fluid expands and does work in the expander (4). The outlet of the organic working fluid after expansion and work is connected to the heat source side inlet of the second heat exchanger (7). The cold source side inlet of the second heat exchanger (7) is connected to the low temperature LNG. The working fluid after heat exchange in the second heat exchanger (7) is pumped into the first heat exchanger (2) to participate in the heat exchange cycle.

4. The method for comprehensive utilization of gas waste pressure and LNG cold energy based on the gas waste pressure and LNG cold energy comprehensive utilization system according to claim 1, characterized in that, The process is as follows: High-pressure gas is sent into the vortex tube (1) through the gas pipeline and divided into two fluids: cold gas and hot gas. The cold gas is used for cooling, and the hot gas is used for heating the circuit. The hot gas is sent into the first heat exchanger (2). The organic working medium absorbs the heat exchanged by the first heat exchanger (2) and expands in the expander (4) to do work, driving the generator to generate electricity. The cooled organic working medium after doing work is supplied to the second heat exchanger (7). In the second heat exchanger (7), it exchanges heat with the low-temperature LNG and condenses from gaseous to liquid. The released heat is absorbed by the LNG. After the heat exchange, the organic working medium enters the first heat exchanger (2) to absorb heat again. After the heat exchange, the low-temperature LNG does work in the turbine (8) to generate electricity. The cold gas flow is sent to the fourth heat exchanger (10) to exchange heat with the outlet gas of the first heat exchanger (2). The gas cooled by the fourth heat exchanger (10) is sent to the third heat exchanger (9) to exchange heat with the low-temperature LNG after power generation. Both the gas and LNG after heat exchange are used as terminal gas. The cold gas flow heated by the fourth heat exchanger (10) is merged into the terminal gas obtained by the third heat exchanger (9), or it can be used as terminal gas alone.

5. The method for comprehensive utilization of residual gas pressure and LNG cold energy according to claim 4, characterized in that, The pressure range of the high-pressure gas is between 0.8 and 2.5 MPa, the temperature range of the cold gas flow is between -50°C and -10°C, the temperature range of the hot gas flow is above 200°C, the temperature range of the resulting terminal gas is between 15°C and 25°C, and the pressure range is between 2000 Pa and 10000 Pa.

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