An adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat

Abstract

The application discloses a kind of self-adaptive zero-carbon power generation system using LNG cold energy and flue gas waste heat, belong to LNG cold energy utilization technology, industrial waste gas treatment waste heat recovery and CO2 capture field, solve the low efficiency of prior art in the recycling of LNG cold energy and flue gas waste heat, it is difficult to effectively treat flue gas to reduce environmental pollution, and power generation system is susceptible to LNG flow fluctuation and other factors and cannot be stably operated.The application constructs self-adaptive zero-carbon power generation system, cooperates with LNG cold energy power generation cycle line and waste heat recovery line, utilizes LNG cold energy and flue gas waste heat, through multi-stage working medium heat exchange, expansion work, also treats flue gas emission reduction, realizes energy efficient utilization and environmental friendliness.The application utilizes LNG cold energy and flue gas waste heat to generate power efficiently, improves energy utilization rate.Synchronously, deeply treat flue gas, reduce pollution emission, and stabilize the system with cold storage medium, realize efficient, environmental protection, stable operation.

Description

Technical Field

[0001] This invention relates to the fields of LNG cold energy utilization technology, industrial waste gas treatment waste heat recovery and CO2 capture technology, and in particular to an adaptive zero-carbon power generation system that utilizes LNG cold energy and flue gas waste heat. Background Technology

[0002] Liquefied natural gas (LNG) is a liquid at atmospheric pressure formed by purifying natural gas and cooling it to -162°C. Before reaching the user, it needs to be heated and vaporized to around 25°C, which releases approximately 830 kJ / kg of cold energy. However, most LNG receiving terminals currently release this cold energy directly into seawater or the air, resulting in a significant waste of this energy.

[0003] Currently, the utilization of LNG cold energy includes cold power generation, alkane separation, dry ice preparation, and cold-water aquaculture. Among these, cold power generation has received extensive research from experts and scholars due to its advantages such as low safety risk and high energy quality. Current methods for LNG cold power generation mainly include direct vaporization expansion (DC) power generation, single-stage organic Rankine cycle (ORC) power generation, and multi-stage ORC power generation. All current LNG cold power generation methods require a stable input of LNG as the cold source. However, domestic LNG receiving terminals are mainly peak-shaving type, with large fluctuations in output, meaning significant fluctuations in the cold source in the cold power generation system. This results in poor system stability, becoming a limiting factor for the widespread application of cold power generation. Existing solutions involve designing LNG storage tanks at the front end of the cold power generation process, but this increases LNG storage costs and poses safety risks. Furthermore, existing LNG cold power generation methods only consider LNG as the front-end cold source and do not consider the coupling utilization of waste gas and waste heat recovery from natural gas combustion with LNG cold energy.

[0004] See Chinese patent document CN106150578A (publication date: 2016-11-23), which discloses a multi-stage coupled LNG cold energy utilization cycle power generation system. This system adopts a three-stage cycle process, in which only the third stage uses seawater as a heat source. This results in a lower initial temperature and pressure of the third-stage cycle medium at the turbine inlet, and a smaller enthalpy difference between the turbine inlet and outlet. Simultaneously, since the first stage cycle is heated by the condensation heat release from the second stage cycle, and the second stage cycle is heated by the condensation heat release from the third stage cycle, the net power generation of the first and second stages is low, resulting in a low overall power generation. When the LNG inlet pressure is 0.6–7 MPa and the mass flow rate is 3600 kg / h, the net power generation per ton of LNG is 66.5–29.74 kWh. Moreover, the LNG leaves the system at a temperature of -53℃ to -47℃, meaning this portion of the cold energy is not utilized.

[0005] Chinese patent document CN115614118B (publication date: 2023-01-17) discloses a cascaded coupling recovery and utilization system for liquefied natural gas (LNG). This system includes a primary, secondary, and tertiary LNG power generation system for organic Rankine cycle (ORC) power generation; a quaternary LNG utilization subsystem for ORC power generation, cold storage refrigeration, and ice making; and a quinary LNG power generation system for direct gasification expansion (DEX) power generation. The primary, tertiary, quaternary, and quinary LNG power generation systems are connected horizontally in parallel, while the secondary LNG power generation system is connected vertically in series with the primary system, achieving cascaded coupling recovery and utilization of LNG cold energy. This system requires an LNG storage tank at the front end to provide a stable LNG cold source with a mass flow rate of 150 t / h, which increases the natural gas storage cost of the system.

[0006] Chinese patent document CN115749978B (publication date: 2023-03-07) discloses a power generation system that utilizes LNG cold energy and industrial waste heat recovery. The system uses high-temperature flue gas generated by coking and steel rolling processes, as well as circulating water from steelmaking and ironmaking, as heat sources. Although it utilizes industrial waste heat, it does not achieve the recovery and capture of water and carbon dioxide in the flue gas from steel plants.

[0007] Current LNG cold energy power generation systems only consider using LNG as the cold source for the power generation system, without considering using low-grade natural gas from other stages of the natural gas industry chain as a heat source; in the process of utilizing LNG cold energy, the use of cold energy to reduce carbon emissions in the natural gas industry chain is not considered; at the same time, current LNG cold energy power generation systems have high requirements for the stability of LNG flow, and the power generation capacity and efficiency are highly dependent on the LNG flow at the cold end. Summary of the Invention

[0008] This invention proposes an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat. It can achieve cascaded cold energy storage, thereby adapting to changes in LNG flow rate at the front-end cold source to reduce LNG storage costs and LNG tank storage pressure. The system utilizes the waste heat from natural gas combustion and LNG cold energy in a cascaded manner to achieve efficient power generation. Furthermore, the system uses LNG cold energy to separate and capture carbon dioxide from flue gas, achieving zero carbon emissions from natural gas flue gas, thus solving the problems existing in the prior art.

[0009] An adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat includes:

[0010] The system includes a primary cold energy power generation cycle line and a secondary cold energy power generation cycle line for realizing steam extraction and regenerative Rankine cycle power generation, a waste heat recovery line for realizing flue gas waste heat recovery, an LNG line for gasifying LNG into gaseous natural gas, and a flue gas treatment line for realizing clean treatment of natural gas combustion flue gas and capture of carbon dioxide.

[0011] The primary cold energy power generation cycle line, the secondary cold energy power generation cycle line, and the flue gas treatment line are connected in series via LNG lines.

[0012] Furthermore, the primary cold energy power generation cycle includes an LNG-first cycle working fluid storage heat exchanger, a first working fluid pump, a first regenerator, a second first working fluid pump, a second first regenerator, a third first working fluid pump, a third cycle working fluid-first cycle working fluid heat exchanger, a first working fluid expander, a first-stage extraction steam regeneration branch, a second-stage extraction steam regeneration branch, and a power generation branch using the first working fluid.

[0013] The inlet of the first working fluid expander is connected to the outlet of the third circulating working fluid-first circulating working fluid heat exchanger. The first outlet of the first working fluid expander is connected to the inlet of the first stage extraction steam regeneration branch. The outlet of the first stage extraction steam regeneration branch is connected to the first inlet of the second first regenerator. The outlet of the second first regenerator is connected to the inlet of the third first working fluid pump.

[0014] The second outlet of the first working fluid expander is connected to the inlet of the second stage extraction steam regeneration branch, the outlet of the second stage extraction steam regeneration branch is connected to the first inlet of the first regenerator, the outlet of the first regenerator is connected to the inlet of the second working fluid pump, and the outlet of the second working fluid pump is connected to the second inlet of the second regenerator.

[0015] The third outlet of the first working fluid expander is connected to the inlet of the LNG-first circulating working fluid storage and heat exchanger. The outlet of the LNG-first circulating working fluid storage and heat exchanger is connected to the inlet of the power generation branch of the first working fluid. The outlet of the power generation branch of the first working fluid is connected to the inlet of the first working fluid pump. The outlet of the first working fluid pump is connected to the second inlet of the first regenerator.

[0016] Furthermore, the secondary cold energy power generation cycle includes an LNG-second cycle working fluid storage heat exchanger, a first second working fluid pump, a first second regenerator, a second second working fluid pump, a second second regenerator, a third second working fluid pump, a third cycle working fluid-second cycle working fluid heat exchanger, a second working fluid expander, a first-stage extraction steam regeneration branch, a second-stage extraction steam regeneration branch, and a power generation branch for the second working fluid.

[0017] The outlet of the third circulating working fluid-second circulating working fluid heat exchanger is connected to the inlet of the second working fluid expander. The first outlet of the second working fluid expander is connected to the inlet of the first stage extraction steam regeneration branch. The outlet of the first stage extraction steam regeneration branch is connected to the first inlet of the second regenerator. The outlet of the second regenerator is connected to the inlet of the third working fluid pump. The outlet of the third working fluid pump is connected to the inlet of the third circulating working fluid-second circulating working fluid heat exchanger.

[0018] The second outlet of the second working fluid expander is connected to the inlet of the second stage extraction steam regeneration branch, the outlet of the second stage extraction steam regeneration branch is connected to the first inlet of the first second regenerator, the outlet of the first second regenerator is connected to the inlet of the second working fluid pump, and the outlet of the second working fluid pump is connected to the second inlet of the second regenerator.

[0019] The third outlet of the second working fluid expander is connected to the inlet of the LNG-second circulating working fluid storage and heat exchanger. The outlet of the LNG-second circulating working fluid storage and heat exchanger is connected to the inlet of the second working fluid power generation branch. The outlet of the second working fluid power generation branch is connected to the inlet of the first second working fluid pump. The outlet of the first second working fluid pump is connected to the second inlet of the first second regenerator.

[0020] Furthermore, the waste heat recovery line includes a third working fluid pump, a flue gas-third circulating working fluid heat exchanger, a third circulating working fluid-second circulating working fluid heat exchanger, and a third circulating working fluid-first circulating working fluid heat exchanger, wherein,

[0021] The heat exchanger inlet is connected to the waste heat recovery working fluid, and the heat exchanger outlet is connected to the inlet of the third working fluid pump. The outlet of the third working fluid pump is connected to the waste heat recovery working fluid inlet of the third circulating working fluid-second circulating working fluid heat exchanger and the waste heat recovery working fluid inlet of the third circulating working fluid-first circulating working fluid heat exchanger. Both the third circulating working fluid-second circulating working fluid heat exchanger and the third circulating working fluid-first circulating working fluid heat exchanger are equipped with waste heat recovery working fluid outlets.

[0022] Furthermore, the LNG line includes an LNG pump, an LNG-first circulating medium cold storage heat exchanger, an LNG-second circulating medium cold storage heat exchanger, an NG-dehydrated flue gas heat exchanger, an NG-flue gas heat exchanger, and a seawater-NG heat exchanger, wherein,

[0023] The LNG pump inlet introduces liquefied natural gas (LNG), which is connected to the LNG inlet of the LNG-first circulating medium cold storage heat exchanger. The LNG outlet of the LNG-first circulating medium cold storage heat exchanger is connected to the LNG inlet of the LNG-second circulating medium cold storage heat exchanger. The LNG outlet of the LNG-second circulating medium cold storage heat exchanger is connected to the LNG inlet of the NG-dehydrated flue gas heat exchanger. The LNG outlet of the NG-dehydrated flue gas heat exchanger is connected to the LNG inlet of the NG-flue gas heat exchanger. The LNG outlet of the NG-flue gas heat exchanger is connected to the LNG inlet of the seawater-NG heat exchanger. The LNG outlet of the seawater-NG heat exchanger is connected to the user end.

[0024] Furthermore, the flue gas treatment line includes a flue gas-third circulating working fluid heat exchanger, an NG-flue gas heat exchanger, a flue gas-ice separator, a multi-stage compressor, an LNG-dehydrated flue gas heat exchanger, a dehydrated flue gas-liquid carbon dioxide separator, a cooling tank, a heating tank, a multi-stage expansion stage, and a compensation circuit, wherein,

[0025] The waste heat flue gas inlet of the heat exchanger is introduced with waste heat flue gas from natural gas combustion. The ambient temperature flue gas outlet of the heat exchanger is connected to the ambient temperature flue gas inlet of the heat exchanger. The dehydrated flue gas outlet of the heat exchanger is connected to the dehydrated flue gas inlet of the multi-stage compressor. The high-pressure flue gas outlet of the multi-stage compressor is connected to the high-pressure flue gas inlet of the cooling tank. The medium-temperature flue gas outlet of the cooling tank is connected to the heat measurement inlet of the heat exchanger. The heat measurement outlet of the heat exchanger is connected to the gas-liquid mixing inlet of the separator. The liquid CO2 outlet of the separator is independently connected to the CO2 storage tank. The residual gas outlet of the separator is connected to the residual gas inlet of the multi-stage expander. The expansion gas outlet of the multi-stage expander is connected to the low-temperature gas inlet of the heating tank. The compliant emission outlet of the heating tank is connected to the atmosphere.

[0026] In the compensation circuit, the multi-stage expander acts as an electrical energy output device, and the electrical energy it generates is preferentially supplied to the multi-stage compressor, which acts as an electrical energy input device.

[0027] Furthermore, in the primary cold energy power generation cycle circuit,

[0028] The LNG-first-cycle working fluid storage heat exchanger is used to cool the first-cycle working fluid using the cold energy of LNG, causing the first-cycle working fluid to condense into a saturated liquid. At the same time, it recovers the cold energy of the liquid phase of LNG. When the LNG flow rate is too high, the excess cold energy is stored in the storage medium; when the flow rate is too low, the stored cold energy is released to cool the exhaust steam after the first-cycle working fluid expander has done its work.

[0029] The No. 1 working fluid pump is used to pressurize the saturated liquid working fluid from the LNG-first circulating working fluid storage heat exchanger, increase the working fluid pressure, and provide power for the circulating flow of the working fluid in the system.

[0030] The No. 1 first regenerator is used to preheat the working fluid output from the No. 1 first working fluid pump by exchanging heat with the superheated steam with lower pressure extracted from the second stage extraction steam regenerator branch, thereby increasing the working fluid temperature and recovering the heat from the extraction steam.

[0031] The No. 2 working fluid pump is used to further pressurize the working fluid after it has been preheated by the No. 1 first regenerator, so that the working fluid pressure meets the requirements for entering the No. 2 first regenerator and subsequent circulation, and maintains the circulation pressure of the working fluid in the system.

[0032] The No. 2 First Regenerator is used to exchange heat with the high-pressure superheated steam extracted from the first-stage extraction steam regenerator branch, preheat the working fluid output from the No. 2 First Working Fluid Pump, and increase the initial temperature of the working fluid; at the same time, it enables the extraction steam to be cooled at constant pressure in the No. 2 First Regenerator and completely condense.

[0033] The No. 3 first working fluid pump is used to repressurize the working fluid after it has been preheated by the No. 2 first regenerator, so as to ensure that the working fluid can smoothly enter the third cycle working fluid-first cycle working fluid heat exchanger.

[0034] The third circulating working fluid-first circulating working fluid heat exchanger is used to recover the working fluid by utilizing waste heat. It heats the first circulating working fluid, which has been pressurized by the No. 3 first working fluid pump, into superheated steam, thereby improving the energy grade of the working fluid and preparing it for expansion and work in the first working fluid expander.

[0035] The first working fluid expander is used to expand superheated steam in the first working fluid expander to do work, converting the internal energy of the steam into mechanical energy to drive the generator to generate electricity. During the expansion process, some steam is extracted from different positions for reheating.

[0036] The first-stage extraction steam regeneration branch is used to extract a portion of the high-pressure superheated steam from the first working fluid expander and introduce it into the No. 2 first regenerator for constant pressure cooling and complete condensation. The heat released is used to preheat the first circulating working fluid after the second-stage extraction steam regeneration branch and the first working fluid power generation branch are mixed.

[0037] The second-stage extraction and regeneration branch is used to extract a portion of superheated steam with lower pressure from the first working fluid expander and enter the No. 1 first regenerator for constant pressure cooling and complete condensation. The heat released is used to preheat the first circulating working fluid after condensation in the first working fluid power generation branch, further improving the thermal efficiency of the system.

[0038] The first working medium power generation branch is used to allow the remaining first cycle working medium after it has done work in the first working medium expander to continue to participate in the cycle through the first working medium power generation branch.

[0039] In the secondary cold energy power generation cycle circuit

[0040] The LNG-second cycle working fluid cold storage heat exchanger is used to cool the second cycle working fluid by utilizing the latent heat energy of the LNG gas-liquid phase change, so that the second cycle working fluid condenses into a saturated liquid, realizing the recovery and utilization of the LNG latent heat energy; when the LNG flow rate is too large, the excess cold energy is stored in the cold storage medium; when the flow rate is too small, the stored cold energy is released to cool the exhaust steam after the second working fluid expander has done work.

[0041] The No. 1 second working fluid pump is used to pressurize the saturated liquid working fluid flowing out of the LNG-second circulating working fluid storage heat exchanger, increase the pressure of the working fluid, and provide power for the subsequent circulation of the working fluid in the system, so that it can smoothly enter the next device, the No. 1 second regenerator.

[0042] The No. 1 second regenerator is used to exchange heat with the superheated steam with lower pressure extracted from the second-stage extraction steam regenerator branch. On the one hand, it recovers the heat of this part of the steam and improves energy utilization efficiency. On the other hand, it uses the recovered heat to preheat the second circulating working fluid output from the No. 1 second working fluid pump and increase the temperature of the working fluid.

[0043] The No. 2 working fluid pump is used to further pressurize the second circulating working fluid after it has been preheated by the No. 1 second regenerator, so that the working fluid pressure meets the requirements for entering the No. 2 second regenerator and subsequent circulation, and maintains the circulating pressure of the working fluid in the system.

[0044] The No. 2 second regenerator is used to exchange heat with the high-pressure superheated steam extracted from the first-stage extraction steam regenerator branch, recover the heat of this steam and use it to preheat the second circulating working fluid output from the No. 2 second working fluid pump, further increasing the initial temperature of the working fluid.

[0045] The No. 3 second working fluid pump is used to repressurize the second circulating working fluid after it has been preheated by the No. 2 second regenerator, to ensure that the working fluid can enter the third circulating working fluid-second circulating working fluid heat exchanger with sufficient pressure, so as to provide pressure conditions for the subsequent heating process.

[0046] The third circulating working fluid-second circulating working fluid heat exchanger is used to recover the working fluid by utilizing waste heat, and heats the second circulating working fluid after being pressurized by the No. 3 second working fluid pump into superheated steam, thereby improving the energy grade of the working fluid and enabling it to expand and do work in the second working fluid expander.

[0047] The second working fluid expander is used to expand hot steam in the second working fluid expander to do work, converting the internal energy of steam into mechanical energy, thereby driving the generator to generate electricity; during the expansion process, some steam is extracted from different positions and introduced into the No. 2 second regenerator and the No. 1 second regenerator through the first stage extraction steam regenerator branch and the second stage extraction steam regenerator branch, respectively, to preheat the second circulating working fluid.

[0048] The first-stage extraction steam regeneration branch is used to extract a portion of superheated steam with higher pressure from the second working fluid expander and introduce it into the No. 2 second regenerator. In the No. 2 second regenerator, this portion of steam is cooled at constant pressure and completely condensed. The heat released is used to preheat the second circulating working fluid output from the No. 2 second working fluid pump.

[0049] The second-stage extraction and regeneration branch is used to extract a portion of superheated steam with lower pressure from the second working fluid expander and introduce it into the first second regenerator. In the first second regenerator, the steam is cooled at constant pressure and completely condensed. The heat released is used to preheat the second circulating working fluid output from the first second working fluid pump.

[0050] The second working fluid power generation branch is used to allow the remaining second cycle working fluid after it has done work in the second working fluid expander to continue to participate in the cycle through the second working fluid power generation branch.

[0051] In the waste heat recovery circuit

[0052] The third working fluid pump is used to pressurize the third circulating working fluid after it has been heated by the flue gas-third circulating working fluid heat exchanger.

[0053] The flue gas-third cycle working fluid heat exchanger is used to exchange heat between the high-temperature flue gas generated by natural gas combustion and the third cycle working fluid, heating the third cycle working fluid and cooling the high-temperature flue gas.

[0054] The heat exchanger is used to distribute the high-temperature third circulating working fluid to the third circulating working fluid-second circulating working fluid heat exchanger and the third circulating working fluid-first circulating working fluid heat exchanger, thereby cooling the high-temperature third circulating working fluid.

[0055] The third circulating working fluid-second circulating working fluid heat exchanger is also used to exchange heat between the high-temperature third circulating working fluid from the flue gas-third circulating working fluid heat exchanger and the second circulating working fluid of the secondary cold energy power generation cycle line. After absorbing heat, the second circulating working fluid is heated into superheated steam, which improves its energy grade, and then enters the second working fluid expander to expand and do work.

[0056] The third circulating working fluid-first circulating working fluid heat exchanger is also used to exchange heat between the high-temperature third circulating working fluid from the flue gas-third circulating working fluid heat exchanger and the first circulating working fluid of the first-stage cold energy power generation cycle line. After absorbing heat, the first circulating working fluid is heated into superheated steam, which improves its energy grade, and then enters the first working fluid expander to expand and do work.

[0057] In LNG lines,

[0058] LNG pumps are used to pressurize cryogenic, low-pressure LNG.

[0059] The LNG-first-cycle medium cold storage heat exchanger is also used to cool the first-cycle medium by utilizing the cold energy of the liquid phase of LNG flowing through the LNG pump, causing the first-cycle medium to condense into a saturated liquid, realizing the transfer of cold energy to the first-cycle medium, and providing a cold source for the first-stage cold energy power generation cycle; it also has a cold energy storage function, storing excess cold energy when the LNG flow fluctuates, and releasing it when the LNG flow is insufficient, thus stabilizing the system operation;

[0060] The LNG-second circulation medium cold storage heat exchanger is also used to utilize the latent heat energy of the LNG flowing through the LNG-first circulation medium cold storage heat exchanger to cool the second circulation medium, causing the second circulation medium to condense into a saturated liquid, thus realizing the transfer of cold energy to the second circulation medium and providing a cold source for the secondary cold energy power generation cycle; it also has a cold energy storage function, storing excess cold energy when the LNG flow fluctuates and releasing it when the LNG flow is insufficient, thus stabilizing system operation;

[0061] NG-flue gas heat exchanger is used to achieve heat exchange between natural gas and flue gas. That is, the heat of flue gas is used to heat natural gas, while flue gas is cooled during the heat exchange process. The water in it is cooled into solid ice, thereby removing moisture from the flue gas.

[0062] Seawater-NG heat exchangers are used to heat natural gas using the heat of seawater, ensuring that the output natural gas can enter the user end at a suitable temperature to meet the user's needs.

[0063] In the flue gas treatment line,

[0064] The flue gas-third circulating working fluid heat exchanger is used to recover waste heat from the flue gas. By transferring the heat of the flue gas to the third circulating working fluid, the third circulating working fluid is heated, thereby realizing the recovery and utilization of waste heat and reducing the flue gas temperature.

[0065] NG - Flue gas heat exchanger is used to exchange heat between flue gas and natural gas. It uses the heat of flue gas to heat natural gas and raise the temperature of natural gas, while further lowering the temperature of flue gas and causing water vapor in the flue gas to condense into solid ice, thereby initially dehydrating the flue gas.

[0066] A flue gas-ice separator is used to separate ice particles formed in cooled flue gas to prevent them from entering subsequent equipment.

[0067] A multi-stage compressor compresses the pre-treated flue gas to increase its pressure.

[0068] The LNG-dehydrated flue gas heat exchanger uses the cold energy of LNG to cool the dehydrated flue gas, further cooling the carbon dioxide in the flue gas, while recovering some of the cold energy in the flue gas.

[0069] A dehydrated flue gas-liquid carbon dioxide separator is used to separate liquid carbon dioxide from cooled flue gas to obtain relatively pure carbon dioxide.

[0070] The cooling tank is used to cool the incoming dehydrated flue gas. The cooling medium is water, and the heated water is supplied to the hot end user.

[0071] A multi-stage expansion stage is used to expand the remaining gas after carbon dioxide separation in a multi-stage expander to perform work. Through gas expansion, the internal energy of the gas is converted into mechanical energy, thereby driving other equipment or generating electricity.

[0072] The heating tank is used to heat the remaining gas to room temperature before releasing it into the atmosphere. The heating medium is water, and the cooled water is supplied to the cold end users.

[0073] Furthermore, both the LNG-first circulating working fluid cold storage heat exchanger and the LNG-second circulating working fluid cold storage heat exchanger include a shell, a heat transfer tube bundle, a support assembly, a cold storage medium, and a circulating working fluid. The support assembly is fixedly installed inside the shell, and the heat transfer tube bundle is fixedly installed on the support assembly. The shell is filled with a cold storage medium and a circulating working fluid. The cold storage medium is submerged in the circulating working fluid. When the flow rate of the low-temperature natural gas in the heat transfer tube bundle is too large, the additional cooling capacity is stored in the cold storage medium. When the flow rate of the low-temperature natural gas in the heat transfer tube bundle is too small, the cooling capacity stored in the cold storage medium is used to cool the exhaust steam after expansion and work done in the expander in the cold energy power generation cycle line where it is located.

[0074] The circulating working medium in the LNG-first circulating working medium storage heat exchanger is the first circulating working medium, and the heat transfer tube bundle in the LNG-first circulating working medium storage heat exchanger contains liquefied natural gas that has been pressurized to the vaporization pressure by the LNG pump.

[0075] The circulating working medium in the LNG-second cycle working medium storage heat exchanger is the second cycle working medium. The heat transfer tube bundle in the LNG-second cycle working medium storage heat exchanger contains natural gas that has been heated by the LNG-first cycle working medium storage heat exchanger but still has a low temperature.

[0076] The arrangement of heat transfer tube bundles includes, but is not limited to, in-line, spiral, serpentine, coaxial, and finned types.

[0077] Cold storage media include, but are not limited to, rocks, metals, alloys, or combinations of any two or three of these media.

[0078] Furthermore, the first and second circulating working fluids include C2H4, C2H6, C3H6, C3H8, and C4H. 10CH3F, CH2F2, CHF3, C2H4F2, C2H3F3, C2H2F4, C2HF5, C2F6, C3F8, and mixtures of two or more.

[0079] Furthermore, in the primary cold energy power generation cycle, the steam extraction rate is determined by the following formula:

[0080] α1(h a1 -h a1′ )=(1-α1)(h a1′ -h b1″ )

[0081] α2(h b1 -h b1′ )=(1-α1-α2)(h b1′ -h c1 )

[0082] Where h a1 h a1′ h b1 h b1′ h b1″ h c1 The enthalpy values ​​at points a1, a1′, b1, b1′, b1″, and c1 are respectively used to obtain the steam extraction rate α1 of the first-stage extraction regenerative branch:

[0083]

[0084] The extraction steam rate α2 of the second-stage extraction regenerator branch:

[0085]

[0086] Then the steam volume of the first working medium power generation branch is (1-α1-α2);

[0087] The specific steam extraction rate of the secondary cold energy power generation cycle circuit is determined by the following formula:

[0088] β1(h a2 -h a2′ )=(1-β1)(h a2′ -h b2″ )

[0089] β2(h b2 -h b2′ )=(1-β1-β2)(h b2′ -h c2 )

[0090] Where h a2 h a2′ h b2 h b2′ h b2″h c2 The enthalpy values ​​at points a2, a2′, b2, b2′, b2″, and c2 are respectively used to obtain the steam extraction rate β1 of the first-stage extraction regenerative branch:

[0091]

[0092] The extraction steam rate β2 of the second-stage extraction regenerator branch:

[0093]

[0094] Then the steam quantity of the second working medium power generation branch is (1-β1-β2).

[0095] The beneficial effects of this invention are:

[0096] 1. The present invention provides an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat. Thanks to the cold storage medium 604 in the cold storage heat exchangers H1 and H2, the system achieves cascaded storage of LNG cold energy. When the LNG flow rate as the cold source is too large, the additional cold energy will be stored in the cold storage medium 604. When the LNG flow rate as the cold source is too small, the cold energy stored in the cold storage medium 604 is used to cool the exhaust steam after expansion work in expanders T1 and T2, thereby reducing the power generation system's dependence on the stability of the cold source and reducing the storage cost at the LNG front end.

[0097] 2. The present invention provides an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat. Thanks to the heat exchanger H7, which uses waste heat recovery working fluid to recover waste heat from natural gas combustion flue gas to heat the first and second cycle working fluids to a superheated steam state, the enthalpy difference of the working fluid before and after the expander inlet and outlet is increased, thereby improving the power generation and cold energy utilization rate of the system.

[0098] 3. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat of the present invention benefits from the longitudinal series connection of the primary and secondary cold energy power generation cycle lines, realizing the cascade utilization of LNG cold energy; at the same time, the expanders T1 and T2 adopt a secondary steam extraction and reheat setting, extracting a portion of steam at different pressures from different intermediate positions of the expanders for constant pressure cooling, and the heat released by condensation is used to preheat the first and second cycle working fluids after the cycle power generation, thereby increasing the average heat absorption temperature and improving the utilization rate of cold energy.

[0099] 4. The adaptive zero-carbon power generation system of the present invention utilizes LNG cold energy and flue gas waste heat. Thanks to the pressurization effect of the multi-stage compressor MC and the cooling effect of heat exchangers H3 and H4, water and carbon dioxide in the flue gas are removed and recovered, achieving zero carbon emissions from the flue gas. At the same time, the multi-stage expander ME and the multi-stage compressor MC form a compensation circuit, and the electrical power of the multi-stage expander is preferentially supplied to the multi-stage compressor MC, reducing the demand of the flue gas treatment line on external electrical power. Attached Figure Description

[0100] Figure 1 This is a schematic diagram of the structure of an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to the present invention.

[0101] Figure 2 A schematic diagram of steam extraction and regeneration for the primary and secondary cold energy power generation cycles;

[0102] Figure 3 Schematic diagrams of the LNG-first circulating medium cold storage heat exchanger H1 and the LNG-second circulating medium cold storage heat exchanger H2;

[0103] Figure 4 This is a schematic diagram illustrating the material composition of an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to an embodiment of the present invention, used to achieve cascaded cold energy power generation, flue gas waste heat recovery, and carbon dioxide capture, wherein:

[0104] LNG, LNG_1, LNG_2: Liquefied Natural Gas;

[0105] NG, NG_1, NG_2, NG_3: natural gas;

[0106] WF1_1, WF1_2, WF1_3, WF1_4, WF1_5, WF1_6, WF1_7, WF1_8, WF1_9, WF1_10: Propane;

[0107] WF2_1, WF2_2, WF2_3, WF2_4, WF2_5, WF2_6, WF2_7, WF2_8, WF2_9, WF2_10: Propane;

[0108] w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13: Seawater;

[0109] g1, g2, g3, g4, g5, g6, g7, g8: flue gas.

[0110] Among them, 100 is the primary cold energy power generation cycle line, 200 is the secondary cold energy power generation cycle line, 300 is the waste heat recovery line, 400 is the LNG line, 500 is the flue gas treatment line, H1 is the LNG-first cycle working fluid storage heat exchanger, P3 is the first working fluid pump, R2 is the first regenerator, P4 is the second working fluid pump, R1 is the second regenerator, P2 is the third working fluid pump, H5 is the third cycle working fluid-first cycle working fluid heat exchanger, T1 is the first working fluid expander, 101 is the first stage extraction steam regeneration branch, 102 is the second stage extraction steam regeneration branch, 103 is the power generation branch of the first working fluid, H2 is the LNG-second cycle working fluid storage heat exchanger, P6 is the first second working fluid pump, R4 is the first second regenerator, P7 is the second second working fluid pump, R3 is the second second regenerator, P5 is the third... Two working fluid pumps, H6 is the third circulating working fluid-second circulating working fluid heat exchanger, T2 is the second working fluid expander, 201 is the first stage extraction steam regeneration branch, 202 is the second stage extraction steam regeneration branch, 203 is the second working fluid power generation branch, P8 is the third working fluid pump, H7 is the flue gas-third circulating working fluid heat exchanger, P1 is the LNG pump, H3 is the NG-dehydrated flue gas heat exchanger, H4 is the NG-flue gas heat exchanger, H8 is the seawater-NG heat exchanger, S1 is the flue gas-ice separator, MC is the multi-stage compressor, H3 is the LNG-dehydrated flue gas heat exchanger, S2 is the dehydrated flue gas-liquid carbon dioxide separator, W1 is the cooling tank, W2 is the heating tank, ME is the multi-stage expander, 601 is the shell, 602 is the heat transfer tube bundle, 603 is the support assembly, 604 is the cold storage medium, 605 is the first circulating working fluid, and 606 is the second circulating working fluid. Detailed Implementation

[0111] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0112] Example 1:

[0113] Figure 1 The diagram shows an adaptive zero-carbon power generation system that utilizes LNG cold energy and flue gas waste heat according to an embodiment of the present invention to achieve cascaded cold energy power generation, flue gas waste heat recovery, and carbon dioxide capture.

[0114] The primary cold energy power generation cycle line 100, the secondary cold energy power generation cycle line 200, and the flue gas treatment line 500 are connected in series via the LNG line 400. LNG flows sequentially through the primary cold energy power generation cycle line, the secondary cold energy power generation cycle line, and the flue gas treatment line, and exchanges heat with the first circulating working medium and cold storage medium in the cold storage heat exchanger H1, the second circulating working medium and cold storage medium in the cold storage heat exchanger H2, the dehydrated flue gas in the heat exchanger H3, and the flue gas in the heat exchanger H4, thereby warming the natural gas and ensuring that the temperature of the vaporized natural gas meets the requirements of the user.

[0115] The specific primary cold energy power generation cycle line 100 includes LNG-first cycle working fluid storage heat exchanger H1, first working fluid pump P3, first regenerator R2, second working fluid pump P4, second regenerator R1, third working fluid pump P2, third cycle working fluid-first cycle working fluid heat exchanger H5, first working fluid expander T1, first stage extraction steam regeneration branch 101, second stage extraction steam regeneration branch 102, and power generation first working fluid power generation branch 103;

[0116] The secondary cold energy power generation cycle line 200 includes an LNG-second cycle working fluid storage and heat exchanger H2, a first second working fluid pump P6, a first second regenerator R4, a second second working fluid pump P7, a second second regenerator R3, a third second working fluid pump P5, a third cycle working fluid-second cycle working fluid heat exchanger H6, a second working fluid expander T2, a first-stage extraction steam regeneration branch 201, a second-stage extraction steam regeneration branch 302, and a power generation branch 203 for the second working fluid.

[0117] The waste heat recovery line 300 includes a third working fluid P8, a flue gas-third circulating working fluid heat exchanger H7, a third circulating working fluid-second circulating working fluid heat exchanger H6, and a third circulating working fluid-first circulating working fluid heat exchanger H5.

[0118] LNG line 400 includes LNG pump P1, LNG-first circulating medium cold storage heat exchanger H1, LNG-second circulating medium cold storage heat exchanger H2, NG-dehydrated flue gas heat exchanger H3, NG-flue gas heat exchanger H4, and seawater-NG heat exchanger H8.

[0119] The flue gas treatment line 500 includes a flue gas-third circulating working fluid heat exchanger H7, an NG-flue gas heat exchanger H4, a flue gas-ice separator S1, a multi-stage compressor MC, an LNG-dehydrated flue gas heat exchanger H3, a dehydrated flue gas-liquid carbon dioxide separator S2, a multi-stage expansion stage ME, and a compensation circuit between ME and MC.

[0120] The workflow of an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to an embodiment of the present invention is as follows:

[0121] After being pressurized to vaporization pressure by LNG pump P1, liquefied natural gas (LNG) flows sequentially through LNG-first cycle working fluid storage and heat exchanger H1, LNG-second cycle working fluid storage and heat exchanger H2, NG-dehydrated flue gas heat exchanger H3, flue gas-NG heat exchanger H4, and seawater-NG heat exchanger H8 to absorb heat and vaporize to a suitable temperature for downstream users before entering the user's terminal through the outlet. Specifically, storage and heat exchanger H1 recovers the latent heat of LNG, storage and heat exchanger H2 recovers the low-temperature vapor phase heat of LNG, and heat exchangers H3, H4, and H8 recover the high-temperature vapor phase heat of natural gas. In this sequential process, the natural gas is heated to a suitable temperature for downstream users.

[0122] In the primary cold energy power generation cycle 100, the first circulating working fluid is pressurized by pump P2 and heated into superheated steam by heat exchanger H5. It then expands and performs work in expander T1. A portion of the superheated steam with higher pressure is extracted from the expander and enters the second primary regenerator R1 via branch 101 for constant-pressure cooling and complete condensation, preheating the first circulating working fluid mixed in branches 102 and 103. Then, a portion of the superheated steam with lower pressure is extracted from expander T1 and enters the first primary regenerator R2 via branch 102 for constant-pressure cooling. The first circulating working fluid in branch 103 is cooled, completely condensed, and preheated. The remaining first circulating working fluid expands completely in expander T1 to do work. The expanded gas-liquid mixture enters the cold storage heat exchanger H1 for heat exchange and condenses into a saturated liquid. After passing through pump P3, it enters the first regenerator R2 through branch 103 and mixes with the first circulating working fluid that has been cooled and condensed in branch 102. After passing through pump P4, it enters the second regenerator R1 and mixes with the first circulating working fluid that has been cooled and condensed in branch 101 for heat exchange. After passing through pump P2, it enters the next cycle.

[0123] Specific steam extraction regeneration, such as Figure 2 As shown, the specific steam extraction rate is determined by the following formula:

[0124] α1(h a1 -h a1′ )=(1-α1)(h a1′ -h b1″ )

[0125] α2(h b1 -h b1′ )=(1-α1-α2)(h b1′ -h c1 )

[0126] Thus, the extraction steam rate α1 of branch 101 is obtained:

[0127]

[0128] Steam extraction rate α2 of branch line 102:

[0129]

[0130] Then the steam volume of branch 103 is (1-α1-α2);

[0131] The specific working fluids for the first cycle include, but are not limited to, C2H4, C2H6, C3H6, C3H8, and C4H. 10 CH3F, CH2F2, CHF3, C2H4F2, C2H3F3, C2H2F4, C2HF5, C2F6, C3F8, and mixtures of two or more.

[0132] The specific LNG-first cycle working fluid storage heat exchanger H1, such as Figure 3 As shown, the system consists of a shell 601, a heat transfer tube bundle 602, and a support assembly 603. The shell is filled with a cold storage medium 604 and a first circulating working fluid 605. The heat transfer tube bundle 602 contains liquefied natural gas that has been pressurized to the vaporization pressure by pump P1. The heat transfer tube bundle 602 is fixed to the support assembly 603. The cold storage medium 604 is submerged in the first circulating working fluid 605.

[0133] The cold storage medium 604 includes, but is not limited to, various rocks such as limestone and granite, as well as metals and alloys such as steel blocks and iron blocks;

[0134] Specifically, in the cold storage heat exchanger H1, liquefied natural gas, pressurized to the vaporization pressure by pump P1, enters the heat transfer tube bundle through the tube side inlet of the cold storage heat exchanger H1 and exchanges heat with the cold storage medium 604 and the first circulating working fluid 605 filled inside the shell. The cold storage is that when the flow rate of LNG as the cold source is too large, the additional cold energy is stored in the cold storage medium 604. When the flow rate of LNG as the cold source is too small, the cold energy stored in the cold storage medium 604 is used to cool the exhaust steam after expansion and work in the expander T1.

[0135] In the secondary cold energy power generation cycle 200, the second circulating working fluid is pressurized by pump P5 and heated into superheated steam by heat exchanger H6. It then expands and performs work in expander T2. A portion of the high-pressure superheated steam is extracted from the expander and enters the second regenerator R3 via branch 201 for constant-pressure cooling and complete condensation, preheating the second circulating working fluid mixed in branches 202 and 203. A portion of the lower-pressure superheated steam is then extracted from the expander and enters the first regenerator R4 via branch 202 for constant-pressure cooling. However, the second circulating working fluid, which is completely condensed and preheated in branch 203, expands completely in expander T2 to do work. The expanded gas-liquid mixture enters the cold storage heat exchanger H2 for heat exchange and condenses into a saturated liquid. After passing through pump P6, it enters branch 203 into the first second regenerator R4 and mixes with the second circulating working fluid that has cooled and condensed in branch 202. After passing through pump P4, it enters the second second regenerator R3 and mixes with the second circulating working fluid that has cooled and condensed in branch 201 for heat exchange. After passing through pump P5, it enters the next cycle.

[0136] Similar to the first-stage cold energy power generation cycle 100, the specific steam extraction rate of the second-stage cold energy power generation cycle 200 is determined by the following formula:

[0137] β1(h a2 -h a2′ )=(1-β1)(h a2′ -h b2″ )

[0138] β2(h b2 -h b2′ )=(1-β1-β2)(h b2′ -h c2 )

[0139] Thus, the extraction steam rate β1 of branch 201 is obtained:

[0140]

[0141] Steam extraction rate β2 of branch line 202:

[0142]

[0143] Then the steam volume of branch 203 is (1-β1-β2);

[0144] Specific second-cycle working fluids include, but are not limited to, C2H4, C2H6, C3H6, C3H8, and C4H. 10 CH3F, CH2F2, CHF3, C2H4F2, C2H3F3, C2H2F4, C2HF5, C2F6, C3F8, and mixtures of two or more.

[0145] The specific LNG-second cycle working fluid storage heat exchanger H2 consists of a shell 601, a heat transfer tube bundle 602, and a support assembly 603. The shell is filled with a cold storage medium 604 and a second cycle working fluid 605. The heat transfer tube bundle 602 contains natural gas that has been heated by the cold storage heat exchanger H1 but still has a low temperature. The heat transfer tube bundle is fixed to the support assembly 603. The cold storage medium 604 is submerged in the second cycle working fluid 605.

[0146] The specific cold storage medium 604 includes, but is not limited to, rocks such as limestone, granite, and dolomite, metals such as steel, iron, aluminum, and copper, and alloys such as stainless steel, iron-nickel alloys, copper-nickel alloys, and iron-cobalt alloys;

[0147] Specifically, in the cold storage heat exchanger H2, the natural gas, which has been heated by the cold storage heat exchanger H1 but still has a low temperature, enters the heat transfer tube bundle through the tube side inlet of the cold storage heat exchanger H2 and exchanges heat with the cold storage medium 604 and the second circulating working fluid 605 filled inside the shell. The cold storage means that when the flow rate of the low-temperature natural gas in the tube side is too large, the extra cold energy is stored in the cold storage medium 604. When the flow rate of the low-temperature natural gas in the tube side is too small, the cold energy stored in the cold storage medium 604 is used to cool the exhaust steam after expansion and work in the expander T2.

[0148] In the waste heat recovery line 300, the waste heat recovery working medium enters the heat exchanger H7 and is heated. After being pressurized by the pump P8, it enters the separator S3 for separation. Part of it enters the heat exchanger H6 and is cooled, and the other part enters the heat exchanger H5 and is cooled. The outlets of the heat exchangers H5 and H6 are the cooled waste heat recovery working medium.

[0149] Specifically, water is preferred as the working fluid for waste heat recovery, and the cooled water can be supplied to cold-end users.

[0150] In LNG line 400, liquefied natural gas (LNG) is pressurized to vaporization pressure by LNG pump P1 and then flows sequentially through LNG-first circulating working fluid storage and heat exchanger H1, LNG-second circulating working fluid storage and heat exchanger H2, NG-dehydrated flue gas heat exchanger H3, flue gas-NG heat exchanger H4, and seawater-NG heat exchanger H8 to absorb heat and vaporize to a suitable temperature for downstream users before entering the user's end through the outlet. Specifically, storage and heat exchanger H1 recovers the latent heat of LNG, storage and heat exchanger H2 recovers the low-temperature vapor phase of LNG, and heat exchangers H3, H4, and H5 recover the high-temperature vapor phase of natural gas. In this sequence, the natural gas is heated to a suitable temperature for downstream users.

[0151] In the flue gas treatment line 500, the waste heat flue gas from natural gas combustion is cooled to room temperature by heat exchanger H7; then it is cooled to sub-zero temperature by heat exchanger H4, where water in the flue gas is cooled into solid ice; after passing through separator S1, the low-temperature gas after removing the solid ice enters multi-stage compressor MC; the dehydrated flue gas is compressed to high pressure by multi-stage compressor MC, and the pressurized dehydrated flue gas enters cooling tank W1 for cooling; after passing through heat exchanger H3, it is cooled to about -20℃, where carbon dioxide in the dehydrated flue gas is liquefied; after passing through separator S2, the liquid carbon dioxide is separated from the gaseous residual gas; the remaining gas enters multi-stage expander ME for expansion and work, and the expanded gas enters heating tank W2 for heating to room temperature before being discharged into the atmosphere.

[0152] Specifically, the cooling tank W1 is filled with a cooling medium, preferably water, and the heated water can be supplied to the hot end user;

[0153] Specifically, the cooling tank W2 is filled with a heating medium, preferably water, and the cooled water can be supplied to the cold end user;

[0154] The main components of the remaining gas are nitrogen and oxygen.

[0155] Specifically, the multi-stage expander ME and the multi-stage compressor MC form a compensation circuit; the compensation circuit prioritizes the power generated by the multi-stage expander ME to supply the multi-stage compressor MC.

[0156] The following example further illustrates the effectiveness of an adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to an embodiment of the present invention:

[0157] Specific example 1:

[0158] Assume that this adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat has an LNG gasification capacity of 150 tons per hour. The LNG is directly extracted from a peak-shaving LNG receiving terminal. The incoming LNG temperature is -162℃, the pressure is 0.1MPa, and the mass flow rate is unstable, assuming a variation range of 150t (±10%) t / h. The pressure requirement for long-distance natural gas pipeline transportation is 7MPa, and the temperature of the LNG after gasification in this system must not be lower than 5℃. In this specific example, the initial temperature of the seawater used as the waste heat recovery medium is 15℃, and the initial temperature of the natural gas combustion flue gas is 150℃. The specific components are shown in Table 1.

[0159] water 26.08 carbon dioxide 6.52 Nitrogen 63.55 oxygen 3.85

[0160] Table 1. Composition of Natural Gas Combustion Flue Gas

[0161] First, when the LNG inflow mass flow rate remains stable at 150 t / h, the system's energy... And mass flow analysis. An embodiment of the present invention utilizes an adaptive zero-carbon power generation system based on LNG cold energy and flue gas waste heat to achieve cascaded cold energy power generation, flue gas waste heat recovery, and carbon dioxide capture. Specific material components are as follows: Figure 4 As shown.

[0162] The LNG is pressurized by LNG pump P1 to reach a vaporization pressure of 7MPa and a temperature of -160℃. It then enters the LNG-first circulating working fluid storage heat exchanger H1 in the first-stage cold energy power generation cycle and is heated to -95℃. It then enters the LNG-second circulating working fluid storage heat exchanger H2 in the second-stage cold energy power generation cycle and is heated to -55℃. Subsequently, it enters the LNG-dehydrated flue gas heat exchanger H3 and is heated to -38℃. It then enters the flue gas-NG heat exchanger H4 and is heated to -6℃. Finally, it enters the flue gas-NG heat exchanger H8 and is heated to 5℃.

[0163] First-stage cold energy power generation cycle: Assume that propane is used as the working fluid in the first cycle of the first-stage cold energy power generation cycle. Propane expands and does work in expander T1. Superheated propane vapor (α1 = 15.7%, pressure 275.51 kPa, temperature -10°C) is extracted from expander T1 and enters the second first regenerator R1 via branch 101 for constant-pressure cooling and complete condensation, preheating the propane mixture in branches 102 and 103. Then, propane vapor (α2 = 14.1%, pressure 70.56 kPa, temperature -50°C, dryness fraction 98.05%) is extracted from the expander and enters the first regenerator R2 via branch 102 for constant-pressure cooling and complete condensation, preheating the condensed propane in branch 103. The remaining (1-α1-α2) = 70.2% propane vapor is further processed in expander T1. The expander T1 performs work after complete expansion. At the end of the expansion, the exhaust steam pressure is 6.44 kPa, the temperature is -90°C, and the dryness is 90.4%. The propane gas-liquid mixture in this part enters the LNG-first cycle working fluid storage and heat exchanger H1, where it is cooled and condensed into a saturated liquid. It is then pressurized to 70.56 kPa by pump P3 and enters the first regenerator R2 through branch 103. After mixing with the propane cooled and condensed in branch 102, it is pressurized to 275.51 kPa by pump P4 and enters the second regenerator R1. After mixing with the propane cooled and condensed in branch 101, it is pressurized to 1 MPa by pump P2 and then enters the heat exchanger H5, where it is heated to 40°C before entering the next cycle.

[0164] The cold storage heat exchanger H1 consists of a shell, a heat transfer tube bundle, and a support assembly. The heat transfer tube bundle contains pressurized cryogenic LNG and is fixed to the support assembly. The shell is filled with limestone and submerged in propane.

[0165] The interior of the cold storage heat exchanger H1 is a cylindrical space with a diameter of 15m and a height of 10m, filled with limestone particles with an average diameter of 20mm, an average porosity of 40%, and a filling ratio of 80%. The thermal properties of the limestone are shown in Table 2.

[0166]

[0167] Table 2 Physical property parameters of various rocks

[0168] The mass of limestone filling the cold storage heat exchanger H1 is:

[0169] m stone =π × 7.5 2 ×10×80%×(1-40%)×2740=2324.1t

[0170] When the system is operating stably, both the propane and the limestone filling in the cold storage heat exchanger H1 maintain a stable temperature of -90℃. The physical properties of the propane at this time are shown in Table 3.

[0171]

[0172] Table 3. Physical properties of propane at various temperatures.

[0173] At this time, the mass of propane filled in the cold storage heat exchanger H1 is:

[0174] m propane =π × 7.5 2 ×10×80%×40%×633.32=358.13t

[0175] Secondary Cold Energy Power Generation Cycle: Assume that propane is used as the working fluid in the second cycle of the secondary cold energy power generation cycle. Propane expands and does work in expander T2. Superheated propane vapor (β1 = 8%) at a pressure of 275.51 kPa and a temperature of -10°C is extracted from expander T2 and enters the second regenerator R3 via branch 201 for constant-pressure cooling and complete condensation, preheating the propane mixture in branches 202 and 203. Then, superheated propane vapor (β2 = 8%) at a pressure of 155.38 kPa and a temperature of -30°C is extracted from the expander and enters the first regenerator R4 via branch 202 for constant-pressure cooling and complete condensation, preheating the condensed propane in branch 203. The remaining (1-β1-β2) = 84% propane vapor completely expands in expander T2. The exhaust steam pressure at the end of the expansion is 70.56 kPa, the temperature is -50°C, and the dryness is 98.05%. This portion of the propane gas-liquid mixture enters the LNG-second cycle working fluid storage and heat exchanger H2, where it is cooled and condensed into a saturated liquid. Subsequently, it is pressurized to 155.38 kPa by pump P6 and enters the No. 1 second regenerator R4 through branch 103. After mixing with the propane cooled and condensed in branch 202, it is pressurized to 275.51 kPa by pump P7 and enters the No. 2 second regenerator R3. After mixing with the propane cooled and condensed in branch 201, it is pressurized to 1 MPa by pump P5 and then enters the heat exchanger H6, where it is heated to 40°C before entering the next cycle.

[0176] The cold storage heat exchanger H2 consists of a shell, heat transfer tube bundles, and support components. The heat transfer tube bundles contain pressurized cryogenic LNG and are fixed to the support components. The shell is filled with limestone and submerged in propane.

[0177] Similar to cold storage heat exchanger H1, cold storage heat exchanger H2 has an internal cylindrical space with a diameter of 15m and a height of 10m, filled with limestone particles with an average diameter of 20mm, an average porosity of 40%, and a filling ratio of 80%.

[0178] The mass of limestone filling the cold storage heat exchanger H2 is:

[0179] m stone =π × 7.5 2 ×10×80%×(1-40%)×2740=2324.1t

[0180] When the system is operating stably, both the propane and the limestone filling in the cold storage heat exchanger H2 maintain a stable temperature of -50℃. At this time, the mass of propane filling the cold storage heat exchanger H1 is:

[0181] m propane =π × 7.5 2 ×10×80%×40%×633.32=358.13t

[0182] Zero-carbon flue gas treatment circuit: The waste heat flue gas from the combustion of natural gas at a temperature of 150℃ and a pressure of 101.5KPa passes through heat exchanger H7 and is cooled to 20℃; then it passes through heat exchanger H4 and is cooled to -10℃, where the water in the flue gas is cooled into solid ice; after passing through separator S1, the low-temperature gas at -10℃ and a pressure of 101.5KPa, after the solid ice is removed, enters the multi-stage compressor MC; after being compressed once by the multi-stage compressor MC to a high-temperature and high-pressure gas of 125℃ and a pressure of 431KPa, it passes through cooling tank W1 and is cooled to a low-temperature and high-pressure gas of 35℃ and a pressure of 412KPa, then passes through multi-stage compressor MC again and is compressed to a high-temperature and high-pressure gas of 125℃ and a pressure of 940KPa, and then passes through cooling tank W1 again and is cooled to a low-temperature and high-pressure gas of 35℃ and a pressure of 412KPa, where it is further compressed. The gas, initially at a low temperature and high pressure of 910 kPa, is compressed three times by a multi-stage compressor MC to a high temperature and high pressure of 125°C and 2172 kPa. It is then cooled to a low temperature and high pressure of 35°C and 2100 kPa by a cooling tank W1. Entering a heat exchanger H3, it is cooled to a temperature of -20°C and 2025 kPa, while carbon dioxide in the flue gas is liquefied. Passing through a separator S2, the liquid carbon dioxide is separated from the remaining gaseous gas. The remaining gas then enters a multi-stage expander ME and expands once to a low temperature and low pressure of -43°C and 1395 kPa. After being heated by a heating tank W2, it reaches a normal temperature and low pressure of 5°C and 1326 kPa. This expansion process is repeated four times until the gas is discharged at a normal temperature and pressure of 5°C and 101 kPa.

[0183] The preferred cooling medium for cooling tank W1 is water. The inlet water is at room temperature (15°C, 101.3 kPa), which is then heated to 100°C (101.3 kPa) by high-temperature gas from the outlet of the multi-stage compressor MC. This water is then available to users at the heat end.

[0184] Water is preferred as the cooling medium in the heating tank W2. The inlet water is room temperature water at 15°C and 101.3 kPa. After being cooled in stages by low-temperature gas at the outlet of the multi-stage expander ME, the water is cooled to a low temperature of 10°C and 101.3 kPa, which can be used by cold-end users and can be used for cold-water aquaculture, etc.

[0185] Waste heat recovery circuit: Room temperature water at 15℃ and pressure of 101KPa enters heat exchanger H7 and is heated to 50℃ and pressure of 101KPa. The high temperature water is then pressurized to 300KPa by pump P7 and separated by separator S3. It then flows through heat exchangers H6 and H5 and is cooled to 10℃ before being discharged. This low temperature water can be used by cold end users and can be used for cold water aquaculture, etc.

[0186] In this specific example, the narrow-point temperature difference between all heat exchangers and condensers is greater than or equal to 5°C, the expander's adiabatic efficiency is 0.8, and heat and friction losses at all system components and connections are ignored, as are the heat loss during the separation process. loss.

[0187] Calculations show that when the LNG inflow is stable at 150 t / h, the propane flow rate in the first-stage cold energy power generation cycle is 114 t / h, and the propane flow rate in the second-stage cold energy power generation cycle is 116 t / h. This can generate 14 t / h of high-temperature water at 100°C for hot-end users and 1950 t / h of cold water at 10°C below ambient temperature for cold-end users. At the same time, it can process 160 t / h of flue gas and capture 28.3 t / h of ice and 17.3 t / h of carbon dioxide.

[0188] The power output of expander T1 in the primary cold energy power generation cycle is W. T1 The power generation capacity of expander T2 in the secondary cold energy power generation cycle is W. T2 The power of pumps P1 to P7 are respectively W P1 To W P7 The power of the multi-stage compressor MC in the zero-carbon flue gas treatment circuit is W. MC The power of the multi-stage compressor ME is W. ME Then the total power generation is:

[0189] W net =W T1 +W T2 +W ME -W P1 -W P2 -W P3 -W P4 -W P5 -W P6 -W P7 -W MC

[0190] The enthalpy of the LNG stream is H LNG The enthalpy of natural gas is H. NG The amount of cold energy released before and after LNG vaporization is:

[0191] Q LNG =H LNG -H NG_4

[0192] The cooling capacity provided by this system is defined as follows:

[0193] Q C =(H w4 -H w5 )+(H w6 -H w7 )+(Hw10 -H w11 )+(H w12 -H w13 )

[0194] The heat provided by this system is defined as:

[0195] Q H =H w9 -H w8

[0196] LNG entering the system The value is E LNG NG The value is E NG_4 Then the system Efficiency is:

[0197]

[0198] Among them, the power generation system Efficiency is:

[0199]

[0200] The system's cold energy utilization rate is:

[0201]

[0202] Calculated using the above formula, the power generation system's output power is 9096 kW, and the net power generation power is 2886 kW. (LNG and NG-1) The power difference is 9203.75 kW, between LNG and NG-4. The power generation system has a power difference of 26516.25 kW. The efficiency is 46.77%. The cooling capacity released before and after LNG vaporization is 31,193 kW, and the system's cooling energy utilization rate is 64%. It can also capture 17.3 t / h of carbon dioxide and produce 28.3 t / h of ice.

[0203] In this specific example, the composition of LNG in the system is shown in Table 4:

[0204] methane 92.11 Ethane 4.17 propane 2.43 Isobutane 0.54 n-Butane 0.55 isopentane 0.2

[0205] Table 4. Specific Components of LNG

[0206] The parameters of each LNG stream component in this specific example are shown in Table 5:

[0207]

[0208] Table 5 Parameter Table of Logistics Components

[0209] The parameters of each component of the first circulating medium WF1 in this specific example are shown in Table 6:

[0210]

[0211]

[0212] Table 6 shows the parameters of the first circulating medium WF1 stream components. When the system is running stably, both the propane and the limestone filling in the cold storage heat exchanger H1 maintain a stable temperature of -90℃. The parameters of each component of the second circulating medium WF2 stream in this specific example are shown in Table 7.

[0213]

[0214] Table 7 shows the parameters of the first circulating medium WF2 stream components. When the system is running stably, both the propane and the limestone filling in the cold storage heat exchanger H2 maintain a stable temperature of -50℃. The parameters and composition of each flue gas stream component in this specific example are shown in Table 8.

[0215]

[0216]

[0217] Table 8 shows the parameters and composition of each flue gas stream component. In this specific example, the parameters and composition of each water stream are shown in Table 9.

[0218]

[0219] Table 9. Parameters of water flow

[0220] This invention, as a novel LNG cold energy utilization process system, utilizes the cold energy of natural gas and the waste heat from combustion flue gas through a cold-thermal-electric coupling. Its power generation system is not only more efficient than the organic Rankine cycle using seawater as a heat source in the prior art, but also recovers and utilizes the waste heat from natural gas combustion flue gas and recovers and captures the water and carbon dioxide therein, realizing the design concept of zero carbon, high efficiency and green.

[0221] Furthermore, the aforementioned adaptive behavior is reflected in the following: when the LNG inflow is large, with a mass flow rate of 150 (+10%) t / h equal to 165 t / h, in the cold storage heat exchanger H1:

[0222] m LNG (h LNG_2 -h LNG_1 )=m WF1 (h WF1_3 -h WF1_4 )+ΔQ1

[0223] ΔQ1 represents the cooling capacity of the limestone and propane stored in the cold storage heat exchanger H1, neglecting the temperature difference between the filling limestone and the submerged propane.

[0224] ΔQ1=m stone c p_stone ΔT+m propane c p_propane ΔT

[0225] Based on the above calculation, ΔT = 0.9℃. At this point, the temperature of WF1_4 drops to -90.9℃. The propane parameters at this temperature are shown in Table 10.

[0226] Table 10 Propane parameters of the primary power generation system when LNG flow rate increases by 10%.

[0227] In the cold storage heat exchanger H2:

[0228] m LNG (h NG_1 -h LNG_2 )=m WF2 (h WF2_3 -h WF2_4 )+ΔQ2

[0229] ΔQ2 represents the cooling capacity of the limestone and propane stored in the cold storage heat exchanger H2, neglecting the temperature difference between the filling limestone and the submerged propane.

[0230] ΔQ2=m stone c p_stone ΔT+m propane c p_propane ΔT

[0231] Based on the above calculation, ΔT = 1.1℃. At this point, the temperature of WF2_4 drops to -51.1℃. The propane parameters at this temperature are shown in Table 11.

[0232]

[0233]

[0234] Table 11 Propane parameters of the secondary power generation system when LNG flow rate increases by 10%

[0235] At this time, the power generation system has a power output of 9231 kW, which is 1.5% higher than the power output at a stable flow rate.

[0236] Furthermore, the aforementioned adaptability is reflected in the fact that when the LNG inflow is relatively small, with a mass flow rate of 150(-10%) t / h equal to 135 t / h, in the cold storage heat exchanger H1:

[0237] m LNG (hLNG_2 -h LNG_1 )=m WF1 (h WF1_3 -h WF1_4 )+ΔQ1

[0238] ΔQ1 represents the cooling capacity of the limestone and propane stored in the cold storage heat exchanger H1, neglecting the temperature difference between the filling limestone and the submerged propane.

[0239] ΔQ1=m stone c p_stone ΔT+m propane c p_propane ΔT

[0240] Based on the above calculation, ΔT = -1℃. At this point, the temperature of WF1_4 rises to -89℃. The propane parameters at this point are shown in Table 12.

[0241]

[0242]

[0243] Table 12 Propane parameters of the primary power generation system when LNG flow rate decreases by 10%.

[0244] In the cold storage heat exchanger H2:

[0245] m LNG (h NG_1 -h LNG_2 )=m WF2 (h WF2_3 -h WF2_4 )+ΔQ2

[0246] ΔQ2 represents the cooling capacity of the limestone and propane stored in the cold storage heat exchanger H2, neglecting the temperature difference between the filling limestone and the submerged propane.

[0247] ΔQ2=m stone c p_stone ΔT+m propane c p_propane ΔT

[0248] Based on the above calculation, ΔT = -1.2℃. At this point, the temperature of WF2_4 rises to -48.8℃. The propane parameters at this point are shown in Table 13.

[0249]

[0250] Table 13 Propane parameters of the secondary power generation system when LNG flow rate decreases by 10%.

[0251] At this time, the power generation capacity of the power generation system is 8968 kW, which is 1.4% lower than the power generation capacity under stable flow conditions.

[0252] In this embodiment of the invention, the cold storage heat exchangers H1 and H2 store the extra cooling capacity when the LNG flow rate is too high through the cold storage medium inside the heat exchanger, and release this portion of the cooling capacity to cool the circulating medium when the LNG flow rate is too low, thus ensuring the stable operation of the power generation system and the back-end system. According to the above-mentioned calculations, the cold storage heat exchangers H1 and H2 of the present invention can achieve the following: when the LNG flow rate changes by ±10%, the power output of the power generation system can be controlled within ±1.5% of the change, thus realizing the system's self-adaptation to the LNG flow rate and power generation.

[0253] The specific embodiments of the invention have been described in detail above, but they are only examples, and the invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the invention are also within the scope of this invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of this invention should be covered within the scope of this invention.

Claims

1. An adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat, characterized in that, include: The system includes a primary cold energy power generation cycle line (100) and a secondary cold energy power generation cycle line (200) for realizing steam extraction regenerative Rankine cycle power generation, a waste heat recovery line (300) for realizing flue gas waste heat recovery, an LNG line (400) for gasifying LNG into gaseous natural gas, and a flue gas treatment line (500) for realizing clean treatment of natural gas combustion flue gas and capture of carbon dioxide. The primary cold energy power generation cycle line (100), the secondary cold energy power generation cycle line (200), and the flue gas treatment line (500) are connected in series via the LNG line (400); The primary cold energy power generation cycle (100) includes an LNG-first cycle working fluid storage heat exchanger (H1), a first working fluid pump (P3), a first regenerator (R2), a second first working fluid pump (P4), a second first regenerator (R1), a third first working fluid pump (P2), a third cycle working fluid-first cycle working fluid heat exchanger (H5), a first working fluid expander (T1), a primary cycle first-stage extraction steam regeneration branch (101), a primary cycle second-stage extraction steam regeneration branch (102), and a power generation first working fluid power generation branch (103). The inlet of the first working fluid expander (T1) is connected to the outlet of the third circulating working fluid-first circulating working fluid heat exchanger (H5), the first outlet of the first working fluid expander (T1) is connected to the inlet of the first stage circulating first stage extraction steam regeneration branch (101), the outlet of the first stage circulating first stage extraction steam regeneration branch (101) is connected to the first inlet of the second first regenerator (R1), and the outlet of the second first regenerator (R1) is connected to the inlet of the third first working fluid pump (P2). The second outlet of the first working fluid expander (T1) is connected to the inlet of the second stage extraction steam regeneration branch (102) of the first stage cycle. The outlet of the second stage extraction steam regeneration branch (102) of the first stage cycle is connected to the first inlet of the first regenerator (R2). The outlet of the first regenerator (R2) is connected to the inlet of the second working fluid pump (P4). The outlet of the second working fluid pump (P4) is connected to the second inlet of the second regenerator (R1). The third outlet of the first working fluid expander (T1) is connected to the inlet of the LNG-first circulating working fluid cold storage heat exchanger (H1), the outlet of the LNG-first circulating working fluid cold storage heat exchanger (H1) is connected to the inlet of the power generation branch of the first working fluid (103), the outlet of the power generation branch of the first working fluid (103) is connected to the inlet of the first working fluid pump (P3), and the outlet of the first working fluid pump (P3) is connected to the second inlet of the first regenerator (R2). The secondary cold energy power generation cycle line (200) includes an LNG-second cycle working fluid storage heat exchanger (H2), a first second working fluid pump (P6), a first second regenerator (R4), a second second working fluid pump (P7), a second second regenerator (R3), a third second working fluid pump (P5), a third cycle working fluid-second cycle working fluid heat exchanger (H6), a second working fluid expander (T2), a secondary cycle first stage extraction steam regeneration branch (201), a secondary cycle second stage extraction steam regeneration branch (202), and a power generation branch for the second working fluid (203). The outlet of the third circulating working fluid-second circulating working fluid heat exchanger (H6) is connected to the inlet of the second working fluid expander (T2). The first outlet of the second working fluid expander (T2) is connected to the inlet of the second-stage circulating first-stage extraction steam regeneration branch (201). The outlet of the second-stage circulating first-stage extraction steam regeneration branch (201) is connected to the first inlet of the second regenerator (R3). The outlet of the second regenerator (R3) is connected to the inlet of the third working fluid pump (P5). The outlet of the third working fluid pump (P5) is connected to the inlet of the third circulating working fluid-second circulating working fluid heat exchanger (H6). The second outlet of the second working fluid expander (T2) is connected to the inlet of the second stage extraction steam regeneration branch (202) of the secondary cycle. The outlet of the second stage extraction steam regeneration branch (202) of the secondary cycle is connected to the first inlet of the first second regenerator (R4). The outlet of the first second regenerator (R4) is connected to the inlet of the second working fluid pump (P7). The outlet of the second second working fluid pump (P7) is connected to the second inlet of the second second regenerator (R3). The third outlet of the second working fluid expander (T2) is connected to the inlet of the LNG-second circulating working fluid storage heat exchanger (H2), the outlet of the LNG-second circulating working fluid storage heat exchanger (H2) is connected to the inlet of the second working fluid power generation branch (203), the outlet of the second working fluid power generation branch (203) is connected to the inlet of the first second working fluid pump (P6), and the outlet of the first second working fluid pump (P6) is connected to the second inlet of the first second regenerator (R4).

2. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 1, characterized in that, The waste heat recovery line (300) includes a third working fluid pump (P8), a flue gas-third circulating working fluid heat exchanger (H7), a third circulating working fluid-second circulating working fluid heat exchanger (H6), and a third circulating working fluid-first circulating working fluid heat exchanger (H5), wherein, Waste heat recovery working fluid is introduced into the inlet of the flue gas-third circulating working fluid heat exchanger (H7). The outlet of the flue gas-third circulating working fluid heat exchanger (H7) is connected to the inlet of the third working fluid pump (P8). The outlet of the third working fluid pump (P8) is connected to the waste heat recovery working fluid inlet of the third circulating working fluid-second circulating working fluid heat exchanger (H6) and the waste heat recovery working fluid inlet of the third circulating working fluid-first circulating working fluid heat exchanger (H5). Both the third circulating working fluid-second circulating working fluid heat exchanger (H6) and the third circulating working fluid-first circulating working fluid heat exchanger (H5) are equipped with waste heat recovery working fluid outlets.

3. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 2, characterized in that, The LNG line (400) includes an LNG pump (P1), an LNG-first cycle working fluid cold storage heat exchanger (H1), an LNG-second cycle working fluid cold storage heat exchanger (H2), an NG-dehydrated flue gas heat exchanger (H3), an NG-flue gas heat exchanger (H4), and a seawater-NG heat exchanger (H8), wherein... The inlet of the LNG pump (P1) introduces liquefied natural gas. The outlet of the LNG pump (P1) is connected to the liquefied natural gas inlet of the LNG-first circulating working medium heat exchanger (H1). The liquefied natural gas outlet of the LNG-first circulating working medium heat exchanger (H1) is connected to the liquefied natural gas inlet of the LNG-second circulating working medium heat exchanger (H2). The liquefied natural gas outlet of the LNG-second circulating working medium heat exchanger (H2) is connected to the liquefied natural gas inlet of the NG-dehydrated flue gas heat exchanger (H3). The liquefied natural gas outlet of the NG-dehydrated flue gas heat exchanger (H3) is connected to the liquefied natural gas inlet of the NG-flue gas heat exchanger (H4). The liquefied natural gas outlet of the NG-flue gas heat exchanger (H4) is connected to the liquefied natural gas inlet of the seawater-NG heat exchanger (H8). The liquefied natural gas outlet of the seawater-NG heat exchanger (H8) is connected to the user end.

4. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 3, characterized in that, The flue gas treatment line (500) includes a flue gas-third circulating working fluid heat exchanger (H7), an NG-flue gas heat exchanger (H4), a flue gas-ice separator (S1), a multi-stage compressor (MC), an LNG-dehydrated flue gas heat exchanger (H3), a dehydrated flue gas-liquid carbon dioxide separator (S2), a cooling tank (W1), a heating tank (W2), a multi-stage expander (ME), and a compensation circuit. The waste heat flue gas inlet of the flue gas-third circulating working fluid heat exchanger (H7) is introduced from the natural gas combustion waste heat flue gas. The ambient temperature flue gas outlet of the flue gas-third circulating working fluid heat exchanger (H7) is connected to the ambient temperature flue gas inlet of the NG-flue gas heat exchanger (H4). The dehydrated flue gas outlet of the NG-flue gas heat exchanger (H4) is connected to the dehydrated flue gas inlet of the multi-stage compressor (MC). The high-pressure flue gas outlet of the multi-stage compressor (MC) is connected to the high-pressure flue gas inlet of the cooling tank (W1). The medium-temperature flue gas outlet of the cooling tank (W1) is connected to the heat exchanger of the NG-dehydrated flue gas heat exchanger (H3). The hot-side outlet of the NG-dehydrated flue gas heat exchanger (H3) is connected to the gas-liquid mixing inlet of the dehydrated flue gas-liquid carbon dioxide separator (S2). The liquid CO2 outlet of the dehydrated flue gas-liquid carbon dioxide separator (S2) is independently connected to a CO2 storage tank. The residual gas outlet of the dehydrated flue gas-liquid carbon dioxide separator (S2) is connected to the residual gas inlet of the multi-stage expander (ME). The expanded gas outlet of the multi-stage expander (ME) is connected to the low-temperature gas inlet of the heating tank (W2). The compliant emission outlet of the heating tank (W2) is connected to the atmosphere. In the compensation circuit, the multi-stage expander (ME) acts as an electrical energy output device, and the electrical energy it generates is preferentially supplied to the multi-stage compressor (MC), which acts as an electrical energy input device.

5. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 4, characterized in that, In the primary cold energy power generation cycle line (100), The LNG-first cycle working fluid storage heat exchanger (H1) is used to cool the first cycle working fluid using the cold energy of LNG, so that the first cycle working fluid condenses into a saturated liquid. At the same time, it recovers the cold energy of the liquid phase of LNG. When the LNG flow rate is too high, the excess cold energy is stored in the storage medium. When the flow rate is too low, the stored cold energy is released to cool the exhaust steam after the first working fluid expander (T1) has done work. The No. 1 working fluid pump (P3) is used to pressurize the saturated liquid working fluid from the LNG-first circulating working fluid storage heat exchanger (H1), increase the working fluid pressure, and provide power for the circulating flow of the working fluid in the system. The No. 1 first regenerator (R2) is used to preheat the working fluid output from the No. 1 first working fluid pump (P3) by exchanging heat with the superheated steam with a lower pressure extracted from the second stage extraction steam regenerator branch (102) of the first stage cycle, thereby increasing the working fluid temperature and recovering the heat of the extracted steam. The No. 2 working fluid pump (P4) is used to further pressurize the working fluid after it has been preheated by the No. 1 first regenerator (R2) so that the working fluid pressure meets the requirements for entering the No. 2 first regenerator (R1) and subsequent circulation, and maintains the circulation pressure of the working fluid in the system. The No. 2 first regenerator (R1) is used to exchange heat with the high-pressure superheated steam extracted from the first stage extraction steam regenerator branch (101) of the first stage cycle, preheat the working fluid output from the No. 2 first working fluid pump (P4) and increase the initial temperature of the working fluid; at the same time, it enables the extraction steam to be cooled at constant pressure in the No. 2 first regenerator (R1) and completely condensed. The No. 3 first working fluid pump (P2) is used to repressurize the working fluid after it has been preheated by the No. 2 first regenerator (R1) to ensure that the working fluid can smoothly enter the third circulating working fluid - first circulating working fluid heat exchanger (H5). The third circulating working fluid-first circulating working fluid heat exchanger (H5) is used to recover the working fluid by utilizing waste heat. It heats the first circulating working fluid, which has been pressurized by the No. 3 first working fluid pump (P2), into superheated steam, thereby improving the energy grade of the working fluid and preparing it for expansion and work in the first working fluid expander (T1). The first working fluid expander (T1) is used to expand superheated steam in the first working fluid expander to do work, converting the internal energy of the steam into mechanical energy to drive the generator to generate electricity. During the expansion process, some steam is extracted from different positions for reheating. The first stage of the primary cycle first stage extraction steam regeneration branch (101) is used to extract a portion of superheated steam with higher pressure from the first working fluid expander (T1), introduce it into the second first regenerator (R1) for constant pressure cooling, complete condensation, and release heat to preheat the first cycle working fluid after mixing with the first stage of the primary cycle second stage extraction steam regeneration branch (102) and the first power generation working fluid power generation branch (103); The first-stage second-stage extraction and regeneration branch (102) is used to extract a portion of superheated steam with lower pressure from the first working fluid expander (T1) and enter the first regenerator (R2) for constant pressure cooling and complete condensation. The released heat is used to preheat the first working fluid after condensation in the first working fluid power generation branch (103) to further improve the thermal efficiency of the system. The first working medium power generation branch (103) is used to allow the remaining first cycle working medium after it has done work through the first working medium expander (T1) to continue to participate in the cycle through the first working medium power generation branch (103); In the secondary cold energy power generation cycle line (200), The LNG-second cycle working fluid storage heat exchanger (H2) is used to cool the second cycle working fluid by utilizing the latent heat energy of the LNG during the gas-liquid phase change, causing the second cycle working fluid to condense into a saturated liquid, thus realizing the recovery and utilization of the LNG latent heat energy. When the LNG flow rate is too high, the excess cooling capacity is stored in the storage medium. When the flow rate is too low, the stored cooling capacity is released to cool the exhaust steam after the second working fluid expander (T2) has done its work. The No. 1 second working fluid pump (P6) is used to pressurize the saturated liquid working fluid flowing out of the LNG-second circulating working fluid storage heat exchanger (H2), increase the pressure of the working fluid, and provide power for the subsequent circulation of the working fluid in the system, so that it can smoothly enter the next device, the No. 1 second regenerator (R4). The No. 1 second regenerator (R4) is used to exchange heat with the superheated steam with lower pressure extracted from the second stage extraction steam regenerator branch (202) of the secondary cycle. On the one hand, it recovers the heat of this part of the steam and improves the energy utilization efficiency. On the other hand, it uses the recovered heat to preheat the second cycle working fluid output from the No. 1 second working fluid pump (P6) and increase the temperature of the working fluid. The second working fluid pump (P7) is used to further pressurize the second circulating working fluid after it has been preheated by the first second regenerator (R4), so that the working fluid pressure meets the requirements for entering the second second regenerator (R3) and subsequent circulation, and maintains the circulating pressure of the working fluid in the system. The second regenerator (R3) is used to exchange heat with the high-pressure superheated steam extracted from the first stage extraction regenerator branch (201) of the secondary cycle, recover the heat of this part of the steam and use it to preheat the second cycle working fluid output from the second working fluid pump (P7), further increasing the initial temperature of the working fluid. The No. 3 second working fluid pump (P5) is used to repressurize the second circulating working fluid after it has been preheated by the No. 2 second regenerator (R3), ensuring that the working fluid can enter the third circulating working fluid-second circulating working fluid heat exchanger (H6) with sufficient pressure, so as to provide pressure conditions for the subsequent heating process. The third circulating working fluid-second circulating working fluid heat exchanger (H6) is used to recover the working fluid by utilizing waste heat. It heats the second circulating working fluid, which has been pressurized by the third second working fluid pump (P5), into superheated steam, thereby improving the energy grade of the working fluid and enabling it to expand and do work in the second working fluid expander (T2). The second working fluid expander (T2) is used to expand hot steam in the second working fluid expander (T2) to do work, converting the internal energy of the steam into mechanical energy, thereby driving the generator to generate electricity; during the expansion process, some steam is extracted from different positions and introduced into the No. 2 second regenerator (R3) and the No. 1 second regenerator (R4) through the first stage extraction steam regenerator branch (201) and the second stage extraction steam regenerator branch (202) of the second cycle, respectively, to preheat the working fluid of the second cycle; The first stage extraction and regeneration branch (201) of the secondary cycle is used to extract a portion of superheated steam with higher pressure from the second working fluid expander (T2) and introduce it into the second regenerator (R3). In the second regenerator (R3), this portion of steam is cooled at constant pressure and completely condensed. The heat released is used to preheat the second cycle working fluid output from the second working fluid pump (P7). The second stage extraction and regeneration branch (202) of the secondary cycle is used to extract a portion of superheated steam with a lower pressure from the second working fluid expander (T2) and introduce it into the first second regenerator (R4). In the first second regenerator (R4), the steam is cooled at constant pressure and completely condensed. The heat released is used to preheat the second cycle working fluid output from the first second working fluid pump (P6). The second working medium power generation branch (203) is used to allow the remaining second cycle working medium after it has done work in the second working medium expander (T2) to continue to participate in the cycle through the second working medium power generation branch (203); In the waste heat recovery circuit (300), The third working fluid pump (P8) is used to pressurize the third circulating working fluid after it has been heated by the flue gas-third circulating working fluid heat exchanger (H7). The flue gas-third cycle working fluid heat exchanger (H7) is used to exchange heat between the high-temperature flue gas generated by natural gas combustion and the third cycle working fluid, heating the third cycle working fluid and cooling the high-temperature flue gas. The heat exchanger (S3) is used to distribute the high-temperature third circulating working fluid to the third circulating working fluid-second circulating working fluid heat exchanger (H6) and the third circulating working fluid-first circulating working fluid heat exchanger (H5), thereby cooling the high-temperature third circulating working fluid. The third circulating working fluid-second circulating working fluid heat exchanger (H6) is also used to exchange the high-temperature third circulating working fluid from the flue gas-third circulating working fluid heat exchanger (H7) with the second circulating working fluid of the secondary cold energy power generation cycle line (200). After absorbing heat, the second circulating working fluid is heated into superheated steam, which improves its energy grade and then enters the second working fluid expander (T2) to expand and do work. The third circulating working fluid-first circulating working fluid heat exchanger (H5) is also used to exchange the high-temperature third circulating working fluid from the flue gas-third circulating working fluid heat exchanger (H7) with the first circulating working fluid of the first-stage cold energy power generation cycle line (100). After absorbing heat, the first circulating working fluid is heated into superheated steam, which improves its energy grade and then enters the first working fluid expander (T1) to expand and do work. In the LNG line (400), LNG pump (P1) is used to pressurize cryogenic, low-pressure LNG; The LNG-first cycle working fluid cold storage heat exchanger (H1) is also used to cool the first cycle working fluid using the cold energy of the liquid phase of LNG flowing through the LNG pump (P1), causing the first cycle working fluid to condense into a saturated liquid, realizing the transfer of cold energy to the first cycle working fluid, and providing a cold source for the first-stage cold energy power generation cycle; it also has a cold energy storage function, storing excess cold energy when the LNG flow fluctuates, and releasing it when the LNG flow is insufficient, thus stabilizing the system operation; The LNG-second cycle working fluid cold storage heat exchanger (H2) is also used to utilize the latent heat energy of the LNG flowing through the LNG-first cycle working fluid cold storage heat exchanger (H1) to cool the second cycle working fluid, causing the second cycle working fluid to condense into a saturated liquid, thus realizing the transfer of cold energy to the second cycle working fluid and providing a cold source for the secondary cold energy power generation cycle; it also has a cold energy storage function, storing excess cold energy when the LNG flow fluctuates and releasing it when the LNG flow is insufficient to stabilize system operation; The NG-flue gas heat exchanger (H4) is used to achieve heat exchange between natural gas and flue gas. That is, the heat of the flue gas is used to heat the natural gas, while the flue gas is cooled during the heat exchange process, and the water in it is cooled into solid ice, thereby removing the moisture from the flue gas. The seawater-NG heat exchanger (H8) is used to heat natural gas using the heat of seawater, ensuring that the output natural gas can enter the user end at a suitable temperature to meet the user's needs. In the flue gas treatment line (500), The flue gas-third circulating working fluid heat exchanger (H7) is used to recover waste heat from the flue gas. By transferring the heat of the flue gas to the third circulating working fluid, the third circulating working fluid is heated, thereby realizing the recovery and utilization of waste heat and reducing the flue gas temperature. The NG-flue gas heat exchanger (H4) is used to exchange heat between flue gas and natural gas. It uses the heat of flue gas to heat the natural gas and raise its temperature, while further lowering the flue gas temperature, causing the water vapor in the flue gas to condense into solid ice, thereby initially dehydrating the flue gas. The flue gas-ice separator (S1) is used to separate ice particles formed in the cooled flue gas to prevent ice particles from entering subsequent equipment. A multi-stage compressor (MC) compresses the pre-treated flue gas to increase its pressure. The LNG-dehydrated flue gas heat exchanger (H3) uses the cold energy of LNG to cool the dehydrated flue gas, further cooling the carbon dioxide in the flue gas, while recovering some of the cold energy in the flue gas. The dehydrated flue gas-liquid carbon dioxide separator (S2) is used to separate liquid carbon dioxide from the cooled flue gas, with a capture rate of 99.9%, thereby obtaining carbon dioxide with a purity of 99.9%. The cooling tank (W1) is used to cool the incoming dehydrated flue gas. The cooling medium is water, and the heated water is supplied to the hot end user. A multistage expander (ME) is used to expand the remaining gas after carbon dioxide separation to do work. Through the expansion of the gas, the internal energy of the gas is converted into mechanical energy, thereby driving other equipment or generating electricity. The heating tank (W2) is used to heat the remaining gas to room temperature before releasing it into the atmosphere. The heating medium is water, and the cooled water is supplied to the cold end users.

6. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 5, characterized in that, The LNG-first circulating working fluid cold storage heat exchanger (H1) and the LNG-second circulating working fluid cold storage heat exchanger (H2) both include a shell (601), a heat transfer tube bundle (602), a support assembly (603), a cold storage medium (604), and a circulating working fluid. The support assembly (603) is fixedly installed inside the shell (601), and the heat transfer tube bundle (602) is fixedly installed on the support assembly (603). The shell (601) is filled with the cold storage medium (604) and the circulating working fluid. The cold storage medium (604) is submerged in the circulating working fluid. When the flow rate of the low-temperature natural gas in the heat transfer tube bundle (602) is too large, the extra cold energy is stored in the cold storage medium (604). When the flow rate of the low-temperature natural gas in the heat transfer tube bundle (602) is too small, the cold energy stored in the cold storage medium (604) is used to cool the exhaust steam after expansion and work done in the expander in the cold energy power generation cycle line where it is located. The circulating working medium in the LNG-first circulating working medium storage heat exchanger (H1) is the first circulating working medium (605), and the heat transfer tube bundle (602) in the LNG-first circulating working medium storage heat exchanger (H1) contains liquefied natural gas that has been pressurized to the vaporization pressure by the LNG pump (P1). The circulating working medium in the LNG-second circulating working medium storage heat exchanger (H2) is the second circulating working medium (606), and the heat transfer tube bundle (602) in the LNG-second circulating working medium storage heat exchanger (H2) contains natural gas that has been heated by the LNG-first circulating working medium storage heat exchanger (H1) but still has a low temperature. The heat transfer tube bundle (602) can be arranged in a straight line, spiral, serpentine, sleeve, or finned manner. The cold storage medium (604) includes rock, metal, alloy or any combination of two or three of the rock, metal or alloy.

7. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 6, characterized in that, The first circulating working medium (605) and the second circulating working medium (606) include C2H4, C2H6, C3H6, C3H8, and C4H. 10 A mixture of two or more of the following: CH3F, CH2F2, CHF3, C2H4F2, C2H3F3, C2H2F4, C2HF5, C2F6, and C3F8.

8. The adaptive zero-carbon power generation system utilizing LNG cold energy and flue gas waste heat according to claim 7, characterized in that, In the primary cold energy power generation cycle line (100), the steam extraction rate is determined by the following formula: in They are The enthalpy value of the point is used to obtain the steam extraction rate of the first-stage extraction regenerative branch (101) of the first-stage cycle. : Steam extraction rate of the second-stage extraction regenerative branch (102) of the first-stage cycle : Then the steam volume of the first working fluid power generation branch (103) is: ; The specific steam extraction rate of the secondary cold energy power generation cycle line (200) is determined by the following formula: in They are The enthalpy value of the point is used to obtain the steam extraction rate of the first stage extraction regenerative branch (201) of the secondary cycle. : Steam extraction rate of the second-stage extraction regenerator branch (202) in the secondary cycle : Then the steam volume of the second working fluid power generation branch (203) is: .

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