Green cold energy power generation synergistic process and application thereof

Abstract

The invention provides a synergistic process for green cold energy power generation and application thereof, relates to the technical field of green cold energy power generation, and comprises an intermediate medium power generation process, a cold energy stepped process, a liquid air cold energy recovery process, a BOG cold energy utilization process and a liquid air stepped heating synergistic process. The technical problems that in the prior art, the power generation amount is low and unstable, and electric energy is difficult to store are solved, and the technical effects that the stability of the operation pressure and temperature of the intermediate medium is guaranteed, the gasification amount of the intermediate medium is increased, and the cooling capacity in the power generation process is recycled are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of green cold energy power generation, and particularly to an efficiency-enhancing process for green cold energy power generation and its application. Background Art

[0002] LNG is the abbreviation of liquefied natural gas and contains a large amount of cold energy. The proportion of natural gas in energy consumption has been increasing year by year. Improving energy utilization efficiency, adopting energy-saving technologies, and developing green energy are effective ways to meet policy requirements at present.

[0003] The liquid air energy storage power generation process utilizes the cold energy of LNG to liquefy compressed air into low-pressure liquid air for cold energy storage. According to the electricity price fluctuation, the liquefied air is then subjected to processes such as boosting, gasification, and expansion power generation to release the cold energy for power generation. When operating the liquid air energy storage, the compressed air utilizes the high-order LNG cold energy, and in the low-order high-pressure LNG cold energy gasification process, an intermediate medium and a heat medium are successively used for heat exchange operations, resulting in problems such as unstable change in the operation amount of the intermediate medium, unstable power generation amount, and poor economic benefits of continuous operation.

[0004] The existing liquefied air energy storage process is an intermittent operation. The gaseous intermediate medium utilizes the cold energy of high-pressure LNG to generate a low-temperature liquid intermediate medium, which is then boosted by a pump and enters the intermediate medium gasifier to exchange heat with seawater to generate a gaseous intermediate medium. The gaseous intermediate medium enters a turbine generator for expansion process power generation. After the expansion process operation, the intermediate medium becomes a low-pressure and low-temperature gaseous intermediate medium, and then enters the LNG-intermediate medium gasifier for heat exchange, and finally condenses into a liquid intermediate medium, and so on for reciprocating cycle operation. Since the gasification pressure of the intermediate medium is limited by the seawater temperature, the pressure and temperature of the intermediate medium at the inlet of the turbine generator are not high, resulting in low power generation; due to the large seasonal variation in seawater temperature, the pressure and temperature of the intermediate medium at the inlet of the turbine generator are unstable, resulting in unstable power generation and affecting the stability of the exported electricity quantity; in addition, the electric energy generated by the existing power generation process cannot be stored at the receiving station, resulting in the electric energy generated not being able to exert its best economic value.

[0005] In order to solve the problems of low power generation, unstable power generation, and electric energy storage, the present invention is specifically proposed. Summary of the Invention

[0006] One of the purposes of the present invention is to provide an efficiency-enhancing process for green cold energy power generation, which can not only ensure the stability of the operation pressure and temperature of the intermediate medium, but also increase the gasification amount of the intermediate medium, and at the same time can recover the cold energy in the power generation process. This process effectively improves the economic value of cold energy utilization.

[0007] The second object of the present invention is to provide an application of a green cold energy power generation enhancement process, which has the characteristics of stable continuous operation, high power generation, high economic benefits, energy conservation and consumption reduction.

[0008] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0009] In the first aspect, an enhancement process for green cold energy power generation includes an intermediate medium power generation process, a cold energy ladder process, a liquid air cold energy recovery process, a BOG cold energy utilization process, and a liquid air ladder heating enhancement process;

[0010] The intermediate medium power generation process includes the following steps:

[0011] The liquid intermediate medium after exchanging with the cryogenic high-pressure medium is pressurized by a circulation pump and then enters a heat exchanger to generate high-temperature and high-pressure gas, which enters a steam turbine generator for power generation;

[0012] The cold energy ladder process includes the following steps: According to the characteristics of cold energy and based on the physical properties of the intermediate medium, corresponding intermediate media are used to utilize the cold energy at different temperature stages;

[0013] The liquid air cold energy recovery process is used to ensure the continuous and stable operation of the power generation process and the power generation amount;

[0014] The BOG cold energy utilization process is to set up a cold exchange between low-pressure BOG and liquid air according to the characteristics of liquid air, avoiding the influence of the BOG change increment on the operation process of the receiving station;

[0015] The liquid air ladder heating enhancement process includes the following steps:

[0016] According to the different temperature levels of the heat source, high-temperature heat sources and low-temperature heat sources are used to carry out stepped heating and heat exchange with liquid air respectively.

[0017] Furthermore, the cryogenic high-pressure medium includes at least one of LNG, liquid nitrogen, and liquid air;

[0018] Preferably, the operating temperature of the cryogenic high-pressure medium is -190°C to -120°C;

[0019] Preferably, the operating pressure of the cryogenic high-pressure medium is 5 to 15 MpaG.

[0020] Furthermore, through the liquid air and intermediate medium cold exchange process, the operating circulation amount of the intermediate medium in the intermediate medium power generation process is controlled to ensure the stability of the total power generation amount of the power generation process under each operating condition.

[0021] Furthermore, when the enhancement process for green cold energy power generation operates continuously, the liquid air cold energy recovery process is used to increase the power generation amount;

[0022] Preferably, the process power generation increases by 1 - 6 kw / t.air, and the process power generation is 30 - 57 kw / t.LNG;

[0023] Preferably, the reflux ratio of the low-temperature gaseous air after liquefaction expansion is 0 - 35%.

[0024] Furthermore, the equipment used in the cold energy ladder process includes a liquid air - intermediate medium heat exchanger, an intermediate medium distributor, an intermediate medium circulation pump, an intermediate medium precooler, an intermediate medium vaporizer, a turbine generator, and an intermediate medium buffer tank.

[0025] Furthermore, the BOG is condensed into low-pressure LNG through a BOG condensation device to reduce the influence of the BOG variation on the operation stability of the recondenser, and the LNG temperature at the inlet of the high-pressure pump is reduced to 1 - 3°C to improve the operation safety of the high-pressure pump.

[0026] Furthermore, the intermediate medium includes at least one of propane, a mixture, ethylene, carbon dioxide, and ammonia;

[0027] Preferably, the operation control parameters of the intermediate medium are as follows:

[0028] The operation temperature is -100 - 20°C, and the operation pressure is 0.03 - 0.8 MpaG;

[0029] Among them, the mixture is a mixture of methane, ethane, propane, ethylene, and butane.

[0030] Furthermore, the low-temperature heat source includes at least one of seawater and a water - ethylene glycol solution;

[0031] Preferably, the operation control parameters of the low-temperature heat source are as follows:

[0032] The operation temperature is 0 - 30°C, and the operation pressure is 0.1 - 0.3 MpaG;

[0033] The high-temperature heat source includes at least one of hot water, high-temperature hot oil, high-temperature steam, and hot molten rock;

[0034] Preferably, the operation control parameters of the high-temperature heat source are as follows:

[0035] The operation temperature is 100 - 300°C, and the operation pressure is 0.2 - 10 MpaG.

[0036] Furthermore, the equipment used in the efficiency enhancement process includes an efficiency enhancement heat exchanger, an air turbine generator, an intermediate medium turbine generator, a heat exchanger, a heat medium pump, and a heat medium circulation pump;

[0037] Preferably, the number of expansion stages of the air turbine generator is 2 - 5 stages.

[0038] In a second aspect, there is provided an application of the efficiency enhancement process for green cold energy power generation as described in any one of the above in a power project.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] The efficiency enhancement process for green cold energy power generation provided by the present invention solves the problems of unstable operation amount of the intermediate medium, unstable power generation amount, and poor economic benefit of continuous operation in the liquid air energy storage power generation process by setting the process of liquid air-intermediate medium heat exchange, improves the operation circulation amount in the intermediate medium power generation process, enhances the stability of the power generation amount and increases the power generation amount; by recovering part of the cold energy of high-pressure liquid air with low-pressure BOG, the operation stability of the receiver recondenser is enhanced and the operation safety of the high-pressure pump is improved, meeting the requirements of the limited external transmission of high-pressure NG; through the stepped heat exchange process of the high-temperature heat source and the low-temperature heat source provided by the heat source device with high-pressure air and the intermediate medium respectively, the power generation amount is effectively increased and the economic benefit of the process is improved.

[0041] In summary, the present invention is applicable to stable and continuous green cold energy power generation, can effectively recover the cold energy in the power generation process, improves the utilization efficiency of the heat source and cold energy, realizes stepped heat exchange, and finally achieves the purposes of stable continuous operation of the process, increased power generation amount, high economic benefit, and energy conservation and consumption reduction.

[0042] The application of the efficiency enhancement process for green cold energy power generation provided by the present invention has the characteristics of stable continuous operation, high power generation amount, high economic benefit, and energy conservation and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0044] Figure 1 FIG. is a schematic structural diagram of the efficiency enhancement process for green cold energy power generation provided by an embodiment of the present invention.

[0045] Icons: 1 - High-pressure and low-temperature LNG; 2 - High-pressure and low-temperature LNG; 3 - High-pressure and low-temperature NG; 4 - High-pressure exported NG; 5 - High-pressure and low-temperature LNG; 6 - High-pressure and low-temperature LNG; 7 - High-pressure and low-temperature LNG; 8 - Atmospheric-pressure and normal-temperature air; 9 - Atmospheric-pressure and normal-temperature air; 10 - Medium-pressure and low-temperature compressed air; 11 - Medium-pressure and low-temperature liquid air; 12 - Medium-pressure and low-temperature liquid air; 13 - Low-pressure and low-temperature air; 14 - Low-pressure and low-temperature gaseous air; 15 - Low-pressure and low-temperature liquid air; 16 - Low-pressure and low-temperature liquid air; 17 - Low-pressure and low-temperature liquid air; 18 - High-pressure and low-temperature liquid air; 19 - High-pressure and low-temperature liquid air; 20 - High-pressure and low-temperature liquid air; 21 - High-pressure and low-temperature liquid air; 22 - High-pressure and low-temperature liquid air; 23 - High-pressure gaseous air; 24 - Atmospheric-pressure air; 25 - Atmospheric-pressure air; 26 - Low-pressure and low-temperature air; 27 - Low-pressure and low-temperature air; 28 - Low-pressure and low-temperature air; 29 - Atmospheric-pressure and normal-temperature air; 30 - Low-pressure and low-temperature intermediate medium; 31 - Low-temperature intermediate medium; 32 - Gaseous intermediate medium; 33 - Low-temperature intermediate medium; 34 - Low-temperature intermediate medium; 35 - Low-temperature liquid intermediate medium; 36 - Low-temperature liquid intermediate medium; 37 - Low-temperature intermediate medium; 38 - Low-temperature liquid intermediate medium; 39 - Low-temperature liquid intermediate medium; 40 - Low-temperature liquid intermediate medium; 41 - Low-temperature liquid intermediate medium; 42 - Low-temperature liquid intermediate medium; 43 - Low-temperature liquid intermediate medium; 44 - Low-temperature liquid intermediate medium; 45 - Low-pressure and low-temperature air; 46 - Seawater upstream; 47 - Heat source heat medium; 48 - Seawater upstream; 49 - Seawater return; 50 - Seawater upstream; 51 - Seawater return; 52 - Seawater upstream; 53 - Seawater return; 54 - Seawater return; 55 - Heat source refrigerant; 56 - Heat source heat medium; 57 - Heat source heat medium; 58 - Heat source refrigerant; 59 - Heat source heat medium; 60 - Heat source refrigerant; 61 - High-pressure and low-temperature liquid air; 62 - High-pressure and high-temperature air; 63 - Medium-pressure and high-temperature air; 64 - Medium-pressure and normal-temperature air; 65 - Heat source heat medium; 66 - Seawater return; 67 - Seawater upstream; 68 - Gaseous high-temperature intermediate medium; 69 - Heat source refrigerant; 70 - Heat source heat medium; 71 - Low-pressure BOG; 72 - Low-pressure LNG; 73 - Low-pressure and low-temperature air; 74 - Atmospheric-pressure and normal-temperature air; 75 - Heat source refrigerant; 76 - Low-temperature liquid intermediate medium; 77 - Low-temperature liquid intermediate medium; 78 - Low-temperature intermediate medium. Detailed implementation manners

[0046] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] According to the first aspect of the present invention, an efficiency - enhancing process for green cold - energy power generation is provided, including an intermediate - medium power - generation process, a cold - energy ladder process, a liquid - air cold - energy recovery process, a BOG cold - energy utilization process, and a liquid - air step - heating efficiency - enhancing process;

[0048] The intermediate - medium power - generation process is as follows: The liquid intermediate medium after exchanging with cryogenic high - pressure media (LNG, liquid nitrogen, liquid air), with a temperature of - 100°C to 20°C, is pressurized by a circulation pump and then successively enters different heat exchangers to generate high - temperature saturated compressed gas, which enters a turbine generator to achieve power generation;

[0049] The cold - energy ladder process is: According to the cold - energy characteristics of sub - cooled LNG / liquid nitrogen / liquid air / low - temperature intermediate medium, based on the physical properties of the intermediate medium, a process of using corresponding media to utilize cold energy at different temperature stages to improve the cold - energy utilization efficiency;

[0050] The liquid - air cold - energy recovery process is: Through the liquid - air cold - energy recovery process, ensure the continuous and stable operation of the liquid - air power - generation process, achieve continuous and stable operation, increase power generation, and improve the economic benefits of cold - energy utilization;

[0051] The BOG cold - energy utilization process is: According to the characteristics of liquid air, set a process of cold exchange between low - pressure BOG and liquid air as the treatment process for BOG condensation to reduce the impact of changes in BOG generation on the re - condenser and increase the operation stability of the high - pressure pump;

[0052] The liquid - air step - heating efficiency - enhancing process is: According to the different temperature levels of heat sources, use high - temperature - level heat sources and low - temperature - level heat sources, adopt a step - heating process, and exchange heat with liquid air respectively. This can not only make full use of the heat of the low - level heat source but also utilize the heat of the high - level heat source to increase power generation.

[0053] It should be noted that the intermediate medium includes but is not limited to at least one of propane, mixture, ethylene, carbon dioxide, and ammonia; among them, the mixture can be a mixture of methane, ethane, propane, ethylene, and butane.

[0054] In a preferred embodiment, the low - temperature - level heat source includes but is not limited to at least one of seawater and water - ethylene glycol solution; at the same time, the high - temperature - level heat source includes but is not limited to at least one of hot water, high - temperature hot oil, high - temperature steam, and hot molten rock.

[0055] In the present invention, the equipment adopted in the efficiency - enhancing process of green cold - energy power generation includes, but is not limited to, air compressor units, LNG - intermediate medium heat exchangers, NG temperature compensators, intermediate medium vaporizers, intermediate medium pre - coolers, air compressor heat exchanger groups, air temperature compensators, LNG - air heat exchangers, intermediate medium vaporizers, liquid air - intermediate medium heat exchangers, liquid air - seawater vaporizers, BOG condensers, liquid air - intermediate medium heat exchangers, efficiency - enhancing heat exchangers, intermediate medium turbine - generator sets, liquid air turbine - generator sets, air turbine - generator sets, intermediate medium booster pumps, intermediate medium heat pumps, intermediate medium cold pumps, liquid air low - pressure pumps, liquid air high - pressure pumps, heat - medium pumps, intermediate medium buffer tanks, low - temperature intermediate medium storage tanks, liquid air storage tanks, and high - temperature devices.

[0056] It should be noted that the efficiency - enhancing process of green cold - energy power generation mainly consists of a power - generation process and an energy - storage process. To solve the problem of unstable power generation in the power - generation process and the energy - storage process, the present invention sets up a liquid air - intermediate medium cold - exchange process as a process route for stabilizing power generation, ensuring stable and continuous output of power generation; the liquid air - intermediate medium cold - exchange process increases the power generation of the intermediate medium by controlling the operation circulation volume of the intermediate medium in the intermediate - medium power - generation process.

[0057] In the present invention, the BOG is condensed into low - pressure LNG through the BOG condensation device, reducing the influence of the BOG variation on the operation stability of the re - condenser, increasing the operation safety of the LNG high - pressure pump, and meeting the requirements of the high - pressure NG external - transmission volume limit.

[0058] During the operation of the receiving station, the amount of BOG generated varies greatly, which affects the stability operation of the re - condenser process. Moreover, the high - pressure NG external - transmission volume changes significantly, with frequent intermittent situations, which has an adverse impact on the operation of the BOG treatment process. To reduce this impact, a liquid air - low - pressure BOG heat - exchange process is set up in the liquid air power - generation process, reducing the influence of the generated BOG variation on the operation of the re - condenser and enhancing the operation stability of the LNG high - pressure pump, and can meet the requirements of the high - pressure NG external - transmission limit.

[0059] In a preferred embodiment, the present invention utilizes heat - source media at different temperature levels to conduct heat exchange with the power - generation medium through a stepped heat - exchange process, which can not only make full use of the low - temperature - level heat source but also increase the temperature of the power - generation medium through the high - temperature - level heat source, thereby increasing the power generation and improving the economic benefits.

[0060] In a preferred embodiment, by setting up a liquid air cold - energy utilization process device, when the efficiency - enhancing process of green cold - energy power generation operates continuously, the power generation is increased, effectively solving the problem of unstable turbine power generation caused by the variation of the intermediate medium operation amount in the intermittent operation mode.

[0061] In the present invention, the liquid air cold energy step utilization process utilizes the cold energy at different temperature levels of an intermediate medium and high pressure to exchange heat with different media, achieving the purpose of fully utilizing the cold energy. The equipment involved in this process includes, but is not limited to, a liquid air - intermediate medium heat exchanger, an intermediate medium distributor, an intermediate medium circulation pump, an intermediate medium precooler, an intermediate medium vaporizer, a turbine generator, and an intermediate medium buffer tank.

[0062] In a preferred embodiment, by setting up a power generation efficiency - increasing process, the heat of heat sources at different temperature levels is utilized to increase the temperature of the intermediate medium / high - pressure air, achieving the purpose of increasing power generation. The equipment involved in this process includes, but is not limited to, an efficiency - increasing heat exchanger, an air turbine generator, an intermediate medium turbine generator, a heat exchanger, a heat medium pump, and a heat medium circulation pump.

[0063] According to the second aspect of the present invention, there is provided an application of the efficiency - increasing process for green cold energy power generation as described in any one of the above in the power engineering, which has the characteristics of stable continuous operation, high power generation, high economic benefits, and energy conservation and consumption reduction.

[0064] The present invention will be further described below through examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0065] The equipment is described as follows:

[0066] Comp - 1 is an air compressor unit, E1 is an LNG - intermediate medium heat exchanger, E2 is an NG temperature - compensating device, E3 is an intermediate medium vaporizer, E4 is an intermediate medium precooler, E5 is an air compressor unit heat exchanger, E6 is an air temperature - compensating device, E7 is an LNG - air heat exchanger, E8 is an energy - saving heat exchanger, E9 is a liquid air cold energy recovery heat exchanger, E10 is a liquid air - seawater vaporizer, E11 is a BOG condenser, E12 is a liquid air - intermediate medium heat exchanger, E13 is an efficiency - increasing heat exchanger a, E14 is a high - temperature heat exchanger, E15 is an efficiency - increasing heat exchanger b, Tur - 1 is an intermediate medium turbine generator, Tur - 2 is a liquid air generator, Tur - 3 is a high - temperature and high - pressure air turbine generator, P1 is an intermediate medium small - flow booster pump, P2 is an intermediate medium heat pump, P3 is an intermediate medium cold pump, P4 is a liquid air low - pressure pump, P5 is a liquid air booster pump, P6 is a heat medium pump, P7 is a heat medium circulation pump, P8 is an intermediate medium large - flow booster pump, T1 is an intermediate medium buffer tank, T2 is a low - temperature intermediate medium storage tank a, T3 is a low - temperature intermediate medium storage tank b, T4 is a liquid air storage tank, GH1 is a high - temperature device, and FP1 is a distributor.

[0067] The isolation valves are described as follows:

[0068] V1 is the high-pressure LNG cross-line isolation valve, V2 is the E7 inlet isolation valve, V3 is the liquid air cold energy utilization cross-line isolation valve, V4 and V20 are the air exhaust isolation valves, V5 is the air exhaust recycling isolation valve, V6 is the P7 outlet isolation valve, V7 is the seawater inlet isolation valve, V8 is the seawater return isolation valve, V9 is the E5 outlet LNG isolation valve, V10 is the E8 low-temperature and low-pressure air inlet isolation valve, V11 is the E8 cross-line isolation valve, V12 is the E7 low-temperature and low-pressure air inlet isolation valve, V13 is the P6 outlet isolation valve, V14 is the E14 heat source refrigerant inlet isolation valve, V15 is the P1 outlet isolation valve, V16 is the P1 inlet isolation valve, V17 is the P8 outlet isolation valve, V18 is the P8 inlet isolation valve, V19 is the E6 outlet isolation valve.

[0069] Example 1

[0070] This example is an energy storage and continuous power generation efficiency improvement process:

[0071] In the efficiency improvement process of stable and continuous green cold energy power generation (see the structural schematic diagram in Figure 1 ), the equipment used in the intermediate medium stable and continuous power generation process includes air compressor unit Comp-1, LNG-intermediate medium heat exchanger E1, NG temperature compensator E2, intermediate medium vaporizer E3, intermediate medium precooler E4, air compressor unit heat exchanger E5, air temperature compensator E6, LNG-air heat exchanger E7, energy-saving heat exchanger E8, liquid air cold energy recovery heat exchanger E9, liquid air-seawater vaporizer E10, BOG condenser E11, liquid air-intermediate medium heat exchanger E12, efficiency improvement heat exchanger a E13, high-temperature heat exchanger E14, efficiency improvement heat exchanger b E15, intermediate medium turbine generator Tur-1, liquid air generator Tur-2, high-temperature and high-pressure air turbine generator Tur-3, intermediate medium small flow booster pump P1, intermediate medium heat pump P2, intermediate medium cold pump P3, liquid air low-pressure pump P4, liquid air booster pump P5, heat medium pump P6, heat medium circulation pump P7, intermediate medium buffer tank T1, low-temperature intermediate medium storage tank a T2, low-temperature intermediate medium storage tank b T3, liquid air storage tank T4;

[0072] Process steps:

[0073] Close valves V1, V4, V11, V17, V18, V20, and open valves V2, V3, V5, V6, V7, V8, V9, V10, V12, V13, V14, V15, V16, V19;

[0074] The high-pressure LNG from the LNG receiving station sequentially passes through the LNG-air heat exchanger E7, the air compressor unit heat exchanger E5, the LNG-intermediate medium heat exchanger E1, and the NG temperature compensator E2, and exchanges heat with compressed air, intermediate medium, and heat source respectively to generate high-pressure NG, which is exported after meeting the process control requirements;

[0075] Air from normal pressure and normal temperature is boosted by an air compressor unit and then enters the high-temperature heat exchanger E14. After heat exchange with the heat source refrigerant, it enters the air compressor unit heat exchanger E5, exchanges heat with high-pressure low-temperature natural gas, and then enters the LNG-air heat exchanger E7 and the energy-saving heat exchanger E8 in sequence. After heat exchange with high-pressure subcooled LNG and the intermediate medium respectively, medium-pressure liquid air is generated. The medium-pressure liquid air enters the liquid air generator Tur-2 for power generation, and then the generated low-temperature and low-pressure air enters the liquid air storage tank T4, completing the cold storage process operation; the low-temperature and low-pressure gaseous air in the liquid air storage tank T4 enters the energy-saving heat exchanger E8, the LNG-air heat exchanger E7, and the air reheater E6 in sequence for heat exchange, and then is mixed with normal-pressure and normal-temperature air and enters the air compressor unit for operation;

[0076] The liquid air from the liquid air storage tank T4 is boosted by the liquid air low-pressure pump P4 and then enters the liquid air cold energy heat exchanger E9, where it exchanges heat with the intermediate medium to generate deep-cooled intermediate medium from the shallow-cooled intermediate medium. The heat-exchanged low-pressure liquid air is boosted by the liquid air booster pump P5. The outlet of the boosted liquid air can be divided into three branches for operation. The first branch 19 exchanges heat with the intermediate medium in the liquid air-intermediate medium heat exchanger E12, using the cold energy of the low-temperature supercooled air to condense the intermediate medium; the second branch 21 exchanges heat with the low-pressure BOG in the BOG condenser E11, using the cold energy of the low-temperature supercooled air to condense the low-pressure BOG into low-pressure LNG; the third branch 18 enters the downstream through the control valve V3; the liquid high-pressure air from the three branches is mixed after operation and enters the liquid air shallow heat vaporizer E10, where it exchanges heat with seawater to convert the high-pressure liquid air into high-pressure normal-temperature air. To further increase the power generation, the high-pressure normal-temperature air enters the efficiency-enhancing heat exchanger a E13, exchanges heat with the high-temperature heat medium to generate high-pressure high-temperature gaseous air, and then enters the high-temperature air turbine generator Tur-3 for expansion power generation to meet the requirements of this process; the normal-pressure air at the outlet of the high-temperature air turbine generator Tur-3 is divided into two paths. One path is mixed with the normal-pressure and normal-temperature air 8 and then enters the air compressor drying unit, and the other branch is directly discharged to the atmosphere;

[0077] The medium from the intermediate medium buffer tank T1 is pressurized by the intermediate medium small flow booster pump P1 and then enters the intermediate medium pre-cooler E4 to exchange heat with the expanded low-pressure shallow-cooled intermediate medium; the substance from the intermediate medium pre-cooler E4 enters the intermediate medium vaporizer E3 to exchange heat with seawater, and the low-temperature intermediate medium generates gaseous intermediate medium. In order to increase the power generation, the gaseous intermediate medium enters the efficiency-enhancing heat exchanger bE15 to exchange heat with the high-temperature heat source, and the temperature of the intermediate medium rises to high temperature, and then enters the intermediate medium turbine generator Tur-1 for expansion power generation. After expansion, the high-temperature intermediate medium generates low-pressure gas intermediate medium. This gas intermediate medium further exchanges heat with the subcooled intermediate medium in the intermediate medium pre-cooler E4 to meet the requirement of making full use of the cold quantity ladder; the low-pressure shallow-cooled intermediate medium from the intermediate medium pre-cooler E4 enters the distributor FP1. The low-pressure shallow-cooled intermediate medium is divided into two branches by the distributor. The first branch 34 enters the LNG-intermediate medium heat exchanger E1 to exchange heat with the high-pressure low-temperature LNG to generate subcooled low-pressure low-temperature liquid intermediate medium, and then enters the branch 35; the second branch 37 enters the liquid air-intermediate medium heat exchanger E12 to exchange heat with liquid air to generate subcooled low-pressure low-temperature liquid intermediate medium, and then mixes with the branch 35 and enters the intermediate medium buffer tank T1;

[0078] The medium from the intermediate medium low-temperature tank T2 is pressurized by the intermediate medium heat pump P2 and then enters the liquid air cold quantity heat exchanger E9 to exchange heat with the low-pressure subcooled liquid air. The intermediate medium after heat exchange enters the intermediate medium low-temperature tank T3, and then is pressurized by the intermediate medium cold pump P3 and enters the energy-saving heat exchanger E8 to exchange heat with the low-temperature air to make full use of the cold quantity and cool the low-temperature air to the medium-pressure subcooled state. The intermediate medium after heat exchange enters the intermediate medium low-temperature tank T2. This process setting makes use of the cold quantity gradient of liquid air to achieve the purpose of making full use of the cold quantity;

[0079] The seawater inlet 46 is divided into four branches. The first branch 48 enters the NG temperature compensator E2 to exchange heat with the high-pressure shallow-cooled NG to meet the requirement of high-pressure NG external transportation; the second branch 50 enters the intermediate medium vaporizer E3 to exchange heat with the low-pressure low-temperature intermediate medium to vaporize the intermediate medium and meet the requirement of the next operation of the intermediate medium; the third branch 52 enters the liquid air-seawater vaporizer E10 to exchange heat with the high-pressure low-temperature liquid air using the low-temperature heat source to vaporize the liquid air; the fourth branch 67 enters the air temperature compensator E6 to exchange heat with the shallow-cooled low-temperature air to meet the process requirement of air reflux utilization; the four branches 49, 51, 53 and 66 are mixed and then enter the seawater return 54, and finally enter the seawater return main pipe;

[0080] The high-temperature heat source from the high-temperature device GH1 enters the high-temperature heat medium pump P7. After being pressurized, the high-temperature heat medium enters pipeline 65, mixes with pipeline 57 and then enters 76. Pipeline 76 branches into two paths. The first path 70 enters the efficiency-enhancing heat exchanger b E15, exchanges heat with the normal-temperature intermediate medium to increase the temperature of the intermediate medium. After the high-temperature heat medium exchanges heat, it generates normal-temperature refrigerant and then enters pipeline 69. The second path 47 enters the efficiency-enhancing heat exchanger a E13, exchanges heat with high-pressure normal-temperature air. After the high-temperature heat medium exchanges heat, it generates normal-temperature refrigerant and then enters pipeline 58. After mixing with the normal-temperature refrigerant from pipeline 69, it enters the high-temperature device through pipeline 75 for heat exchange operation to facilitate the next cycle operation. This operation process increases the power generation of the intermediate medium turbine generator Tur-1 and the high-temperature and high-pressure air turbine generator.

[0081] Example 2

[0082] Example 2 is an efficiency-enhancing process for non-energy storage and continuous power generation:

[0083] In the efficiency-enhancing process of stable and continuous green cold energy power generation (see the structural schematic diagram in Figure 1 ), the equipment adopted in the intermediate medium stable and continuous power generation process includes LNG-intermediate medium heat exchanger E1, NG temperature compensator E2, intermediate medium vaporizer E3, intermediate medium precooler E4, air temperature compensator E6, liquid air cold energy heat exchanger E9, liquid air-seawater vaporizer E10, BOG condenser E11, liquid air-intermediate medium heat exchanger E12, efficiency-enhancing heat exchanger b E15, efficiency-enhancing heat exchanger a E13, intermediate medium turbine generator Tur-1, high-temperature and high-pressure air turbine unit Tur-3, intermediate medium large-flow booster pump P8, intermediate medium heat pump P2, liquid air low-pressure pump P4, liquid air booster pump P5, heat medium circulation pump P7, intermediate medium buffer tank T1, intermediate medium low-temperature tank T2, intermediate medium low-temperature tank T3, liquid air storage tank T4.

[0084] Process steps:

[0085] Close valves V2, V5, V9, V10, V12, V13, V14, V15, V16 and V19, and open valves V1, V3, V4, V6, V7, V8, V11, V17, V18 and V20;

[0086] The high-pressure LNG from the LNG receiving station sequentially passes through the LNG-intermediate medium heat exchanger E1 and the NG temperature compensator E2, exchanges heat with the intermediate medium and seawater respectively, generates high-pressure NG, and the high-pressure NG meeting the process requirements is transported downstream.

[0087] The low-pressure and low-temperature air in the liquid air storage tank T4 enters the air temperature compensator E6 through pipelines 14, 45 and 73, exchanges heat with seawater and then is discharged to the atmosphere.

[0088] The liquid air from the liquid air storage tank T4 is pressurized by the low-pressure liquid air pump P4 and then enters the liquid air cold energy heat exchanger E9, where it exchanges heat with the intermediate medium of the shallow cooling. The low-pressure liquid air after heat exchange is pressurized by the liquid air booster pump P5. The pressurized liquid air is divided into three branch operations. The first branch 19 enters the liquid air-intermediate medium heat exchanger E12 to exchange heat with the intermediate medium, and the high-pressure liquid air after heat exchange enters the pipeline 20. The second branch 21 enters the BOG condenser E11 to exchange heat with the BOG, condensing the BOG into LNG, and the high-pressure liquid air after heat exchange enters the pipeline 22. The third branch 18 enters the pipeline 61 through the control valve V3. The liquid high-pressure air from the three branches 20, 22, and 61 is mixed and enters the liquid air-seawater vaporizer E10 to exchange heat with seawater, generating high-pressure normal-temperature gas. To further increase the power generation, the high-pressure normal-temperature air enters the efficiency-enhancing heat exchanger a E13 to exchange heat with the high-temperature heat medium, generating high-pressure high-temperature gaseous air, and then enters the high-temperature high-pressure air turbine generator Tur-3 for expansion power generation to meet the power generation requirements of this process. The normal-pressure air at the outlet of the high-temperature high-pressure air turbine generator Tur-3 is directly discharged to the atmosphere through the pipeline 74.

[0089] The intermediate medium from the intermediate medium buffer tank T1 enters the booster pump P1 for pressurization. The pressurized intermediate medium enters the intermediate medium precooler E4 to exchange heat with the expanded low-pressure intermediate medium of the shallow cooling. The low-pressure and low-temperature intermediate medium from the intermediate medium precooler E4 enters the intermediate medium vaporizer E3 to exchange heat with seawater. The low-temperature intermediate medium generates gaseous intermediate medium and then enters the efficiency-enhancing heat exchanger b E15 to exchange heat with the high-temperature heat medium. The heated intermediate medium enters the intermediate medium turbine generator Tur-1 for expansion power generation. The low-pressure and low-temperature intermediate medium after expansion and pressure reduction enters the intermediate medium precooler E4 to exchange heat with the subcooled intermediate medium, further cooling the intermediate medium in the pipeline 33 to meet the requirement of making full use of the cold energy step by step. The low-pressure intermediate medium of the shallow cooling from the intermediate medium precooler E4 enters the distributor FP1. The low-pressure intermediate medium of the shallow cooling is divided into two branches by the distributor. The first branch 34 enters the LNG-intermediate medium heat exchanger E1 to exchange heat with the high-pressure low-temperature NG, generating low-pressure subcooled liquid intermediate medium, and then enters the pipeline 35. The second branch 37 enters the liquid air-intermediate medium heat exchanger E12 to exchange heat with the liquid air, generating low-pressure subcooled liquid intermediate medium, enters the pipeline 38, and after mixing with the branch 35, enters the intermediate medium buffer tank T1.

[0090] The medium from the intermediate medium low-temperature tank T2 enters the intermediate medium heat pump P2 for pressurization. The pressurized intermediate medium enters the liquid air cold energy heat exchanger E9 to exchange heat with the low-pressure subcooled liquid air. The intermediate medium after heat exchange enters the intermediate medium low-temperature tank T3. This process setting utilizes the cold energy gradient of the liquid air and achieves the purpose of making full use of the cold energy.

[0091] The seawater from the seawater main pipe 46 is divided into four branches. The first branch 48 enters the NG supplementary heater E2 and exchanges heat with high-pressure shallow-cooled NG. After heat exchange, the seawater enters the pipeline 49. The second branch 50 enters the heat exchanger E3 and exchanges heat with the low-pressure low-temperature intermediate medium. After heat exchange, the seawater enters the pipeline 51. The third branch 52 enters the liquid air-seawater vaporizer E10 and exchanges heat with high-pressure low-temperature liquid air. After heat exchange, the seawater enters the pipeline 53. The fourth branch 67 enters the air supplementary heater E6 and exchanges heat with shallow-cooled low-temperature air to meet the air process control requirements. After heat exchange, the seawater enters the pipeline 66. The four branches 49, 51, 53 and 66 are mixed and then enter the seawater main pipe 54.

[0092] The high-temperature heat source from the high-temperature device GH1 enters the heat medium circulation pump P7. After being pressurized, the high-temperature heat medium enters the pipelines 65 and 76. The pipeline 76 is divided into two branches. The first branch 70 enters the efficiency-enhancing heat exchanger bE15 and exchanges heat with the low-pressure normal-temperature intermediate medium to increase the temperature of the low-pressure intermediate medium and achieve the purpose of increasing the power generation of the intermediate medium turbine generator Tur-1. After heat exchange, the high-temperature heat medium generates normal-temperature refrigerant and then enters the pipeline 69. The second branch 47 enters the efficiency-enhancing heat exchanger a E13 and exchanges heat with high-pressure normal-temperature air. After heat exchange, the high-temperature heat medium generates normal-temperature refrigerant and then enters the pipeline 58. After mixing with the normal-temperature refrigerant from the pipeline 69, it enters the high-temperature device through the pipeline 75 for heat exchange operation to facilitate the next cycle operation.

[0093] In summary, through stepped heat exchange and by using heat sources at different temperature levels, the present invention increases the pressure and temperature of the intermediate medium, ensures the stability of the operating pressure and temperature of the intermediate medium entering the turbine generator, and avoids the influence of seawater temperature changes on the gasification operating pressure and temperature of the intermediate medium. Thus, it effectively solves the problems of poor stability and low increment in the power generation of the turbine generator. At the same time, through different operating processes, the gasification amount of the intermediate medium is increased, solving the problem of low power generation of the turbine generator. This process effectively improves the economic value of cold energy utilization.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A green cold energy power generation efficiency enhancement process, characterized in that: Including intermediate medium power generation process, cold energy ladder process, liquid air cold energy recovery process, BOG cold energy utilization process, and liquid air ladder heating efficiency enhancement process; The intermediate medium power generation process comprises the following steps: The liquid intermediate medium after exchanging with the cryogenic high-pressure medium is pressurized by the circulating pump and then enters the heat exchanger to generate high-temperature and high-pressure gas and enters the turbine generator to generate electricity; The cold energy ladder process comprises the following steps: According to the characteristics of cold energy and the physical properties of the intermediate medium, the cold energy at different temperature stages is used to adopt the corresponding intermediate medium for cold energy utilization; The liquid-air cooling energy recovery process is used to ensure continuous and stable operation of the power generation process with constant amount of electricity generated; The BOG cold energy utilization process is to set low-pressure BOG and liquid air for cold exchange according to the characteristics of liquid air; The liquid air step heating efficiency enhancement process comprises the following steps: According to the different temperature positions of the heat sources, high-temperature heat sources and low-temperature heat sources are used to exchange heat with liquid air respectively using a step-by-step heating method.

2. The green cold energy power generation efficiency enhancement process according to claim 1, characterized in that: The cryogenic high-pressure medium includes at least one of LNG, liquid nitrogen and liquid air; Preferably, the operating temperature of the cryogenic high-pressure medium is -190°C to -120°C; Preferably, the operating pressure of the cryogenic high-pressure medium is 5 to 15 MPaG.

3. The green cold energy power generation efficiency enhancement process according to claim 1, characterized in that: Through the cold exchange process between liquid air and intermediate medium, the operating circulation volume of the intermediate medium in the intermediate medium power generation process is controlled to ensure the stability of the total power generation of the power generation process under various operating conditions.

4. The green cold energy power generation efficiency enhancement process according to claim 1, characterized in that: When the green cold energy power generation efficiency enhancement process is continuously operated, the liquid-air cold energy recovery process is used to increase the power generation; Preferably, the process power generation is increased to 1-6kw / t.air, and the process power generation is 30-57kw / t.LNG; Preferably, the reflux rate of low-temperature gas-phase air after liquefaction and expansion is 0 to 35%.

5. The green cold energy power generation efficiency enhancement process according to claim 1, characterized in that: The equipment used in the cold energy ladder process includes a liquid-air-intermediate medium heat exchanger, an intermediate medium distributor, an intermediate medium circulation pump, an intermediate medium precooler, an intermediate medium vaporizer, a turbine generator and an intermediate medium buffer tank.

6. The green cold energy power generation efficiency enhancement process according to claim 1, characterized in that: BOG is condensed into low-pressure LNG through the BOG condensing device to reduce the impact of BOG variation on the operational stability of the recondenser and reduce the LNG temperature at the high-pressure pump inlet to 1-3°C to improve the operational safety of the high-pressure pump.

7. The green cold energy power generation efficiency enhancement process according to any one of claims 1 to 5, characterized in that: The intermediate medium includes at least one of propane, a mixed agent, ethylene, carbon dioxide and ammonia; Preferably, the operation control parameters of the intermediate medium are as follows: The operating temperature is -100~20℃, and the operating pressure is 0.03~0.8MpaG; Wherein, the mixed agent is a mixture of methane, ethane, propane, ethylene and butane.

8. The green cold energy power generation efficiency enhancement process according to any one of claims 1 to 5, characterized in that: The low temperature heat source comprises at least one of seawater and water-ethylene glycol solution; Preferably, the operation control parameters of the low temperature heat source are as follows: The operating temperature is 0~30℃, and the operating pressure is 0.1~0.3MpaG; The high temperature heat source includes at least one of hot water, high temperature hot oil, high temperature steam and hot lava; Preferably, the operation control parameters of the high temperature heat source are as follows: The operating temperature is 100-300°C, and the operating pressure is 0.2-10MpaG.

9. The green cold energy power generation efficiency enhancement process according to any one of claims 1 to 5, characterized in that: The equipment used in the efficiency enhancement process includes an efficiency enhancement heat exchanger, an air turbine generator, an intermediate medium turbine generator, a heat exchanger, a heat medium pump and a heat medium circulation pump; Preferably, the air turbine generator has 2 to 5 expansion stages.

10. Application of the green cold energy power generation efficiency enhancement process according to any one of claims 1 to 9 in power engineering.

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