CN114687821B - Efficient power generation system based on liquefied natural gas and working method thereof - Google Patents
Efficient power generation system based on liquefied natural gas and working method thereof Download PDFInfo
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- CN114687821B CN114687821B CN202210378598.2A CN202210378598A CN114687821B CN 114687821 B CN114687821 B CN 114687821B CN 202210378598 A CN202210378598 A CN 202210378598A CN 114687821 B CN114687821 B CN 114687821B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K11/00—Plants characterised by the engines being structurally combined with boilers or condensers
- F01K11/02—Plants characterised by the engines being structurally combined with boilers or condensers the engines being turbines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K13/00—General layout or general methods of operation of complete plants
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K21/00—Steam engine plants not otherwise provided for
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
- F01K25/10—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours the vapours being cold, e.g. ammonia, carbon dioxide, ether
- F01K25/103—Carbon dioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K27/00—Plants for converting heat or fluid energy into mechanical energy, not otherwise provided for
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Abstract
The invention discloses a high-efficiency power generation system based on liquefied natural gas and a working method thereof, and belongs to the technical field of power generation systems. The system mainly comprises a natural gas boiler, a carbon dioxide gas turbine, a primary carbon dioxide heat exchanger, a secondary carbon dioxide heat exchanger, an air heat exchanger, a flue gas heat exchanger, an organic working medium gas turbine, an organic working medium heat exchanger, a liquid natural gas tank, a motor cooling working medium heat exchanger and an ultralow temperature motor. According to the invention, the liquid natural gas fuel is used as a cold source, so that the cold of the liquid natural gas is utilized in a cascade manner, the lower limit of the working temperature of carbon dioxide circulation and organic working medium circulation is reduced, and simultaneously, the low-temperature organic working medium circulation is coupled to absorb heat release of the carbon dioxide circulation and heat in the atmosphere; the working temperature of the motor is reduced, cooling equipment is saved, and energy consumption is reduced; the overall circulation efficiency is improved, the circulation structure is simplified, the investment and the operation and maintenance cost of the system are greatly reduced, and the overall requirements of energy conservation and emission reduction are met.
Description
Technical Field
The invention belongs to the technical field of power generation systems, and particularly relates to a high-efficiency power generation system based on liquefied natural gas and a working method thereof.
Background
With the promotion of market demands and the continuous development of energy utilization and equipment manufacturing technologies, in the past decades, large-scale power generation technologies of Rankine cycle using water vapor as a working medium and Brayton cycle using fuel gas as a working medium have been developed towards high-parameter and high-power directions. Analysis shows that the development of the large-scale power generation technology improves the energy conversion efficiency and reduces the construction and power generation cost of unit power. However, high parameters also make the generator set very bulky, the circulatory system is extremely complex, and challenges are presented to material strength, equipment manufacturing and operational control. Therefore, the development of high parameters and high power of large-scale generator sets faces important technical bottlenecks.
In recent years, a closed brayton cycle power generation technology using supercritical carbon dioxide as a working medium is generally focused in academia and industry, the pressure of the working medium is improved by compressing the carbon dioxide in a micro supercritical state by a compressor, the gaseous carbon dioxide is heated in a boiler to reach the working pressure and then enters a supercritical carbon dioxide gas turbine to do work, and the exhaust gas is regenerated through a plurality of gas-gas heat exchangers to improve the cycle efficiency.
Although it has been proven in practice that the impeller machines of the supercritical carbon dioxide brayton cycle are more compact than the devices of the steam rankine cycle, the following disadvantages still exist: (1) In order to improve the circulation efficiency, a recompression or triple compression scheme is adopted, a gas turbine also adopts a double reheating scheme, the structure is extremely complex, and difficulties are brought to system regulation; (2) In order to realize multiple compression, multiple reheating and multi-stage backheating, the boiler is required to be matched with a plurality of temperature intervals for heat transfer so as to improve the efficiency of the boiler; (3) Because of the compression at the near critical point, the liquid state phenomenon of working medium exists at the inlet of the compressor, which causes water erosion to the blades and simultaneously brings difficulty to the stable control of the compressor; (4) The minimum pressure of the circulation is 7.38MPa, so that the enthalpy drop in the gas turbine is about 160kJ/kg, which is far lower than the steam circulation, and thus, the flow of working medium needs to be increased to increase the output power of the circulation, which has fatal influence on the pressure loss of the working medium in the boiler.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a high-efficiency power generation system based on liquid natural gas and a working method thereof, which can fully utilize the cold energy of the liquid natural gas and fully release the energy of a carbon dioxide circulating working medium, thereby simplifying the boiler and impeller machinery, improving the compactness of a large-scale motor and realizing the high-efficiency conversion from heat energy to electric energy.
The invention is realized by the following technical scheme:
the invention discloses a high-efficiency power generation system based on liquefied natural gas, which comprises a natural gas boiler, a carbon dioxide gas turbine, a primary carbon dioxide heat exchanger, a secondary carbon dioxide heat exchanger, an air heat exchanger, a flue gas heat exchanger, an organic working medium gas turbine, an organic working medium heat exchanger, a liquefied natural gas tank, a motor cooling working medium heat exchanger and an ultralow-temperature motor, wherein the air heat exchanger is connected with the flue gas heat exchanger;
the working medium outlet of the natural gas boiler is connected with the inlet of the carbon dioxide gas turbine, the outlet of the carbon dioxide gas turbine is connected with the high-temperature side inlet of the primary carbon dioxide heat exchanger, the high-temperature side outlet of the primary carbon dioxide heat exchanger is connected with the high-temperature side inlet of the secondary carbon dioxide heat exchanger, the high-temperature side outlet of the secondary carbon dioxide heat exchanger is connected with the inlet of the air heat exchanger, the outlet of the air heat exchanger is connected with the inlet of the flue gas heat exchanger, and the outlet of the flue gas heat exchanger is connected with the working medium inlet of the natural gas boiler; the low-temperature side outlet of the first-stage carbon dioxide heat exchanger is connected with the inlet of the organic working medium gas turbine, the outlet of the organic working medium gas turbine is connected with the high-temperature side inlet of the organic working medium heat exchanger, the high-temperature side outlet of the organic working medium heat exchanger is connected with the second low-temperature side inlet of the second-stage carbon dioxide heat exchanger, and the second low-temperature side outlet of the second-stage carbon dioxide heat exchanger is connected with the low-temperature side inlet of the carbon dioxide heat exchanger; the outlet of the liquid natural gas tank is connected with the low-temperature side inlet of the organic working medium heat exchanger, the low-temperature side outlet of the organic working medium heat exchanger is connected with the first low-temperature side inlet of the secondary carbon dioxide heat exchanger, the first low-temperature side outlet of the secondary carbon dioxide heat exchanger is connected with the low-temperature side inlet of the motor cooling working medium heat exchanger, and the low-temperature side outlet of the motor cooling working medium heat exchanger is connected with the fuel inlet of the natural gas boiler; the high-temperature side outlet of the motor cooling working medium heat exchanger is connected with the inlet of the motor cooling working medium pump, the outlet of the motor cooling working medium pump is connected with the cooling working medium inlet of the ultralow-temperature motor, and the ultralow-temperature motor cooling working medium outlet is connected with the high-temperature side inlet of the motor cooling working medium heat exchanger; the rotor of the ultralow temperature motor is connected with the rotor of the carbon dioxide gas turbine through a coupler, and the rotor of the carbon dioxide gas turbine is connected with the rotor of the organic working medium gas turbine through a coupler.
Preferably, a carbon dioxide pump is arranged between the high-temperature side outlet of the secondary carbon dioxide heat exchanger and the inlet of the air heat exchanger; an organic working medium pump is arranged between the high-temperature side outlet of the organic working medium heat exchanger and the second low-temperature side inlet of the secondary carbon dioxide heat exchanger; a liquid natural gas pump is arranged between the outlet of the liquid natural gas tank and the low-temperature side inlet of the organic working medium heat exchanger; and a motor cooling working medium pump is arranged between the high-temperature side outlet of the motor cooling working medium heat exchanger and the cooling working medium inlet of the ultralow-temperature motor.
Preferably, the cryogenic motor, the carbon dioxide gas turbine and the organic working medium gas turbine are coaxially arranged.
Preferably, the primary carbon dioxide heat exchanger is a printed circuit board heat exchanger, the secondary carbon dioxide heat exchanger is a multi-strand printed circuit board heat exchanger, the air heat exchanger is a printed circuit board heat exchanger, the flue gas heat exchanger is a printed circuit board heat exchanger, the organic working medium heat exchanger is a plate-fin heat exchanger, and the motor cooling working medium heat exchanger is a plate-fin heat exchanger.
The working method of the efficient power generation system based on the liquefied natural gas disclosed by the invention comprises the following steps:
the exhaust of the carbon dioxide gas turbine sequentially transfers heat to the organic working medium and the liquid natural gas in the primary carbon dioxide heat exchanger and the secondary carbon dioxide heat exchanger, gaseous carbon dioxide is changed into liquid state, then the heat of the atmosphere is sequentially absorbed in the air heat exchanger to raise the temperature, and the heat contained in the exhaust gas of the natural gas boiler is absorbed in the flue gas heat exchanger to gasify; the gaseous carbon dioxide is heated and warmed to the highest working temperature by heat energy released by the combustion of natural gas and air in the natural gas boiler; the gaseous carbon dioxide enters a carbon dioxide wheel gas turbine to expand and do work, and the shaft work drives an ultralow-temperature motor to convert mechanical work into electric energy;
the method comprises the steps that heat is transferred to liquid natural gas by the exhaust of an organic working medium gas turbine in an organic working medium heat exchanger, a gaseous organic working medium is changed into a liquid state, then the heat released by carbon dioxide circulating exhaust in a secondary carbon dioxide heat exchanger and a primary carbon dioxide heat exchanger is sequentially absorbed, the heat is changed into a gaseous state, and the temperature is raised to the highest working temperature; the gaseous organic working medium enters an organic working medium gas turbine to expand and apply work, and the shaft work drives an ultralow-temperature motor to convert mechanical work into electric energy;
the method comprises the steps that liquid natural gas in a liquid natural gas storage tank enters an organic working medium heat exchanger, heat released by circulating exhaust of the organic working medium is absorbed, then the liquid natural gas enters a secondary carbon dioxide heat exchanger to continuously absorb the heat released by circulating exhaust of the carbon dioxide, finally, heat in an ultralow-temperature motor is absorbed in a motor cooling working medium heat exchanger and is converted into gaseous natural gas, and the gaseous natural gas is sent into a natural gas boiler as fuel to be subjected to chemical reaction with air, so that heat energy is released;
the motor cooling working medium absorbs heat generated by copper loss, iron loss and eddy current loss in the ultralow temperature motor, and releases natural gas in a motor cooling working medium heat exchanger to change the natural gas from liquid state to gas state, and the motor cooling working medium enters the ultralow temperature motor.
Preferably, the outlet pressure of the high temperature side of the secondary carbon dioxide heat exchanger is 0.55-7.00 MPa.
Preferably, the exhaust pressure of the carbon dioxide gas turbine is below the critical pressure of carbon dioxide.
Preferably, the operating temperature of the cryogenic motor is below 0 ℃.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention discloses a high-efficiency power generation system based on liquefied natural gas, which combines a carbon dioxide power cycle with cold energy utilization of liquefied natural gas, absorbs and utilizes heat originally required to be discharged to the outside in the carbon dioxide power cycle, further reduces the lowest pressure of the carbon dioxide power cycle, improves the working capacity of working media with unit mass, reduces the carbon dioxide flow, reduces the pressure loss of a boiler and improves the carbon dioxide circulation efficiency; the heat of carbon dioxide circulation exhaust is adopted to heat the organic working medium, the organic working medium enters an organic working medium gas turbine to do work, the heat of the exhaust is absorbed by the liquid natural gas to form low-temperature organic working medium power circulation, the heat of the exhaust of the carbon dioxide circulation is fully utilized, and the overall circulation efficiency is further improved.
The carbon dioxide power cycle and the low-temperature organic working medium power cycle both adopt Rankine cycle modes, namely the working medium is cooled into liquid, when the working medium is pressurized, more mechanical work can be saved compared with the gaseous state compression, and the cycle efficiency is improved. After the liquid carbon dioxide is pressurized by the pump, firstly, the heat of the atmospheric environment is absorbed in the air heat exchanger, the heat in the natural environment is fully utilized, secondly, the heat contained in the exhaust gas of the boiler is absorbed in the flue gas heat exchanger, and meanwhile, the temperature limit between the high-temperature heat source and the low-temperature heat source is enlarged through cooling of the liquid natural gas, so that the carbon dioxide circulation efficiency is improved.
The exhaust heat of the organic working medium gas turbine is absorbed by the liquid natural gas, the exhaust temperature of the organic working medium gas turbine is reduced to about-150 ℃, the temperature limit between the high-temperature heat source and the low-temperature heat source of the organic working medium circulation is enlarged, and the efficiency of the organic working medium circulation is improved. The liquid natural gas absorbs heat generated when the ultralow-temperature motor works, the working temperature of the motor is reduced to be lower than 0 ℃, the resistance of a coil is reduced, the heat generated by the motor is reduced, the motor efficiency is improved, or the current and magnetic flux in the coil are improved, the size of the motor is reduced, and the material and processing cost are reduced. Meanwhile, the minimum pressure of the carbon dioxide circulation can be reduced to 0.55MPa, compared with the traditional pressure of 7.38MPa, the sealing pressure difference is greatly reduced by the shaft end sealing of the carbon dioxide turbine, the difficulty of the sealing technology is greatly reduced, and the sealing cost is reduced.
According to the working method of the efficient power generation system based on the liquid natural gas, disclosed by the invention, the liquid natural gas fuel is used as a cold source, so that the cold quantity of the liquid natural gas is utilized in a cascade manner, the lower limit of working temperatures of carbon dioxide circulation and organic working medium circulation is reduced, and meanwhile, the low-temperature organic working medium circulation is coupled to absorb carbon dioxide circulation heat release and heat in the atmospheric environment; the working temperature of the motor is reduced, cooling equipment is saved, and energy consumption is reduced; the overall circulation efficiency is improved, the circulation structure is simplified, the investment and the operation and maintenance cost of the system are greatly reduced, and the overall requirements of energy conservation and emission reduction are met.
Drawings
FIG. 1 is a schematic diagram of a high efficiency power generation system based on liquid natural gas in accordance with the present invention.
In the figure: the natural gas boiler is characterized in that the natural gas boiler is 1, the carbon dioxide gas turbine is 2, the primary carbon dioxide heat exchanger is 3, the secondary carbon dioxide heat exchanger is 4, the carbon dioxide pump is 5, the air heat exchanger is 6, the flue gas heat exchanger is 7, the organic working medium gas turbine is 8, the organic working medium heat exchanger is 9, the organic working medium pump is 10, the liquid natural gas tank is 11, the liquid natural gas pump is 12, the motor cooling working medium heat exchanger is 13, the ultralow temperature motor is 14, and the motor cooling working medium pump is 15.
Detailed Description
The invention will now be described in further detail with reference to the accompanying drawings and examples, the content of which is for explanation rather than limitation of the invention:
the cold energy contained in the liquid natural gas can not be well utilized at present; the current supercritical carbon dioxide circulation is low in circulation efficiency and complex in system. The efficient power generation system based on the liquefied natural gas combines the carbon dioxide power cycle with the cold energy utilization of the liquefied natural gas, and solves the technical problems existing at present.
Referring to fig. 1, the efficient power generation system based on liquefied natural gas of the present invention comprises a natural gas boiler 1, a carbon dioxide gas turbine 2, a primary carbon dioxide heat exchanger 3, a secondary carbon dioxide heat exchanger 4, a carbon dioxide pump 5, an air heat exchanger 6, a flue gas heat exchanger 7, an organic working medium gas turbine 8, an organic working medium heat exchanger 9, an organic working medium pump 10, a liquefied natural gas tank 11, a liquefied natural gas pump 12, a motor cooling working medium heat exchanger 13, an ultra-low temperature motor 14 and a motor cooling working medium pump 15.
The working medium outlet of the natural gas boiler 1 is connected with the inlet of the carbon dioxide gas turbine 2, the outlet of the carbon dioxide gas turbine 2 is connected with the high-temperature side inlet of the primary carbon dioxide heat exchanger 3, the high-temperature side outlet of the primary carbon dioxide heat exchanger 3 is connected with the high-temperature side inlet of the secondary carbon dioxide heat exchanger 4, the high-temperature side outlet of the secondary carbon dioxide heat exchanger 4 is connected with the inlet of the carbon dioxide pump 5, the outlet of the carbon dioxide pump 5 is connected with the inlet of the air heat exchanger 6, the outlet of the air heat exchanger 6 is connected with the inlet of the flue gas heat exchanger 7, the outlet of the flue gas heat exchanger 7 is connected with the working medium inlet of the natural gas boiler 1, the low-temperature side outlet of the primary carbon dioxide heat exchanger 3 is connected with the inlet of the organic working medium gas turbine 8, the outlet of the organic working medium gas turbine 8 is connected with the high-temperature side inlet of the organic working medium heat exchanger 9, the high-temperature side outlet of the organic working medium heat exchanger 9 is connected with the inlet of the organic working medium pump 10, an outlet of the organic working medium pump 10 is connected with a second low-temperature side inlet of the secondary carbon dioxide heat exchanger 4, an outlet of the second low-temperature side of the secondary carbon dioxide heat exchanger 4 is connected with a low-temperature side inlet of the primary carbon dioxide heat exchanger 3, an outlet of the liquid natural gas tank 11 is connected with an inlet of the liquid natural gas pump 12, an outlet of the liquid natural gas pump 12 is connected with a low-temperature side inlet of the organic working medium heat exchanger 9, an outlet of the low-temperature side of the organic working medium heat exchanger 9 is connected with a first low-temperature side inlet of the secondary carbon dioxide heat exchanger 4, an outlet of the first low-temperature side of the secondary carbon dioxide heat exchanger 4 is connected with a low-temperature side inlet of the motor cooling working medium heat exchanger 13, an outlet of the low-temperature side of the motor cooling working medium heat exchanger 13 is connected with a fuel inlet of the natural gas boiler 1, an outlet of the high-temperature side of the motor cooling working medium heat exchanger 13 is connected with an inlet of the motor cooling working medium pump 15, an outlet of the motor cooling working medium pump 15 is connected with a cooling working medium inlet of the ultralow-temperature motor 14, the cooling working medium outlet of the ultralow temperature motor 14 is connected with the high temperature side inlet of the motor cooling working medium heat exchanger 13, the rotor of the ultralow temperature motor 14 is connected with the rotor of the carbon dioxide gas turbine 2 through a coupler, and the rotor of the carbon dioxide gas turbine 2 is connected with the organic working medium gas turbine 8 through a coupler.
The carbon dioxide is pressurized by the carbon dioxide pump 5 and is changed into a gas state from a liquid state through three-stage heating of the air heat exchanger 6, the flue gas heat exchanger 7 and the natural gas boiler 1.
The heat of the ultralow temperature motor 14 cooling working medium is absorbed by natural gas in the motor cooling working medium heat exchanger 13.
The heat of the exhaust gas of the carbon dioxide gas turbine 2 is absorbed by the organic working medium on the cold side in the primary carbon dioxide heat exchanger 3 and the secondary carbon dioxide heat exchanger 4.
The secondary carbon dioxide heat exchanger 4 is provided with two cold side working media, namely natural gas and organic working media.
The organic working medium heat of the organic working medium heat exchanger 9 is absorbed by the cold side liquid natural gas.
The air heat exchanger 6 absorbs heat from the atmosphere to raise the liquid carbon dioxide temperature.
In a preferred embodiment of the invention, the ultra-low temperature motor 14, the carbon dioxide gas turbine 2 and the organic working fluid turbine 8 are arranged coaxially.
In a preferred embodiment of the invention, the primary carbon dioxide heat exchanger 3, the secondary carbon dioxide heat exchanger 4, the air heat exchanger 6 and the flue gas heat exchanger 7 are printed circuit board heat exchangers, wherein the secondary carbon dioxide heat exchanger 4 is a multi-stream printed circuit board heat exchanger; the organic working medium heat exchanger 9 and the motor cooling working medium heat exchanger 13 are plate-fin heat exchangers.
The working method of the efficient power generation system based on the liquefied natural gas comprises the following steps:
the exhaust of the carbon dioxide gas turbine 2 sequentially transfers heat to the organic working medium and the liquid natural gas in the primary carbon dioxide heat exchanger 3 and the secondary carbon dioxide heat exchanger 4, gaseous carbon dioxide is changed into liquid, and the liquid carbon dioxide is pressurized to the highest working pressure of carbon dioxide circulation through the carbon dioxide pump 5. The heat of the atmosphere is then absorbed in the air heat exchanger 6 in turn to raise the temperature, and the heat contained in the exhaust gas of the natural gas boiler 1 is absorbed in the flue gas heat exchanger 7 to gasify. The gaseous carbon dioxide is then heated in the natural gas boiler 1 by the heat energy released by the combustion of the natural gas and air, and is warmed up to the maximum operating temperature of the carbon dioxide cycle. Finally, the gaseous carbon dioxide with certain temperature and pressure enters the carbon dioxide gas turbine 2 to expand and do work, and the shaft work drives the ultralow temperature motor 14 to convert mechanical work into electric energy.
The exhaust gas of the organic working medium gas turbine 8 transfers heat to the liquid natural gas in the organic working medium heat exchanger 9, the gaseous organic working medium is changed into liquid, and the liquid natural gas is pressurized to the highest working pressure of the organic working medium circulation through the organic working medium pump 10. Then the organic working medium sequentially absorbs the heat released by the carbon dioxide circulating exhaust gas in the secondary carbon dioxide heat exchanger 4 and the primary carbon dioxide heat exchanger 3, is converted into a gaseous state, and is heated to the highest working temperature of the organic working medium circulation. Then the gaseous organic working medium with certain temperature and pressure enters the organic working medium gas turbine 8 to expand and do work, and the shaft work drives the ultralow temperature motor 14 to convert the mechanical work into electric energy.
The liquefied natural gas in the liquefied natural gas storage tank 11 is conveyed to the organic working medium heat exchanger 9 through the liquefied natural gas pump 12, and heat released by circulating exhaust of the organic working medium is absorbed. And then enters the secondary carbon dioxide heat exchanger 4 to continuously absorb heat released by the carbon dioxide circulating exhaust. Finally, the heat in the ultralow temperature motor 14 is absorbed in the motor cooling working medium heat exchanger 13 and is converted into gaseous natural gas, and the gaseous natural gas is sent into the natural gas boiler 1 as fuel to react with air chemically, so that heat energy is released.
The motor cooling working medium absorbs heat generated by copper loss, iron loss and eddy current loss in the ultralow temperature motor 14, and the heat is released to natural gas in the motor cooling working medium heat exchanger 13 to cause the natural gas to change phase from liquid state to gas state. And then the motor cooling working medium enters the ultralow temperature motor 14 under the pressurized conveying of the motor cooling working medium pump 15.
The exhaust pressure of the carbon dioxide gas turbine 2 is lower than the critical pressure of carbon dioxide by 7.38MPa.
The operating temperature of the cryogenic motor 14 is below 0 ℃.
The intake air temperature of the carbon dioxide gas turbine 2 is about 630 ℃.
The inlet temperature of the organic working gas turbine 8 is about 150 c and the outlet temperature is about-150 c.
The outlet pressure of the high temperature side of the secondary carbon dioxide heat exchanger 4 can be reduced to 0.55MPa at the lowest, and the temperature is about-55 ℃.
The foregoing is only a part of the embodiments of the present invention, and although some terms are used in the present invention, the use of other terms is not excluded. These terms are used merely for convenience of description and to explain the nature of the invention and are to be construed as any additional limitations that are not intended to depart from the spirit of the invention. The foregoing description of the invention is provided by way of example only to facilitate easy understanding, but is not intended to limit the scope of the invention to any particular embodiment or embodiment, and is to be construed as being limited thereto.
Claims (7)
1. The efficient power generation system based on the liquefied natural gas is characterized by comprising a natural gas boiler (1), a carbon dioxide gas turbine (2), a primary carbon dioxide heat exchanger (3), a secondary carbon dioxide heat exchanger (4), an air heat exchanger (6), a flue gas heat exchanger (7), an organic working medium gas turbine (8), an organic working medium heat exchanger (9), a liquefied natural gas tank (11), a motor cooling working medium heat exchanger (13) and an ultralow temperature motor (14);
the working medium outlet of the natural gas boiler (1) is connected with the inlet of the carbon dioxide gas turbine (2), the outlet of the carbon dioxide gas turbine (2) is connected with the high-temperature side inlet of the primary carbon dioxide heat exchanger (3), the high-temperature side outlet of the primary carbon dioxide heat exchanger (3) is connected with the high-temperature side inlet of the secondary carbon dioxide heat exchanger (4), the high-temperature side outlet of the secondary carbon dioxide heat exchanger (4) is connected with the inlet of the air heat exchanger (6), the outlet of the air heat exchanger (6) is connected with the inlet of the flue gas heat exchanger (7), and the outlet of the flue gas heat exchanger (7) is connected with the working medium inlet of the natural gas boiler (1); the low-temperature side outlet of the primary carbon dioxide heat exchanger (3) is connected with the inlet of the organic working medium gas turbine (8), the outlet of the organic working medium gas turbine (8) is connected with the high-temperature side inlet of the organic working medium heat exchanger (9), the high-temperature side outlet of the organic working medium heat exchanger (9) is connected with the second low-temperature side inlet of the secondary carbon dioxide heat exchanger (4), and the second low-temperature side outlet of the secondary carbon dioxide heat exchanger (4) is connected with the low-temperature side inlet of the primary carbon dioxide heat exchanger (3); the outlet of the liquid natural gas tank (11) is connected with the low-temperature side inlet of the organic working medium heat exchanger (9), the low-temperature side outlet of the organic working medium heat exchanger (9) is connected with the first low-temperature side inlet of the secondary carbon dioxide heat exchanger (4), the first low-temperature side outlet of the secondary carbon dioxide heat exchanger (4) is connected with the low-temperature side inlet of the motor cooling working medium heat exchanger (13), and the low-temperature side outlet of the motor cooling working medium heat exchanger (13) is connected with the fuel inlet of the natural gas boiler (1); the high-temperature side outlet of the motor cooling working medium heat exchanger (13) is connected with the inlet of the motor cooling working medium pump (15), the outlet of the motor cooling working medium pump (15) is connected with the cooling working medium inlet of the ultralow-temperature motor (14), and the cooling working medium outlet of the ultralow-temperature motor (14) is connected with the high-temperature side inlet of the motor cooling working medium heat exchanger (13); the rotor of the ultralow temperature motor (14) is connected with the rotor of the carbon dioxide gas turbine (2) through a coupler, and the rotor of the carbon dioxide gas turbine (2) is connected with the rotor of the organic working medium gas turbine (8) through the coupler; the outlet pressure of the high temperature side of the secondary carbon dioxide heat exchanger (4) is 0.55-7.00 MPa.
2. The efficient power generation system based on liquefied natural gas as claimed in claim 1, wherein a carbon dioxide pump (5) is provided between the high temperature side outlet of the secondary carbon dioxide heat exchanger (4) and the inlet of the air heat exchanger (6); an organic working medium pump (10) is arranged between the high-temperature side outlet of the organic working medium heat exchanger (9) and the second low-temperature side inlet of the secondary carbon dioxide heat exchanger (4); a liquid natural gas pump (12) is arranged between the outlet of the liquid natural gas tank (11) and the low-temperature side inlet of the organic working medium heat exchanger (9); a motor cooling working medium pump (15) is arranged between the high-temperature side outlet of the motor cooling working medium heat exchanger (13) and the cooling working medium inlet of the ultralow-temperature motor (14).
3. Efficient power generation system based on liquefied natural gas according to claim 1, characterized in that the ultra-low temperature motor (14), the carbon dioxide gas turbine (2) and the organic working medium gas turbine (8) are coaxially arranged.
4. The efficient power generation system based on liquid natural gas as claimed in claim 1, wherein the primary carbon dioxide heat exchanger (3) is a printed circuit board heat exchanger, the secondary carbon dioxide heat exchanger (4) is a multi-stream printed circuit board heat exchanger, the air heat exchanger (6) is a printed circuit board heat exchanger, the flue gas heat exchanger (7) is a printed circuit board heat exchanger, the organic working medium heat exchanger (9) is a plate-fin heat exchanger, and the motor cooling working medium heat exchanger (13) is a plate-fin heat exchanger.
5. The working method of the efficient power generation system based on the liquefied natural gas according to any one of claims 1 to 4, which is characterized by comprising the following steps:
the exhaust of the carbon dioxide gas turbine (2) sequentially transfers heat to the organic working medium and the liquid natural gas in the primary carbon dioxide heat exchanger (3) and the secondary carbon dioxide heat exchanger (4), gaseous carbon dioxide is changed into liquid state, then sequentially absorbs heat of the atmosphere in the air heat exchanger (6) for heating, and absorbs heat contained in the exhaust smoke of the natural gas boiler (1) for gasification in the smoke heat exchanger (7); the gaseous carbon dioxide is heated by heat energy released by the combustion of natural gas and air in the natural gas boiler (1), and the temperature is raised to the highest working temperature; the gaseous carbon dioxide enters a carbon dioxide gas turbine (2) to expand and do work, and shaft work drives an ultralow-temperature motor (14) to convert mechanical work into electric energy;
the exhaust of the organic working medium gas turbine (8) transfers heat to the liquid natural gas in the organic working medium heat exchanger (9), the gaseous organic working medium is changed into liquid, then the heat released by the carbon dioxide circulating exhaust in the secondary carbon dioxide heat exchanger (4) and the primary carbon dioxide heat exchanger (3) is sequentially absorbed, the heat is changed into gaseous, and the temperature is raised to the highest working temperature; the gaseous organic working medium enters an organic working medium gas turbine (8) to expand and do work, and shaft work drives an ultralow-temperature motor (14) to convert mechanical work into electric energy;
the method comprises the steps that liquid natural gas in a liquid natural gas tank (11) enters an organic working medium heat exchanger (9), heat released by circulating exhaust of the organic working medium is absorbed, then enters a secondary carbon dioxide heat exchanger (4) to continuously absorb the heat released by circulating exhaust of the carbon dioxide, finally, heat in an ultralow-temperature motor (14) is absorbed in a motor cooling working medium heat exchanger (13) and is converted into gaseous natural gas, and the gaseous natural gas is sent into a natural gas boiler (1) as fuel to be subjected to chemical reaction with air, so that heat energy is released;
the motor cooling working medium absorbs heat generated by copper loss, iron loss and eddy current loss in the ultralow temperature motor (14), and releases natural gas in the motor cooling working medium heat exchanger (13) to be converted from liquid state to gas state, and the motor cooling working medium enters the ultralow temperature motor (14).
6. The method of operating a lng-based efficient power generation system according to claim 5, wherein the exhaust pressure of the carbon dioxide gas turbine (2) is below the critical pressure of carbon dioxide.
7. The method of operating a lng-based efficient power generation system of claim 5, wherein the ultra-low temperature motor (14) operates at a temperature less than 0 ℃.
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| CN103016084A (en) * | 2013-01-04 | 2013-04-03 | 成都昊特新能源技术有限公司 | LNG (Liquefied Natural Gas) cold energy double-turbine power generation system |
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