Liquid compressed air energy storage method and system for utilizing waste heat of circulating water of thermal power generating unit
Technical Field
The invention belongs to the field of steam turbine power generation, and particularly relates to a liquid compressed air energy storage method and system for utilizing waste heat of circulating water of a thermal power generating unit.
Background
At present, renewable energy sources such as wind power and photovoltaic power generation are rapidly emerging, but the intermittency and randomness of the renewable energy sources can cause great impact on a power grid, and further development of the renewable energy sources and the safety and stability of the whole power grid are severely restricted.
The energy storage facility can provide output of smooth power generation, peak clipping and valley filling, and coordinated development between the intermittent renewable energy power source and the power grid is realized. Furthermore, by additionally arranging an energy storage facility on the power generation side, multiple functions of enhancing the adjusting capacity of the unit, effectively supporting renewable energy source grid connection, providing reserve capacity and the like can be realized. In addition, the thermal power generating unit is combined with an energy storage facility, so that the defect that the response time of the thermal power generating unit is slow in adjustment can be partially overcome. Along with the gradual improvement of the flexibility auxiliary service market, the thermal power unit can also exert the flexibility thereof to the maximum potential in an energy storage mode, and the maximization of the economic benefit is realized.
According to the prior art, energy storage is mainly divided into three types, namely mechanical energy storage (pumped storage, compressed air energy storage and flywheel energy storage), electrochemical energy storage (sodium-sulfur battery, flow battery, lead-acid battery and nickel-chromium battery) and electromagnetic energy storage (superconducting magnetic energy storage). But only two modes of pumped storage and compressed air energy storage can be realized at present. The pumped storage mode is greatly restricted by the terrain conditions, and the risk of icing can be caused under the condition of extremely low northern air temperature. The energy storage density of the gaseous compressed air is low, and large storage spaces such as salt pits, caves and the like are needed, so that the storage device is also restricted by the terrain conditions. The liquid air energy storage technology can realize higher energy storage density by liquefying air, has smaller storage space and is not limited by geographical conditions, thereby gaining more and more attention.
The existing liquid air energy storage technology is mainly combined with a renewable energy power generation system, and the research of mutual combination with a thermal power generating unit system is less.
Disclosure of Invention
The invention aims to overcome the defects and provides a liquid compressed air energy storage method and system for utilizing the circulating water waste heat of a thermal power unit, which can realize the free conversion process of energy storage and energy release at the thermal power supply side, and can achieve the dual energy efficiency of deep peak regulation and energy storage of the unit by starting a high-pressure bypass and a low-pressure bypass to operate in the energy storage process.
In order to achieve the purpose, the liquid compressed air energy storage system for utilizing the waste heat of the circulating water of the thermal power generating unit comprises a thermal power turbine, wherein the steam extraction of the thermal power turbine is connected with an absorption heat pump, a steam extraction utilization heat storage heat exchanger of the turbine and a back pressure turbine through pipelines;
the steam extraction utilization heat storage heat exchanger is connected with a steam extraction utilization high-temperature working medium storage tank through a pipeline, the steam extraction utilization high-temperature working medium storage tank is connected with a steam extraction utilization energy release heat exchanger through a pipeline by using working medium of the high-temperature working medium storage tank as a heat source, the working medium outlet of the steam extraction utilization energy release heat exchanger after heat release is connected with a steam extraction utilization low-temperature working medium storage tank, and the steam extraction utilization low-temperature working medium storage tank of the steam turbine is connected with the steam extraction utilization heat storage heat exchanger of the steam turbine;
the back pressure type steam turbine is connected with the multistage indirect cooling compressor, a heat source circulation loop of the multistage indirect cooling compressor is connected with the multistage compression heat collecting heat exchanger, a hot working medium outlet of the multistage compression heat collecting heat exchanger is connected with a compression heat utilization high-temperature working medium storage tank through a pipeline, a compressed air outlet of the multistage indirect cooling compressor is connected with a liquefaction heat exchanger, the liquefaction heat exchanger is connected with a low-temperature expander, the low-temperature expander is connected with a vapor-liquid separator, the vapor-liquid separator is connected with a liquid storage tank, the liquid storage tank is connected with a vaporization heat exchanger, working medium of the high-temperature working medium storage tank is used as a heat source to be connected with the vaporization heat exchanger, a working medium outlet of the vaporization heat exchanger is connected with a compression heat utilization low-temperature working medium storage tank through a pipeline, the compression heat utilization low-temperature working medium storage tank is connected with the multistage compression heat collecting heat exchanger, and a liquid outlet after temperature rise in the vaporization heat exchanger is connected with a circulating water waste heat utilization energy release heat exchanger through a pipeline;
the waste heat water circulation loop of the absorption heat pump is used as a heat source to be connected with a circulating water waste heat utilization heat storage heat exchanger, a heat storage working medium outlet of the circulating water waste heat utilization heat storage heat exchanger is connected with a circulating water waste heat utilization high-temperature working medium storage tank through a pipeline, a working medium of the circulating water waste heat utilization high-temperature working medium storage tank is used as a heat source to be connected with a circulating water waste heat utilization energy release heat exchanger, a heat source outlet of the circulating water waste heat utilization energy release heat exchanger is connected with a circulating water waste heat utilization low-temperature working medium storage tank through a pipeline, a heated working medium outlet of the circulating water waste heat utilization energy release heat exchanger is connected with a steam turbine steam extraction utilization energy release heat exchanger through a pipeline, and an air outlet of the steam turbine steam extraction utilization energy release heat exchanger is connected with a power generation steam turbine.
The low-temperature expander is connected with a low-temperature expander generator.
The absorption heat pump is connected with the circulating water waste heat utilization heat storage heat exchanger through a circulating water waste heat utilization water supply pipeline and a circulating water waste heat utilization water return pipeline.
A condensed water outlet of the thermal power turbine is connected with a condenser, circulating water of the condenser is used as a heat source to be connected with an absorption heat pump, a circulating water outlet of the absorption heat pump is connected with a circulating water pump through a pipeline, and the circulating water pump is connected with the condenser.
The thermal power turbine is connected with the boiler.
The working method of the liquid compressed air energy storage system for utilizing the waste heat of the circulating water of the thermal power generating unit comprises an energy storage process and an energy release process;
the energy storage process comprises the following steps:
s11, dividing steam extracted by a thermal power turbine into three parts, performing heat exchange between the first part of steam and a heat storage working medium in a steam turbine steam extraction utilization heat storage heat exchanger, storing heat energy to a steam turbine steam extraction utilization high-temperature working medium storage tank, driving a back pressure steam turbine by the second part of steam to push a multistage indirect cooling compressor, driving an absorption heat pump by the last part of steam, performing waste heat recovery and utilization on circulating water by the absorption heat pump, performing heat exchange between waste hot water discharged by the absorption heat pump and the heat storage working medium in a circulating water waste heat utilization heat storage heat exchanger, and storing the heat energy in a circulating water waste heat utilization high-temperature working medium storage tank;
s12, the multi-stage indirect cooling compressor compresses air, exchanges heat with the multi-stage compression heat collecting heat exchanger, and stores compression heat to a compression heat utilization high-temperature working medium storage tank;
s13, sending the compressed air into a liquefying heat exchanger to absorb cold energy, cooling and entering a cryogenic state;
s14, the compressed air in the cryogenic state sequentially passes through the low-temperature expander and the vapor-liquid separator, the air liquefied into liquid is stored in the liquid storage tank, the non-liquefied compressed air is sent to the liquefaction heat exchanger, and S13 is executed;
the energy release flow comprises the following steps:
s21, the liquefied air in the liquid storage tank enters a vaporization heat exchanger for regenerative heating, the heat source of the vaporization heat exchanger adopts the compression heat stored in a compression heat utilization high-temperature working medium storage tank, and the circulating working medium after releasing the compression heat enters a compression heat utilization low-temperature working medium storage tank;
s22, the compressed air after temperature rise and vaporization enters a circulating water waste heat utilization and energy release heat exchanger, secondary temperature rise is carried out by utilizing exhaust waste heat energy stored in a circulating water waste heat utilization high-temperature working medium storage tank, and circulating working media after heat release in the circulating water waste heat utilization and energy release heat exchanger enter a circulating water waste heat utilization low-temperature working medium storage tank;
s23, the compressed air after the second temperature rise enters a steam turbine extraction energy-releasing heat exchanger, the steam turbine extraction energy-releasing heat exchanger utilizes heat storage energy stored in a steam turbine extraction energy-utilizing high-temperature working medium storage tank to carry out third temperature rise, and the steam turbine extraction utilizes circulating working media after the heat release of the high-temperature working medium storage tank to enter a steam turbine extraction energy-utilizing low-temperature working medium storage tank;
and S24, the compressed air after being heated for the third time enters a multi-stage energy storage power generation turbine, and expands in the multi-stage energy storage power generation turbine to do work and supply power to the outside.
And S12, cooling the compressed air through heat exchange of the heat-conducting fluid, and storing the compression heat in a compression heat utilization high-temperature working medium storage tank.
And the waste heat water heated by the absorption heat pump enters the circulating water waste heat utilization heat storage heat exchanger to exchange heat with the heat transfer fluid, the heat is released and then enters the steam drive absorption heat pump again, and the heated heat transfer fluid is stored in the circulating water waste heat utilization high-temperature working medium storage tank to store and collect the waste heat.
Compared with the prior art, the system provided by the invention fully utilizes the effective mass-heat energy flow of the thermal power generating unit, reduces the electric energy consumption in the existing energy storage process through process optimization, realizes energy gradient utilization and storage, and improves the overall energy conversion efficiency of energy storage implementation. The high-efficiency coupling application of the energy storage technology and the thermal power generating unit is realized.
The invention combines an energy storage system with a thermal power generating unit, during energy storage, steam is extracted from a steam turbine, part of the steam exchanges heat with high-temperature heat storage working medium in a steam turbine extraction and utilization heat storage heat exchanger, part of the steam drives a back pressure steam turbine to push a multi-stage indirect cooling compressor, part of the steam drives an absorption heat pump to utilize waste heat of circulating water, heated waste hot water at an outlet of a heat pump exchanges heat with the high-temperature heat storage working medium in the circulating water waste heat utilization heat storage heat exchanger, heat energy is stored in a circulating water waste heat utilization high-temperature working medium storage tank, compressed air forms liquefied air through a liquefying heat exchanger and then is stored in a low-temperature liquid tank, and during energy release, the collected compression heat and the stored heat energy in the multi-stage compression process are utilized to carry out temperature increase so as to enhance the energy release turbine capacity to do work. The invention can effectively couple the thermal power generating unit with the liquid air energy storage system, realizes the free conversion process of energy storage and energy release at the thermal power supply side, and has great significance for promoting the consumption of renewable energy and improving the stability of a power grid.
Drawings
FIG. 1 is a system diagram of the present invention;
wherein, 1, a multi-stage energy storage power generation turbine; 2. the circulating water waste heat utilizes an energy releasing heat exchanger; 3. a high-temperature working medium storage tank for utilizing the waste heat of the circulating water; 4. a low-temperature working medium storage tank for utilizing the waste heat of the circulating water; 5. the circulating water waste heat utilizes the heat storage heat exchanger; 6-1, a circulating water waste heat utilization water supply pipeline; 6-2, utilizing the waste heat of the circulating water to a water return pipeline; 7. a high-temperature working medium storage tank is used for extracting steam from the steam turbine; 8. a low-temperature working medium storage tank is used for extracting steam from the steam turbine; 9. the steam extraction of the steam turbine utilizes the energy-releasing heat exchanger; 10. the steam extraction of the steam turbine utilizes a heat storage heat exchanger; 12. a backpressure driven small steam turbine; 13. a multi-stage indirect cooling compressor; 14. a multi-stage compression heat collection heat exchanger; 15. a high-temperature working medium storage tank for utilizing compression heat; 16. a low-temperature working medium storage tank for utilizing compression heat; 17. a vapor-liquid separator; 18. a liquefaction heat exchanger; 19. a low temperature expander; 20. a low temperature expander generator; 21. a liquid storage tank; 22. a vaporizing heat exchanger; 23. a thermal power turbine; 24. a water circulating pump; 25. a boiler; 26. a condenser; 27. an absorption heat pump.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1, the liquid compressed air energy storage system for utilizing the waste heat of the circulating water of the thermal power generating unit comprises a thermal power turbine 23, wherein the steam extraction of the thermal power turbine 23 is connected with an absorption heat pump 27, a steam extraction utilization heat storage heat exchanger 10 of the turbine and a back pressure turbine 12 through pipelines;
the hot working medium outlet of the steam turbine extraction utilization heat storage exchanger 10 is connected with a steam turbine extraction utilization high-temperature working medium storage tank 7 through a pipeline, the steam turbine extraction utilizes the working medium of the high-temperature working medium storage tank 7 as a heat source and is connected with a steam turbine extraction utilization energy release heat exchanger 9 through a pipeline, the working medium outlet of the steam turbine extraction utilization energy release heat exchanger 9 after releasing heat is connected with a steam turbine extraction utilization low-temperature working medium storage tank 8, and the steam turbine extraction utilization low-temperature working medium storage tank 8 is connected with the steam turbine extraction utilization heat storage exchanger 10;
the back pressure turbine 12 is connected with a multistage indirect cooling compressor 13, a heat source circulation loop of the multistage indirect cooling compressor 13 is connected with a multistage compression heat collecting heat exchanger 14, a hot working medium outlet of the multistage compression heat collecting heat exchanger 14 is connected with a compression heat utilization high-temperature working medium storage tank 15 through a pipeline, a compressed air outlet of the multistage indirect cooling compressor 13 is connected with a liquefaction heat exchanger 18, the liquefaction heat exchanger 18 is connected with a low-temperature expander 19, the low-temperature expander 19 is connected with a vapor-liquid separator 17, the vapor-liquid separator 17 is connected with a liquid storage tank 21, the liquid storage tank 21 is connected with a vaporization heat exchanger 22, a working medium of the high-temperature working medium storage tank 15 is used as a heat source and is connected with the vaporization heat exchanger 22, a working medium outlet of the vaporization heat exchanger 22 is connected with a compression heat utilization low-temperature working medium storage tank 16 through a pipeline, the compression heat utilization low-temperature working medium storage tank 16 is connected with the multistage compression heat collecting heat exchanger 14, and a liquid outlet after temperature rise in the vaporization heat exchanger 22 is connected with a circulating water waste heat utilization energy releasing heat exchanger 2 through a pipeline;
the waste heat water circulation loop of the absorption heat pump 27 is used as a heat source to be connected with a circulating water waste heat utilization heat storage heat exchanger 5, a heat storage working medium outlet of the circulating water waste heat utilization heat storage heat exchanger 5 is connected with a circulating water waste heat utilization high-temperature working medium storage tank 3 through a pipeline, a working medium of the circulating water waste heat utilization high-temperature working medium storage tank 3 is used as a heat source to be connected with a circulating water waste heat utilization energy release heat exchanger 2, a heat source outlet in the circulating water waste heat utilization energy release heat exchanger 2 is connected with a circulating water waste heat utilization low-temperature working medium storage tank 4 through a pipeline, a heated working medium outlet of the circulating water waste heat utilization energy release heat exchanger 2 is connected with a steam turbine extraction utilization energy release heat exchanger 9 through a pipeline, and an air outlet of the steam turbine extraction utilization energy release heat exchanger 9 is connected with a power generation steam turbine 1.
The low temperature expander 19 is connected to a low temperature expander generator 20.
The absorption heat pump 27 is connected with the circulating water waste heat utilization heat storage heat exchanger 5 through a circulating water waste heat utilization water supply pipeline 6-1 and a circulating water waste heat utilization water return pipeline 6-2.
A condensed water outlet of the thermal power turbine 23 is connected with a condenser 26, circulating water of the condenser 26 is used as a heat source and is connected with an absorption heat pump 27, a circulating water outlet of the absorption heat pump 27 is connected with a circulating water pump 24 through a pipeline, and the circulating water pump 24 is connected with the condenser 26.
The thermal power turbine 23 is connected to a boiler 25.
The steam extraction of the steam turbine utilizes a high-temperature working medium storage tank 7 for storing heat energy of extracted steam;
the circulating water waste heat utilization high-temperature working medium storage tank 3 is used for storing circulating water waste heat energy;
the multi-stage indirect cooling compressor 13 is used for compressing air;
the multi-stage compression heat collection heat exchanger 14 is used for collecting compression heat during air compression and storing the compression heat in a compression heat utilization high-temperature working medium storage tank 15;
the liquefaction heat exchanger 22 is used for absorbing the cold energy of the compressed air and cooling the compressed air to enter a cryogenic state;
the low-temperature expander 19 is used for reducing the pressure and temperature of the compressed air in the cryogenic state;
the vapor-liquid separator 17 is used for separating liquid air and gaseous air;
the reservoir tank 21 is for storing liquid air.
The heat storage working medium of the high-temperature heat storage cycle can be binary molten salt, liquid metal, carbon-containing chemical liquid and the like.
Referring to fig. 1, the working method of the liquid compressed air energy storage system for utilizing the waste heat of the circulating water of the thermal power generating unit comprises an energy storage process and an energy release process;
the energy storage process comprises the following steps:
s11, dividing steam extracted by a thermal power turbine 23 into three parts, performing heat exchange between the first part of steam and a heat storage working medium in a steam turbine steam extraction utilization heat storage heat exchanger 10, storing heat energy to a steam turbine steam extraction utilization high-temperature working medium storage tank 7, driving a back pressure steam turbine 12 to push a multistage intercooling compressor 13 by the second part of steam, driving an absorption heat pump 27 by the last part of steam, performing waste heat recovery and utilization on circulating water by the absorption heat pump 27, performing heat exchange between waste heat water discharged by the absorption heat pump 27 and the heat storage working medium in a circulating water waste heat utilization heat storage heat exchanger 5, and storing the heat energy in a circulating water waste heat utilization high-temperature working medium storage tank 3;
s12, the multistage indirect cooling compressor 13 compresses air, exchanges heat with the multistage compression heat collecting heat exchanger 14, and stores compression heat to the compression heat utilization high-temperature working medium storage tank 15; the compressed air is cooled through heat exchange of the heat-conducting fluid, and the compression heat is stored in the compression heat utilization high-temperature working medium storage tank 15.
S13, sending the compressed air into the liquefying heat exchanger 18 to absorb cold energy, cooling and entering a cryogenic state;
s14, the compressed air in the cryogenic state sequentially passes through the low-temperature expansion machine 19 and the gas-liquid separator 17, the air is liquefied into liquid and stored in the liquid storage tank 21, the non-liquefied compressed air is sent to the liquefying heat exchanger 18, and S13 is executed;
the energy release flow comprises the following steps:
s21, the liquefied air in the liquid storage tank 21 enters the vaporization heat exchanger 22 for regenerative heating, the heat source of the vaporization heat exchanger 22 adopts the compression heat stored in the compression heat utilization high-temperature working medium storage tank 15, and the cycle working medium after releasing the compression heat enters the compression heat utilization low-temperature working medium storage tank 16;
s22, the heated and vaporized compressed air enters a circulating water waste heat utilization and energy release heat exchanger 2, secondary heating is carried out by utilizing the exhaust waste heat energy stored in a circulating water waste heat utilization high-temperature working medium storage tank 3, and the circulating working medium discharged from the circulating water waste heat utilization and energy release heat exchanger 2 enters a circulating water waste heat utilization low-temperature working medium storage tank 4;
s23, the compressed air after the second temperature rise enters a steam turbine extraction steam utilization energy release heat exchanger 9, the steam turbine extraction steam utilization energy release heat exchanger 9 utilizes heat storage energy stored in a steam turbine extraction steam utilization high-temperature working medium storage tank 7 to carry out third temperature rise, and the steam turbine extraction steam utilizes a circulating working medium after heat release of the high-temperature working medium storage tank 7 to enter a steam turbine extraction steam utilization low-temperature working medium storage tank 8;
and S24, the compressed air after being heated for the third time enters the multi-stage energy storage power generation turbine 1, and expands in the multi-stage energy storage power generation turbine 1 to do work and supply power to the outside.
The low-temperature expansion machine 19 drives the generator set to generate electric energy to compensate the consumption of the service power of the thermal power unit.
The waste heat water heated by the absorption heat pump 27 enters the circulating water waste heat utilization heat storage heat exchanger 5 to exchange heat with the heat transfer fluid, the heat is released and then enters the steam drive absorption heat pump 27 again, and the heated heat transfer fluid is stored in the circulating water waste heat utilization high-temperature working medium storage tank 3 to store and collect the waste heat.
After the energy storage process begins, the steam turbine starts the operation mode of the high-low bypass, most of flow from the extraction steam of the high-low bypass of the thermal power generating unit exchanges heat with the heat storage working medium in the high-temperature steam heat exchanger, high-quality heat is stored in the high-temperature working medium heat storage tank, and the heat released by the steam forms drain water to flow back to the thermal system of the steam turbine. In the energy releasing process, the high-temperature working medium heat storage tank flows out through circulation, circulates to the air temperature raising heat exchanger to exchange heat with the vaporized air working medium, and is heated to a high-temperature state, so that the acting capacity of the energy storage power generation turbine is effectively enhanced.
In the energy releasing process, liquefied air in the low-temperature liquid tank is sucked into the low-temperature pump to increase the pressure, firstly, the collected compression heat in the multi-stage compression process is utilized to carry out regenerative heating in the vaporization heat exchanger to raise the temperature for vaporization, then, the residual heat water energy storage heat and the extracted steam energy storage heat are respectively facilitated to further increase the temperature of the inlet of the power generation turbine, and the working capacity of the compressed air is improved. And then the compressed air enters an energy storage power generation turbine, expands in the turbine to do work and supplies power to the outside.