Coal-fired power plant energy storage peak shaving system

Abstract

The application provides a coal-fired power plant energy storage peak shaving system, which comprises a power generation unit and an adjusting unit, the power generation unit is connected with a second generator, the adjusting unit comprises an energy storage module and an energy release module; the energy storage module comprises a first storage tank, a compressor and a second storage tank which are sequentially connected, and further comprises a first heat exchanger; the first heat exchanger is connected with the compressor and the power generation unit respectively, so that the carbon dioxide compressed by the compressor is cooled by the condensate water in the power generation unit; the energy release module comprises the second storage tank, an expander and the first storage tank which are sequentially connected, and further comprises a second heat exchanger, the output shaft of the expander is connected with a first generator; the second heat exchanger is connected with the expander and the power generation unit respectively, so that the carbon dioxide expanded by the expander is heated by the hot steam in the power generation unit. The coal-fired power plant energy storage peak shaving system provided by the application aims to reduce the volume of the low-pressure gas storage chamber in the compressed gas energy storage, simplify the energy storage structure and reduce the energy consumption in the energy storage process.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology for coal-fired power plants, and more specifically, relates to an energy storage and peak-shaving system for coal-fired power plants. Background Technology

[0002] Currently, thermal power generating units still undertake the main peak-shaving tasks of the power grid. Existing energy storage peak-shaving methods mainly include pumped hydro storage, flywheel energy storage, electrochemical energy storage, and compressed air energy storage.

[0003] Pumped hydro storage involves pumping water from a lower reservoir to an upper reservoir during off-peak electricity demand, converting electrical energy into gravitational potential energy for storage. Its overall efficiency is between 70% and 80%, but it has high requirements for geographical conditions, limiting its application environment. Electrochemical energy storage includes lead-acid batteries, lithium-ion batteries, flow batteries, and sodium-sulfur batteries, characterized by high efficiency and fast response, but low energy density and short lifespan. Flywheel energy storage utilizes an electric motor to drive a flywheel at high speed, converting electrical energy into kinetic energy for storage. When needed, the flywheel drives a generator to produce electricity. Flywheel energy storage is an energy storage method, but it suffers from drawbacks such as insufficient energy density and high self-discharge rate, with energy automatically depleted within a few to tens of hours. It is suitable for grid frequency regulation and power quality assurance. Compressed air energy storage refers to using electrical energy to compress air during periods of low grid load and releasing the compressed air to drive a steam turbine to generate electricity during periods of high load. However, air has a critical temperature of -140.74℃ and a critical pressure of 3.77MPa, resulting in poor physical properties. This low temperature places high demands on component materials, leading to difficulties in achieving cryogenic liquid storage. Furthermore, low-pressure air storage chambers are too large, making it difficult to find suitable containers for storage. Summary of the Invention

[0004] The aim is to reduce the volume of the low-pressure gas storage chamber in compressed gas energy storage, simplify the energy storage structure, and reduce energy consumption during the energy storage process.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a coal-fired power plant energy storage and peak-shaving system, including a power generation unit and a regulating unit, wherein the power generation unit is connected to a second generator and is used to drive the second generator to work, and the regulating unit includes an energy storage module and an energy release module;

[0006] The energy storage module includes a first storage tank, a compressor, and a second storage tank connected in sequence, and also includes a first heat exchanger. The carbon dioxide pressure in the second storage tank is higher than that in the first storage tank. The first heat exchanger is connected to the compressor and the power generation unit respectively, and the condensate in the power generation unit cools the carbon dioxide compressed by the compressor.

[0007] The energy release module includes a second storage tank, an expander, and a first storage tank connected in sequence, and also includes a second heat exchanger. The output shaft of the expander is connected to a first generator. The second heat exchanger is connected to both the expander and the power generation unit, and uses the hot steam in the power generation unit to heat the carbon dioxide that has been expanded by the expander.

[0008] In one possible implementation, there are multiple compressors connected in series, and the outlet pipe of each compressor exchanges heat with the condensate generated by the power generation unit through the first heat exchanger.

[0009] In one possible implementation, there are multiple expanders connected in series, and the outlet pipe of each expander exchanges heat with the hot steam generated by the power generation unit through the second heat exchanger.

[0010] In one possible implementation, the power generation unit includes a boiler module, a high-pressure cylinder module, a medium-pressure cylinder module, a low-pressure cylinder module, a condenser module, a low-pressure heating module, a deaerator module, and a high-pressure heating module. Steam in the boiler module passes sequentially through the high-pressure cylinder module, the medium-pressure cylinder module, the low-pressure cylinder module, the condenser module, the low-pressure heating module, the deaerator module, and the high-pressure heating module before returning to the boiler module. The output terminal of the low-pressure cylinder module is connected to the second generator.

[0011] The condensate discharged from the condensation module is diverted and flows back to the low-pressure heating module after passing through the first heat exchanger. The hot steam in the medium-pressure cylinder module is diverted and flows back to the low-pressure heating module after passing through the second heat exchanger.

[0012] In one possible implementation, the energy storage module further includes a steam turbine connected to the drive unit of the compressor, with the steam inlet of the steam turbine connected to the intermediate pressure cylinder module and the steam exhaust of the steam turbine connected to the condensation module.

[0013] In one possible implementation, the energy storage module further includes an evaporator disposed between the first storage tank and the compressor.

[0014] In one possible implementation, the energy release module further includes a cooler disposed between the expander and the first storage tank.

[0015] In one possible implementation, the deaerator module includes a deaerator and a second water pump connected in sequence. The deaerator is connected to the low-pressure heating module, the second water pump is connected to the high-pressure heating module, and the intermediate-pressure cylinder module is also connected to the deaerator.

[0016] In one possible implementation, the high-pressure cylinder module is also connected to the high-pressure heating module, and the high-pressure cylinder module is used to introduce hot steam into the high-pressure heating module.

[0017] In one possible implementation, the exhaust end of the intermediate-pressure cylinder module is also connected to the high-pressure heating module, the low-pressure heating module, and the deaerator, respectively.

[0018] The beneficial effects of the coal-fired power plant energy storage and peak-shaving system provided by this invention are as follows: Compared with the prior art, this invention cools the condensate in the power generation unit by exchanging heat with compressed carbon dioxide, and heats it by exchanging heat with the hot steam generated by the power generation unit with expanding carbon dioxide, achieving isothermal compression and isothermal expansion, thus avoiding the additional energy consumption generated by mechanical heat exchange. Carbon dioxide has advantages over air, such as high density, good thermal conductivity, and low critical parameters, making it easy to reach the critical state. Using carbon dioxide as an energy storage medium not only effectively improves the thermal performance of the system and reduces the volume of the first storage tank, but also fully utilizes carbon dioxide to achieve the goal of reducing carbon emissions. By achieving isothermal compression and isothermal expansion, the power consumption of the compressor can be reduced, and the output power of the expander can be increased, thereby significantly improving the cycle efficiency of the energy storage system. When the power generation unit has excess capacity, the excess energy is stored through the energy storage module; when the power generation cannot meet normal needs, the first motor is driven by the energy release module to increase the power generation, which can effectively regulate the power generation and reduce energy loss. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a coal-fired power plant energy storage and peak-shaving system provided in an embodiment of the present invention.

[0021] In the picture:

[0022] 1. Adjustment unit;

[0023] 10. Energy storage module; 101. First storage tank; 102. Evaporator; 103. Compressor; 104. First heat exchanger; 105. Steam turbine;

[0024] 11. Energy release module; 111. Second storage tank; 112. Second heat exchanger; 113. Expander; 114. Refrigerator; 115. First generator;

[0025] 2. Power generation unit;

[0026] 20. Boiler module;

[0027] 21. High-pressure cylinder module;

[0028] 22. Medium-pressure cylinder module;

[0029] 23. Low-pressure cylinder module;

[0030] 24. Second generator;

[0031] 25. Condensing module; 251. Condenser; 252. First water pump;

[0032] 26. Low-pressure heating module; 261. Low-pressure heater;

[0033] 27. Deaeration module; 271. Deaerator; 272. Second water pump;

[0034] 28. High-pressure heating module; 281. High-pressure heater. Detailed Implementation

[0035] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0036] Please see Figure 1 The present invention will now describe the energy storage and peak shaving system for a coal-fired power plant. The energy storage and peak shaving system for a coal-fired power plant includes a power generation unit 2 and a regulating unit 1. The power generation unit 2 is connected to a second generator 24 and is used to drive the second generator 24 to work. The regulating unit 1 includes an energy storage module 10 and an energy release module 11.

[0037] The energy storage module 10 includes a first storage tank 101, a compressor 103, and a second storage tank 111 connected in sequence, and also includes a first heat exchanger 104. The carbon dioxide pressure in the second storage tank 111 is higher than the carbon dioxide pressure in the first storage tank 101. The first heat exchanger 104 is connected to the compressor 103 and the power generation unit 2 respectively, and uses the condensate in the power generation unit 2 to cool the carbon dioxide compressed by the compressor 103.

[0038] The energy release module 11 includes a second storage tank 111, an expander 113 and a first storage tank 101 connected in sequence, and also includes a second heat exchanger 112. The output shaft of the expander 113 is connected to the first generator 115, and the second heat exchanger 112 is connected to the expander 113 and the power generation unit 2 respectively, so as to heat the expanded carbon dioxide with the hot steam in the power generation unit 2.

[0039] The coal-fired power plant energy storage and peak-shaving system provided by this invention, compared with the prior art, uses condensate from the power generation unit 2 to exchange heat with compressed carbon dioxide in the first heat exchanger 104 to cool it down, and hot steam generated by the power generation unit 2 to exchange heat with expanding carbon dioxide in the second heat exchanger 112 to raise its temperature, thus avoiding the additional energy consumption generated by mechanical heat exchange. Carbon dioxide has advantages over air, such as high density, good thermal conductivity, and low critical parameters, making it easy to reach the critical state. Using carbon dioxide as the energy storage medium not only effectively improves the thermal performance of the system and reduces the volume of the first storage tank 101, but also makes full use of carbon dioxide to achieve the goal of reducing carbon emissions. By achieving isothermal compression and isothermal expansion, the system can reduce the power consumption of the compressor 103 and increase the output power of the expander 113, thereby significantly improving the cycle efficiency of the energy storage system. When the power generation unit 2 has excess capacity, the excess energy is stored through the energy storage module 10; when the power generation cannot meet normal needs, the first motor is driven by the energy release module 11 to increase the power generation, which can effectively regulate the power generation and reduce energy loss.

[0040] Optionally, the condensate in the first heat exchanger 104 exchanges heat with the compressed carbon dioxide and then flows back to the power generation unit 2. The temperature of the condensate in the first heat exchanger 104 increases after heat exchange, which can reduce the energy consumed by the power generation unit 2 to heat the condensate and improve the thermal efficiency of the power generation unit 2.

[0041] Work process:

[0042] When the energy generated by power generation unit 2 is just enough to meet the needs, power generation unit 2 drives the second generator 24 to run, and energy storage module 10 and energy release module 11 are both turned off.

[0043] When the power generation unit 2 has excess energy, the energy storage module 10 is turned on and the energy release module 11 is turned off. The low-pressure carbon dioxide in the first storage tank 101 is increased in pressure after passing through the compressor 103. The carbon dioxide releases heat during the compression process. The first heat exchanger 104 exchanges heat with the heated carbon dioxide to lower the temperature of the carbon dioxide, ensuring the compression efficiency of the carbon dioxide. The compressed carbon dioxide enters the second storage tank 111 for storage.

[0044] When the power generation unit 2 is insufficient, the energy release module 11 is turned on and the energy storage module 10 is turned off. The high-pressure carbon dioxide in the second storage tank 111 enters the expander 113 to expand and reduce pressure. During the expansion of carbon dioxide, heat is released, causing the temperature to drop. The second heat exchanger 112 exchanges heat with the carbon dioxide to raise its temperature and maintain a constant temperature state to ensure the expansion efficiency of carbon dioxide. After the carbon dioxide expands and reduces pressure, it enters the first storage tank 101 for storage. The mechanical energy generated during the expansion of carbon dioxide drives the first generator 115 to work. The first generator 115 and the second generator 24 work simultaneously to ensure that the power demand is met.

[0045] It should be noted that storing liquid carbon dioxide in the first storage tank 101 can effectively reduce the volume of the first storage tank 101.

[0046] In some embodiments, please refer to Figure 1 There are multiple compressors 103, and the multiple compressors 103 are connected in series. The outlet pipe of each compressor 103 exchanges heat with the condensate generated by the power generation unit 2 through the first heat exchanger 104.

[0047] Multiple compressors 103 can be set up to achieve multi-stage compression. The first heat exchanger 104 exchanges heat with the carbon dioxide compressed by the compressor 103 to achieve step-by-step cooling, making it closer to the isothermal compression process and reducing the power consumption of the compressor 103 during the compression process.

[0048] Optionally, the drive units of multiple compressors 103 can be connected in sequence to enable multiple compressors 103 to work synchronously.

[0049] In some embodiments, please refer to Figure 1 Multiple expanders 113 are provided, and the multiple expanders 113 are connected in series. The outlet pipe of each expander 113 is connected to the hot steam generated by the power generation unit 2 through the second heat exchanger 112.

[0050] Multiple expanders 113 can be set up to achieve multi-stage expansion. The second heat exchanger 112 exchanges heat with the carbon dioxide after it has expanded by the expander 113 to achieve step-by-step heating, making the expansion process closer to the isothermal expansion process, which greatly improves the efficiency and economy of the energy release module 11.

[0051] Optionally, the drive units of multiple expanders 113 are connected in sequence, which can enable multiple expanders 113 to work synchronously.

[0052] In some embodiments, please refer to Figure 1 The power generation unit 2 includes a boiler module 20, a high-pressure cylinder module 21, a medium-pressure cylinder module 22, a low-pressure cylinder module 23, a condensing module 25, a low-pressure heating module 26, a deaerator module 27, and a high-pressure heating module 28. The steam in the boiler module 20 flows back to the boiler module 20 after passing through the high-pressure cylinder module 21, the medium-pressure cylinder module 22, the low-pressure cylinder module 23, the condensing module 25, the low-pressure heating module 26, the deaerator module 27, and the high-pressure heating module 28 in sequence. The output end of the low-pressure heating module 26 is connected to the second generator 24.

[0053] The condensate discharged from the condensation module 25 is diverted, passes through the first heat exchanger 104, and then flows back to the low-pressure heating module 26. The hot steam in the medium-pressure cylinder module 22 is diverted, passes through the second heat exchanger 112, and then flows back to the low-pressure heating module 26.

[0054] In this embodiment, the boiler system sequentially feeds hot steam into the high-pressure cylinder module 21, the medium-pressure cylinder module 22, and the low-pressure cylinder module 23 for expansion and work, driving the second generator 24. High-temperature steam is introduced from the exhaust end of the low-pressure cylinder module 23 into the condensing module 25. After being condensed into liquid, the steam enters the low-pressure heating module 26 for heating, then enters the deaeration module 27 for deaeration, and finally enters the high-pressure heating module 28 for heating before entering the boiler module 20, achieving cyclic power generation. The condensing module 25 condenses the gas discharged from the low-pressure cylinder module 23 into liquid, which is then introduced into the first heat exchanger 104 to exchange heat with the carbon dioxide in the compressor 103. The liquid in the first heat exchanger 104 heats up and then enters the low-pressure heating module 26, achieving the recycling of condensate. The increased temperature of the condensate after heat exchange reduces the energy consumption required for heating the liquid in the low-pressure heating module 26, improving thermal efficiency and saving energy. The hot steam in the medium-pressure cylinder module 22 enters the second heat exchanger 112 and exchanges heat with the carbon dioxide in the expander 113. After the temperature decreases, it enters the low-pressure heater 261 for heating, realizing the recycling of steam. There is no need for an external heater to heat the carbon dioxide in the expander 113, which reduces energy consumption and realizes the recycling of energy.

[0055] As one specific embodiment of the condensing module 25, the condensing module 25 includes a condenser 251 and a first water pump 252 connected in sequence, with the condenser 251 located upstream of the first water pump 252.

[0056] Optionally, the low-pressure heating module 26 includes a plurality of low-pressure heaters 261 connected in series, and the high-pressure heating module 28 includes a plurality of high-pressure heaters 281 connected in series.

[0057] In some embodiments, please refer to Figure 1 The energy storage module 10 also includes a steam turbine 105 connected to the drive unit of the compressor 103. The steam inlet of the steam turbine 105 is connected to the intermediate pressure cylinder module 22, and the steam outlet of the steam turbine 105 is connected to the condensation module 25.

[0058] The intermediate-pressure cylinder module 22 supplies high-temperature steam to the steam turbine 105, which drives the turbine 105 to operate. This in turn, the turbine 105 controls the compressor 103. The steam discharged from the turbine 105 enters the condensation module 25 for cooling and liquefaction, and then enters the low-temperature heating module for recirculation. In this embodiment, the high-temperature steam generated by the intermediate-pressure cylinder module 22 controls the operation of the steam turbine 105, thereby driving the compressor 103. This eliminates the need for an external power source to drive the compressor 103, reducing energy consumption and energy conversion losses, and improving thermal efficiency.

[0059] In some embodiments, please refer to Figure 1 The energy storage module 10 also includes an evaporator 102 located between the first storage tank 101 and the compressor 103.

[0060] The first storage tank 101 contains liquid carbon dioxide. After the liquid carbon dioxide exchanges heat with the external air through the evaporator 102, it vaporizes to form carbon dioxide gas, which is beneficial for the compressor 103 to compress and pressurize it.

[0061] In some embodiments, please refer to Figure 1 The energy release module 11 also includes a cooler 114 located between the expander 113 and the first storage tank 101.

[0062] The cooler 114 cools and liquefies the carbon dioxide gas processed by the expander 113, and then introduces it into the first storage tank 101, reducing the volume occupied by the first storage tank 101.

[0063] In some embodiments, please refer to Figure 1 The deaerator module 27 includes a deaerator 271 and a second water pump 272 connected in sequence. The deaerator 271 is connected to the low-pressure heating module 26, the second water pump 272 is connected to the high-pressure heating module 28, and the intermediate-pressure cylinder module 22 is also connected to the deaerator 271.

[0064] The deaerator 271 deoxygenates the water heated by the low-pressure heating module 26, and the second water pump 272 passes the deoxygenated water into the high-pressure heating module 28 to avoid corrosion of the pipeline and improve the service life of the entire system.

[0065] In some embodiments, please refer to Figure 1 The high-pressure cylinder module 21 is also connected to the high-pressure heating module 28, and the high-pressure cylinder module 21 is used to introduce hot steam into the high-pressure heating module 28.

[0066] The hot steam in the high-pressure cylinder module 21 heats the water in the high-pressure heating module 28, reducing the energy consumption of the boiler module 20 for heating.

[0067] In some embodiments, please refer to Figure 1 The exhaust end of the intermediate pressure cylinder module 22 is also connected to the high pressure heating module 28, the low pressure heating module 26 and the deaerator 271 respectively.

[0068] The steam in the intermediate pressure cylinder module 22 exchanges heat with the water in the deaerator 271, increasing the temperature of the water in the deaerator 271 and reducing the energy consumed by the subsequent boiler module 20 for heating.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coal-fired power plant energy storage and peak-shaving system, characterized in that, It includes a power generation unit and a regulation unit. The power generation unit is connected to a second generator and is used to drive the second generator to work. The regulation unit includes an energy storage module and an energy release module. The energy storage module includes a first storage tank, a compressor, and a second storage tank connected in sequence, and also includes a first heat exchanger. The carbon dioxide pressure in the second storage tank is higher than that in the first storage tank. The first heat exchanger is connected to the compressor and the power generation unit respectively, and the condensate in the power generation unit cools the carbon dioxide compressed by the compressor. The energy release module includes a second storage tank, an expander, and a first storage tank connected in sequence, and also includes a second heat exchanger. The output shaft of the expander is connected to a first generator. The second heat exchanger is connected to the expander and the power generation unit respectively, so that the hot steam in the power generation unit heats up the carbon dioxide that has been expanded by the expander. The power generation unit includes a boiler module, a high-pressure cylinder module, a medium-pressure cylinder module, a low-pressure cylinder module, a condenser module, a low-pressure heating module, a deaerator module, and a high-pressure heating module. The steam in the boiler module passes sequentially through the high-pressure cylinder module, the medium-pressure cylinder module, the low-pressure cylinder module, the condenser module, the low-pressure heating module, the deaerator module, and the high-pressure heating module before flowing back to the boiler module. The output end of the low-pressure cylinder module is connected to the second generator. The condensate discharged from the condensation module is diverted and returned to the low-pressure heating module after passing through the first heat exchanger, realizing the recycling of condensate. The temperature of the condensate increases after heat exchange, which can reduce the energy consumption required by the low-pressure heating module to heat the liquid. The hot steam in the medium-pressure cylinder module is diverted and returned to the low-pressure heating module after passing through the second heat exchanger, realizing the recycling of steam. There is no need for an external heater to heat the carbon dioxide in the expander, which reduces energy consumption.

2. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The compressor is provided in multiple units, and the multiple compressors are connected in series. The outlet pipe of each compressor exchanges heat with the condensate generated by the power generation unit through the first heat exchanger.

3. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The expander is provided in multiple units, and the multiple expanders are connected in series. The outlet pipe of each expander exchanges heat with the hot steam generated by the power generation unit through the second heat exchanger.

4. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The energy storage module also includes a steam turbine connected to the drive unit of the compressor. The steam inlet of the steam turbine is connected to the intermediate pressure cylinder module, and the steam exhaust of the steam turbine is connected to the condensation module.

5. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The energy storage module also includes an evaporator located between the first storage tank and the compressor.

6. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The energy release module also includes a cooler located between the expander and the first storage tank.

7. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The deaerator module includes a deaerator and a second water pump connected in sequence. The deaerator is connected to the low-pressure heating module, the second water pump is connected to the high-pressure heating module, and the medium-pressure cylinder module is also connected to the deaerator.

8. The coal-fired power plant energy storage and peak-shaving system as described in claim 1, characterized in that, The high-pressure cylinder module is also connected to the high-pressure heating module, and the high-pressure cylinder module is used to introduce hot steam into the high-pressure heating module.

9. The coal-fired power plant energy storage and peak-shaving system as described in claim 7, characterized in that, The exhaust end of the intermediate-pressure cylinder module is also connected to the high-pressure heating module, the low-pressure heating module, and the deaerator, respectively.

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