Thermo-chemical absorption energy storage combined with thermal power generating unit system and working method thereof

Abstract

The application discloses a kind of thermochemical absorption energy storage combined thermal power generating unit system and its working method, the outlet of carbon dioxide compressor is sequentially communicated with the inlet of energy storage power generation steam turbine by the secondary side of first heat exchanger, supercritical carbon dioxide high-pressure storage tank, the primary side of second heat exchanger and the secondary side of third heat exchanger, the outlet of energy storage power generation steam turbine is communicated with the inlet of chemical absorption carbon dioxide low-pressure storage tank by the secondary side of second heat exchanger, the gas outlet of chemical absorption carbon dioxide low-pressure storage tank is communicated with the inlet of gas-liquid separator, the gas outlet of gas-liquid separator is communicated with the inlet of carbon dioxide compressor, the system and its working method can improve energy storage density, system service life and response rate under the premise of ensuring the stability of thermal power generating unit energy storage system.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive thermal energy utilization technology, and relates to a thermochemical absorption and energy storage combined thermal power unit system and its working method. Background Technology

[0002] With the rapid development of new energy sources, but influenced by natural factors, these new energy sources exhibit significant volatility, posing a major challenge to the safe and stable operation of the power system. Therefore, a symbiotic and complementary development of thermal power and new energy sources is necessary. Currently, when thermal power units operate at low loads, furnace parameters decrease, reducing unit thermal efficiency, and the flue gas temperature at the boiler tail end decreases, affecting denitrification and causing environmental pollution. Furthermore, the difference between daytime and nighttime electricity loads during peak periods is enormous, and the capacity of thermal power units is limited. Therefore, flexibly coupling energy storage systems with thermal power units is of great significance for improving the peak-shaving capacity of thermal power units.

[0003] Currently, most compressed carbon dioxide energy storage systems increase energy density by storing it in liquefaction form. However, the energy input increases dramatically during the liquefaction process, and liquefaction tanks are prone to cold brittleness. Some studies have used tanks filled with physical adsorbents as low-pressure tanks, which have achieved considerable carbon dioxide storage density and improved system stability. However, their response speed and cycle life need to be improved. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a thermochemical absorption energy storage combined thermal power unit system and its working method. This system and its working method can improve energy storage density, system service life and response rate while ensuring the stability of the thermal power unit energy storage system.

[0005] To achieve the above objectives, this invention discloses a thermochemical absorption energy storage combined thermal power unit system, including a carbon dioxide compressor, a first heat exchanger, a supercritical carbon dioxide high-pressure storage tank, a second heat exchanger, a third heat exchanger, an energy storage power generation turbine, a chemical absorption carbon dioxide low-pressure storage tank, and a gas-liquid separator.

[0006] The outlet of the carbon dioxide compressor is sequentially connected to the inlet of the energy storage power generation turbine via the secondary side of the first heat exchanger, the supercritical carbon dioxide high-pressure storage tank, the primary side of the second heat exchanger, and the secondary side of the third heat exchanger. The outlet of the energy storage power generation turbine is connected to the inlet of the chemically absorbed carbon dioxide low-pressure storage tank via the secondary side of the second heat exchanger. The gas outlet of the chemically absorbed carbon dioxide low-pressure storage tank is connected to the inlet of the gas-liquid separator. The gas outlet of the gas-liquid separator is connected to the inlet of the carbon dioxide compressor. The chemically absorbed carbon dioxide low-pressure storage tank is equipped with a spray layer, a first heat exchange tube, and a second heat exchange tube. The chemically absorbed carbon dioxide low-pressure storage tank contains a carbon dioxide chemical absorbent. The first heat exchange tube and the second heat exchange tube are located within the carbon dioxide chemical absorbent. The circulating liquid outlet of the chemically absorbed carbon dioxide low-pressure storage tank is connected to the inlet of the spray layer.

[0007] The liquid outlet of the gas-liquid separator is connected to the inlet of the low-pressure storage tank for chemical absorption of carbon dioxide.

[0008] It also includes a condensate inlet pipe, a first electric shut-off valve, and a condensate outlet pipe;

[0009] The condensate inlet pipe is connected to the inlet of the first heat exchange tube via the first electric shut-off valve, and the outlet of the first heat exchange tube is connected to the condensate outlet pipe.

[0010] It also includes the extraction steam inlet pipe, the second electric shut-off valve, and the extraction steam outlet pipe;

[0011] The extraction steam input pipeline is connected to the inlet of the second heat exchange tube via the second electric shut-off valve, and the outlet of the second heat exchange tube is connected to the extraction steam output pipeline.

[0012] It also includes water supply pipelines, boilers, high-pressure cylinders, back-pressure steam turbines, intermediate-pressure cylinders, low-pressure cylinders, condensers, and condensate pumps;

[0013] The feedwater pipeline is connected to the boiler inlet. The main steam outlet of the boiler is connected to the inlet of the high-pressure cylinder and the inlet of the back-pressure turbine. The outlet of the high-pressure cylinder is connected to the reheat side inlet of the boiler. The reheat side outlet of the boiler is connected to the inlet of the intermediate-pressure cylinder and the primary side inlet of the third heat exchanger. The outlet of the intermediate-pressure cylinder is connected to the inlet of the low-pressure cylinder. The outlet of the low-pressure cylinder is connected to the primary side of the first heat exchanger via the condenser and condensate pump.

[0014] The extraction steam input pipeline is connected to the extraction steam port of the low-pressure cylinder, the condensate output pipeline is connected to the low-pressure heater, the extraction steam output pipeline is connected to the condenser, the outlet of the back-pressure steam turbine is connected to the industrial steam supply pipeline, and the primary side outlet of the third heat exchanger is connected to the deaerator.

[0015] It also includes a first generator, a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, and the first generator arranged coaxially.

[0016] It also includes a second generator, the output shaft of which is connected to the drive shaft of the energy storage power generation turbine.

[0017] The output shaft of the back-pressure steam turbine is connected to the drive shaft of the carbon dioxide compressor.

[0018] This invention discloses a working method for a thermochemical absorption energy storage combined thermal power unit system, comprising:

[0019] In the energy release mode, the supercritical carbon dioxide output from the supercritical carbon dioxide high-pressure storage tank is heated in the second heat exchanger. The heated supercritical carbon dioxide enters the third heat exchanger for further heating, and then enters the energy storage power generation turbine to do work. The exhaust gas output from the energy storage power generation turbine is cooled by the second heat exchanger and then stored in the chemical absorption carbon dioxide low-pressure storage tank. At the same time, condensate is introduced into the chemical absorption carbon dioxide low-pressure storage tank to remove the heat generated during the carbon dioxide absorption process.

[0020] In energy storage mode, the extraction steam output from the low-pressure cylinder is introduced into the low-pressure storage tank for chemically absorbed carbon dioxide to heat the carbon dioxide chemical absorbent. At the same time, carbon dioxide is released by spraying. The released carbon dioxide is separated by a gas-liquid separator. The separated carbon dioxide enters the carbon dioxide compressor and is compressed to supercritical to form supercritical carbon dioxide. The supercritical carbon dioxide is cooled by the first heat exchanger and stored in a high-pressure storage tank for supercritical carbon dioxide.

[0021] The present invention has the following beneficial effects:

[0022] In specific operation, the thermochemical absorption energy storage combined thermal power unit system and its working method described in this invention replaces the liquefied carbon dioxide storage tank with chemical absorption low-pressure storage, resulting in considerable energy density. It is more stable and has lower energy consumption than the liquefied compressed carbon dioxide energy storage system, thus reducing costs. At the same time, condensate and extracted steam are used as the cold source and heat source, respectively, for the chemical absorption carbon dioxide low-pressure storage tank during the energy release and energy storage stages, realizing comprehensive energy utilization and improving the overall operating efficiency of the energy storage system. Under the premise of ensuring the stability of the thermal power unit energy storage system, it improves the energy storage density, system service life, and response rate. Attached Figure Description

[0023] Figure 1 This is a structural diagram of the present invention.

[0024] Among them, 1 is the boiler, 2 is the high-pressure cylinder, 3 is the medium-pressure cylinder, 4 is the low-pressure cylinder, 5 is the first generator, 6 is the condenser, 7 is the condensate pump, 8 is the first heat exchanger, 9 is the carbon dioxide compressor, 10 is the supercritical carbon dioxide high-pressure storage tank, 11 is the second heat exchanger, 12 is the third heat exchanger, 13 is the energy storage and power generation turbine, 14 is the second generator, 15 is the chemical absorption carbon dioxide low-pressure storage tank, 16 is the gas-liquid separator, 17 is the back-pressure turbine, 18 is the first electric shut-off valve, and 19 is the second electric shut-off valve. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0026] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] refer to Figure 1 The thermochemical absorption energy storage combined thermal power unit system of the present invention includes a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a first generator 5, a condenser 6, a condensate pump 7, a first heat exchanger 8, a carbon dioxide compressor 9, a supercritical carbon dioxide high-pressure storage tank 10, a second heat exchanger 11, a third heat exchanger 12, an energy storage power generation turbine 13, a second generator 14, a chemical absorption carbon dioxide low-pressure storage tank 15, a gas-liquid separator 16, a back-pressure turbine 17, a first electric shut-off valve 18, and a second electric shut-off valve 19.

[0028] The feedwater pipeline is connected to the inlet of boiler 1. The main steam outlet of boiler 1 is connected to the inlet of high-pressure cylinder 2 and the inlet of back-pressure turbine 17. The outlet of high-pressure cylinder 2 is connected to the reheat side inlet of boiler 1. The reheat side outlet of boiler 1 is connected to the inlet of intermediate-pressure cylinder 3 and the primary side inlet of third heat exchanger 12. The outlet of intermediate-pressure cylinder 3 is connected to the inlet of low-pressure cylinder 4. The outlet of low-pressure cylinder 4 is connected to the primary side of first heat exchanger 8 via condenser 6 and condensate pump 7.

[0029] The outlet of the carbon dioxide compressor 9 is connected to the inlet of the supercritical carbon dioxide high-pressure storage tank 10 via the secondary side of the first heat exchanger 8. The outlet of the supercritical carbon dioxide high-pressure storage tank 10 is connected to the inlet of the energy storage power generation turbine 13 via the primary side of the second heat exchanger 11 and the secondary side of the third heat exchanger 12. The outlet of the energy storage power generation turbine 13 is connected to the inlet of the chemical absorption carbon dioxide low-pressure storage tank 15 via the secondary side of the second heat exchanger 11. The gas outlet of the chemical absorption carbon dioxide low-pressure storage tank 15 is connected to the inlet of the gas-liquid separator 16. The gas outlet of the gas-liquid separator 16 is connected to the inlet of the carbon dioxide compressor 9, and the liquid outlet of the gas-liquid separator 16 is connected to the inlet of the low-pressure carbon dioxide chemical absorption tank 15. The low-pressure carbon dioxide chemical absorption tank 15 is equipped with a spray layer, a first heat exchange tube, and a second heat exchange tube. The low-pressure carbon dioxide chemical absorption tank 15 contains a carbon dioxide chemical absorbent. The first heat exchange tube and the second heat exchange tube are located inside the carbon dioxide chemical absorbent. The circulating liquid outlet of the low-pressure carbon dioxide chemical absorption tank 15 is connected to the inlet of the spray layer.

[0030] The condensate inlet pipe is connected to the inlet of the first heat exchange tube via the first electric shut-off valve 18, and the outlet of the first heat exchange tube is connected to the condensate outlet pipe. The extraction steam inlet pipe is connected to the inlet of the second heat exchange tube via the second electric shut-off valve 19, and the outlet of the second heat exchange tube is connected to the extraction steam outlet pipe.

[0031] Specifically, the extraction steam input pipe is connected to the extraction steam port of the low-pressure cylinder 4, the condensate output pipe is connected to the low-pressure heater, the extraction steam output pipe is connected to the condenser 6, the outlet of the back-pressure steam turbine 17 is connected to the industrial steam supply pipe, and the primary side outlet of the third heat exchanger 12 is connected to the deaerator.

[0032] Boiler 1, high-pressure cylinder 2, medium-pressure cylinder 3, low-pressure cylinder 4 and first generator 5 are arranged coaxially; the output shaft of back-pressure steam turbine 17 is connected to the drive shaft of carbon dioxide compressor 9; the output shaft of energy storage power generation steam turbine 13 is connected to the drive shaft of second generator 14.

[0033] refer to Figure 1 The working method of the thermochemical absorption and energy storage combined thermal power unit system of the present invention includes an energy release mode and an energy storage mode.

[0034] In the energy release mode, the thermal power unit operates normally. The supercritical carbon dioxide output from the supercritical carbon dioxide high-pressure storage tank 10 is heated by the exhaust steam of the energy storage power generation turbine 13 in the second heat exchanger 11. The heated supercritical carbon dioxide enters the third heat exchanger 12 and is heated by part of the reheat steam output from the boiler 1. Then it enters the energy storage power generation turbine 13 to do work and drive the second generator 14 to generate electricity. The exhaust gas output from the energy storage power generation turbine 13 is cooled by the second heat exchanger 11 and then stored in the chemical absorption carbon dioxide low-pressure storage tank 15. The carbon dioxide absorption process generates heat. The first electric shut-off valve 18 is opened to introduce condensate into the chemical absorption carbon dioxide low-pressure storage tank 15 to remove the heat generated during the carbon dioxide absorption process, so as to continuously and efficiently absorb and store carbon dioxide.

[0035] In energy storage mode, the thermal power unit operates normally. The low-pressure storage tank 15 for chemically absorbed carbon dioxide requires heat to release carbon dioxide. The second electric shut-off valve 19 is opened to introduce the extraction steam output from the low-pressure cylinder 4 into the low-pressure storage tank 15 to heat the carbon dioxide chemical absorbent. Then, carbon dioxide is released by spraying. The released carbon dioxide is separated by the gas-liquid separator 16. The separated carbon dioxide enters the carbon dioxide compressor 9. The separated carbon dioxide chemical absorbent overflows into the low-pressure storage tank 15. Part of the main steam output from the boiler 1 drives the back-pressure turbine 17. The back-pressure turbine 17 drives the carbon dioxide compressor 9 to compress the carbon dioxide to supercritical to form supercritical carbon dioxide. The supercritical carbon dioxide is cooled by condensate in the first heat exchanger 8 and stored in the supercritical carbon dioxide high-pressure storage tank 10.

[0036] This invention has the following characteristics:

[0037] 1) During the energy release phase, the exhaust steam of the energy storage power generation turbine 13 is used for heating, and the reheated steam reheats the carbon dioxide, avoiding the need to collect compression heat in the equipment to heat the carbon dioxide during the energy release phase; in addition, the exhaust steam heat of the energy storage power generation turbine 13 is recovered through a heat exchanger to improve the economic efficiency of the unit.

[0038] 2) In the energy storage stage, the main steam drives the back-pressure turbine 17 to drive the carbon dioxide compressor 9 to improve the compression capacity and effectively reduce the power consumption of the energy storage system; the first heat exchanger 8 is used to collect the compression heat and use it to heat the condensate to increase the temperature of the condensate, reduce irreversible heat exchange losses, and improve the energy efficiency of the unit; the reheat steam is used to heat the high-pressure low-temperature carbon dioxide in the energy release stage of the transcritical compression carbon dioxide energy storage system to improve the work capacity of carbon dioxide and increase the energy storage power generation of the unit.

[0039] 3) By replacing the liquefied carbon dioxide storage tank with chemical absorption low-pressure storage, the energy storage density is considerable, and the system is more stable, has lower energy consumption, and reduces costs compared to the liquefied compressed carbon dioxide energy storage system. Condensate and steam extracted from the low-pressure cylinder 4 are used as the cold source and heat source of the chemical absorption carbon dioxide low-pressure storage tank 15 during the energy release and energy storage stages, respectively, so as to realize the comprehensive utilization of energy and improve the overall operating efficiency of the energy storage system.

[0040] 4) This invention achieves rational cascade utilization of energy by coupling thermal power units with a carbon dioxide thermochemical absorption energy storage system. Compared with conventional compressed carbon dioxide energy storage and liquid compressed carbon dioxide energy storage systems, this invention improves the overall operating efficiency and flexibility of thermal power unit energy storage.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A thermochemical absorption and storage combined thermal power unit system, characterized in that, It includes a carbon dioxide compressor (9), a first heat exchanger (8), a supercritical carbon dioxide high-pressure storage tank (10), a second heat exchanger (11), a third heat exchanger (12), an energy storage power generation turbine (13), a chemical absorption carbon dioxide low-pressure storage tank (15), and a gas-liquid separator (16). The outlet of the carbon dioxide compressor (9) is connected sequentially to the secondary side of the first heat exchanger (8), the supercritical carbon dioxide high-pressure storage tank (10), the primary side of the second heat exchanger (11), and the secondary side of the third heat exchanger (12) to the inlet of the energy storage power generation turbine (13). The outlet of the energy storage power generation turbine (13) is connected to the inlet of the chemically absorbed carbon dioxide low-pressure storage tank (15) via the secondary side of the second heat exchanger (11). The gas outlet of the chemically absorbed carbon dioxide low-pressure storage tank (15) is connected to the gas-liquid separator (16). The gas outlet of the gas-liquid separator (16) is connected to the inlet of the carbon dioxide compressor (9). The low-pressure storage tank (15) for chemical absorption of carbon dioxide is equipped with a spray layer, a first heat exchange tube and a second heat exchange tube. The low-pressure storage tank (15) for chemical absorption of carbon dioxide is filled with carbon dioxide chemical absorbent. The first heat exchange tube and the second heat exchange tube are located inside the carbon dioxide chemical absorbent. The circulating liquid outlet of the low-pressure storage tank (15) for chemical absorption of carbon dioxide is connected to the inlet of the spray layer. The liquid outlet of the gas-liquid separator (16) is connected to the inlet of the low-pressure storage tank (15) for chemical absorption of carbon dioxide; It also includes a condensate inlet pipe, a first electric shut-off valve (18) and a condensate outlet pipe; The condensate inlet pipe is connected to the inlet of the first heat exchange tube via the first electric shut-off valve (18), and the outlet of the first heat exchange tube is connected to the condensate outlet pipe. It also includes a steam extraction inlet pipe, a second electric shut-off valve (19), and a steam extraction outlet pipe; The extraction steam input pipeline is connected to the inlet of the second heat exchange tube via the second electric shut-off valve (19), and the outlet of the second heat exchange tube is connected to the extraction steam output pipeline. It also includes water supply pipelines, boiler (1), high-pressure cylinder (2), back-pressure steam turbine (17), medium-pressure cylinder (3), low-pressure cylinder (4), condenser (6) and condensate pump (7); The water supply pipeline is connected to the inlet of the boiler (1), the main steam outlet of the boiler (1) is connected to the inlet of the high pressure cylinder (2) and the inlet of the back pressure turbine (17), the outlet of the high pressure cylinder (2) is connected to the reheat side inlet of the boiler (1), the reheat side outlet of the boiler (1) is connected to the inlet of the intermediate pressure cylinder (3) and the primary side inlet of the third heat exchanger (12), the outlet of the intermediate pressure cylinder (3) is connected to the inlet of the low pressure cylinder (4), and the outlet of the low pressure cylinder (4) is connected to the primary side of the first heat exchanger (8) via the condenser (6) and the condensate pump (7). The extraction steam input pipe is connected to the extraction steam port of the low-pressure cylinder (4), the condensate output pipe is connected to the low-pressure heater, the extraction steam output pipe is connected to the condenser (6), the outlet of the back-pressure steam turbine (17) is connected to the industrial steam supply pipe, and the primary side outlet of the third heat exchanger (12) is connected to the deaerator.

2. The thermochemical absorption energy storage combined thermal power unit system according to claim 1, characterized in that, It also includes a first generator (5), a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), and the first generator (5) arranged coaxially.

3. The thermochemical absorption energy storage combined thermal power unit system according to claim 2, characterized in that, It also includes a second generator (14), the output shaft of which is connected to the drive shaft of the energy storage power generation turbine (13).

4. The thermochemical absorption energy storage combined thermal power unit system according to claim 1, characterized in that, The output shaft of the back-pressure steam turbine (17) is connected to the drive shaft of the carbon dioxide compressor (9).

5. A method for operating the thermochemical absorption energy storage combined thermal power unit system as described in claim 1, characterized in that, include: In the energy release mode, the supercritical carbon dioxide output from the supercritical carbon dioxide high-pressure storage tank (10) is heated in the second heat exchanger (11), and the heated supercritical carbon dioxide enters the third heat exchanger (12) for further heating, and then enters the energy storage power generation turbine (13) to do work. The exhaust gas output from the energy storage power generation turbine (13) is cooled by the second heat exchanger (11) and then stored in the chemical absorption carbon dioxide low-pressure storage tank (15). At the same time, condensate is introduced into the chemical absorption carbon dioxide low-pressure storage tank (15) to remove the heat generated during the carbon dioxide absorption process. In the energy storage mode, the extraction steam output from the low-pressure cylinder (4) is introduced into the low-pressure storage tank (15) for chemical absorption of carbon dioxide to heat the carbon dioxide chemical absorbent. At the same time, carbon dioxide is released by spraying. The released carbon dioxide is separated by the gas-liquid separator (16). The separated carbon dioxide enters the carbon dioxide compressor (9) and is compressed to supercritical to form supercritical carbon dioxide. The supercritical carbon dioxide is cooled by the first heat exchanger (8) and stored in the supercritical carbon dioxide high-pressure storage tank (10).

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