Combined heat and power system and method for coupling thermochemical energy storage

Abstract

The invention discloses a combined heat and power system and method for coupling thermochemical energy storage. According to the technical scheme, the combined heat and power system coupled with thermochemical energy storage comprises a thermochemical energy storage device, a compressed air energy storage device, a waste heat boiler and a steam turbine power generation device. In a low ebb of electricity utilization, heat storage is performed on the thermochemical energy storage device by adopting electric energy, and gas exhausted by the thermochemical storage tank is further stored by adopting a compressed air energy storage device; in the power utilization peak or peak, the compressed air energy storage device is started to release energy, the thermochemical energy storage device is started to release heat to the outside, high-temperature gas exhausted through heat release reaction is supplied to the waste heat boiler, steam generated by the waste heat boiler drives the steam turbine power generation device to generate power, and exhausted steam is used for supplying heat to the outside to achieve cogeneration. Thermochemical energy storage, compressed air energy storage, the waste heat boiler and steam turbine power generation are coupled for application, and the energy utilization efficiency of the thermochemical energy storage system is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage and energy use, and in particular relates to a heat and power cogeneration system and method coupled with thermochemical energy storage. Background Art

[0002] In the new power system dominated by new energy, although the installed capacity and power generation of renewable energy such as wind and solar power have increased year by year, the problem of new energy consumption is relatively serious. At the same time, most areas in northern my country adopt a centralized heating mode, mostly using coal and oil as heating fuels. In addition, many industrial users in my country have multiple energy needs such as electricity and steam, and enterprises mostly use fossil fuels such as coal or gas to produce steam. The use of fossil fuels for heating has brought the dual pressures of increasingly serious environmental pollution and increasingly scarce energy resources.

[0003] If the energy storage system can be used to replace the heating of residential users and industrial enterprises with electricity, it can not only achieve peak load shifting of the power grid and greatly improve the level of new energy consumption, but also reduce the use of fossil fuels, which is beneficial to environmental protection and sustainable development. Thermochemical energy storage system has the advantages of high energy storage density, wide energy storage temperature range, and direct thermal energy supply. However, existing thermochemical energy storage systems often have problems such as waste of surplus energy resources and low cycle efficiency. Summary of the invention

[0004] In view of the problems that existing thermochemical energy storage systems often have, such as waste of surplus energy resources and low circulation efficiency, the present invention provides a heat and power cogeneration system and method coupled with thermochemical energy storage, which couples thermochemical energy storage, compressed air energy storage, waste heat boiler and steam turbine power generation to effectively improve the energy utilization efficiency of the thermochemical energy storage system, provide support for peak shaving and valley filling of the power grid, and alleviate the dual pressures of environmental pollution and energy shortage caused by the combustion of fossil fuels.

[0005] For this purpose, the present invention adopts the following technical solutions.

[0006] In a first aspect, the present invention provides a combined heat and power system coupled with thermochemical energy storage, comprising a thermochemical energy storage device, a compressed air energy storage device, a waste heat boiler and a steam turbine power generation device;

[0007] The thermochemical energy storage device and the compressed air energy storage device are connected end to end; the thermochemical energy storage device and the waste heat boiler are connected end to end;

[0008] In the energy storage stage, the thermochemical energy storage device provides the compressed air energy storage device with a gas source and compresses and stores it;

[0009] In the energy release stage, the compressed air energy storage device provides oxygen-supplementing gas to the thermochemical energy storage device. The air heated by the thermochemical energy storage device enters the waste heat boiler to release heat. The air at the outlet of the waste heat boiler returns to the thermochemical energy storage device to realize the recycling of oxygen and part of the waste heat in the air. The steam generated by the waste heat boiler is supplied to the outside through the steam turbine power generation device to realize cogeneration of heat and power.

[0010] During periods of low electricity consumption, energy is stored through the combination of thermochemical energy storage devices and compressed air energy storage devices, thereby enhancing the grid's ability to absorb valley electricity and new energy. During periods of peak electricity consumption, thermochemical energy storage devices, compressed air energy storage devices, waste heat boilers and steam turbine power generation devices jointly release energy, thereby achieving combined power and heat generation while improving the system's peak power generation capacity.

[0011] Furthermore, the thermochemical energy storage device includes a gas mixer, a blower and a thermochemical storage tank, wherein the gas mixer is connected to the blower and the thermochemical storage tank in sequence to provide the thermochemical storage tank with gas for heat storage or heat release;

[0012] The gas mixer is provided with an external air inlet to replenish the gas source for the thermochemical storage tank;

[0013] The thermochemical storage tank is provided with a real-time online oxygen measurement device, the thermochemical storage tank is provided with an exhaust valve, and the thermochemical energy storage material is stacked and arranged inside the thermochemical storage tank;

[0014] When storing heat, electric heating is used to cause the thermochemical energy storage material to undergo a reduction reaction, releasing oxygen. A certain amount of air is introduced into the thermochemical storage tank from an external air inlet through a gas mixer to bring out the oxygen released by the reduction reaction.

[0015] When releasing heat, the thermochemical energy storage material undergoes an oxidation reaction, absorbs oxygen in the airflow and releases heat; during the heat release startup phase, the air required for the oxidation reaction needs to be provided by an external air inlet. After the compressed air energy storage device and the waste heat boiler are started, the external air inlet is no longer needed to provide air.

[0016] Further, the compressed air energy storage device comprises a first heat exchanger, a second heat exchanger, a first water pump, a cold water tank, a hot water tank, a third heat exchanger, a second water pump, a compressor, a gas storage tank, an expander and a first generator, wherein the cold water tank, the first water pump, the second heat exchanger, the first heat exchanger, the hot water tank, the second water pump and the third heat exchanger are sequentially connected end to end to form a closed loop, and the expander is connected to the first generator;

[0017] In the energy storage stage, the gas from the outlet of the thermochemical storage tank is first cooled by the first heat exchanger and then compressed by the compressor. The compressed gas is cooled by the second heat exchanger and then enters the gas storage tank for storage. At the same time, the first water pump drives the cold water in the cold water tank to absorb heat in the second heat exchanger and the first heat exchanger in turn, and then enters the hot water tank for storage.

[0018] During the energy release stage, the gas in the gas storage tank absorbs heat through the third heat exchanger and then performs work externally through the expander, driving the first generator to generate electricity; at the same time, the second water pump drives the hot water in the hot water tank to return to the cold water tank after releasing heat in the third heat exchanger, and the gas at the outlet of the expander enters the gas mixer.

[0019] Further, the air inlet of the waste heat boiler is connected to the outlet of the thermochemical storage tank, and the air outlet of the waste heat boiler is connected to the inlet of the gas mixer;

[0020] During the energy release stage, the high-temperature gas from the outlet of the thermochemical storage tank releases heat in the waste heat boiler and then flows into the gas mixer. It is mixed with the oxygen-rich gas from the outlet of the expander in the gas mixer and then flows to the thermochemical storage tank for recycling.

[0021] Furthermore, the steam turbine power generation device comprises a steam turbine and a second generator, the steam turbine is connected to the second generator, and the steam turbine inlet is connected to the steam outlet of the waste heat boiler;

[0022] During the energy release stage, the steam at the outlet of the waste heat boiler flows through the steam turbine to perform work externally, driving the second generator to generate electricity, and the steam discharged from the steam turbine is used to provide heat to heat users.

[0023] In a second aspect, the present invention provides a heat and power cogeneration method coupled with thermochemical energy storage, using the above-mentioned heat and power cogeneration system coupled with thermochemical energy storage, which comprises:

[0024] Step 1, determine whether it is in the low electricity consumption period, if it is satisfied, go to step 2, if not, go to step 5;

[0025] Step 2, starting the thermochemical energy storage device to store heat, and simultaneously starting the compressed air energy storage device to store energy;

[0026] Step 3, determining whether the oxygen concentration in the thermochemical storage tank of the thermochemical energy storage device is greater than the maximum oxygen concentration setting value, if satisfied, executing step 4;

[0027] Step 4, increasing the air flow rate of the gas mixer from the external air inlet to the thermochemical energy storage device, while increasing the energy storage power of the compressed air energy storage device;

[0028] Step 5, determine whether it is in the peak period of electricity consumption; if it is satisfied, proceed to step 6;

[0029] Step 6, starting the thermochemical energy storage device to release heat, starting the waste heat boiler and the steam turbine power generation device to generate electricity, and starting the compressed air energy storage device to release energy;

[0030] Step 7, determining whether the oxygen concentration in the thermochemical storage tank is less than the minimum oxygen concentration setting value; if satisfied, executing step 8;

[0031] Step 8, improving the energy release power of the compressed air energy storage device and increasing the oxygen supplement gas flow from the expander to the gas mixer.

[0032] Furthermore, during the energy storage process, a maximum oxygen concentration is set in the thermochemical storage tank. When the oxygen concentration in the thermochemical storage tank is higher than the maximum oxygen concentration setting value, it is necessary to increase the air flow from the external air inlet to the gas mixer, and at the same time increase the energy storage power of the compressed air energy storage device. During the energy release process, a minimum oxygen concentration is set in the thermochemical storage tank. When the oxygen concentration in the thermochemical storage tank is lower than the minimum oxygen concentration setting value, it is necessary to increase the energy release power of the compressed air energy storage device and increase the oxygen supplement gas flow from the expander to the gas mixer.

[0033] Furthermore, the maximum oxygen concentration setting value in the thermochemical storage tank during the energy storage process is related to the material of the resistance wire and the selection of the thermochemical heat storage material; the oxygen concentration in the thermochemical storage tank needs to be maintained below a certain oxygen concentration to prevent excessive oxygen concentration from inhibiting the reduction reaction and damaging the heating wire.

[0034] Furthermore, the set value of the minimum oxygen concentration in the thermochemical storage tank during the energy release process is related to the selection of the thermochemical heat storage material; the oxygen concentration in the thermochemical storage tank needs to be maintained above a certain oxygen concentration to prevent the oxidation reaction from being inhibited by too low an oxygen concentration.

[0035] Furthermore, the expression between the energy storage power of the compressed air energy storage device and the compressed air mass flow rate is:

[0036] P ch =m ch (h2-h1) / η ch ,

[0037] Where P ch is the energy storage power of the compressed air energy storage device (i.e., the compressor compression power), kW; m ch is the compressed air mass flow rate, kg / s; h2 is the compressor outlet air enthalpy, kJ / kg; h1 is the compressor inlet air enthalpy, kJ / kg; η ch is the compressor efficiency, %;

[0038] The expression between the energy release power of the compressed air energy storage device and the mass flow rate of the expanded air is:

[0039] P disch =m disch (h3-h4)η disch ,

[0040] Where P disch is the energy release power (i.e. expansion power) of the compressed air energy storage device, kW; m disch is the mass flow rate of expanded air, kg / s; h3 is the enthalpy of the air at the expander inlet, kJ / kg; h4 is the enthalpy of the air at the expander outlet, kJ / kg; η disch is the expansion power generation efficiency, %.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) In the past, thermochemical energy storage systems often directly discharged the gas released during the heat storage stage. The gas has a high oxygen content and a certain temperature, and direct discharge causes a double waste of energy and resources. The present invention couples compressed air energy storage with the thermochemical energy storage system, compresses and stores the gas released during the heat storage stage of the thermochemical energy storage device, and resupplies it to the thermochemical energy storage device as a supplementary oxygen source during the heat release stage, thereby realizing efficient recycling of resources.

[0043] (2) The heat release stage of the thermochemical energy storage system is an oxygen absorption process, and the gas released by the system is in an oxygen-deficient state. Previous thermochemical energy storage systems often used waste heat boilers to achieve heat conversion, and often directly discharged the gas after the waste heat boiler was cooled. The gas still has a certain amount of waste heat and oxygen content, and direct discharge causes a double waste of energy and resources. The present invention supplements oxygen through a gas mixer at the outlet of the waste heat boiler, and then supplies it to a thermochemical energy storage device to utilize the oxygen content and part of the waste heat in the gas, thereby realizing the cascade utilization of energy and the recycling of resources.

[0044] (3) In the energy storage stage, the present invention compresses the gas released by the thermochemical energy storage device with a compressor and then stores it. The thermochemical energy storage is superimposed on the compressed air energy storage, which can effectively improve the level of consumption of valley electricity and new energy. In the energy release stage, the present invention uses the gas expansion in the gas storage tank to do work, which can further improve the peak capacity of the steam turbine power generation system, provide support for the peak load shifting of the power grid, and alleviate the pressure of power supply during the peak period of power consumption of the power grid. At the same time, the exhaust steam of the steam turbine is used for external heat supply, which can realize electricity substitution for industrial users. Only valley electricity is needed to meet the energy needs of electricity and heat, which alleviates the dual pressure of environmental pollution and energy shortage caused by the use of fossil fuels to produce steam for industrial enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of a heat and power cogeneration system coupled with thermochemical energy storage according to the present invention;

[0046] In the figure: 1-gas mixer; 2-blower; 3-thermochemical storage tank; 4-drain valve; 5-first heat exchanger; 6-second heat exchanger; 7-first water pump; 8-cold water tank; 9-hot water tank; 10-third heat exchanger; 11-second water pump; 12-compressor; 13-gas storage tank; 14-expander; 15-first generator; 16-waste heat boiler; 17-steam turbine; 18-second generator; 19-steam;

[0047] Figure 2 The present invention is a flow chart of the combined heat and power method coupled with thermochemical energy storage. DETAILED DESCRIPTION

[0048] The following is an explanation and description of the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0049] Example 1

[0050] A combined heat and power system coupled with thermochemical energy storage, such as Figure 1 As shown, it includes a thermochemical energy storage device, a compressed air energy storage device, a waste heat boiler device and a steam turbine power generation device.

[0051] The thermochemical energy storage device and the compressed air energy storage device are connected end to end; the thermochemical energy storage device is connected end to end with the waste heat boiler; in the energy storage stage, the thermochemical energy storage device provides the compressed air energy storage device with an air source and compresses and stores it; in the energy release stage, the compressed air energy storage device provides the thermochemical energy storage device with oxygen-supplementing gas; the air heated by the thermochemical energy storage device enters the waste heat boiler to release heat, and the air at the outlet of the waste heat boiler returns to the thermochemical energy storage device to realize the recycling of oxygen and part of the waste heat in the air. The steam generated by the waste heat boiler is supplied to the outside through the steam turbine power generation device to realize the combined heat and power generation. When electricity consumption is low, the thermochemical energy storage device and the compressed air energy storage device are combined to store energy to enhance the power grid's absorption level of valley electricity and new energy; when electricity consumption is peak, the thermochemical energy storage device, the compressed air energy storage device, the waste heat boiler and the steam turbine power generation device jointly release energy to improve the peak power generation capacity of the system and realize the combined supply of electricity and heat.

[0052] The thermochemical energy storage device comprises a gas mixer 1, a fan 2 and a thermochemical storage tank 3. The gas mixer 1 is connected to the fan 2 and the thermochemical storage tank 3 in sequence to provide the thermochemical storage tank with gas for heat storage or heat release.

[0053] The gas mixer is provided with an external air inlet 20 to supplement the gas source for the thermochemical storage tank.

[0054] A real-time online oxygen measurement device is arranged in the thermochemical storage tank 3. An exhaust valve 4 is installed on the thermochemical storage tank 3. Thermochemical energy storage materials are stacked and arranged inside the thermochemical storage tank 3, and the thermochemical energy storage materials include at least one of copper oxide, cobalt oxide, manganese oxide, barium oxide, iron oxide and multinary composite metal oxides, and the multinary composite metal oxide is a multinary composite metal oxide formed by two or more of copper oxide, cobalt oxide, manganese oxide, barium oxide and iron oxide.

[0055] When storing heat, electric heating is used to cause the thermochemical energy storage material to undergo a reduction reaction to release oxygen. A certain amount of air is introduced into the thermochemical storage tank 3 through the external air inlet 20 via the gas mixer 1 to bring out the oxygen released by the reduction reaction.

[0056] When releasing heat, the thermochemical energy storage material undergoes an oxidation reaction, absorbs oxygen in the airflow and releases heat. During the heat release startup phase, the air required for the oxidation reaction needs to be provided by the external air inlet 20. After the compressed air energy storage device and the waste heat boiler are started, the external air inlet 20 is no longer needed to provide air.

[0057] The compressed air energy storage device includes a first heat exchanger 5, a second heat exchanger 6, a first water pump 7, a cold water tank 8, a hot water tank 9, a third heat exchanger 10, a second water pump 11, a compressor 12, a gas tank 13, an expander 14 and a first generator 15. The cold water tank 8, the first water pump 7, the second heat exchanger 6, the first heat exchanger 5, the hot water tank 9, the second water pump 11 and the third heat exchanger 10 are connected end to end to form a closed loop; the expander 14 is connected to the first generator 15. In the energy storage stage, the gas from the outlet of the thermochemical storage tank 3 is first cooled by the first heat exchanger 5 and then compressed by the compressor 12. The compressed gas is cooled by the second heat exchanger 6 and then enters the gas tank 13 for storage. At the same time, the first water pump 7 drives the cold water in the cold water tank 8, which absorbs heat in the second heat exchanger 6 and the first heat exchanger 5 in turn, and then enters the hot water tank 9 for storage. In the energy release stage, the gas in the gas storage tank 13 absorbs heat through the third heat exchanger 10 and then performs work externally through the expander 14, driving the first generator 15 to generate electricity. At the same time, the second water pump 11 drives the hot water in the hot water tank 9 to return to the cold water tank 8 after releasing heat in the third heat exchanger 10. The gas at the outlet of the expander 14 enters the gas mixer 1.

[0058] The air inlet of the waste heat boiler 16 is connected to the outlet of the thermochemical storage tank 3, and the air outlet of the waste heat boiler 16 is connected to the inlet of the gas mixer 1. In the energy release stage, the high-temperature gas from the outlet of the thermochemical storage tank 3 releases heat in the waste heat boiler 16 and then flows into the gas mixer 1, and is mixed with the oxygen-rich gas from the outlet of the expander 14 in the gas mixer 1 and then flows to the thermochemical storage tank 3 to achieve recycling.

[0059] The steam turbine power generation device includes a steam turbine 17 and a second generator 18. The steam turbine 17 is connected to the second generator 18. The inlet of the steam turbine 17 is connected to the steam outlet of the waste heat boiler 16. In the energy release stage, the steam at the outlet of the waste heat boiler 16 flows through the steam turbine 17 to perform work externally, driving the second generator 18 to generate electricity. The steam 19 discharged from the steam turbine 17 is used to provide heat to heat users.

[0060] Example 2

[0061] A combined heat and power method coupled with thermochemical energy storage, such as Figure 2 As shown, the combined heat and power system described in Example 1 includes the following steps:

[0062] Step 1, determine whether it is in the low electricity consumption period, if it is satisfied, go to step 2, if not, go to step 5;

[0063] Step 2, starting the thermochemical energy storage device to store heat, and simultaneously starting the compressed air energy storage device to store energy;

[0064] Step 3, determining whether the oxygen concentration in the thermochemical storage tank is greater than the maximum oxygen concentration setting value, if satisfied, executing step 4;

[0065] Step 4, increasing the air flow from the external air inlet to the gas mixer, and at the same time increasing the energy storage power of the compressed air energy storage device;

[0066] Step 5, determine whether it is in the peak period of electricity consumption; if it is satisfied, proceed to step 6;

[0067] Step 6, starting the thermochemical energy storage device to release heat, starting the waste heat boiler and the steam turbine power generation device to generate electricity, and starting the compressed air energy storage device to release energy;

[0068] Step 7, determining whether the oxygen concentration in the thermochemical storage tank is less than the minimum oxygen concentration setting value; if satisfied, executing step 8;

[0069] Step 8, improving the energy release power of the compressed air energy storage device and increasing the oxygen supplement gas flow from the expander to the gas mixer.

[0070] Specifically, during the energy storage process, a maximum oxygen concentration is set in the thermochemical storage tank. When the oxygen concentration in the thermochemical storage tank is higher than the maximum oxygen concentration setting value, it is necessary to increase the air flow from the external air inlet to the gas mixer, and at the same time increase the energy storage power of the compressed air energy storage device. During the energy release process, a minimum oxygen concentration is set in the thermochemical storage tank. When the oxygen concentration in the thermochemical storage tank is lower than the minimum oxygen concentration setting value, it is necessary to increase the energy release power of the compressed air energy storage device and increase the oxygen supplement gas flow from the expander to the gas mixer.

[0071] The setting value of the maximum oxygen concentration in the thermochemical storage tank during the energy storage process is related to the material of the resistance wire and the selection of the thermochemical heat storage material; the oxygen concentration in the thermochemical storage tank needs to be maintained below a certain oxygen concentration to prevent excessive oxygen concentration from inhibiting the reduction reaction and damaging the heating wire.

[0072] The set value of the minimum oxygen concentration in the thermochemical storage tank during the energy release process is related to the selection of the thermochemical heat storage material; the oxygen concentration in the thermochemical storage tank needs to be maintained above a certain oxygen concentration to prevent the oxidation reaction from being inhibited by too low an oxygen concentration.

[0073] Specifically, the expression between the energy storage power of the compressed air energy storage device (i.e., the compressor compression power) and the compressed air mass flow rate is:

[0074] P ch =m ch (h2-h1) / η ch ,

[0075] Where P ch is the energy storage power of the compressed air energy storage device, kW; m ch is the compressed air mass flow rate, kg / s; h2 is the compressor outlet air enthalpy, kJ / kg; h1 is the compressor inlet air enthalpy, kJ / kg; η ch is the compressor efficiency, %.

[0076] The expression between the energy release power (i.e., expansion power) of the compressed air energy storage device and the mass flow rate of the expanded air is:

[0077] P disch =m disch (h3-h4)η disch ,

[0078] Where P disch is the energy release power of the compressed air energy storage device, kW; m disch is the mass flow rate of expanded air, kg / s; h3 is the enthalpy of the air at the expander inlet, kJ / kg; h4 is the enthalpy of the air at the expander outlet, kJ / kg; η disch is the expansion power generation efficiency, %.

[0079] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A heat and power cogeneration system coupled with thermochemical energy storage, comprising a thermochemical energy storage device, a compressed air energy storage device, a waste heat boiler and a steam turbine power generation device; The thermochemical energy storage device and the compressed air energy storage device are connected end to end; the thermochemical energy storage device and the waste heat boiler are connected end to end; In the energy storage stage, the thermochemical energy storage device provides the compressed air energy storage device with a gas source and compresses and stores it; In the energy release stage, the compressed air energy storage device provides oxygen-supplementing gas for the thermochemical energy storage device. The air heated by the thermochemical energy storage device enters the waste heat boiler to release heat. The air at the outlet of the waste heat boiler is mixed with the oxygen-rich gas and then returned to the thermochemical energy storage device to realize the recycling of oxygen and part of the waste heat in the air. The steam generated by the waste heat boiler is supplied to the outside through the steam turbine power generation device to realize cogeneration of heat and power. During periods of low electricity consumption, energy is stored jointly through thermochemical energy storage devices and compressed air energy storage devices, thereby enhancing the grid's ability to absorb valley electricity and new energy. During periods of peak electricity consumption, thermochemical energy storage devices, compressed air energy storage devices, waste heat boilers and steam turbine power generation devices jointly release energy, thereby achieving electricity-heat cogeneration while improving the system's peak power generation capacity.

2. A combined heat and power system coupled with thermochemical energy storage according to claim 1, characterized in that: The thermochemical energy storage device comprises a gas mixer (1), a fan (2) and a thermochemical storage tank (3), wherein the gas mixer (1) is connected to the fan (2) and the thermochemical storage tank (3) in sequence to provide the thermochemical storage tank with gas for heat storage or heat release; The gas mixer (1) is provided with an external air inlet (20) for replenishing the gas source for the thermochemical storage tank; The thermochemical storage tank (3) is provided with a real-time online oxygen quantity measuring device, the thermochemical storage tank (3) is provided with an exhaust valve (4), and the thermochemical energy storage material is stacked and arranged inside the thermochemical storage tank (3); During heat storage, electric heating is used to cause the thermochemical energy storage material to undergo a reduction reaction, thereby releasing oxygen. A certain amount of air is introduced into the thermochemical storage tank (3) through an external air inlet (20) via a gas mixer (1) to carry out the oxygen released by the reduction reaction. When releasing heat, the thermochemical energy storage material undergoes an oxidation reaction, absorbs oxygen in the airflow and releases heat; during the heat release startup phase, the air required for the oxidation reaction needs to be provided by an external air inlet (20), and after the compressed air energy storage device and the waste heat boiler are started, the external air inlet (20) is no longer needed to provide air.

3. A combined heat and power system coupled with thermochemical energy storage according to claim 2, characterized in that: The compressed air energy storage device comprises a first heat exchanger (5), a second heat exchanger (6), a first water pump (7), a cold water tank (8), a hot water tank (9), a third heat exchanger (10), a second water pump (11), a compressor (12), an air storage tank (13), an expander (14) and a first generator (15); the cold water tank (8), the first water pump (7), the second heat exchanger (6), the first heat exchanger (5), the hot water tank (9), the second water pump (11) and the third heat exchanger (10) are connected end to end in sequence to form a closed loop; the expander (14) is connected to the first generator (15); In the energy storage stage, the gas from the outlet of the thermochemical storage tank (3) is first cooled by the first heat exchanger (5) and then compressed by the compressor (12). The compressed gas is cooled by the second heat exchanger (6) and then enters the gas storage tank (13) for storage. At the same time, the first water pump (7) drives the cold water in the cold water tank (8) to absorb heat in the second heat exchanger (6) and the first heat exchanger (5) in turn, and then enters the hot water tank (9) for storage. During the energy release phase, the gas in the gas storage tank (13) absorbs heat through the third heat exchanger (10) and then performs work externally through the expander (14), thereby driving the first generator (15) to generate electricity; at the same time, the second water pump (11) drives the hot water in the hot water tank (9) to return to the cold water tank (8) after releasing heat in the third heat exchanger (10), and the gas at the outlet of the expander (14) enters the gas mixer (1).

4. A combined heat and power system coupled with thermochemical energy storage according to claim 2, characterized in that: The air inlet of the waste heat boiler (16) is connected to the outlet of the thermochemical storage tank (3), and the air outlet of the waste heat boiler (16) is connected to the inlet of the gas mixer (1); In the energy release stage, the high-temperature gas from the outlet of the thermochemical storage tank (3) releases heat in the waste heat boiler (16) and then flows into the gas mixer (1), where it is mixed with the oxygen-rich gas from the outlet of the expander (14) and then flows to the thermochemical storage tank (3) to achieve recycling.

5. A combined heat and power system coupled with thermochemical energy storage according to claim 2, characterized in that: The steam turbine power generation device comprises a steam turbine (17) and a second generator (18), wherein the steam turbine (17) is connected to the second generator (18), and the inlet of the steam turbine (17) is connected to the steam outlet of the waste heat boiler (16); In the energy release stage, the steam at the outlet of the waste heat boiler (16) flows through the steam turbine (17) to perform work externally, driving the second generator (18) to generate electricity, and the steam (19) discharged from the steam turbine (17) is used to provide heat to heat users.

6. A heat and power cogeneration method coupled with thermochemical energy storage, using the heat and power cogeneration system coupled with thermochemical energy storage according to any one of claims 1 to 5, characterized in that: include: Step 1, determine whether it is in the low electricity consumption period, if it is satisfied, go to step 2, if not, go to step 5; Step 2, starting the thermochemical energy storage device to store heat, and simultaneously starting the compressed air energy storage device to store energy; Step 3, determining whether the oxygen concentration in the thermochemical storage tank of the thermochemical energy storage device is greater than the maximum oxygen concentration setting value, if satisfied, executing step 4; Step 4, increasing the air flow rate of the gas mixer from the external air inlet to the thermochemical energy storage device, while increasing the energy storage power of the compressed air energy storage device; Step 5, determine whether it is in the peak period of electricity consumption; if it is satisfied, proceed to step 6; Step 6, starting the thermochemical energy storage device to release heat, starting the waste heat boiler and the steam turbine power generation device to generate electricity, and starting the compressed air energy storage device to release energy; Step 7, determining whether the oxygen concentration in the thermochemical storage tank is less than the minimum oxygen concentration setting value; if satisfied, executing step 8; Step 8, improving the energy release power of the compressed air energy storage device and increasing the oxygen supplement gas flow from the expander to the gas mixer.

7. The combined heat and power method coupled with thermochemical energy storage according to claim 6, characterized in that: During the energy storage process, the maximum oxygen concentration is set in the thermochemical storage tank. When the oxygen concentration in the thermochemical storage tank is higher than the maximum oxygen concentration setting value, it is necessary to increase the air flow from the external air inlet to the gas mixer, and at the same time increase the energy storage power of the compressed air energy storage device. During the energy release process, the minimum oxygen concentration is set in the thermochemical storage tank. When the oxygen concentration in the thermochemical storage tank is lower than the minimum oxygen concentration setting value, it is necessary to increase the energy release power of the compressed air energy storage device and increase the oxygen supplement gas flow from the expander to the gas mixer.

8. The combined heat and power method coupled with thermochemical energy storage according to claim 7, characterized in that: The maximum oxygen concentration setting value in the thermochemical storage tank during the energy storage process is related to the material of the resistance wire and the selection of the thermochemical heat storage material; the oxygen concentration in the thermochemical storage tank needs to be maintained below a certain oxygen concentration to prevent excessive oxygen concentration from inhibiting the reduction reaction and damaging the heating wire.

9. The heat and power cogeneration method coupled with thermochemical energy storage according to claim 7, characterized in that: The set value of the minimum oxygen concentration in the thermochemical storage tank during the energy release process is related to the selection of the thermochemical heat storage material; the oxygen concentration in the thermochemical storage tank needs to be maintained above a certain oxygen concentration to prevent the oxidation reaction from being inhibited by too low an oxygen concentration.

10. The combined heat and power method coupled with thermochemical energy storage according to claim 6, characterized in that: The expression between the energy storage power of the compressed air energy storage device and the compressed air mass flow rate is: P ch =m ch (h2-h1) / h ch , Where P ch is the energy storage power of the compressed air energy storage device, kW; m ch is the compressed air mass flow rate, kg / s; h2 is the compressor outlet air enthalpy, kJ / kg; h1 is the compressor inlet air enthalpy, kJ / kg; η ch is the compressor efficiency, %; The expression between the energy release power of the compressed air energy storage device and the mass flow rate of the expanded air is: P disch =m disch (h3-h4)η disch , Where P disch is the energy release power of the compressed air energy storage device, kW; m disch is the mass flow rate of expanded air, kg / s; h3 is the enthalpy of the air at the expander inlet, kJ / kg; h4 is the enthalpy of the air at the expander outlet, kJ / kg; η disch is the expansion power generation efficiency, %.

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