Calcium-based thermochemical heat storage system based on modular fixed bed

Abstract

The calcium-based thermochemical heat storage system based on the modular fixed bed comprises a thermochemical energy storage device, a gas inlet is formed in one side of the thermochemical energy storage device, and a carrier gas outlet is formed in the other side of the thermochemical energy storage device; the water vapor system is connected with the air inlet; the first heat recovery system comprises a waste heat boiler, the carrier gas outlet is connected with the gas inlet end of the waste heat boiler through a pipeline, and the steam outlet end of the waste heat boiler is connected with the water steam system; the second heat recovery system comprises a steam-water heat exchanger and a circulating water pump; two ends of the steam-water heat exchanger and the user side form a circulating pipeline through the circulating water pump; the steam outlet end of the waste heat boiler is connected with the steam inlet end of the steam-water heat exchanger. Through cooperative configuration of the thermochemical energy storage device, the waste heat boiler and the steam-water heat exchanger, water vapor is stably conveyed to the thermochemical energy storage device to react with a calcium-based material by controlling a valve and flow, and released reaction heat is transmitted to a heat storage medium or a user side through the steam-water heat exchanger; the problem of heat release power attenuation of a traditional fixed bed reactor is solved.

Description

Technical Field

[0001] This invention relates to the field of calcium-based thermochemical reaction thermal storage technology, and more specifically to a calcium-based thermochemical thermal storage system based on a modular fixed bed. Background Technology

[0002] Thermal energy storage technology is classified into three types according to different heat storage principles: sensible heat storage, latent heat storage, and thermochemical energy storage. Compared with sensible and latent heat storage systems, thermochemical energy storage systems have advantages such as high energy density, low heat loss, long-term storage, and long-distance transportation. Calcium-based thermochemical energy storage systems mainly consist of five major components: a dehydration / hydration reactor, material circulation, steam management, and heat exchange. The system is relatively complex, with the mainstream systems being dual-fluidized bed and fixed-bed schemes. The dual-fluidized bed scheme consists of a dehydration reactor, a hydration reactor, a heat exchange device, and a steam loop. Although it enhances gas-solid contact, heat loss occurs during the circulation of materials between the calcium oxide and calcium hydroxide tanks and between the two reactors, reducing system efficiency. Furthermore, the thermochemical hydration reaction requires continuous steam consumption, and the additional steam supply system leads to reduced system thermal efficiency and increased costs.

[0003] Existing thermal storage systems, such as sensible and latent heat storage, generally suffer from low energy density, large temperature fluctuations during the heat release process, severe power attenuation leading to unstable output, and low system integration resulting in the waste of a large amount of medium and low temperature waste heat. In particular, for calcium-based thermochemical thermal storage, the steam required for its heat release reaction usually depends on external supply, which seriously reduces the overall efficiency of the system. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the existing technology and provide a novel calcium-based thermochemical reaction system. By realizing the self-circulation of internal steam consumption and condensation regeneration, the system fundamentally eliminates its dependence on external steam. Furthermore, by utilizing the cascade utilization of multi-grade thermal energy and efficient integrated design, the system maximizes the recovery of waste heat. Ultimately, the system achieves high energy density, continuous, stable and controllable exothermic output, significantly improving the system's thermal efficiency and operational economy.

[0005] To achieve the above objectives, the technical solution of the present invention is to design a calcium-based thermochemical thermal storage system based on a modular fixed bed, which includes... A thermochemical energy storage device for calcium-based thermochemical reactions, with an air inlet on one side and a carrier gas outlet on the other side; A steam system, connected to the air inlet, is used to provide steam for calcium-based thermochemical reactions; The first heat recovery system includes a waste heat boiler, wherein the carrier gas outlet is connected to the inlet end of the waste heat boiler via a pipeline, and the steam outlet end of the waste heat boiler is connected to a steam system. The second heat recovery system includes a steam-water heat exchanger and a circulating water pump. The two ends of the steam-water heat exchanger are connected to the user side through pipes and the circulating water pump to form a circulation pipeline. The steam outlet of the waste heat boiler is connected to the steam inlet of the steam-water heat exchanger.

[0006] Furthermore, the first heat recovery system also includes a Y-type filter, an electric regulating valve, a waste heat boiler inlet valve, and a waste heat boiler outlet valve. The carrier gas outlet is connected to the waste heat boiler inlet end through the Y-type filter, the electric regulating valve, the waste heat boiler inlet valve, and a pipeline. The waste heat boiler outlet end is connected to the steam inlet end of the steam-water heat exchanger through the waste heat boiler outlet valve. The second heat recovery system also includes a circulating water tank and a circulating water regulating valve. The circulating water tank is installed in the circulating pipeline, and a circulating water regulating valve is installed on the pipeline near the user side.

[0007] Furthermore, it also includes an air intake system, which comprises a nitrogen heater, a nitrogen generator, a mixing chamber, a nitrogen electric regulating valve, and an intake valve. The nitrogen generator is connected to the air inlet of the mixing chamber via a nitrogen heater, a nitrogen electric regulating valve, and a pipeline. The steam outlet of the mixing chamber is connected to the air inlet via an air inlet valve and a pipeline.

[0008] Furthermore, the air intake system also includes a pipeline preheater, a circulating fan, a preheater, and a heat exchanger outlet valve. The outlet end of the steam-water heat exchanger is connected to one end of the preheater through the heat exchanger outlet valve and a pipeline. The other end of the preheater is connected to one end of the circulating fan. The other end of the circulating fan is connected to the air intake end of the mixing chamber through the pipeline preheater and a pipeline.

[0009] Furthermore, the air intake system also includes a carrier gas bypass valve and a bypass pipeline. The two ends of the circulating fan and the preheater that are opposite to each other are connected to the two ends of the bypass pipeline through pipelines, and the carrier gas bypass valve is installed on the bypass pipeline.

[0010] Furthermore, the steam system includes a steam generator, a steam generator gas production valve, a steam valve, a steam electric regulating valve, and an inlet valve. The steam generator outlet is connected to the mixing chamber via a steam generator gas production valve, a steam electric regulating valve, and a pipeline. The mixing chamber is connected to the air inlet via an air inlet valve and a pipeline. The waste heat boiler's steam outlet is connected to the steam generator via a steam valve, a steam generator's gas production valve, and a pipeline.

[0011] Furthermore, the second heat recovery system also includes a heat exchanger inlet valve and a heat exchanger regulating valve. The carrier outlet is connected to the inlet end of the steam-water heat exchanger through a Y-type filter, the heat exchanger inlet valve, the heat exchanger regulating valve, and a pipeline.

[0012] Furthermore, it also includes a water inlet system, which includes a water tank, a water supply pump, a water tank valve, a waste heat boiler inlet valve, a steam generator inlet valve, and a circulating water inlet valve. The water tank is connected to the water supply pump through the water tank valve and pipes. The water supply pump is connected to the circulation pipeline via a circulating water inlet valve and a pipe. The water supply pump is connected to the inlet of the waste heat boiler via the waste heat boiler inlet valve and pipeline. The water supply pump is connected to the steam generator via the steam generator inlet valve and pipeline.

[0013] Furthermore, the thermochemical energy storage device is equipped with a thermochemical heater; The thermochemical energy storage device is equipped with a drain valve and a blower valve at the bottom; The waste heat boiler is equipped with a waste heat boiler drain valve and a waste heat boiler blowdown valve at the bottom.

[0014] Furthermore, the thermochemical energy storage device includes a heating device, an outer frame, an inner partition, and a carrier gas outlet. The outer frame is a cuboid frame structure. An air inlet is provided on one side of the outer frame, and a carrier gas outlet is provided on the other side of the outer frame. A left cavity and a right cavity are respectively provided on both sides of the outer frame, which are connected to the air inlet and the carrier gas outlet. Several thermochemical beds are arranged longitudinally from bottom to top along the interior of the outer frame. Each thermochemical bed is provided with an inner partition. The inner partition and the thermochemical bed form a cavity that is connected to the left cavity and the right cavity on both sides, respectively. Several of the aforementioned heating devices penetrate the thermochemical bed layer sequentially from top to bottom.

[0015] The advantages and beneficial effects of this invention are as follows: (1) The calcium-based thermochemical reaction system described in this invention can achieve high-energy-density chemical heat storage and construct a continuous heat release loop. This enables the system to not only store heat for a long time and on a large scale, but also to release heat energy continuously and stably according to demand, thus achieving "decoupling" of energy supply and demand and greatly improving the availability and reliability of the system.

[0016] (2) Through the internal design of the system (such as the coordinated operation of waste heat boiler and steam-water heat exchanger), the present invention enables the effective recovery, condensation and reuse of the reaction byproduct steam in the reaction process, forming a closed-loop "steam self-circulation". This greatly reduces the consumption of working fluid and external energy input of the system, and reuses the heat that might otherwise be wasted, thereby significantly improving the thermal efficiency of the entire energy storage system.

[0017] (3) The system is highly integrated and utilizes energy in stages, maximizing the recovery of waste heat. Specifically, this invention constructs a collaborative system by organically integrating components such as a thermochemical reactor and a waste heat boiler. This system can utilize heat energy of different grades in stages: the medium and high temperature portion is used to generate steam, while the low temperature waste heat is recovered by a hot water storage tank or a steam-water heat exchanger. This highly integrated design minimizes heat emission losses, enabling the system to maintain extremely high energy utilization rates in multiple stages such as heat storage, heat release, and working fluid preparation.

[0018] (4) The thermochemical energy storage system features dynamic, precise, and efficient active control. By using nitrogen as an inert medium, it can act as a buffer to prevent the temperature in the reaction zone from becoming excessively high due to violent reactions, thus protecting the lifespan of the materials. By changing the ratio of nitrogen to water vapor and adjusting the partial pressure of water vapor, the reaction rate with calcium oxide (CaO) can be directly controlled, thereby achieving precise and linear adjustment of the exothermic power and overcoming the power decay problem caused by the movement of the reaction front in traditional fixed-bed reactors. Furthermore, the nitrogen flow rate can be used to enhance convective heat transfer, thereby dynamically optimizing the heat exchange intensity of the entire system according to demand.

[0019] (5) The thermochemical thermal storage device of the present invention consists of multiple thermochemical beds, each separated by an inner partition. The inner partition divides the large reaction bed into multiple independent small reaction chambers, effectively limiting the longitudinal short-circuiting of steam and ensuring that each bed can function as an independent unit with a controllable reaction environment. The carrier gas passes through the inlet and the left cavity and then laterally through the reaction chamber module, forcing the steam to fully and uniformly contact the reactants in the thermochemical bed. At the same time, multiple independent heating devices are evenly distributed along the longitudinal direction of the bed. These heating devices adopt a modular design, and each group of heating devices can be controlled independently. Through modular design, the actual design temperature of each bed or even different areas within the bed can be zoned and precisely heated. This avoids reaction stagnation caused by local overheating, thereby ensuring the consistency of the overall reaction kinetics. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a novel calcium-based thermochemical reaction system according to the present invention; Figure 2 This is a schematic diagram of the structure of a novel thermochemical thermal storage device.

[0021] In the diagram: Steam generator-1, Nitrogen heater-2, Nitrogen generator-3, Pipeline preheater-4, Mixing chamber-5, Thermochemical energy storage device-6, Waste heat boiler-7, Circulating fan-8, Preheater-9, Steam-water heat exchanger-10, Circulating water tank-11, Circulating water pump-12, User side-13, Water tank-14, Feed water pump-15, Water tank valve-16, Waste heat boiler inlet valve-17, Thermochemical heater-18, Steam generator inlet valve-19, Steam generator gas production valve-20, Steam valve-21, Steam electric regulating valve-22, Nitrogen electric regulating valve-2 3. Inlet valve - 24. Return valve - 25. Drain valve - 26. Sewage valve - 27. Y-type filter - 28. Electric regulating valve - 29. Waste heat boiler inlet valve - 30. Heat exchanger inlet valve - 31. Waste heat boiler drain valve - 32. Waste heat boiler sewage valve - 33. Waste heat boiler steam outlet valve - 34. Heat exchanger regulating valve - 35. Carrier gas bypass valve - 36. Heat exchanger drain valve - 37. Heat exchanger outlet valve - 38. Circulating water regulating valve - 39. Circulating water inlet valve - 40. Inlet - 41. Heating device - 42. Outer frame - 43. Inner partition - 44. Carrier gas outlet - 45. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0023] according to Figures 1-2 As shown, this invention is a calcium-based thermochemical thermal storage system based on a modular fixed bed, which includes... Thermochemical energy storage device 6 is used for calcium-based thermochemical reactions. It has an air inlet 41 on one side and a carrier gas outlet 45 on the other side. A steam system, connected to inlet 41, is used to provide steam for calcium-based thermochemical reactions; The first heat recovery system includes a waste heat boiler 7, wherein the carrier gas outlet 45 is connected to the gas inlet of the waste heat boiler 7 via a pipe, and the steam outlet of the waste heat boiler 7 is connected to a steam system; the second heat recovery system includes a steam-water heat exchanger 10 and a circulating water pump 12, wherein the two ends of the steam-water heat exchanger 10 are connected to the user side 13 via pipes and the circulating water pump 12 to form a circulation pipeline. The steam outlet of the waste heat boiler 7 is connected to the steam inlet of the steam-water heat exchanger-10.

[0024] As a preferred embodiment of the above technical solution, the first heat recovery system further includes a Y-type filter 28, an electric regulating valve 29, a waste heat boiler inlet valve 30, and a waste heat boiler outlet valve 34. The carrier gas outlet 45 is connected to the inlet end of the waste heat boiler 7 through the Y-type filter 28, the electric regulating valve 29, the waste heat boiler inlet valve 30, and a pipeline. The outlet end of the waste heat boiler 7 is connected to the inlet end of the steam-water heat exchanger 10 through the waste heat boiler outlet valve 34. The second heat recovery system also includes a circulating water tank 11 and a circulating water regulating valve 39. The circulating water tank 11 is installed in the circulating pipeline, and the circulating water regulating valve 39 is installed on the pipeline near the user side 13.

[0025] As a preferred embodiment of the above technical solution, it further includes an air intake system, which comprises a nitrogen heater 2, a nitrogen generator 3, a mixing chamber 5, a nitrogen electric regulating valve 23, and an air intake valve 24. The nitrogen generator 3 is connected to the air inlet of the mixing chamber 5 via a nitrogen heater 2, a nitrogen electric regulating valve 23, and a pipeline. The steam outlet of the mixing chamber 5 is connected to the air inlet 41 via an air inlet valve 24 and a pipeline.

[0026] As a preferred embodiment of the above technical solution, the air intake system further includes a pipeline preheater 4, a circulating fan 8, a preheater 9, and a heat exchanger outlet valve 38. The outlet end of the steam-water heat exchanger 10 is connected to one end of the preheater 9 through the heat exchanger outlet valve 38 and a pipeline. The other end of the preheater 9 is connected to one end of the circulating fan 8. The other end of the circulating fan 8 is connected to the air intake end of the mixing chamber 5 through the pipeline preheater 4 and a pipeline.

[0027] As a preferred embodiment of the above technical solution, the air intake system further includes a carrier gas bypass valve 36 and a bypass pipe. The two ends of the circulating fan 8 and the preheater 9, which are opposite to each other, are connected to the two ends of the bypass pipe through pipes. The carrier gas bypass valve 36 is installed on the bypass pipe.

[0028] As a preferred embodiment of the above technical solution, the steam system includes a steam generator 1, a steam generator gas production valve 20, a steam valve 21, a steam electric regulating valve 22, and an inlet valve 24. The steam generator 1 is connected to the mixing chamber 5 via the steam generator gas production valve 20, the steam electric regulating valve 22 and the pipeline. The mixing chamber 5 is connected to the air inlet 41 via the air inlet valve 24 and the pipeline. The steam outlet of the waste heat boiler 7 is connected to the steam generator 1 via a steam valve 21, a steam generator gas production valve 20, and a pipeline.

[0029] As a preferred embodiment of the above technical solution, the second heat recovery system further includes a heat exchanger inlet valve 31 and a heat exchanger regulating valve 35. The carrier outlet 45 is connected to the inlet end of the steam-water heat exchanger 10 through a Y-type filter 28, the heat exchanger inlet valve 31, the heat exchanger regulating valve 35 and a pipeline.

[0030] As a preferred embodiment of the above technical solution, it also includes a water inlet system, which includes a water tank 14, a water supply pump 15, a water tank valve 16, a waste heat boiler water inlet valve 17, a steam generator water inlet valve 19, and a circulating water inlet valve 40. The water tank 14 is connected to the water supply pump 15 through the water tank valve 16 and pipes. The water supply pump 15 is connected to the circulation pipeline via the circulating water inlet valve 40 and the pipeline. The water supply pump 15 is connected to the water inlet of the waste heat boiler 7 via the waste heat boiler inlet valve 17 and a pipeline. The water supply pump 15 is connected to the steam generator 1 through the steam generator inlet valve 19 and pipeline.

[0031] As a preferred embodiment of the above technical solution, the thermochemical energy storage device 6 is equipped with a thermochemical heater 18; The thermochemical energy storage device 6 is equipped with a drain valve 26 and a drain valve 27 at its bottom. The bottom of the waste heat boiler 7 is equipped with a waste heat boiler drain valve 32 and a waste heat boiler blowdown valve 33.

[0032] As a preferred embodiment of the above technical solution, the thermochemical energy storage device includes a heating device 42, an outer frame 43, an inner partition 44, and a carrier gas outlet 45. The outer frame 43 is a cuboid frame structure. An air inlet 41 is provided on one side of the outer frame 43, and a carrier gas outlet 45 is provided on the other side of the outer frame 43. A left cavity and a right cavity are respectively provided on both sides of the outer frame, which are connected to the air inlet 41 and the carrier gas outlet 45. Several thermochemical beds are arranged sequentially from bottom to top along the inner longitudinal direction of the outer frame 43. Each thermochemical bed is provided with an inner partition. The inner partition and the thermochemical bed form a cavity that is connected to the left cavity and the right cavity on both sides, respectively. Several of the heating devices 42 are arranged sequentially from top to bottom through the thermochemical bed.

[0033] The implementation steps of a calcium-based thermochemical thermal storage system based on a modular fixed bed are as follows: 1) Before the start of heat storage, the water in the water tank 14 is sent through the water tank valve 16 and the water supply pump 15 into the circulation pipeline consisting of the steam-water heat exchanger 10, the circulating water pump 12, etc., and the water is circulated in the pipeline by the circulating water pump 12. 2) During heat storage, the inlet valve 24 and the electric regulating valve 29 are closed, while the heat exchanger inlet valve 31 and the heat exchanger regulating valve 35 are opened. The thermochemical heater 18 is started, and the temperature at different locations of the thermochemical bed is monitored by the internal thermocouples. Modular heating is performed according to different temperatures to ensure the uniformity of the internal temperature of the system. The high-temperature steam generated during the heat storage process is filtered through the Y-type filter 28 at the carrier gas outlet 45, and then enters the steam-water heat exchanger 10 through the heat exchanger inlet valve 31 and the heat exchanger regulating valve 35. The heat is then transferred to the user side 13 through the steam-water heat exchanger 10. 3) Before the exothermic reaction begins, open the pipeline valves, and nitrogen generator 3 blows nitrogen into the pipeline. At the same time, pipeline preheater 4 starts to preheat the pipeline. After the pipeline is filled with nitrogen and the temperature reaches the set value, shut off pipeline preheater 4 and start steam generator 1 to deliver a mixture of water vapor and nitrogen into the pipeline as the heat exchange carrier gas for the thermochemical energy storage system. The partial pressure of the carrier gas is jointly controlled by steam electric regulating valve 22 and nitrogen electric regulating valve 23, and the heat exchange flow rate of the carrier gas is controlled by circulating fan 8. After the nitrogen concentration in the pipeline reaches the set value, shut off nitrogen generator 3 and steam generator 1, and start circulating fan 8 to start the exothermic reaction. 4) During the exothermic reaction, the heat exchanger inlet valve 31 and the heat exchanger regulating valve 35 are closed. The mixed carrier gas composed of nitrogen and water vapor enters the thermochemical device 6 through the inlet 41. The carrier gas enters the thermochemical bed and exchanges heat with the internal reactor. After heat exchange, the high-temperature carrier gas is carried out through the carrier gas outlet 45 and enters the waste heat boiler 7 through the electric regulating valve 29 and the waste heat boiler inlet valve 30. Steam is generated and re-enters the reactor through the steam valve 21 to supplement the thermochemical reaction with water vapor. The remaining heat enters the steam-water heat exchanger 10 and is transferred to the user side 13 through the steam-water heat exchanger. The remaining carrier gas re-enters the thermochemical energy storage device 6 through the circulating fan 8 to absorb heat and carry out the cyclic reaction.

[0034] This invention, through the coordinated configuration of thermochemical energy storage device 6, waste heat boiler 7, and steam-water heat exchanger 10, ensures stable delivery of steam to the thermochemical energy storage device 6 to react with calcium-based materials during the heat storage and release phase by controlling valves and flow rates. At the same time, the released reaction heat is transferred to the heat storage medium or the user side through the steam-water heat exchanger 10, overcoming the problem of heat release power decay in traditional fixed-bed reactors and achieving continuous and controllable heat release that matches user needs.

[0035] Furthermore, this invention enables a system architecture and energy flow design for steam "self-circulation." Through system design, the spontaneous consumption, recovery, and reuse of water vapor during thermochemical reactions are achieved, forming a closed loop that requires no external replenishment, thus greatly improving the system's thermal efficiency.

[0036] This invention utilizes a system design that combines multi-grade thermal energy utilization with efficient thermal management. It uses the highest grade of externally input thermal energy to drive thermochemical reactions; prioritizes the use of the thermal energy from the medium-temperature steam / gas generated by the reaction for power generation or process steam; and uses low-temperature waste heat and reaction condensation heat to preheat feedwater or provide low-temperature heat to hot water storage tanks / users.

[0037] This invention provides a dynamic, precise, and efficient active control method for thermochemical energy storage systems. By monitoring the temperature, pressure, or outlet hot fluid temperature of the thermochemical energy storage device, the injection flow rate and ratio of nitrogen and water vapor are dynamically adjusted to achieve coordinated optimization control of the system's heat release power and heat exchange efficiency.

[0038] This invention is a multi-layer thermochemical thermal storage device that integrates a steam uniform distribution system and a modular zoned temperature control system. Its core innovation lies in the synergistic design and integrated integration of a "multi-layer internal partition distribution system" and a "vertical modular zoned heating system". By precisely controlling the spatial distribution of the reaction medium (steam) and the zoned supply of heat, it achieves rapid, uniform and efficient energy conversion in the entire thermochemical bed during the dehydration (thermal storage) and hydration (exothermic) reaction processes, solving the problems of uneven reactant conversion rate and slow reaction kinetics in traditional thermal storage devices.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A calcium-based thermochemical thermal storage system based on a modular fixed bed, characterized in that, It includes Thermochemical energy storage device (6) is used for calcium-based thermochemical reactions. It has an air inlet (41) on one side and a carrier gas outlet (45) on the other side. A steam system, connected to the air inlet (41), is used to provide steam for calcium-based thermochemical reactions; The first heat recovery system includes a waste heat boiler (7), the carrier gas outlet (45) is connected to the gas inlet of the waste heat boiler (7) through a pipeline, and the steam outlet of the waste heat boiler (7) is connected to a steam system. The second heat recovery system includes a steam-water heat exchanger (10) and a circulating water pump (12). The two ends of the steam-water heat exchanger (10) are connected to the user side (13) through pipes and the circulating water pump (12) to form a circulation pipeline. The steam outlet of the waste heat boiler (7) is connected to the steam inlet of the steam-water heat exchanger (10).

2. The calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 1, characterized in that, The first heat recovery system also includes a Y-type filter (28), an electric regulating valve (29), a waste heat boiler inlet valve (30), and a waste heat boiler outlet valve (34). The carrier gas outlet (45) is connected to the inlet end of the waste heat boiler (7) through the Y-type filter (28), the electric regulating valve (29), the waste heat boiler inlet valve (30), and the pipeline. The outlet end of the waste heat boiler (7) is connected to the inlet end of the steam-water heat exchanger (10) through the waste heat boiler outlet valve (34). The second heat recovery system also includes a circulating water tank (11) and a circulating water regulating valve (39). The circulating water tank (11) is installed in the circulating pipeline, and the circulating water regulating valve (39) is installed on the pipeline near the user side (13).

3. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 2, characterized in that, It also includes an air intake system, which includes a nitrogen heater (2), a nitrogen generator (3), a mixing chamber (5), a nitrogen electric regulating valve (23), and an air intake valve (24). The nitrogen generator (3) is connected to the air inlet of the mixing chamber (5) via a nitrogen heater (2), a nitrogen electric regulating valve (23) and a pipeline. The steam outlet of the mixing chamber (5) is connected to the air inlet (41) via an air inlet valve (24) and a pipeline.

4. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 3, characterized in that, The air intake system also includes a pipeline preheater (4), a circulating fan (8), a preheater (9), and a heat exchanger outlet valve (38). The outlet end of the steam-water heat exchanger (10) is connected to one end of the preheater (9) through the heat exchanger outlet valve (38) and a pipeline. The other end of the preheater (9) is connected to one end of the circulating fan (8). The other end of the circulating fan (8) is connected to the air intake end of the mixing chamber (5) through the pipeline preheater (4) and a pipeline.

5. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 4, characterized in that, The air intake system also includes a carrier gas bypass valve (36) and a bypass pipe. The two ends of the circulating fan (8) and the preheater (9) are connected to the two ends of the bypass pipe respectively through pipes. The carrier gas bypass valve (36) is installed on the bypass pipe.

6. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 3, characterized in that, The steam system includes a steam generator (1), a steam generator gas production valve (20), a steam valve (21), a steam electric regulating valve (22), and an air inlet valve (24). The steam generator (1) is connected to the mixing chamber (5) through the steam generator gas production valve (20), the steam electric regulating valve (22) and the pipeline. The mixing chamber (5) is connected to the air inlet (41) through the air inlet valve (24) and the pipeline. The steam outlet of the waste heat boiler 7 is connected to the steam generator (1) via a steam valve (21), a steam generator gas production valve (20), and a pipeline.

7. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 2, characterized in that, The second heat recovery system also includes a heat exchanger inlet valve (31) and a heat exchanger regulating valve (35). The carrier outlet (45) is connected to the inlet end of the steam-water heat exchanger (10) through a Y-type filter (28), the heat exchanger inlet valve (31), the heat exchanger regulating valve (35) and a pipeline.

8. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 1, characterized in that, It also includes a water inlet system, which includes a water tank (14), a water supply pump (15), a water tank valve (16), a waste heat boiler inlet valve (17), a steam generator inlet valve (19), and a circulating water inlet valve (40). The water tank (14) is connected to the water supply pump (15) through the water tank valve (16) and pipes. The water supply pump (15) is connected to the circulation pipeline through the circulating water inlet valve (40) and the pipeline; The water supply pump (15) is connected to the water inlet of the waste heat boiler 7 through the waste heat boiler inlet valve (17) and pipeline; The water supply pump (15) is connected to the steam generator 1 through the steam generator inlet valve (19) and pipeline.

9. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 1, characterized in that, A thermochemical heater (18) is installed on the thermochemical energy storage device (6); The thermochemical energy storage device (6) is equipped with a drain valve (26) and a drain valve (27) at the bottom. The waste heat boiler (7) is equipped with a waste heat boiler drain valve (32) and a waste heat boiler blowdown valve (33) at the bottom.

10. A calcium-based thermochemical thermal storage system based on a modular fixed bed according to claim 1, characterized in that, The thermochemical energy storage device (6) includes a heating device (42), an outer frame (43), an inner partition (44), and a carrier gas outlet (45). The outer frame (43) is a cuboid frame structure. An air inlet (41) is provided on one side of the outer frame (43), and a carrier gas outlet (45) is provided on the other side of the outer frame (43). A left cavity and a right cavity are respectively provided on both sides of the outer frame, which are connected to the air inlet (41) and the carrier gas outlet (45). Several thermochemical beds are arranged longitudinally from bottom to top along the interior of the outer frame (43). Each thermochemical bed is provided with an inner partition. The inner partition and the thermochemical bed form a cavity that is connected to the left cavity and the right cavity on both sides, respectively. Several of the heating devices (42) penetrate the thermochemical bed layer from top to bottom.

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