Hydroxide-based thermochemical heat storage system

Abstract

The invention discloses a thermochemical heat storage system based on hydroxides. The thermochemical heat storage system comprises a thermochemical heat storage device, a high-temperature heat storage tank, a low-temperature heat storage water tank, a deaerator, a water feeding pump, a steam supply pump and a steam supply main pipe. According to the system, the thermal chemical heat storage material based on the hydroxide is heated through green electricity and valley electricity to store heat, heat is released in the heat using peak, and steam heat released in the chemical reaction in the heat storage process is completely recovered through cascade heat storage, so that the system has the advantages of being simple, high in efficiency, large in heat storage density of the heat storage material, free of solidification risk, free of toxicity, capable of generating water through decomposition reaction and high in heat storage efficiency. And the safety is high.

Description

Technical Field

[0001] The invention belongs to the technical field of heat storage, and in particular relates to a hydroxide-based thermochemical heat storage system. Background Art

[0002] Renewable energy development has received unprecedented attention, and its biggest drawback is the intermittent and volatile nature of energy supply. As one of the main long-term energy storage technologies, heat storage technology has received more and more attention to solve the intermittent and volatile problems of new energy in a more economical way. At present, commonly used heat storage technologies include molten salt heat storage, hot water heat storage, magnesium brick heat storage, and hydride thermochemical heat storage. In molten salt heat storage, the solidification temperature of molten salt is relatively high. In order to prevent the solidification of molten salt from blocking the pipeline, a complex preheating system and anti-condensation protection system need to be designed; in hot water heat storage, the saturated steam pressure is higher when the temperature is higher, and the heat storage density is lower. At the same heat storage density, the storage tank volume is larger, resulting in high storage tank costs; in magnesium brick heat storage, the temperature changes greatly during the heat release process, the temperature is low at the end of the heat release, and the heat exchange end difference is small; in hydride thermochemical heat storage, high-temperature and high-concentration hydrogen is released during heat storage, which poses a safety risk. The heat storage density is usually low, generally below 500kJ / kg. Some technical heat storage devices have high design pressure and temperature, and the device needs to be designed as a high-temperature and high-pressure pressure vessel, which has high manufacturing and management costs. Summary of the invention

[0003] The purpose of the present invention is to provide a hydroxide-based thermochemical heat storage system in view of the deficiencies of the prior art.

[0004] The objective of the present invention is achieved through the following technical solutions: a hydroxide-based thermochemical heat storage system, comprising a thermochemical heat storage device, a high-temperature heat storage tank, a low-temperature water storage tank, a deaerator, a water supply pump, a steam supply pump and a steam supply main pipe; the water inlet of the thermochemical heat storage device is connected to the outlet of the water supply pump, and the steam outlet of the thermochemical heat storage device is connected to the steam supply main pipe; the heat release steam inlet of the thermochemical heat storage device is connected to the high-temperature steam inlet of the high-temperature heat storage tank; the heat storage steam exhaust port of the thermochemical heat storage device is connected to the high-temperature steam inlet of the high-temperature heat storage tank; the high-temperature steam inlet of the high-temperature heat storage tank is provided with a first valve and a third valve; the high-temperature steam outlet of the high-temperature heat storage tank is provided with a second valve and a fourth valve; the first valve and the second valve are used to control the opening and closing of the steam pipeline of the reaction product in the heat storage stage; the third valve and the fourth valve are used to control the opening and closing of the reaction water evaporation pipeline in the heat release stage; A bypass pipe is arranged between the water inlet and the steam outlet of the device, and a fifth valve is arranged on the bypass pipe; the fifth valve is used to control the outlet steam parameters of the thermochemical heat storage device; a reaction water replenishment pipe is arranged between the feed water pump and the low-temperature hot water storage tank; a reaction steam replenishment pipe is arranged on the steam supply main pipe, and the reaction steam replenishment pipe is connected to the heat release steam inlet; a heat exchanger system pipe is also arranged on the steam supply main pipe, the high-temperature end of the heat exchanger system pipe is connected to the steam outlet of the thermochemical heat storage device, and the low-temperature section of the heat exchanger system pipe is connected to the heat release steam inlet of the thermochemical heat storage device; a heat exchanger is arranged in the heat exchanger system pipe; the deaerator is connected to the feed water pump; the inlet of the low-temperature hot water storage tank is connected to the high-temperature steam outlet of the high-temperature heat storage tank, the outlet of the low-temperature hot water storage tank is connected to the inlet of the steam supply pump, and the outlet of the steam supply pump is connected to the high-temperature steam outlet of the high-temperature heat storage tank.

[0005] Furthermore, the thermochemical heat storage device is a container that can withstand high temperatures; the exterior of the thermochemical heat storage device is provided with a heat-insulating layer, and the interior of the thermochemical heat storage device is provided with a thermochemical heat storage material, an electric heater and a steam generator.

[0006] Furthermore, the thermochemical heat storage material is a hydroxide heat storage material.

[0007] Furthermore, the hydroxide heat storage material is Ca(OH)2, Sr(OH)2, Mg(OH)2 or Ba(OH)2.

[0008] Furthermore, the electric heater is a resistive heater for heating the thermochemical heat storage material.

[0009] Furthermore, the steam generator is a built-in heat exchange tube, and the interior of the heat exchange tube contains water and steam media.

[0010] Furthermore, the high-temperature heat storage tank has built-in high-temperature heat storage material and a tubular heat exchanger.

[0011] Furthermore, the high temperature heat storage material is an explicit heat storage material and a phase change heat storage material.

[0012] Furthermore, the heat storage medium of the low-temperature hot water storage tank is water.

[0013] The beneficial effects of the present invention are as follows: the present invention provides a hydroxide-based thermochemical heat storage system with high heat storage density, with a maximum heat storage density of more than 1000 kJ / kg, which is more than twice the heat storage density of commonly used molten salts; the thermochemical heat storage equipment has low working pressure and low equipment shell cost. At the same time, the system is simple, the heat storage material has no risk of solidification, and the decomposition reaction generates water, which is non-toxic and highly safe; the waste heat is recovered in steps during heat storage, and there is no heat loss caused by emission. At the same time, the heat storage density is large, and the surface area of ​​the same heat storage amount is smaller than that of heat storage materials such as molten salt and water, and the heat dissipation loss is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A structural diagram of a hydroxide-based thermochemical heat storage system;

[0015] In the figure, 1-thermochemical heat storage device; 2-high-temperature heat storage tank; 3-low-temperature hot water storage tank; 4-steam supply pump; 5-deaerator; 6-feedwater pump; 7-electric heater; 8-steam generator; 9-heat exchanger; 10-first valve; 11-second valve; 12-third valve; 13-fourth valve; 14-fifth valve; 15-steam supply main pipe; 16-bypass pipeline; 17-heat exchanger system pipeline; 18-reaction water feed pipeline; 19-reaction steam feed pipeline; 20-water inlet; 21-steam outlet; 22-heat release steam inlet; 23-heat storage exhaust outlet; 24-high-temperature steam inlet; 25-high-temperature steam outlet. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0017] like Figure 1As shown, the present invention provides a hydroxide-based thermochemical heat storage system, comprising a thermochemical heat storage device 1, a high-temperature heat storage tank 2, a low-temperature hot water storage tank 3, a deaerator 5, a water supply pump 6, a steam supply pump 4 and a steam supply main pipe 15. The water inlet 20 of the thermochemical heat storage device 1 is connected to the outlet of the water supply pump 6, and the steam outlet 21 of the thermochemical heat storage device 1 is connected to the steam supply main pipe 15; the heat release steam inlet 22 of the thermochemical heat storage device 1 is connected to the high-temperature steam inlet 24 of the high-temperature heat storage tank 2; and the heat storage exhaust port 23 of the thermochemical heat storage device 1 is connected to the high-temperature steam inlet 24 of the high-temperature heat storage tank 2. The high-temperature steam inlet 24 of the high-temperature heat storage tank 2 is provided with a first valve 10 and a third valve 12; the high-temperature steam outlet 25 of the high-temperature heat storage tank 2 is provided with a second valve 11 and a fourth valve 13; the first valve 10 and the second valve 11 are used to control the opening and closing of the reaction product steam pipeline in the heat storage stage; the third valve 12 and the fourth valve 13 are used to control the opening and closing of the reaction water evaporation pipeline in the heat release stage. The first valve 10 is arranged between the heat storage exhaust port 23 and the high-temperature steam inlet 24; the second valve 11 is arranged between the high-temperature steam outlet 25 and the inlet of the low-temperature water storage tank 3; the third valve 12 is arranged between the heat release steam inlet 22 and the high-temperature steam inlet 24; the fourth valve 13 is arranged between the outlet of the steam supply pump 4 and the high-temperature steam outlet 25. A bypass pipe 16 is arranged between the water inlet 20 and the steam outlet 21 of the thermochemical heat storage device 1, and a fifth valve 14 is arranged on the bypass pipe 16; the fifth valve 14 is used to control the outlet steam parameters of the thermochemical heat storage device 1. A section of reaction water replenishment pipeline 18 is provided between the water supply pump 6 and the low-temperature hot water storage tank 3, which is used to replenish the reaction water of the low-temperature hot water storage tank 3. A section of reaction steam replenishment pipeline 19 is provided on the steam supply main pipe 15, and the reaction steam replenishment pipeline 19 is connected to the heat release steam inlet 22, which is used for emergency steam replenishment of the heat release reaction of the thermochemical heat storage device 1. A heat exchanger system pipeline 17 is also provided on the steam supply main pipe 15, and the high-temperature end of the heat exchanger system pipeline 17 is connected to the steam outlet 21 of the thermochemical heat storage device 1, and the low-temperature section of the heat exchanger system pipeline 17 is connected to the heat release steam inlet 22 of the thermochemical heat storage device 1; a heat exchanger 9 is provided in the heat exchanger system pipeline 17. The deaerator 5 is connected to the water supply pump 6; the inlet of the low-temperature hot water storage tank is connected to the high-temperature steam outlet 25 of the high-temperature heat storage tank 2, the outlet of the low-temperature hot water storage tank 3 is connected to the inlet of the steam supply pump 4, and the outlet of the steam supply pump 4 is connected to the high-temperature steam outlet 25 of the high-temperature heat storage tank 2.

[0018] The thermochemical heat storage device 1 is a container that can withstand high temperatures. The thermochemical heat storage device 1 has a heat preservation layer on the outside and thermochemical heat storage materials, an electric heater 7 and a steam generator 8 on the inside.

[0019] The thermochemical heat storage material is a hydroxide heat storage material. The hydroxide heat storage material is Ca(OH)2, Sr(OH)2, Mg(OH)2 or Ba(OH)2. The thermochemical heat storage material can also be a material that can be decomposed into water and other reactants when heated in a reversible reaction.

[0020] The thermochemical heat storage material mainly utilizes the reaction between water (steam) and metal oxides to achieve heat storage and release. The chemical reaction principle is:

[0021] The electric heater 7 is a resistive heater used to heat the thermochemical heat storage material and convert electrical energy into thermochemical energy.

[0022] The steam generator 8 is a built-in heat exchange tube, the interior of which is water and steam medium; the heat exchange tube is a finned heat exchange tube, which is modularly designed and produced as an integrated whole with the thermochemical heat storage material, and its function is to reduce the heat exchange resistance between the thermochemical heat storage material and the water and steam in the finned heat exchange tube, and to enhance the heat exchange.

[0023] The high-temperature heat storage tank 2 has a built-in high-temperature heat storage material and a tubular heat exchanger. The function of the high-temperature heat storage tank 2 is to absorb the high-quality heat of the high-temperature steam discharged during the heat storage process, and the medium in the tube is steam. The high-temperature heat storage material is an explicit heat storage material and a phase change heat storage material. The explicit heat storage material can be concrete, steel or sand. The phase change heat storage material can be molten salt, paraffin, sugar alcohol or polyethylene.

[0024] The heat storage medium of the low-temperature hot water storage tank 3 is water, and steam is directly injected for mixed heat exchange. The low-temperature hot water storage tank 3 is used to directly inject steam or hot water after heat exchange in the high-temperature heat storage tank 2 into the hot water tank for mixed heat exchange with water during the heat storage process. Its function is to absorb the low-grade heat of the high-temperature steam discharged during the heat storage process.

[0025] The heat exchanger 9 can be a shell and tube type, a plate type or a microchannel heat exchanger. Its function is that in the later stage of heat release, when the temperature of the high-temperature heat storage tank 2 is not enough to evaporate the water at the outlet of the steam supply pump 4, the heat exchanger system pipeline 17 is opened to heat the reaction water at the outlet of the steam supply pump 4 through the main steam at the outlet of the thermochemical heat storage device 1.

[0026] The deaerator 5 is used to remove dissolved oxygen in the water to prevent corrosion of the steam generator and ensure safe operation.

[0027] The water feed pump 6 is used to transport water to the steam generator for heating, thereby ensuring the outlet steam pressure of the steam generator 8 .

[0028] The steam supply pump 4 transports the reaction water to the low-temperature hot water storage tank 3 and the high-temperature heat storage tank 2 for heat exchange and evaporation, thereby providing reaction water for the thermochemical heat storage device 1 .

[0029] In the embodiment, the specific working process of the present invention is as follows: during heat storage, the electric heater 7 inside the thermochemical heat storage device 1 is heated, and then the high-temperature heat storage material absorbs heat to react chemically, releasing high-temperature water vapor, which enters the low-temperature water storage tank 3 after heat exchange and heat storage in the high-temperature heat storage tank 2. During heat storage, the residual heat of the steam released is graded and completely stored. At this time, the first valve 10 and the second valve 11 are opened, and the third valve 12 and the fourth valve 13 are closed. During heat release, the hot water stored in the low-temperature water storage tank 3 is transported to the high-temperature heat storage tank 2 for heat exchange through the steam supply pump 4. After heat exchange, it becomes water vapor and enters the thermochemical heat storage device 1 to react chemically with the high-temperature heat storage material to release heat. At this time, the first valve 10 and the second valve 11 are closed, and the third valve 12 and the fourth valve 13 are opened. In the late stage of heat release, when the temperature of the high-temperature heat storage tank 2 is insufficient to evaporate the water at the outlet of the steam supply pump 4, the heat exchanger system pipeline 17 is opened, and the reaction water at the outlet of the steam supply pump 4 is heated by the main steam at the outlet of the thermochemical heat storage device 1. At the same time, water from the deaerator 5 is transported to the thermochemical heat storage device 1 through the water supply pump 6 to absorb heat and become steam for power generation and heating. The bypass pipe 16 controls the stability of the outlet steam parameters by adjusting the fifth valve 14. During the startup phase of a new device or when the reaction water is lost, the reaction water replenishment pipe 18 is used to replenish the low-temperature hot water storage tank 3 with reaction water. When the high-temperature heat storage tank 2 and the low-temperature hot water storage tank 3 fail, the steam supply main pipe 15 connected to the thermochemical heat storage device 1 is used for accident steam replenishment of the exothermic reaction of the thermochemical heat storage device 1 through the reaction steam replenishment pipe 19.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A thermochemical heat storage system based on hydroxide, characterized in that: The invention comprises a thermochemical heat storage device (1), a high-temperature heat storage tank (2), a low-temperature hot water storage tank (3), a deaerator (5), a water supply pump (6), a steam supply pump (4) and a steam supply main pipe (15); the water inlet (20) of the thermochemical heat storage device (1) is connected to the outlet of the water supply pump (6), the steam outlet (21) of the thermochemical heat storage device (1) is connected to the steam supply main pipe (15); the heat release steam inlet (22) of the thermochemical heat storage device (1) is connected to the high-temperature steam inlet (24) of the high-temperature heat storage tank (2); the heat storage steam exhaust port (23) of the thermochemical heat storage device (1) is connected to the high-temperature heat storage tank (2 ) is connected to a high-temperature steam inlet (24) of the high-temperature heat storage tank (2); the high-temperature steam inlet (24) of the high-temperature heat storage tank (2) is provided with a first valve (10) and a third valve (12); the high-temperature steam outlet (25) of the high-temperature heat storage tank (2) is provided with a second valve (11) and a fourth valve (13); the first valve (10) and the second valve (11) are used to control the opening and closing of the reaction product steam pipeline in the heat storage stage; the third valve (12) and the fourth valve (13) are used to control the opening and closing of the reaction water evaporation pipeline in the heat release stage; at the water inlet (20) and the steam outlet (21) of the thermochemical heat storage device (1), A bypass pipe (16) is arranged between the steam supply main pipe (15), and a fifth valve (14) is arranged on the bypass pipe (16); the fifth valve (14) is used to control the outlet steam parameters of the thermochemical heat storage device (1); a reaction water replenishment pipe (18) is arranged between the water supply pump (6) and the low-temperature hot water storage tank (3); a reaction steam replenishment pipe (19) is arranged on the steam supply main pipe (15), and the reaction steam replenishment pipe (19) is connected to the heat release steam inlet (22); a heat exchanger system pipe (17) is also arranged on the steam supply main pipe (15), and the heat exchanger system pipe (17) The high-temperature end of the heat exchanger system is connected to the steam outlet (21) of the thermochemical heat storage device (1), and the low-temperature section of the heat exchanger system pipeline (17) is connected to the heat release steam inlet (22) of the thermochemical heat storage device (1); a heat exchanger (9) is arranged in the heat exchanger system pipeline (17); the deaerator (5) is connected to the water supply pump (6); the inlet of the low-temperature hot water storage tank is connected to the high-temperature steam outlet (25) of the high-temperature heat storage tank (2), the outlet of the low-temperature hot water storage tank (3) is connected to the inlet of the steam supply pump (4), and the outlet of the steam supply pump (4) is connected to the high-temperature steam outlet (25) of the high-temperature heat storage tank (2).

2. A hydroxide-based thermochemical heat storage system according to claim 1, characterized in that: The thermochemical heat storage device (1) is a container that can withstand high temperatures; the exterior of the thermochemical heat storage device (1) is provided with a heat-insulating layer, and the interior of the thermochemical heat storage device (1) contains a thermochemical heat storage material, an electric heater (7) and a steam generator (8).

3. A hydroxide-based thermochemical heat storage system according to claim 2, characterized in that: The thermochemical heat storage material is a hydroxide heat storage material.

4. A hydroxide-based thermochemical heat storage system according to claim 3, characterized in that: The hydroxide heat storage material is Ca(OH)2, Sr(OH)2, Mg(OH)2 or Ba(OH)2.

5. A hydroxide-based thermochemical heat storage system according to claim 2, characterized in that: The electric heater (7) is a resistive heater used to heat the thermochemical heat storage material.

6. A hydroxide-based thermochemical heat storage system according to claim 2, characterized in that: The steam generator (8) is a built-in heat exchange tube, and the interior of the heat exchange tube contains water and steam media.

7. A hydroxide-based thermochemical heat storage system according to claim 1, characterized in that: The high-temperature heat storage tank (2) has built-in high-temperature heat storage material and a tubular heat exchanger.

8. A hydroxide-based thermochemical heat storage system according to claim 7, characterized in that: The high temperature heat storage material is a manifest heat storage material and a phase change heat storage material.

9. A hydroxide-based thermochemical heat storage system according to claim 1, characterized in that: The heat storage medium of the low-temperature hot water storage tank (3) is water.

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