Heat storage system for gradient utilization of high-temperature waste heat and operation method

Abstract

The invention relates to the technical field of high-temperature energy storage, and discloses a heat storage system for high-temperature waste heat gradient utilization and an operation method.The heat storage system comprises three gradient heat storage units and a gradient heat supply adjusting unit, each stage of heat storage unit comprises a heat storage body and a heat exchanger matched with the heat storage body, and the first gradient heat storage unit is configured to preheat feed water; the second step heat storage unit is configured to convert the preheated water into saturated steam; the third cascade heat storage unit is configured to convert saturated steam into superheated steam; the stepped heat supply adjusting unit is connected with the three heat storage units and is configured to control a heat medium flowing path; wherein each heat storage unit adopts a heat storage medium and a heat exchange medium which are different in composition, and the second cascade heat storage unit and the third cascade heat storage unit are each provided with a solid particle injection and recovery system so that heat exchange can be enhanced through particle collision during high-load operation. The comprehensive utilization rate of high-temperature waste heat is remarkably increased through the step design and the enhanced heat exchange means.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature energy storage, and in particular to a heat storage system and an operating method for cascaded utilization of high-temperature waste heat. Background Art

[0002] As global installed capacity of fluctuating renewable energy sources like photovoltaics and wind power increases, the challenge of accommodating renewable energy is becoming increasingly severe. Developing energy storage is a key measure to enhance the regulation capabilities of power systems and support the construction of new power systems. High-temperature solid thermal storage technology, as a key energy storage method, holds significant value in promoting renewable energy consumption and alleviating grid regulation pressure.

[0003] High-temperature solid thermal storage boasts a simple principle, abundant and inexpensive materials, and is easily scaled up for larger thermal storage capacities, facilitating large-scale deployment. Currently, magnesia bricks are the mainstream thermal storage material used in solid thermal storage electric boilers for building heating applications. Numerous thermal storage electric boiler projects have been implemented in northern China, making them a mature energy storage technology.

[0004] However, the current magnesia brick heat storage technology faces two problems. First, traditional magnesia bricks and other heat storage materials are easily damaged when repeatedly storing and releasing heat at high temperatures of around 1000°C, which limits the increase in heat storage temperature and leads to a relatively small heat storage capacity per unit mass of the material. Second, the heat in the heat storage body cannot be released quickly due to the limitations of the thermal conductivity of the magnesia brick material itself and the efficiency of air convection heat exchange between the heat storage body and the heated surface. Summary of the Invention

[0005] In view of this, the present invention provides a heat storage system and an operation method for cascade utilization of high-temperature waste heat to solve the above-mentioned problems faced by the current magnesia brick heat storage technology.

[0006] In a first aspect, the present invention provides a heat storage system for cascade utilization of high-temperature waste heat, comprising:

[0007] A first cascade heat storage unit includes a first heat storage body and a first heat exchanger matched with the first heat storage body, wherein the first cascade heat storage unit is configured to preheat feed water through the first heat storage body;

[0008] a second cascade heat storage unit, comprising a second heat storage body and a second heat exchanger matched with the second heat storage body, wherein the second cascade heat storage unit is configured to convert the preheated water into saturated steam via the second heat storage body;

[0009] a third-stage heat storage unit, comprising a third heat storage body and a third heat exchanger associated with the third heat storage body, wherein the third-stage heat storage unit is configured to convert saturated steam into superheated steam via the third heat storage body;

[0010] a cascade heat supply regulating unit connected to the three heat storage units and configured to control a heat medium flow path;

[0011] Among them, each heat storage unit uses heat storage medium and heat exchange medium with different compositions. The second-stage heat storage unit and the third-stage heat storage unit are respectively equipped with solid particle injection and recovery systems to enhance heat exchange through particle collision during high-load operation.

[0012] The system utilizes three cascaded thermal storage units with different compositions of thermal storage and heat exchange media to achieve graded recovery and utilization of high-temperature waste heat, matching heat demand at different stages and improving the efficiency and flexibility of waste heat utilization. The first cascade thermal storage unit performs initial preheating of the feed water, reducing the energy consumption required for subsequent heating. The second cascade thermal storage unit converts the preheated water into saturated steam, meeting the demand for saturated steam in industrial production. During high load conditions, the injection of solid particles enhances heat exchange through collision, preventing a decrease in heat exchange efficiency due to increased heat load. The third cascade thermal storage unit converts saturated steam into superheated steam, providing a heat source with higher energy quality and expanding the system's application scenarios. The cascaded heat supply regulation unit controls the flow path of the heat medium, enabling the system to dynamically adjust its operating mode according to actual load, ensuring efficient and stable operation under different operating conditions. The solid particle injection and recovery system recovers particles during low-load periods, preventing continuous wear on the heat exchanger and extending equipment life. Through the cascade design and enhanced heat exchange, the overall system significantly improves the comprehensive utilization rate of high-temperature waste heat, reducing energy consumption and carbon emissions.

[0013] In an optional embodiment, the first-stage heat storage unit is equipped with a superheated steam injection interface and a superheated steam valve to switch to a steam-air mixed medium to enhance heat exchange under high load.

[0014] In an optional embodiment, the second-stage thermal storage unit includes:

[0015] a carbon dioxide circulation loop connected to the interior of the second thermal storage body;

[0016] a calcium carbonate powder injection device, connected to the carbon dioxide circulation loop; the calcium carbonate powder injection device is configured to inject calcium carbonate powder into the interior of the second thermal storage body through the carbon dioxide circulation loop;

[0017] A gas-solid separator and a powder recovery bin are connected to the carbon dioxide circulation loop; the gas-solid separator and the powder recovery bin are configured to separate and recover calcium carbonate powder in the carbon dioxide circulation loop;

[0018] Among them, the calcium carbonate powder injection device, the gas-solid separator and the powder recovery bin constitute the solid particle injection and recovery system.

[0019] In an optional embodiment, the third-stage heat storage unit includes:

[0020] a nitrogen circulation loop connected to the interior of the third heat storage body;

[0021] a quartz sand powder injection device, connected to the nitrogen circulation loop;

[0022] A gas-solid separator and a powder recovery bin are connected to the nitrogen circulation loop; the gas-solid separator and the powder recovery bin are configured to separate and recover the quartz sand powder in the nitrogen circulation loop;

[0023] Among them, the quartz sand powder injection device, gas-solid separator and powder recovery bin constitute the solid particle injection and recovery system.

[0024] In an optional embodiment, the circulation loop comprises:

[0025] A gas purification branch and a particle circulation branch are arranged in parallel, wherein the particle circulation branch is connected to the interior of the heat storage body, and the gas purification branch is connected to the gas-solid separator; the gas purification branch and the particle circulation branch are controlled by a valve;

[0026] An air blower is connected to the particle circulation branch.

[0027] In an optional embodiment, the gas inside the gas purification branch is configured to enter the interior of the heat storage body after gas-solid separation by the gas-solid separator.

[0028] In an optional embodiment, the powder recovery bin is located at the lower side of the gas-solid separator, and the powder recovery bin is connected to the lower outlet of the gas-solid separator.

[0029] In an optional embodiment, the powder injection device is communicated with the powder recovery bin, and the powder injection device is configured to inject the powder in the powder recovery bin into the particle circulation branch again.

[0030] In an optional embodiment, each heat storage body includes a shell, a plurality of high-magnesium electric heat storage columns vertically installed inside the shell, and a thermal resistor installed inside the electric heat storage columns;

[0031] Among them, the heat storage material of the first heat storage body is high magnesium brick with magnesium oxide content ≥90%, the heat storage material of the second heat storage body is magnesium carbon brick with carbon content ≥15%, and the heat storage material of the third heat storage body is magnesium carbon brick with carbon content ≥25%.

[0032] In an optional embodiment, the outer shell of the first heat storage body is provided with a drain pipe connected to the interior of the first heat storage body, and the drain pipe is provided with a drain valve.

[0033] In an optional embodiment, the cascade heating regulation unit includes:

[0034] a pipeline, wherein the pipeline is configured to sequentially connect the first heat exchanger, the second heat exchanger, and the third heat exchanger in series;

[0035] a saturated steam inlet regulating valve connected to the pipeline between the first heat exchanger and the second heat exchanger;

[0036] a superheated steam inlet regulating valve connected to the pipeline between the second heat exchanger and the third heat exchanger;

[0037] a back pressure valve connected to the outlet end of the pipeline;

[0038] a buffer tank and a water feed pump, and the inlet end of the pipeline;

[0039] Wherein, the cascade heating regulation unit is configured to realize the separate or combined output of hot water, saturated steam and superheated steam through a valve combination.

[0040] In an optional embodiment, the cascade heating regulation unit further includes:

[0041] a hot water outlet regulating valve connected between the first heat exchanger (12) and the saturated steam inlet regulating valve (41);

[0042] A saturated steam regulating valve is connected between the second heat exchanger (22) and the superheated steam inlet regulating valve (42).

[0043] In an optional embodiment, the step heat supply regulating unit further comprises an air valve, and the air valve is connected to the first heat exchanger (12).

[0044] In a second aspect, the present invention further provides a method for operating a heat storage system based on cascade utilization of high-temperature waste heat, comprising:

[0045] Heat storage stage: Each heat storage unit is filled with a specified gas medium and pressurized, and the heat storage body is heated electrically to reach the set temperature gradient;

[0046] Low load operation mode: using single-phase gas medium circulation heat exchange;

[0047] High-load operation mode: solid particles are injected into the second-stage thermal storage unit and the third-stage thermal storage unit, and the heat exchange efficiency is improved by pressure or medium switching;

[0048] Shutdown protection stage: cool down each thermal storage unit in stages from high temperature to low temperature and recover solid particles, and keep steam flushing of heat exchange pipelines until the temperature is below the safety threshold.

[0049] In an optional implementation, the high-load operation mode includes:

[0050] Inject superheated steam into the first-stage thermal storage unit and make the operating pressure ≥15kPa;

[0051] Injecting calcium carbonate powder into the circulating medium of the second-stage thermal storage unit to enhance heat transfer through its decomposition-regeneration reaction;

[0052] Quartz sand powder is injected into the circulating medium of the third-stage heat storage unit to enhance heat transfer through the collision of solid particles with the heat exchange surface.

[0053] In an optional implementation, the shutdown protection stage includes:

[0054] The third-stage thermal storage unit is preferentially cooled to below 800°C, and the quartz sand is recovered through the solid particle injection and recovery system;

[0055] The second-stage thermal storage unit is cooled to below 600°C and calcium carbonate is recovered simultaneously;

[0056] Perform steam replacement on the first-stage heat storage unit and maintain the pipeline pressure >1000Pa until the air completely replaces the steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 Schematic diagram of a heat storage system for cascaded utilization of high-temperature waste heat according to an embodiment of the present invention.

[0059] Description of reference numerals:

[0060] 1. First cascade heat storage unit; 11. First heat storage body; 12. First heat exchanger; 13. Superheated steam injection port; 14. Superheated steam valve; 15. First air blower;

[0061] 2. Second cascade heat storage unit; 21. Second heat storage body; 22. Second heat exchanger; 23. Calcium carbonate powder injection device; 24. First gas-solid separator; 25. First powder recovery bin; 26. First gas purification branch; 27. First particle circulation branch; 28. Second air blower;

[0062] 3. Third-stage heat storage unit; 31. Third heat storage body; 32. Third heat exchanger; 33. Quartz sand powder injection device; 34. Second gas-solid separator; 35. Second powder recovery bin; 36. Second gas purification branch; 37. Second particle circulation branch; 38. Third air blower;

[0063] 41. Saturated steam inlet regulating valve; 42. Superheated steam inlet regulating valve; 43. Back pressure valve; 44. Buffer tank; 45. Feed water pump; 46. Hot water outlet regulating valve; 47. Saturated steam regulating valve;

[0064] 51. Air valve; 52. Exhaust valve;

[0065] 61. Carbon dioxide gas storage device; 62. Nitrogen gas storage device. DETAILED DESCRIPTION

[0066] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0067] As global installed capacity of fluctuating renewable energy sources like photovoltaics and wind power increases, the challenge of accommodating renewable energy is becoming increasingly severe. Developing energy storage is a key measure to enhance the regulation capabilities of power systems and support the construction of new power systems. High-temperature solid thermal storage technology, as a key energy storage method, holds significant value in promoting renewable energy consumption and alleviating grid regulation pressure.

[0068] High-temperature solid thermal storage boasts a simple principle, abundant and inexpensive materials, and is easily scaled up for larger thermal storage capacities, facilitating large-scale deployment. Currently, magnesia bricks are the mainstream thermal storage material used in solid thermal storage electric boilers for building heating applications. Numerous thermal storage electric boiler projects have been implemented in northern China, making them a mature energy storage technology.

[0069] However, the current magnesia brick heat storage technology faces two problems. First, traditional magnesia bricks and other heat storage materials are easily damaged when repeatedly storing and releasing heat at high temperatures of around 1000°C, which limits the increase in heat storage temperature and leads to a relatively small heat storage capacity per unit mass of the material. Second, the heat in the heat storage body cannot be released quickly due to the limitations of the thermal conductivity of the magnesia brick material itself and the efficiency of air convection heat exchange between the heat storage body and the heated surface.

[0070] In view of this, the present embodiment provides a heat storage system and an operating method for cascade utilization of high-temperature waste heat to solve the above-mentioned problems faced by the current magnesia brick heat storage technology.

[0071] The following combination Figure 1 , describing embodiments of the present invention.

[0072] According to an embodiment of the present invention, on the one hand, a heat storage system for cascade utilization of high-temperature waste heat is provided, comprising a first cascade heat storage unit 1, a second cascade heat storage unit 2, a third cascade heat storage unit 3 and a cascade heat supply adjustment unit, wherein the first cascade heat storage unit 1 comprises a first heat storage body 11 and a first heat exchanger 12 matched with the first heat storage body 11, and the first cascade heat storage unit 1 is configured to preheat the feed water through the first heat storage body 11; the second cascade heat storage unit 2 comprises a second heat storage body 21 and a second heat exchanger 22 matched with the second heat storage body 21, and the second cascade heat storage unit 2 is configured to preheat the feed water through the second heat storage body The body 21 converts the preheated water into saturated steam; the third cascade heat storage unit 3 includes a third heat storage body 31 and a third heat exchanger 32 matched with the third heat storage body 31, and the third cascade heat storage unit 3 is configured to convert the saturated steam into superheated steam through the third heat storage body 31; the cascade heat supply adjustment unit connects the three heat storage units and is configured to control the flow path of the heat medium; wherein, each heat storage unit adopts a heat storage medium and a heat exchange medium of different composition, and the second cascade heat storage unit 2 and the third cascade heat storage unit 3 are respectively equipped with a solid particle injection and recovery system to enhance heat exchange through particle collision during high-load operation.

[0073] The working mode of the heat storage system for cascade utilization of high-temperature waste heat is as follows: the cascade heat supply adjustment unit controls the flow path of the heat medium in the three cascade heat storage units according to different load requirements. The low-temperature heat medium first enters the first-stage heat storage unit 1, exchanges heat with the first heat storage body 11 through the first heat exchanger 12, and uses the heat stored in the first heat storage body 11 to preheat the feed water, raising the feed water temperature to near the saturation temperature; the preheated water enters the second-stage heat storage unit 2, contacts the second heat storage body 21 through the second heat exchanger 22, and the second heat storage body 21 releases heat to convert the preheated water into saturated steam. In this process, when operating at high load, the solid particle injection and recovery system injects solid particles into the second-stage heat storage unit 2, and the particles enhance the heat exchange efficiency by colliding with the heat exchanger surface; the saturated steam then enters the third-stage heat storage unit 3, exchanges heat with the third heat storage body 31 through the third heat exchanger 32, and the third heat storage body 31 releases higher-grade heat to heat the saturated steam into superheated steam. Similarly, when operating at high load, the solid particle injection and recovery system of the third-stage heat storage unit 3 further enhances heat exchange through particle collision.

[0074] The system utilizes three cascaded thermal storage units with different compositions of thermal storage and heat exchange media to achieve graded recovery and utilization of high-temperature waste heat, matching heat demand at different stages and improving the efficiency and flexibility of waste heat utilization. The first-stage thermal storage unit 1 performs initial preheating of the feed water, reducing the energy consumption required for subsequent heating. The second-stage thermal storage unit 2 converts the preheated water into saturated steam, meeting the demand for saturated steam in industrial production. During high load conditions, the injection of solid particles enhances heat exchange through collision, preventing a decrease in heat exchange efficiency due to increased heat load. The third-stage thermal storage unit 3 converts saturated steam into superheated steam, providing a heat source with higher energy quality and expanding the system's application scenarios. The cascaded heat supply regulation unit controls the flow path of the heat medium, enabling the system to dynamically adjust its operating mode according to actual load, ensuring efficient and stable operation under different operating conditions. Furthermore, the solid particle injection and recovery system recovers particles during non-high-load periods, preventing continuous wear on the heat exchanger and extending equipment life. Through the cascade design and enhanced heat exchange, the overall system significantly improves the comprehensive utilization rate of high-temperature waste heat and reduces energy consumption and carbon emissions.

[0075] In one embodiment, the first-stage heat storage unit 1 is equipped with a superheated steam injection port 13 and a superheated steam valve 14 to switch to a steam-air mixed medium to enhance heat exchange under high load.

[0076] When the system detects an increase in heat load, the cascade heat supply regulation unit opens the superheated steam valve 14, introducing the superheated steam generated by the third-stage heat storage unit 3 into the heat exchange circuit of the first-stage heat storage unit 1 through the injection port, where it forms a mixed medium with the existing heat medium (e.g., air). The high enthalpy and excellent heat transfer properties of superheated steam significantly improve the heat transfer coefficient, enhancing the efficiency of heat transfer from the first heat storage body 11 to the feed water, allowing the feed water to reach the preheating target temperature in a shorter time. Simultaneously, the turbulent flow effect formed during the flow of the steam-air mixture further disrupts the boundary layer, reducing thermal resistance and improving overall heat exchange efficiency. This dynamic switching mechanism enables the first-stage heat storage unit 1 to respond quickly under high-load conditions, meeting peak demand by optimizing the physical properties of the heat exchange medium and avoiding the system efficiency drop caused by the insufficient heat exchange capacity of a traditional single medium. At low loads, the superheated steam valve 14 is closed, and the system returns to normal operation mode, maintaining a stable preheating effect, achieving a balance between flexibility and energy efficiency.

[0077] In one embodiment, the second-stage heat storage unit 2 includes a carbon dioxide circulation loop, a calcium carbonate powder injection device 23, a gas-solid separator and a powder recovery bin, the carbon dioxide circulation loop is connected to the interior of the second heat storage body 21; the calcium carbonate powder injection device 23 is connected to the carbon dioxide circulation loop; the calcium carbonate powder injection device 23 is configured to inject calcium carbonate powder into the interior of the second heat storage body 21 through the carbon dioxide circulation loop; the gas-solid separator and the powder recovery bin are connected to the carbon dioxide circulation loop; the gas-solid separator and the powder recovery bin are configured to separate and recover the calcium carbonate powder in the carbon dioxide circulation loop; wherein, the calcium carbonate powder injection device 23, the gas-solid separator and the powder recovery bin constitute the solid particle injection and recovery system.

[0078] The solid particle injection and recovery system of the second-stage heat storage unit 2 realizes enhanced heat exchange and material circulation through a carbon dioxide circulation loop. When the system is under high load operation, the calcium carbonate powder injection device 23 is started to inject powdered calcium carbonate into the second heat storage body 21 through the carbon dioxide circulation loop. Under high temperature conditions (usually >800°C), calcium carbonate undergoes an endothermic decomposition reaction (CaCO3→CaO+CO2), absorbing and storing heat. At the same time, the carbon dioxide produced by decomposition flows along the circulation loop, carrying the decomposed calcium oxide particles to form a gas-solid two-phase flow. During the flow process, the calcium oxide particles frequently collide with the surface of the second heat exchanger 22, significantly enhancing the heat exchange efficiency by increasing the turbulence and destroying the boundary layer.

[0079] When the system is operating at a low load (the output thermal power is less than 50% of the rated thermal power), the gas-solid mixture enters the gas-solid separator and powder recovery bin, and the calcium oxide particles are separated from the airflow by centrifugal force or filtration mechanism. The separated calcium oxide particles are collected in the powder recovery bin, while the carbon dioxide continues to flow in the circulation loop. After the system load is reduced, the recovered calcium oxide and the carbon dioxide in the circulation loop react in reverse (CaO+CO2→CaCO3) at a lower temperature, releasing the stored heat and regenerating calcium carbonate, thus realizing material recycling. The system enhances heat exchange through the synergistic effect of chemical reaction energy storage and physical collision to improve the heat exchange efficiency under high load conditions, and reduces operating costs through material circulation. At the same time, it avoids the problem of heat exchanger wear caused by the long-term use of traditional solid particles and extends the life of the equipment.

[0080] In one embodiment, the third-stage heat storage unit 3 includes a nitrogen circulation loop, a quartz sand powder injection device 33, a gas-solid separator and a powder recovery bin. The nitrogen circulation loop is connected to the interior of the third heat storage body 31; the quartz sand powder injection device 33 is connected to the nitrogen circulation loop; the gas-solid separator and the powder recovery bin are connected to the nitrogen circulation loop; the gas-solid separator and the powder recovery bin are configured to separate and recover the quartz sand powder in the nitrogen circulation loop; wherein the quartz sand powder injection device 33, the gas-solid separator and the powder recovery bin constitute the solid particle injection and recovery system.

[0081] When the system detects a high-load operation requirement, the quartz sand powder injection device 33 activates, injecting quartz sand powder into the interior of the third thermal accumulator 31 through a connection to the nitrogen circulation loop. Using nitrogen as a carrier gas, a gas-solid two-phase flow is formed. Within the high-temperature environment of the third thermal accumulator 31, the quartz sand particles flow along with the nitrogen flow in the circulation loop, causing high-frequency collisions with the surface of the third heat exchanger 32. This physical impact disrupts the fluid boundary layer, significantly enhancing heat exchange efficiency and promoting the conversion of saturated steam to superheated steam.

[0082] When the system is operating at low load (output thermal power is less than 50% of the rated thermal power), the gas-solid mixture enters the gas-solid separator and powder recovery bin. Centrifugal force or filtration separates the quartz sand particles from the nitrogen gas flow. The separated nitrogen gas returns to the circulation loop to continue participating in the carrier gas process, while the quartz sand particles are stored in the powder recovery bin. When the system load decreases, the quartz sand powder injection is stopped, and only the nitrogen circulation is used to maintain basic heat exchange requirements, achieving flexible load adjustment.

[0083] The collision of quartz sand particles enhances heat transfer, effectively meeting the high-temperature heat source requirements under high-load conditions; nitrogen, as an inert carrier gas, avoids chemical reactions with thermal storage materials or heat exchangers in high-temperature environments, extending the service life of the equipment; the efficient separation mechanism of the gas-solid separator and powder recovery bin ensures the recycling rate of quartz sand powder, reducing material consumption and operating costs; the entire system improves heat transfer efficiency through physical intensification of heat exchange without introducing additional chemical reactions, and the high-temperature resistance of quartz sand particles enables it to adapt to the ultra-high temperature environment of the third echelon, ensuring stable operation of the system under extreme conditions.

[0084] In one embodiment, the circulation loop includes a gas purification branch and a particle circulation branch and an air blower arranged in parallel, the particle circulation branch is connected to the interior of the heat storage body, and the gas purification branch is connected to the gas-solid separator; the gas purification branch and the particle circulation branch are controlled by a valve; the air blower is connected to the particle circulation branch.

[0085] In one embodiment, the gas inside the gas purification branch is configured to enter the heat storage body after gas-solid separation in a gas-solid separator.

[0086] Specifically, such as Figure 1 As shown, in the second-stage thermal storage unit 2, the first particle circulation branch 27 is connected to the interior of the second thermal storage body 21, the first gas purification branch 26 is connected to the first gas-solid separator 24, and a valve controls the connection between the first gas purification branch 26 and the first particle circulation branch 27. A second air blower 28 is connected to the first particle circulation branch 27. In the second-stage thermal storage unit 2, the first particle circulation branch 27 is connected to the interior of the second thermal storage body 21, forming a closed loop for transporting carbon dioxide gas. When the system is operating at high load, the calcium carbonate powder injection device 23 injects particles into the first particle circulation branch 27. The carbon dioxide gas driven by the second air blower 28 circulates the solid particles within the first particle circulation branch 27 and the second thermal storage body 21, thereby achieving the aforementioned goal of significantly enhancing heat exchange efficiency by increasing turbulence and destroying the boundary layer. When the system is operating at low load, the first gas purification branch 26 is connected to the first particle circulation branch 27. The airflow of the first particle circulation branch 27 passes through the first gas purification branch 26 and then enters the second heat storage body 21. The first gas-solid separator 24 on the first gas purification branch 26 collects the particles in the airflow. The purified nitrogen can be returned to the first particle circulation branch 27 through valve control to re-participate in the heat exchange process, forming a closed-loop system.

[0087] Likewise, Figure 1 As shown, in the third-stage thermal storage unit 3, the second particle circulation branch 37 is connected to the interior of the third thermal storage body 31, the second gas purification branch 36 is connected to the second gas-solid separator 34, and the second gas purification branch 36 and the second particle circulation branch 37 are connected by a valve. The third air blower 38 is connected to the second particle circulation branch 37. In the third-stage thermal storage unit 3, the second particle circulation branch 37 is connected to the interior of the third thermal storage body 31, forming a closed loop for transporting nitrogen. When the system is operating at high load, the quartz sand powder injection device 33 injects particles into the second particle circulation branch 37. The nitrogen driven by the third blower carries the solid particles and circulates within the second particle circulation branch 37 and the third thermal storage body 31, thereby achieving the aforementioned purpose of enhancing heat exchange efficiency. When the system is operating at low load, the second gas purification branch 36 is connected to the second particle circulation branch 37. The airflow of the second particle circulation branch 37 passes through the second gas purification branch 36 and then enters the third heat storage body 31. The second gas-solid separator 34 on the second gas purification branch 36 collects the particles in the airflow. The purified nitrogen can be returned to the second particle circulation branch 37 through valve control to re-participate in the heat exchange process, forming a closed-loop system.

[0088] In one embodiment, the powder recovery bin is located at the lower side of the gas-solid separator, and the powder recovery bin is connected to the lower outlet of the gas-solid separator.

[0089] The powder recovery bin efficiently collects separated solid particles through gravity settling. After the gas-solid separator separates the gas-solid two-phase flow, the separated solid particles naturally fall due to gravity and fall directly into the powder recovery bin below through the lower outlet of the gas-solid separator. Specifically, the gas-solid separator achieves efficient gas-solid separation through the synergistic effect of centrifugal settling and inertial separation.

[0090] In one embodiment, the powder injection device is communicated with the powder recovery bin, and the powder injection device is configured to inject the powder in the powder recovery bin into the particle circulation branch again.

[0091] When the system detects a high load demand, the valve between the powder injection device and the powder recovery bin opens, and the solid particles (such as calcium oxide or quartz sand) in the recovery bin fall into the injection device's hopper under the action of gravity. The injection device uses a screw conveyor or rotary feeder to quantitatively transport the particles to the particle circulation branch, where they mix with the high-pressure carrier gas (carbon dioxide or nitrogen) to form a gas-solid two-phase flow.

[0092] In one embodiment, each heat storage body includes an outer shell, a plurality of high-magnesium electric heat storage columns vertically installed inside the outer shell, and a thermal resistor installed inside the electric heat storage column; wherein, the heat storage material of the first heat storage body 11 is a high-magnesium brick with a magnesium oxide content ≥90%, the heat storage material of the second heat storage body 21 is a magnesium-carbon brick with a carbon content ≥15%, and the heat storage material of the third heat storage body 31 is a magnesium-carbon brick with a carbon content ≥25%.

[0093] The first heat storage body 11 uses high-magnesium bricks with a magnesium oxide content of ≥90%. Its high thermal conductivity and good thermal shock resistance make it suitable for medium-temperature environments of 500-800°C, and can quickly convert electrical energy into thermal energy and transfer it to the water supply. The second heat storage body 21 uses magnesium-carbon bricks with a carbon content of ≥15%. The high thermal conductivity of the carbon phase improves the thermal response speed, while the magnesium sand matrix provides high temperature resistance. In a high-temperature environment of 800-1200°C, the carbon phase can inhibit the sintering and growth of magnesium sand grains, maintain the pore structure of the material, and enable the second heat storage body 21 to maintain stable thermal conductivity when decomposing calcium carbonate. The third heat storage body 31 uses magnesium-carbon bricks with a carbon content of ≥25%. The higher carbon content further enhances the thermal conductivity and meets the ultra-high temperature requirements of 1200-1600°C.

[0094] In one embodiment, an exhaust pipe communicating with the interior of the first heat storage body 11 is provided on the outer shell of the first heat storage body 11 , and an exhaust valve 52 is provided on the exhaust pipe.

[0095] The drain pipe and drain valve 52 of the first thermal accumulator 11 are primarily used for gas replacement and pressure regulation during system startup, shutdown, and troubleshooting. Before system startup, the drain valve 52 is opened, allowing outside air to enter the first thermal accumulator 11 through the drain pipe, displacing any remaining nitrogen or other inert gases. This creates an open environment within the first thermal accumulator 11, preventing pressure imbalances caused by gas accumulation from affecting subsequent heat exchange efficiency. During system shutdown for maintenance, the drain valve 52 is also opened to discharge high-temperature gases, allowing operators to safely enter the equipment for inspection and maintenance.

[0096] In one embodiment, the cascade heat supply regulating unit includes a pipeline, a saturated steam inlet regulating valve 41, a superheated steam inlet regulating valve 42, a back pressure valve 43, a buffer tank 44 and a water supply pump 45. The pipeline is configured to connect the first heat exchanger 12, the second heat exchanger 22 and the third heat exchanger 32 in series in sequence; the saturated steam inlet regulating valve 41 is connected to the pipeline between the first heat exchanger 12 and the second heat exchanger 22; the superheated steam inlet regulating valve 42 is connected to the pipeline between the second heat exchanger 22 and the third heat exchanger 32; the back pressure valve 43 is connected to the outlet end of the pipeline; the buffer tank 44 and the water supply pump 45 are connected to the inlet end of the pipeline; wherein, the cascade heat supply regulating unit is configured to realize the separate or combined output of hot water, saturated steam and superheated steam through a valve combination.

[0097] The working mode of the cascade heating regulation unit is as follows: the feed water enters the pipeline after being pressurized by the water feed pump 45, and first flows through the first heat exchanger 12 to be preheated. If only hot water output is required at this time, the saturated steam inlet regulating valve 41 and the superheated steam inlet regulating valve 42 can be closed, and the back pressure valve 43 can be adjusted to maintain the pipeline pressure, so that the hot water is directly output from the outlet of the hot water outlet regulating valve 46 of the pipeline; if saturated steam is required, the saturated steam inlet regulating valve 41 is opened to allow the preheated water to enter the second heat exchanger 22, and the heat of the second heat storage body 21 is used to convert it into saturated steam. At this time, the back pressure valve 43 controls the outlet pressure to match the corresponding temperature of the saturated steam, and the saturated steam can be output from the outlet of the saturated steam regulating valve 47 of the pipeline; if superheated steam is required, the superheated steam inlet regulating valve 42 is further opened to allow the saturated steam to enter the third heat exchanger 32, and after being heated by the third heat storage body 31 to become superheated steam, it is output from the outlet of the back pressure valve 43. The back pressure valve 43 ensures the stability of the pipeline pressure in this process to prevent steam backflow. When combined output is required, the opening of each regulating valve can be adjusted proportionally. For example, when saturated steam and superheated steam are output simultaneously, part of the saturated steam is drawn out from the second heat exchanger 22, and the other part continues to enter the third heat exchanger 32 for heating, thereby realizing the on-demand distribution of different heat media.

[0098] Through valve combination adjustment, the system can flexibly switch between three output modes: hot water, saturated steam, and superheated steam to meet the diverse needs of different industrial scenarios.

[0099] In one embodiment, the cascade heating regulation unit further includes a hot water outlet regulating valve 46 and a saturated steam regulating valve 47. The hot water outlet regulating valve 46 is connected between the first heat exchanger 12 and the saturated steam inlet regulating valve 41; the saturated steam regulating valve 47 is connected between the second heat exchanger 22 and the superheated steam inlet regulating valve 42.

[0100] The cascade heat supply regulation unit further refines the heat output control capability through the newly added hot water outlet regulating valve 46 and saturated steam regulating valve 47. When the system needs hot water, the feed water is pressurized by the water pump 45 and flows into the first heat exchanger 12 for preheating. At this time, the hot water outlet regulating valve 46 is opened, and the saturated steam inlet regulating valve 41 and saturated steam regulating valve 47 are closed. The preheated hot water can be directly output through the hot water outlet regulating valve 46, meeting the hot water demand scenario of 50-200°C. If saturated steam is required, the hot water outlet regulating valve 46 and superheated steam inlet regulating valve 42 can be closed, and the saturated steam inlet regulating valve 41 can be opened, allowing the preheated water to enter the second heat exchanger 22. Under the action of the second heat storage body 21, it is converted into saturated steam. The saturated steam regulating valve 47 can adjust the output flow.

[0101] In one embodiment, the step heating regulation unit further includes an air valve 51 , and the air valve 51 is connected to the first heat exchanger 12 .

[0102] The air valve 51 of the cascade heating control unit introduces external air for flexible system regulation and emergency protection. When the system is operating at low load or requires rapid cooling, the air valve 51 opens, allowing ambient air to enter the first heat exchanger 12 through the air valve 51, where it mixes with the high-temperature heat medium (such as steam or nitrogen), reducing the outlet temperature through heat dilution.

[0103] During emergency shutdowns or troubleshooting, the air valve 51 serves as a safety redundancy feature. If the temperature of the first heat storage element 11 rises abnormally (e.g., exceeding 900°C) or the system pressure surges, the air valve 51 rapidly opens, allowing a large amount of cold air to flow into the first heat exchanger 12. This heat exchange quickly removes heat from the heat storage element's surface and dilutes the internal gas concentration, preventing material aging or equipment damage caused by local overheating.

[0104] According to an embodiment of the present invention, on the other hand, a method for operating a heat storage system based on cascade utilization of high-temperature waste heat is provided, comprising:

[0105] Heat storage stage: Each heat storage unit is filled with a specified gas medium and pressurized, and the heat storage body is heated electrically to reach the set temperature gradient;

[0106] Low load operation mode: using single-phase gas medium circulation heat exchange;

[0107] High-load operation mode: solid particles are injected into the second-stage heat storage unit 2 and the third-stage heat storage unit 3, and the heat exchange efficiency is improved by pressure or medium switching;

[0108] Shutdown protection stage: cool down each thermal storage unit in stages from high temperature to low temperature and recover solid particles, and keep steam flushing of heat exchange pipelines until the temperature is below the safety threshold.

[0109] In one embodiment, the high load operation mode includes:

[0110] Inject superheated steam into the first-stage thermal storage unit 1 and make the operating pressure ≥ 15kPa;

[0111] Injecting calcium carbonate powder into the circulating medium of the second-stage thermal storage unit 2 to enhance heat transfer by utilizing its decomposition-regeneration reaction;

[0112] Quartz sand powder is injected into the circulating medium of the third-stage heat storage unit 3 to enhance heat transfer through the collision of solid particles with the heat exchange surface.

[0113] In one embodiment, the shutdown protection stage includes:

[0114] The third-stage thermal storage unit 3 is preferentially cooled to below 800°C, and the quartz sand is recovered through the solid particle injection and recovery system;

[0115] The second-stage thermal storage unit 2 is cooled to below 600°C and calcium carbonate is recovered simultaneously;

[0116] Perform steam replacement on the first-stage heat storage unit 1, and maintain the pipeline pressure >1000Pa until the air completely replaces the steam.

[0117] The operation method provided in this embodiment is specifically as follows:

[0118] Open the air valve 51 and close the exhaust valve 52, run the first air blower 15, fill the first thermal storage body 11 with air, and after the pressure in the first thermal storage body 11 is no less than 8000 Pa, close the first air blower 15 and the air valve 51, connect the first thermal storage body 11 junction box, and use electricity to heat the high magnesium electric thermal storage column in the first thermal storage body 11 to 800-900°C;

[0119] The carbon dioxide gas storage device 61 is operated to fill the second thermal storage body 21 with carbon dioxide gas. After the pressure in the second thermal storage body 21 reaches no less than 1000 Pa, the carbon dioxide gas storage device 61 is closed, and the junction box of the second thermal storage body 21 is connected. The magnesium-carbon electric thermal storage column in the second thermal storage body 21 is heated by electricity to a temperature of 950-1000°C.

[0120] Run the nitrogen storage device 62 to fill the second thermal storage body 21 with nitrogen. After the pressure in the second thermal storage body 21 is no less than 1000 Pa, close the nitrogen storage device 62, connect the junction box of the third thermal storage body 31, and use electricity to heat the magnesium-carbon electric thermal storage column in the third thermal storage body 31 to 1200-1400°C.

[0121] Open the saturated steam inlet regulating valve 41, the superheated steam inlet regulating valve 42 and the back pressure valve 43 in sequence, and operate the feed water pump 45 so that water flows from the feed water tank through the feed water pump 45 and the buffer tank 44, and then passes through the first heat exchanger 12, the second heat exchanger 22, the third heat exchanger 32 and the back pressure valve 43 in sequence before leaving the system;

[0122] During low-load operation (the output thermal power is less than 50% of the rated thermal power), the first air blower 15 is operated and adjusted to realize the circulation of air between the first thermal storage body 11 and the first heat exchanger 12, and transfer heat from the first thermal storage body 11 to the first heat exchanger 12, so as to increase the temperature of the feed water to become saturated water;

[0123] The second air blower 28 is operated and adjusted to realize the circulation of carbon dioxide gas between the second thermal storage body 21 and the second heat exchanger 22, thereby transferring heat from the second thermal storage body 21 to the second heat exchanger 22, thereby converting saturated water into saturated steam;

[0124] The third air blower 38 is operated and adjusted to circulate nitrogen between the third thermal storage body 31 and the third heat exchanger 32, thereby transferring heat from the third thermal storage body 31 to the third heat exchanger 32, thereby converting saturated steam into superheated steam.

[0125] By adjusting the water pump operation, hot water outlet regulating valve 46, saturated steam regulating valve 47, and superheated steam inlet regulating valve 42, hot water, saturated steam, and superheated steam can be output individually or in any combination. The first heat accumulator 11 utilizes heat-resistant high-magnesium bricks, the second heat accumulator 21 utilizes heat-resistant magnesium-carbon bricks with a carbon content of at least 15%, and the third heat accumulator 31 utilizes heat-resistant magnesium-carbon bricks with a carbon content of at least 25%. Since carbon has a higher melting point than magnesium oxide, a higher carbon content allows the heat accumulator to operate at higher temperatures. However, carbon reacts with various gases, such as oxygen, water vapor, and carbon dioxide, at high temperatures, limiting the range of heat exchange media available. When using water, saturated steam, or superheated steam as the heat output medium, its temperature and gas-liquid state determine the quality of the heat energy. Superheated steam is the highest quality of the three, followed by saturated steam, and water is the lowest. Accordingly, the heat accumulators utilize different heat storage bricks, enabling long-life, economical operation to meet different levels of heat output. When operating at low load, the first heat storage body 11 uses air as the heat exchange medium to meet the heat exchange requirements. The air can be replenished free of charge at any time, and the operation economy is good; the second heat storage body 21 uses carbon dioxide as the heat exchange medium. The triatomic carbon dioxide has certain gas radiation characteristics, which can meet the heat exchange requirements; the third heat storage body 31 uses nitrogen as the heat exchange medium, mainly because nitrogen is an inert gas at the operating temperature, does not react with carbon, and has weak heat exchange characteristics. However, the temperature of the third heat storage body 31 is the highest, and the larger temperature difference makes up for the defect of the low heat transfer coefficient, so the heat exchange requirements can be met at low load.

[0126] When operating at high load (output thermal power is between 50% and 100% of rated thermal power), the superheated steam valve 14 is opened, and superheated steam enters the first heat accumulator 11 from the superheated steam inlet, forms a mixed gas with air, and circulates between the first heat accumulator 11 and the first heat exchanger 12 under the action of the first air blower 15. When the pressure in the first heat accumulator 11 is not less than 15kPa, the superheated steam valve 14 is closed to achieve enhanced heat exchange under pressure environment, and transfer heat from the first heat accumulator 11 to the first heat exchanger 12; the calcium carbonate powder is added to the air inlet pipe of the second heat accumulator 21 by the calcium carbonate powder injection device 23 (feeder), enters the second heat accumulator 21 with the circulating carbon dioxide gas, and is discharged from the second heat accumulator 21. The calcium oxide and carbon dioxide are heated by the high-temperature carbon-magnesium heat storage column and decomposed into calcium oxide particles and carbon dioxide gas. Under the action of the second air blower 28, they enter the second heat exchanger 22 together with the circulating carbon dioxide gas. In the second heat exchanger 22, due to the decrease in temperature, the calcium oxide and carbon dioxide are converted back into calcium carbonate particles and release heat. The heat transfer is enhanced by the collision of the calcium carbonate particles with the heat exchange surface. The quartz sand powder is added to the air inlet pipe of the third heat storage body 31 by the quartz sand powder injection device 33 (feeder). The quartz sand powder enters the third heat storage body 31 along with the circulating nitrogen and is heated by the high-temperature carbon-magnesium heat storage column in the third heat storage body 31. Under the action of the third air blower 38, the quartz sand powder enters the third heat exchanger 32 along with the circulating nitrogen. The heat transfer is enhanced by the collision of the quartz sand particles with the heat exchange surface.

[0127] When the system stops running, the third heat storage body 31 is powered off, valves e and f are opened, and valve d is closed. The nitrogen carrying the quartz sand powder enters the second gas-solid separator 34. After the quartz sand powder is separated, it enters the second powder recovery bin 35. The separated nitrogen passes through f and the circulating air inlet of the third heat storage body 31 and enters the third heat storage body 31. When the temperature of the high-temperature carbon magnesium heat storage column drops below 800°C, the third air blower 38 is stopped. Steam always passes through the third heat exchanger 32 before the third air blower 38 stops. The second heat storage body 21 is powered off, valves b and c are opened, and valve a is closed. The carbon dioxide gas carrying the calcium carbonate powder enters the first gas-solid separator 24. After the calcium carbonate powder is separated, it enters the first powder recovery bin 25. The separated carbon dioxide gas enters the second heat storage body 21 through the valve c and the circulating air inlet of the second heat storage body 21. When the temperature of the high-temperature carbon magnesium heat storage column drops below 600°C, the second air fan 28 is stopped. Before the second air fan 28 stops, there is always steam passing through the third heat exchanger 32; the first heat storage body 11 is powered off, and the drain valve 52 is opened. When the pressure in the first heat storage body 11 drops below 1000Pa, the air valve 51 is opened. Under the action of the air fan, the air completely replaces the steam. The first air fan 15 and the air valve 51 are closed, and the drain valve 52 is kept open.

[0128] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A heat storage system for cascade utilization of high-temperature waste heat, characterized in that: include: A first cascade heat storage unit (1) comprises a first heat storage body (11) and a first heat exchanger (12) matched with the first heat storage body (11), wherein the first cascade heat storage unit (1) is configured to preheat feed water via the first heat storage body (11) and the first heat exchanger (12); A second cascade heat storage unit (2) comprises a second heat storage body (21) and a second heat exchanger (22) matched with the second heat storage body (21), wherein the second cascade heat storage unit (2) is configured to convert preheated water into saturated steam via the second heat storage body (21) and the second heat exchanger (22); A third cascade heat storage unit (3) comprises a third heat storage body (31) and a third heat exchanger (32) matched with the third heat storage body (31), wherein the third cascade heat storage unit (3) is configured to convert saturated steam into superheated steam via the third heat storage body (31) and the third heat exchanger (32); a cascade heat supply regulating unit connected to the three heat storage units and configured to control a heat medium flow path; Each heat storage unit uses a heat storage medium and a heat exchange medium of different compositions, and the second-stage heat storage unit (2) and the third-stage heat storage unit (3) are respectively equipped with a solid particle injection and recovery system to enhance heat exchange through particle collision during high-load operation.

2. The heat storage system for cascade utilization of high-temperature waste heat according to claim 1, characterized in that: The first-stage heat storage unit (1) is equipped with a superheated steam injection interface (13) and a superheated steam valve (14) so as to switch to a steam-air mixed medium to enhance heat exchange under high load.

3. The heat storage system for cascade utilization of high-temperature waste heat according to claim 1, characterized in that: The second-stage heat storage unit (2) comprises: A carbon dioxide circulation loop connected to the interior of the second heat storage body (21); A calcium carbonate powder injection device (23) is connected to the carbon dioxide circulation loop; the calcium carbonate powder injection device (23) is configured to inject calcium carbonate powder into the interior of the second heat storage body (21) through the carbon dioxide circulation loop; A gas-solid separator and a powder recovery bin are connected to the carbon dioxide circulation loop; the gas-solid separator and the powder recovery bin are configured to separate and recover calcium carbonate powder in the carbon dioxide circulation loop; The calcium carbonate powder injection device (23), the gas-solid separator and the powder recovery bin constitute the solid particle injection and recovery system.

4. The heat storage system for cascade utilization of high-temperature waste heat according to claim 1, characterized in that: The third-stage heat storage unit (3) comprises: A nitrogen circulation loop connected to the interior of the third heat storage body (31); a quartz sand powder injection device (33) connected to the nitrogen circulation loop; A gas-solid separator and a powder recovery bin are connected to the nitrogen circulation loop; the gas-solid separator and the powder recovery bin are configured to separate and recover the quartz sand powder in the nitrogen circulation loop; The quartz sand powder injection device (33), the gas-solid separator and the powder recovery bin constitute the solid particle injection and recovery system.

5. The heat storage system for cascade utilization of high-temperature waste heat according to claim 3 or 4, characterized in that: The circulation loop includes: A gas purification branch and a particle circulation branch are arranged in parallel, wherein the particle circulation branch is connected to the interior of the heat storage body, and the gas purification branch is connected to the gas-solid separator; the gas purification branch and the particle circulation branch are controlled by a valve; An air blower is connected to the particle circulation branch.

6. The heat storage system for cascade utilization of high-temperature waste heat according to claim 5, characterized in that: The gas inside the gas purification branch is configured to enter the interior of the heat storage body after being separated into gas and solid by the gas-solid separator.

7. The heat storage system for cascade utilization of high-temperature waste heat according to claim 6, characterized in that: The powder recovery bin is located at the lower side of the gas-solid separator, and the powder recovery bin is communicated with the lower outlet of the gas-solid separator.

8. The heat storage system for cascade utilization of high-temperature waste heat according to claim 7, characterized in that: The powder injection device is communicated with the powder recovery bin, and the powder injection device is configured to inject the powder in the powder recovery bin into the particle circulation branch again.

9. The thermal storage system for cascade utilization of high-temperature waste heat according to any one of claims 1 to 4, characterized in that: Each heat storage body includes a shell, a plurality of high-magnesium electric heat storage columns vertically installed inside the shell, and a thermal resistor installed inside the electric heat storage columns; The heat storage material of the first heat storage body (11) is a high-magnesium brick with a magnesium oxide content of ≥90%, the heat storage material of the second heat storage body (21) is a magnesium-carbon brick with a carbon content of ≥15%, and the heat storage material of the third heat storage body (31) is a magnesium-carbon brick with a carbon content of ≥25%.

10. The heat storage system for cascade utilization of high-temperature waste heat according to claim 9, characterized in that: An exhaust pipe communicating with the interior of the first heat accumulator (11) is provided on the outer shell of the first heat accumulator (11), and an exhaust valve (52) is provided on the exhaust pipe.

11. The thermal storage system for cascade utilization of high-temperature waste heat according to any one of claims 1 to 4, characterized in that: The cascade heating adjustment unit includes: a pipeline, wherein the pipeline is configured to sequentially connect the first heat exchanger (12), the second heat exchanger (22), and the third heat exchanger (32) in series; a saturated steam inlet regulating valve (41) connected to the pipeline between the first heat exchanger (12) and the second heat exchanger (22); a superheated steam inlet regulating valve (42) connected to the pipeline between the second heat exchanger (22) and the third heat exchanger (32); a back pressure valve (43), connected to the outlet end of the pipeline; a buffer tank (44) and a water pump (45), and an inlet end of the pipeline; Wherein, the cascade heating regulation unit is configured to realize the separate or combined output of hot water, saturated steam and superheated steam through a valve combination.

12. The heat storage system for cascade utilization of high-temperature waste heat according to claim 11, characterized in that: The step heat supply regulating unit further comprises: a hot water outlet regulating valve (46) connected between the first heat exchanger (12) and the saturated steam inlet regulating valve (41); A saturated steam regulating valve (47) is connected between the second heat exchanger (22) and the superheated steam inlet regulating valve (42).

13. The heat storage system for cascade utilization of high-temperature waste heat according to claim 11, characterized in that: The step heat supply regulating unit further comprises an air valve (51), and the air valve (51) is connected to the first heat exchanger (12).

14. An operating method of a heat storage system based on the cascade utilization of high-temperature waste heat according to any one of claims 1 to 7, characterized in that: include: Heat storage stage: Each heat storage unit is filled with a specified gas medium and pressurized, and the heat storage body is heated electrically to reach the set temperature gradient; Low load operation mode: using single-phase gas medium circulation heat exchange; High-load operation mode: solid particles are injected into the second-stage heat storage unit (2) and the third-stage heat storage unit (3), and heat exchange efficiency is improved by pressure or medium switching; Shutdown protection stage: cool down each thermal storage unit in stages from high temperature to low temperature and recover solid particles, and keep steam flushing of heat exchange pipelines until the temperature is below the safety threshold.

15. The method for cascade utilization of high-temperature waste heat according to claim 14, characterized in that: The high-load operation mode includes: Injecting superheated steam into the first-stage heat storage unit (1) and making the operating pressure ≥15 kPa; Injecting calcium carbonate powder into the circulating medium of the second-stage heat storage unit (2) to enhance heat transfer by utilizing its decomposition-regeneration reaction; Quartz sand powder is injected into the circulating medium of the third-stage heat storage unit (3), and heat transfer is enhanced by the collision of solid particles with the heat exchange surface.

16. The method for cascade utilization of high-temperature waste heat according to claim 15, characterized in that: The shutdown protection stage includes: The third-stage heat storage unit (3) is preferentially cooled to below 800° C., and the quartz sand is recovered through a solid particle injection and recovery system; Cooling the second-stage heat storage unit (2) to below 600° C. and simultaneously recovering calcium carbonate; The first-stage heat storage unit (1) is subjected to steam replacement, and the pipeline pressure is maintained at >1000 Pa until the complete replacement of steam by air is completed.

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