Thermochemical energy storage system
By embedding the heat exchange buried pipe into the energy storage unit in the thermochemical energy storage system and using a steam induction device for efficient steam regulation, the problem of long heat transfer paths and leakage and mechanical wear of the mechanical pump system at high temperatures is solved, and an efficient and stable energy conversion process is achieved.
Patent Information
- Application Number
- CN202510539767.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-27
- Publication Date
- 2025-06-13
AI Technical Summary
The current solar thermal chemical energy storage system has limited energy storage efficiency during the thermochemical reaction process, mainly due to the lengthy heat transfer path and the leakage and mechanical wear of mechanical pump systems at high temperatures.
By directly embedded in the heat exchange buried pipe inside the energy storage unit, an integrated "reaction-heat transfer" space is formed, and a steam induction device is used for efficient steam regulation, which avoids seal failure and mechanical wear of traditional power conveying equipment.
It achieves shortening of the heat transfer path, reducing heat transfer loss, improving the thermodynamic coupling efficiency, and enhancing the efficiency and stability of the system.
Smart Images
Figure CN120140966A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solar thermal power generation, and particularly to a thermochemical energy storage system. Background Art
[0002] The inherent intermittency characteristics of solar power generation systems and the spatio-temporal mismatch problem between energy supply and demand seriously restrict their large-scale application process. It is urgent to break through high-efficiency energy storage technologies to achieve continuous and stable energy supply.
[0003] In the existing energy storage technology system, although sensible heat energy storage and latent heat energy storage have been commercially applied, they have technical bottlenecks such as low energy density (<500 kJ / kg), high heat loss rate (>20%), and insufficient cycle stability, making it difficult to meet the requirements of large-scale high-temperature industrial scenarios. In contrast, thermochemical energy storage realizes energy storage and release through reversible chemical reactions, showing breakthrough technical advantages: the energy storage density can reach 5-10 times that of sensible heat energy storage, cross-seasonal lossless heat storage can be achieved, and different temperature requirements can be flexibly matched through the design of chemical reaction paths, providing a revolutionary technical path for solving the problem of renewable energy consumption.
[0004] To achieve efficient and stable output of solar power generation, a compatible thermochemical energy storage system is required. However, there are still problems with limited energy storage efficiency in the thermochemical reaction process of the current solar thermochemical energy storage system. The main reasons are as follows: First, the traditional fixed reactor and the molten salt circulation system of the solar thermal power station adopt a series connection design, resulting in a long heat transfer path (typical heat loss >15%) and low thermodynamic coupling efficiency; Second, in the steam regulation system (including metal mechanical seals and impeller bearing components) of the mechanical pump connected to the reactor, at a working condition of >300°C, due to the mismatch of the thermal expansion coefficients of the seals, the leakage rate >2.0%, it is difficult to achieve sufficient reaction requirements in a short time for steam supply, and the high-temperature lubrication of the impeller bearings fails, causing mechanical wear, presenting serious operation risks. Against the background of the increasingly prominent contradiction between energy supply and demand, new energy storage systems with high energy storage efficiency have become a common technical problem in promoting the transformation of the energy structure. Summary of the Invention
[0005] In order to solve the above technical problems, the present invention provides a thermochemical energy storage system, which can improve the energy storage efficiency in the thermochemical reaction process of the thermochemical energy storage system.
[0006] The present invention provides a thermochemical energy storage system, comprising: a thermochemical energy storage module, including a housing and an energy storage unit fixed inside thereof. The energy storage unit is filled with a solid energy storage medium. The bottom of the energy storage unit has an air inlet hole. Inside the energy storage unit, there are fixed heat exchange buried pipes and steam vaporization pipes. The inlet end of the heat exchange buried pipe is connected to a heat transfer medium storage tank, and the outlet end is connected to an external heat-using device. Both ends of the steam vaporization pipe are connected to a water tank to form a circulation pipeline. There is an air outlet hole on the steam vaporization pipe. The energy storage unit and the water tank are connected to a solar heating unit. The solar heating unit includes a resistance heating element and a heat conducting rod. The resistance heating element is connected inside the water tank, and the heat conducting rod is connected inside the energy storage unit. Both the resistance heating element and the heat conducting rod are connected to a photovoltaic power generation device; a steam ejector device, including an integrated mixing chamber and diffuser chamber. The mixing chamber is respectively connected with a main flow channel and an ejector flow channel. The first air outlet of the water tank is connected to the main flow channel, and the second air outlet of the water tank is connected to the ejector flow channel after being connected to a pressure pump. The outlet of the diffuser chamber is connected to the bottom of the energy storage unit to enable steam to enter through the air inlet hole.
[0007] Optionally, the outlet end of the steam vaporization pipe is inclined downward and arranged on the lower side wall of the energy storage unit.
[0008] Optionally, the inclination angle of the outlet end of the steam vaporization pipe is 5° - 10°, and the aperture of the air outlet hole of the steam vaporization pipe is 50μm - 200μm.
[0009] Optionally, the outlet of the mixing chamber is connected to the bottom of the housing through a steam pipeline, and the steam pipeline has a plurality of branches evenly distributed inside the housing. A redistribution plate is connected below the energy storage unit. The redistribution plate is located above the branches. The redistribution plate has micropores, and the aperture of the micropores is 1mm - 3mm.
[0010] Optionally, the heat exchange buried pipes are arranged in a serpentine shape inside the energy storage unit and cover the entire longitudinal space of the energy storage unit. The inlet and outlet of the heat exchange buried pipes both extend out of the top of the housing. The steam vaporization pipe is in a three-section bent shape, and the middle section is close to the side wall of the energy storage unit.
[0011] Optionally, the solar heating unit includes a photovoltaic power generation device, a resistance heating element, and a heat conducting rod. The resistance heating element is connected inside the water tank, and the heat conducting rod is connected inside the energy storage unit. Both the resistance heating element and the heat conducting rod are connected to the photovoltaic power generation device.
[0012] Optionally, the outlet end of the heat transfer medium storage tank is connected to the low-temperature side inlet of a preheater. The low-temperature side outlet of the preheater is connected to the inlet end of the heat exchange buried pipe. The high-temperature side inlet of the preheater is connected to the second air outlet of the water tank. The high-temperature side outlet of the preheater is connected to a pressure pump.
[0013] Optionally, there are multiple energy storage units, and the multiple energy storage units are detachably connected in parallel.
[0014] Optionally, an exhaust valve is provided at the upper part of the outer shell, a blowdown valve is provided at the bottom of the outer shell, thermocouples are evenly distributed in the energy storage unit, and a condensation pipeline is also connected between the outer shell and the water tank.
[0015] Optionally, the steam ejector device further includes a contraction chamber connected to the mixing chamber, the ejector flow channel is connected with a throat structure, and both the throat structure and the main flow channel are connected to the contraction chamber.
[0016] The technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art: A thermochemical energy storage system provided by an embodiment of the present invention directly embeds a heat exchange buried pipe inside the energy storage unit. The heat exchange buried pipe is in close contact with the energy storage medium to form a "reaction-heat transfer" integrated space. The whole system includes an energy release stage and an energy storage stage. In the initial stage of the reaction in the energy release stage, water in the water tank is heated to 150 °C by a solar heating unit to generate water vapor. The steam enters the energy storage unit from the bottom of the energy storage unit through a steam ejector device and reacts with the solid energy storage medium therein through a hydration reaction. After the reaction enters a steady state, the steam vaporization pipeline is opened. When the liquid water in the water tank flows through the steam vaporization pipeline under its own weight, it absorbs the chemical heat released by the hydration reaction in the energy storage unit and vaporizes into steam, realizing self-sustaining steam supply. The heat-conducting medium in the heat exchange buried pipe outputs the reaction heat to external heat-using equipment. The reaction heat release raises the temperature inside the outer shell to above 300 °C. At the same time, the volume ratio of the high-pressure steam entering the ejector flow channel through a pressure pump and the low-pressure steam entering the main flow channel is regulated in real time through the steam ejector device. The two fluid streams are fully mixed in the mixing chamber and a local vacuum is formed in the mixing chamber for energy exchange. The kinetic energy of the high-pressure steam is transferred to the entrained low-pressure steam. Subsequently, the mixed fluid enters the diffuser chamber, and the kinetic energy is converted into pressure energy to increase the pressure. Finally, it is discharged from the outlet end and transported to the bottom of the outer shell and enters the energy storage unit from the bottom through the air inlet hole, cooperating with the steam discharged from the air outlet hole of the steam vaporization pipeline to provide power and medium conditions for subsequent energy storage reactions. The unreacted steam in the steam vaporization pipeline returns to the water tank. In the energy storage stage, the energy storage unit is heated by a solar heating unit to decompose Mg(OH) 2 into MgO and water vapor at above 350 °C. The overall structure is beneficial to improving the volume utilization rate of the outer shell, shortening the heat transfer path, reducing heat transfer losses, and realizing efficient thermal coupling of the system. The steam ejector device actively sucks in low-pressure steam using the pressure difference and realizes mixing through kinetic energy conversion. There are no moving parts throughout the process, avoiding problems such as seal failure, component deformation, or control lag caused by high temperature in traditional power transmission equipment, thereby realizing a more efficient and stable energy conversion process. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a schematic structural diagram of a thermochemical energy storage system provided by an embodiment of the present invention; Figure 2Structural schematic diagram of the steam ejector device provided by the embodiment of the present invention.
[0018] Explanation of reference numerals: 1, Photovoltaic power generation device; 2, Drain valve; 3, Steam vaporization pipeline; 4, Resistance heating element; 5, Water tank; 6, Make-up water valve; 7, Preheater; 8, Heat-conducting medium storage tank; 9, Heat-conducting medium replenishing valve; 10, Pressurizing pump; 11, Steam ejector device; 12, High-temperature heat-conducting medium outlet valve; 13, Outer shell; 14, Energy storage unit; 15, Heat exchange buried pipe; 16, Exhaust valve; 17, Heat-conducting rod; 18, Negative terminal; 19, Positive terminal; 20, Thermocouple; 21, Blowdown valve; 22, Redistributing plate; 23, Main flow channel; 24, Ejector flow channel; 25, Throat structure; 26, Shrinkage chamber; 27, Mixing chamber; 28, Pulse backblower; 29, Diffuser chamber; 30, Self-cleaning flow channel; 31, Condensation pipeline. Specific embodiments
[0019] The following combines the drawings to describe a specific embodiment of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.
[0020] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.
[0021] The present invention will be described below through several specific embodiments. In order to keep the description clear and concise for the following embodiments of the present invention, the detailed description of known functions and known components may be omitted. When any component of the embodiments of the present invention appears in more than one drawing, the component may be represented by the same reference numeral in each drawing.
[0022] As Figure 1As shown in the figure, an embodiment of the present invention provides a thermochemical energy storage system, including: a thermochemical energy storage module and a steam ejector device 11. The thermochemical energy storage module includes a housing 13 and an energy storage unit 14 fixed inside it. The housing 13 provides mechanical support and thermal insulation to ensure the stable operation of the system under high temperature and high pressure. The energy storage unit 14 is filled with a solid energy storage medium (such as metal hydride, carbonate or oxide), and realizes heat storage and heat release through reversible chemical reactions (such as dehydration / hydration, reduction / oxidation). The bottom of the energy storage unit 14 has an air inlet hole for introducing reaction gases (such as water vapor, CO, etc.) to trigger the chemical reaction of the energy storage medium. It should be noted that the aperture of the air inlet hole needs to be smaller than the particle size of the solid energy storage medium. Specifically, the energy storage medium can be Mg(OH) 2 / MgO, Ca(OH) 2 / CaO, Ba(OH) 2 / BaO and other materials of the alkaline earth system. The following will all take Mg(OH) 2 / MgO as an example. A heat exchange buried pipe 15 and a steam vaporization pipe 3 are fixed in the energy storage unit 14. The inlet end of the heat exchange buried pipe 15 is connected to a heat transfer medium storage tank 8, and the heat transfer medium storage tank 8 is connected with a heat transfer medium filling valve 9 for supplementing the heat transfer medium. The heat transfer medium includes but is not limited to water, molten salt, heat transfer oil, etc. The outlet end is connected to an external heat-using device. The heat exchange buried pipe 15 is used to transfer heat to the external heat-using device during the energy release stage. Specifically, the outlet end of the heat exchange buried pipe 15 is connected with a high-temperature heat transfer medium outlet valve 12, and whether to communicate with the external heat-using device is controlled by the opening or closing of the high-temperature heat transfer medium outlet valve 12. Both ends of the steam vaporization pipe 3 are connected to a water tank 5 to form a circulation pipeline. A water filling valve 4 and a drainage valve 2 are respectively arranged at the top and bottom of the water tank 5 for the supplement and discharge of water in the tank. The steam vaporization pipe 3 has air outlet holes to make the steam uniformly penetrate into the energy storage medium to promote the chemical reaction. The energy storage unit 14 and the water tank 5 are connected to a solar heating unit. The steam ejector device 11 includes a mixing chamber 27 and a diffuser chamber 29 connected as a whole. The mixing chamber 27 is used to mix high-pressure mainstream steam and low-pressure ejector steam. The diffuser chamber 29 reduces the flow rate and increases the pressure through a gradually expanding structure to ensure the stable entry of steam into the energy storage unit 14. The mixing chamber 27 is respectively connected with a mainstream channel 23 and an ejector flow channel 24. The first air outlet of the water tank 5 is connected to the mainstream channel 23, and the second air outlet of the water tank 5 is connected to the ejector flow channel 24 after being connected to a pressurizing pump 10. The mainstream channel 23 is connected to the first air outlet of the water tank 5 to input high-pressure steam (driving fluid), and the ejector flow channel 24 is connected to the pressurizing pump 10 to extract and pressurize the low-pressure steam (ejected fluid) from the second air outlet of the water tank 5. The outlet of the diffuser chamber 29 is connected to the bottom of the energy storage unit 14 so that the steam enters through the air inlet hole.
[0023] A thermochemical energy storage system provided by an embodiment of the present invention directly embeds heat exchange buried pipes inside the energy storage unit. The heat exchange buried pipes are in close contact with the energy storage medium, forming a "reaction-heat transfer" integrated space. The whole system includes an energy release stage and an energy storage stage. In the initial stage of the reaction in the energy release stage, water in the water tank is heated to 150°C by a solar heating unit to generate water vapor. The steam enters the energy storage unit from the bottom of the energy storage unit through a steam ejector device and reacts with the solid energy storage medium therein through a hydration reaction. After the reaction enters a steady state, the steam vaporization pipeline is opened. When the liquid water in the water tank flows through the steam vaporization pipeline under its own weight, it absorbs the chemical heat released by the hydration reaction in the energy storage unit and vaporizes into steam, realizing self-sustained steam supply. The heat-conducting medium in the heat exchange buried pipes outputs the reaction heat to external heat-using equipment. The reaction heat release raises the temperature inside the outer shell to above 300°C. At the same time, the volume ratio of the high-pressure steam entering the ejector flow channel through the pressure pump and the low-pressure steam entering the main flow channel is regulated in real time through the steam ejector device. The two fluid streams are fully mixed in the mixing chamber and a local vacuum is formed in the mixing chamber for energy exchange. The kinetic energy of the high-pressure steam is transferred to the entrained low-pressure steam. Subsequently, the mixed fluid enters the diffuser chamber, where the kinetic energy is converted into pressure energy to increase the pressure. Finally, it is discharged from the outlet end and transported to the bottom of the outer shell and enters the energy storage unit from the bottom through the air inlet hole, cooperating with the steam discharged from the air outlet hole of the steam vaporization pipeline to provide power and medium conditions for subsequent energy storage reactions. The unreacted steam in the steam vaporization pipeline returns to the water tank. The overall structure is conducive to improving the volume utilization rate of the outer shell, shortening the heat transfer path, reducing heat transfer losses, and realizing efficient thermal coupling of the system. In the energy storage stage, the energy storage unit is heated by a solar heating unit so that Mg(OH) 2 decomposes into MgO and water vapor at temperatures above 350°C. The steam ejector device actively sucks in low-pressure steam using the pressure difference and realizes mixing through kinetic energy conversion. There are no moving parts throughout the process, avoiding problems such as seal failure, component deformation, or control lag caused by high temperatures in traditional power transmission equipment, thus realizing a more efficient and stable energy conversion process.
[0024] Refer again to Figure 1 , the outlet end of the steam vaporization pipeline 3 is inclined downward and arranged on the lower side wall of the energy storage unit 14. There is a certain angle below the steam vaporization pipeline 3 for sewage discharge and steam rising. The inclined flow channel promotes the rapid detachment of steam bubbles from the orifice of the air outlet hole, reducing the gas-liquid two-phase flow resistance and ensuring the stable output of steam in the self-sustained stage (relying on reaction heat vaporization).
[0025] Specifically, the inclination angle of the outlet end of the steam vaporization pipeline 3 is 5° - 10°, and the aperture of the air holes on the steam vaporization pipeline 3 is 50μm - 200μm. The inclination angle design of 5° - 10° enables the liquid water that has not been completely vaporized in the steam vaporization pipeline 3 to flow back along the pipe wall to the water tank 5 under the action of gravity, effectively preventing the blockage of the air holes of the steam vaporization pipeline 3 caused by the retention of condensate. The steam vaporization pipeline 3 is connected to the water tank 5, and the pipe wall of the steam vaporization pipeline 3 is provided with apertures of 50μm - 200μm to ensure the uniform distribution of steam and avoid the blockage of the air holes caused by the entry of the energy storage medium.
[0026] Optionally, the outlet of the mixing chamber 27 is connected to the bottom of the outer shell 13 through a steam pipeline, and the steam pipeline has a plurality of branches evenly distributed inside the outer shell 13. A redistribution plate 22 is connected below the energy storage unit 14. The redistribution plate 22 is located above the steam pipeline. The redistribution plate 22 has micropores with an aperture of 1mm - 3mm. There are dense small holes with a diameter of 1mm - 3mm on the redistribution plate 22, which are used for secondary uniform distribution of the steam coming out of the branches, and cooperate with the micropore distribution structure on the steam vaporization pipeline 3 to make the contact of the medium more uniform and avoid local overheating or incomplete reaction.
[0027] Optionally, the heat exchange buried pipes 15 are arranged in a serpentine shape in the energy storage unit 14 and cover the entire longitudinal space of the energy storage unit 14. The inlet and outlet of the heat exchange buried pipes 15 both extend out of the top of the outer shell 13. The steam vaporization pipeline 3 is in a three - section bent shape, and the middle section is close to the side wall of the energy storage unit 14. The serpentine heat exchange buried pipes 15 are directly embedded into the reaction cavity of the thermochemical energy storage module 13 by a spiral nested structure. The serpentine heat exchange buried pipes 15 are in close contact with the energy storage medium to form a "reaction - heat transfer" integrated space. The micropores of the steam vaporization pipeline 3 are evenly distributed on the side wall or the top of the energy storage unit 14, and are in an interlaced network layout with the heat exchange buried pipes 15, ensuring that the steam injection area completely overlaps with the area covered by the heat exchange tube cluster. This structure is beneficial to improving the volume utilization rate of the thermochemical energy storage module 13, shortening the heat transfer path, reducing the heat transfer loss, and realizing the efficient thermal coupling of the system.
[0028] The working principle of the thermochemical energy storage module is as follows: The energy storage unit 14 is filled with energy storage media such as Mg(OH) 2 / MgO in the alkaline earth system. During the energy release process, the water in the water tank 5 enters the energy storage unit 14 through the steam vaporization pipeline 3. The micropores with an aperture of 50μm - 200μm on the pipe wall of the steam vaporization pipeline 3 evenly distribute the steam at the upper, middle, and lower parts of the energy storage unit 14. Cooperating with the 5° - 10° inclination angle design at the bottom to promote the steam to form an upward flow state along the inclination direction and utilize gravity to self - drain condensate and sediments. Subsequently, the mixed steam is secondarily evenly distributed through the dense small holes with a diameter of 1mm - 3mm on the redistribution plate 22 from the branches of the steam pipeline, and fully contacts with the energy storage medium to undergo a thermochemical reaction (such as the reaction of MgO with water to form Mg(OH)2 The heat released by the reaction is transferred to the external heat-using equipment for storage through the built-in serpentine heat exchange buried pipe 15; when storing energy, the external heat is input through the serpentine heat exchange buried pipe 15 to drive the energy storage medium to undergo a reverse reaction (such as Mg(OH) 2 decomposes into MgO and absorbs heat), and the released energy can be utilized by subsequent systems.
[0029] Traditional solar photovoltaic power generation has day-and-night intermittency and meteorological sensitivity, and the existing system lacks an efficient utilization mechanism for solar photovoltaic power generation.
[0030] Based on the above problems, the solar heating unit includes a photovoltaic power generation device 1, a resistance heating element 4 and a heat conducting rod 17. The resistance heating element 4 is connected to the water tank 5, and the heat conducting rod 17 is connected to the energy storage unit 14. The resistance heating element 4 and the heat conducting rod 17 are both connected to the photovoltaic power generation device 1. The resistance heating element 4 is embedded in the inner wall of the water tank 5, and the power density is 50kW / m²-10kW / m². The heat conducting rod 17 extends to the inside of the energy storage unit 14, and the surface is coated with a high-temperature resistant ceramic layer, and is connected to the photovoltaic power supply circuit through the positive terminal 19 and the negative terminal 18. The photovoltaic power generation device 1 directly drives the resistance heating element 4 and the heat conducting rod 17, realizing the coordinated utilization of new energy and chemical energy storage, and reducing the dependence on the external power grid.
[0031] Energy storage stage: The photovoltaic power generation device 1 drives the heat conducting rod 17 to heat the energy storage unit 14, so that the Mg(OH) in the thermochemical energy storage module 13 2 It decomposes into MgO and water vapor at a temperature above 350°C. The dried MgO is ready for use. The water vapor generated by the reaction is discharged through the exhaust valve 16. The decomposed MgO powder is dried (water content < 0.5%) and stored in the energy storage module 13 in a loose and porous state to provide highly active reactants for the hydration reaction in the subsequent energy release stage. The distributed heating structure of the heat conducting rod 17 ensures that Mg(OH) 2 The temperature uniformity of the decomposition reaction (temperature difference ≤ ±5°C) improves the energy conversion efficiency and material utilization rate in the energy storage stage.
[0032] Energy release stage: In the initial stage, the water in the water tank 5 is heated to 150 °C by the resistance heating element 4 to generate steam. The steam enters the energy storage unit 14 through the steam ejector device 11 to trigger the MgO hydration reaction, and the initial steam pressure is controlled at 0.8 MPa. After the reaction enters a steady state, the resistance heating element 4 is turned off. When the liquid water in the water tank 5 flows through the steam vaporization pipeline 3, it absorbs the chemical heat released by the MgO hydration reaction in the module and vaporizes into steam, realizing self-sustaining steam supply. The heat released by the reaction raises the internal temperature of the outer shell 13 above 300 °C. The steam ejector device 11 adjusts the volume ratio of high-pressure steam (from the outlet of the preheater 7) to low-pressure steam (from the water tank 5) in real time through model predictive control (1:3 to 1:5) to maintain the pressure at 0.5 - 1.2 MPa. The heat transfer medium in the heat exchange buried pipe 15 outputs the reaction heat to external heat-using equipment. At the same time, the preheater 7 preheats the initial temperature of the medium from 20 °C to 80 °C, realizing cascade utilization of waste heat.
[0033] As an alternative, the outlet end of the heat transfer medium storage tank 8 is connected to the low-temperature side inlet of the preheater 7, the low-temperature side outlet of the preheater 7 is connected to the inlet end of the heat exchange buried pipe 15, the high-temperature side inlet of the preheater 7 is connected to the second gas outlet of the water tank 5, and the high-temperature side outlet of the preheater 7 is connected to the pressure pump 10. The heat exchange system includes the preheater 7 and the heat transfer medium storage tank 8.
[0034] The working principle of the heat exchange system is as follows: The low-temperature heat transfer medium in the heat transfer medium storage tank 8 enters from the low-temperature side inlet of the preheater 7. At the same time, the high-temperature medium (such as water or steam) in the water tank 5 enters from the high-temperature side inlet of the preheater 7. The two exchange heat through the heat exchange surface in the preheater 7. The high-temperature medium transfers heat to the low-temperature heat transfer medium to raise its temperature. The cooled high-temperature medium flows out from the high-temperature side outlet of the preheater 7 and enters the pressure pump 10 (screw pump), while the preheated heat transfer medium flows out from the low-temperature side outlet of the preheater 7 and is transported to the serpentine heat exchange buried pipe 15. Heat exchange is carried out with the energy storage medium (such as Mg(OH) 2 / MgO) in the energy storage unit 14 to store or release heat, thus completing the heat transfer and utilization process of the entire heat exchange system. This system uses the serpentine heat exchange buried pipe 15 to recover the reaction heat and simultaneously implements cascade waste heat recovery through the preheater 7.
[0035] For the traditional fixed reactor, capacity increase requires the overall replacement of the reaction vessel. It cannot be flexibly expanded through module parallel connection and is difficult to adapt to the modular layout requirements of the solar thermal power station.
[0036] Based on the above problems, in the embodiments of the present invention, there are multiple energy storage units 14, and the multiple energy storage units 14 can be detachably connected in parallel. The thermochemical energy storage module 13 adopts a detachable reactor design with a standardized interface, supports parallel expansion of multiple units, and can meet different-scale energy storage requirements.
[0037] Optionally, an exhaust valve 16 is provided at the upper part of the outer shell 13, and a blowdown valve 21 is provided at the bottom of the outer shell 13. Thermocouples 20 are evenly distributed in the energy storage unit 14. A condensation pipeline 31 is also connected between the outer shell 13 and the water tank 5. The exhaust valve 16 at the top of the module and the blowdown valve 21 at the bottom are respectively used to discharge the gas generated by the reaction and clean the residue, ensuring a stable reaction environment. The thermocouples 20 are evenly arranged axially and radially in the energy storage unit 14 to monitor the reaction temperature field in real time, providing data support for system regulation, so as to ensure the efficient and stable operation of the module.
[0038] Reference Figure 2 , Figure 2 is a schematic structural diagram of the steam ejector device provided by an embodiment of the present invention. As Figure 2 shown, the steam ejector device 11 further includes a contraction chamber 26 connected to the mixing chamber 27. The ejector channel 24 is connected to a throat structure 25, and both the throat structure 25 and the main flow channel 23 are connected to the contraction chamber 26. It should be noted that laser engraved micro-groove structures (width 50 μm, depth 200 μm) are provided on the inner walls of the flow channels of the contraction chamber 26, mixing chamber 27, and diffuser chamber 29 in the steam ejector device 11, and the steam shear force is used to realize the directional discharge of particulate matter. A pulse backblower 28 is provided on the diffuser chamber 29, and a high-pressure nitrogen pulse (pressure 8-10 MPa) is started for 0.1 second every 30 minutes to remove the attachments. The steam ejector device 11 adopts model predictive control, predicts and regulates the steam entrainment ratio based on real-time data, realizes a second-level dynamic response, and makes the mixing efficiency volatility < ±2%.
[0039] The high-pressure side inlet of the steam ejector device 11 is connected to a pressure pump 10. In this embodiment, a screw pump is selected. The low-pressure side inlet is communicated with the gas phase outlet of the water tank 5, and the outlet end is connected to the bottom of the outer shell 13; When the steam ejector device 11 is working, the high-pressure steam (pressure 1.5 MPa - 2.0 MPa) transported by the screw pump enters the steam ejector device 11 through the ejector flow channel 24. When passing through the throat structure 25, the pressure energy is converted into kinetic energy to form a high-speed jet, creating a low-pressure environment in the contraction chamber 26 area. Then, the gas-phase fluid (pressure 0.8 MPa) at the first air outlet of the water tank 5 is ejected and enters the steam ejector device 11 through the main flow channel 23. The two fluids are fully mixed in the mixing chamber 27 and a local vacuum (pressure < 0.3 MPa) is formed in the mixing chamber 27 for energy exchange. The kinetic energy of the high-pressure steam is transferred to the ejected gas-phase fluid. Subsequently, the mixed fluid enters the diffuser chamber 29. Since the flow cross-sectional area of the diffuser chamber 29 gradually increases, the flow velocity decreases, and the kinetic energy is converted into pressure energy to increase the pressure. Finally, it is discharged from the outlet end and transported to the bottom of the outer shell 13, providing power and medium conditions for the subsequent energy storage reaction. It actively sucks in low-pressure steam using the pressure difference and realizes mixing through kinetic energy conversion. There are no moving parts throughout the process, avoiding problems such as seal failure, component deformation, or control lag caused by high temperature in traditional power transmission equipment. The structural material of the steam ejector device 11 is selected as high-temperature resistant alloy steel (such as Inconel 625), which can operate stably for a long time above 350°C and withstand the extreme working conditions released by the thermochemical energy storage module.
[0040] Specifically, the steam ejector device 11 adopted in the present invention effectively solves the problem of steam parameter regulation under medium and high temperature conditions (> 300°C) through the coordination of a fluid structure design without moving parts and model predictive control technology. The supporting model predictive control system predicts the future state of the system based on the steam pressure, temperature, flow rate and other parameters monitored in real time, and adjusts the volume ratio of high-pressure steam and low-pressure steam in advance, maintaining the volume ratio of high and low-pressure steam dynamically at 1:3 - 1:5 to ensure that the pressure of the mixed steam is stable at 0.5 - 1.2 MPa (fluctuation range < ±3%).
[0041] The above are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.
Claims
1. A thermochemical energy storage system, characterized in that: include: A thermochemical energy storage module comprises a housing (13) and an energy storage unit (14) fixed therein, wherein the energy storage unit (14) is filled with a solid energy storage medium, the bottom of the energy storage unit (14) is provided with an air inlet, a heat exchange buried pipe (15) and a steam vaporization pipeline (3) are fixed in the energy storage unit (14), the inlet end of the heat exchange buried pipe (15) is connected to a heat transfer medium storage tank (8), and the outlet end is connected to an external heat-using device, both ends of the steam vaporization pipeline (3) are connected to a water tank (5) to form a circulation pipeline, the steam vaporization pipeline (3) is provided with an air outlet, and the energy storage unit (14) and the water tank (5) are connected to a solar heating unit; The steam ejection device (11) comprises a mixing chamber (27) and a diffusion chamber (29) which are connected as one body, the mixing chamber (27) being connected to a main flow channel (23) and an ejection channel (24) respectively, the first air outlet of the water tank (5) being connected to the main flow channel (23), the second air outlet of the water tank (5) being connected to a pressure pump (10) and then to the ejection channel (24), and the outlet of the diffusion chamber (29) being connected to the bottom of the energy storage unit (14) so that steam can enter through the air inlet.
2. The thermochemical energy storage system according to claim 1, characterized in that: The outlet end of the steam vaporization pipe (3) is arranged on the lower side wall of the energy storage unit (14) in a manner inclined downward.
3. The thermochemical energy storage system according to claim 2, characterized in that: The inclination angle of the outlet end of the steam vaporization pipeline (3) is 5°-10°, and the aperture of the air outlet hole of the steam vaporization pipeline (3) is 50 μm-200 μm.
4. The thermochemical energy storage system according to claim 2, characterized in that: The outlet of the mixing chamber (27) is connected to the bottom of the shell (13) via a steam pipeline, and the steam pipeline has a plurality of branches evenly distributed inside the shell (13). A redistribution plate (22) is connected below the energy storage unit (14), and the redistribution plate (22) is located above the branches. The redistribution plate (22) has micropores, and the pore diameter of the micropores is 1 mm-3 mm.
5. The thermochemical energy storage system according to claim 1, characterized in that: The buried heat exchange pipe (15) is arranged in a serpentine shape in the energy storage unit (14) and covers the entire longitudinal space of the energy storage unit (14); the inlet and outlet of the buried heat exchange pipe (15) both extend out of the top of the outer shell (13); the steam vaporization pipe (3) is in a three-section bent shape, wherein the middle section is close to the side wall of the energy storage unit (14).
6. The thermochemical energy storage system according to claim 1, characterized in that: The solar heating unit comprises a photovoltaic power generation device (1), a resistance heating element (4) and a heat conducting rod (17); the resistance heating element (4) is connected to the inside of a water tank (5); the heat conducting rod (17) is connected to the inside of an energy storage unit (14); and both the resistance heating element (4) and the heat conducting rod (17) are connected to the photovoltaic power generation device (1).
7. The thermochemical energy storage system according to claim 6, characterized in that: The outlet end of the heat transfer medium storage tank (8) is connected to the low-temperature side inlet of the preheater (7), the low-temperature side outlet of the preheater (7) is connected to the inlet end of the heat exchange buried pipe (15), the high-temperature side inlet of the preheater (7) is connected to the second air outlet of the water tank (5), and the high-temperature side outlet of the preheater (7) is connected to the pressure pump (10).
8. The thermochemical energy storage system according to claim 1, characterized in that: There are a plurality of energy storage units (14), and the plurality of energy storage units (14) are detachable and connected in parallel.
9. The thermochemical energy storage system according to claim 1, characterized in that: An exhaust valve (16) is provided on the upper portion of the shell (13), a sewage valve (21) is provided on the bottom portion of the shell (13), thermocouples (20) are evenly distributed in the energy storage unit (14), and a condensation pipeline (31) is connected between the shell (13) and the water tank (5).
10. A thermochemical energy storage system according to claim 1, characterized in that: The steam ejection device (11) further comprises a contraction chamber (26) connected to the mixing chamber (27); the ejection channel (24) is connected to a throat structure (25); and the throat structure (25) and the main flow channel (23) are both connected to the contraction chamber (26).