Gravity-driven chemical heat storage reactor with upper wave type flow channel

Abstract

The invention discloses a gravity-driven upper wave type flow channel chemical heat storage reactor, which comprises a filler box, a discharge box and an upper wave type flow channel, the upper wave type flow channel comprises a plurality of sections of reaction flow channels, each section of reaction flow channel is provided with openings at two ends, is hollow inside and is used for accommodating a heat storage medium, the upper surface of each section of reaction flow channel is wave-shaped, and the lower surface of each section of reaction flow channel is straight; the adjacent reaction flow channels are connected through variable-angle corrugated compensation elbows; an air outlet and a feeding port are formed in the top of the upper wave type flow channel, the feeding port is connected with a discharging port of the stuffing box through a stuffing pipe, an air supply port and a discharging port are formed in the bottom of the upper wave type flow channel, and the discharging port is connected with a feeding port of the discharging box through a discharging pipe. Under the same reactor size, the heat exchange capacity is higher, the reaction rate of reactants is improved, the large reaction conversion rate is achieved, and the energy storage power and the energy storage density are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage equipment, and in particular relates to a gravity-driven upper wave-type flow channel chemical heat storage reactor. Background Art

[0002] At present, in the field of heat storage, there are three common technical routes according to different heat storage principles, namely sensible heat storage, latent heat storage and chemical heat storage. Among them, chemical heat storage technology has the largest theoretical heat storage density, the most cutting-edge technology and broad application prospects. Heat storage reactors are necessary devices for chemical heat storage technology, and there are three forms: fluidized bed reactors, fixed bed reactors and moving bed reactors. Among them, the moving bed reactor does not need to use a large air volume like the fluidized bed reactor to blow the energy storage material (usually particles) into a suspended state, so it can maintain low energy consumption while avoiding the problems of energy storage "dead zone" and slow heat transfer that are prone to occur in fixed bed reactors due to particle accumulation and uneven heat exchange, and can realize continuous loading and unloading of materials to ensure a relatively smooth output and input power of the entire energy storage / release process. Therefore, the moving bed reactor takes into account the advantages of both fixed bed and fluidized bed reactors and is an emerging reactor form.

[0003] In the field of moving bed reactors, such as the literature (Cosquillo Mejia, A., Afflerbach, S., Linder, M., Schmidt, M. Development of a Moving Bed Reactor for Thermochemical Heat Storage Based on Granulated Ca(OH)2. Processes 2022, 10, 1680) and the literature (Wan, Q.; Zhao, Z.; Wang, R.; Tang, M.; Wang, D.; Zhang, S.; Hu, B. Characteristics of Gas–Solid Flow in an Intermittent Countercurrent Moving Bed. Processes 2022,10,2116.) The moving bed reactor reported by this type has a vertical straight-through structure. The gas flows from the bottom to the top. The solid energy storage medium (such as particles) falls rapidly from the top under the action of gravity and then accumulates at the bottom of the bed. At this time, the state is no different from that of a fixed bed. The heat exchange between the particles and the gas is hindered, the heat transfer is uneven, and the thermochemical reaction and the heat storage / release rate are slowed down. For this type of reactor, in order to achieve a higher reaction conversion rate and heat storage density, as well as a faster thermochemical reaction rate, it is generally necessary to significantly increase the particle reaction time and increase the height of the reactor so that the particles can stay in the air long enough when falling from top to bottom so that the particles can fully react. However, this results in a larger reactor size, poorer economy, and higher space requirements.

[0004] The shell and tube moving bed reactor reported in the literature (AC Mejía, Afflerbach S, Linder M, et al. Experimental analysis of encapsulated CaO / Ca(OH)2 granules as thermochemical storage in a novel moving bed reactor[J]. Applied Thermal Engineering, 2020, 169: 114961.) has a cylindrical bed structure. The solid energy storage medium (such as particles) in the bed will fall rapidly under the action of gravity when storing / releasing heat, and an indirect heating method is adopted. The solid particles in the bed are not in direct contact with the fluid heat medium. There is a lack of convective heat exchange inside the bed, and heat exchange mainly relies on the wall surface and the heating fluid. Heat is transferred from the outside to the inside, and there are problems such as weak heat diffusion capacity, uneven heat exchange, slow thermochemical reaction rate, and difficulty in matching the particle unloading rate with the reaction conversion rate.

[0005] The literature (Schrader AJ, Bush HE, Ranjan D, Loutzenhiser P G. Aluminum-doped calcium manganite particles for solar thermochemical energy storage: Reactor design, particle characterization, and heat and mass transfer modeling [J]. International Journal of Heat and Mass Transfer, 2020, 152: 119461.) reports a sloped moving bed reactor for chemical heat storage. Compared with the "vertical straight-through structure" moving bed reactor, this reactor increases the residence time of particles in the reaction channel to a certain extent and improves the reaction conversion rate, but the channel has not undergone heat transfer enhancement design, and there are problems such as limited convective heat exchange intensity between particles and gas and slow reaction rate.

[0006] In view of the problems of existing chemical heat storage moving bed reactors, such as weak convective heat transfer intensity, slow reaction rate, large reactor structure size and lack of compactness, it is urgent to develop a reaction device with a new structure to solve the above problems. Summary of the invention

[0007] Technical problems solved: In response to the above technical problems, the present invention provides a gravity-driven upper wave flow channel chemical heat storage reactor with a more compact structure. The difficulty of gas movement transmission is reduced by designing the flow channel. At the same time, the upper wave component is designed to greatly increase the airflow disturbance in the reactor flow channel, enhance the convective heat exchange between particles and gas heat medium, increase the reaction rate of reactants, and improve the efficiency and energy storage density of the moving bed energy storage reactor.

[0008] Technical solution: A gravity-driven upper wave flow channel chemical heat storage reactor, comprising a stuffing box, a discharge box and an upper wave flow channel, wherein the upper wave flow channel comprises several sections of reaction flow channels, each section of the reaction flow channel is open at both ends and hollow inside, and is used to accommodate heat storage medium, wherein the upper surface is wave-shaped and the lower surface is straight, and adjacent reaction flow channels are connected by variable-angle corrugated compensation elbows; an air outlet and a feed port are provided at the top of the upper wave flow channel, and the feed port is connected to the discharge port of the stuffing box through a stuffing pipe, an air supply port and a discharge port are provided at the bottom, and the discharge port is connected to the feed port of the discharge box through a discharge pipe.

[0009] Preferably, the wavy upper surface of the reaction channel is composed of a plurality of connected positive and negative arc walls with the same curvature, the connection points of the positive and negative arc walls are on the same straight line, and the vertical distance between the center points of the positive and negative arc walls and the straight line is not less than 5 mm, and the vertical distance between the center point of the negative arc wall and the lower surface of the channel is 10 to 20 times the particle size of the heat storage medium.

[0010] Preferably, the angle between the filling tube and the upper wave-like flow channel is 100° to 160°.

[0011] Preferably, the angle between the discharge pipe and the upper wave-like flow channel is greater than 90° and less than 180°.

[0012] Preferably, the angle between the variable-angle corrugated compensating elbow and the horizontal plane is 0 to 30°.

[0013] Preferably, a pull-out material box is provided in the discharge box and an observation window is provided on the side.

[0014] Preferably, the air supply port and the air outlet are both provided with filters.

[0015] Preferably, valves are provided on both the filling pipe and the discharge pipe.

[0016] Preferably, the reactor further comprises a slide rail bracket for fixing and adjusting the angle of the reaction channel.

[0017] Preferably, the reactor also includes a gas treatment system, which includes an air supply channel, an air outlet channel, a return air channel and a combined gas treatment unit, wherein the combined gas treatment unit is arranged on the air supply channel; the inlet of the air supply channel is connected to the gas or gaseous reactant required for heat storage or heat release, and the outlet is connected to the air supply port of the upper wave-like flow channel; the inlet of the air outlet channel is connected to the air outlet of the upper wave-like flow channel, and the outlet is connected to the outside world or the energy demand end; the inlet of the return air channel is connected to the air outlet of the upper wave-like flow channel, and the outlet is connected to the combined gas treatment unit.

[0018] Beneficial effects: Compared with the prior art, the present invention can have a stronger heat exchange capacity under the same reactor size, improve the reaction rate of the reactants, achieve a higher reaction conversion rate, and improve the energy storage power and energy storage density. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the present invention;

[0020] Figure 2 It is a detailed view of the wavy flow channel of the present invention;

[0021] Figure 3 It is a detailed view of the discharge box of the present invention;

[0022] Figure 4It is a smooth flow channel heat storage reactor;

[0023] Figure 5 It is an inclined plate type heat storage reactor;

[0024] Figure 6 It is a schematic diagram of the grid used for simulating the heat storage performance of the three reactors;

[0025] Figure 7 is the hourly convective heat transfer coefficient in the three reactors;

[0026] Figure 8 is the hourly reaction rate in the three reactors;

[0027] Fig. 9 is the hourly heat storage power in the three reactors;

[0028] Fig.10 is the total effective heat storage in the three reactors at each hour;

[0029] Fig.11 is the final heat storage density in the three reactors;

[0030] The numbers in the figure represent the following: 1. Stuffing box; 2. Discharge box; 21. Observation window; 22. Pull-out material box; 3. Upper wave-type flow channel; 4. Variable-angle corrugated compensation elbow; 5. Air outlet; 6. Stuffing pipe; 7. Air supply port; 8. Discharge pipe; 9. Slide rail bracket; 10. Gas treatment system; 101. Air supply channel; 102. Air outlet channel; 103. Return air channel; 104. Combined gas treatment unit; 105. Power unit. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] like Figure 1As shown, a gravity-driven chemical heat storage reactor with an upper wave-type flow channel 3 includes components such as a stuffing box 1, a discharge box 2, an upper wave-type flow channel 3, a gas treatment system 10, and a slide rail bracket 9. The upper wave-type flow channel 3 is the reactor body, including a plurality of reaction flow channels, each of which is open at both ends and hollow inside, and is used to accommodate heat storage media. Its upper surface is wave-shaped and its lower surface is straight. Adjacent reaction flow channels are connected by variable-angle corrugated compensation elbows 4; an air outlet 5 and a feed port are provided at the top of the upper wave-type flow channel 3, and the feed port is connected to the discharge port of the stuffing box 1 through a stuffing pipe 6, and an air supply port 7 and a discharge port are provided at the bottom, and the discharge port is connected to the feed port of the discharge box 2 through a discharge pipe 8. The gas processing system 10 includes an air supply channel 101, an air outlet channel 102, a return air channel 103 and a combined gas processing unit 104, wherein the combined gas processing unit 104 is arranged on the air supply channel 101; the inlet of the air supply channel 101 is connected to the gas or gaseous reactant required for heat storage or heat release, and the outlet is connected to the air supply port 7 of the upper wave-type flow channel 3; the inlet of the air outlet channel 102 is connected to the air outlet 5 of the upper wave-type flow channel 3, and the outlet is connected to the outside world or the energy demand end; the inlet of the return air channel 103 is connected to the air outlet 5 of the upper wave-type flow channel 3, and the outlet is connected to the combined gas processing unit 104. The slide rail bracket 9 is placed vertically on the ground to fix and adjust the angle of the reaction flow channel.

[0034] The upper wave-shaped flow channel 3 and the variable angle corrugated compensation elbow 4 are both made of high temperature resistant materials, and the joints are airtight. The outer surface of each component of the reactor is provided with an insulation layer, the thermal conductivity of the insulation layer is less than 0.055W / (mK), and the insulation standard meets the requirements of relevant national standards.

[0035] The included angle between the filling pipe 6 and the upper wave-like flow channel 3 is 100° to 160°.

[0036] The angle between the discharge pipe 8 and the upper wave-like flow channel 3 is greater than 90° and less than 180°.

[0037] The included angle between the variable angle corrugated compensating elbow 4 and the horizontal plane is 0-30°, and the included angle is appropriately adjusted according to the flow conditions of the heat storage particles.

[0038] The air supply port 7 and the air outlet 5 are both provided with filters, which can effectively prevent the heat storage particles from leaking into the air duct.

[0039] The filling pipe 6 and the discharge pipe 8 are both provided with valves for controlling the filling and discharge speeds respectively.

[0040] like Figure 2As shown, the wavy upper surface of the reaction channel is composed of a plurality of connected positive and negative arc walls with the same curvature, the connection points of the positive and negative arc walls are on the same straight line, and the vertical distance between the center point of the positive and negative arc walls and the straight line is not less than 5mm, and the vertical distance between the center point of the negative arc wall and the lower surface of the channel is 10 to 20 times the particle size of the heat storage medium. Figure 3 As shown, a drawable material box 22 is provided in the discharge box 2, and an observation window 21 is provided on the side.

[0041] In the reactor, the energy storage medium (usually particles) enters the filling pipe 6 from the filling box 1, and then enters the top of the upper wave-like flow channel 3, and flows from top to bottom in the upper wave-like flow channel 3 under the action of gravity. The gas enters from the air supply port 7, flows from bottom to top in the upper wave-like flow channel 3, and forms a countercurrent heat exchange with the particles.

[0042] The gas introduced into the reactor is preferably stable in physical and chemical properties and does not affect the main reactions involved in the thermochemical energy storage. Taking the thermal decomposition heat storage reaction of calcium hydroxide as an example, calcium hydroxide is dehydrated by heat to generate calcium oxide and water vapor, and the heat obtained is stored in chemical bonds (the principle is shown in formula (1)). Therefore, the gas introduced into the reactor cannot contain a large amount of carbon dioxide or other components that are easy to react chemically with calcium oxide. Nitrogen or air after carbon removal by the gas treatment system 10 is preferably used.

[0043]

[0044] The reacted gas is discharged through the air outlet 5, and according to actual needs, it flows to the outside or is transported to the energy demand end through the air outlet channel 102, or is connected to the combined gas processing unit 104 through the return air channel 103; the gas or gaseous reactant required for heat storage or heat release passes through the air supply channel 101 under the drive of the power device 105 (such as a fan, a compressor, etc.), is processed by the combined gas processing unit 104, and is sent to the upper wave-shaped flow channel 3 from the air supply port 7. The air supply channel 101, the air outlet channel 102 and the return air channel 103 are all provided with air duct valves, which can be flexibly opened and closed according to different working conditions to achieve the purpose of energy saving and improving heat storage efficiency. The combined gas processing unit 104 includes but is not limited to flow, temperature and humidity control devices, heating devices and other necessary gas production or purification devices (such as pipeline heaters, carbon removal and dehumidification devices).

[0045] More specifically, taking the classic calcium hydroxide / calcium oxide particle heat storage reaction in the field of chemical heat storage as an example (the principle is shown in formula (1)), there is a batch of calcium hydroxide particles with an average diameter of 2 mm. When using the reactor of the present invention to store energy, first adjust the slide rail bracket 9 to make the reaction flow channel at a suitable inclination angle, then open the air duct valves of the air supply channel 101 and the return air channel 103, the valve of the discharge pipe 8, the power device 105, and the combined gas treatment unit 104, keep the valve of the filling pipe 6 and the air duct valve of the air outlet channel 102 closed, and introduce decarbonized air with a temperature of 380°C into the upper wave flow channel 3 to preheat the upper wave flow channel 3. In this example, the wavy upper surface of the upper wavy flow channel 3 reaction flow channel is composed of positive and negative arc walls with the same curvature. The connection points of the positive and negative arc walls are on the same straight line, and the vertical distance between the center point of the positive and negative arc walls and the straight line is 10 mm, and the vertical distance between the center point of the negative arc wall and the lower surface of the flow channel is 20 mm, which is 10 times the particle size, that is, the maximum height of the flow channel h max The minimum height h is 40 mm. min The distance between the center points of the positive and negative arc walls is h s is 20mm, characteristic height h e The angle θ between each section of the reaction channel and the horizontal plane is 10°, and the total length is about 6.3m. After preheating, the air temperature is increased to 650°C, and the valve of the filling pipe 6 is opened to control the calcium hydroxide particles to enter the upper wave-like flow channel 3. Depending on the flow of the calcium hydroxide particles, the slide rail bracket 9 is adjusted to increase or decrease θ; the discharge box 2 is observed through the observation window 21. After the discharge box 2 is basically filled, the power device 105, the air supply channel 101, and the discharge pipe 8 are temporarily closed, and the drawable material box 22 is extracted. After unloading and emptying, the drawable material box 22 is loaded into the discharge box 2, and then the discharge pipe 8, the air supply channel 101, and the power device 105 are opened in turn to continue the aforementioned cycle.

[0046] The present invention is combined with a smooth flow channel heat storage reactor ( Figure 4 ), Inclined Plate Heat Storage Reactor ( Figure 5 ) to simulate and compare the heat storage performance of the present invention, proving the advantages of the present invention. The simulation software is MFiX. Considering the complexity of the model, a quasi-3D CFD-DEM model is used, that is, the height and width directions are the original size, and the depth direction is 10mm as the research object ( Figure 6 The working conditions are as follows: Ca(OH)2 heat storage particles enter from the top of the three reactors, the initial particle temperature is 380°C, and the loading flow rate is 3.54 kg / h; high-temperature carbon removal air enters from the air supply port 7 at the bottom of the reactor, and the air supply port area is 0.0005 m 2 , temperature is 650℃, flow rate is 2.1kg / h, heat exchange with particles is countercurrent, working time is 60s.

[0047] The average convection heat transfer coefficient in the reactor is selected as an indicator for evaluating the heat transfer capacity of the reactor; the average reaction rate of the particles in the reactor is selected as an indicator for evaluating the reaction capacity of the reactor; and the reactor heat storage power, effective heat storage and heat storage density are selected as evaluation indicators. Among them, effective heat storage and heat storage density refer to the heat stored in the particles falling into the particle slot and the corresponding heat storage density.

[0048] Figure 7 This reflects that the convective heat transfer coefficient of the present invention is much greater than that of the other two reactors. The convective heat transfer coefficient of the present invention is 1.48 times that of the smooth channel heat storage reactor and 1.81 times that of the inclined plate heat storage reactor.

[0049] Figure 8 This shows that the reaction rate of the present invention is much higher than that of the other two reactors. The reaction rate of the present invention is 4.83 times that of the smooth channel heat storage reactor and 15.38 times that of the inclined plate heat storage reactor.

[0050] Fig. 9 This reflects that the heat storage power of the present invention is much greater than that of the other two reactors. The heat storage power of the present invention is 10 times that of the smooth channel heat storage reactor and 20 times that of the inclined plate heat storage reactor.

[0051] Fig.10 This reflects that the effective heat storage capacity of the present invention is much greater than that of the other two reactors. The effective heat storage capacity of the present invention is 7.08 times that of the smooth flow channel heat storage reactor and 14.75 times that of the inclined plate heat storage reactor.

[0052] Fig.11 This reflects that the heat storage density of the present invention is much greater than that of the other two reactors. The heat storage density of the present invention is 28.46 times that of the smooth channel heat storage reactor and 58.88 times that of the inclined plate heat storage reactor.

[0053] For further explanation, Table 1 gives four cases of wave heat storage reactors of different sizes, and simulates their performance under the above heat storage conditions, and compares them with smooth flow channel heat storage reactors and inclined plate heat storage reactors.

[0054] Table 1. Performance comparison of wave thermal storage reactors of 4 different sizes:

[0055]

[0056] Table 1 shows that: Cases 1 and 3 meet the conditions specified in the present invention. Compared with conventional moving bed reactors, they significantly improve heat exchange capacity and reaction rate, and achieve greater energy storage power and energy storage density; while Case 2 does not meet the conditions specified in the present invention, and the performance improvement is not obvious; Case 3 does not meet the conditions specified in the present invention at all, and particles are blocked in the reactor flow channel, resulting in the attenuation of the reactor's effective heat storage and heat storage density performance.

Claims

1. A gravity-driven upper wave flow channel (3) chemical heat storage reactor, characterized in that: The invention comprises a stuffing box (1), a discharge box (2) and an upper wavy flow channel (3), wherein the upper wavy flow channel (3) comprises a plurality of reaction flow channels, each of which is open at both ends and hollow inside, and is used to accommodate a heat storage medium, wherein the upper surface is wavy and the lower surface is straight, and adjacent reaction flow channels are connected via variable-angle corrugated compensation elbows (4); an air outlet (5) and a feed port are provided at the top of the upper wavy flow channel (3), and the feed port is connected to the discharge port of the stuffing box (1) via a stuffing pipe (6); an air supply port (7) and a discharge port are provided at the bottom, and the discharge port is connected to the feed port of the discharge box (2) via a discharge pipe (8).

2. A gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The wavy upper surface of the reaction channel is composed of a plurality of connected positive and negative arc walls with the same curvature, the connection points of the positive and negative arc walls are on the same straight line, and the vertical distance between the center points of the positive and negative arc walls and the straight line is not less than 5 mm, and the vertical distance between the center point of the negative arc wall and the lower surface of the channel is 10 to 20 times the particle size of the heat storage medium.

3. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The included angle between the filling tube (6) and the upper wave-shaped flow channel (3) is 100° to 160°.

4. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The angle between the discharge pipe (8) and the upper wave-shaped flow channel (3) is greater than 90° and less than 180°.

5. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The angle between the variable-angle corrugated compensating elbow (4) and the horizontal plane is 0-30°.

6. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The discharge box (2) is provided with a drawable material box (22) in the interior and an observation window (21) on the side.

7. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The air supply port (7) and the air outlet (5) are both provided with filter screens.

8. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The filling pipe (6) and the discharge pipe (8) are both provided with valves.

9. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The reactor also includes a slide rail support (9) for fixing and adjusting the angle of the reaction channel.

10. The gravity-driven upper wave-type flow channel (3) chemical heat storage reactor according to claim 1, characterized in that: The reactor further comprises a gas processing system (10), wherein the gas processing system (10) comprises an air supply channel (101), an air outlet channel (102), a return air channel (103) and a combined gas processing unit (104), wherein the combined gas processing unit (104) is arranged on the air supply channel (101); the inlet of the air supply channel (101) is connected to the gas or gaseous reactant required for heat storage or heat release, and the outlet is connected to the air supply port (7) of the upper wave-like flow channel (3); the inlet of the air outlet channel (102) is connected to the air outlet (5) of the upper wave-like flow channel (3), and the outlet is connected to the outside world or the energy demand end; the inlet of the return air channel (103) is connected to the air outlet (5) of the upper wave-like flow channel (3), and the outlet is connected to the combined gas processing unit (104).

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