Round connector solid oxide electrolytic cell geometric structure for improving electrolytic efficiency of synthesis gas

Abstract

The utility model relates to a geometric structure of a solid oxide electrolytic cell with circular connectors for improving the electrolytic efficiency of synthesis gas, which is characterized by comprising a first connector and a second connector which are oppositely arranged and are in a cover shape, and an interlayer positioned between the first connector and the second connector, a plurality of cylindrical connecting bodies are respectively arranged between the inner bottom surfaces of the first connecting body and the second connecting body and the interlayer in an array manner, and vertically crossed flow channels are formed among the cylindrical connecting bodies. The runner is reasonable in structural design, the transmission efficiency and the distribution uniformity of reaction gas are improved, and the working performance of the electrolytic cell is improved.

Description

Technical field:

[0002] The utility model relates to a circular connector solid oxide electrolytic cell geometric structure for improving synthesis gas electrolysis efficiency. Background technology:

[0004] The water electrolysis reaction in a solid oxide electrolyzer requires the introduction of H2O and CO2 at the cathode inlet for co-electrolysis. The flow channel of the electrolyzer is an important transmission channel for the reaction gas and reaction products, which directly affects the mass transfer efficiency and performance of the entire electrolyzer.

[0005] The flow channels of traditional solid oxide electrolyzers are all straight flow channels, and the common forms are parallel straight flow channels (such as Figure 1 As shown in (a), the parallel direct current channel is short, and H2O / CO2 does not have enough time to fully react to generate H2 / CO. The ribs of the parallel direct current channel are more concentrated, which is not conducive to the current distribution of co-electrolysis of H2O / CO2.

[0006] Currently, a Chinese patent "Method for Making a Solid Oxide Electrolyzer" with publication number CN101302631A has been retrieved. The corresponding metal oxide is deposited on a metal substrate, sintered, and naturally cooled to serve as the cathode, or the metal is directly used as the cathode; the solid oxide electrolyte powder is formed into a green billet by a casting method, sintered in an oxidizing atmosphere, and naturally cooled to obtain a dense solid electrolyte film, and then the anode activation layer and the anode contact layer are further deposited and sintered to form a semi-electrolyzer; the cathode and the solid oxide electrolyte in the semi-electrolyzer are brought into close contact to form a solid oxide electrolyzer. Although this patent avoids the loss of electrolyte and the possible corrosion problems, it does not disclose how to improve the flow channel structure of the electrolyzer to improve the transmission efficiency and distribution uniformity of the reaction gas and enhance the working performance of the electrolyzer.

[0007] Currently, a Chinese patent application titled "A 3D Flow Field Plate for a Fuel Cell" with publication number CN220272517U has been retrieved. The patent comprises a flow field plate having a flow field provided in the middle thereof. The flow field is used to provide a flow field for reactants and products, and to a certain extent determines the mass transfer capacity within the fuel cell, affecting the electrochemical reaction rate and, in turn, the electrochemical performance of the cell. The flow field plate is provided with a flow guide mechanism in the flow field. The flow guide mechanism is used to guide gas flow. The flow guide mechanism comprises a plurality of lands, each of which comprises two curved plates. The curved plates are used to divide the flow field into a plurality of secondary flow channels. The secondary flow channels function to transport gas and play an important role in mass transfer within the fuel cell. Although the patent enhances convective mass transfer through the multi-directional turbulence effect of the 3D opposed sinusoidal wave structure, forms a periodically varying pressure distribution within the flow channel, increases the pressure gradient between the flow channel and the gas diffusion layer and the concentration gradient of the reactant gas, promotes the diffusion of the reactant gas to the electrode surface, and accelerates the electrochemical reaction, it does not disclose how to improve the flow channel structure of the electrolyzer to improve the transmission efficiency and distribution uniformity of the reactant gas and improve the working performance of the electrolyzer. Summary of the invention:

[0009] In view of the above-mentioned problems, the purpose of the present invention is to propose a circular connector solid oxide electrolytic cell geometric structure that improves the efficiency of synthesis gas electrolysis. The flow channel structure is reasonably designed, which is conducive to improving the transmission efficiency and distribution uniformity of the reaction gas and improving the working performance of the electrolytic cell.

[0010] The utility model is implemented by the following scheme:

[0011] The utility model provides a geometric structure of a circular connector solid oxide electrolysis cell for improving the efficiency of synthesis gas electrolysis, characterized in that it includes a first connector and a second connector in the shape of a cover arranged opposite to each other, and a partition located between the first connector and the second connector, and a plurality of cylindrical connectors are arrayed between the inner bottom surfaces of the first connector and the second connector and the partition, forming vertically intersecting flow channels between the cylindrical connectors.

[0012] Preferably, 1-72 cylindrical connectors are arranged in the first connector and the second connector, and the diameter of the cylindrical connector is 4 mm.

[0013] Preferably, the first connector and the second connector are made of stainless steel.

[0014] Preferably, the separator includes a cathode support layer, a cathode functional layer, an electrolyte layer, an anode functional layer and an anode current collecting layer in sequence.

[0015] Preferably, a fuel electrode flow channel is formed between the first connector and the spacer for passing H2O / CO2, an air electrode flow channel is formed between the second connector and the spacer for passing air, and a voltage of 1.4 V is loaded between the first connector and the second connector.

[0016] The working method of the circular connector solid oxide electrolysis cell geometric structure for improving the efficiency of synthesis gas electrolysis of the present invention is characterized in that: the circular connector solid oxide electrolysis cell geometric structure for improving the efficiency of synthesis gas electrolysis includes a first connector and a second connector in a cover shape that are relatively arranged, and a partition located between the first connector and the second connector, a plurality of cylindrical connectors are arrayed between the inner bottom surfaces of the first connector and the second connector and the partition, and vertical cross flow channels are formed between the cylindrical connectors; one end between the first connector and the second connector and the partition serves as an air inlet, and the other end serves as an air outlet, H2O and CO2 are introduced into the air inlet between the first connector and the partition, and air is introduced into the air inlet between the second connector and the partition, and H2 and CO are output at the air outlet after electrolysis.

[0017] The utility model has a simple structure, is easy to process and has low cost. The utility model establishes a single cell model for H2O / CO2 co-electrolysis simulation research and uses COMSOL Multiphysics simulation software for multi-physics field coupling modeling. The results show that the geometric structure of the solid oxide electrolyzer of the utility model enhances the gas transmission performance inside the electrolyzer and improves the uniformity of gas distribution, so that the H2 production efficiency of the circular connector solid oxide electrolyzer is about 59.6% higher than that of the traditional direct current channel; the CO production efficiency is about 87.29% higher than that of the traditional direct current channel; the maximum electrolyte current density of the circular connector is about 11 A / m2 higher than that of the traditional direct current channel, and the maximum PEN temperature is about 0.5 K higher than that of the traditional direct current channel.

[0018] The utility model has a simple structure, is easy to process and has a low cost. The utility model is an improvement on the original traditional parallel direct current channel structure, realizing the coordinated work of the main channel (from the air inlet to the air outlet) and the branch channel (perpendicular to the air inlet to the air outlet). The main channel and the branch channel cross vertically, and the cross-sectional shape of the connector between the cross-flow channels is circular, so it is named a circular connector. The total inlet and outlet cross-sectional area of the circular connector electrolytic cell of the utility model is equal to the total inlet and outlet cross-sectional area of the traditional direct current channel, which is more conducive to comparing the changes in the flow channel form. Impact on the performance of the electrolyzer; the circular connector creates tortuosity and diversion in the original straight channel, thereby enhancing gas flow and diffusion; the elliptical connector in the middle part of the circular connector of the utility model plays the role of dispersing the current, making the current density of H2O / CO2 electrolysis more evenly distributed, increasing the effective reaction area of the electrode and improving the mass transfer efficiency; since the total length of the flow channel of the utility model is longer than that of the traditional straight channel, water vapor and carbon dioxide have more time to participate in the electrochemical reaction in the flow channel, thereby achieving more efficient synthesis gas efficiency and significant economic benefits.

[0019] The present invention is further described below in conjunction with the accompanying drawings; Description of the drawings:

[0021] Figure 1 This is a schematic diagram of the simulation domain of a solid oxide electrolyzer with a conventional straight channel and a circular connector;

[0022] Figure 2 It is a two-dimensional planar schematic diagram of the flow channel shape of a traditional straight flow channel and a circular connector solid oxide electrolyzer;

[0023] Figure 3 This is the schematic diagram of the electrolytic reaction in the electrolytic cell;

[0024] Figure 4 This is a schematic diagram comparing the H2 mass concentration of a conventional direct-flow solid oxide electrolyzer and a circular connector;

[0025] Figure 5 Schematic diagram comparing the surface integral of H2 mass concentration at the cathode inlet (z=0mm) and outlet (z=40mm) of a conventional direct-flow solid oxide electrolyzer and a circular connector.

[0026] Figure 6 This is a schematic diagram comparing the CO mass concentration of a traditional direct-flow solid oxide electrolyzer and a circular connector;

[0027] Figure 7 Schematic diagram comparing the surface integral of CO mass concentration at the cathode inlet (z=0 mm) and outlet (z=40 mm) of a conventional direct-flow solid oxide electrolyzer and a circular connector.

[0028] Figure 8 This is a schematic diagram comparing the CH4 mass concentration of a traditional direct-flow solid oxide electrolyzer and a circular connector;

[0029] Figure 9 This is a schematic diagram comparing the O2 mass concentration of a conventional direct-flow solid oxide electrolyzer and a circular connector anode;

[0030] Figure 10 This is a schematic diagram comparing the reaction rates of the WGSR (water gas shift reaction) in the solid oxide electrolyzer with a circular connector of the conventional flow channel and the present invention;

[0031] Figure 11 This is a schematic diagram comparing the DIR (internal reforming reaction) reaction rates of a solid oxide electrolyzer with a conventional flow channel and a circular connector of the present invention;

[0032] Figure 12 This is a schematic diagram comparing the temperatures of a conventional flow channel and a circular connector solid oxide electrolyzer PEN (positive electrode-electrolyte-negative electrode) of the present invention;

[0033] Figure 13 This is a schematic diagram comparing the temperature distribution of the electrolyte middle section (x=20 mm, y=-0.4175 mm) along the flow direction of the conventional flow channel and the circular connector solid oxide electrolytic cell of the present invention;

[0034] Figure 14 Schematic diagram comparing the electrolyte current density distribution along the flow direction of the circular connector solid oxide electrolytic cell of the conventional flow channel and the present invention;

[0035] Figure 15 It is a cross-sectional schematic diagram of the flow channel of the utility model;

[0036] Figure 16 is a front view of the first connector or the second connector;

[0037] Figure 17 It is a three-dimensional diagram of a square connector of a comparative example;

[0038] Figure 18 This is a front view of the flow channel of the square connector in the comparative example;

[0039] Figure 19 It is a three-dimensional diagram of a triangular connector of a comparative example;

[0040] Figure 20 This is the main view of the flow channel of the triangular connector of the comparative example;

[0041] In the previous figures, (a) is a conventional flow channel, and (b) is a flow channel of the present invention. Specific implementation method:

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] The circular connector solid oxide electrolysis cell geometric structure of the present invention improves the efficiency of synthesis gas electrolysis, including a first connector A1 and a second connector A2 in the shape of a cover arranged opposite to each other. The first connector and the second connector can be made of materials such as stainless steel.

[0045] An interlayer A3 is provided between the cover openings of the first connector and the second connector. The interlayer includes a cathode support layer, a cathode functional layer, an electrolyte layer, an anode functional layer and an anode current collecting layer in sequence.

[0046] A plurality of cylindrical connectors A4 are arranged in an array between the inner bottom surfaces of the first connector A1 and the second connector A2 and the partition layer A3, forming vertically intersecting flow channels between the cylindrical connectors.

[0047] 1-72 cylindrical connectors can be arranged in the first connector and the second connector, and the diameter of the cylindrical connector is 4 mm; the circular connectors in adjacent rows can be arranged at the same position, or the circular connectors in adjacent rows can be staggered.

[0048] Specifically, a fuel electrode flow channel is formed between the above-mentioned first connector and the spacer for passing H2O / CO2, an air electrode flow channel is formed between the second connector and the spacer for passing air, and a voltage of 1.4 V is loaded between the first connector and the second connector.

[0049] The utility model is an improvement on the parallel straight flow channel structure of the traditional solid oxide electrolyzer. By setting a diversion method in the flow channel, the gas reaction time is increased. The dispersed connector can make the current density distribution more uniform, promote the electrolytic H2O / CO2 reaction, and the utility model can improve the synthesis gas efficiency of the solid oxide fuel cell.

[0050] like Figure 2 As shown in FIG, the circular connector solid oxide electrolyzer of the utility model has three excellent properties compared with the traditional parallel direct current channel: (1) the efficiency of producing H2 by electrolyzing H2O is improved, and the hydrogen production efficiency of the circular connector electrolyzer is 59.6% higher than that of the traditional electrolyzer; (2) the efficiency of producing CO by electrolyzing CO2 is improved, and the hydrogen production efficiency of the circular connector electrolyzer is 87.29% higher than that of the traditional electrolyzer; (3) the electrolyte current density of the circular connector is more uniform than that of the traditional direct current channel electrolyzer, and the maximum value of the electrolyte current density of the circular connector is about 11 A / m higher than that of the traditional direct current channel 2 , and the electrolyte current density of the new structure is more uniform.

[0051] The circular connector design is mainly suitable for solid oxide electrolyzers, and is also applicable to low-temperature proton exchange membrane fuel cells and electrolyzers, high-temperature solid oxide cells and other fuel cells with any flow channel form. The length range of the fuel cell flow channel from inlet to outlet applicable to this utility model is 1-1000mm; the flow channel diameter range is 0.1-1.5mm, the diameter of the cylindrical connector is 4mm; the number of circular connectors in the flow channel is 1-72.

[0052] The circular connector is mainly suitable for high-temperature solid oxide electrolyzers, and is also applicable to high-temperature and low-temperature fuel cells (solid oxide fuel cells and proton exchange membrane fuel cells) and electrolyzers.

[0053] The battery flow channel can adopt 72 or more circular connectors in the structural layout, and the circular area can be larger or smaller. Multiple circular connectors increase the gas transmission path, and the battery performance is improved more significantly and more uniformly.

[0054] The present invention is described in detail below in conjunction with specific simulation results:

[0055] Comparison of existing simulation results: The geometric parameters of the circular connector electrolytic cell with a traditional parallel straight flow channel, a flow channel length of 40 mm, a flow channel height of 1 mm, and a flow channel width of 2 mm are shown in Table 1. The electrolytic cell simulation boundary conditions are: the electrolytic cell is tested at a temperature of T = 1073 K and an operating pressure of 1 atm, with a cathode inlet (20% H2, 40% H2O, 40% CO2) volume flow rate Vca = 100 sccm (standard cubic centimeter per minute, sccm) and an anode inlet (21% O2, 79% N2) volume flow rate Van = 20 sccm; the electrolysis voltage is 1.4 V. The circular connector of the utility model is simulated under the same working conditions.

[0056] like Figure 3 Shown is the schematic diagram of the electrolytic reaction in the electrolytic cell.

[0057] like Figure 4 As shown in Figure 2, the H2 mass concentration in the electrode and channel gradually increases along the fuel flow direction (-z direction), and the maximum H2 mass concentration at the cathode outlet of the traditional flow channel is 7.8×10-3 kg / m 3 The maximum H2 mass concentration at the circular connector outlet is 10×10-3 kg / m 3 .

[0058] Figure 5 The mass concentration distribution diagram of the two cross sections of the inlet and outlet of the traditional flow channel and circular connector electrolyzer, where each cross section is the surface integral of the mass concentration of H2 in kg / m 3; When x = 0 mm, hydrogen just enters the SOEC. In order to maintain the reducing atmosphere at the cathode, 20% H2 is introduced in advance; the hydrogen mass concentration at the cathode inlet of the traditional flow channel and the circular connector electrolyzer is 2.6608×10-7 kg / m 3 , 2.708×10-7 kg / m 3 ; The H2 mass concentration at the cathode outlet of the traditional flow channel and circular connector electrolyzer is 4.1526×10-7 kg / m 3 , 5.089×10-7 kg / m 3 ; It can be seen that at the cathode inlet volume flow rate Vca=100 sccm, the H2 production efficiency of the circular connector SOEC is 59.6% higher than that of the traditional flow channel.

[0059] like Figure 6 As shown in Figure 2, the CO mass concentration in the electrode and channel gradually increases along the fuel flow direction (-z direction), and the maximum CO mass concentration at the cathode outlet of the traditional flow channel is 0.0489 kg / m 3 The maximum CO mass concentration at the circular connector outlet is 0.0930 kg / m 3 .

[0060] Figure 7 The mass concentration distribution diagram of the inlet and outlet sections of the traditional flow channel and circular connector electrolyzer is shown in Figure 2. Each section is the surface integral of the mass concentration of CO in kg / m 3 The CO mass concentration at the cathode inlet of the traditional flow channel and circular connector electrolyzer is 1.0734×10-7 kg / m 3 , 1.696×10-7 kg / m 3 The CO mass concentration at the cathode outlet of the traditional flow channel and circular connector electrolyzer is 22.035×10-7 kg / m 3 , 40.955×10 -7 kg / m 3 ; It can be seen that at the cathode inlet volume flow rate Vca=100 sccm, the CO production efficiency of the circular connector SOEC is 87.29% higher than that of the traditional flow channel.

[0061] Under the DIR chemical reaction, CO and H2 react in reverse to form CH4 and H2O; Figure 8 Figure 3 shows the CH4 concentration distribution at the cathode of a SOEC cell with a conventional flow channel and a circular interconnector at a voltage of 1.4 V. Under the DIR reaction, the CH4 content is very low. However, it can be seen that the CH4 content under the cathode outlet rib of the circular interconnector SOEC is higher than that of the conventional flow channel.

[0062] Figure 9The O2 mass concentration distribution at the anode of SOEC under the downstream condition is shown. The maximum O2 mass concentration of the traditional flow channel is below the rib, and the maximum oxygen mass concentration is 0.236 kg / m 3 The maximum oxygen mass concentration of the circular connector SOEC is 0.338 kg / m 3 , the higher O2 mass concentration proves that the electrochemical reaction of the circular connector is more intense.

[0063] Figure 10 The reaction rate distribution of the WGSR electrolyzer with a traditional flow channel and a circular connector, where positive values represent the forward reaction and negative values represent the reverse reaction (i.e., CO2 and H2 react to produce CO and H2O). It can be seen that the reaction rates of the two electrolyzers WGSR (WGSR reaction: ) are inversely distributed, and the unit is mol / (m 3 ·s), at the cathode inlet, the reverse WGSR reaction rate is the highest, because there are a lot of CO2 and H2 at the cathode inlet, and the reactants are sufficient, which will cause the reverse WGSR reaction in the electrolyzer. Because the same initial gas composition is introduced into the two electrolyzers at the cathode inlet, the WGSR reverse reaction rate at the cathode inlet is almost the same; as the reaction gas goes deeper along the flow channel (-z direction), the WGSR reverse reaction rate gradually decreases; although the H2 content gradually increases, the CO2 content gradually decreases, and the reduction of reactants will reduce the reverse WGSR reaction rate; since the circular connector electrolyzer consumes a lot of CO2, its reverse WGSR reaction rate is greatly reduced at the outlet.

[0064] Figure 11 is the DIR reaction rate of the electrolytic cell with traditional flow channel and circular connector (DIR reaction: ) distribution, with negative values indicating a reverse reaction. Because no CH₄ is introduced at the cathode inlet, the DIR reaction in this model proceeds in reverse. Compared to the WGSR reaction rate, the DIR reaction rate is much lower. It can be seen that the DIR reverse reaction rate is lowest, almost zero, at the cathode inlet for both electrolyzers because there is no CH₄ reactant at the cathode inlet for the DIR forward reaction. The DIR reverse reaction rate gradually increases as the reactant gas penetrates deeper along the flow channel (in the -z direction). The DIR reverse reaction rate in the electrolyzer with a circular connector is higher than that in the conventional flow channel, resulting in a higher CH₄ content in the circular connector.

[0065] Figure 12 The temperature distribution of the traditional flow channel and the circular connector electrolytic cell PEN under the downstream arrangement state of 1.4 V voltage. It can be seen that the overall temperature of the circular connector PEN is higher, and its maximum temperature is 1108 K, which is about 0.5 K higher than the maximum temperature of the traditional flow channel.

[0066] Figure 13 Figure 3 shows the temperature distribution of the electrolyte middle section (x=20 mm, y=-0.4175 mm) along the flow direction of the traditional flow channel and the circular connector electrolytic cell under the downstream arrangement state of 1.4 V voltage. It can be seen that the overall temperature of the circular connector PEN is higher than that of the traditional flow channel. The higher working stability is conducive to improving the electrolyte ion conductivity, thereby accelerating the electrochemical reaction rate.

[0067] Figure 14 The electrolyte current density distribution of the conventional flow channel and circular connector electrolytic cell under the 1.4 V voltage downstream arrangement. The electrolyte current density of the conventional direct flow channel ranges from 3847 to 4663 A / m 2 The electrolyte current density of the circular connector varies from 3687 to 4674 A / m2; the maximum current density of the circular connector is 11 A / m higher than that of the traditional flow channel. 2 , higher current density corresponds to higher electrolysis efficiency, and the electrolyte current density of the circular connector is more uniform. Only the local circular low current density between the circular connectors is present, and the electrolyte current density in other areas is higher than that of the traditional flow channel. This is also the advantage of this design.

[0068] Table 1 Geometric parameters of solid oxide electrolyzer model

[0069]

[0070] Table 2 Performance comparison of connectors with different cross-sectional shapes

[0071]

[0072] Table 3 Effect of circular column connector diameter on SOEC performance

[0073]

[0074] In the above table 2, through the comparison of traditional flow channels, square connector flow channels, circular connector flow channels and triangular connector flow channels, it is proved that the circular connector flow channel has higher hydrogen production efficiency. Table 3 shows that the performance is better and the hydrogen production capacity is greater when the side length is 4 mm.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention. They should all be included in the scope of the technical solution for protection of the present invention.

Claims

1. A circular interconnected solid oxide electrolyzer geometry for improving syngas electrolysis efficiency, characterized by: It includes a first connector and a second connector in the shape of a cover that are arranged opposite to each other, and a partition layer located between the first connector and the second connector. A plurality of cylindrical connectors are arranged in an array between the inner bottom surfaces of the first connector and the second connector and the partition layer, forming vertical cross flow channels between the cylindrical connectors.

2. The circular interconnected solid oxide electrolyzer geometry for improving syngas electrolysis efficiency according to claim 1, characterized in that: 1-72 cylindrical connectors are arranged in the first connector and the second connector, and the diameter of the cylindrical connector is 4 mm.

3. The circular connector solid oxide electrolyzer geometric structure for improving syngas electrolysis efficiency according to claim 1 or 2, characterized in that: The first connecting body and the second connecting body are made of stainless steel.

4. The circular interconnected solid oxide electrolyzer geometry for improving syngas electrolysis efficiency according to claim 3, characterized in that: The separator includes a cathode support layer, a cathode functional layer, an electrolyte layer, an anode functional layer and an anode current collecting layer in sequence.

5. The circular interconnected solid oxide electrolyzer geometric structure for improving syngas electrolysis efficiency according to claim 4, characterized in that: A fuel electrode flow channel is formed between the first connector and the spacer for passing H2O / CO2, and an air electrode flow channel is formed between the second connector and the spacer for passing air. A voltage of 1.4 V is loaded between the first connector and the second connector.

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