Water electrolysis hydrogen production device based on graphite electrode

Abstract

The invention relates to the technical field of water electrolysis hydrogen production, and particularly discloses a graphite electrode-based water electrolysis hydrogen production device, which comprises a power supply, a reactor, a gas collection chamber and a plurality of electrode groups, the upper part of the reactor is provided with a water inlet, the bottom of the reactor is provided with an electrolytic tank, the electrolytic tank is filled with electrolyte, and the liquid level of the electrolyte is lower than the water inlet; the plurality of electrode groups are arranged in an electrolytic tank of the reactor and are soaked in electrolyte, each electrode group comprises an insulating ring, a plurality of graphite anodes and a plurality of graphite cathodes, a plurality of preset clamping grooves are uniformly distributed in the insulating ring, the graphite anodes and the graphite cathodes are crosswise embedded in the preset clamping grooves, the graphite anodes are connected in parallel to a positive electrode of a power supply, and the graphite cathodes are connected in parallel to a negative electrode of the power supply. The graphite cathodes are connected in parallel to the power supply cathode; the gas collecting chamber is positioned above the reactor and is communicated with the reactor through a connecting pipeline; a one-way valve is arranged on the connecting pipeline, so that a one-way connecting channel is formed between the reactor and the collecting chamber.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by water electrolysis, and particularly relates to a hydrogen production device by water electrolysis based on graphite electrodes. Background Art

[0002] As a clean and sustainable hydrogen production method, the core of hydrogen production by water electrolysis is to decompose water into hydrogen and oxygen through an electrochemical reaction, with no carbon emissions during the process, which conforms to the development trend of green energy. With the rapid development of hydrogen energy technology, it has important application value in the hydrogen energy industry, energy storage and laboratory research, and has received extensive attention. However, traditional hydrogen production technologies by water electrolysis have significant limitations in aspects such as electrode materials, reactor design, and electrolyte selection, which restrict their large-scale commercial applications.

[0003] In traditional hydrogen production devices by water electrolysis, the cathode is mainly made of platinum or platinum-based composite materials, using their high catalytic activity to accelerate the hydrogen evolution reaction; the anode mostly uses materials such as nickel or nickel alloys, supplemented by surface coatings to improve corrosion resistance. However, due to the high price of precious metals or their alloy materials, it has a great impact on their popularization; moreover, it is prone to oxidation and corrosion in alkaline electrolytes, and also requires high costs and technical support during use, which further restricts its large-scale application.

[0004] In addition, in traditional hydrogen production devices by water electrolysis, the electrodes mostly adopt a parallel plate arrangement method, with the anode and cathode placed in parallel in the electrolytic cell at a fixed distance. The current density is low, the mass transfer resistance is large, and it is easy to have too high a local electric field intensity, causing concentration polarization and activation polarization, reducing the current efficiency; at the same time, there is also a serious problem of bubble accumulation. The generated hydrogen and oxygen are easily attached to the electrode surface, forming a "dead zone", reducing the effective reaction area.

[0005] Currently, there have been attempts to reduce costs by developing non-precious metal catalysis technologies or optimizing the electrode structure to adopt porous electrodes. However, the overpotential of non-precious metal electrodes is relatively high, and it is difficult to match the performance of precious metal electrodes; while the preparation process of nanostructured electrodes is complex and the industrialization difficulty is relatively large.

[0006] Graphite, as a material with low cost, high conductivity and corrosion resistance, has the potential to be used as an electrolysis electrode. However, the design and arrangement methods of traditional graphite electrodes have not fully utilized their performance advantages, resulting in low electrolysis efficiency. The traditional electrolyte environment is also incompatible with low-cost materials such as graphite. In addition, existing water electrolysis devices also have deficiencies in gas collection, sealing and safety. Therefore, there is an urgent need for an improved hydrogen production device by water electrolysis to improve electrolysis efficiency, reduce costs and enhance safety. Summary of the Invention

[0007] In view of the defects and problems of the current traditional water electrolysis device, such as high electrode cost, easy corrosion of electrode materials, and low electrolysis efficiency, the present invention provides a water electrolysis hydrogen production device based on graphite electrodes. The device includes a power source, a reactor, a gas collection chamber, and multiple electrode groups. An inlet is provided at the upper part of the reactor, and an electrolytic cell is provided at the bottom of the reactor. The electrolytic cell is filled with an electrolyte, and the liquid level of the electrolyte is lower than the inlet. The multiple electrode groups are arranged in the electrolytic cell of the reactor and immersed in the electrolyte. Each electrode group includes an insulating ring, multiple graphite anodes, and multiple graphite cathodes. A plurality of preset card slots are evenly distributed on the insulating ring, and the graphite anodes and graphite cathodes are cross-embedded in the preset card slots. The graphite anodes are connected in parallel to the positive electrode of the power source, and the graphite cathodes are connected in parallel to the negative electrode of the power source. The gas collection chamber is located above the reactor, and the gas collection chamber is communicated with the reactor through a connecting pipe. A one-way valve is installed on the connecting pipe to form a one-way connection channel between the reactor and the collection chamber.

[0008] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, the reactor is an acrylic reactor.

[0009] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, the electrolyte is a sulfuric acid solution with a concentration of 0.5 - 1.5 mol / L.

[0010] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, the distance between adjacent graphite anodes and graphite cathodes is 5 - 10 mm.

[0011] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, the graphite anodes and graphite cathodes are connected to the positive and negative electrodes of the power source through copper wires, and the connection between the copper wires and the graphite electrodes is fixed.

[0012] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, each electrode group includes two insulating rings. The two insulating rings are parallel to each other and the preset card slots on the insulating rings are correspondingly arranged. The adjacent graphite anodes and graphite cathodes are respectively fixed on the two insulating rings.

[0013] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, all the graphite anodes are fixed on the same insulating ring, and all the graphite cathodes are fixed on another insulating ring.

[0014] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, the inner side surface of the preset card slot is an arc concave surface structure, which can be tightly fitted with the cylindrical surfaces of the graphite anodes and graphite cathodes.

[0015] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, the reactor and the gas collection chamber are sealed and packaged through a silica gel sealing ring.

[0016] For the above-mentioned water electrolysis hydrogen production device based on graphite electrodes, a flashback arrester is installed between the gas collection chamber and the one-way valve.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention uses the graphite rods in waste carbon core batteries as the anode and cathode, without the participation of precious metals, greatly reducing the electrode cost. At the same time, a low-concentration sulfuric acid solution is used as the electrolyte, which can effectively reduce the corrosion rate of the graphite electrode while having good ionic conductivity, thus extending the service life.

[0018] 2. The electrode group of the present invention adopts the arrangement method of alternating the anode and cathode electrodes, which can reduce the local electric field concentration, make the electric field more evenly distributed in the electrolyte, thereby reducing the electrode polarization reaction and improving the current efficiency.

[0019] 3. The electrode group of the present invention adopts the structure of alternating the anode and cathode electrodes, increasing the contact area between the electrode surface and the electrolyte, and at the same time promoting the rapid detachment of bubbles (H 2 and O 2 ), reducing the "dead zone" caused by bubbles covering the electrode surface, and improving the effective reaction area.

[0020] 4. The electrode group of the present invention adopts the arrangement method of alternating the anode and cathode electrodes, which can form microchannels, enhance the convection and diffusion of the electrolyte, reduce the transport resistance of reactants (H + and OH - ), and achieve the effect of enhancing mass transfer.

[0021] 5. The present invention selects a low-concentration sulfuric acid solution as the electrolyte. Compared with the problem that alkaline electrolytes in traditional water electrolysis for hydrogen production are prone to generate peroxide by-products, using a low-concentration sulfuric acid electrolyte can directly provide H + as the hydrogen source, without relying on the dissociation of water, effectively avoiding the generation of OH - and peroxides, and improving the hydrogen evolution reaction efficiency.

[0022] 6. The present invention connects the graphite electrodes to the positive and negative electrodes of the power supply in parallel. This can not only diversify the current path, reduce the uneven current distribution caused by local resistance differences of the electrodes, but also the parallel connection can disperse the current density, improve the uniformity of current distribution, avoid overheating of a single electrode due to current overload, thereby maintaining the electrode stability; it can also maintain partial functions of the remaining electrodes in the case of electrode failure due to pollution or corrosion, improving the reliability of the device.

[0023] 7. The present invention installs a one-way valve on the connecting pipeline and an anti-backfire device in the gas collection chamber, which can make the evolved hydrogen flow unidirectionally to the gas collection chamber, prevent hydrogen backflow and backfire during combustion, ensuring safety; at the same time, an appropriate amount of water is injected into the reactor to ensure the free overflow of gas and prevent excessive pressure.

[0024] 8. Through the combined synergistic effects of the cross - arrangement, parallel connection of graphite electrodes, and low - concentration sulfuric acid electrolyte, the electrolysis efficiency and hydrogen evolution efficiency of the present invention are significantly improved. Under the same 12V power supply, the bubble coverage rate is reduced by 50%; the current density can reach 80 - 100 mA / cm², which is significantly higher than the 60 - 70 mA / cm² current density of the traditional parallel scheme; while reducing energy consumption, the hydrogen production rate is increased from 0.8 - 1.0 L / h·dm² of the traditional parallel arrangement to 1.2 - 1.5 L / h·dm²; effectively compensating for the disadvantage that the weak hydrophobicity of the graphite electrode surface is easily adsorbed by gas, resulting in polarization loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the water electrolysis hydrogen production device of the present invention.

[0026] Figure 2 It is a schematic structural diagram of the insulating ring of the present invention.

[0027] Figure 3 It is a front view of the electrode group structure of the present invention.

[0028] Figure 4 It is a top view of the electrode group structure of the present invention.

[0029] In the figure: 1 is the power supply, 2 is the acrylic reactor, 3 is the gas collection chamber, 4 is the electrode group, 41 is the first insulating ring, 42 is the second insulating ring, 43 is the preset card slot, 44 is the graphite anode, 45 is the graphite cathode, 46 is the copper wire, 47 is the bolt, 5 is the electrolyte, 6 is the water inlet, 7 is the connecting pipe, 8 is the hydrogen - conveying pipe, 9 is the check valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] Aiming at the defects and problems of the current traditional water electrolysis device, such as high electrode cost, easy corrosion of electrode materials, and low electrolysis efficiency, the present invention provides a water electrolysis hydrogen production device based on graphite electrodes. The following further illustrates the technology of the present invention with reference to the drawings and specific embodiments.

[0031] Embodiment: This embodiment provides a water electrolysis hydrogen production device based on graphite electrodes. As Figure 1 shown, the water electrolysis hydrogen production device includes a power supply 1, a reactor 2, a gas collection chamber 3, and a plurality of electrode groups 4; among them, the power supply 1 is a 12V DC power supply 1, the reactor 2 is made of an insulating and non - corrosive material. In this embodiment, acrylic material is selected and tightly sealed to ensure the tightness of the device. There is a water inlet 6 at the upper part of the acrylic reactor and an electrolytic cell at the bottom. An appropriate amount of water is injected into the reactor 2 through the water inlet 6 to ensure the free overflow of gas and prevent excessive pressure.

[0032] There are three electrode groups 4 in the electrolytic cell. The three electrode groups are arranged in the electrolytic cell of the reactor 2 and immersed in the electrolyte 5. Each electrode group 4 includes two 3D-printed insulating rings, a plurality of graphite anodes 44 and a plurality of graphite cathodes 45. The used graphite anodes 44 and graphite cathodes 45 are graphite rods extracted from waste carbon core batteries. After being cleaned and the surface impurities are removed, they are used. Compared with the precious metal electrodes used in traditional water electrolysis devices, using waste graphite rods as the anode and cathode electrode materials, the electrode cost is significantly lower. As Figure 2 and Figure 3 shown, the insulating ring 1 41 and the insulating ring 2 42 are arranged in parallel, and an equal number of even-numbered preset card slots 43 are evenly distributed on the two insulating rings. The preset card slots 43 on the two insulating rings are arranged in one-to-one correspondence, so that both ends of the graphite electrode can pass through the preset card slots of the two insulating rings. The inner side surface of the preset card slot is an arc concave surface structure, which can be tightly fitted with the cylindrical surface of the graphite anode 44 and the graphite cathode 45 for easy fixation.

[0033] The electrolytic cell is filled with the electrolyte 5. The liquid level height of the electrolyte is lower than the water inlet 6 to prevent the electrolyte from overflowing from the water inlet 6 and affecting the injection of water into the electrolytic cell. A gas collection chamber 3 is provided above the reactor 2. The gas collection chamber is communicated with the reactor through a connecting pipe 7. For safety improvement, a check valve 9 is installed on the connecting pipe 7 to form a one-way connection channel between the reactor 2 and the collection chamber. At the same time, a flashback arrester is installed on the gas collection chamber 3 to prevent the backflow of hydrogen and flashback during combustion. In order to extend the service life of the check valve, an acid-resistant check valve is selected to slow down the corrosion of the acidic steam generated during the water electrolysis to produce hydrogen.

[0034] In this embodiment, the graphite anodes 44 and the graphite cathodes 45 are arranged in a cross pattern, and the distance between adjacent graphite anodes 44 and graphite cathodes 45 is tested and optimized. According to Ohm's law, the anode-cathode distance directly affects the resistance of the electrolyte. If the distance is too large, the energy consumption will increase significantly. If it is too small, short circuit is likely to occur due to bubble accumulation. After testing, the comprehensive efficiency is the highest when the adjacent anode-cathode distance is controlled at 5-10 mm.

[0035] The anode and cathode electrodes in this embodiment are arranged in a cross pattern. On the one hand, it can reduce the local electric field concentration, make the electric field distribution in the electrolyte more uniform, thereby reducing the electrode polarization effect, such as concentration polarization and activation polarization, and improving the current efficiency. On the other hand, the cross arrangement can also increase the contact area between the electrode surface and the electrolyte 5, and at the same time promote the rapid detachment of bubbles (H 2 and O 2 ), reduce the "dead zone" caused by bubbles covering the electrode surface, and increase the effective reaction area. In addition, the cross arrangement can also form microchannels, enhance the convection and diffusion of the electrolyte 5, and reduce the reactants (H + and OH -The transmission resistance of ( ) is realized to enhance mass transfer.

[0036] As Figure 4 shown, for the convenience of installation and wire connection, to prevent poor contact and electric leakage, the graphite anode 44 of each electrode group is fixed on the first insulating ring 41, and after welding the electrodes through the copper wire 46, it is connected in parallel to the positive pole of the power supply 1. The graphite cathode 45 is fixed on the second insulating ring 42, and after welding the electrodes through the copper wire, it is connected in parallel to the negative pole of the power supply 1. The parallel connection method can not only improve the current distribution uniformity, but also diversify the current path, reducing the uneven current distribution caused by the local resistance difference of the electrodes; it can also disperse the current density, avoiding overheating (Joule heat) caused by current overload in a single electrode, thereby maintaining the electrode stability. Even in the special case where a certain electrode fails due to pollution or corrosion, the remaining electrodes can still maintain partial functions, improving the reliability of the device.

[0037] Since graphite is easily oxidized in traditional alkaline electrolytes, in this embodiment, a 0.5M sulfuric acid solution is selected as the electrolyte, allowing an acidic electrolyte environment to exist, avoiding the corrosion of the electrodes by the electrolyte, and effectively reducing the corrosion rate of the graphite electrodes; at the same time, compared with alkaline electrolytes that are prone to generate peroxide by-products, the acidic environment of the low-concentration sulfuric acid electrolyte directly provides H⁺ as the hydrogen source, without relying on the dissociation of water, which can reduce energy consumption and effectively avoid the generation of OH - and peroxide. After testing, under the same 12V power supply condition, the current density of this solution can reach 80 - 100 mA / cm², significantly higher than the current density of 60 - 70 mA / cm² of the traditional parallel solution, and the energy consumption is significantly reduced. At the same time, the hydrogen generation rate is increased to 1.2 - 1.5 L / h·dm², higher than 0.8 - 1.0 L / h·dm² of the traditional parallel method. It can be seen that the electrolysis efficiency and hydrogen generation rate can be significantly improved.

[0038] The above are only the preferred embodiments of the present invention and do not limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A water electrolysis hydrogen production device based on graphite electrodes, characterized in that: It comprises a power supply, a reactor, a gas collection chamber and a plurality of electrode groups; the reactor is provided with a water inlet at the top and an electrolytic cell at the bottom, the electrolytic cell is filled with electrolyte, and the electrolyte level is lower than the water inlet; the plurality of electrode groups are arranged in the electrolytic cell of the reactor and immersed in the electrolyte, each electrode group comprises an insulating ring, a plurality of graphite anodes and a plurality of graphite cathodes, the insulating ring is evenly provided with a plurality of preset slots, the graphite anodes and the graphite cathodes are cross-embedded in the preset slots, the graphite anodes are connected in parallel to the positive pole of the power supply, and the graphite cathodes are connected in parallel to the negative pole of the power supply; the gas collection chamber is located above the reactor, and is connected to the reactor through a connecting pipe; a one-way valve is installed on the connecting pipe to form a one-way connection channel from the reactor to the collection chamber.

2. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 1, characterized in that: The reactor is an acrylic reactor.

3. The water electrolysis hydrogen production device based on graphite electrodes according to claim 1, characterized in that: The electrolyte is a 0.5-1.5 mol / L sulfuric acid solution.

4. The water electrolysis hydrogen production device based on graphite electrodes according to claim 1, characterized in that: The distance between adjacent graphite anodes and graphite cathodes is 5-10 mm.

5. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 1, characterized in that: The graphite anode and the graphite cathode are connected to the positive and negative electrodes of the power supply through copper wires, and the connection between the copper wires and the graphite electrodes is fixed.

6. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 1, characterized in that: Each electrode group includes two insulating rings, the two insulating rings are parallel to each other and the preset slots on the insulating rings are arranged correspondingly, and adjacent graphite anodes and graphite cathodes are fixed on the two insulating rings respectively.

7. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 6, characterized in that: The graphite anodes are all fixed on the same insulating ring, and the graphite cathodes are all fixed on another insulating ring.

8. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 1, characterized in that: The inner side surface of the preset slot is an arc-shaped concave structure, which can be tightly embedded with the cylindrical surface of the graphite anode and the graphite cathode.

9. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 1, characterized in that: The reactor and the gas collection chamber are sealed and packaged by a silicone sealing ring.

10. The device for producing hydrogen by water electrolysis based on graphite electrodes according to claim 1, characterized in that: A flashback arrester is provided between the gas collecting chamber and the one-way valve.

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