Electrolytic water hydrogen production system for reducing hydrogen content in oxygen

Abstract

The utility model relates to a kind of electrolytic water hydrogen production system for reducing hydrogen content in oxygen, including electrolytic cell, cathode side is sequentially connected with hydrogen separator, first washing tower, first gas cooler, purification pry piece;Anode side is sequentially connected with dehydrogenation reactor, oxygen separator, second washing tower, second gas cooler;Compressed air pipe is connected between dehydrogenation reactor and oxygen separator;Second gas cooler's exhaust pipe is also connected with hydrogen content detector;Hydrogen separator, oxygen separator are sequentially connected with lye circulating pump, lye cooler, electrolytic cell by three-way pipe.It can solve the problem that gas in oxygen separation module has higher explosion risk when electrolytic water hydrogen production system is in low load operation by using the electrolytic water hydrogen production system for reducing hydrogen content in oxygen designed by the utility model.

Description

Technical Field

[0001] This utility model relates to the field of water electrolysis for hydrogen production technology, and specifically to a water electrolysis system for reducing the hydrogen content in oxygen. Background Technology

[0002] Hydrogen energy, as a green and low-carbon secondary energy source, plays an indispensable role in the new energy landscape. Flexible water electrolysis hydrogen production technology, through advanced hydrogen production technology and an intelligent management system, achieves deep coupling and flexible adjustment between the hydrogen production process and renewable energy power generation. This hydrogen production method can fully adapt to the rapid fluctuations and intermittent characteristics of photovoltaic and wind power, achieving a stable, efficient, and intelligent hydrogen production process.

[0003] In an alkaline electrolyzer, a diaphragm divides the electrolysis chamber into anode and cathode compartments. The water electrolysis reaction occurs in the anode compartment, where oxidation oxidizes water molecules into oxygen. Simultaneously, hydrogen ions permeate through the diaphragm into the cathode compartment, where a reduction reaction produces hydrogen gas. The diaphragm separates the generated hydrogen and oxygen, allowing them to proceed to subsequent separation and purification processes. However, the diaphragm also needs sufficient porosity to allow hydrogen ions to pass through into the cathode compartment. Since the diaphragm porosity is typically between 1 and 10 micrometers, much larger than the dynamic diameter of hydrogen molecules (0.289 nm), when the cathode pressure is higher than the anode pressure, hydrogen may be forced into the anode compartment and mix with the generated oxygen. Because the production load of flexible hydrogen production fluctuates within a certain range, when the water electrolysis unit operates at low load, the amount of hydrogen and oxygen produced decreases. However, the amount of hydrogen permeating into the anode compartment through the diaphragm is not affected by the hydrogen production, leading to an increase in the hydrogen-oxygen mixing ratio at the oxygen outlet. When the volume concentration of hydrogen in oxygen reaches 4% to 94%, an explosion can occur if an ignition source is present. Therefore, when the water electrolysis hydrogen production system is operating at low load, the gas in the oxygen separation module has a high risk of explosion.

[0004] To address this potential safety hazard, Chinese patent CN119411146A, entitled "Alkaline Electrolysis Hydrogen Production Device and Method for Reducing Hydrogen Content in Oxygen," proposes inserting a third electrode into the anode chamber of an alkaline electrolyzer to form a hydrogen-oxygen fuel cell circuit. This allows the permeated hydrogen in the anode chamber to undergo an electrochemical reverse reaction and be removed, thereby reducing the hydrogen concentration in the oxygen-to-hydrogen production system and improving system safety. While this method can theoretically reduce the hydrogen concentration in oxygen, the introduction of the third electrode increases the manufacturing cost of the electrolyzer equipment, and it has not been applied in large-scale industrial production; the stability of its operation remains to be verified.

[0005] Chinese patent CN117144416A, entitled "A Control Method for Alkaline Electrolysis Hydrogen Production Adapted to Wide Power Fluctuations," describes a method to reduce the degree of hydrogen-oxygen mixing and improve hydrogen production purity by dynamically adjusting the hydrogen-oxygen side pressure and the alkaline solution circulation speed. It mentions reducing the alkaline solution circulation speed to decrease the amount of dissolved oxygen and hydrogen flowing to the other side with the alkaline solution, thus reducing hydrogen-oxygen mixing; simultaneously, it reduces the hydrogen-oxygen side pressure ratio, thereby reducing the possibility of hydrogen permeating the alkaline membrane. This method can not only effectively solve the problem of hydrogen production purity under low load conditions but also reduce the hydrogen concentration in oxygen on the oxygen side. However, since the main source of hydrogen in oxygen is hydrogen entering the oxygen separation system through the membrane, reducing the alkaline solution circulation speed or the pressure ratio can only reduce the hydrogen content in oxygen; it cannot fundamentally solve the problem of excessive hydrogen in oxygen and ensure that the hydrogen-oxygen mixing ratio is maintained below the explosion limit.

[0006] Therefore, existing technologies have shortcomings and need to be improved and developed. Utility Model Content

[0007] The utility model provides an electrolytic water hydrogen production system for reducing the hydrogen content in oxygen, which solves the problem that the gas in the oxygen separation module has a high explosion hazard when the electrolytic water hydrogen production system is operating at low load in the prior art.

[0008] This utility model provides a water electrolysis hydrogen production system for reducing the hydrogen content in oxygen, including an electrolyzer. The cathode side of the electrolyzer is connected in sequence to a hydrogen separator, a first washing tower, a first gas cooler, and a purification skid, so that the hydrogen generated in the electrolyzer is sequentially subjected to liquid-gas separation, hydrogen washing, hydrogen cooling, and hydrogen purification to obtain hydrogen product.

[0009] The anode side of the electrolytic cell is sequentially connected to a dehydrogenation reactor, an oxygen separator, a second scrubbing tower, and a second gas cooler via pipelines, so that the oxygen generated in the electrolytic cell is discharged after sequentially undergoing hydrogen removal, liquid-gas separation, oxygen scrubbing, and oxygen cooling; a compressed air pipe for compressed air to enter the oxygen separator is also connected between the pipelines of the dehydrogenation reactor and the oxygen separator, and a valve is connected to the compressed air pipe; a hydrogen content detector is also connected to the exhaust pipe of the second gas cooler for discharging oxygen.

[0010] The outlet pipes of the hydrogen separator and the oxygen separator are respectively connected to two ports of a three-way pipe. The remaining port of the three-way pipe is connected in sequence to the alkali circulation pump, the alkali cooler, and the electrolytic cell via a pipeline.

[0011] Furthermore, the dehydrogenation reactor is a tank-type reaction vessel with its inlet located at the bottom and its outlet located at the top.

[0012] Furthermore, the dehydrogenation packing material filled in the dehydrogenation reactor is coated with precious metal catalyst powder.

[0013] Furthermore, the precious metal catalyst powder is one of palladium powder, platinum powder, and rhodium powder.

[0014] Furthermore, the valve connected to the compressed air pipe is a flow regulating valve.

[0015] Furthermore, both the first and second washing towers are counter-current spray washing towers.

[0016] Beneficial effects:

[0017] As can be seen from the above technical solutions, this utility model provides an electrolytic water production system for reducing the hydrogen content in oxygen, which has the following beneficial effects:

[0018] 1. Achieving proactive reduction of hydrogen content in oxygen under low-load conditions: By sequentially installing a dehydrogenation reactor, an oxygen separator, a second scrubbing tower, and a second gas cooler on the anode side of the electrolyzer, and connecting a compressed air pipe between the dehydrogenation reactor and the oxygen separator, a dedicated dehydrogenation and post-treatment process for the oxygen side is constructed. The dehydrogenation reactor is filled with dehydrogenation packing material coated with precious metal catalyst powder, causing hydrogen and oxygen permeating into the anode chamber to undergo a catalytic oxidation reaction, generating water, which is subsequently removed from the gas phase by the oxygen separator and the second scrubbing tower, thereby reducing residual hydrogen in the oxygen at its source.

[0019] 2. Balancing Hydrogen Product Quality and Electrolytic Alkali Solution Circulation Stability: A hydrogen separator, a first washing tower, a first gas cooler, and a purification skid are installed on the cathode side of the electrolyzer. This allows the hydrogen generated on the cathode side to undergo sequential liquid-gas separation, washing, cooling, and purification to obtain the hydrogen product. Simultaneously, the outlet pipes of the hydrogen separator and oxygen separator are collected into a three-way pipe, and then returned to the electrolyzer via an alkali solution circulation pump and alkali solution cooler. This ensures that the alkali solutions separated from the cathode and anode sides are uniformly incorporated into the circulation loop, which helps maintain the stability of the alkali solution composition and temperature within the electrolyzer and reduces the accumulation of localized bubbles or dissolved gases in the liquid phase.

[0020] 3. Reduce the explosion hazard of the oxygen discharge pipeline: A hydrogen content detector is installed on the exhaust pipe of the second gas cooler used for oxygen discharge to monitor the hydrogen content at the oxygen discharge end online. When the hydrogen content approaches the preset safety threshold, the amount of compressed air entering the oxygen separator can be adjusted in conjunction with the pneumatic valve on the compressed air pipeline to further dilute the hydrogen in the oxygen, or corresponding measures can be taken in conjunction with the system control strategy, thereby reducing the risk of the hydrogen-oxygen mixture in the oxygen discharge pipeline entering the flammable and explosive range.

[0021] 4. Improve overall system reliability: The hydrogen separator and oxygen separator adopt a vertical cylindrical structure with a packing layer and demister, combined with a first and second scrubbing tower with a counter-current spray structure, to fully remove entrained droplets and soluble impurities from hydrogen and oxygen. The first and second gas coolers further reduce the temperature and saturated water vapor content before gas discharge and transportation, which is beneficial for the corrosion prevention and stable operation of subsequent pipelines and equipment.

[0022] 5. A system-level safety control foundation suitable for flexible water electrolysis hydrogen production has been established: Through the comprehensive configuration of anode-side dehydrogenation reaction, compressed air introduction, online oxygen hydrogen content detection, and cathode-side hydrogen product purification and unified alkali circulation path, not only has a specialized system for reducing the hydrogen content in oxygen been structurally constructed, but a safety control foundation has also been provided for the long-term operation of flexible water electrolysis hydrogen production over a wide load range. This is conducive to coordination with fluctuating renewable energy power sources to achieve a safe, stable, and efficient hydrogen production process.

[0023] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0024] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0025] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0026] Figure 1 This is a structural diagram of an electrolytic water production system for reducing the hydrogen content in oxygen, as described in an embodiment of this application.

[0027] Explanation of icon numbers:

[0028] 1. Electrolyzer; 2. Hydrogen separator; 3. First scrubbing tower; 4. First gas cooler; 5. Purification skid; 6. Dehydrogenation reactor; 7. Oxygen separator; 8. Second scrubbing tower; 9. Second gas cooler; 10. Valve; 11. Hydrogen content detector; 12. Alkali circulation pump; 13. Alkali cooler. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0030] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0031] Because the production load of flexible hydrogen production fluctuates within a certain range, when the water electrolysis unit operates at low load, the amount of hydrogen and oxygen produced by water electrolysis decreases. However, the amount of hydrogen permeating into the anode chamber through the diaphragm is not affected by the hydrogen production, which leads to an increase in the hydrogen-oxygen mixing ratio at the oxygen outlet. When the volume concentration of hydrogen in oxygen reaches 4% to 94%, an explosion can occur if an ignition source is present. Therefore, when the water electrolysis hydrogen production system is operating at low load, the gas in the oxygen separation module has a high risk of explosion.

[0032] In view of this, the present invention provides an electrolytic water production system for reducing the hydrogen content in oxygen, comprising an electrolytic cell 1.

[0033] The cathode side of the electrolytic cell 1 is connected in sequence by a hydrogen separator 2, a first washing tower 3, a first gas cooler 4, and a purification skid 5, so that the hydrogen generated in the electrolytic cell 1 will be sequentially subjected to liquid-gas separation, hydrogen washing, hydrogen cooling, and hydrogen purification to obtain hydrogen products.

[0034] The gas-liquid mixture from the cathode of electrolytic cell 1 enters hydrogen separator 2. The separated liquid is transported back to electrolytic cell 1 via alkaline circulating pump 12, and the gas is transported to downstream users after passing through first scrubbing tower 3 and first gas cooler 4.

[0035] The anode side of the electrolytic cell 1 is connected in sequence by a dehydrogenation reactor 6, an oxygen separator 7, a second scrubbing tower 8, and a second gas cooler 9 via pipelines, so that the oxygen generated in the electrolytic cell 1 is discharged after passing through hydrogen removal, liquid-gas separation, oxygen scrubbing, and oxygen cooling in sequence; a compressed air pipe for compressed air to enter the oxygen separator 7 is also connected between the pipelines of the dehydrogenation reactor 6 and the oxygen separator 7, and a valve 10 is connected to the compressed air pipe; a hydrogen content detector 11 is also connected to the exhaust pipe of the second gas cooler 9 for discharging oxygen.

[0036] The gas-liquid mixture from the anode of electrolytic cell 1 enters oxygen separator 7. The separated liquid is transported back to electrolytic cell 1 via alkaline circulating pump 12. The gas is directly vented after passing through the second scrubbing tower 8 and the second gas cooler 9.

[0037] In traditional hydrogen production processes, when the water electrolysis unit operates under low load, the hydrogen-oxygen mixing ratio at the oxygen outlet increases significantly. To avoid the resulting explosion hazard, refer to... Figure 1 A dehydrogenation reactor 6 is installed at the anode outlet. It removes hydrogen from oxygen through a catalytic reaction. Under the action of the catalyst, hydrogen and oxygen react at a molar ratio of 2:1, removing a portion of the hydrogen and effectively reducing the hydrogen content entering the oxygen separation system, fundamentally eliminating the main risk. In some embodiments, the dehydrogenation reactor 6 is a tank-type reaction vessel with the inlet located at the bottom and the outlet at the top. In some embodiments, the dehydrogenation packing material filling the dehydrogenation reactor 6 is coated with precious metal catalyst powder. In some embodiments, the precious metal catalyst powder is one of palladium powder, platinum powder, and rhodium powder. The precious metal powder is attached to the packing material, with the packing layer thickness sufficient to cover the entire straight section. The gas-liquid mixture flowing from the anode enters the dehydrogenation reactor 6, where, under the action of the precious metal catalyst, hydrogen and oxygen further react to produce water, thus reducing the hydrogen content.

[0038] To further control the hydrogen content in the oxygen separation system, a hydrogen content detector 11 is installed on the oxygen venting pipe. The detector is set to trigger a high-hydrogen-content level one alarm when the hydrogen content in the ambient air exceeds 1% VOL, and a high-to-high-hydrogen-content level two alarm when the hydrogen content exceeds 2% VOL. Simultaneously, valve 10 on the compressed air pipe is opened to introduce compressed air into the inlet material of the oxygen separator 7, reducing the hydrogen content in the inlet material. The hydrogen detector controls valve 10 on the compressed air pipe, which can be manually controlled or controlled by a separately designed program. This controls the amount of hydrogen in the oxygen separator 7, preventing the explosion hazard caused by excessive hydrogen content. Valve 10 on the compressed air pipe is closed only after the hydrogen content in the venting pipe falls below the safety set value.

[0039] Compressed air is the preferred safe medium. Compressed air mainly contains nitrogen and oxygen. As an inert gas, nitrogen can reduce the partial pressure of hydrogen through physical displacement, which can quickly dilute the hydrogen concentration and push it away from the explosion limit. The overall concentration of oxygen in it still decreases after being diluted by nitrogen. Therefore, compressed air has the advantages of high safety and easy availability.

[0040] In existing industrial processes, hydrogen analyzers and online gas chromatographs based on the thermal conductivity detection principle are commonly used devices for hydrogen content detection, and their structure and usage are well known to those skilled in the art. In some embodiments, the valve 10 connected to the compressed air pipe is a flow regulating valve. By combining existing detection and control technologies, those skilled in the art can select appropriate instrument models and connection methods as needed to specifically implement detection and regulation.

[0041] The outlet pipes of hydrogen separator 2 and oxygen separator 7 are respectively connected to two ports of a three-way pipe. The remaining port of the three-way pipe is connected in sequence to alkali circulation pump 12, alkali cooler 13, and electrolytic cell 1 through a pipeline.

[0042] In alkaline electrolyzer 1, water molecules undergo a reduction reaction at the cathode under the influence of direct current, producing hydrogen and hydroxide ions. Subsequently, these hydroxide ions, propelled by the electric field and the concentration difference between the hydrogen and oxygen sides, cross the membrane and reach the anode. Finally, an oxygen evolution reaction occurs at the anode, producing oxygen and water. Electrolyzer 1 is immersed in alkaline electrolyte during operation. The electrolytic cell is designed with two electrodes separated by a membrane. This membrane design ensures that hydrogen and oxygen do not mix, while allowing the electrolyte to flow smoothly through the membrane to the other side. During the operation of the hydrogen production system, the mixture of hydrogen and alkaline solution flows out from the cathode and enters the hydrogen separation system. After separation, the hydrogen is further purified by the purification skid 5 and then sent to the user's location. The mixture of oxygen and alkaline solution flows out from the sample end and enters the oxygen separator 7. After separation, any oxygen not required for recovery is directly discharged. Hydrogen separator 2 and oxygen separator 7 can effectively separate the gas and the solution. The separated alkaline solution will pass through alkaline solution circulation pump 12 and cooler, and then flow back into electrolytic cell 1 to continue participating in the reaction.

[0043] In some embodiments, both the first scrubbing tower 3 and the second scrubbing tower 8 are countercurrent spray scrubbing towers.

[0044] All modifications are to the equipment and piping systems, using conventional methods found in industrial installations. Valves can be added to the pipes as needed to achieve control, so there will be virtually no impact on the operational stability of already mature and widely used complete sets of equipment.

[0045] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A water electrolysis system for reducing the hydrogen content in oxygen, comprising an electrolyzer, characterized in that, The cathode side of the electrolytic cell is connected in sequence by a hydrogen separator, a first washing tower, a first gas cooler, and a purification skid through a pipeline, so that the hydrogen generated in the electrolytic cell is sequentially subjected to liquid-gas separation, hydrogen washing, hydrogen cooling, and hydrogen purification to obtain hydrogen products. The anode side of the electrolytic cell is sequentially connected to a dehydrogenation reactor, an oxygen separator, a second scrubbing tower, and a second gas cooler via pipelines, so that the oxygen generated in the electrolytic cell is discharged after sequentially undergoing hydrogen removal, liquid-gas separation, oxygen scrubbing, and oxygen cooling; a compressed air pipe for compressed air to enter the oxygen separator is also connected between the pipelines of the dehydrogenation reactor and the oxygen separator, and a valve is connected to the compressed air pipe; a hydrogen content detector is also connected to the exhaust pipe of the second gas cooler for discharging oxygen. The outlet pipes of the hydrogen separator and the oxygen separator are respectively connected to two ports of a three-way pipe. The remaining port of the three-way pipe is connected in sequence to the alkali circulation pump, the alkali cooler, and the electrolytic cell via a pipeline.

2. The water electrolysis hydrogen production system for reducing the hydrogen content in oxygen according to claim 1, characterized in that, The dehydrogenation reactor is a tank-type reaction vessel with the feed inlet located at the bottom and the discharge outlet located at the top.

3. The water electrolysis hydrogen production system for reducing the hydrogen content in oxygen according to claim 2, characterized in that, The dehydrogenation reactor is filled with dehydrogenation packing material coated with precious metal catalyst powder.

4. The water electrolysis hydrogen production system for reducing the hydrogen content in oxygen according to claim 3, characterized in that, The precious metal catalyst powder is one of palladium powder, platinum powder, and rhodium powder.

5. The water electrolysis hydrogen production system for reducing the hydrogen content in oxygen according to claim 1, characterized in that, The valve connected to the compressed air pipe is a flow regulating valve.

6. The water electrolysis hydrogen production system for reducing the hydrogen content in oxygen according to claim 1, characterized in that, Both the first and second washing towers are counter-current spray washing towers.

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