On-line monitoring system for hydrogen concentration in oxygen in hydrogen production process by alkaline electrolysis of water

Abstract

The utility model relates to an on-line monitoring system for hydrogen concentration in oxygen in a hydrogen production process by alkaline electrolysis of water, which is characterized in that an oxygen side outlet of each electrolytic cell is connected with an input end of an oxygen preprocessor, and gas output ends of a plurality of oxygen preprocessors are communicated with a gas phase end of a same oxygen separator; the liquid output ends of the plurality of oxygen preprocessors are connected with the liquid phase end of the same oxygen separator; a hydrogen side outlet of each electrolytic cell is connected with a hydrogen separator, the oxygen separator and the hydrogen separator are simultaneously connected with an alkali liquor cooler, and alkali liquor cooled by the alkali liquor cooler is communicated with the matched electrolytic cell through an alkali liquor circulating pump; a check valve, a pressure transmitter and a regulating valve are sequentially mounted at an oxygen side outlet and a hydrogen side outlet of each electrolytic cell; and the input end and the gas output end of the oxygen preprocessor are respectively provided with an oxygen-hydrogen analyzer. According to the utility model, shutdown of the separator caused by excessive hydrogen content in oxygen can be avoided, and long-term stable operation of the separator is ensured.

Description

Technical Field

[0001] The utility model relates to an online monitoring system for the concentration of hydrogen in oxygen during the process of producing hydrogen by alkaline water electrolysis, and belongs to the technical field of water electrolysis. Background Art

[0002] When multiple electrolytic cells are used in parallel, the operating conditions of each electrolytic cell are different, resulting in different gas-liquid pressures entering the separator from the electrolytic cell. This in turn results in different outlet resistances for each electrolytic cell, causing pressure imbalance inside the electrolytic cell, causing hydrogen and oxygen to pass through the diaphragm and cross-talk between hydrogen and oxygen. In severe cases, explosions may occur, affecting the safety of the electrolytic cell operation.

[0003] In addition to the differences in operating conditions between several electrolyzers, there are also differences in the pressure between each electrolyzer and the separator. The gas in the separator may flow back into the electrolyzer, causing an imbalance in the pressure between the hydrogen and oxygen sides of the electrolyzer, further increasing the difficulty of controlling the operation of the electrolyzer.

[0004] Therefore, it is necessary to design a monitoring system for the safe and stable operation of one or more electrolytic cells connected in parallel, so as to solve the problems in the prior art such as the inconsistency of the operating conditions of the electrolytic cells, the imbalance of the gas production and pressure of the electrolytic cells, the difference between the pressure in each electrolytic cell and the total pressure of the separator, etc., which lead to poor exhaust of the low-pressure electrolytic cells and even gas backflow. Summary of the invention

[0005] The utility model provides an online monitoring system for the concentration of hydrogen in oxygen during the process of producing hydrogen by alkaline water electrolysis, which monitors the concentration index of hydrogen in oxygen on the oxygen side of the electrolyzer, avoids the shutdown of the separator due to excessive hydrogen in oxygen content, and ensures the long-term stable operation of the separator.

[0006] The technical solution adopted by the utility model to solve its technical problems is:

[0007] An online monitoring system for the concentration of hydrogen in oxygen during the process of producing hydrogen by alkaline water electrolysis comprises a plurality of electrolyzers, an oxygen separator, a hydrogen separator, an alkali solution cooler and an alkali solution circulation pump.

[0008] The oxygen side outlet of each electrolyzer is connected to the input end of an oxygen preprocessor, the gas output ends of several oxygen preprocessors are connected to the gas phase end of the same oxygen separator, and the liquid output ends of several oxygen preprocessors are connected to the liquid phase end of the same oxygen separator; the hydrogen side outlet of each electrolyzer is connected to the hydrogen separator, the oxygen separator and the hydrogen separator are simultaneously connected to the alkali liquid cooler, and the alkali liquid cooled by the alkali liquid cooler is connected to the matching electrolyzer through the alkali liquid circulation pump;

[0009] A lye temperature monitor is provided at the inlet of each electrolytic cell to monitor the temperature of the lye;

[0010] A check valve, a pressure transmitter and a regulating valve are sequentially installed at the oxygen side outlet and the hydrogen side outlet of each electrolyzer;

[0011] The input end and gas output end of the oxygen preprocessor are respectively provided with oxygen-hydrogen analyzers;

[0012] As a further design of the utility model, the oxygen preprocessor includes a dehydrogenation device and a separation tank which are interconnected, and the dehydrogenation device is located on the top of the separation tank, and the dehydrogenation device and the separation tank are detachably connected via a flange;

[0013] The dehydrogenation device is used for catalytic reaction between hydrogen in oxygen and oxygen;

[0014] The separation tank is used to separate liquid and gaseous oxygen;

[0015] As a further design of the utility model, an electric heater is installed on the top of the dehydrogenation device, and the electric heater is started to maintain the internal temperature of the dehydrogenation device ≤ 200°C;

[0016] As a further design of the utility model, a dehydrogenation catalyst is arranged in the dehydrogenation device, and the dehydrogenation catalyst is a palladium catalyst with titanium or other metal as a carrier;

[0017] As a further design of the utility model, an oxygen-hydrogen analyzer arranged at the input end of the oxygen preprocessor monitors the operation of the electrolyzer, specifically including testing, analyzing and controlling the hydrogen in the oxygen on the oxygen side of the electrolyzer;

[0018] As a further design of the utility model, an oxygen-hydrogen analyzer arranged at the gas output end of the oxygen preprocessor detects the index results after the oxygen preprocessor has processed the gas.

[0019] Through the above technical solution, compared with the prior art, the utility model has the following beneficial effects:

[0020] 1. The online monitoring system for hydrogen concentration in oxygen during the alkaline water electrolysis hydrogen production process provided by the utility model is provided with an oxygen pre-treatment device at the oxygen side outlet of each electrolyzer, the top of which is a dehydrogenation device, and the bottom is a separation tank. After the gas-liquid separation on the oxygen side, hydrogen is removed promptly and effectively, which greatly reduces the safety risk and ensures the safe and stable operation of the entire water electrolysis hydrogen production system;

[0021] 2. The utility model provides an online monitoring system for the concentration of hydrogen in oxygen during the process of hydrogen production by alkaline water electrolysis. The input end and the gas output end of the oxygen preprocessor are respectively provided with an oxygen-hydrogen analyzer. Gas-liquid separation is first performed and then monitoring is performed. The oxygen-hydrogen analyzer at the input end plays a role in monitoring the stable operation of the electrolyzer. The oxygen-hydrogen analyzer at the gas output end plays a role in detecting the excessive hydrogen content on the oxygen side after the treatment is completed, so as to avoid the separator from stopping due to excessive hydrogen content in oxygen, and ensure the long-term stable operation of the separator.

[0022] 3. The online monitoring system for the concentration of hydrogen in oxygen during the alkaline water electrolysis hydrogen production process provided by the utility model is based on the test and control of the oxygen-hydrogen analyzer at the input end. It adjusts the circulation volume, circulation temperature and valve opening according to different loads to control the hydrogen content in oxygen, avoid the chain shutdown phenomenon caused by excessive hydrogen content, and ensure the stable operation of the water electrolysis hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 It is a schematic diagram of the overall structure of a preferred embodiment provided by the utility model;

[0025] Figure 2 It is a specific structural schematic diagram of an oxygen preprocessor in a preferred embodiment provided by the utility model.

[0026] In the figure: 1-electrolyzer, 2-oxygen pre-treatment device, 3-separation tank, 4-dehydrogenation device, 5-oxygen hydrogen analyzer, 6-pressure transmitter, 7-regulating valve. DETAILED DESCRIPTION

[0027] The utility model is now further described in detail in conjunction with the accompanying drawings. In the description of this application, it should be understood that the terms "left side", "right side", "upper part", "lower part", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second", etc. do not indicate the importance of the components, and therefore cannot be understood as a limitation on the utility model. The specific dimensions used in this embodiment are only for illustrating the technical solution by example, and do not limit the scope of protection of the utility model.

[0028] As described in the background technology, when one or more electrolyzers are connected in parallel, gas backflow may occur between the parallel electrolyzers and between the electrolyzers and separators due to pressure differences. When the hydrogen content in oxygen exceeds a certain limit, a flammable and explosive mixed gas is formed, which seriously affects the continuous operation and production of the hydrogen production system.

[0029] In order to solve the above problems, the present application provides an online monitoring system for the concentration of hydrogen in oxygen during the process of producing hydrogen by alkaline water electrolysis, the overall structure of which is as follows: Figure 1 As shown, it should be noted that this application is a monitoring system designed for several electrolytic cells arranged in parallel. Figure 1 Only one electrolyzer is used as an example, so the whole monitoring system includes several electrolyzers 1, an oxygen separator, a hydrogen separator, a lye cooler and a lye circulation pump. The oxygen side outlet of each electrolyzer is connected to the oxygen separator, the hydrogen side outlet of each electrolyzer is connected to the hydrogen separator, the oxygen separator and the hydrogen separator are connected to the lye cooler at the same time, and the lye cooled by the lye cooler is connected to the matching electrolyzer through the lye circulation pump, and each electrolyzer forms a complete circulation loop.

[0030] In order to monitor the concentration of hydrogen in oxygen at the outlet of the electrolyzer, ensure the normal and stable operation of the electrolyzer, and ensure that the hydrogen content in oxygen in the separator does not exceed the standard, an oxygen pre-processor 2 is set at the oxygen side outlet of each electrolyzer. The gas output ends of oxygen pre-processors matching the number of electrolyzers are connected to the gas phase end of the same oxygen separator, and the liquid output ends of several oxygen pre-processors are connected to the liquid phase end of the same oxygen separator. The oxygen pre-processor can also be called an online monitor of hydrogen concentration in oxygen, which consists of two parts, namely a dehydrogenation device and a separation tank 3. Figure 2 From the perspective of the dehydrogenation device 4, the dehydrogenation device 4 is located above the separation tank, and the two parts are connected from top to bottom. The separation tank is similar to a gas-liquid separator, focusing on separating the liquid and gaseous components in oxygen, and the dehydrogenation device is the part that promotes the catalytic reaction between hydrogen in oxygen and oxygen, that is, the oxygen pretreatment provided by the present application has both separation and dehydrogenation functions.

[0031] Preferably, the dehydrogenation catalyst placed in the dehydrogenation device of the present application is a palladium catalyst with titanium or other metal as a carrier. During design, the separation tank needs to condense the alkali liquid as much as possible to ensure that the service life of the dehydrogenation catalyst is extended. At the same time, considering the replacement of the dehydrogenation catalyst, the dehydrogenation device and the separation tank adopt a flange connection structure.

[0032] As a further design of the present application, an electric heater can be installed on the top of the dehydrogenation device. When the electric heater is started, the dehydrogenation catalyst in the dehydrogenation device works at a certain temperature to improve the catalytic efficiency. In order to achieve the optimal catalytic effect, the internal temperature of the dehydrogenation device is maintained at ≤200°C.

[0033] In this application, an oxygen hydrogen analyzer 5 is respectively arranged at the input end and the gas output end of the oxygen preprocessor to Figure 1Taking the oxygen preprocessor as an example, the input end of the oxygen preprocessor is the front section, and the gas output end is the back section. The oxygen-hydrogen analyzer in the front section plays the role of monitoring the stable operation of the electrolyzer, and the oxygen-hydrogen analyzer in the back section plays the role of detecting the excessive hydrogen content on the oxygen side after the treatment is completed.

[0034] It should be made clear that the components mentioned in the above system are all professional and well-known equipment in this field, and relevant personnel in this industry are all clearly aware of them, so specific equipment models are not provided for preference.

[0035] In order to ensure that the separator does not stop due to excessive hydrogen content in oxygen, the front section needs to test, analyze and control the hydrogen in oxygen. For testing and control, the present application provides a relevant control method. In order to achieve the best control result, the monitoring system provided by the present application also includes an alkali solution temperature monitor arranged at the inlet of each electrolyzer, and a check valve, a pressure transmitter 6 and a regulating valve 7 installed in sequence at the oxygen side outlet and the hydrogen side outlet of each electrolyzer. The alkali solution temperature monitor is used to monitor the temperature of the alkali solution. The check valve plays a role in preventing the gas, liquid or gas-liquid mixed fluid produced by electrolysis in the electrolyzer from flowing back. The types include but are not limited to axial flow check valves, swing check valves, lifting check valves and other valves that play a check role. The installation method includes horizontal installation or vertical installation. The pressure transmitter at the oxygen side outlet is interlocked with the pressure transmitter at the hydrogen side outlet. The opening of the oxygen side and hydrogen side regulating valves is adjusted by the pressure difference of the pressure transmitter to protect the diaphragm of the electrolyzer, prevent the diaphragm from rupturing and hydrogen and oxygen from interlacing, and ensure the safety of the electrolyzer.

[0036] During specific control, the hydrogen in oxygen analyzer installed at the input end (front section) of the oxygen preprocessor monitors the hydrogen in oxygen on the oxygen side of the electrolyzer. If the monitored hydrogen in oxygen content is ≥0.5%, the control system controls the alkali liquid circulation pump to control the alkali liquid flow until the hydrogen in oxygen content is <0.8%. The alkali liquid circulation pump controls the flow rate according to the load reduction, that is, the alkali liquid circulation volume increases according to the load reduction. When the electrolyzer load drops to the minimum, the alkali liquid circulation volume is opened to the maximum; the hydrogen in oxygen content state rises from the steady-state fluctuation to the rated value and then gradually decreases. After steady state, the load is reduced to 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, and 5% in the same operation mode in turn to complete the final low-load operation index, thereby obtaining an adjusted simulation trend chart, which is then convenient for controlling the technical safety limit of hydrogen oxide.

[0037] If the monitored hydrogen content in oxygen is ≥0.8%, the control system controls the alkali liquid cooler to adjust the alkali liquid temperature through the alkali liquid temperature monitor until the hydrogen content in oxygen is <1.0%. The alkali liquid temperature decreases as the load decreases, and the hydrogen content in oxygen rises from a steady-state fluctuation to the rated value and then gradually decreases. After steady state, the load is reduced to 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, and 5% in the same way to complete the final low-load operation index, thereby understanding the relationship trend between temperature and hydrogen content in oxygen, and then adjusting the applicability accordingly to achieve safe production.

[0038] If the monitored hydrogen content in oxygen is ≥1.0%, the control system controls the alkali solution flow rate and alkali solution temperature (the alkali solution flow rate and temperature control methods refer to the hydrogen content in oxygen ≥0.5% and hydrogen content in oxygen ≥0.8%), and controls the regulating valve and pressure transmitter at the same time. By controlling the opening of the regulating valve, the pressure difference between the pressure transmitters on both sides of the hydrogen and oxygen in the electrolyzer is adjusted to ≤3kpa until the hydrogen content in oxygen is <1.5%.

[0039] If the monitored hydrogen content in oxygen is ≥1.5%, the system will be shut down for processing.

[0040] When the control system adjusts the alkali solution circulation pump, alkali solution cooler, regulating valve and pressure transmitter, the hydrogen content detected by the oxygen-hydrogen analyzer installed at the gas output end (latter section) of the oxygen preprocessor is less than 1.5%, which can secondary avoid the phenomenon of excessive content in the electrolytic cell and chain shutdown.

[0041] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0042] The meaning of "and / or" described in this application means that the situations where each exists alone or both exist at the same time are included.

[0043] The term “connection” as used in this application may mean a direct connection between components or an indirect connection between components via other components.

[0044] Based on the above ideal embodiments of the utility model, the relevant staff can make various changes and modifications without deviating from the technical concept of the utility model through the above description. The technical scope of the utility model is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An online monitoring system for hydrogen concentration in oxygen during hydrogen production by alkaline water electrolysis, characterized in that: It includes several electrolyzers, oxygen separators, hydrogen separators, alkali liquid coolers and alkali liquid circulation pumps. The oxygen side outlet of each electrolyzer is connected to the input end of an oxygen preprocessor, the gas output ends of several oxygen preprocessors are connected to the gas phase end of the same oxygen separator, and the liquid output ends of several oxygen preprocessors are connected to the liquid phase end of the same oxygen separator; the hydrogen side outlet of each electrolyzer is connected to the hydrogen separator, the oxygen separator and the hydrogen separator are simultaneously connected to the alkali liquid cooler, and the alkali liquid cooled by the alkali liquid cooler is connected to the matching electrolyzer through the alkali liquid circulation pump; A lye temperature monitor is provided at the inlet of each electrolytic cell to monitor the temperature of the lye; A check valve, a pressure transmitter and a regulating valve are sequentially installed at the oxygen side outlet and the hydrogen side outlet of each electrolyzer; The input end and the gas output end of the oxygen preprocessor are respectively provided with oxygen-hydrogen analyzers.

2. The online monitoring system for hydrogen concentration in oxygen during hydrogen production by alkaline water electrolysis according to claim 1, characterized in that: The oxygen preprocessor comprises a dehydrogenation device and a separation tank which are interconnected, and the dehydrogenation device is located on the top of the separation tank, and the dehydrogenation device and the separation tank are detachably connected via a flange; The dehydrogenation device is used for catalytic reaction between hydrogen in oxygen and oxygen; The separation tank is used for separating liquid and gaseous oxygen.

3. The online monitoring system for hydrogen concentration in oxygen during hydrogen production by alkaline water electrolysis according to claim 2, characterized in that: An electric heater is installed on the top of the dehydrogenation device, and the electric heater is started to maintain the internal temperature of the dehydrogenation device ≤ 200°C.

4. The online monitoring system for hydrogen concentration in oxygen during hydrogen production by alkaline water electrolysis according to claim 2, characterized in that: A dehydrogenation catalyst is arranged in the dehydrogenation device, and the dehydrogenation catalyst is a palladium catalyst with titanium as a carrier.

5. The online monitoring system for hydrogen concentration in oxygen during hydrogen production by alkaline water electrolysis according to claim 1, characterized in that: The hydrogen-in-oxygen analyzer installed at the input end of the oxygen preprocessor monitors the operation of the electrolyzer, specifically including testing, analyzing and controlling the hydrogen in oxygen on the oxygen side of the electrolyzer.

6. The online monitoring system for hydrogen concentration in oxygen during hydrogen production by alkaline water electrolysis according to claim 1, characterized in that: The hydrogen-in-oxygen analyzer arranged at the gas output end of the oxygen preprocessor detects the index results after the oxygen preprocessor is processed.

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