Safety protection system of water electrolysis hydrogen production device

Abstract

The invention provides a safety protection system of a water electrolysis hydrogen production device, which comprises a safety interlocking system and a safety relief system which are arranged in an electrolytic cell unit and a gas-liquid separation unit in the water electrolysis hydrogen production device, the safety interlocking system and the safety relief system are characterized in that liquid level transmitters are respectively arranged on a hydrogen separation tank and an oxygen separation tank, and a hydrogen side pressure transmitter and an oxygen side pressure transmitter are respectively arranged on the top of the hydrogen separation tank and the top of the oxygen separation tank or a pipeline in front of a first stop valve at the downstream of the hydrogen separation tank and the oxygen separation tank; a rapid interlocking stop valve is arranged on a communication line of the hydrogen separation tank and the oxygen separation tank to realize physical isolation of hydrogen and oxygen, and a hydrogen interlocking emptying valve and an oxygen interlocking emptying valve are respectively arranged on a hydrogen side and an oxygen side; and overpressure protection equipment is respectively arranged at the tops of the hydrogen separation tank and the oxygen separation tank or on the pipeline in front of the first stop valve at the downstream. According to the system, physical isolation of hydrogen and oxygen is achieved, the safety risk of hydrogen and oxygen mixing after equipment overpressure damage is avoided, and safe operation of the system is protected.

Description

Technical Field

[0001] The present invention belongs to the chemical industry field and relates to a hydrogen production technology by electrolyzing water. Specifically, it relates to a safety protection system for a hydrogen production device by electrolyzing water. Background Art

[0002] As a clean and low-carbon new energy, hydrogen can help industries that are difficult to decarbonize achieve the goal of carbon emission reduction; hydrogen energy enriches the storage methods of renewable energy, can help renewable energy adjust energy fluctuations, promote the diversification of the energy structure and ensure the security of energy supply.

[0003] The main way of producing hydrogen from renewable energy is hydrogen production by electrolyzing water. Hydrogen production by electrolyzing water is a technology that decomposes water under the action of direct current to produce hydrogen and oxygen. The cathode reaction is a hydrogen evolution reaction, and the anode reaction is an oxygen evolution reaction. The overall reaction formula is: 2H2O = 2H2 + O2. This technology can use renewable energy electricity and does not produce emissions of CO2 and other toxic and harmful substances, thus obtaining "green hydrogen" in the true sense. Currently, there are mainly four different types of hydrogen production technologies by electrolyzing water: alkaline electrolyzed water technology (ALK), proton exchange membrane electrolyzed water technology (PEM), solid oxide electrolyzed water technology (SOEC), and alkaline anion exchange membrane electrolyzed water technology (AEM). Currently, alkaline electrolyzed water technology (ALK) and proton exchange membrane electrolyzed water technology (PEM) are the most mature.

[0004] During the process of hydrogen production by electrolyzing water, oxygen is produced simultaneously with hydrogen. Hydrogen is a flammable and explosive gas, and the explosion limit range of hydrogen is relatively wide. Once the safety measures in the utilization process are improper, hydrogen is likely to mix with oxygen and cause a fire and explosion accident. Currently, the hydrogen production device by electrolyzing water mainly consists of an electrolysis unit, a gas-liquid separation unit, a hydrogen purification unit, etc. The crude hydrogen and crude oxygen produced by the electrolysis unit are first subjected to gas-liquid separation in the gas-liquid separation unit to prepare hydrogen and oxygen. In the gas-liquid separation unit, a gas-liquid processor with the bottom of the hydrogen-oxygen separator connected is mainly used currently, and the pressure difference on both sides of the hydrogen-oxygen separator is controlled by the liquid level difference on both sides of the hydrogen-oxygen separator. It is pointed out in the national standard GB / T37563-2019 Safety Requirements for Pressure-Type Water Electrolysis Hydrogen Production Systems that for the gas-liquid treatment device with the bottom of the hydrogen-oxygen separator connected, the abnormal liquid level control system causing the mixing of hydrogen and oxygen gases is a system hazard and harmful factor in the hydrogen production system.

[0005] Patent CN114045529A proposes a method and system for hydrogen production by electrolysis. The system includes a bypass return pipeline, a liquid pump, an electrolyzer gas-liquid separator, a controller, and an alarm device. The input electrolyte is electrolyzed by the electrolyzer to generate target gases, and the generated gases are input into the gas-liquid separator. A cooler is provided in the gas-liquid separator to cool the alkaline solution output by the electrolyzer or the liquid pump. The liquid pump is used to output the electrolyte input from the liquid inlet end to the electrolyzer through the liquid outlet end, and pump at least a part of the electrolyte into the bypass return pipeline through the second connection point. A return valve is provided on the bypass return pipeline to control the flow rate of the electrolyte pumped back to the upstream of the liquid pump. The controller is used to obtain the temperature of the electrolyte in the electrolyzer and control the electrolyte temperature within a preset temperature by adjusting the liquid pump power or the electrolyte return flow rate, etc. The alarm device, connected to the controller, is used to send a warning message when the electrolyte temperature is outside the preset temperature range. This system realizes the control and warning of the system temperature by controlling the cooling amount of the alkaline solution, which helps to avoid overheating of the electrolyzer, but does not analyze and study the greatest risk of hydrogen-oxygen intermixing during the process of water electrolysis for hydrogen production.

[0006] Patent CN113621990A proposes a safety instrument system for a water electrolysis hydrogen production device. The safety instrument system includes at least: a pressure control loop, a liquid level control loop, and a temperature control loop. The pressure signal collected by the pressure transmitter is transmitted to the process control PLC through the pressure control loop and associated with the diaphragm control valve PV for adjusting the pressure of the pressure control loop. The pressure control is achieved by adjusting the opening of the control valve. The liquid level control of the separator is realized by controlling the opening of the diaphragm control valve LV through the liquid level control system. The pressure signal of the pressure transmitter is transmitted to the safety PLC through the safety instrument system. When the system pressure reaches the set threshold after the pressure control fails, the rectifier cabinet is hard-interlocked to cut off the power supply of the electrolyzer. When the liquid level signal collected by the differential pressure transmitter exceeds the set interlock range through the safety instrument system, the rectifier cabinet is hard-interlocked to cut off the power supply of the electrolyzer. This system reduces the guarantee of device safety through interlock shutdown, but fails to achieve the physical isolation of hydrogen and oxygen, and there is still a safety hazard of hydrogen and oxygen mixing. Summary of the Invention

[0007] To solve the technical problems of the risk of hydrogen-oxygen intermixing and achieve the physical isolation of hydrogen and oxygen during the process of water electrolysis for hydrogen production in the prior art, the present invention provides a safety protection system for a water electrolysis hydrogen production device.

[0008] The present invention provides a safety protection system for an electrolytic water hydrogen production device. The safety protection system includes a safety interlock system and a safety relief system provided in the electrolytic cell unit and the gas-liquid separation unit of the electrolytic water hydrogen production device. The safety interlock system and the safety relief system include level transmitters respectively provided on the hydrogen separation tank and the oxygen separation tank, and hydrogen-side pressure transmitters and oxygen-side pressure transmitters respectively provided on the pipelines at the top of the hydrogen separation tank and the oxygen separation tank or in front of the first cut-off valve downstream; a quick interlock cut-off valve is provided on the connecting line between the hydrogen separation tank and the oxygen separation tank to achieve physical isolation of hydrogen and oxygen, and a hydrogen interlock vent valve and an oxygen interlock vent valve are respectively provided on the hydrogen side and the oxygen side; overpressure protection devices are respectively provided on the pipelines at the top of the hydrogen separation tank and the oxygen separation tank or in front of the first cut-off valve downstream, and are used for emergency relief when the system is overpressured under accident conditions.

[0009] The ultra-high pressure protection device is a safety valve.

[0010] When the hydrogen separator and the oxygen separator are connected through multiple connecting lines, quick interlock cut-off valves need to be provided on each connecting line.

[0011] The electrolytic cell unit includes a transformer, a rectifier, and an alkaline electrolytic cell.

[0012] A rectifier is provided between the transformer and the electrolytic cell to supply power to the electrolytic cell. The electrolytic cell, the rectifier, and the transformer include various combinations such as one-to-one, many-to-one, and many-to-many.

[0013] The gas-liquid separation unit includes a filter, a circulation pump, a circulation cooler, a quick interlock cut-off valve, an oxygen separation tank, a hydrogen separation tank, a first oxygen cooler, a first hydrogen cooler, an oxygen safety valve, a hydrogen safety valve, an oxygen scrubber, a hydrogen scrubber, a second oxygen cooler, a second hydrogen cooler, an oxygen liquid separation tank, a hydrogen liquid separation tank, an oxygen interlock vent valve, a hydrogen interlock vent valve, a hydrogen flame arrester, a product hydrogen valve, a product oxygen valve, an oxygen-side pressure transmitter, a hydrogen-side pressure transmitter, an oxygen-side level transmitter, and a hydrogen-side level transmitter.

[0014] The safety interlock system includes an oxygen-side level transmitter, a hydrogen-side level transmitter, an oxygen-side pressure transmitter, a hydrogen-side pressure transmitter, a controller, a quick interlock cut-off valve, an oxygen interlock vent valve, a hydrogen interlock vent valve, and a rectifier.

[0015] The safety relief system includes an oxygen safety valve, a hydrogen safety valve, an oxygen-side pressure transmitter, a hydrogen-side pressure transmitter, a controller, a quick interlock cut-off valve, an oxygen interlock vent valve, a hydrogen interlock vent valve, and a rectifier, etc.

[0016] The working principle of the safety protection system for the electrolytic water hydrogen production device provided by the present invention is as follows:

[0017] The process parameters of the electrolytic water hydrogen production process are controlled by the basic process control system. When the basic process control system fails to effectively control the system liquid level and the liquid levels of the hydrogen separation tank or the oxygen separation tank seriously deviate from the normal values, the liquid level transmitter transmits the liquid level signal to the controller, and through the controller, the rectifier cabinet is interlocked to stop and the power supply of the electrolytic cell is cut off, and the quick interlock cut-off valve is interlocked to close to achieve the physical isolation of hydrogen and oxygen.

[0018] When the basic process control system fails to effectively control the system pressure and the pressures of the hydrogen separation tank or the oxygen separation tank seriously deviate from the normal values, the pressure transmitter transmits the pressure signal to the controller, and through the controller, the rectifier cabinet is interlocked to stop and the power supply of the electrolytic cell is cut off, the quick interlock cut-off valve is interlocked to close, and the interlock vent valves on the hydrogen side and the oxygen side are interlocked to open to achieve the safe pressure relief of the system.

[0019] When the basic process control system fails to effectively control the system pressure, the system pressure relief is achieved through the safety interlock system. When an accident condition occurs and the safety interlock system fails to achieve the quick pressure relief of the system, the emergency relief is achieved through the safety valves on the hydrogen side and the oxygen side or other overpressure protection devices.

[0020] The present invention has the following beneficial effects:

[0021] 1) A quick interlock cut-off valve is arranged on the bottom connecting line of the hydrogen separation tank and the oxygen separation tank, and it quickly closes when an interlock action occurs to achieve the physical isolation of hydrogen and oxygen, preventing explosion due to the mixing of hydrogen and oxygen.

[0022] 2) Liquid level transmitters are arranged on the hydrogen separation tank and the oxygen separation tank, and pressure transmitters are respectively arranged on the top of the hydrogen separation tank and the oxygen separation tank or on the pipeline before the first cut-off valve downstream; interlock vent valves are arranged on both the hydrogen side and the oxygen side; the liquid level signals of the liquid level transmitters are sent to the controller. When the system liquid level is abnormal, the rectifier cabinet is interlocked to stop and the power supply of the electrolytic cell is cut off, and the quick interlock cut-off valve is interlocked to close to achieve the physical isolation of hydrogen and oxygen; the pressure signals of the pressure transmitters are sent to the controller. When the system pressure is abnormal, the rectifier cabinet is interlocked to stop and the power supply of the electrolytic cell is cut off through the controller, the quick interlock cut-off valve is interlocked to close, and the interlock vent valves on the hydrogen side and the oxygen side are interlocked to open to achieve the safe pressure relief of the system, protecting the safe long-term operation of the system and improving the efficiency.

[0023] 3) Overpressure protection devices are respectively arranged on the top of the hydrogen separation tank and the oxygen separation tank or on the pipeline before the first cut-off valve downstream. When an accident condition occurs, the physical isolation of hydrogen and oxygen is achieved through the quick interlock cut-off valve, and the hydrogen and oxygen in the system are timely vented through the overpressure protection devices, avoiding the safety risk of hydrogen-oxygen mixing after the equipment is damaged by overpressure. Description of the Drawings

[0024] Figure 1 Schematic diagram of the process of the present invention;

[0025] Figure 2 Schematic diagram of the safety interlock system.

[0026] In the figure: 1 - transformer, 2 - rectifier, 3 - alkaline electrolyzer, 4 - filter, 5 - circulation pump, 6 - circulation cooler, 7 - quick interlock cut-off valve, 8 - oxygen separation tank, 9 - hydrogen separation tank, 10 - No. 1 oxygen cooler, 11 - No. 1 hydrogen cooler, 12 - oxygen safety valve, 13 - hydrogen safety valve, 14 - oxygen scrubber, 15 - hydrogen scrubber, 16 - No. 2 oxygen cooler, 17 - No. 2 hydrogen cooler, 18 - oxygen liquid separation tank, 19 - hydrogen liquid separation tank, 20 - oxygen interlock vent valve, 21 - hydrogen interlock vent valve, 22 - hydrogen flame arrester, 23 - product hydrogen valve, 24 - product oxygen valve, 25 - oxygen side pressure transmitter, 26 - hydrogen side pressure transmitter, 27 - oxygen side level transmitter, 28 - hydrogen side level transmitter, 29 - controller; A - electrolyzer unit, B - gas-liquid separation unit, C - safety interlock system, D - safety relief system. Specific embodiments

[0027] The present invention will be further described below with reference to the accompanying drawings.

[0028] As Figures 1-2 shown, the present invention discloses a safety protection system for an electrolytic water hydrogen production device. The safety protection system includes a safety interlock system C and a safety relief system D provided in the electrolyzer unit A and the gas-liquid separation unit B of the electrolytic water hydrogen production device. The safety interlock system C and the safety relief system D include level transmitters provided on the hydrogen separation tank 9 and the oxygen separation tank 8, and hydrogen side pressure transmitter 26 and oxygen side pressure transmitter 25 are respectively provided on the pipelines at the top of the hydrogen separation tank 9 and the oxygen separation tank 8 or in front of the first cut-off valve downstream; a quick interlock cut-off valve 7 is provided on the connecting line between the hydrogen separation tank 9 and the oxygen separation tank 18 to achieve physical isolation of hydrogen and oxygen, and a hydrogen interlock vent valve 21 and an oxygen interlock vent valve 20 are respectively provided on the hydrogen side and the oxygen side; hydrogen safety valve 13 and oxygen safety valve 12 are respectively provided on the pipelines at the top of the hydrogen separation tank and the oxygen separation tank or in front of the first cut-off valve downstream, for emergency relief in case of system overpressure under accident conditions.

[0029] The electrolyzer unit includes a transformer 1, a rectifier 2, and an alkaline electrolyzer 3, which successively convert external power into the direct current required by the electrolyzer, and electrolyze to produce crude hydrogen and crude oxygen under the action of a direct current voltage. The gas-liquid separation unit includes a filter 4, a circulation pump 5, a circulation cooler 6, a quick interlock cut-off valve 7, an oxygen separation tank 8, a hydrogen separation tank 9, a first oxygen cooler 10, a first hydrogen cooler 11, an oxygen safety valve 12, a hydrogen safety valve 13, an oxygen scrubber 14, a hydrogen scrubber 15, a second oxygen cooler 16, a second hydrogen cooler 17, an oxygen liquid separation tank 18, a hydrogen liquid separation tank 19, an oxygen interlock vent valve 20, a hydrogen interlock vent valve 21, a hydrogen flame arrester 22, a product hydrogen valve 23, a product oxygen valve 24, an oxygen-side pressure transmitter 25, a hydrogen-side pressure transmitter 26, an oxygen-side liquid level transmitter 27, and a hydrogen-side liquid level transmitter 28.

[0030] The safety interlock system includes the oxygen-side liquid level transmitter 27, the hydrogen-side liquid level transmitter 28, the oxygen-side pressure transmitter 25, the hydrogen-side pressure transmitter 26, a controller 29, the quick interlock cut-off valve 7, the oxygen interlock vent valve 20, the hydrogen interlock vent valve 21, and the rectifier 2, etc.

[0031] Under normal operating conditions, the process parameters of the hydrogen production process by electrolyzing water are controlled by the basic process control system. When the basic process control system fails to effectively control the system liquid level and the liquid levels of the hydrogen separation tank 9 or the oxygen separation tank 8 seriously deviate from the normal values, the hydrogen-side liquid level transmitter 28 or the oxygen-side liquid level transmitter 27 transmits the liquid level signal to the controller 29, and the rectifier cabinet 2 is interlocked to stop and cut off the power supply of the alkaline electrolyzer 3, and the quick interlock cut-off valve 7 is interlocked to close to achieve the physical isolation of hydrogen and oxygen.

[0032] Under normal operating conditions, the process parameters of the hydrogen production process by electrolyzing water are controlled by the basic process control system. When the basic process control system fails to effectively control the system pressure and the pressures of the hydrogen separation tank 9 or the oxygen separation tank 8 seriously deviate from the normal values, the hydrogen-side pressure transmitter 26 or the oxygen-side pressure transmitter 25 transmits the pressure signal to the controller, and the rectifier cabinet 2 is interlocked to stop and cut off the power supply of the alkaline electrolyzer 3, the quick interlock cut-off valve 7 is interlocked to close, and the hydrogen-side interlock vent valve 21 and the oxygen-side interlock vent valve 20 are interlocked to open to achieve the safe pressure relief of the system.

[0033] The safety relief system includes the oxygen safety valve 12, the hydrogen safety valve 13, the oxygen-side pressure transmitter 25, the hydrogen-side pressure transmitter 26, the controller 29, the quick interlock cut-off valve 7, the oxygen interlock vent valve 20, the hydrogen interlock vent valve 21, and the rectifier 2, etc.

[0034] Under normal operating conditions, the process parameters of the electrolytic water hydrogen production process are controlled by the basic process control system. When the basic process control system fails to effectively control the system pressure, the system is depressurized through the safety interlock system. When an accident occurs, the safety interlock system fails to quickly depressurize the system, and emergency relief is achieved through the hydrogen safety valve 13 and the oxygen safety valve 12.

[0035] The above are only typical embodiments of the present invention, and there is no any formal limitation on the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, the changes or modifications made using the above content should be regarded as equivalent examples of equivalent changes. Any equivalent changes made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A safety protection system for an electrolytic water hydrogen production device, characterized in that: The safety protection system includes a safety interlock system and a safety relief system provided in the electrolyzer unit and the gas-liquid separation unit of the water electrolysis hydrogen production device. The safety interlock system and the safety relief system include level transmitters respectively provided on the hydrogen separation tank and the oxygen separation tank, and hydrogen-side pressure transmitters and oxygen-side pressure transmitters respectively provided on the pipelines at the top of the hydrogen separation tank and the oxygen separation tank or in front of the first cut-off valve downstream; a quick interlock cut-off valve is provided on the connecting line between the hydrogen separation tank and the oxygen separation tank to achieve physical isolation of hydrogen and oxygen, and a hydrogen interlock vent valve and an oxygen interlock vent valve are respectively provided on the hydrogen side and the oxygen side; overpressure protection devices are respectively provided on the pipelines at the top of the hydrogen separation tank and the oxygen separation tank or in front of the first cut-off valve downstream, for emergency relief when the system is overpressurized under accident conditions.

2. The safety protection system of the electrolytic water hydrogen production device according to claim 1, wherein: The ultra-high pressure protection device is a safety valve.

3. The safety protection system of the electrolytic water hydrogen production device according to claim 1, characterized in that: When the hydrogen separator and the oxygen separator are connected by multiple connecting lines, a quick interlock cut-off valve is provided on each connecting line.

4. The safety protection system of the electrolytic water hydrogen production device according to claim 1, wherein: The electrolyzer unit includes a transformer, a rectifier, and an alkaline electrolyzer.

5. The safety protection system of the electrolytic water hydrogen production device according to claim 1, characterized in that: A rectifier is provided between the transformer and the electrolyzer to supply power to the electrolyzer. The electrolyzer, the rectifier, and the transformer include various combinations such as one-to-one, many-to-one, and many-to-many.

6. The safety protection system of the electrolytic water hydrogen production device according to claim 1, wherein: The gas-liquid separation unit includes a filter, a circulation pump, a circulation cooler, a quick interlock cut-off valve, an oxygen separation tank, a hydrogen separation tank, a first oxygen cooler, a first hydrogen cooler, an oxygen safety valve, a hydrogen safety valve, an oxygen scrubber, a hydrogen scrubber, a second oxygen cooler, a second hydrogen cooler, an oxygen liquid separation tank, a hydrogen liquid separation tank, an oxygen interlock vent valve, a hydrogen interlock vent valve, a hydrogen flame arrester, a product hydrogen valve, a product oxygen valve, an oxygen-side pressure transmitter, a hydrogen-side pressure transmitter, an oxygen-side level transmitter, a hydrogen-side level transmitter, and a controller.

7. The safety protection system of the electrolytic water hydrogen production device according to claim 1, wherein: The safety interlock system includes an oxygen-side level transmitter, a hydrogen-side level transmitter, an oxygen-side pressure transmitter, a hydrogen-side pressure transmitter, a controller, a quick interlock cut-off valve, an oxygen interlock vent valve, a hydrogen interlock vent valve, and a rectifier.

8. The safety protection system of the electrolytic water hydrogen production device according to claim 1, characterized in that: The safety relief system includes an oxygen safety valve, a hydrogen safety valve, an oxygen-side pressure transmitter, a hydrogen-side pressure transmitter, a controller, a quick interlock cut-off valve, an oxygen interlock vent valve, a hydrogen interlock vent valve, and a rectifier.

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