PEM electrolytic bath resistant to high pressure and differential pressure and control method thereof

Abstract

The invention relates to the technical field of fuel cells, and discloses a high pressure and differential pressure resistant PEM electrolytic bath and a control method thereof. The high-pressure-resistant and pressure-difference-resistant PEM electrolytic cell is composed of a CCM, a protection ring, a pressure bearing plate, a flow field plate, a supporting plate, a pressure regulating plate, a sealing ring and an end plate, and parts on the two sides of a cathode and an anode are the same. When the electrolytic cell works under high pressure or high pressure difference, the pressure regulating plate can internally balance the pressure on the two sides of the cathode and the anode, so that the CCM is prevented from being damaged. When the electrolytic bath runs, the inlet and outlet pressure difference and impedance of the cathode and anode steam-water separator are monitored in real time, whether the running condition of the electrolytic bath is normal or not is judged, an impedance monitoring result is compared with a pressure difference monitoring result, and cathode and anode pressure and temperature are actively adjusted to guarantee safe and efficient running of the electrolytic bath.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a high-pressure and differential-pressure resistant PEM electrolyzer and its control method. Background Art

[0002] Proton exchange membrane (PEM) electrolysis technology is an efficient method for water electrolysis to produce hydrogen. It uses a proton exchange membrane as the electrolyte, where oxidation-reduction reactions occur at the anode and cathode respectively to generate hydrogen and oxygen. Compared with traditional alkaline electrolysis technology, PEM electrolysis technology is particularly suitable for integration with renewable energy due to its advantages of high current density, fast response, and compact structure. The core advantages of this technology lie in high-purity hydrogen production, fast startup, and strong adaptability, making PEM electrolyzers an important technology in the field of renewable energy hydrogen production.

[0003] Currently, the working pressure of mainstream PEM electrolyzers is less than 3 MPa, and it is often difficult to directly obtain a relatively high hydrogen pressure from the electrolyzer. Since the hydrogen density is too low under normal temperature and low pressure conditions, it is usually necessary to additionally use a hydrogen compressor to boost the outlet of the electrolyzer to a high pressure value for hydrogen storage and transportation. Therefore, existing water electrolysis hydrogen production systems still have problems such as large overall equipment volume, complex structure, high energy consumption, poor reliability, and low electrolysis efficiency; developing and designing a high-pressure electrolysis technology has important practical significance. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-pressure and differential-pressure resistant PEMFC electrolyzer and its control method, to solve one or more technical problems existing in the prior art, and to provide at least one beneficial choice or create conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions.

[0006] A high-pressure and differential-pressure resistant PEM electrolyzer includes an electrolysis chamber and a catalyst-coated membrane that divides the cathode chamber and anode chamber of the electrolysis chamber; the cathode chamber and the anode chamber are respectively arranged on two end plates, and a protective ring, a pressure-bearing plate, a flow field plate, a support plate, and a pressure regulating plate are sequentially arranged in the cathode chamber and the anode chamber. The protective ring is connected to the catalyst-coated membrane, and the pressure regulating plate is connected to the end plate.

[0007] The catalyst-coated membrane comprises a proton exchange membrane and catalytic layers provided on both sides of the proton exchange membrane; an electrolysis reaction occurs on the catalyst-coated membrane; the protective ring is used to protect the proton exchange membrane from damage caused by shear stress generated by the pressure difference in the cell; the pressure-bearing plate is a titanium felt for bearing pressure; the flow field plate is a titanium mesh group composed of 2-4 titanium meshes; the support plate is made of titanium and is used to evenly distribute the pressing force generated by the pressure-adjusting plate on the flow field plate; the pressure-adjusting plate is made of titanium in a sinusoidal elastic shape and is used to provide an internal interlayer pressing force to press the pressure-adjusting plate, the flow field plate, the pressure-bearing plate, the protective ring and the catalyst-coated membrane from the inside and balance the pressures on both the anode and cathode sides of the catalyst-coated membrane.

[0008] More preferably, the end plates are made of stainless steel, and corresponding current collector plates are respectively installed on the two end plates for accessing the electrolysis voltage; one anode flow channel inlet and two anode flow channel outlets communicating with the anode chamber are provided on the anode end plate, and one cathode flow channel inlet and two cathode flow channel outlets communicating with the cathode chamber are provided on the cathode end plate; the anode flow channel inlet and the cathode flow channel inlet are oppositely arranged.

[0009] More preferably, corresponding connection holes are provided on the anode end plate and the cathode end plate, and the anode end plate and the cathode end plate are connected and fixed by bolts and nuts passing through the connection holes.

[0010] More preferably, a sealing ring is provided between the end plate and the catalyst-coated membrane.

[0011] More preferably, the porosity of the bearing plate is 20%-60%, the pore diameter is 2±0.5 microns and the proportion of pores with a pore diameter of 2 microns is greater than 80%, and the thickness of the titanium felt is 0.3 mm - 1.5 mm.

[0012] More preferably, in the flow field plate, the mesh number of a single-layer titanium mesh is 30-300 meshes, and the wire diameter of the titanium mesh is 0.1 mm - 0.5 mm.

[0013] More preferably, the thickness of the support plate is 1-2 mm.

[0014] More preferably, the thickness of the pressure-adjusting plate is 1-2 mm, the waveform amplitude of the sine wave of the pressure-adjusting plate is 0.5-2 mm, and the waveform angular frequency is 1-4.

[0015] More preferably, the flow channel surfaces of the pressure-bearing plate, the flow field plate, the support plate, the pressure-adjusting plate and the end plate are all platinum-plated.

[0016] On the other hand, the present invention also provides a control method for a high-pressure and differential-pressure-resistant PEM electrolyzer, which is used to control a high-pressure and differential-pressure-resistant PEM electrolyzer as described above.

[0017] When the high-pressure and differential-pressure resistant PEM electrolyzer operates normally, performance calibration is carried out in advance; at different working points of cell voltage, differential pressure and temperature, the voltage is adjusted by perturbation at different frequencies, the interlayer comprehensive impedance relationship is monitored, the impedance change relationship at different working points is obtained, and the allowable impedance fluctuation threshold is set accordingly; the anode-cathode pressure difference threshold is set.

[0018] When the high-pressure and differential-pressure resistant PEM electrolyzer is operating, the voltage is periodically adjusted by perturbation at different frequencies, the impedance change relationship is monitored, and the anode-cathode pressure difference is monitored in real time. When the monitored impedance exceeds the impedance fluctuation threshold or the anode-cathode pressure difference exceeds the anode-cathode pressure difference threshold, the working pressure of the PEM electrolyzer is adjusted to make the measured impedance return to normal, or the working temperature of the PEM electrolyzer is adjusted to reduce the working impedance of the electrolyzer.

[0019] The present invention adopts the above technical solutions and has at least the following beneficial effects.

[0020] First, for the PEM electrolyzer provided by the present invention, by arranging a protective ring, a bearing plate, a flow field plate, a support plate and a pressure regulating plate between the catalyst coated membrane and the end plate, the high-pressure and differential-pressure resistance capabilities of the electrolyzer can be effectively improved; through actual tests, the electrolyzer in the present invention can withstand a pressure and pressure difference of 20 MPa, avoiding cracks in the CCM and titanium felt due to overpressure. The output of high-pressure gas, in addition to reducing the compression energy consumption, the water vapor in the generated gas under high-pressure electrolysis will condense, reducing the gas drying cost. The designed high-pressure and differential-pressure resistant PEM electrolyzer and its control method in the present invention contribute to improving the efficiency of the hydrogen production system.

[0021] Second, the present invention combines impedance monitoring technology and differential pressure detection technology, which can better avoid the damage problem of the electrolyzer caused by excessive pressure. The impedance monitoring system in the present invention can also timely identify the problem of uneven pressure occurring during the operation of the electrolyzer and take corresponding measures in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure shows a schematic structural diagram of a high-pressure and differential-pressure resistant PEM electrolyzer in an embodiment of the present invention.

[0023] Figure 2 Shown as Figure 1 The structural schematic diagram from another perspective.

[0024] Figure 3 The figure shows an exploded view of the structure of a high-pressure and differential-pressure resistant PEM electrolyzer in an embodiment of the invention.

[0025] Description of the reference numerals.

[0026] 1: Catalyst Coated Membrane, 2: Protective Ring, 3: Bearing Plate, 4: Flow Field Plate, 5: Support Plate, 6: Pressure Regulating Plate, 7: Sealing Ring, 8: End Plate, 9: Current Collector Plate, 10: Anode Flow Channel Inlet, 11: Anode Flow Channel Outlet, 12: Cathode Flow Channel Inlet, 13: Cathode Flow Channel Outlet, 14: Bolt, 15: Nut.

[0027] 1-1: Catalytic Layer. Detailed Implementation Manner

[0028] The following further describes the detailed implementation manner of the present invention in combination with the accompanying drawings of the specification, making the technical solution and its beneficial effects of the present invention clearer and more definite. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0029] The additional aspects and advantages of the present invention will become apparent in the following description section, or be learned through the practice of the present invention. Embodiment

[0030] Referring to Figures 1-3 As shown, a high-pressure and differential pressure resistant PEM electrolyzer includes an electrolysis chamber and a Catalyst Coated Membrane (CCM) 1 that divides the cathode chamber and the anode chamber of the electrolysis chamber; the cathode chamber and the anode chamber are respectively arranged on two end plates 8, and a protective ring 2, a bearing plate 3, a flow field plate 4, a support plate 5, and a pressure regulating plate 6 are sequentially connected in the cathode chamber and the anode chamber. The protective ring 2 is connected to the catalyst coated membrane 1, the pressure regulating plate 6 is connected to the end plate 8, and a sealing ring 7 is provided between the catalyst coated membrane 1 and the two end plates 8.

[0031] Among them, the catalyst coated membrane 1 includes a proton exchange membrane and catalytic layers 1-1 provided on both sides of the proton exchange membrane; the electrolysis reaction occurs on the catalyst coated membrane 1. The protective ring 2 is made of polyimide plastic material and is used to protect the proton exchange membrane from damage caused by the shear stress generated by the pressure difference in the cell. The bearing plate 3 is preferably a titanium felt, which can withstand a relatively high pressure to achieve the purpose of protecting the catalyst coated membrane 1. Preferably, the porosity of the titanium felt material is 40%, the pore diameter of the titanium felt is 2±0.5 microns and the proportion of pores with a pore diameter of 2 microns is greater than 80%, and the thickness of the titanium felt is preferably 1.0 mm. The flow field plate 4 is a titanium mesh group composed of multiple titanium meshes welded together. Preferably, the number of titanium mesh layers is 3 layers, the mesh number of a single layer of titanium mesh is 100, and the wire diameter is 0.3 mm. The support plate 5 is preferably made of titanium, which can make the pressing force generated by the pressure regulating plate 6 more evenly distributed on the flow field plate 4. Preferably, the thickness of the support plate 5 is 1 mm. The pressure regulating plate 6 is made of titanium with a sine wave elastic shape, which can provide an internal interlayer pressing force and play a role in pressing the flow field plate 4, the bearing plate 3, the protective ring 2 and the catalyst coated membrane 1 from the inside. When the electrolytic cell is operating under high pressure or high pressure difference, the pressure regulating plate 6 can also balance the pressures on both the anode and cathode sides to avoid damage to the CCM (catalyst coated membrane 1). Preferably, the thickness of the pressure regulating plate is 2 mm, the waveform amplitude of its sine wave is 1 mm, and the waveform angular frequency is 2. The sealing ring 7 is a silicone O-ring with a hardness of 50-55 Shore hardness and is used for sealing the electrolytic cell to prevent gas leakage. The end plates 8 are made of stainless steel. Corresponding current collecting plates 9 are installed on the two end plates 8 respectively to connect to the electrolysis voltage; an anode flow channel inlet 10 and two anode flow channel outlets 11 communicating with the anode electrolytic chamber are provided on the anode end plate, and a cathode flow channel inlet 12 and two cathode flow channel outlets 13 communicating with the cathode electrolytic chamber are provided on the cathode end plate. The two outlets are conducive to the outflow of gas. During assembly, the anode flow channel inlet 10 and the cathode flow channel inlet 12 are arranged opposite to each other.

[0032] In this embodiment, preferably, corresponding connection holes are provided on the anode end plate and the cathode end plate, and the anode end plate and the cathode end plate are connected and fixed by bolts 14 and nuts 15 passing through the connection holes. Obviously, those skilled in the art can adopt other existing known or future achievable connection methods to connect and fix the anode end plate and the cathode end plate according to different actual needs, which are not limited to this embodiment.

[0033] In some embodiments, the porosity of the titanium felt material for making the bearing plate 3 is appropriately selected between 20-60%, such as 20%, 30%, 50%, 60%, etc., and the thickness of the titanium felt is appropriately selected between 0.3 mm - 1.5 mm, such as 0.5 mm, 0.8 mm, 1.2 mm, etc.

[0034] In some embodiments, the titanium mesh for manufacturing the flow field plate 4 can be 1 layer or 2 layers. The mesh number of the single-layer titanium mesh can be appropriately selected between 30 and 300, such as 50 mesh, 80 mesh, 150 mesh, 200 mesh, 250 mesh, etc.; the wire diameter can be appropriately selected between 0.1 mm and 0.5 mm.

[0035] In some embodiments, the thickness of the support plate 5 can be 2 mm, the thickness of the pressure regulating plate 6 can be 1 mm, the waveform amplitude of the sine wave of the pressure regulating plate 6 can be appropriately selected between 0.5 and 2 mm, and the waveform angular frequency can be appropriately selected between 1 and 4; this is not limited to this embodiment.

[0036] Furthermore, to reduce the contact resistance, it is preferably to perform platinum plating treatment on the flow channel surfaces of the bearing plate 3, the flow field plate 4, the support plate 5, the pressure regulating plate 6, and the end plate 8.

[0037] Since the electrolytic cell is a multi-layer structure, when the pressure in the cell changes, the inter-layer contact situation changes complexly, which will cause changes in the internal impedance and thus affect the electrolysis performance. During the normal operation of the PEM electrolytic cell of the present invention, performance calibration is pre-carried out. At different working points of cell voltage, differential pressure, and temperature, the voltage is perturbed and adjusted at different frequencies, the inter-layer comprehensive impedance relationship is monitored, the impedance change relationship at different working points is obtained, and the threshold value Z of the allowable impedance fluctuation is set accordingly.

[0038] During the operation of the PEM electrolytic cell, the voltage is periodically perturbed and adjusted at different frequencies, and the monitored impedance change relationship is compared with the pre-calibrated data to judge whether the operation status of the electrolytic cell is normal.

[0039] During the operation of the PEM electrolytic cell, the pressure difference between the inlet and outlet of the anode and cathode steam-water separators is monitored in real time to judge whether the operation status of the electrolytic cell is normal. The impedance monitoring result is compared with the monitoring result of the differential pressure sensor to make a real-time judgment to ensure the normal operation of the electrolytic cell.

[0040] When the differential pressure is too high, it usually damages the CCM. Therefore, when the monitored impedance exceeds the threshold value or the pressure difference between the anode and cathode is too large, the working pressure of the PEM electrolytic cell is adjusted in time. The anode side pressure can be actively increased or the cathode side pressure can be decreased to achieve the effect of improving the contact between layers. If the measured impedance returns to normal at this time, it is considered that the CCM deformation has recovered to the allowable range, and the electrolytic cell continues to work in this state.

[0041] In addition, the working temperature of the PEM electrolytic cell can also be adjusted to reduce the working impedance of the electrolytic cell.

[0042] After experimental operation, the PEM electrolytic cell in the present invention can stably produce hydrogen at 20 MPa.

[0043] It should be noted that in the description of the present invention, for orientation terms, such as the terms "center", "horizontal", "vertical", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the indicated orientation and positional relationships are based on the orientation or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of the present invention.

[0044] In addition, for terms such as "first" and "second", they are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "at least" is one or more, unless otherwise specifically defined.

[0045] In the present invention, unless otherwise clearly specified and defined, for terms such as "assembled", "connected", and "joined", they should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may also be a mechanical connection; it can be directly connected, or connected through an intermediate medium, and can be internally connected and communicated between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the invention, unless otherwise specified and defined, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through other features therebetween. Moreover, the first feature being "above", "below", and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "above", "below", and "beneath" the second feature includes the first feature being directly below or obliquely below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0047] Through the description of the above structures and principles, those skilled in the art should understand that the present invention is not limited to the above specific embodiments. Improvements and substitutions using well-known technologies in the art based on the present invention fall within the protection scope of the present invention. The protection scope of the present invention shall be defined by each claim item and its equivalents. The parts not described in the specific embodiments are all prior art or common general knowledge.

Claims

1. A high-pressure and differential-pressure resistant PEM electrolyzer, characterized in that, It includes an electrolysis chamber and a catalyst-coated membrane that divides the cathode chamber and the anode chamber of the electrolysis chamber; The cathode chamber and the anode chamber are respectively arranged on two end plates. A protective ring, a pressure-bearing plate, a flow field plate, a support plate, and a pressure regulating plate are sequentially arranged in the cathode chamber and the anode chamber. The protective ring is connected to the catalyst-coated membrane, and the pressure regulating plate is connected to the end plate; The catalyst-coated membrane includes a proton exchange membrane and catalytic layers provided on both sides of the proton exchange membrane; the electrolysis reaction occurs on the catalyst-coated membrane; the protective ring is used to protect the proton exchange membrane from damage caused by shear stress generated by the pressure difference in the cell; the pressure-bearing plate is a titanium felt for bearing pressure; the flow field plate is a titanium mesh group composed of 2-4 titanium meshes; the support plate is made of titanium and is used to evenly distribute the pressing force generated by the pressure regulating plate on the flow field plate; the pressure regulating plate is made of titanium in a sine-wave elastic shape and is used to provide an internal interlayer pressing force to press the pressure regulating plate, the flow field plate, the pressure-bearing plate, the protective ring, and the catalyst-coated membrane from the inside and balance the pressures on both sides of the catalyst-coated membrane.

2. The high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, wherein, The end plates are made of stainless steel. Corresponding current collecting plates are respectively installed on the two end plates to connect the electrolysis voltage; an anode flow channel inlet and two anode flow channel outlets communicating with the anode chamber are provided on the anode end plate, and a cathode flow channel inlet and two cathode flow channel outlets communicating with the cathode chamber are provided on the cathode end plate; the anode flow channel inlet and the cathode flow channel inlet are arranged opposite to each other.

3. The high-pressure and differential-pressure resistant PEM electrolyzer according to claim 2, characterized in that, Corresponding connection holes are provided on the anode end plate and the cathode end plate, and the anode end plate and the cathode end plate are connected and fixed by bolts and nuts passing through the connection holes.

4. A high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, characterized in that, A sealing ring is provided between the end plate and the catalyst-coated membrane.

5. A high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, characterized in that, The porosity of the bearing plate is 20%-60%, the pore diameter is 2±0.5 microns, and the proportion of pores with a pore diameter of 2 microns is greater than 80%, and the thickness of the titanium felt is 0.3 mm - 1.5 mm.

6. A high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, characterized in that, In the flow field plate, the mesh number of a single-layer titanium mesh is 30-300 meshes, and the wire diameter of the titanium mesh is 0.1 mm - 0.5 mm.

7. A high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, wherein The thickness of the support plate is 1-2 mm.

8. A high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, characterized in that, The thickness of the pressure regulating plate is 1-2 mm, the waveform amplitude of the sine wave of the pressure regulating plate is 0.5-2 mm, and the waveform angular frequency is 1-4.

9. A high-pressure and differential-pressure resistant PEM electrolyzer according to claim 1, wherein, Platinum plating treatment is performed on the flow channel surfaces of the pressure-bearing plate, the flow field plate, the support plate, the pressure regulating plate, and the end plate.

10. A control method for a high-pressure and differential-pressure-resistant PEM electrolyzer, characterized in that, Used to control a high-pressure and differential-pressure-resistant PEM electrolysis cell as described in any one of claims 1-9; When the high-pressure and differential-pressure-resistant PEM electrolysis cell is operating normally, performance calibration is performed in advance; at different cell voltage, differential pressure, and temperature working points, the voltage is adjusted by perturbation at different frequencies, the interlayer comprehensive impedance relationship is monitored, the impedance change relationship at different working points is obtained, and the allowable impedance fluctuation threshold is set accordingly; the anode-cathode pressure difference threshold is set; During the operation of a high-voltage-resistant and differential-pressure PEM electrolyzer, the voltage is periodically adjusted with different frequencies of perturbation, the impedance change relationship is monitored, and the cathode and anode pressure difference is monitored in real time. When the monitored impedance exceeds the impedance fluctuation threshold or the cathode and anode pressure difference exceeds the cathode and anode pressure difference threshold, the working pressure of the PEM electrolyzer is adjusted to restore the measured impedance to normal, or the working temperature of the PEM electrolyzer is adjusted to reduce the working impedance of the electrolyzer.

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