Alkaline water electrolysis bipolar plate, electrolysis unit, electrolyzer and hydrogen production system

Abstract

The present invention discloses an alkaline water electrolysis bipolar plate, an electrolysis unit, an electrolyzer and a hydrogen production system. The bipolar plate includes: a main pole plate, a pole frame sleeved on the outer edge of the main pole plate, and a pole ear connected to the pole frame; a cooling cavity is provided in the main pole plate, and the cooling cavity liquid inlet and the cooling cavity liquid outlet extend toward the lower end surface of the main pole plate and the upper end surface of the main pole plate respectively, and respectively penetrate the channels formed by the lower end surface of the pole frame and the upper end surface of the pole frame, and form a cooling liquid channel with the cooling cavity. The water replenishment device of the hydrogen production system is connected to the electrolyte inlet in each electrolysis unit in the electrolyzer; the cooling liquid device forms a cooling liquid loop with the cooling liquid inlet, the cooling cavity, and the cooling liquid outlet. The bipolar plate structure can meet the uniform cooling requirements inside the electrolyzer, respond more quickly to temperature changes, have strong resistance to temperature shock, and reduce the manufacturing cost of the electrolyzer; the hydrogen production system does not require alkaline liquid circulation, and maintains the temperature range of each electrolysis unit by controlling the parameters of the cooling liquid.

Description

Technical Field

[0001] The present invention belongs to the technical field of alkaline water electrolysis, and in particular relates to an alkaline water electrolysis bipolar plate, an electrolysis unit, an electrolyzer and a hydrogen production system. Background Art

[0002] At present, the mainstream methods of hydrogen production include proton exchange membrane water electrolysis, anion exchange membrane water electrolysis, solar photolysis water electrolysis and alkaline water electrolysis. Among them, alkaline water electrolysis has obvious advantages in single tank large-scale and low equipment cost.

[0003] With the increase in hydrogen production demand and scale, alkaline water electrolyzers are gradually developing towards large-scale. However, with the large-scale alkaline water electrolyzer, its end diameter is also gradually increasing, which inevitably increases the number of electrolysis units (also called "electrolysis chambers"), and also causes the increase in the length of the alkaline water electrolyzer.

[0004] In traditional alkaline hydropower hydrogen production, such as Figure 1 As shown, a method of circulating alkali solution and cooling the alkali solution outside the hydrolysis tank is set up, which can not only provide the alkali solution required for hydrogen production in the electrolysis unit, but also take away the heat generated by the electrochemical reaction in the electrolysis unit. However, as the number of electrolysis units increases, the uniformity of the flow field in the electrolysis tank deteriorates, the voltage of the local electrolysis unit is too high, and the electrolysis efficiency decreases.

[0005] For this reason, there are studies on improving the bipolar plate structure. For example, patent CN116497382A provides a bipolar plate, an electrolysis unit and an electrolytic cell, wherein the bipolar plate comprises: a plate body, the plate body comprises an alkaline water electrolysis side and a cooling side, the front of the plate body corresponds to the alkaline water electrolysis side, the back of the plate body corresponds to the cooling side, the front of the plate body is arranged with an alkaline water flow area, a first liquid inlet area and a first sealing area in sequence from the center to the edge, the back of the plate body is arranged with a coolant flow area, a second liquid inlet area and a second sealing area in sequence from the center to the edge, the plate body is provided with a coolant flow port and an electrolyte flow port that penetrate the first liquid inlet area and the second liquid inlet area; and an electrical connection component connected to the peripheral side of the plate body. On the one hand, the bipolar plate can form a hydrogen evolution chamber with the hydrogen evolution electrode and the diaphragm, and the hydrogen evolution chamber can accommodate alkaline electrolyte. The bipolar plate can form an oxygen evolution chamber with the oxygen evolution electrode and the diaphragm, and the oxygen evolution chamber can accommodate alkaline electrolyte. It can change its own polarity according to different needs and participate in the process of alkaline water electrolysis. On the other hand, the bipolar plate has a cooling function, which can cool the alkaline electrolyte during operation, thereby improving the hydrogen or oxygen evolution effect.

[0006] The method of electrolyzing on one side of the bipolar plate and cooling on the other side has alleviated the problem of overheating of local electrolytic cells to a certain extent. However, this improvement has increased the number of bipolar plates, which has increased the volume of the electrolytic cell. When more electrolytic cells are stacked, it is still impossible to ensure the uniform distribution of heat and mass transfer of the alkali solution during the circulation.

[0007] Therefore, how to solve the problems of uneven temperature and uneven mass transfer inside the alkaline water electrolyzer on the basis of miniaturization and integration to achieve low-cost and high-efficiency alkaline water electrolysis hydrogen production is an urgent problem to be solved by technical personnel in this field. Summary of the invention

[0008] In view of the defects existing in the above-mentioned prior art, the present invention provides an alkaline water electrolysis bipolar plate, an electrolysis unit, an electrolyzer and a hydrogen production system. The bipolar plate specifically includes: a main pole plate, a pole frame sleeved on the outer edge of the end face of the main pole plate, and a pole ear connected to the outer edge of the pole frame; the main pole plate is provided with a built-in cooling cavity, the lower end face of the cooling cavity is provided with a cooling cavity liquid inlet, and the upper end face of the cooling cavity is provided with a cooling cavity liquid outlet, which extend from the cooling cavity liquid inlet and the cooling cavity liquid outlet to the lower end face of the main pole plate and the upper end face of the main pole plate, respectively, and respectively penetrate the channels formed by the lower end face of the pole frame and the upper end face of the pole frame, and form a cooling liquid channel with the cooling cavity. The water replenishment device in the hydrogen production system is connected to the electrolyte inlet in each electrolysis unit in the electrolyzer; the cooling liquid device forms a cooling liquid loop with the cooling liquid inlet, the cooling cavity, and the cooling liquid outlet. The bipolar plate structure can meet the uniform cooling requirements inside the electrolyzer, respond more quickly to temperature changes, have strong resistance to temperature shocks, and reduce the manufacturing cost of the electrolyzer; the hydrogen production system does not require alkaline liquid circulation, and maintains the temperature range of each electrolytic unit by controlling the parameters of the coolant.

[0009] In a first aspect, the present invention provides an alkaline water electrolysis bipolar plate, specifically comprising: a pole frame, a main pole plate and a pole ear, wherein the pole frame is sleeved on the outer edge of the end surface of the main pole plate, and the pole ear is connected to the outer edge of the pole frame;

[0010] A cooling cavity is provided in the main pole plate, a cooling cavity liquid inlet is provided on the lower end surface of the cooling cavity, and a cooling cavity liquid outlet is provided on the upper end surface of the cooling cavity;

[0011] The liquid inlet and the liquid outlet of the cooling cavity extend toward the lower end surface of the main pole plate and the upper end surface of the main pole plate respectively, and respectively penetrate the channels formed by the lower end surface and the upper end surface of the pole frame, forming a coolant channel with the cooling cavity.

[0012] Furthermore, the coolant channel includes a first coolant channel, a cooling cavity and a second coolant channel, the first coolant channel runs through the lower end surface of the pole frame from the coolant inlet, and the second coolant channel runs through the upper end surface of the pole frame from the coolant outlet;

[0013] The widths of the first coolant channel and the second coolant channel are both smaller than the width of the cooling cavity.

[0014] Furthermore, at least one side surface of the main electrode plate is a cathode and anode electrolyte flow field extending from the center to the end surface of the main electrode plate.

[0015] Furthermore, at least one electrolyte inlet is arranged on the lower end surface of the pole frame, and the electrolyte inlet is close to the side edge of the lower end surface of the pole frame.

[0016] Furthermore, at least one electrolysis gas outlet is arranged on the upper end surface of the pole frame, and the electrolysis gas outlet is close to the side edge of the upper end surface of the pole frame.

[0017] Furthermore, two electrolyte inlets are provided on the lower end surface of the pole frame, the two electrolyte inlets are respectively close to two different side edges of the lower end surface of the pole frame, and the two electrolyte inlets are respectively an anode electrolyte inlet and / or a cathode electrolyte inlet;

[0018] Two electrolysis gas outlets are arranged on the upper end surface of the pole frame, the two electrolysis gas outlets are respectively close to two different side edges of the upper end surface of the pole frame, and the two electrolysis gas outlets are respectively oxygen outlets and / or hydrogen outlets;

[0019] The oxygen outlet and the anolyte inlet are located on the same side of the pole frame, and the hydrogen outlet and the catholyte inlet are located on the same side of the pole frame.

[0020] Furthermore, the lower end surface of the pole frame is also provided with a positive and negative pole communication hole, and the positive and negative pole communication hole passes through the two side surfaces of the pole frame;

[0021] A porous diaphragm is also arranged in the connecting hole between the cathode and the anode to isolate oxygen and hydrogen.

[0022] Furthermore, the cooling cavity and the main pole plate have the same shape, both are annular, the radius ratio of the cooling cavity to the main pole plate is 0.75-0.85, and the width ratio of the cooling cavity to the main pole plate is 0.15-0.25.

[0023] Furthermore, the ratio of the radius of the pole frame to the radius of the main pole plate is 1.1 to 1.2.

[0024] In a second aspect, the present invention further provides an alkaline water electrolysis unit, specifically comprising:

[0025] A first bipolar plate, a cathode electrode, a diaphragm, an anode electrode and a second bipolar plate, wherein the first bipolar plate and the second bipolar plate are respectively arranged on both sides of the diaphragm, the cathode electrode is arranged between the first bipolar plate and the diaphragm, and the anode electrode is arranged between the second bipolar plate and the diaphragm;

[0026] The first bipolar plate and / or the second bipolar plate are the alkaline water electrolysis bipolar plates described above.

[0027] Furthermore, the width of the cooling cavity is not greater than the width interval between the main polar plates in two adjacent bipolar plates.

[0028] In a third aspect, the present invention further provides an alkaline water electrolyzer, specifically comprising: at least two alkaline water electrolysis units as described above are stacked in series, and the pole frames of adjacent electrolysis units are fixedly connected;

[0029] Both sides of the first bipolar plate and / or the second bipolar plate are adjacent electrolytic units.

[0030] In a fourth aspect, the present invention further provides an alkaline water electrolysis hydrogen production system, specifically comprising: at least one alkaline water electrolyzer as described above, a water replenishment device and a coolant device;

[0031] The water replenishing device is connected to the electrolyte inlet in each electrolytic unit in the alkaline water electrolysis tank through the first pipeline;

[0032] The coolant device is connected with the second pipeline, the coolant inlet, the cooling chamber, the coolant outlet, and the third pipeline in sequence, and the coolant device, the second pipeline, the coolant inlet, the cooling chamber, the coolant outlet, and the third pipeline form a coolant loop.

[0033] Furthermore, the cooling liquid device also includes a control structure, which controls the rate at which the cooling liquid in the cooling liquid device enters the cooling chamber according to the temperature of the electrolyte in each electrolytic unit.

[0034] Furthermore, the control structure controls the rate at which the coolant in the coolant device enters the cooling chamber according to the temperature of the electrolyte in each electrolytic unit, specifically including:

[0035] Determine the heat dissipated into the cooling chamber by each electrolytic cell, expressed as:

[0036] Q1=[k1·(πR1 2 )·ΔT1] / d

[0037] Wherein, Q1 is the heat dissipated from the electrolytic unit to the cooling chamber through the side of the bipolar plate, k1 is the heat conductivity of the side of the bipolar plate, R1 is the radius of the cathode and anode electrolyte flow field, ΔT1 is the temperature difference between the electrolyte fluid temperature in the electrolytic unit and the coolant fluid temperature in the cooling chamber, and d is the width between the outer side of the bipolar plate and the side of the cooling chamber;

[0038] Combined with the flow characteristics of the coolant, the rate at which the coolant enters the cooling chamber is given, which can be specifically expressed as:

[0039]

[0040] Wherein, h is the convective heat exchange coefficient of the coolant, R2 is the radius of the side of the cooling chamber, ΔT2 is the temperature difference between the coolant fluid temperature and the side wall temperature of the cooling chamber, k2 is the heat conductivity coefficient of the coolant, L is the height of the cooling chamber, C, m, n are all preset constants, ρ is the density of the coolant, U is the average flow rate of the coolant, μ is the dynamic viscosity of the coolant, c p is the specific heat capacity of the coolant.

[0041] The present invention provides an alkaline water electrolysis bipolar plate, an electrolysis unit, an electrolyzer and a hydrogen production system, which have at least the following beneficial effects:

[0042] (1) The bipolar plate structure provided by the present invention can meet the uniform cooling requirements inside the electrolytic cell, respond more quickly to temperature changes, have strong resistance to temperature shock, and reduce the manufacturing cost of the electrolytic cell; the hydrogen production system does not require alkaline liquid circulation, and the temperature range of each electrolytic unit is maintained by controlling the parameters of the coolant.

[0043] (2) After the electrode frame and the main electrode plate are welded, the coolant inlet and coolant outlet are processed. The coolant and the deionized water added to the anode reaction chamber and the cathode reaction chamber react and flow in their respective chambers without interfering with each other.

[0044] In addition, the mutual transmission between the solution and the hydrogen and oxygen in the electrolyte has also been weakened, and the safety and service performance of the electrolysis unit and the overall alkaline water electrolysis hydrogen production system have been improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of an alkaline water electrolysis hydrogen production system in which an alkaline water electrolysis battery stack is located in the prior art;

[0046] Figure 2 A schematic diagram of the cross-sectional structure of an alkaline water electrolysis bipolar plate provided by the present invention;

[0047] Figure 3 This is a schematic diagram of the enlarged structure of the cross-section A of an alkaline water electrolysis bipolar plate provided by the present invention;

[0048] Figure 4 This is a schematic diagram of the enlarged structure of the cross-section B of an alkaline water electrolysis bipolar plate provided by the present invention;

[0049] Figure 5 A structural diagram of a cross-section of an alkaline water electrolysis bipolar plate provided by the present invention;

[0050] Figure 6 A structural diagram of an alkaline water electrolyzer provided by the present invention;

[0051] Figure 7 A schematic diagram of an alkaline water electrolysis hydrogen production system provided by the present invention.

[0052] Description of reference numerals:

[0053] 100-bipolar plate, 110-polar frame, 111-polar frame upper end surface, 1111-oxygen outlet, 1112-hydrogen outlet, 112-polar frame lower end surface, 1121-anodic electrolyte inlet, 1122-cathodic electrolyte inlet, 1123-cathodic connecting hole, 120-main polar plate, 121-main polar plate upper end surface, 122-main polar plate lower end surface, 123-cathodic electrolyte flow field, 1 30-ear, 140-cooling chamber, 141-upper end surface of cooling chamber, 1411-liquid outlet of cooling chamber, 142-lower end surface of cooling chamber, 1421-liquid inlet of cooling chamber, 150-cooling liquid channel, 151-first cooling liquid channel, 152-second cooling liquid channel, 200-water replenishing device, 201-first pipeline, 300-cooling liquid device, 301-second pipeline, 302-third pipeline. DETAILED DESCRIPTION

[0054] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0056] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0057] As alkaline water electrolyzers are gradually enlarged, the number of electrolysis units is gradually increasing. The uniformity of the alkaline electrolyte flow field in the electrolysis unit will deteriorate, and the temperature difference caused by the heat release of the electrochemical reaction in the electrolysis unit will increase. As a result, the internal temperature and mass transfer of the alkaline water electrolyzer will become more prominent as the volume of the tank increases.

[0058] In the prior art, whether it is the circulation of alkaline solution, the cooling of alkaline solution outside the hydrolysis tank, or the structural improvement of the bipolar plate (electrolysis on one side and cooling on the other side), it still cannot meet the requirements of uniform temperature distribution and uniform mass transfer inside the alkaline water electrolysis tank.

[0059] The present invention improves the structure of the bipolar plate and sets a cooling cavity inside the main plate to form an electrolysis mode in which electrolysis is performed on both sides of the main plate and the inside is cooled. That is, during the operation of the electrolysis unit, coolant is injected into the cavity in the middle of the flow field of the main plates at both ends, so that there is a cooling cavity between every two adjacent electrolysis units. By controlling the temperature, flow rate and other parameters of the coolant in each cooling cavity, the temperature distribution inside the alkaline water electrolyzer is made more uniform.

[0060] Thirdly, according to different operating conditions, the water replenishment temperature and rate of the electrolysis unit are controlled, and the temperature and flow rate of the coolant in the cooling chamber are combined to maintain the concentration and temperature of the alkali electrolyte in the electrolysis unit within the set range. There is no need to add additional alkali cooling devices and alkali circulation devices, and the hydrogen production system of alkaline water electrolysis is also simplified, and the hydrogen production cost and the area occupied by the hydrogen production system are also reduced accordingly.

[0061] like Figure 2 -like Figure 5 As shown, the present invention provides an alkaline water electrolysis bipolar plate, specifically comprising: a pole frame 110, a main pole plate 120 and a pole ear 130, the pole frame 110 is sleeved on the outer edge of the end surface of the main pole plate 120, and the pole ear 130 is connected to the outer edge of the pole frame 110;

[0062] A cooling cavity 140 is provided in the main pole plate 120, a cooling cavity liquid inlet 1421 is provided on the lower end surface 142 of the cooling cavity, and a cooling cavity liquid outlet 1411 is provided on the upper end surface 141 of the cooling cavity;

[0063] The cooling chamber liquid inlet 1421 and the cooling chamber liquid outlet 1411 extend toward the lower end surface 122 and the upper end surface 121 of the main pole plate respectively, and respectively penetrate the channels formed by the lower end surface 112 and the upper end surface 111 of the pole frame, and form a coolant channel 150 with the cooling chamber 140.

[0064] The bipolar plate has a hollow structure, and the hollow part is a cooling cavity. During the operation of the electrolysis unit, coolant is injected into the hollow cooling cavity of the bipolar plate. The cooling liquid channel thus formed can cool two adjacent electrolysis units. By controlling the cooling liquid of multiple bipolar plates, the uniform distribution of the internal temperature of the alkaline water electrolysis cell formed by multiple electrolysis units can be ensured.

[0065] The coolant channel 150 includes a first coolant channel 151 , a cooling cavity 140 and a second coolant channel 152 . The first coolant channel 151 penetrates the lower end surface 112 of the pole frame from the coolant inlet 1421 , and the second coolant channel 152 penetrates the upper end surface 111 of the pole frame from the coolant outlet 1412 .

[0066] Three-dimensional coordinates are set around the bipolar plate structure, wherein the center point of the bipolar plate is the origin of the three-dimensional coordinates, the normal direction of the side of the bipolar plate is the Y-axis direction, the Y-axis direction is the width direction, the direction parallel to the side of the bipolar plate is the Z-axis direction, the Z-axis direction is the height direction, the direction perpendicular to the YZ plane is the X-axis direction, and the X-axis direction is the length direction.

[0067] In the width direction of the bipolar plate ( Figure 2 The width of the first coolant channel 151 and the second coolant channel 152 are both smaller than the width of the cooling cavity 140. The widths of the first coolant channel and the second coolant channel can be the same or different, and are specifically set according to different application scenarios, and are not further limited here.

[0068] In order to ensure the stability of the overall structure of the bipolar plate, welding can be used when assembling the main pole plate and the pole frame, that is, the pole frame is welded to the outer edge of the end face of the main pole plate. In addition, the cooling chamber liquid inlet, the cooling chamber liquid outlet, the first coolant channel, and the second coolant channel can be formed by drilling after the pole frame and the main pole plate are welded.

[0069] At least one side of the main electrode plate 120 is a cathode electrolyte flow field 123 extending from the center to the end surface of the main electrode plate. The cathode electrolyte flow field includes a cathode electrolyte flow field and an anode electrolyte flow field, and any side of the main electrode plate 120 can be a cathode electrolyte flow field or an anode electrolyte flow field.

[0070] That is, any side or both sides of the main electrode plate, when used as a cathode electrolyte flow field, form a cathode reaction cavity with the cathode electrode and the diaphragm; when used as an anode electrolyte flow field, form an anode reaction cavity with the anode electrode and the diaphragm.

[0071] If one side of the main electrode plate is the cathode electrolyte flow field, the other side can be the anode electrolyte flow field, or it can still be the cathode electrolyte flow field. Of course, it can also serve only as the side wall of the alkaline water electrolyzer. It is specifically set according to different application scenarios and no further limitation is made here.

[0072] At least one electrolyte inlet is provided on the lower end surface 112 of the pole frame, and the electrolyte inlet is close to the side edge of the lower end surface 112 of the pole frame. At least one electrolysis gas outlet is provided on the upper end surface 111 of the pole frame, and the electrolysis gas outlet is close to the side edge of the upper end surface 111 of the pole frame.

[0073] In one embodiment, if Figure 3 and Figure 4 As shown, two electrolyte inlets are arranged on the lower end surface 112 of the pole frame, and the two electrolyte inlets are respectively close to two different side edges of the lower end surface 112 of the pole frame, and the two electrolyte inlets are respectively an anode electrolyte inlet 1121 and / or a cathode electrolyte inlet 1122; the setting of the anode electrolyte inlet 1121 and the cathode electrolyte inlet 1122 is related to the application scenario, and is set to the cathode electrolyte inlet 1122 when corresponding to the cathode electrolyte flow field, and is set to the anode electrolyte inlet 1121 when corresponding to the anode electrolyte flow field.

[0074] Two electrolysis gas outlets are arranged on the upper end surface 111 of the pole frame, and the two electrolysis gas outlets are respectively close to two different side edges of the upper end surface 111 of the pole frame, and the two electrolysis gas outlets are respectively oxygen outlets and / or hydrogen outlets; the settings of the oxygen outlet 1111 and the hydrogen outlet 1112 are related to the application scenario, and are set to the hydrogen outlet 1112 when corresponding to the cathode electrolyte flow field, and are set to the oxygen outlet 1111 when corresponding to the anode electrolyte flow field.

[0075] The oxygen outlet 1111 and the anolyte inlet 1121 are located on the same side of the pole frame, and the hydrogen outlet 1112 and the catholyte inlet 1122 are located on the same side of the pole frame.

[0076] That is, for each electrolytic unit, an anolyte inlet and a cathode electrolyte inlet are arranged on the lower end surface of the pole frame, an oxygen outlet and a hydrogen outlet are arranged on the upper end surface of the pole frame, the side surface of the main pole plate can provide an anolyte flow field or a cathode electrolyte flow field, and the middle area of ​​the bipolar plate is hollowed out as a cooling chamber.

[0077] In the cathode reaction chamber, the cathode electrolyte inlet is provided on the lower end face of the pole frame, and the hydrogen outlet is provided on the upper end face of the pole frame; in the anode reaction chamber, the anode electrolyte inlet is provided on the lower end face of the pole frame, and the oxygen outlet is provided on the upper end face of the pole frame. As the inlet for replenishing deionized water to the cathode reaction chamber and the anode reaction chamber, the cathode electrolyte inlet and the anode electrolyte inlet are provided on the same end face of the pole frame, and as the gas outlet of the cathode reaction chamber and the anode reaction chamber, they are provided on the other end face of the pole frame.

[0078] For the alkaline water electrolysis unit, the following reactions occur in the anode reaction chamber:

[0079] 2OH - →2e - +H2O+1 / 2O2↑

[0080] At the anode, the hydroxide ion (OH-) loses electrons (e - ) and is oxidized into water molecules (H2O) and oxygen (O2).

[0081] The cathode reaction chamber undergoes the following reactions:

[0082] 2e - +2H2O→H2↑+2OH -

[0083] At the cathode, water molecules accept electrons (e - ) and is reduced to hydrogen (H2) and hydroxide ions (OH - ).

[0084] Overall reaction:

[0085] H2O→H2↑+1 / 2O2↑

[0086] During the entire water electrolysis process, water molecules are decomposed into hydrogen and oxygen. Hydrogen production by alkaline water electrolysis has the advantages of simple process, convenient operation, low cost, and no greenhouse gases such as CO2 are produced during the production process. The hydrogen product has high purity and can be widely used.

[0087] At the same time, after the pole frame and the main pole plate are welded, the coolant inlet and outlet are processed. The coolant and the deionized water added to the anode reaction chamber and the cathode reaction chamber react and flow in their respective chambers without interfering with each other. In addition, the mutual transmission between the solution and the hydrogen and oxygen in the electrolyte has also been weakened, and the safety and service performance of the electrolysis unit and the overall alkaline water electrolysis hydrogen production system have been improved.

[0088] In addition, if Figure 4 As shown, the lower end surface 112 of the pole frame is also provided with a cathode-cathode communication hole 1123, and the cathode-cathode communication hole 1123 passes through two side surfaces of the pole frame;

[0089] A porous diaphragm is also provided in the cathode-cathode communication hole 1123, and the porous diaphragm is used to isolate the oxygen and hydrogen generated in the anode reaction chamber and the cathode reaction chamber to avoid cross-talk.

[0090] The cathode and anode connecting holes can penetrate two adjacent electrolytic units and balance the pressure and water level in the electrolytic units on both sides of the bipolar plate.

[0091] The pole frame includes a first part located on the inner side (i.e., the inner end face) and a second part located on the outer side (i.e., the outer end face). The first part is provided with an oxygen outlet, a hydrogen outlet, an anolyte inlet, a cathode electrolyte inlet and other inlets and outlets. The second part is provided with a structure for alignment and sealing. Figure 3 , Figure 4 The second part is not shown. Figure 5 The polar frame in FIG. 1 shows the overall structure including the first part, the second part and their boundary line.

[0092] Preferably, Figure 5As shown, preferably, the cooling cavity and the main pole plate have the same shape, both are annular, the radius ratio of the cooling cavity to the main pole plate is 0.75-0.85, and the width ratio of the cooling cavity to the main pole plate is 0.15-0.25.

[0093] Furthermore, the ratio of the radius of the pole frame to the radius of the main pole plate is 1.1 to 1.2.

[0094] The pole frame sleeved on the outer edge of the end surface of the main pole plate is annular, and the side surface of the pole frame is also a circular ring structure.

[0095] In addition, under the premise of satisfying the cooling function of the electrolytic unit, the cooling chamber preferably has a narrower thickness to reduce the thickness of the bipolar plate as much as possible, thereby reducing the overall volume of the entire alkaline water electrolyzer.

[0096] For example, in one embodiment, the electrolyte in the electrolytic unit is a KOH solution with a concentration range of 27-30 wt.%, and the coolant is tap water.

[0097] When the electrolysis unit operates at low electrical density, the rate of deionized water consumption of the electrolyte and the temperature rise rate caused by the water electrolysis reaction are both slow, and the rate of replenishing deionized water into the electrolysis unit from the anode electrolyte inlet and the cathode electrolyte inlet and the flow rate of the coolant in the coolant channel are both set to lower values.

[0098] When the electrolysis unit operates at low electrical density, the rate of deionized water consumption of the electrolyte and the temperature rise rate caused by the water electrolysis reaction are both fast. The rate of replenishing deionized water into the electrolysis unit from the anode electrolyte inlet and the cathode electrolyte inlet and the flow rate of the coolant in the coolant channel are set to higher values.

[0099] The present invention also provides an alkaline water electrolysis unit, which specifically comprises:

[0100] A first bipolar plate, a cathode electrode, a diaphragm, an anode electrode and a second bipolar plate, wherein the first bipolar plate and the second bipolar plate are respectively arranged on both sides of the diaphragm, the cathode electrode is arranged between the first bipolar plate and the diaphragm, and the anode electrode is arranged between the second bipolar plate and the diaphragm;

[0101] The first bipolar plate and / or the second bipolar plate are the alkaline water electrolysis bipolar plates described above.

[0102] The width of the cooling cavity is not greater than the width interval between the main pole plates in two adjacent bipolar plates.

[0103] like Figure 6 As shown, the present invention also provides an alkaline water electrolysis cell, specifically comprising: at least two alkaline water electrolysis units as described above are stacked in series, and the pole frames of adjacent alkaline water electrolysis units are fixedly connected;

[0104] Both sides of the first bipolar plate and / or the second bipolar plate are adjacent electrolytic units.

[0105] The alkaline water electrolyzer is composed of multiple repeated electrolysis units stacked in series. In the alkaline water electrolysis units stacked in series, the pole frames of adjacent alkaline water electrolysis units are fixedly connected, and the connection method can be selected according to different application scenarios. Of course, the pole frames in multiple alkaline water electrolysis units can also be prepared in an integrated molding manner.

[0106] Similarly, in the alkaline water electrolyzer provided by the present invention, the anolyte inlet, the cathode electrolyte inlet, and the coolant inlet are arranged at the same end of the alkaline water electrolyzer, while the hydrogen outlet, the oxygen outlet, and the coolant outlet are arranged at the other end of the alkaline water electrolyzer.

[0107] like Figure 7 As shown, the present invention also provides an alkaline water electrolysis hydrogen production system, which specifically includes: at least one alkaline water electrolyzer as described above, a water replenishment device 200 and a coolant device 300;

[0108] The water replenishing device 200 is connected to the electrolyte inlets 1121 and 1122 in each electrolytic unit in the electrolytic cell through the first pipeline 201;

[0109] The coolant device 300 is connected to the second pipeline 301, the coolant inlet 1421, the cooling chamber 140, the coolant outlet 1411, and the third pipeline 302 in sequence, and the coolant device 300, the second pipeline 301, the coolant inlet 1421, the cooling chamber 140, the coolant outlet 1411, and the third pipeline 302 form a coolant loop.

[0110] The water replenishment device 200 includes a deionized water device, a first water storage tank and a water replenishment pump, and the coolant device 300 includes a second water storage tank and a coolant circulation pump. The deionized water device, the first water storage tank, the water replenishment pump, the first pipeline, the electrolyte inlet, and the anode / cathode reaction chamber form a water replenishment channel, and the second water storage tank, the coolant circulation pump, the second pipeline, the coolant inlet, the cooling chamber, the coolant outlet, and the third pipeline form a coolant loop.

[0111] In the alkaline water electrolysis hydrogen production system, the temperature and alkali concentration in the alkaline water electrolyzer can be maintained within the set value range under the action of the water replenishment channel and the coolant loop, and the temperature distribution in the alkaline water electrolyzer is also more uniform. Therefore, the alkaline water electrolysis hydrogen production system does not have an alkali solution cooling device and an alkali solution circulation device.

[0112] In addition, the alkaline water electrolysis hydrogen production system also includes a hydrogen cooling device, a purification device, and an oxygen collection device.

[0113] The hydrogen cooling device is connected to the hydrogen outlet through a hydrogen pipeline. The high-temperature hydrogen becomes low-temperature hydrogen after passing through the hydrogen cooling device. The low-temperature hydrogen then enters the purification device to obtain high-purity hydrogen, which will then be provided to users.

[0114] The oxygen collecting device is connected to the oxygen outlet through a hydrogen pipeline. Of course, the oxygen generated in the alkaline water electrolysis hydrogen production system can be directly discharged from the oxygen outlet without connecting the oxygen collecting device.

[0115] In addition, the cooling liquid device also includes a control structure, which controls the rate at which the cooling liquid in the cooling liquid device enters the cooling chamber according to the temperature of the electrolyte in each electrolytic unit.

[0116] The flow rate of the coolant in the cooling chamber is set according to the cooling function. The heat taken away by the cooling chamber is the heat generated by the water electrolysis reaction in the anode reaction chamber and the cathode reaction chamber.

[0117] First, the heat load needs to be determined. The total heat load generated by the water electrolysis reaction outside the bipolar plate is determined, that is, the heat that needs to be removed.

[0118] Then, the control structure controls the rate at which the coolant in the coolant device enters the cooling chamber according to the temperature of the electrolyte in each electrolytic unit, specifically including:

[0119] Determine the heat dissipated into the cooling chamber by each electrolytic cell, expressed as:

[0120] Q1=[k1·(πR1 2 )·ΔT1] / d

[0121] Wherein, Q1 is the heat dissipated from the electrolytic unit to the cooling chamber through the side of the bipolar plate, k1 is the heat conductivity of the side of the bipolar plate, R1 is the radius of the cathode and anode electrolyte flow field, ΔT1 is the temperature difference between the electrolyte fluid temperature in the electrolytic unit and the coolant fluid temperature in the cooling chamber, and d is the width between the outer side of the bipolar plate and the side of the cooling chamber;

[0122] Finally, combined with the flow characteristics of the coolant, the rate at which the coolant enters the cooling chamber is given, which is specifically expressed as:

[0123]

[0124] Wherein, h is the convective heat exchange coefficient of the coolant, R2 is the radius of the side of the cooling chamber, ΔT2 is the temperature difference between the coolant fluid temperature and the side wall temperature of the cooling chamber, k2 is the heat conductivity coefficient of the coolant, L is the height of the cooling chamber, C, m, n are all preset constants, ρ is the density of the coolant, U is the average flow rate of the coolant, μ is the dynamic viscosity of the coolant, c p is the specific heat capacity of the coolant.

[0125] Among them, combined with the flow characteristics of the coolant, the rate at which the coolant enters the cooling chamber is given. It is necessary to first calculate the heat Q2 taken away by the convective heat exchange based on the heat conducted to the cooling chamber. It is specifically expressed as:

[0126] Q2=h·(πR2 2 )·ΔT2

[0127] Among them, Q2 is the heat taken away by the flowing coolant in the cooling chamber.

[0128] There are two ways to determine the convection exchange coefficient h. First, empirical data, and second, analysis and calculation based on the fluid state of the coolant, as follows:

[0129] The Reynolds number is a parameter that describes the flow state and is specifically expressed as:

[0130]

[0131] The Prandtl number describes the relative rate of momentum transfer and heat transfer in a fluid, and is specifically expressed as:

[0132]

[0133] Based on the Reynolds number and combined with the Nusselt number, the convective heat transfer coefficient is given, which is specifically expressed as:

[0134]

[0135] Nu=C·R e m ·P r n

[0136] Wherein, Nu is the Nusselt number of the coolant convective heat exchange, Re is the Reynolds number, and Pr is the Prandtl number.

[0137] In the Nusselt number Nu calculation, C, m, and n are all preset constants. The values ​​of C, m, and n are related to the flow type of the coolant. That is, when the coolant is laminar, the values ​​of C, m, and n are different from those when the coolant is turbulent. Of course, in different scenarios, even if the flow type of the coolant is the same, the values ​​of C, m, and n will be different. The specific values ​​can be corrected through experiments based on the calculation.

[0138] The present invention provides an alkaline water electrolysis bipolar plate, an electrolysis unit, an electrolyzer and a hydrogen production system, which have at least the following beneficial effects:

[0139] (1) The bipolar plate structure provided by the present invention can meet the uniform cooling requirements inside the electrolytic cell, respond more quickly to temperature changes, have strong resistance to temperature shock, and reduce the manufacturing cost of the electrolytic cell; the hydrogen production system does not require alkaline liquid circulation, and the temperature range of each electrolytic unit is maintained by controlling the parameters of the coolant.

[0140] (2) After the electrode frame and the main electrode plate are welded, the coolant inlet and coolant outlet are processed. The coolant and the deionized water added to the anode reaction chamber and the cathode reaction chamber react and flow in their respective chambers without interfering with each other.

[0141] In addition, the mutual transmission between the solution and the hydrogen and oxygen in the electrolyte has also been weakened, and the safety and service performance of the electrolysis unit and the overall alkaline water electrolysis hydrogen production system have been improved.

[0142] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An alkaline water electrolysis bipolar plate, characterized in that: The bipolar plate is a hollow structure, the hollow part of which is a cooling chamber, and specifically includes: a pole frame, a main pole plate and a pole ear. The pole frame is sleeved on the outer edge of the end face of the main pole plate, and the pole ear is connected to the outer edge of the pole frame; A cooling cavity is provided in the main pole plate, the shape of the cooling cavity is consistent with that of the main pole plate, the radius ratio of the cooling cavity to the main pole plate is 0.75-0.85, the width ratio of the cooling cavity to the main pole plate is 0.15-0.25, the lower end surface of the cooling cavity is provided with a cooling cavity liquid inlet, and the upper end surface of the cooling cavity is provided with a cooling cavity liquid outlet; The coolant channel includes a first coolant channel, a cooling cavity and a second coolant channel, wherein the first coolant channel runs through the lower end surface of the pole frame from the coolant inlet, and the second coolant channel runs through the upper end surface of the pole frame from the coolant outlet, and the widths of the first coolant channel and the second coolant channel are both smaller than the width of the cooling cavity; A positive and negative pole communication hole is also arranged on the lower end surface of the pole frame, and the positive and negative pole communication hole passes through the two side surfaces of the pole frame. A porous diaphragm is also arranged in the positive and negative pole communication hole.

2. The alkaline water electrolysis bipolar plate according to claim 1, characterized in that: At least one side surface of the main electrode plate is a cathode and anode electrolyte flow field extending from the center to the end surface of the main electrode plate.

3. The alkaline water electrolysis bipolar plate according to claim 1, characterized in that: At least one electrolyte inlet is arranged on the lower end surface of the pole frame, and the electrolyte inlet is close to the side edge of the lower end surface of the pole frame.

4. The alkaline water electrolysis bipolar plate according to claim 3, characterized in that: At least one electrolysis gas outlet is arranged on the upper end surface of the pole frame, and the electrolysis gas outlet is close to the side edge of the upper end surface of the pole frame.

5. The alkaline water electrolysis bipolar plate according to claim 4, characterized in that: Two electrolyte inlets are arranged on the lower end surface of the pole frame, the two electrolyte inlets are respectively close to two different side edges of the lower end surface of the pole frame, and the two electrolyte inlets are respectively an anode electrolyte inlet and / or a cathode electrolyte inlet; Two electrolysis gas outlets are arranged on the upper end surface of the pole frame, the two electrolysis gas outlets are respectively close to two different side edges of the upper end surface of the pole frame, and the two electrolysis gas outlets are respectively oxygen outlets and / or hydrogen outlets; The oxygen outlet and the anolyte inlet are located on the same side of the pole frame, and the hydrogen outlet and the catholyte inlet are located on the same side of the pole frame.

6. An alkaline water electrolysis unit, characterized in that Specifically include: A first bipolar plate, a cathode electrode, a diaphragm, an anode electrode and a second bipolar plate, wherein the first bipolar plate and the second bipolar plate are respectively arranged on both sides of the diaphragm, the cathode electrode is arranged between the first bipolar plate and the diaphragm, and the anode electrode is arranged between the second bipolar plate and the diaphragm; The first bipolar plate and / or the second bipolar plate is an alkaline water electrolysis bipolar plate as claimed in any one of claims 1 to 5.

7. The alkaline water electrolysis unit according to claim 6, characterized in that: The width of the cooling cavity is not greater than the width interval between the main pole plates in two adjacent bipolar plates.

8. An alkaline water electrolyzer, characterized in that: Specifically include: At least two alkaline water electrolysis units as claimed in claim 6 or 7 are stacked in series, and the pole frames of adjacent electrolysis units are fixedly connected; Both sides of the first bipolar plate and / or the second bipolar plate are adjacent electrolytic units.

9. An alkaline water electrolysis hydrogen production system, characterized in that: Specifically include: At least one alkaline water electrolyzer, water replenishment device and cooling liquid device as claimed in claim 8; The water replenishing device is connected to the electrolyte inlet in each electrolytic unit in the electrolytic cell through the first pipeline; The coolant device is connected with the second pipeline, the coolant inlet, the cooling chamber, the coolant outlet, and the third pipeline in sequence, and the coolant device, the second pipeline, the coolant inlet, the cooling chamber, the coolant outlet, and the third pipeline form a coolant loop.

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