Alkaline water electrolysis hydrogen production system and control method thereof

Abstract

The invention discloses an alkaline electrolytic water hydrogen production system and a control method thereof, and the control method comprises the following steps: load condition judgment: judging the load condition of an electrolytic bath according to the load parameter of the electrolytic bath; wherein if the load parameter of the electrolytic cell is in the preset low-load range, the load working condition of the electrolytic cell is judged to be a low-load working condition; and flow control: controlling the output flow of the electrolyte to be greater than the backflow flow of the electrolyte under the low-load working condition. Under the low-load working condition of the electrolytic cell, the concentration of hydrogen in the electrolyte can be reduced, and the pressure coupling relation between the electrolytic cell and the gas-liquid separator can be relieved, so that the pressure of the electrolytic cell does not need to be the same as that of the gas-liquid separator, and the pressure of the electrolytic cell is reduced under the condition that the pressure of the gas-liquid separator is not reduced; the separation of hydrogen in the electrolyte is accelerated, and the hydrogen in the electrolytic cell is inhibited from transmembrane permeation from the hydrogen side to the oxygen side, so that the hydrogen concentration in oxygen is reduced, and the lower load limit of the electrolytic cell is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by water electrolysis, and in particular to an alkaline water electrolysis hydrogen production system and a control method thereof. Background Art

[0002] As the installed capacity of renewable energy increases rapidly year by year, hydrogen energy storage is needed to meet the long-term, large-scale, cross-seasonal, and cross-space energy storage and diversified utilization needs in the transformation of renewable energy due to the strong volatility, randomness, and inconsistency of regional supply and demand of wind power and photovoltaic power generation. Water electrolysis hydrogen production technology is an irreplaceable technical means in hydrogen energy storage methods, and it is also an indispensable bridge connecting hydrogen energy and renewable energy. Alkaline water electrolysis hydrogen production has become the mainstream system for industrial hydrogen production in recent years due to its high technical maturity, long life, large scale, no use of precious metal catalysts, and low investment cost. As a mature hydrogen production method at this stage, alkaline water electrolysis has become the mainstream hydrogen production method driven by the application of hydrogen energy storage engineering.

[0003] Due to the high volatility of wind power generation and the intermittent characteristics of photovoltaic power generation during the day and night, and the long shutdown cycle and long startup time of alkaline electrolyzers, the electrolyzer system is required to maintain low current density operation within a certain time range. However, the current load limit of the alkaline water electrolysis hydrogen production system is around 40%, which is difficult to meet the needs of coupling renewable energy generation and hydrogen energy storage. Summary of the invention

[0004] The purpose of the present invention is to provide an alkaline water electrolysis hydrogen production system and a control method thereof, so as to solve the technical problem that the current alkaline water electrolysis hydrogen production system has a high load lower limit and is difficult to meet the needs of coupling renewable energy power generation and hydrogen energy storage.

[0005] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0006] The present invention provides a control method for an alkaline water electrolysis hydrogen production system, the alkaline water electrolysis hydrogen production system comprising an electrolyzer and a gas-liquid separator, the electrolyte of the electrolyzer can be output from the hydrogen side output end of the electrolyzer to the gas-liquid separator for gas-liquid separation, and the electrolyte after gas-liquid separation can flow back into the electrolyzer; the control method comprises the following steps: load condition judgment: judging the load condition of the electrolyzer according to the load parameter of the electrolyzer; wherein, if the load parameter of the electrolyzer is within a preset low load range, the load condition of the electrolyzer is judged to be a low load condition; flow control: under the low load condition, controlling the output flow rate of the electrolyte to be greater than the reflux flow rate of the electrolyte.

[0007] In an embodiment of the present invention, the control method includes the following steps: under the low load condition, measuring the pressure of the electrolytic cell, and controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte according to the pressure of the electrolytic cell, so that the pressure of the electrolytic cell meets a preset pressure range.

[0008] In an embodiment of the present invention, the preset pressure range is 5%P0≤P≤10%P0, wherein P is the pressure of the electrolytic cell and P0 is the preset rated pressure.

[0009] In an embodiment of the present invention, the load parameter includes current density; and the preset low load range is less than or equal to 40% of the rated load of the electrolytic cell.

[0010] In an embodiment of the present invention, in the load condition judgment step, if the load parameter of the electrolytic cell is within a preset high load range, the operating condition of the electrolytic cell is judged to be a high load condition; in the flow control step, under the high load condition, the reflux flow rate of the electrolyte and the output flow rate of the electrolyte are controlled to be the preset rated circulation flow rate.

[0011] In an embodiment of the present invention, the control method further includes the following steps: dynamic operating condition judgment: judging the dynamic operating condition of the electrolytic cell according to changes in the load parameters of the electrolytic cell; wherein, if the load parameters of the electrolytic cell increase, the dynamic operating condition of the electrolytic cell is judged to be a dynamic loading condition; if the load parameters of the electrolytic cell decrease, the operating condition of the electrolytic cell is judged to be a dynamic load reduction condition; under the dynamic loading condition, the reflux flow rate of the electrolyte and the output flow rate of the electrolyte are controlled to be greater than the preset rated circulation flow rate.

[0012] In an embodiment of the present invention, under the dynamic load reduction condition, the output flow rate of the electrolyte is controlled to be greater than the reflux flow rate of the electrolyte; until the load parameter of the electrolytic cell stops increasing and decreasing, the load condition judgment step and the flow control step are repeated in sequence.

[0013] In an embodiment of the present invention, under the low load condition and the dynamic load reduction condition, the output flow rate L1 of the electrolyte is equal to the preset rated circulation flow rate L0; the reflux flow rate L2 of the electrolyte and the preset rated circulation flow rate L0 have a relationship of 40% L0≤L2≤60% L0; under the dynamic loading condition, the output flow rate L1 of the electrolyte and the preset rated circulation flow rate L0 have a relationship of 105% L0≤L1≤115% L0; the reflux flow rate L2 of the electrolyte and the preset rated circulation flow rate L0 have a relationship of 105% L0≤L2≤115% L0.

[0014] In an embodiment of the present invention, the control method further comprises: in a shutdown condition, controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte to be greater than or equal to a preset rated circulation flow rate.

[0015] The present invention also provides an alkaline water electrolysis hydrogen production system, comprising an electrolytic cell and a gas-liquid separator, wherein the electrolyte in the electrolytic cell can be output from the hydrogen side output end of the electrolytic cell via an output pipeline to the gas-liquid separator for gas-liquid separation, and the electrolyte after gas-liquid separation can flow back into the electrolytic cell from the liquid output end of the gas-liquid separator via a reflux pipeline; wherein an output control device is provided on the output pipeline, and the output control device is used to control the output flow rate of the electrolyte; and a reflux control device is provided on the reflux pipeline, and the reflux control device is used to control the reflux flow rate of the electrolyte.

[0016] In an embodiment of the present invention, the output control device includes a gas-liquid two-phase pump; the reflux control device includes an electrolyte circulation pump and / or a current limiting structure.

[0017] In an embodiment of the present invention, the output control device further comprises at least one one-way valve, and the output end of the electrolytic cell is unidirectionally connected to the input end of the gas-liquid separator through the one-way valve.

[0018] In an embodiment of the present invention, the output pipeline includes a first output branch and a second output branch arranged in parallel, the input end of the first output branch and the input end of the second output branch are both connected to the output end of the electrolyzer, and the output end of the first output branch and the output end of the second output branch are both connected to the input end of the gas-liquid separator;

[0019] There are two one-way valves, which are respectively a first one-way valve and a second one-way valve. The first one-way valve is installed on the first output branch, and the gas-liquid two-phase pump and the second one-way valve are installed on the second output branch along the output direction.

[0020] In an embodiment of the present invention, a first pressure sensor is provided at the hydrogen-side output end of the electrolyzer.

[0021] In an embodiment of the present invention, the output pipeline is connected to the input end of the gas-liquid separator through a jet device, and the jet device can spray the electrolyte into the gas-liquid separator to break the bubbles in the electrolyte.

[0022] The characteristics and advantages of the present invention are:

[0023] The alkaline water electrolysis hydrogen production system and control method thereof of the present invention controls the output flow rate and the reflux flow rate of the electrolyte according to the load condition of the electrolyzer. Thus, under the low load condition of the electrolyzer, by controlling the output flow rate of the electrolyte to be greater than the reflux flow rate of the electrolyte, the electrolyte with hydrogen can flow out of the electrolyzer more quickly, and the electrolyte refluxed into the electrolyzer after hydrogen separation is reduced. On the one hand, the concentration of hydrogen in the electrolyte can be reduced, and on the other hand, the pressure coupling relationship between the electrolyzer and the gas-liquid separator can be released, so that the pressure of the electrolyzer does not need to be the same as the pressure of the gas-liquid separator, and the pressure of the electrolyzer can be reduced without reducing the pressure of the gas-liquid separator, which is conducive to accelerating the separation of hydrogen in the electrolyte and inhibiting the hydrogen in the electrolyzer from permeating across the membrane from the hydrogen side to the oxygen side, thereby reducing the hydrogen concentration in the oxygen and reducing the load lower limit of the electrolyzer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a schematic diagram of the structure of the alkaline water electrolysis hydrogen production system in the present invention.

[0026] Figure 2 It is a schematic structural diagram of an alkaline water electrolysis hydrogen production system in a specific embodiment of the present invention.

[0027] Figure 3 It is a schematic structural diagram of an alkaline water electrolysis hydrogen production system in another specific embodiment of the present invention.

[0028] In the figure:

[0029] 1. Electrolyzer; 2. Gas-liquid separator; 3. Output pipeline; 31. First output branch; 32. Second output branch; 33. First three-way valve; 34. Second three-way valve; 4. Reflux pipeline;

[0030] 5. Output control device; 51. Gas-liquid two-phase pump; 52. First one-way valve; 53. Second one-way valve;

[0031] 6. Reflux control device; 61. Electrolyte circulation pump;

[0032] 7. Jet device; 8. First pressure sensor; 9. Second pressure sensor; 10. Heat exchanger; 11. Exhaust control valve. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0034] The inventors of the present invention have found that the lower load limit of the electrolyzer is mainly restricted by the concentration of hydrogen in oxygen at low load, and the hydrogen in oxygen mainly comes from the transmembrane permeation of hydrogen from the hydrogen side to the oxygen side across the porous diaphragm, and the hydrogen that is not completely separated by the gas-liquid separator in the electrolyte mixed circulation system on the hydrogen side and the oxygen side is brought into the oxygen side of the electrolyzer by the refluxed electrolyte. Therefore, in order to reduce the concentration of hydrogen in oxygen, in addition to using a composite diaphragm or functional ion membrane with low hydrogen and oxygen permeability, it is also necessary to accelerate the separation of hydrogen in the electrolyte.

[0035] Therefore, if Figure 1 As shown, the present invention provides an alkaline water electrolysis hydrogen production system and a control method thereof, which controls the output flow rate and reflux flow rate of the electrolyte according to the load condition of the electrolyzer 1, so that under the low load condition of the electrolyzer 1, by controlling the output flow rate of the electrolyte to be greater than the reflux flow rate of the electrolyte, the electrolyte with hydrogen can flow out of the electrolyzer 1 more quickly, and the electrolyte refluxed into the electrolyzer 1 after the hydrogen is separated is reduced, which can reduce the concentration of hydrogen in the electrolyte on the one hand, and release the pressure coupling relationship between the electrolyzer 1 and the gas-liquid separator 2 on the other hand, so that the pressure of the electrolyzer 1 does not have to be the same as the pressure of the gas-liquid separator 2, and the pressure of the electrolyzer 1 is reduced without reducing the pressure of the gas-liquid separator 2, which is conducive to accelerating the separation of hydrogen in the electrolyte, and inhibiting the hydrogen in the electrolyzer 1 from the hydrogen side to the oxygen side through the membrane, thereby reducing the hydrogen concentration in the oxygen, and reducing the load lower limit of the electrolyzer 1.

[0036] Implementation Method 1

[0037] like Figure 1 As shown, the present invention provides a control method for an alkaline water electrolysis hydrogen production system, the alkaline water electrolysis hydrogen production system comprising an electrolyzer 1 and a gas-liquid separator 2, the electrolyte of the electrolyzer 1 can be output from the hydrogen side output end of the electrolyzer 1 to the gas-liquid separator 2 for gas-liquid separation, and the electrolyte after gas-liquid separation can flow back into the electrolyzer 1; the control method comprises the following steps: load condition judgment: judging the load condition of the electrolyzer 1 according to the load parameter of the electrolyzer 1; wherein, if the load parameter of the electrolyzer 1 is within a preset low load range, then the load condition of the electrolyzer 1 is judged to be a low load condition; flow control: controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte according to the load condition; wherein, under the low load condition, the output flow rate of the electrolyte is controlled to be greater than the reflux flow rate of the electrolyte.

[0038] Specifically, the load parameter includes but is not limited to current density; in some preferred embodiments of the present invention, the preset low load range is set to be less than or equal to 40% of the rated load of the electrolytic cell 1. For example, when the current density of the electrolytic cell 1 is lower than 40% of the rated current density, the load condition of the electrolytic cell 1 can be judged to be a low load condition; when the current density of the electrolytic cell 1 is lower than 35% of the rated current density, the load condition of the electrolytic cell 1 can be judged to be a low load condition. In other embodiments of the present invention, the preset low load range can also be set to other load ranges as needed.

[0039] like Figure 1 As shown, the hydrogen side output end of the electrolyzer 1 is connected to the input end of the gas-liquid separator 2 through the output pipeline 3; the liquid phase output end of the gas-liquid separator 2 is connected to the reflux input end of the electrolyzer 1 through the reflux pipeline 4. An output control device 5 is provided on the output pipeline 3, and the output control device 5 is used to control the output flow rate of the electrolyte; the reflux pipeline 4 is provided with a reflux control device 6, and the reflux control device 6 is used to control the reflux flow rate of the electrolyte. The specific structures of the electrolyzer 1 and the gas-liquid separator 2 are the same as those in the prior art and are not described here. Under low load conditions, the output flow rate of the electrolyte is increased by the reflux control device 6 and / or the reflux flow rate of the electrolyte is reduced by the reflux control device 6, so that the output flow rate of the electrolyte is greater than the reflux flow rate of the electrolyte, thereby reducing the pressure of the electrolyzer 1.

[0040] like Figure 1 As shown, in some embodiments of the present invention, under low load conditions, the output flow rate L1 of the electrolyte is equal to the preset rated circulation flow rate L0, and the reflux flow rate L2 of the electrolyte and the preset rated circulation flow rate L0 have a relationship of 40% L0≤L2≤60% L0, and preferably the reflux flow rate L2 of the electrolyte is 50% of the preset rated circulation flow rate L0. Among them, the preset rated circulation flow rate L0 is the circulation flow rate of the electrolyte of the electrolytic cell 1 under the rated load range. In other embodiments of the present invention, under low load conditions, the output flow rate L1 of the electrolyte and the reflux flow rate L2 of the electrolyte are set to meet other flow ranges as needed.

[0041] like Figure 2 As shown, after the output flow rate of the electrolyte and the reflux flow rate of the electrolyte are preliminarily adjusted under low-load conditions, in order to further reduce the lower load limit of the electrolytic cell 1, in an embodiment of the present invention, the control method includes the following steps: under low-load conditions, measuring the pressure of the electrolytic cell 1, and controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte according to the pressure of the electrolytic cell 1, so that the pressure of the electrolytic cell 1 meets the preset pressure range.

[0042] Specifically, in some preferred embodiments of the present invention, the preset pressure range is set to 5% P0 ≤ P ≤ 10% P0, where P is the pressure of the electrolyzer 1 and P0 is the preset rated pressure. In other embodiments of the present invention, the preset pressure range is set to other pressure ranges as required. The pressure of the electrolyzer 1 is measured by providing a first pressure sensor 8 at the hydrogen side output end of the electrolyzer 1.

[0043] like Figure 1 As shown, in the embodiment of the present invention, in the load condition judgment step, if the load parameter of the electrolytic cell 1 is within the preset high load range, the operating condition of the electrolytic cell 1 is judged to be a high load condition; in the flow control step, under the high load condition, the reflux flow rate of the electrolyte and the output flow rate of the electrolyte are controlled to be the preset rated circulation flow rate, that is, the electrolyte forms a rated circulation state, and the normal supply of the electrolyte in the electrolytic cell 1 is ensured.

[0044] Specifically, in some embodiments of the present invention, the preset high load range is set to be greater than or equal to 80% of the rated load of the electrolytic cell 1. For example, when the current density of the electrolytic cell 1 is higher than 80% of the rated current density, the load condition of the electrolytic cell 1 at this time can be judged to be a high load condition; when the current density of the electrolytic cell 1 is higher than 90% of the rated current density, the load condition of the electrolytic cell 1 at this time can be judged to be a high load condition. In other embodiments of the present invention, the preset high load range is set to other load ranges as needed.

[0045] like Figure 1 As shown, in order to improve the dynamic performance of the electrolytic cell 1, in an embodiment of the present invention, the control method further includes the following steps: dynamic condition judgment: judging the dynamic condition of the electrolytic cell 1 according to the change of the load parameter of the electrolytic cell 1; wherein, if the load parameter of the electrolytic cell 1 increases, the dynamic condition of the electrolytic cell 1 is judged to be a dynamic loading condition; if the load parameter of the electrolytic cell 1 decreases, the operating condition of the electrolytic cell 1 is judged to be a dynamic load reduction condition; under the dynamic loading condition, the reflux flow rate of the electrolyte is controlled to be greater than the preset rated circulation flow rate, and the output flow rate of the electrolyte is equal to the reflux flow rate of the electrolyte; under the dynamic load reduction condition, the output flow rate of the electrolyte is controlled to be greater than the reflux flow rate of the electrolyte; until the load parameter of the electrolytic cell 1 stops increasing and decreasing, the load condition judgment step and the flow control step are repeated in sequence, that is, it is judged whether the load condition of the electrolytic cell 1 is a low load condition or a high load condition, and then the reflux flow rate of the electrolyte and the output flow rate of the electrolyte are controlled according to the load condition.

[0046] Specifically, in some embodiments of the present invention, under the dynamic load reduction condition, the output flow rate L1 of the electrolyte is equal to the preset rated circulation flow rate L0, and the reflux flow rate L2 of the electrolyte has a relationship with the preset rated circulation flow rate L0: 40% L0≤L2≤60% L0, and preferably the reflux flow rate L2 of the electrolyte is 50% of the preset rated circulation flow rate L0. Under the dynamic loading condition, the output flow rate L1 of the electrolyte has a relationship with the preset rated circulation flow rate L0: 105% L0≤L1≤115% L0; the reflux flow rate L2 of the electrolyte has a relationship with the preset rated circulation flow rate L0: 105% L0≤L2≤115% L0; preferably, the output flow rate L1 of the electrolyte and the reflux flow rate L2 of the electrolyte are both 110% of the preset rated circulation flow rate L0. In other embodiments of the present invention, under the dynamic load reduction condition and the dynamic loading condition, the output flow rate L1 of the electrolyte and the reflux flow rate L2 of the electrolyte are respectively set to meet other flow ranges as needed.

[0047] In addition, if Figure 1 As shown, in an embodiment of the present invention, the control method further includes: under shutdown conditions, controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte to be greater than or equal to a preset rated circulation flow rate, thereby quickly discharging the gas in the electrolytic cell 1.

[0048] Combination Figure 2 and Figure 3 As shown, in some embodiments of the present invention, the reflux control device 6 includes an electrolyte circulation pump 61, and the preset rated circulation flow is the rated working flow of the electrolyte circulation pump 61. The electrolyte circulation pump 61 can not only provide conveying power for the circulation of the electrolyte under the rated circulation state, but also reduce the reflux flow of the electrolyte, thereby producing a throttling effect and reducing the pressure of the electrolytic cell 1. The output control device 5 includes a gas-liquid two-phase pump 51, which can increase the output flow of the electrolyte, thereby accelerating the output of the electrolyte from the hydrogen side output end to the gas-liquid separator 2 for separation, and reducing the pressure of the electrolytic cell 1.

[0049] In other embodiments of the present invention, the reflux control device 6 may not include the electrolyte circulation pump 61 but include a flow limiting structure installed on the reflux pipeline 4, such as a throttle valve or a flow control valve. Under low load conditions and dynamic load reduction conditions, the reflux flow of the electrolyte is reduced by opening the flow limiting function of the flow limiting structure, while under high load conditions, dynamic loading conditions and shutdown conditions, the flow limiting function of the flow limiting structure is closed, and the gas-liquid two-phase pump 51 is used to provide conveying power for the circulation of the electrolyte.

[0050] In some other embodiments of the present invention, the reflux control device 6 includes an electrolyte circulation pump 61 and a current limiting structure. Under low load conditions and dynamic load reduction conditions, the reflux flow of the electrolyte is reduced by turning on the current limiting function of the current limiting structure and reducing the working flow of the electrolyte circulation pump 61. Under high load conditions, dynamic loading conditions and shutdown conditions, the current limiting function of the current limiting structure is turned off, and the electrolyte circulation pump 61 is used to provide conveying power for the circulation of the electrolyte, and the gas-liquid two-phase pump 51 can be in a closed state.

[0051] In addition, in order to prevent the gas-liquid mixture in the gas-liquid separator 2 from flowing back due to the pressure difference between the gas-liquid separator 2 and the electrolytic cell 1 after the low-load condition or the dynamic load reduction condition is switched to the high-load condition or the dynamic loading condition, the output control device 5 also includes at least one one-way valve to limit the delivery direction of the electrolyte in the output pipeline 3 to prevent the electrolyte from flowing back.

[0052] Implementation Method 2

[0053] like Figure 1 As shown, the present invention also provides an alkaline water electrolysis hydrogen production system, including an electrolytic cell 1 and a gas-liquid separator 2, wherein the electrolyte in the electrolytic cell 1 can be output from the hydrogen side output end of the electrolytic cell 1 through an output pipeline 3 to the gas-liquid separator 2 for gas-liquid separation, and the electrolyte after gas-liquid separation can flow back into the electrolytic cell 1 from the liquid output end of the gas-liquid separator 2 through a reflux pipeline 4; wherein an output control device 5 is provided on the output pipeline 3, and the output control device 5 is used to control the output flow rate of the electrolyte; and a reflux control device 6 is provided on the reflux pipeline 4, and the reflux control device 6 is used to control the reflux flow rate of the electrolyte.

[0054] The alkaline water electrolysis hydrogen production system of the present invention is controlled by the control method in the first embodiment. In some embodiments of the present invention, the above control method is implemented by manually controlling the output control device 5 and the reflux control device 6. In other embodiments of the present invention, in order to achieve automatic control, the alkaline water electrolysis hydrogen production system also includes an operation control device, which is electrically connected to the electrolyzer 1, the output control device 5 and the reflux control device 6 respectively. The operation control device determines the load condition and dynamic condition of the electrolyzer 1 by obtaining the load parameters of the electrolyzer 1, and then controls the working state of the output control device 5 and the reflux control device 6 according to the load condition and dynamic condition of the electrolyzer 1.

[0055] like Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the output control device 5 includes a gas-liquid two-phase pump 51. The reflux control device 6 includes an electrolyte circulation pump 61 and / or a current limiting structure.

[0056] In order to prevent the gas-liquid mixture in the gas-liquid separator 2 from flowing back when the pressure of the electrolytic cell 1 decreases and becomes lower than the pressure of the gas-liquid separator 2, in an embodiment of the present invention, the output control device 5 also includes at least one one-way valve, and the output end of the electrolytic cell 1 is unidirectionally connected to the input end of the gas-liquid separator 2 through the one-way valve.

[0057] like Figure 2 and Figure 3 As shown, in some embodiments of the present invention, the output pipeline 3 includes a first output branch 31 and a second output branch 32 arranged in parallel, the input end of the first output branch 31 and the input end of the second output branch 32 are both connected to the output end of the electrolyzer 1, and the output end of the first output branch 31 and the output end of the second output branch 32 are both connected to the input end of the gas-liquid separator 2; the number of the one-way valves is two, the two one-way valves are respectively a first one-way valve 52 and a second one-way valve 53, the first one-way valve 52 is installed on the first output branch 31, and the gas-liquid two-phase pump 51 and the second one-way valve 53 are installed on the second output branch 32 along the output direction. Under low load conditions and dynamic load reduction conditions, the gas-liquid two-phase pump 51 is started to pump all the electrolyte from the second output branch 32 to the gas-liquid separator 2, or a portion of the electrolyte is pumped from the second output branch 32 to the gas-liquid separator 2, and another portion of the electrolyte is transported from the first output branch 31 to the gas-liquid separator 2 under the transport power provided by the electrolyte circulation pump 61, thereby increasing the output flow of the electrolyte. Under high load conditions and dynamic loading conditions, the gas-liquid two-phase pump 51 is turned off, so that the electrolyte is output to the gas-liquid separator 2 through the first output branch 31 only under the transport power provided by the electrolyte circulation pump 61.

[0058] Specifically, the input end of the first output branch 31 and the input end of the second output branch 32 are connected to the output end of the electrolytic cell 1 through the first three-way valve 33, and the output end of the first output branch 31 and the output end of the second output branch 32 are connected to the input end of the gas-liquid separator 2 through the second three-way valve 34. By setting the first three-way valve 33 and the second three-way valve 34, the on-off of the first output branch 31 and the second output branch 32 are controlled respectively.

[0059] In other embodiments of the present invention, the output pipeline 3 may be provided with only the second output branch 32, and the gas-liquid two-phase pump 51 and the second one-way valve 53 are installed on the second output branch 32 along the output direction. Under high load conditions and dynamic loading conditions, the gas-liquid two-phase pump 51 is also in the start-up state, and the working flow rate of the gas-liquid two-phase pump 51 is controlled to be equal to the working flow rate of the electrolyte circulation pump 61.

[0060] like Figure 3As shown, in the embodiment of the present invention, the output pipeline 3 is connected to the input end of the gas-liquid separator 2 through the jet device 7, and the jet device 7 can spray the electrolyte into the gas-liquid separator 2 to break the bubbles in the electrolyte, thereby heating the separation of hydrogen in the gas-liquid separator 2. The specific structure of the jet device 7 is the same as that of the prior art and will not be repeated here.

[0061] like Figure 2 and Figure 3 As shown, in the embodiment of the present invention, the hydrogen side output end of the electrolyzer 1 is provided with a first pressure sensor 8 to measure the pressure of the electrolyzer 1, so as to control the output control device 5 and the reflux control device 6 according to the pressure of the electrolyzer 1. Specifically, the first pressure sensor 8 is electrically connected to the operation control device. In addition, the gas phase output end of the gas-liquid separator 2 is provided with a second pressure sensor 9 and an exhaust control valve 11 along its output direction, and the pressure of the gas-liquid separator 2 is measured by the second pressure sensor 9, and then the exhaust control valve 11 is controlled according to the pressure of the gas-liquid separator 2 to discharge the gas separated in the gas-liquid separator 2.

[0062] In an embodiment of the present invention, a heat exchanger 10 for cooling the reflux electrolyte is also provided on the reflux pipeline 4. The heat exchanger 10 is located upstream of the reflux control device 6, so that the electrolyte flows into the reflux control device 6 after being cooled, which is beneficial to improving the service life of the reflux control device 6.

[0063] The above are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A control method for an alkaline water electrolysis hydrogen production system, characterized in that: The alkaline water electrolysis hydrogen production system comprises an electrolytic cell and a gas-liquid separator, wherein the electrolyte of the electrolytic cell can be output from the hydrogen side output end of the electrolytic cell to the gas-liquid separator for gas-liquid separation, and the electrolyte after gas-liquid separation can flow back into the electrolytic cell; The control method comprises the following steps: Load condition judgment: judging the load condition of the electrolytic cell according to the load parameter of the electrolytic cell; wherein, if the load parameter of the electrolytic cell is within a preset low load range, judging the load condition of the electrolytic cell as a low load condition; Flow control: Under the low load condition, the output flow of the electrolyte is controlled to be greater than the reflux flow of the electrolyte.

2. The control method of the alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The control method comprises the following steps: under the low load condition, measuring the pressure of the electrolytic cell, and controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte according to the pressure of the electrolytic cell, so that the pressure of the electrolytic cell meets a preset pressure range.

3. The control method of the alkaline water electrolysis hydrogen production system according to claim 2, characterized in that: The preset pressure range is 5%P0≤P≤10%P0, wherein P is the pressure of the electrolytic cell and P0 is the preset rated pressure.

4. The control method of the alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The load parameter includes current density; the preset low load range is less than or equal to 40% of the rated load of the electrolytic cell.

5. The control method of the alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: In the load condition determination step, if the load parameter of the electrolytic cell is within a preset high load range, the operating condition of the electrolytic cell is determined to be a high load condition; In the flow control step, under the high load condition, the reflux flow of the electrolyte and the output flow of the electrolyte are controlled to be the preset rated circulation flow.

6. The control method of the alkaline water electrolysis hydrogen production system according to claim 5, characterized in that: The control method further comprises the following steps: Dynamic operating condition judgment: judging the dynamic operating condition of the electrolytic cell according to the change of the load parameter of the electrolytic cell; wherein, if the load parameter of the electrolytic cell increases, the dynamic operating condition of the electrolytic cell is judged to be a dynamic loading condition; if the load parameter of the electrolytic cell decreases, the operating condition of the electrolytic cell is judged to be a dynamic load reduction condition; Under the dynamic loading condition, controlling the reflux flow rate of the electrolyte and the output flow rate of the electrolyte to be greater than the preset rated circulation flow rate; Under the dynamic load reduction condition, controlling the output flow rate of the electrolyte to be greater than the reflux flow rate of the electrolyte; The load condition determination step and the flow control step are repeated in sequence until the load parameter of the electrolytic cell stops increasing and decreasing.

7. The control method of the alkaline water electrolysis hydrogen production system according to claim 6, characterized in that: Under the low load condition and the dynamic load reduction condition, the output flow rate L1 of the electrolyte is equal to the preset rated circulation flow rate L0; the reflux flow rate L2 of the electrolyte and the preset rated circulation flow rate L0 have the relationship of 40% L0≤L2≤60% L0; Under the dynamic loading condition, the output flow rate L1 of the electrolyte and the preset rated circulation flow rate L0 have the relationship: 105% L0≤L1≤115% L0; the reflux flow rate L2 of the electrolyte and the preset rated circulation flow rate L0 have the relationship: 105% L0≤L2≤115% L0.

8. The control method of the alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The control method further includes: in a shutdown condition, controlling the output flow rate of the electrolyte and the reflux flow rate of the electrolyte to be greater than or equal to a preset rated circulation flow rate.

9. An alkaline water electrolysis hydrogen production system, characterized in that: It comprises an electrolytic cell and a gas-liquid separator, wherein the electrolyte in the electrolytic cell can be output from the hydrogen side output end of the electrolytic cell through an output pipeline to the gas-liquid separator for gas-liquid separation, and the electrolyte after gas-liquid separation can flow back into the electrolytic cell from the liquid output end of the gas-liquid separator through a reflux pipeline; Wherein, an output control device is provided on the output pipeline, and the output control device is used to control the output flow rate of the electrolyte; The reflux pipeline is provided with a reflux control device, and the reflux control device is used to control the reflux flow rate of the electrolyte.

10. The alkaline water electrolysis hydrogen production system according to claim 9, characterized in that: The output control device includes a gas-liquid two-phase pump; the reflux control device includes an electrolyte circulation pump and / or a current limiting structure.

11. The alkaline water electrolysis hydrogen production system according to claim 10, characterized in that: The output control device further comprises at least one one-way valve, through which the output end of the electrolytic cell is unidirectionally connected to the input end of the gas-liquid separator.

12. The alkaline water electrolysis hydrogen production system according to claim 11, characterized in that: The output pipeline includes a first output branch and a second output branch arranged in parallel, the input end of the first output branch and the input end of the second output branch are both connected to the output end of the electrolyzer, and the output end of the first output branch and the output end of the second output branch are both connected to the input end of the gas-liquid separator; There are two one-way valves, which are respectively a first one-way valve and a second one-way valve. The first one-way valve is installed on the first output branch, and the gas-liquid two-phase pump and the second one-way valve are installed on the second output branch along the output direction.

13. The alkaline water electrolysis hydrogen production system according to claim 10, characterized in that: A first pressure sensor is provided at the hydrogen-side output end of the electrolyzer.

14. The alkaline water electrolysis hydrogen production system according to claim 9, characterized in that: The output pipeline is connected to the input end of the gas-liquid separator through a jet device, and the jet device can spray the electrolyte into the gas-liquid separator to break the bubbles in the electrolyte.

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