Electrolysis hydrogen production system and electrolysis hydrogen production method

Abstract

The present invention discloses an electrolytic hydrogen production system and an electrolytic hydrogen production method. The electrolytic hydrogen production system includes: an electrolyzer, a first gas-liquid separator, and a second gas-liquid separator; the cathode side of the electrolyzer is connected to the first gas-liquid separator; the anode side of the electrolyzer is connected to the second gas-liquid separator; the electrolytic hydrogen production system also includes a first alkali liquid input pipeline, which is respectively connected to the first gas-liquid separator, the second gas-liquid separator, and the electrolyzer; and further includes: a third gas-liquid separator and a fourth gas-liquid separator; the cathode side of the electrolyzer is connected to the third gas-liquid separator; the anode side of the electrolyzer is connected to the fourth gas-liquid separator; the electrolytic hydrogen production system also includes a second alkali liquid input pipeline, which is respectively connected to the third gas-liquid separator, the fourth gas-liquid separator, and the first alkali liquid input pipeline; the ratio of the capacity of the first gas-liquid separator to the capacity of the third gas-liquid separator is greater than 3:1; and the ratio of the capacity of the second gas-liquid separator to the capacity of the fourth gas-liquid separator is greater than 3:1.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen preparation, and in particular to an electrolytic hydrogen production system and an electrolytic hydrogen production method. Background Art

[0002] Hydrogen is an energy carrier with both physical and energetic properties. It plays a vital role in industrial production, as an electrical energy carrier, as an electrosynthetic fuel, in heating, and in transportation. It spans all energy sectors and holds high potential market value in global decarbonization. Renewable energy sources, such as wind power, are intermittent, cyclical, and regional, posing challenges for large-scale, cross-seasonal energy storage. Using renewable energy to produce hydrogen through water electrolysis is an ideal large-scale, long-term energy storage method. Hydrogen is also a crucial fuel and chemical feedstock in transportation, industry, electricity, construction, and other sectors.

[0003] Among the mature water electrolysis hydrogen production technologies, alkaline water electrolysis hydrogen production technology is relatively mature, with a relatively simple process and relatively low cost, but the bottleneck is the relatively low working current density (less than 0.5A / cm 2 ), the efficiency of the electrolyzer (60-75%) needs to be improved. Starting from the low power start-up, the load operation range of the electrolyzer is only 15%-100%. The operating load is very low at low power. The coordinated control strategy of multiple devices in large-scale state is complex and large in size. The time required from room temperature to the temperature corresponding to the rated power is long. Taking the temperature corresponding to the electrolyzer outlet at rated power as 95℃ as an example, the hydrogen production capacity is 500Nm 3 A caustic soda system producing 1000 liters of liquid per hour takes nearly 3-4 hours to start up from room temperature to 95°C. During this time, hydrogen production cannot reach its rated power, and electricity consumption remains the same as when operating at rated power. This results in a significant waste of electricity, and the time required to reach the required hydrogen output increases, further increasing electricity consumption. Furthermore, when the temperature does not reach the rated power level, the hydrogen needs to be vented, and this vented hydrogen also results in waste.

[0004] Therefore, a solution is needed to shorten the low power period during cold start to reduce the power consumption during the low power period and reduce the waste of hydrogen. Summary of the Invention

[0005] In response to the above problems, the present invention provides an electrolytic hydrogen production system and an electrolytic hydrogen production method to solve the problem of electric energy waste during the low power period during cold start of electrolytic hydrogen production.

[0006] The present invention provides an electrolytic hydrogen production system, comprising: an electrolyzer, a first gas-liquid separator and a second gas-liquid separator; the cathode side of the electrolyzer and the first gas-liquid separator are connected via a first gas-liquid output pipeline; the anode side of the electrolyzer and the second gas-liquid separator are connected via a second gas-liquid output pipeline; the electrolytic hydrogen production system further comprises a first alkali liquid input pipeline, the first alkali liquid input pipeline being connected to the first gas-liquid separator, the second gas-liquid separator and the electrolyzer respectively; the electrolytic hydrogen production system further comprises: a third gas-liquid separator and a fourth gas-liquid separator; the electrolyzer The cathode side of the electrolytic cell is connected to the third gas-liquid separator through a third gas-liquid output pipeline; the anode side of the electrolytic cell is connected to the fourth gas-liquid separator through a fourth gas-liquid output pipeline; the electrolytic hydrogen production system also includes a second alkali liquid input pipeline, which is respectively connected to the third gas-liquid separator, the fourth gas-liquid separator and the first alkali liquid input pipeline; the ratio of the capacity of the first gas-liquid separator to the capacity of the third gas-liquid separator is greater than 3:1; the ratio of the capacity of the second gas-liquid separator to the capacity of the fourth gas-liquid separator is greater than 3:1.

[0007] Optionally, the electrolytic cell has a cathode side outlet, which is close to the cathode of the electrolytic cell, and is suitable for the alkaline solution and the gas generated on the cathode side to flow out of the electrolytic cell; the cathode side outlet of the electrolytic cell is connected to the mixed inlet of the first gas-liquid separator through a first gas-liquid output pipeline; the electrolytic cell has an anode side outlet, which is close to the anode of the electrolytic cell, and is suitable for the alkaline solution and the gas generated on the anode side to flow out of the electrolytic cell; the anode side outlet of the electrolytic cell is connected to the mixed inlet of the second gas-liquid separator through the second gas-liquid output pipeline; the electrolytic cell also includes an alkaline solution inlet, and the first alkaline solution input pipeline connects the alkaline solution inlet and the alkaline solution outlet of the first gas-liquid separator, and at the same time connects the alkaline solution inlet and the alkaline solution outlet of the second gas-liquid separator.

[0008] Optionally, the mixed inlet of the third gas-liquid separator is connected to the first gas-liquid output pipeline through the third gas-liquid output pipeline; the mixed inlet of the fourth gas-liquid separator is connected to the second gas-liquid output pipeline through the fourth gas-liquid output pipeline; the first alkali liquid input pipeline is provided with a second alkali liquid input pipeline inlet, and the second alkali liquid input pipeline is connected to the alkali liquid outlet of the third gas-liquid separator and the inlet of the second alkali liquid input pipeline, and at the same time is connected to the alkali liquid outlet of the fourth gas-liquid separator and the inlet of the second alkali liquid input pipeline.

[0009] Optionally, the electrolysis hydrogen production system also includes: a first scrubber and a second scrubber; the gas inlet of the first scrubber is connected to the gas outlet of the first gas-liquid separator through a first scrubber pipeline; the alkali liquid outlet of the first scrubber is connected to the alkali liquid inlet of the first gas-liquid separator through a first return liquid pipeline; the gas inlet of the second scrubber is connected to the gas outlet of the second gas-liquid separator through a second scrubber pipeline; the alkali liquid outlet of the second scrubber is connected to the alkali liquid inlet of the second gas-liquid separator through a second return liquid pipeline.

[0010] Optionally, the gas inlet of the first scrubbing device is connected to the gas outlet of the third gas-liquid separator through a third scrubbing pipeline; the alkali liquid outlet of the first scrubbing device is connected to the alkali liquid inlet of the third gas-liquid separator through a third return liquid pipeline; the gas inlet of the second scrubbing device is connected to the gas outlet of the fourth gas-liquid separator through a fourth scrubbing pipeline; the alkali liquid outlet of the second scrubbing device is connected to the alkali liquid inlet of the fourth gas-liquid separator through a fourth return liquid pipeline.

[0011] Optionally, a first regulating valve is provided on the first gas-liquid output pipeline near the first gas-liquid separator; a second regulating valve is provided on the second gas-liquid output pipeline near the second gas-liquid separator; a third regulating valve is provided on the third gas-liquid output pipeline; a fourth regulating valve is provided on the fourth gas-liquid output pipeline; a fifth regulating valve is provided on the third return liquid pipeline; a sixth regulating valve is provided on the fourth return liquid pipeline; and a seventh regulating valve is provided on the second alkali liquid input pipeline near the inlet of the second alkali liquid input pipeline.

[0012] Optionally, a variable frequency alkali solution pump is provided on the alkali solution inlet side of the first alkali solution input pipeline close to the alkali solution inlet of the electrolytic cell.

[0013] Optionally, a lye cooler is provided between the variable frequency lye pump and the lye inlet.

[0014] Optionally, the electrolysis hydrogen production system further includes: a first gas cooler and a second gas cooler; the first gas cooler is connected to the gas outlet of the first scrubber; and the second gas cooler is connected to the gas outlet of the second scrubber.

[0015] Optionally, the electrolysis hydrogen production system further includes: a water tank; the water tank is connected to the first scrubber to replenish water for the first scrubber; a water replenishment pump is provided on the pipeline connecting the water tank to the first scrubber.

[0016] The present invention also provides an electrolytic hydrogen production method, which uses the electrolytic hydrogen production system provided by the present invention; the electrolytic hydrogen production system has two working modes. In the first working mode, the method includes the following steps: opening the first alkali liquid input pipeline; controlling the alkali liquid to circulate between the electrolyzer and the first gas-liquid separator, and controlling the alkali liquid to circulate between the electrolyzer and the second gas-liquid separator; separating hydrogen from the alkali liquid from the first gas-liquid separator; and separating oxygen from the alkali liquid from the second gas-liquid separator; in the second working mode, the method includes the following steps: opening the first alkali liquid input pipeline and opening the second alkali liquid input pipeline so that the second alkali liquid input pipeline is connected to the first alkali liquid input pipeline; controlling the alkali liquid to circulate between the electrolyzer and the third gas-liquid separator, and controlling the alkali liquid to circulate between the electrolyzer and the fourth gas-liquid separator; separating hydrogen from the alkali liquid from the third gas-liquid separator; and separating oxygen from the alkali liquid from the fourth gas-liquid separator.

[0017] Optionally, the electrolysis hydrogen production system uses a first operating mode when the alkali solution input flow rate of the electrolyzer is greater than 1 / 3 of the rated alkali solution input flow rate of the electrolyzer; the electrolysis hydrogen production system uses a second operating mode when the alkali solution input flow rate of the electrolyzer is less than 1 / 3 of the rated alkali solution input flow rate of the electrolyzer.

[0018] The beneficial effects of the present invention are:

[0019] The electrolytic hydrogen production system of the present invention, by providing a third gas-liquid separator and a fourth gas-liquid separator, wherein the ratio of the capacity of the first gas-liquid separator to the capacity of the third gas-liquid separator is greater than 3:1, and the ratio of the capacity of the second gas-liquid separator to the capacity of the fourth gas-liquid separator is greater than 3:1, can realize two sets of gas-liquid separation cycles, namely, a large-capacity (high-flow) cycle of the electrolyzer-first gas-liquid separator and the second gas-liquid separator, and a small-capacity (low-flow) cycle of the electrolyzer-third gas-liquid separator and the fourth gas-liquid separator. Thus, during the cold start process, i.e., during the period of low power and low temperature of the electrolyzer, a small-capacity (low-flow) cycle can be adopted. The alkali solution flow rate corresponds to the low power period. Since the flow rate is low at this time, the heat exchange with the external environment is less, and the heat dissipation is low. At the same time, the power supply to the electrolyzer is to meet the rated power state. The heat generation of the electrolyzer is mainly affected by the heat generated by the electrode power supply. Therefore, the heat generation of the electrolyzer is not reduced, thereby increasing the speed of the electrolyzer temperature rise, shortening the low power period during cold start, and reducing the energy waste during the low power period. From low power to rated power, the variable frequency pump can be adjusted based on the electrolytic cell temperature, adjusting the alkali flow rate and thus achieving a linear regulation between the alkali flow rate and the electrolytic cell temperature. When the electrolytic cell temperature meets the temperature requirement corresponding to the rated power, a high-capacity (high-flow) circulation system is used, with the alkali flow rate corresponding to the rated power, achieving a linear regulation between the flow rate and the temperature. This allows for timely adjustment to the rated power state to meet production needs.

[0020] The electrolytic hydrogen production method of the present invention, using the electrolytic hydrogen production system provided herein, can achieve different high-capacity and low-capacity cycles by controlling pipeline flow to accommodate different power periods. This allows the low-capacity cycle to shorten the low-power period during cold start, reducing energy waste during low-power periods. Furthermore, the system can be adjusted to the rated power state of the high-capacity cycle in a timely manner to meet production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of a hydrogen production system by electrolysis according to a comparative example;

[0023] Figure 2 FIG. 1 is a schematic diagram of a hydrogen production system by electrolysis according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0026] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Comparative Example

[0028] refer to Figure 1 , Figure 1 Schematic diagram of a comparative example electrolytic hydrogen production system, wherein hollow arrows indicate gas flow and solid arrows indicate alkali solution flow. A hydrogen production system 100 includes an electrolytic cell 110, a first gas-liquid separator 121, and a second gas-liquid separator 122.

[0029] The electrolyzer 110 has a cathode side outlet. The cathode side outlet is close to the cathode of the electrolyzer 110 (the cathode position is not shown in the figure), and the cathode side outlet is suitable for the alkali solution and the gas (hydrogen) generated on the cathode side to flow out of the electrolyzer. The cathode side outlet of the electrolyzer is connected to the inlet of the first gas-liquid separator 121. Hydrogen is generated at the cathode of the electrolyzer 110, flows out of the electrolyzer with the alkali solution and enters the first gas-liquid separator 121, and is separated from the first gas-liquid separator 121 to the first scrubber 131. The first scrubber 131 discharges the scrubbed gas backward, and the remaining alkali solution flows back to the first gas-liquid separator 121. The first gas-liquid separator 121 feeds the alkali solution back to the electrolyzer 110 through the alkali solution input pipeline for continued circulation.

[0030] The electrolytic cell 110 has an anode-side outlet. The anode-side outlet is located near the anode of the electrolytic cell 110 (the anode position is not shown in the figure). The anode-side outlet is suitable for the alkali solution and the gas (oxygen) generated on the anode side to flow out of the electrolytic cell. The anode-side outlet of the electrolytic cell is connected to the inlet of the second gas-liquid separator 122 via a second gas-liquid output pipeline 142. Oxygen is generated at the anode of the electrolytic cell 110 and flows out of the electrolytic cell with the alkali solution into the second gas-liquid separator 122. From the second gas-liquid separator 122, it is separated and sent to the second scrubber 132. The second scrubber 132 discharges the scrubbed gas backward, and the remaining alkali solution flows back to the second gas-liquid separator 122. The second gas-liquid separator 122 feeds the alkali solution back to the electrolytic cell 110 via the alkali solution input pipeline.

[0031] The electrolytic cell 110 has an inlet for circulating alkali solution, located in the center of the cell. An alkali solution input pipeline connects to this inlet and to the liquid outlets of the first gas-liquid separator 121 and the second gas-liquid separator 122. Alkali solution flowing out of the first gas-liquid separator 121 and the second gas-liquid separator 122 flows into the alkali solution input pipeline and enters the electrolytic cell, forming a hybrid circulation system. A alkali solution pump 140 is installed on the side of the alkali solution input pipeline near the electrolytic cell to provide power for the alkali solution circulation. A alkali solution cooler 150 is installed between the alkali solution pump 140 and the electrolytic cell 110 to control the temperature of the alkali solution entering the electrolytic cell 110.

[0032] During a cold start, the electrolytic cell temperature and electrolysis rate of such a hydrogen production system are relatively low, while the power consumption is the same as when operating at rated power. This results in a large amount of power waste and increases the time required for hydrogen production to reach the required output, further increasing power consumption.

[0033] Example 1

[0034] refer to Figure 2 , Figure 2 FIG. 1 is a schematic diagram of an electrolytic hydrogen production system according to an embodiment of the present invention, wherein hollow arrows indicate gas flow direction and solid arrows indicate alkali solution flow direction. This embodiment provides an electrolytic hydrogen production system 200, comprising:

[0035] The electrolytic cell 210, a first gas-liquid separator 221, and a second gas-liquid separator 222 are provided. The cathode side of the electrolytic cell 210 is connected to the first gas-liquid separator 221 via a first gas-liquid output pipeline. The anode side of the electrolytic cell 210 is connected to the second gas-liquid separator 222 via a second gas-liquid output pipeline. The electrolytic hydrogen production system 200 also includes a first alkali liquid input pipeline, which connects the first gas-liquid separator 221, the second gas-liquid separator 222, and the electrolytic cell 210, respectively.

[0036] The electrolytic hydrogen production system also includes a third gas-liquid separator 223 and a fourth gas-liquid separator 224. The cathode side of the electrolytic cell 210 is connected to the third gas-liquid separator 223 via a third gas-liquid output pipeline. The anode side of the electrolytic cell 210 is connected to the fourth gas-liquid separator 224 via a fourth gas-liquid output pipeline. The electrolytic hydrogen production system 200 also includes a second alkali liquid input pipeline, which connects the third gas-liquid separator 223, the fourth gas-liquid separator 224, and the first alkali liquid input pipeline, respectively.

[0037] The ratio of the capacity of the first gas-liquid separator 221 to the capacity of the third gas-liquid separator 223 is greater than 3:1.

[0038] The ratio of the capacity of the second gas-liquid separator 222 to the capacity of the fourth gas-liquid separator 224 is greater than 3:1.

[0039] The electrolysis hydrogen production system 200 of this embodiment, by setting up a third gas-liquid separator 223 and a fourth gas-liquid separator 224, the ratio of the capacity of the first gas-liquid separator 221 to the capacity of the third gas-liquid separator 223 is greater than 3:1, and the ratio of the capacity of the second gas-liquid separator 222 to the capacity of the fourth gas-liquid separator 224 is greater than 3:1. This setting can realize two sets of gas-liquid separation cycles, namely, a large-capacity (high-flow) cycle of the electrolyzer 210-first gas-liquid separator 221, second gas-liquid separator 222 and a small-capacity (low-flow) cycle of the electrolyzer 210-third gas-liquid separator 223, fourth gas-liquid separator 224. Therefore, during the cold start process, that is, during the period of low power and low temperature of the electrolytic cell 210, a small capacity (low flow) cycle can be adopted, and the alkali solution flow rate corresponds to the low power. Since the flow rate is low at this time, there is less heat exchange with the external environment and the heat dissipation is low. At the same time, the power supply to the electrolytic cell 210 is to meet the rated power state. The heat generation of the electrolytic cell 210 is mainly affected by the heat generated by the electrode power supply. Therefore, the heat generation of the electrolytic cell is not reduced, thereby increasing the speed of heating of the electrolytic cell 210, shortening the time of the low power period during cold start, and reducing the waste of electricity during the low power period. When the temperature of the electrolytic cell 210 meets the temperature requirement corresponding to the rated power, a large capacity (high flow) cycle is adopted, and the alkali solution flow rate corresponds to the rated power. The flow rate and temperature are in a linear adjustment state. And timely adjust to the rated power state to meet production needs.

[0040] In this embodiment, the electrolytic cell 210 has a cathode outlet, which is located near the cathode of the electrolytic cell 210 and is suitable for allowing alkaline solution and gases generated on the cathode side to flow out of the electrolytic cell 210. The cathode outlet of the electrolytic cell 210 is connected to the mixing inlet of the first gas-liquid separator 221 via a first gas-liquid output pipeline. The electrolytic cell 210 has an anode outlet, which is located near the anode of the electrolytic cell 210 and is suitable for allowing alkaline solution and gases generated on the anode side to flow out of the electrolytic cell 210. The anode outlet of the electrolytic cell 210 is connected to the mixing inlet of the second gas-liquid separator 222 via a second gas-liquid output pipeline. The electrolytic cell 210 also includes an alkaline solution inlet. The first alkaline solution input pipeline connects the alkaline solution inlet to the alkaline solution outlet of the first gas-liquid separator 221 and also connects the alkaline solution inlet to the alkaline solution outlet of the second gas-liquid separator 222.

[0041] Furthermore, the mixing inlet of the third gas-liquid separator 223 is connected to the first gas-liquid output pipeline via a third gas-liquid output pipeline. The mixing inlet of the fourth gas-liquid separator 224 is connected to the second gas-liquid output pipeline via a fourth gas-liquid output pipeline. The first alkali liquid input pipeline is provided with a second alkali liquid input pipeline inlet, which is connected to the alkali liquid outlet of the third gas-liquid separator 223 and the second alkali liquid input pipeline inlet, and is also connected to the alkali liquid outlet and the second alkali liquid input pipeline inlet of the fourth gas-liquid separator 224.

[0042] In this embodiment, the electrolysis hydrogen production system 200 further includes: a first scrubber 231 and a second scrubber 232. The gas inlet of the first scrubber 231 is connected to the gas outlet of the first gas-liquid separator 221 via a first scrubber pipeline. The alkali liquid outlet of the first scrubber 231 is connected to the alkali liquid inlet of the first gas-liquid separator 221 via a first liquid return pipeline. The gas inlet of the second scrubber 232 is connected to the gas outlet of the second gas-liquid separator 222 via a second scrubber pipeline. The alkali liquid outlet of the second scrubber 232 is connected to the alkali liquid inlet of the second gas-liquid separator 222 via a second liquid return pipeline.

[0043] Furthermore, the gas inlet of the first gas scrubber 231 is connected to the gas outlet of the third gas-liquid separator 223 via a third gas scrubber pipeline. The alkali liquid outlet of the first gas scrubber 231 is connected to the alkali liquid inlet of the third gas-liquid separator 223 via a third liquid return pipeline. The gas inlet of the second gas scrubber 232 is connected to the gas outlet of the fourth gas-liquid separator 224 via a fourth gas scrubber pipeline. The alkali liquid outlet of the second gas scrubber 232 is connected to the alkali liquid inlet of the fourth gas-liquid separator 224 via a fourth liquid return pipeline.

[0044] In various embodiments, the first gas-liquid separator 221 and the third gas-liquid separator 223 are connected to the gas pipeline of the first scrubber 231 by pipelines, either through separate inlets or through pipelines that converge to the same inlet. Similarly, the second gas-liquid separator 222 and the fourth gas-liquid separator 224 are connected to the gas pipeline of the second scrubber 232 by pipelines, either through separate inlets or through pipelines that converge to the same inlet. The alkali liquid inlet and the mixing inlet of each gas-liquid separator are separate inlets.

[0045] In this embodiment, a first regulating valve a is provided on the side of the first gas-liquid output pipeline close to the first gas-liquid separator 221 .

[0046] The side close to the first gas-liquid separator 221 refers to the side close to the first gas-liquid separator 221 , with the connection point of the two pipelines being used as a calibration point, since the third gas-liquid output pipeline is connected to the first gas-liquid output pipeline.

[0047] A second regulating valve b is provided on the side of the second gas-liquid output pipeline close to the second gas-liquid separator 222 .

[0048] The side close to the second gas-liquid separator 222 refers to the side close to the second gas-liquid separator 222 , with the connection point of the two pipelines being used as a calibration point, since the fourth gas-liquid output pipeline is connected to the second gas-liquid output pipeline.

[0049] The third gas-liquid output pipeline is provided with a third regulating valve c.

[0050] The fourth gas-liquid output pipeline is provided with a fourth regulating valve d.

[0051] The third liquid return pipeline is provided with a fifth regulating valve e.

[0052] The fourth liquid return pipeline is provided with a sixth regulating valve f.

[0053] A seventh regulating valve g is provided near the inlet of the second alkali liquid input pipeline. Since the second alkali liquid input pipeline is connected to the third gas-liquid separator 223 and the fourth gas-liquid separator 224, respectively, and then connected to the first alkali liquid input pipeline after confluence, "near the inlet of the second alkali liquid input pipeline" refers to the side of the second alkali liquid input pipeline inlet (the first alkali liquid input pipeline) near the confluence, i.e., the pipeline section after confluence.

[0054] By setting the above-mentioned regulating valves, it is possible to control the working mode of the electrolysis hydrogen production system 200, that is, different working states, by coordinating the switching of the regulating valves. For example:

[0055] Close the third regulating valve c, the fourth regulating valve d, the fifth regulating valve e, the sixth regulating valve f, and the seventh regulating valve g, and open the first regulating valve a and the second regulating valve b. At this point, the alkaline solution circulates between the electrolytic cell 210 and the first gas-liquid separator 221, and simultaneously circulates between the electrolytic cell 210 and the second gas-liquid separator 222. The electrolytic hydrogen production system 200 is in a high-capacity circulation mode, i.e., the first operating mode.

[0056] Open the third regulating valve c, the fourth regulating valve d, the fifth regulating valve e, the sixth regulating valve f, and the seventh regulating valve g, and close the first regulating valve a and the second regulating valve b. At this point, the alkaline solution circulates between the electrolytic cell 210 and the third gas-liquid separator 223, and simultaneously circulates between the electrolytic cell 210 and the fourth gas-liquid separator 224. The electrolytic hydrogen production system 200 is in a low-capacity cycle, i.e., the second operating mode.

[0057] From the first working mode to the second working mode, those skilled in the art can adjust the variable frequency pump and the alkali solution flow rate according to the temperature of the electrolytic cell 210, so as to achieve a linear adjustment state between the alkali solution flow rate and the temperature of the electrolytic cell 210, and then determine which working mode the electrolytic cell 210 is in to cope with different working states of the electrolytic cell 210.

[0058] In this embodiment, a variable frequency alkali liquid pump 240 is provided on the first alkali liquid input pipeline near the alkali liquid inlet of the electrolyzer 210. The variable frequency alkali liquid pump 240 can control the alkali liquid circulation flow state within the electrolysis hydrogen production system 200 in different operating modes to cope with different operating conditions of the electrolyzer 210.

[0059] Furthermore, a lye cooler 250 is provided between the variable frequency lye pump 240 and the lye inlet. By providing the lye cooler 250, the temperature of the lye entering the electrolytic cell 210 can be further controlled, thereby coping with different working conditions of the electrolytic cell 210.

[0060] In some embodiments, electrolysis hydrogen production system 200 further includes a first gas cooler (not shown) and a second gas cooler (not shown). The first gas cooler is connected to the gas outlet of first scrubber 231. The second gas cooler is connected to the gas outlet of second scrubber 232. The coolers control the temperature of the gas output from electrolysis hydrogen production system 200 to meet production standards.

[0061] In some embodiments, the electrolysis hydrogen production system further includes a water tank connected to the first scrubber 231 to replenish water for the first scrubber 231. A water replenishment pump is provided on the pipeline connecting the water tank to the first scrubber 231. The water replenishment pump controls the flow rate of water replenished to the first scrubber 231.

[0062] Example 2

[0063] This embodiment provides a method for producing hydrogen by electrolysis, using the electrolysis hydrogen production system provided in the above embodiment 1. The electrolysis hydrogen production system has two operating modes. In the first operating mode, the following steps are included:

[0064] Open the first alkali solution input pipeline.

[0065] The alkali solution is controlled to circulate between the electrolytic cell and the first gas-liquid separator, and the alkali solution is controlled to circulate between the electrolytic cell and the second gas-liquid separator.

[0066] The hydrogen is separated from the alkaline liquid from the first gas-liquid separator.

[0067] Oxygen is separated from the alkali liquid from the second gas-liquid separator.

[0068] In the second working mode, the following steps are included:

[0069] The first alkali solution input pipeline is opened, and the second alkali solution input pipeline is opened, so that the second alkali solution input pipeline is connected to the first alkali solution input pipeline.

[0070] The alkali solution is controlled to circulate between the electrolytic cell and the third gas-liquid separator, and the alkali solution is controlled to circulate between the electrolytic cell and the fourth gas-liquid separator.

[0071] The hydrogen is separated from the alkaline liquid from the third gas-liquid separator.

[0072] The oxygen is separated from the alkali liquid from the fourth gas-liquid separator.

[0073] Specifically, for example, it can be:

[0074] Close the third, fourth, fifth, sixth, and seventh regulating valves, and open the first and second regulating valves. Alkaline solution now circulates between the electrolyzer and the first gas-liquid separator, and also between the electrolyzer and the second gas-liquid separator. The electrolytic hydrogen production system is in a high-capacity cycle, or first operating mode.

[0075] Open the third, fourth, fifth, sixth, and seventh regulating valves, and close the first and second regulating valves. Alkaline solution now circulates between the electrolyzer and the third gas-liquid separator, and also between the electrolyzer and the fourth gas-liquid separator. The electrolytic hydrogen production system is in a low-capacity cycle, or the second operating mode.

[0076] Those skilled in the art can determine which operating mode to use based on the temperature of the electrolyzer to cope with different operating conditions of the electrolyzer. For example, in this embodiment, the electrolysis hydrogen production system uses the first operating mode when the alkali solution input flow rate of the electrolyzer is greater than 1 / 3 of the rated alkali solution input flow rate of the electrolyzer. The electrolysis hydrogen production system uses the second operating mode when the alkali solution input flow rate of the electrolyzer is less than 1 / 3 of the rated alkali solution input flow rate of the electrolyzer.

[0077] The alkali flow rate in the electrolytic hydrogen production system can range from 20 L / h to 500 L / h, with a rated value of 500 L / h. When the flow rate is below 167 L / h, the second operating mode is used; when the flow rate is above 167 L / h, the first operating mode is used. The alkali flow rate can be controlled by the alkali pump or pump group in the system, or by adjusting the opening and closing degrees of different valve combinations in conjunction with the alkali pump or pump group.

[0078] The electrolytic hydrogen production method of this embodiment utilizes the electrolytic hydrogen production system provided in Example 1 above. By controlling the flow of pipes, different high-capacity and low-capacity cycles can be implemented to accommodate different power periods. This allows the low-capacity cycle to shorten the low-power period during cold start, reducing energy waste during low-power periods. Furthermore, the system can be adjusted to the rated power state of the high-capacity cycle in a timely manner to meet production needs.

[0079] To illustrate the beneficial effects of the present invention, a 10Nm 3 / h electrolysis hydrogen production system as an example, taking the electrolysis hydrogen production system of Example 1 and the electrolysis hydrogen production system of the comparative example as an example, the results are shown in Table 1:

[0080] Table 1 Comparison of heating time

[0081]

[0082] As can be seen from Table 1, compared with the comparative example, the heating time in Example 1 is reduced whether it is from 25°C to 60°C or from 25°C to 80°C, and the total energy consumption is reduced by 1kw.h. It can be proved that the electrolysis hydrogen production system provided by the present invention can shorten the low power period during cold start and reduce the energy waste during the low power period.

[0083] The technical solutions disclosed in the present invention have been described above through the use of embodiments. It is believed that those skilled in the art will be able to understand the present invention through the description of the above embodiments. Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A hydrogen production system by electrolysis, characterized in that: include: An electrolytic cell, a first gas-liquid separator, and a second gas-liquid separator; the cathode side of the electrolytic cell and the first gas-liquid separator are connected via a first gas-liquid output pipeline; the anode side of the electrolytic cell and the second gas-liquid separator are connected via a second gas-liquid output pipeline; the electrolytic hydrogen production system further includes a first alkali liquid input pipeline, which is respectively connected to the first gas-liquid separator, the second gas-liquid separator, and the electrolytic cell; The electrolysis hydrogen production system further includes: a third gas-liquid separator and a fourth gas-liquid separator; the cathode side of the electrolytic cell and the third gas-liquid separator are connected through a third gas-liquid output pipeline; The anode side of the electrolytic cell and the fourth gas-liquid separator are connected through a fourth gas-liquid output pipeline; the electrolytic hydrogen production system further includes a second alkali liquid input pipeline, which is respectively connected to the third gas-liquid separator, the fourth gas-liquid separator and the first alkali liquid input pipeline; The ratio of the capacity of the first gas-liquid separator to the capacity of the third gas-liquid separator is greater than 3:1; The ratio of the capacity of the second gas-liquid separator to the capacity of the fourth gas-liquid separator is greater than 3:

1.

2. The electrolysis hydrogen production system according to claim 1, characterized in that: The electrolytic cell has a cathode side outlet, the cathode side outlet is close to the cathode of the electrolytic cell, and the cathode side outlet is suitable for the alkali solution and the gas generated on the cathode side to flow out of the electrolytic cell; the cathode side outlet of the electrolytic cell is connected to the mixing inlet of the first gas-liquid separator through a first gas-liquid output pipeline; The electrolytic cell has an anode-side outlet, the anode-side outlet is close to the anode of the electrolytic cell, and the anode-side outlet is suitable for the alkaline solution and the gas generated on the anode side to flow out of the electrolytic cell; the anode-side outlet of the electrolytic cell is connected to the mixing inlet of the second gas-liquid separator through the second gas-liquid output pipeline; The electrolytic cell further includes an alkali solution inlet, the first alkali solution input pipeline is connected to the alkali solution inlet and the alkali solution outlet of the first gas-liquid separator, and is also connected to the alkali solution inlet and the alkali solution outlet of the second gas-liquid separator.

3. The electrolysis hydrogen production system according to claim 2, characterized in that: The mixing inlet of the third gas-liquid separator is connected to the first gas-liquid output pipeline through the third gas-liquid output pipeline; The mixing inlet of the fourth gas-liquid separator is connected to the second gas-liquid output pipeline through the fourth gas-liquid output pipeline; The first alkali liquid input pipeline is provided with a second alkali liquid input pipeline inlet, and the second alkali liquid input pipeline is connected to the alkali liquid outlet of the third gas-liquid separator and the second alkali liquid input pipeline inlet, and is also connected to the alkali liquid outlet of the fourth gas-liquid separator and the second alkali liquid input pipeline inlet.

4. The electrolysis hydrogen production system according to claim 3, characterized in that: Also includes: a first scrubber and a second scrubber; The gas inlet of the first gas scrubber is connected to the gas outlet of the first gas-liquid separator through a first gas scrubber pipeline; The alkali liquid outlet of the first scrubber is connected to the alkali liquid inlet of the first gas-liquid separator through a first liquid return pipeline; The gas inlet of the second scrubber is connected to the gas outlet of the second gas-liquid separator through a second scrubber pipeline; the alkali liquid outlet of the second scrubber is connected to the alkali liquid inlet of the second gas-liquid separator through a second liquid return pipeline.

5. The electrolysis hydrogen production system according to claim 4, characterized in that: The gas inlet of the first gas washing device is connected to the gas outlet of the third gas-liquid separator through the third gas washing pipeline; the alkali liquid outlet of the first gas washing device is connected to the alkali liquid inlet of the third gas-liquid separator through the third liquid return pipeline; The gas inlet of the second gas washing device is connected to the gas outlet of the fourth gas-liquid separator through the fourth gas washing pipeline; the alkali liquid outlet of the second gas washing device is connected to the alkali liquid inlet of the fourth gas-liquid separator through the fourth liquid return pipeline.

6. The electrolysis hydrogen production system according to claim 5, characterized in that: A first regulating valve is provided on the side of the first gas-liquid output pipeline close to the first gas-liquid separator; A second regulating valve is provided on the side of the second gas-liquid output pipeline close to the second gas-liquid separator; The third gas-liquid output pipeline is provided with a third regulating valve; The fourth gas-liquid output pipeline is provided with a fourth regulating valve; The third liquid return pipeline is provided with a fifth regulating valve; The fourth liquid return pipeline is provided with a sixth regulating valve; The second alkali solution input pipeline is provided with a seventh regulating valve near the inlet of the second alkali solution input pipeline.

7. The electrolysis hydrogen production system according to claim 6, characterized in that: A variable frequency alkali liquid pump is provided on the alkali liquid inlet side of the first alkali liquid input pipeline close to the electrolytic cell.

8. The electrolysis hydrogen production system according to claim 7, characterized in that: A lye cooler is provided between the variable frequency lye pump and the lye inlet.

9. A method for producing hydrogen by electrolysis, characterized in that: Using the electrolysis hydrogen production system according to any one of claims 1 to 8; The electrolysis hydrogen production system has two working modes: In the first working mode, the following steps are included: opening the first alkali solution input pipeline; controlling the alkaline solution to circulate between the electrolytic cell and the first gas-liquid separator, and simultaneously controlling the alkaline solution to circulate between the electrolytic cell and the second gas-liquid separator; Separating the hydrogen from the alkaline solution in the first gas-liquid separator; separating oxygen from the alkali solution from the second gas-liquid separator; In the second working mode, the following steps are included: Opening the first alkali solution input pipeline and opening the second alkali solution input pipeline so that the second alkali solution input pipeline is connected to the first alkali solution input pipeline; controlling the alkaline solution to circulate between the electrolytic cell and the third gas-liquid separator, and simultaneously controlling the alkaline solution to circulate between the electrolytic cell and the fourth gas-liquid separator; Separating the hydrogen from the alkali liquid in the third gas-liquid separator; The oxygen is separated from the alkaline solution from the fourth gas-liquid separator.

10. The method for producing hydrogen by electrolysis according to claim 9, characterized in that The electrolysis hydrogen production system uses the first working mode when the alkali solution input flow rate of the electrolytic cell is greater than 1 / 3 of the rated alkali solution input flow rate of the electrolytic cell; The electrolytic hydrogen production system uses the second working mode when the alkali solution input flow rate of the electrolytic cell is less than 1 / 3 of the rated alkali solution input flow rate of the electrolytic cell.

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