A hydrogen production system by alkaline electrolysis

Abstract

This invention belongs to the field of electrolytic hydrogen production and discloses an alkaline electrolytic hydrogen production system, including an alkaline solution circulation loop, a hydrogen-oxygen separation loop, a hydrogen deoxygenation and drying loop, and a cooling water circulation loop. The alkaline solution circulation loop includes an electrolyzer, a hydrogen precooler, an oxygen precooler, a hydrogen separator, an oxygen separator, and an alkaline solution cooler. The alkaline solution from the hydrogen and oxygen separators enters the alkaline solution cooler, where it undergoes secondary cooling by cooling water from the cooling water circulation loop. It then enters the electrolyzer for hydrogen electrolysis, and subsequently enters the hydrogen and oxygen precoolers, where it undergoes primary cooling by cooling water from the alkaline solution cooler. This two-stage cooling process achieves gradient cooling, maximizing heat recovery during the electrolytic hydrogen production process and improving the system's heat exchange efficiency. The recovered heat is used for hydrogen preheating, reducing the load on subsequent hydrogen-oxygen separation and hydrogen drying processes, further reducing system energy consumption.

Description

Technical Field

[0001] This invention relates to the field of hydrogen electrolysis technology, and in particular to an alkaline hydrogen electrolysis system. Background Technology

[0002] As the green hydrogen industry, as an important carrier of the clean energy system, enters a stage of rapid development, alkaline water electrolysis hydrogen production technology has become one of the mainstream routes for large-scale hydrogen production due to its mature process and controllable cost. However, in the process of industrialization towards large-scale and intensive development, traditional alkaline water electrolysis hydrogen production systems have exposed significant technical bottlenecks: existing devices mostly adopt decentralized small-scale designs, and the energy consumption per unit of hydrogen production in the electrolysis process is generally maintained at 4.3-4.8 kWh / Nm³. 3 The high price range is in line with industry expectations of 4.0 kWh / Nm³. 3 There is a significant gap between the following energy-saving targets and the target.

[0003] Electrolysis systems generate significant amounts of low-grade waste heat (30-80℃) during operation. Current cooling solutions typically employ direct heat exchange with cooling water at a single temperature, prepared using an air-cooled tower. This not only results in repeated water consumption across multiple stages, including the electrolyzer, separation unit, and alkali circulation system, but also leads to mixed losses of heat energy at different temperatures. An alkaline electrolysis hydrogen production system requires 30-40 tons of water to produce 1 ton of hydrogen, with approximately 50% of this water consumption stemming from evaporation losses during the air-cooled tower cooling process. This inefficient thermal management approach exacerbates water waste and reduces overall system energy efficiency, severely hindering the large-scale commercial application of alkaline electrolysis hydrogen production technology. Summary of the Invention

[0004] The purpose of this invention is to provide an alkaline electrolysis hydrogen production system to solve the problems existing in the above-mentioned related technologies, recover and utilize the heat in the hydrogen production system, and save system energy consumption.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides an alkaline electrolysis hydrogen production system, comprising:

[0007] An alkali solution circulation loop includes an electrolytic cell, a hydrogen precooler, an oxygen precooler, a hydrogen separator, an oxygen separator, and an alkali solution cooler. Water in the alkali solution undergoes a decomposition reaction within the electrolytic cell. The cathode outlet of the electrolytic cell is connected to the alkali solution inlet of the hydrogen precooler, and the alkali solution outlet of the hydrogen precooler is connected to the alkali solution inlet of the hydrogen separator. The anode outlet of the electrolytic cell is connected to the alkali solution inlet of the oxygen precooler, and the alkali solution outlet of the oxygen precooler is connected to the alkali solution inlet of the oxygen separator. The alkali solution outlets of both the hydrogen separator and the oxygen separator are connected to the alkali solution inlet of the alkali solution cooler, and the alkali solution outlet of the cooler is connected to the electrolytic cell. The hydrogen separator is also connected to the oxygen separator.

[0008] A hydrogen-oxygen separation circuit, wherein the hydrogen separator is connected to the hydrogen-oxygen separation circuit, and the hydrogen-oxygen separation circuit is capable of separating hydrogen and oxygen.

[0009] A hydrogen deoxygenation drying circuit is provided, wherein the hydrogen-oxygen separation circuit is connected to the hydrogen deoxygenation drying circuit, and the hydrogen deoxygenation drying circuit is capable of drying the separated hydrogen.

[0010] The alkali cooler is also connected to the cooling water circulation loop. The cooling water outlet of the alkali cooler is connected to the cooling water inlet of the hydrogen precooler and the cooling water inlet of the oxygen precooler, respectively. The cooling water outlet of the hydrogen precooler and the cooling water outlet of the oxygen precooler are both connected to the cooling water circulation loop.

[0011] Preferably, the alkaline outlet of the hydrogen separator and the alkaline outlet of the oxygen separator are both connected to the alkaline inlet of the alkaline cooler via an alkaline circulation pump.

[0012] Preferably, the hydrogen-oxygen separation circuit includes a hydrogen cooler, an oxygen cooler, a hydrogen scrubber, an oxygen scrubber, a first gas-liquid separator, and a second gas-liquid separator. The hydrogen cooler is located at the top of the hydrogen separator and the two are connected. The gas-liquid outlet of the hydrogen cooler is connected to the gas-liquid inlet of the hydrogen scrubber, and the gas-liquid outlet of the hydrogen scrubber is connected to the return liquid port of the hydrogen separator. The oxygen cooler is located at the top of the oxygen separator and the two are connected. The gas-liquid outlet of the oxygen cooler is connected to the gas-liquid inlet of the oxygen scrubber, and the gas-liquid outlet of the oxygen scrubber is connected to the return liquid port of the oxygen separator.

[0013] The hydrogen outlet of the hydrogen scrubber is connected to the first gas-liquid separator, and the liquid outlet of the first gas-liquid separator is connected to the return water port of the hydrogen separator.

[0014] The oxygen outlet of the oxygen scrubber is connected to the second gas-liquid separator, the oxygen outlet of the second gas-liquid separator is connected to an external collection pipeline, and the liquid outlet of the second gas-liquid separator is connected to the return water port of the oxygen separator.

[0015] Preferably, the hydrogen cooler is connected to the hydrogen separator via a flange, and the oxygen cooler is connected to the oxygen separator via a flange.

[0016] Both the hydrogen scrubber and the oxygen scrubber include a scrubber housing and a cooling coil disposed within the scrubber housing. The cooling coil is connected to an external pipeline via a flange on the side wall of the scrubber housing.

[0017] Preferably, the oxygen deoxygenation drying circuit includes a first preheater, a hydrogen regenerator, a deoxygenation heater, a deoxygenation tower, a first cooler, a second cooler, a third gas-liquid separator, a fourth gas-liquid separator, a three-tower drying system, a regeneration heater, a second preheater, and a hydrogen filter.

[0018] The hydrogen outlet of the first gas-liquid separator is connected to the hydrogen inlet of the first preheater. The hydrogen outlet of the first preheater is connected to the low-temperature inlet of the hydrogen regenerator. The low-temperature outlet of the hydrogen regenerator is connected to the inlet of the deoxygenation heater. The outlet of the deoxygenation heater is connected to the inlet of the deoxygenation tower. The outlet of the deoxygenation tower is connected to the high-temperature inlet of the hydrogen regenerator. The high-temperature outlet of the hydrogen regenerator is connected to the hydrogen inlet of the first cooler. The hydrogen outlet of the first cooler is connected to the inlet of the third gas-liquid separator. The hydrogen outlet of the third gas-liquid separator is connected to the inlet of the three-tower drying system. The three-tower drying system is capable of drying the separated hydrogen.

[0019] Preferably, the three-tower drying system includes a first drying tower, a second drying tower, and a third drying tower. The hydrogen outlet of the third gas-liquid separator is connected to the inlet of the first drying tower. The outlet of the first drying tower is connected to the inlet of the hydrogen filter and the hydrogen inlet of the second preheater. The hydrogen outlet of the second preheater is connected to the hydrogen inlet of the regeneration heater. The hydrogen outlet of the regeneration heater is connected to the inlet of the second drying tower. The outlet of the second drying tower is connected to the hydrogen inlet of the second cooler. The hydrogen outlet of the second cooler is connected to the inlet of the fourth gas-liquid separator. The hydrogen outlet of the fourth gas-liquid separator is connected to the inlet of the third drying tower. The outlet of the third drying tower is connected to the inlet of the hydrogen filter.

[0020] Preferably, the first preheater, the second preheater, the hydrogen precooler, and the oxygen precooler are all shell-and-tube heat exchangers.

[0021] The first cooler and the second cooler use chilled water at 7°C to 12°C for cooling on their low-temperature sides.

[0022] Preferably, the cooling water circulation loop includes a cooling water supply main pipe and a cooling water return main pipe;

[0023] The cooling water inlet of the alkali cooler is connected to the cooling water supply main pipe. The cooling water outlet of the alkali cooler is connected to the cooling water inlet of the hydrogen precooler, the cooling water inlet of the oxygen precooler, and the water-side inlet of the first preheater. The water-side outlet of the first preheater is connected to the water-side inlet of the second preheater. The water-side outlet of the second preheater is connected to the inlet of the cooling coil of the hydrogen scrubber and the oxygen scrubber. The water-side outlet of the second preheater is also connected to the cooling water return main pipe. The outlets of the cooling coils of the hydrogen scrubber and the oxygen scrubber are connected to the cooling water inlet of the hydrogen cooler and the cooling water inlet of the oxygen cooler, respectively. The cooling water outlets of the hydrogen cooler and the oxygen cooler are connected to the water-side inlet of the first preheater.

[0024] The cooling water outlets of the hydrogen precooler and the oxygen precooler are both connected to the cooling water return main.

[0025] Preferably, after the cooling water outlet of the hydrogen precooler is connected to the cooling water outlet of the oxygen precooler, it is connected to the cooling water return main pipe via a return water pipe, and a first flow valve is provided on the return water pipe.

[0026] The return water pipe is also connected to the water-side inlet of the second preheater via a return water branch pipe. The return water branch pipe is located on the outlet side of the first flow valve, and a second flow valve is installed on the return water branch pipe.

[0027] Preferably, a shut-off valve is provided between the water-side outlet of the second preheater and the inlet of the cooling coil of the hydrogen scrubber and the oxygen scrubber.

[0028] Preferably, the alkaline electrolysis hydrogen production system is characterized in that it further includes a controller, and the alkaline solution circulation loop, the hydrogen-oxygen separation loop, the hydrogen deoxygenation and drying loop, and the cooling water circulation loop are all communicatively connected to the controller.

[0029] This invention achieves the following technical advantages over related technologies: The alkaline electrolysis hydrogen production system of this invention includes an alkaline solution circulation loop, a hydrogen-oxygen separation loop, a hydrogen deoxygenation and drying loop, and a cooling water circulation loop; wherein, the alkaline solution circulation loop includes an electrolytic cell, a hydrogen precooler, an oxygen precooler, a hydrogen separator, an oxygen separator, and an alkaline solution cooler, where water in the alkaline solution undergoes a decomposition reaction within the electrolytic cell, the cathode outlet of the electrolytic cell is connected to the alkaline solution inlet of the hydrogen precooler, and the alkaline solution outlet of the hydrogen precooler is connected to the alkaline solution inlet of the hydrogen separator; the anode outlet of the electrolytic cell is connected to the alkaline solution inlet of the oxygen precooler, and the alkaline solution outlet of the oxygen precooler is connected to the alkaline solution inlet of the oxygen separator; the alkaline solution of the hydrogen separator... The alkali outlet of the oxygen separator and the alkali outlet of the alkali cooler are both connected to the alkali inlet of the alkali cooler, and the alkali outlet of the alkali cooler is connected to the electrolytic cell; the hydrogen separator is also connected to the oxygen separator; the hydrogen separator is connected to the hydrogen-oxygen separation circuit, which can separate hydrogen from oxygen; the hydrogen-oxygen separation circuit is connected to the hydrogen deoxygenation and drying circuit, which can dry the separated hydrogen; the alkali cooler is also connected to the cooling water circulation circuit, and the cooling water outlet of the alkali cooler is connected to the cooling water inlet of the hydrogen precooler and the cooling water inlet of the oxygen precooler, respectively. The cooling water outlets of the hydrogen precooler and the oxygen precooler are both connected to the cooling water circulation circuit.

[0030] In the alkaline electrolysis hydrogen production system of the present invention, the alkaline solution from the hydrogen separator and oxygen separator enters the alkaline solution cooler. The alkaline solution is subjected to secondary cooling by cooling water from the cooling water circulation loop, and then enters the electrolytic cell for electrolysis to produce hydrogen. The produced hydrogen (mixture) containing alkaline solution and oxygen (mixture) containing alkaline solution enter the hydrogen precooler and oxygen precooler respectively, and are subjected to primary cooling by cooling water from the alkaline solution cooler. The cooled gas-liquid mixture enters the hydrogen separator and oxygen separator respectively, completing the alkaline solution circulation. In the above process, the cooling water undergoes primary cooling in the alkali cooler, raising its temperature. Secondary cooling occurs in the hydrogen and oxygen separators, further raising the temperature. This two-stage heat exchange cooling method achieves gradient cooling, maximizing heat recovery during the electrolytic hydrogen production process and improving the system's heat exchange efficiency. Compared to existing technologies that rely solely on the alkali cooler for cooling, this method saves on cooling water consumption. Furthermore, the recovered heat is used for hydrogen preheating, reducing the load on subsequent hydrogen-oxygen separation and hydrogen drying processes, further lowering system energy consumption. The cooling water circulation loop uses cooling water as the working fluid for heat recovery and utilization within the electrolytic hydrogen production system, significantly reducing cooling water consumption and lowering both power and water consumption during cooling water production. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the alkaline electrolysis hydrogen production system disclosed in the embodiments of the present invention.

[0033] In the diagram: 101, Hydrogen precooler; 102, Oxygen precooler; 103, Alkali cooler; 104, First preheater; 105, First cooler; 106, Second cooler; 107, Second preheater; 108, Hydrogen regenerator; 201, Hydrogen separator; 202, Oxygen separator; 301, Hydrogen cooler; 302, Oxygen cooler; 401, Hydrogen scrubber; 402, Oxygen scrubber; 501, First gas-liquid separator; 502, Second gas-liquid separator. Separator; 503, Third gas-liquid separator; 504, Fourth gas-liquid separator; 601, Deoxygenation heater; 602, Regeneration heater; 7, Deoxygenation tower; 8, Three-tower drying system; 801, First drying tower; 802, Second drying tower; 803, Third drying tower; 9, Alkali circulation pump; 10, Hydrogen filter; 11, Electrolytic cell; 001, First flow valve; 002, Second flow valve; 003, Shut-off valve; 004, Return water pipe; 005, Return water branch pipe;

[0034] CWS, Cooling water supply main pipe; CWR, Cooling water return main pipe. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The purpose of this invention is to provide an alkaline electrolysis hydrogen production system to solve the problems existing in the above-mentioned related technologies, recover and utilize the heat in the hydrogen production system, and save system energy consumption.

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] This embodiment provides an alkaline electrolysis hydrogen production system. Please refer to [reference needed]. Figure 1 The system includes an alkali circulation loop, a hydrogen-oxygen separation loop, a hydrogen deoxygenation and drying loop, and a cooling water circulation loop. The alkali circulation loop includes an electrolytic cell 11, a hydrogen precooler 101, an oxygen precooler 102, a hydrogen separator 201, an oxygen separator 202, and an alkali cooler 103. Water in the alkali solution undergoes a decomposition reaction within the electrolytic cell 11. The cathode outlet of the electrolytic cell 11 is connected to the alkali inlet of the hydrogen precooler 101, and the alkali outlet of the hydrogen precooler 101 is connected to the alkali inlet of the hydrogen separator 201. The anode outlet of the electrolytic cell 11 is connected to the alkali inlet of the oxygen precooler 102, and the alkali outlet of the oxygen precooler 102 is connected to the alkali inlet of the oxygen separator 202. The alkali outlet of the hydrogen separator 201 and the cooling water circulation loop are also connected. The alkali outlets are all connected to the alkali inlet of the alkali cooler 103, and the alkali outlet of the alkali cooler 103 is connected to the electrolytic cell 11; the hydrogen separator 201 is also connected to the oxygen separator 202; the hydrogen separator 201 is connected to the hydrogen-oxygen separation circuit, which can separate hydrogen from oxygen; the hydrogen-oxygen separation circuit is connected to the hydrogen deoxygenation and drying circuit, which can dry the separated hydrogen; the alkali cooler 103 is also connected to the cooling water circulation circuit, and the cooling water outlet of the alkali cooler 103 is connected to the cooling water inlet of the hydrogen precooler 101 and the cooling water inlet of the oxygen precooler 102, respectively. The cooling water outlets of the hydrogen precooler 101 and the oxygen precooler 102 are both connected to the cooling water circulation circuit.

[0040] In the alkaline electrolysis hydrogen production system of the present invention, the alkaline solution from the hydrogen separator 201 and the oxygen separator 202 enters the alkaline solution cooler 103. The alkaline solution is subjected to secondary cooling by cooling water from the cooling water circulation loop, and then enters the electrolytic cell 11 for electrolysis to produce hydrogen. The produced alkaline-containing hydrogen (gas-liquid mixture) and alkaline-containing oxygen (gas-liquid mixture) enter the hydrogen precooler 101 and the oxygen precooler 102 respectively, and are subjected to primary cooling by cooling water from the alkaline solution cooler 103. The cooled gas-liquid mixture then enters the hydrogen separator 201 and the oxygen separator 202 respectively, completing the alkaline solution circulation. In the above process, the cooling water undergoes primary cooling in the alkali cooler 103, raising its temperature. Secondary cooling occurs in the hydrogen separator 201 and oxygen separator 202, further raising the cooling water temperature. This two-stage heat exchange cooling method achieves gradient cooling, maximizing heat recovery during the electrolytic hydrogen production process and improving the system's heat exchange efficiency. Compared to existing technologies that only use an alkali cooler for cooling, this method saves on cooling water consumption during the alkali cooling process. Furthermore, the recovered heat is used for hydrogen preheating, reducing the load on subsequent hydrogen-oxygen separation and hydrogen drying processes, further lowering system energy consumption. The cooling water circulation loop of this invention uses cooling water as the working fluid for heat recovery and utilization within the electrolytic hydrogen production system, significantly reducing the system's cooling water consumption and lowering the power and water consumption during cooling water production.

[0041] The alkaline outlets of the hydrogen separator 201 and the oxygen separator 202 are connected to the alkaline inlet of the alkaline cooler 103 via the alkaline circulation pump 9, ensuring smooth circulation of the alkaline solution, preventing backflow, and ensuring the reliability of the system.

[0042] Specifically, the hydrogen-oxygen separation circuit includes a hydrogen cooler 301, an oxygen cooler 302, a hydrogen scrubber 401, an oxygen scrubber 402, a first gas-liquid separator 501, and a second gas-liquid separator 502. The hydrogen cooler 301 is located on top of the hydrogen separator 201 and the two are connected. The gas-liquid outlet of the hydrogen cooler 301 is connected to the gas-liquid inlet of the hydrogen scrubber 401, and the gas-liquid outlet of the hydrogen scrubber 401 is connected to the return port of the hydrogen separator 201. The oxygen cooler 302 is located on top of the oxygen separator 202 and the two are connected. The gas-liquid outlet of the oxygen cooler 302 is connected to the gas-liquid inlet of the oxygen scrubber 402, and the gas-liquid outlet of the oxygen scrubber 402 is connected to the return port of the oxygen separator 202.

[0043] The hydrogen outlet of the hydrogen scrubber 401 is connected to the first gas-liquid separator 501, and the liquid outlet of the first gas-liquid separator 501 is connected to the return water port of the hydrogen separator 201.

[0044] The oxygen outlet of the oxygen scrubber 402 is connected to the second gas-liquid separator 502, the oxygen outlet of the second gas-liquid separator 502 is connected to the external collection pipeline, and the liquid outlet of the second gas-liquid separator 502 is connected to the return water port of the oxygen separator 202.

[0045] During system operation, the hydrogen in hydrogen cooler 301 and the oxygen in oxygen cooler 302 undergo primary cooling by cooling water from hydrogen scrubber 401 and oxygen scrubber 402. The cooled hydrogen and oxygen then enter hydrogen scrubber 401 and oxygen scrubber 402 respectively for secondary cooling. In this process, the cooling water undergoes primary cooling in hydrogen scrubber 401 and oxygen scrubber 402, raising its temperature, and then undergoes secondary cooling in hydrogen cooler 301 and oxygen cooler 302, further raising its temperature. This cascaded recovery of heat from the alkali solution improves system heat exchange efficiency and reduces cooling water consumption, thus saving system energy.

[0046] Hydrogen and oxygen, after undergoing two-stage cooling, enter the first gas-liquid separator 501 and the second gas-liquid separator 502 for gas-liquid separation, respectively. The separated hydrogen enters the subsequent hydrogen deoxygenation and drying circuit, while the separated oxygen can be input into an external collection pipeline for collection and backup, making rational use of resources and avoiding waste.

[0047] In this specific embodiment, the hydrogen cooler 301 is connected to the hydrogen separator 201 via a flange, and the oxygen cooler 302 is connected to the oxygen separator 202 via a flange. This improves the ease of disassembly and assembly of the hydrogen cooler 301 and the hydrogen separator 201, and the oxygen cooler 302 and the oxygen separator 202, and provides convenience for cleaning and maintenance of the system.

[0048] It should also be noted that both the hydrogen scrubber 401 and the oxygen scrubber 402 include a scrubber housing and a cooling coil installed inside the scrubber housing. The cooling coil is connected to the external pipeline via a flange on the side wall of the scrubber housing, which improves the ease of operation of connecting the cooling coil to the external pipeline while avoiding leakage of the scrubber housing.

[0049] More specifically, the oxygen deoxygenation drying circuit includes a first preheater 104, a hydrogen regenerator 108, a deoxygenation heater 601, a deoxygenation tower 7, a first cooler 105, a second cooler 106, a third gas-liquid separator 503, a fourth gas-liquid separator 504, a three-tower drying system 8, a regeneration heater 602, a second preheater 107, and a hydrogen filter 10.

[0050] The hydrogen outlet of the first gas-liquid separator 501 is connected to the hydrogen inlet of the first preheater 104. The hydrogen outlet of the first preheater 104 is connected to the low-temperature inlet of the hydrogen regenerator 108. The low-temperature outlet of the hydrogen regenerator 108 is connected to the inlet of the deoxygenator 601. The outlet of the deoxygenator 601 is connected to the inlet of the deoxygenator 7. The outlet of the deoxygenator 7 is connected to the high-temperature inlet of the hydrogen regenerator 108. The high-temperature outlet of the hydrogen regenerator 108 is connected to the hydrogen inlet of the first cooler 105. The hydrogen outlet of the first cooler 105 is connected to the inlet of the third gas-liquid separator 503. The hydrogen outlet of the third gas-liquid separator 503 is connected to the inlet of the three-tower drying system 8. The three-tower drying system 8 can dry the separated hydrogen.

[0051] In the oxygen deoxygenation drying circuit of the present invention, the hydrogen separated by the first gas-liquid separator 501 is input into the first preheater 104. The hydrogen is preheated by the heated cooling water in the first preheater 104. The preheated hydrogen enters the low-temperature side of the hydrogen regenerator 108 for reheating, and then enters the deoxygenation heater 601 for heating. The hydrogen preheating reduces the heating load of the subsequent deoxygenation heater 601, which helps to save system energy consumption. The high-temperature hydrogen heated by the deoxygenation heater 601 enters the high-temperature side of the hydrogen regenerator 108 and its temperature decreases. Then it enters the first cooler 105 for cooling. The hydrogen cooled by the first cooler 105 enters the third gas-liquid separator 503 for gas-liquid separation again. The hydrogen after gas-liquid separation enters the three-tower drying system 8 for drying treatment.

[0052] In this specific embodiment, the three-tower drying system 8 includes a first drying tower 801, a second drying tower 802, and a third drying tower 803. The hydrogen outlet of the third gas-liquid separator 503 is connected to the inlet of the first drying tower 801. The outlet of the first drying tower 801 is connected to the inlet of the hydrogen filter 10 and the hydrogen inlet of the second preheater 107. The hydrogen outlet of the second preheater 107 is connected to the hydrogen inlet of the regeneration heater 602. The hydrogen outlet of the regeneration heater 602 is connected to the inlet of the second drying tower 802. The outlet of the second drying tower 802 is connected to the hydrogen inlet of the second cooler 106. The hydrogen outlet of the second cooler 106 is connected to the inlet of the fourth gas-liquid separator 504. The hydrogen outlet of the fourth gas-liquid separator 504 is connected to the inlet of the third drying tower 803. The outlet of the third drying tower 803 is connected to the inlet of the hydrogen filter 10.

[0053] The hydrogen separated by the third gas-liquid separator 503 enters the first drying tower 801 for drying. Most of the hydrogen after preliminary drying is filtered by the hydrogen filter 10 before being fed into subsequent processes. The hydrogen filter 10 can effectively prevent adsorbent from being mixed in with the hydrogen. Part of the hydrogen enters the second preheater 107. The hydrogen preheated by the second preheater 107 enters the regeneration heater 602 for heating to form high-temperature regeneration gas. The high-temperature regeneration gas is passed into the second drying tower 802 to heat the saturated adsorbent, causing the moisture to desorb and be discharged with the gas, thus realizing the regeneration of the adsorbent. The hot and humid gas in the second drying tower 802 enters the second cooler 106 for cooling, and the water vapor condenses into liquid water. Then it enters the fourth gas-liquid separator 504 for gas-liquid separation again to obtain dry hydrogen. The dried hydrogen enters the third drying tower 803 for further drying, and then is filtered by the hydrogen filter 10 before being fed into subsequent processes. In this specific embodiment, the first drying tower 801, the second drying tower 802, and the third drying tower 803 of the three-tower drying system 8 operate in a cyclical manner according to the functions of "drying"-"regeneration"-"re-drying", achieving continuous gas supply and efficient dehydration of the system. The cyclical operation includes three stages. In each stage, one of the three drying towers in the three-tower drying system 8 performs the drying operation, one performs the adsorbent regeneration operation, and the other performs the re-drying operation, enabling the system to continuously output dry hydrogen gas. While continuously and efficiently dehydrating hydrogen gas, the system's energy consumption is optimized.

[0054] Among them, the first preheater 104, the second preheater 107, the hydrogen precooler 101 and the oxygen precooler 102 all adopt shell-and-tube heat exchangers. Shell-and-tube heat exchangers are resistant to high temperature and high pressure, have a large processing capacity and strong adaptability, and have low operating costs.

[0055] In this specific embodiment, the low-temperature sides of the first cooler 105 and the second cooler 106 are cooled by chilled water at a temperature of 7°C to 12°C. In practical applications, the temperature range of the cooling water can be adjusted according to actual production conditions to meet different specific cooling requirements.

[0056] Furthermore, the cooling water circulation loop includes a cooling water supply main pipe (CWS) and a cooling water return main pipe (CWR) to meet the system's cooling water circulation requirements.

[0057] The cooling water inlet of the alkali cooler 103 is connected to the cooling water supply main pipe CWS. The cooling water outlet of the alkali cooler 103 is connected to the cooling water inlet of the hydrogen precooler 101, the cooling water inlet of the oxygen precooler 102, and the water-side inlet of the first preheater 104. The water-side outlet of the first preheater 104 is connected to the water-side inlet of the second preheater 107. The water-side outlet of the second preheater 107 is connected to the inlet of the cooling coil of the hydrogen scrubber 401 and the oxygen scrubber 402. The water-side outlet of the second preheater 107 is also connected to the cooling water return main pipe CWR. After the outlets of the cooling coils of the hydrogen scrubber 401 and the oxygen scrubber 402 are connected, they are connected to the cooling water inlet of the hydrogen cooler 301 and the cooling water inlet of the oxygen cooler 302, respectively. After the cooling water outlets of the hydrogen cooler 301 and the oxygen cooler 302 are connected, they are connected to the water-side inlet of the first preheater 104.

[0058] The cooling water outlets of the hydrogen precooler 101 and the oxygen precooler 102 are both connected to the cooling water return main pipe CWR.

[0059] For ease of control, the cooling water outlet of the hydrogen precooler 101 is connected to the cooling water outlet of the oxygen precooler 102, and then connected to the cooling water return main CWR via the return water pipe 004. A first flow valve 001 is installed on the return water pipe 004. The return water pipe 004 is also connected to the water side inlet of the second preheater 107 via the return water branch pipe 005. The return water branch pipe 005 is located on the outlet side of the first flow valve 001, and a second flow valve 002 is installed on the return water branch pipe 005.

[0060] Accordingly, a shut-off valve 003 is provided between the water-side outlet of the second preheater 107 and the inlet of the cooling coil of the hydrogen scrubber 401 and the oxygen scrubber 402.

[0061] Meanwhile, the alkaline electrolysis hydrogen production system of the present invention also includes a controller. The alkaline solution circulation loop, hydrogen-oxygen separation loop, hydrogen deoxygenation and drying loop, and cooling water circulation loop are all communicatively connected to the controller to control the operating status of each loop and improve the system's automation level. Furthermore, monitoring elements are installed in the aforementioned alkaline solution circulation loop, hydrogen-oxygen separation loop, hydrogen deoxygenation and drying loop, and cooling water circulation loop to monitor the operating parameters of each loop, such as temperature and pressure. These monitoring elements are communicatively connected to the controller to adjust the system's operating status in real time based on the system parameters monitored by the monitoring elements, thereby improving the system's operational safety factor. It should be noted that the specific structure and working principle of the controller are conventional methods used by those skilled in the art and will not be elaborated upon here.

[0062] During system operation, the water-side outlet temperatures of the first preheater 104 and the second preheater 107 can be monitored. When the water-side outlet temperature of the first preheater 104 is lower than (higher than) the set value, the opening of the first flow valve 001 can be automatically reduced (increased) to increase (decrease) the cooling water flow rate entering the first preheater 104. When the outlet temperature of the second preheater 107 is lower than (higher than) the set value, the opening of the first flow valve 001 can be automatically increased (decreased) to increase (decrease) the cooling water flow rate entering the second preheater 107, thereby achieving precise temperature control.

[0063] In addition, when the cooling water supply is insufficient, the shut-off valve 003 can be opened to introduce the preheated cooling water in the second preheater 107 into the hydrogen scrubber 401 and the oxygen scrubber 402, thereby reducing the water supply load of the cooling water supply main pipe CWS.

[0064] The alkaline electrolysis hydrogen production system of the present invention, by setting up a hydrogen precooler 101 and an oxygen precooler 102, and by designing a stepped cooling system for the coolers, precoolers and scrubbers in the system according to the working fluid temperature, maximizes the heat recovery of the electrolysis hydrogen production process; by using the recovered heat for hydrogen preheating, the electrical load of the deoxygenation heater 601 and the regeneration heater 602 can be reduced, thus achieving energy saving of the system.

[0065] Example 2

[0066] This embodiment provides an alkaline electrolysis hydrogen production system. In this embodiment, the system's hydrogen production capacity is 1000 Nm³. 3 The system cooling water supply temperature is designed to be 32℃. In the alkali circulation loop, the alkali circulation pump 9 pumps the alkali from the outlets of the hydrogen separator 201 and the oxygen separator 202 into the alkali cooler 103. The alkali is subjected to secondary cooling by cooling water from the cooling water supply main pipe CWS, and then enters the electrolytic cell 11 for electrolysis to produce hydrogen. The produced hydrogen and alkali mixture and oxygen and alkali mixture enter the hydrogen precooler 101 and the oxygen precooler 102, respectively, and are subjected to primary cooling by cooling water from the alkali cooler 103. The cooled gas-liquid mixtures then enter the hydrogen separator 201 and the oxygen separator 202, respectively, completing the alkali circulation. In the above process, the cooling water undergoes primary cooling in the alkali cooler 103, raising the water temperature, and then undergoes secondary cooling in the hydrogen separator 201 and oxygen separator 202, raising the water temperature again. During the two heat exchange processes, the alkali temperature is cooled from 90°C to 80°C during the primary cooling process, while the cooling water temperature is raised from 51°C to 65°C. During the secondary cooling process, the alkali temperature continues to decrease from 80°C to 65°C, while the cooling water temperature is raised from 32°C to 51°C. After two stages of waste heat recovery, the cooling water temperature is raised from 32°C to 65°C.

[0067] The heat exchange efficiency after a two-stage cooling process is:

[0068]

[0069] In the traditional process, only the alkali cooler 103 is used for cooling, the cooling water outlet temperature is about 45℃, and the heat exchange efficiency is:

[0070]

[0071] Compared to the traditional alkaline cooling process, the heat exchange efficiency of the alkaline electrolysis hydrogen production system of the present invention is increased by about 2.5 times, which means that the amount of cooling water used in the alkaline cooling process is reduced by about 60%.

[0072] In the hydrogen-oxygen separation circuit, the hydrogen in hydrogen cooler 301 and the oxygen in oxygen cooler 302 are first-stage cooled by cooling water from hydrogen scrubber 401 and oxygen scrubber 402. The cooled hydrogen and oxygen then enter hydrogen scrubber 401 and oxygen scrubber 402 respectively, where they are second-stage cooled by cooling water from the cooling water supply main CWS and the second preheater 107 in the cooling coils. In this process, the cooling water undergoes first-stage cooling in hydrogen scrubber 401 and oxygen scrubber 402, raising its temperature, and then undergoes second-stage cooling in hydrogen cooler 301 and oxygen cooler 302, further raising its temperature, thus achieving a cascade recovery of heat from the alkali solution.

[0073] The amount of cooling water used in the hydrogen-oxygen separation circuit is about 3% of that used in the alkali circulation circuit. The heat exchange efficiency is basically the same as that in the alkali circulation circuit, at about 56.9%, which is 2.5 times higher.

[0074] Cooling water from the hydrogen precooler 101, oxygen precooler 102, hydrogen cooler 301, and oxygen cooler 302, after undergoing two stages of cooling, converges through pipelines and enters the water-side pipeline of the first preheater 104 to preheat the hydrogen. The water temperature decreases from 65℃ to 45℃, and the hydrogen temperature increases from 40℃ to 60℃. The preheated hydrogen is then reheated to 100℃ through the cold-side pipeline of the hydrogen regenerator 108, and further heated to 120℃ by the deoxygenation heater 601. The resulting high-temperature hydrogen enters the deoxygenation tower 7 for deoxygenation, and then cools down to 100℃ through the hot-side pipeline of the hydrogen regenerator 108. After this process, the inlet temperature of the deoxygenation heater 601 can be increased from 80℃ to 100℃, reducing the heat load by approximately 50%.

[0075] Water from the outlet of the water-side pipeline of the first preheater 104 continues to enter the water-side pipeline of the second preheater 107 to preheat the hydrogen. The water temperature decreases from 45°C to 32°C, and the hydrogen temperature increases from 26°C to 40°C. The preheated hydrogen enters the regeneration heater 602 and is heated to 300°C, reducing the heat load by about 5%.

[0076] In this specific embodiment, the PID control system monitors the outlet temperatures of the first preheater 104 and the second preheater 107. When the outlet temperature of the first preheater 104 is lower than (higher than) the set value, the opening of the first flow valve 001 can be automatically reduced (increased) to increase (decrease) the water flow rate entering the first preheater 104. When the outlet temperature of the second preheater 107 is lower than (higher than) the set value, the opening of the first flow valve 001 can be automatically increased (decreased) to increase (decrease) the water flow rate entering the second preheater 107, thereby achieving precise temperature control.

[0077] It should also be noted that when the cooling water supply is insufficient, opening the shut-off valve 003 can introduce the preheated cooling water in the second preheater 107 into the hydrogen scrubber 401 and the oxygen scrubber 402, thereby reducing the water supply load of the cooling water supply main pipe CWS.

[0078] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An alkaline electrolysis hydrogen production system, characterized in that, include: An alkali solution circulation loop includes an electrolytic cell, a hydrogen precooler, an oxygen precooler, a hydrogen separator, an oxygen separator, and an alkali solution cooler. Water in the alkali solution undergoes a decomposition reaction within the electrolytic cell. The cathode outlet of the electrolytic cell is connected to the alkali solution inlet of the hydrogen precooler, and the alkali solution outlet of the hydrogen precooler is connected to the alkali solution inlet of the hydrogen separator. The anode outlet of the electrolytic cell is connected to the alkali solution inlet of the oxygen precooler, and the alkali solution outlet of the oxygen precooler is connected to the alkali solution inlet of the oxygen separator. The alkali solution outlets of both the hydrogen separator and the oxygen separator are connected to the alkali solution inlet of the alkali solution cooler, and the alkali solution outlet of the cooler is connected to the electrolytic cell. The hydrogen separator is also connected to the oxygen separator. A hydrogen-oxygen separation circuit, wherein the hydrogen separator is connected to the hydrogen-oxygen separation circuit, and the hydrogen-oxygen separation circuit is capable of separating hydrogen and oxygen. A hydrogen deoxygenation drying circuit is provided, wherein the hydrogen-oxygen separation circuit is connected to the hydrogen deoxygenation drying circuit, and the hydrogen deoxygenation drying circuit is capable of drying the separated hydrogen. The alkali cooler is also connected to the cooling water circulation loop. The cooling water outlet of the alkali cooler is connected to the cooling water inlet of the hydrogen precooler and the cooling water inlet of the oxygen precooler. The cooling water outlet of the hydrogen precooler and the cooling water outlet of the oxygen precooler are both connected to the cooling water circulation loop. The hydrogen-oxygen separation circuit includes a hydrogen cooler, an oxygen cooler, a hydrogen scrubber, an oxygen scrubber, a first gas-liquid separator, and a second gas-liquid separator. The hydrogen cooler is located at the top of the hydrogen separator and the two are connected. The gas-liquid outlet of the hydrogen cooler is connected to the gas-liquid inlet of the hydrogen scrubber, and the gas-liquid outlet of the hydrogen scrubber is connected to the return liquid port of the hydrogen separator. The oxygen cooler is located at the top of the oxygen separator and the two are connected. The gas-liquid outlet of the oxygen cooler is connected to the gas-liquid inlet of the oxygen scrubber, and the gas-liquid outlet of the oxygen scrubber is connected to the return liquid port of the oxygen separator. The hydrogen outlet of the hydrogen scrubber is connected to the first gas-liquid separator, and the liquid outlet of the first gas-liquid separator is connected to the return water port of the hydrogen separator. The oxygen outlet of the oxygen scrubber is connected to the second gas-liquid separator, the oxygen outlet of the second gas-liquid separator is connected to an external collection pipeline, and the liquid outlet of the second gas-liquid separator is connected to the return water port of the oxygen separator. The hydrogen deoxygenation drying circuit includes a first preheater, a hydrogen regenerator, a deoxygenation heater, a deoxygenation tower, a first cooler, a second cooler, a third gas-liquid separator, a fourth gas-liquid separator, a three-tower drying system, a regeneration heater, a second preheater, and a hydrogen filter. The hydrogen outlet of the first gas-liquid separator is connected to the hydrogen inlet of the first preheater. The hydrogen outlet of the first preheater is connected to the low-temperature inlet of the hydrogen regenerator. The low-temperature outlet of the hydrogen regenerator is connected to the inlet of the deoxygenation heater. The outlet of the deoxygenation heater is connected to the inlet of the deoxygenation tower. The outlet of the deoxygenation tower is connected to the high-temperature inlet of the hydrogen regenerator. The high-temperature outlet of the hydrogen regenerator is connected to the hydrogen inlet of the first cooler. The hydrogen outlet of the first cooler is connected to the inlet of the third gas-liquid separator. The hydrogen outlet of the third gas-liquid separator is connected to the inlet of the three-tower drying system. The three-tower drying system is capable of drying the separated hydrogen.

2. The alkaline electrolysis hydrogen production system according to claim 1, characterized in that: The alkaline outlet of the hydrogen separator and the alkaline outlet of the oxygen separator are both connected to the alkaline inlet of the alkaline cooler via an alkaline circulation pump.

3. The alkaline electrolysis hydrogen production system according to claim 1, characterized in that: The hydrogen cooler is connected to the hydrogen separator via a flange, and the oxygen cooler is connected to the oxygen separator via a flange. Both the hydrogen scrubber and the oxygen scrubber include a scrubber housing and a cooling coil disposed within the scrubber housing. The cooling coil is connected to an external pipeline via a flange on the side wall of the scrubber housing.

4. The alkaline electrolysis hydrogen production system according to claim 1, characterized in that: The three-tower drying system includes a first drying tower, a second drying tower, and a third drying tower. The hydrogen outlet of the third gas-liquid separator is connected to the inlet of the first drying tower. The outlet of the first drying tower is connected to the inlet of the hydrogen filter and the hydrogen inlet of the second preheater. The hydrogen outlet of the second preheater is connected to the hydrogen inlet of the regeneration heater. The hydrogen outlet of the regeneration heater is connected to the inlet of the second drying tower. The outlet of the second drying tower is connected to the hydrogen inlet of the second cooler. The hydrogen outlet of the second cooler is connected to the inlet of the fourth gas-liquid separator. The hydrogen outlet of the fourth gas-liquid separator is connected to the inlet of the third drying tower. The outlet of the third drying tower is connected to the inlet of the hydrogen filter.

5. The alkaline electrolysis hydrogen production system according to claim 1, characterized in that: The first preheater, the second preheater, the hydrogen precooler, and the oxygen precooler all employ shell-and-tube heat exchangers. The first cooler and the second cooler use chilled water at 7°C to 12°C for cooling on their low-temperature sides.

6. The alkaline electrolysis hydrogen production system according to claim 1, characterized in that: The cooling water circulation loop includes a cooling water supply main pipe and a cooling water return main pipe; The cooling water inlet of the alkali cooler is connected to the cooling water supply main pipe. The cooling water outlet of the alkali cooler is connected to the cooling water inlet of the hydrogen precooler, the cooling water inlet of the oxygen precooler, and the water-side inlet of the first preheater. The water-side outlet of the first preheater is connected to the water-side inlet of the second preheater. The water-side outlet of the second preheater is connected to the inlet of the cooling coil of the hydrogen scrubber and the oxygen scrubber. The water-side outlet of the second preheater is also connected to the cooling water return main pipe. The outlets of the cooling coils of the hydrogen scrubber and the oxygen scrubber are connected to the cooling water inlet of the hydrogen cooler and the cooling water inlet of the oxygen cooler, respectively. The cooling water outlets of the hydrogen cooler and the oxygen cooler are connected to the water-side inlet of the first preheater. The cooling water outlets of the hydrogen precooler and the oxygen precooler are both connected to the cooling water return main.

7. The alkaline electrolysis hydrogen production system according to claim 6, characterized in that: After the cooling water outlet of the hydrogen precooler is connected to the cooling water outlet of the oxygen precooler, it is connected to the cooling water return main pipe through a return water pipe, and a first flow valve is installed on the return water pipe. The return water pipe is also connected to the water-side inlet of the second preheater via a return water branch pipe. The return water branch pipe is located on the outlet side of the first flow valve, and a second flow valve is installed on the return water branch pipe. A shut-off valve is provided between the water-side outlet of the second preheater and the inlet of the cooling coil of the hydrogen scrubber and the oxygen scrubber.

8. The alkaline electrolysis hydrogen production system according to any one of claims 1-7, characterized in that: It also includes a controller, and the alkaline solution circulation loop, the hydrogen-oxygen separation loop, the hydrogen deoxygenation and drying loop, and the cooling water circulation loop are all communicatively connected to the controller.

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