Alkaline electrolytic hydrogen production system

Abstract

The invention belongs to the field of electrolytic hydrogen production, and discloses an alkaline electrolytic hydrogen production system which comprises an alkali liquor circulation loop, a hydrogen-oxygen separation loop, a hydrogen deoxidizing and drying loop and a cooling water circulation loop. Wherein the alkali liquor circulation loop comprises an electrolytic cell, a hydrogen precooler, an oxygen precooler, a hydrogen separator, an oxygen separator and an alkali liquor cooler, alkali liquor from the hydrogen separator and the oxygen separator enters the alkali liquor cooler, the alkali liquor is subjected to secondary cooling by cooling water from the cooling water circulation loop, and then the alkali liquor enters the electrolytic cell for electrolytic hydrogen production; then the hydrogen enters the hydrogen precooler and the oxygen precooler and is subjected to primary cooling by cooling water from the alkali liquor cooler, gradient cooling is realized by a cooling mode of two heat exchange processes, heat recovery in the electrolytic hydrogen production process is performed to the greatest extent, and the heat exchange efficiency of the system is improved; and the recovered heat is used for hydrogen preheating, so that the load of subsequent hydrogen-oxygen separation and hydrogen drying treatment can be reduced, and the energy consumption of the system is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic hydrogen production, and particularly to an alkaline electrolytic hydrogen production system. Background Art

[0002] As the green hydrogen industry, an important carrier of the clean energy system, enters a rapid development stage, the alkaline electrolytic water hydrogen production technology has become one of the mainstream routes for large-scale hydrogen production due to its advantages such as mature process and controllable cost. However, in the process of the industry developing towards large-scale and intensive, the traditional alkaline electrolytic hydrogen production system has exposed significant technical bottlenecks: most existing devices adopt a decentralized small-scale design, and the unit hydrogen production energy consumption in the electrolysis process generally remains in the high range of 4.3 - 4.8 kWh / Nm 3 in the high position range, showing an obvious gap with the energy-saving target of below 4.0 kWh / Nm 3 expected by the industry.

[0003] A large amount of low-grade waste heat at 30 - 80°C is generated during the operation of the electrolysis system. The current cooling scheme usually uses the single-temperature cooling water prepared by an air cooling tower for direct heat exchange, which not only causes repeated consumption of cooling water in multiple links such as the electrolyzer, separation device, and lye circulation system, but also leads to the mixing loss of thermal energy at different temperature levels. For every 1 ton of hydrogen produced by the alkaline electrolytic hydrogen production system, 30 - 40 tons of water is consumed, and about 50% of the water resource consumption comes from the evaporation loss during the cooling process of the air cooling tower. This extensive thermal management method not only aggravates the waste of water resources but also reduces the overall energy efficiency of the system, severely restricting the large-scale commercial application of the alkaline electrolytic hydrogen production technology. Summary of the Invention

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

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] The present invention provides an alkaline electrolytic hydrogen production system, including:

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

[0008] Hydrogen-oxygen separation loop, the hydrogen separator is connected to the hydrogen-oxygen separation loop, and the hydrogen-oxygen separation loop can separate hydrogen and oxygen;

[0009] Hydrogen deoxidation and drying loop, the hydrogen-oxygen separation loop is connected to the hydrogen deoxidation and drying loop, and the hydrogen deoxidation and drying loop can dry the separated hydrogen;

[0010] Cooling water circulation loop, the alkali solution cooler is also connected to the cooling water circulation loop. The cooling water outlet of the alkali solution cooler is respectively connected to the cooling water inlets of the hydrogen pre-cooler and the oxygen pre-cooler, and the cooling water outlets of the hydrogen pre-cooler and the oxygen pre-cooler are both connected to the cooling water circulation loop.

[0011] Preferably, the alkali solution outlets of the hydrogen separator and the oxygen separator are both connected to the alkali solution inlet of the alkali solution cooler by an alkali solution circulation pump.

[0012] Preferably, the hydrogen-oxygen separation loop 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 is connected to it. 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 liquid return port of the hydrogen separator; the oxygen cooler is located at the top of the oxygen separator and is connected to it. 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 liquid return 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 water return 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 water return port of the oxygen separator.

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

[0016] Both the hydrogen scrubber and the oxygen scrubber include a scrubber housing and cooling coils disposed within the scrubber housing, and the cooling coils are connected to an external pipeline by flanges on the side wall of the scrubber housing.

[0017] Preferably, the oxygen deoxidation and drying circuit includes a first preheater, a hydrogen recuperator, a deoxidation heater, a deoxidation 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 recuperator, the low-temperature outlet of the hydrogen recuperator is connected to the inlet of the deoxidation heater, the outlet of the deoxidation heater is connected to the inlet of the deoxidation tower, the outlet of the deoxidation tower is connected to the high-temperature inlet of the hydrogen recuperator, the high-temperature outlet of the hydrogen recuperator 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, and the three-tower drying system can perform drying treatment on 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 respectively 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, and 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 all adopt shell-and-tube heat exchangers;

[0021] The low-temperature sides of the first cooler and the second cooler are cooled with chilled water at 7°C to 12°C.

[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 lye cooler is connected to the cooling water supply main pipe. The cooling water outlet of the lye cooler is respectively connected to the cooling water inlets of the hydrogen precooler, 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 respectively connected to the inlets of the cooling coils 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 and then respectively connected to the cooling water inlets of the hydrogen cooler and the oxygen cooler. The cooling water outlets of the hydrogen cooler and the oxygen cooler are connected and then 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 pipe.

[0025] Preferably, after the cooling water outlets of the hydrogen precooler and the oxygen precooler are connected, they are connected to the cooling water return main pipe through a return water pipe, and a first flow valve is provided on the return water pipe;

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

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

[0028] Preferably, the alkaline electrolytic hydrogen production system further includes a controller, and the lye circulation loop, the hydrogen-oxygen separation loop, the hydrogen deoxidation and drying loop, and the cooling water circulation loop are all communicatively connected to the controller.

[0029] The present invention has achieved the following technical effects compared with the related art: The alkaline electrolytic hydrogen production system of the present invention includes an alkali solution circulation circuit, a hydrogen-oxygen separation circuit, a hydrogen deoxidation and drying circuit, and a cooling water circulation circuit; wherein, the alkali solution circulation circuit includes an electrolytic cell, a hydrogen pre-cooler, an oxygen pre-cooler, a hydrogen separator, an oxygen separator, and an alkali solution cooler. Water in the alkali solution undergoes a decomposition reaction in the electrolytic cell. The cathode outlet of the electrolytic cell is connected to the alkali solution inlet of the hydrogen pre-cooler, and the alkali solution outlet of the hydrogen pre-cooler 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 pre-cooler, and the alkali solution outlet of the oxygen pre-cooler is connected to the alkali solution inlet of the oxygen separator; the alkali solution outlets of the hydrogen separator and the oxygen separator are both connected to the alkali solution inlet of the alkali solution cooler, and the alkali solution outlet of the alkali solution 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, and the hydrogen-oxygen separation circuit can separate hydrogen and oxygen; the hydrogen-oxygen separation circuit is connected to the hydrogen deoxidation and drying circuit, and the hydrogen deoxidation and drying circuit can perform drying treatment on the separated hydrogen; the alkali solution cooler is also connected to the cooling water circulation circuit. The cooling water outlet of the alkali solution cooler is respectively connected to the cooling water inlet of the hydrogen pre-cooler and the cooling water inlet of the oxygen pre-cooler, and the cooling water outlets of the hydrogen pre-cooler and the oxygen pre-cooler are both connected to the cooling water circulation circuit.

[0030] In the alkaline electrolytic hydrogen production system of the present invention, the alkali solution from the hydrogen separator and the oxygen separator enters the alkali solution cooler, and the alkali solution is secondarily cooled by the cooling water from the cooling water circulation circuit, and then enters the electrolytic cell for electrolytic hydrogen production. The hydrogen (mixture) containing alkali solution and the oxygen (mixture) containing alkali solution produced are respectively introduced into the hydrogen pre-cooler and the oxygen pre-cooler, and are primarily cooled by the cooling water from the alkali solution cooler. The cooled gas-liquid mixture enters the hydrogen separator and the oxygen separator respectively to complete the alkali solution circulation. In the above process, the cooling water is primarily cooled in the alkali solution cooler, and the temperature of the cooling water rises. The cooling water is secondarily cooled in the hydrogen separator and the oxygen separator, and the temperature of the cooling water is raised again. The cooling method of performing two heat exchange processes realizes gradient cooling, maximally recovers the heat in the electrolytic hydrogen production process, and improves the heat exchange efficiency of the system. Compared with the prior art in which the alkali solution is only cooled by the alkali solution cooler, the cooling water consumption in the alkali solution cooling process is saved; the present invention uses the recovered heat for hydrogen preheating, which can reduce the load of subsequent hydrogen-oxygen separation and hydrogen drying treatment, and further reduce the system energy consumption; the cooling water circulation circuit of the present invention uses cooling water as the working medium to recover and utilize the heat in the electrolytic hydrogen production system, greatly reducing the cooling water consumption of the system and reducing the power consumption and water consumption in the cooling water production process. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following will briefly introduce the accompanying drawings required for use in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

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

[0033] In the figure: 101, hydrogen pre-cooler; 102, oxygen pre-cooler; 103, lye cooler; 104, first pre-heater; 105, first cooler; 106, second cooler; 107, second pre-heater; 108, hydrogen regenerative heat exchanger; 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; 503, third gas-liquid separator; 504, fourth gas-liquid separator; 601, deoxidation heater; 602, regeneration heater; 7, deoxidation tower; 8, three-tower drying system; 801, first drying tower; 802, second drying tower; 803, third drying tower; 9, lye circulation pump; 10, hydrogen filter; 11, electrolytic cell; 001, first flow valve; 002, second flow valve; 003, cut-off valve; 004, return water pipeline; 005, return water branch pipe.

[0034] CWS, cooling water supply main pipe; CWR, cooling water return main pipe. Detailed implementation manners

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide an alkaline electrolytic 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 the system energy consumption.

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

[0038] Embodiment 1

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

[0040] The alkaline electrolytic hydrogen production system of the present invention is such that the alkaline solutions from the hydrogen separator 201 and the oxygen separator 202 enter the alkaline solution cooler 103, where the alkaline solutions are secondarily cooled by the cooling water from the cooling water circulation loop. Then they enter the electrolyzer 11 for electrolytic hydrogen production. The hydrogen-containing alkaline solution (gas-liquid mixture) and the oxygen-containing alkaline solution (gas-liquid mixture) produced enter the hydrogen pre-cooler 101 and the oxygen pre-cooler 102 respectively, and are primarily cooled by the cooling water from the alkaline solution cooler 103. The cooled gas-liquid mixtures enter 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 alkaline solution cooler 103, and its temperature rises. It undergoes secondary cooling in the hydrogen separator 201 and the oxygen separator 202, and the temperature of the cooling water is raised again. The cooling method with two heat exchange processes achieves gradient cooling, maximizing the heat recovery during the electrolytic hydrogen production process, improving the heat exchange efficiency of the system. Compared with the prior art where the alkaline solution is only cooled by the alkaline solution cooler, the cooling water consumption in the alkaline solution cooling process is saved; the present invention uses the recovered heat for hydrogen preheating, which can reduce the load of subsequent hydrogen-oxygen separation and hydrogen drying processes, further reducing the system energy consumption; the cooling water circulation loop of the present invention uses cooling water as the working medium to recover and utilize the heat in the electrolytic hydrogen production system, greatly reducing the system cooling water consumption and the power consumption and water consumption in the cooling water production process.

[0041] Among them, the alkaline solution outlet of the hydrogen separator 201 and the alkaline solution outlet of the oxygen separator 202 are both connected to the alkaline solution inlet of the alkaline solution cooler 103 by the alkaline solution circulation pump 9, ensuring the smooth circulation and transportation of the alkaline solution, avoiding the backflow of the alkaline solution, and ensuring the working 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 at the top of the hydrogen separator 201 and is connected to it. 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 liquid return port of the hydrogen separator 201; the oxygen cooler 302 is located at the top of the oxygen separator 202 and is connected to it. 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 liquid 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 water return 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 an external collection pipeline, and the liquid outlet of the second gas-liquid separator 502 is connected to the water return port of the oxygen separator 202.

[0045] When the system operates, the hydrogen in the hydrogen cooler 301 and the oxygen in the oxygen cooler 302 are first-stage cooled by the cooling water from the hydrogen scrubber 401 and the oxygen scrubber 402. The cooled hydrogen and oxygen respectively enter the hydrogen scrubber 401 and the oxygen scrubber 402 for second-stage cooling. In the above process, the cooling water is first-stage cooled in the hydrogen scrubber 401 and the oxygen scrubber 402, and its temperature rises. Then it is second-stage cooled in the hydrogen cooler 301 and the oxygen cooler 302, and its temperature is raised again. The heat of the lye is recovered in a cascade manner, improving the heat exchange efficiency of the system. Similarly, it can reduce the consumption of cooling water and save the energy consumption of the system.

[0046] The hydrogen and oxygen after second-stage cooling respectively enter the first gas-liquid separator 501 and the second gas-liquid separator 502 for gas-liquid separation. The separated hydrogen enters the subsequent hydrogen deoxygenation and drying circuit, and the separated oxygen can be input into an external collection pipeline for collection and standby, reasonably utilizing resources to avoid waste.

[0047] In this specific embodiment, the hydrogen cooler 301 is connected to the hydrogen separator 201 by a flange, and the oxygen cooler 302 is connected to the oxygen separator 202 by a flange, improving the disassembly and assembly convenience of the hydrogen cooler 301 and the hydrogen separator 201, and the oxygen cooler 302 and the oxygen separator 202, providing convenience for the 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 cooling coils disposed inside the scrubber housing. The cooling coils are connected to external pipelines by flanges on the side walls of the scrubber housing, improving the operation convenience of connecting the cooling coils to external pipelines on the premise of avoiding leakage of the scrubber housing.

[0049] More specifically, the oxygen deoxygenation and drying circuit includes a first preheater 104, a hydrogen recuperator 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 recuperator 108. The low-temperature outlet of the hydrogen recuperator 108 is connected to the inlet of the deoxidation heater 601. The outlet of the deoxidation heater 601 is connected to the inlet of the deoxidation tower 7. The outlet of the deoxidation tower 7 is connected to the high-temperature inlet of the hydrogen recuperator 108. The high-temperature outlet of the hydrogen recuperator 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, and the three-tower drying system 8 can perform drying treatment on the separated hydrogen.

[0051] In the oxygen deoxidation and 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 cooling water after being heated in the first preheater 104. The preheated hydrogen enters the low-temperature side of the hydrogen recuperator 108 for heat regeneration, and then enters the deoxidation heater 601 for heating. The preheating of the hydrogen reduces the heating load of the subsequent deoxidation heater 601, which helps to save the system energy consumption. The high-temperature hydrogen heated by the deoxidation heater 601 enters the high-temperature side of the hydrogen recuperator 108 and then the 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 respectively 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 gas separated by the third gas-liquid separator 503 enters the first drying tower 801 for drying treatment. Most of the hydrogen gas after preliminary drying is filtered by the hydrogen filter 10 and then input into the subsequent process. The hydrogen filter 10 can effectively prevent the adsorbent from being mixed in the hydrogen gas; a part of the hydrogen gas enters the second preheater 107. The hydrogen gas preheated by the second preheater 107 enters the regeneration heater 602 to be heated and raised in temperature to form a high-temperature regeneration gas. The high-temperature regeneration gas is introduced into the second drying tower 802 to heat the saturated adsorbent, so that the moisture is desorbed and discharged with the gas, realizing the regeneration of the adsorbent; the wet and hot gas in the second drying tower 802 enters the second cooler 106 to be cooled down. The water vapor condenses into liquid water, and then enters the fourth gas-liquid separator 504 for gas-liquid separation again to obtain dry hydrogen gas. The dried hydrogen gas enters the third drying tower 803 for re-drying treatment, and then is filtered by the hydrogen filter 10 and enters the subsequent process. 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 work in a functional cycle of "drying" - "regeneration" - "re-drying" to achieve continuous gas supply and high-efficiency dehydration of the system. The cycle work includes three stages. In each stage, in the three drying towers of the three-tower drying system 8, one drying tower performs drying operation, one drying tower performs the regeneration operation of the adsorbent, and the other drying tower performs re-drying operation, so that the system can continuously output dry hydrogen gas. While continuously and efficiently dehydrating hydrogen gas, the energy consumption optimization of the system is realized.

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

[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 7°C to 12°C. In actual application, the temperature range of the cooling water can also be adjusted according to the actual production conditions to meet different specific cooling requirements.

[0056] Furthermore, the cooling water circulation circuit includes a cooling water supply main pipe CWS and a cooling water return main pipe CWR to meet the cooling water circulation requirements of the system.

[0057] Among them, the cooling water inlet of the lye cooler 103 is connected to the cooling water supply main pipe CWS. The cooling water outlet of the lye cooler 103 is respectively connected to the cooling water inlet of the hydrogen pre-cooler 101, the cooling water inlet of the oxygen pre-cooler 102, and the water-side inlet of the first pre-heater 104. The water-side outlet of the first pre-heater 104 is connected to the water-side inlet of the second pre-heater 107. The water-side outlet of the second pre-heater 107 is respectively connected to the inlets of the cooling coils of the hydrogen scrubber 401 and the oxygen scrubber 402. The water-side outlet of the second pre-heater 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 respectively connected to the cooling water inlet of the hydrogen cooler 301 and the cooling water inlet of the oxygen cooler 302. 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 pre-heater 104.

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

[0059] For the convenience of control, after the cooling water outlets of the hydrogen pre-cooler 101 and the oxygen pre-cooler 102 are connected, they are connected to the cooling water return main pipe CWR by means of the return water pipe 004. A first flow valve 001 is provided on the return water pipe 004. The return water pipe 004 also uses a return water branch pipe 005 to be connected to the water-side inlet of the second pre-heater 107. The return water branch pipe 005 is located on the outlet side of the first flow valve 001. A second flow valve 002 is provided on the return water branch pipe 005.

[0060] Correspondingly, a cut-off valve 003 is provided between the water-side outlet of the second pre-heater 107 and the inlets of the cooling coils of the hydrogen scrubber 401 and the oxygen scrubber 402.

[0061] Meanwhile, the alkaline electrolytic hydrogen production system of the present invention further includes a controller. The lye circulation loop, the hydrogen-oxygen separation loop, the hydrogen deoxidation and drying loop, and the cooling water circulation loop are all communicatively connected to the controller to control the working states of each loop and improve the automation degree of the system. In addition, monitoring elements are provided in the above-mentioned lye circulation loop, hydrogen-oxygen separation loop, hydrogen deoxidation and drying loop, and cooling water circulation loop to monitor the working parameters such as temperature and pressure of each loop. The detection elements are communicatively connected to the controller to adjust the working state of the system in real time according to the system parameters monitored by the monitoring elements and improve the working safety factor of the system. It should be explained here that the specific structure and working principle of the controller are both conventional means for those skilled in the art and will not be elaborated here.

[0062] During the operation of the system, 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 (higher) than the set value, the opening degree of the first flow valve 001 can be automatically reduced (increased), and the cooling water flow rate into the first preheater 104 can be increased (decreased); when the outlet temperature of the second preheater 107 is lower (higher) than the set value, the opening degree of the first flow valve 001 can be automatically increased (decreased), and the cooling water flow rate into the second preheater 107 can be increased (decreased), finally achieving precise temperature control.

[0063] In addition, when the supply of cooling water is insufficient, the switch of the cut-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, reducing the water supply load of the cooling water supply main pipe CWS.

[0064] In the alkaline electrolytic hydrogen production system of the present invention, by setting the hydrogen pre-cooler 101 and the oxygen pre-cooler 102, and performing a cascade cooling design on the coolers, pre-coolers and scrubbers in the system according to the working medium temperature, the heat recovery in the electrolytic hydrogen production process is maximally achieved; by using the recovered heat for hydrogen preheating, the electrical loads of the deoxidation heater 601 and the regeneration heater 602 can be reduced, realizing the energy saving of the system.

[0065] Embodiment 2

[0066] This embodiment provides an alkaline electrolytic hydrogen production system. In this embodiment, the hydrogen production scale of the system is 1000 Nm 3 / h, and the designed water supply temperature of the system cooling water is 32°C. In the caustic solution circulation loop, the caustic solution circulation pump 9 pumps the caustic solution from the outlets of the hydrogen separator 201 and the oxygen separator 202 into the caustic solution cooler 103. The caustic solution is cooled in two stages by the cooling water from the cooling water supply main pipe CWS, and then enters the electrolytic cell 11 for electrolytic hydrogen production. The hydrogen and caustic solution mixture and the oxygen and caustic solution mixture respectively enter the hydrogen pre-cooler 101 and the oxygen pre-cooler 102, and are cooled in the first stage by the cooling water from the caustic solution cooler 103. The cooled gas-liquid mixture respectively enters the hydrogen separator 201 and the oxygen separator 202 to complete the caustic solution circulation. In the above process, the cooling water is cooled in the first stage in the caustic solution cooler 103, and the water temperature rises. It is cooled in the second stage in the hydrogen separator 201 and the oxygen separator 202, and the water temperature rises again; in the two heat exchange processes, in the first-stage cooling process, the caustic solution temperature is cooled from 90°C to 80°C, and the cooling water is heated from 51°C to 65°C; in the second-stage cooling process, the caustic solution temperature continues to drop from 80°C to 65°C, and the cooling water is heated from 32°C to 51°C. After two-stage cascade waste heat recovery, the cooling water temperature is increased from 32°C to 65°C.

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

[0068]

[0069] In the traditional process, only the lye cooler 103 is used for cooling. The outlet temperature of the cooling water is about 45°C, and the heat exchange efficiency is:

[0070]

[0071] Compared with the traditional lye cooling process, the heat exchange efficiency of the alkaline electrolytic hydrogen production system of the present invention is increased by about 2.5 times, that is, the cooling water consumption in the lye cooling process is reduced by about 60%.

[0072] In the hydrogen-oxygen separation circuit, the hydrogen in the hydrogen cooler 301 and the oxygen in the oxygen cooler 302 are first cooled by the cooling water from the hydrogen scrubber 401 and the oxygen scrubber 402. After cooling, the hydrogen and oxygen enter the hydrogen scrubber 401 and the oxygen scrubber 402 respectively, and are secondarily cooled by the cooling water from the cooling water supply main pipe CWS and the second preheater 107 in the cooling coils. In the above process, the cooling water is first cooled in the hydrogen scrubber 401 and the oxygen scrubber 402, and the temperature is increased. Then it is secondarily cooled in the hydrogen cooler 301 and the oxygen cooler 302, and the temperature is increased again, achieving a cascaded recovery of the lye heat.

[0073] The cooling water consumption in the hydrogen-oxygen separation circuit is about 3% of that in the lye circulation circuit. The heat exchange efficiency is basically the same as that in the lye circulation circuit, about 56.9%, and it is increased by 2.5 times.

[0074] The cooling water after two-stage cooling in the hydrogen pre-cooler 101, oxygen pre-cooler 102, hydrogen cooler 301, and oxygen cooler 302 is collected through pipelines and enters the water side pipeline of the first preheater 104 to preheat the hydrogen. The water temperature is reduced from 65°C to 45°C, and the hydrogen temperature is increased from 40°C to 60°C. The preheated hydrogen passes through the cold side pipeline of the hydrogen recuperator 108 to be reheated to 100°C, and then is heated to 120°C by the deoxygenation heater 601. The generated high-temperature hydrogen enters the deoxygenation tower 7 to complete deoxygenation, and then is cooled to 100°C through the hot side pipeline of the hydrogen recuperator 108. After the above process, the inlet temperature of the original deoxygenation heater 601 can be increased from 80°C to 100°C, and the heat load is reduced by about 50%.

[0075] The outlet water 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 is reduced from 45°C to 32°C, and the hydrogen temperature is increased from 26°C to 40°C. The preheated hydrogen enters the regeneration heater 602 to be heated to 300°C, and the heat load is reduced by about 5%.

[0076] In this specific embodiment, the PID control system is used to monitor the outlet temperatures of the first preheater 104 and the second preheater 107. When the outlet temperature of the first preheater 104 is lower (higher) than the set value, the opening degree of the first flow valve 001 can be automatically reduced (increased), and the water flow rate into the first preheater 104 can be increased (decreased). When the outlet temperature of the second preheater 107 is lower (higher) than the set value, the opening degree of the first flow valve 001 can be automatically increased (decreased), and the water flow rate into the second preheater 107 can be increased (decreased), so as to finally achieve precise temperature control.

[0077] It should also be noted that when the cooling water supply is insufficient, by turning on the switch of the cutoff valve 003, the preheated cooling water in the second preheater 107 can be introduced into the hydrogen scrubber 401 and the oxygen scrubber 402 to reduce the water supply load of the cooling water supply main pipe CWS.

[0078] In the present invention, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An alkaline electrolysis hydrogen production system, characterized in that: include: An alkali liquid circulation loop, comprising an electrolyzer, a hydrogen precooler, an oxygen precooler, a hydrogen separator, an oxygen separator and an alkali liquid cooler, wherein water in the alkali liquid undergoes a decomposition reaction in the electrolyzer, the cathode outlet of the electrolyzer is connected to the alkali liquid inlet of the hydrogen precooler, and the alkali liquid outlet of the hydrogen precooler is connected to the alkali liquid inlet of the hydrogen separator; the anode outlet of the electrolyzer is connected to the alkali liquid inlet of the oxygen precooler, and the alkali liquid outlet of the oxygen precooler is connected to the alkali liquid inlet of the oxygen separator; the alkali liquid outlet of the hydrogen separator and the alkali liquid outlet of the oxygen separator are both connected to the alkali liquid inlet of the alkali liquid cooler, and the alkali liquid outlet of the alkali liquid cooler is connected to the electrolyzer; the hydrogen separator is also connected to the oxygen separator; a hydrogen-oxygen separation circuit, wherein the hydrogen separator is in communication with the hydrogen-oxygen separation circuit, and the hydrogen-oxygen separation circuit is capable of separating hydrogen from oxygen; A hydrogen deoxidation and drying circuit, wherein the hydrogen-oxygen separation circuit is connected to the hydrogen deoxidation and drying circuit, and the hydrogen deoxidation and drying circuit is capable of drying the separated hydrogen; A cooling water circulation loop, the alkali liquid cooler is also connected to the cooling water circulation loop, the cooling water outlet of the alkali liquid cooler is respectively connected to the cooling water inlet of the hydrogen precooler and the cooling water inlet of the oxygen precooler, and 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.

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

3. The alkaline electrolysis hydrogen production system according to claim 1, characterized in that: 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 liquid return 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 liquid return 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 water return 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 a water return port of the oxygen separator.

4. The alkaline electrolysis hydrogen production system according to claim 3, 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; The hydrogen scrubber and the oxygen scrubber both include a scrubber shell and a cooling coil disposed in the scrubber shell. The cooling coil is connected to an external pipeline via a flange on a side wall of the scrubber shell.

5. The alkaline electrolysis hydrogen production system according to claim 3, characterized in that: The oxygen deoxidation drying circuit includes a first preheater, a hydrogen regenerator, a deoxidation heater, a deoxidation 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 reheater, the low-temperature outlet of the hydrogen reheater is connected to the inlet of the deoxidation heater, the outlet of the deoxidation heater is connected to the inlet of the deoxidation tower, the outlet of the deoxidation tower is connected to the high-temperature inlet of the hydrogen reheater, the high-temperature outlet of the hydrogen reheater 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, and the three-tower drying system is capable of drying the separated hydrogen.

6. The alkaline electrolysis hydrogen production system according to claim 5, 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 respectively 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, and the outlet of the third drying tower is connected to the inlet of the hydrogen filter.

7. The alkaline electrolysis hydrogen production system according to claim 5, characterized in that: The first preheater, the second preheater, the hydrogen precooler and the oxygen precooler all adopt shell and tube heat exchangers; The low-temperature sides of the first cooler and the second cooler are cooled by chilled water at 7° C. to 12° C.

8. The alkaline electrolysis hydrogen production system according to claim 5, 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 liquid cooler is connected to the cooling water supply main pipe, the cooling water outlet of the alkali liquid cooler is respectively 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 respectively connected to the inlets of the cooling coils 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 respectively connected to the cooling water inlet of the hydrogen cooler and the cooling water inlet of the oxygen cooler, the cooling water outlet of the hydrogen cooler and the cooling water outlet of the oxygen cooler are connected to the water side inlet of the first preheater; The cooling water outlet of the hydrogen precooler and the cooling water outlet of the oxygen precooler are both connected to the cooling water return main pipe.

9. The alkaline electrolysis hydrogen production system according to claim 8, characterized in that: After the cooling water outlet of the hydrogen precooler is connected to the cooling water outlet of the oxygen precooler, the cooling water outlet is connected to the cooling water return main pipe through a return pipe, and a first flow valve is provided on the return pipe; The return water pipeline is also connected to the water side inlet of the second preheater through a return water branch pipe, the return water branch pipe is located on the outlet side of the first flow valve, and the second flow valve is provided on the return water branch pipe; A shutoff valve is provided between the water-side outlet of the second preheater and the inlets of the cooling coils of the hydrogen scrubber and the oxygen scrubber.

10. The alkaline electrolysis hydrogen production system according to any one of claims 1 to 9, characterized in that: It also includes a controller, and the alkali solution circulation loop, the hydrogen and oxygen separation loop, the hydrogen deoxidation and drying loop, and the cooling water circulation loop are all communicatively connected to the controller.

Images