Alkaline electrolytic cell coupling biomass dark fermentation combined hydrogen production energy-saving system and method

Abstract

The invention provides an alkaline electrolytic cell coupling biomass dark fermentation combined hydrogen production energy-saving system and method. Comprising an alkaline electrolytic bath, a gas-liquid separator of a coupling heat exchanger, a primary heat exchanger, an oxygen drying and purifying device, a hydrogen drying and purifying device, an alkali liquor reflux pump, a biomass substrate supply device, a dark fermentation hydrogen production reactor, a heat preservation heater and a heat conduction oil circulating pump, the number of the gas-liquid separators of the coupling heat exchangers is two, and the two gas-liquid separators are the gas-liquid separator of the first coupling heat exchanger and the gas-liquid separator of the second coupling heat exchanger respectively. According to the alkaline electrolytic cell coupling biomass dark fermentation combined hydrogen production energy-saving system and method, two hydrogen production systems are coupled, the utilization efficiency of waste heat and a hydrogen production auxiliary system is improved, the overall hydrogen production capacity and hydrogen production stability of the system are improved, and meanwhile energy conservation and consumption reduction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen production by water electrolysis and biomass hydrogen production, and specifically relates to an energy-saving system and method for combined hydrogen production by alkaline electrolysis cell coupled with biomass dark fermentation. Background Art

[0002] Alkaline water electrolysis refers to the process of producing hydrogen by electrolyzing water in an alkaline electrolyte environment, and the electrolyte is generally a KOH solution or a NaOH solution. The alkaline electrolyzer is the core equipment of the hydrogen production system. In the prior art, the alkaline electrolyzer hydrogen production process has the following problems: (1) When the alkaline electrolyzer produces hydrogen, the energy of the high-temperature gas-liquid mixture produced is not fully utilized, resulting in energy waste; (2) The hydrogen production rate of the alkaline electrolyzer is easily affected by the volatility of wind and solar power sources. Therefore, the stability of the hydrogen flow rate it ultimately provides is poor, which increases the difficulty of hydrogen utilization. Summary of the invention

[0003] In view of the defects of the prior art, the present invention provides an energy-saving system and method for hydrogen production by coupling alkaline electrolysis cell with biomass dark fermentation, which can effectively solve the above problems.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The present invention provides an alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system, comprising an alkaline electrolyzer (1), a gas-liquid separator (2) coupled with a heat exchanger, a primary heat exchanger (3), an oxygen drying and purification device (4), a hydrogen drying and purification device (5), an alkali liquid reflux pump (6), a biomass substrate supply device (8), a dark fermentation hydrogen production reactor (9), a heat preservation heater (10) and a heat transfer oil circulation pump (11); wherein two gas-liquid separators (2) coupled with heat exchangers are provided, namely: a gas-liquid separator (2A) of a first coupled heat exchanger and a gas-liquid separator (2B) of a second coupled heat exchanger;

[0006] The biomass substrate supply port of the dark fermentation hydrogen production reactor (9) is connected to the biomass substrate supply device (8); the heat preservation heater (10) is installed at the bottom of the dark fermentation hydrogen production reactor (9); heat transfer oil flows in the heat preservation heater (10); the heat transfer oil outlet of the heat preservation heater (10) is connected to the cold medium inlet of the primary heat exchanger (3) through the heat transfer oil circulation pump (11); after being heated by the primary heat exchanger (3), the heat transfer oil output from the cold medium outlet of the primary heat exchanger (3) is respectively connected to the lower heat transfer oil inlets of the gas-liquid separator (2A) of the first coupled heat exchanger and the gas-liquid separator (2B) of the second coupled heat exchanger; the upper heat transfer oil outlets of the gas-liquid separator (2A) of the first coupled heat exchanger and the gas-liquid separator (2B) of the second coupled heat exchanger are connected to the heat transfer oil reflux port of the heat preservation heater (10) through pipelines, completing the heat transfer oil circulation loop;

[0007] The alkaline electrolyzer (1) has a first high-temperature gas-liquid mixture outlet and a second high-temperature gas-liquid mixture outlet; the first high-temperature gas-liquid mixture outlet is used to output a first high-temperature gas-liquid mixture formed by hydrogen and alkaline liquid; the second high-temperature gas-liquid mixture outlet is used to output a second high-temperature gas-liquid mixture formed by oxygen and alkaline liquid; the first high-temperature gas-liquid mixture outlet is connected to a first high-temperature gas-liquid mixture inlet of a gas-liquid separator (2A) of the first coupled heat exchanger; the second high-temperature gas-liquid mixture outlet is connected to a second high-temperature gas-liquid mixture inlet of a gas-liquid separator (2B) of the second coupled heat exchanger;

[0008] The gas-liquid separator (2A) of the first coupled heat exchanger performs gas-liquid separation on the first high-temperature gas-liquid mixture under the action of the heat transfer oil absorbing heat and cooling, and the top is a high-temperature hydrogen outlet, and the bottom is a first alkali liquid outlet; the gas-liquid separator (2B) of the second coupled heat exchanger performs gas-liquid separation on the second high-temperature gas-liquid mixture under the action of the heat transfer oil absorbing heat and cooling, and the top is a high-temperature oxygen outlet, and the bottom is a second alkali liquid outlet;

[0009] The first alkali solution outlet and the second alkali solution outlet are both connected to the alkali solution inlet of the alkali solution reflux pump (6); the alkali solution outlet of the alkali solution reflux pump (6) is connected to the inside of the alkaline electrolytic cell (1), forming an alkali solution circulation loop;

[0010] The high-temperature hydrogen outlet of the gas-liquid separator (2A) of the first coupled heat exchanger is connected to the hydrogen heat source inlet of the primary heat exchanger (3), and after heat exchange with the heat transfer oil flowing through, the high-temperature hydrogen flows out from the hydrogen heat source outlet of the primary heat exchanger (3) and flows into the inlet of the hydrogen drying and purification device (5), thereby completing the thermal energy utilization of the high-temperature hydrogen;

[0011] The high-temperature oxygen outlet of the gas-liquid separator (2B) of the second coupled heat exchanger is connected to the oxygen heat source inlet of the primary heat exchanger (3). After heat exchange with the heat transfer oil flowing through, the high-temperature oxygen flows out from the oxygen heat source outlet of the primary heat exchanger (3) and flows into the inlet of the oxygen drying and purification device (4), thereby completing the thermal energy utilization of the high-temperature oxygen.

[0012] Preferably, it also includes: an alkali liquid water tank (7);

[0013] The alkali liquid water tank (7) is respectively connected to the alkali liquid inlet of the alkali liquid reflux pump (6) and the reaction chamber of the dark fermentation hydrogen production reactor (9).

[0014] Preferably, a flow regulating valve (12) is installed in the pipeline between the upper heat transfer oil outlet of the gas-liquid separator (2A) of the first coupled heat exchanger and the upper heat transfer oil outlet of the gas-liquid separator (2B) of the second coupled heat exchanger and the heat transfer oil return port of the thermal insulation heater (10).

[0015] Preferably, the gas-liquid separator (2) of the coupled heat exchanger comprises a shell (2-1); a low-temperature heat transfer oil inlet (2-2) is provided at a lower portion of one side of the shell (2-1); a high-temperature heat transfer oil outlet (2-3) is provided at an upper portion of the other side of the shell (2-1); a spiral heat transfer oil spiral pipe (2-4) is installed in communication with the inside of the shell (2-1) and between the low-temperature heat transfer oil inlet (2-2) and the high-temperature heat transfer oil outlet (2-3);

[0016] A high-temperature gas-liquid mixture inlet (2-5) is arranged at the upper part of one side of the shell (2-1); an alkali liquid outlet (2-6) is arranged at the bottom of the shell (2-1); and a high-temperature gas outlet (2-7) is arranged at the top of the shell (2-1).

[0017] Preferably, elliptical micro-fins (2-8) are fixedly mounted on the upper and lower surfaces of the thermal oil spiral tube (2-4).

[0018] The present invention also provides a hydrogen production method of the alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system, comprising the following steps:

[0019] Step S1, dark fermentation hydrogen production process:

[0020] The biomass substrate supply device (8) supplies the biomass substrate to the dark fermentation hydrogen production reactor (9); the dark fermentation hydrogen production reactor (9) contains anaerobic fermentation hydrogen-producing bacteria; the anaerobic fermentation hydrogen-producing bacteria decompose the biomass substrate to produce hydrogen under anaerobic conditions without light;

[0021] In the process of hydrogen production by anaerobic fermentation hydrogen-producing bacteria, on the one hand, since volatile acid is produced while the anaerobic fermentation hydrogen-producing bacteria produce hydrogen, the pH value of the reactor is reduced and the hydrogen production effect is inhibited. Therefore, alkali liquid is transported to the dark fermentation hydrogen production reactor (9) through the alkali liquid water tank (7) to adjust the pH value to the optimal working pH value; on the other hand, a heat preservation heater (10) is installed at the lower part of the dark fermentation hydrogen production reactor (9); the flow rate of the heat transfer oil heated after passing through the gas-liquid separator (2) of the coupling heat exchanger is controlled by the flow regulating valve (12), and the heated heat transfer oil is transported to the heat preservation heater (10); usually, the heat preservation heater (10) adjusts the working temperature of the anaerobic fermentation hydrogen production process to keep it at the optimal working temperature for hydrogen production;

[0022] The hydrogen produced by the dark fermentation hydrogen production reactor (9) is transported to the hydrogen drying and purification device (5) through a pipeline;

[0023] After the heat transfer oil flows through the heat preservation heater (10), the temperature is reduced and the heat transfer oil flows out from the heat transfer oil outlet of the heat preservation heater (10), and under the action of the heat transfer oil circulation pump (11), flows into the primary heat exchanger (3) for primary preheating; then flows into the gas-liquid separator (2) of the coupled heat exchanger for further temperature increase; the heated heat transfer oil is transported to the heat preservation heater (10) under the control of the flow regulating valve (12) to adjust the working temperature of the hydrogen production process of the anaerobic fermentation hydrogen-producing bacteria in the dark fermentation hydrogen production reactor (9); this cycle is continuously repeated to form a heat transfer oil circulation loop;

[0024] Step S2, alkaline water electrolysis hydrogen production process:

[0025] Step S2.1, the alkaline electrolyte in the alkaline electrolytic cell (1) is decomposed into hydrogen and oxygen at an operating temperature of 80 to 90° C., thereby generating a first high-temperature gas-liquid mixture formed by hydrogen and alkaline solution, and a second high-temperature gas-liquid mixture formed by oxygen and alkaline solution;

[0026] Step S2.2, the first high-temperature gas-liquid mixture is transported to the gas-liquid separator (2A) of the first coupled heat exchanger; heat exchange is performed with the heat transfer oil input into the gas-liquid separator (2A) of the first coupled heat exchanger, the first high-temperature gas-liquid mixture is cooled down by the heat transfer oil, and hydrogen and alkali liquid are separated under the action of the gas-liquid separator (2A) of the first coupled heat exchanger; the separated alkali liquid flows back to the alkaline electrolytic cell (1) through the alkali liquid reflux pump (6), so as to realize the recycling of the alkali liquid; the separated high-temperature hydrogen is input into the primary heat exchanger (3), heat exchange is performed with the heat transfer oil flowing into the primary heat exchanger (3), the high-temperature hydrogen is cooled down, and then transported to the hydrogen drying and purification device (5); thereby realizing the heat energy recovery and utilization of the first high-temperature gas-liquid mixture and the separated high-temperature hydrogen;

[0027] The second high-temperature gas-liquid mixture is transported to the gas-liquid separator (2B) of the second coupled heat exchanger; heat is exchanged with the heat transfer oil input into the gas-liquid separator (2B) of the second coupled heat exchanger, the second high-temperature gas-liquid mixture is cooled down by the heat transfer oil, and oxygen and alkali liquid are separated by the gas-liquid separator (2B) of the second coupled heat exchanger; the separated alkali liquid flows back to the alkaline electrolytic cell (1) through the alkali liquid reflux pump (6), so as to realize the recycling of the alkali liquid; the separated high-temperature oxygen is input into the primary heat exchanger (3), heat is exchanged with the heat transfer oil flowing into the primary heat exchanger (3), the high-temperature oxygen is cooled down, and then transported to the oxygen drying and purification device (4); thereby realizing the heat energy recovery and utilization of the second high-temperature gas-liquid mixture and the separated high-temperature oxygen;

[0028] Meanwhile, during the hydrogen production process of the alkaline electrolytic cell (1), water in the alkaline solution will be converted into hydrogen and oxygen, and there will be a partial loss of alkaline substances. Therefore, the alkaline solution is replenished into the alkaline electrolytic cell (1) through the alkaline solution water tank (7) under the action of the alkaline solution reflux pump (6).

[0029] Preferably, the gas-liquid separator (2A) of the first coupled heat exchanger and the gas-liquid separator (2B) of the second coupled heat exchanger have the same structure and principle for gas-liquid separation, which is summarized by the gas-liquid separator (2) of the coupled heat exchanger:

[0030] ① The heat transfer oil preheated by the primary heat exchanger (3) flows into the heat transfer oil spiral tube (2-4) from the low-temperature heat transfer oil inlet (2-2) at the bottom of the gas-liquid separator (2) coupled to the heat exchanger, and flows upward in a spiral along the inner passage of the heat transfer oil spiral tube (2-4);

[0031] ② The high-temperature gas-liquid mixture output from the alkaline electrolytic cell (1) flows into the inner cavity of the shell (2-1) from the high-temperature gas-liquid mixture inlet (2-5) at the upper part of the gas-liquid separator (2) coupled to the heat exchanger, and flows from top to bottom in the inner cavity of the shell (2-1);

[0032] Since the inner cavity of the shell (2-1) is provided with a heat transfer oil spiral tube (2-4), and the upper and lower surfaces of the heat transfer oil spiral tube (2-4) are fixedly installed with elliptical micro-fins (2-8), when the high-temperature gas-liquid mixture flows from top to bottom in the inner cavity of the shell (2-1), it exchanges heat with the low-temperature heat transfer oil flowing in the heat transfer oil spiral tube (2-4), and the heat of the high-temperature gas-liquid mixture is absorbed by the heat transfer oil, thereby improving the gas-liquid separation efficiency of the high-temperature gas-liquid mixture; at the same time, under the action of the elliptical micro-fins (2-8), small liquid droplets in the high-temperature gas-liquid mixture are separated from the gas-liquid mixture due to impact; therefore, from the two perspectives of temperature and impact, the gas-liquid separation efficiency of the high-temperature gas-liquid mixture is improved;

[0033] ③ After the high-temperature gas-liquid mixture is separated into gas and liquid, the separated hydrogen or oxygen flows into the primary heat exchanger (3); the separated alkaline liquid flows back to the alkaline electrolytic cell (1); the heat transfer oil after being heated is transported to the insulation heater (10) under the control of the flow regulating valve (12).

[0034] Preferably, the hydrogen produced by the alkaline electrolyzer (1) is transported to the hydrogen drying and purification device (5) after passing through the gas-liquid separator (2) and the primary heat exchanger (3) of the coupled heat exchanger; the hydrogen produced by the dark fermentation hydrogen production reactor (9) is also transported to the hydrogen drying and purification device (5) at the same time; since the hydrogen production rate of the alkaline electrolyzer (1) is easily affected by the volatility of wind and solar power sources, the stability of the hydrogen output by the hydrogen drying and purification device (5) is enhanced by coupling with the hydrogen produced by the dark fermentation hydrogen production reactor (9).

[0035] The alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system and method provided by the present invention has the following advantages:

[0036] The present invention provides an alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system and method, which couples the two hydrogen production systems to improve the utilization efficiency of waste heat and hydrogen production auxiliary systems, improve the overall hydrogen production capacity and hydrogen production stability of the system, and achieve energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the overall structure of an alkaline electrolyzer coupled with biomass dark fermentation combined hydrogen production energy-saving system provided by the present invention;

[0038] Figure 2 A cross-sectional view of a gas-liquid separator coupled to a heat exchanger provided by the present invention. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] See also Figure 1 The present invention provides an alkaline electrolyzer coupled with biomass dark fermentation combined hydrogen production energy-saving system, comprising an alkaline electrolyzer 1, a gas-liquid separator 2 coupled with a heat exchanger, a primary heat exchanger 3, an oxygen drying and purification device 4, a hydrogen drying and purification device 5, an alkali liquid reflux pump 6, a biomass substrate supply device 8, a dark fermentation hydrogen production reactor 9, a heat preservation heater 10 and a heat transfer oil circulation pump 11; wherein, two gas-liquid separators 2 coupled with a heat exchanger are provided, namely: a first gas-liquid separator 2A coupled with a heat exchanger and a second gas-liquid separator 2B coupled with a heat exchanger;

[0041] The biomass substrate supply port of the dark fermentation hydrogen production reactor 9 is connected to the biomass substrate supply device 8; a heat preservation heater 10 is installed at the bottom of the dark fermentation hydrogen production reactor 9; heat transfer oil flows in the heat preservation heater 10; the heat transfer oil outlet of the heat preservation heater 10 is connected to the cold medium inlet of the primary heat exchanger 3 through the heat transfer oil circulation pump 11; after being heated by the primary heat exchanger 3, the heat transfer oil output from the cold medium outlet of the primary heat exchanger 3 is respectively connected to the gas-liquid separator 2A of the first coupled heat exchanger and the second coupled heat exchanger The lower heat transfer oil inlet of the gas-liquid separator 2B of the first coupled heat exchanger; the upper heat transfer oil outlets of the gas-liquid separator 2A of the first coupled heat exchanger and the gas-liquid separator 2B of the second coupled heat exchanger are connected to the heat transfer oil return port of the thermal insulation heater 10 through a pipeline to complete the heat transfer oil circulation loop; wherein, a flow regulating valve 12 is installed in the pipeline between the upper heat transfer oil outlets of the gas-liquid separator 2A of the first coupled heat exchanger and the gas-liquid separator 2B of the second coupled heat exchanger to the heat transfer oil return port of the thermal insulation heater 10.

[0042] The alkaline electrolyzer 1 has a first high-temperature gas-liquid mixture outlet and a second high-temperature gas-liquid mixture outlet; the first high-temperature gas-liquid mixture outlet is used to output a first high-temperature gas-liquid mixture formed by hydrogen and alkali liquid; the second high-temperature gas-liquid mixture outlet is used to output a second high-temperature gas-liquid mixture formed by oxygen and alkali liquid; the first high-temperature gas-liquid mixture outlet is connected to a first high-temperature gas-liquid mixture inlet of a gas-liquid separator 2A of a first coupled heat exchanger; the second high-temperature gas-liquid mixture outlet is connected to a second high-temperature gas-liquid mixture inlet of a gas-liquid separator 2B of a second coupled heat exchanger;

[0043] The gas-liquid separator 2A of the first coupled heat exchanger performs gas-liquid separation on the first high-temperature gas-liquid mixture under the action of heat absorption and cooling of the heat-conducting oil, and the top is a high-temperature hydrogen outlet, and the bottom is a first alkali liquid outlet; the gas-liquid separator 2B of the second coupled heat exchanger performs gas-liquid separation on the second high-temperature gas-liquid mixture under the action of heat absorption and cooling of the heat-conducting oil, and the top is a high-temperature oxygen outlet, and the bottom is a second alkali liquid outlet;

[0044] The first alkali solution outlet and the second alkali solution outlet are both connected to the alkali solution inlet of the alkali solution reflux pump 6; the alkali solution outlet of the alkali solution reflux pump 6 is connected to the inside of the alkaline electrolytic cell 1 to form an alkali solution circulation loop;

[0045] The high-temperature hydrogen outlet of the gas-liquid separator 2A of the first coupled heat exchanger is connected to the hydrogen heat source inlet of the primary heat exchanger 3, and after heat exchange with the heat transfer oil flowing through, it flows out from the hydrogen heat source outlet of the primary heat exchanger 3 and flows into the inlet of the hydrogen drying and purification device 5, completing the thermal energy utilization of the high-temperature hydrogen;

[0046] The high-temperature oxygen outlet of the gas-liquid separator 2B of the second coupled heat exchanger is connected to the oxygen heat source inlet of the primary heat exchanger 3. After heat exchange with the heat transfer oil flowing through it, it flows out from the oxygen heat source outlet of the primary heat exchanger 3 and flows into the inlet of the oxygen drying and purification device 4, completing the thermal energy utilization of the high-temperature oxygen.

[0047] It also includes: an alkali liquid water tank 7; the alkali liquid water tank 7 is connected to the alkali liquid inlet of the alkali liquid reflux pump 6 and the reaction chamber of the dark fermentation hydrogen production reactor 9 respectively.

[0048] The present invention also improves the structure of the gas-liquid separator 2 coupled to the heat exchanger, thereby effectively improving the gas-liquid separation efficiency:

[0049] like Figure 2 As shown, the gas-liquid separator 2 of the coupled heat exchanger includes a shell 2-1; a low-temperature heat transfer oil inlet 2-2 is arranged at the lower part of one side of the shell 2-1; a high-temperature heat transfer oil outlet 2-3 is arranged at the upper part of the other side of the shell 2-1; a spiral heat transfer oil spiral pipe 2-4 is installed in the interior of the shell 2-1 and between the low-temperature heat transfer oil inlet 2-2 and the high-temperature heat transfer oil outlet 2-3; and elliptical micro-fins 2-8 are fixedly installed on the upper and lower surfaces of the heat transfer oil spiral pipe 2-4.

[0050] A high-temperature gas-liquid mixture inlet 2-5 is arranged at the upper part of one side of the shell 2-1; an alkali liquid outlet 2-6 is arranged at the bottom of the shell 2-1; and a high-temperature gas outlet 2-7 is arranged at the top of the shell 2-1.

[0051] The present invention also provides a hydrogen production method of an alkaline electrolyzer coupled with a biomass dark fermentation combined hydrogen production energy-saving system, comprising the following steps:

[0052] Step S1, dark fermentation hydrogen production process:

[0053] The biomass substrate supply device 8 supplies the biomass substrate to the dark fermentation hydrogen production reactor 9; the dark fermentation hydrogen production reactor 9 contains anaerobic fermentation hydrogen-producing bacteria; the anaerobic fermentation hydrogen-producing bacteria decompose the biomass substrate to produce hydrogen under anaerobic conditions without light;

[0054] In the process of hydrogen production by anaerobic fermentation hydrogen-producing bacteria, on the one hand, since volatile acids are produced while the anaerobic fermentation hydrogen-producing bacteria produce hydrogen, the pH value of the reactor is reduced and the hydrogen production effect is inhibited. Therefore, alkali liquid is transported to the dark fermentation hydrogen production reactor 9 through the alkali liquid water tank 7 to adjust the pH value to the optimal working pH value; on the other hand, a heat preservation heater 10 is installed at the lower part of the dark fermentation hydrogen production reactor 9; the flow rate of the heat transfer oil heated after passing through the gas-liquid separator 2 of the coupling heat exchanger is controlled by the flow regulating valve 12, and the heated heat transfer oil is transported to the heat preservation heater 10; usually, the heat preservation heater 10 adjusts the working temperature of the anaerobic fermentation hydrogen-producing bacteria hydrogen production process to keep it at the optimal working temperature for hydrogen production;

[0055] The hydrogen produced by the dark fermentation hydrogen production reactor 9 is transported to the hydrogen drying and purification device 5 through a pipeline;

[0056] After the heat transfer oil flows through the heat preservation heater 10, the temperature is reduced, and it flows out from the heat transfer oil outlet of the heat preservation heater 10, and under the action of the heat transfer oil circulation pump 11, it flows into the primary heat exchanger 3 for primary preheating; then it flows into the gas-liquid separator 2 of the coupled heat exchanger for further temperature increase; the heated heat transfer oil is transported to the heat preservation heater 10 under the control of the flow regulating valve 12 to adjust the working temperature of the hydrogen production process of the anaerobic fermentation hydrogen-producing bacteria in the dark fermentation hydrogen production reactor 9; this cycle is continuously repeated to form a heat transfer oil circulation loop;

[0057] Step S2, alkaline water electrolysis hydrogen production process:

[0058] Step S2.1, the alkaline electrolyte in the alkaline electrolytic cell 1 is decomposed into hydrogen and oxygen at an operating temperature of 80-90° C., thereby generating a first high-temperature gas-liquid mixture formed by hydrogen and alkaline solution, and a second high-temperature gas-liquid mixture formed by oxygen and alkaline solution;

[0059] Step S2.2, the first high-temperature gas-liquid mixture is transported to the gas-liquid separator 2A of the first coupled heat exchanger; heat exchange is performed with the heat transfer oil input into the gas-liquid separator 2A of the first coupled heat exchanger, the first high-temperature gas-liquid mixture is cooled down by the heat transfer oil, and hydrogen and alkali liquid are separated under the action of the gas-liquid separator 2A of the first coupled heat exchanger; the separated alkali liquid flows back to the alkaline electrolytic cell 1 through the alkali liquid reflux pump 6 to realize the recycling of the alkali liquid; the separated high-temperature hydrogen is input into the primary heat exchanger 3, heat exchange is performed with the heat transfer oil flowing into the primary heat exchanger 3, the high-temperature hydrogen is cooled down, and then transported to the hydrogen drying and purification device 5; thereby realizing the heat energy recovery and utilization of the first high-temperature gas-liquid mixture and the separated high-temperature hydrogen;

[0060] The second high-temperature gas-liquid mixture is transported to the gas-liquid separator 2B of the second coupled heat exchanger; heat is exchanged with the heat transfer oil input into the gas-liquid separator 2B of the second coupled heat exchanger, the second high-temperature gas-liquid mixture is cooled down by the heat transfer oil, and oxygen and alkali liquid are separated under the action of the gas-liquid separator 2B of the second coupled heat exchanger; the separated alkali liquid flows back to the alkaline electrolytic cell 1 through the alkali liquid reflux pump 6 to realize the recycling of the alkali liquid; the separated high-temperature oxygen is input into the primary heat exchanger 3, heat is exchanged with the heat transfer oil flowing into the primary heat exchanger 3, the high-temperature oxygen is cooled down, and then transported to the oxygen drying and purification device 4; thereby, the heat energy recovery and utilization of the second high-temperature gas-liquid mixture and the separated high-temperature oxygen are realized;

[0061] Meanwhile, during the hydrogen production process of the alkaline electrolytic cell 1 , water in the alkaline solution will be converted into hydrogen and oxygen, and there will be some loss of alkaline substances. Therefore, the alkaline solution is replenished into the alkaline electrolytic cell 1 through the alkaline solution water tank 7 under the action of the alkaline solution reflux pump 6 .

[0062] In the present invention, the gas-liquid separator 2A of the first coupled heat exchanger and the gas-liquid separator 2B of the second coupled heat exchanger have the same structure and principle for gas-liquid separation, see Figure 2 , which is summarized by the gas-liquid separator 2 coupled to the heat exchanger:

[0063] ① The heat transfer oil preheated by the primary heat exchanger 3 flows into the heat transfer oil spiral tube 2-4 from the low-temperature heat transfer oil inlet 2-2 at the lower part of the gas-liquid separator 2 coupled to the heat exchanger, and flows upward in a spiral along the inner passage of the heat transfer oil spiral tube 2-4;

[0064] ② The high-temperature gas-liquid mixture output from the alkaline electrolytic cell 1 flows into the inner cavity of the shell 2-1 from the high-temperature gas-liquid mixture inlet 2-5 at the upper part of the gas-liquid separator 2 coupled with the heat exchanger, and flows from top to bottom in the inner cavity of the shell 2-1;

[0065] Since the inner cavity of the shell 2-1 is provided with a heat transfer oil spiral tube 2-4, and the upper and lower surfaces of the heat transfer oil spiral tube 2-4 are fixedly installed with elliptical micro-fins 2-8, therefore, when the high-temperature gas-liquid mixture flows from top to bottom in the inner cavity of the shell 2-1, it exchanges heat with the low-temperature heat transfer oil flowing in the heat transfer oil spiral tube 2-4, and the heat of the high-temperature gas-liquid mixture is absorbed by the heat transfer oil, thereby improving the gas-liquid separation efficiency of the high-temperature gas-liquid mixture; at the same time, under the action of the elliptical micro-fins 2-8, small droplets in the high-temperature gas-liquid mixture are separated from the gas-liquid mixture due to impact; therefore, from the two perspectives of temperature and impact, the gas-liquid separation efficiency of the high-temperature gas-liquid mixture is improved;

[0066] ③ After the high-temperature gas-liquid mixture is separated into gas and liquid, the separated hydrogen or oxygen flows into the primary heat exchanger 3; the separated alkali liquid flows back to the alkaline electrolytic cell 1; the heat transfer oil after heating is transported to the insulation heater 10 under the control of the flow regulating valve 12.

[0067] The gas-liquid separator 2 coupled to the heat exchanger provided by the present invention has the following design features:

[0068] (1) Designing the heat transfer oil spiral pipe 2-4, specifically, designing a spiral flow channel, and designing the wall of the spiral flow channel to be a hollow structure, so that the heat transfer oil can flow from bottom to top against the high-temperature gas-liquid mixture and absorb heat along the way through the wall;

[0069] (2) Elliptical micro-fins are designed on the upper and lower surfaces of the spiral flow channel of the heat transfer flow to enhance the heat transfer effect between the gas-liquid mixture and the flow channel wall;

[0070] (3) The high-temperature gas-liquid mixture absorbs heat through the heat transfer oil, and the temperature of the high-temperature gas-liquid mixture can be effectively reduced, which is conducive to gas-liquid separation; combined with the setting of elliptical micro-fins on the flow channel wall, small droplets in the gas-liquid mixture will be separated from the mixture due to impact, which is conducive to the gas-liquid separation efficiency from both the temperature and impact perspectives; at the same time, the heat transfer oil after absorbing heat is used for anaerobic fermentation of hydrogen-producing bacteria to produce hydrogen, thereby realizing heat recovery and utilization of the high-temperature gas-liquid mixture.

[0071] Therefore, by coupling the gas-liquid separator of the heat exchanger, the two goals of high-purity hydrogen production and efficient heat utilization are achieved.

[0072] As a specific implementation example, combined with Figure 1 The present invention also provides a hydrogen production method of an alkaline electrolyzer coupled with a biomass dark fermentation combined hydrogen production energy-saving system, comprising the following steps:

[0073] 1. During the operation of the alkaline electrolyzer 1, a high-temperature gas-liquid mixture of hydrogen and alkali liquid and a high-temperature gas-liquid mixture of oxygen and alkali liquid are generated. The two gas-liquid mixtures are respectively transported to the gas-liquid separator 2A of the first coupled heat exchanger and the gas-liquid separator 2B of the second coupled heat exchanger through pipelines;

[0074] 2. The two high-temperature gas-liquid mixtures are cooled in the gas-liquid separators of the corresponding coupled heat exchangers, and the gas-liquid separation is performed while releasing part of the heat to obtain gas (hydrogen or oxygen) and alkali solution with a still high temperature. The alkali solution is returned to the alkaline electrolytic cell 1 through the alkali solution reflux pump 6, and the hydrogen and oxygen enter the primary heat exchanger 3 to be cooled again;

[0075] 3. Because the water in the alkali solution will be converted into hydrogen and oxygen during the operation of the alkaline electrolytic cell 1, and there will be some loss of alkaline substances, the alkali solution tank 7 will replenish the alkaline electrolytic cell 1 with alkali solution through the pipeline;

[0076] 4. The heat transfer oil medium first absorbs a small amount of heat released by high-temperature hydrogen and oxygen in the primary heat exchanger 3, realizing further recycling of the heat of hydrogen and oxygen; then, it absorbs more heat in the gas-liquid separator 2 coupled to the heat exchanger, realizing recycling of the heat of the high-temperature gas-liquid mixture; finally, under the control of the flow regulating valve 12, it enters the heat preservation heater 10 at the bottom of the dark fermentation hydrogen production reactor 9 to release heat. The flow regulating valve 12 can control the flow of the heat transfer oil medium to ensure that the temperature of the dark fermentation hydrogen production reactor 9 is within a suitable range.

[0077] 5. The dark fermentation reactor 9 can be kept at an optimal working temperature under the action of the heat preservation heater 10, and the byproduct acid in the reactor can be neutralized by the alkali solution supplied by the alkali solution water tank 7 to maintain an optimal working pH value.

[0078] 6. Under the condition of sufficient biomass substrate supply, the anaerobic fermentation hydrogen-producing bacteria inside the dark fermentation reactor 9 can decompose the substrate to produce hydrogen. The hydrogen is sent to the hydrogen drying and purification device 5 through a pipeline.

[0079] 7. The hydrogen cooled in the primary heat exchanger 3 and the hydrogen coming out of the dark fermentation reactor 9 are purified together in the hydrogen drying and purification device 5 to obtain a hydrogen product.

[0080] In the present invention, the hydrogen prepared by the alkaline electrolyzer 1 is transported to the hydrogen drying and purification device 5 after passing through the gas-liquid separator 2 and the primary heat exchanger 3 of the coupling heat exchanger; the hydrogen prepared by the dark fermentation hydrogen production reactor 9 is also transported to the hydrogen drying and purification device 5 at the same time; since the hydrogen production rate of the alkaline electrolyzer 1 is easily affected by the volatility of wind and solar power sources, the stability of the hydrogen output by the hydrogen drying and purification device 5 is enhanced by coupling with the hydrogen prepared by the dark fermentation hydrogen production reactor 9.

[0081] The present invention provides an alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system and method, which couples the two hydrogen production systems to improve the utilization efficiency of waste heat and hydrogen production auxiliary systems, improve the overall hydrogen production capacity and hydrogen production stability of the system, and achieve energy saving and consumption reduction.

[0082] The specific improvement measures and effects are divided into four points:

[0083] (1) By adding a waste heat utilization loop, the waste heat in the alkaline water electrolysis hydrogen production system is effectively absorbed, and this part of the heat is supplied to the dark fermentation hydrogen production reactor 9 through a heating and insulation circulation loop to achieve heating and insulation functions;

[0084] Specifically, the waste heat utilization loop includes a gas-liquid separator 2 and a primary heat exchanger 3 coupled to a heat exchanger. The waste heat utilization loop is added to recycle the waste heat generated by the alkaline water electrolysis hydrogen production system, specifically recovering the heat in the high-temperature gas-liquid mixture and the separated high-temperature hydrogen (oxygen). This part of the heat is used to heat the dark fermentation hydrogen production reactor 9 through the heat preservation medium, and the dark fermentation hydrogen production reactor 9 can be maintained in the optimal operating temperature range. This improvement avoids the loss of waste heat and improves the dark fermentation hydrogen production efficiency.

[0085] (2) The coupled dark fermentation hydrogen production reactor 9 and the alkaline electrolyzer 1 share a set of auxiliary systems such as an alkali solution supply system and a hydrogen drying, purification and collection system, thereby improving the utilization rate of the auxiliary system and reducing the unit cost of hydrogen production;

[0086] (3) The hydrogen production rate of the alkaline electrolyzer is easily affected by the volatility of wind and solar power, while the hydrogen production rate of the dark fermentation biomass hydrogen production reactor is relatively stable. The coupling of the two can enhance the hydrogen production stability of the combined hydrogen production system and improve the utilization rate of various auxiliary systems;

[0087] Specifically, the stable hydrogen production characteristics of the dark fermentation biological hydrogen production system are utilized to reduce the impact of the volatility of hydrogen production in the alkaline electrolyzer on the overall hydrogen production effect, thereby achieving a continuous and stable supply of hydrogen.

[0088] (4) A new type of gas-liquid separator coupled with a heat exchanger was proposed. In particular, the design of the hollow spiral flow channel and the elliptical micro-fins can enable the heat transfer oil to fully absorb the heat released by the high-temperature gas-liquid mixture during the gas-liquid separation process. The gas-liquid separation efficiency is improved by cooling the gas-liquid separation process and enhancing the impact between the gas-liquid mixture and the fins, thereby improving the energy efficiency of the entire system.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. An alkaline electrolyzer coupled with biomass dark fermentation combined hydrogen production energy-saving system, characterized in that: The invention comprises an alkaline electrolytic cell (1), a gas-liquid separator (2) coupled with a heat exchanger, a primary heat exchanger (3), an oxygen drying and purification device (4), a hydrogen drying and purification device (5), an alkali liquid reflux pump (6), a biomass substrate supply device (8), a dark fermentation hydrogen production reactor (9), a heat preservation heater (10) and a heat transfer oil circulation pump (11); wherein two gas-liquid separators (2) coupled with a heat exchanger are provided, namely: a gas-liquid separator (2A) of a first coupled heat exchanger and a gas-liquid separator (2B) of a second coupled heat exchanger; The biomass substrate supply port of the dark fermentation hydrogen production reactor (9) is connected to the biomass substrate supply device (8); the heat preservation heater (10) is installed at the bottom of the dark fermentation hydrogen production reactor (9); heat transfer oil flows in the heat preservation heater (10); the heat transfer oil outlet of the heat preservation heater (10) is connected to the cold medium inlet of the primary heat exchanger (3) through the heat transfer oil circulation pump (11); after being heated by the primary heat exchanger (3), the heat transfer oil output from the cold medium outlet of the primary heat exchanger (3) is respectively connected to the lower heat transfer oil inlets of the gas-liquid separator (2A) of the first coupled heat exchanger and the gas-liquid separator (2B) of the second coupled heat exchanger; the upper heat transfer oil outlets of the gas-liquid separator (2A) of the first coupled heat exchanger and the gas-liquid separator (2B) of the second coupled heat exchanger are connected to the heat transfer oil reflux port of the heat preservation heater (10) through pipelines, completing the heat transfer oil circulation loop; The alkaline electrolyzer (1) has a first high-temperature gas-liquid mixture outlet and a second high-temperature gas-liquid mixture outlet; the first high-temperature gas-liquid mixture outlet is used to output a first high-temperature gas-liquid mixture formed by hydrogen and alkaline liquid; the second high-temperature gas-liquid mixture outlet is used to output a second high-temperature gas-liquid mixture formed by oxygen and alkaline liquid; the first high-temperature gas-liquid mixture outlet is connected to a first high-temperature gas-liquid mixture inlet of a gas-liquid separator (2A) of the first coupled heat exchanger; the second high-temperature gas-liquid mixture outlet is connected to a second high-temperature gas-liquid mixture inlet of a gas-liquid separator (2B) of the second coupled heat exchanger; The gas-liquid separator (2A) of the first coupled heat exchanger performs gas-liquid separation on the first high-temperature gas-liquid mixture under the action of the heat transfer oil absorbing heat and cooling, and the top is a high-temperature hydrogen outlet, and the bottom is a first alkali liquid outlet; the gas-liquid separator (2B) of the second coupled heat exchanger performs gas-liquid separation on the second high-temperature gas-liquid mixture under the action of the heat transfer oil absorbing heat and cooling, and the top is a high-temperature oxygen outlet, and the bottom is a second alkali liquid outlet; The first alkali solution outlet and the second alkali solution outlet are both connected to the alkali solution inlet of the alkali solution reflux pump (6); the alkali solution outlet of the alkali solution reflux pump (6) is connected to the inside of the alkaline electrolytic cell (1), forming an alkali solution circulation loop; The high-temperature hydrogen outlet of the gas-liquid separator (2A) of the first coupled heat exchanger is connected to the hydrogen heat source inlet of the primary heat exchanger (3), and after heat exchange with the heat transfer oil flowing through, the high-temperature hydrogen flows out from the hydrogen heat source outlet of the primary heat exchanger (3) and flows into the inlet of the hydrogen drying and purification device (5), thereby completing the thermal energy utilization of the high-temperature hydrogen; The high-temperature oxygen outlet of the gas-liquid separator (2B) of the second coupled heat exchanger is connected to the oxygen heat source inlet of the primary heat exchanger (3). After heat exchange with the heat transfer oil flowing through, the high-temperature oxygen flows out from the oxygen heat source outlet of the primary heat exchanger (3) and flows into the inlet of the oxygen drying and purification device (4), thereby completing the thermal energy utilization of the high-temperature oxygen.

2. The alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system according to claim 1 is characterized in that: Also includes: Lye water tank (7); The alkali liquid water tank (7) is respectively connected to the alkali liquid inlet of the alkali liquid reflux pump (6) and the reaction chamber of the dark fermentation hydrogen production reactor (9).

3. The alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system according to claim 1 is characterized in that: A flow regulating valve (12) is installed in the pipeline between the upper heat transfer oil outlet of the gas-liquid separator (2A) of the first coupled heat exchanger and the upper heat transfer oil outlet of the gas-liquid separator (2B) of the second coupled heat exchanger and the heat transfer oil return port of the thermal insulation heater (10).

4. The alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system according to claim 1 is characterized in that: The gas-liquid separator (2) of the coupled heat exchanger comprises a shell (2-1); a low-temperature heat transfer oil inlet (2-2) is arranged at the lower part of one side of the shell (2-1); a high-temperature heat transfer oil outlet (2-3) is arranged at the upper part of the other side of the shell (2-1); a spiral heat transfer oil spiral pipe (2-4) is installed in the interior of the shell (2-1) and between the low-temperature heat transfer oil inlet (2-2) and the high-temperature heat transfer oil outlet (2-3); A high-temperature gas-liquid mixture inlet (2-5) is arranged at the upper part of one side of the shell (2-1); an alkali liquid outlet (2-6) is arranged at the bottom of the shell (2-1); and a high-temperature gas outlet (2-7) is arranged at the top of the shell (2-1).

5. The alkaline electrolyzer coupled biomass dark fermentation combined hydrogen production energy-saving system according to claim 4 is characterized in that: Elliptical micro-fins (2-8) are fixedly installed on the upper and lower surfaces of the thermal oil spiral tube (2-4).

6. A hydrogen production method of an alkaline electrolyzer coupled with biomass dark fermentation combined hydrogen production energy-saving system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step S1, dark fermentation hydrogen production process: The biomass substrate supply device (8) supplies the biomass substrate to the dark fermentation hydrogen production reactor (9); the dark fermentation hydrogen production reactor (9) contains anaerobic fermentation hydrogen-producing bacteria; the anaerobic fermentation hydrogen-producing bacteria decompose the biomass substrate to produce hydrogen under anaerobic conditions without light; In the process of hydrogen production by anaerobic fermentation hydrogen-producing bacteria, on the one hand, since volatile acid is produced while the anaerobic fermentation hydrogen-producing bacteria produce hydrogen, the pH value of the reactor is reduced and the hydrogen production effect is inhibited. Therefore, alkali liquid is transported to the dark fermentation hydrogen production reactor (9) through the alkali liquid water tank (7) to adjust the pH value to the optimal working pH value; on the other hand, a heat preservation heater (10) is installed at the lower part of the dark fermentation hydrogen production reactor (9); the flow rate of the heat transfer oil heated after passing through the gas-liquid separator (2) of the coupling heat exchanger is controlled by the flow regulating valve (12), and the heated heat transfer oil is transported to the heat preservation heater (10); usually, the heat preservation heater (10) adjusts the working temperature of the anaerobic fermentation hydrogen production process to keep it at the optimal working temperature for hydrogen production; The hydrogen produced by the dark fermentation hydrogen production reactor (9) is transported to the hydrogen drying and purification device (5) through a pipeline; After the heat transfer oil flows through the heat preservation heater (10), the temperature is reduced and the heat transfer oil flows out from the heat transfer oil outlet of the heat preservation heater (10), and under the action of the heat transfer oil circulation pump (11), flows into the primary heat exchanger (3) for primary preheating; then flows into the gas-liquid separator (2) of the coupled heat exchanger for further temperature increase; the heated heat transfer oil is transported to the heat preservation heater (10) under the control of the flow regulating valve (12) to adjust the working temperature of the hydrogen production process of the anaerobic fermentation hydrogen-producing bacteria in the dark fermentation hydrogen production reactor (9); this cycle is continuously repeated to form a heat transfer oil circulation loop; Step S2, alkaline water electrolysis hydrogen production process: Step S2.1, the alkaline electrolyte in the alkaline electrolytic cell (1) is decomposed into hydrogen and oxygen at an operating temperature of 80 to 90° C., thereby generating a first high-temperature gas-liquid mixture formed by hydrogen and alkaline solution, and a second high-temperature gas-liquid mixture formed by oxygen and alkaline solution; Step S2.2, the first high-temperature gas-liquid mixture is transported to the gas-liquid separator (2A) of the first coupled heat exchanger; heat exchange is performed with the heat transfer oil input into the gas-liquid separator (2A) of the first coupled heat exchanger, the first high-temperature gas-liquid mixture is cooled down by the heat transfer oil, and hydrogen and alkali liquid are separated under the action of the gas-liquid separator (2A) of the first coupled heat exchanger; the separated alkali liquid flows back to the alkaline electrolytic cell (1) through the alkali liquid reflux pump (6), so as to realize the recycling of the alkali liquid; the separated high-temperature hydrogen is input into the primary heat exchanger (3), heat exchange is performed with the heat transfer oil flowing into the primary heat exchanger (3), the high-temperature hydrogen is cooled down, and then transported to the hydrogen drying and purification device (5); thereby realizing the heat energy recovery and utilization of the first high-temperature gas-liquid mixture and the separated high-temperature hydrogen; The second high-temperature gas-liquid mixture is transported to the gas-liquid separator (2B) of the second coupled heat exchanger; heat is exchanged with the heat transfer oil input into the gas-liquid separator (2B) of the second coupled heat exchanger, the second high-temperature gas-liquid mixture is cooled down by the heat transfer oil, and oxygen and alkali liquid are separated by the gas-liquid separator (2B) of the second coupled heat exchanger; the separated alkali liquid flows back to the alkaline electrolytic cell (1) through the alkali liquid reflux pump (6), so as to realize the recycling of the alkali liquid; the separated high-temperature oxygen is input into the primary heat exchanger (3), heat is exchanged with the heat transfer oil flowing into the primary heat exchanger (3), the high-temperature oxygen is cooled down, and then transported to the oxygen drying and purification device (4); thereby realizing the heat energy recovery and utilization of the second high-temperature gas-liquid mixture and the separated high-temperature oxygen; Meanwhile, during the hydrogen production process of the alkaline electrolytic cell (1), water in the alkaline solution will be converted into hydrogen and oxygen, and there will be a partial loss of alkaline substances. Therefore, the alkaline solution is replenished into the alkaline electrolytic cell (1) through the alkaline solution water tank (7) under the action of the alkaline solution reflux pump (6).

7. The hydrogen production method of the alkaline electrolyzer coupled with biomass dark fermentation combined hydrogen production energy-saving system according to claim 6 is characterized in that: The gas-liquid separator (2A) of the first coupled heat exchanger and the gas-liquid separator (2B) of the second coupled heat exchanger have the same structure and principle for gas-liquid separation, and are generally described by the gas-liquid separator (2) of the coupled heat exchanger: ① The heat transfer oil preheated by the primary heat exchanger (3) flows into the heat transfer oil spiral tube (2-4) from the low-temperature heat transfer oil inlet (2-2) at the bottom of the gas-liquid separator (2) coupled to the heat exchanger, and flows upward in a spiral along the inner passage of the heat transfer oil spiral tube (2-4); ② The high-temperature gas-liquid mixture output from the alkaline electrolytic cell (1) flows into the inner cavity of the shell (2-1) from the high-temperature gas-liquid mixture inlet (2-5) at the upper part of the gas-liquid separator (2) coupled to the heat exchanger, and flows from top to bottom in the inner cavity of the shell (2-1); Since the inner cavity of the shell (2-1) is provided with a heat transfer oil spiral tube (2-4), and the upper and lower surfaces of the heat transfer oil spiral tube (2-4) are fixedly installed with elliptical micro-fins (2-8), when the high-temperature gas-liquid mixture flows from top to bottom in the inner cavity of the shell (2-1), it exchanges heat with the low-temperature heat transfer oil flowing in the heat transfer oil spiral tube (2-4), and the heat of the high-temperature gas-liquid mixture is absorbed by the heat transfer oil, thereby improving the gas-liquid separation efficiency of the high-temperature gas-liquid mixture; at the same time, under the action of the elliptical micro-fins (2-8), small liquid droplets in the high-temperature gas-liquid mixture are separated from the gas-liquid mixture due to impact; therefore, from the two perspectives of temperature and impact, the gas-liquid separation efficiency of the high-temperature gas-liquid mixture is improved; ③ After the high-temperature gas-liquid mixture is separated into gas and liquid, the separated hydrogen or oxygen flows into the primary heat exchanger (3); the separated alkaline liquid flows back to the alkaline electrolytic cell (1); the heat transfer oil after being heated is transported to the insulation heater (10) under the control of the flow regulating valve (12).

8. The hydrogen production method of the alkaline electrolyzer coupled with biomass dark fermentation combined hydrogen production energy-saving system according to claim 6 is characterized in that: The hydrogen produced by the alkaline electrolytic cell (1) is transported to the hydrogen drying and purification device (5) after passing through the gas-liquid separator (2) and the primary heat exchanger (3) of the coupled heat exchanger; the hydrogen produced by the dark fermentation hydrogen production reactor (9) is also transported to the hydrogen drying and purification device (5) at the same time; since the hydrogen production rate of the alkaline electrolytic cell (1) is easily affected by the volatility of wind and solar power sources, the hydrogen produced by the dark fermentation hydrogen production reactor (9) is coupled to enhance the stability of the hydrogen output by the hydrogen drying and purification device (5).

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