High-temperature electrolytic hydrogen production method and device for generating steam by using low-temperature heat source

Abstract

The invention discloses a high-temperature electrolytic hydrogen production method and device for generating steam by using a low-temperature heat source. The method comprises the following steps: i) converting low-grade heat energy carried by a low-temperature heat source of below 100 DEG C into heat energy of above 100 DEG C carried by a heat pump working medium through a heat pump system; ii) heating and gasifying liquid water into water vapor by taking the high-grade heat energy as a main heat supply source; and iii) electrolyzing the water vapor to prepare hydrogen. According to the method, the problem that steam cannot be independently generated due to insufficient waste heat in the high-temperature electrolytic hydrogen production system is solved. The device not only can generate steam required by high-temperature electrolytic hydrogen production, but also can efficiently utilize low-grade heat energy such as terrestrial heat and industrial waste heat, and provides a new solution thought for efficient conversion and utilization of low-grade energy such as terrestrial heat and industrial waste heat to high-grade energy such as hydrogen energy. The application scene of the high-temperature electrolytic hydrogen production technology is widened, the development of the high-temperature electrolytic hydrogen production technology is promoted, and the method has the advantages of wide application space, energy conservation and efficiency improvement.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis in solid oxide electrolyzers, and in particular to a method and device for producing hydrogen by high-temperature electrolysis by utilizing a low-temperature heat source to generate steam. Background Art

[0002] Hydrogen energy is an important technical approach to achieving the dual carbon goals. The premise of its widespread application is the large-scale, efficient and green production of hydrogen. Hydrogen production by water electrolysis is currently recognized as the mainstream hydrogen production technology route in the future. There are three main technical routes for hydrogen production by water electrolysis: alkaline electrolysis, proton exchange membrane electrolysis and solid oxide electrolysis. Compared with low-temperature electrolysis technologies such as alkaline electrolysis and proton exchange membrane electrolysis, the operating temperature of solid oxide electrolysis is between 600 and 1000°C, so it is also called high-temperature electrolysis. At high temperatures, water is electrolyzed into hydrogen and oxygen in the form of steam. The electrochemical reaction rate is fast and the polarization loss is small. Therefore, high-temperature electrolysis hydrogen production technology has outstanding efficiency advantages, and the power consumption of hydrogen production is generally less than 4kWh / Nm 3 , which is 20% to 30% more efficient than low-temperature electrolysis technology.

[0003] The normal operation of the high-temperature electrolyzer requires that the water input to the electrolyzer is in a high-temperature steam state. In the natural environment, water generally exists in liquid form, so the supply of steam becomes one of the important issues that need to be solved for high-temperature electrolysis hydrogen production. At the system level, the cooling and cooling process of the high-temperature electrolysis product can provide part of the heat energy for the preheating and evaporation of water. However, existing system-level studies have shown that the cooling and heat release of the electrolysis product alone is not enough to preheat the input material of the high-temperature electrolyzer to the specified temperature. The gap in heat energy is mainly concentrated in the evaporation process of liquid water, which is caused by the huge latent heat of evaporation phase change of water. In response to this problem, the current existing solutions are: first, directly provide steam with qualified temperature from the outside, and transfer the evaporation problem of water to the high-temperature electrolysis system for solution, but it faces the problem of whether the steam supply is convenient at the hydrogen production site; second, use electric heating to evaporate and gasify water, but this solution uses high-grade electricity to generate low-temperature steam of one or two hundred degrees Celsius, and there is a grade mismatch problem in energy utilization, and the energy utilization method is not entirely reasonable. Summary of the invention

[0004] In view of the above problems, the present invention provides a method and device for producing hydrogen by high-temperature electrolysis using a low-temperature heat source to generate steam. The method provides a solution for supplying steam for the high-temperature electrolysis hydrogen production process using a low-temperature heat source through heat pump technology, and at the same time opens up a new way to efficiently utilize low-temperature thermal energy such as geothermal energy and industrial waste heat to convert into hydrogen energy.

[0005] In one aspect of the present invention, there is provided a method for producing hydrogen by high-temperature electrolysis using a low-temperature heat source to generate steam, comprising: i) converting low-grade thermal energy carried by a low-temperature heat source below 100°C into high-grade thermal energy above 100°C carried by a heat pump working fluid through a heat pump system; ii) using the high-grade thermal energy as the main heat source to heat liquid water and gasify it into water vapor; and iii) electrolyzing the water vapor to produce hydrogen.

[0006] As a specific embodiment of the present invention, the low-temperature heat source includes any one of geothermal water, oil field produced water, industrial flue gas, and industrial or domestic wastewater.

[0007] Another aspect of the present invention provides a high-temperature electrolytic hydrogen production device that uses a low-temperature heat source to generate steam, including a water supply unit, a steam generating unit and an electrolytic hydrogen production unit, the water supply unit is used to provide liquid water, the steam generating unit is used to heat the liquid water to produce water vapor and preheat it to the temperature required for electrolysis, and the electrolytic hydrogen production unit is used to electrolyze water vapor to produce hydrogen; the water supply unit is connected to the electrolytic hydrogen production unit through a pipeline, and the steam generating unit is provided on the pipeline; the electrolytic hydrogen production unit includes an electrolyzer, and the electrolyzer includes an electrolysis product outlet; the steam generating unit includes a heat pump system and an auxiliary heating component; the type of the heat pump system is not specifically limited, and can be any one of a compression heat pump, an absorption heat pump, a chemical heat pump or other types of heat pumps; the auxiliary heating component includes an electrolysis product heat exchanger for cooling the electrolysis product of the electrolyzer; the electrolysis product outlet is connected to the inlet of the electrolysis product heat exchanger.

[0008] As a specific embodiment of the present invention, when a compression heat pump is used, the heat pump system includes an evaporator, a compressor, a heat pump condenser and a throttle valve connected in sequence to form a loop, the loop is filled with a heat pump working fluid, and a low-temperature heat source inlet is provided on one side of the evaporator and a low-temperature heat source outlet is provided on the other side. The heat pump system is tightly coupled with the electrolytic hydrogen production unit, and uses low-grade thermal energy in the environment to evaporate and gasify the feed water of the water source supply unit to generate qualified steam for use in the subsequent electrolysis process.

[0009] As a specific embodiment of the present invention, the electrolysis product outlet includes a cathode product outlet and an anode product outlet; the auxiliary heating component includes a cathode product heat exchanger for cooling the cathode product of the electrolytic cell and an anode product heat exchanger for cooling the anode product of the electrolytic cell; the cathode product outlet is connected to the inlet of the cathode product heat exchanger, and the anode product outlet is connected to the inlet of the anode product heat exchanger.

[0010] As a specific embodiment of the present invention, there are multiple cathode product heat exchangers; preferably, the cathode product heat exchanger includes a high-temperature regenerator and a low-temperature regenerator connected in sequence; more preferably, the cathode product heat exchanger includes a high-temperature regenerator, a low-temperature regenerator, and a cooler connected in sequence; and / or, there are multiple anode product heat exchangers; preferably, the anode product heat exchanger includes an air regenerator and an air-steam heat exchanger connected in sequence.

[0011] The functions of the aforementioned various types of heat exchangers, including heat pump condensers, high-temperature regenerators, low-temperature regenerators, coolers, air regenerators and air-steam heat exchangers, are to realize the heat energy exchange between cold and hot materials and fully recover the heat energy carried by high-temperature materials to preheat cold materials.

[0012] As a specific embodiment of the present invention, the water supply unit includes a water inlet pipeline and a water make-up pump; the water inlet pipeline is provided with a water make-up pump, a low-temperature regenerator, a heat pump condenser, an air-steam heat exchanger and a high-temperature regenerator in sequence along the direction from the inlet to the outlet, and the outlet of the water inlet pipeline is connected to the inlet of the electrolytic cell.

[0013] As a specific embodiment of the present invention, the auxiliary heating component also includes a first electric heater, and a make-up water pump, a low-temperature heat exchanger, a heat pump condenser, an air-steam heat exchanger, a high-temperature heat exchanger and a first electric heater are sequentially arranged on the water inlet pipeline along the direction from the inlet to the outlet.

[0014] As a specific embodiment of the present invention, it also includes a post-processing system; preferably, the post-processing system includes a gas-liquid separator; the inlet of the gas-liquid separator is connected to the outlet of the cooler, the gas outlet of the gas-liquid separator is connected to the hydrogen product outlet through a first pipeline, the gas outlet of the gas-liquid separator is connected to the water inlet pipeline between the air-steam heat exchanger and the high-temperature regenerator through a second pipeline, and a hydrogen circulation compressor is provided on the second pipeline; the liquid outlet of the gas-liquid separator is connected to the water inlet pipeline between the water make-up pump and the low-temperature regenerator through a third pipeline, and a circulation pump is provided on the third pipeline.

[0015] As a specific embodiment of the present invention, the electrolytic hydrogen production unit also includes a purge gas equipment assembly, which includes an air intake pipeline and an air compressor; the air intake pipeline is provided with an air compressor and an air heat exchanger in sequence along the direction from the inlet to the outlet, and the outlet of the air intake pipeline is connected to the inlet of the electrolyzer; preferably, it also includes a second electric heater, and the air intake pipeline is provided with an air compressor, an air heat exchanger and a second electric heater in sequence along the direction from the inlet to the outlet, and the outlet of the air intake pipeline is connected to the inlet of the electrolyzer.

[0016] The device provided by the present invention comprises the following steps: (1) the feed water of the water source supply unit and the circulating water that has not been completely electrolyzed enter the heat pump system to absorb heat after absorbing the residual heat of the low temperature section of the electrolysis product; (2) the heat pump system is connected in series in the preheating and heating pipeline of the feed water as the main steam generating device. The heat pump system absorbs low-grade heat energy provided by the outside, such as residual heat between 30 and 100°C, and generates high-temperature heat energy through the drive of electric energy or higher-grade heat energy, heats the feed water of the water source supply unit to evaporate and gasify to generate steam, and feeds it into the subsequent electrolysis process; (3) after the feed water becomes steam, it is further preheated and heated, and enters the electrolytic cell to undergo electrolysis reaction to generate hydrogen and oxygen. After the purge air is preheated and heated, it enters the anode of the electrolytic cell to purge the oxygen generated by electrolysis. The hydrogen and oxygen-enriched air coming out of the electrolytic cell preheat the feed of the electrolytic cell in the heat exchanger of their respective pipelines, and after cooling to a certain temperature with heat release, they are subsequently processed or discharged into the atmosphere.

[0017] The beneficial effects of the present invention are:

[0018] The high-temperature electrolytic hydrogen production method provided by the present invention uses a heat pump system to increase external low-grade thermal energy to high-grade thermal energy above 100°C, and then uses the high-grade thermal energy as the main heat source to heat liquid water and gasify it into water vapor for electrolytic production of hydrogen. This method solves the problem of insufficient internal waste heat in the high-temperature electrolytic hydrogen production system and the inability to independently generate steam. It can not only generate the steam required for high-temperature electrolytic hydrogen production, but also efficiently utilize low-grade thermal energy such as geothermal energy and industrial waste heat, providing a new solution for the efficient conversion and utilization of low-grade energy such as geothermal energy and industrial waste heat into high-grade energy such as hydrogen energy. In addition, it broadens the application scenarios of high-temperature electrolytic hydrogen production technology, promotes the development of high-temperature electrolytic hydrogen production technology, and has the important advantages of broad application space and energy saving and efficiency improvement.

[0019] The high-temperature electrolytic hydrogen production device provided by the present invention particularly introduces a heat pump system and tightly couples it with the electrolytic hydrogen production unit, thereby providing a high-temperature electrolytic hydrogen production device that utilizes a low-temperature heat source and waste heat inside the high-temperature electrolytic hydrogen production system to generate steam. The device has a novel structure and solves the heat gap problem of the electrolytic hydrogen production system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structural principle of the device of the present invention;

[0021] Figure 2 A schematic diagram of the structure of a device according to an embodiment of the present invention;

[0022] Among them: 1-gas-liquid separator; 2-circulation pump; 3-water feed pump; 4-cooler; 5-low-temperature regenerator; 6-heat pump condenser; 7-air-steam heat exchanger; 8-high-temperature regenerator; 9-first electric heater; 10-compressor; 11-evaporator; 12-throttle valve; 13-air regenerator; 14-second electric heater; 15-air compressor; 16-solid oxide electrolyzer; 17-hydrogen circulation compressor; 18-heat exchanger 1; 19-heat exchanger 2. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] To further illustrate the structural principle of the device of the present invention, Figure 1 As shown, the device system of the present invention includes a water supply unit, a steam generation unit and an electrolytic hydrogen production unit, wherein: the water supply unit includes a water inlet pipeline and a water supply pump 3; the steam generation unit includes a compression heat pump (evaporator 11, compressor 10, heat pump condenser 6 and throttle valve 12), a heat exchanger 118; the electrolytic hydrogen production unit includes a solid oxide electrolyzer 16 and a purge gas equipment assembly (air inlet pipeline, air compressor 15, heat exchanger 219). The compression heat pump includes an evaporator 11, a compressor 10, a heat pump condenser 6 and a throttle valve 12 which are connected in sequence to form a loop, the loop is filled with a heat pump working fluid, a low-temperature heat source inlet is provided on one side of the evaporator 11, and a low-temperature heat source outlet is provided on the other side; a make-up water pump 3, a heat pump condenser 6 and a heat exchanger 1 are provided in sequence on the water inlet pipeline, and the outlet of the water inlet pipeline is connected to the steam inlet of the solid oxide electrolyzer 16; an air compressor 15 and a heat exchanger 219 are provided in sequence on the air inlet pipeline, and the outlet of the air inlet pipeline is connected to the purge gas inlet of the solid oxide electrolyzer 16; the cathode product outlet of the solid oxide electrolyzer 16 is connected to the inlet of the heat exchanger 1, and the outlet of the heat exchanger 1 is a hydrogen outlet; the anode product outlet of the solid oxide electrolyzer 16 is connected to the inlet of the heat exchanger 2, and the outlet of the heat exchanger 2 is connected to the external environment.

[0025] During operation, in the evaporator 11 of the heat pump system, the liquid heat pump working fluid absorbs the heat provided by the external low-temperature heat source and turns into a gaseous state, and then enters the compressor 10 to be further compressed into a high-temperature and high-pressure state. Subsequently, the heat pump working fluid enters the heat pump condenser 6 to condense under high pressure to release the latent heat of phase change, and heats the feed water of the water source supply unit and vaporizes it into steam. After cooling and releasing heat, the heat pump working fluid undergoes throttling in the throttle valve 12, and turns back into a low-temperature and low-pressure state, and enters the evaporator 11 again to absorb external low-temperature heat energy. After the steam is preheated by the electrolysis product of the cathode of the solid oxide electrolyzer 16 in the heat exchanger 1, it enters the solid oxide electrolyzer 16 for electrolysis reaction. The electrolysis product of the cathode of the solid oxide electrolyzer 16 cools and releases heat in the heat exchanger 1, releasing the high-temperature heat energy it carries. The electrolysis product after cooling, i.e., hydrogen, is discharged from the electrolytic hydrogen production unit and enters the subsequent process. On the anode side of the solid oxide electrolyzer 16, fresh air in the environment is introduced into the heat exchanger 2 via the air compressor 15, absorbing the high-temperature heat energy carried by the oxygen-enriched air coming out of the solid oxide electrolyzer 16. The preheated fresh air comes out of the heat exchanger 2 and enters the anode of the solid oxide electrolyzer 16 to purge the oxygen produced by electrolysis and become oxygen-enriched air. The oxygen-enriched air discharged from the solid oxide electrolyzer 16 enters the heat exchanger 2 to preheat the fresh air from the air compressor. The oxygen-enriched air cools down and enters the subsequent process.

[0026] A specific embodiment of the device of the present invention is as follows Figure 2As shown, it includes a heat pump system, a water inlet pipeline, an air inlet pipeline and a solid oxide electrolyzer 16, wherein: the heat pump system includes an evaporator 11, a compressor 10, a heat pump condenser 6 and a throttle valve 12 which are connected in sequence to form a loop; the loop is filled with a heat pump working medium, and a low-temperature heat source inlet is provided on one side of the outside of the evaporator 11, and a low-temperature heat source outlet is provided on the other side; a water supply pump 3, a low-temperature regenerator 5, a heat pump condenser 6, an air-steam heat exchanger 7, a high-temperature regenerator 8, and a first electric heater 9 are provided on the water inlet pipeline in sequence, and the outlet of the water inlet pipeline is connected to the steam inlet of the solid oxide electrolyzer 16; an air compressor 15 is provided on the air inlet pipeline in sequence , an air reheater 13, a second electric heater 14, the outlet of the air inlet pipeline is connected to the purge gas inlet of the solid oxide electrolyzer 16; the cathode product outlet of the solid oxide electrolyzer 16 is connected to the inlet of the high-temperature reheater 8, the outlet of the high-temperature reheater 8 is connected to the inlet of the low-temperature reheater 5, the outlet of the low-temperature reheater 5 is connected to the inlet of the cooler 4, the outlet of the cooler 4 is connected to the inlet of the gas-liquid separator 1, the gas outlet of the gas-liquid separator 1 is connected to the hydrogen product outlet and the water inlet pipeline between the air-steam heat exchanger 7 and the high-temperature reheater 8 through two independent pipelines, and a hydrogen circulation compressor 17 is also provided on the latter pipeline. The liquid outlet of the gas-liquid separator 1 is connected to the water inlet pipeline between the water make-up pump 3 and the low-temperature regenerator 5 through a pipeline, and a circulation pump 2 is also provided on the pipeline; the anode product outlet of the bulk oxide electrolyzer 16 is connected to the inlet of the air regenerator 13, the outlet of the air regenerator 13 is connected to the inlet of the air-steam heat exchanger 7, and the outlet of the air-steam heat exchanger 7 is connected to the external environment.

[0027] During operation, in the heat pump system, the external low-temperature heat source, such as geothermal water or oil field produced water, enters the evaporator 11 from the low-temperature heat source inlet to exchange heat with the heat pump working fluid, and its own temperature is reduced and discharged from the heat pump system from the low-temperature heat source outlet. After absorbing the heat of the low-temperature heat source, the heat pump working fluid is compressed into a high-temperature and high-pressure gas in the compressor 10, and then condenses and releases heat in the heat pump condenser 6, transferring the heat to the feed water of the electrolysis system, causing it to evaporate and become steam. The working fluid after cooling and releasing heat is throttled and depressurized in the throttle valve 12, converted into a low-temperature and low-pressure state, and re-enters the evaporator 11 to absorb heat, starting the next round of heat pump cycle.

[0028] After the fresh feed water is pressurized in the make-up water pump 3, it merges with the circulating water in the circulating pump 2, enters the low-temperature regenerator 5 to absorb part of the waste heat of the electrolysis product and then heats up. Then it enters the heat pump condenser 6 of the heat pump system and turns into steam after absorbing heat. The generated steam enters the air-steam heat exchanger 7 to absorb the waste heat of the oxygen-enriched air, mixes with the hydrogen discharged from the hydrogen circulation compressor 17, and then enters the high-temperature regenerator 8 to absorb the waste heat of the high-temperature section of the electrolysis product. The first electric heater 9 serves as a backup to perform necessary heating on the steam when the steam preheating temperature does not meet the requirements of the electrolytic cell (600-1000°C). The steam enters the solid oxide electrolytic cell 16 and is electrolyzed into hydrogen and oxygen.

[0029] In the downstream process of the solid oxide electrolyzer 16, hydrogen and part of the incompletely reacted steam are the outlet materials of the cathode of the solid oxide electrolyzer, and are cooled and released in the high-temperature regenerator 8 and the low-temperature regenerator 5 respectively, and further cooled in the cooler 4, so as to separate the hydrogen and liquid water in the gas-liquid separator 1. The liquid water re-enters the circulation pump 2 as circulating water. Most of the hydrogen obtained at the top of the gas-liquid separator 1 is separated out of the system as a product and further processed, and another small part enters the hydrogen circulation compressor 17 and mixes with the steam entering the solid oxide electrolyzer 16.

[0030] The air in the atmosphere is pressurized by the air compressor 15 as a purge gas, enters the air regenerator 13, absorbs the waste heat of the oxygen-enriched air and then heats up, and enters the standby electric heater 14 to ensure the temperature of the purge air entering the solid oxide electrolyzer 16. After the purge air enters the solid oxide electrolyzer 16, the oxygen generated by electrolysis is purged out of the solid oxide electrolyzer 16, and its own oxygen concentration is increased to become oxygen-enriched air. After the oxygen-enriched air comes out of the solid oxide electrolyzer 16, it preheats the low-temperature feed of the solid oxide electrolyzer 16 in the air regenerator 13 and the air-steam heat exchanger 7 in turn, and then is discharged into the atmosphere.

[0031] The effects of the present invention are quantitatively described below using simulation results of the process simulation software AspenPlus.

[0032] In Aspen Plus Figure 2The system flow shown in the figure is used as an example for simulation. Assume that the DC electrolysis power of the electrolyzer is 1MW, and the electrolyzer operates at a temperature of 750℃, normal pressure, and thermal neutrality. All materials entering the electrolyzer are preheated to 750℃ in the electric heater. The minimum heat exchange temperature difference of the high-temperature regenerator, air regenerator, and air-steam heat exchanger is assumed to be 20℃. The feed water temperature is 20℃; the electrolysis product is cooled to 25℃ and hydrogen and liquid water are separated in the gas-liquid separator. In the mixture of water vapor and hydrogen entering the electrolyzer, the molar fraction of hydrogen is 10%. Adjust the amount of purge air introduced so that the molar fraction of oxygen in the oxygen-enriched air reaches 50%. The water required for electrolytic hydrogen production is preheated to saturated water at the corresponding pressure in the low-temperature regenerator, and then evaporated to saturated steam in the heat pump condenser of the heat pump system, with an evaporation temperature of 108℃. The isentropic efficiency of the hydrogen cycle compressor is assumed to be 0.75, the isentropic efficiency of the air compressor is assumed to be 0.75, and the DC-AC conversion efficiency of the electrolyzer is assumed to be 0.95.

[0033] In terms of the heat pump system, the following simulation assumptions are made. A compression heat pump is used, and the heat pump working fluid is R245fa. The compressor adopts two-stage adiabatic compression, the compressor outlet pressure is 18.5bar, and the compressor isentropic efficiency is 0.8. The throttle valve outlet pressure is 3.44bar. Correspondingly, the condensation and evaporation temperatures of the working fluid are 118℃ and 50℃, respectively. Water with a temperature of 60℃ enters the evaporator as a low-temperature heat source, and is cooled to 55℃ after releasing heat to the heat pump working fluid. To ensure the safe operation of the heat pump unit, the subcooling and superheating of the heat pump condenser and evaporator are assumed to be 5℃. During the simulation, the PENG-ROB physical property method is used globally; for the heat pump system, the REFPROP physical property method is used on the working fluid side, and the STEAMNBS physical property method is used on the water side as a low-temperature heat source.

[0034] The simulation results show that the water evaporation process of the electrolysis system uses 198kW of heat, all of which is provided by the heat pump condenser of the heat pump system, of which 138kW is extracted from the water as a low-temperature heat source and 60kW is provided by the compressor. According to formula (1.1), the coefficient of performance (COP) of the heat pump system is 3.3.

[0035] COP = heat release of heat pump condenser / power consumption of heat pump compressor (1.1)

[0036] The working fluid temperatures on the hot and cold sides of the heat pump condenser are 108°C and 118°C respectively, which means that the heat exchange temperature difference of 10°C is maintained in the steam generator of the electrolysis system. Since both sides have high heat exchange coefficient conditions brought about by phase change, this solution is feasible and can be used to solve the steam supply problem of the high-temperature electrolysis hydrogen production unit. The flow rate of water as a low-temperature heat source is 23.8t / h, and the working fluid flow rate of the heat pump system is 5.7t / h.

[0037] Since the heat from the low-temperature heat source is originally discharged to the environment, it is considered that this heat is free and is not included in the energy consumption of hydrogen production. After taking into account the power consumption of all pumps, compressors, electric heaters, and electrolyzers, the energy consumption of hydrogen production is calculated according to formula (1.2), where E is the energy consumption of hydrogen production, in kWh / Nm 3 ; E 水泵 、E 热泵压缩机 、E 氢气循环压缩机 、E 空压机 、E 电加热器 、E 电解槽 They represent the AC power consumed by the water pump, heat pump compressor, hydrogen circulation compressor, air compressor, all electric heaters, and electrolyzer in the system when a certain amount of H2 is produced, in kWh; V 氢气 Indicates the amount of H2 produced by consuming the above electricity, in Nm 3 (One cubic meter under standard conditions).

[0038]

[0039] The calculation results show that the energy consumption E for hydrogen production is 3.5 kWh / Nm 3 , all of which is electricity consumption, with no additional heat energy consumption. This shows that high-temperature electrolysis to produce hydrogen has an outstanding advantage of low energy consumption.

[0040] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A method for producing hydrogen by high-temperature electrolysis using a low-temperature heat source to generate steam, characterized in that: The method comprises: ⅰ) The heat pump system converts the low-grade heat energy carried by the low-temperature heat source below 100°C into the high-grade heat energy above 100°C carried by the heat pump working fluid; ii) using the high-grade thermal energy as the main heat source to heat liquid water and vaporize it into water vapor; iii) electrolyzing the water vapor to produce hydrogen.

2. The method according to claim 1, characterized in that The low-temperature heat source includes any one of geothermal water, oil field produced water, industrial flue gas, and industrial or domestic wastewater.

3. A high-temperature electrolytic hydrogen production device that uses a low-temperature heat source to generate steam, characterized in that: The device comprises a water supply unit, a steam generating unit and an electrolytic hydrogen production unit, wherein the water supply unit is used to provide liquid water, the steam generating unit is used to heat the liquid water into water vapor and preheat it to a temperature required for electrolysis, and the electrolytic hydrogen production unit is used to electrolyze the water vapor to produce hydrogen; the water supply unit is connected to the electrolytic hydrogen production unit through a pipeline, and the steam generating unit is provided on the pipeline; The electrolytic hydrogen production unit comprises an electrolytic cell, and the electrolytic cell comprises an electrolysis product outlet; The steam generating unit comprises a heat pump system and an auxiliary heating component; the heat pump system is selected from any one of a compression heat pump, an absorption heat pump, and a chemical heat pump; the auxiliary heating component comprises an electrolysis product heat exchanger for cooling the electrolysis product of the electrolysis cell; The electrolysis product outlet is connected to the inlet of the electrolysis product heat exchanger.

4. The device according to claim 3, characterized in that The heat pump system is a compression heat pump, which includes an evaporator, a compressor, a heat pump condenser and a throttle valve connected in sequence to form a loop. The loop is filled with a heat pump working fluid. A low-temperature heat source inlet is provided on one side of the outside of the evaporator, and a low-temperature heat source outlet is provided on the other side.

5. The device according to claim 3, characterized in that The electrolysis product outlet includes a cathode product outlet and an anode product outlet; the auxiliary heating component includes a cathode product heat exchanger for cooling the cathode product of the electrolytic cell and an anode product heat exchanger for cooling the anode product of the electrolytic cell; the cathode product outlet is connected to the inlet of the cathode product heat exchanger, and the anode product outlet is connected to the inlet of the anode product heat exchanger.

6. The device according to claim 5, characterized in that There are multiple cathode product heat exchangers; preferably, the cathode product heat exchanger includes a high-temperature heat regenerator and a low-temperature heat regenerator connected in sequence; more preferably, the cathode product heat exchanger includes a high-temperature heat regenerator, a low-temperature heat regenerator, and a cooler connected in sequence; And / or, there are multiple anode product heat exchangers; preferably, the anode product heat exchanger includes an air regenerator and an air-steam heat exchanger connected in sequence.

7. The device according to claim 6, characterized in that The water supply unit includes a water inlet pipeline and a water replenishment pump; The water inlet pipeline is provided with a water supply pump, a low-temperature regenerator, a heat pump condenser, an air-steam heat exchanger and a high-temperature regenerator in sequence from the inlet to the outlet, and the outlet of the water inlet pipeline is connected to the inlet of the electrolytic cell.

8. The device according to claim 7, characterized in that The auxiliary heating component also includes a first electric heater. A water supply pump, a low-temperature heat exchanger, a heat pump condenser, an air-steam heat exchanger, a high-temperature heat exchanger and a first electric heater are sequentially arranged on the water inlet pipeline along the direction from the inlet to the outlet.

9. The device according to claim 8, characterized in that It also includes a post-processing system; preferably, the post-processing system includes a gas-liquid separator; the inlet of the gas-liquid separator is connected to the outlet of the cooler, the gas outlet of the gas-liquid separator is connected to the hydrogen product outlet through a first pipeline, the gas outlet of the gas-liquid separator is connected to the water inlet pipeline between the air-steam heat exchanger and the high-temperature regenerator through a second pipeline, and a hydrogen circulation compressor is provided on the second pipeline; the liquid outlet of the gas-liquid separator is connected to the water inlet pipeline between the water make-up pump and the low-temperature regenerator through a third pipeline, and a circulation pump is provided on the third pipeline.

10. The device according to any one of claims 6 to 9, characterized in that: The electrolytic hydrogen production unit also includes a purge gas equipment component, which includes an air intake pipeline and an air compressor; the air intake pipeline is provided with an air compressor and an air regenerator in sequence from the inlet to the outlet, and the outlet of the air intake pipeline is connected to the inlet of the electrolyzer; preferably, it also includes a second electric heater, and the air intake pipeline is provided with an air compressor, an air regenerator and a second electric heater in sequence from the inlet to the outlet, and the outlet of the air intake pipeline is connected to the inlet of the electrolyzer.

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