Electrolysis system

Abstract

To suppress unnecessary heat consumption in a system that generates steam to be supplied to an electrolytic cell by heat-exchanging the heat from a heat storage part with a refrigerant and heating a raw water via the refrigerant.SOLUTION: An electrolysis system comprises: an electrolysis cell that generates hydrogen by high-temperature steam electrolysis; a steam generator section that has a refrigerant heat exchange part that heat-exchanges between the heat storage part and the refrigerant, heats raw water via the refrigerant heat-exchanged in the refrigerant heat exchange section to generate steam, and supplies it to the electrolysis cell; a heat storage feed section that has a heat storage part and feeds heat in the heat storage part to the refrigerant heat exchange section; and a control part that controls the heat storage feed section so that the heat input to the refrigerant heat exchange section is smaller during system startup or high-temperature standby than that during a normal operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This specification discloses an electrolysis system. [Background technology]

[0002] Conventionally, as this type of electrolysis system, one that has been proposed is one that includes a solid oxide electrolysis cell (SOEC) that produces hydrogen by high-temperature steam electrolysis while consuming electrical energy, and a heat pump that is composed of an evaporator, a condenser, a compressor, and a throttle valve, and that generates steam by passing low-temperature heat through the evaporator and heating supply water in the condenser, and supplies the steam to the SOEC (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-517233 Summary of the Invention [Problem to be solved by the invention]

[0004] If a heat pump is equipped with a heat storage unit that stores heat (low-temperature heat) to be supplied to it, heat can be supplied stably. However, if heat is wasted, a heat shortage occurs or the heat storage unit needs to be enlarged.

[0005] The electrolysis system disclosed herein performs heat exchange between a heat storage unit and a refrigerant, and generates water vapor by heating raw water via the refrigerant, and a main object of the system is to suppress unnecessary heat consumption. [Means for solving the problem]

[0006] The electrolysis system of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The electrolysis system of the present disclosure comprises: an electrolysis cell for generating hydrogen by high-temperature steam electrolysis; a steam generating unit including a refrigerant heat exchange unit that exchanges heat between the heat storage unit and a refrigerant, and that generates steam by heating raw water through the refrigerant that has undergone heat exchange in the refrigerant heat exchange unit, and supplies the steam to the electrolysis cell; a heat storage supply unit having the heat storage unit and supplying heat from the heat storage unit to the refrigerant heat exchange unit; a control unit that controls the heat storage supply unit so that the amount of heat input to the refrigerant heat exchange unit is reduced during system startup or high-temperature standby compared to during normal operation; The gist of the project is to provide the following:

[0008] The electrolysis system disclosed herein includes a refrigerant heat exchanger that exchanges heat between a heat storage unit and a refrigerant, and generates steam by heating raw water via the refrigerant. During system startup or high-temperature standby, the heat storage supply unit is controlled to reduce the amount of heat input to the refrigerant heat exchanger compared to normal operation. This reduces unnecessary heat consumption in the heat storage unit. As a result, the heat storage unit can be made smaller. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of an electrolysis system according to an embodiment of the present invention. [Figure 2] 10 is a flowchart illustrating an example of a steam heat pump control process. [Figure 3] 10 is an explanatory diagram showing the flow of hot water to a steam heat pump during a system startup mode or a high-temperature standby mode in a comparative example and the present embodiment. FIG. [Figure 4] 10A and 10B are explanatory diagrams showing the control effect of the vapor heat pump during the system startup mode or the high-temperature standby mode in the comparative example and the present embodiment. [Figure 5] 10 is a flowchart showing a steam heat pump control process according to another embodiment. [Figure 6] 10A and 10B are explanatory diagrams showing the control effect of the vapor heat pump during the system startup mode or the high-temperature standby mode in the comparative example and other embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings.

[0011] 1 is a schematic diagram of an electrolysis system 10 of the present embodiment. The electrolysis system 10 of the present embodiment comprises an electrolysis module 20 including an electrolysis cell stack 21 that generates hydrogen by steam electrolysis, a water vapor supply system 30 that generates water vapor using a steam heat pump 40 and supplies the water vapor to the electrolysis module 20, a heat storage supply system 50 that stores waste heat outside the system in a heat storage tank 51 and supplies the stored waste heat to the steam heat pump 40, an air supply system that supplies air as a sweep gas to the electrolysis module 20, a hydrogen recovery system 60 that recovers hydrogen generated in the electrolysis cell stack 21, and a controller 70 that controls the entire system.

[0012] In addition to the electrolysis cell stack 21, the electrolysis module 20 includes a heat exchanger 22, heaters 23 and 24 (for example, sheath heaters), and a combustor 27, all of which are housed in a module case 25 with thermal insulation properties.

[0013] The electrolysis cell stack 21 includes multiple solid oxide unit cells, each including a solid electrolyte, an anode disposed on one side of the solid electrolyte, and an oxidizer electrode disposed on the other side of the solid electrolyte. The electrolysis cell stack 21 receives power from a power source 26 and electrolyzes water vapor supplied to the anode, thereby producing hydrogen at the anode and oxygen at the oxidizer electrode. The power source 26 can be a grid power source, a renewable energy source (e.g., a solar power generation system), or a storage battery. The combustor 27 receives the oxidizer electrode off-gas discharged from the oxidizer electrode of the electrolysis cell stack 21 and hydrogen supplied from the hydrogen supply line 26, and combusts the resulting mixed gas. The temperature of the electrolysis cell stack 21 is increased by the combustion heat and combustion exhaust gas generated by the combustor 27. The combustion exhaust gas discharged from the combustor 27 passes through a heat exchanger 22 and is then discharged to the outside air.

[0014] The electrolysis cell stack 21 operates in a high-temperature environment of, for example, 650-800°C, so the solid electrolyte, fuel electrode, and oxidizer electrode are made of ceramic materials. Furthermore, to decompose water vapor into oxygen ions and hydrogen using a catalyst, the fuel electrode is made of a cermet made of ceramic and a catalytic metal such as nickel. To maintain good catalytic activity of the fuel electrode, it is necessary to keep the fuel electrode in a reducing atmosphere and prevent oxidation of the metal. For this reason, in this embodiment, a small amount of hydrogen is mixed as a reducing gas into the water vapor supplied to the fuel electrode.

[0015] The steam supply system 30 includes a water tank 31 that stores raw water (pure water), a steam heat pump 40 that generates steam from the raw water, a raw water supply line 32 that connects the water tank 31 and the steam heat pump 40, a raw water pump 33 installed on the raw water supply line 32, and a steam supply line 34 that connects the steam heat pump 40 and the electrolysis module 20. The raw water stored in the water tank 31 is supplied to the steam heat pump 40 via the raw water supply line 32 by driving the raw water pump 33, and is converted into steam by the steam heat pump 40, and then supplied to the electrolysis module 20 via the steam supply line 34. The steam supplied to the electrolysis module 20 is then heated to a required temperature by a heater 23, and then supplied to the anode of the electrolysis cell stack 21.

[0016] The raw water supply line 32 is provided with a heat exchange section 36 that heats the raw water flowing through the raw water supply line 32 by heat exchange with hot water stored in a heat storage tank 51, a bypass line 37 that branches off from the raw water supply line 32 and merges with it so as to bypass the heat exchange section 36, and a control valve 38 (three-way valve) that is installed at the branching point of the raw water supply line 32.

[0017] The vapor heat pump 40 exchanges heat (hot water) supplied from the thermal storage supply system 50 with a refrigerant to generate water vapor (saturated steam) from raw water via the refrigerant. The vapor heat pump 40 includes an evaporator 41, a condenser 42, a compressor 43, an expansion valve 44, and a circulation pipe 45 that connects these components so that the refrigerant circulates. The refrigerant circulating in the circulation pipe 45 absorbs heat from the thermal storage supply system 50 in the evaporator 41 and evaporates, is compressed into a high-temperature, high-pressure gas in the compressor 43, and is supplied to the condenser 42. The refrigerant supplied to the condenser 42 then releases heat in the condenser 42 to heat the raw water and generate water vapor. The refrigerant that passes through the condenser 42 becomes liquid, is depressurized by the expansion valve 44, and returns to the evaporator 41.

[0018] The thermal storage supply system 50 includes a thermal storage tank 51, a hot water supply line 52 connecting the hot water outlet of the thermal storage tank 51 to the hot water inlet of the steam heat pump 40 (evaporator 41), a hot water discharge line 53 connecting the hot water outlet of the steam heat pump 40 (evaporator 41) to the hot water inlet of the thermal storage tank 51, a hot water bypass line 55 connecting the hot water supply line 52 to the hot water discharge line 53 so as to bypass the thermal storage tank 51 for the steam heat pump 40, and a hot water adjustment valve 56 installed on the hot water bypass line 55. The thermal storage tank 51 stores hot water heated by heat exchange with waste heat from outside the system and keeps the hot water at a predetermined temperature range (e.g., 60-80°C). The waste heat from outside the system is unused low-temperature waste heat (e.g., below 100°C) from facilities that generate a lot of waste heat, such as factory waste heat. By making effective use of unused waste heat, the efficiency of the system can be improved.

[0019] The air supply system includes an air filter and an air blower (not shown), and air is sucked through the air filter by driving the air blower and supplied to the electrolysis module 20. The air supplied to the electrolysis module 20 passes through a heat exchanger 22 and a heater 24, and is heated to a required temperature by heat exchange with the combustion exhaust gas and by the heat of the heater 24, before being supplied to the oxidizer electrode of the electrolysis cell stack 21.

[0020] The hydrogen recovery system 60 includes a condenser 61, a hydrogen tank 62, a hydrogen recovery line 63 connecting the condenser 61 and the hydrogen tank 62, and a condensed water recovery line 64 connecting the condenser 61 and the water tank 31. The condenser 61 is supplied with anode off-gas containing hydrogen and water vapor discharged from the anode of the electrolysis cell stack 21. The anode off-gas supplied to the condenser 61 is subjected to heat exchange with cooling water to condense the water vapor, and the water vapor is then recovered from the hydrogen recovery line 63 to the hydrogen tank 62 by a booster pump (not shown). The condensed water generated by condensing the anode off-gas in the condenser 61 is recovered in the water tank 31 through the condensed water recovery line 64. The water stored in the water tank 31 is used as raw water for generating water vapor for electrolysis.

[0021] The hydrogen recovery system 60 also includes a hydrogen supply line 65 that branches off from the hydrogen recovery line 63 and is connected to the water vapor supply line 34. The hydrogen supply line 65 supplies a portion of the anode off-gas (hydrogen) that has passed through the condenser 61 as a reducing gas to the anode of the electrolysis cell stack 21. The hydrogen supply line 65 is also connected to a hydrogen tank 62 and branches into a combustion hydrogen supply line 66 that leads to the combustor 27. This allows the portion of the anode off-gas that has passed through the condenser 61 to be supplied to the combustor 27 as a combustion gas, or the hydrogen stored in the hydrogen tank 62 to be supplied to the combustor 27 as a combustion gas.

[0022] Although not shown, the control device 70 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, and input / output ports. Detection signals from a temperature sensor installed near the electrolytic cell stack 21, a temperature sensor installed in the heat storage tank 51, a temperature sensor 57 installed near the hot water inlet of the steam heat pump 40 (evaporator 41) in the hot water supply line 52, a flow rate sensor installed in the steam supply line 34, and the like are input to the control device 70 via the input port. Meanwhile, control signals are output from the control device 70 to the heaters 23, 24, the power source 26, the raw water pump 33, the control valve 38, the hot water pump 54, the hot water adjustment valve 56, the air pump, the steam heat pump 40, and the like via the output port.

[0023] Next, a description will be given of the operation of the electrolysis system 10 of this embodiment configured as described above. The electrolysis system 10 has three operation modes (system states): a normal operation mode, a system startup mode, and a high-temperature standby mode.

[0024] The normal operation mode is a mode in which hydrogen is produced by high-temperature steam electrolysis. In the normal operation mode, steam is generated from raw water using a steam heat pump 40, the generated steam is heated by a heater 23, and the heated steam is supplied to the fuel electrode of the electrolysis cell stack 21. Air used as a sweep gas is heated by a heater 24, and the heated steam is supplied to the oxidizer electrode of the electrolysis cell stack 21. Power is supplied to the electrolysis cell stack 21 from a power source 26.

[0025] In the normal operation mode, water vapor supplied to the fuel electrode of the electrolysis cell stack 21 is converted into hydrogen and oxygen ions (O 2-), and the oxygen ions permeate the solid electrolyte, generating oxygen at the oxidizer electrode. The hydrogen generated at the anode is discharged from the electrolysis cell stack 21 as anode off-gas together with water vapor that has not reacted in the electrolysis reaction, and is supplied to the hydrogen recovery system 60. The anode off-gas supplied to the hydrogen recovery system 60 is cooled by heat exchange with cooling water in the condenser 61, where the water vapor is removed, and then the anode off-gas is recovered in the hydrogen tank 62 through the hydrogen recovery line 63. Furthermore, a portion of the anode off-gas (hydrogen) that has passed through the condenser 61 is supplied as a reducing gas to the anode of the electrolysis cell stack 21 through the hydrogen supply line 65.

[0026] The system startup mode is a mode in which the system is started by heating the electrolysis cell stack 21 to a temperature at which hydrogen can be produced by steam electrolysis (hydrogen production temperature). The system startup mode is performed by stopping the supply of power from the power source 26, and by heating water vapor generated by the steam heat pump 40 with the heater 23 and supplying it to the anode of the electrolysis cell stack 21, and by heating air with the heater 24 and supplying it to the oxidizer electrode of the electrolysis cell stack 21, so that the temperature of the electrolysis cell stack 21 reaches a temperature at which hydrogen can be produced. The high-temperature standby mode is a mode in which the inside of the electrolysis module 20 (electrolysis cell stack 21) is kept at a predetermined temperature (standby temperature) after the normal operation mode has ended, so that the system can be quickly switched to the next normal operation mode. The high-temperature standby mode is performed by heating water vapor generated by the steam heat pump 40 with the heater 23 and supplying it to the anode of the electrolysis cell stack 21, and heating air with the heater 24 and supplying it to the oxidizer electrode of the electrolysis cell stack 21, so that the electrolysis cell stack 21 is maintained at the standby temperature while the supply of power from the power source 26 is stopped. Note that in both the system startup mode and the high-temperature standby mode, in order to reduce the power consumption of the heaters 23 and 24, the temperature of the electrolysis cell stack 21 may be raised or maintained by supplying hydrogen from the hydrogen tank 62 to the combustor 27 via the hydrogen supply line 65 and the combustion hydrogen supply line 66, and supplying air from the air supply system to the combustor 27 via the oxidizer electrode of the electrolysis cell stack 21 and combusting it in the combustor 27.

[0027] The electrolysis system 10 of this embodiment stores unused waste heat outside the system as hot water in a heat storage tank 51, and the steam heat pump 40 pumps the heat of the hot water from the heat storage tank 51 and transfers it to raw water, thereby heating the raw water and generating steam. The electrolysis system 10 then heats the generated steam to a required temperature using a heater 23 or the like before supplying it to the anode of the electrolysis cell stack 21. This allows the unused waste heat to be used for latent heat (state change) of the raw water, thereby efficiently utilizing the unused waste heat and further improving system efficiency. Furthermore, the electrolysis system 10 of this embodiment includes the heat storage tank 51, and controls the amount of heat input from the heat storage tank 51 to the steam heat pump 40 (evaporator 41) according to the state of the electrolysis system 10. This prevents unnecessary consumption of heat from the heat storage tank 51, and enables a stable supply of heat (hot water) to the steam heat pump 40 (evaporator 41) using a heat storage tank 51 with a relatively small capacity.

[0028] 2 is a flowchart showing an example of a vapor heat pump control process executed by the control device 70 (CPU). This process is repeatedly executed at predetermined time intervals.

[0029] When the vapor heat pump control process is executed, the control device 70 acquires the system status (S100) and determines whether the system is in system startup mode (S102) and whether the system is in high-temperature standby mode (S104). If the control device 70 determines that the system is not in system startup mode or high-temperature standby mode, it determines that the system is in normal operation mode, closes the hot water adjustment valve 56 (S106), and controls the hot water pump 54 so that hot water passes through the evaporator 41 at a constant flow rate (S108). As a result, the hot water in the heat storage tank 51 is introduced into the hot water inlet of the evaporator 41 of the vapor heat pump 40, passes through the evaporator 41 and exchanges heat with the refrigerant, and then is discharged from the hot water outlet of the evaporator 41 and returned to the heat storage tank 51. Then, the control device 70 controls the raw water pump 33 and the control valve 38 so that the raw water in the water tank 31 passes through the heat exchanger 36 of the heat storage tank 51 before being supplied to the condenser 42 of the steam heat pump 40 (S110), and ends the steam heat pump control process. As a result, in the normal operation mode, relatively high-temperature hot water is supplied to the evaporator 41 of the steam heat pump 40, and relatively high-temperature raw water is supplied to the condenser 42 of the steam heat pump 40. Therefore, a large amount of steam can be generated in the steam heat pump 40, and large amounts of hydrogen can be efficiently produced on demand.

[0030] On the other hand, if the control device 70 determines in S102 that the system is in the system startup mode or in S104 that the system is in the high-temperature standby mode, it sets the target value for the inlet hot water temperature of the vapor heat pump 40 (evaporator 41) to a temperature (e.g., 60°C) lower than the hot water temperature (e.g., 80°C) in the heat storage tank 51 (S112). Next, the control device 70 controls the hot water pump 54 so that hot water passes through the evaporator 41 at a constant flow rate (S114). Next, the control device 70 inputs the inlet hot water temperature of the vapor heat pump 40 (evaporator 41) detected by the temperature sensor 57 (S116), and controls the hot water adjustment valve 56 by feedback control so that the input inlet hot water temperature becomes the target temperature set in S112 (S118). The control device 70 then controls the raw water pump 33 and the control valve 38 so that the raw water from the water tank 31 bypasses the heat exchanger 36 of the heat storage tank 51 and is supplied to the condenser 42 of the steam heat pump 40 (S120), and ends the steam heat pump control process. As a result, in the system startup mode and high-temperature standby mode, relatively low-temperature hot water is supplied to the evaporator 41 of the steam heat pump 40, and relatively low-temperature raw water is supplied to the condenser 42 of the steam heat pump 40. Note that in S120, the control device 70 controlled the control valve 38 so that the raw water from the water tank 31 bypasses the heat exchanger 36 and is supplied to the condenser 42 of the steam heat pump 40, but the control valve 38 may also be controlled so that a portion of the raw water from the water tank 31 passes through the heat exchanger 36.

[0031] Fig. 3 is an explanatory diagram showing the flow of hot water to the vapor heat pump during system startup mode or high-temperature standby mode in a comparative example and this embodiment, and Fig. 4 is an explanatory diagram showing the control effect of the vapor heat pump during system startup mode or high-temperature standby mode in a comparative example and this embodiment. In the comparative example, during system startup mode or high-temperature standby mode, the thermal storage supply system 50 supplies hot water from the thermal storage tank 51 to the hot water inlet of the vapor heat pump 40 (evaporator 41) and circulates the hot water between the thermal storage tank 51 and the vapor heat pump 40 (evaporator 41) so that all of the hot water discharged from the hot water outlet of the vapor heat pump 40 (evaporator 41) is returned to the thermal storage tank 51 (see Fig. 3(a)). In contrast, in this embodiment, during the system startup mode or the high-temperature standby mode, the heat storage supply system 50 circulates a portion of the hot water that has passed through the hot water outlet of the vapor heat pump 40 (evaporator 41) to the hot water inlet of the vapor heat pump 40 (evaporator 41), bypassing the heat storage tank 51 (see FIG. 3(b)). As a result, in this embodiment, during the system startup mode or the high-temperature standby mode, when a large amount of steam is not required, the flow rate of hot water leaving the heat storage tank 51 (heat storage tank supply hot water flow rate) is reduced, and wasteful consumption of the hot water (heat) in the heat storage tank 51 can be suppressed. As a result, as shown in FIG. 4, in this embodiment, the amount of heat required to be stored in the heat storage tank 51 can be reduced compared to the comparative example, and the heat storage tank 51 can be made smaller. In addition, in this embodiment, during the system startup mode or high temperature standby mode, the steam supply system 30 supplies the raw water in the water tank 31 to the steam heat pump 40 (condenser 42) at a low temperature without passing it through the heat exchange section 36 of the heat storage tank 51, thereby further reducing the waste of hot water (heat) in the heat storage tank 51 and making it possible to further reduce the size of the heat storage tank 51.

[0032] In the above-described embodiment, the thermal storage supply system 50 is configured to return a portion of the hot water discharged from the hot water outlet of the vapor heat pump 40 (evaporator 41) to the hot water inlet of the vapor heat pump 40 (evaporator 41), bypassing the thermal storage tank 51, during the system startup mode or the high-temperature standby mode. However, the thermal storage supply system 50 may be configured to return all of the hot water discharged from the hot water outlet of the vapor heat pump 40 (evaporator 41) to the thermal storage tank 51 during the system startup mode or the high-temperature standby mode, while reducing the flow rate of hot water circulating between the thermal storage tank 51 and the vapor heat pump 40 (evaporator 41) compared to that during the normal operation mode. In this case, the hot water bypass line 55 and the hot water adjustment valve 56 may be omitted.

[0033] FIG. 5 is a flowchart showing a vapor heat pump control process according to another embodiment. Among the steps of the vapor heat pump control process in FIG. 5, the same steps as those in the vapor heat pump control process in FIG. 2 are assigned the same step numbers, and their descriptions will be omitted to avoid redundancy. In the vapor heat pump control process according to another embodiment, if the control device 70 determines in S102 and S104 that the system is not in the system startup mode or the high-temperature standby mode but is in the normal operation mode, the control device 70 controls the hot water pump 54 to circulate hot water at a first flow rate between the heat storage tank 51 and the vapor heat pump 40 (evaporator 41) (S108B), and then proceeds to S110. On the other hand, if the control device 70 determines in S102 that the system is in the system startup mode or the high-temperature standby mode in S104, the control device 70 reduces the rotation speed of the hot water pump 54 to circulate hot water at a second flow rate that is lower than the first flow rate (S114B), and then proceeds to S120.

[0034] FIG. 6 is an explanatory diagram showing the control effect of the steam heat pump during system startup mode or high-temperature standby mode in a comparative example and this embodiment. In another embodiment, the heat storage supply system 50 reduces the flow rate of circulating hot water (heat storage tank supply hot water flow rate) during system startup mode or high-temperature standby mode compared to normal operation mode. As a result, in the other embodiment, as in this embodiment, the flow rate of hot water leaving the heat storage tank 51 (heat storage tank supply hot water flow rate) during system startup mode or high-temperature standby mode can be reduced, thereby preventing the hot water (heat) in the heat storage tank 51 from being wasted. As a result, as shown in FIG. 6, in the other embodiment, the amount of heat required to be stored in the heat storage tank 51 can be reduced compared to the comparative example, and the heat storage tank 51 can be made smaller.

[0035] In the above-described embodiment, the raw water supply line 32 is provided with the heat exchanger 36 that exchanges heat between the raw water from the water tank 31 and the hot water in the heat storage tank 51. However, the heat exchanger 36 may be omitted.

[0036] In the above-described embodiment, the water vapor supplied from the water vapor supply system 30 to the electrolysis module 20 is heated by the heater 23. However, the water vapor may be heated by heat exchange with the anode off-gas or the oxidizer electrode off-gas discharged from the electrolysis cell stack 21, or by heat exchange with the combustion exhaust gas discharged from the combustor 27.

[0037] In the above-described embodiment, the electrolysis module 20 includes the heaters 23 and 24 and the combustor 27. However, either one of the heaters 23 and 24 or the combustor 27 may be omitted.

[0038] In the above-described embodiment, a portion of the anode off-gas from which water vapor has been removed by passing through the condenser 61 is returned as a reducing gas to the anode of the electrolysis cell stack 21. However, pressurized hydrogen in the hydrogen tank 62 may be supplied to the anode. Alternatively, a portion of the anode off-gas before passing through the condenser 61 may be returned to the anode within the electrolysis module 20 (module case 25).

[0039] In the above-described embodiment, the electrolysis system 10 includes the electrolysis cell stack 21 that generates hydrogen by high-temperature steam electrolysis. However, the electrolysis system 10 may use the electrolysis cell stack 21 as a reversible solid oxide cell stack, so that it can selectively perform the above-described electrolysis operation and a power generation operation that generates power by a reaction between hydrogen as a fuel gas and oxygen contained in an oxidant gas. In the electrolysis operation, hydrogen is introduced as a fuel gas from the hydrogen tank 62 to the fuel electrode of the electrolysis cell stack 21, and air is introduced as an oxidant gas from the air supply system to the oxidant electrode of the electrolysis cell stack 21. Then, oxide ions (O 2- ) is generated, and the oxide ions permeate the solid electrolyte and react with hydrogen at the fuel electrode, generating electrical energy.

[0040] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0041] The present disclosure is applicable to the electrolysis system manufacturing industry and the like. [Explanation of symbols]

[0042] 10 Electrolysis system, 21 Electrolysis cell stack (Electrolysis cell), 32 Raw water supply line (Raw water line), 36 Heat exchange section (Raw water heat exchange section), 37 Bypass line (Raw water bypass line), 38 Control valve, 40 Steam heat pump (Water vapor generation section), 41 Evaporator (Refrigerant heat exchange section), 50 Heat storage supply system (Heat storage supply section), 51 Heat storage tank (Heat storage section), 52 Hot water supply line (Supply line), 53 Hot water discharge line (Discharge line), 54 Hot water pump (Pump), 55 Hot water bypass line (Bypass line), 56 Adjustment valve, 70 Control device (Control section).

Claims

1. an electrolysis cell for generating hydrogen by high-temperature steam electrolysis; a steam generating unit including a refrigerant heat exchange unit that exchanges heat between the heat storage unit and a refrigerant, and that generates steam by heating raw water through the refrigerant that has undergone heat exchange in the refrigerant heat exchange unit, and supplies the steam to the electrolysis cell; a heat storage supply unit having the heat storage unit and supplying heat from the heat storage unit to the refrigerant heat exchange unit; a control unit that controls the heat storage supply unit so that the amount of heat input to the refrigerant heat exchange unit is reduced during system startup or high-temperature standby compared to during normal operation; An electrolysis system comprising:

2. 2. The electrolysis system of claim 1, the heat storage supply unit includes a supply line connected to the heat outlet of the heat storage unit and the heat inlet of the refrigerant heat exchange unit, a discharge line connected to the heat outlet of the refrigerant heat exchange unit and the heat inlet of the heat storage unit, a pump that circulates heat between the heat storage unit and the refrigerant heat exchange unit, a bypass line that is connected to the supply line and the discharge line so as to bypass the heat storage unit with respect to the refrigerant heat exchange unit, and an adjustment valve that adjusts the bypass amount of heat discharged from the heat outlet of the refrigerant heat exchange unit to the discharge line, The control unit controls the amount of heat input to the refrigerant heat exchange unit by adjusting the amount of heat bypassed by the adjustment valve. Electrolysis system.

3. 2. The electrolysis system of claim 1, the heat storage unit is a heat storage tank that stores hot water, the heat storage supply unit includes a supply line connected to a hot water outlet of the heat storage tank and a hot water inlet of the heat exchange unit, a discharge line connected to a hot water outlet of the refrigerant heat exchange unit and a hot water inlet of the heat storage tank, and a pump that circulates hot water between the heat storage tank and the refrigerant heat exchange unit, The control unit controls the amount of heat input to the refrigerant heat exchange unit by adjusting the amount of hot water circulated by the pump. Electrolysis system.

4. 4. The electrolysis system according to claim 1, a raw water heat exchange unit that exchanges heat between the raw water and the heat storage unit; a raw water line that supplies raw water to the steam generating unit through the raw water heat exchange unit; a raw water bypass line branching off from and joining the raw water line so as to bypass the raw water heat exchange section; a control valve for controlling the supply of raw water to the raw water heat exchange unit and the raw water bypass line; Equipped with the control unit controls the control valve so that the temperature of the raw water supplied to the steam generating unit is lower during system startup or high-temperature standby compared to during normal operation. Electrolysis system.

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