SOC system

Abstract

To suppress sudden rise of pressure when vaporizing water by a vaporizer provided in an SOC system.SOLUTION: The SOC system 1 is provided with a water pump 80 able to adjust a feed water flow, a vaporizer 30A generating steam by vaporizing water fed from the water pump 80, a cell stack 20 to which the steam generated at the vaporizer 30A is fed and which generates hydrogen and hydrogen by a steam electrolysis reaction and discharges a first exhaust gas containing the generated hydrogen and a second exhaust gas containing hydrogen, and a control device 100 controlling the vaporization of water at the vaporizer 30A. The vaporizer 30A includes a plurality of vaporizers, and water is supplied to each of the plurality of vaporizers, and thermal energy for heating the supplied water is supplied to each of the plurality of vaporizers. The control device 100 controls the flow amount of the water supplied from the water pump 80 to the vaporizer 30A based on the physical quantity correlated with the heat energy amount supplied to the plurality of vaporizers.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to SOC systems. [Background technology]

[0002] A SOFC system is a power generation system that generates electricity using a solid oxide fuel cell (SOFC). A SOEC system is a gas production system that produces hydrogen, carbon monoxide, or both by performing an electrolytic reaction using a solid oxide electrolysis cell (SOEC). An r-SOC system is a system that combines the functions of a SOFC system and an SOEC system. In this specification, SOFC systems, SOEC systems, and r-SOC systems are collectively referred to as SOC systems.

[0003] SOC systems require water vapor. For example, SOEC systems require water vapor as a feed gas for the steam electrolysis reaction, and SOFC systems require water vapor as a feed gas for the hydrocarbon reforming reaction. For this reason, SOC systems are equipped with a vaporizer that generates water vapor by vaporizing water. Patent Document 1 discloses an SOEC system (hydrocarbon production system) equipped with a vaporizer. Patent Document 1 also shows an example in which the vaporizer includes multiple vaporizers (first and second evaporators). These vaporizers are supplied with thermal energy to heat and vaporize water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-161600 Summary of the Invention

[0005] When a vaporizer has multiple vaporizers, it is difficult to supply an appropriate amount of heat energy to all of the vaporizers. If the amount of heat energy supplied to a particular vaporizer is too large compared to the amount of water supplied to that vaporizer, the water supplied to that vaporizer will evaporate all at once, causing a sudden rise in pressure. This sudden rise in pressure is undesirable because it can have a negative impact on components connected downstream of the vaporizer.

[0006] The present disclosure aims to solve the above-mentioned problems. That is, one of the objectives of the present disclosure is to suppress the occurrence of a sudden rise in pressure when water is vaporized by a vaporizer provided in an SOC system.

[0007] The SOC system (1, 2, 3) according to the present disclosure includes a water supply device (80, 81, 82) capable of adjusting a supply water flow rate, a vaporization device (30A, 30B) that generates water vapor by vaporizing water supplied from the water supply device (80, 81, 82), a reaction device (20) that receives the water vapor generated in the vaporization device (30A, 30B), generates a first gas and a second gas through a chemical reaction using the supplied water vapor, and discharges a first exhaust gas containing the generated first gas and a second exhaust gas containing the second gas, and a control device (100) that controls the vaporization of water in the vaporization device (30A, 30B). The vaporization device (30A, 30B) includes a plurality of vaporizers (31, 32 or 33, 34), and the plurality of vaporizers (31, 32 or 33, 34) are each supplied with water and thermal energy for heating the supplied water. The control device (100) controls the flow rate of water supplied from the water supply devices (80, 81, 82) to the vaporizers (30A, 30B) based on a physical quantity correlated with the amount of thermal energy supplied to the plurality of vaporizers (31, 32 or 33, 34).

[0008] According to the SOC system of the present disclosure, the flow rate of water supplied from the water supply device to the vaporizer is controlled based on a physical quantity correlated with the amount of thermal energy supplied to the multiple vaporizers. That is, the control device controls the flow rate of water supplied to the vaporizers according to the amount of thermal energy supplied to the multiple vaporizers. This allows each vaporizer to be supplied with an appropriate amount of water according to the amount of thermal energy supplied to each vaporizer, thereby enabling each vaporizer to stably vaporize water. As a result, a sudden increase in pressure in each vaporizer can be suppressed.

[0009] A physical quantity correlated with the amount of thermal energy is a physical quantity whose change affects the amount of thermal energy. The physical quantity correlated with the amount of thermal energy may be the amount of thermal energy itself, or a physical quantity required to calculate the amount of thermal energy, such as temperature or a temperature difference. Here, the amount of thermal energy is the amount of heat flowing in per unit time (heat flow rate). For example, when referring to the amount of thermal energy supplied to a vaporizer, the amount of thermal energy is the amount of heat [J / sec.] supplied to the vaporizer per unit time.

[0010] In one aspect of the SOC system according to the present disclosure, the plurality of vaporizers (31, 32) are connected in series, and the water supply device (80) is connected to the first-stage vaporizer (31), which is the most upstream vaporizer of the plurality of vaporizers (31, 32) connected in series, so as to supply water to the first-stage vaporizer (31). The control device (100) controls the flow rate of water supplied from the water supply device (80) to the first-stage vaporizer (31), based on a physical quantity correlated with the amount of thermal energy supplied to the plurality of vaporizers (31, 32).

[0011] According to the above configuration, water can be stably vaporized in the plurality of vaporizers connected in series, thereby making it possible to suppress the occurrence of a sudden rise in pressure in each vaporizer.

[0012] In another aspect of the SOC system according to the present disclosure, the control device (100) controls the flow rate of water supplied from the water supply device (80) to the first-stage vaporizer (31) so that the flow rate of water supplied to the first-stage vaporizer (31) increases as the amount of thermal energy supplied to the plurality of vaporizers (31, 32) increases.

[0013] According to the above configuration, the first-stage vaporizer is supplied with an amount of water commensurate with the amount of thermal energy supplied to the series-connected vaporizers, allowing the series-connected vaporizers to stably vaporize water, thereby preventing a sudden rise in pressure in each vaporizer.

[0014] In another aspect of the SOC system according to the present disclosure, the plurality of vaporizers (31, 32) include an initial-stage vaporizer (31) and one subsequent-stage vaporizer (32) arranged downstream of the initial-stage vaporizer (31). The initial-stage vaporizer (31) has an initial-stage vaporization chamber (311) to which water is supplied from a water supply device (80) and an initial-stage heating chamber (312) arranged adjacent to the initial-stage vaporization chamber (311) and to which a first exhaust gas discharged from the reaction device (20) is supplied. The subsequent-stage vaporizer (32) has a subsequent-stage vaporization chamber (321) to which water is supplied from the initial-stage vaporization chamber (311) and a subsequent-stage heating chamber (322) arranged adjacent to the subsequent-stage vaporization chamber (321) and to which a second exhaust gas discharged from the reaction device (20) is supplied. The subsequent-stage vaporization chamber (321) is connected in series downstream of the initial-stage vaporization chamber (311). The control device (100) controls the flow rate of water supplied from the water supply device (80) to the first-stage evaporation chamber (311) based on the temperature (T1) of the first exhaust gas supplied to the first-stage heating chamber (312) and the temperature (T2) of the second exhaust gas supplied to the second-stage heating chamber (322).

[0015] According to the above configuration, the thermal energy of the first exhaust gas discharged from the reactor is supplied to the first-stage vaporizer, and the thermal energy of the second exhaust gas discharged from the reactor is supplied to the second-stage vaporizer, thereby enabling effective utilization of the thermal energy of the gases discharged from the reactor. Furthermore, the flow rate of water supplied to the first-stage vaporization chamber is controlled based on the temperature of the first exhaust gas, which is a physical quantity correlated with the amount of thermal energy supplied from the first exhaust gas to the first-stage vaporizer, and the temperature of the second exhaust gas, which is a physical quantity correlated with the amount of thermal energy supplied from the second exhaust gas to the second-stage vaporizer. This allows water to be stably vaporized in the first-stage vaporization chamber and the second-stage vaporization chamber, thereby preventing a sudden rise in pressure in each vaporization chamber.

[0016] In yet another aspect of the SOC system according to the present disclosure, the SOC system (2) includes a heat source device (60) for supplying thermal energy to either or both of the first exhaust gas supplied to the initial heating chamber (312) and the second exhaust gas supplied to the subsequent heating chamber (322). The control device (100) controls either or both of the amount of thermal energy supplied from the heat source device (60) to the first exhaust gas and the amount of thermal energy supplied from the heat source device (60) to the second exhaust gas, based on either or both of the temperature of the first exhaust gas supplied to the initial heating chamber (312) and the temperature of the second exhaust gas supplied to the subsequent heating chamber (322).

[0017] According to the above configuration, by controlling the amount of thermal energy supplied from the heat source device to the first exhaust gas or the second exhaust gas, it is possible to efficiently generate water vapor.

[0018] In yet another embodiment of the SOC system according to the present disclosure, the heat source device (60) is configured to heat the second exhaust gas supplied to the post-heating chamber (322).

[0019] According to the above configuration, by controlling the heat source device so as to reliably vaporize the water supplied to the rear-stage vaporization chamber, it is possible to prevent a decrease in the amount of water vapor, pressure changes, and water outflow to the downstream side due to insufficient heat of vaporization. Also, by controlling the heat source device so that the temperature of the second exhaust gas supplied to the rear-stage heating chamber exceeds the temperature of the first exhaust gas supplied to the initial-stage heating chamber, the water vapor vaporized in the initial-stage vaporizer can also be heated in the rear-stage vaporizer, improving heat conversion efficiency.

[0020] In still another aspect of the SOC system according to the present disclosure, the control device (100) calculates a predicted value of the amount of water vapor to be generated per unit time in the vaporizer (30A) as a predicted water vapor flow rate (V) based on a physical quantity correlated with the amount of thermal energy supplied to each of the plurality of vaporizers (31, 32), sets the predicted water vapor flow rate (V) as a target flow rate (Ft), and controls the flow rate of water supplied from the water supply device (80) to the first-stage vaporizer (31) so that the flow rate of water supplied from the water supply device (80) to the first-stage vaporizer (31) matches the target flow rate (Ft).

[0021] According to the above configuration, the vaporizer can be supplied with an amount of water that corresponds to the flow rate of water vapor generated by the thermal energy supplied to the vaporizer, thereby stably vaporizing water in the vaporizer and thereby suppressing a sudden rise in pressure in each vaporizer.

[0022] In yet another aspect of the SOC system according to the present disclosure, the vaporizers (33, 34) are connected in parallel, and the water supply devices (81, 82) are connected to the parallel-connected vaporizers (33, 34), respectively. The control device (100) controls the flow rates of water supplied from the water supply devices (81, 82) to the vaporizers (33, 34), respectively, based on a physical quantity correlated with the amount of thermal energy supplied to the vaporizers (33, 34).

[0023] According to the above configuration, water can be stably vaporized in the plurality of vaporizers connected in parallel, thereby making it possible to suppress the occurrence of a sudden rise in pressure in each vaporizer.

[0024] In yet another aspect of the SOC system according to the present disclosure, the plurality of vaporizers (33, 34) include a first vaporizer (33) and a second vaporizer (34), and the water supply devices (81, 82) include a first water supply device (81) that supplies water to the first vaporizer (33) and a second water supply device (82) that supplies water to the second vaporizer (34). The first vaporizer (33) has a first vaporization chamber (331) to which water is supplied from a first water supply device (81) and a first heating chamber (332) disposed adjacent to the first vaporization chamber (331) and to which a first exhaust gas discharged from the reaction device (20) is supplied. The second vaporizer (34) has a second vaporization chamber (341) to which water is supplied from a second water supply device (82) and a second heating chamber (342) disposed adjacent to the second vaporization chamber (341) and to which a second exhaust gas discharged from the reaction device (20) is supplied. The first vaporization chamber (331) and the second vaporization chamber (341) are connected in parallel. The control device (100) controls the flow rate of water supplied from the first water supply device (81) to the first vaporization chamber (331) based on the temperature of the first exhaust gas supplied to the first heating chamber (332), and controls the flow rate of water supplied from the second water supply device (82) to the second vaporization chamber (341) based on the temperature of the second exhaust gas supplied to the second heating chamber (342).

[0025] According to the above configuration, the vaporization chambers of the plurality of vaporizers connected in parallel are each supplied with an amount of water commensurate with the magnitude of the thermal energy of the gas supplied to the heating chamber of each vaporizer, thereby enabling stable vaporization of water in the plurality of vaporizers connected in parallel and thereby preventing a sudden rise in pressure in the vaporization chamber of each vaporizer. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a block diagram of a SOC system according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of the vaporizer. [Figure 3] FIG. 2 is a perspective view of a cell stack. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2 is a cross-sectional view of an electrolysis cell in the thickness direction. [Figure 6] FIG. 2 is a schematic cross-sectional view of a vaporizer in which a rear-stage vaporization chamber is in an empty-fire state. [Figure 7] 10 is a schematic cross-sectional view of the vaporizer showing a state in which water in the rear-stage vaporization chamber has overflowed. FIG. [Figure 8A] 3 is a diagram showing an example of a flowchart of a program executed by a CPU so that the control device according to the first embodiment executes supply water flow rate control. FIG. [Figure 8B] 3 is a diagram showing an example of a flowchart of a program executed by a CPU so that the control device according to the first embodiment executes supply water flow rate control. FIG. [Figure 8C] 10 is a table showing the relationship between the first temperature T1 and the second temperature T2 and the set water flow rate F. [Figure 9] FIG. 10 is a diagram showing an example of a flowchart of a program executed by a CPU so that a control device according to a second modification of the first embodiment executes supply water flow rate control. [Figure 10] FIG. 10 is a block diagram of a SOC system according to a second embodiment. [Figure 11] FIG. 10 is a diagram showing an example of a flowchart of a program executed by a CPU so that a control device according to a second embodiment executes thermal energy control. [Figure 12] FIG. 10 is a block diagram of a SOC system according to a third embodiment. [Figure 13] FIG. 11 is a diagram showing an example of a flowchart of a program executed by a CPU so that a control device according to a third embodiment executes supply water flow rate control. DETAILED DESCRIPTION OF THE INVENTION

[0027] (First embodiment) Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a block diagram of an SOC system 1 according to a first embodiment. The SOC system 1 according to this embodiment is a hydrogen production system (SOEC system) that produces hydrogen by electrolyzing water vapor. As shown in FIG. 1, the SOC system 1 includes a hot module 10, a water pump 80, a condenser 90, a control device 100, and a plurality of passages. The plurality of passages include passage R1, passage R2, passage R3, passage R4, passage R5, passage R6, passage R7, passage R8, passage R9, passage R10, and passage R11.

[0028] Water pump 80 has an intake port and an outlet port. A water source is connected to the intake port of water pump 80 via passage R1. Water pump 80 draws water through the intake port and delivers the drawn water to the outlet port. The outlet port of water pump 80 is connected to vaporizer 30A (described later) via passage R2. Water pump 80 is also configured to adjust the flow rate of water delivered from the outlet port to vaporizer 30A. Therefore, water pump 80 is a water supply device that supplies water to vaporizer 30A and can adjust the flow rate of the supplied water. Note that configurations other than a water pump can be used as the water supply device. For example, a variable flow valve or the like can be used as the water supply device.

[0029] The hot module 10 is constructed by covering with insulating material the main components that become hot among the elements that make up the SOC system 1, and is a device that aggregates the main components within the insulating material so that the high temperature state of the main components is maintained. This hot module 10 includes a cell stack 20, a vaporizer 30A, a temperature raising device 40, and an insulating material 50.

[0030] Vaporization device 30A includes initial-stage vaporizer 31 and post-stage vaporizer 32. Initial-stage vaporizer 31 and post-stage vaporizer 32 are connected in series via passage R3. Initial-stage vaporizer 31 is the most upstream of the two series-connected vaporizers (initial-stage vaporizer 31 and post-stage vaporizer 32). Post-stage vaporizer 32 is disposed downstream of initial-stage vaporizer 31.

[0031] 2 is a schematic cross-sectional view of vaporization device 30A. As shown in FIGS. 1 and 2, first-stage vaporizer 31 of vaporization device 30A has first-stage vaporization chamber 311 and first-stage heating chamber 312. Furthermore, second-stage vaporizer 32 of vaporization device 30A has second-stage vaporization chamber 321 and second-stage heating chamber 322.

[0032] Passage R2 is connected to initial-stage vaporization chamber 311. Therefore, water is supplied from water pump 80 to initial-stage vaporization chamber 311. The water supplied to initial-stage vaporization chamber 311 is temporarily stored in initial-stage vaporization chamber 311. The water temporarily stored in initial-stage vaporization chamber 311 is vaporized, thereby generating water vapor in initial-stage vaporization chamber 311. The water vapor generated in initial-stage vaporization chamber 311 flows downstream into subsequent-stage vaporization chamber 321 via passage R3. Furthermore, water supplied to initial-stage vaporization chamber 311 that overflows initial-stage vaporization chamber 311 is supplied to subsequent-stage vaporization chamber 321 via passage R3. Therefore, water vapor and water are supplied to subsequent-stage vaporization chamber 321 from initial-stage vaporization chamber 311 via passage R3. The water supplied to subsequent-stage vaporization chamber 321 is temporarily stored in subsequent-stage vaporization chamber 321. The water temporarily stored in the latter-stage vaporization chamber 321 is vaporized, thereby generating water vapor in the latter-stage vaporization chamber 321. The water vapor generated in the first-stage vaporization chamber 311 and the water vapor generated in the latter-stage vaporization chamber 321 are supplied to the temperature raising device 40 via the passage R4.

[0033] As shown in FIG. 2, first-stage heating chamber 312 is disposed adjacent to first-stage vaporization chamber 311. Specifically, first-stage heating chamber 312 is disposed adjacent to first-stage vaporization chamber 311 so as to be in contact with the portion of first-stage vaporization chamber 311 where water is stored. High-temperature first exhaust gas discharged from cell stack 20 is supplied to first-stage heating chamber 312 via passage R6. As a result, thermal energy of the first exhaust gas is supplied to first-stage vaporizer 31. The water stored in first-stage vaporization chamber 311 is heated by the thermal energy of the high-temperature first exhaust gas supplied to first-stage heating chamber 312, and is thereby vaporized.

[0034] Furthermore, the post-heating chamber 322 is disposed adjacent to the post-vaporization chamber 321. Specifically, the post-heating chamber 322 is disposed adjacent to the post-vaporization chamber 321 so as to be in contact with the portion of the post-vaporization chamber 321 where water is stored. The high-temperature second exhaust gas discharged from the cell stack 20 is supplied to the post-heating chamber 322 via the passage R10. As a result, the thermal energy of the second exhaust gas is supplied to the post-vaporizer 32. The water stored in the post-vaporization chamber 321 is heated by the thermal energy of the high-temperature second exhaust gas supplied to the post-heating chamber 322, and is thereby vaporized.

[0035] As described above, water vapor is supplied to the temperature raising device 40 from the rear-stage vaporization chamber 321 of the vaporizer 30A via passage R4, and air is also supplied via passage R8. The temperature raising device 40 heats the supplied water vapor and air to the operating temperature of the cell stack 20 (i.e., the temperature required to operate the cell stack 20). The high-temperature first and second exhaust gases discharged from the cell stack 20 are used as a heat source to heat the water vapor and air in the temperature raising device 40. The temperature raising device 40 also includes a heater. This heater further heats the water vapor and air heated by the first and second exhaust gases. This heats the water vapor and air to the operating temperature. The water vapor heated to the operating temperature by the temperature raising device 40 is introduced into the cell stack 20 via passage R5. The air heated to the operating temperature by the temperature raising device 40 is also supplied to the cell stack 20 via passage R9.

[0036] The cell stack 20 is a reaction device that generates hydrogen as a first gas and oxygen as a second gas through an electrochemical reaction using water vapor supplied from the vaporizer 30A via the heating device 40, and discharges a first exhaust gas containing the generated hydrogen and a second exhaust gas containing the generated oxygen. The cell stack 20 is formed by stacking solid oxide electrolysis cells (SOECs). The cell stack 20 is heated to an operating temperature by a heat source (such as a burner) (not shown). A predetermined voltage is applied to the cell stack 20. As a result, water vapor introduced into the cell stack 20 is electrolyzed to generate hydrogen and oxygen.

[0037] FIG. 3 is a perspective view of the cell stack 20, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3 . As shown in FIGS. 3 and 4 , the cell stack 20 comprises an electrolysis unit group including a plurality of rectangular flat-plate-shaped electrolysis units Ue stacked in the thickness direction (vertical direction), and a pair of end plates 27, 28 disposed on the upper and lower surfaces of the electrolysis unit group, respectively. The end plates 27, 28 are each a rectangular flat-plate-shaped member having the same outer shape as the electrolysis unit Ue, and each have a rectangular opening formed in their center. The electrolysis unit group and the end plates 27, 28 are fastened to each other at their four corners by bolts B inserted through the end plates 27, 28 in the thickness direction and nuts (not shown). The end plates 27, 28 are made of metal (for example, stainless steel) and function as an anode and a cathode, respectively, when a voltage is applied. For ease of explanation, the proportions of the components in the drawings may differ from the actual proportions.

[0038] The electrolysis unit Ue will be described with reference to Fig. 4. As shown in Fig. 4, the electrolysis unit Ue comprises a solid oxide electrolysis cell 21 (hereinafter simply referred to as the electrolysis cell 21), an interconnector 22, a separator 23, a cathode frame 24, a fuel electrode frame 25, and a current collector 26.

[0039] The electrolysis cell 21 is the smallest unit of an SOEC and includes a solid electrolyte layer 211, an air electrode layer 212 laminated on the upper surface of the solid electrolyte layer 211, and an anode layer 213 laminated on the rear surface (lower surface) of the solid electrolyte layer 211. The air electrode layer 212 has a smaller outer shape than the solid electrolyte layer 211 and the anode layer 213, and is disposed in the center of the upper surface of the solid electrolyte layer 211 in a plan view of the electrolysis cell 21. Therefore, the upper surface of the outer periphery of the solid electrolyte layer 211 is exposed.

[0040] The interconnector 22 is a rectangular metal (for example, stainless steel) member that has a rectangular current collecting part 22a that protrudes downward from the center of its lower surface. A pair of interconnectors 22 is arranged on both sides of the electrolysis cell 21 in the thickness direction. Two adjacent electrolysis units Ue, Ue share one interconnector 22. The interconnector 22 also functions as a separator that separates the two adjacent electrolysis units Ue, Ue. The lower surface of the current collecting part 22a is in contact with the upper surface of the air cathode layer 212 of the electrolysis cell 21. The lower electrolysis unit Ue includes a pair of interconnectors 22, 29 instead of the pair of interconnectors 22, 22. The interconnector 29 is arranged at the bottom end of the cell stack 20 and differs from the interconnector 22 in that it does not have a current collecting part 22a.

[0041] The separator 23 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in the center. The periphery of the opening of the separator 23 is brazed to the upper surface of the outer periphery of the solid electrolyte layer 211 of the electrolysis cell 21 with a brazing material (e.g., Ag brazing) (not shown). The separator 23 prevents mixing of oxygen generated in the air electrode layer 212 by electrolysis of water vapor and hydrogen generated in the fuel electrode layer 213.

[0042] The cathode frame 24 is a rectangular plate-shaped insulating member and may be formed of, for example, a mica sheet. A rectangular opening is formed in the center of the cathode frame 24. The cathode frame 24 is disposed between the separator 23 and the interconnector 22 above it.

[0043] The fuel electrode frame 25 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in the center thereof. The fuel electrode frame 25 is disposed between the separator 23 and the interconnector 22 below it.

[0044] The internal space of the electrolysis unit Ue is partitioned into an air chamber Sa and a fuel chamber Sf by the separator 23. The air chamber Sa is a space that allows the flow of oxygen generated in the air electrode layer 212, and is defined by a space surrounded by the upper interconnector 22, separator 23, air electrode frame 24, and electrolysis cell 21. The fuel chamber Sf is a space that allows the flow of hydrogen generated in the fuel electrode layer 213, and is defined by a space surrounded by the lower interconnector 22 (or interconnector 29), separator 23, fuel electrode frame 25, and electrolysis cell 21.

[0045] The current collector 26 is a rectangular porous member made of metal (for example, nickel) that is smaller than the fuel electrode layer 213 in plan view and allows hydrogen to pass through. The current collector 26 is arranged in the fuel chamber Sf so as to be in contact with the lower surface of the fuel electrode layer 213 and the upper surface of the lower interconnector 22. Two adjacent electrolysis cells 21 are stacked in the thickness direction so as to share the interconnector 22 via the current collector 26, thereby electrically connecting the multiple electrolysis cells 21 in series.

[0046] 3 and 4, four paths Pfi, Pfo, Pai, and Pao are formed as gas flow paths around the outer periphery of the cell stack 20. These paths Pfi, Pfo, Pai, and Pao are each formed to penetrate through members of the cell stack 20 in the thickness direction, excluding the "end plate 27" and the "upper interconnector 22 of the upper electrolysis unit Ue."

[0047] The path Pfi is formed near one corner of the side E1, which is one of the four sides that make up the outer periphery of the cell stack 20. The path Pfo is formed near the other corner of the side E2 that faces the side E1 (the corner located diagonally from the one corner of the side E1). As shown in FIG. 4 , the path Pfi communicates with the fuel chamber Sf via a horizontal hole 25a formed in the anode frame 25 of each electrolysis unit Ue. The path Pfo communicates with the fuel chamber Sf via a horizontal hole 25b formed in the anode frame 25 of each electrolysis unit Ue. The path Pfi is connected to the path R5 in FIG. 1 , and the path Pfo is connected to the path R6 in FIG. 1 .

[0048] Path Pai is formed near one corner of side E2. Path Pao is formed near the other corner of side E1. Path Pai and path Pao each communicate with the air chamber Sa via a horizontal hole (not shown) formed in the air electrode frame 24 of each electrolysis unit Ue. Path Pai is connected to path R9 in FIG. 1 , and path Pao is connected to path R10 in FIG. 1 .

[0049] Next, the configuration of the electrolysis cell 21 will be described in more detail with reference to FIG. 5. FIG. 5 is a cross-sectional view of the electrolysis cell 21 in the thickness direction. As described above, the electrolysis cell 21 includes a solid electrolyte layer 211, an air cathode layer 212, and an anode layer 213. In this embodiment, the solid electrolyte layer 211 is a rectangular flat layer measuring approximately 150 mm square and approximately 6 μm thick, and is configured to contain YSZ (yttria-stabilized zirconia) and formed by sintering. The solid electrolyte layer 211 has high oxide ion conductivity. The solid electrolyte layer 211 is a dense layer and is designed to prevent leakage between the atmosphere on the air cathode layer 212 side (air atmosphere) and the atmosphere on the anode layer 213 side (reducing atmosphere).

[0050] The air electrode layer 212 is laminated on the upper surface 211B side of the solid electrolyte layer 211. The air electrode layer 212 is a rectangular flat layer with a thickness of approximately 100 μm, is configured to contain a perovskite oxide such as LSCF (lanthanum strontium cobalt iron oxide), and is formed by sintering. The air electrode layer 212 has a functional layer and a current collecting layer. The current collecting layer is thicker than the functional layer and is disposed on the upper surface of the functional layer. The air electrode layer 212 has high electronic conductivity and effectively collects electrons from the current collecting layer. The air electrode layer 212 is a porous layer with pores inside.

[0051] The anode layer 213 is a rectangular flat layer measuring approximately 150 mm square, and is formed to have a thickness of, for example, approximately 400 μm, which is greater than the thicknesses of the solid electrolyte layer 211 and the air cathode layer 212. The anode layer 213 supports the solid electrolyte layer 211 and the air cathode layer 212. In other words, the electrolysis cell 21 is an anode-supported cell. The anode layer 213 includes an anode functional layer 213a and an anode support layer 213b. The anode support layer 213b is formed to be significantly thicker than the anode functional layer 213a, and the thickness ratio can be set to, for example, approximately 16 to 40 times.

[0052] The anode layer 213 is laminated on the back surface 211A side of the solid electrolyte layer 211, which is the bottom surface in Fig. 5. Specifically, the anode functional layer 213a is laminated on the back surface 211A of the solid electrolyte layer 211, and the anode support layer 213b is laminated on the back surface (bottom surface in Fig. 5) of the anode functional layer 213a. In other words, the anode functional layer 213a and the anode support layer 213b are laminated on the back surface 211A side of the solid electrolyte layer 211 in this order.

[0053] The anode support layer 213b is primarily composed of a cermet of Ni and YSZ (yttria-stabilized zirconia). The anode support layer 213b is a porous layer configured to have a porous shape including a plurality of micropores (not shown). The diameter of the micropores is on the order of several μm, which ensures water vapor permeability (gas diffusibility). The anode functional layer 213a is also primarily composed of a cermet of Ni and YSZ. Like the anode support layer 213b, the anode functional layer 213a is also a porous layer configured to have a porous shape including a plurality of micropores (not shown). The anode functional layer 213a is formed to be denser than the anode support layer 213b. That is, the anode functional layer 213a and the anode support layer 213b are formed so that the porosity of the anode functional layer 213a is smaller than that of the anode support layer 213b. The anode layer 213 is formed by sintering, similar to the solid electrolyte layer 211 and the air cathode layer 212. The components of the anode functional layer 213a and the anode support layer 213b are not limited to those described above. For example, the anode functional layer 213a may be mainly composed of Ni and gadolinia-doped ceria (GDC).

[0054] The operation of the cell stack 20 will be described. First, a voltage is applied between the end plates 27, 28 of the cell stack 20. Next, high-temperature steam is supplied from the path Pfi. The steam supplied to the path Pfi flows into the fuel chamber Sf of each electrolysis unit Ue via the horizontal holes 25a. In addition, high-temperature air is supplied from the path Pai. The air supplied to the path Pai flows into the air chamber Sa of each electrolysis unit Ue via horizontal holes (not shown). The reason for supplying high-temperature air to the air chamber Sa is to control the temperature of the cell stack 20.

[0055] The water vapor that flows into the fuel chamber Sf passes through the anode support layer 213b and travels to the anode functional layer 213a. In the anode functional layer 213a, the water vapor reacts with electrons supplied from the end plate 28 via the current collector 26 and is decomposed into hydrogen and oxide ions (water vapor electrolysis reaction). The hydrogen produced by the water vapor electrolysis reaction diffuses within the fuel chamber Sf and is discharged from path Pfo via the horizontal holes 25b. At this time, unreacted water vapor is discharged from path Pfo together with the hydrogen. Meanwhile, the oxide ions travel via the solid electrolyte layer 211 to the air cathode layer 212 in the air chamber Sa, where they release electrons in the functional layer of the air cathode layer 212 and become oxygen. The oxygen diffuses within the air chamber Sa and is discharged from path Pao via the horizontal holes (not shown) together with the air that flowed into the air chamber Sa. In this way, the cell stack 20, which is made up of stacked electrolytic cells 21, generates a first gas (hydrogen) and a second gas (oxygen) through an electrochemical reaction using water vapor, and discharges a high-temperature first exhaust gas containing the generated first gas (hydrogen) and water vapor, and a high-temperature second exhaust gas containing the generated second gas (oxygen) and air.

[0056] Electrons emitted from the functional layer of the air electrode layer 212 are collected by the current collecting portion 22a of the interconnector 22 via the current collecting layer, and circulate from the end plate 27 to the end plate 28 via the external power supply.

[0057] As shown in FIG. 1 , the high-temperature first exhaust gas discharged from cell stack 20 is introduced into temperature raising device 40 via passage R6, where it is used to heat the water vapor and air supplied from vaporization device 30A to temperature raising device 40, and then supplied to first-stage heating chamber 312 of first-stage vaporizer 31. Then, the water in first-stage vaporization chamber 311 is heated and vaporized by the thermal energy of the first exhaust gas supplied to first-stage heating chamber 312. The first exhaust gas that has heated the water in first-stage heating chamber 312 is then introduced from first-stage heating chamber 312 into condenser 90 via passage R7. Water vapor is condensed in condenser 90. The condensed water produced in condenser 90 is supplied to passage R1. Meanwhile, hydrogen separated by condensation of the water vapor in condenser 90 is recovered.

[0058] Furthermore, the high-temperature second exhaust gas discharged from the cell stack 20 is introduced into the temperature raising device 40 via the passage R10, where it is used to heat the water vapor and air, and is then supplied to the rear-stage heating chamber 322 of the rear-stage vaporizer 32. Then, the water in the rear-stage vaporization chamber 321 is heated and vaporized by the thermal energy of the second exhaust gas supplied to the rear-stage heating chamber 322. The second exhaust gas that has heated the water in the rear-stage vaporization chamber 321 then flows from the rear-stage heating chamber 322 to the passage R11 and is recovered (or released to the atmosphere).

[0059] The cell stack 20, the vaporizer 30A, and the temperature raising device 40 are disposed inside the heat insulating material 50. This suppresses heat radiation from each component. Heat-resistant fibers such as ceramic wool, refractory ceramic fiber (RCF), and biosoluble fiber (AES), and / or a heat-resistant container formed from these heat-resistant fibers, may be used for the heat insulating material 50. The heat-resistant fibers are disposed so as to fill the gaps between the cell stack 20, the vaporizer 30A, and the temperature raising device 40.

[0060] 1 , the SOC system 1 also has a first temperature sensor 71 and a second temperature sensor 72. The first temperature sensor 71 is attached to the passage R6. The first temperature sensor 71 is attached to a position in the passage R6 close to the first-stage heating chamber 312. The first temperature sensor 71 detects a first temperature T1, which is the temperature of the first exhaust gas supplied from the passage R6 to the first-stage heating chamber 312, and transmits a temperature signal indicating the detected first temperature T1 to the control device 100.

[0061] The second temperature sensor 72 is attached to the passage R10. The second temperature sensor 72 is attached to a position in the passage R10 close to the rear-heating chamber 322. The second temperature sensor 72 detects a second temperature T2, which is the temperature of the second exhaust gas supplied from the passage R10 to the rear-heating chamber 322, and transmits a temperature signal representing the detected second temperature T2 to the control device 100.

[0062] The control device 100 controls the operating state of the SOC system 1. The control device 100 mainly comprises a microcomputer including a CPU, ROM, and RAM. The ROM of the control device 100 stores a program for controlling the operating state of the SOC system 1 in advance. The CPU of the control device 100 reads the program from the ROM, expands it into the RAM, and executes it.

[0063] The control device 100 executes supply water flow rate control during operation of the SOC system 1. In this supply water flow rate control, the control device 100 acquires a first temperature T1 and a second temperature T2 based on temperature signals received from the first temperature sensor 71 and the second temperature sensor 72. Then, the control device 100 controls the flow rate of water supplied from the water pump 80 to the first-stage vaporization chamber 311 of the vaporization device 30A based on the first temperature T1 and the second temperature T2. The supply water flow rate control will be described below.

[0064] As shown in FIG. 2, the normal water storage state is when water is stored in first-stage vaporization chamber 311 and second-stage vaporization chamber 321 of vaporization device 30A, and the water in second-stage vaporization chamber 321 does not overflow into passage R4. This normal state is a state in which the amount of thermal energy supplied to first-stage vaporizer 31 and second-stage vaporizer 32 is balanced with the flow rate of water supplied from water pump 80 to vaporization device 30A. When this normal state is maintained, water steadily vaporizes in first-stage vaporizer 31 and second-stage vaporizer 32, and water vaporization is stable. When water vaporization is stable, pressure fluctuations in each vaporization chamber are small. This suppresses sudden pressure increases in vaporization device 30A.

[0065] When the amount of thermal energy supplied to initial heating chamber 312 and / or subsequent heating chamber 322 increases relative to the flow rate of water supplied to vaporizer 30A (for example, when the temperature of the supplied gas increases), the flow rate of water vapor generated by vaporizer 30A exceeds the flow rate of water supplied to vaporizer 30A, and the amount of water stored in vaporizer 30A decreases. As the amount of water stored in vaporizer 30A decreases, a state in which almost no water remains in subsequent vaporizer 321 is reached, as shown in FIG. 6. At this time, subsequent vaporizer 321 is heated by thermal energy supplied to subsequent heating chamber 322 from the second exhaust gas, and subsequent vaporizer 321 enters a dry-fire state. If water is supplied from initial vaporizer 311 to subsequent vaporizer 321 while subsequent vaporizer 321 is in a dry-fire state, the amount of thermal energy is excessive compared to the amount of water supplied, causing the water to evaporate all at once, resulting in a sudden rise in pressure. Such a sudden rise in pressure may cause an abnormality in the downstream cell stack 20. Therefore, the water accumulation state (dry-fired state) shown in Fig. 6 is not desirable.

[0066] Furthermore, when the water storage state is in the normal state shown in FIG. 2, if the amount of thermal energy supplied to the first-stage heating chamber 312 and / or the second-stage heating chamber 322 decreases relative to the flow rate of water supplied to the vaporizer 30A (for example, if the temperature of the supplied gas drops), the flow rate of water supplied to the vaporizer 30A exceeds the flow rate of water vapor generated by the vaporizer 30A, and the amount of water stored in the vaporizer 30A increases. As the amount of water stored in the vaporizer 30A increases, the water in the second-stage vaporizer chamber 321 eventually overflows and flows into passage R4, as shown in FIG. 7. If water flows downstream of the vaporizer 30A in this way, it may adversely affect downstream devices. Therefore, the water storage state (overflow state) shown in FIG. 7 is undesirable.

[0067] In this embodiment, control device 100 controls the flow rate of water supplied from water pump 80 to initial-stage vaporization chamber 311 by executing supply water flow rate control so that the storage state of water stored in vaporization device 30A does not transition from the normal state shown in FIG. 2 to a dry-fire state or an overflow state, i.e., so as to maintain the normal state. Specifically, control device 100 controls the flow rate of water supplied from water pump 80 to initial-stage vaporization chamber 311 based on a physical quantity correlated with the amount of thermal energy supplied from the first exhaust gas to initial-stage heating chamber 312 and a physical quantity correlated with the amount of thermal energy supplied from the second exhaust gas to subsequent-stage heating chamber 322. More specifically, control device 100 controls the flow rate of water supplied from water pump 80 to initial-stage vaporization chamber 311 based on the temperature of the first exhaust gas (first temperature T1), which is a physical quantity correlated with the amount of thermal energy supplied from the first exhaust gas to initial-stage vaporizer 31, and the temperature of the second exhaust gas (second temperature T2), which is a physical quantity correlated with the amount of thermal energy supplied from the second exhaust gas to subsequent-stage vaporizer 32. Note that the relatively higher the first temperature T1 is, the greater the amount of thermal energy supplied from the first exhaust gas to the initial stage vaporizer 31, and therefore the first temperature T1 is a physical quantity correlated with the amount of thermal energy supplied from the first exhaust gas to the initial stage vaporizer 31. Similarly, the relatively higher the second temperature T2 is, the greater the amount of thermal energy supplied from the second exhaust gas to the subsequent stage vaporizer 32, and therefore the second temperature T2 is a physical quantity correlated with the amount of thermal energy supplied from the second exhaust gas to the subsequent stage vaporizer 32.

[0068] In this case, if the amount of thermal energy supplied from the first exhaust gas to first-stage vaporizer 31 and the amount of thermal energy supplied from the second exhaust gas to second-stage vaporizer 32 are large, a dry-fire state as shown in Fig. 6 will occur unless more water is supplied to first-stage vaporization chamber 311. Therefore, control device 100 controls the flow rate of water supplied from water pump 80 to first-stage vaporization chamber 311 so that the flow rate of water supplied to first-stage vaporization chamber 311 increases as the amount of thermal energy supplied from the first exhaust gas and second exhaust gas to first-stage heating chamber 312 and second-stage heating chamber 322 increases.

[0069] Furthermore, when the amount of thermal energy supplied from the first exhaust gas to the first-stage vaporizer 31 and the amount of thermal energy supplied from the second exhaust gas to the second-stage vaporizer 32 are small, an overflow state as shown in Fig. 7 will occur unless the flow rate of water supplied to the first-stage vaporization chamber 311 is reduced. Therefore, the control device 100 controls the flow rate of water supplied from the water pump 80 to the first-stage vaporization chamber 311 so that the flow rate of water supplied to the first-stage vaporization chamber 311 decreases as the amount of thermal energy supplied from the first exhaust gas and the second exhaust gas to the first-stage heating chamber 312 and the second-stage heating chamber 322 decreases.

[0070] By executing this supply water flow rate control, it is possible to supply to vaporizer 30A an amount of water that corresponds to the amount of water vapor evaporated by the amount of thermal energy supplied to vaporizer 30A. As a result, the water storage state in vaporizer 30A can be maintained in the normal state shown in Figure 2, and the vaporization of water in each vaporizer (first-stage vaporizer 31 and second-stage vaporizer 32) can be stabilized. Therefore, water is not allowed to flow downstream of vaporizer 30A, and a sudden rise in pressure in vaporizer 30A can be prevented.

[0071] 8A and 8B are diagrams showing an example of a flowchart of a program executed by the CPU of the control device 100 so that the control device 100 can control the supply water flow rate. This program is started when the SOC system 1 is activated, and is executed repeatedly at a predetermined cycle. When this program is started, the CPU first acquires a first temperature T1, which is the temperature of the first exhaust gas supplied to the first-stage heating chamber 312, based on a temperature signal received from the first temperature sensor 71 in step (hereinafter, step numbers will be abbreviated as S) 101 of FIG. 8A. The first temperature T1 is a physical quantity correlated with the amount of thermal energy supplied from the first exhaust gas to the first-stage vaporizer 31. Next, the CPU determines whether the first temperature T1 is equal to or lower than a predetermined first upper limit temperature T1. H It is determined whether the first upper limit temperature T1 is higher than the first upper limit temperature T1 (S102). H The first upper limit temperature T1 can be, for example, a temperature in the range of 460°C to 480°C. HThe first temperature T1 can be set to, for example, 470° C. H If it is higher than (S102: Yes), the process proceeds to S104. In S104, the CPU determines that the first thermal energy amount Q1, which is the amount of thermal energy supplied from the first exhaust gas to the first-stage vaporizer 31, is large.

[0072] On the other hand, in S102, the first temperature T1 is equal to the first upper limit temperature T1 H If it is determined that the first temperature T1 is equal to or lower than the first lower limit temperature T1 (S102: No), the process proceeds to S103. L and the first upper limit temperature T1 H Determine whether the temperature is equal to or lower than the first lower limit temperature T1. L is the first upper limit temperature T1 H The first lower limit temperature T1 is predetermined as a temperature lower than the first lower limit temperature T1. L The first lower limit temperature T1 can be, for example, a temperature in the range of 420°C to 440°C. L The first temperature T1 can be set to, for example, 430° C. L and the first upper limit temperature T1 H If it is equal to or less than the first amount of thermal energy Q1 (S103: Yes), the process proceeds to S105. In S105, the CPU determines that the first amount of thermal energy Q1 is medium.

[0073] In addition, in S103, the first temperature T1 is set to the first lower limit temperature T1 L and the first upper limit temperature T1 H If it is determined that the first temperature T1 is not equal to or lower than the first lower limit temperature T1, the process proceeds to S106. L Therefore, in S106, the CPU determines that the first amount of thermal energy Q1 is small.

[0074] After the CPU determines the magnitude of the first amount of thermal energy Q1 in any of S104, S105, and S106, the process proceeds to S107. In S107, the CPU acquires a second temperature T2, which is the temperature of the second exhaust gas supplied to the rear-stage heating chamber 322, based on the temperature signal received from the second temperature sensor 72. The second temperature T2 is a physical quantity correlated with the amount of thermal energy supplied from the second exhaust gas to the rear-stage vaporizer 32. Next, the CPU determines whether the second temperature T2 is equal to or lower than a predetermined second upper limit temperature T2 H It is determined whether the second upper limit temperature T2 is higher than the second upper limit temperature T1 (S108). H The second upper limit temperature T2 can be, for example, a temperature in the range of 540°C to 560°C. H The second upper limit temperature T2 can be set to, for example, 550°C. H is the first upper limit temperature T1 H The second temperature T2 may be the same as or different from the second upper limit temperature T2 H If it is higher than Q2 (S108: Yes), the process proceeds to S110. In S110, the CPU determines that the second amount of thermal energy Q2, which is the amount of thermal energy supplied from the second exhaust gas to the rear-stage vaporizer 32, is large.

[0075] On the other hand, in S108, the second temperature T2 is equal to the second upper limit temperature T2 H If it is determined that the second temperature T2 is equal to or lower than the second lower limit temperature T2 (S108: No), the process proceeds to S109. L and the second upper limit temperature T2 H It is determined whether the temperature is equal to or lower than the second lower limit temperature T2. L is the second upper limit temperature T2 H The second lower limit temperature T2 is predetermined as a temperature lower than the second lower limit temperature T1. L The second lower limit temperature T2 can be, for example, a temperature in the range of 500°C to 520°C. L The second lower limit temperature T2 can be set to, for example, 510°C. L is the first lower limit temperature T1 L The second temperature T2 may be the same as the second lower limit temperature T2 or may be different from the second lower limit temperature T2 L and the second upper limit temperature T2H If it is equal to or less than the second amount of thermal energy Q2 (S109: Yes), the process proceeds to S111. In S111, the CPU determines that the second amount of thermal energy Q2 is medium.

[0076] In addition, in S109, the second temperature T2 is set to the second lower limit temperature T2 L and the second upper limit temperature T2 H If it is determined that the second temperature T2 is not equal to or lower than the second lower limit temperature T2, the process proceeds to S112. L Therefore, in S112, the CPU determines that the second amount of thermal energy Q2 is small.

[0077] After the CPU determines the magnitude of the second amount of thermal energy Q2 in any of S110, S111, and S112, the process proceeds to S113 in FIG. 8B. In S113, the CPU executes a process for estimating the magnitude of the total amount of thermal energy Q. The total amount of thermal energy Q is the total amount of thermal energy supplied to the vaporization device 30A. The total amount of thermal energy Q is estimated based on the magnitude of the first amount of thermal energy Q1 and the magnitude of the second amount of thermal energy Q2.

[0078] In this embodiment, an estimation table for the total thermal energy amount Q is used to estimate the magnitude of the total thermal energy amount Q. As shown in FIG. 8B , in this estimation table, the magnitude of the total energy amount Q is associated with a combination of the magnitude of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2. Therefore, the magnitude of the total thermal energy amount Q is estimated according to the combination of the magnitude of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2. Specifically, when the magnitude of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2 are both “large,” or when one of the magnitudes of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2 is “large” and the other is “medium,” the magnitude of the total thermal energy Q is estimated to be “medium.” Furthermore, when the magnitude of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2 are both “medium,” or when one of the magnitudes of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2 is “large” and the other is “small,” the magnitude of the total thermal energy Q is estimated to be “medium.” Furthermore, if the magnitude of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2 are both "small", or if one of the magnitude of the first thermal energy amount Q1 and the magnitude of the second thermal energy amount Q2 is "small" and the other is "medium", the magnitude of the total thermal energy amount Q is estimated to be "small".

[0079] After the magnitude of the total energy amount Q is estimated using the estimation table in S113, the process proceeds to S114. In S114, the CPU determines whether the magnitude of the estimated total energy amount Q is "large." If the magnitude of the total energy amount Q is "large" (S114: Yes), the process proceeds to S116. In S116, the CPU sets the flow rate F of water supplied from water pump 80 to first-stage vaporization chamber 311 to flow rate FL. Here, when the process proceeds to S116, the CPU estimates that the total thermal energy amount Q supplied to vaporization device 30A is large. If the total thermal energy amount Q is large, the amount of thermal energy supplied to vaporization device 30A is large, and therefore the amount of water vapor vaporized by vaporization device 30A is considered to be greater than the normal amount of water vapor. Therefore, the flow rate FL is predetermined to be a flow rate that is a predetermined amount greater than the normal flow rate FN corresponding to the normal amount of water vapor. Thereafter, in S119, the CPU sends a flow rate signal representing the set flow rate F (= flow rate FL) to water pump 80. As a result, the water pump 80 receives a flow rate signal representing the flow rate FL, and the supply water flow rate is adjusted so that it matches the flow rate FL. After that, the CPU temporarily ends this program.

[0080] The normal flow rate FN can be determined in advance by experiment or the like. For example, the normal flow rate FN is determined when the first temperature T1 is equal to or lower than the first lower limit temperature T1 L and the first upper limit temperature T1 H The second temperature T2 is equal to or higher than the second lower limit temperature T2 L and the second upper limit temperature T2 H When the above conditions are met, the flow rate at which the water storage state in the vaporization device 30A is maintained in a normal state can be determined in advance by experiment or the like.

[0081] Furthermore, if it is determined in S114 that the magnitude of the total energy amount Q is not "large" (S114: No), the process proceeds to S115. In S115, the CPU determines whether the magnitude of the estimated total thermal energy amount Q is "medium." If the magnitude of the total energy amount Q is "medium" (S115: Yes), the process proceeds to S117. In S117, the CPU sets the flow rate F of water supplied from water pump 80 to first-stage vaporization chamber 311 to flow rate FN. Here, if the process proceeds to S117, the CPU estimates that the total thermal energy amount Q supplied to vaporization device 30A is medium. If the total thermal energy amount Q is medium, the amount of thermal energy supplied to vaporization device 30A is medium, and therefore the amount of water vapor vaporized by vaporization device 30A is considered to be approximately a normal amount of water vapor. Therefore, in S117, the CPU sets the flow rate F of water supplied from water pump 80 to first-stage vaporization chamber 311 to the normal flow rate FN. Then, in S119, the CPU sends a flow rate signal representing the set flow rate F (=flow rate FN) to the water pump 80. As a result, the water pump 80 receives the flow rate signal representing the flow rate FN, and the supply water flow rate is adjusted so that it matches the flow rate FN. Then, the CPU temporarily terminates this program.

[0082] Furthermore, if it is determined in S115 that the magnitude of the total energy amount Q is not "medium" (S115: No), the process proceeds to S118. In S118, the CPU sets the flow rate F of water supplied from water pump 80 to first-stage vaporization chamber 311 to flow rate FS. Here, if the process proceeds to S118, the CPU estimates that the total thermal energy amount Q supplied to vaporization device 30A is small. If the total thermal energy amount Q is small, the amount of thermal energy supplied to vaporization device 30A is small, and therefore the amount of water vapor vaporized by vaporization device 30A is considered to be less than the normal amount of water vapor. Therefore, the flow rate FS is predetermined to be a flow rate that is a predetermined amount less than the normal flow rate FN. Then, in S119, the CPU sends a flow rate signal representing the set flow rate F (= flow rate FS) to water pump 80. As a result, water pump 80 receives the flow rate signal representing flow rate FS, and the supply water flow rate is adjusted so that the supply water flow rate matches flow rate FS. Then, the CPU temporarily terminates this program.

[0083] The CPU repeatedly executes the above-described program at predetermined short intervals during operation of the SOC system 1, whereby the control device 100 performs supply water flow rate control. This controls the flow rate of water supplied from the water pump 80 to the first-stage vaporization chamber 311 of the first-stage vaporizer 31 based on a first temperature T1, which is a physical quantity correlated with a first amount of thermal energy Q1 supplied from the first exhaust gas to the first-stage vaporizer 31, and a second temperature T2, which is a physical quantity correlated with a second amount of thermal energy Q2 supplied from the second exhaust gas to the post-stage vaporizer 32. FIG. 8C is a table showing the relationship between the first temperature T1 and the second temperature T2 and the water flow rate F set based on these temperatures. As shown in FIG. 8C, when the first temperature T1 is lower than the first lower-limit temperature T1, the flow rate F of water supplied from the first temperature T1 to the first lower-limit temperature T1 is controlled. L and the second temperature T2 is lower than the second upper limit temperature T2 H In the following cases, and the first temperature T1 is equal to or lower than the first lower limit temperature T1 L Above first upper limit temperature T1 H and the second temperature T2 is equal to or lower than the second lower limit temperature T2 L When the first temperature T1 is lower than the first upper limit temperature T1, the flow rate F is set to the smallest flow rate FS. H and the second temperature T2 is higher than the second lower limit temperature T2 L If the first temperature T1 is equal to or higher than the first lower limit temperature T1 L Above first upper limit temperature T1 H and the second temperature T2 is equal to or lower than the second upper limit temperature T2 H If the first temperature T1 and the second temperature T2 are higher than the first lower limit temperature T1, the flow rate F is set to the largest flow rate FL. L Above first upper limit temperature T1 H and the second temperature is equal to or lower than the second lower limit temperature T2 L Second upper limit temperature T2 H In the following cases, and the first temperature T1 is equal to or lower than the first lower limit temperature T1 L and the second temperature T2 is lower than the second upper limit temperature T2 H and when the first temperature T1 is higher than the first upper limit temperature T1 H and the second temperature T2 is higher than the second lower limit temperature T2 LIf the flow rate F is less than 100%, the flow rate F is set to a medium flow rate FN.

[0084] According to this control, water pump 80 is controlled so that the greater the total amount of thermal energy Q supplied to vaporizer 30A from the first exhaust gas and the second exhaust gas, the greater the flow rate of water supplied from water pump 80 to initial vaporization chamber 311; conversely, the smaller the total amount of thermal energy Q, the smaller the flow rate of water supplied from water pump 80 to initial vaporization chamber 311. Therefore, water is supplied to vaporizer 30A at an appropriate flow rate corresponding to the amount of water vapor vaporized when the total amount of thermal energy supplied to each heating chamber of vaporizer 30A is supplied. As a result, the water storage state in vaporizer 30A is maintained in the normal state shown in FIG. 2, preventing the dry-fire state shown in FIG. 6 or the overflow state shown in FIG. 7. This stabilizes the vaporization of water in vaporizer 30A, thereby preventing a sudden rise in pressure due to rapid water vaporization in vaporizer 30A.

[0085] (Variation 1) In the first embodiment described above, an example was shown in which the magnitude of the total amount of thermal energy Q was estimated based on the first temperature T1 and the second temperature T2, and the flow rate F of water supplied from the water pump 80 to the first-stage vaporization chamber 311 was set in accordance with the magnitude of the estimated total amount of thermal energy Q. However, if the CPU of the control device 100 stores the table shown in FIG. 8C , the estimation of the magnitude of the total amount of thermal energy Q can be omitted. In this case, the CPU of the control device 100 can obtain the first temperature T1 and the second temperature T2, and directly set the flow rate F by applying the obtained first temperature T1 and second temperature T2 to the table shown in FIG. 8C .

[0086] (Variation 2) In the first embodiment described above, an example was shown in which, when the control device 100 executes the supply water flow rate control, the CPU executes the programs shown in Figures 8A and 8B. In this example, an example will be described in which, when the control device 100 executes the supply water flow rate control, the CPU executes the program shown in Figure 9.

[0087] 9 is started, the CPU first acquires a first temperature T1, which is the temperature of the first exhaust gas supplied to the first-stage heating chamber 312, based on the temperature signal received from the first temperature sensor 71 in S201 of FIG. 9. Next, the CPU calculates a first amount of thermal energy Q1, which is the amount of thermal energy supplied from the first exhaust gas to the first-stage heating chamber 312 (S202). The first amount of thermal energy Q1 [J / sec.] can be calculated using the following equation (1) based on the first temperature T1 [K], the specific heat C1 [J / g K] and mass flow rate M1 [g / sec.] of the first exhaust gas, and the temperature T1' [K] of the first exhaust gas discharged from the first-stage heating chamber 312. (1) Q1 = M1 × C1 × (T1 - T1')

[0088] Next, the CPU acquires a second temperature T2, which is the temperature of the second exhaust gas supplied to the rear-stage heating chamber 322 (S203). After that, the CPU calculates a second amount of thermal energy Q2, which is the amount of thermal energy supplied from the second exhaust gas to the rear-stage heating chamber 322 (S204). The second thermal energy Q2 [J / sec.] can be calculated based on the second temperature T2 [K], the specific heat C2 [J / g K] and mass flow rate M2 [g / sec.] of the second exhaust gas, and the temperature T2' [K] of the second exhaust gas discharged from the rear-stage heating chamber 322, using the following equation (2): (2) Q2 = M2 × C2 × (T2 - T2')

[0089] Next, the CPU calculates the total amount of thermal energy Q supplied to the vaporizer 30A based on the first amount of thermal energy Q1 and the second amount of thermal energy Q2 (S205). The total amount of thermal energy Q can be calculated as the amount of heat (heat flow rate) flowing into the vaporizer 30A per unit time, for example, using the following equation (3): (3) Q = Q1 × η1 + Q2 × η2 Here, η1 is the thermal conversion efficiency indicating the proportion of the first thermal energy Q1 supplied to the first-stage heating chamber 312 that is transferred to the first-stage evaporation chamber 311, and η2 is the thermal conversion efficiency indicating the proportion of the second thermal energy Q2 supplied to the second-stage heating chamber 322 that is transferred to the second-stage evaporation chamber 321.

[0090] Next, the CPU calculates a predicted water vapor flow rate V (S206). The predicted water vapor flow rate V is a predicted value of the mass of water vapor that evaporates per unit time when total thermal energy Q is applied to the water in vaporizer 30A. The predicted water vapor flow rate V [g / sec.] can be calculated based on the total thermal energy Q [J / sec.], the specific heat of water Cp [J / g K], the temperature difference ΔT [K] between the temperature of water supplied to vaporizer 30A (input temperature) and the temperature at which the water evaporates, the heat of vaporization qw [J / g] of water, etc. The predicted water vapor flow rate V can be calculated using, for example, the following equation (4): (4)V [g / sec.] = Q / (Cp × ΔT + qw)

[0091] Next, the CPU sets the predicted water vapor flow rate V to the target flow rate Ft (S207). The target flow rate Ft [g / sec.] is the amount of water vapor (gas) that has turned into water (liquid) corresponding to the predicted water vapor flow rate V [g / sec.].

[0092] Next, the CPU outputs a flow rate signal representing the set target flow rate Ft to the water pump 80 (S208). This causes the water pump 80 to control the supply water flow rate so that the supply water flow rate matches the target flow rate Ft. Thereafter, the CPU temporarily terminates this program.

[0093] The CPU repeatedly executes the above-described program at predetermined short intervals, causing control device 100 to control the supply water flow rate. This directly calculates the amount of thermal energy to be supplied to each heating chamber (first-stage heating chamber 312 and second-stage heating chamber 322) of vaporizer 30A, and water at a flow rate that can be evaporated with the calculated amount of thermal energy is supplied from water pump 80 to first-stage vaporization chamber 311 of vaporizer 30A. This stabilizes the vaporization of water in vaporizer 30A, thereby preventing a sudden rise in pressure due to rapid water vaporization in vaporizer 30A.

[0094] Second Embodiment 10 is a block diagram of an SOC system 2 according to the second embodiment. Like the SOC system 1 according to the first embodiment, the SOC system 2 is a hydrogen production system (SOEC system). The configuration of the SOC system 2 is similar to that of the SOC system 1. Therefore, the same components as those in the SOC system 1 are denoted by the same reference numerals and their description will be omitted. The following describes the differences.

[0095] 10, the SOC system 2 includes a burner device 60 as a heat source device. The burner device 60 is configured to heat the second exhaust gas that flows through the passage R10 and is supplied to the post-heating chamber 322. The burner device 60 is electrically connected to the control device 100, and the operation of the burner device 60 is controlled by the control device 100. The other configurations are the same as those of the SOC system 1 according to the first embodiment.

[0096] The control device 100 of the SOC system 2 configured as described above controls the supply water flow rate, similar to the control device 100 of the SOC system 1 according to the first embodiment. At this time, the CPU of the control device 100 can execute the programs shown in Figures 8A and 8B. This stabilizes the vaporization of water in the vaporizer 30A, thereby preventing a sudden rise in pressure due to rapid vaporization of water in the vaporizer 30A.

[0097] Furthermore, the control device 100 executes thermal energy control in parallel with the supply water flow rate control. This thermal energy control activates (ignites) the burner device 60 as needed. By the control device 100 executing thermal energy control, the vaporizer 30A can generate steam more efficiently.

[0098] 11 is a flowchart showing an example of a program executed by the CPU of the control device 100 in order for the control device 100 to perform heat flow control. This program is started when the SOC system 2 is activated. When this program is started, the CPU first acquires a first temperature T1, which is the temperature of the first exhaust gas supplied to the initial heating chamber 312, based on a temperature signal received from the first temperature sensor 71 in S301 of FIG. 10. Next, the CPU acquires a second temperature T2, which is the temperature of the second exhaust gas supplied to the subsequent heating chamber 322, based on a temperature signal received from the second temperature sensor 72 (S302).

[0099] Next, the CPU calculates the temperature difference ΔT (=T2-T1) by subtracting the first temperature T1 from the second temperature T2 (S303). Next, the CPU determines whether the temperature difference ΔT is equal to or greater than a predetermined threshold value α (S304). The threshold value α is set in advance. The threshold value α is set to a positive number. If the temperature difference ΔT is equal to or greater than the threshold value α (S304: Yes), the process proceeds to S305. On the other hand, if the temperature difference ΔT is less than the threshold value α (S304: No), the process proceeds to S306.

[0100] In S305, the CPU controls the burner device 60 so that the burner device 60 is in a non-ignited state (OFF). If the burner device 60 is already in a non-ignited state, that state is maintained. After that, the CPU temporarily ends this program.

[0101] In S306, the CPU controls the burner device 60 so that the burner device 60 is in an ignition state (ON). In this case, the CPU may control the burner device 60 in S306 so that the burner device 60 maintains the ignition state for a predetermined time, and then switches to a non-ignition state. By the processing of S306, the second exhaust gas supplied from the passage R10 to the post-heating chamber 322 is heated by the burner device 60. Thereafter, the CPU temporarily terminates this program.

[0102] 11 repeatedly at predetermined short intervals, the control device 100 performs thermal energy control. When the control device 100 performs thermal energy control, the second exhaust gas supplied to the rear-stage heating chamber 322 is heated by the burner device 60 when the second temperature T2 is lower than the temperature obtained by adding the threshold value α to the first temperature T1. This controls the thermal energy (second temperature T2) of the second exhaust gas so that the temperature (second temperature T2) of the second exhaust gas supplied to the rear-stage heating chamber 322 is always higher than the temperature (first temperature T1) of the first exhaust gas supplied to the initial-stage heating chamber 312.

[0103] When such thermal energy control is performed, the water vapor vaporized in the first-stage vaporization chamber 311 can be further heated in the second-stage vaporization chamber 321. This can improve the heat conversion efficiency.

[0104] In the present embodiment, the thermal energy supplied to the vaporizer 30A is controlled so that the second temperature T2 exceeds the first temperature T1. However, the thermal energy control is not necessarily limited to this control. For example, the control device 100 may control the burner device 60 to heat the second exhaust gas supplied to the rear-stage heating chamber 322 so that the temperature in the rear-stage vaporization chamber 321 is a temperature at which condensation does not occur in the rear-stage vaporization chamber 321. In this case, the second temperature T2 may be lower than the first temperature T1. Furthermore, if a temperature at which vaporization is possible in the rear-stage vaporizer 32 is set in advance, the control device 100 may control the burner device 60 to heat the second exhaust gas when the second temperature T2 is lower than the set temperature. Furthermore, if the amount of water vapor vaporized in the vaporizer 30A is set in advance, the control device 100 may control the burner device 60 so that the amount of water vapor vaporized in the vaporizer 30 does not fall below the set amount of water vapor. In this case, when the amount of water vapor that can be vaporized in the vaporization device 30A calculated from the first temperature T1 and the second temperature T2 is about to fall below the set amount of water vapor, the control device 100 may heat the second exhaust gas using the burner device 60 and control the burner device 60 so that the amount of water vapor is always equal to or greater than the set amount of water vapor.

[0105] (Third embodiment) FIG. 12 is a block diagram of an SOC system 3 according to a third embodiment. Like the SOC system 1 according to the first embodiment, the SOC system 3 is a hydrogen production system (SOEC system). While the SOC system 1 shown in FIG. 1 and the SOC system 2 shown in FIG. 10 show examples in which multiple vaporizers (first-stage vaporizer 31 and second-stage vaporizer 32) constituting the vaporization device 30A are connected in series, the SOC system 3 according to this embodiment differs from the SOC systems 1 and 2 in that multiple vaporizers (first vaporizer 33 and second vaporizer 34) constituting the vaporization device 30B are connected in parallel. The following describes the SOC system 3, focusing on the differences.

[0106] 12, the SOC system 3 includes a hot module 10, a first water pump 81, a second water pump 82, a condenser 90, a control device 100, and a plurality of paths. The paths include a path R1, a path R21, a path R22, a path R31, a path R32, a path R41, a path R42, a path R5, a path R6, a path R7, a path R8, a path R9, a path R10, and a path R11.

[0107] Passage R1 is connected to a water source. Passage R1 branches into passages R21 and R22. A first water pump 81 is connected to passage R21, and a second water pump 82 is connected to passage R22. The first water pump 81 and the second water pump 82 each have an intake port and a discharge port, with the intake port of the first water pump 81 connected to passage R21 and the intake port of the second water pump 82 connected to passage R22. Therefore, water from the water source flows through passage R1 into passages R21 and R22, and is then supplied from passage R21 to the first water pump 81 and from passage R22 to the second water pump 82.

[0108] First water pump 81 and second water pump 82 draw water from their suction ports and deliver the drawn water to their discharge ports. The discharge port of first water pump 81 is connected to first vaporizer 33 of vaporization device 30B (described later) via passage R31, and the discharge port of second water pump 82 is connected to second vaporizer 34 of vaporization device 30B via passage R32. First water pump 81 is configured to adjust the flow rate of water delivered from its discharge port to first vaporizer 33, and second water pump 82 is configured to adjust the flow rate of water delivered from its discharge port to second vaporizer 34. Therefore, first water pump 81 and second water pump 82 are water supply devices that supply water to vaporization device 30B and can adjust the flow rate of the supplied water.

[0109] The hot module 10 includes a cell stack 20, a vaporizer 30B, a heating device 40, and a heat insulator 50. The configurations of the cell stack 20, the heating device 40, and the heat insulator 50 are the same as those of the cell stack 20, the heating device 40, and the heat insulator 50 of the SOC system 1 according to the first embodiment, and therefore detailed description thereof will be omitted.

[0110] The vaporization device 30B includes a first vaporizer 33 and a second vaporizer 34. As described above, the first vaporizer 33 is connected to the first water pump 81 via the passage R31, and the second vaporizer 34 is connected to the second water pump 82 via the passage R32. As can be seen from Fig. 12, the first vaporizer 33 and the second vaporizer 34 are connected in parallel to each other by the passages R31 and R32.

[0111] The first vaporizer 33 has a first vaporization chamber 331 and a first heating chamber 332. The second vaporizer 34 has a second vaporization chamber 341 and a second heating chamber 342. A passage R31 is connected to the first vaporization chamber 331 of the first vaporizer 33, and a passage R32 is connected to the second vaporization chamber 341 of the second vaporizer 34. Therefore, the first water pump 81 supplies water to the first vaporization chamber 331 of the first vaporizer 33 via the passage R31, and the second water pump 82 supplies water to the second vaporization chamber 341 of the second vaporizer 34 via the passage R32. Each vaporization chamber (the first vaporization chamber 331 and the second vaporization chamber 341) is configured to store the supplied water.

[0112] First heating chamber 332 is disposed adjacent to first vaporization chamber 331. Specifically, first heating chamber 332 is disposed adjacent to first vaporization chamber 331 so as to be in contact with the portion of first vaporization chamber 331 where water is stored. High-temperature first exhaust gas discharged from cell stack 20 is supplied to first heating chamber 332 via passage R6. Therefore, thermal energy of the first exhaust gas is supplied to first vaporization chamber 331. The water stored in first vaporization chamber 331 is heated by the thermal energy of the high-temperature first exhaust gas supplied to first heating chamber 332, and is thereby vaporized.

[0113] The second heating chamber 342 is disposed adjacent to the second vaporization chamber 341. Specifically, the second heating chamber 342 is disposed adjacent to the second vaporization chamber 341 so as to be in contact with the portion of the second vaporization chamber 341 where water is stored. The high-temperature second exhaust gas discharged from the cell stack 20 is supplied to the second heating chamber 342 via the passage R10. Therefore, the thermal energy of the second exhaust gas is supplied to the second vaporization chamber 341. The water stored in the second vaporization chamber 341 is heated by the thermal energy of the high-temperature second exhaust gas supplied to the second heating chamber 342, and is thereby vaporized.

[0114] The water vapor generated by vaporizing the water stored in first vaporization chamber 331 is supplied to temperature raising device 40 via passage R41. The water vapor generated by vaporizing the water stored in second vaporization chamber 341 is supplied to temperature raising device 40 via passage R42. In FIG. 12, passages R41 and R42 merge midway to form a single passage, and this single passage is connected to temperature raising device 40.

[0115] Water vapor is supplied to the temperature raising device 40 from the vaporizer 30B via passages R41 and R42, and air is also supplied via passage R8. The temperature raising device 40 raises the temperature of the supplied water vapor and air to the operating temperature of the cell stack 20 (i.e., the temperature required to operate the cell stack 20).

[0116] Water vapor heated to the operating temperature by the temperature raising device 40 is introduced into the cell stack 20 via passage R5. Air heated to the operating temperature by the temperature raising device 40 is introduced into the cell stack 20 via passage R9. The water vapor introduced into the cell stack 20 is electrolyzed by a water vapor electrolysis reaction, thereby producing hydrogen (first gas) and oxygen (second gas). A high-temperature first exhaust gas (hydrogen and water vapor) containing hydrogen and water vapor, and a high-temperature second exhaust gas (oxygen and air) containing oxygen and air are then discharged from the cell stack 20.

[0117] The high-temperature first exhaust gas discharged from cell stack 20 is introduced into temperature raising device 40 via passage R6, where it is used to heat the water vapor and air supplied from vaporization device 30B to temperature raising device 40, and then supplied to first heating chamber 332 of first vaporizer 33. The thermal energy of the first exhaust gas supplied to first heating chamber 332 heats and vaporizes the water in first vaporization chamber 331. The first exhaust gas that has heated the water in first vaporization chamber 331 is then introduced from first heating chamber 332 into condenser 90 via passage R7. Water vapor is condensed in condenser 90. The condensed water produced in condenser 90 is supplied to passage R1. Meanwhile, hydrogen separated by condensation of the water vapor in condenser 90 is recovered.

[0118] Furthermore, the high-temperature second exhaust gas discharged from the cell stack 20 is introduced into the temperature raising device 40 via the passage R10, where it is used to heat the water vapor and air, and is then supplied to the second heating chamber 342 of the second vaporizer 34. The water in the second vaporization chamber 341 is heated and vaporized by the thermal energy of the second exhaust gas supplied to the second heating chamber 342. The second exhaust gas that has heated the water in the second vaporization chamber 341 then flows from the second heating chamber 342 to the passage R11 and is recovered (or released to the atmosphere).

[0119] 12 , the first temperature sensor 71 is attached to the passage R6. The first temperature sensor 71 is attached to a position in the passage R6 close to the first heating chamber 332. The first temperature sensor 71 detects a first temperature T1, which is the temperature of the first exhaust gas supplied from the passage R6 to the first heating chamber 332, and transmits a temperature signal indicating the detected first temperature T1 to the control device 100.

[0120] The second temperature sensor 72 is attached to the passage R10. The second temperature sensor 72 is attached to a position in the passage R10 close to the second heating chamber 342. The second temperature sensor 72 detects a second temperature T2, which is the temperature of the second exhaust gas supplied from the passage R10 to the second heating chamber 342, and transmits a temperature signal representing the detected second temperature T2 to the control device 100.

[0121] The control device 100 controls the operating state of the SOC system 3. The control device 100 mainly comprises a microcomputer including a CPU, ROM, and RAM. The ROM of the control device 100 stores a program for controlling the operating state of the SOC system 1. The CPU of the control device 100 reads the program from the ROM, expands it into the RAM, and executes it.

[0122] Furthermore, during operation of SOC system 3, control device 100 sequentially receives temperature signals from first temperature sensor 71 and second temperature sensor 72. Furthermore, control device 100 executes supply water flow rate control during operation of SOC system 3. The supply water flow rate control controls the flow rate of water supplied from first water pump 81 to first vaporization chamber 331 of vaporization device 30B and the flow rate of water supplied from second water pump 82 to second vaporization chamber 341 of vaporization device 30B.

[0123] 13 is a diagram showing an example of a flowchart of a program executed by the CPU of the control device 100 in order for the control device 100 according to this embodiment to execute supply water flow rate control. This program is started when the SOC system 3 is activated. When this program is started, the CPU first acquires a first temperature T1, which is the temperature of the first exhaust gas supplied to the first heating chamber 332, based on a temperature signal received from the first temperature sensor 71, in S401 of FIG. 13. Next, the CPU calculates whether the first temperature T1 is equal to or lower than a predetermined first upper limit temperature T1. H (S402) H is the first upper limit temperature T1 shown in the first embodiment. H The first temperature T1 may be the same as or different from the first upper limit temperature T1 H If it is higher than (S402: Yes), the process proceeds to S404. In S404, the CPU determines that the first thermal energy amount Q1, which is the thermal energy supplied from the first exhaust gas to the first heating chamber 332, is large. Next, the process proceeds to S407. Note that if the determination result in S402 is Yes, the process of S404 may be omitted and the process may proceed to S407.

[0124] In S407, the CPU sets the flow rate F1 of water supplied from first water pump 81 to first vaporization chamber 331 to flow rate FL1. If the process proceeds to S407, the CPU has determined that the first amount of thermal energy Q1 is large. If the first amount of thermal energy Q1 is large, the amount of thermal energy supplied to first vaporizer 33 is large, and therefore the amount of water vapor vaporized in first vaporizer 33 is considered to be greater than the normal amount of water vapor. Therefore, flow rate FL1 is predetermined as a flow rate that is a predetermined amount greater than the normal flow rate FN1 corresponding to the normal amount of water vapor.

[0125] On the other hand, in S402, the first temperature T1 is equal to the first upper limit temperature T1 H If it is determined that the first temperature T1 is equal to or lower than the first lower limit temperature T1 (S402: No), the process proceeds to S403. L and the first upper limit temperature T1 H Determine whether the temperature is equal to or lower than the first lower limit temperature T1.L is the first upper limit temperature T1 H The first lower limit temperature T1 is predetermined as a temperature lower than the first lower limit temperature T1. L is the first lower limit temperature T1 shown in the first embodiment. L The first temperature T1 may be the same as the first lower limit temperature T1 or may be a different temperature. L and the first upper limit temperature T1 H If it is equal to or less than this (S403: Yes), the process proceeds to S405. In S405, the CPU determines that the first thermal energy amount Q1 is medium. Then, the process proceeds to S408. Note that if the determination result in S403 is Yes, the process of S405 may be omitted and the process may proceed to S408.

[0126] In S408, the CPU sets the flow rate F1 to a flow rate FN1. Here, when the process proceeds to S408, the CPU has determined that the first amount of thermal energy Q1 is medium. When the first amount of thermal energy Q1 is medium, the amount of thermal energy supplied to the first vaporizer 33 is medium, and therefore the amount of water vapor vaporized in the first vaporizer 33 is considered to be approximately a normal amount of water vapor. Therefore, the flow rate FN1 is predetermined as a flow rate corresponding to a normal amount of water vapor. Note that the normal flow rate FN1 can be determined in advance by experiment or the like, as described in the first embodiment above.

[0127] In addition, in S403, the first temperature T1 is the first lower limit temperature T1 L and the first upper limit temperature T1 H If it is determined that the first temperature T1 is not equal to or lower than the first lower limit temperature T1 (S403: No), the process proceeds to S406. L This is the case when the first amount of thermal energy Q1 is less than the predetermined value. Therefore, in S406, the CPU determines that the first amount of thermal energy Q1 is small. Next, the process proceeds to S409. Note that if the determination result in S403 is No, the process of S406 may be omitted and the process may proceed to S409.

[0128] In S409, the CPU sets the flow rate F1 to a flow rate FS1. Here, when the process proceeds to S409, the CPU determines that the first amount of thermal energy Q1 is small. When the first amount of thermal energy Q1 is small, the amount of thermal energy supplied to the first vaporizer 33 is small, and therefore the amount of water vapor vaporized in the first vaporizer 33 is considered to be less than the normal amount of water vapor. Therefore, the flow rate FS1 is predetermined as a flow rate that is a predetermined amount less than the normal flow rate FN1 corresponding to the normal amount of water vapor.

[0129] After the CPU sets the flow rate F1 to one of FL1, FN1, or FS1 in either S407, S408, or S409, the process proceeds to S410. In S410, the CPU sends a flow rate signal representing the set flow rate F1 to the first water pump 81. As a result, the first water pump 81 receives the flow rate signal representing the flow rate F1, and the supply water flow rate of the first water pump 81 is adjusted so that the supply water flow rate matches the flow rate F1.

[0130] Next, in S411, the CPU acquires a second temperature T2, which is the temperature of the second exhaust gas supplied to the second heating chamber 342, based on the temperature signal received from the second temperature sensor 72. Next, the CPU determines whether the second temperature T2 is equal to or lower than a predetermined second upper limit temperature T2 H (S412) H is the second upper limit temperature T2 shown in the first embodiment. H The second temperature T2 may be the same as or different from the second upper limit temperature T2 H If it is higher than (S412: Yes), the process proceeds to S414. In S414, the CPU determines that the magnitude of the second thermal energy Q2, which is the thermal energy supplied from the second exhaust gas to the second heating chamber 342, is large. Next, the process proceeds to S417. Note that if the determination result in S412 is Yes, the process of S414 may be omitted and the process may proceed to S417.

[0131] In S417, the CPU sets the flow rate F2 of water supplied from the second water pump 82 to the second vaporization chamber 341 to a flow rate FL2. If the process proceeds to S417, the CPU has determined that the second amount of thermal energy Q2 is large. If the second amount of thermal energy Q2 is large, the amount of thermal energy supplied to the second vaporizer 34 is large, and therefore the amount of water vapor vaporized in the second vaporizer 34 is considered to be greater than the normal amount of water vapor. Therefore, the flow rate FL2 is predetermined to be a flow rate that is a predetermined amount greater than the normal flow rate FN2 corresponding to the normal amount of water vapor.

[0132] On the other hand, in S412, the second temperature T2 is equal to or lower than the second upper limit temperature T2 H If it is determined that the second temperature T2 is equal to or lower than the second lower limit temperature T2 (S412: No), the process proceeds to S413. L and the second upper limit temperature T2 H It is determined whether the temperature is equal to or lower than the second lower limit temperature T2. L is the second upper limit temperature T2 H The second lower limit temperature T2 is predetermined as a temperature lower than the second lower limit temperature T1. L is the second lower limit temperature T2 shown in the first embodiment. L The second temperature T2 may be the same as or different from the second lower limit temperature T2 L and the second upper limit temperature T2 H If it is equal to or less than this (S413: Yes), the process proceeds to S415. In S415, the CPU determines that the magnitude of the second thermal energy Q2 is medium. Next, the process proceeds to S418. Note that if the determination result in S413 is Yes, the process of S415 may be omitted and the process may proceed to S418.

[0133] In S418, the CPU sets the flow rate F2 to the flow rate FN2. Here, when the process proceeds to S418, the CPU has determined that the second amount of thermal energy Q2 is medium. When the second amount of thermal energy Q2 is medium, the amount of thermal energy supplied to the second vaporizer 34 is medium, and therefore the amount of water vapor vaporized in the second vaporizer 34 is considered to be about a normal amount of water vapor. Therefore, the flow rate FN2 is predetermined as a flow rate corresponding to a normal amount of water vapor. Note that the normal flow rate FN2 can be determined in advance by experiment or the like, as described in the first embodiment above.

[0134] In addition, in S413, the second temperature T2 is set to the second lower limit temperature T2 L and the second upper limit temperature T2 H If it is determined that the second temperature T2 is not equal to or lower than the second lower limit temperature T2 (S413: No), the process proceeds to S416. L This is the case when the second amount of thermal energy Q2 is less than the predetermined value. Therefore, in S416, the CPU determines that the second amount of thermal energy Q2 is small. Next, the process proceeds to S419. Note that if the determination result in S413 is No, the process of S416 may be omitted and the process may proceed to S419.

[0135] In S419, the CPU sets the flow rate F2 to the flow rate FS2. Here, when the process proceeds to S419, the CPU has determined that the second amount of thermal energy Q2 is small. When the second amount of thermal energy Q2 is small, the amount of thermal energy supplied to the second vaporizer 34 is small, and therefore the amount of water vapor vaporized in the second vaporizer 34 is considered to be less than the normal amount of water vapor. Therefore, the flow rate FS2 is predetermined as a flow rate that is a predetermined amount less than the normal flow rate FN2 corresponding to the normal amount of water vapor.

[0136] After the CPU sets the flow rate F2 to one of FL2, FN2, or FS2 in either S417, S418, or S419, the process proceeds to S420. In S420, the CPU sends a flow rate signal representing the set flow rate F2 to the second water pump 82. As a result, the second water pump 82 receives the flow rate signal representing the flow rate F2, and the supply water flow rate of the second water pump 82 is adjusted so that the supply water flow rate matches the flow rate F2. After executing the process of S420, the CPU temporarily terminates this program.

[0137] The CPU repeatedly executes the above-described program at predetermined short intervals, causing the control device 100 to perform supply water flow rate control. This supply water flow rate control controls the flow rate of water supplied from the first water pump 81 to the first vaporization chamber 331 based on the temperature (first temperature T1) of the first exhaust gas supplied to the first heating chamber 332, and controls the flow rate of water supplied from the second water pump 82 to the second vaporization chamber 341 based on the temperature (second temperature T2) of the second exhaust gas supplied to the second heating chamber 342. This allows water to be supplied to each vaporization chamber (first vaporization chamber 331 and second vaporization chamber 341) of each vaporizer (first vaporizer 33 and second vaporizer 34) at a flow rate appropriate for the amount of thermal energy supplied to each heating chamber (first heating chamber 332 and second heating chamber 342) of each vaporizer (first vaporizer 33 and second vaporizer 34). This allows each vaporizer to stably generate water vapor, thereby preventing a sudden rise in pressure due to rapid water evaporation in the vaporization device 30B.

[0138] Furthermore, according to this embodiment, the flow rate of water supplied to each vaporizer connected in parallel can be individually controlled, so that the water can be supplied at an optimal flow rate that matches the amount of thermal energy supplied to each vaporizer, thereby enabling more stable generation of water vapor in vaporizer 30B.

[0139] Although the embodiments of the present disclosure have been described above, the technology according to the present disclosure is not limited to the above embodiments. For example, while the first embodiment described above illustrates a configuration in which the vaporizers are connected in series in two stages, the vaporizer may include three or more vaporizers connected in series in three or more stages. In this case, the gas discharged from the cell stack can be diverted to supply the gas discharged from the cell stack to all of the vaporizers. Furthermore, in addition to the gas discharged from the cell stack, an external heat source may be used to supply thermal energy to all of the vaporizers. Furthermore, while the first embodiment described an example in which a gas containing hydrogen and water vapor is supplied to the first-stage vaporizer 31 and a gas containing oxygen and air is supplied to the second-stage vaporizer 32, a gas containing oxygen and air may be supplied to the first-stage vaporizer 31 and a gas containing hydrogen and water vapor may be supplied to the second-stage vaporizer 32. In this case, the condenser 90 is provided on the second-stage vaporizer 32 side.

[0140] In the first embodiment, the temperature of the first exhaust gas (first temperature T1) supplied to the initial heating chamber 312 and the temperature of the second exhaust gas (second temperature T2) supplied to the subsequent heating chamber 322 are each divided into three stages, and the flow rate F of the water pump 80 is set based on the combination of the divided temperatures. However, the temperature of the exhaust gas may be divided into two stages or four or more stages. In the first embodiment, the amount of thermal energy (Q1, Q2) supplied to each vaporizer is divided into three patterns: large, medium, and small. However, the amount of thermal energy may be further divided into four or more patterns. Furthermore, the magnitude of the amount of thermal energy supplied to the vaporization device 30A may be quantified, and the flow rate F of the water pump 80 may be set based on the numerical value. Alternatively, a balance between the first amount of thermal energy Q1 and the second amount of thermal energy Q2 may be achieved and reflected in the control.

[0141] Furthermore, in the second embodiment, an example was shown in which the burner device 60 serving as the heat source device was configured to heat the gas supplied to the rear-stage vaporizer 32. However, the heat source device may also be configured to heat the gas supplied to the initial-stage vaporizer 31. Furthermore, a heat source device for heating the gas supplied to the initial-stage vaporizer 31 and a heat source device for heating the gas supplied to the rear-stage vaporizer 32 may be separately provided. In this case, the control device can control (e.g., heat) the amount of thermal energy of the first exhaust gas and the second exhaust gas that can be controlled by the heat source device based on either or both of a physical quantity correlated with the amount of thermal energy supplied from the first exhaust gas to the initial-stage heating chamber (e.g., the temperature of the first exhaust gas (first temperature T1)) and a physical quantity correlated with the amount of thermal energy supplied from the second exhaust gas to the rear-stage heating chamber (e.g., the temperature of the second exhaust gas (second temperature T2)). For example, the control device can execute control to operate the heat source device so as to suppress temperature fluctuations in a vaporizer in which the temperature fluctuations of the supplied gas are large.

[0142] In addition, while the third embodiment has been described as an example in which the vaporizers are connected in parallel, the number of vaporizers connected in parallel may be three or more. A heat source device may be provided to heat the gas supplied to one or more of the vaporizers connected in parallel. In this case, for example, the control device may execute control to operate the heat source device so as to suppress temperature fluctuations in a vaporizer that has large fluctuations in the temperature of the gas supplied thereto.

[0143] In addition, in the above embodiments, the temperature of the gas (first exhaust gas and second exhaust gas) supplied to the vaporizer is shown as the physical quantity correlated with the amount of thermal energy supplied to the vaporizer, but the physical quantity correlated with the amount of thermal energy may be something other than temperature. For example, in a case where water is vaporized by attaching an electric heater to the vaporizer, the physical quantity correlated with the thermal energy supplied to the vaporizer may be the current value of the electric heater.

[0144] In addition, in each of the above embodiments, a hydrogen production system (SOEC system) that produces hydrogen has been exemplified as an SOC system, but the technology according to the present disclosure can also be applied to a gas production system that produces hydrogen and / or other gases (e.g., hydrocarbon gas). Furthermore, the technology according to the present disclosure can also be applied to an SOFC system or an r-SOC system that has a vaporizer that generates water vapor. In this way, the technology according to the present disclosure can be modified without departing from the spirit thereof.

[0145] Furthermore, the present disclosure may include the following aspects. [1] a water supply device capable of adjusting the flow rate of supplied water; a vaporizer that generates water vapor by vaporizing the water supplied from the water supply device; a reactor to which the water vapor generated in the vaporizer is supplied, which generates a first gas and a second gas by a chemical reaction using the supplied water vapor, and which discharges a first exhaust gas containing the generated first gas and a second exhaust gas containing the generated second gas; a control device for controlling the evaporation of water in the evaporation device; A SOC system comprising: the vaporization device has a plurality of vaporizers; Each of the plurality of vaporizers is supplied with water and thermal energy for heating the supplied water, the control device controls the flow rate of water supplied from the water supply device to the vaporizer based on a physical quantity correlated with the amount of thermal energy supplied to the plurality of vaporizers. SOC system. [2] [1] The SOC system according to [1], the plurality of vaporizers are connected in series; the water supply device is connected to a first-stage vaporizer that is the most upstream vaporizer among the plurality of vaporizers connected in series so as to supply water to the first-stage vaporizer; the control device controls the flow rate of water supplied from the water supply device to the first-stage vaporizer based on a physical quantity correlated with the amount of thermal energy supplied to the plurality of vaporizers. SOC system. [3] [2] The SOC system according to [2], the control device controls the flow rate of water supplied from the water supply device to the first-stage vaporizer so that the flow rate of water supplied to the first-stage vaporizer increases as the amount of thermal energy supplied to the plurality of vaporizers increases. SOC system. [4] [2] or [3], the SOC system according to the plurality of carburetors include the first-stage carburetor and one rear-stage carburetor arranged downstream of the first-stage carburetor, the first-stage vaporizer includes a first-stage vaporization chamber to which water is supplied from the water supply device, and a first-stage heating chamber disposed adjacent to the first-stage vaporization chamber to which the first exhaust gas discharged from the reaction device is supplied, the post-vaporizer includes a post-vaporization chamber to which water is supplied from the first-stage vaporization chamber, and a post-heating chamber disposed adjacent to the post-vaporization chamber and to which the second exhaust gas discharged from the reaction device is supplied, the latter-stage vaporization chamber is connected in series downstream of the former-stage vaporization chamber; the control device controls the flow rate of water supplied from the water supply device to the first-stage vaporization chamber based on the temperature of the first exhaust gas supplied to the first-stage heating chamber and the temperature of the second exhaust gas supplied to the second-stage heating chamber. SOC system. [5] [4] The SOC system according to [4], a heat source device for supplying thermal energy to either or both of the first exhaust gas supplied to the initial-stage heating chamber and the second exhaust gas supplied to the subsequent-stage heating chamber; the control device controls either or both of the amount of thermal energy supplied from the heat source device to the first exhaust gas and the amount of thermal energy supplied from the heat source device to the second exhaust gas, based on either or both of the temperature of the first exhaust gas supplied to the initial heating chamber and the temperature of the second exhaust gas supplied to the subsequent heating chamber. SOC system. [6] [5] The SOC system according to [5], the heat source device is configured to heat the second exhaust gas supplied to the post-heating chamber. SOC system. [7] [2] to [7], the SOC system according to any one of [2] to [7], the control device calculates a predicted value of the amount of water vapor to be generated per unit time in the vaporizer as a predicted water vapor flow rate based on a physical quantity correlated with the amount of thermal energy supplied to each of the plurality of vaporizers, sets the predicted water vapor flow rate as a target flow rate, and controls the flow rate of water supplied from the water supply device to the first-stage vaporizer so that the flow rate of water supplied from the water supply device to the first-stage vaporizer coincides with the target flow rate. SOC system. [8] [1] The SOC system according to [1], the plurality of vaporizers are connected in parallel; The water supply device is connected to each of the plurality of vaporizers connected in parallel, the control device controls the flow rates of water supplied from the water supply devices to the vaporizers based on a physical quantity correlated with an amount of thermal energy supplied to the vaporizers. SOC system. [9] [8] The SOC system according to [8], the plurality of vaporizers include a first vaporizer and a second vaporizer; the water supply device includes a first water supply device that supplies water to the first vaporizer and a second water supply device that supplies water to the second vaporizer; the first vaporizer includes a first vaporization chamber to which water is supplied from the first water supply device, and a first heating chamber disposed adjacent to the first vaporization chamber to which the first exhaust gas discharged from the reaction device is supplied; the second vaporizer includes a second vaporization chamber to which water is supplied from the second water supply device, and a second heating chamber disposed adjacent to the second vaporization chamber to which the second exhaust gas discharged from the reaction device is supplied, the first vaporization chamber and the second vaporization chamber are connected in parallel, the control device controls the flow rate of water supplied from the first water supply device to the first evaporation chamber based on the temperature of the first exhaust gas supplied to the first heating chamber, and controls the flow rate of water supplied from the second water supply device to the second evaporation chamber based on the temperature of the second exhaust gas supplied to the second heating chamber. SOC system. [Explanation of symbols]

[0146] 1, 2, 3...SOC system, 10...hot module, 20...cell stack (reaction device), 30A...vaporizer, 30B...vaporizer, 31...first stage vaporizer, 311...first stage vaporizer chamber, 312...first stage heating chamber, 32...post-stage vaporizer, 321...post-stage vaporizer chamber, 322...post-stage heating chamber, 33...first vaporizer, 331...first vaporizer chamber, 332...first heating chamber, 34...second vaporizer, 341...second vaporizer chamber, 342...second heating chamber, 40...heating device, 50...insulating material, 60...burner device (heat source device), 71...first temperature sensor, 72...second temperature sensor, 80...water pump (water supply device), 81...first water pump (water supply device), 82...second water pump (water supply device), 90...condenser, 100...control device

Claims

1. a water supply device capable of adjusting the flow rate of supplied water; a vaporizer that generates water vapor by vaporizing the water supplied from the water supply device; a reactor to which the water vapor generated in the vaporizer is supplied, which generates a first gas and a second gas by a chemical reaction using the supplied water vapor, and which discharges a first exhaust gas containing the generated first gas and a second exhaust gas containing the generated second gas; a control device for controlling the evaporation of water in the evaporation device; An SOC system comprising: the vaporization device has a plurality of vaporizers; Each of the plurality of vaporizers is supplied with water and thermal energy for heating the supplied water, the control device controls the flow rate of water supplied from the water supply device to the vaporizer based on a physical quantity correlated with the amount of thermal energy supplied to the plurality of vaporizers. SOC system.

2. 2. The SOC system of claim 1, the plurality of vaporizers are connected in series; the water supply device is connected to a first-stage vaporizer that is the most upstream vaporizer among the plurality of vaporizers connected in series so as to supply water to the first-stage vaporizer; the control device controls the flow rate of water supplied from the water supply device to the first-stage vaporizer based on a physical quantity correlated with the amount of thermal energy supplied to the plurality of vaporizers. SOC system.

3. 3. The SOC system according to claim 2, the control device controls the flow rate of water supplied from the water supply device to the first-stage vaporizer so that the flow rate of water supplied to the first-stage vaporizer increases as the amount of thermal energy supplied to the plurality of vaporizers increases. SOC system.

4. 3. The SOC system according to claim 2, the plurality of carburetors include the first-stage carburetor and one rear-stage carburetor arranged downstream of the first-stage carburetor, the first-stage vaporizer includes a first-stage vaporization chamber to which water is supplied from the water supply device, and a first-stage heating chamber disposed adjacent to the first-stage vaporization chamber to which the first exhaust gas discharged from the reaction device is supplied; the post-vaporizer includes a post-vaporization chamber to which water is supplied from the first-stage vaporization chamber, and a post-heating chamber disposed adjacent to the post-vaporization chamber and to which the second exhaust gas discharged from the reaction device is supplied, the latter-stage vaporization chamber is connected in series downstream of the former-stage vaporization chamber; the control device controls the flow rate of water supplied from the water supply device to the first-stage vaporization chamber based on the temperature of the first exhaust gas supplied to the first-stage heating chamber and the temperature of the second exhaust gas supplied to the second-stage heating chamber. SOC system.

5. 5. The SOC system according to claim 4, a heat source device for supplying thermal energy to either or both of the first exhaust gas supplied to the initial-stage heating chamber and the second exhaust gas supplied to the subsequent-stage heating chamber; the control device controls either or both of the amount of thermal energy supplied from the heat source device to the first exhaust gas and the amount of thermal energy supplied from the heat source device to the second exhaust gas, based on either or both of the temperature of the first exhaust gas supplied to the initial heating chamber and the temperature of the second exhaust gas supplied to the subsequent heating chamber. SOC system.

6. 6. The SOC system according to claim 5, the heat source device is configured to heat the second exhaust gas supplied to the post-heating chamber. SOC system.

7. 3. The SOC system according to claim 2, the control device calculates a predicted value of the amount of water vapor to be generated per unit time in the vaporizer as a predicted water vapor flow rate based on a physical quantity correlated with the amount of thermal energy supplied to each of the plurality of vaporizers, sets the predicted water vapor flow rate as a target flow rate, and controls the flow rate of water supplied from the water supply device to the first-stage vaporizer so that the flow rate of water supplied from the water supply device to the first-stage vaporizer coincides with the target flow rate. SOC system.

8. 2. The SOC system of claim 1, the plurality of vaporizers are connected in parallel; The water supply device is connected to each of the plurality of vaporizers connected in parallel, the control device controls the flow rates of water supplied from the water supply devices to the vaporizers based on a physical quantity correlated with an amount of thermal energy supplied to the vaporizers. SOC system.

9. 9. The SOC system according to claim 8, the plurality of vaporizers include a first vaporizer and a second vaporizer; the water supply device includes a first water supply device that supplies water to the first vaporizer and a second water supply device that supplies water to the second vaporizer; the first vaporizer includes a first vaporization chamber to which water is supplied from the first water supply device, and a first heating chamber disposed adjacent to the first vaporization chamber to which the first exhaust gas discharged from the reaction device is supplied; the second vaporizer includes a second vaporization chamber to which water is supplied from the second water supply device, and a second heating chamber disposed adjacent to the second vaporization chamber to which the second exhaust gas discharged from the reaction device is supplied, the first vaporization chamber and the second vaporization chamber are connected in parallel, the control device controls the flow rate of water supplied from the first water supply device to the first evaporation chamber based on the temperature of the first exhaust gas supplied to the first heating chamber, and controls the flow rate of water supplied from the second water supply device to the second evaporation chamber based on the temperature of the second exhaust gas supplied to the second heating chamber. SOC system.

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