Reforming unit and fuel cell device

Abstract

To more efficiently perform heat exchange while increasing the degree of design freedom of a reforming unit.SOLUTION: A reforming unit 100 includes: a vaporization part 200 and a reforming part 300. The reforming part 300 is located in the downward of the vaporization part 200. A gas mixture conduit 230 extends downward from the vicinity of an end part of the vaporization part 200 and is connected to the reforming part 300 in the vicinity of the end part of the reforming part 300.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a reforming unit and a fuel cell device. [Background technology]

[0002] A reforming unit for supplying reformed gas to a fuel cell generally has, as its main components, a burner that burns the fuel cell's off-gas, a vaporizer that vaporizes water, and a reformer that generates reformed gas from a mixture of raw gas and steam. Conventional reforming units have a structure in which the burner, reformer, and vaporizer are stacked in this order from bottom to top. For example, in Patent Document 1, exhaust gas generated in the combustor passes through a hole in the center of the reformer and flows upward in the housing. Above the hole, the mixed gas pipe connecting the vaporizer and reformer is bent, creating a structure that facilitates heat transfer of the exhaust gas to the mixed gas pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-91619 Summary of the Invention [Problem to be solved by the invention]

[0004] In the reforming unit with the structure described in Patent Document 1, the heat of the exhaust gas generated in the combustor is taken away more than necessary by the mixed gas in the mixed gas piping, making it impossible to efficiently exchange heat with the oxidant (air), and there is a problem that the overall heat exchange efficiency in the reforming unit cannot be sufficiently improved.In addition, because one end of the vaporizer is located in the center of the reformer, the other end of the vaporizer protrudes in the horizontal direction, which limits the length of the vaporizer and reduces the design freedom of the reforming unit.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a reforming unit that can perform heat exchange more efficiently while increasing the degree of freedom in design. [Means for solving the problem]

[0006] One aspect of the present disclosure is a reforming unit. The reforming unit includes: a vaporizer that vaporizes supplied water to generate steam and outputs a mixed gas of the steam and a raw material gas; a reformer that is installed below the vaporizer and that generates a reformed gas containing hydrogen by reforming the mixed gas output from the vaporizer; and a mixed gas conduit that connects the vaporizer and the reformer. The mixed gas conduit extends downward from near an end of the vaporizer and is connected to the reformer near an end of the reformer. A fuel cell device of the present disclosure also includes the above-described reforming unit. [Effects of the Invention]

[0007] The reforming unit of the present disclosure allows for more efficient heat exchange while increasing design freedom, and the fuel cell device of the present disclosure allows for more efficient heat exchange while increasing design freedom. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a reforming unit according to a first embodiment. [Figure 2] FIG. 10 is a schematic view of a reforming unit according to a second embodiment. [Figure 3] FIG. 10 is a plan view of a modified portion used in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail.

[0010] (Embodiment 1) 1 is a schematic diagram of a reforming unit 100 according to embodiment 1. As shown in FIG. 1, the reforming unit 100 includes a vaporizing section 200, a reforming section 300, and a combustion section (burner) 400.

[0011] A water supply pipe 210 and a gas supply pipe 220 are connected to one end of the vaporizer 200 (the left end in FIG. 1 ). The water supply pipe 210 and the gas supply pipe 220 may be connected to the vaporizer 200 separately, or may be connected to the vaporizer 200 as a multi-pipe configuration. For example, in the case of a multi-pipe configuration, a cylindrical water supply pipe 210 may be arranged on the central axis, and a cylindrical gas supply pipe 220 may be arranged to surround the water supply pipe 210. Water is supplied to the vaporizer 200 through the water supply pipe 210. Meanwhile, the raw material gas supplied to the gas supply pipe 220 flows through a flow path formed between the outer wall of the water supply pipe 210 and the inner wall of the gas supply pipe 220, and reaches the vaporizer 200. Examples of the raw material gas include gaseous fuels such as hydrocarbon-containing natural gas and LPG.

[0012] Water supplied to vaporizer 200 flows while being preheated, and a portion of the water becomes water vapor. The generated water vapor mixes with the preheated source gas in vaporizer 200 to generate a mixed gas. A mixing layer filled with balls made of ceramics such as alumina to promote mixing of the water vapor and the source gas may be formed in part of vaporizer 200. In this case, mixing of the water vapor and the source gas is promoted in the mixing layer.

[0013] The mixed gas generated in vaporization unit 200 is introduced into mixed gas conduit 230, which is connected to the bottom end of vaporization unit 200 on the side opposite to the side connected to water supply pipe 210 and gas supply pipe 220. An electric heater 600 is installed at the end of vaporization unit 200 on the side connected to mixed gas conduit 230, and electric heater 600 heats the mixed gas.

[0014] The mixed gas conduit 230 extends downward without bending and is connected to the reforming section 300 near the end of the reforming section 300 described below, and the mixed gas is supplied to the reforming section 300 via the mixed gas conduit 230.

[0015] A housing 110 is installed below the vaporization section 200. Inside the housing 110, a reforming section 300, a combustion section 400, and an exhaust gas induction chamber 500 are housed.

[0016] The upper end of the housing 110 is closed by an air chamber wall 114, and a lid 112 is provided at a position spaced apart from the air chamber wall 114, thereby providing an air chamber 116, which is part of an oxygen-containing gas flow path through which an oxygen-containing gas (such as air) supplied from the outside via an air supply pipe 140 flows, between the lid 112 and the air chamber wall 114. That is, the air chamber 116 is located above the reforming section 300. The air chamber 116 may also be located inside the housing 110. That is, by closing the upper end of the housing 110 with the lid 112 and providing the air chamber wall 114 at a position inside the housing 110 spaced apart from the lid 112, the air chamber 116, which is part of an oxygen-containing gas flow path through which an oxygen-containing gas (such as air) supplied from the outside via the air supply pipe 140 flows, may be provided between the lid 112 and the air chamber wall 114. The lower end of the housing 110 is closed by a lid 118. An air chamber wall 115 is provided below the lid 118 at a position spaced apart from the lid 118, thereby providing an air chamber 119, which is a part of the oxygen-containing gas flow path, between a part of the lid 118 and the air chamber wall 115. The air chamber 119 may also be located within the housing 110. That is, the lower end of the housing 110 may be closed by the air chamber wall 115, and the lid 118 may be provided at a position within the housing 110 spaced apart from the air chamber wall 115, thereby providing the air chamber 119, which is a part of the oxygen-containing gas flow path, between the lid 118 and the air chamber wall 115. The air chamber 119 is located close to the combustion section 400, which will be described later, and is configured so that heat generated in the combustion section 400 is transferred to the air within the air chamber 119. The size of the air chamber 116 and the air chamber 119 does not necessarily have to match the length or width of one side of the housing 110, and can be changed by appropriately adjusting the size of the lid 112 or the air chamber wall 115.

[0017] An air supply pipe 140 is connected to the lid 112. A portion of the wall of the housing 110 (not shown) also has a double-wall structure formed by the lid 112 and the air chamber wall 114, and an air flow path (not shown) through which air circulates is formed inside the double wall. The air flow path connects the air chamber 116 and the air chamber 119. Air supplied to the air supply pipe 140 passes through the air chamber 116, the air flow path inside the double wall, and the air chamber 119, and is supplied to the fuel cell stack via an air introduction path 150 connected to the bottom of the housing 110. In this embodiment, the double-wall structure for the air flow path is formed on a portion of the wall of the housing 110, but the double-wall structure for the air flow path may also be formed on all (six) wall surfaces of the housing 110. In this way, the air supplied from the air supply pipe 140 exchanges heat with the heat inside the housing 110 while flowing through the air chamber 116, the air flow path inside the double wall, and the air chamber 119, and can be supplied to the fuel cell stack as air with an increased temperature. In other words, the reforming unit 100 of the present disclosure also functions as a heat exchanger that increases the temperature of air supplied from the outside. Also, plate fins may be provided in the air chamber 116 to allow efficient heat exchange with the off-gas.

[0018] When viewed vertically in plan, the reforming section 300 has a doughnut-like shape with a hole. This hole may be located in the center of the reforming section 300. The outer shape of the reforming section 300 is not particularly limited and may be, for example, a circle, an ellipse, or a rectangle. A reforming catalyst is housed in the reforming section 300, and the mixed gas is reformed by the reforming catalyst to generate a reformed gas containing hydrogen. The reformed gas generated in the reforming section 300 passes through a reformed gas supply path 330 connected to the reforming section 300 and is supplied to the fuel cell stack. Any commonly known reforming catalyst may be used.

[0019] The position at which the mixed gas conduit 230 is connected in the reforming section 300 is near the end of the top surface of the reforming section 300 (near the right end of the reforming section 300 in FIG. 1). More specifically, it can be connected to a position away from the hole provided in the reforming section 300 and near the end of the top surface.

[0020] Various types of fuel cell stacks can be used. For example, when the fuel cell is a solid oxide type, various structures such as a flat type, a cylindrical type, and a cylindrical and flat type can be used. Furthermore, fuel cell stacks are not limited to solid oxide types, and solid polymer type fuel cell stacks can also be used.

[0021] Offgas discharged from the fuel cell stack is supplied to the combustion unit 400 through an offgas supply passage 440, and the offgas is ejected from an outlet (not shown) provided on the upper surface of the combustion unit 400. The ejected offgas is ignited and combusted by an ignition device 610, such as a ceramic heater. The ignition device 610 can be provided on the same side of the housing as the electric heater 600. Furthermore, by providing a thermocouple 620 near the ignition device 610, it is possible to easily monitor the temperature inside the housing. Exhaust gas generated by the combustion of the offgas passes through a hole provided in the reforming unit 300 and exchanges heat with the reforming unit 300. An exhaust gas guiding chamber 500 can also be provided adjacent to the lower part of the air chamber 116. In this case, the exhaust gas that has exchanged heat with the reforming unit 300 flows into the exhaust gas guiding chamber 500, allowing the heat of the exhaust gas in the exhaust gas guiding chamber 500 to be efficiently transferred to the air in the air chamber 116.

[0022] An exhaust gas pipe 510 is connected to the upper end of the exhaust gas guide chamber 500 (in this embodiment, the right end in Figure 1), and exhaust gas flows through the exhaust gas pipe 510 into a combustion catalyst chamber 520 located adjacent to and below the vaporization section 200.

[0023] The exhaust gas pipe 510 is provided around the mixed gas conduit 230 described above, and a flow path for the exhaust gas is formed between the outer wall of the mixed gas conduit 230 and the inner wall of the exhaust gas pipe 510. In the process of passing through this flow path, heat of the exhaust gas is transferred to the mixed gas flowing through the mixed gas conduit 230.

[0024] In addition, the mixed gas conduit 230 penetrates the exhaust gas guide chamber 500 below the double-structure area formed by the exhaust gas pipe 510 and the mixed gas conduit 230, and the heat of the exhaust gas in the exhaust gas guide chamber 500 is transferred to the mixed gas conduit 230.

[0025] A combustion catalyst layer filled with a combustion catalyst is formed in a part of the combustion catalyst chamber 520, and the combustion of unreacted gas contained in the exhaust gas is promoted in the combustion catalyst layer.

[0026] The flow of exhaust gas in combustion catalyst chamber 520 is a counterflow that opposes the flow of water, raw material gas, or mixed gas in vaporization section 200. Heat generated in combustion catalyst chamber 520 is transferred to vaporization section 200, promoting the evaporation of water supplied to vaporization section 200. The exhaust gas that has passed through combustion catalyst chamber 520 is discharged to the outside via exhaust gas pipe 540.

[0027] In the reforming unit 100, intake and exhaust system leads such as the water supply pipe 210, gas supply pipe 220, air supply pipe 140, and exhaust gas pipe 540 are provided on the opposite side of the end of the reforming section 300 to which the mixed gas conduit 230 is connected. On the other hand, electrical system leads such as the electric heater 600, ignition device 610, and thermocouple 620 are arranged on the same side as the end of the reforming section 300 to which the mixed gas conduit 230 is connected.

[0028] According to the reforming unit 100 described above, the heat exchange area between the mixed gas conduit 230 and the exhaust gas is reduced, making it difficult for the heat of the exhaust gas to be conducted to the mixed gas conduit 230. This allows the air in the upper part of the housing to be heated more efficiently by the heat of the exhaust gas.

[0029] Furthermore, since the mixed gas conduit 230 extends without bending, the structure of the reforming unit 100 is simplified, which in turn simplifies the manufacturing process and reduces manufacturing costs.

[0030] Furthermore, by locating the intake / exhaust system lead-out section on the opposite side of the end of the reforming section 300 to which the mixed gas conduit 230 is connected, and by locating the electrical system lead-out section on the same side as the end of the reforming section 300 to which the mixed gas conduit 230 is connected, safety can be further improved, the length of the vaporization section 200 can be increased, and the design freedom of the reforming unit 100 can be improved.

[0031] (Embodiment 2) The reforming unit 100 according to the second embodiment will be described below, focusing on the configuration different from that of the first embodiment, and omitting the description of the configuration similar to that of the first embodiment.

[0032] Fig. 2 is a schematic diagram of a reforming unit 100 according to a second embodiment. Fig. 3 is a plan view of a reforming section 301. As shown in Fig. 3, in this embodiment, a partition section 310 is provided in the reforming section 301, a mixed gas conduit 230 is connected near one side of the partition section 310, and a reformed gas supply channel 330 is connected near the other side of the partition section 310. A first position to which the mixed gas conduit 230 is connected and a second position to which the reformed gas supply channel 330 is connected are close to each other, and the flow path from the first position to the second position goes around a hole 320 provided in the reforming section 301.

[0033] This allows the path from the first position to the second position in the reforming section 301 to be longer, and the reforming efficiency in the reforming section 301 to be further improved.

[0034] The fuel cell device of this embodiment can be configured by including the reforming unit described above. The fuel cell device may be a so-called fuel cell module, or a fuel cell device equipped with auxiliary equipment for operating the fuel cell device. For example, when a flat-plate fuel cell stack is used, the reforming unit and the fuel cell stack can be housed in a housing container or covered integrally with a heat insulating material to form a fuel cell module. When a cylindrical or hollow flat-plate fuel cell stack is used, the reforming unit and the fuel cell stack can be housed in a housing container to form a fuel cell module. When a polymer electrolyte fuel cell stack is used, each component can be housed independently in an exterior case. Furthermore, a fuel cell can be configured by including these fuel cell modules and auxiliary equipment for operating the fuel cell module (e.g., pumps and sensors).

[0035] Although the present embodiment has been described above, these are merely examples of the present disclosure, and various configurations other than those described above can also be adopted. For example, to increase the design freedom of the reforming unit 100, one of the widths of the vaporizing section 200 and the reforming section 300 may be positioned more inward than the other in at least one of a side view, a plan view, and a front view. This simplifies the structure of the reforming unit 100 and reduces the size of the heat insulating material and the storage container surrounding the reforming unit 100, thereby making the reforming unit 100 more compact overall. In this case, the mixed gas conduits and the like may have the connection structure described above. Alternatively, the cell stack and reforming unit 100 may be housed inside one container, and exhaust gas generated by combustion of off-gas at the top of the cell stack may pass through holes provided in the reforming section 300, exchange heat with the reforming section 300, and then flow into the exhaust gas guiding chamber 500. Note that one container may be, for example, a container made of metal or the like, but is not limited to this. When the cell stack and reforming unit 100 are covered with a heat insulating material, the heat insulating material may also be considered as one container. Furthermore, a box-shaped exhaust gas introduction member (gas reservoir) may be provided on the upper part of the reforming section 300 so as to form a predetermined gap, allowing exhaust gas (and air) to flow in, thereby providing thermal insulation functions. [Explanation of symbols]

[0036] 100 reforming unit, 200 vaporization section, 300 reforming section, 230 mixed gas conduit

Claims

1. one vaporization unit that vaporizes supplied water to generate steam and delivers a mixed gas obtained by mixing the steam and a raw material gas; one reforming unit disposed below the vaporizing unit and configured to generate a reformed gas containing hydrogen by reforming the mixed gas sent out from the vaporizing unit; a mixed gas conduit connecting the vaporizing unit and the reforming unit; Equipped with the mixed gas conduit extends downward from a vicinity of an end of the vaporizing section and is connected to the reforming section at a vicinity of an end of the reforming section; A reforming unit in which, when viewed from the side or from the front, the longitudinal width of the vaporization section is located more inward than the longitudinal width of the reforming section, or the lateral width of the vaporization section is located more inward than the lateral width of the reforming section.

2. The reforming unit according to claim 1 , wherein one of the longitudinal widths of the vaporizing section and the reforming section is located more inward than the other when viewed in a plan view perpendicular to the vertical direction.

3. The reforming unit according to claim 1 or 2, wherein the reforming section has a shape with a hole when viewed in a vertical plane.

4. a combustion unit for combusting off-gas discharged from the fuel cell stack; The reforming unit according to claim 3 , wherein exhaust gas generated in the combustion section passes through the holes.

5. 5. The reforming unit according to claim 3 or 4, wherein in the reforming section, a first position to which the mixed gas conduit is connected and a second position to which a reformed gas supply path through which the reformed gas is delivered from the reforming section is connected are adjacent to each other, and the flow path from the first position to the second position circles around the hole.

6. 6. The reforming unit according to claim 1, further comprising an oxygen-containing gas flow passage above said reforming section, through which oxygen-containing gas supplied from outside flows.

7. A fuel cell device comprising the reforming unit according to any one of claims 1 to 6.

8. A vaporization unit that vaporizes supplied water to generate water vapor and delivers a mixed gas in which the water vapor and a raw material gas are mixed; a reforming unit disposed below the vaporizing unit and configured to generate a reformed gas containing hydrogen by reforming the mixed gas sent out from the vaporizing unit; a mixed gas conduit connecting the vaporizing unit and the reforming unit; Equipped with the mixed gas conduit extends downward from a vicinity of an end of the vaporizing section and is connected to the reforming section at a vicinity of an end of the reforming section; When viewed from the side or the front, the longitudinal width of the vaporizing section is located inside the longitudinal width of the reforming section, or the lateral width of the vaporizing section is located inside the lateral width of the reforming section, The reforming unit has a longitudinal width of the vaporizing section and a longitudinal width of the reforming section, and when viewed in a plan view from a direction perpendicular to the vertical direction, one of the longitudinal widths of the vaporizing section and the reforming section is located more inward than the other.

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