JP2008059770A - Heat exchanger for exhaust heat recovery, and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger for exhaust heat recovery with heat exchange effectiveness improved, and to provide a fuel cell system equipped with it. <P>SOLUTION: The heat exchanger for exhaust heat recovery 1 is provided with a heat exchange unit 12 for recovering heat of exhaust gas exhausted from a fuel cell, and a storing container 2 for storing the heat exchange unit 12. The storing container 2 is structured of a cylindrical container 3 formed of heat-resistant resin inide which the exhausted gas passes through, and lid-shape members 4, 5 arranged at apertures on both sides of the cylindrical container 3 and closing the apertures. The cylindrical container 3 consists of an inner wall 6 and an outer wall 7, and has a dual structure consisting of a storing part 8 storing the heat exchange unit 12 formed by the inner wall 6 and a hollow part 9 formed by the inner wall 6 and the outer wall 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat exchanger for exhaust heat recovery that effectively recovers heat from exhaust gas of a fuel cell and a fuel cell system including a heat exchanger for exhaust heat recovery.

  In recent years, various fuel cell systems that generate power using fuel cells have been proposed as next-generation energy.

  In this fuel cell system, the exhaust heat of the exhaust gas generated by the power generation of the fuel cell is effectively recovered, the recovered heat is exchanged with a heated source such as tap water, and the tap water is heated to Thus, it has been proposed to use the warm water for hot water supply, for example.

In addition, a heat exchanger for effectively recovering the exhaust heat of the exhaust gas generated by the power generation of the fuel cell is disclosed (for example, see Patent Document 1), and in order to recover the exhaust heat more effectively. There has been proposed a heat exchanger in which a plurality of fins are provided on the outer wall of a pipe through which water flows, and the flow of exhaust gas and the flow of water are opposed to each other (see, for example, Patent Document 2).
JP 2002-231285 A JP 2006-127784 A

  By the way, since the operating temperature of the solid oxide fuel cell is generally a high temperature of 800 to 1000 ° C., the exhaust heat temperature of the exhaust gas generated by the power generation of the fuel cell is also increased. Therefore, conventionally, the storage container for storing the heat exchange unit is made of a material having high heat resistance, and such a material has been made of metals such as copper, aluminum, and stainless steel.

  However, when the storage container is made of these metals, there are many problems unique to the metals.

  For example, since metals have high thermal conductivity, there is a problem that exhaust heat of exhaust gas is likely to be thermally diffused outside the storage container, resulting in a low heat exchange rate of the heat exchanger. When the heat exchange rate of the heat exchanger is low, the fuel cell cannot efficiently generate power. Therefore, for the purpose of improving the heat exchange rate, it is necessary to affix or wrap the insulation around the storage container, and in the assembly of the heat exchanger, there is a problem that the number of steps of assembling the insulation is large. there were.

  Also, heat exchange of the exhaust heat of the exhaust gas causes the water vapor in the exhaust gas to liquefy and produce condensed water. When the operating temperature of the fuel cell is very high, the condensed water contains impurities such as NOx. Condensed water may become acidic. Therefore, there is a problem that the storage container is corroded by the acidic condensed water.

  Further, when the storage container is made of metal, there is a problem that the weight of the heat exchanger for exhaust heat recovery becomes heavy.

  Accordingly, an object of the present invention is to provide a heat exchanger for recovering exhaust heat and a fuel cell system that can improve the heat exchange rate and solve the problems that occur when a storage container is made of metals. .

  The heat exchanger for exhaust heat recovery of the present invention is for exhaust heat recovery comprising a heat exchange unit for recovering heat of exhaust gas discharged from a fuel cell, and a storage container for storing the heat exchange unit. A heat exchanger, wherein the storage container is disposed in a cylindrical container formed of a heat-resistant resin through which exhaust gas passes and an opening on both sides of the cylindrical container, and closes the opening. The cylindrical container is composed of an inner wall and an outer wall, and a hollow portion formed by the inner wall and the outer wall that houses the heat exchange unit formed by the inner wall. It is characterized by a double structure consisting of parts.

  In such a heat exchanger for exhaust heat recovery, since the cylindrical container constituting the storage container has a double structure consisting of a storage part and a hollow part, the exhaust heat of the exhaust gas is thermally diffused outside the storage container. This can be suppressed. That is, even if the exhaust heat of the exhaust gas is thermally diffused from the storage part, it is possible to suppress the thermal diffusion to the outside of the storage container by the hollow part or the outer wall. Therefore, the exhaust heat of the exhaust gas discharged from the fuel cell can be brought into contact with the heat exchange unit efficiently, and the exhaust heat recovery by the heat exchange unit can be performed efficiently.

  In addition, since the cylindrical container is formed of a heat resistant resin, it is possible to effectively prevent the cylindrical container from being corroded by condensed water generated after heat exchange of the exhaust gas, and the weight of the heat exchanger for recovering exhaust heat. Can be lightened.

  In the heat exchanger for exhaust heat recovery according to the present invention, an outer edge of the lid member on the exhaust gas inflow side of the lid member is attached to the housing part, and a heat insulating material is housed in the hollow part. It is preferable.

  In such a heat exchanger for exhaust heat recovery, the outer edge of the lid-like member on the side into which the exhaust gas flows out of the lid-like member is attached to the accommodating portion so that the accommodating portion is closed by the lid-like member. Since the heat insulating material is stored in the hollow portion, it is possible to further suppress the exhaust heat of the exhaust gas from being thermally diffused to the outside of the storage container. Therefore, exhaust heat of the exhaust gas discharged from the fuel cell can be brought into contact with the heat exchange unit more efficiently, and exhaust heat recovery by the heat exchange unit can be performed efficiently.

  Here, the heat insulating material accommodated in the hollow part forms a heat insulating material that matches the shape of the hollow part, and the heat insulating unit is accommodated only by inserting the formed heat insulating material into the hollow part. Can be surrounded by a heat insulating material.

  As a result, for example, the process of affixing or attaching a heat insulating material to the outer wall of the heat exchanger for exhaust heat recovery is not necessary, so the number of processes for assembling the heat insulating material can be reduced, and the heat for heat recovery An exchanger can be easily manufactured.

  In the heat exchanger for exhaust heat recovery according to the present invention, the hollow portion is preferably closed by the lid-like member.

  In such a heat exchanger for exhaust heat recovery, since the hollow portion is sealed by the lid-like member, the air filled in the hollow portion and the air outside the storage container are not convected, and the hollow portion The heat insulation effect can be effectively obtained by the air. Therefore, exhaust heat recovery by the heat exchange unit can be performed more effectively.

  Furthermore, since the lid-like member only needs to close the hollow portion, the size of the gas circulation hole for allowing the exhaust gas to flow into the cylindrical container can be increased. Thereby, the pressure loss of the exhaust gas flowing into the storage container can be reduced.

  Moreover, it is preferable that the heat exchanger for waste heat recovery of this invention is provided with the heat insulating material in the said hollow part.

  In such a heat exchanger for exhaust heat recovery, since the heat insulating material is stored in the hollow portion, it is possible to further suppress the heat diffusion of the exhaust heat of the exhaust gas to the outside of the storage container. Therefore, exhaust heat of the exhaust gas discharged from the fuel cell can be brought into contact with the heat exchange unit more efficiently, and exhaust heat recovery by the heat exchange unit can be performed efficiently.

  Here, the heat insulating material accommodated in the hollow part forms a heat insulating material that matches the shape of the hollow part, and the heat insulating unit is accommodated only by inserting the formed heat insulating material into the hollow part. Can be surrounded by a heat insulating material.

  As a result, for example, the process of affixing or attaching a heat insulating material to the outer wall of the heat exchanger for exhaust heat recovery is not necessary, so the number of processes for assembling the heat insulating material can be reduced, and the heat for heat recovery An exchanger can be easily manufactured.

  Further, in the heat exchanger for exhaust heat recovery according to the present invention, the cylindrical container is arranged so that the exhaust gas flows from the top to the bottom inside the lid, and closes the opening on the lower side of the cylindrical container It is preferable that the shaped member includes a drain port for draining condensed water generated by heat exchange and an exhaust port for exhausting exhaust gas after heat exchange.

  In such a heat exchanger for exhaust heat recovery, since the exhaust gas is arranged so as to flow from the top to the bottom of the cylindrical container, the exhaust gas flows in a straight line, reducing the pressure loss of the exhaust gas. be able to. Therefore, the exhaust heat of the exhaust gas discharged from the fuel cell can be efficiently recovered.

  Here, when the exhaust gas discharged by the power generation of the fuel cell is heat-exchanged by the heat exchanger, the condensed water generated by the heat exchange and the exhaust gas after the heat exchange are generated.

  The condensed water generated after the heat exchange is collected more efficiently, for example, by supplying it to a reformer or a water tank that performs steam reforming to supply fuel gas to the fuel cell. In addition, the fuel cell can generate power.

  In addition, since the exhaust gas after heat exchange has a low temperature (about room temperature), when the low temperature exhaust gas stays in the storage part of the storage container, the temperature in the storage container decreases, The heat exchange rate decreases. Therefore, the exhaust gas after heat exchange is preferably exhausted to the outside of the storage container.

  Here, the lid-like member that covers the lower surface of the storage container has a drain port for draining condensed water generated by heat exchange and an exhaust port for exhausting exhaust gas after heat exchange. The exhaust gas after heat exchange can be exhausted outside the storage container.

  And since a cylindrical container is arrange | positioned so that waste gas may flow inside from the top to the bottom, the condensed water which arises by heat exchange flows effectively below a cylindrical container. Here, since the drainage port which drains the condensed water which arises by heat exchange is provided in the lid-shaped member which covers the lower surface of a cylindrical container, the condensed water produced by heat exchange can be collect | recovered efficiently.

  The fuel cell system according to the present invention includes a fuel cell, the heat exchanger for exhaust heat recovery according to any one of the above for recovering heat of exhaust gas discharged from the fuel cell, and the exhaust heat recovery. And a hot water storage tank for storing hot water generated by the heat exchanger.

  By incorporating the heat exchanger for exhaust heat recovery of the present invention into a fuel cell system including a fuel cell and a hot water storage tank, exhaust heat of exhaust gas discharged from the fuel cell can be efficiently recovered. Therefore, a more efficient fuel cell system can be obtained.

  Further, the condensed water recovered by the heat exchanger for exhaust heat recovery of the present invention is subjected to steam reforming for supplying fuel gas to the fuel cell, and water (steam) is supplied to the reformer. By supplying it to a water tank or the like, it is possible to efficiently generate power from the fuel cell. Therefore, a more efficient fuel cell system can be obtained.

  The heat exchanger for exhaust heat recovery of the present invention is formed of a heat-resistant resin, and is disposed in a double-structured cylindrical container composed of an inner wall and an outer wall, and openings on both sides of the cylindrical container, and the openings are closed. Since the heat exchange unit for recovering the heat of the exhaust gas discharged from the fuel cell is stored inside the storage container having the lid-like member to be recovered, the heat of the exhaust gas discharged from the fuel cell is efficiently recovered can do. In addition, since the cylindrical container that houses the heat exchange unit is made of heat-resistant resin, the heat of the exhaust gas can be recovered more efficiently, and the cylindrical container may be corroded by the condensed water generated after the heat exchange of the exhaust gas. Absent. Moreover, since the cylindrical container is formed of a heat resistant resin, the weight of the heat exchanger can be reduced.

  FIG. 1 is an exploded perspective view showing a heat exchanger 1 for exhaust heat recovery according to the present invention, and shows a storage container 2 for storing a heat exchange unit. In FIG. 1, the heat exchange unit is omitted. In addition, the same number shall be attached | subjected about the same member and it is the same below.

  The storage container 2 includes a cylindrical container 3 through which exhaust gas passes, and lid-shaped members 4 and 5 that are disposed at openings on both sides of the cylindrical container 3 and close the openings. The container 3 is made of a heat resistant resin.

  The cylindrical member 3 has a double structure composed of an inner wall 6 and an outer wall 7, and a double structure composed of a storage portion 8 for storing the heat exchange unit 12 and a hollow portion 9 formed by the inner wall 6 and the outer wall 7. Is formed.

  Therefore, since the cylindrical container 3 has a double structure composed of the storage portion 8 and the hollow portion 9, even if the heat of the exhaust gas is thermally diffused from the storage portion 8, the outer wall 7 and the hollow portion 9 Therefore, it is possible to suppress thermal diffusion outside the storage container, and it is possible to suppress exhaust heat of exhaust gas from thermally diffusing outside the storage container 2. Thereby, the exhaust heat of the exhaust gas discharged from the fuel cell can be brought into contact with the heat exchange unit efficiently, and the exhaust heat recovery by the heat exchange unit can be performed efficiently.

  In addition, the temperature of the exhaust gas generated by the power generation of the fuel cell flowing into the storage container 2 (tubular container 3) is preferably 250 ° C. or less, and more preferably 200 ° C. or less. If it is in this temperature range, it is not defined as a boiler. Therefore, when the heat exchanger 1 for exhaust heat recovery according to the present invention is incorporated in a fuel cell system, a safe fuel cell system is obtained.

  Therefore, as the heat resistant resin forming the cylindrical member 3, a material having heat resistance against the temperature of the exhaust gas can be used. For example, polyether ether ketone, polyether ketone, polyphenylene sulfide Generally known heat-resistant resins such as polycarbonate and ABS can be used, and polyether ether ketone and polyphenylene sulfide can be used more preferably.

  In addition, since the cylindrical member 3 is formed of the above heat-resistant resin, the cylindrical container 3 can be prevented from being corroded by condensed water generated after the heat exchange of the exhaust gas, and the exhaust heat recovery heat exchanger The weight of 1 can be reduced.

  In FIG. 1, the outer edge of the lid-like member 4 on the side into which the exhaust gas flows is attached to the accommodating portion 8 of the cylindrical member 3, and the lid-like member 4 closes the accommodating portion 8 of the cylindrical member 3. And the hollow part 9 is arrange | positioned so that it may open. A dotted line in FIG. 1 indicates that the outer edge of the lid-like member 4 overlaps with the outer edge of the storage portion 8, that is, the outer edge of the lid-like member 4 is attached to the storage portion of the cylindrical member 3. .

  The lid-like member 4 has a gas flow hole 11 that is a gas inlet / outlet through which the exhaust gas flows into the cylindrical container 3.

  Here, in the case where the cylindrical member 3 is arranged so that the exhaust gas flows from the top to the bottom, the lid-like member 4 that closes the upper opening of the cylindrical member has a high exhaust gas temperature. The cylindrical member 3 is preferably formed of a heat-resistant resin, but the upper part of the cylindrical member 3 has a high exhaust gas temperature and is unlikely to be corroded by condensed water. In addition to the heat-resistant resin described above, metals such as copper, aluminum, and stainless steel can also be used.

  Further, when the tubular member 3 is arranged so that the exhaust gas flows from the top to the bottom, the lid-like member 5 that closes the opening on the lower side of the tubular member suppresses corrosion due to condensed water. Therefore, it is preferable to be formed of resin, and since the exhaust gas after heat exchange has a low temperature (about room temperature), in addition to the heat-resistant resin described above, a commonly used resin may be used. it can.

  Although not shown, in such a heat exchanger 1 for exhaust heat recovery, a heat insulating material can be accommodated in the hollow portion 9.

  Accordingly, the storage portion 8 is closed by the lid-like members 4 and 5, and the outer edge of the lid-like member 4 is attached to the storage portion 8 and the heat insulating material is accommodated in the hollow portion 9. It is possible to effectively suppress the exhaust heat of the exhaust gas discharged by the heat diffusion outside the storage container 2.

  In this case, the heat insulating material is produced in accordance with the shape of the hollow portion 9, and the produced heat insulating material is inserted into the hollow portion 9 so that the periphery of the storage portion 8 that houses the heat exchange unit 12 is surrounded by the heat insulating material. can do. Therefore, unlike the conventional case, it is not necessary to attach or wind a heat insulating material to the outside of the outer wall 7 of the cylindrical container 3, and the heat insulating material can be easily assembled and the exhaust heat recovery exchanger 1 can be assembled. Can be manufactured very easily.

  The storage container 3 is provided with a hole 10 through which the piping of the heat exchange unit is inserted.

  FIG. 2 is an exploded perspective view showing that the heat exchange unit 12 is housed in the housing portion 8 of the cylindrical container 3 of the present invention. In FIG. 2, the lid-like members 4 and 5 are omitted.

  The heat exchange unit 12 is provided with a pipe 13 through which water flows in a meandering manner with the flow direction of exhaust gas discharged from the fuel cell as an axis, and a plurality of fins 14 in contact with the outer wall of the pipe 13 in parallel with the exhaust gas flow direction. ing. In FIG. 2, exhaust gas flows from the upper part to the lower part of the heat exchanger 1 for exhaust heat recovery (cylindrical container 3), and conversely, water flows from the lower part to the upper part. Yes.

  FIG. 2 shows a case where a so-called finned tube heat exchanger is accommodated in the cylindrical container 3. For example, a plate heat exchanger having a large heat transfer area and a compact shape can be used. 3 can also be stored.

  The pipe 13 is preferably closely packed in the cylindrical container 3 in order to improve heat exchange efficiency. For example, the pipe 13 can be manufactured in a meandering shape, a spiral shape, a corrugated shape, or the like. However, in order to make the shape of the heat exchanger 1 compact, a meandering shape is preferable. In addition, in order to collect | recover the heat | fever of waste gas efficiently as metals of piping 13, metals, such as copper, aluminum, and stainless steel, can be used.

  Furthermore, in order to increase the heat transfer area from the exhaust gas to the water flowing inside the pipe 13, it is preferable that fins 14 are provided in contact with the outer wall of the pipe 13, and a plurality of heat transfer areas can be increased more efficiently. The fin 14 is preferably provided.

  Further, the fin 14 is not provided at the bent portion of the pipe 13 so as to reduce the pressure loss of the exhaust gas, but is disposed in a straight portion in a direction perpendicular to the exhaust gas flow direction in parallel with the exhaust gas flow direction.

  When a plurality of fins 14 are provided, these fins 14 are preferably arranged at a predetermined interval in order to prevent pressure loss of the exhaust gas. In addition, if this interval is too narrow, condensed water generated by the liquefaction of water vapor in the exhaust gas may accumulate in the gaps between the fins, and the heat exchange rate may decrease, whereas if the interval is too wide, The recovery efficiency is poor, and the heat exchange rate may be reduced. Accordingly, the interval between the fins 14 is preferably about 1 to several mm.

  Further, the shape of the fins 14 may be designed so that heat exchange is performed uniformly throughout the heat exchange unit 12. For example, a square shape, a rectangular shape, a disk shape, or the like can be appropriately selected and used. it can. Furthermore, as a material of the fin 14, metals, such as copper, aluminum, and stainless steel, can be used.

  The flow rate of the water flowing through the pipe 13 of the heat exchange unit 12 is appropriately set so that the temperature of the hot water obtained after the heat exchange falls within a preset temperature range, but is 0.2 liter / min or less. Is preferred.

  For example, the calorific value of the exhaust gas of a 1 KW class solid oxide fuel cell is calculated as 66.1 KJ / min when the exhaust gas temperature flowing into the cylindrical container 3 is 212 ° C., for example. In this case, a sufficient temperature difference can be secured by the counter flow between the exhaust gas and the water flowing through the pipe 13 of the heat exchange unit 12 in the cylindrical container 3, and high-temperature hot water can be obtained from the exhaust gas. Specifically, the water temperature at the outlet of the heat exchanger can be set to 80 ° C. to 90 ° C. by setting the flow rate of water flowing through the pipe 13 of the heat exchange unit 12 to 0.2 liter / min or less.

  FIG. 3 is an exploded perspective view showing the heat exchanger 15 for exhaust heat recovery according to the present invention, and shows a storage container 16 for storing the heat exchange unit 12. In addition, although the heat exchange unit 12 is abbreviate | omitted in FIG. 3, the heat exchange unit mentioned above can be used.

  The storage container 16 has substantially the same shape as the storage container 2 shown in FIG. 1, and is characterized in that the hollow portion 9 is closed by a lid-like member 4 '.

  Here, since the lid-like member 4 ′ only needs to close the hollow portion 9, the hole diameter of the gas flow hole 11 ′ of the lid-like member 4 ′ can be made the same size as the hole diameter of the storage portion 8. Thereby, the pressure loss of the exhaust gas flowing into the storage container 2 can be reduced. 3, the hole diameter of the gas flow hole 11 ′ of the lid-like member 4 ′ and the hole diameter of the storage portion 8 are the same size, and the gas flow hole 11 ′ and the storage portion 8 are overlapped and connected. It shows that

  The hollow portion 9 is closed by a lid-like member 4 ′ that covers the upper surface of the cylindrical container 3 and a lid-like member 5 that covers the lower surface of the cylindrical container 3. Therefore, when the hollow portion 9 is filled with air, the filled air does not convect with the air outside the storage container 16. Therefore, the air filled in the hollow portion 9 effectively has a heat insulating effect. Thereby, it is possible to more effectively prevent the exhaust heat of the exhaust gas flowing into the storage unit 8 from being diffused to the outside of the storage container 16, and the exhaust heat recovery by the heat exchange unit 12 can be efficiently performed. it can.

  The lid-like members 4 ′ and 5 may have any shape that closes the hollow portion 9. However, the lid-like member 5 that covers the lower surface has an exhaust port for exhausting exhaust gas and a drain port for draining condensed water described later. It is preferable to provide.

  In order to further increase the power generation efficiency, a heat insulating material can be stored in the hollow portion 9. A heat insulating material is produced according to the shape of the hollow part 9, and the circumference | surroundings of the accommodating part 8 which accommodates the heat exchange unit 12 can be enclosed with a heat insulating material by inserting the produced heat insulating material in the hollow part 9. . Therefore, unlike the prior art, there is no need for a step of attaching or insulating the heat insulating material to the outside of the outer wall 7 of the cylindrical container 3, and it becomes very easy to assemble the heat insulating material. 15 is very easy to manufacture.

  Another embodiment of the heat exchanger 17 for exhaust heat recovery of the present invention is shown in FIG. FIG. 5 is an exploded perspective view in which the heat exchange unit 12 is mounted on the storage portion 8 of the cylindrical container 18, and the hollow portion 9 is covered with lid-like members 4 'and 5'. The hole diameter of the gas flow hole 11 ′ of the lid-like member 4 ′ covering the upper surface of the cylindrical container 18 is the same as the hole diameter of the storage portion 8. Further, the lid-like member 5 ′ covering the lower surface of the cylindrical container 18 is provided with a drain port 20 for draining condensed water and an exhaust port 21 for exhausting exhaust gas. Further, a blowout duct 22 is provided at the exhaust port 21, and a lid 23 for closing the hole 10 is provided at the cylindrical container 18. FIG. 5 shows a longitudinal sectional view of the heat exchanger 17 for exhaust heat recovery in which the components shown in FIG. 4 are connected.

  The cylindrical container 18 can be provided with a reinforcing rib 19 that connects the inner wall 6 and the outer wall 7 of the cylindrical container 18, and FIG. 5 shows a case where the reinforcing rib 19 is provided. By providing the reinforcing ribs 18 in the cylindrical container 18, the strength of the cylindrical container 18 can be increased, and damage due to an impact from an external force can be prevented.

  When exhaust heat of the exhaust gas flowing into the storage portion 8 of the cylindrical container 18 is heat-exchanged by the heat exchange unit 12, water contained in the exhaust gas is generated as condensed water as the temperature of the exhaust gas decreases. Is done. Then, the condensed water is collected and supplied to a reformer, a water tank, or the like that performs steam reforming to supply fuel gas to the fuel cell, for example, so that the fuel cell can generate power more efficiently. .

  Here, when supplying condensed water to a reformer etc., it is preferable that impurities, such as NOx and SOx, are not contained in condensed water. Therefore, the operating temperature of the solid oxide fuel cell is preferably less than 1000 ° C, more preferably 800 ° C or less. When the operating temperature of the fuel cell is 1000 ° C. or higher, the condensed water generated when the exhaust heat of the exhaust gas from the fuel cell is recovered may be acidic with impurities such as NOx and SOx. Therefore, the condensed water containing these impurities cannot be reused unless it is neutralized with a neutralizing agent, and the efficiency of reuse of the condensed water is deteriorated.

  On the other hand, when the operating temperature of the solid electrolyte is 1000 ° C. or lower, preferably 800 ° C. or lower, the condensed water contains almost no impurities such as NOx and SOx. Thus, the condensed water can be reused efficiently.

  The drain port 20 provided in the lid-like member 5 ′ covering the lower surface of the storage container 18 is preferably provided on the lower surface side of the lid-like member 5 ′ (on the side opposite to the surface connected to the cylindrical container 18). Thereby, for example, the condensed water collected on the lower surface side of the lid-like member 5 ′ along the side surface of the storage portion 8 can be collected more efficiently. In addition, in order to collect | recover condensed water more efficiently, the shape of the drain port 20 can also be made into the diagonal shape like a tapered shape.

  In addition, the temperature of the exhaust gas after heat exchange has dropped to about room temperature. Therefore, when the low-temperature exhaust gas stays inside the storage unit 8, the temperature in the storage unit 8 decreases and the heat exchange rate decreases, so the exhaust gas after heat exchange is stored in the storage container 18. It is preferable to exhaust outside.

  In the heat exchanger 17 for exhaust heat recovery according to the present invention, the exhaust port 21 is provided in the lid-like member that covers the lower surface of the storage container 18, so that the exhaust gas after heat exchange is stored in the storage container 18 from the exhaust port 21. Exhausted outside.

  In performing the gas-liquid separation in which the condensed water is exhausted from the drain port 20 and the exhaust gas is exhausted from the exhaust port 21, the diameter of the drain port 20 is preferably smaller than that of the exhaust port 21. Thus, the exhaust gas after heat exchange is not exhausted from the drain port 20 but is exhausted from the exhaust port 21, and gas-liquid separation can be performed.

  Further, in order to exhaust the exhaust gas after heat exchange to the outside of the cylindrical container 18, it is also possible to provide a blowout duct 22 connected to the exhaust port 21. Here, in FIGS. 4 and 5, the blowout duct 22 has a shape in which exhaust gas is exhausted in the lateral direction with respect to the cylindrical container 18 and then exhausted downward. Depending on the shape of the exchanger 17 and the configuration of the fuel cell system, the shape of the blowout duct 22 can be changed as appropriate. Examples of such a shape include a shape in which the exhaust gas after heat exchange exhausted from the exhaust port 21 is exhausted to the upper side of the heat exchanger 17 for exhaust heat recovery.

  The fuel cell system of the present invention stores hot water generated by a fuel cell, a heat exchanger for recovering exhaust heat for recovering heat of exhaust gas discharged from the fuel cell, and a heat exchanger for recovering exhaust heat. A hot water storage tank is provided, and an example of the configuration is shown in FIG.

  The fuel cell system in FIG. 6 includes a fuel cell 24, a fuel supply device 25 for supplying a fuel gas such as natural gas, an oxygen-containing gas supply device 26 for supplying an oxygen-containing gas to the fuel cell 24, a reformed gas, A reformer 27 that performs steam reforming with steam, a water treatment device 29 that purifies the water supplied from the water supply pipe 28, a water tank 30 that stores the water purified by the water treatment device 29, and a water tank 30 A water pump 31 for supplying water stored in the reformer 27, an exhaust gas supply pipe 32 for supplying exhaust gas generated by fuel cell power generation, and heat exchange of the exhaust gas supplied from the exhaust gas supply pipe 32 to hot water. The heat exchanger 33 for exhaust heat recovery, a hot water storage tank 34 for storing hot water generated by heat exchange, a circulation pipe 35 for circulating hot water, and a circulation pump 36 are configured. . In addition, the arrow in FIG. 6 has shown the flow of water, fuel gas, and oxygen containing gas.

  In this fuel cell system, the heat of the exhaust gas discharged from the fuel cell 24 is exchanged by the exhaust heat recovery heat exchanger 33 of the present invention, and the water supplied from the circulation pipe 35 is used as hot water to store the hot water storage tank 34. Stored in the water.

  Here, the exhaust heat of the exhaust gas discharged from the fuel cell 24 is heat-exchanged by the exhaust heat recovery heat exchanger 33 of the present invention, so that the exhaust heat of the exhaust gas discharged from the fuel cell 24 is efficiently recovered. Therefore, a more efficient fuel cell system can be obtained.

  Further, the condensed water recovered by the heat exchanger 33 for exhaust heat recovery is supplied to the reformer 27 that performs steam reforming for supplying the fuel gas to the fuel cell 24, so that the fuel cell 24 can be efficiently used. Power generation can be performed, and a more efficient fuel cell system can be obtained.

  6 shows the case where the condensed water recovered by the heat exchanger 33 for exhaust heat recovery is supplied to the reformer 27. For example, the fuel cell system supplies the condensed water to the water tank 30. Further, the exhaust heat recovery heat exchanger 33 of the present invention utilizes exhaust heat of exhaust gas generated by power generation of the fuel cell 24, and recovers exhaust heat generated by the reformer 27, for example. It is also possible to design a fuel cell system.

It is a disassembled perspective view which shows an example of the heat exchanger for waste heat recovery of this invention. It is a disassembled perspective view of the heat exchanger for exhaust heat recovery of this invention which shows storing a heat exchange unit in a cylindrical container. It is a disassembled perspective view of the heat exchanger for exhaust heat recovery of this invention which shows that a hollow part is obstruct | occluded by a lid-shaped member. The heat exchanger for exhaust heat recovery according to the present invention, which shows that a heat exchanger unit is housed in a cylindrical container, and a drainage port, an exhaust port and a blowout duct are provided on a lid-like member covering the lower surface of the cylindrical container. It is a disassembled perspective view. It is a longitudinal cross-sectional view of the heat exchanger for exhaust heat recovery of this invention which combined each member shown in FIG. It is a block diagram which shows an example of a structure of the fuel cell system of this invention.

Explanation of symbols

1, 15, 17, 33: heat exchanger 2 for exhaust heat recovery, 16: storage container 3, 18: cylindrical container 4, 4 ', 5, 5': lid member 6: inner wall 7: outer wall 8: storage Part 9: Hollow part 11, 11 ': Gas flow hole 12: Heat exchange unit 13: Pipe 14: Fin 19: Reinforcement rib 20: Drain port 21: Exhaust port 24: Fuel cell
34: Hot water storage tank

Claims (6)

A heat exchanger for exhaust heat recovery comprising a heat exchange unit for recovering heat of exhaust gas discharged from a fuel cell, and a storage container for storing the heat exchange unit, the storage container comprising: A cylindrical container formed of a heat-resistant resin through which exhaust gas passes, and a lid-shaped member that is disposed in openings on both sides of the cylindrical container and closes the opening, The cylindrical container is composed of an inner wall and an outer wall, and has a double structure including a housing part for housing the heat exchange unit formed by the inner wall and a hollow part formed by the inner wall and the outer wall. A heat exchanger for exhaust heat recovery. 2. The outer edge of the lid-like member on the side into which exhaust gas flows in the lid-like member is attached to the accommodating portion, and a heat insulating material is accommodated in the hollow portion. Heat exchanger for exhaust heat recovery. The heat exchanger for exhaust heat recovery according to claim 1, wherein the hollow portion is closed by the lid-like member. The heat exchanger for exhaust heat recovery according to claim 3, wherein a heat insulating material is accommodated in the hollow portion. The cylindrical container is disposed so that the exhaust gas flows from top to bottom in the interior, and the lid-shaped member that closes the opening on the lower side of the cylindrical container drains condensed water generated by heat exchange. The exhaust heat recovery heat exchanger according to any one of claims 1 to 4, further comprising an outlet and an exhaust port for exhausting the exhaust gas after heat exchange. A fuel cell, a heat exchanger for exhaust heat recovery according to any one of claims 1 to 5, and a hot water storage tank for storing hot water heat-exchanged with exhaust gas by the heat exchanger for exhaust heat recovery. A fuel cell system comprising the fuel cell system.

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