JP2009084077A - Reforming apparatus for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving the thermal efficiency in a reforming apparatus for a fuel cell. <P>SOLUTION: In a reforming apparatus for a fuel cell for reforming a raw fuel into a hydrogen-rich reformed gas, a reformer 12 generates the reformed gas from the raw fuel. A reforming reaction tube 18 houses linearly the reformer 12, a shift reactor 14 and a selective oxidation unit 16 in this order, and has a recessed area 120 at one-end side thereof where the reformer 12 is housed. An outer casing 22 is disposed around the reforming reaction tube 18 and has a larger diameter than the reforming reaction tube 18. A burner 20 is placed in a combustion chamber 30 opposite to the recessed part 120 and burns a raw fuel to produce combustion exhaust gas. In a heated flow passage 32, the combustion exhaust gas is passes through while heating a recessed part side and an outer casing side of the reformer 12 provided around the recessed part 120. A returning part 128 of the heated flow passage 32 is formed to return from inside the concave part 120 toward the outer circumference side of the reforming reaction tube 18. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reformer for a fuel cell that reforms raw fuel into a reformed gas used in a fuel cell system.

  A polymer electrolyte fuel cell generates electric power by converting chemical energy of hydrogen into electric energy. Practically, hydrogen used as a fuel for a polymer electrolyte fuel cell is a natural gas, a hydrocarbon gas such as naphtha, or a raw fuel gas of alcohols such as methanol and water vapor, which can be obtained relatively easily and inexpensively. Are mixed and reformed by a reformer. Hydrogen gas obtained by reforming is supplied to the fuel electrode of the fuel cell and used for power generation.

Generally, the reformer includes a burner for supplying heat necessary for the reforming reaction of the raw fuel gas with steam. The combustion gas generated by burning the fuel with the burner is guided from the combustion cylinder to a path provided in the vicinity of the reforming reaction section, whereby the thermal energy of the combustion gas is used for the reforming reaction (for example, Patent Documents). 1 and 2).
JP 2007-15911 A Special table 2003-78311 gazette

  However, the reformers described in Patent Documents 1 and 2 flow the combustion exhaust gas generated by burning the fuel with a burner inside the reforming section, thereby generating the thermal energy of the combustion exhaust gas and generating or reforming high-temperature steam. However, the combustion exhaust gas does not flow except inside the reforming part. Therefore, there is room for further improvement in thermal efficiency. In addition, a carbon monoxide shifter and a carbon monoxide remover for reducing carbon monoxide contained in the reformed gas generated by the reformer are further outside the flow path including the reformer. Therefore, the flow path is complicated. As a result, the diameter of the reforming part is increased, and this is a cause of increasing the complexity and size of the entire reformer.

  This invention is made | formed in view of such a condition, The place made into the objective is to provide the technique which improves the thermal efficiency in the reformer for fuel cells.

  In order to solve the above problems, a fuel cell reforming apparatus according to an aspect of the present invention is a fuel cell reforming apparatus that reforms a raw fuel into a hydrogen-rich reformed gas. Reducing part that generates gas, shift shift part that reduces carbon monoxide contained in the reformed gas by a shift reaction, and selective oxidation of carbon monoxide contained in the reformed gas that has passed through the shift shift part A reforming reaction cylinder in which a selective oxidation unit, a reforming unit, a shift shift conversion unit, and a selective oxidation unit are linearly housed in this order and a recess is formed on one end side where the reforming unit is housed. An outer cylinder having a diameter larger than that of the reforming reaction cylinder, a combustion means disposed in a combustion chamber facing the recess, and combusting raw fuel to generate combustion exhaust gas; Recessed part side and outer cylinder of reforming part where combustion exhaust gas is provided around recessed part And a heating channel which passes while heating.

  According to this aspect, since the recessed part side and the outer cylinder side of the reforming part are heated by the combustion exhaust gas passing through the heating flow path, the heat necessary for the reforming part is efficiently supplied.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal efficiency in the reformer for fuel cells can be improved.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. Further, for convenience of explanation, the positional relationship between the respective members will be described in correspondence with the upper, lower, left, and right sides of the drawing, but it is a relative positional relationship and is not limited to this. For example, it is also possible to have an aspect that is upside down.

  FIG. 1 is a cross-sectional view showing a configuration of a fuel cell reforming apparatus 10 according to the present embodiment. The fuel cell reformer 10 generates a hydrogen-rich reformed gas by steam reforming methane, propane, butane, or the like, which is a raw fuel.

  The fuel cell reformer 10 includes a reforming unit 12 that generates reformed gas from raw fuel, a shift shifter 14 that reduces carbon monoxide contained in the reformed gas by a shift reaction, and a shift shifter 14. The selective oxidation unit 16 that selectively oxidizes and reduces carbon monoxide contained in the reformed gas that has passed through, and the reforming unit 12, the shift shift conversion unit 14, and the selective oxidation unit 16 are linearly stored in this order. In addition, a reforming reaction cylinder 18 having a recess 120 formed on one end side in which the reforming section 12 is housed, a burner 20 as combustion means for burning raw fuel to generate combustion exhaust gas, reforming An outer cylinder 22 which is coaxially disposed on the outer periphery of the reaction cylinder 18 and has a diameter larger than that of the reforming reaction cylinder 18. The periphery of the outer cylinder 22 is covered with a heat insulating material 24 except for a place where a plurality of pipes communicate with the outside.

  The burner 20 mixes and burns the air taken in from the air intake 26 and the raw fuel off-gas taken in from the fuel intake 28. When the raw fuel gas burns in the burner 20, a high-temperature combustion exhaust gas of 1200 to 1300 ° C. is generated. The burner 20 is disposed in the combustion chamber 30 facing the recess 120 formed at one end of the reforming reaction cylinder 18 on the reforming section 12 side, and is fixed to the lower portion of the outer cylinder 22. As a result, the heat of the combustion exhaust gas generated by the burner 20 can be immediately used for the reforming reaction in the reforming section 12, so that the thermal efficiency can be improved.

  Between the reforming reaction cylinder 18 and the outer cylinder 22, a heating flow path 32 through which the above-described combustion exhaust gas passes is formed in order to heat the reforming reaction cylinder 18.

  The reforming unit 12 includes a case 34 having a smaller outer diameter than the reforming reaction tube 18 provided at the bottom of the reforming reaction tube 18, and nickel, ruthenium, or the like housed in an inner peripheral portion below the case 34. And a catalyst layer 36 containing a reforming catalyst in which metal particles are supported on alumina. The catalyst layer 36 according to the present embodiment is an annular member that surrounds the outer periphery of the recess 120.

  On the upper surface of the case 34, an opening 38 is formed through which raw fuel and water vapor are mixed. The case 34 is provided with a vent 122 on the side surface so that the reformed gas can pass from the lower side surface of the catalyst layer 36.

  The raw fuel is supplied to the catalyst layer 36 of the reforming unit 12 from the outside of the fuel cell reforming apparatus 10 via the raw fuel supply path 40. At this time, the temperature of the raw fuel is raised by the fuel exhaust gas flowing through the heating flow path 32 and the reformed gas inside the reforming reaction cylinder 18 and the temperature of the reformed gas is lowered.

  Further, the steam necessary for the reforming reaction in the reforming unit 12 is generated from the reformed water supplied from the outside of the fuel cell reforming apparatus 10 via the steam supply path 42. The reformed water, which is a liquid supplied from the outside, is vaporized by the combustion exhaust gas or the reformed gas whose temperature is raised inside the reforming reaction cylinder 18 and is supplied to the catalyst layer 36 as water vapor, and the shift shift section. 14 and the temperature of the selective oxidation unit 16 are lowered.

  In the fuel cell reforming apparatus 10 according to the present embodiment, the raw fuel supply path 40 joins at the steam supply path 42 and the junction 114 at the upstream side of the location where water passing through the steam supply path 42 is vaporized. is doing. The steam supply path 42 has a coil shape in which a part of the steam supply path 42 is spirally wound inside the outer cylinder 22 and the reforming reaction cylinder 18, and water is easily vaporized by increasing the surface area. Therefore, water vapor is generated at least at the lower end of the coil.

  As a result, the temperature increase of the raw fuel and the vaporization of the water by heating the combustion exhaust gas are performed together in the water vapor supply path 42, so that the raw fuel supply path 40 can be shortened.

  Further, since the raw fuel supply path 40 joins the steam supply path 42 in the region outside the reforming reaction cylinder 18, the raw fuel supply path 40 is connected to the steam supply path 42 inside the reforming reaction cylinder 18. There is no need to provide it separately. Therefore, it becomes easy to manufacture the reforming reaction cylinder 18 and the fuel cell reforming apparatus 10 including the same.

  The water vapor supply path 42 has an annular portion 124 formed in a coil shape so that at least a part thereof is in contact with the inner surface of the reforming reaction cylinder 18. As a result, the steam supply passage 42 is efficiently supplied with heat from the combustion exhaust gas passing through the heating passage 32 outside the reforming reaction tube 18 through the reforming reaction tube 18, and water is easily vaporized into steam. . Particularly, by bringing the annular portion 124 formed in a coil shape into contact with the inner surface of the reforming reaction cylinder 18, the contact area between the steam supply path 42 and the reforming reaction cylinder 18 is increased. The heat exchange efficiency between the raw fuel or reformed water and the combustion exhaust gas can be improved.

  The shift shifter 14 includes, for example, a catalyst layer 46 made of copper oxide or zinc oxide pellets, and a partition plate 48 that supports the catalyst layer 46 and has holes formed so that the reformed gas permeates from below to above. And have. The shift shifter 14 can reduce carbon monoxide by a shift reaction using water vapor contained in the reformed gas by the action of the catalyst layer 46.

  For example, the selective oxidation unit 16 has a catalyst layer 50 made of a carbon monoxide selective oxidation catalyst supported by alumina, and a hole formed so as to support the catalyst layer 50 and allow the reformed gas to permeate from below to above. And a partition plate 52. In the selective oxidation unit 16, the concentration of carbon monoxide is further reduced by oxidizing the carbon monoxide with oxygen by the action of the catalyst layer 50 to carbon dioxide.

  In the selective oxidation unit 16 according to the present embodiment, a resistance member 126 that provides resistance to the flow of the reformed gas is provided in a region other than the region A through which the water vapor supply path 42 passes. As a result, the reformed gas heated by the combustion exhaust gas easily flows toward the coil of the water vapor supply path 42 that passes through the selective oxidation unit 16, and heats the water inside the water vapor supply path 42 or the water vapor. Easy to supply. The resistance member 126 may be a member that completely blocks the flow of the reformed gas. As a result, the reformed gas is introduced into the catalyst layer 50 of the selective oxidation unit 16. It should be noted that the same effect can be obtained even if the above-described resistance member is provided in the shift transformer 14.

  An air supply path 54 that communicates with the outside of the fuel cell reforming apparatus 10 to supply oxygen consumed by the selective oxidation unit 16 to a region between the shift shift unit 14 and the selective oxidation unit 16. The distal end portion 56 is disposed. As a result, the air flowing from the tip 56 rises together with the reformed gas from which carbon monoxide has been reduced in the shift shift unit 14 and contributes to the reaction in the selective oxidation unit 16.

  An opening 58 is formed on the upper surface of the reforming reaction cylinder 18 above the selective oxidation unit 16. Connected to the opening 58 is a reformed gas delivery pipe 60 for delivering a reformed gas with sufficiently reduced carbon monoxide to the fuel electrode of a fuel cell (not shown).

  The heating flow path 32 according to the present embodiment has a folded portion 128 on the inlet side located above the burner 20. The folded portion 128 is provided from the inside of the recess 120 so that the combustion exhaust gas passes through the recess side and the outer cylinder side of the catalyst layer 36 of the reforming portion 12 provided around the recess 120 while being heated. 18 is folded toward the outer peripheral side. Therefore, since the recessed portion side and the outer cylinder side of the reforming unit 12 are heated by the combustion exhaust gas passing through the heating flow path 32, the heat necessary for the reforming unit 12 is efficiently supplied.

  In the reforming unit 12, the mixed gas of water vapor and raw fuel flowing into the case 34 from the opening 38 is discharged from the vent 122 as the reformed gas while passing through the catalyst layer 36 downward. The discharged reformed gas flows upward in the gap between the reforming reaction cylinder 18 and the case 34. In other words, the reforming unit 12 turns the gas flow along the side surface of the recess 120 toward the combustion chamber 30 side along the side surface of the recessed portion 120 and toward the shift transformation unit 14 side along the inner surface of the reforming reaction cylinder 18. A flow path 130 is provided.

  Next, the operation of the fuel cell reforming apparatus 10 according to the present embodiment will be described. The combustion exhaust gas generated by the burner 20 flows into the heating flow path 32 from the recess 120 on the lower surface of the reforming reaction cylinder 18, and changes the direction at the folded portion 128 while heating the side surface of the catalyst layer 36 on the recess 120 side. The outer cylinder side of the catalyst layer 36 is also heated while ascending the heating flow path 32. At this time, the catalyst layer 36 is heated through the reforming reaction cylinder 18 to a temperature necessary for the reforming reaction, for example, in the range of 600 to 700 ° C. Further, the water vapor supply path 42 is heated directly or indirectly by the fuel exhaust gas via the reforming reaction cylinder 18, and the reformed water passing through the inside is vaporized. On the other hand, the fuel exhaust gas is cooled by the water vapor supply passage 42 as the heating passage 32 is raised, and the temperature gradually decreases. The combustion exhaust gas that has passed through the heating flow path 32 is discharged to the outside from a discharge port 62 formed in the upper portion of the outer cylinder 22.

  The raw fuel supply path 40 merges with the water vapor supply path 42 at the junction 114, and the reformed water and the raw fuel are sent out downward in the case 34 while being vaporized and heated in the water vapor supply path 42 in a mixed state. It is. Since the steam supply path 42 according to the present embodiment includes the annular portion 124 that is in contact with the inner peripheral surface of the reforming reaction cylinder 18, the reformed water can be vaporized more efficiently and steam can be generated. The raw fuel gas containing water vapor is gradually heated by the heat of the combustion exhaust gas when passing through the inside of the catalyst layer 36, and changes to a hydrogen-rich reformed gas by the reforming reaction.

  The reformed gas obtained by reforming the raw fuel gas rises inside the reforming reaction cylinder 18 by the flow of the supplied raw fuel gas and reaches the shift shift unit 14. Here, since the reforming reaction in the reforming unit 12 is an endothermic reaction, the reformed gas whose temperature has decreased due to the heat recovery of the steam supply path 42 reaches the shift shift unit 14. The shift reaction in the shift shift unit 14 is performed, for example, in the range of 200 to 300 ° C., and heat balance is achieved by the heat recovery of the water vapor supply path 42, so an appropriate temperature can be maintained without special temperature control. It is possible to maintain. As a result, the reformed gas is reduced in carbon monoxide at the shift shift section 14.

  In the case of an apparatus in which the temperature at the shift shift section 14 does not reach an appropriate temperature, the amount of raw fuel in the burner 20 is adjusted, or the number of turns of the coil of the water vapor supply path 42 near the shift shift section 14 is increased or decreased. Can be adjusted.

  The reformed gas whose carbon monoxide has been reduced in the shift shift unit 14 further rises while the flow is regulated by the flow straightening plate 64 inside the reforming reaction cylinder 18 by the flow of the supplied raw fuel gas, and the selective oxidation unit 16 is reached. At that time, the air supplied from the air supply path 54 also rises in the reforming reaction cylinder 18 and reaches the selective oxidation unit 16. The rectifying plate 64 changes the flow of the reformed gas into the flow toward the water vapor supply path 42 in the space between the shift transformation unit 14 and the selective oxidation unit 16. That is, by changing the flow of the reformed gas flowing in the reforming reaction cylinder 18 toward the steam supply path 42, the reformed water and raw fuel gas flowing in the steam supply path 42, the reformed gas, The heat exchange is efficiently performed.

  Since the selective oxidation unit 16 is disposed in the vicinity of the inlet 66 of the water vapor supply path 42, the temperature of the reformed gas is lower than the temperature of the reformed gas in the shift shift unit 14 by cooling with the reformed water. . The selective oxidation reaction in the selective oxidation unit 16 is performed at a lower temperature than the shift reaction in the shift shift unit 14, for example, in the range of 70 to 200 ° C., and heat balance is achieved by heat recovery of the steam supply path 42. It is possible to maintain the reformed gas at an appropriate temperature without controlling the temperature. As a result, the reformed gas is further reduced in carbon monoxide in the selective oxidation unit 16.

  As described above, the fuel cell reforming apparatus 10 has a complicated shape because the reforming unit 12, the shift shift conversion unit 14, and the selective oxidation unit 16 are accommodated in one reforming reaction cylinder 18 in this order. The carbon monoxide contained in the reformed gas can be reduced without forming the flow path. Further, since the combustion exhaust gas passes through the heating flow path 32 between the reforming reaction cylinder 18 and the outer cylinder 22, heat necessary for the reforming reaction in the reforming section 12 inside the reforming reaction cylinder 18 is supplied. Therefore, no heating means such as a heater is required. Further, by forming the heating flow path 32 between the reforming reaction cylinder 18 and the outer cylinder 22, the fuel cell reforming apparatus 10 can be configured with a simple configuration without requiring a flow path that requires folding or many cylinders. Can be realized.

  In other words, the fuel cell reforming apparatus 10 according to the present embodiment is not provided with a flow path that requires folding or many cylinders, so that the cost is reduced by reducing the number of parts and simplifying the manufacturing process. The Moreover, since the heat insulation of the whole apparatus is easily securable by covering the outer peripheral part of the outer cylinder 22 with the heat insulating material 24, the process at the time of mounting | wearing with the heat insulating material 24 can be simplified.

  In addition, the heating flow path 32 is formed so that the combustion exhaust gas passes from the reforming unit 12 side toward the selective oxidation unit 16 side, so that the combustion exhaust gas is connected to the reforming reaction cylinder 18 and the steam supply path 42. The temperature gradually decreases while performing heat exchange. Therefore, the combustion exhaust gas passes through the inside of the heating channel 32 while the temperature is appropriately lowered from the reforming unit 12 having a high reaction temperature to the selective oxidation unit 16 having a low reaction temperature. Therefore, it becomes possible to form the heating flow path 32 linearly.

  The present invention has been described with reference to the above-described embodiment. However, this is an exemplification, and the present invention is not limited to the above-described embodiment, and appropriately combines the configurations of the embodiments. And those substituted are also included in the present invention. Various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and the embodiments to which such modifications are added can be included in the scope of the present invention. .

  For example, in the fuel cell reforming apparatus 10, the raw fuel supply path 40 is configured to merge with the water vapor supply path 42 at a junction downstream of the location where water passing through the water vapor supply path 42 is vaporized. Also good. Thus, after the raw fuel temperature rise and the water vaporization by heating the combustion exhaust gas are performed in the separate raw fuel supply passage 40 and the water vapor supply passage 42, the raw fuel and the steam are joined together to supply each supply. This makes it easy to control the supply of water vapor by raising the temperature of raw fuel and vaporizing water.

  In the fuel cell reforming apparatus described above, in the heat exchange section between gas and water, in order to promote heat transfer on the gas side, an object that increases heat transfer by diffusion of alumina balls, McMahon packing, etc. in the gas side passage. It may be filled. For example, a heat exchange unit for combustion exhaust gas between the reforming unit 12 and the shift conversion unit 14, between the shift conversion unit 14 and the selective oxidation unit 16, an upper portion of the selective oxidation unit 16, and an inlet side of the steam supply path 42. , Etc. may be filled with a heat transfer promoting substance.

  Further, the coil-shaped annular portion 124 may be provided in the entire region of the water vapor supply path 42, or may be provided partially or intermittently, taking into consideration the thermal efficiency and heat balance of the entire apparatus. Design.

  The raw fuel used in the above-described fuel cell reforming apparatus is not limited to the exemplified methane, propane, butane and the like. For example, natural gas, hydrocarbons such as LPG mainly composed of propane / butane, naphtha and kerosene, alcohols such as methanol and ethanol, ethers such as dimethyl ether, and the like may be used as the raw fuel.

It is sectional drawing which shows the structure of the reformer for fuel cells which concerns on this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell reformer, 12 reformer, 14 shift shifter, 16 selective oxidation unit, 18 reforming reaction cylinder, 20 burner, 22 outer cylinder, 30 combustion chamber, 32 heating flow path, 36 catalyst layer, 42 Steam supply path, 64 current plate, 120 recess, 122 vent, 124 annular part, 126 resistance member, 128 folded part, 130 folded channel.

Claims (9)

A reformer for a fuel cell that reforms raw fuel into hydrogen-rich reformed gas,
A reforming section for generating reformed gas from raw fuel;
A shift shifter that reduces carbon monoxide contained in the reformed gas by a shift reaction;
A selective oxidation unit that selectively oxidizes and reduces carbon monoxide contained in the reformed gas that has passed through the shift transformation unit;
A reforming reaction cylinder in which the reforming section, the shift shift conversion section, and the selective oxidation section are stored linearly in this order, and a recess is formed on one end side in which the reforming section is stored,
An outer cylinder disposed on the outer periphery of the reforming reaction cylinder and having a larger diameter than the reforming reaction cylinder;
A combustion means disposed in a combustion chamber facing the recess, and combusting raw fuel to generate combustion exhaust gas;
A heating flow path through which the combustion exhaust gas passes while heating the recess side and the outer cylinder side of the reforming part provided around the recess;
A reformer for a fuel cell, comprising:   2. The reformer for a fuel cell according to claim 1, wherein the heating channel has a folded portion that is folded from the inside of the recess toward the outer peripheral side of the reforming reaction cylinder.   The reforming section has a return flow path in which a gas flow is directed toward the combustion chamber along the side surface of the recess and is directed toward the shift transformation section along the inner surface of the reforming reaction cylinder. Item 3. The fuel cell reformer according to Item 1 or 2. The reforming reaction cylinder houses a steam supply path in which water is vaporized by heating with the combustion exhaust gas in order to supply steam to the reforming section,
The reformer for a fuel cell according to any one of claims 1 to 3, wherein at least a part of the water vapor supply path is in contact with an inner surface of the reforming reaction cylinder.   5. The steam supply path according to claim 4, wherein the steam supply path has an annular portion formed in a coil shape, and is arranged so that at least a part of the annular portion is in contact with an inner surface of the reforming reaction cylinder. The fuel cell reforming apparatus described.   The said selective oxidation part is provided with the resistance member used as resistance of the flow of the said reformed gas in the area | regions other than the area | region through which the said water vapor | steam supply path has passed. Fuel cell reformer.   7. The shift shift unit according to claim 4, wherein a resistance member that provides resistance to the flow of the reformed gas is provided in a region other than a region through which the water vapor supply path passes. A reformer for a fuel cell according to claim 1.   The fuel cell according to any one of claims 4 to 7, wherein the reforming reaction cylinder includes a rectifying member that changes the flow of the reformed gas into a flow toward the water vapor supply path. Reformer.   9. The fuel cell modification according to claim 1, wherein the heating passage is formed so that the combustion exhaust gas passes from the reforming unit side toward the selective oxidation unit side. Quality equipment.

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