Fuel reforming apparatus with first pipe ends closed onto second pipe

A fuel reforming apparatus in constructed with a main body including a first pipe and a second pipe disposed in the first pipe and a heat source installed in the second pipe and adapted to generate thermal energy in the second pipe. A reforming reaction unit is formed by filling a reforming catalyst in a space defined between the first and second pipes and is adapted to generate a reformed gas containing hydrogen through a reforming reaction of the fuel. A housing encloses the main body and allows a combustion gas generated from the heat source to flow along an outer circumference of the reforming reaction unit.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filed in the Korean Intellectual Property Office on 27 Sep. 2005 and 19 Oct. 2005 and there duly assigned Ser. Nos. 10-2005-0089817 and 10-2005-0098516, respectively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fuel reforming apparatus for a fuel cell system.

2. Description of Related Art

As is well known, a fuel cell is a system for generating electric energy using a fuel.

In the fuel cell, a polymer electrolyte membrane fuel cell has an excellent output characteristic, a low operating temperature, and fast starting and response characteristics. Therefore, the polymer electrolyte fuel cell advantageously has a wide range of applications including a mobile power source for vehicles, a distributed power source for home or buildings, and a small-sized power source for electronic apparatuses.

The fuel cell system employing the polymer electrolyte membrane fuel cell is constructed with a fuel cell main body (hereinafter, referred to as “stack”), a fuel reformer which reforms the fuel to generate a reformed gas containing hydrogen and supplies the reformed gas to the fuel cell main body, and an oxidizing gas supply unit which supplies an oxidizing gas to the stack.

Therefore, the polymer electrolyte membrane fuel cell system generates electric energy through an electrochemical reaction between the reformed gas and oxidizing gas that are supplied to the stack.

The fuel reformer may be constructed with a heat source that generates thermal energy by direct combustion of the fuel and a reforming reaction unit that generates the reformed gas through a reforming reaction of the fuel using the thermal energy.

In the contemporary fuel reformer, a relatively high temperature combustion gas, which is generated while the fuel is burned in the heat source, is exhausted as it is. This causes the loss of the heat energy of the combustion gas and thus increased the startup time. As a result, the thermal efficiency and performance efficiency of the system are deteriorated.

In addition, since the high temperature combustion gas exhausted through an outlet of the heat source contacts locally a portion of the housing of the fuel reformer, which corresponds to the outlet of the heat source, the housing may be damaged or the thermal energy of the combustion gas may be discharged to an external space through the local portion of the housing, thereby causing the thermal insulation performance to deteriorate.

As described above, in the contemporary fuel reformer, the thermal energy generated from the heat source is discharged through the local portion of the housing and thus the startup time increases. This causes a deterioration of thermal efficiency and performance efficiency of the fuel system.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved fuel reforming apparatus.

It is another object of the present invention to provide a fuel reforming apparatus that is configured to additionally supply thermal energy of the combustion gas to a reforming reaction unit.

It is still another object of the present invention to provide a fuel reforming apparatus that is configured to improve a thermal insulation performance for thermal energy generated from a heat source.

In an exemplary embodiment of the present invention, a fuel reforming apparatus is constructed with a main body including a first pipe and a second pipe disposed inside the first pipe, a heat source installed in the second pipe and adapted to generate thermal energy in the second pipe, a reforming reaction unit formed by filling a reforming catalyst in a space defined between the first and second pipes and adapted to generate a reformed gas containing hydrogen through a reforming reaction of the fuel, and a housing enclosing the main body and allowing a combustion gas generated from the heat source to flow along an outer circumference of the reforming reaction unit.

A flow path along which the combustion gas flows may be formed between the housing and the first pipe.

The housing may be provided with at least one discharging port for discharging the combustion gas flowing along the flow path.

The housing may be made from a thermally insulating material.

The heat source may be provided with a torch connected to a first end of the second pipe and igniting and burning the fuel together with the air.

The heat source may be provided with a first injection port formed on the torch to inject the fuel and air into the second pipe and a first discharging port formed on a second end of the second pipe to discharge the combustion gas to a space defined between the first pipe and the housing.

The heat source may be configured to generate the thermal energy through an oxidation reaction of the fuel and air by an oxidizing catalyst filled in the second pipe.

The heat source may be provided with a first injection port formed on a first end of the second pipe to inject the fuel and air into the second pipe and a first discharging port formed on a second end of the second pipe to discharge the combustion gas to a space defined between the first pipe and the housing.

The reforming reaction unit maybe provided with a second injection port formed on a first end of the first pipe to inject the fuel into a space defined between the first and second pipes and a second discharging port formed on a second end of the first pipe to discharge the reformed gas.

In another exemplary embodiment of the present invention, a fuel reforming apparatus is constructed with a heat source adapted to generate thermal energy, a reforming reaction unit adapted to generate a reformed gas containing hydrogen through a reforming reaction of the fuel using the thermal energy, a main thermal insulation member enclosing the heat source and reforming reaction unit to prevent the thermal energy generated from the heat source from being dissipated to an external side, and an auxiliary thermal insulation member installed on a local portion of the main thermal insulation member, which locally contacts a combustion gas generated from the heat source.

The main thermal insulation member may be provided in the form of a housing.

The auxiliary thermal insulation member may be provided with at least one thermal insulation plate attached on the local portion of the main thermal insulation member.

The main thermal insulation member and the auxiliary thermal insulation member may be made from a material selected from the group consisting of stainless steel, zirconium, aluminum, and ceramic.

The main thermal insulation member may be provided with a receiving portion formed near the local portion and the auxiliary thermal insulation member is made from a thermally insulating material filled in the receiving portion.

The thermally insulating material may be a glass fiber.

In still another exemplary embodiment of the present invention, a fuel reforming apparatus is constructed with a main body comprising a first pipe and a second pipe disposed in the first pipe, a heat source installed in the second pipe and adapted to generate thermal energy in the second pipe, a reforming reaction unit formed by filling a reforming catalyst in a space defined between the first and second pipes and adapted to generate a reformed gas containing hydrogen through a reforming reaction of the fuel, a main thermal insulation member enclosing the main body to allow a combustion gas generated from the heat source to flow along an outer circumference of the reforming reaction unit, and an auxiliary thermal insulation member installed on a local portion of the main thermal insulation member, which contacts locally a combustion gas generated from the heat source.

The main thermal insulation member may be provided in the form of a housing having a cross section area greater than that of the first pipe and a flow path is formed between the first pipe and the housing.

The auxiliary thermal insulation member may be provided with at least one thermal insulation plate attached on the local portion of the main thermal insulation member.

The main thermal insulation member may be provided with a receiving portion formed near the local portion and the auxiliary thermal insulation member is made from a thermally insulating material filled in the receiving portion.

The heat source may be provided with a torch connected to a first end of the second pipe and igniting and burning the fuel together with the air in the second pipe, a first injection port formed on the torch to inject the fuel and air into the second pipe, and a first discharging port formed on a second end of the second pipe to discharge the combustion gas to a space defined between the first pipe and the housing.

The auxiliary thermal insulation member may be provided with at least one thermal insulation plate attached on an inner wall of the main thermal insulation member, which corresponds to the first discharging port.

The main thermal insulation member may be provided with a receiving portion formed to correspond to the first discharging port and the auxiliary thermal insulation member is made from a thermally insulating material filling the receiving portion.

The heat source may be configured to generate the thermal energy through an oxidation reaction of the fuel and air by an oxidizing catalyst filling in the second pipe.

The heat source may be provided with a first injection port formed on a first end of the second pipe to inject the fuel and air into the second pipe and a first discharging port formed on a second end of the second pipe to discharge the combustion gas to a space defined between the first pipe and the housing.

The reforming reaction unit be provided with a second injection port formed on a first end of the first pipe to inject the fuel into a space defined between the first and second pipes and a second discharging port formed on a second end of the first pipe to discharge the reformed gas.

DETAILED DESCRIPTION OF INVENTION

FIG. 1is an assembly drawing of a fuel reforming apparatus constructed as an embodiment according to the principles of the present invention andFIG. 2is a cross-sectional view of the fuel reforming apparatus ofFIG. 1, when the fuel reforming apparatus is assembled.

Referring toFIGS. 1 and 2, a fuel reforming apparatus100as an embodiment according to the principles of the present invention is configured to generate a reformed gas containing hydrogen by combustion reaction of a fuel together with an oxidizing gas to generate thermal energy and performing a reforming reaction of the gaseous fuel using the thermal energy.

Fuel reforming apparatus100is used for a polymer electrolyte membrane fuel cell system that generates electrical energy through an oxidation reaction of the reformed gas and a reduction reaction of an oxidizing gas. Therefore, the reformed gas generated from fuel reforming apparatus100is supplied to a stack of the polymer electrolyte membrane fuel cell system.

The fuel used in fuel reforming apparatus100may be a liquid fuel containing hydrogen, such as methanol, ethanol, liquid petroleum gas (LPG), liquid natural gas (LNG) or gasoline, or a gaseous fuel containing hydrogen.

In addition, oxygen stored in a storage unit or ambient air containing oxygen may be used as the oxidizing gas. In the present embodiment, the case where ambient air containing the oxygen is used as oxidizing gas is exampled.

Fuel reforming apparatus100is constructed with a heat source10for generating thermal energy by combustion reaction of the fuel together with atmospheric air and a reforming reaction unit30for generating a reformed gas containing hydrogen through a reforming reaction of the fuel using the thermal energy generated by heat source10.

Fuel reforming apparatus100is also constructed with a main body50having a concentric dual-pipe structure. That is, main body50includes a first pipe51and a second pipe52disposed inside first pipe51.

First pipe51is cylindrical having opposite ends that are closed and a cross sectional area. Second pipe52is also cylindrical having a cross sectional area smaller than that of first pipe51and opposite ends that are closed. First and second pipes51and52are coaxially disposed so that an outer circumference of second pipe52is spaced apart from an inner circumference of first pipe51by an interval.

In fuel reforming apparatus100, heat source10functions to bum the fuel and supply the thermal energy generated by combustion reaction of the fuel to reforming reaction unit30. Heat source10is constructed with a torch11connected to a first end of second pipe52. Torch11functions to ignite the gaseous fuel together with the air in second pipe52.

Torch11is constructed with an ignition plug (not shown) for igniting the gaseous fuel and the atmospheric air. Torch11is also constructed with a first injection port13afor injecting the fuel and the atmospheric air into second pipe52.

In addition, in heat source10, a first discharging port13bfor discharging combustion gas generated during the combustion reaction of the fuel and air in second pipe52is formed on a second end of second pipe52.

In the present embodiment, reforming reaction unit30is constructed by filling the space between the first and second pipes51and52with a reforming catalyst31, and accordingly, the reformed gas containing hydrogen is generated through a reforming reaction of the gaseous fuel using reforming catalyst31.

Reforming catalyst31may contain a pellet-type carrier made from alumina (Al2O3), silica (SiO2), or titania (TiO2) and a catalytic material such as copper (Cu), nickel (Ni), or platinum (Pt) that is supported in the pellet-type carrier.

In addition, a third injection port33afor injecting the fuel into the space between the first and second pipes51and52is formed on a first end of first pipe51. A second discharging port33bfor discharging the reformed gas generated in the space between first and second pipes51and52through the reforming reaction between the fuel and reforming catalyst31is formed on a second end of first pipe51.

Fuel reforming apparatus100is constructed with a housing70enclosing main body50. Housing70allows a relatively high temperature combustion gas discharged through first discharging port13bof heat source10to flow along an outer circumference of reforming reaction unit30. That is, housing70functions to additionally supply the thermal energy of the combustion gas to reforming reaction unit30.

In addition, housing70also functions as a thermal insulation case that can prevent the thermal energy acting on main body50from being dissipated to an external side.

Housing70is formed in a cylindrical pipe-shape providing an internal space for receiving main body50. Housing70has a first end76that is opened and a second end78that is closed. Housing70is constructed with a sealing cap71for sealing the opening first end76. At this point, sealing cap71is formed in a flat donut-shaped disk so that one end of main body50received in housing70can protrude out of housing70through central hole72of sealing cap71.

Here, housing70is coaxially disposed around first pipe51such that an outer circumference of first pipe51is spaced apart from an inner circumference of housing70. That is, the cross section area of housing70is greater than that of first pipe51.

Therefore, a flow path73along which the combustion gas discharged through first discharging port13bof the heat source10can flow while contacting the outer circumference of reforming reaction unit30is defined between housing70and reforming reaction unit30.

At this point, in order to prevent the thermal energy, which is generated by heat source10and acts on main body50, from being dissipated through housing70, housing70maybe made from a metallic thermally insulating material such as stainless steel, zirconium, or aluminum or a non-metallic thermally insulating material such as ceramic.

Furthermore, housing70is provided near the first end that is open with one or more discharging ports75for discharging the combustion gas circulating along flow path73. Four discharging ports75may be formed at a portion near first end of the housing70and spaced apart from each at an interval of 90°.

The operation of the above-described fuel reforming apparatus constructed as the present embodiment according to the principles of the present invention will now be described in detail.

First, the fuel and atmospheric air are supplied into second pipe52through first injection port13aof torch11.

In this state, when the ignition plug (not shown) is operated, the fuel and air are sprayed into second pipe52and ignited by the ignition plug in heat source10. Then, the fuel and air are burned to generate thermal energy in second pipe52.

At this point, since reforming reaction unit30is formed at an external side of heat source10, the thermal energy is supplied to reforming catalyst31of reforming reacting unit30through second pipe52.

During the above-procedure, the relatively high temperature combustion gas generated by the combustion reaction of the fuel and air in second pipe52is discharged through first discharging port13bof heat source10.

Then, as indicated by arrows inFIG. 2, the combustion gas circulates along flow path73defined between first pipe51and housing70while contacting the outer circumference of reforming reaction unit30. As a result, the thermal energy of the combustion gas is additionally applied to reforming reaction unit30.

Accordingly, since reforming reaction unit30receives the thermal energy of the combustion gas as well as the thermal energy directly supplied from heat source10, reforming reaction unit30can maintain a uniform temperature distribution within a reaction start temperature range required for the reforming reaction throughout the entire region of reforming reaction unit30. At this point, the combustion gas circulating along flow path73is discharged to the external side through discharging ports75of housing70.

In this state, the fuel is supplied to a space defined between first and second pipes51and52through third injection port33aof reforming reaction unit30. Then, the reforming reaction of the fuel is processed by reforming catalyst31in reforming reaction unit30, thereby generating the reformed gas.

At this point, the reformed gas is discharged through the second discharging port33bof reforming reaction unit30and then supplied to the stack of the polymer electrolyte membrane fuel cell system. An oxidation reaction of hydrogen contained in the reformed gas and a reduction reaction of the separately supplied atmospheric air are performed in the stack to output electric energy.

FIG. 3is a cross-sectional view of a modified example of the fuel reforming apparatus ofFIG. 1.

Referring toFIG. 3, a fuel reforming apparatus200of this modified example is identical to that of the foregoing embodiment ofFIG. 2except that a heat source110is formed by filling an oxidizing catalyst115in a second pipe152.

That is, heat source110is configured to generate the thermal energy through an oxidation reaction between oxidizing catalyst115and the fuel and atmospheric air. Therefore, in heat source110, second pipe152is provided at a first end with a first injection port113athrough which the fuel and air are injected into second pipe152. Second pipe152is further provided at a second end with a first discharging port113bthrough which the combustion gas generated during the combustion reaction of the fuel and air by oxidizing catalyst115is discharged.

Oxidizing catalyst115may contain a pellet-type carrier made from alumina (Al2O3), silica (SiO2), or titania (TiO2) and a catalytic material such as platinum (Pt) or ruthenium (Ru) that is supported on the pellet-type carrier.

When fuel reforming apparatus200is operated, the fuel and atmospheric air are supplied into second pipe152through first injection port113aof heat source110. Then, the thermal energy is generated in heat source110through the oxidation reaction of the fuel and atmospheric air by oxidizing catalyst115. In addition, the combustion gas generated during the combustion reaction of the fuel and atmospheric air by oxidizing catalyst115is discharged through first discharging port113bof heat source110.

Since other parts of fuel reforming apparatus200according to this modified example and the operation thereof are identical to those of the foregoing embodiment ofFIG. 2, the detailed description of fuel reforming apparatus200will be omitted herein.

FIG. 4is an assembly drawing of a fuel reforming apparatus according to another embodiment of the present invention andFIG. 5is a sectional view of the fuel reforming apparatus ofFIG. 4, when the fuel reforming apparatus is assembled.

Since a basic structure of the fuel reforming apparatus of this embodiment is identical to that of the foregoing embodiment ofFIGS. 1 and 2, only the different structure and operation from those of the foregoing embodiment will be described in the following description.

In a fuel reforming apparatus300of this embodiment, a housing370serves as a heat insulation case for preventing the thermal energy applied from a heat source310to a main body350from being dissipated to the external side. For convenience, housing370will be referred to as “main thermal insulation member.”

The combustion gas generated during the combustion reaction of the fuel in heat source310is discharged through a first discharging port313bof heat source310and then circulated along a flow path373defined between first pipe351and main thermal insulation member370.

During the above procedure, since the combustion gas discharged through first discharging port313bof heat source310locally contacts an end (a portion A inFIGS. 4 and 5) of main thermal insulation member370, which corresponds to first discharging port313b, a temperature of the portion A increases locally and thus the thermal energy is dissipated through the portion A. As a result, the overall thermal insulation performance of fuel reforming apparatus300deteriorates.

Therefore, in this embodiment, an auxiliary thermal insulation member390is provided on portion A of main auxiliary insulation member370. Auxiliary thermal insulation member390prevents the thermal energy of the combustion gas from being locally discharged through portion A.

Auxiliary thermal insulation member390is constructed with a thermal insulation plate391attached on an inner wall of the end (portion A) of main thermal insulation member370. Thermal insulation plate391is formed in a shape corresponding to that of the portion A and made from a material identical to that of main thermal insulation member370.

That is, when main thermal insulation member370is formed in a cylindrical shape having a circular section, thermal insulation plate391is formed in a disk-shape corresponding to a shape of the end of main thermal insulation member370.

Referring toFIGS. 4 and 5, although only one thermal insulation plate391is provided on portion A, the present invention is not limited thereto. For example, a plurality of thermal insulation plates391may be installed on portion A.

When main thermal insulation member370is made from a metallic thermally insulating material, thermal insulation plate391is attached on portion A through a welding process. When main thermal insulation member370is made from a non-metallic thermally insulating material, thermal insulation plate391may be attached on portion A by an adhesive substance.

The operation of fuel reforming apparatus300constructed as this embodiment will now be described in detail.

First, the fuel and atmospheric air are supplied into second pipe352through first injection port313aof torch311.

In this state, when the ignition plug (not shown) is operated, the fuel and atmospheric air are sprayed into second pipe352and ignited by the ignition plug in heat source310. Then, the fuel and atmospheric air are burned to generate the thermal energy in second pipe352.

At this point, since reforming reaction unit330is formed at an external side of heat source310, the thermal energy is supplied to reforming catalyst331of reforming reacting unit330through second pipe352.

During the above-procedure, the relatively high temperature combustion gas generated by the combustion reaction of the fuel and atmospheric air in second pipe352is discharged through first discharging port313bof heat source310.

Then, as indicated by arrows inFIG. 5, the combustion gas circulates along the flow path373defined between first pipe351and main insulation member370while contacting the outer circumference of reforming reaction unit330. As a result, the thermal energy of the combustion gas is additionally applied to reforming reaction unit330.

Accordingly, since reforming reaction unit330receives the thermal energy of the combustion gas as well as the thermal energy directly supplied from heat source310, reforming reaction unit330can maintain a uniform temperature distribution within a reaction start temperature range required for the reforming reaction throughout the entire region of reforming reaction unit330. At this point, the combustion gas circulating along flow path373is discharged to the external side through discharging port375of main thermal insulation member370.

The thermal energy applied to reforming reaction unit330and flow path373by heat source310is not dissipated to the external side by main thermal insulation member370.

During the above procedure, the high temperature combustion gas generated from heat source310is locally directed to the end (portion A) of main thermal insulation member370through first discharging port313b. At this point, since thermal insulation plate391is installed on portion A of main thermal insulation member370, dissipation of the thermal energy of the combustion gas locally acting on portion A of main thermal insulation member370through the portion A can be prevented by thermal insulation plate391.

Therefore, the combustion gas maintains its thermal energy and circulates along flow path373defined between first pipe351and main thermal insulation member370, thereby additionally applying the thermal energy to reforming reaction unit330.

In this state, the fuel is supplied to a space defined between first and second pipes351and352through first injection port333aof reforming reaction unit330. Then, the reforming reaction of the fuel is processed by reforming catalyst31in reforming reaction unit30, thereby generating the reformed gas containing the hydrogen.

At this point, the reformed gas is discharged through second discharging port333bof reforming reaction unit330and then supplied to the stack of the polymer electrolyte membrane fuel cell system. An oxidation reaction of hydrogen contained in the reformed gas and a reduction reaction of the separately supplied atmospheric air are performed in the stack to output predetermined electric energy.

FIG. 6is a cross-sectional view of a modified example of the fuel reforming apparatus ofFIG. 5.

Referring toFIG. 6, in a fuel reforming apparatus400according to this modified example, an auxiliary thermal insulation member490is constructed with a thermally insulating material491that is buried near a portion A of a main thermal insulation member470.

That is, a receiving space471is provided near portion A of main thermal insulation member470and filled with the thermally insulating material. Receiving space471is defined between an inner wall of portion A and a barrier473spaced apart from the inner wall of portion A. The thermally insulating material may be a glass fiber.

Since other parts of fuel reforming apparatus400according to this modified example and the operation thereof are identical to those of the foregoing embodiment ofFIGS. 4 and 5, the detailed description thereof will be omitted herein.

FIGS. 7 and 8are cross-sectional views of other modified examples of the fuel reforming apparatus ofFIG. 5.

Referring toFIGS. 7 and 8, in a fuel reforming apparatus500,600according to these modified examples, an oxidizing catalyst515,615fills a second pipe552,652of a heat source510,610.

Heat source510,610is configured to generate the thermal energy through the oxidation reaction of the fuel and atmospheric air by the oxidizing catalyst515,615.

In heat source510,610, a first injection port513a,613afor injecting the fuel and atmospheric air into second pipe552,652is formed on a first end of second pipe552,652. A first discharging port513b,613bfor discharging the combustion gas generated during the combustion reaction of the fuel and atmospheric air by oxidizing catalyst515and615is formed on a second end of second pipe552,652.

Oxidizing catalyst515,615may contain a pellet-type carrier made from alumina (Al2O3), silica (SiO2), or titania (TiO2) and a catalytic material such as platinum (Pt) or ruthenium (Ru) that is supported in the pellet-type carrier.

Therefore, when fuel reforming apparatus500,600is operated, the fuel and atmospheric air are supplied into second pipe552,652through first injection port513a,613aof heat source510,610. Then, the thermal energy is generated in heat source510,610through the oxidation reaction of the fuel and atmospheric air by oxidizing catalyst515,615. In addition, the combustion gas generated during the combustion reaction of the fuel and atmospheric air by oxidizing catalyst515,615is discharged through first discharging port513b,613bof heat source510,610.

Referring toFIG. 7, auxiliary thermal insulation member590in fuel reforming apparatus500is constructed with a thermal insulation plate591attached on an inner wall of the end wall578(portion A) of main thermal insulation member570. Thermal insulation plate591is formed in a shape corresponding to that of portion A and made from a material identical to that of main thermal insulation member570.

That is, when main thermal insulation member570is formed in a cylindrical shape having a circular section, thermal insulation plate591is formed in a disk-shape corresponding to a shape of the end of main thermal insulation member570.

Referring toFIG. 8, auxiliary thermal insulation member690in fuel reforming apparatus600is constructed with a thermally insulating material691that is buried near a portion A of main thermal insulation member670.

That is, a receiving space671is provided near portion A of main thermal insulation member670and filled with the thermally insulating material. Receiving space671is defined between an inner wall of portion A and a barrier673spaced apart from the inner wall of portion A. The thermally insulating material may be a glass fiber.

Since other parts of fuel reforming apparatus500,600according to this modified example and the operation thereof are identical to those of the foregoing embodiment ofFIG. 2, the detailed description thereof will be omitted herein.

According to the present invention, since the fuel reforming apparatus further includes the housing enclosing the main body, the housing allows a relatively high temperature combustion gas discharged through the first discharging port of the heat source to flow along an outer circumference of the reforming reaction unit. As a result, the thermal energy of the combustion gas is additionally applied to the reforming reaction unit.

Accordingly, since the reforming reaction unit receives the thermal energy of the combustion gas as well as the thermal energy directly supplied from the heat source, it can maintain a uniform temperature distribution within a reaction start temperature range required for the reforming reaction throughout the entire region. As a result, the thermal efficiency and performance efficiency of the fuel cell system can be further improved.

Furthermore, since the auxiliary thermal insulation member is additional installed on a local portion of the main thermal insulation member, which locally contacts the combustion gas discharged from the heat source, the dissipation of the thermal energy to the external side through the local portion of the main thermal insulation member can be prevented, thereby reducing the thermal energy loss and preventing the main thermal insulation member from being locally damaged.

Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concept taught herein still fall within the spirit and scope of the present invention, as defined by the appended claims.