Patent Description:
A fuel cell generates electricity using reaction between hydrogen and oxygen. The fuel cell has the highest efficient when using hydrogen directly. However, installing a hydrogen storage tank directly where the fuel cell is installed causes a safety problem. Therefore, at present, hydrocarbon fuel is reformed to produce hydrogen which in turn is used as fuel in the fuel cell. A method of reforming the hydrocarbon fuel includes a water vapor reforming method in which hydrogen is generated by reacting water vapor with hydrocarbon fuel.

In a fuel cell system operating in a high temperature, such as a solid oxide fuel cell (SOFC) system or a molten carbonate fuel cell (MCFC) system, in order to improve electricity generation efficiency and to operate the system stably, fuel gas and air should be heated to a temperature above a certain temperature and then be fed to a fuel cell module. A fuel cell system comprising a fuel cell stack, an evaporating part, a reforming part, a heat exchange part, and a burning part in a single module is known from <CIT>.

In such a fuel cell system, the reformed fuel gas needs to be stably and uniformly supplied to the fuel cell module, and the fuel gas and air are required to be heated using combustion equipment having a minimal number of component.

A purpose of the present disclosure is to provide a fuel cell system that may not only improve thermal efficiency, but also improve reforming efficiency and electricity generation efficiency.

One aspect of the present disclosure provides a fuel cell system comprising: a fuel cell module including a plurality of unit cells for generating electric energy using oxygen of air and hydrogen of reformed fuel gas; a first module including: a burner to burn unreacted fuel gas and air discharged from the fuel cell module; a heat-transfer device placed adjacent to the burner to heat air via heat exchange thereof with flame and hot combusted gas generated from the burner and to supply the heated air to the fuel cell module; and a water-vapor generator disposed adjacent to the burner to convert water moving therein to water vapor via heat exchange thereof with the hot combusted gas; and a second module placed adjacent to the first module, wherein the second module is configured to: mix fuel supplied from an external fuel supply source and the water vapor supplied from the water-vapor generator with each other to form a mixture; perform a water vapor reforming reaction of the mixture; and supply the reformed fuel gas to the fuel cell module.

In one embodiment, the heat-transfer device includes: a first container having a first inner space defined therein, wherein the first container has a bottom having a first opening and a second opening defined therein for exposing the first inner space, wherein the first opening and the second opening are spaced from each other; and a heat-exchange pipe received in the first inner space and having an inlet connected to an external air supply source and an outlet connected to the fuel cell module, wherein the burner includes: an outer casing coupled to the bottom of the first container, wherein the outer casing has an open top and has a second inner space communicating with the first inner space through the first opening; an inner casing received in the second inner space, wherein the inner casing has a third inner space defined therein, wherein a horizontal cross sectional area of the third inner space increases as the third inner space extends upwards, and wherein the inner casing has an open top, and a side wall having through-holes defined therein communicating the second inner space and the third inner space with each other; an ignition device received in the third inner space; a fuel supply pipe connected to the inner casing for supplying the unreacted fuel gas discharged from the fuel cell module to the third inner space; and an air supply pipe connected to the outer casing for supplying the unreacted air discharged from the fuel cell module to the second inner space, wherein the water-vapor generator includes: a second container having a fourth inner space defined therein communicating with the first inner space through the second opening, wherein the second container is coupled to the bottom of the first container and is disposed adjacent to the outer casing; and a vaporization pipe received in the fourth inner space and having an inlet connected to an external water supply source and an outlet connected to the second module.

In one embodiment, the first container further includes a fluid guide plate protruding from the bottom of the first container to a first height. In one embodiment, the first height is smaller than a height of the first inner space, wherein a width of the fluid guide plate is equal to a width of the first inner space.

In one embodiment, the heat-exchange pipe includes a plurality of straight portions extending in a parallel manner, and bent portions, each bent portion connecting adjacent straight portions to each other, wherein the fluid guide plate passes through at least some of the straight portions.

In one embodiment, the burner further includes a diffusion mesh network disposed at an outlet of the fuel supply pipe to diffuse the unreacted fuel gas discharged from the fuel supply pipe.

In one embodiment, an area of the second opening is smaller than an area of a top face of the fourth inner space.

In one embodiment, the second container contacts the outer casing.

In one embodiment, the second container has a combusted gas outlet to discharge combusted gas supplied from the first inner space through the second opening to an outside.

In one embodiment, the second module includes: a mixer for mixing fuel supplied from the external fuel supply source and water vapor supplied from the water-vapor generator with each other to form a mixed fuel gas; a first heat exchanger placed on top of the mixer for heating the mixed fuel gas supplied from the mixer via heat exchange thereof with hot unreacted fuel gas supplied from the fuel cell module; a reformer placed on top of the first heat exchanger for performing a water vapor reforming reaction of the heated mixed fuel gas supplied from the first heat exchanger to generate the reformed fuel gas; and a second heat exchanger placed on top of the reformer for heating the reformed fuel gas supplied from the reformer via heat exchange thereof with hot unreacted air supplied from the fuel cell module and supplying the heated reformed fuel gas to the fuel cell module.

In one embodiment, the second module further include a container for receiving therein at least one of the mixer, the first heat exchanger, the reformer and the second heat exchanger.

In one embodiment, the mixer includes: an outer housing having an inner space defined therein and having an outlet for connecting the inner space thereof with the first heat exchanger; a first pressure-pulsation prevention plate received in the inner space of the outer housing to divide the inner space thereof into a first space and a remaining space, wherein first through-holes are defined in the first pressure-pulsation prevention plate; a second pressure-pulsation prevention plate received in the inner space of the outer housing and disposed on top of the first pressure-pulsation prevention plate, wherein the second pressure-pulsation prevention plate divides the remaining space to a second space connected to the first heat exchanger through the outlet and a third space located between the first space and the second space, wherein second through-holes are defined in the second pressure-pulsation prevention plate; an inner housing received in the inner space of the outer housing and disposed on top of the second pressure-pulsation prevention plate, wherein the inner housing is disposed in the second space and has a fourth space defined therein, wherein the inner housing has third through-holes for communicating the second space and the fourth space with each other, wherein the water vapor is supplied to one of the first space and the fourth space, and the fuel is supplied to the other of the first space and the fourth space.

In one embodiment, the mixer further includes: a water vapor supply pipe coupled to the outer housing and connected to the first space for receiving the water vapor from the water-vapor generator and supplying the water vapor to the first space; and a fuel supply pipe coupled to the outer housing and the inner housing and connected to the fourth space for supplying the fuel received from the fuel supply source to the fourth space.

In one embodiment, each of the first and second pressure-pulsation prevention plates has a central region and a peripheral region surrounding the central region, wherein the first through-holes are formed in the central region of the first pressure-pulsation prevention plate, wherein the second through-holes are formed in the peripheral region of the second pressure-pulsation prevention plate. In one embodiment, a position of the fourth space corresponds to the central region of the second pressure-pulsation prevention plate.

In the fuel cell system according to the present disclosure, the heat-transfer device, the burner and the water-vapor generator are collected to form the first module, and the mixer, the first heat exchanger, the reformer and the second heat exchanger are collected to form the second module. Thus, a length of a pipe connecting the components to each other in each module may be minimized, thereby to minimize differential pressure and heat loss, as well as simplify an assembly process of the system and allow easy maintenance.

Moreover, the first module heats the air and generates the water vapor using one combustion device that burns the unreacted fuel gas and air, thereby to improve thermal efficiency. The water-vapor generator is capable of reducing the pressure-pulsation, such that the fuel gas may be uniformly supplied to the fuel cell module. Further, since the mixed fuel gas heated via the heat exchange is supplied to the reformer, and the reformed fuel gas is heated again via heat exchange and then is supplied to the fuel cell module, reforming efficiency and electricity generation efficiency may be improved.

The present disclosure may be modified in various ways and may take many forms. Specific embodiments are illustrated in the drawings and described in detail herein. However, the embodiments are not intended to limit the present disclosure thereto. In describing the drawings, similar reference numerals are used for similar components. In the accompanying drawings, dimensions of structures are shown to be enlarged than actual ones for clarity of the present disclosure.

Thus, a first element, component, region, layer or section described below could be termed a second element, component, region, layer or section.

It will be further understood that the terms "comprises", "comprising", "includes", and "including" when used in this specification, specify the presence of the stated features, integers, operations, elements, and/or components, but do not preclude the presence or addition of one or greater other features, integers, operations, elements, components, and/or portions thereof.

<FIG> is a view for illustrating a fuel cell system according to an embodiment of the present disclosure. <FIG> is a cross-sectional view of a first module shown in <FIG>.

Referring to <FIG>, a fuel cell system <NUM> according to an embodiment of the present disclosure may include a fuel cell module <NUM>, a first module <NUM>, and a second module <NUM>. In one embodiment, the fuel cell module <NUM>, the first module <NUM> and the second module <NUM> may be disposed inside a hot box (not shown) in which spaces between the fuel cell module <NUM>, the first module <NUM> and the second module <NUM> are filled with an insulating material.

The fuel cell module <NUM> may include a plurality of unit cells, each unit cell generating electrical energy using oxygen in air and hydrogen in reformed fuel gas. The unit cell may include a fuel electrode (anode), an air electrode (cathode), and an electrolyte positioned therebetween. When fuel gas containing hydrogen (H<NUM>) and air containing oxygen (O<NUM>) are respectively supplied to the fuel electrode and the air electrode, reduced oxygen ions (O<NUM>-) are transferred from the air electrode to the fuel electrode via the electrolyte. The oxygen ion (O<NUM>-) transferred to the fuel electrode reacts with hydrogen (H<NUM>) provided to the fuel electrode to produce water (H<NUM>O) and electron (e-). The unit cell may generate electrical energy using the electrons generated via the reaction as described above. The reaction between oxygen and hydrogen is an exothermic reaction, so that the fuel cell module <NUM> is capable of releasing heat during a power generation mode in which the module <NUM> generates electrical energy.

The fuel cell module <NUM> may include a solid oxide fuel cell (SOFC) or a molten carbonate fuel cell (MCFC) operating at a temperature of about <NUM> or higher. In one example, the fuel cell module <NUM> may include a stack of flat unit cells or may include a bundle of tubular or flat tubular unit cells.

The first module <NUM> may heat the air and supply the heated air to the fuel cell module <NUM>, and may generate water vapor and supply the same to a gas mixer <NUM> of the second module <NUM>.

In one embodiment, the first module <NUM> may supply the heated air to the fuel cell module <NUM> through a connection plate (not shown). In this case, the connection plate may have channels defined therein to connect a first pipe for supplying hot air generated from the first module <NUM> to the fuel cell module <NUM> and a second pipe to supply reformed fuel gas generated from the second module <NUM> to the fuel cell module <NUM> to an air channel (cathode path) and a fuel channel (anode path) defined inside the fuel cell module <NUM>.

In one embodiment, the connection plate is disposed under the fuel cell module <NUM> to support the fuel cell module <NUM> thereon. In this case, the first and second modules <NUM> and <NUM> may be placed under the connection plate.

In another embodiment, the connection plate may be disposed above the fuel cell module <NUM>. In this case, the first and second modules <NUM> and <NUM> may be disposed above the connection plate.

In another embodiment, the first and second pipes may be directly connected to the fuel cell module <NUM>.

In one embodiment, the first module <NUM> may include a heat-transfer device <NUM>, a burner <NUM> and a water-vapor generator <NUM>.

The heat-transfer device <NUM> may heat the air supplied from an external air supply source <NUM> and supply the heated air to the fuel cell module <NUM>.

In one embodiment, the heat-transfer device <NUM> may include a first container <NUM> and a heat-exchange pipe <NUM>.

The first container <NUM> may have an inner space defined therein. The heat-exchange pipe <NUM> may be placed in the inner space of the first container <NUM>. In one example, a first opening 1211a exposing the inner space of the first container <NUM> to the burner <NUM> and a second opening 1211b exposing the inner space of the first container <NUM> to the water-vapor generator <NUM> may be defined in a bottom face of the first container <NUM>.

The heat-exchange pipe <NUM> may have a meandering structure having a plurality of straight portions and bent portions, each bent portion connecting adjacent straight portions with each other. The heat-exchange pipe <NUM> may have an inlet connected to the external air supply source <NUM> and an outlet connected to the fuel cell module <NUM>. In one embodiment, the inlet and the outlet of the heat-exchange pipe <NUM> may be disposed outside the first container <NUM>.

The heat-exchange pipe <NUM> may receive heat energy from flame and hot combusted gas generated in the burner <NUM>, and may use the heat energy to heat the air supplied from the external air supply source <NUM>.

In one embodiment, the first container <NUM> further includes a fluid guide plate <NUM> protruding from a bottom thereof to a predetermined height to increase a residence time in the first container <NUM> of the hot combusted gas supplied from the burner <NUM>.

The height of the fluid guide plate <NUM> from the bottom of the container <NUM> is smaller than a vertical height of the inner space of the first container <NUM>. A width of the fluid guide plate <NUM> may be the same as a width of the inner space of the first container <NUM>. In this case, a portion of the heat-exchange pipe <NUM> may penetrate the fluid guide plate <NUM>.

When such a fluid guide plate <NUM> is disposed, the hot combusted gas supplied from the burner <NUM> stays in the first container <NUM> for a relatively long time, such that more heat energy is supplied to the heat-exchange pipe <NUM>.

The burner <NUM> may be disposed under the heat-transfer device <NUM>, and may combust unreacted fuel gas and air emitted from the fuel cell module <NUM>.

In one embodiment, the burner <NUM> may include an outer casing <NUM>, an inner casing <NUM>, an ignition device <NUM>, a fuel supply pipe <NUM> and an air supply pipe <NUM>.

The outer casing <NUM> may have an inner space having an open top and may be coupled to a bottom of the first container <NUM> so that the inner space of the outer casing <NUM> is connected to the inner space of the first container <NUM> through the first opening 1211a of the first container <NUM>. In this case, the first opening 1211a of the first container <NUM> may expose an entirety of the inner space of the outer casing <NUM>. As long as the outer casing <NUM> is coupled to the bottom of the first container <NUM> so that the inner space of the outer casing <NUM> is connected to the inner space of the first container <NUM> through the first opening 1211a of the first container <NUM>, a structure of the outer casing <NUM> is not particularly limited. In one embodiment, the outer casing <NUM> may include a first bottom spaced apart from the bottom of the first container <NUM>, and a first side wall extending upwardly from an edge of the first bottom, and having a top coupled to the bottom of the first container <NUM>.

The inner casing <NUM> may be placed inside the outer casing <NUM>. A horizontal width of an inner space of the inner casing <NUM> may increase as the inner casing extends upwardly. The inner casing <NUM> may have an open top. In one embodiment, the inner casing <NUM> may include a second bottom placed above the first bottom, a second side wall extending obliquely and upwardly from an edge of the second bottom such that a cross-sectional area of the inner space increases as it extends upwardly. Through-holes may be formed in the second side wall to allow external air to flow into the inner space of the inner casing <NUM>.

The ignition device <NUM> may be disposed inside the inner casing <NUM>. The fuel and the air supplied from the fuel supply pipe <NUM> and the air supply pipe <NUM> may be ignited by the ignition device <NUM>. A known ignition device may be used without limitation as the ignition device <NUM>.

The fuel supply pipe <NUM> may be coupled to the inner casing <NUM>, for example, the second bottom thereof. The unreacted fuel gas discharged from the fuel cell module <NUM> may be supplied via the fuel supply pipe <NUM> to the inner space of the inner casing <NUM>. In one embodiment, the hot unreacted fuel gas discharged from the fuel cell module <NUM> may be first supplied to a first heat exchanger <NUM> of the second module <NUM> to heat a mixed fuel gas via heat exchange therewith. Then, the fuel supply pipe <NUM> may receive the unreacted fuel gas cooled via heat exchange thereof from the first heat exchanger <NUM> and supply the cooled unreacted fuel gas to the inner space of the inner casing <NUM>.

The air supply pipe <NUM> may be coupled to the outer casing <NUM>, for example, the first side wall thereof and may supply the unreacted air discharged from the fuel cell module <NUM> to a space out of the inner casing <NUM> and in the inner space of the outer casing <NUM>. The air supplied to the inner space of the outer casing <NUM> may be introduced into the inner space of the inner casing <NUM> via through-holes formed in the second side wall of the inner casing <NUM>. In one embodiment, hot unreacted air discharged from the fuel cell module <NUM> may be first supplied to a second heat exchanger <NUM> of the second module <NUM> to heat reformed fuel gas via heat exchange therewith. The air supply pipe <NUM> may receive unreacted air cooled via the heat exchange from the second heat exchanger <NUM> and supply the cooled unreacted air to the inner space of the outer casing <NUM>.

In one example, the burner <NUM> may further include a diffusion mesh network <NUM> disposed at an outlet of the fuel supply pipe <NUM> to diffuse the unreacted fuel gas supplied from the fuel supply pipe <NUM>. In one embodiment, the diffusion mesh network <NUM> may be coupled to a top face of the second bottom of the inner casing <NUM>. The unreacted fuel gas contains relatively low content fuel. When the fuel is diffused through the diffusion mesh network <NUM>, the fuel may be spread over a larger area. As a result, the burner <NUM> may create a larger area of flame.

As described above, the inner space of the inner casing <NUM> forming the combustion space has a structure in which a cross-sectional area thereof increases as it goes upwards, and the diffusion mesh network <NUM> is disposed at the outlet of the fuel supply pipe <NUM>. Thus, even when the burner <NUM> receives unreacted fuel gas with a relatively low fuel content and unreacted air with a relatively low oxygen content, flame with a larger area may be generated.

The flame and the hot combusted gas generated in the burner <NUM> may reach the heat-exchange pipe <NUM> through the first opening 1211a of the first container <NUM> to supply heat energy to the heat-exchange pipe <NUM>. In this connection, in order to supply more heat energy to the heat-exchange pipe <NUM>, an area of the first opening 1211a may be equal to an area of a top face of the inner space of the outer casing <NUM>.

The water-vapor generator <NUM> may be disposed adjacent to the burner <NUM> and under the heat-transfer device <NUM>, and may convert water supplied from the external water supply source <NUM> into water vapor via heat exchange thereof with the hot combusted gas generated from the burner <NUM>.

In one embodiment, the water-vapor generator <NUM> may include a second container <NUM> and a vaporization pipe <NUM>.

The second container <NUM> may be coupled to the bottom of the first container <NUM> so that an inner space of the second container <NUM> is connected to the inner space of the first container <NUM> through the second opening 1211b of the first container <NUM>. An area of the second opening 1211b may be smaller than an area of a top face of the inner space of the second container <NUM> so that the hot combusted gas generated from the burner <NUM> stays in the inner space of the first container <NUM> for a long time. For example, the area of the second opening 1211b may be about <NUM>/<NUM> to <NUM>/<NUM> or of the area of the top face of the inner space of the second container <NUM>.

In one example, in order to minimize heat loss, a side wall of the second container <NUM> may contact the outer casing <NUM> of the burner <NUM>.

The vaporization pipe <NUM> may be disposed inside the second container <NUM>, and may have an inlet connected to the external water supply source <NUM> and an outlet connected to a mixer <NUM> of the second module <NUM>. The vaporization pipe <NUM> may receive heat energy from the hot combusted gas as generated from the burner <NUM> and supplied into the second container <NUM> through the inner space of the first container <NUM>. Thus, the vaporization pipe <NUM> may use the heat energy to convert water moving therein into water vapor.

In order to reduce heat loss, the water-vapor generator <NUM> may further include a central structure <NUM> which is disposed in the inner space of the second container <NUM> and around which the vaporization pipe <NUM> is wound.

In one example, the second container <NUM> may have a combusted gas outlet 1231a that supplies thermal energy to the vaporized pipe <NUM> and discharges cooled combusted gas to an outside.

The second module <NUM> may mix the fuel supplied from the external fuel supply source <NUM> and the water vapor supplied from the first module <NUM>, and then may perform a water vapor reforming reaction thereof and may supply the reformed fuel gas to the fuel cell module <NUM>. In this connection, the fuel supplied from the fuel supply source <NUM> may be hydrocarbon fuel chemically containing hydrogen, such as methane (CH<NUM>), ethane (C<NUM>H<NUM>), propane (C<NUM>H<NUM>), butane (C<NUM>H<NUM>), natural gas, and coal gas. The second module <NUM> may be placed adjacent to the first module <NUM> to minimize heat loss.

In one embodiment, the second module <NUM> may include the mixer <NUM>, the first heat exchanger <NUM>, a reformer <NUM> and the second heat exchanger <NUM>.

The mixer <NUM> may be placed adjacent to the burner <NUM> or the water-vapor generator <NUM> of the first module <NUM>, and receive the fuel and the water vapor from the external fuel supply source <NUM> and the water-vapor generator <NUM>, respectively, and may mix the fuel and the water vapor and may supply the mixed fuel gas to the first heat exchanger <NUM>.

A structure of the mixer <NUM> will be described with reference to <FIG>.

The first heat exchanger <NUM> may be placed on top of the mixer <NUM>, and may receive the mixed fuel gas as the mixture between the fuel and the water vapor from the mixer <NUM>, and may heat the mixed fuel gas and supply the heated mixed fuel gas to the reformer <NUM>. In one embodiment, the first heat exchanger <NUM> may receive the hot unreacted fuel gas from the fuel cell module <NUM>, and may heat the fuel gas via heat exchange thereof with the hot unreacted fuel gas. A structure of the first heat exchanger <NUM> is not particularly limited. A known heat exchanger structure for a fuel cell may be applied without limitation.

The reformer <NUM> may be placed on top of the first heat exchanger <NUM>, and may generate hydrogen as a portion of the fuel via the water vapor reforming reaction as shown in a following Reaction Formula <NUM>, and may supply the reformed fuel gas to the second heat exchanger <NUM>:.

Reaction Formula <NUM>     <NUM>CH<NUM> + <NUM>H<NUM>O → <NUM>H<NUM> + <NUM>CO + CO<NUM>.

A structure of the reformer <NUM> is not particularly limited. A known water vapor reforming device may be applied without limitation.

The second heat exchanger <NUM> may be placed on top of the reformer <NUM>, and may heat the reformed fuel gas supplied from the reformer <NUM> and supply the heated reformed fuel gas to the fuel cell module <NUM>. A structure of the second heat exchanger <NUM> is not particularly limited. A known heat exchanger for a fuel cell may be applied without limitation. In one embodiment, the second heat exchanger <NUM> may receive the hot unreacted air from the fuel cell module <NUM>, and may heat the reformed fuel gas via heat exchange thereof with the hot unreacted air.

In one example, the second module <NUM> may further include at least one container (not shown) accommodating therein at least one of the mixer <NUM>, the first heat exchanger <NUM>, the reformer <NUM> and the second heat exchanger <NUM>, respectively.

<FIG> is a cross-sectional view for illustrating one embodiment of the mixer shown in <FIG>.

Referring to <FIG>, the mixer <NUM> may include an outer housing <NUM>, a first pressure-pulsation prevention plate 1312a, a second pressure-pulsation prevention plate 1312b, an inner housing <NUM>, a water vapor supply pipe <NUM>, and a fuel supply pipe <NUM>.

The outer housing <NUM> may have an inner space defined therein, and may have an outlet 1311a for connecting the inner space thereof with the first heat exchanger <NUM>. A structure of the outer housing <NUM> is not particularly limited when the inner space is defined therein to receive the fuel and the water vapor from the external fuel supply source <NUM> and the water-vapor generator <NUM> of the first module <NUM> respectively and mix the fuel and the water vapor with each other.

The first pressure-pulsation prevention plate 1312a and the second pressure-pulsation prevention plate 1312b may be spaced apart from each other and extend parallel to each other and may be disposed inside the outer housing <NUM> and the divide the inner space of the outer housing <NUM> into a first space <NUM>, a second space <NUM>, and a third space <NUM> between the first space <NUM> and the second space <NUM>. In this connection, the outlet 1311a of the outer housing <NUM> may connect the second space <NUM> to the outside. Each of the first and second pressure-pulsation prevention plates 1312a and 1312b may have a through-hole through which gases such as the water vapor and the fuel may pass.

The inner housing <NUM> may be placed on top of the second pressure-pulsation prevention plate 1312b, and may have a fourth space <NUM> defined therein and may be received in the second space <NUM>. In one embodiment, the inner housing <NUM> includes a side wall extending upwardly from the second pressure-pulsation prevention plate 1312b and a cover covering a top of the side wall, and thus may define the fourth space <NUM> together with the second pressure-pulsation prevention plate 1312b. Through-holes through which gases such as the water vapor and the fuel may pass may be formed in the cover of the inner housing <NUM>.

In one embodiment, the water vapor supply pipe <NUM> may be coupled to the outer housing <NUM> and may be connected to the first space <NUM>, and thus may receive the water vapor from the water-vapor generator <NUM> of the first module <NUM> and may supply the water vapor to the first space <NUM>. Further, the fuel supply pipe <NUM> may be coupled to the outer housing <NUM> and the inner housing <NUM> and may be connected to the fourth space <NUM>, and may receive the fuel supplied from the fuel supply source <NUM> and may supply the fuel to the fourth space <NUM>.

Alternatively, in another embodiment, the fuel supply pipe <NUM> may be coupled to the outer housing <NUM> and may be connected to the first space <NUM>. The water vapor supply pipe <NUM> may be coupled to the outer housing <NUM> and the inner housing <NUM> and may be connected to the fourth space <NUM>.

In this manner, the inner space of the outer housing <NUM> may be divided into a plurality of spaces via the pressure-pulsation prevention plates 1312a and 1312b having the through-holes formed therein. When the fuel and the water vapor are supplied to the different spaces, fluctuations in a pressure generated by a supply pump or during a water vaporization process, that is, the pressure-pulsation may be reduced, such that irregularity in the supply of the fuel gas to the first heat exchanger <NUM> may be reduced.

To further reduce the irregularity in the supply of the mixed fuel gas due to the pressure-pulsation, the through-holes may be formed only in a central region C1 among the central region C1 and a peripheral region P1 surrounding the region C1 in the first pressure-pulsation prevention plate 1312a. The through-holes may be formed only in a peripheral region P2 among a central region C2 and the peripheral region P2 surrounding the region C2 in the second pressure-pulsation prevention plate 1312b. In addition, a position of the inner housing <NUM> may correspond to the central region C2 of the second pressure-pulsation prevention plate 1312b, so that the fourth space <NUM> may not be directly connected to the third space <NUM>.

Claim 1:
A fuel cell system comprising:
a fuel cell module including a plurality of unit cells for generating electric energy using oxygen of air and hydrogen of reformed fuel gas;
a first module including:
a burner to burn unreacted fuel gas and air discharged from the fuel cell module;
a heat-transfer device placed adjacent to the burner to heat air via heat exchange thereof with flame and hot combusted gas generated from the burner and to supply the heated air to the fuel cell module; and
a water-vapor generator disposed adjacent to the burner to convert water moving therein to water vapor via heat exchange thereof with the hot combusted gas; and
a second module placed adjacent to the first module, wherein the second module is configured to:
mix fuel supplied from an external fuel supply source and the water vapor supplied from the water-vapor generator with each other to form a mixture;
perform a water vapor reforming reaction of the mixture; and
supply the reformed fuel gas to the fuel cell module.