JPH04322739A - Fuel reformer for fuel cell - Google Patents

Abstract

PURPOSE:To simplify a whole apparatus by providing a heat exchanging means of an off-gas and a combustion air with a combustion exhaust gas, generated when a raw gas to be reformed passing through an annular type reacting tube packed with a reforming catalyst is heated by a heating medium generated from combustion of off-gas of the fuel cell with combustion air with a burner to reform into a hydrogen enriched gas, in the fuel reformer without providing separately. CONSTITUTION:The combustion exhaust gas passing through the annular exhaust gas flow passage 30 surrounding the annular reacting tube 11 is heat exchanged with the combustion exhaust gas passing through the exhaust gas flow passage 30 in the both side interposing the flow passage between. The annular off-gas flow passage through which the off-gas flows and the annular combustion air flow passage 33 through which the combustion air flows are arranged. And the heat conductive particle 45 is packed in the exhaust gas flow passage 30, the off-gas flow passage 41 and the combustion air flow passage 35, and combustion exhaust gas is heat exchanged with the off-gas and the combustion air, and then the whole appratus is simplified.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention heats a reforming raw material, especially a hydrocarbon raw fuel, using a heat medium produced by burning off gas from a fuel cell with combustion air to reform it into a hydrogen-rich gas. The present invention relates to a fuel reformer for fuel cells that supplies fuel to fuel cells.

0002

2. Description of the Related Art A fuel cell power generation device is constructed by combining a fuel cell and a fuel reformer. A fuel reformer is equipped with a reaction tube filled with a reforming catalyst and a burner.The burner uses a heating medium generated by burning off gas from a fuel cell (described later) with combustion air to heat the reaction tube and heat the inside of the reaction tube. A reformed gas is produced by steam reforming the flowing reforming raw material into a hydrogen-rich gas, and the reformed gas is supplied to the fuel electrode of the fuel cell.

[0003] A fuel cell generates electricity by causing a cell reaction using the above-mentioned reformed gas and air that is separately supplied to an oxidizer electrode. At this time, off-gas containing hydrogen that does not contribute to the cell reaction from the fuel electrode is supplied as fuel to the burner of the fuel reformer.
It is combusted in a burner to heat the reaction tube as described above.

[0004] By the way, when hydrocarbon-based methane is used as the raw fuel for reforming, the equilibrium temperature in the steam reforming reaction in the reaction tube must be maintained at about 700°C. The temperature of the combustion exhaust gas after heating the reaction tube also becomes a high temperature of 650 to 700°C.

[0005]Furthermore, in order to improve the system efficiency of the fuel cell power generation device, the heat of the high-temperature combustion exhaust gas is recovered, and the heat of the combustion exhaust gas is recovered as shown in FIG. One equipped with a heat exchanger is known.

In FIG. 4, reference numeral 1 denotes a fuel reformer equipped with a reaction tube (not shown), and is equipped with a burner 2 at the top. Off-gas supplied from the fuel cell to the burner 2 via an off-gas supply system 3 is combusted by combustion air supplied to the burner via a combustion air supply system 4. The heat medium generated by this combustion heats the reaction tube, and then becomes combustion exhaust gas and is discharged outside the system via the combustion exhaust gas system 5.

At this time, the off-gas and the combustion air exchange heat with the high-temperature combustion exhaust gas in the heat exchanger 6, and their respective temperatures rise due to heat transfer from the combustion exhaust gas, and are supplied to the burner 2 where they are combusted. heat is recovered to improve system efficiency.

[0008]

[Problems to be Solved by the Invention] In the above system, the fuel reformer and heat exchanger are placed separately, so the configuration is complicated, and the entire device has a large number of devices and piping, and the assembly is also complicated. It has the disadvantage of becoming.

An object of the present invention is to provide a fuel reformer for a fuel cell that can simplify the entire device by integrating a fuel reformer and a heat exchanger.

0010

[Means for Solving the Problems] In order to solve the above problems, according to the present invention, there is provided an annular reaction tube filled with a reforming catalyst, and an annular reaction tube provided facing one inner end of the reaction tube. ,
A fuel cell that is equipped with a burner that burns off gas from the fuel cell using combustion air, and that heats a reaction tube with a heat medium generated by combustion in the burner to reform the reformed raw material flowing through the reaction tube into hydrogen-rich gas. In a fuel reformer for a fuel system, there is an annular exhaust gas flow path surrounding the reaction tube and through which the combustion exhaust gas discharged after heating the reaction tube flows, and an exhaust gas flow path arranged on both sides of the exhaust gas flow path. An annular off-gas flow path through which off-gas is supplied to the burner after heat exchange with the combustion exhaust gas flowing through the combustion exhaust gas, and an annular combustion air flow path through which combustion air flows.

[0011] The above-mentioned exhaust gas flow path, off-gas flow path, and combustion air flow path are filled with heat transfer particles that promote heat transfer.

0012

[Function] Heat can be exchanged between the annular exhaust gas passage surrounding the annular reaction tube and through which the combustion exhaust gas flows after heating the reaction tube, and the combustion exhaust gas flowing through the exhaust gas passages on both sides of this exhaust gas passage. By providing an annular off-gas flow path through which off-gas flows and an annular combustion-air flow path through which combustion air flows, off-gas and combustion air exchange heat with combustion exhaust gas, raise their temperature, and are supplied to the burner for combustion. It will be done.

FIG. 3 shows the flow when the above-mentioned off-gas and combustion air exchange heat with the combustion exhaust gas. In FIG. 3, the off-gas supplied to the fuel reformer 1 via the off-gas supply system 3 and the combustion air supplied via the combustion air supply system 4 are the combustion exhaust gas and the fuel reformer after heating a reaction tube (not shown). Heat is exchanged by flowing through the off-gas flow path, combustion air flow path, and combustion exhaust gas flow path provided around the reaction tube provided in 1, and as a result, the temperature rises and is supplied to the burner 2 where combustion occurs. be exposed. Note that the combustion exhaust gas after heat exchange is discharged to the outside via an external exhaust gas system 8.

[0014] By doing this, the heat exchanger is provided with means for exchanging heat between the combustion exhaust gas, off-gas, and combustion air, so that the entire apparatus is simplified.

[0015] By filling each of the above-mentioned exhaust gas flow path, off-gas flow path, and combustion air flow path with heat transfer particles, the combustion exhaust gas flowing through the exhaust gas flow path is separated from the off-gas flow path,
The heat transfer particles promote heat transfer to the off-gas and combustion air flowing through the combustion air flow path, respectively.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below based on the drawings. FIG. 1 is a sectional view of a fuel reformer according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. 1 and 2, the reaction tube 11 has an inner tube 13 and an outer tube 14 provided on both sides of an upright partition cylinder 12, and the lower end openings of the inner tube 13 and outer tube 14 are separated from the lower end of the partition cylinder 12. It consists of a closed bottom plate 15, and between the inner tube 13 and the outer tube 14, heat transfer particles 19 are filled in the upper half and reforming catalyst 16 is filled in the lower half. The upper end openings of the outer tube 14 and the partition cylinder 12 are the raw fuel inlet 17 through which raw fuel for methane as a reforming raw material flows into the reaction tube 11 together with water vapor, and the upper end openings of the inner tube 13 and the partition cylinder 12 are It serves as a reformed gas outlet 18 for the reformed gas flowing out from the reaction tube 11.

The burner 20 is provided facing the upper end opening inside the annular reaction tube 11, and the inside of the reaction tube 11 forms a combustion chamber 21.

The furnace vessel 22 has a bottom plate 23 provided apart from the lower end surface of the reaction tube 11 and surrounds the reaction tube 11. A combustion gas flow path 24 is formed through which combustion gas flows through the combustion chamber 21.

The exhaust gas inner tube 26 surrounds the side wall of the furnace vessel 22, and the exhaust gas outer tube 27 surrounds the exhaust gas inner tube 26, and the upper end openings of the furnace vessel 22 and the exhaust gas inner tube 26 and the outer tube 14 of the reaction tube 11 are connected to each other. The upper end opening of the exhaust gas outer pipe 27 is connected to the upper plate 2.
8, 29, and the exhaust gas inner pipe 26 and the exhaust gas outer pipe 2
7 forms an exhaust gas flow path 30 through which combustion exhaust gas flows. Note that the combustion gas flow path 24 and the exhaust gas flow path 30 communicate with each other at the upper portion, and the lower end opening of the exhaust gas flow path 30 serves as the exhaust gas outlet 32.

A combustion air passage 35 adjacent to the exhaust gas passage 30 through which combustion air flows is formed between the side wall of the furnace vessel 22 and the exhaust gas inner pipe 26, and the opening at the lower end of the combustion air passage 35 is a combustion air inlet. It is 37. Note that the upper plate 28 is provided with a combustion air outlet 38.

The off-gas outer pipe 40 surrounds the exhaust gas outer pipe 27, and between the off-gas outer pipe 40 and the exhaust gas outer pipe 27, an off-gas flow path 41 is formed through which the off-gas adjacent to the exhaust gas flow path 31 flows, and the upper end opening is at the upper end. It is closed with a plate 42. The lower end opening of the off-gas flow path 41 serves as an off-gas inlet 43 into which off-gas flows. Note that the upper plate 42 is provided with an off-gas outlet 44 through which off-gas is sent out.

Note that the exhaust gas flow path 30 and the combustion air flow path 3
5. The off-gas flow path 41 contains heat transfer particles 45, such as alumina particles, that promote heat transfer from the combustion exhaust gas flowing through the exhaust gas flow path 31 to the combustion air flow path 35 and the combustion air flowing through the off-gas flow path 42, respectively, to the off-gas. is filled.

The combustion air supply pipe 46 is connected to the combustion air outlet 38 and the burner 20 and guides the combustion air flowing through the combustion air passage 35 to the burner 20.

The off-gas supply pipe 47 is connected to the off-gas outlet 44 and the burner 20 and guides the off-gas flowing through the off-gas flow path to the burner 20.

With this structure, off-gas from the fuel cell flows in from the off-gas inlet 43 and flows into the off-gas flow path 4.
1 and flows upward through the off-gas supply pipe 47 to the burner 20.
supplied to And this off gas is the combustion air inlet 37
The combustion air flows upward through the combustion air flow path 35 and is supplied to the burner 20 via the combustion air supply pipe 46 to cause combustion.

Combustion gas generated by combustion in the burner 20 flows downward through the combustion chamber 21, turns back at the lower end of the reaction tube 11, and flows upward through the combustion gas passage 24 between the reaction tube 11 and the furnace vessel 22. , the exhaust gas passage 30 between the exhaust gas inner pipe 26 and the exhaust gas outer pipe 27 is folded back at the upper end, and the combustion air passage 35
The combustion air flowing through the off-gas flow path 41 flows downward in the opposite direction to the flow direction of the off-gas and is discharged to the outside from the exhaust gas outlet 32.

On the other hand, the raw fuel consisting of methane flows from the raw fuel inlet 17 together with water vapor, flows downward between the partition cylinder 12 and the outer tube 14 in the reaction tube 11 filled with the reforming catalyst 16, and flows downward through the partition. Fold back at the lower end of the cylinder 12 to partition the cylinder 12
The reformed gas flows upward between the reformed gas outlet 18 and the inner pipe 13, and is sent out to the outside from the reformed gas outlet 18. At this time, the raw fuel flowing through the reaction tube 11 is heated by the combustion gas flowing through the combustion chamber 21 and the combustion gas flow path 24, and is steam-reformed into hydrogen-rich gas.

By the way, the high-temperature combustion exhaust gas flowing through the exhaust gas flow path 30 via the combustion gas flow path 24 is connected to the combustion air and off gas flowing through the combustion air flow path 35 and off gas flow path 41 adjacent on both sides, and to the exhaust gas inner pipe 26, respectively. Exhaust gas outer pipe 2
The combustion air and off-gas are heated by exchanging heat with the combustion air and the off-gas.

Note that the exhaust gas flow path 30 and the combustion air flow path 3
5 and the off-gas flow path 41 are filled with heat transfer particles 45, so that heat transfer from the combustion exhaust gas to the combustion air and the off-gas is promoted.

[0030] In this way, the off-gas and combustion air are heated and supplied to the burner 20 for combustion.
Heat recovery from high-temperature combustion exhaust gas is performed well.

In this embodiment, the combustion air passage 35 is arranged inside the exhaust gas passage 30, and the off-gas passage 41 is arranged outside. The same effect can be obtained.

[0032]

Effects of the Invention As is clear from the above description, according to the present invention, there is provided an annular exhaust gas channel surrounding an annular reaction tube through which combustion exhaust gas flows, and an exhaust gas channel disposed across this channel. An annular off-gas flow path through which off-gas flows and which is supplied to the burner after exchanging heat with the combustion exhaust gas flowing through the combustion air flow path, and an annular combustion air flow path through which combustion air flows.
By filling the off-gas flow path and the combustion air flow path with heat-transfer particles, heat transfer is promoted by the heat-transfer particles, and the flow direction of the combustion exhaust gas, off-gas, and combustion air is reversed as in this example. Since the countercurrent type heat exchange is performed, the temperature of the off-gas and combustion air increases due to good heat exchange with the combustion exhaust gas, and the heat of the combustion exhaust gas is recovered as much as possible, improving system efficiency. Since the fuel reformer is equipped with a means for heat exchange between combustion air and off-gas, the number of equipment required for the entire system is reduced, and the number of parts such as piping is also reduced, making assembly easier and more compact. effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fuel reformer for a fuel cell according to an embodiment of the present invention.

[Figure 2] A-A sectional view of the fuel reformer for fuel cells in Figure 1

[
Figure 3: Flow diagram of the fuel reformer for fuel cells in Figure 1

[Figure 4]
System diagram of conventional heat exchanger and fuel reformer for fuel cells

[Explanation of symbols]

1 Fuel reformer 6 Heat exchanger 11 Reaction tube 16 Reforming catalyst 20 Burner 30 Exhaust gas flow path 35 Combustion air flow path 41 Off-gas flow path 45 Heat transfer particles

Claims (2)

[Claims] Claim 1: An annular reaction tube filled with a reforming catalyst, and a burner provided facing one inner end of the reaction tube to burn off gas from a fuel cell with combustion air, In a fuel reformer for a fuel cell, which heats a reaction tube with a heat medium generated by combustion in a burner to reform the reformed raw material flowing through the reaction tube into a hydrogen-rich gas, the reaction tube is surrounded by An annular exhaust gas flow path through which the combustion exhaust gas that is discharged after being heated flows, and an annular exhaust gas flow path that is arranged on both sides of this exhaust gas flow path, and after which the off-gas that is supplied to the burner flows after exchanging heat with the combustion exhaust gas flowing through the exhaust gas flow path. A fuel reformer for a fuel cell, comprising an annular off-gas flow path and an annular combustion air flow path through which combustion air flows. 2. The fuel reformer for fuel cells according to claim 1, wherein the annular exhaust gas flow path, offgas flow path, and combustion air flow path are filled with heat transfer particles that promote heat transfer. Fuel reformer for fuel cells.