Chemistry: electrical current producing apparatus – product – and – Having magnetic field feature
Reexamination Certificate
2003-03-20
2004-12-28
Gulakowski, Randy (Department: 1746)
Chemistry: electrical current producing apparatus, product, and
Having magnetic field feature
C429S010000, C429S006000, C422S186220, C422S198000, C422S211000, C048S094000
Reexamination Certificate
active
06835482
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel reforming apparatus for a polymer electrolyte membrane fuel cell.
2. Description of the Related Art
FIG. 20
shows as an example the construction of a conventional fuel reforming apparatus for a polymer electrolyte membrane fuel cell. As shown in the drawing, the conventional fuel reforming apparatus comprises a reformer A, a carbon monoxide converter B and a carbon monoxide selective oxidation reactor C.
Steam
6
, which is obtained as follows, is supplied into the reformer A. Specifically, water
5
within a gas-liquid separator
26
is introduced into an evaporator (steam generator)
13
, and a water-steam mixture
4
obtained by partially evaporating the water is introduced into the gas-liquid separator
26
so as to separate the mixture
4
into water
7
and steam
6
.
The steam
6
thus obtained is mixed with a reforming fuel
8
consisting of, for example, a natural gas in the reformer A, and the resultant mixture is introduced into a reforming catalyst layer
14
included in the reformer A. While the fuel
8
passes through the reforming catalyst layer
14
, a so-called “reforming reaction” to form hydrogen (H
2
), carbon monoxide (CO) and carbon dioxide (CO
2
) is carried out while the fuel
8
and the steam
6
pass through the reforming catalyst layer
14
. Since the reforming reaction is an endothermic reaction, hydrogen remaining in the fuel (exhaust gas) of the fuel cell stack (not shown) is burned in a burner
10
attached to the reformer A so as to generate heat within a burner space chamber
9
. The heat thus generated is transmitted to the reforming catalyst layer
14
within the reformer A so as to bring about the reforming reaction.
A center plug
11
for forming a radiation heat transmitting section
91
utilizing burner gas of a high temperature and a convection heat transmitting section
92
utilizing burner gas of a high and intermediate temperature is arranged within the burner space chamber
9
.
It should be noted that, in the fuel reforming apparatus of the polymer electrolyte membrane fuel cell, it is necessary to remove carbon monoxide formed by the reforming reaction because carbon monoxide markedly impairs the performance of the fuel cell stack even if carbon monoxide is contained in a very small amount. Such being the situation, the carbon monoxide converter B comprising a carbon monoxide converting catalyst layer
27
and a cooling device
28
buried in the carbon monoxide converting catalyst layer
27
and formed of a heat transmitting tube wound in, for example, a spiral form is arranged downstream of the reformer A in the conventional fuel reforming apparatus of the polymer electrolyte membrane fuel cell.
A reaction is carried out between carbon monoxide and steam within the carbon monoxide converting catalyst layer
27
so as to form hydrogen and carbon dioxide. Since this reaction is an exothermic reaction, the cooling device
28
is buried in the catalyst layer
27
so as to remove the heat generated by the exothermic reaction.
It should also be noted that the fuel gas coming from the reforming catalyst layer
14
has a high temperature and, thus, the fuel gas noted above is not adapted for the transforming reaction of carbon monoxide. Such being the situation, a cooling device
16
for cooling the inlet gas of the carbon monoxide converter (cooling device arranged upstream of the carbon monoxide converting catalyst layer) is arranged upstream of the carbon monoxide converting catalyst layer
27
. Also, in order to further remove carbon monoxide, which was left unreacted in the carbon monoxide converting catalyst layer
27
, the carbon monoxide selective oxidation reactor C consisting of a carbon monoxide selective oxidation catalyst layer
29
and a cooling device
30
buried in the carbon monoxide selective oxidation catalyst layer
29
are arranged downstream of the carbon monoxide converter B.
The air
2
is mixed with the reformed gas before entering the carbon monoxide selective oxidation catalyst layer
29
and, thus, oxygen contained in the air selectively carries out the reaction with carbon monoxide within the carbon monoxide selective oxidation catalyst layer
29
so as to form carbon dioxide, with the result that the carbon monoxide concentration is lowered to 10 ppm or less. In this case, hydrogen also reacts with oxygen so as to form steam. However, it is possible to suppress the reaction of hydrogen by the function of the catalyst if the air amount and the temperature of the catalyst layer are adjusted at appropriate values.
The carbon monoxide selective oxidation reaction is an exothermic reaction and, thus, the cooling device
30
is buried in the catalyst layer
29
in order to remove the heat generated by the exothermic reaction and to maintain the temperature at an appropriate value. Also, the gas passing through the carbon monoxide converting catalyst layer
27
is not adapted for the carbon monoxide selective oxidation reaction if the gas noted above is allowed to flow directly into the carbon monoxide selective oxidation catalyst layer
29
. Therefore, the cooling device
20
is mounted on the inlet port of the catalyst layer
29
for the carbon monoxide selective oxidation reaction so as to lower the temperature of the gas passing through the carbon monoxide converting catalyst layer
27
and, then, the gas with the lowered temperature is supplied into the catalyst layer
29
for the carbon monoxide selective oxidation.
As a method for combining and integrating the particular system for providing a single apparatus, a stacked type structure is proposed in, for example, a first prior art, i.e., Japanese Patent Disclosure No. 7-126001, and a second prior art, i.e., Japanese Patent Disclosure No. 7-133101. Each of these prior arts is directed to the case where, for example, methanol is used as raw fuel material. It is taught that the apparatuses such as a burner, a reformer, carbon monoxide converter, and a carbon monoxide selective oxidation reactor are successively stacked one upon the other so as to make it possible to utilize effectively the heat recovery in an evaporator, the endothermic reaction in the reformer, the exothermic reaction in each of the carbon monoxide converter and the carbon monoxide selective oxidation reactor in the case where the operating temperature in every apparatus is low and the temperature differences between the apparatuses is small such that the operating temperature of each of the reformer and the carbon monoxide converter is 200 to 300° C., the operating temperature of the carbon monoxide selective oxidation reactor is 150° C. and the operating temperature of the evaporator is 100 to 150° C. As a result, it is made possible to provide a reforming apparatus performing the function of steam-reforming, for example, methanol.
The body portion of the polymer electrolyte membrane fuel cell, in which electricity is generated by the reaction between hydrogen and oxygen carried out under a low temperature in the presence of a catalyst, can be made compact, compared with the body portion of another fuel cell, e.g., a phosphoric acid type fuel cell. In addition, since the operating temperature is low, the body portion of the polymer electrolyte membrane fuel cell is expected to be applied to, for example, a domestic power generating apparatus and an automatic vending machine.
However, in the conventional fuel reforming apparatus of the polymer electrolyte membrane fuel cell, the reactors included in the apparatus differ from each other in the required temperature level, as described above. Therefore, it was necessary to arrange individually the reformer, the cooling device at the inlet port of the carbon monoxide converter, the cooling device at the inlet port of the carbon monoxide selective oxidation reactor, and the carbon monoxide selective oxidation reactor and, then, to connect these apparatuses using pipes. Such being the situation, it was unavoidable for the fuel reforming apparatus to be re
Kawamoto Koichi
Miyoshi Michizo
Tanaka Masatoshi
Gulakowski Randy
Oblon, Spivak, McClelland, Maier & Neustadt PC
Winter Gentle E.
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