Chemistry: electrical current producing apparatus – product – and – Having magnetic field feature
Reexamination Certificate
2001-06-20
2004-09-07
Bell, Bruce F. (Department: 1746)
Chemistry: electrical current producing apparatus, product, and
Having magnetic field feature
C429S006000, C429S006000
Reexamination Certificate
active
06787255
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power generating system using a fuel cell which generates a fuel gas containing a hydrogen gas by reforming fuel such as a natural gas with steam, and generates power by reacting the fuel gas with an oxidizing gas, such as oxygen in the air, by electrochemical reaction, and an operation method for the system.
This application is based on Japanese Patent Application Nos. 2000-185355 and 2000-185356, the content of which are incorporated herein by reference.
2. Description of the Related Art
A fuel cell power generating system typically uses coolant, which adjusts the temperature inside a fuel cell stack, in order to keep the power generating efficiency of the fuel cell high. The coolant is normally subjected to demineralization before usage.
FIG. 6
exemplifies a fuel cell power generating system, which comprises a fuel cell unit
1
, a water storage tank
2
for water which serves as the coolant for the fuel cell unit
1
, a water treatment system
3
which performs purification of the water in the water storage tank
2
and supplies the resultant water as coolant to the fuel cell unit
1
, a heat exchanger
4
for recovering the exhaust heat which heats water using the exhaust heat from the fuel cell unit
1
, a hot water storage tank
5
which retains hot water obtained by using the heat exchanger
4
, and a auxiliary water supply path
42
which supplies auxiliary water to the water storage tank
2
.
The fuel cell unit
1
has a heat exchanger
17
for recovering the condensed water in the exhaust gas which recovers steam in the exhaust gas as condensed water.
The water treatment system
3
has water purifying equipment
19
such as an ion-exchange demineralizer, and a water feed pump P
1
.
The hot water storage tank
5
is constructed in such a way as to be able to feed hot water in the tank to a heat using equipment (not shown).
In the fuel cell power generating system, the fuel cell unit
1
generates a fuel gas containing a hydrogen gas by reforming fuel such as natural gas with steam and generates power by reacting the fuel gas with an oxidizing gas, such as atmospheric oxygen by electrochemical reaction, and the heat exchanger
17
condenses the steam in the exhaust gas by cooling it down, recovers the condensed water and retains it in the water storage tank
2
. Auxiliary water, such as city water, is supplied into the water storage tank
2
through the auxiliary water supply path
42
.
Ions (carbonate ions, metal ions or the like) or a solid material, which are originated from auxiliary water, such as city water, are fed in the water storage tank
2
as impurities, and the supply water in the water storage tank
2
is supplied to the fuel cell unit
1
as coolant after the impurities are removed by the water purifying equipment
19
of the water treatment system
3
. This can prevent the occurrence of scaling or the like in a coolant circulation path.
Because a large load is applied to the water purifying equipment
19
in the fuel cell power generating system, however, the water purifying equipment
19
in use can be complex and large, thus resulting in a large increase in equipment cost. In a case where an ion-exchange demineralizer is used, for example, the operation cost, such as a regenerating cost, increases.
FIG. 7
shows another example of the fuel cell power generating system. The system comprises fuel cell power generating equipment
61
which generates power by reacting fuel gas containing a hydrogen gas with an oxidizing gas by electrochemical reaction, a hot water storage tank
52
which retains hot water heated up by using the heat generated at the time power is generated by the power generating equipment
61
, and a auxiliary water supply path
69
which supplies auxiliary water, such as city water, to the hot water storage tank
52
.
The fuel cell power generating equipment
61
has a fuel cell stack
53
, a coolant circulation path
64
which regulates the temperature of the fuel cell stack
53
, a heat exchanger
65
for recovering water which condenses and recovers steam in the exhaust gas discharged from the fuel cell stack
53
, a water storage tank
56
which retains supply water recovered by the heat exchanger
65
, water purifying equipment
57
which purifies the supply water in the water storage tank
56
and supplies the purified water as coolant to the coolant circulation path
64
, an heat exchanger
58
which heats up and makes water hot using the coolant, and a auxiliary water supply path
70
which supplies auxiliary water, such as city water, to the water storage tank
56
.
The fuel cell stack
53
is designed to have an electrolyte
73
sandwiched between a anode
71
and an cathode
72
. Electrode plates
74
and
75
are respectively provided between the anode
71
and the electrolyte
73
and between the cathode
72
and the electrolyte
73
.
An ion-exchange demineralizer or the like, which removes impurities from the supply water from the water storage tank
56
, is used as the water purifying equipment
57
.
The hot water storage tank
52
can supply hot water in the tank to heat using equipment (not shown).
The fuel cell power generating system allows a reformer (not shown) to reform fuel such as a natural gas with steam, thus generating a fuel gas containing a hydrogen gas, supplies the fuel gas to the anode
71
through a fuel-gas supply path
76
, and supplies an oxidizing gas, such as air, to the cathode
72
through an oxidizing-gas supply path
77
, so that the fuel gas reacts with the oxidizing gas electrochemically, thereby generating power.
The fuel-based exhaust gas from the reformer is discharged outside the system via the heat exchanger
65
through an exhaust path
78
. The oxidant-based exhaust gas from the cathode
72
travels through an exhaust path
79
, merges with fuel-based exhaust gas in the exhaust path
78
, and is discharged outside the system via the heat exchanger
65
.
As the coolant circulates in the coolant circulation path
64
, the fuel cell stack
53
is cooled down to maintain the pre-set temperature. At this time, the coolant is heated to a high temperature (normally 60 to 80° C.) and is led into the heat exchanger
58
.
In the heat exchanger
58
, the hot coolant heats up the water in the hot water storage tank
52
and makes it as hot as about 50 to 60° C. The coolant that has passed through the heat exchanger
58
is led into the exchanger
65
through the path
66
, and is then led into the water storage tank
56
through the path
67
.
In the exchanger
65
, the steam in the fuel-based exhaust gas and oxidant-based exhaust gas in the exhaust path
78
is cooled and condensed by the coolant, and the condensed water is recovered into the water storage tank
56
through the path
62
. When the supply water in the water storage tank
56
becomes insufficient, auxiliary water such as city water is provided as a supplement through the auxiliary water supply path
70
.
Carbonate ions or metal ions for example, originated from auxiliary water, such as city water, are fed in supply water in the water storage tank
56
as impurities, and the supply water is supplied to the coolant circulation path
64
in the fuel cell stack
53
as coolant through a supply path
63
after impurities are removed by the water purifying equipment
57
. This can prevent the occurrence of scaling or the like in the coolant circulation path
64
.
Because a large load is applied to the water purifying equipment
57
in the fuel cell power generating system, however, the water purifying equipment
57
in use can be complex and large, thus increasing the equipment cost. There is another problem that the operation cost, such as the regenerating cost for an ion exchange resin, increases.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a fuel cell power generating system and an operation method therefore, which can reduce the equipment cost and the operation cost.
To achieve the above object, acc
Bell Bruce F.
Kurita Water Industries, Ltd
Scully Scott Murphy & Presser
Wills Monique
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