U.S. patent application number 10/508560 was filed with the patent office on 2005-07-14 for fuel cell generation apparatus.
Invention is credited to Fujihara, Seiji, Taguchi, Kiyoshi, Ukai, Kunihiro, Wakita, Hidenobu.
Application Number | 20050153179 10/508560 |
Document ID | / |
Family ID | 31190326 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050153179 |
Kind Code |
A1 |
Ukai, Kunihiro ; et
al. |
July 14, 2005 |
Fuel cell generation apparatus
Abstract
The present invention provides a fuel cell system comprising a
hydrogen generator (1) which generates hydrogen gas by allowing a
source material to undergo a reforming reaction and a fuel cell (3)
which is equipped with a anode and an cathode and which generates
electric power by allowing the hydrogen gas supplied to the anode
and oxygen gas supplied to the cathode to react electrochemically
with each other. The fuel cell system further comprises a water
recovering portion (5) configured to recover water from water vapor
discharged from at least one of the fuel and cathodes, a water
storing portion (6) which is equipped with a tank (6a) for storing
water recovered by the water recovering portion (5), and a water
supply portion (10) configured to supply water stored in the tank
(6a) to the hydrogen generator (1), wherein the tank (6a) is
configured, in order to prevent water stored in the tank (6a) from
decaying, such that the stored water is dischargable to the
outside, and wherein the fuel cell system is so configured as to
make a decision on whether or not to discharge the stored water to
the outside for the prevention of water decay.
Inventors: |
Ukai, Kunihiro; (Nara,
JP) ; Taguchi, Kiyoshi; (Osaka, JP) ; Wakita,
Hidenobu; (Kyoto, JP) ; Fujihara, Seiji;
(Osaka, JP) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103
US
|
Family ID: |
31190326 |
Appl. No.: |
10/508560 |
Filed: |
September 22, 2004 |
PCT Filed: |
July 30, 2003 |
PCT NO: |
PCT/JP03/09629 |
Current U.S.
Class: |
429/410 ;
429/414; 429/423; 429/442; 429/450 |
Current CPC
Class: |
H01M 8/04156 20130101;
H01M 8/0612 20130101; Y02E 60/50 20130101 |
Class at
Publication: |
429/022 ;
429/019; 429/034; 429/026 |
International
Class: |
H01M 008/04; H01M
008/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2002 |
JP |
2002-221270 |
Feb 5, 2003 |
JP |
2003-28033 |
Claims
We claim:
1. A fuel cell system comprising: a hydrogen generator configured
to generate hydrogen gas by allowing a source material to undergo a
reforming reaction; a fuel cell equipped with a anode and an
cathode and configured to generate electric power by allowing the
hydrogen gas supplied to the anode and oxygen gas supplied to the
cathode to react electrochemically with each other; a water
recovering portion configured to recover water from water vapor
discharged from at least one of the fuel and cathodes; a water
storing portion which is equipped with a tank for storing water
recovered by said water recovering portion; and a water supply
portion configured to supply water stored in the tank to said
hydrogen generator, wherein: the tank is configured, in order to
prevent water stored in the tank from decaying, such that the
stored water is dischargable to the outside, and said fuel cell
system is so configured as to make a decision on whether or not to
discharge the stored water to the outside for the prevention of
water decay.
2. The fuel cell system as set forth in claim 1 further comprising
a discharge prompting information output portion configured to
output, when it is decided that water stored in the tank is to be
discharged outside, discharge prompting information indicative of
the discharging of the stored water to the outside.
3. The fuel cell system as set forth in claim 2, wherein said fuel
cell system is so configured as to make, on the basis of the
accumulated operating time of said fuel cell system, a decision on
whether or not to discharge the stored water to the outside.
4. The fuel cell system as set forth in claim 2, wherein said fuel
cell system is so configured as to make, on the basis of the
accumulated downtime of said fuel cell system, a decision on
whether or not to discharge the stored water to the outside.
5. The fuel cell system as set forth in claim 2, wherein: said
water supply portion has a pump for transporting water stored in
the tank, a filter, disposed between the tank and the pump, for
water purification, and said fuel cell system is so configured as
to make, on the basis of a flow rate of water output from the pump,
a decision on whether or not to discharge the stored water to the
outside.
6. The fuel cell system as set forth in claim 2, wherein: said
water supply portion has a pump for transporting water stored in
the tank, a filter, disposed between the tank and the pump, for
water purification, and said fuel cell system is so configured as
to make, on the basis of the operating state of the pump, a
decision on whether or not to discharge the stored water to the
outside.
7. The fuel cell system as set forth in claim 1, wherein the inside
of the tank is dried after the discharging of the water stored in
the tank to the outside.
8. The fuel cell system as set forth in claim 7 further comprising
a heater for heating the tank, wherein the inside of the tank is
dried by application of heat to the tank by said heater.
9. The fuel cell system as set forth in claim 8, wherein said
heater heats the tank at a temperature within the range of 100 to
130 degrees Centigrade.
10. The fuel cell system as set forth in claim 8, wherein said
heater heats the tank when water is stored in the tank.
11. The fuel cell system as set forth in claim 10 further
comprising: a water purifier for water purification, and a cooler
for cooling water heated by said heater, wherein said water supply
portion supplies water cooled by said cooler to said hydrogen
generator through said water purifier.
12. The fuel cell system as set forth in claim 10, wherein the tank
is provided with an openable and closable exhaust opening so that
gas generated by heating by said heater is dischargable to the
outside.
13. The fuel cell system as set forth in claim 12 wherein gas
discharged from the tank is supplied to said hydrogen
generator.
14. The fuel cell system as set forth in claim 7, wherein: the tank
is supplied with water from the outside, and after the discharging
of the stored water in the tank to the outside, the inside of the
tank is cleaned by a supply of water to the tank from the outside,
and thereafter the inside of the tank is dried.
15. The fuel cell system as set forth in claim 14, wherein the
concentration of chlorine in said water supplied from the outside
falls within the range of 0.1 to 5 mg/l.
16. The fuel cell system as set forth in claim 1, wherein: the tank
is supplied with water from the outside, and after the discharging
of the stored water in the tank to the outside, the inside of the
tank is cleaned by a supply of water to the tank from the
outside.
17. The fuel cell system as set forth in claim 2, wherein: said
water storing portion has a plurality of tanks which sequentially
store water, and said fuel cell system is so configured as to make
a decision on whether or not to discharge water, stored in a tank
of the plurality of tanks which is not storing water, to the
outside.
18. The fuel cell system as set forth in claim 17, wherein the
inside of the tank is dried after the discharging of the water
stored in the tank to the outside.
19. The fuel cell system as set forth in claim 18 further
comprising a heater for heating the tank, wherein the inside of the
tank is dried by application of heat to the tank by said
heater.
20. The fuel cell system as set forth in claim 1 further comprising
a gas drawing portion for drawing gas into the tank from the
outside.
21. The fuel cell system as set forth in claim 20, wherein a filter
for removing solid impurity components from gas is disposed
upstream of said gas drawing portion relative to the direction in
which the gas flows.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Section 371 of International
Application No. PCT/JP2003/009629, filed Jul. 30, 2003, and the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a fuel cell system provided with a
fuel cell which produces electric power by making utilization of
hydrogen gas. More specifically, the invention provides a fuel cell
system capable of preventing water recovered from such a type of
fuel cell from decaying.
[0003] With recent increasingly growing recognition of the
importance of the global environment protection, fuel cell systems
which are small in size but are capable of producing electric power
at high levels of efficiency have attracted attention. In addition,
when a fuel cell system produces electric power, thermal energy is
generated. Accordingly, it is hoped that high levels of energy
utilization efficiency are achieved through the use of such thermal
energy.
[0004] Most of the fuel cell systems of the above-described type
use hydrogen for fuel and generate electric power. However, the
infrastructure needed for supplying hydrogen to fuel cell systems
has still not been provided at present. Consequently, the following
procedure has been employed commonly. That is to say, the procedure
uses fossil fuels such as natural gas, and hydrogen gas is
generated by causing a reforming reaction to take place in the fuel
cell system.
[0005] Besides, the above-mentioned reforming reaction requires the
provision of water, which means that it is very important to secure
a water supply source which supplies water to a fuel cell system.
In the case where a water infrastructure is always used as a water
supply source, the removal of component parts of calcium, chlorine
et cetera from the water supplied from the water infrastructure is
required. To this end, the fuel cell system has to have a water
purifying means (e.g., ion exchange resin) more powerful than
usual. This necessitates the execution of regular maintenance work
on the water purifying means. As just described, the arrangement
that water is always supplied from a water infrastructure gives
rise to many disadvantages. In the light of this, for the case of a
fuel cell system of a so-called distributed type that is installed
in the vicinity of an area in demand of electric power and thermal
energy, the procedure of recovering water generated in the inside
of the system and making utilization of it, i.e., the water
self-supplying procedure, has been employed often.
[0006] However, the water recovered in the inside of the fuel cell
system does not contain any bactericidal substances such as the
component parts of chlorine but does contain undesirable germs and
their necessary nourishment. This increases the possibility that
the recovered water decays. If the recovered water decays, this
will give rise to flow path blockage in a water recovering portion
or in a water supply portion, thereby producing problems with the
water supply.
[0007] With a view to eliminating these drawbacks, there have been
made several proposals. For example, there is a first method in
which organic materials are decomposed and germ-eradicated by
blowing ozone generated by an ozone generator into the recovered
water. In addition, in a second method, various germs are
eradicated by exposure of the recovered water to ultraviolet
irradiation. Furthermore, there is proposed a third method in
which, in order to prevent the recovered water from decaying, both
a water recovering portion and a water supply portion are formed of
material having an antibacterial action. For example, Japanese
Patent Application Kokai Publication No. 1996-22833 discloses an
exemplary case in which both a water recovering portion and a water
supply portion are formed using metal having an antibacterial
action.
[0008] However, both the first method (i.e., ozone blowing) and the
second method (i.e., ultraviolet irradiation) find it difficult to
utterly decompose and remove organic materials contained in the
recovered water. Besides, if there are members and pipes which come
to contact with ozone or are irradiated with ultraviolet light and
which are formed of resin material, these components deteriorate
significantly, therefore producing another problem that water
leakage will occur. Furthermore, if ozone blowing or ultraviolet
irradiation has not been carried out over a long period of time,
this increases the possibility that the degree of water decay
becomes progressively worse by residual component parts. For
example, when the fuel cell system has been taken out of operation
for a long period of time, neither ozone blowing nor ultraviolet
irradiation can be carried out, therefore producing the problem
that the decay of water becomes progressively worse.
[0009] On the other hand, in accordance with the third method, both
an apparatus for water recovery and an apparatus for water supply
are formed of material having an antibacterial action. This makes
it possible to effectively preventing the recovered water from
decaying. However, since the elution of antibacterial component
parts cannot be controlled, the result may be that antibacterial
effects cannot be obtained as expected depending the use
conditions. In addition, there is a likelihood that antibacterial
effects are not exhibited at all depending on the type of bacteria.
Besides, there is another problem that the load to a purifying
means for recovered water purification, especially the load to an
ion exchange resin, increases.
BRIEF SUMMARY OF THE INVENTION
[0010] Bearing in mind the above-described problems, the present
invention was made. Accordingly, an object of the present invention
is to provide an improved fuel cell system capable of avoiding the
occurrence of flow path blockage due to the decay of recovered
water and capable of providing a supply of water in a stable manner
by ensuring that the recovered water is prevented from
decaying.
[0011] In order to solve the above-described problems, the present
invention provides a fuel cell system. The fuel cell system of the
present invention comprises a hydrogen generator configured to
generate hydrogen gas by allowing a source material to undergo a
reforming reaction and a fuel cell equipped with a anode and an
cathode and configured to generate electric power by allowing the
hydrogen gas supplied to the anode and oxygen gas supplied to the
cathode to react electrochemically with each other, and further
comprises a water recovering portion configured to recover water
from water vapor discharged from at least one of the fuel and
cathodes, a water storing portion which is equipped with a tank for
storing water recovered by the water recovering portion, and a
water supply portion configured to supply water stored in the tank
to the hydrogen generator, wherein the tank is configured, in order
to prevent water stored in the tank from decaying, such that the
stored water is dischargable to the outside, and wherein the fuel
cell system is so configured as to make a decision on whether or
not to discharge the stored water to the outside for the prevention
of water decay.
[0012] In addition, preferably the fuel cell system of the
aforesaid invention further comprises a discharge prompting
information output portion configured to output, when it is decided
that water stored in the tank is to be discharged outside,
discharge prompting information indicative of the discharging of
the stored water to the outside.
[0013] Furthermore, preferably the fuel cell system of the
aforesaid invention is so configured as to make, on the basis of
the accumulated operating time of the fuel cell system, a decision
on whether or not to discharge the stored water to the outside.
[0014] In addition, preferably the fuel cell system of the
aforesaid invention is so configured as to make, on the basis of
the accumulated downtime of the fuel cell system, a decision on
whether or not to discharge the stored water to the outside.
[0015] Furthermore, preferably in the fuel cell system of the
aforesaid invention the water supply portion has a pump for
transporting water stored in the tank, a filter, disposed between
the tank and the pump, for water purification, and the fuel cell
system is so configured as to make, on the basis of a flow rate of
water output from the pump, a decision on whether or not to
discharge the stored water to the outside.
[0016] In addition, preferably in fuel cell system of the aforesaid
invention the water supply portion has a pump for transporting
water stored in the tank, a filter, disposed between the tank and
the pump, for water purification, and the fuel cell system is so
configured as to make, on the basis of the operating state of the
pump, a decision on whether or not to discharge the stored water to
the outside.
[0017] Furthermore, preferably in the fuel cell system of the
aforesaid invention the inside of the tank is dried after the
discharging of the water stored in the tank to the outside.
[0018] In addition, preferably the fuel cell system of the
aforesaid invention further comprises a heater for heating the
tank, wherein the inside of the tank is dried by application of
heat to the tank by the heater.
[0019] Furthermore, preferably in the fuel cell system of the
aforesaid invention the heater heats the tank at a temperature
within the range of 100 to 130 degrees Centigrade.
[0020] In addition, preferably in the fuel cell system of the
aforesaid invention the heater heats the tank when water is stored
in the tank.
[0021] Furthermore, preferably the fuel cell system of the
aforesaid invention further comprises a water purifier for water
purification and a cooler for cooling water heated by the heater,
wherein the water supply portion supplies water cooled by the
cooler to the hydrogen generator through the water purifier.
[0022] In addition, preferably in the fuel cell system of the
aforesaid invention the tank is provided with an openable and
closable exhaust opening so that gas generated by heating by the
heater is dischargable to the outside.
[0023] Furthermore, preferably in the fuel cell system of the
aforesaid invention gas discharged from the tank is supplied to the
hydrogen generator.
[0024] In addition, preferably in the fuel cell system of the
aforesaid invention the tank is supplied with water from the
outside, and after the discharging of the stored water in the tank
to the outside, the inside of the tank is cleaned by a supply of
water to the tank, and thereafter the inside of the tank is
dried.
[0025] Furthermore, preferably in the fuel cell system of the
aforesaid invention the concentration of chlorine in the water
supplied from the outside falls within the range of 0.1 to 5
mg/l.
[0026] In addition, preferably in the fuel cell system of the
aforesaid invention the tank is supplied with water from the
outside, and after the discharging of the stored water in the tank
to the outside, the inside of the tank is cleaned by a supply of
water to the tank from the outside.
[0027] Furthermore, preferably in the fuel cell system of the
aforesaid invention the water storing portion has a plurality of
tanks which sequentially store water, and the fuel cell system is
so configured as to make a decision on whether or not to discharge
water, stored in a tank of the plural tanks which is not storing
water, to the outside.
[0028] In addition, preferably in the fuel cell system of the
aforesaid invention the inside of the tank is dried after the
discharging of the water stored in the tank to the outside.
[0029] Furthermore, preferably the fuel cell system of the
aforesaid invention further comprises a heater for heating the
tank, wherein the inside of the tank is dried by application of
heat to the tank by the heater.
[0030] In addition, preferably the fuel cell system of the
aforesaid invention further comprises a gas drawing portion for
drawing gas into the tank from the outside.
[0031] Furthermore, preferably in the fuel cell system of the
aforesaid invention a filter for removing solid impurity components
from gas is disposed upstream of the gas drawing portion relative
to the direction in which the gas flows.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0032] The foregoing summary, as well as the following detailed
description of the invention, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustrating the invention, there are shown in the drawings
embodiments which are presently preferred. It should be understood,
however, that the invention is not limited to the precise
arrangements and instrumentalities shown.
[0033] In the drawings:
[0034] FIG. 1 is a block diagram showing a constructional
arrangement of a fuel cell system according to a first embodiment
of the present invention;
[0035] FIG. 2 is a flow chart showing steps of a procedure of a
controller of the fuel cell system of the first embodiment of the
present invention;
[0036] FIG. 3 is a flow chart showing steps of a procedure of a
controller of a fuel cell system according to a second embodiment
of the present invention;
[0037] FIG. 4 is a block diagram showing a constructional
arrangement of a fuel cell system according to a third embodiment
of the present invention;
[0038] FIG. 5 is a flow chart showing steps of a procedure of a
controller of the fuel cell system of the third embodiment of the
present invention;
[0039] FIG. 6 is a flow chart showing steps of a procedure of a
controller 7 of a fuel cell system according to a fourth embodiment
of the present invention;
[0040] FIG. 7 is a block diagram showing a constructional
arrangement of a fuel cell system according to a fifth embodiment
of the present invention;
[0041] FIG. 8 is a flow chart showing steps of a procedure of a
controller of a fuel cell system according to a sixth embodiment of
the present invention;
[0042] FIG. 9 is a block diagram showing a constructional
arrangement of a fuel cell system according to a seventh embodiment
of the present invention;
[0043] FIG. 10 is a flow chart showing steps of a procedure of a
controller 7 of the fuel cell system according of the seventh
embodiment of the present invention;
[0044] FIG. 11 is a block diagram showing a constructional
arrangement of a fuel cell system according to an eighth embodiment
of the present invention;
[0045] FIG. 12 is a block diagram showing a constructional
arrangement of a fuel cell system according to a ninth embodiment
of the present invention;
[0046] FIG. 13 is a block diagram showing a constructional
arrangement of a fuel cell system according to a tenth embodiment
of the present invention;
[0047] FIG. 14 is a block diagram showing a constructional
arrangement of a fuel cell system according to an eleventh
embodiment of the present invention; and
[0048] FIG. 15 is a block diagram showing a constructional
arrangement of a fuel cell system according to a twelfth embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0049] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings.
Embodiment 1
[0050] Referring to FIG. 1, there is shown a block diagram
illustrating a constructional arrangement of a fuel cell system
according to a first embodiment of the present invention. As shown
in FIG. 1, the fuel cell system of the first embodiment is provided
with a hydrogen generator 1 adapted to generate hydrogen gas mainly
by acceleration of a reforming reaction through the use of a source
material (such as a hydrocarbon component part of natural gas, LP
gas et cetera, alcohol (e.g., methanol), naphtha et cetera) and
water vapor. The hydrogen generator 1 is made mainly up of a
reformer 1a for accelerating a reforming reaction as described
above, a CO shifter 1b for reducing the concentration of carbon
monoxide in hydrogen gas after a reforming reaction in the reformer
1a, and a CO removing portion 1c. And, the reformer 1a is provided
with a reforming heater (not shown) which supplies the heat
necessary for the reforming reaction. The reforming heater is
provided with a flame burner for burning a part of the source
material or for burning gas returned from where the hydrogen gas
was supplied, and a sirocco fan for supplying combustion air.
[0051] The hydrogen generator 1 is connected to a material feed
portion 2 which supplies the hydrogen generator 1 with a source
material and to a fuel cell 3 of the proton-exchange membrane type.
The material feed portion 2 receives natural gas from, for example,
a gas infrastructure and supplies it to the hydrogen generator
1.
[0052] In addition, the fuel cell 3 produces electric power by
making use of hydrogen gas supplied to the anode (anode) side from
the hydrogen generator 1 and air supplied to the cathode (cathode)
side from a blower 4. And, in the present embodiment, the fuel cell
3 is of the proton-exchange membrane type, which, however, should
not in any way be deemed restrictive. The heat, produced when the
fuel cell 3 generates electricity, is recovered and utilized in
water heating equipment, heating equipment et cetera through an
appropriate heat medium. By means of this, the fuel cell 3
functions as a cogeneration apparatus capable of generation of
electric power and heat.
[0053] The fuel cell 3 is connected to a water recovering portion 5
which is made up of an air cooling fan and other components. The
water recovering portion 5 recovers moisture contained in hydrogen
gas discharged from the anode of the fuel cell 3 and moisture
contained in air discharged from the cathode of the fuel cell 3.
The water recovering portion 5 is connected to the hydrogen
generator 1 and supplies hydrogen gas discharged from the anode of
the fuel cell 3 to the hydrogen generator 1. Furthermore, the water
recovering portion 5 is connected also to a water storing portion 6
which will be described later, and supplies water recovered in the
way as descried above to the water storing portion 6.
[0054] The water storing portion 6 is provided with a tank 6a
adapted to store water supplied from the water recovering portion
5. In addition, the water storing portion 6 is further provided
with an openable and closable drain opening 8, thereby allowing the
stored water to flow out through the drain opening 8 for the
prevention of water decay, as will be described later.
[0055] And now, in order to force the water held in the tank 6a to
flow out through the drain opening 8, it is necessary to draw gas
into the tank 6a. To this end, the water storing portion 6 is
provided with a gas drawing opening 31 for drawing gas into the
tank 6a.
[0056] If gas drawn into the inside of the tank 6a through the gas
drawing opening 31 contains undesirable germs and their necessary
nourishment, this increases the possibility that the water held
within the tank 6a decays. To cope with this, the gas drawing
opening 31 is connected to a filter 32 which is disposed upstream
relative to the gas flowing direction for the removal of solid
contaminants contained in the gas.
[0057] Furthermore, the water storing portion 6 is in connection
with a water supply valve 9 for supplying water provided from a
water infrastructure into the tank 6a, so that a supply of water is
provided to the tank 6a by way of the water supply valve 9 if
required.
[0058] When the concentration of chlorine in the water which is
supplied to the tank 6a via the water supply valve 9 is relatively
low, bactericidal effects with respect to the water held in the
tank 6a is weak. On the other hand, when the chlorine concentration
is relatively high, pipes and constructional members of the tank 6a
through which water flows undergo significant deterioration. In the
light of this, preferably the concentration of chlorine in the
water which is supplied to the tank 6a from the outside through the
water supply valve 9 falls within the range of about 0.1 to about 5
mg/l.
[0059] The water storing portion 6 is connected to a water purifier
11 comprising a filter 11a such as an ion exchange resin, an
activated carbon et cetera and to a water supply portion 10
comprising a pump 10a for water transportation. The water supply
portion 10 delivers to the hydrogen generator 1 the water supplied
from the water storing portion 6 through the water purifier 11. The
water thus supplied will be used for a reforming reaction in the
hydrogen generator 1.
[0060] In the present embodiment, the water held in the water
storing portion 6 is used for a reforming reaction; however, it may
be used for humidification of fuel gas or oxidant gas or in other
water utilizing means.
[0061] Furthermore, the fuel cell system of the present embodiment
is further provided with a display portion 30 which displays
discharge prompting information requesting the user or maintenance
service provider to discharge the water held in the tank 6a from
the drain opening 8. The display portion 30 is formed by a liquid
crystal display or by a light emitting diode. For the case of the
fuel cell system of the present embodiment, the user visually
acquires such a discharge prompting information message, which,
however, should not in any way be deemed restrictive. For example,
the discharge prompting information is outputted outside in the
form of a voice message, thereby allowing the user to acoustically
acquire the information.
[0062] The foregoing units, namely the hydrogen generator 1, the
material feed portion 2, the fuel cell 3, the blower 4, the water
recovering portion 5, the water storing portion 6, the water supply
valve 9, the water supply portion 10, and the display portion 30,
are all connected to a controller 7, and each unit operates in
response to a control signal outputted from the controller 7.
[0063] The controller 7 is provided with a memory 7a having a
predetermined storage area. The memory 7a stores programs that the
controller 7 executes and various data.
[0064] Next, the operation of the fuel cell system of the first
embodiment of the present invention having the above-described
configuration will be described below.
[0065] The reformer 1a of the hydrogen generator 1 performs a
reforming reaction of converting a natural gas supplied from the
material feed portion 2 and water supplied from the water supply
portion 10 in the way as will be describe below, into hydrogen and
carbon dioxide. In order to achieve the acceleration of a reforming
reaction, heating is carried out by the reforming heating part
during the reforming reaction. And, in order to reduce the
concentration of carbon monoxide contained in hydrogen gas, a
transformation reaction for allowing CO to react with water is
carried out in the CO shifter 1b. In addition, for the purpose of
reducing the carbon monoxide concentration, a selective oxidation
reaction is carried out in the CO removing portion 1c by addition
of air. Hydrogen gas is generated after the aforesaid reforming,
transformation, selective oxidation reactions.
[0066] The hydrogen generator 1 supplies the hydrogen gas thus
generated to the anode side of the fuel cell 3. Meanwhile, the
blower 4 supplies a stream of air to the cathode side of the fuel
cell 3. Alternatively, it may be arranged such that the blower 4
supplies air humidified in the water recovering portion 5 to the
fuel cell 3.
[0067] The fuel cell 3 generates water and electric power by
allowing hydrogen gas supplied to the anode side from the hydrogen
generator 1 and oxygen contained in air supplied to the cathode
side from the blower 4 to react electrochemically with each
other.
[0068] In addition, in the fuel cell 3, hydrogen gas is discharged
from the anode while air is discharged from the cathode. As
described above, the discharged hydrogen gas and air contain water
produced when generating electric power. The water recovering
portion 5 recovers moisture contained in the hydrogen gas and air
discharged from the fuel cell 3 and condenses the recovered
moisture for delivery to the water storing portion 6.
[0069] Furthermore, after recovering moisture from hydrogen gas
discharged from the anode, the water recovering portion 5 supplies
the hydrogen gas to the hydrogen generator 1. The hydrogen gas thus
supplied to the hydrogen generator 1 is used as a heat source in
the reforming heating part of the reformer 1a of the hydrogen
generator 1.
[0070] Instead of employing the aforesaid arrangement of supplying
hydrogen gas discharged from the anode through the water recovering
portion 5 to the hydrogen generator 1, another arrangement may be
employed in which hydrogen gas is supplied directly to the hydrogen
generator 1 from the fuel cell 3 so that it is utilized as a heat
source for the reforming heating part. In this arrangement, the
hydrogen gas utilized by the reforming heating part is supplied to
the water recovering portion 5 for moisture recovery.
[0071] In the water storing portion 6, water delivered from the
water recovering portion 5 is stored in the tank 6a. The water thus
stored in the tank 6a is supplied, through the water purifier 11,
to the water supply portion 10. The water supply portion 10
transports the water to the hydrogen generator 1 by the action of
the pump 10a. In this way, the water delivered from the water
supply portion 10 is used for a reforming reaction in the reformer
1a of the hydrogen generator 1.
[0072] As has been described above, the water discharged from the
fuel cell 3 is recovered by the water recovering portion 5.
Thereafter, the water is stored in the tank 6a of the water storing
portion 6 and then is supplied, through the water purifier 11 and
through the water supply portion 10, to the hydrogen generator 1.
Here, the possibility that the water recovered in the inside of the
fuel cell system decays is high because it contains no
antibacterial component parts such as chlorine component parts. For
example, undesirable germs and their necessary nourishment
contained in the air discharged from the cathode may often remain
intact in the recovered water, and the recovered water consequently
decays. This causes flow path blockage or other trouble in a water
collecting construction or in a water supply construction, thereby
producing water supply problems. In order to prevent the problems,
in the fuel cell system of the present embodiment, the user or
maintenance service provider is warned to discharge the water
stored in the tank 6a of the water tank 6 from the drain opening 8
in the following way.
[0073] FIG. 2 is a flow chart showing steps of a procedure of the
controller 7 of the fuel cell system of the first embodiment of the
present invention.
[0074] The controller 7 finds the accumulated operating time of the
fuel cell system, i.e., the accumulated time of the operation of
the fuel cell system since the moment that the water stored in the
tank 6a was discharged. In the present embodiment, the accumulated
time of the operation of the reformer 1a of the hydrogen generator
1 since the moment that the water stored in the tank 6a was
discharged serves as the accumulated operating time of the fuel
cell system.
[0075] The controller 7 monitors the operating state of the
hydrogen generator 1 and stores, in the memory 7a, data indicative
of the operation start time of the reformer 1a, data indicative of
the operation stop time of the reformer 1a, and data indicative of
the time that the water stored in the tank 6a was last discharged.
And, the controller 7 calculates, at appropriate timing, the
accumulated operating time of the fuel cell system (hereinafter
referred to just as the accumulated operating time) by making use
of the data stored in the memory 7a (S101).
[0076] Next, the controller 7 decides whether or not the
accumulated operating time.gtoreq.a predetermined threshold (S102).
The threshold is set such that the amount of undesirable germs
present in the water stored in the tank 6a will not exceed a
predetermined value. Here, the predetermined value is approximately
an amount of germs at which algae is liable to grow in the tank 6a.
The predetermined value is for example about 105 germs/ml.
[0077] The accumulated operating time taken for the amount of germs
contained in the water held in the tank 6a to exceed the
predetermine value varies depending on the operating condition of
the blower 4 (e.g., the output of the blower 4) during the normal
operation of the fuel cell system and depending on the system
configuration. Accordingly, the threshold used in the present
embodiment is determined appropriately so as to range, for example,
between about 72 and about 96 hours on the basis of the operating
condition and on the basis of the system configuration.
[0078] If in Step S102 it is decided that the accumulated operating
time is less than the threshold (in other words, the result of Step
S102 is "NO"), the controller 7 returns to Step S101 and continues
processing. On the other hand, if in Step S102 it is decided that
the accumulated operating time is equal to or greater than the
threshold (in other words, the result of Step S102 is "YES"), then
the controller 7 issues an instruction that requests the display
portion 30 to display discharge prompting information (S103). In
response to the instruction, the display portion 30 displays the
message requested.
[0079] In the fuel cell system of the present embodiment, as the
accumulated operating time increases, the amount of undesirable
germs in the water held in the tank 6a increases. Accordingly, when
the accumulated operating time exceeds a predetermined value, the
controller 7 decides that the water should be drained and, in order
to draw the user's or maintenance service provider's attention to
the discharging of the water, the display portion 30 displays
discharge prompting information.
[0080] The user or maintenance service provider places the drain
opening 8 in the open state in response to the discharge prompting
information displayed on the display portion 30. As a result, the
water held in the tank 6a is discharged through the drain opening
8. This makes it possible to prevent the water stored in the tank
6a from decaying.
[0081] In the present embodiment, the drain opening 8 is placed in
the open state by the user or maintenance service provider in order
that the water in the tank 6a may be discharged. However, an
alternative arrangement may be made as follows. More specifically,
the controller 7 is configured so that it can control the
opening/closing state of the drain opening 8. The controller 7
automatically places the drain opening 8 in the open state if Step
S102 decides that the accumulated operating time.gtoreq.the
threshold value. In this way, the water held in the tank 6a is
discharged. In this case, the display portion 30 no longer needs to
display discharge prompting information.
[0082] In addition, in the present embodiment, the water recovering
portion 5 recovers both moisture contained in the hydrogen gas
discharged from the fuel cell 3 and moisture contained in the air
supplied from the blower 4; however, it may be arranged such that
either one of the former and the latter is recovered by the water
recovering portion 5. In the case where the water recovering
portion 5 recovers moisture contained in the hydrogen gas and
moisture contained in the air or in the case where the water
recovering portion 5 recovers only moisture contained in air
supplied to the cathode side from the blower 4, the accumulated
time of air supply from the blower 4 to the cathode side since the
moment that the water held in the tank 6 was drained may serve as
the accumulated operating time, the reason for which is that it is
reasonable that the accumulated time of air supply to the cathode
side is used as the time used to determine the timing of the
discharging of water for the purpose of water decay prevention,
because undesirable germs and their necessary nourishment are
contained in the air supplied to the cathode side from the blower
4, as described above.
Embodiment 2
[0083] The fuel cell system of the first embodiment is so
configured as to decide whether or not to discharge the water in
the tank on the basis of the accumulated operating time of the fuel
cell system. On the contrary, a second embodiment of the present
invention provides a fuel cell system configured to decide whether
or not to discharge the water held in the tank on the basis of the
accumulated downtime of the fuel cell system which is the
accumulated downtime of the fuel cell system since the moment that
the water stored in the tank was last drained.
[0084] In the present embodiment, the accumulated downtime of the
reformer of the hydrogen generator since the moment that the water
held in the tank was last drained serves as the accumulated down
time of the fuel cell system.
[0085] The fuel cell system of the second embodiment is identical
in configuration with the fuel cell system of the first embodiment.
Accordingly, the description of the fuel cell system of the second
embodiment is omitted.
[0086] Hereinafter, with reference to FIG. 1 and a flow chart, the
operation of the fuel cell system of the present embodiment will be
described.
[0087] Referring to FIG. 3, there is shown a flow chart
illustrating steps of a procedure of the controller 7 of the fuel
cell electric power generating of the second embodiment of the
present invention.
[0088] The controller 7 monitors the operation state of the
hydrogen generator 1. The memory 7a stores data indicative of the
operation start time of the reformer 1a, data indicative of the
operation stop time of the reformer 1a, and data indicative of the
time that the water held in the tank 6a was last drained. And, the
controller 7 calculates, at appropriate timing, the accumulated
downtime of the fuel cell system (hereinafter referred to just as
the accumulated downtime) by making use of the data stored in the
memory 7a (S201).
[0089] Next, the controller 7 decides whether or not the
accumulated downtime found.gtoreq.a predetermined threshold (S202).
The threshold is set such that the amount of undesirable germs
present in the water stored in the tank 6a will not exceed a
predetermined value. Here, the predetermined value is approximately
an amount of undesirable germs at which algae is liable to grow.
The predetermined value is for example about 105 germs/ml, as in
the case of the first embodiment.
[0090] The accumulated downtime taken for the amount of undesirable
germs contained in the water held in the tank 6a to exceed the
predetermine value varies depending on the temperature of the
inside of the tank 6a. Accordingly, the threshold used in the
present embodiment is determined appropriately so as to normally
range between about 24 and about 40 degrees Centigrade on the basis
of the temperature of the inside of the tank 6a out of
operation.
[0091] For example, for the case of water which contains an amount
of undesirable germs (=103 germs/ml), when left to stand at 25
degrees Centigrade for 48 hours, the amount will increase up to 105
germs/ml. From this, preferably the threshold of the present
embodiment is so set as to fall in the range of from about 24 hours
to about 72 hours.
[0092] By comparison, the threshold of the first embodiment is
greater than the threshold of the second embodiment, the reason for
which is as follows. Since the temperature of the water in the tank
6a is about 70 degrees Centigrade during the system operation
period, this condition disrupts the habitat of undesirable germs in
comparison with the system downtime period. Besides, the water in
the tank 6a is consumed constantly because there is the need for a
supply of water vapor to the hydrogen generator 1 from the water
storing portion 6. Therefore, the growth rate, at which the amount
of undesirable germs increases, is less than that during the system
operating period.
[0093] If in Step S202 it is decided that the accumulated downtime
is less than the threshold (in other words, the result of Step S202
is "NO"), the controller 7 returns to Step S201 and continues
processing. On the other hand, if in Step S202 it is decided that
the accumulated downtime is equal to or greater than the threshold
(in other words, the result of Step S202 is "YES"), the controller
7 issues an instruction that requests the display portion 30 to
display discharge prompting information (S203). In response to the
instruction, the display portion 30 displays the message
requested.
[0094] In the fuel cell system of the present embodiment, as the
accumulated downtime increases, the amount of undesirable germs
contained in the water held in the tank 6a increases. Accordingly,
when the accumulated downtime exceeds the predetermined value, the
controller 7 decides that the water should be drained and, in order
to draw the user's or maintenance service provider's attention to
the discharging of the water, the display portion 30 display
discharge prompting information.
[0095] The user or maintenance service provider places the drain
opening 8 in the open state in response to the discharge prompting
information displayed on the display portion 30. As a result, the
water held in the tank 6a is drained through the drain opening 8.
This makes it possible to prevent the water stored in the inside of
the tank 6a from decaying.
[0096] In addition, in the case where the fuel cell system is
activated after the water held in the tank 6a was drained during
the system downtime period, water is supplied into the tank 6a from
a water infrastructure by the controller 7 placing the water supply
valve 9 in the open state. This enables the fuel cell system to be
activated quickly.
Embodiment 3
[0097] A fuel cell system formed in accordance with a third
embodiment of the present invention is so configured as to decide
whether or not to discharge the water held in the tank on the basis
of the flow rate of the water output from the pump of the water
supply portion.
[0098] Referring to FIG. 4, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
according to the third embodiment of the present invention. As
shown in FIG. 4, in the fuel cell system of the present embodiment,
a flow rate detector 40 for detecting the flow rate of water per
unit time is disposed downstream of the water supply portion 10
relative to the direction in which the water flows. The flow rate
detector 40 is connected in communicable manner with the controller
7. The flow rate detector 40 outputs a signal (hereinafter called
the flow rate detection signal) indicative of a detected value of
the flow rate of the water output from the water supply portion 10,
to the controller 7. Based on the flow rate detection signal, the
controller 7 instructs the display portion 30 to display discharge
prompting information in the way described later.
[0099] With respect to other constructional components, the fuel
cell system of the present embodiment and the fuel cell system of
the first embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0100] Next, the operation of the fuel cell system of the present
embodiment constructed in the way as described above will be
discussed.
[0101] During the operating period, the controller 7 brings the
pump 10a of the water supply portion 10 to operate under
predetermined operating conditions. In this case, since the
operation of the pump 10a is constant, the flow rate of the water
output from the pump 10a increases or decreases according to the
increase or decrease in the flow rate of the water which is
supplied to the water supply portion 10 through the water purifier
11.
[0102] In the controller 7, the memory 7a pre-stores data
indicative of a reference value of the flow rate of the water
output from the pump 10a of the water supply portion 10. The
reference value is set on the assumption of the flow rate of the
water output from the pump 10a when water flowing from the tank 6a
passes through the filter 11a in a normal state prior to the
occurrence of clogging of the filter 11a of the water purifier 11
caused by undesirable germs.
[0103] When undesirable germs cause clogging of the filter 11a of
the water purifier 11, the flow rate of the water past the filter
11a decreases, and the flow rate of the water output from the pump
10a of the water supply portion 10 likewise decreases. When the
filter 11a of the water purifier 11 becomes clogged by germs, the
detected value of the flow rate of the water output from the pump
10a of the water supply portion 10 is less than the reference
value. Therefore, from the fact that the detected value of the flow
rate of the water output from the pump 10a of the water supply
portion 10 is less than the reference value, the filter 11a of the
water supply portion 11 can be concluded to suffer from clogging by
germs.
[0104] Referring to FIG. 5, there is shown a flow chart
illustrating steps of a procedure of the controller 7 of the fuel
cell system formed in accordance with the third embodiment of the
present invention.
[0105] The controller 7 receives, at appropriate timing, a flow
rate detection signal from the flow rate detector 40. Based on the
flow rate detection signal received, the controller 7 obtains a
detected value of the flow rate of the water output from the pump
of the water supply portion 10 (S301).
[0106] Next, the controller 7 makes a decision on whether or not
the detected value obtained falls below the reference value stored
in the memory 7a (S302). If the detected value is determined to be
equal to or greater than the reference value (in other words, the
result of Step S302 is "NO"), then the controller 7 returns to Step
S301 and continues processing. On the other hand, if the detected
value is determined to be less than the reference value (in other
words, the result of Step S302 is "YES"), then the controller 7
issues an instruction that requests the display portion 30 to
display discharge prompting information (S303). In response to the
instruction, the display portion 30 displays the message
requested.
[0107] In the fuel cell system of the present embodiment, with the
increase in the accumulated operating time, the amount of
undesirable germs collected in the filter 11a of the water purifier
11 likewise increases. When the filter 11a becomes clogged by
germs, it can be judged that the accumulated operating time is
considerably great and there is a considerable increase in the
amount of undesirable germs present in the water held in the tank
6a. Accordingly, if it is concluded that the filter 11a of the
water purifier 11 becomes clogged by germs because the detected
value of the flow rate of the water falls below the reference
value, discharge prompting information is displayed on the display
portion 30 in order to draw the user's or maintenance service
provider's attention to the discharging of the water held in the
tank 6a.
[0108] The user or maintenance service provider places the drain
opening 8 in the open state in response to the discharge prompting
information displayed on the display portion 30. As a result, the
water held in the tank 6a is drained through the drain opening 8.
This makes it possible to prevent the water stored in the tank 6a
from decaying.
[0109] In addition, it may be arranged such that the controller 7
controls the operation of the pump 10a of the water supply portion
10 so that the pump 10a rotates in the opposite direction, at the
time when instructing the display portion 30 to display discharge
prompting information or before or after it. Because of this,
germs, the cause of clogging of the filter 11a of the water
purifier 11, are brought back to the tank 6a. The germs thus
brought back to the tank 6a are discarded outside when the water
held in the tank 6a is drained.
Embodiment 4
[0110] A fuel cell system formed in accordance with a fourth
embodiment of the present invention is so configured as to decide
whether or not to discharge the water held in the tank on the basis
of the operating state of the water supply portion.
[0111] Since the configuration of the fuel cell system of the
fourth embodiment is substantially the same as that of the fuel
cell system of the third embodiment, the description thereof is
omitted. Hereinafter, referring to FIG. 4, the operation of the
fuel cell system according to the fourth embodiment will be
described.
[0112] In the present embodiment, during the operating period, the
controller 7 controls the operation of the pump 10a of the water
supply portion 10 so that the pump 10a delivers water at a
predetermined flow rate. In this case, the workload of the pump 10a
of the water supply portion 10 increases or decreases according to
the increase or decrease in the flow rate of water which is
supplied to the water supply unit 10 through the water purifier
11.
[0113] The memory 7a of the controller 7 pre-stores data indicative
of a reference value of the flow rate of water output from the pump
10a of the water supply portion 10. As in the foregoing case, the
reference value is set on the assumption of the flow rate of water
output from the pump 10a when water flowing from the tank 6a passes
through the filter 11a in a normal state prior to the occurrence of
clogging of the filter 11a of the water purifier 11 caused by
undesirable germs.
[0114] In addition, the memory 7a of the controller 7 pre-stores
data indicative of the workload of the pump 10a (hereinafter
referred to as the reference workload) required for the delivery of
water at a rate of flow according to the reference value. And,
based on the flow rate detection signal outputted from the flow
rate detector 40, the controller 7 obtains a detected value of the
flow rate of the water delivered by the pump 10a and then makes a
comparison between the detected value and the reference value. If
the detected value is found to fall below the reference value, then
the workload of the pump 10a is increased. On the other hand, if
the detected value is found to exceed the reference value, then the
workload of the pump 10a is decreased.
[0115] Since the rate of flow of the water past the filter 11a of
the water purifier 11 decreases when the filter 11a becomes clogged
by germs, the workload of the pump 10a of the water supply portion
10 becomes greater than the reference workload in order to deliver
water at a rate of flow according to the reference value.
Accordingly, if the workload of the pump 10a of the water supply
portion 10 exceeds the reference workload, then it can be concluded
that the filter 11a of the water purifier 11 becomes clogged by
germs.
[0116] In the third embodiment the operation of the pump 10a of the
water supply portion 10 is made constant. Also by the arrangement
that the flow rate of the water delivered by the pump 10a is made
constant, it can be concluded that the filter 11a of the water
purifier 11 becomes clogged by germs, in the same way as described
above.
[0117] The workload of the pump 10a can be measured by input energy
to the pump 10a or by energy consumed by the pump 10a. Accordingly,
the workload of the pump 10a can be measured by detecting an input
voltage or power to the pump 10a or by detecting an amount of power
consumed by the pump 10a.
[0118] The detection of input energy to the pump 10a or the
detection of energy consumed by the pump 10a may be carried out by
the controller 7. Alternatively, such detection may be carried out
by a separately-provided, dedicated detecting means.
[0119] Referring to FIG. 6, there is shown a flow chart
illustrating steps of a procedure of the controller 7 of the fuel
cell system of the fourth embodiment of the present invention.
[0120] The controller 7 measures, at appropriate timing, the
workload of the pump 10a of the water supply portion 10 (S401).
[0121] Next, the controller 7 decides whether or not a measured
workload of the pump 10a (hereinafter referred to as the measured
workload) exceeds the reference workload stored in the memory 7a
(S402). If it is decided that the measured workload is equal to or
less than the reference workload (in other words, the result of
Step S402 is "NO"), then the controller 7 returns to Step S401 and
continues processing. On the other hand, if in Step S402 it is
decided that the measured workload exceeds the reference workload
(in other words, the result of Step S402 is "YES"), then the
controller 7 issues an instruction that requests the display
portion 30 to display discharge prompting information (S403). In
response to the instruction, the display portion 30 displays the
message requested.
[0122] In the fuel cell system of the present embodiment, with the
increase in the accumulated operating time, the amount of
undesirable germs collected in the filter 11a of the water purifier
11 likewise increases. When the filter 11a becomes clogged by
germs, it can be judged that the accumulated operating time is
considerably great and there is a considerable increase in the
amount of germs present in the water held in the tank 6a.
Accordingly, if it is concluded that the filter 11a of the water
purifier 11 becomes clogged by germs because the measured workload
of the pump 10a exceeds the reference workload, discharge prompting
information is displayed on the display portion 30 in order to draw
the user's or maintenance service provider's attention to the
discharging of the water held in the tank 6a.
[0123] Consequently, the water held in the tank 6a is drained
through the drain opening 8 by the user or maintenance service
provider. This makes it possible to prevent the water stored in the
inside of the tank 6a from decaying.
[0124] In addition, as in the case of the third embodiment, it may
be arranged such that the controller 7 controls the operation of
the pump 10a of the water supply portion 10 so that the pump 10a
rotates in the opposite direction at the time when instructing the
display portion 30 to display discharge prompting information or
before or after it.
Embodiment 5
[0125] A fuel cell system formed in accordance with a fifth
embodiment of the present invention is so configured as to decide
whether or not to discharge the water held in the tank on the basis
of the operating state of the water supply portion, as in the case
of the fourth embodiment.
[0126] Referring to FIG. 7, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
according to the fifth embodiment of the present invention. As
shown in FIG. 7, the fuel cell system of the present embodiment is
provided with a water pressure detector 50 for detecting the
pressure of water flowing between the water storing portion 6 and
the water purifier 11. The water pressure detector 50 is connected
in communicable manner with the controller 7. The water pressure
detector 50 outputs a signal (hereinafter called the water pressure
detection signal) indicative of a detected value of the pressure of
water flowing between the water storing portion 6 and the water
purifier 11, to the controller 7. Based on the water pressure
detection signal, the controller 7 instructs the display portion 30
to display discharge prompting information as will be described
later.
[0127] With respect to other constructional components, the fuel
cell system of the present embodiment and the fuel cell system of
the first embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0128] Next, the operation of the fuel cell system of the present
embodiment constructed in the way as described above will be
discussed.
[0129] In the case of the present embodiment, during the operating
period, the controller 7 brings the pump 10a of the water supply
portion 10 to operate in such a way that the detected value of the
pressure of water flowing between the water storing portion 6 and
the water purifier 11 equals the reference value. Data indicative
of the reference value is pre-stored in the memory 7a. The
reference value is set on the assumption of the pressure of water
flowing between the water storing portion 6 and the water purifier
11 in a normal state prior to the occurrence of clogging of the
filter 11a of the water purifier 11 due to germs.
[0130] In addition, the memory 7a of the controller 7 pre-stores
data indicative of the workload of the pump 10a necessary for
making the pressure of water flowing between the water storing
portion 6 and the water purifier 11 equal to the reference value
(hereinafter referred to as the reference workload). And, based on
the water pressure detection signal outputted from the water
pressure detector 50, the controller 7 obtains a detected value of
the pressure of water flowing between the water storing portion 6
and the water purifier 11 and makes a comparison between the
detected value and the reference value. If the detected value is
found to exceed the reference value, then the workload of the pump
10a is increased. On the other hand, if the detected value is found
to fall below the reference value, then the workload of the pump
10a is decreased.
[0131] The flow rate of the water past the filter 11a of the water
purifier 11 decreases when the filter 11a becomes clogged by germs.
Accordingly, the velocity of flow of the water between the water
storing portion 6 and water purifier 11 decreases and, at the same
time, the pressure of the water between the water storing portion 6
and the water purifier 11 increases. As a result, the detected
value of the water pressure exceeds the reference value. In order
to make the detected value agree with the reference value, the
controller 7 increases the workload of the pump 10a. This increases
the flow rate of the water passing through the filter 11a, and the
velocity of flow of the water between the water storing portion 6
and the water purifier 11 increases and, at the same time, the
pressure of the water between the water storing portion 6 and the
water purifier 11 decreases. In this case, the workload of the pump
10a exceeds the reference workload.
[0132] Therefore, if the workload of the pump 10a of the water
supply portion 10 exceeds the reference workload, then it can be
concluded that the filter 11a of the water purifier 11 becomes
clogged by germs.
[0133] The workload of the pump 10a is measured by input energy to
the pump 10a or by energy consumed by the pump 10a, as in the case
of the fourth embodiment.
[0134] The detection of input energy to the pump 10a or the
detection of energy consumed by the pump 10a may be carried out by
the controller 7, as in the case of the fourth embodiment.
Alternatively, such detection may be carried out by a
separately-provided, dedicated detecting means.
[0135] The procedure steps of the fuel cell system according to the
fifth embodiment of the present invention are the same as the
procedure steps of the fourth embodiment. More specifically, as
illustrated in the flow chart shown in FIG. 6, the controller 7
measures, at appropriate manner, the workload of the pump 10a of
the water supply portion 10 (S401) and make a decision on whether
or not the measured workload of the pump 10a exceeds the reference
workload (S402). If it is decided that the measured workload falls
below the reference workload (in other words, the result of Step
S402 is "NO"), then the controller 7 returns to Step S401 and
continues processing. On the other hand, if in Step S402 it is
decided that the measured workload is found to exceed the reference
workload (in other words, the result of Step S402 is "YES"), then
the controller 7 issues an instruction that requests the display
portion 30 to display discharge prompting information (S403). In
response to the instruction, the display portion 30 displays the
message requested.
[0136] In the fuel cell system of the present embodiment, with the
increase in the accumulated operating time, the amount of germs
collected in the filter 11a of the water purifier 11 likewise
increases. When the filter 11a becomes clogged by germs, it can be
judged that the accumulated operating time is considerably great
and there is a considerable increase in the amount of germs present
in the water held in the tank 6a. Accordingly, if it is concluded
that the filter 11a of the water purifier 11 becomes clogged by
germs because the measured workload of the pump 10a exceeds the
reference workload as described above, then discharge prompting
information is displayed on the display portion 30 in order to draw
the user's or maintenance service provider's attention to the
discharging of the water held in the tank 6a.
[0137] Consequently, the water held in the tank 6a is drained
through the drain opening 8 by the user or maintenance service
provider. This makes it possible to prevent the water stored in the
inside of the tank 6a from decaying.
[0138] As in the case of the third embodiment, it may be arranged
such that the controller 7 controls the operation of the pump 10a
of the water supply portion 10 so that the pump 10a rotates in the
opposite direction at the time when instructing the display portion
30 to display discharge prompting information or before or after
it.
Embodiment 6
[0139] In the fuel cell systems according to the first to fifth
embodiments, discharge prompting information is outputted at
appropriate timing in order to prompt the user or maintenance
service provider to discharge the water in the tank. As a result,
the tank water is discharged through the drain opening, thereby
preventing the water held in the tank from decaying.
[0140] A fuel cell system according to a sixth embodiment of the
present invention is capable of cleaning the inside of the tank by
providing a supply of water into the tank from the outside after
the discharging of the water in the tank in the way as described
above.
[0141] The configuration of the fuel cell system of the sixth
embodiment is substantially the same as that of the fuel cell
system of the first embodiment and the description thereof is
omitted accordingly.
[0142] Hereinafter, referring to FIG. 1 and a flow chart, the
operation of the fuel cell system of the present embodiment will be
described.
[0143] FIG. 8 is a flow chart showing steps of a procedure of the
controller 7 of the fuel cell system of the sixth embodiment of the
present invention.
[0144] As in any one of the first to fifth embodiments, the display
portion 30 displays discharge prompting information, after which
the controller 7 decides whether or not the water held in the tank
6a has been discharged through the drain opening 8 by the user or
maintenance service provider (S501). Such decision may be made
based on the result of detection of the water level of the tank 6a
carried out by, for example, a water level detecting means.
Alternatively, the user or maintenance service provider may input
to the controller 7 information indicating that the water held in
the tank 6a has been drained.
[0145] If in Step S501 it is decided that the water in the tank 6a
has not been drained yet (in other words, the result of Step S501
is "NO"), then the controller 7 repeatedly executes Step S501 until
it is decided that the water in the tank 6a has been drained. On
the other hand, if in Step S501 it is decided that the water in the
tank 6a has been drained (in other words, the result of Step S501
is "YES"), then the controller 7 places the water supply valve 9 in
the open state so that a fixed amount of water is supplied to the
tank 6a from the water infrastructure (S502).
[0146] Next, the controller 7 instructs the display portion 30 to
display discharge prompting information (S503). In response to the
instruction, the display portion 30 displays the message
requested.
[0147] In the fuel cell system of the present embodiment, slimes
may develop on the internal wall surface of the tank 6a if
undesirable germs multiply in the water of the tank 6a. The growth
of such slimes can be prevented by discharging the water held in
the tank 6a, as in the first to fifth embodiments; however, it is
difficult to remove the slimes themselves. Accordingly, as
described above, water is supplied into the tank 6a through the
water supply valve 9 after the existing water in the tank 6a was
drained. The inside of the tank 6a is cleaned by the water thus
supplied. As a result, residual undesirable germs and their
necessary nourishment which are decay factors present in the inside
of the tank 6a are washed away, thereby achieving a reduction in
the absolute amount. As a result, the growth of the slimes is
prevented and the slimes can be removed. In comparison with the
first to fifth embodiments, the present embodiment prevents more
definitely the water held in the tank 6a from decaying.
Embodiment 7
[0148] A fuel cell system according to a seventh embodiment of the
present invention is capable of effectively removing undesirable
germs by drying the inside of the tank after the discharging of the
water in the tank, as in the case of the first to fifth
embodiments.
[0149] Referring to FIG. 9, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
according to the seventh embodiment of the present invention. As
shown in FIG. 9, in the fuel cell system of the present embodiment,
the water storing portion 6 is provided with a heater 6b having an
electric heater for heating the tank 6a and a temperature sensor
for measuring the temperature of heating by the electric
heater.
[0150] The controller 7 controls the operation of the heater 6b of
the water storing portion 6 and receives a signal indicative of a
measured value by the temperature sensor of the heater 6b
(hereinafter referred to as the temperature measurement
signal).
[0151] With respect to other constructional components, the fuel
cell system of the present embodiment and the fuel cell system of
the first embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0152] Next, the operation of the fuel cell system of the present
embodiment as constructed above will be described.
[0153] Referring to FIG. 10, there is shown a flow chart
illustrating steps of a procedure of the controller 7 of the fuel
cell system according to the seventh embodiment of the present
invention.
[0154] As in any one of the first to fifth embodiments, the display
portion 30 displays discharge prompting information. Thereafter,
the controller 7 decides whether or not the water held in the tank
6a has been drained through the drain opening 8 by the user or
maintenance service provider (S601), as in the sixth embodiment. If
in Step S601 it is decided that the water in the tank 6a has not
been drained yet (in other words, the result of Step S601 is "NO"),
then the controller 7 repeatedly executes Step S601 until Step S601
decides that the water held in the tank 6a has been drained. On the
other hand, if in Step S601 it is decided that the water in the
tank 6a has been drained (in other words, the result of Step S601
is "YES"), then the controller 7 activates the electric heater of
the heater 6a so that the tank 6a is subjected to heating treatment
(S602).
[0155] Next, based on the temperature measurement signal received
from the water storing portion 6, the controller 7 decides whether
or not the temperature of heating by the electric heater of the
heater 6b is higher than the threshold (S603). Here, the threshold
is so set as to fall in the range of from about 100 to about 130
degrees Centigrade. The reason for such a temperature setting is
that the inside of the tank 6a cannot be dried if the heating
temperature of the electric heater is below 100 degrees Centigrade.
On the other hand, if the heating temperature is above 130 degrees
Centigrade, this necessitates that the tank 6a must be formed using
members of high resistance to heat, thereby producing the problem
that the system production cost becomes high. Within the foregoing
temperature range, it is possible to effectively eliminate
undesirable germs present in the inside of the tank 6a.
[0156] If in Step S603 it is decided that the heating temperature
of the electric heater is below the threshold (in other words, the
result of Step S603 is "NO"), then the controller 7 repeatedly
executes Step S603 until it is decided that the heating temperature
is in excess of the threshold. On the other hand, if in Step S603
it is decided that the heating temperature of the electric heater
exceeds the threshold (in other words, the result of Step S603 is
"YES"), then the controller 7 maintains the operation of the
electric heater of the heater 6a for a predetermined length of time
so that heating is continued for that length of time (S604).
[0157] If there still remains a small amount of moisture in the
inside of the tank 6a in the fuel cell system of the present
embodiment after the discharging of the water in the tank 6a,
undesirable germs will multiply by making utilization of such
residual moisture. Particularly, in the case where the fuel cell
system is brought down over a long term, generation of slimes will
occur early on the internal wall surface of the tank 6a by
multiplying germs, when the fuel cell system is activated again.
Accordingly, such residual moisture is removed by drying the inside
of the tank 6a as in the case of the present embodiment, thereby
early avoiding generation of slimes.
[0158] In addition, in accordance with the present embodiment, the
inside of the tank 6a is dried by application of heat. As a result,
undesirable germs present in the inside of the tank 6a are
eliminated effectively.
[0159] In comparison with the first to fifth embodiments, the fuel
cell system of the present embodiment prevents more definitely the
water held in the tank 6a from decaying.
[0160] In addition, in the present embodiment, it is arranged such
that the inside of the tank 6a is dried by application of heat to
the tank 6a by the electric heater of the heater 6b; however, this
arrangement should not in any way be deemed restrictive. For
example, the inside of the tank 6a may be dried by delivering a
stream of heated air into the tank 6a.
[0161] In addition, also in the present embodiment, it may be
arranged such the inside of the tank 6a is cleaned by supplying
water into the tank 6a through the water supply valve 9 as in the
sixth embodiment and thereafter the inside of the tank 6a is dried
by application of heat to the tank 6a by the heater 6b.
Embodiment 8
[0162] A fuel cell system according to an eighth embodiment of the
present invention is configured such that the tank of the water
storing portion is divided into two sub-tanks so that, even when
the water held in one sub-tank is drained for the purpose of the
prevention of water decay, it is still possible to continuously
provide a supply of water to the hydrogen generator from the
other.
[0163] Referring to FIG. 11, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
formed in accordance with the eighth embodiment of the present
invention. As shown in FIG. 11, the water storing portion 6 of the
fuel cell system of the present embodiment is provided with a first
tank 6a1 and a second tank 6a2 for the storage of water supplied
from the water recovering portion 5 and water supplied via the
water supply valve 9. The first and second tanks 6a1 and 6a2 are
each connected to a switch 20 formed by a switching valve by which
the destination, to which water supplied from the water supply
portion 5 and water supplied through the water supply valve 9
should be distributed, is switched between the first tank 6a1 and
the second tank 6a2.
[0164] The switch 20 is connected to the controller 7 and the
operation of the switching valve of the switch 20 is controlled by
the controller 7.
[0165] In addition, the first and second tanks 6a1 and 6a2 are
connected to a first drain opening 21 and to a second drain opening
22 respectively so that water held in the former and water held in
the latter are drained through these openings respectively.
[0166] With respect to other constructional components, the fuel
cell system of the eighth embodiment and the fuel cell system of
the first embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0167] Next, the operation of the fuel cell system of the eighth
embodiment as constructed above will be described.
[0168] As in the case of the first embodiment, in the fuel cell
system of the fourth embodiment, hydrogen gas is generated in the
hydrogen generator 1 and the fuel cell 3 generates electric power
using the hydrogen gas and air. And, water generated during the
electric power generation is recovered by the water recovering
portion 5. The water recovering portion 5 supplies the recovered
water to the switch 20 so that the recovered water is supplied to
the water storing portion 6.
[0169] Based on the control signal outputted from the controller 7,
the switch 20 switches the destination, to which the water supplied
from the water recovering portion 5 is distributed, between the
first tank 6a1 and the second tank 6a2 at predetermined timing. As
a result of such arrangement, the first and second tanks 6a1 and
6a2 are supplied with water in alternation.
[0170] The controller 7 instructs the display portion 30 to display
either first discharge prompting information prompting the user or
maintenance service provider to discharge the water held in the
first tank 6a1 through the first drain opening 21 or second
discharge prompting information prompting the user or maintenance
service provider to discharge the water held in the second tank 6a2
through the second drain opening 22.
[0171] In the present embodiment, the controller 7 decides whether
or not to discharge the water held in one of the first and second
tanks 6a1 and 6a2 that is not being supplied with water, as in the
case of any one of the first to fifth embodiments. If it is decided
that the water should be discharged, then the controller 7
instructs the display portion 30 to display either the first
discharge prompting information or the second discharge prompting
information in order to prompt the user or maintenance service
provider to do so.
[0172] As a result, when the display portion 30 displays the first
discharge prompting information, the water held in the first tank
6a1 is drained through the first drain opening 21 by the user or
maintenance service provider. On the other hand, when the display
portion 30 displays the second discharge prompting information, the
water held in the second tank 6a2 is drained through the second
drain opening 22 by the user or maintenance service provider.
[0173] Here, the water held in the other of the first and second
tanks 6a1 and 6a2 that is being supplied with water is not drained
and is supplied to the hydrogen generator 1 through the water
purifier 11 and through the water supply portion 10. As a result of
such arrangement, it is possible to continuously supply the water
held in one tank to the hydrogen generator 1 and at the same time
to drain the water held in the other for the purpose of the
prevention of water decay.
[0174] In the present embodiment, preferably the timing, at which
the destination to which water is distributed is switched between
the first and second tanks 6a1 and 6a2, is set in the light of the
size of fuel cell system and in the light of the actual operating
performance of fuel cell system so that water decay prevention is
carried out effectively.
[0175] In the present embodiment, the water storing portion 6 is
provided with two tanks, i.e., the first and second tanks 6a1 and
6a2. For example, it may be arranged such that the water storing
portion 6 is provided with three or more tanks. In the case where
the water storing portion 6 is provided with three or more tanks,
it suffices if water is supplied to each tank one after the other
and the display portion 30 displays discharge prompting information
indicating that a tank that was first supplied with water should be
drained.
[0176] In addition, also in the present embodiment, it is possible
to more definitely prevent water decay by cleaning the inside of
each tank as in the case of the sixth embodiment and by drying the
inside of each tank as in the case of the seventh embodiment.
Embodiment 9
[0177] A fuel cell system according to a ninth embodiment of the
present invention is configured such that water in the tank is
prevented from decaying by application of heat to the tank water by
means of the heater of the water storing portion.
[0178] Referring to FIG. 12, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
according to the ninth embodiment of the present invention. As
shown in FIG. 12, the water storing portion 6 of the fuel cell
system of the present embodiment is provided with a heater 6b
comprising an electric heater for heating the tank 6a and a
temperature sensor for measuring the temperature of heating by the
electric heater.
[0179] The controller 7 controls the operation of the heater 6b of
the water storing portion 6 and receives from the water storing
portion 6 a temperature measurement signal indicative of a measured
value by the temperature sensor of the heater 6b.
[0180] In addition, the fuel cell system of the present embodiment
is further provided with a cooling water tank 61 adapted for
storing cooling water which is circulated through the fuel cell 3
for controlling the temperature thereof, and a cooling water heater
62 adapted for heating cooling water held in the cooling water tank
61. The cooling water tank 61 and the fuel cell 3 are connected
together by two channels, namely a channel for supplying water to
the fuel cell 3 from the cooling water tank 61 and another channel
for supplying water to the cooling water tank 61 from the fuel cell
3.
[0181] Furthermore, the fuel cell system of the present embodiment
is further provided with a cooling water purifier 63 for purifying
cooling water, and the cooling water tank 61 and the tank 6a of the
water storing portion 6 are connected together by two channels,
i.e., one passing through the cooling water purifier 63 and the
other passing through the cooling water purifier 63. And, when
water is supplied to the tank 6a from the cooling water tank 61,
the water is supplied without passing through the water purifier
63. On the other hand, when water is supplied to the cooling water
tank 61 from the tank 6a, the water is supplied through the water
purifier 63.
[0182] With respect to other constructional components, the fuel
cell system of the present embodiment and the fuel cell system of
the first embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0183] Next, the operation of the fuel cell system of the present
embodiment as constructed above will be described.
[0184] Also in the fuel cell system of the present embodiment, it
is arranged such that the display portion 30 displays discharge
prompting information at predetermined timing in order to draw the
user's or maintenance service provider's attention to the
discharging of the water held in the tank 6a, as in the case of the
first to fifth embodiments. In addition, apart from this operation,
water decay is prevented definitely by application of heat to the
water in the tank 6a in the following way.
[0185] In the water storing portion 6, water delivered from the
water recovering portion 5 and water delivered from the cooling
water tank 61 are stored in the tank 6a. And, based on the control
signal outputted from the controller 7, the heater 6b of the water
storing portion 6 is operated so that heating treatment for heating
the water held in the tank 6a is carried out. In this case,
preferably the heating temperature is set to a value capable of
completely eliminating undesirable germs and molds present in the
water held in the tank 6a. Most of the germs can be eliminated by
heating at temperatures in the range of from 80 to 90 degrees
Centigrade for several minutes. In the light of this, the
controller 7 controls the operation of the heater 6b so that the
heating temperature of about 90 degrees Centigrade is maintained
for about ten minutes or so.
[0186] The heating temperature of the heater 6b may be determined
taking into consideration the heat or pressure resisting properties
of its constructional members. However, when the heating
temperature is set above 100 degrees Centigrade, this necessitates
use of members that can withstand high temperatures. Therefore, it
must be noted that the costs of manufacture will increase in this
case.
[0187] In addition, there is a correlation between the germ
eliminating time and the germ eliminating temperature. Therefore,
if the heating temperature is relatively low, this requires an
extension of the heating time. On the other hand, if the heating
temperature is relatively high, a shorter heating time will
suffice.
[0188] The controller 7 controls the heater 6b to force it to
repeatedly perform the above-described heating treatment at
constant intervals of time. This makes it possible to prevent mold
spores that can survive even at about 90 degrees Centigrade and
undesirable germs from the outside from re-multiplying in the water
held in the tank 6a. At which interval that heating treatment is to
be carried out should be determined in the light of the operating
conditions and the installation place of fuel cell system and in
the light of the multiplication state of undesirable germs.
[0189] The water in the tank 6a heated by the heater 6b is supplied
to the water purifier 11 and to the cooling water purifier 63.
Passing through the filter 11a of the water purifier 11, the water
is purified. Then, the water is supplied to the water supply
portion 10 for forwarding to the hydrogen generator 1. This makes
it possible for the hydrogen generator 1 to receive a supply of
water which is required for a reforming reaction.
[0190] On the other hand, the water, purified when passing through
the cooling water purifier 63, is supplied to the cooling water
tank 61. This makes it possible for the cooling water tank 61 to
receive a supply of cooling water to be circulated in the fuel cell
3.
[0191] As described above, the water, recovered by the water
recovering portion 5, stored in the cooling water tank 61, and then
stored in the tank 6a of the water storing portion 6, is subjected
to heating treatment by the heater 6b. As a result, undesirable
germs present in the recovered water are eliminated. In addition,
alcohol of low boiling point and aldehyde components which become
nutriments for undesirable germs can be evaporated, thereby making
the multiplication rate of undesirable germs as low as possible.
This prevents water decay and therefore avoids the occurrence of
problems such as flow path blockage in the piping.
[0192] In the above, heating treatment is carried out at
predetermined intervals of time when the fuel cell system of the
present embodiment is being in service, i.e., when the hydrogen
generator 1 is generating hydrogen gas and the fuel cell 3 is
producing electric power by the use of the hydrogen gas. However,
the fuel cell system of the present invention is not limited to
such operations. For example, it may be arranged such that only the
heater 6b of the water storing portion 6 is brought into activation
without activating constructional elements other than the heater
6b, so that only heating treatment by the heater 6b is made
executable. This arrangement that only heating treatment by the
heater 6b is made executable makes it possible to first eliminate
undesirable germs reproduced in the water held in the tank 6a of
the water storing portion 6 by performing heating treatment, for
example when the fuel cell system has been stopped for a long
period of time, and then to perform normal operations.
[0193] In addition, also in the present embodiment, it is possible
to prevent water decay more definitely by cleaning the inside of
the tank as in the case of the sixth embodiment or by drying the
inside of the tank as in the case of the seventh embodiment.
Embodiment 10
[0194] A fuel cell system formed in accordance with a tenth
embodiment of the present invention is provided, between the water
storing portion and the water purifier, a cooler for the cooling of
recovered water. The provision of the cooler makes it possible to
prevent water of high temperature from being supplied to the water
purifier.
[0195] Referring to FIG. 13, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
of the tenth embodiment. As shown in FIG. 13, the fuel cell system
of the present embodiment is provided with a cooler 12 which is
connected to the water storing portion 6 and to the water purifier
11 and which has an air cooling fan for the cooling of water which
is supplied to the water purifier 11 from the water storing portion
6. The cooler 12 is connected to the controller 7, and operates
based on the control signal outputted from the controller 7.
[0196] With respect to other constructional components, the fuel
cell system of the present embodiment and the fuel cell system of
the ninth embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0197] Next, the operation of the fuel cell system of the present
embodiment as constructed above will be described.
[0198] Also in the fuel cell system of the present embodiment, it
is arranged such that the display portion 30 displays discharge
prompting information at predetermined timing in order to draw the
user's or maintenance service provider's attention to the
discharging of the water in the tank 6a, as in the case of the
first to fifth embodiments. In addition, apart from this operation,
water decay is prevented definitely by application of heat to the
water in the tank 6a in the following way.
[0199] As in the case of the ninth embodiment, in the fuel cell
system of the present embodiment the hydrogen generator 1 generates
hydrogen gas and the fuel cell 3 generates electric power by the
use of the hydrogen gas and air. And, water generated during the
electric power generation is recovered by the water recovering
portion 5 and the recovered water is stored in the tank 6a of the
water storing portion 6. Water supplied from the cooling water tank
61 is likewise stored in the tank 6a. The water thus stored in the
tank 6a is heated at a heating temperature of about 90 degrees
Centigrade for a predetermined length of time by the heater 6b.
[0200] In the way as described above, the water heated by the
heater 6b is supplied to the cooler 12 from the water storing
portion 6. Based on the control signal outputted from the
controller 7, the air cooling fan of the cooler 12 operates to cool
the water supplied from the water storing portion 6. And, the
cooler 12 supplies the cooled water to the water purifier 11. Here,
it suffices if the cooler 12 is activated in conjunction with the
heater 6b of the water storing portion 6, so that there is no need
to constantly operate the cooler 12. In other words, since the
heater 6b repeatedly performs heating treatment at predetermined
intervals of time (as described above), it suffices if the cooler
12 is made to operate only when water heated by such heating
treatment is supplied from the water storing portion 6.
[0201] In the water purifier 11, the water cooled by the cooler 12
is purified by the filter 11a and the water purified is supplied to
the water supply portion 10. And, the water supply portion 10
supplies the water supplied from the water purifier 11 to the
hydrogen generator 1. In this way, the hydrogen generator 1 is
provided with a supply of water which is necessary for a reforming
reaction.
[0202] If water heated by the heater 6a is supplied, without being
cooled, to the water purifier 11, there is the danger that the
water purifying function of the activated carbon or ion exchange
resin becomes worse. In the fuel cell system of the present
embodiment, however, the cooler 12 is activated in the way as
described above, whereby cooled water is supplied to the water
purifier 11. Such arrangement prevents deterioration of the water
purifying function of the water purifier 11.
[0203] In the case where both the water purifier 11 and the water
supply portion 10 are constructed of members having resistance to
heat, the problem of water purifying function deterioration will
not occur even when the cooler 12 is not provided.
[0204] In addition, also in the present embodiment, it is possible
to prevent water decay more definitely by cleaning the inside of
the tank as in the case of the sixth embodiment or by drying the
inside of the tank as in the case of the seventh embodiment.
Embodiment 11
[0205] A fuel cell system formed in accordance with an eleventh
embodiment of the present invention is provided with a water vapor
exhausting valve for preventing the rise in pressure of the inside
of the water storing portion.
[0206] Referring to FIG. 14, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
according to the eleventh embodiment. As shown in FIG. 14, the
water storing portion 6 of the fuel cell system of the present
embodiment is provided with a water vapor exhausting valve 13 which
discharges water vapor accompanied by heat processing by the heater
6b. With respect to other constructional components, the fuel cell
system of the present embodiment and the fuel cell system of the
ninth embodiment are substantially the same. Accordingly, they are
assigned the same reference numerals and their description is
omitted.
[0207] Next, the operation of the fuel cell system of the eleventh
embodiment as constructed above will be described.
[0208] Also in the fuel cell system of the present embodiment, it
is arranged such that the display portion 30 displays discharge
prompting information at predetermined timing in order to draw the
user's or maintenance service provider's attention to the
discharging of the water held in the tank 6a, as in the case of the
first to fifth embodiments. In addition, apart from this operation,
water decay is prevented definitely by application of heat to the
water in the tank 6a in the following way.
[0209] As in the case of the first embodiment, in the fuel cell
system of the present embodiment the hydrogen generator 1 generates
hydrogen gas and the fuel cell 3 generates electric power by the
use of the generated hydrogen gas and air. And, water generated
during the electric power generation is recovered by the water
recovering portion 5 and the recovered water is stored in the tank
6a of the water storing portion 6. In addition, water supplied from
the cooling water tank 61 is likewise stored in the tank 6a. In
this way, the water thus held in the tank 6a is heated at a heating
temperature of about 90 degrees Centigrade for a predetermined
length of time by the heater 6b.
[0210] In the case where undesirable germs having resistance to
heat multiply, it is necessary to apply heat to the water at a
temperature high enough to eliminate the germs. However, if the
heater 6b performs heat processing at such a high temperature, this
accompanies water vapor generation, as a result of which the
pressure of the inside of the water storing portion 6 increases.
Therefore, the water storing portion 6 is required to have
considerable resistance to pressure. This may increase the
production costs of a fuel cell system. To cope with this problem,
the water vapor exhausting valve 13 of the water storing portion 6
is operated based on the control signal outputted from the
controller 7 so that water vapor accompanied by heating treatment
by the heater 6b is emitted. This makes it possible to avoid the
rise in pressure of the inside of the water storing portion 6.
[0211] The water vapor discharged through the water vapor
exhausting valve 13 is exhausted to outside the fuel cell system
and, at the same time, is supplied to the hydrogen generator 1 and
utilized in a reforming reaction for hydrogen gas generation.
Because of such arrangement, thermal energy consumed during water
vapor generation is utilized effectively.
[0212] In addition, the fuel cell system of the present embodiment
may be provided, between the water storing portion 6 and the water
purifier 11, with a cooler 12. In addition, it is possible to
prevent water decay more definitely by cleaning the inside of the
tank as in the case of the sixth embodiment or by drying the inside
of the tank as in the case of the seventh embodiment.
Embodiment 12
[0213] A fuel cell system formed in accordance with a twelfth
embodiment of the present invention is configured such that the
tank of the water storing portion is divided into two tanks as in
the case of the eighth embodiment for allowing the water purifier
to operate efficiently.
[0214] Referring to FIG. 15, there is shown a block diagram
illustrating a constructional arrangement of the fuel cell system
according to the twelfth embodiment. As shown in FIG. 15, the water
storing portion 6 of the fuel cell system of the present embodiment
is provided with a heater 6b having an electric heater for heating
the tank 6a and a temperature sensor for measuring the temperature
of heating by the electric heater.
[0215] The controller 7 controls the operation of the heater 6b of
the water storing portion 6 and receives from the water storing
portion 6 a temperature measurement signal representative of a
measured value by the temperature sensor of the heater 6b.
[0216] With respect to other constructional components, the fuel
cell system of the twelfth embodiment and the fuel cell system of
the eighth embodiment are substantially the same. Accordingly, they
are assigned the same reference numerals and their description is
omitted.
[0217] Next, the operation of the fuel cell system of the twelfth
embodiment as constructed above will be described.
[0218] Also in the fuel cell system of the present embodiment, it
is arranged such that the display portion 30 displays discharge
prompting information at predetermined timing in order to draw the
user's or maintenance service provider's attention to the
discharging of water in the tank 6a, as in the case of the first to
fifth embodiments. In addition, apart from this operation, water
decay is prevented definitely by application of heat to the water
in the tank 6a in the following way.
[0219] As in the case of the ninth embodiment, in the fuel cell
system of the present embodiment the hydrogen generator 1 generates
hydrogen gas and the fuel cell 3 generates electric power by the
use of the generated hydrogen gas and air. And, water generated
during the electric power generation is recovered by the water
recovering portion 5. The water recovering portion 5 supplies the
recovered water to the switch 20 so that the recovered water is
supplied to the water storing portion 6. Based on the control
signal outputted from the controller 7, the switch 20 switches the
destination, to which the water supplied from the water recovering
portion 5 is distributed, between the first tank 6a1 and the second
tank 6a2 at predetermined timing. As a result of such arrangement,
the first and second tanks 6a1 and 6a2 are supplied with water in
alternation fashion.
[0220] As in the case of the ninth embodiment, the heater 6b of the
water storing portion 6 repeatedly executes heating treatment at
predetermined intervals of time. Here, the heater 6b performs
heating treatment on the first tank 6a1 and on the second tank 6a2
in alternation. In other words, for example, if the heater 6b
performs heating treatment on the water held in the first tank 6a1,
the next heating treatment will be performed on the water held in
the second tank 6a2.
[0221] The water storing portion 6 supplies the heated water in the
tanks 6a1 and 6a2 to the water purifier 11. Here, the water storing
portion 6 supplies to the water purifier 11 the water held in one
of the tanks that has undergone a longer elapsed time since the
completion of heating treatment than the other. As a result of such
arrangement, the heated water, whose temperature has lowered
sufficiently, is supplied to the water purifier 11.
[0222] If the elapsed time since the completion of heating
treatment is greater than a predetermined length of time, this
increases the probability that undesirable germs grow up.
Accordingly, in such a case, preferably a supply of water is
provided by the other tank.
[0223] And now, as described above, the recovered water supplied
from the water recovering portion 5 by the switch 20 is supplied to
the first tank 6a1 and to the second tank 6a2 in alternation. If it
is arranged such that heating treatment is performed on the water
held in the second tank 6a2 when recovered water is supplied to the
first tank 6a1, i.e., when the first tank 6a1 is in water storing
operation while on the other hand heating treatment is performed on
the water held in the first tank 6a1 when recovered water is
supplied to the second tank 6a2, i.e., when the second tank 6a2 is
in water storing operation, this makes it possible for the heater
6b to perform heating treatment on the first tank 6a1 and on the
second tank 6a2 in alternation, as described above.
[0224] As previously described in the tenth embodiment, if water
heated by the heater 6b to a high temperature is supplied to the
water purifier 11 as it is, there is the danger that the water
purifying function of the activated carbon or ion exchange resin
deteriorates. In the fuel cell system of the present embodiment,
water, whose temperature has lowered sufficiently, is supplied to
the water purifier 11. This makes it possible to prevent the drop
in water purifying function of the water purifier 11.
[0225] In the present embodiment, the water storing portion 6 is
provided with two tanks, i.e., the first and second tanks 6a1 and
6a2. For example, it may be arranged such that the water storing
portion 6 is provided with three or more tanks. In the case where
the water storing portion 6 is provided with three or more tanks,
it may be arranged such that heating treatment by the heater 6b is
sequentially performed on each tank and the water held in a tank
that has first undergone heating treatment is supplied to the water
purifier 11.
[0226] Furthermore, the fuel cell system of the present embodiment
may be provided, between the water storing portion 6 and the water
purifier 11, with a cooler 12, as in the case of the tenth
embodiment. In addition, needless to say, the fuel cell system of
the present embodiment may be provided with a water vapor
exhausting valve 13, as in the case of the eleventh embodiment.
Furthermore, it is possible to prevent water decay more definitely
by cleaning the inside of each tank as in the case of the sixth
embodiment or by drying the inside of each tank as in the case of
the seventh embodiment.
[0227] In addition, a new type of fuel cell system may be
configured by adequate combination of two or more of the foregoing
embodiments.
[0228] Numerous modifications and alternative embodiments of the
invention will be apparent to those skilled in the art in view of
the foregoing description. Accordingly, the description is to be
construed as illustrative only, and is provided for the purpose of
teaching those skilled in the art the best mode of carrying out the
invention. The details of the structure and/or function may be
varied substantially without departing from the sprit of the
invention and all modifications which come within the scope of the
appended claims are reserved.
INDUSTRIAL APPLICABILITY
[0229] The present invention provides fuel cell systems each of
which is useful as an electric power generator capable of producing
electric power at high level of efficiency for their small
size.
[0230] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *