U.S. patent application number 12/712733 was filed with the patent office on 2010-09-02 for water electrolysis system.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. Invention is credited to Koji NAKAZAWA, Masanori OKABE, Jun TAKEUCHI, Kenji TARUYA.
Application Number | 20100219066 12/712733 |
Document ID | / |
Family ID | 42666541 |
Filed Date | 2010-09-02 |
United States Patent
Application |
20100219066 |
Kind Code |
A1 |
TAKEUCHI; Jun ; et
al. |
September 2, 2010 |
WATER ELECTROLYSIS SYSTEM
Abstract
A water electrolysis system includes a water electrolysis
apparatus for electrolyzing pure water supplied from a pure water
supply apparatus for manufacturing high-pressure hydrogen. The
water electrolysis apparatus has a pipe serving as a hydrogen
outlet to which a gas-liquid separator, a cooler, and a water
adsorption apparatus are successively connected in this order along
the direction in which hydrogen is discharged from the water
electrolysis apparatus. A first back-pressure valve is connected
between the cooler and the water adsorption apparatus, and a second
back-pressure valve is connected downstream of the water adsorption
apparatus.
Inventors: |
TAKEUCHI; Jun;
(Utsunomiya-shi, JP) ; OKABE; Masanori;
(Nerima-ku, JP) ; NAKAZAWA; Koji; (Utsunomiya-shi,
JP) ; TARUYA; Kenji; (Utsunomiya-shi, JP) |
Correspondence
Address: |
LAHIVE & COCKFIELD, LLP;FLOOR 30, SUITE 3000
ONE POST OFFICE SQUARE
BOSTON
MA
02109
US
|
Assignee: |
HONDA MOTOR CO., LTD.
Tokyo
JP
|
Family ID: |
42666541 |
Appl. No.: |
12/712733 |
Filed: |
February 25, 2010 |
Current U.S.
Class: |
204/242 |
Current CPC
Class: |
Y02E 60/50 20130101;
C25B 1/04 20130101; C25B 15/08 20130101; H01M 8/0656 20130101; Y02E
60/36 20130101 |
Class at
Publication: |
204/242 |
International
Class: |
C25B 9/00 20060101
C25B009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2009 |
JP |
2009-045708 |
Claims
1. A water electrolysis system comprising: a water electrolysis
apparatus for electrolyzing water with an electric current supplied
from a DC power supply to generate hydrogen and oxygen; a water
adsorption apparatus disposed downstream of and connected to a
hydrogen outlet of the water electrolysis apparatus, for adsorbing
water contained in the hydrogen discharged from the hydrogen
outlet; a first pressure regulating valve connected between the
hydrogen outlet and the water adsorption apparatus; and a second
pressure regulating valve connected downstream of the water
adsorption apparatus.
2. A water electrolysis system according to claim 1, wherein the
second pressure regulating valve has a preset pressure which is
higher than a preset pressure of the first pressure regulating
valve.
3. A water electrolysis system according to claim 1, further
comprising a gas-liquid separator and a cooler, wherein the
gas-liquid separator, the cooler, and the first pressure regulating
valve are successively positioned in this order between the
hydrogen outlet and the water adsorption apparatus, along a
direction in which the hydrogen flows.
4. A water electrolysis system according to claim 1, wherein each
of the first pressure regulating valve and the second pressure
regulating valve comprises a back-pressure valve.
5. A water electrolysis system according to claim 1, wherein the
water electrolysis apparatus discharges the hydrogen under a
pressure higher than a normal pressure.
6. A water electrolysis system according to claim 1, further
comprising a bleeder passage having an on-off valve, the bleeder
passage being connected between the first pressure regulating valve
and the water adsorbing apparatus.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Patent Application No. 2009-045708 filed on Feb. 27,
2009, in the Japan Patent Office, of which the contents are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a water electrolysis system
having a water electrolysis apparatus for electrolyzing water with
an electric current supplied from a DC power supply to generate
hydrogen and oxygen, and a water adsorbing apparatus for adsorbing
water in the hydrogen generated by the water electrolysis
apparatus, the water adsorbing apparatus being connected downstream
of a hydrogen discharge port of the water electrolysis apparatus
which discharges the hydrogen.
[0004] 2. Description of the Related Art
[0005] Solid polymer electrolyte fuel cells generate DC electric
energy when anodes thereof are supplied with a fuel gas, i.e., a
gas mainly composed of hydrogen, e.g., a hydrogen gas, and cathodes
thereof are supplied with an oxygen-containing gas, a gas mainly
composed of oxygen, e.g., air.
[0006] Generally, water electrolysis apparatus are used to generate
a hydrogen gas for use as a fuel gas for such solid polymer
electrolyte fuel cells. The water electrolysis apparatus employ a
solid polymer electrolyte membrane (ion exchange membrane) for
decomposing water to generate hydrogen (and oxygen). Electrode
catalytic layers are disposed on the respective sides of the solid
polymer electrolyte membrane, making up a membrane electrode
assembly. Electric feeders are disposed on the respective sides of
the membrane electrode assembly, making up a unit. The unit is
essentially similar in structure to the fuel cells described
above.
[0007] A plurality of such units are stacked, and a voltage is
applied across the stack while water is supplied to the electric
feeders on the anode side. On the anodes of the membrane electrode
assemblies, the water is decomposed to produce hydrogen ions
(protons). The hydrogen ions move through the solid polymer
electrolyte membranes to the cathodes, where the hydrogen ions
combine with electrons to generate hydrogen. On the anodes, oxygen
generated together with hydrogen is discharged with excess water
from the units.
[0008] Such a water electrolysis system generates hydrogen under a
high pressure of several tens MPa. Japanese Laid-Open Patent
Publication No. 2007-100204 discloses a method of and an apparatus
for manufacturing high-pressure hydrogen. As shown in FIG. 7 of the
accompanying drawings, the disclosed apparatus for manufacturing
high-pressure hydrogen comprises a high-pressure oxygen vessel 1, a
differential pressure regulator 2, a high-pressure hydrogen vessel
3, an electrolytic cell 4, a water adsorption tube 5, a
back-pressure valve 6, and a deoxidization tube 7.
[0009] Pure water contained in the high-pressure oxygen vessel 1 is
delivered to an anode side of the electrolytic cell 4 by a
circulation pump 8. The pure water delivered to the electrolytic
cell 4 is electrolyzed when the electrolytic cell 4 is energized by
a power supply 9. Oxygen generated from the pure water by the
electrolytic cell 4 is delivered, together with returning pure
water from the circulation pump 8, to the high-pressure oxygen
vessel 1.
[0010] Hydrogen generated at the cathode of the electrolytic cell 4
is discharged, together with permeated water, into the
high-pressure hydrogen vessel 3. At this time, the differential
pressure regulator 2 equalizes the pressure in the high-pressure
oxygen vessel 1 and the pressure in the high-pressure hydrogen
vessel 3 to each other.
[0011] The hydrogen stored in the high-pressure hydrogen vessel 3
is delivered to the deoxidization tube 7, which removes oxygen
contained in the hydrogen. The hydrogen is then delivered from the
deoxidization tube 7 through the back-pressure valve 6 to the water
adsorption tube 5, which removes water from the hydrogen, thereby
finalizing the hydrogen as a product.
[0012] According to Japanese Laid-Open Patent Publication No.
2007-100204, the high-pressure hydrogen stored in the high-pressure
hydrogen vessel 3 may be abruptly introduced through the
back-pressure valve 6 into the water adsorption tube 5. When the
high-pressure hydrogen is abruptly introduced into the water
adsorption tube 5, the water adsorption tube 5 may not be able to
adsorb water well from the high-pressure hydrogen because the
high-pressure hydrogen flows at an excessively high speed. In order
for the water adsorption tube 5 to have a high water adsorbing
capability, it needs to have a large amount of adsorbent. However,
the water adsorption tube 5 with a large amount of adsorbent will
become considerably large in size and is not economical.
[0013] In addition, if the pressure difference between the water
adsorption tube 5 and the hydrogen tank of a fuel cell vehicle is
large, then the water adsorption tube 5 is likely to be released
from the pressure. When the water adsorption tube 5 is released
from the pressure, the adsorbed water tends to be released from the
adsorbent in the water adsorption tube 5 and introduced into the
hydrogen tank.
SUMMARY OF THE INVENTION
[0014] It is an object of the present invention to provide a water
electrolysis system of simple structure which is capable of
reliably preventing water contained in hydrogen from passing
through a water adsorption apparatus and hence of efficiently
supplying desired dry hydrogen.
[0015] According to the present invention, a water electrolysis
system includes a water electrolysis apparatus for electrolyzing
water with an electric current supplied from a DC power supply to
generate hydrogen and oxygen, and a water adsorption apparatus
connected downstream of and connected to a hydrogen outlet of the
water electrolysis apparatus, for adsorbing water contained in the
hydrogen discharged from the hydrogen outlet.
[0016] The water electrolysis system has a first pressure
regulating valve connected between the hydrogen outlet and the
water adsorption apparatus, and a second pressure regulating valve
connected downstream of the water adsorption apparatus.
[0017] According to the present invention, since the second
pressure regulating valve is connected downstream of the water
adsorption apparatus, the pressure acting in the water adsorbing
apparatus can be kept at a preset pressure. Therefore, hydrogen
containing water does not quickly flow through the water adsorbing
apparatus, which is thus able to reliably adsorb the water
contained in the hydrogen. Further, as the pressure acting in the
water adsorbing apparatus is kept at a preset pressure, the
adsorbed water in the water adsorbing apparatus is prevented from
being released therefrom and flowing downstream of the water
adsorbing apparatus.
[0018] Further, the first pressure regulating valve is connected
between the hydrogen outlet and the water adsorbing apparatus. As a
result, the water adsorbing apparatus can be isolated from the
region upstream thereof. Thus, the water adsorbing apparatus, for
example, can be cleaned easily and efficiently. Therefore, the
water electrolysis system is of a relatively simple structure for
reliably preventing water contained in the hydrogen from passing
through the water adsorbing apparatus, and also for efficiently
supplying desired dry hydrogen.
[0019] The above and other objects, features, and advantages of the
present invention will become more apparent from the following
description when taken in conjunction with the accompanying
drawings in which a preferred embodiment of the present invention
is shown by way of illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic diagram of a water electrolysis system
according to an embodiment of the present invention;
[0021] FIG. 2 is a diagram illustrative of the manner in which the
pressures on first and second back-pressure valves of the water
electrolysis system change with time;
[0022] FIG. 3 is a schematic diagram illustrative of a pressure
increase up to the first back-pressure valve;
[0023] FIG. 4 is a schematic diagram illustrative of a pressure
increase up to the second back-pressure valve;
[0024] FIG. 5 is a diagram illustrative of the manner in which the
pressures on the second back-pressure valve change with time when
the water electrolysis system resumes its operation;
[0025] FIG. 6 is a diagram illustrative of the manner in which the
pressures on the first and second back-pressure valves change with
time when a water adsorption apparatus is released from the
pressure and the water electrolysis system resumes its operation;
and
[0026] FIG. 7 is a schematic diagram of an apparatus for
manufacturing high-pressure hydrogen disclosed in Japanese
Laid-Open Patent Publication No. 2007-100204.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] As shown in FIG. 1, a water electrolysis system 10 according
to an embodiment of the present invention comprises a water
electrolysis apparatus 14 for being supplied with pure water that
has been generated from city water from a pure water supply
apparatus 12 and electrolyzing the pure water to produce
high-pressure hydrogen (whose pressure is higher than a normal
pressure), a gas-liquid separator 18 for removing water contained
in the high-pressure hydrogen which is delivered from the water
electrolysis apparatus 14 into a hydrogen outlet passage 16, a
cooler 20 for cooling the hydrogen discharged from the gas-liquid
separator 18, a water adsorbing apparatus 22 for adsorbing away
water contained in the cooled hydrogen discharged from the cooler
20, and a hydrogen tank 26 for storing the hydrogen (dry hydrogen)
delivered from the water adsorbing apparatus 22 into a dry hydrogen
supply passage 24. The hydrogen tank 26 is optional, and may be
added when necessary or may be dispensed with.
[0028] The water electrolysis apparatus 14 comprises a stack of
water decomposition cells 28 and a pair of end plates 30a, 30b
disposed respectively on the opposite ends of the stack of water
decomposition cells 28. An electrolytic power supply 32 in the form
of a DC power supply is connected across the water electrolysis
apparatus 14. The water electrolysis apparatus 14 has an anode
connected to the positive terminal of the electrolytic power supply
32 and a cathode connected to the negative terminal of the
electrolytic power supply 32.
[0029] A pipe 34a is connected to the end plate 30a, and pipes 34b,
34c are connected to the end plate 30b. The pure water from the
pure water supply apparatus 12 is circulated through a circulation
passage 35 to the pipes 34a, 34b. The pipe 34c, which serves as a
hydrogen outlet, is connected by the hydrogen outlet passage 16 to
the gas-liquid separator 18.
[0030] The hydrogen outlet passage 16 includes a first
back-pressure valve (first pressure regulating valve) 36 connected
between the pipe 34c and the water adsorbing apparatus 22, or more
specifically between the cooler 20 and the water adsorbing
apparatus 22, and a bleeder passage 38 branched from the hydrogen
outlet passage 16 between the first back-pressure valve 36 and the
water adsorbing apparatus 22. The bleeder passage 38 has an on-off
valve, e.g., a solenoid-operated valve 40. The first back-pressure
valve 36 has a first preset pressure.
[0031] The water adsorbing apparatus 22 includes an adsorption
tower (not shown) filled with a water adsorbent (not shown) for
physically adsorbing a water vapor (water) contained in hydrogen,
the water adsorbent being regenerated when it discharges adsorbed
water. The dry hydrogen supply passage 24 is connected downstream
of the water adsorbing apparatus 22, i.e., is connected to the
outlet port of the water adsorbing apparatus 22, through a second
back-pressure valve (second pressure regulating valve) 42. The
second back-pressure valve 42 has a second preset pressure which is
equal to or higher than the first preset pressure of the first
back-pressure valve 36 (see FIG. 2). The first back-pressure valve
36 and the second back-pressure valve 42 may be replaced with
various valves such as solenoid-operated valves.
[0032] The hydrogen tank 26 is connected to the dry hydrogen supply
passage 24. A hydrogen supply passage 46 is connected to the
hydrogen tank 26 through an on-off valve 48. The hydrogen supply
passage 46 can be connected directly or via a reservoir tank, not
shown, to the fuel tank of a fuel cell vehicle 50.
[0033] Operation of the water electrolysis system 10 will be
described below.
[0034] When the water electrolysis system 10 starts to operate, the
water electrolysis apparatus 14 is supplied with pure water that
has been generated from city water from the pure water supply
apparatus 12. The water electrolysis apparatus 14 electrolyzes the
pure water to produce hydrogen when it is energized by the
electrolytic power supply 32.
[0035] The hydrogen generated by the water electrolysis apparatus
14 is delivered through the hydrogen outlet passage 16 to the
gas-liquid separator 18. In the gas-liquid separator 18, a water
vapor contained in the hydrogen is separated from the hydrogen. The
hydrogen is then delivered to the cooler 20 in which it is cooled.
Therefore, the water in the hydrogen is condensed and separated as
condensed water from the hydrogen.
[0036] The first back-pressure valve 36 is connected downstream of
the cooler 20. As shown in FIG. 2, the cooler 20 can pressurized
the hydrogen until the first preset pressure of the first
back-pressure valve 36 is reached, i.e., until time T1 (see FIG.
3). Consequently, the water in the hydrogen is reliably condensed
and separated as condensed water from the hydrogen.
[0037] When the hydrogen pressure in a hydrogen system that ranges
from the water electrolysis apparatus 14 to the cooler 20 increases
to the first preset pressure of the first back-pressure valve 36,
the first back-pressure valve 36 is opened. The high-pressure
hydrogen, i.e., the hydrogen whose pressure has risen to the first
preset pressure, flows through the first back-pressure valve 36
into the water adsorbing apparatus 22. The water adsorbing
apparatus 22 then adsorbs a water vapor contained in the supplied
hydrogen, producing dry hydrogen.
[0038] The second back-pressure valve 42 is connected downstream of
the water adsorbing apparatus 22. Therefore, the dry hydrogen is
held under pressure within the water adsorbing apparatus 22 (see
FIG. 4) until the pressure of the hydrogen in the water adsorbing
apparatus 22 reaches the second preset pressure of the second
back-pressure valve 42, i.e., from time T1 to time T2 (see FIG. 2).
When the pressure of the hydrogen in the water adsorbing apparatus
22 reaches the second preset pressure, the second back-pressure
valve 42 is opened, introducing the dry hydrogen from the water
adsorbing apparatus 22 into the dry hydrogen supply passage 24.
[0039] The dry hydrogen delivered to the dry hydrogen supply
passage 24 is stored in the hydrogen tank 26. When necessary, the
dry hydrogen stored in the hydrogen tank 26 is sent through the
hydrogen supply passage 46 to the fuel cell vehicle 50, filling the
fuel tank thereof, by opening the on-off valve 48.
[0040] According to the present embodiment, the second
back-pressure valve 42 is connected downstream of the water
adsorbing apparatus 22. Therefore, the pressure acting in the water
adsorbing apparatus 22 can be kept at a preset pressure, i.e., the
second preset pressure. Specifically, the speed at which the
hydrogen in the water adsorbing apparatus 22 flows is nil after the
first back-pressure valve 36 disposed upstream of the water
adsorbing apparatus 22 is opened until the second back-pressure
valve 42 is opened, i.e., from time T1 to time T2 shown in FIG.
2.
[0041] Therefore, the hydrogen containing water which is introduced
from the cooler 20 does not quickly flow through the water
adsorbing apparatus 22, which is thus able to reliably adsorb the
water contained in the hydrogen with the water adsorbent (not
shown).
[0042] Since the pressure acting in the water adsorbing apparatus
22 is kept at a preset pressure, the adsorbed water in the water
adsorbing apparatus 22 is prevented from being released from the
water adsorbent and flowing downstream of the water adsorbing
apparatus 22 into the hydrogen tank 26.
[0043] The first back-pressure valve 36 is connected between the
water electrolysis apparatus 14 and the water adsorbing apparatus
22, or more specifically between the cooler 20 and the water
adsorbing apparatus 22. As a result, the water adsorbing apparatus
22 can be isolated from the region upstream thereof, i.e., from the
cooler 20, by the first back-pressure valve 36. Thus, the water
adsorbing apparatus 22 can be cleaned easily and efficiently.
[0044] The water electrolysis system 10 is of a relatively simple
structure for reliably preventing water contained in the hydrogen
from passing through the water adsorbing apparatus 22, and also for
efficiently supplying the desired dry hydrogen.
[0045] The water adsorbing apparatus 22 can be isolated from the
water electrolysis apparatus 14 by the first back-pressure valve
36. When the water electrolysis system 10 is temporarily shut down,
therefore, the interior of the water adsorbing apparatus 22 can be
maintained under a desired pressure. When the water electrolysis
system 10 subsequently resumes its operation at time T3 shown in
FIG. 5, the time required to increase the pressure in the water
adsorbing apparatus 22 is thus effectively shortened.
[0046] For releasing the water adsorbing apparatus 22 from the
pressure when the water adsorbing apparatus 22 is to be cleaned,
the water adsorbing apparatus 22 is shut down and the
solenoid-operated valve 40 is opened, releasing the water adsorbing
apparatus 22 from the pressure at time T4 shown in FIG. 6. When the
water electrolysis system 10 subsequently resumes its operation at
time T5, the pressure from the water electrolysis apparatus 14 to
the water adsorbing apparatus 22 starts to increase at time T6
while the second back-pressure valve 42 is being closed. Therefore,
water contained in the hydrogen does not quickly pass through the
water adsorbing apparatus 22, but is reliably adsorbed by the water
adsorbent (not shown) in the water adsorbing apparatus 22.
[0047] Although a certain preferred embodiment of the present
invention has been shown and described in detail, it should be
understood that various changes and modifications may be made
therein without departing from the scope of the appended
claims.
* * * * *