U.S. patent application number 14/616338 was filed with the patent office on 2015-06-04 for hydrogen generator with improved volume efficiency.
This patent application is currently assigned to Intelligent Energy Limited. The applicant listed for this patent is Intelligent Energy Limited. Invention is credited to Jason L. Stimits, Guanghong Zheng.
Application Number | 20150155578 14/616338 |
Document ID | / |
Family ID | 45976550 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150155578 |
Kind Code |
A1 |
Zheng; Guanghong ; et
al. |
June 4, 2015 |
Hydrogen Generator with Improved Volume Efficiency
Abstract
A hydrogen generator with improved volume efficiency and a
method of producing hydrogen gas with the hydrogen generator are
disclosed. A fluid containing a reactant is transported from a
reactant storage area to a reaction area. Hydrogen gas passes
through, and an effluent pass from the reaction area into the
effluent storage area that is in a volume exchanging relationship
with one or both of the reactant storage area and the reaction
area. An initially compressed filter is disposed in the effluent
storage area to remove solids from the hydrogen gas. The filter is
attached to a moveable partition separating the effluent storage
area from the reactant storage area and/or the reaction area, and
the filter expands as the volume of the effluent storage area
increases.
Inventors: |
Zheng; Guanghong; (Westlake,
OH) ; Stimits; Jason L.; (Avon, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Intelligent Energy Limited |
Loughborough |
|
GB |
|
|
Assignee: |
; Intelligent Energy
Limited
Loughborough
GB
|
Family ID: |
45976550 |
Appl. No.: |
14/616338 |
Filed: |
February 6, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13444878 |
Apr 12, 2012 |
8979954 |
|
|
14616338 |
|
|
|
|
61477641 |
Apr 21, 2011 |
|
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Current U.S.
Class: |
422/187 |
Current CPC
Class: |
F17C 11/005 20130101;
B01J 7/00 20130101; Y02E 60/36 20130101; H01M 8/065 20130101; C01B
3/065 20130101; H01M 8/04216 20130101; Y02E 60/32 20130101; Y02E
60/50 20130101; B01J 2219/1923 20130101; C01B 3/06 20130101 |
International
Class: |
H01M 8/06 20060101
H01M008/06; C01B 3/06 20060101 C01B003/06 |
Claims
1. A hydrogen generator comprising: a container; a first reactant
storage area within the container, the first reactant storage area
having a volume and configured to contain a fluid comprising a
first reactant; a reaction area within the container, the reaction
area having a volume; a fluid passage from the first reactant
storage area to the reaction area; an effluent storage area within
the container, the effluent storage area having a volume and
configured to facilitate the passing of hydrogen gas and the
storage of an effluent produced by a reaction of the first reactant
within the reaction area; an effluent passage from the reaction
area to the effluent storage area; an initially compressed filter
within the effluent storage area; a liquid impermeable, gas
permeable component in fluid communication with the effluent
storage area; and a hydrogen outlet; wherein: the initially
compressed filter is configured to expand to contain a portion of
the effluent, the effluent storage area volume is configured to
increased, and at least one of the first reactant storage area
volume and the reaction area volume is configured to decrease
during operation of the hydrogen generator; a moveable partition
separates the effluent storage area from at least one of the first
reactant storage area and the reaction area; and, a portion of the
filter is attached to the moveable partition; and the first
reactant can react to produce hydrogen gas, and all of the hydrogen
gas must pass through a portion of the effluent storage area to
reach the hydrogen outlet.
2. The hydrogen generator according to claim 1, wherein the filter
is configured to apply a force for reducing the first reactant
storage area volume, the reaction area volume or both the first
reactant storage area volume and the reaction area volume during
operation of the hydrogen generator.
3. The hydrogen generator according to claim 2, wherein the
hydrogen generator further comprises a biased component configured
to apply a force for reducing the first reactant storage area
volume, the reaction area volume or both the first reactant storage
area volume and the reaction area volume during operation of the
hydrogen generator.
4. The hydrogen generator according to claim 1, wherein the filter
comprises at least two areas of different porosity prior to
compression.
5. The hydrogen generator according to claim 4, wherein the filter
comprises two distinct components, each having a different porosity
prior to compression.
6. The hydrogen generator according to claim 4, wherein the area of
greatest porosity prior to compression is closest to the effluent
passage and the area of least porosity is closest to the
outlet.
7. The hydrogen generator according to claim 1, wherein the filter
comprises a material that does not have an affinity for a liquid in
the effluent.
8. The hydrogen generator according to claim 7, wherein a portion
of the filter proximate the effluent entryway to the effluent
storage area does not have an affinity for the liquid in the
effluent.
9. The hydrogen generator according to claim 1, wherein the filter
comprises a material that has an affinity for a liquid in the
effluent.
10. The hydrogen generator according to claim 9, wherein a portion
of the filter proximate the liquid impermeable, gas permeable
component has an affinity for the liquid in the effluent.
11. The hydrogen generator according to claim 1, wherein the filter
comprises an open cell foam.
12. The hydrogen generator according to claim 1, wherein the
moveable partition comprises a flexible effluent enclosure within
the effluent storage area, the flexible effluent enclosure has a
volume, and the filter is contained within and attached to a
portion of the flexible effluent enclosure.
13. The hydrogen generator according to claim 12, wherein the
moveable partition further comprises a rigid wall adjacent to the
flexible effluent enclosure.
14. The hydrogen generator according to claim 12, wherein the
volume of the flexible effluent enclosure is configured to increase
during operation of the hydrogen generator.
15. The hydrogen generator according to claim 1, wherein the
moveable partition pulls the filter to expand the filter.
16. The method according to claim 1, wherein the filter comprises
an elastic material, and the filter expands as a result of a
reduction in a compressive stress in the filter.
17. The hydrogen generator according to claim 1, wherein the first
reactant is initially contained within a flexible first reactant
enclosure within the first reactant storage area.
18. The hydrogen generator according to claim 1, wherein the
hydrogen generator further comprises a second reactant.
19. The hydrogen generator according to claim 1, wherein at least
one of the first reactant and the second reactant comprises a
borohydride.
20. A hydrogen generator comprising: a container, a first reactant
storage area within the container, the first reactant storage area
comprising a flexible enclosure having a volume configured to
contain a fluid comprising a first reactant; a reaction area within
the container, the reaction area comprising a flexible enclosure
having a volume; a fluid passage from the first reactant storage
area enclosure to the reaction area enclosure; an effluent storage
area within the container, the effluent storage area comprising a
flexible enclosure having a volume configured to facilitate the
passing of hydrogen gas and an effluent produced by a reaction of
the first reactant within the reaction area; an effluent passage
from the reaction area enclosure to the effluent storage area
enclosure; an initially compressed filter within the effluent
storage area enclosure; a liquid impermeable, gas permeable
component in fluid communication with the effluent storage area;
and a hydrogen outlet; wherein: the initially compressed filter is
configured to expand to contain a portion of the effluent, the
effluent storage area enclosure volume is configured to increased,
and at least one of the first reactant storage area enclosure
volume and the reaction area enclosure volume is configured to
decrease during operation of the hydrogen generator; the flexible
effluent enclosure separates the effluent storage area from at
least one of the first reactant storage area and the reaction area;
a portion of the filter is attached to a portion of the flexible
effluent storage area enclosure; and, the first reactant can react
to produce hydrogen gas, and all of the hydrogen gas must pass
through a portion of the effluent storage area to reach the
hydrogen outlet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of patent application
Ser. No. 13/444,878, filed Apr. 12, 2012, which claims benefit of
U.S. Provisional Patent Application No. 61/477,641, filed Apr. 21,
2011, the contents of which are incorporated in their entirety.
FIELD OF THE INVENTION
[0002] This invention relates to a hydrogen generator, particularly
a hydrogen generator for a fuel cell system, and a method of
producing hydrogen gas with the hydrogen generator.
BACKGROUND
[0003] Interest in fuel cell batteries as power sources for
portable electronic devices has grown. A fuel cell is an
electrochemical cell that uses materials from outside the cell as
the active materials for the positive and negative electrode.
Because a fuel cell does not have to contain all of the active
materials used to generate electricity, the fuel cell can be made
with a small volume relative to the amount of electrical energy
produced compared to other types of batteries.
[0004] Fuel cells can be categorized according to the types of
materials used in the positive electrode (cathode) and negative
electrode (anode) reactions. One category of fuel cell is a
hydrogen fuel cell using hydrogen as the negative electrode active
material and oxygen as the positive electrode active material. When
such a fuel cell is discharged, hydrogen is oxidized at the
negative electrode to produce hydrogen ions and electrons. The
hydrogen ions pass through an electrically nonconductive, ion
permeable separator and the electrons pass through an external
circuit to the positive electrode, where oxygen is reduced.
[0005] In some types of hydrogen fuel cells, hydrogen is formed
from a fuel supplied to the negative electrode side of the fuel
cell. In other types of hydrogen fuel cells, hydrogen gas is
supplied to the fuel cell from a source outside the fuel cell. A
fuel cell system can include a fuel cell battery, including one or
more fuel cells, and a hydrogen source, such as a hydrogen tank or
a hydrogen generator. In some fuel cell systems, the hydrogen
source can be replaced after the hydrogen is depleted. Replaceable
hydrogen sources can be rechargeable or disposable.
[0006] A hydrogen generator uses one or more reactants containing
hydrogen that can react to produce hydrogen gas. The reaction can
be initiated in various ways, such as hydrolysis and thermolysis.
For example, two reactants can produce hydrogen and byproducts when
mixed together. A catalyst can be used to catalyze the reaction.
When the reactants react, reaction products including hydrogen gas
and byproducts are produced.
[0007] In order to minimize the volume of the hydrogen generator,
volume that is initially occupied by the reactants can be used to
accommodate reaction products as the reactants are consumed by
arranging the components of the hydrogen generator in a volume
exchanging configuration. As reactants are consumed, volume that
they had occupied is simultaneously made available to contain
reaction products.
[0008] The hydrogen gas is separated from byproducts and unreacted
reactants, and the gas exits the hydrogen generator and is provided
to the fuel cell battery. Various means for separating the hydrogen
gas are known, including porous filters to separate solids from the
hydrogen gas and gas permeable, liquid impermeable membranes to
separate the hydrogen gas from liquids.
[0009] It is desirable to further improve the volume efficiency of
hydrogen generators while providing for effective separation of the
hydrogen gas from reaction products and unreacted reactants. It is
also desirable to provide a hydrogen generator having a simple
design that is easily manufactured at a low cost.
SUMMARY
[0010] The above advantages are provided by a hydrogen generator
according to the present invention.
[0011] Accordingly, one aspect of the invention is a method of
producing hydrogen gas using a hydrogen generator including a
container; a first reactant storage area within the container, the
first reactant storage area having a volume and containing a liquid
including a first reactant; a reaction area within the container,
the reaction area having a volume; an effluent storage area within
the container, the effluent storage area having a volume; a liquid
passage from the first reactant storage area to the reaction area;
an effluent passage from the reaction area to the effluent storage
area; a compressed filter contained within the effluent storage
area; a liquid impermeable, gas permeable component; and a hydrogen
outlet. The first reactant is moved from the first reactant storage
area, through the liquid passage, to the reaction area; the first
reactant is reacted in the reaction area to produce hydrogen gas
and an effluent; the hydrogen gas and the effluent are moved from
the reaction area, through the effluent passage, to the effluent
storage area; and the hydrogen gas is passed through the filter and
the liquid impermeable, gas permeable component to the outlet. The
first reactant storage area volume, the reaction area volume or
both the first reactant storage area and the reaction area volumes
decrease, the filter expands, and the effluent storage area volume
increases as the first reactant is moved from the first reactant
storage area and the hydrogen gas and the effluent are moved from
the reaction area to the effluent storage area. A moveable
partition separates the effluent storage area from at least one of
the first reactant storage area and the reaction area, and a
portion of the filter is attached to the moveable partition. All
hydrogen gas passing to the outlet passes through the effluent
storage area.
[0012] Embodiments of the first aspect of the invention can include
one or more of the following features:
[0013] one or both of the expanding filter and a biased component
applies a force to the first reactant storage area volume, the
reaction area volume or both the first reactant storage area volume
and the reaction area volume as the effluent is moved to the
effluent storage area;
[0014] the filter has at least two areas of different porosity
prior to compression; the filter can include at least two distinct
components of different porosities prior to compression; preferably
the area of greatest porosity prior to compression is closest to
the effluent passage and the area of least porosity is closest to
the liquid impermeable, gas permeable component;
[0015] the filter includes a material that does not have an
affinity for a liquid in the effluent; preferably a portion of the
filter proximate the effluent entryway to the effluent storage area
does not have an affinity for the liquid in the effluent;
[0016] the filter includes a material that has an affinity for a
liquid in the effluent; preferably a portion of the filter
proximate the liquid impermeable, gas permeable component has an
affinity for the liquid in the effluent;
[0017] the filter includes an open cell foam;
[0018] the moveable partition includes a flexible effluent
enclosure within the effluent storage area, the flexible effluent
enclosure has a volume, and the filter is contained within and
attached to a portion of the flexible effluent enclosure; the
moveable partition can further include a rigid wall adjacent to the
flexible effluent enclosure; the volume of the flexible effluent
enclosure can increase as the hydrogen gas and the effluent are
moved to the effluent storage area;
[0019] the moveable partition can pull the filter to expand the
filter;
[0020] the filter includes an elastic material, and the filter
expands as a result of a reduction in a compressive stress in the
filter;
[0021] the first reactant is initially contained within a flexible
first reactant enclosure within the first reactant storage area;
and
[0022] the hydrogen generator includes a second reactant, and the
second reactant reacts with the first reactant in the reaction
area; the second reactant can be stored within the reaction area;
the reaction area can include a catalyst configured to catalyze the
reaction of the first and second reactants; the second reactant can
be initially contained within a flexible second reactant enclosure
within the reaction area; the flexible second reactant enclosure
can be wrapped with a biasing component that applies a force to
reduce the volume of the second reactant container as the hydrogen
gas and the effluent are moved to the effluent storage area; at
least one of the first reactant and the second reactant includes a
borohydride; at least one of the first reactant and the second
reactant is part of a composition that includes at least one of an
acid and a metal compound catalyst.
[0023] A second aspect of the invention is a hydrogen generator
including a container; a first reactant storage area within the
container, the first reactant storage area having a volume and
configured to contain a first liquid reactant; a reaction area
within the container, the reaction area having a volume; a liquid
passage from the first reactant storage area to the reaction area;
an effluent storage area within the container, the effluent storage
area having a volume and configured to store hydrogen gas and an
effluent produced by a reaction of the first reactant within the
reaction area; an effluent passage from the reaction area to the
effluent storage area; an initially compressed filter within the
effluent storage area; a liquid impermeable, gas permeable
component in fluid communication with the effluent storage area;
and a hydrogen outlet. The initially compressed filter is
configured to expand to contain a portion of the effluent, the
effluent storage area volume is configured to increased, and at
least one of the first reactant storage area volume and the
reaction area volume is configured to decrease during operation of
the hydrogen generator. A moveable partition separates the effluent
storage area from at least one of the first reactant storage area
and the reaction area, and a portion of the filter is attached to
the moveable partition. The first reactant can react to produce
hydrogen gas, and all of the hydrogen gas must pass through a
portion of the effluent storage area to reach the hydrogen
outlet.
[0024] Embodiments of the second aspect of the invention can
include one or more of the following features:
[0025] the filter is configured to apply a force for reducing the
first reactant storage area volume, the reaction area volume or
both the first reactant storage area volume and the reaction area
volume during operation of the hydrogen generator;
[0026] the hydrogen generator further includes a biased component
configured to apply a force for reducing the first reactant storage
area volume, the reaction area volume or both the first reactant
storage area volume and the reaction area volume during operation
of the hydrogen generator;
[0027] the filter has at least two areas of different porosity
prior to compression; the filter can include two distinct
components, each having a different porosity prior to compression;
preferably the area of greatest porosity prior to compression is
closest to the effluent passage and the area of least porosity is
closest to the outlet;
[0028] the filter includes a material that does not have an
affinity for a liquid in the effluent;
[0029] preferably a portion of the filter proximate the effluent
entryway to the effluent storage area does not have an affinity for
the liquid in the effluent;
[0030] the filter includes a material that has an affinity for a
liquid in the effluent; preferably a portion of the filter
proximate the liquid impermeable, gas permeable component has an
affinity for the liquid in the effluent;
[0031] the filter includes an open cell foam;
[0032] the moveable partition includes a flexible effluent
enclosure within the effluent storage area, the flexible effluent
enclosure has a volume, and the filter is contained within and
attached to a portion of the flexible effluent enclosure; the
moveable partition can further includes a rigid wall adjacent to
the flexible effluent enclosure; the volume of the flexible
effluent enclosure can be configured to increase during operation
of the hydrogen generator;
[0033] the filter includes an elastic material, and the filter
expands as a result of a reduction in a compressive stress in the
filter;
[0034] the first reactant is initially contained within a flexible
first reactant container within the first reactant storage
area;
[0035] the hydrogen generator further includes a second reactant;
the second reactant can be initially contained within a flexible
second reactant container within the reaction area; the flexible
second reactant container can be wrapped with a biasing component
configured to apply a force to reduce the volume of the second
reactant container as the first reactant and the second reactant
react; at least one of the first reactant and the second reactant
can include a borohydride; at least one of the first reactant and
the second reactant can be part of a composition that includes at
least one of an acid and a metal compound catalyst; and
[0036] the reaction area further includes a catalyst.
[0037] A third aspect of the invention is a hydrogen generator
including a container; a first reactant storage area within the
container, the first reactant storage area including a flexible
enclosure having a volume configured to contain a fluid including a
first reactant; a reaction area within the container, the reaction
area including a flexible enclosure having a volume; a fluid
passage from the first reactant storage area enclosure to the
reaction area enclosure; an effluent storage area within the
container, the effluent storage area including a flexible enclosure
having a volume configured to store hydrogen gas and an effluent
produced by a reaction of the first reactant within the reaction
area; an effluent passage from the reaction area enclosure to the
effluent storage area enclosure; a liquid impermeable, gas
permeable component in fluid communication with the effluent
storage area; and a hydrogen outlet. The flexible effluent
enclosure separates the effluent storage area from at least one of
the first reactant storage area and the reaction area. The hydrogen
generator also includes an initially compressed filter within the
effluent storage area enclosure; wherein a portion of the filter is
attached to a portion of the flexible effluent storage area
enclosure. The initially compressed filter is configured to expand
to contain a portion of the effluent, the effluent storage area
enclosure volume is configured to increased, and at least one of
the first reactant storage area enclosure volume and the reaction
area enclosure volume is configured to decrease during operation of
the hydrogen generator. The first reactant can react to produce
hydrogen gas, and all of the hydrogen gas must pass through a
portion of the effluent storage area to reach the hydrogen
outlet.
[0038] Embodiments of the third aspect of the invention can include
one or more of the additional features of the second aspect of the
invention disclosed above.
[0039] These and other features, advantages and objects of the
present invention will be further understood and appreciated by
those skilled in the art by reference to the following
specification, claims and appended drawings.
[0040] Unless otherwise specified, the following definitions and
methods are used herein: [0041] "effluent" means non-gaseous
reaction products and unreacted reactants, solvents and additives;
[0042] "expand" when used in describing a filter means for the
filter material to simultaneously increase in volume, increase in
porosity and decrease in density and pertains only to the material
of which the filter is made; [0043] "flexible" means capable of
changing shape, e.g., by stretching, bending, folding, unfolding,
and so on; [0044] "initial" means the condition of a hydrogen
generator in an unused or fresh (e.g., refilled) state, before
initiating a reaction to generate hydrogen; [0045] "volume
exchanging relationship" means a relationship between two or more
areas or containers within a hydrogen generator such that a
quantity of volume lost by one or more of the areas or containers
is simultaneously gained by one or more of the other areas or
containers; the volume thus exchanged is not necessarily the same
physical space, so volume lost in one place can be gained in
another place.
[0046] Unless otherwise specified herein, all disclosed
characteristics and ranges are as determined at room temperature
(20-25.degree. C.).
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] In the drawings:
[0048] FIG. 1A is a schematic diagram of a first arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0049] FIG. 1B is a schematic diagram of a first arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0050] FIG. 2A is a schematic diagram of a second arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0051] FIG. 2B is a schematic diagram of a second arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0052] FIG. 3A is a schematic diagram of a third arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0053] FIG. 3B is a schematic diagram of a third arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0054] FIG. 4A is a schematic diagram of a fourth arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0055] FIG. 4B is a schematic diagram of a fourth arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0056] FIG. 5A is a schematic diagram of a fifth arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0057] FIG. 5B is a schematic diagram of a fifth arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0058] FIG. 6A is a schematic diagram of a sixth arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0059] FIG. 6B is a schematic diagram of a sixth arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0060] FIG. 7A is a schematic diagram of a seventh arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0061] FIG. 7B is a schematic diagram of a seventh arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0062] FIG. 8A is a schematic diagram of a eighth arrangement of a
reactant storage area, a reaction area and an effluent storage area
before use of hydrogen generator;
[0063] FIG. 8B is a schematic diagram of a eighth arrangement of a
reactant storage area, a reaction area and an effluent storage area
after use of hydrogen generator;
[0064] FIG. 9 is a cross-sectional drawing of a first embodiment of
a hydrogen generator; and
[0065] FIG. 10 is a cross-sectional drawing of a second embodiment
of a hydrogen generator.
DETAILED DESCRIPTION
[0066] The present invention includes a separate hydrogen gas
generator that can be incorporated into a fuel cell system
including a fuel cell battery, but it is not part of the fuel cell
itself. It is typically a removable, replaceable or refillable unit
that can supply hydrogen to a fuel cell, rather than supplying a
liquid or other fluid that is reformed by or within the fuel cell
to produce hydrogen gas or protons.
[0067] The fuel cell with which the hydrogen generator can be used
can be a battery containing a single fuel cell, or it can be a
battery containing a plurality of fuel cells (sometimes referred to
as a fuel cell stack). The fuel cell can be any type of fuel cell
that uses hydrogen as a fuel. Examples include proton exchange
membrane fuel cells, alkaline fuel cells and solid oxide fuel
cells.
[0068] In one embodiment of the invention a hydrogen generator
includes a container with one or more reactant storage areas, a
reaction area and an effluent storage area within the container.
One or more reactant-containing fluids, each containing one or more
reactants, are transferred from the reactant storage area or areas
to the reaction area, where the reactant or reactants react to
produce hydrogen gas and byproducts. One or more reactants can also
be initially contained within the reaction area. Reaction can be a
catalyzed by a catalyst, which can be initially in the reaction
area or contained in a fluid transferred to the reaction area. The
byproducts can include gaseous, liquid and solid reaction products.
The production of hydrogen gas forces effluent from the reaction
area, through an effluent passage, to the effluent storage area.
The effluent can include reaction byproducts as well as unreacted
reactants and additives.
[0069] The reactant-containing fluid can be a liquid or other
easily transported fluid. The reactant can be the fluid (e.g.,
water), or the reactant can be mixed, suspended, dissolved or
otherwise contained in a liquid. After the fluid is transported
from the reactant storage area to the reaction area, it reacts to
produce hydrogen gas. In one embodiment the reactant or reactants
react upon contact with a catalyst in the reaction area. In another
embodiment two fluids, one or both including a reactant, are
transported to the reaction area. The fluids may come in contact
with each other in an intermediate mixing area or within the
reaction area, where they react to produce hydrogen gas; the
reaction may be catalyzed by a catalyst, which can be initially
contained in the reaction area or in a fluid transported to the
reaction area. In yet another embodiment one reactant is contained
in the reaction area, preferably in a solid form, and another
reactant is transported from the reactant storage area to the
reaction area, where the reactants react to produce hydrogen gas;
the reaction may be catalyzed by a catalyst in the reaction
area.
[0070] The reactant storage, reaction and effluent storage areas
are arranged in a volume exchanging configuration such that, as
reactants are consumed during operation of the hydrogen generator,
the effluent storage area simultaneously increases in volume by
moving into space made available by a reduction in volume of the
areas initially containing reactant to accommodate the effluent
within the effluent storage area. In this way the total volume of
the hydrogen generator can be minimized, since the amount of
initial void volume within the hydrogen generator can be kept at a
minimum (though some initial void volume may be necessary, if the
solid and liquid reaction products have a greater volume than the
initial total volume of the reactants for example). Any suitable
volume exchanging configuration can be used. For example, one or
more areas containing reactant (e.g., a reactant storage area
and/or a reaction area containing a reactant) can be adjacent to
the effluent storage area, or the effluent storage area can be
separated from the areas containing reactant by one or more other
components of the hydrogen generator that can move or otherwise
allow the volume exchange.
[0071] Hydrogen gas is separated from the liquid and solid effluent
and is released through the hydrogen outlet to an apparatus such as
a fuel cell as needed. A filter and a hydrogen permeable, liquid
impermeable component are used to separate the hydrogen. The filter
removes solids and may remove liquids as well, and the hydrogen
permeable, liquid impermeable component removes liquids and any
remaining solids, allowing only gas to pass through the hydrogen
outlet. Optionally, other components may be included within or
downstream from the hydrogen generator to remove other gases and
impurities from the hydrogen flow.
[0072] The filter is initially compressed within the effluent
storage area to reduce its initial volume and porosity. As the
hydrogen generator is operated and the effluent storage area
increases in volume, the filter expands. This has several
advantages. First, the filter is initially smaller in size,
allowing the effluent storage area to be smaller initially, thereby
contributing to the volumetric efficiency of the hydrogen
generator. Second, the filter can better conform to the size of the
effluent storage area and reduce the flow of effluent around the
filter as the effluent storage area becomes larger. Third, as the
filter becomes more porous it may be better able to continue to
remove particulate material without becoming clogged. Fourth, the
filter can provide a force (in addition to any force applied by the
hydrogen gas, the effluent and any other component, such as a
biasing component) to facilitate the increase in volume of the
effluent storage area.
[0073] In various embodiments, as space becomes available as a
result of the volume exchange, the filter can expand due to its
elasticity, by being pulled by another internal component of the
hydrogen generator to which the filter is attached, by a biasing
member within or surrounded by the filter, by some other means, or
a combination thereof. For example, an elastic material can expand
due to a reduction in compressive stress. It is advantageous for a
portion of the filter to be attached to a moveable partition that
separates the effluent storage area from the first reactant storage
area and/or the reaction area. This can assure that the partition
and the filter move together, preventing a gap from forming between
the filter and the partition and preventing effluent from bypassing
the filter by flowing through the gap. The filter can also be
attached to other components within or surrounding the effluent
storage area (such as a wall on the opposite side of the filter
from the moveable partition) to prevent gaps from forming around
other portions of the filter as the filter expands. For example,
one portion of the filter can be attached to an internal surface of
the housing, and an opposite portion of the filter can be attached
to the moveable partition. The filter can help to move the moveable
partition and enlarge the effluent storage area as the hydrogen
generator is used, or the moveable partition can pull the attached
portion of the filter (e.g., away from the housing surface to which
the filter is also attached), expanding the filter. In addition to
or instead of being moved by force applied by the expanding filter,
the moveable partition can be moved by a biasing member such as a
spring or by a pressure differential on opposite sides of the
partition, for example. In yet another example, one or more springs
can be disposed within the filter so the filter is forced to expand
by the springs. In one embodiment the moving partition can be a
wall, such as a rigid wall, between the effluent storage area and
one or both of the first reactant storage area and the reaction
area. In another embodiment the moving partition can be a flexible
effluent enclosure (described in detail below) enclosing the
effluent storage area and containing the filter. In yet another
embodiment the moving partition includes both a flexible effluent
enclosure and a separate wall between the effluent storage area and
at least one of the first reactant storage area and the reaction
area. The filter can be attached to the moveable partition in any
suitable manner, such as adhering with an adhesive, fastening with
one or more fasteners (e.g., clamps, screws, rivets and the like),
or strapping with one or more straps (e.g., cords, bands, belts and
the like).
[0074] The filter can be a single component filter. It can have a
uniform composition and porosity before compression, or the
composition and porosity can vary. In one embodiment the filter
before compression is more porous in an upstream portion (the
portion that will be closer to the effluent passage) and less
porous in a downstream portion (the portion that will be closer to
the hydrogen outlet). In this way the filter can remove larger
particles in the upstream portion while allowing smaller particles
to pass to the downstream portion, to help prevent clogging of the
filter.
[0075] The filter can be a multi-component filter, at least one
component of which is initially compressed and expands during
operation of the hydrogen generator. Two or more components can
have different porosities before compression. It can be
advantageous for a higher porosity filter component to be located
at the upstream side of the filter and a lower porosity filter
component to be located at the downstream side of the filter. If
there are more than two filter components, they can be arranged
according to porosity, with the more porous filter components being
upstream from the less porous filter components. The individual
filter components can be of uniform or non-uniform composition and
porosity. All filter components can be made of the same type of
material, or different materials can be used for individual filter
components. Two or more filter components can be joined together to
create a laminar filter having different layers. Filter components
can be joined by any suitable method, such as by bonding with an
adhesive.
[0076] The filter material and the amount of initial compression
can be selected, based at least in part on the expected amount and
composition of the effluent, to provide at least a minimum filter
porosity at all times as the filter expands and retains a portion
of the effluent during use of the hydrogen generator, such that
sufficient hydrogen gas can reach the hydrogen permeable, liquid
impermeable component and the outlet to provide at least a minimum
desired hydrogen flow rate.
[0077] Desirable properties of the filter components and the
materials from which they are made include: chemical stability in
contact with the effluent during at least the expected duration of
use, compressibility, the ability to expand or be expanded to the
desired extent after being compressed before and during use, and
porosity and pore size distribution within the desired ranges
before and during use. Affinity or lack of affinity for liquid in
the effluent can also be considered in material selection.
[0078] In one embodiment, at least a portion of the filter is made
from a material that does not have an affinity for, and may even
tend to repel liquid in the effluent. For example, where the
effluent contains an aqueous liquid, a portion of the filter may be
a material that is not hydrophilic and may be hydrophobic. If only
a portion of the filter does not have an affinity for or tends to
repel liquid in the effluent, preferably at least that portion of
the filter is proximal to the effluent entryway to the effluent
storage area. In this way the portion of the filter proximal to the
effluent entryway can remove solids from the hydrogen gas flow, and
as the filter expands the filter can accommodate an increasing
amount of solids. In this embodiment, it may be possible to avoid
premature blocking of the pores in that portion of the filter due
to swelling that may accompany absorption of liquid.
[0079] In another embodiment, at least a portion of the filter is
made from a material that has an affinity for liquid in the
effluent. For example, where the effluent contains an aqueous
liquid, a portion of the filter may be hydrophilic. If only a
portion of the filter has an affinity for liquid in the effluent,
preferably at least that portion of the filter is proximal to the
liquid-impermeable, gas-permeable component and/or the hydrogen
outlet has an affinity for liquid in the effluent. In this way the
portion of the filter can absorb liquid that may have solids
dissolved therein and prevent blockage of the liquid-impermeable,
gas-permeable component and/or the hydrogen outlet.
[0080] In yet another embodiment, the filter has both a portion
that does not have an affinity for, and may even tend to repel
liquid in the effluent, and another portion that has an affinity
for liquid in the effluent. The portion that does not have an
affinity for liquid in the effluent is proximal the effluent
entryway to the effluent storage area, and the portion that has an
affinity for liquid in the effluent is proximal one or both of the
liquid-impermeable, gas-permeable component and/or the hydrogen
outlet.
[0081] The hydrogen permeable, liquid impermeable component can be
located within the effluent storage area, within the hydrogen
outlet, or at an interface between the outlet and either or both of
the effluent storage area and a hydrogen passage from the outlet to
the fuel cell. In some embodiments it is highly permeable to
hydrogen and less permeable to other gases that may be present with
the hydrogen, as byproducts or contaminants for example. The
hydrogen permeable, liquid impermeable material can be any suitable
form, such as a sheet, a membrane or a non-planar form.
[0082] Filter components, the hydrogen permeable, liquid
impermeable material or both can be coated or partially filled with
one or more other materials such as a catalyst to facilitate
reaction of unreacted reactants contained in the effluent, an
ion-exchange resin to capture detrimental impurities in the
effluent, a defoamer to break up gas bubbles in the effluent, and a
surfactant to improve the flowability of the effluent.
[0083] Any or all of the reactant storage area(s), the reaction
area and the effluent storage area can be defined by one or more of
the internal surfaces of the container and other components of the
hydrogen generator, or one or more of these areas can be enclosed
by an enclosure, such as a reactant storage enclosure, a reaction
area enclosure or an effluent storage area enclosure. Such
enclosures are able to undergo a change in shape (e.g., by being
flexible) so their internal volume can decrease or increase as
material exits or enters the enclosure. An enclosure can include a
structure such as a bag, a balloon or a bellows, for example. The
walls of an enclosure can be pleated or made from an elastomeric
material that can stretch or contract, for example, to enable a
change in internal volume. In one embodiment, an enclosure can have
a wall or a portion of a wall that can stretch to provide a larger
internal volume and can apply a force to the contents to facilitate
emptying the contents.
[0084] In one embodiment, the effluent storage area is enclosed by
an enclosure. One or more filter components can be fastened to the
enclosure in one or more places to minimize the amount of effluent
that can flow around the filter component. The enclosure can be or
can include a hydrogen permeable, liquid impermeable material to
separate hydrogen gas from liquids in the effluent storage
area.
[0085] A fluid including a reactant can be transported from the
reactant storage area by any suitable means. For example, it can be
wicked, pumped, expelled by applying a force on the liquid, or a
combination thereof. If the fluid is pumped, the pump can be within
or outside the hydrogen generator. The pump can be powered by the
fuel cell, a battery within the hydrogen generator, or an external
power source. A force can be applied directly against a reactant
storage area enclosure, against a moveable partition in contact
with the enclosure, or against one or more other components that
make contact with or are a part of the enclosure (such as a valve
assembly) for example. Force can be provided in various ways, such
as with a spring, an elastic reactant storage enclosure that is
initially stretched when full, wrapping the reactant storage
enclosure with an elastic member, air or gas pressure on or within
the reactant storage enclosure, the expansion of the filter in the
effluent storage area, or a combination thereof.
[0086] The flow path of the fluid reactant composition to and
within the reactant area can include various components such as
tubes, wicks connections, valves, etc. Within the reaction area the
fluid reactant composition can be dispersed by a dispersing member
to improve the distribution of fresh reactant. The dispersing
member can include one or more structures extending into or within
the reaction area. The structures can be tubular or can have other
shapes. At least a portion of the dispersing member can be flexible
so it can move as the reactant composition and/or the reaction area
change shape during operation of the hydrogen generator. In one
embodiment the dispersing member can include a tube with holes or
slits therein through which the fluid reactant composition can
exit. In another embodiment the dispersing member can include a
porous material through which the fluid reactant composition can
permeate. In another embodiment the dispersing member can include a
material through which the fluid reactant composition can wick. In
yet another embodiment a sleeve of wicking material is provide
around another component of the dispersing member. This can keep
solid reaction byproducts from forming on the other component and
clogging the holes, slits, pores, etc., and preventing the flow of
fluid reaction composition.
[0087] The generation of hydrogen gas can be controlled so hydrogen
is produced as needed. Control can be based on one or more
criteria, such as: pressure (e.g., internal pressure or a
differential between an internal and an external pressure);
temperature (e.g., hydrogen generator, fuel cell or device
temperature); a fuel cell electrical condition (e.g., voltage,
current or power); or a device criterion (e.g., internal battery
condition, power input, or operating mode.
[0088] The hydrogen generator can use a variety of reactants that
can react to produce hydrogen gas. Examples include chemical
hydrides, alkali metal silicides, metal/silica gels, water,
alcohols, dilute acids and organic fuels (e.g., N-ethylcarbazole
and perhydrofluorene).
[0089] As used herein, the term "chemical hydride" is broadly
intended to be any hydride capable of reacting with a liquid to
produce hydrogen. Examples of chemical hydrides that are suitable
for use in the hydrogen generating apparatus described herein
include, but are not limited to, hydrides of elements of Groups
IA-IVA of the Periodic Table and mixtures thereof, such as alkaline
or alkali metal hydrides, or mixtures thereof. Specific examples of
chemical hydrides include lithium hydride, lithium aluminum
hydride, lithium borohydride, sodium hydride, sodium borohydride,
potassium hydride, potassium borohydride, magnesium hydride,
calcium hydride, and salts and/or derivatives thereof. In an
embodiment, a chemical hydride such as sodium borohydride can react
with water to produce hydrogen gas and a byproduct such as a
borate. This can be in the presence of a catalyst, heat, a dilute
acid or a combination thereof.
[0090] An alkali metal silicide is the product of mixing an alkali
metal with silicon in an inert atmosphere and heating the resulting
mixture to a temperature of below about 475.degree. C., wherein the
alkali metal silicide composition does not react with dry 0.sub.2.
Such alkali metal silicides are described in US Patent Publication
2006/0002839. While any alkali metal, including sodium, potassium,
cesium and rubidium may be used, it is preferred that the alkali
metal used in the alkali metal silicide composition be either
sodium or potassium. Metal silicides including a Group IIA metal
(beryllium, magnesium, calcium, strontium, barium and radium) may
also be suitable. In an embodiment, sodium silicide can react with
water to produce hydrogen gas and sodium silicate, which is soluble
in water.
[0091] A metal/silica gel includes a Group IA metal/silica gel
composition. The composition has a Group IA metal absorbed into the
silica gel pores. The Group IA metals include sodium, potassium,
rubidium, cesium and alloys of two or more Group IA metals. The
Group IA metal/silica gel composition does not react with dry
0.sub.2. Such Group IA metal/silica gel compositions are described
in U.S. Pat. No. 7,410,567 B2 and can react rapidly with water to
produce hydrogen gas. A Group IIA metal/silica gel composition,
including one or more of the Group IIA metals (beryllium,
magnesium, calcium, strontium, barium and radium) may also be
suitable.
[0092] The reactant composition contained in the reactant storage
area is a fluid that can be transported from the reactant storage
area to the reaction area. The fluid can be or include a liquid
such as water, alcohol, a dilute acid, or a combination thereof. A
reactant can be mixed, dissolved or suspended in the liquid, as
long as there is no substantial reaction prior to reaching the
reaction area. For example, the fluid can be a chemical hydride
dissolved in water and the chemical hydride does not react with the
water until the reaction is initiated by contact with a catalyst,
heat or acid in the reaction area.
[0093] One or more catalysts can be used to catalyze the hydrogen
producing reactions. Examples of suitable catalysts include
transition metals from Group VIII (iron, cobalt, nickel, ruthenium,
rhodium, palladium, osmium, iridium and platinum), Group IB
(copper, silver and gold) and Group IIB (zinc, cadmium and mercury)
of the Periodic Table of the Elements, as well as other transition
metals including scandium, titanium, vanadium, chromium and
manganese. Suitable catalysts also include metal salts, such as
chlorides, oxides, nitrates and acetates. Some metal salts can be
dissolved in a reactant-containing fluid.
[0094] Additives can be used for various purposes. For example,
additives can be included with a solid reactant as a binder to hold
the solid material in a desired shape or as a lubricant to
facilitate the process of forming the desired shape. Other
additives can be included with a liquid or solid reactant
composition to control pH, to control the rate of reaction for
example. Such additives include but are not limited to acids (e.g.,
hydrochloric, nitric, acetic, sulfuric, citric, carbonic, malic,
phosphoric and acetic acids or combinations thereof), or basic
compounds. Additives such as alcohols and polyethylene glycol based
compounds can be used to prevent freezing of the fluid. Additives
such as surfactants or wetting agents can be used to control the
liquid surface tension and reaction product viscosity to facilitate
the flow of hydrogen gas and/or effluents. Additives such as porous
fibers (e.g., polyvinyl alcohol and rayon) can help maintain the
porosity of a solid reactant component and facilitate even
distribution of the reactant containing fluid and/or the flow of
hydrogen and effluents.
[0095] In one embodiment a chemical hydride such as sodium
borohydride (SBH) is one reactant, and water is another reactant.
The SBH can be a component of a liquid such as water. The SBH and
water can react when they come in contact with a catalyst, acid or
heat in the reaction chamber. The SBH can be stored as a solid in
the reaction area. It can be present as a powder or formed into a
desired shape. If an increased rate of reaction between the SBH and
the water is desired, a solid acid, such as malic acid, can be
mixed with the SBH, or acid can be added to the water. Solid (e.g.
powdered) SBH can be formed into a mass, such as a block, tablet or
pellet, to reduce the amount of unreacted SBH contained in the
effluent that exits the reaction area. As used below, "pellet"
refers to a mass of any suitable shape or size into which a solid
reactant and other ingredients are formed. The pellet should be
shaped so that it will provide a large contact surface area between
the solid and liquid reactants. Preferably water is another
reactant. For example, a mixture including about 50 to 65 weight
percent SBH, about 30 to 40 weight percent malic acid and about 1
to 5 weight percent polyethylene glycol can be pressed into a
pellet. Optionally, up to about 3 weight percent surfactant
(anti-foaming agent). up to about 3 weight percent silica
(anti-caking agent) and/or up to about 3 weight percent powder
processing rheology aids can be included. The density of the pellet
can be adjusted, depending in part on the desired volume of
hydrogen and the maximum rate at which hydrogen is to be produced.
A high density is desired to produce a large amount of hydrogen
from a given volume. On the other hand, if the pellet is too
porous, unreacted SBH can more easily break away and be flushed
from the reaction area as part of the effluent. One or more pellets
of this solid reactant composition can be used in the hydrogen
generator, depending on the desired volume of hydrogen to be
produced by the hydrogen generator. The ratio of water to SBH in
the hydrogen generator can be varied, based in part on the desired
amount of hydrogen and the desired rate of hydrogen production. If
the ratio is too low, the SBH utilization can be too low, and if
the ratio is too high, the amount of hydrogen produced can be too
low because there is insufficient volume available in the hydrogen
generator for the amount of SBH that is needed.
[0096] It may be desirable to provide for cooling of the hydrogen
generator during use, since the hydrogen generation reactions can
produce heat. The housing may be designed to provide coolant
channels. In one embodiment standoff ribs can be provided on one or
more external surfaces of the housing and/or interfacial surfaces
with the fuel cell system or device in or on which the hydrogen
generator is installed or mounted for use. In another embodiment
the hydrogen generator can include an external jacket around the
housing, with coolant channels between the housing and external
jacket. Any suitable coolant can be used, such as water or air. The
coolant can flow by convection or by other means such as pumping or
blowing. Materials can be selected and/or structures, such as fins,
can be added to the hydrogen generator to facilitate heat
transfer.
[0097] It may also be desirable to provide means for heating the
hydrogen generator, particularly at startup and/or during operation
at low temperatures.
[0098] The hydrogen generator can include other components, such as
control system components for controlling the rate of hydrogen
generation (e.g., pressure and temperature monitoring components,
valves, timers, etc.), safety components such as pressure relief
vents, thermal management components, electronic components, and so
on. Some components used in the operation of the hydrogen generator
can be located externally rather than being part of the hydrogen
generator itself, making more space available within the hydrogen
generator and reducing the cost by allowing the same components to
be reused even though the hydrogen generator is replaced.
[0099] The hydrogen generator can be disposable or refillable. For
a refillable hydrogen generator, reactant filling ports can be
included in the housing, or fresh reactants can be loaded by
opening the housing and replacing containers of reactants. If an
external pump is used to pump fluid reactant composition from the
reaction storage area to the reactant area, an external connection
that functions as a fluid reactant composition outlet to the pump
can also be used to refill the hydrogen generator with fresh fluid
reactant composition. Filling ports can also be advantageous when
assembling a new hydrogen generator, whether it is disposable or
refillable. If the hydrogen generator is disposable, it can be
advantageous to dispose components with life expectancies greater
than that of the hydrogen generator externally, such as in the fuel
cell system or an electrical appliance, especially when those
components are expensive.
[0100] The reactant storage area, reaction area and effluent
storage area can be arranged in many different ways, as long as
effluent storage area is in a volume exchanging relationship with
one or both of the reactant storage and reaction areas that will
allow the initially compressed filter to expand as the effluent
storage area increases in volume. Other considerations in selecting
an arrangement include thermal management (adequate heat for the
desired reaction rate and dissipation of heat generated by the
reactions), the desired locations of external connections (e.g.,
for hydrogen gas, fluid reactant flow to and from an external
pump), any necessary electrical connections (e.g., for pressure and
temperature monitoring and control of fluid reactant flow rate),
and ease of assembly.
[0101] FIGS. 1 A to 8B illustrates various possible arrangements of
the reactant storage area 1, the reaction area 2 and the effluent
storage area 3 of a hydrogen generator. Each pair of drawing
figures A and B shows a comparison of relative sizes of the
components before and after using the hydrogen generator,
respectively. These drawings are not to scale and do not show any
other components of the hydrogen generator. They show only a few of
many possible arrangements that can be used.
[0102] FIGS. 1 A and 1B show an arrangement with the reactant
storage area 1 and the reaction area 2 separated by the effluent
storage area 3. As clear from a comparison of FIG. 1A with FIG. 1B,
the effluent storage area 3 is in a volume exchanging relationship
with both the reactant storage area 1 and the reaction area 2.
[0103] FIGS. 2A and 2B show an arrangement similar to the
arrangement in FIGS. 1A and 1B, except that the effluent storage
area 3 is on one end rather than between the reactant storage area
1 and the reaction area 2. Although in FIGS. 2A and 2B the effluent
storage area is adjacent to the reaction area 2, the areas 1, 2 and
3 can be arranged with the effluent storage area 3 adjacent to the
reactant storage area. Even though the effluent storage area 3 is
adjacent to only one of the other two areas, it is in a volume
exchanging relationship with both since the amount of volume
increase in the effluent storage area 3 includes volume reductions
in both the reactant storage area 1 and the reaction area 2.
[0104] FIGS. 3A and 3B also show an arrangement similar to the
arrangement in FIGS. 1A and 1B, except that while the areas 1, 2
and 3 are arranged in a horizontal or linear configuration in FIGS.
1A and 1B, they are arranged in a vertical or stacked configuration
in FIGS. 3A and 3B. The sequence of the areas 1, 2 and 3 in a
stacked configuration can also be varied, in a similar manner as
described above with reference to FIGS. 2A and 2B.
[0105] FIGS. 4A and 4B show another arrangement with two of the
areas (areas 1 and 2) side by side, stacked on the other area (area
3). As described above, the locations of the individual areas 1, 2
and 3 can be varied in this type of arrangement.
[0106] FIGS. 5A and 5B, as well as FIGS. 6A and 6B, show
arrangements in which one of the areas 1, 2 and 3 is adjacent to
more than one side of another of the areas 1, 2 and 3. As described
above, the locations of the individual areas 1, 2 and 3 can be
interchanged in these types of arrangements.
[0107] The arrangement shown in FIGS. 7A and 7B shows one reaction
area 2, with an effluent storage area 3 adjacent to two opposite
sides of the reaction area 2, and a reactant storage area 1
adjacent to each of the effluent storage areas 3. In some
embodiments the two effluent storage areas 3 can be different
portions of a single effluent storage area 3, joined by another
portion(s) of effluent storage area 3 in another plane(s), and/or
the two reactant storage areas 2 can be different portions of a
single reactant storage area 1, joined by another portion(s) of
reaction storage area 1 in another plane(s). As in the arrangements
described above, the locations of areas 1, 2 and 3 in FIGS. 7A and
7B can be interchanged.
[0108] The arrangement in FIG. 8A is similar to the arrangement in
FIG. 4A in that two areas are side by side and stacked on top of
the other area before use of the hydrogen generator. However, FIGS.
8A and 8B illustrate an embodiment in which the increase in volume
of the effluent storage area 3 is less than the sum of the volume
reductions of the reactant storage area 1 and the reaction area 2,
or an embodiment in which the effluent storage area 3 is in a
volume exchanging relationship with only one of the other two areas
(the reaction area 2 in this example, but it could be the reaction
storage area 1 in another example). As shown in FIG. 8B, as
reactant in the reactant storage area 1 is used volume initially
occupied by the reactant that is removed from the reactant storage
area 1 becomes unoccupied as the hydrogen generator is used, as
represented by the "empty area" 4. Similar embodiments are possible
with other arrangements, including those represented by FIGS. 1A to
7B.
[0109] Embodiments of a hydrogen generator are described below with
reference to FIGS. 9 and 10. The hydrogen generators 10 and 100
include a reactant storage area 14, a reaction area 16 and an
effluent storage area 18 within a housing 12. A first reactant
composition 20 is contained within the reactant storage area 14,
and a second reactant composition 22 is contained within the
reaction area 16. The first reactant composition 20 is a fluid that
can be transported to the reaction area 16. The second reactant
composition 22 can be a fluid or, as shown in FIGS. 9 and 10, it
can be a solid. The effluent storage area 18 includes a filter,
which can have one or more filter components, such as three filter
components 24, 26, 28. The reactant storage area 14 is enclosed by
an enclosure 30. The reaction area 16 can be at least partially
enclosed by an optional enclosure 32. The effluent storage area 18
can be enclosed by an optional enclosure (not shown). Various types
of enclosures can be used for the reactant storage area 14, the
reaction area 16 and the effluent storage area 18. For example, an
enclosure can include internal surfaces of the housing 12, other
internal components of the hydrogen generator 10, 100 and/or it can
share a common wall or section with one or more other enclosures.
All or portions of the enclosures can be flexible, rigid,
stationary or moveable, as long as the effluent storage area 18 is
in a volume exchanging relationship with at least one of the
reactant storage area 14 and the reaction area 16. As shown in
FIGS. 9 and 10, the enclosures 30 and 32 enclosing the reactant
storage area 14 and the reaction area 16, respectively, are
flexible enclosures that can collapse on contact as first reactant
composition 20 exits the reaction storage area 14 and effluent
exits the reaction area 16. Examples of flexible enclosures include
bags, balloons and bellows. It can be advantageous for flexible
enclosures to be elastic so they can be stretched when full and
tend to contract back to their original size as the contents exit,
thereby helping to expel fluids as the hydrogen generator 10, 100
is operated.
[0110] During use of the hydrogen generator 10, 100, first reactant
composition 20 is transported from the reactant storage area 14 to
the reaction area 16 by any suitable means, as described above. For
example, the first reactant composition 20 can be transported
through a fluid outlet passage 34. If a pump is used, the pump 54
can be within the housing 12 as shown in FIG. 10, or it can be
located externally as in the embodiment in FIG. 9. When a pump 54
is used, the first reactant composition 20 can be pumped through
the fluid outlet passage 34, such as a tube, and, as shown in FIG.
9, a fluid outlet connection 36 to the pump. Optional features,
such as valves, filters and the like can be incorporated into the
fluid outlet passage 34 or the fluid outlet connection 36. An
external pump 54 can pump the first reactant composition 20 back
into the hydrogen generator 10, 100 through a fluid inlet
connection 38. The first reactant composition 29 can flow to the
reactant area 16 through a fluid inlet passage 40, such as a tube.
Optional features such as valves, filters and the like can be
incorporated into the fluid inlet connection 38. The first reactant
composition 20 can exit the fluid inlet passage 40 directly from an
opening in the end of the fluid inlet passage 40 or be delivered
though a dispersing member 42 to disperse the first reactant
composition over a larger portion of the reaction area 16. The
dispersing member 42 can include one or more structures that extend
into the reaction area 16. The structures can be essentially
linear, as shown in FIGS. 9 and 10, or they can have other shapes,
as described above.
[0111] When an internal or external pump 54 is used, it can be
powered at least initially by an external power source, such as the
fuel cell or another battery within a fuel cell system or an
electrical appliance. If the pump 54 is within the container 12
(FIG. 10), connection can be made to an external power source
through electrical contacts 56. Alternatively, a battery can be
located within the container to at least start the pump 54.
[0112] The second reactant composition 22 can be a solid
composition containing a second reactant that will react with the
first reactant in the first reactant composition 20. The second
reactant composition 22 can be in a convenient form such as a
pellet containing the second reactant and any desired additives. An
optional catalyst can be included in or downstream from the
reaction area. For example, the catalyst can be on or part of the
reaction area enclosure 32, dispersed in the second reactant
composition 22, or carried into the reaction area as part of the
first reactant composition 20.
[0113] As the first reactant composition 20 comes in contact with
the second reactant composition 22, the first and second reactants
react to produce hydrogen gas and byproducts. The hydrogen gas
flows out of the reaction area 22 and through an effluent passage
to an effluent entryway 46, where it enters the effluent storage
area 18. The hydrogen gas carries with it effluent that includes
byproducts as well as unreacted reactants and other constituents of
the reactant compositions 20, 22. Where a reaction area enclosure
32 is used, the effluent exits the reaction area though an aperture
in the enclosure 32. The opening in the reaction area enclosure 32
can include an effluent exit nozzle 44, which can help keep the
aperture open. The effluent exit nozzle 44 can optionally include a
screen to hold large pieces of the second reactant composition 22
in the reaction area 16 to improve utilization of the second
reactant. The effluent passageway can be a structure such as a tube
(not shown) extending between the effluent exit nozzle 44 and the
effluent entryway 46, or it can be spaces that are present or
develop between the effluent exit nozzle 44 and the effluent entry
46, as in FIGS. 9 and 10. Although it is desirable for the majority
of the reactants to react within the reaction area 16, unreacted
reactants in the effluent can continue to react after exiting the
reaction area 16. An optional secondary reaction area (not shown)
can be included between the primary reaction area 16 and the
effluent storage area 18. Fresh first reactant composition 20 can
be transported directly to this secondary reaction area, such as
through a second fluid passage (not shown), to react with unreacted
second reactant in the effluent from the primary reaction area 16.
A catalyst can be disposed within the secondary reaction area.
[0114] Hydrogen gas and effluent entering a proximal portion of the
effluent storage area 18 through the effluent entryway 46 flows
through the filter 24, 26, 28 toward a distal portion of the
effluent storage area 18. As the hydrogen gas and effluent flow
through the filter 24, 26, 28, hydrogen gas is separated from solid
particles of the effluent by the filter 24, 26, 28, which can be a
single filter component or multiple filter components, such as the
three filter components 24, 26, 28 shown in FIGS. 9 and 10. As
described above, the filter 24, 26, 28 can have portions and/or
filter components of different porosities, preferably increasing in
porosity from the proximal portion toward the distal portion of the
effluent storage area 18, where the hydrogen gas exits the effluent
storage area 18.
[0115] The hydrogen gas is separated from liquids and any remaining
solids in the effluent before exiting the hydrogen generator 10,
100 by a hydrogen permeable, liquid impermeable material 58. The
hydrogen gas can exit the hydrogen generator 10, 100 through a
hydrogen outlet connection 50. The hydrogen outlet connection 50
can be located near the distal portion of the effluent storage area
18 as shown in FIG. 10, or it can be located elsewhere, such as
near the proximal portion of the effluent storage area 18 as shown
in FIG. 9. If the hydrogen outlet connection 50 is not near the
distal portion of the effluent storage area 18, the hydrogen gas
can flow from the distal portion of the effluent storage area 18 to
the hydrogen outlet connection 50 through a hydrogen outlet passage
48, such as a tube, which has a proximal end near the hydrogen
outlet connection and a distal end 52 near the distal portion of
the effluent storage area 18. The hydrogen gas can enter the
hydrogen outlet passage 48 through the distal end 52. The hydrogen
permeable, gas impermeable material 58 can be a component, such as
a membrane, plug or filter element, preferably located at or near
the distal end 52, or at least a portion of the hydrogen passage 48
can be made of a material that has high hydrogen permeability and
low or no liquid permeability. If only a portion of the hydrogen
passage 48 is made from a material with high hydrogen, low liquid
permeability, that portion is preferably a distal portion to
minimize the amount of solids in the effluent that comes in contact
with and could clog the material, preventing hydrogen gas from
exiting the effluent storage area 18.
[0116] If the hydrogen outlet connection 50 is located near the
distal portion of the effluent storage area 18 as in FIG. 10, the
hydrogen generator 10, 100 can include an optional compartment 60
positioned between the hydrogen outlet connection 50 and the
hydrogen permeable, liquid impermeable material 58. Alternatively,
at least a portion of an effluent storage area enclosure (e.g., a
flexible bag) near the distal portion of the effluent storage area
18 can be the hydrogen permeable and liquid impermeable
material.
[0117] As shown in FIGS. 9 and 10, the effluent storage area 18 can
be in a volume exchanging relationship with both the reactant
storage area 14 and the reaction area 16. As the hydrogen generator
10, 100 is used, reactant composition 20 is transported from the
first reactant storage area 14, which becomes smaller, to the
reactant area 16, where first and second reactants are consumed as
they react to produce hydrogen and byproducts. The hydrogen gas and
effluents exit the reaction area 16, which becomes smaller, and
enter the effluent storage area 18, which is able to become larger
by gaining at least a portion of the quantity of volume lost by the
reactant storage area 14 and the reaction area 16. As the effluent
storage area 18 becomes larger, the filter or at least one filter
component 24, 26, 28 expands to partially or completely fill the
enlarged volume and accommodate the hydrogen gas and effluent. The
relative sizes, shapes and locations of the areas 14, 16, 18 can be
varied as described above, as can passageways, connections and the
like, as long as the effluent storage area 18 is in a volume
exchanging relationship with at least one and preferably both of
the reactant storage area 14 and the reaction area 16, and the
filter 24, 26, 28 is initially compressed and expands during
operation of the hydrogen generator as the volume of the effluent
storage area 18 increases. The locations of other components, such
as filter components, fluid connections, passageways, dispersing
members, nozzles and the like can also be varied, whether the areas
14, 16, 18 are in the arrangement shown in FIG. 9 or FIG. 10 or in
another arrangement.
[0118] The hydrogen generator 10, 100 can include an optional
moveable partition 62, as shown in FIG. 10, between the effluent
storage area 18 and adjacent portions of the reactant storage area
14 and the reaction area 16, with the moveable partition able to
move toward the reactant storage area 14 and the reaction area 16
as those two areas 14, 16 become smaller and the effluent storage
area 18 becomes larger during operation of the hydrogen generator
10, as long as there is a effluent entryway 46 through which
effluent can pass into the effluent storage area 18. Such a
moveable partition 62 can be used to facilitate compression of the
filter components 24, 26, 28 during assembly of the hydrogen
generator 10, 100. The hydrogen generator 10, 100 can include other
components not shown in FIG. 9 or FIG. 10, as described above.
[0119] A variety of materials are suitable for use in a hydrogen
generator, including those disclosed above. Materials selected
should be resistant to attack by other components with which they
may come in contact (such as reactant compositions, catalysts,
effluent materials and hydrogen gas) as well as materials from the
external environment. The materials and their important properties
should also be stable over the expected temperature ranges during
storage and use, and over the expected lifetime of the hydrogen
generator.
[0120] Suitable materials for the housing and internal partitions
can include metals, plastics, composites and others. Preferably the
material is a rigid material that is able to tolerate expected
internal pressures, such as a polycarbonate or a metal such as
stainless steel or anodized aluminum. The housing can be a
multi-component housing that is closed and sealed to securely hold
the components of the hydrogen generator and prevent hydrogen gas
from leaking therefrom. Various methods of closing and sealing can
be used, including fasteners such as screws, rivets, etc.,
adhesives, hot melts, ultrasonic bonding, and combinations
thereof.
[0121] Suitable materials for flexible enclosures can include
polypropylene, polyethylene, polyethylene terephthalate and
laminates with a layer of metal such as aluminum. If an elastic
enclosure is desired, suitable materials include silicone and
rubbers.
[0122] Suitable materials for tubing, etc., used to transport fluid
reactant composition and effluents can include silicone, TYGON.RTM.
and polytetrafluoroethylene.
[0123] Suitable materials for filters and filter components can
include foam materials. A foam material can have an open cell
structure (an open cell foam) or closed cell structure (a closed
cell foam). Generally a major part of the foam filter will have an
open cell structure. In some embodiments the filter component or a
portion thereof can have a closed cell structure or a skin on one
or more surfaces, depending on the desired porosity and
permeability to solids, liquids and gases. The filter components
can be made from elastomeric foams, preferable with a quick
recovery (low compression set/high recovery). The elastomer may be
a resilient cured, cross-linked or vulcanized elastomer, for
example. Examples of suitable elastomeric materials include one or
more of: a polyurethane elastomer, a polyethylene, a
polychloroprene (neoprene), a polybutadiene, a chloro isobutylene
isoprene, a chlorosulphonated polyethylene, an epichlorohydrin, an
ethylene propylene, an ethylene propylene diene monomer, an
ethylene vinyl acetate, a hydrogenated nitrile butadiene, a
polyisoprene, an isoprene, an isoprene butylene, a butadiene
acrylonitrile, a styrene butadiene, a fluoroelastomer, a silicone,
and derivatives and combinations thereof.
[0124] Other materials that can be used for the filter components
include reticulated materials such as reticulated polyesters (e.g.,
polyethylene terephthalate), polyethylene, polyurethane, polyimide,
melamine, nylon, fiberglass, polyester wool and acrylic yam. As
disclosed above, the filter does not necessarily have to be made of
a material that can expand by itself after being compressed if
another means of expanding the filter is provided.
[0125] Suitable materials for a dispersing member can include a
liquid impermeable material, such as tubular or other hollow
components made from materials such as silicone rubber, TYGON.RTM.
and polytetrafluoroethylene, polyvinylidene fluoride (PVDF) and
fluorinated ethylene-propylene (FEP), with holes or slits formed
therein; a liquid permeable member made from a material such as
cotton, a nylon, an acrylic, a polyester, ePTFE, or a fitted glass
that can allow the fluid reactant composition to pass through or
that can wick the fluid reactant composition; or a combination,
such as a hollow liquid impermeable material with holes or slits
therein and wrapped in, surrounded by or coated with a material
that can wick the fluid reactant composition.
[0126] All references cited herein are expressly incorporated
herein by reference in their entireties. To the extent publications
and patents or patent applications incorporated by reference
contradict the disclosure contained in the present specification,
the present specification is intended to supersede and/or take
precedence over any such contradictory material.
[0127] It will be understood by those who practice the invention
and those skilled in the art that various modifications and
improvements may be made to the invention without departing from
the spirit of the disclosed concept. The scope of protection
afforded is to be determined by the claims and by the breadth of
interpretation allowed by law.
* * * * *