U.S. patent application number 11/074360 was filed with the patent office on 2005-08-11 for storage, generation, and use of hydrogen.
Invention is credited to Becker, Frederick E., Konduri, Ravi K., Larsen, Christopher A., McClaine, Andrew W., Rolfe, Jonathan L..
Application Number | 20050175868 11/074360 |
Document ID | / |
Family ID | 27808585 |
Filed Date | 2005-08-11 |
United States Patent
Application |
20050175868 |
Kind Code |
A1 |
McClaine, Andrew W. ; et
al. |
August 11, 2005 |
Storage, generation, and use of hydrogen
Abstract
A composition comprising a carrier liquid; a dispersant; and a
chemical hydride. The composition can be used in a hydrogen
generator to generate hydrogen for use, e.g., as a fuel. A
regenerator recovers elemental metal from byproducts of the
hydrogen generation process.
Inventors: |
McClaine, Andrew W.;
(Lexington, MA) ; Rolfe, Jonathan L.; (N. Easton,
MA) ; Larsen, Christopher A.; (Dorchester, MA)
; Konduri, Ravi K.; (Heathrow, FL) ; Becker,
Frederick E.; (Reading, MA) |
Correspondence
Address: |
FISH & RICHARDSON PC
225 FRANKLIN ST
BOSTON
MA
02110
US
|
Family ID: |
27808585 |
Appl. No.: |
11/074360 |
Filed: |
March 7, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11074360 |
Mar 7, 2005 |
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10044813 |
Jan 11, 2002 |
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10044813 |
Jan 11, 2002 |
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09707105 |
Nov 6, 2000 |
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09707105 |
Nov 6, 2000 |
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09309198 |
May 10, 1999 |
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Current U.S.
Class: |
422/236 ;
429/421; 429/515; 44/500 |
Current CPC
Class: |
Y02E 60/36 20130101;
H01M 8/04208 20130101; H01M 8/04216 20130101; Y02E 60/50 20130101;
C01B 3/065 20130101; H01M 8/065 20130101; Y02E 60/32 20130101 |
Class at
Publication: |
429/012 ;
044/500 |
International
Class: |
H01M 008/00; C10L
005/00 |
Goverment Interests
[0003] This invention was made with Government support under
contracts awarded by the U.S. Department of Energy. The Government
has certain rights in the invention.
Claims
1-22. (canceled)
23. Apparatus comprising: a reservoir containing a chemical
hydride, and a mechanism configured to introduce a reactant to
selected different portions of the chemical hydride to effect
hydrogen generating reactions at different locations within the
reservoir.
24. The apparatus of claim 23 in which the reservoir comprises a
canister.
25. The apparatus of claim 23 in which the reservoir includes
chambers that contain chemical hydride.
26. The apparatus of claim 23 in which the mechanism comprises
conduits that have open delivery ends arranged to introduce the
reactant to respective selected portions of the chemical
hydride.
27. The apparatus of claim 23 in which the conduits are arranged in
parallel.
28. The apparatus of claim 27 in which the conduits are located at
different distances along an axis of the reservoir.
29. The apparatus of claim 23 in which the mechanism is configured
to be movable relative to the chemical hydride contained in the
reservoir.
30. The apparatus of claim 16 in which the conduits comprise
needles.
31. The apparatus of claim 23 in which the mechanism includes a
valving system that controls the introduction of the reactant to
the different portions.
32. The apparatus of claim 23 in which the reservoir includes an
exit for hydrogen generated in the reaction.
33. The apparatus of claim 23 in which the chemical hydride is
dispersed in a carrier liquid at a concentration of about 40-75% by
weight of the composition.
34. The apparatus of claim 23 in which the carrier liquid comprises
an organic liquid.
35. The apparatus of claim 23 in which the chemical hydride
comprises a light metal hydride.
36. The apparatus of claim 35 in which the light metal hydride is
selected from the group consisting of lithium hydride, lithium
borohydride, lithium aluminum hydride, sodium hydride, sodium
borohydride, sodium aluminum hydride, magnesium hydride, and
calcium hydride.
37. The apparatus of claim 33 also including a triglyceride acting
as a dispersant.
38. The apparatus of claim 23 in which chemical hydride comprises
lithium hydride.
39. The apparatus of claim 23 in which chemical hydride comprises
magnesium hydride.
40. The apparatus of claim 23 in which the reactant comprises
water.
41-62. (canceled)
Description
[0001] This application claims the benefit of the filing dates of
Provisional U.S. Patent Applications Ser. No. 60/261,616, Hydrogen
Fuel Storage Slurry, Jonathan L. Rolfe et al.; Ser. No. 60/261,601,
Hydrogen Fuel Generation Assembly and Method, Christopher A. Larsen
et al.; and Ser. No. 60/261,600, Regeneration Assembly and Method
for Converting Metal Oxides and Metal Hydroxides to Elemental
Metals, Ravi Konduri et al., all of which were filed on Jan. 12,
2001, and all of which are incorporated here by reference in their
entireties.
[0002] This application is a continuation-in-part of U.S. patent
application Ser. No. 09/707,105, Disposable Hydrogen Fuel Source,
filed Nov. 6, 2000, which is a divisional of U.S. patent
application Ser. No. 09/309,198, filed May 10, 1999, now abandoned,
and is incorporated by reference here in its entirety.
BACKGROUND
[0004] This invention relates to the storage, generation, and use
of hydrogen.
[0005] Traditional storage technologies for hydrogen include
bottled compressed hydrogen gas and bottled liquid hydrogen. The
use of such technologies has been limited because of dangers in
storage and in handling and transporting. Hydrogen gas and
cryogenic liquid in storage or transport have evidenced instability
and high combustibility.
[0006] Hydrogen also has been incorporated into metal hydrides from
which the hydrogen can be released by the application of water.
U.S. Pat. No. 4,155,712, issued May 22, 1979, to Walter G. Taschek,
discloses a hydrogen generator in which water vapor is combined
with a metal hydride, preferably calcium hydride (CaH.sub.2) or
lithium aluminum hydride (LiAlH.sub.4) to release hydrogen
(H.sub.2) stored in the hydride. U.S. Pat. No. 4,261,955, issued
Apr. 14, 1981, to Cornelius E. Bailey, Jr., et al, describes
subjecting a metal hydride, such as calcium hydride, to water vapor
to generate essentially pure hydrogen.
[0007] Known hydrogen-fueled power devices include fuel cells,
internal combustion engines, and other devices.
[0008] Mixing a light metal hydride, such as lithium hydride and a
reactant, such as water to produce hydrogen also produces, as a
byproduct, a hydroxide of the elemental metal, lithium hydroxide.
Although the generation of hydrogen in such a process can occur on
a continuing basis, the byproduct, i.e., the lithium hydroxide,
accumulates until removed.
SUMMARY
[0009] In general, in one aspect, the invention features a
composition comprising a carrier liquid; a dispersant; and a
chemical hydride. Implementations of the invention may include one
or more of the following features. The chemical hydride has a
concentration of at least 40% by weight of the composition. In some
examples, the chemical hydride has a concentration of less than 75%
by weight of the composition, for example, about 61%. In other
examples, the chemical hydride has a concentration of more than
90%. The carrier liquid includes an organic liquid. The organic
liquid includes mineral oil, e.g., a light mineral oil. The carrier
liquid includes a hydrocarbon. The hydrocarbon includes an alkane.
The alkane is selected from a group consisting of pentane and
hexane. The composition is in the form of a slurry. The carrier
liquid has a viscosity in the range of about 32 Saybolt Universal
seconds (S.U.s.) at standard temperature and pressure (STP) to
about 100 S.U.s but preferably about 42 S.U.s. to about 59 S.U.s.
The carrier liquid exhibits a flash point in the range of about
100.degree. C. to about 350.degree. C. and preferably about
154.degree. C. to about 177.degree. C.
[0010] The chemical hydride includes a light metal hydride. The
light metal hydride is selected from the group consisting of
lithium hydride, lithium borohydride, lithium aluminum hydride,
sodium hydride, sodium borohydride, sodium aluminum hydride,
magnesium hydride, and calcium hydride. The chemical hydride
includes lithium hydride.
[0011] The dispersant comprises a triglyceride. The triglyceride
includes a triglyceride of oleic acid. The triglyceride includes
triolein. The chemical hydride includes magnesium hydride.
[0012] In general, in another aspect, the invention features a
method that includes mixing chemical hydride particles and an oil
to form a slurry.
[0013] In general, in another aspect, the invention includes a
composition comprising a mass of chemical hydride particles in a
concentration of about 90-95% by weight of the composition, and an
oil coating the chemical hydride particles, the oil comprising
5-10% by weight of the composition.
[0014] In general, in another aspect, the invention features
apparatus comprising: a reservoir containing a chemical hydride,
and a mechanism configured to introduce a reactant to selected
different portions of the chemical hydride to effect hydrogen
generating reactions at different locations within the
reservoir.
[0015] Implementations of the invention may include one or more of
the following features. The reservoir includes a canister. The
reservoir includes chambers that contain chemical hydride. The
mechanism includes conduits that have open delivery ends arranged
to introduce the reactant to respective selected portions of the
chemical hydride. The conduits are arranged in parallel. The ends
are located at different distances along an axis of the reservoir.
The mechanism is configured to be movable relative to the chemical
hydride contained in the reservoir. The conduits comprise needles.
The mechanism includes a valving system that controls the
introduction of the reactant to the different portions. The
reservoir includes an exit for hydrogen generated in the
reaction.
[0016] In general, in another aspect, the invention features a
hydrogen fuel generation assembly that includes: (a) a reservoir
for a slurry comprising a carrier liquid, a triglyceride
dispersant, and a chemical hydride; (b) a reservoir for water; (c)
a hydride reactor in communication with said slurry reservoir and
said water reservoir and adapted to receive the slurry and water
from the reservoirs, respectively, and to mix the slurry and water
to effect release of hydrogen from the slurry; (d) a tank for
receiving the hydrogen from said reactor and for receiving
hydroxide byproduct from said reactor, and for facilitating
separation of the hydrogen and the hydroxide byproduct; (e) a heat
exchanger for receiving the hydrogen from said tank and adapted to
condense water from the hydrogen; (f) a gas-liquid separator for
receiving hydrogen and water from said heat exchanger and adapted
to separate the water from the hydrogen and to dispense dried
hydrogen; (g) a conduit for conveying the water from said separator
to said water reservoir; and (h) a conduit for conveying the dried
hydrogen to a hydrogen-fueled power-producing device.
[0017] Implementations of the invention may include one or more of
the following features. The reactor includes a tubular housing and
a mixer for mixing the slurry and the water. The tank is provided
with an outlet for flowing hydrogen gas from the tank, and a bottom
portion for the receiving of the hydroxide byproduct. The
power-producing device includes a selected one of a fuel cell, an
internal combustion engine, and an external combustion engine.
There are also conduit means for conveying condensed water from
said fuel cell to said water reservoir. The power-producing device
includes a selected one of the internal combustion engine and the
external combustion engine and the assembly further includes a
condenser for condensing water from water vapor from said engine,
said condenser being in communication with means for conveying
water from said condenser to said water reservoir.
[0018] In general, in another aspect, the invention includes a
method for generating hydrogen fuel for a power-producing
hydrogen-fueled device, the method includes the steps of: (a)
providing a slurry comprising an organic carrier liquid, a
triglyceride dispersant, and a chemical hydride; (b) mixing said
slurry with water to effect release of hydrogen from the slurry;
(c) removing water vapor from the hydrogen released from the
slurry, to provide dried hydrogen; and (d) conveying the dried
hydrogen to the hydrogen-fueled device for the production of
power.
[0019] Implementations of the invention may include one or more of
the following features. The organic carrier liquid includes a light
mineral oil. The mixing of said slurry and said water is undertaken
with an auger. The water removed from the hydrogen is returned back
to a source of the water for mixing with the slurry. Water
condensed from a fuel cell is returned to a source of the water for
mixing with the slurry.
[0020] In general, in another aspect, the invention features a
regeneration assembly for converting metal oxides and hydroxides to
elemental metals, the assembly comprising: (a) a reactor adapted to
receive the metal hydroxide and carbon, and adapted to retain a
molten carbon-dissolving metal in the reactor; (b) means for
flowing gases comprising the elemental metal in gaseous form,
carbon monoxide, and hydrogen from said reactor; (c) a condenser
adapted to receive the gases flowed from said reactor and adapted
to discharge carbon monoxide and hydrogen from a first outlet and
the elemental metal, metal oxide, and carbon from a second outlet;
(d) a separator adapted to receive the elemental metal, oxide
thereof, and carbon from said condenser and to discharge the
elemental metal in gaseous form; (e) means for flowing the
elemental metal and the carbon dissolving metal in liquid form from
said reactor to said separator; and (f) means for flowing the metal
oxide and the carbon dissolving metal from said separator to said
reactor.
[0021] Implementations of the invention may include one or more of
the following features. A second separator receives the carbon
monoxide and hydrogen from said condenser, said second separator
having a first outlet for discharging carbon monoxide and a second
outlet for discharging hydrogen.
[0022] In general, in another aspect, the invention features a
method for converting metal oxides and metal hydroxides to
elemental metals thereof, the method comprising the steps of: (a)
admitting the metal hydroxide and carbon into a reactor having
molten carbon-dissolving metal therein; (b) flowing gases
comprising the elemental metal in gaseous form, carbon monoxide and
hydrogen from the reactor to a condenser; (c) condensing out the
elemental metal and oxide thereof, and carbon, and flowing same to
a separator; (d) flowing carbon monoxide and hydrogen from the
condenser; (e) flowing the elemental metal and the carbon
dissolving metal from the reactor to the separator; (f) flowing
elemental metal oxide and the carbon dissolving metal from the
separator to the reactor; and (g) flowing the elemental metal from
the separator. In some implementations, an inert gas is flowed into
the reactor.
[0023] Other advantages and features will become apparent from the
following description and from the claims.
DESCRIPTION
[0024] (FIGS. 1, 2, 3, and 6 show hydride containers with water
feed tubes.
[0025] FIG. 4 is a block diagram of a hydrogen generator.
[0026] FIG. 5 is a block diagram of a hydrogen generator and a
metal regenerator.
[0027] FIGS. 7 and 8 are side sectional and top views of a hydrogen
generation canister.)
[0028] The Slurry
[0029] Hydrogen fuel can be stored in a medium that takes the form
of a slurry. The slurry includes a carrier liquid, such as an
organic carrier, a dispersant, such as a triglyceride, for
stabilizing the slurry, and a chemical hydride dispersed in the
carrier liquid at a concentration of at least 40 and typically less
than 75%, except for a dry, non-pumpable slurry described later, in
which the concentration may be higher. The best range can be
determined experimentally. Higher percentages yield higher energy
densities. Lower percentages are less viscous. A good tradeoff for
a slurry of LiH with light mineral oil and a triglyceride
dispersant is about 61% of LiH. Above this percentage, the slurry
became too thick to pump. Higher concentrations may be achievable
by replacing LiH with MgH.sub.2.
[0030] Typical slurries will be in the 50-70% range depending on
the hydride used. LiH slurries will likely be in the 50-61% range.
A thinner slurry, with as little as 40% hydride by weight of the
slurry may be useful for certain applications.
[0031] The slurry may be safely stored and transported and the
hydrogen may be easily extracted for use as a fuel. The slurry is
not highly flammable or combustible and may be safely handled,
stored, and transported. The slurry is stable at normal
environmental temperatures and pressures and, because it is a
liquid, can easily be pumped through conduits. The reaction rate
with the slurry is easily controlled.
[0032] The Carrier Liquid
[0033] The carrier liquid may be an organic carrier liquid, such as
mineral oil or a low molecular weight hydrocarbon, such as an
alkane, preferably pentane or hexane. A preferable mineral oil is a
non-toxic light mineral oil which exhibits a high flash point, in
the range of about 154 degrees C. to about 177 degrees C. and a
viscosity in the range of about 42 Saybolt Universal seconds
(S.U.s.) to about 59 S.U.s.
[0034] The mineral oil is not chemically reactive with metal
hydrides, produces relatively low vapor pressure, and remains
liquid through a temperature range of about -40 to 200 degrees C.
The carrier liquid renders the slurry pumpable and, as a safe
liquid, simple to store or transport. The carrier slows the
reaction rate when water is introduced into the hydride. The use of
a slurry permits easy refueling, as by simply topping off a tank.
Other carriers may work well, including carriers that are without
water bonds and preferably are without OH bonds. Silicone-based
carriers may also work for slurries. Light mineral oils have been
tested successfully at percentages of 37 to 50% by weight of the
slurry.
[0035] The Dispersant
[0036] The dispersant in the slurry may be, for example, a
triglyceride dispersant, which sterically stabilizes the slurry.
The triglyceride dispersant preferably is triglyceride of oleic
acid, or triolein.
[0037] Triolein is not normally considered to have the properties
of a dispersant. Other dispersants that could be used include
Hypermer LP1, a polymeric dispersant. One function of the
dispersant is to attach to the particles of chemical hydride,
increasing the drag of the particle in the carrier fluid thus
helping to prevent settling. The dispersant also helps to keep the
particles from agglomerating. The dispersant promotes the formation
of the slurry and the stabilization of the hydride into the mineral
oil.
[0038] Good dispersant concentrations range from 0.68% to 1.88% in
tests. A particularly good percentage is 0.75%. A broader range of
percentages, from about 0.5 to about 2% of the slurry could be
used. Instead of tryglicerides, the dispersants could be polymeric
dispersants. A combination of triglyceride and polymeric
dispersants may also be used, and may be particularly useful if the
hydride is magnesium hydride.
[0039] Dispersants sometimes have surfactant properties that may
also be useful in the formation of the slurry.
[0040] The Chemical Hydride
[0041] U.S. patent application Ser. No. 09/309,198, filed May 10,
1999, and incorporated by reference in its entirety, discloses
hydrogen-containing material, such as lithium hydride, lithium
aluminum hydride, calcium hydride, sodium hydride, magnesium
hydride, and others, for contact with a reactant, such as water, to
produce hydrogen.
[0042] The chemical hydride in the slurry may be a light metal
hydride, such as lithium hydride, lithium borohydride, lithium
aluminum hydride, magnesium hydride, calcium hydride, sodium
hydride, sodium borohydride, and sodium aluminum hydride, all of
which react with water to produce high purity hydrogen.
[0043] Examples of reactions are:
LiH+H.sub.2O.fwdarw.LiOH+H.sub.2
LiBH.sub.4+4H.sub.2O.fwdarw.LiOH+H.sub.3BO.sub.3+4H.sub.2
MgH.sub.2+2H.sub.2O.fwdarw.Mg(OH).sub.2+2H.sub.2
CaH.sub.2+2H.sub.2O.fwdarw.Ca(OH).sub.2+2H.sub.2
NaBH.sub.4+4H.sub.2O.fwdarw.NaOH+H.sub.3BO.sub.3+4H.sub.2
[0044] The hydrides are finely ground before being mixed with the
other components of the slurry. The particles of the slurry are
between 5 and 10 microns in diameter.
[0045] To make the slurry, we start with a powder form of hydride.
This powder is first combined with a mixture of the mineral oil and
dispersant. Then the mixture is ground in a grinder to further
reduce the size of the particles. The final particles were measured
to be primarily between 5 and 10 microns in diameter.
[0046] The hydrogen generation capability of the above hydrides
when reacted with water is outstanding. For example, the volume of
H.sub.2 produced by complete hydrolysis of 1 kg. (2.2 lb.) of
lithium hydride is 2800 liters (99 ft.sup.3), and by complete
hydrolysis of 1 kg of lithium borohydride is 4100 liters (145
ft.sup.3).
[0047] Characteristics of the Slurry
[0048] In summary, pumpable mixtures (slurries) can usefully have
proportions of components that are 40-75% hydride (but see the
later discussion concerning dry slurries having greater
concentrations), 28-59.5% carrier, and 0.5 to 2% dispersant. A
particularly good mixture is 60% lithium hydride, 0.75%
triglyceride, and 39.25% light mineral oil.
[0049] Slurries of the kind described here (with hydride
concentrations less than about 0.75%) have a liquid-like flow
characteristic and may be used in generation processes that involve
continuous formation and extraction of hydrogen. In such processes,
the slurry can be continuously introduced into a tank, while a
portion of the slurry is continuously drawn off and subjected to
water to release hydrogen. The reaction may be stopped and started
quickly and repeatedly without sacrificing control of the reaction
or safety.
[0050] The oil in the slurry protects the hydride from
unintentional contact with moisture in the air and renders the
hydride pumpable: The slurry, when in the form of a continuing
stream, provides a path for dissipating heat generated from the
hydride/water reaction. That, in conjunction with control of
surface chemistry of the carrier liquid, permits easy control of
the hydride reaction rate. In a continuous process, the hydrogen
production rate is controlled by the injection rate of water and
hydride.
[0051] Because the oil inhibits water access to the hydride, it
controls the rate of reaction, which otherwise could be explosive.
The dispersant maintains the hydride particles in suspension. The
dispersant attaches to the particles and fends off adjacent
particles to prevent agglomeration of the particles. The mineral
oil protects the particles from unintentional reaction with water.
The amount of the dispersant and the size of the hydride particles
control the viscosity of the slurry.
[0052] The slurry burns only if high heat is applied, as by a blow
torch, and maintained. Upon removal of heat, the burning of the
slurry ceases and flames die out.
[0053] Alternative Dry Slurry
[0054] An alternative hydrogen storage medium would be in the form
of a dry slurry comprising 90%-95% hydride. When a drop of water is
injected into a mass of dry slurry in a test tube, a volume of
about 1 cubic centimeter of the hydride around the droplet reacts
with the water, releasing hydrogen. Some of the water flashes to
steam and the steam reacts with hydride as it escapes the tube with
the released hydrogen.
[0055] As shown in FIG. 1, this effect can be exploited by packing
dry hydride slurry 102 into a tube 100 and pulling a needle 104
(which had been placed in the tube when it was packed) out of the
tube while intermittently passing water droplets through the
needle. Each water droplet would then strike fresh hydride until
the needle is fully withdrawn.
[0056] As shown in FIG. 2, an alternate configuration would be to
locate needles 106 strategically throughout (e.g., along the length
of) a large mass of dry hydride or in tubes 108 of hydride (only
one tube is shown in FIG. 2). A valve 110 would then be controlled
to selectively put water droplets into different parts of the mass
or into different parts of the tube to produce hydrogen as
required. This arrangement would have the advantage of requiring
only one moving part, the valve, and would provide the opportunity
to control where the heat is being generated and how the heat of
reaction is dissipated.
[0057] As shown schematically in FIG. 3, another configuration
would use several parallel needles 120 with ends 122 located at
different distances along the length of a tube of hydride 124. As
the water drops are supplied simultaneously to all of the needles
of the set, hydride would be reacted along the tube at several
locations. Then the set of needles would be moved outward 125 along
the centerline 126 of the tube so that the ends 122 are in contact
with new hydride slurry. This configuration reduces the distance
that must be traversed by any one needle. Because reacted hydride
128 will exist downstream of the lower needles, a path of egress
132 must be provided for the generated hydrogen and steam. The path
could be provided by non-reacting porous material 130 positioned
along the wall of the hydride tube far enough away from the
centerline of the tube so that all the water vapor is consumed in
reaction with hydride before the gases reach the porous wall. Then
only hydrogen would be conducted along the porous material to an
outlet end 134.
[0058] The oil in the dry slurry coats the hydride particles and
reduces the rates of reactions with the slurry.
[0059] The Hydrogen Generator
[0060] As shown in FIG. 4, a wet slurry can be used to generate
hydrogen in a hydrogen fuel generation assembly 8 that includes a
reservoir 10 for the slurry, a reservoir 14 for water, and a
hydride reactor 18. The water and slurry are delivered by pumps 16,
12 to the reactor 18, which mixes the slurry and water to release
hydrogen. A tank 26 receives the hydrogen and hydroxide waste from
the reactor, and separates the hydrogen from the hydroxide
byproduct. A heat exchanger 32 receives the hydrogen (and
associated water vapor) carried in conduit 30 from the tank and
condenses the water.
[0061] A gas-liquid separator 40 receives hydrogen and water
carried in line 34 from the heat exchanger, separates the water
from the hydrogen, and dispenses dried hydrogen and water in
discrete streams 44, 42. (The water that is carried in conduit 34
is partly in droplet form, and partly in liquid stream form.) The
water from the separator is conveyed to the water reservoir 14 (or
to water flowing from the reservoir to the reactor) through
conduits 42, 36, and the dried hydrogen is conveyed to a
hydrogen-fueled power-producing device 38, such as a fuel cell.
[0062] In FIG. 4, the hydride reactor 18 includes a tubular member
20 housing a mixing device, such as an auger 22, rotatable in the
housing. Other mixing devices could also be used including
ultrasonic mixers or vibratory mixers.
[0063] The amount of water pumped to the reactor 18 is more than is
needed to complete the release of hydrogen from the slurry. The
excess water is converted to steam and carries heat produced in the
reaction out of the reaction chamber, thus controlling the
temperature of the reaction.
[0064] The tubular member 20 may be fixed to, or otherwise in
communication with an inlet 24 of the tank 26. In tank 26, the
hydroxide solid material falls to the bottom 28 for removal by way
of an outlet 29.
[0065] When the hydrogen-fueled power-providing device is a fuel
cell 38, water condensed from the exhaust of the fuel cell is also
returned to the water reservoir 14, or to the water flowing from
the reservoir to the reactor.
[0066] When the hydrogen-fueled power-providing device 38 is an
internal or external combustion engine, the assembly also includes
a condenser 46 that accepts water vapor from the device 38 through
a conduit 48 and condenses water. The condensed water passes
through conduit 50 into the conduit 38 for return to the water
reservoir 14 (or water flowing from the reservoir into the reactor
18).
[0067] Thus, hydrogen suitable for use with fuel cells or engines,
for example, is generated by providing a slurry including an
organic carrier liquid, such as a light mineral oil, a triglyceride
dispersant, and a chemical hydride, such as lithium hydride, mixing
the slurry with water to release hydrogen from the slurry,
controlling the reaction temperature by vaporization of water,
condensing water from the hydrogen released from the slurry, and
conveying the dried hydrogen to the hydrogen-fueled power-producing
device.
[0068] The slurry may be prepared at centralized plants, where it
is readily pumpable into tank trucks or through pipes to
distribution centers where the slurry can be pumped into tanks of
vehicles powered by hydrogen fuel cells, or into slurry reservoirs
of homes or business and industrial facilities. The hydroxide
byproduct of the hydrogen production reaction may be picked up upon
the next delivery of slurry is made and transported back to a
regeneration plant, where the hydroxide will be separated from the
mineral oil and will be regenerated to hydride, as explained
below.
[0069] Other Techniques for Distributing Water to the Hydride
[0070] As shown in FIG. 6, another method of distributing water to
the hydride in a chamber is through needles placed in hydride tubes
in locations that permit water droplets that pass through needles
to react with enough of the hydride to release more than 90% of the
potential hydrogen. Several needles could be placed along the
length of each tube. Water would be delivered first to the needle
154 that is farthest from the exit of the tube 156. This water
would react with the hydride around it. Some of the water would be
evaporated and would travel through unreacted hydride causing
further reaction along the tube. A valving system 158 would be
incorporated with the tubes of hydride to deliver water to the
needles selectively. A computer control system 160 would record
which needles had already delivered water and would select needles
that had not delivered water for future hydrogen release.
[0071] The system of FIG. 6 overcomes the blockage of water and
hydrogen flow to all portions of hydride by the metal hydroxide
byproduct that is formed during the reaction. By selecting the
sequence of tubes and needles for water injection, water is
delivered only to fresh hydride. The arrangement of FIG. 6 also
allows the heat released from the reaction in one tube to be
dissipated from the tube while another tube in the system is
reacting with water to deliver hydrogen. By causing the reactions
to occur in different tubes, the heat of reaction on one tube can
dissipate to the environment while slurry and water are reacting in
another tube to continue to produce hydrogen. The system may be
designed so that the heat in one tube is dissipated before another
reaction must take place in that tube. This will control the
temperature of the tube and the materials within the tube.
[0072] Alternatively, the needles could be retractable from the
tubes in a manner similar to that shown in FIG. 3.
[0073] Small Scale Implementation
[0074] In a small scale implementation, shown in FIGS. 7 and 8, the
water supply tubes 170 are buried in a bed 172 of chemical-hydride
slurry in such a manner that each supply tube will provide enough
water to react with the chemical hydride near the outlet 174 of the
tube. Water is stored in chambers 176 located around the perimeter
of a canister 180 that holds the lithium hydrid tubes 182. A valve
177 sequentially directs charges of water to each successive region
of chemical hydride. The valving mechanism could be based on inkjet
technology. Water charges would be supplied when the pressure in
the canister drops below a set value. In this manner, the pressure
in the canister will be cycled between a high value of about 200
psi and a low value of about 50 psi. The generated hydrogen exits
the canister through conduit 183 after passing through a carbon
filter 184.
[0075] The hydrogen produced could be consumed by an attached fuel
cell as fast as it is generated and the electricity produced by the
fuel cell may be stored in a battery or capacitor.
[0076] By supplying discrete charges of water sufficient to react
with the chemical hydride within a specified diameter of the
release location, the reaction within the canister 176 can be
controlled so that there is never a surplus of water. As the
chemical hydride reacts with water, its volume increases. This
increased volume occupies the storage volume of the water that is
consumed, to achieve a minimum system volume. Flexible walls 190
enable the water supply chambers and the hydride tubes to change
volume as needed.
[0077] The Hydrogen Regenerator
[0078] The hydroxide byproduct can be processed to regenerate its
elemental metal component. The metal can then re-used in the
hydride fuel generating process by hydrogenating the elemental
metal to produce the hydride fuel.
[0079] As shown in FIG. 5, the hydrogen generation assembly is
similar to the one shown in FIG. 4 and includes a reactor 210 and
inlet tubes 212, 214 which convey slurry and water, respectively,
to the reactor 210. The reactor 210 includes a tubular portion 216
housing an auger 218 for mixing the slurry and water to effect
release of hydrogen gas (H.sub.2) from the slurry. A reactor tank
portion 219 receives the hydrogen gas and solid matter from the
auger 218. The hydrogen gas moves toward a top portion 220 of the
reactor tank portion 219 and is carried by a conduit 222 to a
separator (not shown) for drying the hydrogen. The hydroxide, which
is a wet solid dust 224, falls to a bottom portion 226 of the
reactor tank portion 219, from which it is removed and conveyed by
transport means 223 to a mixer 228. Mixer 228 receives carbon
through a conduit 234 and mixes the carbon with the hydroxide.
[0080] The conduit 234 introduces the carbon, in solid or fluid
form, such as coal in pellet or powder form, biomass, or graphite,
to the mixer 228. The mixed carbon and hydroxide are transported by
transport 229 to a second reactor 230 where there is disposed a
molten pool 232 of carbon dissolving metal, such as iron, nickel,
manganese, and alloys of those metals. The metal, because of its
high heat capacity and thermal conductivity, provides superior heat
transfer characteristics.
[0081] Alternatively, the mixer 228 may be omitted and the carbon
and hydroxide fed directly into the reactor 230.
[0082] The intermixed carbon and hydroxide particles form a layer
238 in the reactor 230, the layer 238 descending into a layer 236,
and then sinking into the pool of molten carbon dissolving metal
232. In layer 236, decomposition of hydroxide into oxide and water
vapor occurs. In layer 232, the reaction between carbon and metal
oxide produces elemental metal and carbon monoxide.
[0083] In one example, the hydroxide is lithium hydroxide (LiOH)
and the carbon-dissolving metal is iron (Fe). The lithium hydroxide
and carbon introduced into the second reactor 230, forms the upper
layer 328 which descends in the reactor 230 and in the area of
layer 236 produces lithuim oxide (Li.sub.2O), water (H.sub.2O),
hydrogen (H.sub.2) and carbon monoxide (CO). The hydrogen (H.sub.2)
and carbon monoxide (CO) rise toward the top of the reactor 230.
Lithium oxide (Li.sub.2O) and carbon (C) sink into the molten pool
of iron (Fe) where they produce lithium metal (2Li), carbon
monoxide (CO) and iron. (Fe).
[0084] In the molten layer 232, lithium gas (Li) is also produced,
which rises to the second reactor upper portion 238. Liquid lithium
(Li) and iron (Fe) pass from the second reactor metal pool 232 to a
separator 240 through a conduit 242. The gaseous lithium (Li) in
the upper portion 238 of the reactor 230, along with hydrogen
(H.sub.2) and carbon monoxide (CO), pass through a conduit 246 to a
condenser 244. Condenser 244 separates out carbon, lithium, and
lithium oxide, which, in solid/liquid form, pass into the separator
240 through a conduit 248. The condenser 244 discharges carbon
monoxide and hydrogen gas through a conduit 250 to another
separator 258, which separates the carbon monoxide from the
hydrogen.
[0085] In the separator 240, the lithium (Li) is evaporated and
released through conduit 252 in vapor form, while the lithium oxide
(Li.sub.2O), in liquid form, is passed through conduit 254 to the
molten metal pool 232 in the second reactor 230. The lithium
discharged by the separator 240 and the hydrogen discharged by the
separator 258 may be recycled for use in the hydride slurry.
[0086] Pumps may be used in the assembly as needed. For example,
the conduits 242, 254 may have magneto-hydrodynamic pumps for
pumping molten metal. The molten metal pool 232 may be maintained
at a temperature of at least 1500.degree. Kelvin, somewhat above
the melting temperature of carbon saturated iron (1430.degree. K).
Alloys can be used to tailor the temperature.
[0087] The operating temperature of the second reactor 230 is
maintained lower than would otherwise be required by continuously
introducing into the molten pool 232 an inert gas, such as argon,
through an inlet 256. The lithium concentration in the lower layer
232 of the reactor 230 is thus maintained at a low level. The
continuous use of the inert gas tilts the thermodynamic equilibrium
in favor of the lithium, allows the operating temperature to be
reduced significantly and achieves higher yields at lower
temperatures. Without the inert gas, the second reactor 230 would
have to be maintained at about 1850.degree. K to obtain the same
yield as 1500.degree. K with the inert gas. The temperature in the
second reactor 230 may also be influenced by using an iron alloy
such as iron-manganese (FeMn).
[0088] When the carbon components are introduced directly into the
reactor 230, they may include natural gas, which is flowable into
the reactor 230 through inlet 256 or a similar inlet.
[0089] In accordance with a further feature of the invention, there
is provided a method for converting metal oxides and hydroxides to
the elemental metals thereof.
[0090] The assembly and method provide for a substantially
closed-loop conversion, without discharge of harmful elements into
the atmosphere.
[0091] Other embodiments are within the scope of the following
claims. For example, elemental metals other than lithium may be
recovered, such as sodium and potassium. Alkaline-earth metals,
such as magnesium and calcium, could also be recovered.
* * * * *