U.S. patent application number 13/346915 was filed with the patent office on 2012-05-03 for multi-cell dual voltage electrolysis apparatus and method of using same.
Invention is credited to Nehemia Davidson.
Application Number | 20120103824 13/346915 |
Document ID | / |
Family ID | 40086897 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120103824 |
Kind Code |
A1 |
Davidson; Nehemia |
May 3, 2012 |
Multi-Cell Dual Voltage Electrolysis Apparatus and Method of Using
Same
Abstract
A method for achieving high output efficiency from an
electrolysis system (100) using a plurality of electrolysis cells
all located within a single electrolysis tank (101) is provided.
Each individual electrolysis cell includes a membrane (105-107), a
plurality of low voltage electrodes comprised of at least a first
and second anode (117/118; 125/126) and at least a first and second
cathode (121/122; 129/130), and a plurality of high voltage
electrodes comprised of at least an anode (119; 127) and a cathode
(123; 131). Within each cell, the high voltage anode is interposed
between the first and second low voltage anodes and the high
voltage cathode is interposed between the first and second low
voltage cathodes. The low voltage applied to the low voltage
electrodes and the high voltage applied to the high voltage
electrodes is pulsed with the pulses occurring simultaneously.
Inventors: |
Davidson; Nehemia;
(Rosh-Haayin, IL) |
Family ID: |
40086897 |
Appl. No.: |
13/346915 |
Filed: |
January 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12151331 |
May 6, 2008 |
|
|
|
13346915 |
|
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Current U.S.
Class: |
205/335 ;
205/334 |
Current CPC
Class: |
Y02E 60/36 20130101;
C25B 15/00 20130101; Y02E 60/366 20130101; C25B 9/00 20130101; C25B
1/04 20130101 |
Class at
Publication: |
205/335 ;
205/334 |
International
Class: |
C25B 15/00 20060101
C25B015/00; C25B 15/08 20060101 C25B015/08; C25B 15/02 20060101
C25B015/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2007 |
CA |
2590487 |
Claims
1. A method of operating a multi-cell electrolysis system
comprising the steps of: applying a low voltage to at least a first
low voltage anode, a second low voltage anode, a first low voltage
cathode and a second low voltage cathode contained within each of a
plurality of electrolysis cells contained within an electrolysis
tank of said electrolysis system, said low voltage applying step
further comprising the step of pulsing said low voltage at a first
frequency and with a first pulse duration; and applying a high
voltage to at least a first high voltage anode and a first high
voltage cathode contained within each of said plurality of
electrolysis cells, said high voltage applying step further
comprising the step of pulsing said high voltage at said first
frequency and with said first pulse duration, wherein said high
voltage pulsing step is performed simultaneously with said low
voltage pulsing step, and wherein said first high voltage anode is
interposed between said first low voltage anode and said second low
voltage anode within a first region of each of said plurality of
electrolysis cells, and wherein said first high voltage cathode is
interposed between said first low voltage cathode and said second
low voltage cathode within a second region of each of said
plurality of electrolysis cells.
2. A method of operating an electrolysis system comprising the
steps of: positioning a plurality of electrolysis cells within an
electrolysis tank, wherein each of said electrolysis cells is
comprised of a membrane dividing each of said electrolysis cells
into a first region and a second region; filling said electrolysis
tank with a liquid; positioning a plurality of low voltage
electrodes within each of said plurality of electrolysis cells,
wherein said plurality of low voltage electrodes is comprised of at
least a first low voltage anode, a second low voltage anode, a
first low voltage cathode and a second low voltage cathode, wherein
said positioning step further comprises the steps of positioning
said first and second low voltage anodes within said first region
of each of said electrolysis cells and positioning said first and
second low voltage cathodes within said second region of each of
said electrolysis cells; positioning a plurality of high voltage
electrodes within each of said plurality of electrolysis cells,
wherein said plurality of high voltage electrodes is comprised of
at least a first high voltage anode and a first high voltage
cathode, wherein said positioning step further comprises the steps
of positioning said first high voltage anode between said first and
second low voltage anodes within said first region of each of said
electrolysis cells and positioning said first high voltage cathode
between said first and second low voltage cathodes within said
second region of each of said electrolysis cells; applying a low
voltage to said plurality of low voltage electrodes, said low
voltage applying step further comprising the step of pulsing said
low voltage at a first frequency and with a first pulse duration;
and applying a high voltage to said plurality of high voltage
electrodes, said high voltage applying step further comprising the
step of pulsing said high voltage at said first frequency and with
said first pulse duration, and wherein said high voltage pulsing
step is performed simultaneously with said low voltage pulsing
step.
3. The method of claim 2, further comprising the step of selecting
said liquid from the group consisting of water, deuterated water,
tritiated water, semiheavy water, heavy oxygen water, water
containing an isotope of hydrogen, or water containing an isotope
of oxygen.
4. The method of claim 2, further comprising the steps of:
monitoring a liquid level within said electrolysis tank; and adding
more of said liquid to said electrolysis tank when said monitored
liquid level falls below a preset value.
5. The method of claim 2, further comprising the step of adding an
electrolyte to said liquid.
6. The method of claim 2, further comprising the steps of:
monitoring pH of said liquid within said electrolysis tank; and
adding electrolyte to said liquid when said monitored pH falls
outside of a preset range.
7. The method of claim 2, further comprising the steps of:
monitoring resistivity of said liquid within said electrolysis
tank; and adding electrolyte to said liquid when said monitored
resistivity falls outside of a preset range.
8. The method of claim 2, further comprising the steps of:
fabricating said plurality of low voltage electrodes from a first
material; fabricating said plurality of high voltage electrodes
from a second material; and selecting said first material and said
second material from the group consisting of steel, nickel, copper,
iron, stainless steel, cobalt, manganese, zinc, titanium, platinum,
palladium, aluminum, lithium, magnesium, boron, carbon, graphite,
carbon-graphite, metal hydrides and alloys of steel, nickel,
copper, iron, stainless steel, cobalt, manganese, zinc, titanium,
platinum, palladium, aluminum, lithium, magnesium, boron, carbon,
graphite, carbon-graphite and metal hydrides.
9. The method of claim 2, further comprising the steps of:
fabricating said first low voltage anode from a first material;
fabricating said second low voltage anode from a second material;
fabricating said first low voltage cathode from a third material;
fabricating said second low voltage cathode from a fourth material;
fabricating said first high voltage anode from a fifth material;
fabricating said first high voltage cathode from a sixth material;
and selecting said first, second, third, fourth, fifth and sixth
materials from the group consisting of steel, nickel, copper, iron,
stainless steel, cobalt, manganese, zinc, titanium, platinum,
palladium, aluminum, lithium, magnesium, boron, carbon, graphite,
carbon-graphite, metal hydrides and alloys of steel, nickel,
copper, iron, stainless steel, cobalt, manganese, zinc, titanium,
platinum, palladium, aluminum, lithium, magnesium, boron, carbon,
graphite, carbon-graphite and metal hydrides.
10. The method of claim 2, further comprising the step of selecting
said first pulse duration to be between 0.01 and 75 percent of a
time period defined by said first frequency.
11. The method of claim 2, further comprising the steps of:
monitoring a rate corresponding to said heat generation of said
electrolysis system; selecting an operating parameter from at least
one of said low voltage, said high voltage, said first frequency,
and said first pulse duration; and optimizing said operating
parameter of said electrolysis system in response to said monitored
heat generation rate.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a divisional of U.S. patent
application Ser. No. 12/151,331, filed 6 May 2008, which, under 35
U.S.C. 119, claims the benefit of the earlier filing date and the
right of priority to Canadian Patent Application Serial No.
2,590,487, filed 30 May 2007, the disclosures of which are hereby
incorporated by reference for any and all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates generally to electrolysis
systems and, more particularly, to a high efficiency electrolysis
system and methods of using same.
BACKGROUND OF THE INVENTION
[0003] Fossil fuels, in particular oil, coal and natural gas,
represent the primary sources of energy in today's world.
Unfortunately in a world of rapidly increasing energy needs,
dependence on any energy source of finite size and limited regional
availability has dire consequences for the world's economy. In
particular, as a country's need for energy increases, so does its
vulnerability to disruption in the supply of that energy.
Additionally, as fossil fuels are the largest single source of
carbon dioxide emissions, a greenhouse gas, continued reliance on
such fuels can be expected to lead to continued global warming.
Accordingly it is imperative that alternative, clean and renewable
energy sources be developed that can replace fossil fuels.
[0004] Hydrogen-based fuel is currently one of the leading
contenders to replace fossil fuel. There are a number of techniques
that can be used to produce hydrogen, although the primary
technique is by steam reforming natural gas. In this process
thermal energy is used to react natural gas with steam, creating
hydrogen and carbon dioxide. This process is well developed, but
due to its reliance on fossil fuels and the release of carbon
dioxide during production, it does not alleviate the need for
fossil fuels nor does it lower the environmental impact of its use
over that of traditional fossil fuels. Other, less developed
hydrogen producing techniques include (i) biomass fermentation in
which methane fermentation of high moisture content biomass creates
fuel gas, a small portion of which is hydrogen; (ii) biological
water splitting in which certain photosynthetic microbes produce
hydrogen from water during their metabolic activities; (iii)
photoelectrochemical processes using either soluble metal complexes
as a catalyst or semiconducting electrodes in a photochemical cell;
(iv) thermochemical water splitting using chemicals such as bromine
or iodine, assisted by heat, to split water molecules; (v)
thermolysis in which concentrated solar energy is used to generate
temperatures high enough to split methane into hydrogen and carbon;
and (vi) electrolysis.
[0005] Electrolysis as a means of producing hydrogen has been known
and used for over 80 years. In general, electrolysis of water uses
two electrodes separated by an ion conducting electrolyte. During
the process hydrogen is produced at the cathode and oxygen is
produced at the anode, the two reaction areas separated by an ion
conducting diaphragm. Electricity is required to drive the process.
An alternative to conventional electrolysis is high temperature
electrolysis, also known as steam electrolysis. This process uses
heat, for example produced by a solar concentrator, as a portion of
the energy required to cause the needed reaction. Although lowering
the electrical consumption of the process is desirable, this
process has proven difficult to implement due to the tendency of
the hydrogen and oxygen to recombine at the technique's high
operating temperatures.
[0006] A high temperature heat source, for example a geothermal
source, can also be used as a replacement for fossil fuel. In such
systems the heat source raises the temperature of water
sufficiently to produce steam, the steam driving a turbine
generator which, in turn, produces electricity. Alternately the
heat source can raise the temperature of a liquid that has a lower
boiling temperature than water, such as isopentane, which can also
be used to drive a turbine generator. Alternately the heat source
can be used as a fossil fuel replacement for non-electrical
applications, such as heating buildings.
[0007] Although a variety of alternatives to fossil fuels in
addition to hydrogen and geothermal sources have been devised, to
date none of them have proven acceptable for a variety of reasons
ranging from cost to environmental impact to availability.
Accordingly, what is needed is a new energy source, or a more
efficient form of a current alternative energy source, that can
effectively replace fossil fuels without requiring an overly
complex distribution system. The present invention provides such a
system and method of use.
SUMMARY OF THE INVENTION
[0008] The present invention provides a method and apparatus for
achieving high output efficiency from an electrolysis system using
a plurality of electrolysis cells all located within a single
electrolysis tank. Each individual electrolysis cell includes a
membrane which separates the portion of the electrolysis tank
containing that electrolysis cell into two regions. Additionally,
each electrolysis cell includes a plurality of low voltage
electrodes and a plurality of high voltage electrodes. The
plurality of low voltage electrodes includes at least a first and
second low voltage anode contained within the first region of the
electrolysis cell and at least a first and second low voltage
cathode contained within the second region of the electrolysis
cell. The plurality of high voltage electrodes includes at least a
first high voltage anode contained within the first region of the
electrolysis cell and interposed between the first and second low
voltage anodes, and a first high voltage cathode contained within
the second region of the electrolysis cell and interposed between
the first and second low voltage cathodes. The low voltage applied
to the low voltage electrodes is pulsed as is the high voltage
applied to the high voltage electrodes, the low voltage pulses and
the high voltage pulses being timed to occur simultaneously.
[0009] Preferably the low and high voltage pulses occur at a
frequency between 50 Hz and 1 MHz, and more preferably at a
frequency of between 100 Hz and 10 kHz. The pulse duration is
preferably between 0.01 and 75 percent of the time period defined
by the frequency, and more preferably between 1 and 50 percent of
the time period defined by the frequency. Preferably the ratio of
the high voltage to the low voltage is at least 5:1, more
preferably within the range of 5:1 to 100:1, still more preferably
within the range of 5:1 to 33:1, and still more preferably within
the range of 5:1 to 20:1. Preferably the low voltage is between 3
and 1500 volts, more preferably between 12 and 750 volts.
Preferably the high voltage is between 50 volts and 50 kilovolts,
more preferably between 100 volts and 5 kilovolts.
[0010] Preferably the liquid within the tank is comprised of one or
more of; water, deuterated water, tritiated water, semiheavy water,
heavy oxygen water, and/or any other water containing an isotope of
either hydrogen or oxygen. Preferably the liquid within the
electrolysis tank includes an electrolyte with a concentration in
the range of 0.05 to 10 percent by weight, more preferably in the
range of 0.05 to 2.0 percent by weight, and still more preferably
in the range of 0.1 to 0.5 percent by weight.
[0011] The electrodes can be fabricated from a variety of
materials, although preferably the material for each electrode is
selected from the group consisting of steel, nickel, copper, iron,
stainless steel, cobalt, manganese, zinc, titanium, platinum,
palladium, aluminum, lithium, magnesium, boron, carbon, graphite,
carbon-graphite, metal hydrides and alloys thereof.
[0012] In at least one embodiment, the electrolysis system is
cooled. Cooling is preferably achieved by thermally coupling at
least a portion of the electrolysis system to a portion of a
conduit containing a heat transfer medium. The conduit can surround
the electrolysis tank, be integrated within the walls of the
electrolysis tank, or be contained within the electrolysis
tank.
[0013] In at least one embodiment, the electrolysis system also
contains a system controller. The system controller can be used to
perform system optimization, either during an initial optimization
period or repeatedly throughout system operation.
[0014] A further understanding of the nature and advantages of the
present invention may be realized by reference to the remaining
portions of the specification and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an illustration of an exemplary embodiment of the
invention utilizing a three cell configuration;
[0016] FIG. 2 is an illustration of an alternate embodiment based
on the configuration shown in FIG. 1 utilizing multiple sets of low
voltage electrodes for each cell;
[0017] FIG. 3 is an illustration of an alternate embodiment based
on the configuration shown in FIG. 1 utilizing multiple sets of
high voltage electrodes for each cell;
[0018] FIG. 4 is an illustration of an alternate embodiment based
on the configuration shown in FIG. 1 utilizing multiple sets of low
voltage electrodes and multiple sets of high voltage electrodes for
each cell;
[0019] FIG. 5 is an illustration of an alternate embodiment
utilizing a cylindrically-shaped tank;
[0020] FIG. 6 is an illustration of an alternate embodiment based
on the configuration shown in FIG. 1 utilizing switching power
supplies;
[0021] FIG. 7 is an illustration of an alternate embodiment based
on the configuration shown in FIG. 1 utilizing switching power
supplies with internal pulse generators and a system
controller;
[0022] FIG. 8 is an illustration of one mode of operation;
[0023] FIG. 9 is an illustration of an alternate mode of operation
that includes initial process optimization steps;
[0024] FIG. 10 is an illustration of an alternate, and preferred,
mode of operation in which the process undergoes continuous
optimization;
[0025] FIG. 11 is an illustration of an alternate embodiment of
FIG. 1 utilizing multiple low voltage supplies and multiple high
voltage supplies; and
[0026] FIG. 12 is an illustration of an alternate embodiment of
FIG. 1 that includes a system controller.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0027] FIG. 1 is an illustration of an exemplary, and preferred,
embodiment of the invention which can be used, for example, as a
heat generator. Electrolysis system 100 includes a tank 101
comprised of a non-conductive material, the size of the tank
depending primarily upon the desired output level for the system,
for example the desired heat production. Although tank 101 is shown
as having a rectangular shape, it will be appreciated that the
invention is not so limited and that tank 101 can utilize other
shapes, for example cylindrical, square, irregularly-shaped, etc.
Tank 101 is substantially filled with liquid 103. In at least one
preferred embodiment, liquid 103 is comprised of water with an
electrolyte, the electrolyte being either an acid electrolyte or a
base electrolyte. Exemplary electrolytes include potassium
hydroxide and sodium hydroxide. The term "water" as used herein
refers to water (H.sub.2O), deuterated water (deuterium oxide or
D.sub.2O), tritiated water (tritium oxide or T.sub.2O), semiheavy
water (HDO), heavy oxygen water (H.sub.2.sup.18O or
H.sub.2.sup.17O) or any other water containing an isotope of either
hydrogen or oxygen, either singly or in any combination thereof
(for example, a combination of H.sub.2O and D.sub.2O).
[0028] A typical electrolysis system used to decompose water into
hydrogen and oxygen gases utilizes relatively high concentrations
of electrolyte. The present invention, however, has been found to
work best with relatively low electrolyte concentrations, thereby
maintaining a relatively high initial water resistivity. Preferably
the water resistivity prior to the addition of an electrolyte is on
the order of 1 to 28 megohms. Preferably the concentration of
electrolyte is in the range of 0.05 percent to 10 percent by
weight, more preferably the concentration of electrolyte is in the
range of 0.05 percent to 2.0 percent by weight, and still more
preferably the concentration of electrolyte is in the range of 0.1
percent to 0.5 percent by weight.
[0029] The electrolysis system of the invention uses two types of
electrodes, one comprised of low voltage electrodes and the other
comprised of high voltage electrodes. The system of the invention
also includes multiple electrolysis cells, an electrolysis cell
defined herein as having at least two low voltage cathodes, at
least two low voltage anodes, at least one high voltage cathode
interposed between the two low voltage cathodes and at least one
high voltage anode interposed between the two low voltage anodes.
Furthermore the cathode electrodes (low and high voltage) and the
anode electrodes (low and high voltage) within each cell are
separated by a membrane, specifically membranes 105-107 in the
illustrated embodiment. Accordingly the embodiment illustrated in
FIG. 1 includes three electrolysis cells. It should be understood
that the invention is not limited to an electrolysis system with a
specific number of cells, rather the number of cells depends
primarily on the desired output level (e.g., heat production) and
the size of the electrolysis tank.
[0030] Membranes 105-107 permit ion/electron exchange between the
two regions of each cell while keeping separate the oxygen and
hydrogen bubbles produced during electrolysis. Maintaining separate
hydrogen and oxygen gas regions is important as a means of
minimizing the risk of explosions due to the inadvertent
recombination of the two gases. Additionally, separating the
regions allows the collection of pure hydrogen gas and pure oxygen
gas. Accordingly similar polarity electrodes are grouped together
with the membranes keeping groups separate. Thus in the exemplary
embodiment shown in FIG. 1, only anodes are positioned between
membrane 105 and the left side of electrolysis tank 101; only
cathodes are positioned between membranes 105 and 106; only anodes
are positioned between membranes 106 and 107; and only cathodes are
positioned between membrane 107 and the right side of electrolysis
tank 101. Exemplary membrane materials include, but are not limited
to, polypropylene, tetrafluoroethylene, asbestos, etc.
[0031] As noted herein, the present system is capable of generating
considerable heat. Accordingly, system components such as the
electrolysis tank (e.g., tank 101) and the membranes (e.g.,
membranes 105-107) that are expected to be subjected to the heat
generated by the system must be fabricated from suitable materials
and designed to indefinitely accommodate the intended operating
temperatures as well as the internal tank pressure. For example, in
at least one preferred embodiment the system is designed to operate
at a temperature of approximately 90.degree. C. at standard
pressure. In an alternate exemplary embodiment, the system is
designed to operate at elevated temperatures (e.g., 100.degree. C.
to 150.degree. C.) and at sufficient pressure to prevent boiling of
liquid 103. In yet another alternate exemplary embodiment, the
system is designed to operate at even higher temperatures (e.g.,
200.degree. C. to 350.degree. C.) and higher pressures (e.g.,
sufficient to prevent boiling). Accordingly, it will be understood
that the choice of materials (e.g., for tank 101 and membranes
105-107) and the design of the system (e.g., tank wall thicknesses,
fittings, etc.) will vary, depending upon the intended system
operational parameters, primarily temperature and pressure.
[0032] Other standard features of the electrolysis tank are gas
outlets for any hydrogen and oxygen gases generated within the
tank. In the exemplary embodiment shown in FIG. 1, the oxygen gas
produced at the anodes will exit tank 101 at gas outlets 108-109
while hydrogen gas produced at the cathodes will exit the tank at
gas outlets 110-111. Replenishment of liquid 103 is preferably
through a separate conduit, for example conduit 113. In at least
one embodiment of the invention, another conduit 115 is used to
remove liquid 103 from the system. Alternately, each cell can
include one or more conduits for liquid 103 replenishment. If
desired, a single conduit can be used for both liquid removal and
replenishment. It will be appreciated that the system can either be
periodically refilled or liquid 103 can be continuously added at a
very slow rate during system operation.
[0033] In the embodiment illustrated in FIG. 1, each cell includes
four low voltage electrodes (i.e., two cathodes and two anodes) and
two high voltage electrodes (i.e., one cathode and one anode). In
the illustrated embodiment, the first cell includes low voltage
anodes 117/118 and interposed high voltage anode 119, and includes
low voltage cathodes 121/122 and high voltage cathode 123. Noting
that adjacent cells preferably co-use sets of electrodes as shown,
the second cell includes low voltage cathodes 121/122 and high
voltage cathode 123, and includes low voltage anodes 125/126 and
interposed high voltage anode 127. The third cell includes low
voltage anodes 125/126 and interposed high voltage anode 127, and
includes low voltage cathodes 129/130 and high voltage cathode
131.
[0034] In FIG. 1, low voltage power source 133 supplies power to
all of the low voltage electrodes and high voltage power source 135
supplies power to all of the high voltage electrodes. As described
and illustrated, voltage source 133 is referred to and labeled as a
`low` voltage source not because of the absolute voltage produced
by the source, but because the output of voltage source 133 is
maintained at a lower output voltage than the output of voltage
source 135.
[0035] Preferably and as shown, the faces of the individual
electrodes are parallel to one another. It should be understood,
however, that the faces of the electrodes do not have to be
parallel to one another.
[0036] In a preferred embodiment, all of the electrodes are
comprised of titanium. In another preferred embodiment, all of the
electrodes are comprised of stainless steel. It should be
appreciated, however, that other materials can be used and that the
same material does not have to be used for both the low voltage and
the high voltage electrodes, nor does the same material have to be
used for both the low voltage anodes and the low voltage cathodes,
nor does the same material have to be used for both the high
voltage anodes and the high voltage cathodes. In addition to
titanium and stainless steel, other exemplary materials that can be
used for the low voltage electrodes and the high voltage electrodes
include, but are not limited to, copper, iron, stainless steel,
cobalt, manganese, zinc, nickel, platinum, palladium, aluminum,
lithium, magnesium, boron, carbon, graphite, carbon-graphite, metal
hydrides and alloys of these materials. As used in the present
specification, a metal hydride refers to any compound of a metal
and hydrogen or an isotope of hydrogen (e.g., deuterium,
tritium).
[0037] Preferably the surface area of each of the faces of the low
voltage electrodes (i.e., electrodes 117, 118, 121, 122, 125, 126,
129 and 130 in FIG. 1) is a large percentage of the cross-sectional
area of tank 101, typically on the order of at least 40 percent of
the cross-sectional area of tank 101, and often between
approximately 70 percent and 90 percent of the cross-sectional area
of tank 101. The high voltage electrodes may be larger, smaller or
the same size as the low voltage electrodes. Although the
separation distance between electrodes is dependent upon a variety
of factors (e.g., tank size, voltage/current, etc.), in at least
one preferred embodiment the separation between the closest low
voltage electrodes positioned on either side of a membrane (e.g.,
in FIG. 1 electrodes 118/121, electrodes 122/125 and electrodes
126/129) is between 0.2 millimeters and 15 centimeters.
[0038] Preferably the ratio of the high voltage to the low voltage
applied to the high voltage and low voltage electrodes,
respectively, is at least 5:1, more preferably the ratio is between
5:1 and 100:1, still more preferably the ratio is between 5:1 and
33:1, and even still more preferably the ratio is between 5:1 and
20:1. Preferably the high voltage generated by source 135 is within
the range of 50 volts to 50 kilovolts, and more preferably within
the range of 100 volts to 5 kilovolts. Preferably the low voltage
generated by source 133 is within the range of 3 volts to 1500
volts, and more preferably within the range of 12 volts to 750
volts.
[0039] Rather than continually apply voltage to the electrodes,
sources 133 and 135 are pulsed, preferably at a frequency between
50 Hz and 1 MHz, and more preferably at a frequency of between 100
Hz and 10 kHz. The pulse width (i.e., pulse duration) is preferably
between 0.01 and 75 percent of the time period defined by the
frequency, and more preferably between 1 and 50 percent of the time
period defined by the frequency. Thus, for example, for a frequency
of 150 Hz, the pulse duration is preferably in the range of 0.67
microseconds to 5 milliseconds, and more preferably in the range of
66.7 microseconds to 3.3 milliseconds. Alternately, for example,
for a frequency of 1 kHz, the pulse duration is preferably in the
range of 0.1 microseconds to 0.75 milliseconds, and more preferably
in the range of 10 microseconds to 0.5 milliseconds. Additionally,
the voltage pulses are applied simultaneously to the high voltage
and low voltage electrodes via sources 135 and 133, respectively.
In other words, in the embodiment illustrated in FIG. 1, the
voltage pulses applied to high voltage electrodes 119/123/127/131
coincide with the pulses applied to low voltage electrodes
117/118/121/122/125/126/129/130. Although voltage sources 133 and
135 can include internal means for pulsing the respective outputs
from each source, preferably an external pulse generator 137
controls a pair of switches, i.e., a low voltage switch 139 and a
high voltage switch 141 which, in turn, control the output of
voltage sources 133 and 135 as shown, and as described above. Other
means for pulsing the voltage sources are clearly envisioned, for
example using switching power supplies coupled to an external pulse
generator or using switching power supplies with internal pulse
generators. If multiple pulse generators are used, for example one
pulse generator coupled to the low voltage source and a second
pulse generator coupled to the high voltage source, preferably
means such as a system controller are used to insure that the
pulses generated by the individual pulse generators are
simultaneous.
[0040] As previously noted, the electrolysis process of the
invention generates considerable heat. To withdraw that heat so
that it can be used, and to prevent the liquid within the tank from
becoming too hot and boiling at a given temperature, and to prevent
possible damage to those system components that may be susceptible
to damage, in the preferred embodiments of the invention the system
includes means to actively cool the system to within an acceptable
temperature range. For example, in at least one preferred
embodiment the cooling system does not allow the temperature to
exceed 90.degree. C. Although it will be appreciated that the
invention is not limited to a specific type of cooling system or a
specific implementation of the cooling system, in at least one
embodiment the electrolysis tank is surrounded by a coolant conduit
143, portions of which are shown in FIGS. 1-7, 11 and 12. Within
coolant conduit 143 is a heat transfer medium, for example water.
Coolant conduit 143 can either surround a portion of the
electrolysis tank as shown, or be contained within the electrolysis
tank, or be integrated within the walls of the electrolysis tank.
The coolant pump and heat withdrawal system is not shown in the
figures as cooling systems are well known by those of skill in the
art.
[0041] As will be appreciated by those of skill in the art, there
are numerous minor variations of the system described herein and
shown in FIG. 1 that will function in substantially the same manner
as the disclosed system. As previously noted, alternate
configurations can utilize fewer or greater numbers of cells,
differently sized/shaped tanks, different electrolytic solutions,
and a variety of different electrode configurations and materials.
Additionally the system can utilize a range of input powers,
frequencies and pulse widths (i.e., pulse duration). In general,
the exact configuration depends upon the desired output level as
well as available space and power. FIGS. 2-5 illustrate a few
alternate configurations, including the use of multiple sets of low
voltage electrodes for each cell (e.g., FIG. 2), multiple sets of
high voltage electrodes for each cell (e.g., FIG. 3), multiple sets
of low voltage and high voltage electrodes for each cell (e.g.,
FIG. 4), and a horizontal cylindrical tank (e.g., FIG. 5).
[0042] FIG. 2 illustrates an alternate embodiment of the system
shown in FIG. 1, the alternate configuration replacing low voltage
electrode 117 with three low voltage electrodes 201-203, replacing
low voltage electrode 118 with three low voltage electrodes
205-207, replacing low voltage electrode 121 with three low voltage
electrodes 209-211, replacing low voltage electrode 122 with three
low voltage electrodes 213-215, replacing low voltage electrode 125
with three low voltage electrodes 217-219, replacing low voltage
electrode 126 with three low voltage electrodes 221-223, replacing
low voltage electrode 129 with three low voltage electrodes
225-227, and replacing low voltage electrode 130 with three low
voltage electrodes 229-231.
[0043] FIG. 3 illustrates an alternate embodiment of the system
shown in FIG. 1, the alternate configuration replacing high voltage
electrode 119 with two high voltage electrodes 301-302, replacing
high voltage electrode 123 with two high voltage electrodes
303-304, replacing high voltage electrode 127 with two high voltage
electrodes 305-306, and replacing high voltage electrode 131 with
two high voltage electrodes 307-308.
[0044] FIG. 4 illustrates an alternate embodiment of the system
shown in FIG. 1, the alternate embodiment utilizing the low voltage
configuration shown in FIG. 2 and the high voltage configuration
shown in FIG. 3.
[0045] FIG. 5 illustrates an alternate embodiment of the system
shown in FIG. 1, the alternate configuration replacing tank 101
with a horizontally configured cylindrical tank 501, replacing
membrane 105 with an appropriately shaped membrane 503, replacing
membrane 106 with an appropriately shaped membrane 504, replacing
membrane 107 with an appropriately shaped membrane 505, replacing
low voltage electrode 117 with disc-shaped low voltage electrode
507, replacing low voltage electrode 118 with disc-shaped low
voltage electrode 508, replacing high voltage electrode 119 with
disc-shaped high voltage electrode 509, replacing low voltage
electrode 121 with disc-shaped low voltage electrode 511, replacing
low voltage electrode 122 with disc-shaped low voltage electrode
512, replacing high voltage electrode 123 with disc-shaped high
voltage electrode 513, replacing low voltage electrode 125 with
disc-shaped low voltage electrode 515, replacing low voltage
electrode 126 with disc-shaped low voltage electrode 516, replacing
high voltage electrode 127 with disc-shaped high voltage electrode
517, replacing low voltage electrode 129 with disc-shaped low
voltage electrode 519, replacing low voltage electrode 130 with
disc-shaped low voltage electrode 520, and replacing high voltage
electrode 131 with disc-shaped high voltage electrode 521.
[0046] It will be appreciated that the supply electronics (i.e.,
low/high voltage supplies, low/high voltage switches, pulse
generator) shown in FIGS. 1-5 represent only one exemplary
configuration and that other configurations can be used to supply
the requisite pulsed and timed power to the low voltage and high
voltage electrodes within the cells of the electrolysis system of
the invention. FIGS. 6 and 7 illustrate two additional alternate,
and exemplary, configurations. Specifically, FIG. 6 illustrates a
system similar to that shown in FIG. 1, except that low voltage
supply 133 and low voltage switch 139 are combined into a single
low voltage switching power supply 601. Similarly high voltage
supply 135 and high voltage switch 141 are combined into a single
high voltage switching power supply 603. The embodiment illustrated
in FIG. 7 combines the pulse generation within the power supplies,
i.e., low voltage supply 701 and high voltage supply 703, and then
uses a system controller 705 to coordinate the low voltage pulses
and the high voltage pulses produced by the two systems.
[0047] It should be understood that the electrolysis system of the
present invention can be operated in a number of modes, the primary
differences between modes being the degree of process optimization
used during operation. For example, FIG. 8 illustrates one method
of operation requiring minimal optimization. As illustrated,
initially the electrolysis tank, e.g., tank 101, is filled with
water (step 801). Preferably the level of water in the tank at
least covers the top of the electrodes. The electrolyte can either
be mixed into the water prior to filling the tank or after the tank
is filled. The frequency of the pulse generator is then set (step
803) as well as the pulse duration (step 805). The initial voltage
settings for the low voltage power supply and the high voltage
power supply are also set (step 807). It will be appreciated that
the order of set-up is clearly not critical to the electrolysis
process. Typically, prior to the initiation of electrolysis, the
temperature of the water is at room temperature.
[0048] Once set-up is complete, electrolysis is initiated (step
809). During the electrolysis process (step 811), and as previously
noted, the water is heated by the process itself. Eventually, when
operation is no longer desirable, the electrolysis process is
suspended (step 813). If desired, prior to further operation the
tank can be drained (step 815) and refilled (step 817). Prior to
refilling the tank, a series of optional steps can be performed.
For example, the tank can be washed out (optional step 819) and the
electrodes can be cleaned, for example to remove oxides, by washing
the electrodes with diluted acids (optional step 821). Spent, or
used up, electrodes can also be replaced prior to refilling
(optional step 823). After cleaning the system and/or replacing
electrodes as deemed necessary, and refilling the system, the
system is ready to reinitiate the electrolysis process.
[0049] The above sequence of processing steps works best once the
operational parameters have been optimized for a specific system
configuration since the system configuration will impact the heat
generation efficiency of the process. Exemplary system
configuration parameters that affect the optimal electrolysis
settings include tank size, quantity of water, type and/or quality
of water, electrolyte composition, electrolyte concentration,
electrode size, electrode composition, electrode shape, electrode
configuration, electrode separation, cell number, cell separation,
initial water temperature, low voltage setting, high voltage
setting, pulse frequency and pulse duration.
[0050] FIG. 9 illustrates an alternate procedure, one in which the
process undergoes optimization. Initially the tank is filled (step
901) and initial settings for pulse frequency (step 903), pulse
duration (step 905), high voltage supply output (step 907) and low
voltage supply output (step 909) are made. Typically the initial
settings are based on previous settings that have been optimized
for a similarly configured system. For example, assuming that the
new configuration was the same as a previous configuration except
for the composition of the electrodes, a reasonable initial set-up
would be the optimized set-up from the previous configuration.
[0051] After the initial set-up is completed, electrolysis is
initiated (step 911) and system output is monitored (step 913), for
example absolute temperature or the rate of temperature increase.
Although system optimization can begin immediately, preferably the
system is allowed to run for an initial period of time (step 915)
prior to optimization. The initial period of operation can be based
on achieving a predetermined output, for example a specific level
of temperature increase, or achieving a steady state output (e.g.,
steady state temperature). Alternately the initial period of time
can simply be a predetermined time period, for example 6 hours.
[0052] After the initial time period is exceeded, the system output
(e.g., temperature rate increase, steady state temperature, etc.)
is monitored (step 917) while optimizing one or more of the
operational parameters. Although the order of parameter
optimization is not critical, in at least one preferred embodiment
the first parameter to be optimized is pulse duration (step 919).
Then the pulse frequency is optimized (step 920), followed by
optimization of the low voltage (step 921) and the high voltage
(step 922). In this embodiment after optimization is complete the
electrolysis process is allowed to continue (step 923) without
further optimization until the process is halted, step 925. In
another, and preferred, alternative approach illustrated in FIG.
10, one or more of optimization steps 919-922 are performed
continuously throughout the electrolysis process until electrolysis
is suspended.
[0053] Note that the optimization processes described relative to
FIGS. 9 and 10 assume that (i) the cells physical geometry is fixed
and (ii) there is no control over the low and/or high voltage
applied to individual cell electrodes. If the system does include
means for adjusting the physical geometry of the individual cells
during electrolysis, for example the spacing between the electrodes
within the cells or the cell-to-cell spacing, these parameters can
also be altered to further optimize the electrolysis process during
system operation. The system can also be configured to provide
additional control over the low and/or high voltage applied to the
cells. For example, the system shown in FIG. 11 uses a pair of low
voltage power supplies 1101/1102 and associated low voltage
switches 1103/1104, and a pair of high voltage power supplies
1105/1106 and associated high voltage switches 1107/1108. Systems
such as these, although more complex, provide further control and
therefore potentially greater optimization.
[0054] The optimization process described relative to FIGS. 9 and
10 can be performed manually. In the preferred embodiment, however,
the system or portions of the system are controlled via a system
controller such as controller 1201 shown in an alternate embodiment
of the configuration illustrated in FIG. 1 (i.e., FIG. 12).
Assuming that controller 1201 is used to control and optimize the
pulse frequency, pulse duration, high voltage and low voltage,
system controller 1201 is coupled to the pulse generator and the
voltage supplies as shown. If the system controller is only used to
control and optimize a subset of these parameters, the system
controller is coupled accordingly (i.e., coupled to the pulse
generator to control pulse frequency and duration; coupled to the
high voltage source to control the high voltage; coupled to the low
voltage source to control the low voltage). In order to allow
optimization automation, system controller 1201 is also coupled to
a system monitor, for example one or more temperature monitors
(e.g., monitor 1203). In at least one preferred embodiment system
controller 1201 is also coupled to a monitor 1205, monitor 1205
providing either the pH or the resistivity of liquid 103 within
electrolysis tank 101, thereby providing means for determining when
additional electrolyte needs to be added. In at least one preferred
embodiment system controller 1201 is also coupled to a liquid level
monitor 1207, thereby providing means for determining when
additional water needs to be added to the electrolysis tank.
Preferably system controller 1201 is also coupled to one or more
flow valves 1209 which allow water, electrolyte, or a combination
of water and electrolyte to be automatically added to the
electrolysis system in response to pH/resistivity data provided by
monitor 1205 (i.e., when the monitored pH/resistivity falls outside
of a preset range) and/or liquid level data provided by monitor
1207 (i.e., when the monitored liquid level falls below a preset
value).
[0055] As will be understood by those familiar with the art, the
present invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof.
Accordingly, the disclosures and descriptions herein are intended
to be illustrative, but not limiting, of the scope of the invention
which is set forth in the following claims.
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