Note: Descriptions are shown in the official language in which they were submitted.
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
STEAM GENERATOR SYSTEM
Field
This patent application generally relates to a steam generator system. More
specifically it
relates to a system for generating steam by passing a current through water.
Even more
specifically it relates to a system for delivering a predetermined amount of
steam, intermittent
amounts of steam or a continuous amount of steam.
Background
In steam use applications the need for rapid generation and replacement of
steam is often
required for speed of the work being performed by the steam. Different work to
be performed by
steam can require a determined amount of steam, intermittent amounts of steam
or a continuous
amount of steam. Food cooking is one such application where it is necessary to
provide a
continuous amount of steam to rapidly cook or reheat bulk food in the
quantities needed for
serving large numbers of people, such as in a restaurant or for banquet
feeding. In other
applications where portions of food are to be reheated for individual servings
such as sandwich
meats, short blasts of steam in small amount, repeated at intervals are
preferable. Where a single
function is to be performed for a specific amount of time a determined amount
of steam is often
preferable.
In steam generation by an electrical resistance element, electrical energy
must first heat
an electrical resistance element then its casement and then the water to be
used to produce steam.
An electrical resistance element is generally enchased in a sheath of metal or
other material
which is heated by the resistance element when the element is submerged in
water to generate
steam. A delay in heating the water to sufficient temperature to generate
steam occurs due to the
conduction of heat through layers of material and then into the water
molecules.
In attempts to speed steam generation, electrical elements are often oversized
and
overpowered in order to quickly heat the sheathing so that the sheathing can
then heat the water,
which generally causes excessive energy use. When steam is required in a
device with electrical
resistance elements, full power is applied to the element, in this way the
surface temperatures of
the element and its sheathing become much hotter than the water and heat
transfer is faster.
When steam is no longer needed, energy is removed from the resistance element,
however heat
1
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
in the resistance element and casement continues to transfer to the water and
is wasted. In this
way more energy is used than would be necessary if a direct application of
energy to heat was
provided in just the amount of energy needed to supply the amount of steam
necessary to
perform the work required.
Other problems are created by heating the element and sheathing to a
temperature much
hotter than the water to be heated. Dissolved solids such as calcium carbonate
and magnesium
are percolated out of the water and these particles adhere to the surface of
the element sheathing,
thus forming a layer of deposits called lime scale on the heat transfer
surface. These lime scale
deposits become another layer of heat transfer and reduce the speed of heat
transfer further. The
lime scale then causes more energy use for the work required. Lime scale is
also a major factor
creating maintenance and service requirements for steam generation devices.
In continuous steaming applications, steam generators having storage for a
quantity of
water are used. The size of the reservoir for water storage is based on the
maximum amount of
steam generation required in a period of time. The generating of steam then
requires heating this
entire mass of stored water to near steam generation temperatures in order to
provide the
required amount of steam as quickly as possible. Heating this entire quantity
of water is required
in continuous steaming applications to offset the amount of time required to
take water to steam
in a continuous supply using electrical resistance elements. Energy is wasted
by heating the
entire supply of stored water. After water in the heated reservoir is heated
to generate steam, new
water is supplied to the water storage cooling the entire amount of water.
When new water is
added the temperature of the entire quantity of water is reduced and must be
reheated to the
desired maintenance temperature, again wasting energy.
Attempts to speed the generation of steam in a steam generator with water
storage have
included the use of a pressurized housing in which the water can be heated and
maintained at a
higher temperature so that its release to steam use will flash the water from
superheated water to
steam. Devices with steam generation and pressurized water are generally
complex, heavy due to
the weight of components and due to the stored supply of water and are prone
to service and
maintenance issues. A great deal of energy is expended to reheat and maintain
the water supply
at a temperature ready to produce steam.
2
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
In an alternate steam generating method serving the need for rapid steam
generation
devices, a nozzle supplies a small amount of water as a spray against a hot
surface where it
flashes to steam. In this way a small quantity of steam is produced almost
instantly and then is
used for the application intended. Additional quantities of water are sprayed
against the hot
surface intermittently to provide additional quantities of steam for the
intended purpose. The hot
surface is heated by an encased electrical element or in some cases water is
sprayed directly on
an electrical element encased in sheathing. This method of steam generation
provides an
intermittent amount of steam but not a continuous amount of steam. In this
solution the amount
of steam that can be created at one time is limited first by the quantity of
water contained in each
spray and then by the surface temperature of the surface on which the water is
sprayed. Repeated
sprays can create additional steam but sprays must be delayed until the heated
surface has had a
chance to recover adequate temperature to flash more water to steam, limiting
the amount of
steam that can be generated. In some cases the electrical element provided to
heat a surface or
provided as a flashing surface is increased in size to allow for faster
recovery in order to flash
more water to steam in a given time, wasting energy.
In instances where the need for steam is often unpredictable, the heated
surface is
maintained in a hot surface condition in order to be ready for steam
production when required,
this also wastes energy. In this solution, the dissolved solids of the water
supply are given up to
the heated surface when the water is flashed to steam. The dissolved solids
form a lime scale
coating on the flashing surface causing it to become less efficient at heat
transfer. This results in
the need for additional energy to heat the surface and additional time to
reach a temperature
capable of generating steam. These conditions result in a reduction in the
amount of steam that
can be generated and the speed at which steam can be generated. The buildup of
lime on the
surface eventually leads to the need for maintenance or repair.
Because of the inherent problems with the related art, there is a need for a
new and
improved steam generator system for rapidly creating steam by a direct
conversion of electrical
energy to heat in the water molecules and in controlled sequences to deliver a
determinant
amount of steam, intermittent amounts of steam or a continuous amount of
steam.
Summary
One aspect of the present patent application is a system for generating steam
from an
3
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
electrolytic solution. The system includes a steam generating tank, a flow
producing device, an
electric current measuring device, and a controller. The steam generating tank
includes a first
electrode and a second electrode. The first electrode and the second electrode
are arranged to
contact the electrolytic solution when the electrolytic solution is provided
in the steam
generating tank. Electrical current flows between the first electrode and the
second electrode
through the electrolytic solution. The electrical current heats the
electrolytic solution to produce
the steam. The controller is connected to the flow producing device to to turn
on and turn off
provision of the electrolytic solution to said steam generating tank based on
the electrical current
measured by the electric current measuring device.
Another aspect of the present patent application is a system for generating
steam from an
electrolytic solution. The system includes a steam generating tank. The steam
generating tank
includes a first electrode and a second electrode. The first electrode and the
second electrode are
arranged to contact the electrolytic solution when the electrolytic solution
is provided to the
steam generating tank and when the first and the second electrodes are
connected to a source of
AC electrical power. Electrical current flows between the first electrode and
the second electrode
through the electrolytic solution. The electrical current heats the
electrolytic solution to produce
the steam. Flow of electrical current automatically stops when all
electrolytic solution in the
steam generating tank has been converted to steam.
Brief Description of Drawings
The foregoing and other aspects and advantages of the invention will be
apparent from
the following detailed description as illustrated in the accompanying
drawings, in which:
FIG. 1 is an block diagram of one embodiment of a steam generator system;
FIG. 2 is a block diagram that includes one embodiment of a control circuit
for
controlling the steam generator system of FIG. 1;
FIG. 3 is a three dimensional view of one embodiment of a steam generating
tank;
FIG. 4 is a cross sectional view of the steam generating tank of FIG. 3;
4
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
FIG. 5 is a three dimensional view of another embodiment of a steam generating
tank;
FIG. 6 is a cross sectional view of the steam generating tank of FIG. 5;
FIG. 7 is a three dimensional view of one embodiment of a filter;
FIG. 8 is a three dimensional exploded view of another embodiment of a steam
generating tank and its electrical and mechanical connectors; and
FIG. 9 is a three dimensional view of one embodiment of a steam generating
system.
Detailed Description
One embodiment of the present patent application provides a system for rapidly
creating
steam. Electrical current passing through an electrolytic solution of water
heats the electrolytic
solution to the boiling point to deliver a pre-determined amount of steam,
intermittent amounts
of steam or a continuous amount of steam. The electrolytic solution has an
ionic content
sufficient for a high current to flow to provide rapid ohmic heating. The
electrolytic solution is
received in a steam generating tank where it contacts electrodes. A control
system directs
production of steam in a continuous, intermittent, or a pre-determined amount.
In one
embodiment a water reservoir supplies the electrolytic solution for conversion
to steam in the
steam generating tank. In one embodiment, a pump is used to flow the
electrolytic solution from
the reservoir to the steam generating tank.
The current flowing between electrodes in the steam generating tank is
controlled by the
combination of ionic content added to the water, the level of the electrolytic
solution in the
steam generating tank, and operation of a phase angle controller and a current
sensor of an
electrical circuit.
In one embodiment, the ionic content of the water is adjusted before use in
steam
generation. In another embodiment tap water with its inherent conductive
impurities is used for
the steam generation.
In one embodiment, energy is provided to operate the steam generating system
only when
5
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
the steam is required by an apparatus that uses the steam. Energy for
maintaining steam or
heated water can be avoided. In one embodiment steam generation is controlled
by the resupply
of a quantity of electrolytic solution to the steam generating tank. One
embodiment of the
present patent application can produce a fixed quantity of steam determined by
a quantity of
electrolytic solution provided to the steam generating tank and in contact
with the electrodes in
the steam generating tank until that quantity is completely converted into
steam. The system can
also be operated to provide a small quantity of steam intermittently. The
system can also be
operated to provide a continuous quantity of steam by continuous supply of
electrolytic solution.
The present applicants found that energy conversion was at a high efficiency.
They also
found that the system consumes energy only when water is present in the steam
generating tank
and that it automatically turns off when all of the electrolytic solution has
been converted to
steam because the circuit is thereby interrupted. They also found that
steaming stops quickly
when current supply to the electrodes was switched off. As no surfaces get
hotter than the
electrolytic solution in the steam generating tank and the steam generated in
the tank, lime scale
is avoided, thus avoiding regular maintenance or repair. In this
configuration, the present
applicants found that precipitating salt and solids are found along with steam
condensate that
flows into a collection pan in the compartment using the steam. In other
configurations salt and
solids can be flushed out of the steam generating tank with a plain water or
chemical rinse.
In one embodiment, the steam is generated for a cooking appliance. One
embodiment is
light weight and requires very few connections for use and can be attached to
a particular
appliance when steam is required. Several of the embodiments are in a steam
ready condition
without the consumption of electricity until steam is called for.
In steam generator system 10 electrolytic solution 11 is received by steam
generating
tank 17 for producing steam in a continuous, intermittent, or a pre-determined
amount, as
determined by control system 16, as shown in FIG. 1. The steam is rapidly
created via direct
conversion of electrical energy to heat in the electrolytic solution that is
to become steam. Steam
generating system 10 also includes reservoir 13, filter 12, pump 14, and check
valve 15.
In one embodiment, pump 14 is replaced with another type of flow controlling
device. In
one such embodiment flow of electrolytic solution 11 into steam generating
tank 17 is by gravity
6
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
feed and the flow controlling device is an electrically controlled valve. In
this embodiment
controller 21 that would otherwise turn pump 14 on and off would instead open
and close the
valve to inject electrolytic solution from reservoir 13 into steam generating
tank 17. While in the
remainder of the description in this patent application the flow controlling
device is called pump
14, it is understood that the gravity feed and valve scheme or another such
scheme may equally
well be used.
In the embodiment of FIG. 1 reservoir 13 holds a supply of electrolytic
solution 11. In an
alternate embodiment, a connection for supply of electrolytic solution 11
could be provided for a
continuous supply in place of or in addition to reservoir 13. Reservoir 13 can
be fabricated of a
blow molded or injection molded plastic or can be of another material suitable
for the storage of
an electrolytic solution of water.
Electrolytic solution 11 is adjusted in ionic content by passing water through
filter 12.
Filter 12 is so constructed as to direct water flow through a series of holes
and through an ionic
material that adds ionic content to the water as it passes through the filter
12. Applicant made
filter 12 by loading table salt into a cheesecloth bag and inserting the bag
into a filter housing.
To remove chlorine and other impurities from the water applicant loaded
charcoal into another
cheesecloth bag and inserted that bag into the filter housing as well. As
water runs thorough
filter 12 toward reservoir 13, the flow of water is controlled by the hole
size in the filter housing.
The hole size is set to allow adequate residence time for the water with the
salt so that the
desired dissolved ionic content is achieved for electrolytic solution 11 that
flows out through the
filter's discharge holes into reservoir 13.
In another embodiment, applicants simply added salt to the reservoir and then
filled the
reservoir with water, thereby achieving sufficient residence time for the salt
to dissolve and
achieving the desired concentration of about a quarter teaspoon of salt per
gallon for the
reservoir which held about 2 gallons of electrolytic solution 11.
By either technique, electrolytic solution 11 is adjusted in ionic content by
the addition of
an amount of sodium chloride in an approximate ratio of approximately 3/4 of a
gram per gallon
of water. Addition of an ionic material to water is described in commonly
assigned US patent
publication 2010/0040352 "Rapid Liquid Heating," incorporated herein by
reference.
7
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
The ionic content may include one or more potable ionic elements, such as
sodium
chloride. A charcoal filtering element can be included to remove chlorine and
other impurities
from the water entering steam generating system 10. The amount of sodium
chloride and the
amount of dissolved solids dissolved in electrolytic solution 11 will
determine the conductivity
of electrolytic solution 11, the current flow in electrolytic solution 11, and
the rate of heating and
steam generation by electrolytic solution 11.
Reservoir 13 is connected to pump 14 which in turn is connected to one way
check valve
connected to steam generating tank 17, as shown in FIG. 1. Pump 14 is
controlled by on and
off signals received from control system 16. The longer control system 16 has
pump 14 turned
10 on the more water is pumped to the interior of steam generating tank 17
and the higher the level
of water in contact with electrodes in steam generating tank 17. Check valve
15 allows flow to
steam generating tank 17 but prevents steam generated in steam generating tank
17 from flowing
back to pump 14. The output of steam generating tank 17 is directed to steam
chamber 19, such
as a cooking appliance, compartment, or other device that uses steam. The
connections between
15 components that permit water and steam flow may include piping, tubing,
or other suitable
structural components. Also illustrated connected to steam generating tank 17
in FIG. 1 are
connection boxes for receiving a positive AC power line and a neutral AC power
line for
connection to electrodes in steam generating tank 17.
FIG. 2 illustrates one embodiment of electrical circuit 20 used with the
embodiment of
FIG. 1. Electrical circuit 20 controls operation of pump 14 and monitors and
controls current
flow between electrodes in steam generating tank 17. In one embodiment,
current is controlled to
avoid exceeding a current load set point. A circuit breaker is also included
which would disrupt
current flow if current exceeds its preset disconnect value. In one
embodiment, current is
maintained relatively high, close to but not exceeding the circuit breaker
preset disconnect value
current limit in order to most quickly generate the desired amount of steam
without interruption.
The amount of dissolved solids and sodium chloride in the water could easily
reach a level
where a current load limit could be achieved and exceeded if other controls
were not in place.
In one embodiment, electrical circuit 20 is connected to plug 26, such as a
120V, 20A
NEMA 5-20P for plugging into a wall outlet. However, it is appreciated that
other power
supplies may be used, such as 208, 220, 240, and 440 volts. As also
illustrated in FIG. 2, current
8
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
sensor 22, such as sold by Digi-key Corporation, South Thief River Falls,
Minnesota, is located
on controller 21, wherein current sensor 22 reads the level of current being
provided to steam
generating tank 17 and is programmed to supply current to pump 14 based on the
current level
programmed into controller 21. Interface to controller 21 allows operator to
put in time for
operation. Start and stop control is also provided. For a 120 volt system, for
example, the
breaker current is 20A and the maximum operating current would be factory set
at 15 amps.
Similarly, for the higher voltage systems a corresponding circuit breaker and
a maximum
operating current are provided.
In one embodiment, when current sensor 22 senses that current flow to
electrodes in
steam generator tank 17 has dropped below a set point for normal operation,
such as 14 amperes,
controller 21 activates pump 14. Pump 14 then supplies electrolytic solution
11 to steam
generating tank 17, which raises the level of electrolytic solution 11 in
steam generating tank 17
which increases the area of submerged electrodes, lowers resistance, and
increases the electrical
current flowing between electrodes in steam generating tank 17. When the
electrical current
flowing across gap 37 between the electrodes rises to a preset level as
determined by current
sensor 22, controller interrupts the power to pump 14, turning off the flow of
electrolytic
solution 11 to steam generating tank 17 and halting the rise in electrical
current.
In this embodiment, since controller 21 is preset so steam generating tank
operates with a
specified level of current flow between electrodes to maximize rate of steam
generation, current
sensor 22 and pump 14 work together to adjust and maintain a level of current
near the
maximum set point, such as 14 amperes for a 20 ampere system. This scheme
allows for
variation in ionic content of the electrolytic solution, such as over
ionization of the water, by
adjusting the water level in contact with the electrodes in steam generating
tank 17 to maintain
the pre-set level of current flow and steam generation. Adjusting level of
electrolytic solution 11
in steam generating tank 17 allows resistance of electrolytic solution 11 to
remain constant even
if resistivity of electrolytic solution 11 varies. When current falls below a
preset level, say 14
amperes, controller 21 turns pump 14 on and when the current goes back up to
the 14 ampere
level controller 21 turns pump 14 off. Thus, level of electrolytic solution 11
in steam generating
tank 17 is adjusted to achieve the preset current even if concentration of
electrolyte varies. In one
embodiment, pump 14 turns on and off several times per minute. In one
embodiment, controller
21 provides that current sensor 22 checks current flow every 3 seconds and if
current is
9
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
measured below the 14 ampere set point, controller 21 turns on pump 14 and
keeps pump 14 on
until current reaches the 14 ampere set point. When pump 14 is running,
current sensor 22
monitors current continuously so controller 21 can turn pump 14 off at any
time. Although in
this example, current sensor checks current every 3 seconds, the interval for
checking current
and the current set point can be set to other values.
As illustrated in FIG. 2, current sensor 22 is also wired into phase angle
controller 24,
such as the SSRMAN-1P Microprocessor Controlled SSR Mounted Phase Angle
Control
Module, available from NuWave Technologies, Inc., Norristown, Pennsylvania.
The supplied
power is one of the potential variables in determining the current flow. Phase
angle controller 24
operates to prevent RMS current from exceeding a preset value. Control over
the conductance of
entering electrolytic solution 11 and control over the level of electrolytic
solution 11 in steam
generating tank 17 allows maintenance of a high working current. However, at
such a peak
current level, small variations can cause an overshoot of a breaker set point
and cause the
breaker to open and an electrical disconnect which would stop production of
steam.
Alternatively, an operator may add far too much electrolyte, increasing
conductivity to the point
that the line voltage would allow current to exceed the breaker set point.
Phase angle controller
24 in conjunction with the current sensor 22 recognizes that RMS current is
approaching the set
point and limits the current by switching off current flow for part of each AC
cycle. Thus, the
high current flow is maintained but not exceeding the set point limit.
Operation of current
sensor 22 and phase angle controller 24 to adjust RMS current, along with
control over ionic
content of electrolytic solution 11 provides a high level of current near
current maximum
without overshooting the maximum current limit.
In one embodiment of use of the steam generating system, by controlling the
quantity and
frequency of flow of electrolytic solution 11 to steam generating tank 17,
steam generating
system 10 can generate a continuous supply of steam. In this embodiment,
controller 21 pumps
electrolytic solution 11 at a frequency sufficient to maintain a constant
quantity of water in steam
generating tank 17 as steam is generated. In another embodiment, electrolytic
solution 11 may be
added at intervals of time, such as every ninety seconds, to provide an
intermittent supply of
steam. In another embodiment, a specific amount of steam is generated by
supplying an amount
of water to steam generating tank 17, such as one tenth liter of electrolytic
solution 11, and
steam is generated until this amount of electrolytic solution 11 is fully
depleted without resupply.
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
When electrolytic solution 11 is supplied to steam generating tank 17, water
will seek a
common level between the electrodes. Current will only flow between positive
and neutral
electrodes when a connection between the electrodes is made by electrolytic
solution 11 being
present. In this way steam generation ceases when either all electrolytic
solution 11 is evaporated
to steam and no additional water is provided or when electrical power to the
electrodes is
switched off or otherwise removed.
In one embodiment, power is not supplied to maintain electrolytic solution 11
hot in
order to save energy. This embodiment takes advantage of the fact that only a
small amount of
electrolytic solution 11 may be needed to supply the desired amount of steam
at any instant, and
converting a small amount of electrolytic solution 11 to steam in steam
generator tank 17 is very
fast. For example, a few milliliters of electrolytic solution may be added to
steam generator tank
17. Applicants found that such a small volume of room temperature water was
converted to
steam by the steam generator system within 3 seconds. Speed is enhanced
because the steam
generator system of the present application provides a very large amount of
electrical power
passing through a relatively small amount of electrolytic solution. For
example, with a 120 volt
supply providing 14 amperes of RMS current, 1680 watts are supplied, which
provides 5040
joules of energy in 3 seconds. This is enough energy to raise the temperature
and boil away 8m1
of water from 20 C in those 3 seconds. As steam generator tank 17 can be
continuously
replenished with electrolytic solution 11, steam generator tank 17 can then
supply steam
continuously with no further delay.
As steam is generated between electrodes of steam generator tank 17, the steam
bubbles
up into a steam chamber in steam generator tank 17 or to an appliance that
uses the steam. In one
embodiment, no steam valve is provided since the supply of steam is determined
by the amount
of electrolytic solution provided to steam generator tank 17 and by operation
of control system
16.
FIGS. 3 and 4 illustrate one embodiment of steam generator tank 30 which
receives
electrolytic solution 48 and outputs steam 49. Steam generator tank 30
includes shell 31
comprised of a metallic material, such as titanium or another conductive and
non-corrosive
material, such as graphite. In one embodiment, shell 31 is cylindrical in
shape and connected to
neutral line 43 of electrical circuit 20. Shell 31 is fitted with first end
cap 32 and second end cap
11
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
33, preferably each constructed of a non-conductive material, such as
polypropylene, to form a
water-tight, sealed interior space. In one embodiment, shell 31 is also the
outside surface of
steam generator tank 30.
In this embodiment, first end cap 32 is fitted with input fitting 38 for
receiving
electrolytic solution 48. First end cap 32 also has output fitting 39 for
outputting steam 49 for
delivery for its purpose, such as heating food. Input fitting 38 and output
fitting 39 may be
fabricated of a tubular, barbed structure which is adapted to receive and
fluidly connect to a
hose, pipe or other transferring medium with a tube clamp or other fitting
device.
In this embodiment, second end cap 33 is also fitted with an electrical
fitting 41 for
receiving positive power line 42 of electrical circuit 20. Positive power line
42 extends within
channel 34 along the bottom surface of second end cap 33 that is not connected
to the fluid filled
interior space. Alternatively, positive power line 42 can extend within an
opening within second
end cap 33. Electrical fitting 41 may include a screw which permits transfer
of the electrical
connection to positive electrode 40 within the interior space of steam
generator tank 30. End cap
33 also includes cover 45, formed of a non-conductive material, such as
polycarbonate, installed
over the electrical connection of electrical fitting 41 and positive power
line 42. Positive
electrode 40 is in electrical connection with electrical fitting 41 and
located within the interior
space of steam generator tank 30. Positive electrode 40 is sealed along a
lower end with
0-shaped, silicone seal ring 46. In one embodiment, positive electrode 40 is
fabricated of a
graphite material. Alternatively, other conductive materials may be used, such
as stainless steel,
titanium. In one embodiment both electrodes 31, 40 were fabricated of a
graphite material. Gap
37 between the outer circumference of positive electrode 40 and the inner
circumference of
conductive shell 31 holds electrolytic solution 48 for current flow there
between.
The interior space of steam generator tank 30 includes a lower space that has
positive
electrode 40, gap 37, and a portion of shell 31, and an upper space which
serves as expansion
chamber 36, as shown in FIG. 4. In one embodiment of operation of steam
generator tank 30,
electrolytic solution 48 is fed to the interior space of steam generator tank
30 in gap 37 between
positive electrode 40 and conductive shell 31. The height of electrolytic
solution 48 in this filled
gap is adjustable and may vary during operation, as described herein above.
With electrolytic
solution 48 in gap 37 and in electrical contact with positive electrode 40 and
conductive shell 31,
12
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
current flows between electrodes 31, 40, creating heat that boils electrolytic
solution 48 to create
steam 49.
The space above positive electrode 40 in the interior space of steam generator
tank 30
serves as expansion chamber 36 for electrolytic solution 48 vaporizing to
steam 49, which due to
the confinement creates pressure which forces steam 49 to exit from outlet 39
and enter chamber
19 or another receptacle where the steam is intended to go. Expansion chamber
36 has a volume
sufficient to provide enough steam 49 to maintain a continuous supply of steam
49 if desired.
Alternatively, an intermittent or a specified amount of steam can be provided.
The variables to steam generation are the size of gap 37 between the
conductive shell 31
and positive conductive electrode 40, the height or level of electrolytic
solution 48 in gap 37, the
conductance and resistance of the electrolytic solution 48 in gap 37, and the
applied electrical
voltage. In one embodiment, adjusting the level of electrolytic solution 48 in
contact with
positive electrode 40 and conductive shell 31 is one method of adjusting and
controlling the
current flow and the rate of steam generation. In another embodiment, a
current sensor is used to
sense the current, and when the current falls below a set point, such as 14
amperes, controller 21
turns pump 14 on, driving additional electrolytic solution to flow into gap 37
of steam generator
tank 17. Electrolytic solution 11 continues to flow until current sensor 22
measures that current
has increased to the set point, 14 amperes. At that point, controller 21 turns
off pump 14. In one
embodiment, once pump 14 turns off no measurement of current is taken by
current sensor until
a designated time, such as 3 seconds, has passed. In this embodiment, pump 14
can at most turn
on every 3 seconds. In one embodiment, gap 37 between positive electrode 40
and conductive
shell 31 is 1/4 inch, the height of positive electrode 40 is about 1/3 of the
height of the interior
space in steam generator tank 30 and the total height of this interior space
is approximately 5
inches. However, it is appreciated that various alternate embodiments, shapes,
and sizes may be
used.
FIGS. 5 and 6 illustrate another embodiment of steam generator tank 50. Steam
generator
tank 50 includes housing 51 constructed of a non-electrically conductive
material, such as
polypropylene. It may be fabricated of any material that will not convey
electrical current or of a
material, such as a metal, that is coated with a non-conductive material, for
example, steel coated
with PTFE. Housing 51 includes sidewalls 52 and bottom 53 to form a
rectangular, box-shape
13
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
and a rectangular interior space. Other shapes may be used. Housing 51 has an
open top that is
closed with steam housing cover 55 and sealed with gasket 56. Steam housing
cover 55 is
secured by fasteners 57 to seal housing 51 shut in a water-tight manner.
Housing 51 includes
inlet tube 65 and steam supply discharge tube 66.
Housing 51 generally includes first electrode 60 and second electrode 61.
Housing 51
may also include third electrode 62. Housing 51 can also include fourth
electrode 63. Electrodes
60-63 are fabricated of a corrosion-resistant electrically conductive
material, such as stainless
steel, titanium or a graphite material. In one embodiment, electrodes 60-63
are evenly-spaced
and are rectangular, plate-shaped. Third electrode 62 and fourth electrode 63
may be electrically
connected to electrodes 60 and 61. In one embodiment, first electrode 60 and
third electrode 62
are connected to one leg (i.e. positive) of power and second electrode 61 and
fourth electrode 63
are connected to the second leg (i.e. negative or neutral) of power of the
power supply, for
example, 120 volts.
The specific shapes and sizes of electrodes can vary to match the size and
shape of steam
housing 51 while configured to allow electrolytic solution to contact all
electrodes 60-63. In one
embodiment notch 64 is provided to allow liquid flow between electrodes 60-63,
wherein the
notch 64 would generally be located along a bottom edge of the electrodes 61,
62. Space
between electrodes may be adjusted to facilitate flow of current through
electrolytic solution 11
in an efficient manner. In this embodiment, electrical current is provided by
power cord and plug
69 similar to other embodiments. Alternately a hard wired connecter may be
used. Electrical
connection box 68 is provided adjacent to housing 51 to receive electrical
wires 67 for reciting
control commands from control system 16 and to provide connection from power
cord and plug
69 to electrodes 60-63.
Filter 70 includes base housing 71 and water filter cap 74 to seal base
housing 71 after
containers 72, 73 of filter material are inserted, as shown in FIG. 7. The
filter material is
packaged in individual replaceable containers 72, 73, such as the cheesecloth
bags of table salt
and charcoal described herein above. One embodiment includes at least one
replaceable
container 72 of ionic material, such as table salt and one replaceable
container 73 of an alternate
filter material, such as charcoal or carbon. Filter cap 74 includes
communication holes 75 that
control the flow of inlet water and outlet electrolytic solution through
filter 70.
14
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
FIG. 8 illustrates another embodiment of steam generator tank 80 and its
connectors that
can be used for providing steam to an appliance requiring steam, such as a
clothing steamer.
Steam generator tank 80 includes housing 81 fabricated of a heat resistant
plastic, such as
polypropylene. In one embodiment, housing 81 is formed of a clear or a semi-
transparent heat
resistant material. Housing 81 can take different shapes, such as the tube
shape of FIG. 8. In one
embodiment, steam generator tank 80 has sealable end caps 82, 85 that attach
by means of
threads on each end of housing 81 and on removable caps 82, 85. Disposed
within housing 81
are first removable electrode 90 and second removable electrode 91. First
removable electrode
90 and second removable electrode 91 are fabricated of a conductive material,
such as graphite
and are positioned to electrolytic solution to contact each electrode 90, 91
equally when the
housing 81 is positioned in an upright position, as shown in FIG. 8.
First end cap 82 includes electrode recesses and communications port 83 for
steam to
exit and for the connection to steam supply line 92. Communications port 83
may have a barb
fitting. In one embodiment, first end cap 82 has an internal 0-shaped ring
gasket to seal against
steam or water leakage. Mounted to second end cap 85 is electrode mount 86
internal to and
electrically separate from second end cap 85. Electrode mount plate 86
includes mount caps 87
for receiving the ends of pencil-shaped electrodes 90, 91 and for providing
electrical contact to
electrodes 90, 91. Second end cap 85 includes a gasket that provides a steam-
and water-tight
seal when end cap 85 is threaded to housing 81. Electrode mount plate 86 and
mount caps 87
stay stationary as second end cap 85 is rotated to complete a screw tight
seal.
As illustrated in FIG. 8, one embodiment of electrical supply line 95 includes
a two-piece
structure. First connector 97 has a male component and a second connector 98 a
female
component to detach steam generating tank 80 from electrical plug 99.
Electrical plug 99
extends from the wall outlet to second connector 98. When second connector 98
is connected to
first connector 97 electrical current can flow to electrodes 90, 91 through
the electrical
connection within the mounting caps 87. Water within housing 81 then boils to
steam which is
transferred to the appliance through supply line 92. In one embodiment, supply
line 92 is
connected to an appliance through quick connect coupling 93. Additional
electrodes may be
included within housing 81. First and second connectors 97, 98 may include a
safety lock for
preventing accidental disengagement. They may also include nonconductive
shielding.
CA 02844489 2014-02-06
WO 2013/025208
PCT/US2011/048007
In one embodiment for its use, no control system is provided for the
embodiment of FIG.
8. An operator may put in table salt and fill housing 81 with tap water to a
fill line at a sink.
Then the operator can plug the steam generating system into a wall outlet and
let it produce
steam and run until all the water is used up. In many places the system would
operate with tap
water and generate steam even without the addition of table salt because of
dissolved solids in
the ordinary tap water.
FIG. 9 illustrates another embodiment of steam generator system 10 of the
present patent
application as it may be sold to consumers for cooking or other activities
requiring constant,
intermittent, or a pre-determined supply of steam.
Reservoir 100 of steam generator system 10 of FIG. 9 is fabricated of a clear,
removable
and washable material, such as plastic, and is removable from control box 101.
Control box 101
includes a steam generator tank, such as steam generator tank 30 shown in
FIGS. 3, 4. Such a
steam generator tank 30 inside control box 101 stands upright and is fed by
reservoir 100.
Control box 101 also includes the circuitry of control system 16 as
illustrated in FIG. 2. Control
box 101 may also include on/off indicator 102 and various other indicators, an
on/off switch, and
a knob for setting time of operation that is connected to controller 21. Steam
generator system 10
also includes condensate catch pan 103 which is removable from under steam
receiving
compartment 104. Steam from steam generating tank steam in control box 101
passes into
receiving compartment 104 and into steam chamber 107 that may receive various
food or
non-food items therein. Steam receiving compartment 104 and steam chamber 107
include
hinged cover 105 with handle 106. In this embodiment, steam chamber 107
includes a plurality
of openings 108 along one or more surfaces allowing steam from steam receiving
compartment
104 to travel through into steam chamber 107. Condensate from the steam drops
down into
condensate catch pan 103.
While the disclosed methods and systems have been shown and described in
connection
with illustrated embodiments, various changes may be made therein without
departing from the
spirit and scope of the invention as defined in the appended claims.
16
