Note: Descriptions are shown in the official language in which they were submitted.
CA 02378940 2002-O1-09
WO 01106051 PCTIUSOO/i9206
IPE~S 16 A ( l r 2001
but are still classified as volatile organic compounds (V(~C's). As such, such
compounds are
regulated and permitted by most air districts.
The dry cleaning industry has long depended on petroleum-based solvents and
the well-known
chlorinated hydrocarbons, perchloroethylene, for use in the cleaning of
fabrics and articles of
clothing. Since the 1940's, PERC was praised as being a synthetic compound
that is non-
flammable and has great degreasing and cleaning qualities ideal for the dry
cleaning industry.
Beginning in the 1970's, PERC was found to cause liver cancer in animals. This
was an
alarming discovery, as dry cleaning waste was placed in landfills and
dumpsters at that time,
from which it leached into soil and ground water.
Environmental Protection Agency regulations gradually were tightened,
culminating in a law that
took effect in 1996 that required all dry cleaners to have "dry to dry"
cycles, meaning that fabrics
and articles of clothing go into the machine dry and come out dry. These
required "closed loop"
systems that can recapture almost all PERC, liquid or vapor. The process
"cycle" involves
placing fabrics or articles of clothing into a specially designed washing
machine that can hold 15
1 S to 150 pounds of fabrics or articles of clothing that are visible through
a circular window. Prior
to being placed into the machine, the fabrics or articles of clothing are
checked and treated by
local hand spotting for stains. If the fabric is unusual or known to be
troublesome, the label is
checked to verify that the manufacturer has deemed the item safe for dry
cleaning. If not, the
stain may be permanent. If the stain is grease related, water won't help, but
solvent will as it
solubilizes grease. In fact, the principal reason for dry cleaning certain
clothes (which should not
be washed in a regular washing machine) is to remove the build up of body oils
(known as fatty
acids) because they too oxidize and produce rancid nasty smells.
The grease and fatty acids which build up in the solvent are removed by
filtration and by
distillation of the solvent. In other words, the dirty solvent is boiled and
all vapors are condensed
through a condensation coil back to a liquid. The remaining NVR (non volatile
residue) is later
removed and disposed of according to regulations. The liquid recovered is
comprised of both
solvent and water and the liquid is then passed through a separator in order
to separate the two
non-miscible liquids. The water may originate from the natural humidity of the
ambient air
exposed to the textiles prior to cleaning. Another source of moisture may be
materials used
during pre-spotting.
2
A!~~~ND~~ ~i~~~T
CA 02378940 2002-O1-09
WO 01/06051 ~ P~~ ~3~2~ ~ ~ ~ /
Before textiles are removed from the machine, the washer becomes a
drier.~H,o,~t~a/i/r~/is blowbn
through the compartment but, instead of being vented outside, the air stream
goes through a
condenser that condenses the vapors to liquid. The water must then be
separated from the solvent
and the solvent returned for reuse.
If the water is not separated from the solvent, the water will carry over into
an associated storage
tank and due to its density will settle on the bottom of the tank. If the
level of water is sufficient it
will be picked up by the pump system and may be pumped onto the articles being
cleaned,
which would result in damaging the articles.
If the water sits on the base tank for a sufficient amount of time, bacteria
will begin to grow
which will result in a very bad odor that will transfer to the articles being
cleaned. The
hydrocarbon solvent is a feedstock for bacteria and may quickly contribute to
the growth of
bacteria. The silicone-based solvent is not a feedstock for bacteria but the
interface level
between the lighter density solvent and the more dense water causes an
interface level between
the water and solvent. The polar solvent soluble contaminants in this
interface level may include
fatty acids, food, perspiration, and general body odor. The extended settling
can quickly result in
the growth of bacteria and the end result of odor.
It is therefore very critical for professional dry cleaning to control the
presence of water in such a
way as to not damage the articles being cleaned or cause odors that would
result in customer
dissatisfaction.
It should be noted that many organic solvents vary in their degree of
hygroscopicity. Organic
solvents in general, which are not water-soluble, have the ability to adsorb
moisture from their
environment; hence they are hygroscopic. In the case of the cyclic and linear
silicone solvents,
they exhibit the property of adsorbing water (their saturation
points,are,around 200 parts per
million). The rate at which they adsorb water is increased when the solvents
are heated in the
presence of moisture. In a dry cleaning application, where garments are
immersed in the silicone
solvent during the washing process and later centrifuged, any remaining
solvent in the garments
is removed through a tumbling and heating process. The heat causes the solvent
and any
moisture to evaporate. The solventlmoisture combination is transported to a
cooling coil
condenser at which point the resulting liquid solvent/moisture combination may
be of a milky
white appearance which is known as a colloidal emulsion or lyophobic colloid.
This milky white
AMENDED SHE
CA 02378940 2002-O1-09
WO 01/06051 PCT/US00/19206
liquid is the silicone solvent coexisting with adsorbed molecular water. Over
considerable time,
the adsorbed water is gradually and slowly released by the solvent and the two
separate given
their densities and gravity. The adsorption of the water molecules on the
solvent molecules can
be attributed to weak van der Waals forces holding the molecules together
temporarily.
Any two molecules attract each other and the force between them, in general
terms, is called van
der Waals forces. They arise from electrostatic forces between various charges
in these two
molecules (i.e., the constituent electrons and nuclear charges).
4
SUBSTITUTE SHEET (RULE 26)
CA 02378940 2002-O1-09
WO 01/06051 PCT/US001~9206
~IU~ 16 AUG 2~
SUMMARY OF THE INVENTION
It is the purpose of this invention to rapidly and effectively break-up of the
forces binding
molecules of the water and dry cleaning solvent, thus allowing the solvent and
the water
molecules to separate quickly. The process of stripping water from hygroscopic
solvents can be
greatly affected by the chemical nature and design of the micro-cellular
stripping filter.
The process of stripping water from hygroscopic solvents can be greatly
affected by the chemical
nature and design of the micro-cellular porous structure. This is true because
as the
water/solvent liquid mixture is forced through the tiny orifices of the porous
structure, the forces
which cause the water molecules to adhere to the solvent molecules are
reduced, thereby
allowing the molecules to separate.
Urea-formaldehyde foam with a cell structure under 10 microns is the preferred
material for
construction of the porous structure. As the solvent/water liquid is forced
through this rigid yet
porous medium, the solvent and the water are immediately separated in part due
to the difference
in their densities and also due to the reduction of the adsorption forces
(i.e., van der Waals
forces). Other factors that also play part in the separation include
capillarity, surface tensions, and
even the difference of attractive forces between water molecules and foam
molecules verses
silicone molecules and foam molecules. These factors along with flow rate
determine the rate of
separation.
Though rigid materials are preferred due to their ability to withstand greater
pressure
differences, it should be noted that certain flexible materials, such as open-
cellular polyurethane
foams, and phenyl formaldehyde polymers exhibit a similar ability to separate
the solvent and
the water and may be used to construct the porous structure. The cell size,
the density of the
foam, and the pressure at which the solvent/water liquid passes through the
medium determines
the optimum degree of water coalescing (stripping) from the solvent. As an
example, 3-inch 30
diameter rigid foam with a cell size of under 10 microns effectively allows
the water stripping
to occur successfully at a flow rate of over 3 GPM.
It should also be noted that varying materials that may be used as the porous
structure will have
differing degrees of hydrophilicity (ability to attract water). If the micro-
cellular structure has a
S
A~IEN~~~ ~H~ET
CA 02378940 2002-O1-09
WO 01106051 S00119 0
~US ~ ~ AUG 20C
higher degree of hydrophilicity, the effectiveness and the speed of the water
stripping process is
more efficient.
The hydrated silicone solvent, or colloids, also classified as lyophilic
colloid are produced when
immiscible liquids are cooled together during the condensation of vapors both
during drying and
during the distillation process. The proper separation of water from solvent
is influenced by the
proper selection of and implementation of a coalescing or stripping medium.
The medium selected acts primarily as a coalescence of tiny water droplets.
Coalescence is an
indication of destabilization of the colloidal emulsion. The most important
factors in
destabilizing a colloidal emulsion are: ( 1 ) upsetting double layers of
electrical charges
surrounding dispersed droplets in lyophobic colloids so that the "zeta
potential" disappears or (2)
destroying the solvated layer or film that surrounds dispersed droplets in
lyophilic colloids. The
droplets coagulte and the system loses its stability only when both the
stabilizing double layer of
charges and the solvated atmosphere surrounding the droplets are removed.
The "porous structure" media can also be causing coalescence by removing ions
from a double
layer and/or removing a solvated film. Various extended-surface media (as
identified later, but
not limited to) have a significant valence or other amactive forces left over
at their extreme
surfaces that can attract other materials, a phenomenon which is called
adsorption. The
adsorption of ions and surfactants by the "porous structure" media are
reasonable methods by
which the media can fimction and thereby bring about coalescence. Thus, the
selection of the
"porous structure" to be used as the coalescing or stripping medium is based
upon its ability to in
the end separate the siloxane solvent from the water.
The present invention includes a system and method for separating water from a
silicone-based
solvent, such as siloxane, in a dry cleaning application. According to the
invention, an inlet is
capable of receiving a mixture of silicone-based siloxane dry cleaning fluid
and water from a
condenser of a dry cleaning apparatus. A chamber is coupled to the inlet for
receiving the mixture
from the inlet. A porous structure is positioned in the chamber for separating
the dry cleaning
fluid and the water. The dry cleaning fluid passes through pores in the porous
structure. An
outlet is coupled to the chamber to remove the dry cleaning fluid from the
chamber in the
substantial absence of the water.
6
AMENDED SKEET
CA 02378940 2002-O1-09
WO 01/06051 PCT/US00/19206
In one aspect of the present invention, the cell size of the porous structure
is under 10 microns.
The porous structure can be constructed of urea-formaldehyde foam. Ideally,
the cell size of the
urea-formaldehyde foam is under 5 microns. Alternatively, the porous structure
can be
constructed of a polyurethane foam, ideally with a cell size of under 5
microns but rnay exceed
microns. In another aspect of the present invention, the porous structure is
hydrophilic.
7
SUBSTITUTE SHEET (RULE 26)
CA 02378940 2002-O1-09
W001706051 ~~~~~~~1~~ ~~~
Alternatively the porous structure can be constructed of a phenol formaldehyde
polymer foam,
ideally with a cell size of under 10 microns.
In one aspect of the present invention the use of fractional distillation may
allow for the
elimination of water from solvent based on density and re-circulation. Low-end
boilers such as
water can be distilled prior to the distillation of silicone solvent.
The ideal distillation of silicone solvent is by producing temperatures of
between 235 F and 250
F with a vacuum of from 27 inches to 29 inches. By producing temperatures
above the boiling
point of water 212 F and creating a slight vacuum < 20 inches the process is
able to vaporize the
low-end boilers and urge the condensed vapors to a separate vessel. Some
azetrophic will occur
and thus a water sensor on this vessel will cause the free water present to
leave the system. The
remaining hydrated solvent will return to the still for re-distillation.
After low-end boilers have been distilled (based on either time or an increase
in temperature) the
full vacuum (27 to 29 inches) is established with the full temperature (235 F
to 250 F) also
established resulting in distillation of dehydrated silicone solvent. The
condensed vapors are
urged to a separate vessel that may have a water sensor, for safety, allowing
the water if present
to leave the system. The solvent is returned to the tanks on the dry cleaning
machine for reuse.
The second source of hydrated solvent is from the drying recovery head, this
solvent is normally
very hydrated and is collected in a separate vessel that may contain a water
sensor so as to
eliminate free water. After the drying recovery cycle the collected hydrated
solvent is urged to
the still for distillation, thus the only solvent being re-cycled is through
the high-end boiler vessel
of the fractional distillation operation.
CA 02378940 2002-O1-09
WO 01106051 . T S00/19 0
;~I~u~ ~ ~ BUG 20c
the use of silicone-based solvent allows for latitudes in temperatures that
have not traditionally
existed in the dry cleaning field. The importance of controlling the
temperature of the liquid
solvents that are used in the field of dry cleaning is critical.
The most prevalent solvent used as previously stated is PERC whose temperature
is ideally
maintained at a range of 78 to 82 degrees Fahrenheit. This is also a common
range for all other
solvents currently being used in the field of dry cleaning. If the temperature
should increase, the
result is a much more aggressive solvent resulting in damage to textiles being
processed. The
increase in the KB (kari butyl) value most often results in causing dyes to be
solubilize from
articles being cleaned, resulting in the transfer of these dyes to other
articles being cleaned. The
concern for controlling temperature has caused manufactures of dry cleaning
machines to install
water cooling coils placed in the base tanks, and in-line water cooling
jackets on the plumbing
lines for heat transfer.
By increasing the temperature of the silicone-based solvent of the present
invention to a range of
90 to 130 degrees Fahrenheit, an aggressiveness in cleaning is afforded,
without the result of
pulling or stripping dyes. This may be best accomplished by circulating water
in a closed loop
fashion between a hot water tank and through a circulating pump and through
the coils
(previously used for cooling) and back to the hot water tank. The circulating
pump is controlled
by a temperature probe that can be placed in the solvent. The result is
precisely controlled
solvent temperature which influences the aggressiveness of the solvent without
causing damage
to the articles being cleaned. This is optional and is not necessary to
achieve good cleaning.
9
AMEi~~E~ ~~FET
CA 02378940 2002-O1-09
WO 01106051 ~~~~5~ ~1~ ~ ~~~
DESCRIPTION OF THE DRAWINGS
The aforementioned advantages of the present invention, as well as additional
objects and
advantages thereof, will be more fully understood hereinafter as a result of a
detailed description
of a preferred embodiment when taken in conjunction with the following drawing
in which:
Figure 1 is a schematic that represents a dry cleaning machine that is used
with solvent that has a
boiling point that if distilled requires vacuum distillation;
Figure 2 is a flow diagram indicating the flow of liquid in a dry cleaning
apparatus as described in
Figure 1;
Figure 3 is a flow diagram indicating the flow of vapor in a dry cleaning
apparatus as described
in Figure 1;
Figure 4 is a flow diagram indicating the functional steps of the method of
separating water from
the solvent using a separate apparatus; and
Figure 5 is a flow diagram indicating the functional steps of separating water
from solvent using
an apparatus as a part (OEM) of the dry cleaning machine;
Figure 6 is a flow diagram and schematic of a separator with functional steps
of the separation of
water from solvent.
Figure 7 is a flow diagram indicating the functional steps of condensing
liquid in a transfer drier
~e- and moving the liquid to a separator.
Figure 8 is a schematic that represents a transfer drier that is used with
solvent that has a boiling
point that requires vacuum distillation.
AMENDED 56~EET
CA 02378940 2002-O1-09
WO 01106051 /US00/~920
~~~IU~ 1 ~ AUG HOC
DISCLOSURE OF THE INVENTION
The present invention includes an apparatus and method used in conjunction for
the dry cleaning
of fabrics, textiles, leathers and the like.
To perform the interrelated cleaning steps involving the present invention, a
dry cleaning
apparatus is shown schematically in Figure 1, although it is recognized that
alternative cleaning
configurations can be used. It should be noted that the cleaning configuration
of Figure 1 may be
used for processing with a Class 3-A (solvent having a flash point between 140
F and 200 F)
type solvent.
The dry cleaning of articles or other items begins by placing them in a
horizontal rotating
cleaning basket 10. The wash cycle is initiated with a dry cleaning fluid
including an organo
silicone-based siloxane solvent being pumped using a pump 12. The solvent is
pumped from
either a working tank 14, or a new solvent tank 16, and then to the cleaning
basket 10 with the
articles. The course of the pumped solvent can either be through a filter 18,
or directly to the
cleaning basket 10
From the cleaning basket 10, the solvent is then circulated through the button
trap 20 to the pump
12. After agitation for a predetermined amount of time, the solvent is drained
and pumped to
either of the three tanks 14,16, and 22 shown in Figure 1. The cleaning basket
10 is then
centrifuged in order to extract the remaining solvent to any of the tanks or
to the still.
The types of filtration systems compatible with the particular solvent of the
present invention
are: a spin disc of a 20 and 60 micron type and may use diatomaceous earth
being capable of
optional use with the larger micron spin disc type; a tubular filtration (Aex,
rigid, or bump) also
being capable of optional use with diatomaceous earth; a cartridge (carbon
core, all carbon of the
standard size, jumbo or split size); and Kleen Rite cartridge system which may
result in no need
for a still. Filters may also be used with a dimension between 10 to 100
microns to filter
condensed vapors prior to separation.
The solvent may be filtered so as to eliminate the particulate soil that is
released from the articles
11
AMEs'~DE~ ~uE~T'
CA 02378940 2002-O1-09
W001/06051 ~~~~'~~~ ~~G 200
being cleaned. Further, filtering of the silicone-based solvent eliminates the
polymerization of the
solvent even in the presence of catalysts.
The solvent being used for cleaning may be distilled at a rate of 10 to 20
gallons per hundred
pounds cleaned, unless the aforementioned Kleen Rite cartridge system is being
used. To
accomplish this, a still 24 may be used to receive solvent from the filter 18,
or from the dirty tank
22, or the wheel 10. The solvent in the dirty tank 22 can be introduced to the
still through
suction since the still is under a vacuum that may be controlled by a float
ball valve (not shown).
Any recovered or condensed vapors originating from the still may be condensed
by water-cooled
coils of a still vapor condenser 26. Thereafter, gravity urges the condensed
solvent into a
primary separator 28 or holding vessel. The rate of flow, depending on the
still, may range
between .75 and 2.50 GPM, and the separator is engineered accordingly. Vacuum
may be
created by a liquid-head pump 30 or an evacuation process created by a
venturi.
During the drying process either as a part of the same machine or transferred
to the drier, the
articles are tumbled in basket 10 with air being forced by a fan 32 over
heating coils 34, which
results in the incoming air flow to be between 120 and 180 degrees Fahrenheit.
As the solvent
and water remaining on the articles are heated and become vapor, the airflow
exits the cleaning
basket 10 and passes over cooling coils of a drying vapor condenser 36 where
the vapors
condense back to a liquid. Gravity urges such liquid to the primary separator
28 or holding vessel
via a conduit 37.
The vapor laden air that leaves the cleaning basket 10 ranges in temperature
between 120 and
160 degrees Fahrenheit. This temperature is important in that it can also be
an advantage to
regulate the temperature at or below 140 degrees such that the temperature is
30 degrees
Fahrenheit below the flash point of the aforementioned solvent. In one
embodiment, the rate of
flow of the condensed liquid may be limited to 0.75 GPM, and the separator may
thus be
engineered for the combined flow rate of condensed liquid from the still and
drying vapor
condensers 26 and 36.
12
AMEI~~D~E~ W'~~T
CA 02378940 2002-O1-09
wo ono6osy~~~~~,o~~~ p,UG 200'
Figure 2, 3 & 4 illustrates an order in which the various components of the
present invention
may be employed for clarification purposes. Having followed the foregoing
process of dry
cleaning, there are no less than one but as many as two or more sources of
solvent to the
separator. The ability to return re-condensed solvent to the dry cleaning
system is dependent on
the separator and its efficiency.
To afford such efficiency, a method of water and solvent separation is
provided, as shown in
Figure 4, 5, & 6. As shown, a mixture of the silicone-based dry cleaning fluid
and any water
from the articles is received from one or both sources of condensed solvent
being; drying and or
distillation of the dry cleaning process. Upon receipt, the mixture may either
enter a holding
vessel or be urged directly through a porous structure that separates the dry
cleaning fluid and the
water. Next, the dry cleaning fluid is removed in the substantial absence of
water and is recycled
into the dry cleaning system.
Figure 6 is a schematic of the separators of one embodiment of the present
invention, which is
capable of performing the method of Figure 4 & 5. As the flow of the hydrated
solvent, or
mixture of water and dry cleaning fluid, approaches a main chamber 48 of the
separator Figure 4,
5, & 6 the mixture may be filtered 54 to prevent lint and particulate soil
from entering the
separator Figure 6 which may in turn restrict a coalescent filter that is
downstream. To
accomplish such filtering, coalescent media 54 may be draped at the initial
termination of an
inlet tube 52. The various media of the present invention may include nylon or
any other
coalescing media. The plumbing connection from the vapor condensers 26 and 36
of the dry
cleaning of Figure 1 & 8 may be plumbed to terminate at inlet 52
The hydrated solvent enters the separator (Figures 4, 5 & 6) where gravity
feeds it down the inlet
tube 52, which terminates several inches above an interface level between the
water and the dry
cleaning fluid. The silicone-based solvent is insoluble in water, yet water,
in small cellular size
does suspends itself in the hydrated solvent until they form globules. Due to
the combined
weight, the globules settle to the bottom of the main chamber 48.
13
AMENDED SHEET
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WO 01/06051 PCTIUS00/192 6
,~~AIU~ 1 ~ AUG 2001
As the overall hqwd in the mam chamber 48 rises, a float level switch 58 is
tnpped which in turn
activates a pump 60. The liquid is then pumped by the pump 60 through either 1
or 2 filters 62
that are rated as high as 20 to 50 microns and as low as 5 microns for
filtering (Figures 4, 5 & 6).
The hydrated solvent is then forced or pulled through a porous structure 64
which may be
positioned within the filter housing 62 or placed in-line post filter 62 and
which acts as a
"coalescing medium". Preferably, this structure is between 112 and 15 inches
in length with a
cross-section between 1/4 and 4 inches and has a cell size of under 20
microns. It should be
noted that there can be as many as one to three or more separate structures 64
positioned in line
of the filter housing 62. Some of the water globules are created as the
hydrated solvent is forced
through the porous structure 64 and appear on the outgoing side of the porous
structure 64.
The pump 60 may be electrical or pneumatic in form. The use of any flow method
such as the
pump 60 or, in the alternative, a vacuum results in sufficient separation. The
flow methodology
chosen should effect a flow of 0.5 to 3.5 GPM. If the inflow of hydrated
solvent is greater than
the porous structure 64 will allow, the re-positioning of the float level
switch 58, which activates
the flow controller, can be lowered to allow for a larger buffer for the
hydrated solvent. The flow
rate can be modified by raising or lowering the air pressure or using a
throttling valve.
The hydrated solvent is moved from the primary vessel 48 through the suction
line 59, through
the filter or filters 62. The hydrated solvent is exposed to the stripping
media 64 and then out into
the final vessel 68 having passed through a diffuser 65 and into the dry
cleaning machines clear
tank 16, Figure 1.
Located on the final vessel are three outlets. The highest is a safety
overflow 70 which carries
the solvent back to the primary vessel 48. The middle height line 66 carries
the solvent to the
clear tank 16 and the lower line 67 carries the possibly hydrated solvent to
the primary vessel 48
and creates a closed-loop process to protect the clear tank 16 from hydrated
solvent.
When this process is applied to an OEM (original equipment manufacture) system
the principles
are the same but the vessels may change. As demonstrated in Figure 6 the
source of the
condensed liquid 26 and 36 are the same with the hydrated solvent routed to
the first vessel 48
which if equipped with a water sensor 71 will actuate a valve so as to drain
the water off and
14
~Er~~~~ ~~C~
CA 02378940 2002-O1-09
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~~~~~°~ AUG 20C
close again once the water has been removed. The hydrated solvent will be
circulated either by
an add on pump 60 or using an existing dousing pump 60 that will circulate the
hydrated solvent
from the vessel 48 through a filter (less than 10 micron) 62 and then through
the stripping
medium 64 which will cause the water molecules to form globular size water
structures which
are then sensed by the water sensor 71 and thus drained from the vessel 48.
This leaves a
dehydrated solvent that can safely be recycled to the clear tank 16 Figure 1.
The water that is collected at the bottom of the main chambers 48 & 68 is
evacuated manually or
by a water float switch (not shown) which mechanically opens a hinged valve
There is also an
option of using two conductivity points, or probes (not shown), that make
contact as the water
rises in order to complete a circuit to signal either a pneumatic or electric
valve which may
discharge the water that is in the main chambers 48 & 68. There may also be a
manual drain at
the bottom of the main chambers 48 & 68 for manual periodic maintenance.
The composition of the main chambers 48 & 68 can be stainless steel, or
polyethylene.
Constructing with the use of carbon steel is discouraged since oxidation and
rusting can quickly
occur.
While various embodiments have been described above, it should be understood
that they have
been presented by way of example only, and not limitation. Thus, the breadth
and scope of a
preferred embodiment should not be limited by any of the above-described
exemplary
embodiments, but should be defined only in accordance with the following
claims and their
equivalents.
ANIENDE'~ ~u~~"~
