Title of Invention

OIL DEHYDRATOR

Abstract A method and apparatus for the removal of free, emulsified, or dissolved water from liquids of low volatility, such as oil, is shown. The liquid of low volatility is removed by contacting the fluid stream of concern with one side of a semi-permeable membrane. The membrane divides a separation chamber into a feed side into which the stream of fluid is fed, and a permeate side from which the water is removed. The permeate side of the chamber is maintained at a low partial pressure of water through presence of vacuum, or by use of a sweep gas. (FIG.NIL)
Full Text TITLE
OIL DEHYDRATOR
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the
lubrication and hydraulic industry, and particularly to
an apparatus and a process used for the removal of free,
emulsified, or dissolved water from oil, and more
generally, from liquids of low volatility.
2. Discussion of the Related Art
Oil is used in lubrication and hydraulic systems.
It is widely recognized that the presence of water has
deleterious effects on the oil in such systems, the
components in the systems, and the operation of the
systems. It is well known chat corrosion; oil
oxidation, chemical wear and tear, reduced bearing
fatigue life, and loss of lubricity may result when
water contamination enters a lubrication or hydraulic
system. These deleterious effects can be directly
attributed to water present in free, emulsified or
dissolved form.
Consequently, significant efforts have been made to
remove water from oil in order to provide optimal
performance of lubrication and hydraulic systems. The
devices and systems that have been used to remove water
contamination include settling tanks or reservoirs,
centrifuges, water absorbing filters, and vacuum
dehydration oil purifiers. However, these have had
significant limitations in either their water removal
capabilities, ease of operation, capital costs, or
operating costs, as will be discussed.
Settling tanks remove bulk quantities of "free"
water from oil based on the difference in their
densities and gravitational settling. To be effective
in removing "free" water, settling tanks require large

residence times and a significant amount of floor space.
However, they are ineffective in separating oil-water
emulsions and are not capable of removing dissolved
water.
Centrifuges accelerate the gravitational settling
of water from oil by imposing centrifugal force on the
fluid that, in effect, elevates the gravitational force.
Centrifuges are effective in removing free water from
the oil. However, these centrifuges are generally
expensive, and have limited capability of separating
oil-water emulsions. They cannot remove dissolved water
from the oil.
Water absorbing filters use special filter media
that absorbs water from the oil. As the water is
absorbed, the media swells, the flow is restricted, and
the pressure drop across the filter rises. When the
pressure drop reaches a predetermined level, the water
absorbing filter is removed, disposed of, and a new
filter is installed. These water-absorbing filters are
effective in removing free water but have marginal
effect in removing emulsified or dissolved water from
the oil. In addition, water-absorbing filters have a
limited capacity for water. Therefore, they must be
replaced once they are saturated with water.
Consequently, they are typically only used in
applications where trace amounts of water are present.
In applications where water concentrations are higher,
the cost of continuously replacing water-absorbing
filters becomes very high.
Several types of vacuum dehydration oil purifiers
have been used for oil dehydration. These generally
operate under the principle of vacuum distillation, mass
transfer of moisture from the oil to dry air, or a
combination of the two.
In vacuum distillation, a vacuum is applied to
reduce the boiling point of the water. For example,
while the boiling point of water is 100°c (212°F) at 1013

mm H20 (29.92"Hg) barometric pressure (standard
atmospheric pressure), its boiling point at 100 mm H,0
(approximately 26" Hg of vacuum) is only 50°C (122°F) .
By applying a sufficient vacuum relative to the
temperature of the oil, the water in the oil will
evaporate from the oil into the low-pressure air
(vacuum), thus dehydrating the oil.
Flowing the oil into a contactor vessel which has a
vacuum applied to it by means of a vacuum pump is the
typical means by which this is achieved. In order to
maximise the water vaporisation rare in a given vessel,
large surface area-to-volume ratios of oil are
preferred. This can be accomplished by means of flowing
the oil over structured packing, random packing,
cascading plates, spinning discs, or other methods well
known in the vacuum distillation and contactor fields.
The oil usually enters at the top of the contactor and
flows gravitationally downward over the packing,
spreading into relatively thin films. The oil collects
in the bottom of the vessel where it must be pumped out
by means of an oil pump. Examples of these are U.S.
Patent No. 4,604,109 by Koslow and U.S. Patent No.
5,133,880 by Lundquist,et al. Heat may be added to the
oil in order to reduce the amount of vacuum needed.
Vacuum is applied to lower the water boiling point,
and to increase the water removal rate. Heat may also
be applied to increase the water removal rate. However,
great care must be taken in not applying too much heat
and/or vacuum because more and more of the lower
molecular weight hydrocarbons in the oil will also be
vaporized as the temperature and/or vacuum is increased
to levels below their boiling points. It should be
understood that any liquid with a boiling point less
than water will also be removed. This may, or may not
be desirable, depending upon the application.
Mass transfer-based systems use similar contactor
vessels. However, rather than relying on distillation

for removal of the water, dry air or gas is continuously
passed countercurrently upwards across the oil that
flows downward. Water molecules in the oil will move
via a concentration gradient into the relatively drier
air. The now humid air is drawn from the contactor by a
vacuum pump or blower and exhausted to atmosphere. It
is not necessary to heat the oil more than the boiling
point of water in order for the water to vaporize.
Therefore, less heat and/or vacuum can be used for water
removal with a mass transfer-based system than in vacuum
distillation systems.
While vacuum distillation and mass transfer systems
do remove free, emulsified and dissolved water, they
have several drawbacks that have prevented their
widespread use. In both systems, liquid level controls
are used within the vessel in order to ensure that the
oil level does not become so low so that the oil pump
runs dry. The liquid level controls also function to
ensure that the oil level does not become so high that
the vacuum vessel fills with oil. This would reduce or
eliminate the water removal efficiency of the vessel and
may even lead to the oil entirely filling the vessel and
overflowing into the vacuum pump.
Vacuum purifiers are also subject to foaming within
the vessels as water is vaporized within the oil. This
foam has a lower specific gravity than the oil and can
cause malfunctioning of the liquid level controls and a
reduction in the performance of the purifier.
Due to the very nature of the use of heaters,
controls, pumps, etc., purifiers are relatively complex
pieces of equipment. In addition, the type of packing
used, the viscosity of the oil, and the airflow rate,
limit the flow rates through contactor vessels. This
usually results in very large vessels being used
relative to the amount of flow. When packaged with all
of the necessary oil pumps, vacuum pumps, heaters,
controls, electrical panels and connections, the system

becomes quite large and expensive. With the number of
components and complexity of these systems, the
maintenance and operating costs are usually quite high
as well.
Due to their ability to remove free, emulsified or
dissolved water from oil, vacuum dehydration oil
purifiers have become the desired method for water
removal from oil. However, the drawbacks associated
with vacuum oil purifiers have prohibited these
purifiers from being" widely used and/or are not
practical on the majority of lubrication or hydraulic
systems. Because of their relatively large size and
costs, they are limited to non-mobile, stationary
applications, and are not practical for use on mobile
equipment.
Due to their high capital cost, they are typically
not permanently installed in a system unless it is a
relatively large, expensive lubrication or hydraulic
system. Instead, they are usually shared by several
systems by using one to purify the oil on one machine or
reservoir for a period of time, and then move it to
another machine, etc. However, when the purifier is
being used in this manner, the oil in the machines that
are not connected to the purifier can become
contaminated with water. This oil will remain
contaminated until the purifier can be reattached to
them and the oil dehydrated again. Thus, those skilled
in the art have continued to search for better ways to
remove oil from water. Applicants have directed their
efforts toward membrane based systems.
Membrane based systems have been used to remove
water from organic systems. It must, however, be
recognized that the presence of pores or defects in a
membrane used for this purpose will result in the
hydraulic permeation of the oil to the permeate side.
This situation will result in the loss of oil. It will
also allow the non-volatile oil to coat the permeate

side of the membrane, thereby fouling the membrane and
reducing its effectiveness in permeating water.
U. S. Patent No. 4,857,081 to Taylor discloses a
process for the dehydration of hydrocarbons or
halogenated hydrocarbon gases or liquids. This process
is based on a cuproammonium regenerated cellulose
membrane. Cuproammonium regenerated cellulose membranes
are known to those skilled in the art to have a
structure of mutually connected passages or pores (U. S.
patent No. 3,888,771 to Isuge et al) . These membranes
are also said to have a distribution of pores of the
order of 10-90 A, with a mean of 30 A (U. S. Pat. No.
3,888,771 to Isuge et al, U. S. Pat. No. 5,192,440 to
Sengbusch) . The mechanism for separation of water from
the liquid organic phase through this cuproammonium
regenerated cellulose is that of dialysis. The
permeating species permeates the membrane as a liquid.
Since the membrane has pores, it permits hydraulic
permeation through it. Water-soluble species may
permeate through it as well. This precludes its utility
in the dehydration of oil, as the oil will always have a
finite solubility in water.
Even if Taylor were satisfactory for dehydration
of oil, the structure of Taylor will itself cause
defects. The molecular structure of the regenerated
cellulose membranes is maintained by the presence of
moisture. Upon removal of the moisture from the
hydrophilic membrane, the pores-undergo large capillary
stresses which can lead to, shrinkage and cracking of the
membrane. Since the membranes have pores of various
sizes the capillary stresses formed during drying result
in differential stresses throughout the membrane
microstructure. This differential stress is known to
cause cracks or "defects" in the membrane. If such a
membrane is used to dehydrate a closed system, the
moisture in the membrane will be eventually stripped
out. This results in the creation of cracks or


"defects" as described above. These "defects" will now
cause the hydraulic transport of oil through the
membrane.
U. S. Pat. No. 5,182,022 to Pasternak et al
discloses a pervaporation process for the dehydration of
ethylene glycol. The ethylene glycol is completely
miscible with water, and is characteristic of
pervaporation applications where the mixtures to be
separated are fully miscible. The sulfonated
polyethylene resin membrane that is used permits
substantial quantities of ethylene glycol to permeate.
It will be apparent to those skilled in the art that the
permeation of such quantities of ethylene glycol is due
to hydraulic permeation through defects (see definition
below), which are present in the discriminating layer.
The invention does not require a defect-free
discriminating layer because the loss of the non-aqueous
phase is tolerable. This is not the case in the
dehydration of oil in a lubrication and hydraulic
system.
U. S. Pat. No. 5,464,540 to Friesen discloses a
process for the removal of a component from a liquid
feed mixture via the process of pervaporation. The
sweep stream in the Friesen et al patent is comprised of
a component of the feed stream that is not to be removed
and is introduced to the module as a vapor. In column
5, lines 8 to 13, Friesen et al postulates that the
process can be used to dehydrate oils such as sesame oil
and corn oil. However, in the examples provided in the
patent, Friesen et al only provides performance data for
the dehydration of organic compounds of high volatility,
much in excess of sesame oil and corn oil. In
particular, Friesen provides examples for the
dehydration of acetone, toluene, and ethanol.
Consequently, it is clear that Friesen fails to
recognize and teach the need for a defect free (as
described hereinbelow) non-porous membrane for the

dehydration of these types of oils. Those skilled in
the art may also question the feasibility of providing a
sweep stream of corn oil or sesame oil vapor.
U. S. Pat. No. 5.552.023 to Zhou discloses a
membrane distillation technique for the dehydration of
ethylene glycol. This process employs a porous
membrane. This is unattractive for the dehydration of
oils because of the likelihood that the porous support
will get wetted out and hydraulically permeate the
fluids.
U. S. Pat. No. 6,001,2 57 to Bratton et al discloses
a zeolite membrane that is substantially defect-free for
the purpose of dehydration of various liquids. As noted
in column 4, lines 12-15 of Bratton, the use of the
zeolite membrane is critical to the function of the
apparatus, as it can be used to separate any two liquids
where only one liquid can pass through the zeolite
membrane. Zeolite membranes use zeolitic-type
materials, which are also known as molecular sieves, and
contain a network of channels formed from silicon/oxygen
tetrahedrons joined through the oxygen atoms. Column 2,
lines 46-49, indicate that the material should be
"substantially free of defects", without defining the
extent of "substantially" or the implied meaning of
"defect". Such a membrane cannot be used for the
dehydration of oils because the presence of defects,
described hereinbelow, will result in the hydraulic
permeation of oil to the permeate side.
In the context of the present invention, the
following terms, as used throughout the application, are
intended to convey the meanings defined hereinbelow:
Definitions:
"Defect", as used herein, is used to indicate an
aperture through the membrane of sufficient size to
allow hydraulic permeation of the liquid of low
volatility through the membrane.

"Defect free", therefore, indicates a membrane
containing no apertures of sufficient magnitude to allow
hydraulic permeation of liquids through the membrane,
instead limiting the passage of materials through the
membrane to solution diffusion. Hydraulic permeation of
oil will tend to occur when permanent apertures (i.e.
pinholes) of a diameter greater than or equal to the
molecular size of oil are present in a membrane. It is
expected chat the molecular size of the oil molecules is
greater than 5 to 10 Angstroms, however since oil
consists of fractions of different molecular size, the
exact value will depend on the chemical makeup of the
particular oil being dehydrated. Thus defect free
membranes are limited to apertures of a smaller diameter
than the molecular size of the oil molecules.
"Non-porous" indicates membranes that do not
contain what are commonly referred to as pores, that is
permanent apertures of at least the molecular size of
the oil molecules, which as discussed above is expected
to be greater than 5 to 10 Angstroms, but absolutely
dependent on the particular type of oil being
dehydrated.
While a defect free membrane, as used herein, is
inevitably non-porous, a non-porous membrane, as used
herein, is not necessarily defect free. In theory, a
non-porous membrane would be one that is defect free,
i.e. free from defects as described above. This implies
that, a defect free membrane would have the same gas
permeability/selectivity as a dense film made from the
same material. In practice, however, this is not the
case. For example, Pinnau and Koros (Pinnau, I. And
Koros, W., "Gas-Permeation Properties of Asymmetric
Polycarbonate, Polyestercarbonate, and Fluorinated
Polyimide Membranes Prepared by the Generalized Dry-Wet
Phase Inversion Process," J. Applied Polymer Science
Vol. 46 1195-1204 (1992)) and Pesek (Pesek, S. "Aqueous
Quenched Asymmetric Polysulfone Flat Sheet and Hollow

Fiber Membranes Prepared by Dry/Wet Phase Separation"
Dissertation submitted to The University of Texas at
Austin (1993)) have defined a defect-free gas separation
membrane as a membrane that has 75% to 85% of the
perselectivity of a dense film. It can be shown that, a
membrane that has 85% of the permselectivity can contain
a significant number of defects that would allow for the
hydraulic permeation of oil.
Consider a membrane consisting of a polysulfone
selective layer supported by a substructure of
negligible resistance. At 35ºC, polysulfone has an
oxygen permeability of 1.4 barrer (Membrane Handbook)
and an O2/N2, selectivity of 5.6. Consider the thickness
of the polysulfone selective layer to be 700 A. This
thickness is typical for commercially available
membranes. Accordingly, the permeance of this selective
layer for oxygen would be 20 GPU and for nitrogen 3.57
GPU. According to Pinnau and Koros (1992) this
polysulfone membrane would be considered defect free if
the O2/N2, selectivity was 85% of the dense film, or in
this case 4.76. Obviously according to the definition
of the present invention, this membrane contains
defects. If the defects are small enough, the flow
through the defects will be governed by knudsen
diffusion. If the defects are large, then flow through
the defects will be convective (or viscous) and will
obey the Hagen-Poiseuille law. The table below
illustrates the number of defects of different size that
would result in a O2/N2, selectivity of 4.76 for a 1
square meter polysulfone module.



Knudsen Diffusion Through Defects in Selective Layer
Defect Diameter (A) 25 50 100
Number of Defects 1.22E+1 1 1.53E+10 1.91E+9
Surface Porosity (Defect Area/Total Area) 6.0E-7 3.0E-7 1.5E-7

Convective Flow Through Defects in Selective Layer, 1 psig Applied Pressure
Defect Diameter (»m) 0.5 1 2
Number of Defects 39700 247 15
Surface Porosity (Defect Area/Total Area) 7.8E-10 1.9E-10 4.9E-11
The average size of the defects listed in the above
table are large enough to allow hydraulic permeation of
oil through the defects and render a oil dehydration
module commercially unviable. However, for an
application such as gas separation, the presence of the
defects merely reduces the efficiency of the separation
but does not render the module commercially unviable.
In theory, a non-porous membrane would be one that
is defect free, i.e. free from defects as described
above. In practice, however, this is not the case. As
practiced, and as recognized by one skilled in the art,
a membrane that is regarded as being non-porous will
allow hydraulic permeation up to a certain factor,
typically sufficient to reduce its gas selectivity by up
to 85% from the intrinsic selectivity of the dense film,
and will still be considered a non-porous membrane.
Thus, such a membrane would actually have a relatively
small but still significant number of pores. The actual
number of pores that would be acceptable in a "non-
porous" membrane would be related to the size of the
pores and the properties of the materials being

separated by the membranes. As used herein, the defect
free membranes refer to non-porous membranes that are
non-porous as defined hereinabove, and not non-porous as
the term is generally used in the art. For the
successful practice of the present invention, the
membrane must be "non-porous" and "defect-free" as the
terms are defined herein.
"Oil" is used to indicate a low volatility chemical
material. Typically, the oil will comprise many
fractions of different molecular weight and molecular
structure in a mixture.
"Semi-permeable" indicates a membrane that allows
permeation of certain materials while being resistant to
the transport of other materials. Such a membrane can
also be referred to as a discerning membrane.
"Wetting" indicates the spreading of a liquid over
a surface.
"Fouling" indicates adding a resistance to mass
transfer through an undesirable action such as filling
the porous substructure of the membrane with oil, or
coating the sweep side of the membrane with oil.
SUMMARY OF THE INVENTION
The present invention provides a membrane based
process for removing free, emulsified or dissolved water
from oils or other liquids of low volatility. This
process is such that it may be used on mobile equipment
while in operation and moving, as well as on stationary
equipment and processes. The operation of this process
is simple, while the equipment in question is small and
compact making it practical and cost effective for
systems of all sizes.
The present invention further provides for a
defect-free discriminating layer, or membrane, which
does not permit the hydraulic permeation of liquids
through it, restricting permeation to transport through
the discriminating layer. The invention further

provides for the removal of the vapors permeating
through the discriminating layer. Thus, the present
invention provides an apparatus and method for more
efficiently separating free, emulsified and dissolved
water from oil.
Specifically, this invention relates to the process
of using a non-porous, defect free membrane to remove
water selectively from oils. More particularly, the
process consists of removing water from the oil stream
of concern by contacting the oil with one side ("feed
side") of a semi-permeable membrane. The membrane
divides a separation chamber into the feed side into
which the oil is fed, and a permeate side from which the
water is removed. The permeate side is maintained at a
low partial pressure of water through presence of
vacuum, or by use of a sweep gas. The water in the oil
may be either in the dissolved form, or, as a separate
phase, either emulsified, dispersed or "free." The
membrane material is one that is of the appropriate
chemical compatibility with the oil, while selectively
permitting the transport of water across it. The
membrane is chemically compatible with the oil if it
does not chemically react with the oil, or if its
physical properties such as size, strength,
permeability, and selectivity are not adversely affected
by contact with the oil.
Thus, one of the objects of the present invention
is to overcome the shortcomings of conventional oil
dehydration techniques, and provide a new apparatus and
a process for dehydrating oil that overcomes these
limitations.
Another object of this invention is to provide an
oil dehydrator that removes free, emulsified or
dissolved water from oils.
A further object of the present invention is to
provide an oil dehydrator that is simple to operate.


A further object of the present invention is to
provide an oil dehydrator that is relatively small and
compact.
A further object of the present invention is to
provide an oil dehydrator that is cost effective.
A further object of the present invention is to
provide an oil dehydrator that is practical to use on
small and large systems.
A further object of the present invention is to
provide an oil dehydrator that may be used on mobile
equipment while in operation and moving.
Further objects and advantages of the present
invention will be apparent from the following
description and appended claims, reference being made to
the accompanying drawings forming a part of the
specification, wherein like reference characters
designate corresponding parts in the several views.
BRIEF DESCRIPTION OF THE ACCOMPAYING DRAWINGS
Fig. 1 is a perspective view of a membrane
construction used in the present invention.
Fig. 2 is a perspective view of a modification of a
membrane useful for the present invention.
Fig. 3 is a perspective view of a further
modification of a membrane useful for the present
invention.
Fig. 4A is a plan view of a plurality of hollow
fiber membranes, as shown in Fig. 3, woven into a mat.
Fig. 4B is a cross sectional view, taken in the
direction of the arrows, along the section line B-B of
Fig. 4A.
Fig. 4C is a schematic diagram of the mat shown in
Fig. 4B after being spirally wound.
Fig. 4D is a perspective view of two hollow fiber
semi-permeable membrane constructions, such as
illustrated in Fig. 3, after being helically wound.


Fig. 5 is a schematic view of the construction
shown in Fig. 1 after being spirally wound.
Fig. 6 is a schematic view of an exemplary membrane
separation process embodying the present invention,
wherein the water is removed by means of a vacuum pump.
Fig. 7 is a schematic view of a modification of
separation process shown in Fig. 6, wherein the water is
removed by means of a sweep gas stream.
Fig. 8 is a schematic of a further modification of
the separation process shown in Fig. 6, wherein the
membrane is protected from contaminants in the feed
stream by means of an upstream filter.
Fig. 9 is an elevational view of a hollow fiber
membrane device embodying the construction of the
present invention, wherein the feed flows in the bore of
the fibers.
Fig. 10 is an elevational view of a hollow fiber
membrane device embodying the construction of the
present invention, wherein the feed flows on the outside
of the fibers.
Fig. 11 is an elevational view of a hollow fiber
membrane device embodying the construction of the
present invention, wherein the feed flows on the outside
of the fibers and the water is removed countercurrent to
the exiting oil. The oil is extracted by means of a
perforated core.
Fig. 12 is an elevational view of a hollow fiber
membrane device embodying the construction of the
present invention, wherein the water is removed by means
of a sweep gas.
Fig. 13 is a perspective view of a modification of
the construction shown in Fig. 1 wherein the membrane
has an integrally formed skin.
Fig. 14 is a fragmentary end elevational view of
the construction shown in Fig. 13.


Fig. 15 is a perspective view of a modification of
the construction shown in Fig. 3 wherein the membrane
has an integrally formed skin.
Fig. 16 is a fragmentary end elevational view of
the construction shown in Fig. 13.
DETAILED DESCRIPTION OF THE INVENTION
It is to be understood that the specific devices
and processes illustrated in the attached drawings, and
described in the following description, are exemplary
embodiments of the inventive concepts defined in the
appended claims. Hence, specific dimensions and other
physical characteristics relating to the embodiments
disclosed herein should not be considered as limiting,
unless the claims expressly state otherwise.
Before describing the preferred embodiment of the
invention, incorporated herein as if fully rewritten are
the Membrane Handbook, pages 3-15, published by Van
Nostrand Reinhold, 1992 and the Handbook of Industrial
Membranes First Edition, pages 56-61, 1995.
According to the present invention, there is an
apparatus and a process with utility in the
discriminating removal of water, or other highly
volatile solvents, from a broad class of liquids of low
volatility. A liquid of low volatility is defined as a
liquid with a normal boiling point greater than that of
water (100°C) . Water may thus be categorized as a liquid
of high volatility. It is necessary to recognize that
components that may exhibit low volatility in the pure
state may behave non-ideally in a mixture. This can
result in a greater apparent rate of evaporation of a
component from a mixture than would be expected from
pure component volatilities. Preferably, the present
invention is involved in the separation of water from
oil.
More specifically, the process of dehydrating the
oil consists of the following steps: contacting one side

of a non-porous, defect-free, semi-permeable membrane
with a liquid stream containing at least oil and water,
wherein the membrane divides a separation chamber into a
feed-side, into which the feed liquid mixture is fed,
and a permeate side, from which the water is withdrawn;
maintaining a partial chemical potential gradient for
water such that the water preferentially permeates
through the membrane from the feed side to the permeate
side; removing, from the permeate side, the water that
has permeated; and removing, from the feed side of the
membrane the oil that is dehydrated. The term "chemical
potential gradient" may also be referred to as an
"activity gradient" or as a "partial pressure gradient.
The term "partial pressure gradient" is understood to
mean the difference between the water vapor pressure on
the permeate side and the equilibrium water vapor
pressure cirresponding to the water concentration in the
oil.
The device for dehydrating the oil consists of a
vessel containing at least a nonporous, semi-permeable,
defect-free membrane interposed in said vessel in such a
fashion as to divide the interior of the vessel into at
least one feed-side space and one permeate space; at
least one inlet opening to the feed space; at least one
outlet opening to the feed space; and at least one
outlet opening to the permeate space. Such an apparatus
would enable flowing the oil-water mixture in through
the inlet opening, and contacting at least one side of
the semi-permeable membrane; maintaining a chemical
potential gradient for water such that the water
preferentially permeates through the membrane from the
feed side to the permeate side; removing, from the
permeate side, the water that has permeated through the
outlet opening; and removing from the feed side of the
membrane, the oil that is dehydrated, through the outlet
opening.

The membrane can be in any form or shape as long as
a surface suitable for separation is provided. Common
examples of this include self-supported films, hollow
fibers, composite sheets, and composite hollow fibers.
The hollow fiber membranes may be potted or otherwise
disposed so that the fibers are nominally parallel to
each other. The fibers of the composite hollow fiber
membrane or the hollow fiber membrane may be helically
wound or twisted. Alternatively, the fibers may also be
woven into a mat. In the case of a membrane that is
composed of flat sheets or mats of fibers, the sheets or
mats may be spirally wound. In addition, spacers may
separate the sheets or mats.
The membrane used is made, at least in part, of a
thin, defect-free, dense, nonporous, discriminating
layer (the term "discriminating layer" may also be
referred to as "skin") and a support structure. In an
alternate embodiment, the discriminating layer may be
self-supporting; however, this is not required to
practice the invention. To those skilled in the art, it
is clear that dense, nonporous, discriminating layers
may have defects in the discriminating layer. When such
a discriminating layer is used for separating a mixture
of gases, or of liquids, non-discriminating transport
may occur through these defects. In the case of such a
discriminating layer used to separate a gas mixture, the
transport through the discriminating layer occurs by
"solution-diffusion", whereas transport through the
defects occur by Knudsen diffusion. This has been
documented by Clausi Clausi, N. "Formation and
Characterization of Asymmetric Polyimide Hollow Fiber
Membranes for Gas Separation" Dissertation submitted to
The University of Texas at Austin (1998). When such a
defect-containing discriminating layer is used to
separate a mixture of liquids, non-discriminating
hydraulic transport will occur through these defects.
The hydraulic permeation through these defects will

result in liquid permeation to the permeate side of the
membrane. While such non-discriminating transport is
acceptable in some applications, it is not acceptable in
other uses.
An example of a defect-free, dense, nonporous
discriminating layer is that of a solution cast dense
membrane. These membranes are very well known in to
those skilled in the art. A defect-free, dense,
nonporous discriminating layer with a dehydration rate
that is commercially viable, may be made by solution
casting such films with a sufficiently thin thickness as
to permit the desired dehydration rate. Potential
defects may be eliminated by multiple coats of the
solution cast polymer, with intermediate cross-linking
steps.
In the specific instance of oil dehydration, the
hydraulic permeation of oil to the permeate side will
result in the loss of oil from the system, rendering the
dehydrator commercially non-viable, and will result in
the fouling of the permeate side of the membrane. If
the discriminating layer is supported on the permeate
side, the hydraulically permeated oil will fill the
porous support and foul the membrane by offering a
resistance to the transport of water. Further, since
the oil is unlikely to evaporate, or if evaporation does
occur, it will not evaporate faster than the rate of
hydraulic permeation through the defects, the presence
of defects will irreversibly foul the membrane and
reduce the rate of dehydration. Further, if the
membrane is not completely defect-free, the sweep that
may be used on the permeate side to sweep away the
moisture may pass through the membrane and thus be
entrained in the "clean" oil. This may create foam in
the oil, and is thus undesirable.
The mechanism of transport through such a the
defect-free, dense, nonporous discriminating layer is
through "solution-diffusion." To those skilled in the

art, the term "solution-diffusion" is understood to mean
the dissolution of the permeating species into the
discriminating layer, followed by diffusion through the
discriminating layer, followed by de-sorption on the
permeate face of the discriminating layer. The oil and
water exist in the liquid phase on the feed side of the
membrane, whereas, the permeated species are removed
from the permeate face of the discriminating layer in
the vapor, or gas phase. If the discriminating layer
contains any defects, hydraulic permeation will occur
through the discriminating layer resulting in the
transport of liquids to the permeate side. As described
above, this situation will foul the membrane and result
in the loss of oil from the system, both leading to a
commercially non-viable product.
Pervaporation, to those skilled in the art, is
understood to mean the separation of a mixture of
liquids that are completely miscible through a dense,
nonporous discriminating layer. Further, pervaporation
is understood to mean that the components permeate
through the discriminating layer at a finite rate and
are removed on the permeate side as a vapor. Further,
in the case of pervaporative dehydration, in the event
of a defective discriminating layer, the hydraulic
transport of the non-aqueous phase to the permeate side
is not catastrophic. This is because the non-aqueous
phase has a high vapor pressure and is easily
evaporated. This is the case even for low volatility
components such as ethylene glycol which when mixed with
water can exhibit significant non-expected behavior
compared to the pure component.
Porous membranes such as those used for micro-
filtration, ultra-filtration, and dialysis are not
suitable, as the low volatility fluid will permeate the
pores, and foul the membrane.
Included as suitable membranes are dense, nonporous
polymer films or asymmetric membranes with relatively

dense discriminating layers, or skins, on one, or both,
surfaces of a support structure. Dense, nonporous
membranes are made either by "phase inversion," or by
"solution casting." In the case of phase inversion, a
polymer-solvent-nonsolvent system is forced to
precipitate by evaporating the solvent, extracting the
solvent, or introducing nonsolvent into the system.
Phase inversion results in a non-homogeneous, porous
polymer matrix which may or may not be symmetric, and
which may or may not have a region of dense, nonporous
polymer. A dense, nonporous discriminating layer may be
formed by phase separation by the appropriate choice of
solvent-nonsolvent systems and precipitation systems.
In the case of solution casting, a suitable polymer-
solvent system is permitted to gel and then dry.
Solution cast polymers are typically not porous and are
homogenous films. In both cases, the dense, nonporous
film may be formed on another support structure. The
dense, nonporous discriminating layer formed by both
methods is likely to have defects (U. S. Pat. No.
4,230,463). Methods to post treat these discriminating
layers to reduce defects substantially have also been
reported by Henis and Tripodi (Henis, J. and Tripodi,
M., "Composite Hollow Fiber Membranes for Gas
Separation: The Resistance Model Approach, " J. Membr.
Sci. (8) 233-245 (1981)). These methods to reduce these
defects involve repeatedly coating the defective
membrane until all the defects are eliminated. The
secondary coat may be based on the same polymer as the
original layer, or based on a different polymer.
A defect-free, dense, nonporous, discriminating layer
may be formed by solution casting a sufficiently thick
homogenous polymer film. It has also been demonstrated
by Pfromm that ultra-thin, defect-free, dense, nonporous
discriminating layers may be formed (Pfromm, P. H. "Gas
transport properties and aging of thin and thick films

made from amorphous glassy polymers" Dissertation
submitted to The University of Texas at Austin (1994)).
The transport characteristics of gases through a
defect-free, dense, nonporous, homogeneous polymer film,
to those skilled in the art, is typically considered an
"intrinsic" property of the polymer (Clausi, 1998) . The
intrinsic permeability of the polymer, for example, is
independent of the thickness of the discriminating
layer. If such a discriminating layer is used to
separate a mixture of gases, and the layer is either a
free standing film, or a composite on a support with
negligible transport resistance compared to the
discriminating layer, the ratio of the permeabilities of
the specific mixture is also an intrinsic property of
the polymer under these specified conditions. This
ratio is called the intrinsic selectivity of the polymer
to the specified gas components.
If the dense, nonporous, discriminating layer does
not exhibit the "intrinsic" selectivity to a particular
combination of gases, it is likely that this
discriminating layer contains defects. This is because
the defects permit non-discriminating transport of the
components to be separated. This technique is commonly
used, by those skilled in the art, to determine the
presence of defects in discriminating layers, when the
porous support offers negligible resistance to flow
(Clausi, 1998; U.S. Pat. No. 4,902,422). This technique
may be used to determine the presence or absence of
defects regardless of the mechanism of formation of the
discriminating layer. If it is verified that the
discriminating layer is defect free, it will not permit
the non-discriminating transport of gases or liquids,
and in the case of liquid permeation, the permeating
species will de-sorb from the membrane as a vapor.
The thin, dense, nonporous discriminating layer may
be a separate layer. It may also be formed at nominally
the same time, and integrally with, the support

structure. It may consist of the same material as the
support structure, or a different material in a
composite form. The composite membrane has a dense
layer that is attached to the support structure. The
dense, nonporous, discriminating layer may be formed as
a separate step at a later time. These composite films,
fibers, or sheets may be porous or nonporous. The
sheets, preferably, are flat, though this is not
required to practice the invention. These fibers, films
or sheets may be potted on one or more sides to separate
the feed from the permeate space. The discriminating
layer in such a membrane may be identical to or
different from the support structure that may be
composed of porous organic or inorganic polymer, ceramic
or glass. The preferred embodiment would be a composite
sheet or composite hollow fiber with a thin, dense,
nonporous, discriminating layer of polymer on one or
both faces of the support. In the case of a symmetric
or asymmetric membrane, the liquid may contact the
membrane on either side, although the preferred
embodiment would be the one that minimizes the boundary
layer on the feed side.
The dense nonporous layer, or skin, may also be an
integral part of the membrane and formed at least
nominally at the same time as the support structure.
However, the invention is not limited to forming the
dense nonporous layer at the same time as the support
structure. The invention may also be practiced by
forming the dense nonporous layer as a component (a.k.a.
composite part) of the membrane. The dense nonporous
layer may be formed at a different time than the support
structure. In this case, the dense nonporous layer is
subsequently attached to the support structure.
The support structure may be porous or nonporous.
The dense nonporous skin, or the support structure, may
be polymeric in nature. The dense nonporous skin, or
support structure, may be an inorganic or organic

polymer. The polymer may be a linear polymer, a
branched polymer, a crosslinked polymer, a cyclolinear
polymer, a ladder polymer, a cyclomatrix polymer, a
copolymer, a terpolymer, a graft polymer, or a blend
thereof.
The liquid of low volatility may wet the porous
support structure. Alternatively, the porous support
structure may be treated so that the liquid of low
volatility does not wet the structure. However, this is
not required to practice the invention. The invention
may still be practiced when the porous support structure
is not wetted with the liquid of low volatility.
Furthermore, the invention may still be practiced when
the porous support structure is treated such that the
structure is not wetted with the liquid of low
volatility. Preferably, the porous support structure is
of such a nature that the low volatility liquid does not
wet the structure.
In the situation wherein the membrane consists of a
dense, nonporous layer, or skin, on only one side, the
presence of defects in the dense, nonporous layer would
likely result in passage of the oil, as discussed above.
If the oil hydraulically permeates through the membrane
it will likely evaporate at a slower rate than the
water, or not at all, thus fouling the membrane and
reducing dehydration rates. Consequently, the preferred
embodiment would be one that has a defect free, dense,
nonporous, discriminating layer, or skin, on one or both
sides of the porous support structure. It is necessary
to have a defect free, dense, nonporous, discriminating
layer so that the oil cannot hydraulically permeate
through defects in the discriminating layer. An
advantage of having a defect free, dense, nonporous,
discriminating layer on both sides of the porous
structure is that the potential of hydraulic transport
of the oil is diminished further.


In the case of hollow fibers, the feed may contact
the membrane in the bore of the fiber, or on the outside
of the fiber. The preferred embodiment would be the one
where the liquid is fed on the outside to provide lower
operating pressure drop.
The discriminating layer, or skin, may be composed
of any family of polymers that is chemically compatible
with the feed as long as the dense, nonporous layer does
not permit the transport of the oil in substantial
quantities. The discriminating layer, or skin, is
chemically compatible with the oil if it does not
chemically react with the oil, or if its physical
properties such as size, strength, permeability, and
selectivity are not adversely affected by contact with
the oil. The dense, nonporous layer may be composed of
polymers including, but not restricted to, polymers such
as polyimides, polysulfones, polycarbonates, polyesters,
polyamides, polyureas, poly(ether-amides), amorphous
Teflon, polyorganosilanes, alkyl celluloses and
polyolefins.
The liquid may be contacted with the membrane in a
countercurrent, co-current, crossflow, or radial
crossflow configuration. The flow may be such that
either, none, or both streams {i.e., feed and permeate)
are well mixed or unmixed. The feed stream is
preferably well mixed.
The liquid stream containing the low volatility
liquid (e.g. oil) and the water may be fed into the
vessel to contact the defect-free, dense, nonporous
layer of the membrane. However, the operation of the
invention is not limited to feeding the liquid into the
vessel to contact the dense nonporous layer. The
invention may also be practiced by feeding the liquid
into the vessel to contact the membrane on the side
without the dense nonporous layer or skin.
The water partial pressure on the permeate side may
be reduced by the application of vacuum, or by the use

of a sweep gas with a low water vapor partial pressure,
such as carbon dioxide, argon, hydrogen, helium,
nitrogen, methane, or preferably air. The permeate
flow, including the sweep, is preferably in the
countercurrent, crossflow or radial crossflow mode. The
pressure of the permeate may be equal to or less than
the pressure of the feed.
Alternatively, the pressure of the permeate may be
greater than the pressure of the feed. An example of
when the pressure of the permeate is greater than the
pressure of the feed would be when the permeate is
removed by a sweep gas. The sweep gas may be comprised
of dehydrated compressed air or nitrogen such that the
pressure on the permeate side is greater than the
pressure on the feed side of the vessel. Typically in
this scenario, the activity of the high volatility
liquid being removed from the feed is locally greater on
the feed side than on the permeate side.
With membrane based oil dehydration, it is
preferable to filter the incoming fluid. Filtration may
be used to remove particulate matter or bulk water
entrained in the stream. Any of the techniques known in
the art to filter a fluid is suitable. This can prevent
the destruction of the discriminating layer by
particulate matter entrained in this stream.
In the preferred embodiment, the membrane consists
of a hollow fiber with a dense, defect-free, nonporous
discriminating layer on one or both sides of the porous
support structure. In the preferred embodiment, the
feed side boundary layer is minimized. In addition, in
the preferred embodiment, the pressure drop across the
feed side is minimized. The permeated water may be
withdrawn, from the permeate side, by means of a vacuum
or a sweep. This water will be in the vapor, or gas,
phase. The sweep may be in the form of a gas or a
liquid. In addition, the sweep may have a lower

activity for water than that of the low volatility
liquid.
This device may be applied in situations where
vacuum purifiers and other conventional dehydrators are
used. This process or device may be used to treat oil
in a "kidney-loop" system, where the oil dehydrator is
connected to a reservoir that is part of a piece of
equipment. The oil is withdrawn from the process
reservoir, processed through the dehydrator, and then
returned to the reservoir. The oil dehydrator may be
operated continuously or intermittently while the main
system is operating, or while it is at rest. This
device may also be used "off-line" to treat the fluid in
a reservoir. This reservoir is not connected to any
piece of operating equipment and serves as a container
for conditioning the fluid.
In addition to conventional applications, this
device may be used "in-line". Since the feed and
permeate spaces are separated by a dense, nonporous
barrier, it is possible to operate the device such that
the feed and permeate are at different pressures.
Consequently, the device may be operated in such a way
that the oil is at the pressure of the system in which
it is used. Consequently, this opens the possibility of
using such a device and process "in-line," which is the
preferred embodiment of this invention. The need for
conventional off-line or kidney-loop systems is reduced
and may be eliminated. Being able to use the present
invention in-line and at system pressure allows it to be
compact and lightweight and useful on virtually ail
hydraulic or lubrication equipment. It can, also, be
used on stationary or mobile equipment since additional
power; pumps and controls are not required.
Referring now to the drawings, wherein like
numerals refer to the same elements, Fig. 1 is a flat
sheet embodiment of a semi-permeable membrane 18. The
membrane 18 includes the non-porous, defect-free,


discriminating layer, or skin, 22 and the support
structure 24. The discriminating layer or skin 22 may
be present on either, or both, sides of the support
structure 24.
Referring to Figs. 13-14, a modification of the
semi-permeable membrane 18 is shown wherein the
discriminating layer or skin 22 is formed integrally
with the support structure 24 by methods known in the
membrane art. As before, the discriminating layer or
skin 22 may be present on either, or both, sides of the
support structure 24.
In Fig. 2, two flat sheet semi-permeable membranes
18 are separated by a plurality of feed channel spacers
34. The spacers 34 may be made or formed of a variety
of materials well known in the art, including potting
compounds. Each membrane 18 has skin 22 and support
structure 24. Permeate collection spacer 25, which is
constructed to prevent the feed and permeate streams
from mixing, is interposed between membrane 18 and
spacers 34. Membranes 18 are separated by feed channel
spacers 34.
Depicted in Fig. 3 is a hollow fiber embodiment of
the semi-permeable membrane 20. In this embodiment,
hollow fiber membrane 20 includes the discriminating
layer 22 and the support structure 24. The
discriminating layer may be on the inside or outside of
the fiber, or both sides of it.
Referring to Figs. 15-16, there is shown a
modification of the hollow fiber membrane 20 wherein the
discriminating layer or skin 22 is formed integrally
with the support structure 24 by methods known in the
membrane art. As before, the discriminating layer or
skin 22 may be present on either, or both, sides of the
support structure 24.
Shown in Fig. 4A is a plurality of the hollow fiber
semi-permeable membranes 20 woven into a mat 30. In
terms of weaving or web technology, the hollow fiber

membranes 20 would typically consticute the weft of the
mat 30. A plurality of fillers 28 are used to weave the
hollow fiber membranes 20 into a mat. The fillers 28
are used in the traditional sense of weaving a mat or
web.
A cross sectional view along section line B-B of
Fig. 4A is shown in Fig. 4B. The reference numerals
used in Fig. 4B indicate the same elements as previously
identified. Any weaving type process may be used to
create hollow fiber mats, provided it does not damage
the fibers.
In Fig. 4C mat 30 is shown spirally wound.
Typically, a feed channel spacer 34, such as a potting
compound 35, will have been applied proximate the ends
of mat 30, and will fill the spaces between the hollow
fibers 20, as will be discussed further below.
In Fig. 4D, two hollow fiber semi-permeable
membranes 20 are helically wound to form a "rope" 32.
In Fig. 5, a flat sheet semi-permeable membrane 1B
is spirally wound using known spiral-wound
configurations and techniques which provide for a feed
space and a permeate space in the spiral wound module.
Before spirally winding the membrane 18, a feed channel
spacer 34 was disposed on the discriminating layer 22.
More than one flat sheet semi-permeable membrane 20 may
be spirally wound at the same time. Typically, a
plurality of flat sheet semi-permeable membranes 18 will
be disposed horizontally to each other. The membranes
18 may or may not be separated by spacers 34. The
assembly of the horizontally disposed plurality of flat
sheet membranes 20 is then spirally wound on to core 60
(if used). Typically, the spiral would be wound
tighter, and the feed channel spacer 34 would contact
permeate collection spacer 25.
In Fig 6, the invention with a vacuum permeate mode
is depicted. A water containing feed 40 is introduced
to the feed side of a membrane separator vessel 42 so

that the oil is efficiently contacted with the membrane
18. The feed 40 may optionally be heated before coming
in contact with the membrane 20. The dehydrated low
volatility liquid is removed from the vessel 42 in an
effluent 44. The permeate 46 is withdrawn by means of a
vacuum pump 48. Optionally, the feed 40 may flow
parallel or perpendicular to the membrane 2 0 and the
permeate 46 may also flow parallel or perpendicular to
the membrane 20 or any combination thereof. Optionally,
the vessel 42 may be heated.
Clearly, the vessel 42 should be sized
appropriately to the desired flow rate of the feed 40,
the desired operating pressure drop, and the amount of
water to be removed. The permeate 46 is illustrated in
the crossflow configuration, but, the feed 40 and the
permeate 46 may also flow in relation to each other in
countercurrent flow, co-current flow, or radial cross
flow.
The sweep gas mode is demonstrated in Figs. 7 and 8
where there is an inlet on the permeate side of membrane
20 for a sweep fluid 50. The feed stream can be
filtered as shown in Fig. 8 by means of a filter 52.
In Figs. 9,10,11, and 12 the fluid on the bore side
of the hollow fiber 2 0 is separated from the fluid on
the shell side by means of a potting compound 34. In
Fig. 11, the oil exits by means of a perforated core 60.
The perforated core 60 is a conventional perforated core
with a housing 62 having a perforated section 64 and an
outlet 68. The perforated section includes a plurality
of perforations 66. The outlet 68 is in communication
with the effluent 44 of the vessel 42. The perforations
may be any suitable size or configuration. The liquid
of low volatility flows over the housing 62 and the
perforated section 64. The low volatility liquid enters
the housing 62 through the perforations 66. The low
volatility liquid exits the perforated core 60 through
the outlet 68.


In addition to lubricating oils, this device and
process may also be used for dehydrating other fluids,
such as vegetable or food grade oils, silicones, or
other fluids of low volatility.
The terms and expressions that have been used in
the foregoing specification are used as terms of
description and not of limitation, and there is no
intention in the use of such terms and expressions of
excluding equivalents of the features shown and
described or portions thereof. It is recognized that
the scope of the invention is defined and limited only
by the claims that follow.

WE CLAIM
1. A process for dehydration of oils, by means of a defect-free dense
nonporous membrane;
characterized in that said defect-free dense, nonporous membrane is a
composite part of a hollow fiber, with a discriminating layer supported on
a porous support, and said discriminating layer and porous support being
polymeric in nature; said dehydration process comprising the steps of:
a) contacting one side of said defect-free, dense, nonporous
membrane with a liquid stream containing free, emulsified or
dissolved water and oil, wherein the membrane divides the
separation chamber into a feed side, into which the liquid
stream is fed, and a permeate side, from which the water is
withdrawn;
b) maintaining a partial pressure differential for water such that
the water selectively permeates by "solution diffusion" through
the discriminating polymer layer from the feed side to the
permeate side as a vapor;
c) removing the water vapor that has permeated from the
permeate with a side with a sweep gas stream or vacuum;
d) preventing permeation of oil to the permeate side in the liquid
phase; and
e) removing the dehydrated oil from the feed side of the
membrane.

A process for the dehydration of low
volatility liquids, comprising the following steps:
a) contacting one side of a defect-free,
nonporous, semi-permeable membrane with a liquid
stream containing at least water and liquid of low
volatility, wherein the membrane divides a
separation chamber into a feed-side, into which the
liquid stream is fed, and a permeate side, from
which the water is withdrawn, wherein:
1) the defect-free, dense, nonporous
membrane is a composite part of a hollow fiber
wherein a defect-free, dense, nonporous
discriminating layer is supported on a porous
support; and
2) the discriminating layer and porous
support are polymeric in nature;
b) maintaining a partial pressure
differential for water such that the water
permeates through the membrane from the feed side
to the permeate side and the liquid of low
volatility cannot permeate to the permeate side by
hydraulic transport;
c) removing the water that has permeated
from the permeate side; and
d) removing the dehydrated liquid from the
feed side of the membrane.

3. A process for the dehydration of oil,
comprising the following steps:
a) contacting one side of a defect-free,
semi-permeable nonporous membrane with a liquid
stream containing at least water and oil
b) where the water is free, emulsified or
dissolved in the oil;

c) wherein the membrane divides a separation
chamber into a feed-side, into which the liquid
stream is fed, and a permeate side, from which the
water is withdrawn;
d) maintaining a partial pressure
differential for water such that the water
permeates through the membrane from the feed side
to the permeate side and the oil cannot permeate to
the permeate side by hydraulic transport;
e) removing the water that has permeated
from the permeate side; and
f) removing the dehydrated oil from the feed
side of the membrane.
4. A process as/claimed in claim 2, wherein the
low volatility liquid is oil.

5. The process as claimed in claim 2, wherein the
liquid of low volatility is defined as a liquid with a
normal boiling point greater than that of water.

6. The process/as claimed claim 2, wherein water
is present in the liquid of low volatility in the
dissolved, dispersed or emulsified form, or as a
separate phase.

7. The process as now claimed in claim 2, wherein the
defect-free, nonporous, semi-permeable membrane consists
of a dense, nonporous, self-supported layer.

8. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense, nonporous layers on a porous or
nonporous hollow fiber.



9. The. process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more, dense nonporous layers on a porous or
nonporous flat sheet.
10. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as an integral part of a hollow
fiber, the dense, nonporous layer being formed at the
same time as a support structure in the hollow fiber.
11. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as an integral part of a flat
sheet, the dense, nonporous layer being formed nominally
at the same time as a support structure in the flat
sheet.

12. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as a composite part of a hollow
fiber, the dense, nonporous layer being formed at a
different time than a support structure in the hollow
fiber.
13. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as a composite part of a flat
sheet, the dense, nonporous layer being formed at a
different time than a support structure in the flat
sheet.

14. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a support structure in a hollow fiber, the hollow fiber
having a dense, nonporous layer on one of the bore or
outside faces.

15. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a support structure in a flat sheet, the flat sheet
having a dense, nonporous layer on one of its sides.
16. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a support structure in a hollow fiber, the hollow fiber
having a dense, nonporous layer on both its bore and
outside faces.
17. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a support structure in a flat sheet, the flat sheet
having a dense, nonporous layer on both of its sides.
18. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of a dense, nonporous layer on a porous or nonporous
hollow fiber, and the liquid of low volatility is fed on
the side with the dense, nonporous layer.
19. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of a dense nonporous layer on a porous or nonporous flat
sheet, and the oil is fed on the side without the dense,
nonporous layer.
20. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense, nonporous layers on a porous or
nonporous hollow fiber, wherein the oil is fed on the
outside of the fibers.

21. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense, nonporous layers on a porous or
nonporous hollow fiber, wherein the oil is fed on the
inside of the fibers.
22. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense nonporous layers on a porous or
nonporous hollow fiber, wherein the fibers are helically
wound.
23. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense nonporous layers on a porous or
nonporous flat sheet, wherein the flat sheets are
spirally wound.
24. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense nonporous layers on a porous or
nonporous flat sheet, wherein spacers separate the flat
sheets.
25. The process as now claimed in claim 2, wherein the
liquid stream is well mixed.
26. The process as now claimed in claim 2, wherein the
liquid stream is not well mixed.
27 . The process as now claimed in claim 2, wherein the
process is in line in another system wherein at least a
part of the entire flow of the liquid of low volatility
is continually fed through the said process.
28. The process as now claimed in claim 2, wherein the
process operates as a "kidney loop" in another system
wherein a fraction of the total flow of the liquid of
low volatility is continually fed through the said
process.
29. The process as now claimed in claim 2, wherein the
process operates offline in another system, and wherein
the liquid of low volatility is fed through the said
process from a storage device.
30. The process as now claimed in claim 2, wherein the
feed flows parallel to the surface of the semi-permeable
membrane.
31. The process as now claimed in claim 2, wherein the
feed flows perpendicular to surface of the semi-
permeable membrane.
32. The process as now claimed in claim 30, wherein the
flow on the permeate side is parallel to the surface of
the semi-permeable membrane.
33. The process as now claimed in claim 30, wherein the
flow on the permeate side is perpendicular to the
surface of the semi-permeable membrane.
34. The process as now claimed in claim 31, wherein the
flow on the permeate side is parallel to the surface of
the semi-permeable membrane.
35. The process as now claimed in claim 31, wherein the
flow on the permeate side is perpendicular to the
surface of the semi-permeable membrane.
36. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense, nonporous layers on a porous or
nonporous hollow fiber, and the feed flows parallel to
the hollow fiber.
37. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense, nonporous layer on a porous or
nonporous hollow fiber, and the flow on the permeate
side is parallel to the hollow fiber.
38. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense, nonporous layer on a porous or
nonporous hollow fiber, and the flow on the permeate
side is perpendicular to the hollow fiber.
39. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense nonporous layer pn a porous or
nonporous hollow fiber, and the feed flows perpendicular
to the hollow fiber.
40. The process as now climed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense nonporous layer on a porous or
nonporous flat sheet, and the feed flows parallel to the
flat sheet.
41. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense nonporous layer on a porous or
nonporous flat sheet and the flow on the permeate side
is parallel to the flat sheet.
42. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense nonporous layer on a porous or
nonporous flat sheet, and the flow on the permeate side
is perpendicular to the flat sheet.
43. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane consists
of at least one dense nonporous layer on a porous or
nonporous flat sheet and the feed flows perpendicular to
the flat sheet.
44. The process as now claimed in claim 2, wherein the
flows on the feed side and on the permeate side are
countercurrent.
45. The process as now claimed in claim 2, wherein the
flows on the feed side and on the permeate side are co-
current.
46. The process as now claimed in claim 2, wherein the
flows on the feed side and on the permeate side are
crossflow.
47. The process as now claimed in claim 2, wherein the
flows on the feed side and on the permeate side are
radial crossflow.
48. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a porous support structure, and the porous support
structure is wetted by the liquid of low volatility.
49. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a porous support structure, and the porous support
structure is treated so that it is wetted by the liquid
of low volatility.
50. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a porous support structure, and the porous support
structure is not wetted by the liquid of low volatility.
51. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a porous support structure, and the porous support
structure is treated so that it is not wetted by the
liquid of low volatility.
52. The process as now claimed in claim 2, wherein the
permeate side is at a pressure greater than that of the
feed side.
53. The process as now claimed in claim 2, wherein the
permeate side is at the same pressure or lower than the
feed side.
54. The process as now claimed in claim 2, wherein there
is a sweep of gas or liquid through the permeate side.
55. The process as now claimed in claim 2, wherein there
is a sweep of gas through the permeate side, and said
sweep gas is selected from the group consisting of
argon, methane, nitrogen, air, carbon dioxide, helium,
or hydrogen or any mixture thereof.
56. The process as now claimed in claim 2, wherein said
there is a sweep of gas through the permeate side, and
said sweep gas has a lower activity for water than that
of the low volatility liquid.
57. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense nonporous layer, and said non-porous layer is
polymeric in nature.
58. The process as now claimed in claim 3, wherein the
defect-free, nonporous, semi -permeable membrane includes
a dense porous support, and the dense porous support is
polymeric in nature.
59. The process as now claimed in claim 2, wherein the
porous support is ceramic.
60. The process as now claimed in claim 2, wherein the
porous support is glass.
61. The process as now claimed in claim 2, wherein the
porous support is an inorganic polymer.
as claimed
62. The process as now claimed in claim 2, where the
liquid of low volatility is filtered before it contacts
the semi-permeable membrane.
63. The process as now climed in claim 2, wherein the
semi-permeable membrane consists of a plurality of
hollow fibers and the hollow fibers are woven in a mat.
64. The process as now climed in claim 2, wherein the
liquid stream is heated before contacting the membrane.
65. The process as now claimed in claim 3, wherein the
semi-permeable membrane of uniform construction consists
of a dense, nonporous, self supported layer having an
integrally formed skin.
66. The process as now claimed in claim 2, wherein said
nonporous, semi-permeable membrane has an integrally
formed skin on at least one side of the support
structure.
67. A device for the dehydration of oils
comprising:
a) a fluid-containing vessel;
b) a defect-free, nonporous, semi-permeable
membrane interposed in said vessel dividing the
interior of said vessel into at least one feed-side
space and one permeate space;
c) at least one inlet opening to the feed-
side space;
d) at least one outlet opening to the feed-
side space; and
e) at least one outlet opening to the
permeate space.
68. The device as now claimed in claim 67, wherein the
fluid containing vessel is heated.
69. The device as now claimed in claim 67, further
comprising a porous support to support said non-porous,
semi-permeable membrane.
70. The device as now claimed 69, wherein said
nonporous semi-permeable membrane has an integrally
formed skin on at least one side of the porous support.
71. The device as now claimed in claim 67, wherein said
non-porous semi-permeable membrane is polymeric in
nature.
72. The device as now claimed in claim 69, wherein said
porous support is polymeric in nature.
73 . The device as now claimed in claim 69 wherein said
porous support is ceramic.
74. The device as now claimed in claim 67, further
comprising a sweep gas inlet opening to the permeate
space.
75. The device as now claimed in claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of a dense, nonporous, self-supported layer.
76. The device as now claimed in claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense, nonporous layers on a porous or
nonporous hollow fiber.
77. The device as now claimed in claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more, dense nonporous layers on a porous or
nonporous flat sheet.
78. The device as now claimed in claim 67, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as an integral part of a hollow
fiber, the dense, nonporous layer being formed at the
same time as a support structure in the hollow fiber.
79. The device as now claimed in 67, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as an integral part of a flat
sheet, the dense, nonporous layer being formed nominally
at the same time as a support structure in the flat
sheet.
80. The device as claimed in claim 67, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as a composite part of a hollow
fiber, the dense, nonporous layer being formed at a
different time than a support structure in the hollow
fiber.
81. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane includes
a dense, nonporous layer as a composite part of a flat
sheet, the dense, nonporous layer being formed at a
different time than a support structure in the flat
sheet.
82. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane includes
a support structure in a hollow fiber, the hollow fiber
having a dense, nonporous layer on at least one of the
bore and the outside faces.
83. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane includes
a support structure in a flat sheet, the flat sheet
having a dense, nonporous layer on at least one of its
sides.
84. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of a dense, nonporous layer on a porous or nonporous
hollow fiber, and the liquid of low volatility is fed on
one of the side with the dense, nonporous layer, and the
side without the dense, nonporous layer.
85. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense, nonporous layers on a porous or
nonporous hollow fiber, wherein the oil is fed on one of
the inside and the outside of the fibers.
86. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense nonporous layers on a porous or
nonporous hollow fiber, wherein the fibers are helically
wound.
87. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense nonporous layers on a porous or
nonporous flat sheet, wherein the flat sheets are
spirally wound.
88. The device as now claimed to claim 67, wherein the
defect-free, nonporous, semi-permeable membrane consists
of one or more dense nonporous layers on a porous or
nonporous flat sheet, wherein spacers separate the flat
sheets.
A method and apparatus for the removal of free, emulsified, or
dissolved water from liquids of low volatility, such as oil, is
shown. The liquid of low volatility is removed by contacting the
fluid stream of concern with one side of a defect feed semi—
permeable membrane (18). The membrane divides a separation
chamber (42) into a feed side into which the stream of fluid (40)
is fed, and a permeate side (46) from which the water is removed.
The permeate side (46) of the chamber (42) is maintained at a
low partial pressure of water through presence of vacuum, or by
use of a sweep gas (50).

Documents:

380-kolnp-2004-granted-abstract.pdf

380-kolnp-2004-granted-claims.pdf

380-kolnp-2004-granted-correspondence.pdf

380-kolnp-2004-granted-description (complete).pdf

380-kolnp-2004-granted-drawings.pdf

380-kolnp-2004-granted-examination report.pdf

380-kolnp-2004-granted-form 1.pdf

380-kolnp-2004-granted-form 18.pdf

380-kolnp-2004-granted-form 2.pdf

380-kolnp-2004-granted-form 3.pdf

380-kolnp-2004-granted-form 5.pdf

380-kolnp-2004-granted-letter patent.pdf

380-kolnp-2004-granted-pa.pdf

380-kolnp-2004-granted-reply to examination report.pdf

380-kolnp-2004-granted-specification.pdf


Patent Number 215517
Indian Patent Application Number 00380/KOLNP/2004
PG Journal Number 09/2008
Publication Date 29-Feb-2008
Grant Date 27-Feb-2008
Date of Filing 22-Mar-2004
Name of Patentee POROUS MEDIA CORPORATION
Applicant Address 1350 HAMMOND ROAD ST, PAUL MANNESOTA 55110 USA.
Inventors:
# Inventor's Name Inventor's Address
1 SPEARMAN MICHAEL R. 2 LACEWING PLACE THE WOODLANDS, TEXAS 77380 USA.
2 BURBAN JOHN H. 9612 57TH STREET LAKE ELMO,MINNESOTA 55042 USA.
3 THUNDYIL MATHEWS 40 TEAK MILL PLACE THE WOODIANDS TX 77382 USA
4 ZIA KAJID 4695 CENTERVILLE ROAD WHITE BEAR TOWNSHIP, ,OMMESPTA 55127 USA.
PCT International Classification Number C10G33/00
PCT International Application Number PCT/US01/26501
PCT International Filing date 2001-08-27
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 PCT/US01/26501 2001-08-27 Not Applicable