EP1442100A1 - Oil dehydrator - Google Patents
Oil dehydratorInfo
- Publication number
- EP1442100A1 EP1442100A1 EP01966200A EP01966200A EP1442100A1 EP 1442100 A1 EP1442100 A1 EP 1442100A1 EP 01966200 A EP01966200 A EP 01966200A EP 01966200 A EP01966200 A EP 01966200A EP 1442100 A1 EP1442100 A1 EP 1442100A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- nonporous
- dense
- semi
- free
- defect
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G33/00—Dewatering or demulsification of hydrocarbon oils
Definitions
- 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.
- 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 that 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.
- 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.
- 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.
- 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.
- a vacuum is applied to reduce the boiling point of the water.
- the boiling point of water is 100°C (212°F) at 1013 mm H 2 0 (29.92"Hg) barometric pressure (standard atmospheric pressure)
- its boiling point at 100 mm H 2 0 is only 50°C (122°F) .
- the water in the oil will evaporate from the oil into the- low-pressure air (vacuum) , thus dehydrating the oil .
- 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.
- 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.
- vacuum dehydration oil purifiers 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 .
- 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 cuproamonium 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.
- U. S. Pat. No. 5,182,022 to Pasternak et al discloses a pervaporation process for the dehydration of ethylene glyco ' l .
- 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.
- Friesen et al postulates that the process can be used to dehydrate oils such as sesame oil and corn oil.
- 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.
- 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. 6,001,257 to Bratton et al discloses a zeolite membrane that is substantially defect-free for the purpose of dehydration of various liquids .
- 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.
- “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 that 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.
- a non-porous membrane is not necessarily defect free.
- 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.
- Pinnau and Koros 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.
- 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.
- the presence of the defects merely reduces the efficiency of the separation but does not render the module commercially unviable.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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 .
- 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.
- 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.
- 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.
- the present invention is involved in the separation of water from oil .
- the process of dehydrating the oil consists of the following steps: contacting one side of a on-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 corresponding 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.
- the discriminating layer may be self-supporting; however, this is not required to practice the invention.
- 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 .
- 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.
- 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.
- 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.
- the oil 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.
- 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.”
- 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.
- suitable membranes include 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.
- 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.
- 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 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 those specified conditions. This ratio is called the intrinsic selectivity of the p . olymer to the specified gas components.
- 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 .
- 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.
- 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.
- 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.
- 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.
- the porous support structure is of such a nature that the low volatility liquid does not . wet the structure.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- the activity of the high volatility liquid being removed from the feed is locally greater on the feed side than on the permeate side.
- 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.
- 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.
- the feed side boundary layer is minimized.
- 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.
- 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.
- this device maybe 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 all • hydraulic or lubrication equipment. It can, also, be used on stationary or mobile equipment since additional power; pumps and controls are not required.
- 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.
- 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.
- 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.
- 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.
- the discriminating layer or skin 22 may be present on either, or both, sides of the support structure 24.
- FIG. 4A Shown in Fig. 4A is a plurality of the hollow fiber semi-permeable membranes 20 woven into a mat 30.
- the hollow fiber membranes 20 would typically constitute. 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.
- FIG. 4B 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.
- 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.
- Fig. 4D two hollow fiber semi-permeable membranes 20 are helically wound to form a "rope" 32.
- a flat sheet semi-permeable membrane 18 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 .
- 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.
- 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) .
- the spiral would be wound tighter, and the feed channel spacer 34 would contact permeate collection spacer 25.
- 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.
- the feed 40 may flow parallel or perpendicular to the membrane 20 and the permeate 46 may also flow parallel or perpendicular to the membrane 20 or any combination thereof.
- the vessel 42 may -be heated.
- 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.
- the fluid on the bore side of the hollow fiber 20 is separated from the fluid on the shell side by means of a potting compound 34.
- 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.
- this device and process may also be used for dehydrating other fluids, such as vegetable or food grade oils, silicones, or other fluids of lo volatility.
Abstract
Description
Claims
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2001/026501 WO2003018719A1 (en) | 1999-05-27 | 2001-08-27 | Oil dehydrator |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1442100A1 true EP1442100A1 (en) | 2004-08-04 |
EP1442100A4 EP1442100A4 (en) | 2005-07-27 |
Family
ID=32467097
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01966200A Withdrawn EP1442100A4 (en) | 2001-08-27 | 2001-08-27 | Oil dehydrator |
Country Status (12)
Country | Link |
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EP (1) | EP1442100A4 (en) |
JP (1) | JP2005501168A (en) |
KR (1) | KR100864674B1 (en) |
CN (1) | CN1318545C (en) |
AU (1) | AU2001286733B2 (en) |
BR (1) | BR0117116A (en) |
CA (1) | CA2458957A1 (en) |
EA (1) | EA006273B1 (en) |
HK (1) | HK1072068A1 (en) |
MX (1) | MXPA04001895A (en) |
NO (1) | NO20041278L (en) |
UA (1) | UA77436C2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114618321A (en) * | 2020-12-11 | 2022-06-14 | 中国科学院大连化学物理研究所 | Hollow fiber membrane, preparation and application in hydraulic oil degassing |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
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US7429166B2 (en) * | 2005-12-20 | 2008-09-30 | General Electric Company | Methods and apparatus for gas turbine engines |
US8318023B2 (en) * | 2009-09-28 | 2012-11-27 | GM Global Technology Operations LLC | Heated air assisted membrane separation of water and fuel from engine oil in an internal combustion engine |
CN101914399B (en) * | 2010-07-02 | 2013-08-07 | 江南大学 | Method for preparing emulsified fuel by utilizing high-molecular hollow fiber porous membrane |
CN103409228B (en) * | 2013-07-22 | 2015-01-07 | 吴东顺 | Making process of Gaoligong mountain ancient tea oil |
CN103762005B (en) * | 2014-01-22 | 2016-05-11 | 清华大学 | A kind of distillation device for nuclear industry concentrate decrement |
CN105688672A (en) * | 2014-11-26 | 2016-06-22 | 安徽智新生化有限公司 | Membrane dewatering device |
CN104914233A (en) * | 2015-06-29 | 2015-09-16 | 成都迈斯拓新能源润滑材料有限公司 | Method for evaluating regeneration feasibility of conduction oil online |
FR3060410B1 (en) * | 2016-12-21 | 2019-05-24 | Technologies Avancees Et Membranes Industrielles | TANGENTIAL FLOW SEPARATION ELEMENT INTEGRATING FLEXIBLE CHANNELS |
CN108514758B (en) * | 2018-06-11 | 2024-03-01 | 广东德诚化学技术有限公司 | Super-gravity water reducer dehydration equipment and water reducer dehydration method |
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EP0470699A1 (en) * | 1990-08-06 | 1992-02-12 | Texaco Development Corporation | Membrane process for dewatering lube oil dewaxing solents |
US5334314A (en) * | 1989-12-01 | 1994-08-02 | Deutsche Carbone Ag | Composition membrane for separating water from fluids containing organic components by means of pervaporation |
WO2000072948A1 (en) * | 1999-05-27 | 2000-12-07 | Porous Media Corporation | Oil dehydrator |
WO2001080982A1 (en) * | 2000-04-19 | 2001-11-01 | Porous Media Corporation | Oil dehydrator |
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DE3610011A1 (en) * | 1986-03-25 | 1987-10-08 | Geesthacht Gkss Forschung | METHOD FOR SEPARATING THE COMPONENTS OF A LIQUID MIXTURE |
US4857081A (en) * | 1987-10-15 | 1989-08-15 | Separation Dynamics, Inc. | Separation of water from hydrocarbons and halogenated hydrocarbons |
US4944882A (en) * | 1989-04-21 | 1990-07-31 | Bend Research, Inc. | Hybrid membrane separation systems |
US5041227A (en) * | 1990-10-09 | 1991-08-20 | Bend Research, Inc. | Selective aqueous extraction of organics coupled with trapping by membrane separation |
JPH0768134A (en) * | 1993-06-29 | 1995-03-14 | Ube Ind Ltd | Method for removing moisture in oil |
US5464540A (en) * | 1993-12-09 | 1995-11-07 | Bend Research, Inc. | Pervaporation by countercurrent condensable sweep |
-
2001
- 2001-08-27 AU AU2001286733A patent/AU2001286733B2/en not_active Ceased
- 2001-08-27 CA CA002458957A patent/CA2458957A1/en not_active Abandoned
- 2001-08-27 EA EA200400347A patent/EA006273B1/en not_active IP Right Cessation
- 2001-08-27 CN CNB018237428A patent/CN1318545C/en not_active Expired - Fee Related
- 2001-08-27 MX MXPA04001895A patent/MXPA04001895A/en active IP Right Grant
- 2001-08-27 UA UA2004032222A patent/UA77436C2/en unknown
- 2001-08-27 KR KR1020047002974A patent/KR100864674B1/en not_active IP Right Cessation
- 2001-08-27 EP EP01966200A patent/EP1442100A4/en not_active Withdrawn
- 2001-08-27 JP JP2003523570A patent/JP2005501168A/en active Pending
- 2001-08-27 BR BR0117116-0A patent/BR0117116A/en not_active Application Discontinuation
-
2004
- 2004-03-26 NO NO20041278A patent/NO20041278L/en not_active Application Discontinuation
-
2005
- 2005-06-13 HK HK05104928A patent/HK1072068A1/en not_active IP Right Cessation
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US5334314A (en) * | 1989-12-01 | 1994-08-02 | Deutsche Carbone Ag | Composition membrane for separating water from fluids containing organic components by means of pervaporation |
EP0470699A1 (en) * | 1990-08-06 | 1992-02-12 | Texaco Development Corporation | Membrane process for dewatering lube oil dewaxing solents |
WO2000072948A1 (en) * | 1999-05-27 | 2000-12-07 | Porous Media Corporation | Oil dehydrator |
WO2001080982A1 (en) * | 2000-04-19 | 2001-11-01 | Porous Media Corporation | Oil dehydrator |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114618321A (en) * | 2020-12-11 | 2022-06-14 | 中国科学院大连化学物理研究所 | Hollow fiber membrane, preparation and application in hydraulic oil degassing |
CN114618321B (en) * | 2020-12-11 | 2023-07-25 | 中国科学院大连化学物理研究所 | Hollow fiber membrane, preparation and application thereof in hydraulic oil degassing |
Also Published As
Publication number | Publication date |
---|---|
CA2458957A1 (en) | 2003-03-06 |
AU2001286733B2 (en) | 2008-07-10 |
EA006273B1 (en) | 2005-10-27 |
EA200400347A1 (en) | 2004-08-26 |
CN1558941A (en) | 2004-12-29 |
JP2005501168A (en) | 2005-01-13 |
EP1442100A4 (en) | 2005-07-27 |
HK1072068A1 (en) | 2005-08-12 |
BR0117116A (en) | 2004-09-28 |
MXPA04001895A (en) | 2004-06-15 |
UA77436C2 (en) | 2006-12-15 |
CN1318545C (en) | 2007-05-30 |
KR20040039312A (en) | 2004-05-10 |
KR100864674B1 (en) | 2008-10-23 |
NO20041278L (en) | 2004-03-26 |
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