MXPA99003181A - Solvent extraction process - Google Patents

Abstract

In a solvent extraction process for the extraction of an extractive from extractive-containing material employing in an extraction zone operating under extraction conditions a process solvent, whereby a miscella comprising a portion of the process solvent and a portion of the extractive, and an extractive-depleted substrate is formed, the improvement to which comprises:(a) removing the miscella from the extraction zone under extraction conditions;(b) filtering the miscella by use of microfiltration, an ultrafiltration, a nanofiltration, or a reverse osmosis membrane, under conditions which achieve a differential pressure across said membrane, to separate the solvent in the miscella from the extractive in the miscella;and (c) recycling under extraction conditions at least a portion of the separated solvent to the extraction zone.

Description

SOLVENT EXTRACTION PROCESS TECHNICAL FIELD This invention relates to the extraction of lipid solvents from plant and animal materials, as well as to organic substances from waste streams containing organic substances to produce a permeate-rich stream in recyclable solvent, a stream that it contains the retentate rich in extractive, and a substrate stream with decreased extractive substance.

ANTECEDENTS OF THE TECHNIQUE For purposes of this invention, the term "extraction conditions" is defined as those temperatures and pressures necessary for a C3 or C4 hydrocarbon to normally exist as a liquid.A "process solvent" is defined as one or more C3 hydrocarbons or C4 normally gaseous that can be converted to a liquid under extraction conditions An "extractive" is defined to include lipids and / or lipid constituents, and / or any other organic compound that is soluble under extraction conditions in a solvent The use of solvents to extract specific compounds from feeds is well known.Some of the most commercially developed uses of solvent extraction can be found in the oil refining industry, the chemical processing industry, and the food industry, in the chemical processing and petroleum refining industries, the solvents are used to treat certain waste streams carrying organic substances, such as water / oil emulsions, waste sludge, oily sludge from refinery operations, sludge from the bottoms of storage tanks, and the like, to remove these organic substances, before unloading, recycling or the subsequent refining treatment of the stream. In such processes, it is recognized that many compounds are gases at normal environmental pressures and temperatures that can be converted to critical or near supercritical fluids by subjecting them to pressures and temperatures near or above the critical limits, and the resulting fluid can have solvent properties , particularly for organic materials. One such recognized compound is propane. Examples of such processes and process equipment are described in US Patents Nos. 4765257, 4770780, 4848918, and 4877530. In the food industry, lipids include various waxes (more particularly long chain carboxylic acids and alcohols). long chain constituents), oils and fats (more particularly, triglycerides), found in plants and animals, are extracted commercially through the use of solvent extraction processes. Particular feeds include oliferous plant materials (beans and peanuts), which include oily seeds (soybeans, cotton, linseed, peanuts, palm ani, coconuts and cocoa seeds), oily seed products (cocoa liquor), bran of cereal and fruits as well as animal meats, and even cooked plant and animal materials. In many cases, both the lipids extracted as well as the feed with eliminated lipina, are valuable products that are used in the cooking, feeding of animals, cosmetics, lubricants, insecticides and fungicides.

Commonly, the primary recovery of the oils of the seeds and the vegetal matter is completed by crushing and, if the oil content is high, by means of the pressure of the oleiferous material in a suitable machinery to eliminate a portion of the oils. However, such pressures lead to a large fraction of the oils in the press forming a cake. For example, after compression of the cottonseed oil, approximately 10% to 15% of the oil in the seeds remains pressed into the cake. Typically, a suitable solvent extraction process is used to recover the residual oil from the press cake. Oil extraction processes are also used to remediate waste streams and oil contaminated soil. In the present, hexane is the solvent most commonly used commercially in the food industry. Hexane, and other C5 + hydrocarbons, have been preferred because they are liquid at environmental temperatures and pressures which makes them safe and easy to operate in low pressure, low cost and relatively simple equipment. Thus, oil-containing materials can be transported continuously in and out of the extraction zone so that hexane extraction processes can be easily adapted to continuous processes that can scale to high production volumes and cause processes are more cost effective than batch processes. In addition, hexane is generally safer than many of the hydrocarbon solvents in C3 and C4 that can be explosive when mixed with air. This has been one of the main reasons that hexane has been in the past the more preferred solvent than propane and that potentially similar explosive solvents. In general, hexane has proven to be an economical and effective solvent. Processes with hexane effectively remove fat and oil from animal and plant substrates over a wide range of fat and oil concentrations and reduce the residual fat and oil content in substrates to relatively low levels, typically less than 1 % in weigh. However, extraction processes that use hexane or other C5 + liquid hydrocarbons as the extraction solvent have significant disadvantages. Many C5 + hydrocarbons are now recognized to be toxicologically harmful even at low concentrations when ingested by humans and animals. For this reason, the content of residual hydrocarbons in edible fats and oils and in the solid substrates containing low fat and oil content produced by the extraction processes must be reduced to extremely low levels in order to meet the health standards. The removal of solvents from extracted fats and oils, as well as the matter of plants and animals with low content of fats and oils, is usually completed by distillation, thermal instantaneous evaporation, or separation techniques. Because C5 + hydrocarbons have relatively low volatilities and strong affinity for extracted fats and oils, as well as substrates with low fat and oil content, severe separation techniques and conditions and relatively high temperatures must be used to separate the residual solvent . In many cases, these severe conditions degrade and diminish the important quality characteristics such as color, taste and digestibility of both fats and extracted oils and solids with low content thereof, and thus reduce their value economic. In addition, even when severe separation conditions and high temperatures are used, it is often not possible to reduce the C5 + hydrocarbon concentrations in the products to acceptably low safe values. For example, it has been reported that the residual hexane content of the solid residues of the rape seed extracts can not be reduced below about 0.2% hexane by weight, which is unacceptably high, even using separation conditions. that approach the thermal decomposition of the rapeseed. To overcome the problems with C5 + solvents, there is a strong will to use certain normally gaseous C3 and C4 hydrocarbon solvents, particularly propane, which can be more easily separated from extractive and low extractive feeds. These solvents are generally gaseous at ambient temperatures and pressures, and therefore, achieve the desired extraction of the oil that must be introduced into extraction vessels under conditions of pressure and temperatures that convert them into liquids. However, the potentially explosive characteristics and the need to operate under pressurized systems cause such liquefied solvent extraction processes to require energy and relatively high capital equipment costs. For example, in a typical propane extraction process, the materials that carry the extractive and propane are contacted in a pressurized, sealed vessel that is operated under conditions to keep the propane as a liquid. The resulting mixture highly rich in extractive substance comprising the extractive substance and a small portion of the liquid propane are separated from the substrate with low content of extractive substance. In these prior art processes, the propane is then separated from the mixture for the purpose of recycling the propane back into the extraction vessel. In the present commercial operations, this separation is performed outside the extraction vessel by distillation and / or flash evaporation of the solvent outside the solvent-rich permeate stream. These separation stages require the introduction of heat into the process which generates energy costs. The amount of heat needed depends on the solvent and the amount of the solvent to be heated. Once the solvent is separated from the extractive substance, it will be recycled for use in the extraction vessel. However, liquid solvents that have been reverted to their gaseous state normally during the separation operation must be re-cooled and pressurized back to a liquid before they are recycled to the extraction vessel. This stage introduces even more energy costs to the process. However, the non-re-use of the solvent would return to the less economical process. In industries with large volumes, such as oil refining, chemical processing, and food processing, even a small percentage of energy savings translates into large economic savings. Examples of such processes and process equipment are illustrated in US Patent Nos. 1802533, 1849886, 2247851, 2281865, 2682551, 2281865, 2538007, 2548434, 2560936, 2564409, 2682551, 2727914, 3261690, 3565634, 3923847, 3939281, 3966981, 3966982, 4331695, 4617177, 4675133, 5041245, 5210240, 5281732, 5405633, 5482633 and 5525746. As reported in SS Kóseoglu et al. Membrane Processing of Crude Vegetable Oiis: Pilot Plant Scale Removal of Solvent from Oil Miscellany, JACCS, Vol. 67, no. 5 (May 1990), the research was conducted by the Food Protein Research and Development Center, Texas A & amp;; M University, where the separation with membranes of a mixture of solvent and oil formed during an extraction process with hexane, ethanol or isopropanol has been used to try to separate the solvent from the extracted oil. This research indicated that trials in a pilot plant for satisfactory separation of hexane was not successful with hollow fiber membranes, but polyamide membranes could be acceptable when the solvent used is hexane. It was also reported that the flows achieved during the separation were increased by the increase in temperature and pressure and decreased with the increase in oil concentration in the mixture. Due to the above reasons, the need for a solvent extraction process that uses a liquified solvent so that the concentration of the residual solvent in the extractive substrate or the extractive substance and exhausted with the extractive substance is reduced to low and safe levels without the degradation of the products; what can be effectively adapted in a costly manner to the continuous operation that requires a continuous feeding of material that carries extractive substance in the extraction zone and the continuous elimination of the permeate rich in liquified solvent and the substrate depleted with extractive substance from the zone of extraction. extraction; and that it reduces energy costs the capital needed to recycle the liquified solvent to be used in the process. Another difficulty with the present solvent extraction processes is the need to use multiple stages as well as additional equipment to achieve the separation of the various compounds that are extracted, such as light gums and waxes from the oils that are extracted. The ability to achieve such separation in a single stage or container would be significant in the food and pharmaceutical industries. These and other objects and objectives of this invention will become apparent from the following descriptions of the invention.

DESCRIPTION OF THE INVENTION Applicants have discovered that the objects of this invention can be achieved through the use of a solvent extraction process wherein the mixture of solvent and oil formed during the extraction step is filtered under extraction conditions to form (a) a permeate rich in process solvent that is substantially free of extractive substance and that can be recycled directly to the extraction zone without further processing, and (b) a retained substance rich in extractive substance that is usually free of solvent, and that requires substantially less energy and a reduced amount of equipment to satisfactorily separate the solvent from the process of the retained substance rich in extractive substance. In a preferred embodiment, the present invention is directed to a process for extracting lipids from animal and plant materials that contain lipids, using a process solvent as the extraction solvent. The most preferred solvent is propane. The lipid-bearing material is treated with the liquid solvent in an extraction vessel to form a mixture of solvent and oil and a substrate depleted with lipids. While the extraction conditions are maintained, the mixture is passed through microfiltration, ultrafiltration, nanofiltration or reverse osmosis membranes, suitable for forming a permeated substance rich in the process that is recycled directly back to the extraction zone without having to go through a thermal vaporization, a compression cycle and - condensation, and a stream of retained substance rich in lipids. The lipid-rich retained substance of the stream is then subjected to additional conventional treatment, such as thermal separation or distillation, to separate and recover the remaining solvent that is in the lipid-rich retained substance stream. This separate solvent vapor can then be compressed, condensed and recycled to the extraction zone to minimize any requirement to add replenishing process solvent. The separated lipids can then be recovered and sold as a separate commercial product. Separately, the lipid-depleted substrate is subjected to an appropriate thermal separation operation to separate the solvent from the residual process off the substrate. The solvent vapor separated from the substrate can then be compressed, condensed and recycled to the extraction zone. The remaining substrate material or cake can be recovered and sold as a second separate commercial product. Due to the large volume of process solvent that is removed during the filtration step, less material must be moved through the subsequent separation, compression and condensation steps, resulting in substantial energy savings. For the same reason, smaller separation, compression, condensation and distillation units need to be employed for the "processing of the same amount of feed in an extraction solvent with conventional solvents." Accordingly, such filtration separation techniques are very effective in the operation and capital cost and energy efficient In another aspect of the invention, the operating conditions in the extract vessel (such as the flow rate of the feed, the speed of the flow of the solvent, the used solvent, temperature, pressure, perfection of mixing of feed and solvent, etc.) is controlled to allow the extraction of a first extractive substance, such as oils, from the feed before the extraction of a second extractive substances, such as gums, waxes, or other compounds in the diet, in this modality, the remnants of the The amount that is extracted in the extractor vessel is sufficiently separated to allow selectivity only in the desired extracting substance to exit through a particularly designed outlet. Other aspects of the present invention are directed to adapt the process to a continuous operation. The process is preferably operated continuously to be cost-effective on a large scale, with high volumes of operation. The continuous operation is completed using a continuous extractor comprising a boring screw conveyor in a pressure sealed vessel operated under extraction conditions and containing the process solvent. Under pressure, the materials containing the extractive substance are continuously fed to the feeding end of the boring screw. The boring screw transports the materials through the extraction zone. The process solvent is dripped or sprayed onto the materials from one or more points and flows down through the materials by gravity. The boring screw mixes and removes the materials providing an effective contact between the process solvent and the materials that carry the extractive substance to promote an extractive substance of the extractive substance of the materials to form a mixture. The mixture of solvent and oil is collected in the lower part of the extractor. The lower part of the extractor is comprised of porous surfaces through which the mixture is extracted from the extractor. The pores of the porous surfaces are sized to allow the passage of the mixture, but to retain the depleted materials of the extractive substance in the extraction zone. The mixture is passed under extraction conditions through the filtration membranes and the process continues as set above. The boring screw conveyor transports the depleted materials with extractive substance out of the extraction zone. In a preferred embodiment, the boring conveyor or extractor will be constructed in such a manner that the material depleted with the extractive substance is compressed to remove any mixture trapped in the material. This can be complemented in a mode where the boring conveyor screw includes a number of compaction screw harrows at its outer end which. co prime the mixture outside the materials depleted with active substance before the discharge of the extractor materials. It is also preferred that the compaction screw dies form a seal with a screw barrel that prevents the flow of vapor from the exhaust solvent. In a second embodiment, the extraction vessel is constructed having a discharge end formed in the shape of a truncated cone which, with a screw of constant diameter, will similarly press the mixture out of the materials depleted with extractive substance. In another preferred embodiment, a device for measuring the content of the substance it extracts is placed to measure the extractive substance contained in the substrate. The measuring device is preferably electronically connected to a controller that controls the drive device such as a hydraulic motor that controls the speed at which the conveyor moves the feed through the extraction vessel. In this way, an optimum flow velocity of the feed can be obtained through the extraction zone for any pre-determined level of the allowable extraction content in the substrate. The material containing the extractive substance has a large physical structure which for economic reasons can not be compressed or ground, then it was preferred that the continuous extractor comprises a moving belt conveyor or a moving belt conveyor with spacers mounted on the strap to keep the material that contains the extractive substance. In this embodiment, the belt or separators would be provided with openings that allow only the mixture to drain to the bottom of the extraction chamber where they can be collected and directed towards the filtration membrane. Another aspect of this invention is directed to the continuous operation that generates problems in the continuous feeding of materials that take the extractive substance to the extractor, which contains a process solvent, such as propane. With the use of propane as the process solvent, a certain amount of propane vapor appears to be present under extraction conditions. Therefore, it is preferable to prevent air from entering the extractor vessel to avoid the formation of an explosive oxygen / propane vapor mixture in the extractor vessel. Two methods have been designed for the continuous feeding of the materials that carry the extractive substance to the extraction zone. One method is to employ two or more pressurized alternative hoppers in a sequential purge / air charge operation that alternates between the hoppers. Another system is to form a paste or suspension that can be pumped from suspension of materials that carry the extractive substance to the extractive substance to be extracted and to pump the pulp or suspension in the extractor. Similarly, another aspect of this invention addresses the problem of discharging depleted materials with the extractive substance without releasing the process solvent vapor from the extractor. Two alternative ways to overcome this problem are described. One way is to use a system of pressurized alternative hoppers similar to the material feed system. Alternatively, the extractor may comprise a compaction ring that receives the depleted materials with the extractive substance. This screw transports the depleted materials with the extractive substance out of the extractor while maintaining a seal against the flow of solvent vapor from the process outside the extractor. Still another process of the present invention pertains to milling or grinding, under conditions of extraction of the materials that carry the extractive substance into particles having an optimum size for the extraction of the solvent to avoid the commercial degradation of the materials exhausted with the substance. extractive resulting. A further aspect of this invention is the use of a sampling assembly insertable into the substrate flow coming out of the extractor for the purpose of capturing a sample of the substrate to be tested for the amount of substance it extracts in the substrate. Yet a further aspect of this invention is to use the results of the tests to optimize the flow rate of the feed material through the extractor. These and other features, aspects and advantages of the present invention are presented in the following description, appended claims and accompanying drawings.

DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic drawing of the combination of the equipment and the material flow process of a preferred embodiment of this invention. Figure 2 is a schematic drawing of the combination of the equipment and the continuous flow process of the material of another preferred embodiment of this invention that also provides for the grinding or milling of the feedstock and the partially treated feedstock under extraction conditions. Figure 3A is a cross-sectional view of a preferred embodiment of the extraction chamber 1 and 2 using a conveyor screw that has graduated diameter screws and the screen separator of mixed materials / oil. Figure 3B is a cross-sectional view of line 1-1 of Figure 3A. Figure 3C is a cross-sectional view of another preferred embodiment of the extraction chamber of Figures 1 and 2 using an extractor constructed with a truncated cone-shaped discharge end, a conveyor screw and a screen separator of materials exhausted with a mixture / oil. Figure 3D is a perspective view of an alternative embodiment of the extractor having a measurement assembly of the extracted substance attached to receive the substrate as it leaves the outlet opening in the extractor. Figure 3E is a cross-sectional view of a type of sample holder used with the de-metering assembly of the substance that is removed as shown in Figure 3D. Figure 3F is a cross-sectional view taken along lines 2-2 of Figure 3E. Figure 4 is a schematic drawing of the combination of the equipment and the material flow process of a preferred embodiment of the invention useful for treating rags and articles of clothing. Figure 5 is a side view of an alternative embodiment of a conveyor illustrating the use of a moving belt conveyor and alternatively with mounted hoppers, which can be used to move the material carrying the extractive substance through the zone of extraction.

Figure 5A is a top view of the conveyor system of Figure 5.

BEST WAY TO CARRY OUT THE INVENTION The feedstocks that can be treated during the process of this invention are varied, and include any material that carries the extractive substance. Depending on the structure and physical form of the material, the need to decrease the size of the material before or during processing, or the need for adequate physical treatment of the material during the extraction process, the type of the extraction reactor used may vary. Preferred embodiments of the invention illustrated in Figures 1, 2, and 3A-3F will be described using oleaginous plant or animal materials, while solid materials that must be handled carefully and that are not easily or desirably transported by a boring screw such as towels and clothing, will be used to describe the preferred embodiments of the invention, illustrated in Figures 4, 5A and 5B. With certain materials it is desirable first to break the cellular structure in which the extractive substance is contained. For example, the seeds often tend to be disheveled, peeling, broken and in the form of flakes. In addition, it may be desirable to require reducing the size of such materials to fine flakes, granules or particles either to achieve the desired commercial size or to increase the exposed surface area to increase the solvent exposure of the process. In one embodiment of this invention, the preparation and reduction of the particle size can be complemented by any conventional method now used for the feedstock being processed. However, in a new preferred embodiment illustrated in Figure 2 discussed below, the decrease in size is carried out under extraction conditions, and more preferably, in the presence of the solvent of the selected process. Typical extraction conditions include temperatures ranging from about room temperature to about 140 ° F, and pressures ranging up to 200 psig. Some crude oleaginous materials, such as cocoa beans, are difficult to grind up to a particle size distribution that can be extractable. These materials express their oil to form a paste before they are finely granulated. The solid in this paste form can not be effectively ground and is difficult to transport and handle. For these materials it is difficult to grind and extract the materials in two or more stages wherein the oleaginous solid is first ground or crushed, more preferably under extraction conditions, for a size that does not result in. the formation of a paste. This material can then be treated with a process solvent in the manner described below to remove the oil, and then the material partially depleted with oil can then be milled, again preferably under the extraction conditions. Turning now to Figure 1, the feed comprising material from animals or plants carrying lipids is first fed to a belt conveyor 1 in a first feed hopper 2. If desired, the feed material can be introduced into a hopper 2 as a suspension. The hopper 2 is sealed and the air is preferably removed by conventional vacuum formation or replacement techniques and is vented through the vent line 3. The hopper 2 is then pressurized with an inert gas, or preferably with the process selected in its vapor state, which is introduced into the hopper 2 by the line 4. In a preferred embodiment, the vaporized process solvent will be obtained from the distillation column 43 as described below. This preferred embodiment reduces the amount of inert materials in the system which ultimately reduces the amount of process solvent loss that occurs when the inert gases are vented or removed from the system. This modality also has the benefit of accelerating the process because the air can be removed more easily at this stage of the process than at any other stage of the process. In addition, this mode minimizes the potential safety problem associated with mixing air and volatile solvents such as propane. The valve 5 is then opened to allow the lipid-containing material to flow into the extraction vessel 6. The valve 5 can be any full-opening valve that is bubble-proof, such as the ball valve. The extraction vessel 6 is maintained at temperature and pressure conditions that allow the solvent to remain in the liquid state.

The extraction vessel 6, as illustrated in Figure 3A, will preferably be constructed having side and end walls 6 and 8, respectively, forming an elongated, horizontal tubular chamber 9, in which a boring screw conveyor 10, helical , rotatable, is operatively mounted on the walls 8 of the opposite end. The feed material is passed through the valve 5 into the chamber 9 through the flange 11 located at one end of the chamber 9 and fed into the screw conveyor 10. The upper half of the side wall 7 is provided with a series of process solvent inlets 12 preferably extending along the length of the chamber 9, but ending sufficiently in front of the outlet 13 of the lipid-depleted substrate. to prevent the excess process solvent from coming out at the outlet 13. The process solvent is sprayed or drips onto the feed material as it is transported through the chamber 9 by the screw conveyor 10. Although the inlets 12 of the process solvent are illustrated as being placed directly above the conveyor 10, they can be placed in any location that allows sufficient contact of the process solvent with the feed material to remove the desired amount of the oil or other substances that they are extracted from the feeding material. The lower half of the side wall 7 is constructed having a series of outlets 14 with a screen or screen positioned along the length of the chamber 9 that are designed in size to allow the mixture of solvent and oil to pass through. they, but that are too small to allow the passage of any substantial portion of the substrate exhausted with lipid. The pore size of the outlets 14 with screen for most streams with feedstock, such as oleaginous material, is set from 0.1 to 10 microns. The lower half d of the side wall 7 is constructed having an outlet 13 located at the opposite end of the chamber 9 of the rim 11 to allow the oil-depleted substrate to be removed from the chamber 9 by the screw conveyor 10. In a more preferred embodiment, the screw conveyor 10 is a built-in boring type, with a central arrow 15 whose diameter - increases along the horizontal central axis of the chamber 9 that starts at the rim 11 and ends at the exit 13. The region in the container 6 containing the increased diameter section of the arrow or shaft 15 is referred to as the compression zone. In this embodiment, the mixture that has not been drained from the lipid-depleted substrate can be pressed out from the substrate before the substrate is removed from the chamber 9. In a more preferred embodiment, the increase in diameter of the shaft or arrow it does not start increasing until the midpoint of the camera axis and more preferably does not start until the last third of the camera axis. In these preferred embodiments, it is easier to treat more lipid-containing material in the chamber 9. Spiral screws 16 are mounted on the shaft 15, the spacing of which increases along the length of the shaft or shaft 15, and more preferably starts to increase as the screw 16 approaches the outlet 13 of the substrate. In yet another preferred embodiment, the screws 16 will have a diameter when mounted on the shaft or arrow 15 to position its edge 17 extending adjacent to the interior surface of the side wall 7 to better control the flow of material through the chamber 9 and to prevent the outlets 14 of the sieved mixture from easily clogging with the lipid-depleted substrate. Operationally fixed in a conventional manner, on the shaft 15 is the motor 18 that can be pneumatically operated, hydraulically operated, or otherwise conventionally driven, to rotate the shaft or arrow . The motor 18 is located in the housing 19 of the extraction vessel attached to one of the end walls 8. In a preferred embodiment, the motor 18 will be a variable speed motor having a conventional electronic controlled assembly operatively contacted thereto to allow the revolutions per minute of the conveyor shaft to vary as desired. This embodiment is particularly useful when used with the oil content measurement assembly described below. The housing 19 will be provided with the fluid couplings necessary to control the flow of fluid to and from the engine 18 which is operated in a conventional manner. In an alternative embodiment illustrated in Figure 3B, the desired distance between the outlets 14 of the array and the edge 17 of the axis can be achieved by constructing the outlets 14 of the screen or screen in a manner that allows them to be vertically adjustable. The advantage of this modality is the reduction in the cost of capital through the use of perforators designed in conventional size, as well as to allow an easier adjustment that may be necessary due to manufacturing errors in the extraction chamber. In this embodiment, the screen or screen 14a is mounted on top of a support structure 14f. The support structure 14f is adopted to be adjusted vertically to allow the upper surface of the screen 14a to be positioned in a substantial manner allowing flow with the inner surface of the side wall 7. The mechanism for achieving the desired vertical adjustment can include a lateral wall 14f of the screw-retained support structure that can be screwed into the cavity of the outlet 14, as well as any other known similar arrangement. If the length of the vertical adjustment is not large, then the insertion collars 14c can be used as shown in Figures 3B and 3C. In this preferred embodiment, a sufficient number of thin collars 14c fit between the lower flange 14d of the outlet 14d and the outlet 14 and the lower flange 14c of the support structure 14f to achieve the desired adjustment in the height of the screen or sieve. The bolts 14 are then used to secure the collars 14c between the flanges 14d and 14e to fix the position of the shield 14a. It is also illustrated in Figure 3C in an alternative embodiment wherein the extraction vessel 6 is constructed so that the chamber 9 is shaped to have a truncated cone-shaped discharge section 9a that forms the compression zone. This modality has several advantages. First the surface 6a of the lower wall in the form of a slope forms a natural drainage path for the mixture of solvent and oil that will be compressed out of the spent material with the extractive substance before discharge. Second, it allows for easier placement of the screen outputs 14 to ensure passage of all of the mixture in the chamber 9. Third, it reduces the possibility of the mixture coming out through the outlets 13 of the oil-depleted substrate. As before, the material depleted with the extractive substance will be compressed as it enters the discharge section 9a due to the reduced volume. The amount of compression can be controlled by the flow velocity of the material through the extraction chamber 9 or the amount of the volume reduction in the discharge section 9a. In another embodiment of this invention, the outputs 14 are spaced apart a sufficient distance to allow selective removal of the different extractive compounds. It has been found that under extraction conditions, the oils contained in certain feedstocks will be extracted before other components, such as gums and waxes. By controlling the extraction conditions (flow velocity of the feed material, propane contact speed), etc.) oils contained in certain feedstocks, such as leaflets, will be extracted earlier than other compounds, such as gums and waxes. By proper spacing of the outlets 14 in the extractor vessel 6, separation and collection of the oils from the outlets 14 can occur before the separation and collection of the gums and waxes extracted from the outlets 14 downstream. This separation and collection of the outlets 14 results in extractive streams having a larger concentration of the desired extractive substance, and further results in the elimination or reduction of subsequent refining steps. This same technique can be applied to other compounds extracted separately. It is desirable to optimize the amount of feedstock that can be treated per unit of time and / or per unit amount of the process solvent used to achieve the desired level of oil or extraction of other compounds. The Figures 3D-3E illustrate a preferred embodiment designed to achieve this goal. In Figure 3D an oil content measurement assembly 100 is attached to the orifice or nozzle or outlet nozzle 13"of the oil-depleted substrate to capture a sample of the substrate as it leaves the outlet 13" - In a preferred embodiment the assembly 100 comprises a pipe 101 having a flange 102 which is attached to the flange 103 of the outlet orifice 13"by bolts 104 allowing the substrate to exit the outlet nozzles 13" and to flow through the passageway. 105 of the pipe 101. The assembly 100 further comprises a duct 106 extending perpendicularly through the wall 107 of the pipe. The duct 106 can be permanently welded or fixed in another way to the wall 107 of the pipe. Alternately, it can be slidable in and out into the opening 108 in the wall 107 of the pipe. In the latter case, the conventional sealing means 108 is positioned to seal the opening 108 to prevent any propane or other material in the passage 105 from coming out through the opening 108. The assembly 11 further comprises a device 110 for measuring the substance that extracts, such as an absorption manometer that uses infra-red or near infra-red light projected in passage 105 to measure the amount of extractant in the substrate. One such pressure gauge is the Model No. MM55E adsorption manometer manufactured by Infrared Engineering Inc. located in Concord, Massachusetts. In a preferred embodiment, the duct 106 is closed at its end 111 extending internally from the passage 105. The end 111 is provided with a hole 112 from which a duct 113 of smaller diameter projects and through which the beam of light from device 110 will pass. In this embodiment, conventional seals 114 are used to prevent any liquid or any other matter in the passageway 115 from the duct from exiting through the opening 112. The opposite end 116 of the duct 106 is open to the passage 105 of the pipe. The wall 117 of the duct is provided with a slot 118 positioned in the passageway 105 of the pipe to allow the substrate to fall through the slot 118 and to be collected in the opposite section of the pipe wall 117. The duct 106 is further provided with an inlet pipe 119 having an end 120 that can be connected to a supply to a propane solvent or other process solvent and the other end 121 is opened in the passage 115 of the duct, preferably in a position between the closed end 111 of the duct and the slot 118 that allows any propane or other process solvent to pass under pressure through the inlet pipe 119 to blow any substrate that is collected in the duct passage 115 out of passage 115. In operation, the substrate falls through slot 118 and is collected within passageway 115 of the duct. After sufficient substrate has been collected, a near-infrared beam of light is passed through the duct 113 and the amount of light absorbed at different predetermined wavelengths is determined. The amount of absorption measured is proportional to the amount of oil or other extractant removed from the feedstock. These measurements are recorded by the device 110 which in a preferred embodiment is provided with conventional means for signaling the controller (not shown) of the motor 18 to either reduce or increase the revolutions per minute of the shaft or arrow 15. More particularly, if the measurements indicate that the oil content is below a predetermined level, then the device 110 signals the controller to increase the speed of revolutions per minute of the axis 15. This is continued until the oil content approaches or exceeds the level predetermined. If the measurements indicate that the oil content is greater than the pre-determined level, then the device 110 signals the controller to reduce the revolutions per minute of the shaft 15 until the oil content approaches the predetermined level. In addition to the positioning assembly 100 after the outlet orifice 13", it can be placed at any point or points in the extraction zone where one wishes to measure the oil content or other contents of the extractant or the substance that is extracted of the substrate.

Returning to Figure 1, the solvent / oil mixture passing through the outlets 14 is collected and transported via line 20 to the mixing compensation tank 21 that can be used to gravity-free any water , or other undesirable fluid that may be in the mixture. The mixture is preferably maintained in line 20 and in the tank 21 of compensation of the mixture under extraction conditions. While under these conditions, the collected muffle is pumped from tank 21 by pump 22 to assembly 23 of the filter membrane. The pore size and construction of the selected membrane will depend on the solvent of the processes and the extractive substance used in the process, the operating conditions used in the separation as well as the volume of the mixture to be treated. The pore size is selected so as to substantially allow only the process solvent to pass through the pores. However, it is feasible that small amounts of the extractive substance can be allowed to pass through the pores of the membrane. In addition, the filter must be constructed to allow not only operation under extraction conditions, but also to allow sufficient differential pressure to exist on opposite sides of the membrane to force the solvent through the membrane. Because it is intended that the filtrate process solvent be directly recycled in the hoppers 2 or the extraction vessel 6, the pore size is preferably selected to minimize the amount of extractive substance that can pass through the pores of the vessel. filter membrane. Ideally, the extractive substance will not be allowed to pass. To allow filtration under the extraction conditions, and with the use of the liquified solvents of this invention, it is preferred that a ceramic filter constructed have a flow through the central wall with the desired pore size formed by alumina, silicon and Water, zirconium, silica or titanium coating compounds can be used. More preferably, the coating will be zirconium or titanium oxide. Ceramic filters are preferred due to their ability to resist use and to be formed with a consistent pore size that allows operation under pressure. The process solvent together with any extractive substance passing through the filter membrane is transported through the process solvent filtered by the transfer line 24 to a tank 24 containing solvent from the process from which it can be recycled directly when the chamber 9 is needed by the pump 26 through the line 27 of recycling the solvent or for other uses, such as the use in a distillation column 43. It is anticipated that the loss of the solvent in the preferred process will be less than 0.1% which is substantially better than the processes of the prior known techniques. However, if necessary, fresh process solvent may be added to the tank 25 containing the solvent through the replacement line 28 of the process solvent from a source of the process solvent, shown. The extractive substance that does not pass through the filter membrane is then transferred through the extractive transfer line 29 to a flash unit 30 of the conventional solvent to remove any process solvent that may be trapped in the extractive substance. The extractive substance is then transferred via transfer line 31 for further treatment in a conventional vacuum flash unit 32 to remove any remaining process solvent from the extractive substance. This treated extractive substance is then transported through the line 33 of storage of the extractive substance to a storage tank 34 of the extractive substance from which it can be transferred via the pump through the transfer line 36 to any current processing from below.

The solvent liquefied in a vapor state removed from units 30 and 32 is transformed through solvent transfer lines 37 and 38, respectively, to pressure compressors and vacuum chamber LPG 39 and 40, respectively . The solvent vapor is compressed and condensed to transform it back into the fluid state. This process solvent can be transferred to tank 25 storing the solvent process. If desired, line 41 can be ventilated to remove inert substances that may be present through inert ventilation line 42. Ventilation should be kept to a minimum, as this can result in the loss of solvent from the system. The process solvent introduced in the distillation column 43 is transformed into its vapor state and transported via the transfer line 44 of the condensed vaporizer back to the hoppers 2. Any lipid or other extracted material removed during the distillation is discharged to the through line 45 of download. The material depleted with the extractive substance passes through the outlet 13 and into the retention hopper 46 which is sealingly connected to the outlets 13 through the valve 46.

Any air in the retention hopper 46 has been previously removed with the LPG vacuum compressor 40 and vented to the atmosphere. The retention hopper 46 is enchaquetada with 48 to eliminate any solvent in the material. The solvent in the vapor state is vented via line 49 to vacuum compressor 40 LPG or through line 49a to pressure compressor 39. The remaining (refined) material in the retention hopper 46 is then removed via the line 50 and is introduced into the transfer container 51 provided with a screw conveyor and thus transferred through the container 51 to a retention hopper 52 compensation. The compensating retention hopper 52 is also provided with a water jacket 53 to heat the raffinate to further remove any remaining solvent from the process. The process solvent in vapor state is vented through line 54 and into a conventional cyclone or similar separation unit 55 where any trapped solid can be separated and discharged via line 56 to conveyor 57. The process solvent The vaporizer is then transferred via line 58 to line 38 to vacuum compressor 40 LPG. The material in the stopping hopper 47 is treated in the same manner as in the stopping hopper 46. Having multiple stopping hoppers it is possible to run a continuous or semi-continuous process instead of a batch process. A feature of the embodiment of Figure 1 is that as the material containing the lipid from the hopper 2 is fed into the extractor container 6, the second hopper 2a can be loaded with additional feed material. Through the proper sizing and selection of the number of hoppers and the flow velocity in and out of the hoppers, there can be a continuous feeding of lipid-bearing material to the chamber 9. Figure 2 is an alternative mode that employs the use of grinders or mills 59 and 60 under extraction conditions. More particularly, the lipid bearing material is fed from the hopper 2 under pressure via the transfer line 61 from the valve 5 to the grinder / mill 59 where the material carrying the lipid is decreased in size under the conditions of extraction.

The degree of grinding or decrease in size will depend on the material that contains the lipid. If the material does not really form a paste, then the material will be milled to its final desired size. The ground material is then transferred under pressure via the transfer line 62 to chamber 9. However, if the ground or pulverized material could not be reduced to a desired final size, then the substrate exiting through the exit orifice 13 of the substrate is transferred under pressure via the transfer line 63 to the mill / grinder 60 of the second stage wherein the substrate is further reduced to the final desired size. The substrate is then transferred under pressure via line 64 to a second extraction vessel 65 and constructed and operated in a manner similar to extraction vessel 6. The solvent / oil mixture exiting both of the extraction vessels is collected under pressure via transfer lines 66 and 67 to the mixing compensation tank 21 and then substantially liquefied as illustrated in the Figure 1. The substrate containing small amounts of the mixture leaving the second extraction vessel 65 is then treated substantially as described above. Turning now to Figure 4, the process is illustrated in which the feedstock comprises material that can not be easily transported by a screw conveyor or where it is desired that the feedstock receive a milder mixing action with the solvent , such as clothing or clothing. In this embodiment, the laundry will be loaded by any conventional means into a sealable container 68 containing an inner basket 69 that has been provided with drainage openings 70 of the extractive substance. Mounted on the drive shaft 71 are the stirring blades 72 driven by the motor 73 positioned externally of the container 68. Once the clothes are loaded, the valves 74 and 75 are opened. The vacuum pump 76 is then activated to pump the air from the chamber 77 of the inner basket via the line 78 and the air ventilation line 79.

Once the air has been emptied from the chamber 77 and the valves 74 and 75 have been closed, the valve 80 is opened to allow the process solvent, such as propane, to pass from the storage container 81 of the solvent to be introduced into the chamber 77 via the transfer line 82. The camera 77 will be operated under extraction conditions. The rotating motor 73 is turned on to cause the blades or blades 72 to agitate the process solvent mixture and clothing enough to cause the process solvent to come into contact and extract the extractive substance absorbed in the clothing. The mixture of solvent and oil formed flows through the drain openings 70 and into the outlet line 83 of the mixture which when the valve 84 is opened allows the mixture to be stored in the pressurized container 85. If desired, one or more additional cycles of the process solvent extraction can be used to assist in the removal of any oil. When the extraction process is complete, the engine 73 is turned off, and any remaining mixture is allowed to drain into the storage container 85 of the mixture. Once the mixture has drained, valve 84 closes, and valves 74 and 86 open. The vacuum pump 76 is activated to remove any vapor from the solvent that could remain in the chamber 77. The solvent vapor is then transferred via the transfer line 87 to a conventional solvent recovery unit 88 that allows the venting of any substance inert through line 89 of ventilation. The unit 88 also allows the solvent captured in a vapor state to be liquefied and transferred via line 90 to the storage vessel 81 of the process solvent. The solvent recovery unit 88 may comprise the flash vessel, the vacuum vessels, the compressors and the distillation columns as shown in Figure 1. Once the vaporized solvent has been removed from the chamber 77, the extraction container 68 is opened to allow the disposal of the laundry 91 treated. The mixture in the container 85 is transferred via the transfer line 92 to the filtration unit 93 where the extractive substance and the solvent are separated from the process. The filter unit 93 is preferably constructed as described above for mounting 23 of the filter membrane. The solvent from the separate process is then transferred directly via line 94 to the storage vessel 81 of the process solvent. The extractive substance is then transferred via the transfer line 95 of the extractive substance to the receiver 96 of the extractive substance receiver where, if desired, it can be further transferred via the transfer line 97 to the recovery unit 88 of the extractive substance. solvent to remove any remaining liquefied solvent remaining in the extractive substance. Alternatively, or in addition, the extractive substance in vessel 96 can be transferred via line 98 to the downstream refining processes. Figures 5A and 5B illustrate an alternative method for transporting the extraction material through the extraction zone. This embodiment is particularly useful for food material such as clothing or other bulky items. In this alternative embodiment, the feedstock is introduced into an extraction container 100 of the inlet opening 101 preferably positioned at one end of the extraction chamber 102. The introduction of the feed material can be controlled to allow any quantity to fill only one basket 103. In this embodiment, the basket 103 will be positioned directly below the inlet opening 101 to allow the feed material to be fed by gravity directly to the basket 103 Once the basket 103 is full, the conveyor belt 104 to which the basket 103 is fixed is activated to move forward in the direction of the arrows "A" by coupling the motor 105 operatively connected to the conveyor belt 104 by the conventional shaft 106 and coupling the roller assemblies 107. The forward movement is continued until the back basket 103 is positioned below the entry opening 101. The conveyor band 014 then stops for a sufficient time for the basket 103 to be filled. The transported web 104 is then activated again and the process is activated in a similar manner. Each basket 103 is fixed to the conveyor band 104 so that when it reaches the position as shown by basket 103D and basket 103C, it will be retained in conveyor belt 104. It is preferred that the section that the section 110 of the floor forming the basket 103 be provided with drainage or drain openings 111 sized to allow any mixture formed in the basket 103 to drain from the mixture 103 during transport to the container 103. through the chamber 102. The side walls 112 of the basket 103 can similarly have openings that allow the mixture to pass. Such a basket could be constructed having the sides and roof in the form of a sieve. Regardless of the construction, it is preferred that the size of the openings be such as to allow the mixture to drain through it, but not allow the passage of the feedstock or allow any significant portion of the feedstock to be extended to through the sieve openings. The extraction vessel 100 is also provided with a substrate outlet 108 depleted with extractive substance, structured and positioned to receive the solvent treated material being removed from the basket 103B. The extraction vessel 100 is also provided with one or more outlet openings 108 for allowing the mixture to drain by gravity from the chamber 102. In a preferred embodiment, the extraction vessel 100 will be constructed with a floor 110 with an inclination that helps in the collection and in the directing of the mixture towards exit opening 108. Placed on the upper surface of the container 100 are the nozzles 114 through which the process solvent can be introduced into the chamber 102. In a preferred embodiment, the nozzles 114 are positioned to introduce the process solvent directly into the baskets 103. as each of the baskets passes below one of the nozzles. In operation, the air is removed from the chamber 102. The feed material is then introduced into the chamber 102 through the inlet opening 101 as described above. The chamber 102 is maintained under extraction conditions. The solvent is introduced through the nozzles 114 and brought into contact with the feed material in each basket 103 as the baskets are passed through the chamber 102. The speed of the baskets is preferably controlled to allow extraction of the oil from the feed material before a basket 103 reaches the position of the basket 103b. The mixture that is formed is drained from the baskets, through the band 104, or fall from the baskets when they reach the position of the basket 103c. The mixture is collected on the 110th floor and fed by gravity to the opening 109 where it is collected. The collected mixture can then be treated as shown in Figure 1. The substrate depleted with extractive substance is removed from the baskets as they reach the position of the basket 103b. The substrate passes through the opening 108 and can be further treated as shown in Figure 1. The conveyor belt 104 is preferably constructed having mesh openings 113 that allow any mixture to pass through the baskets 103 and toward the band 104 continues to pass through band 104 where it can be collected from floor 110. There are variations and modifications of the invention as described that could be obvious to someone skilled in the art and that could be included in the scope of the invention as defined by the following claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (11)

1. - A solvent extraction process that uses a solvent to extract an extractive substance from a material that contains the active substances, the process is characterized in that it comprises the steps of: a. contacting said material containing the active substance with the solvent in an extraction zone operated under extraction conditions to form a mixture of solvent and oil and a substrate depleted with extractive substance; b. separating the mixture from the spent substrate with extractive substance under extraction conditions; and c. filtering the mixture using microfiltration, ultrafiltration, nanofiltration or reverse osmosis filtration membrane under conditions that achieve a different pressure across the membrane to form a separate solvent-rich permeate and a stream containing the substance rich in extractive substance; wherein (i) said filtering of the mixture through the filtration is carried out under conditions necessary for at least some of the solvents to remain in a liquid state.

2. - The process according to claim 1, characterized in that it comprises the additional step of: d. subjecting the retained substance from step (c) to separation conditions in a separation zone such that the residual solvent that may be present in the retained substance is separated from the retained substance to produce an extractive substance that is essentially free of the solvent and produce a vapor stream that • understands the solvent in a vapor state. and. discharging the substrate exhausted with extractive substance from the extraction zone to the zone of instantaneous evaporation that is maintained at a pressure and temperature that induces any residual solvent in said substrate exhausted with the extractive substance the separation by instantaneous evaporation and the separation of said spent substrate with the extractive substance to form a vapor stream comprised of the solvent in the vapor state and to form a spent substrate with an evaporated evaporative substance having a reduced residual solvent content.

3. - The process according to claim 2, characterized in that it comprises the additional step of: f. discharging the spent substrate with extractive substance separated by instantaneous evaporation of the instantaneous evaporation zone towards a separation zone where said substances depleted with the extractive substance separated by flash evaporation are subjected to a pressure and temperature that induce the residual substrate in said Depleted substrate with extractive substance, evaporated by flash evaporation are separated from said depleted substances with extractive material separated by flash evaporation to form a second vapor stream comprising the solvent in a vapor state and a depleted substrate with separate extractive substance which is substantially free of said solvent.

4. - The process according to claim 3, characterized in that the separation zones and the separation conditions of the spent substrate with a separated extractive substance are brought into contact with the inert gas additionally under conditions that induce the residual solvent to diffuse and separate from it. said substrate depleted with extractive substance, separated to form a third stream of vapor comprised of solvent in a state of vapor and said inert gas, to form a second stream of the substrate depleted with extractive, separate substance that is essentially free of solvents.

5. A process according to claim 1, characterized in that said solvent is a solvent in process, and wherein the extraction zone comprises having walls that form a pressurized chamber in which a conveyor placed in it is mounted to receive the material that contains the extractive substance, said walls are provided with a first opening through which the material containing the extractive substance can be introduced into the chamber, said walls being provided with a second opening separated from the first opening through which the substrate exhausted with Extractive substance can exit from the extraction zone, said material containing the extractive substance is continuously fed through the first opening towards an end section of the conveyor, the conveyor is operated to move the material containing the extractive substance at a controlled rate through the extraction zone towards the second opening, said conveyor is further positioned to allow the solvent to enter the container through the solvent inlet openings and be distributed over the upper surfaces of the substance of the material containing the solvent. extractive substance at one or more points along the This conveyor is run in such a manner that the process solvent flows downwardly through the material containing the extractive substance as said conveyor moves the material containing the extractive substance through the extraction zone to provide contact between the solvent of the process and the material that contains the extractive substance to promote the extraction of the extractive substance by means of said solvent of the process to form the mixture and the substrate exhausted with extractive substance; and wherein the walls are provided with at least a third opening on which a porous filter is placed, said third opening is placed under the conveyor, the porous filter is structured with pore sizes that allow the mixture to flow through the pores and out of the extraction mixture and dimensioned in its size to substantially block the flow of the spent substrate with the extractive substance.

6. - The process according to claim 5, characterized in that a compression zone is contained in the container and the conveyor is a rotating helical rotary screw conveyor having extensions downstream of said boring screw placed closer to the second opening than the first opening and within the compression zone for compressing and removing from the spent substrate with extractive substance at least some of any process solvent in said substrate depleted with extractive substance as the compression screw extensions transport the depleted substrate with extractive substance.

7. - A process according to claim 5, characterized in that a means for measuring the percentage of the concentrate of the extractive substance is fixed to the container to receive a sample of the substrate depleted with extractive substance.

8. - A process according to claim 7, characterized in that the conveyor is operated operatively by a motor, the speed of the motor is determined by a controller operatively connected to the motor, said controller is electronically connected to the means to receive the measurement of the percentage of the Concentrating said means, the controller is programmed to adjust the speed of the motor in relation to the measurement.

9. - A process according to claim 5, characterized in that the feed material is brought into contact with the solvent under conditions that produce a first stream rich in extractive substance and subsequently produce a second stream rich in extractive substance, said second opening is placed at a sufficient distance from the first opening to receive the first stream rich in extractive substance, the walls are further provided with a fourth opening placed between the second and fourth openings, said fourth opening being placed at a sufficient distance from the second opening for receive the second stream rich in extractive substance.

10. - A solvent extraction process according to claim 1, characterized in that the filtration occurs at a temperature up to 140 ° F and the pressures are lower than 200 psig and under conditions to achieve a differential pressure across the membrane.

11. - A solvent extraction process according to claim 1, characterized in that the material containing the extractive substance is reduced in particle size before being brought into contact with the solvent, and wherein said substrate exhausted with the extractive substance is reduced in the relative size and then said depleted substrate is contacted in a second extraction zone with the extractive substance with reduced particle size with the solvent to form a second mixture and a second substrate depleted with the extractive substance.