Patent Publication Number: US-6212736-B1

Title: Tube density separator and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/117,454, filed Jan. 26, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     A. Field of the Invention 
     The present invention relates in general to the design and operation of cotton gins. More specifically, the present invention relates to apparatuses and methods of mechanically separating cotton fibers from foreign matter. Even more specifically, the present invention relates to an apparatus and method of more efficiently separating cotton fibers from foreign matter by utilizing conveying air and gravity separation. 
     B. Background 
     Cotton that is harvested from a field consists primarily of the desired cotton fibers and cotton seed and much undesirable foreign matter, such as burrs, sticks, stems and green leaf material. After harvesting, the cotton/foreign matter material is taken to a cotton gin for processing the harvested material into bulk cotton fibers and cotton seed. A large part of a modern cotton ginning plant consists of machines and processes for separating and removing foreign matter from the cotton fiber both prior to and following the actual separation of the cotton lint from the seed (the actual ginning). The machines for removing foreign matter from the seed cotton prior to the ginning are referred to as pre-cleaners. Basically there are two types of pre-cleaners: (1) extractors, which are used for separating the large particles of foreign matter from cotton fibers (for instance, as described in U.S. Pat. Nos. 2,848,635 and 2,862,247 to Vandergriff); and (2) cylinder cleaners, which remove foreign matter that was not removed by the extractor. 
     Most common extractors make use of cylinders covered with aggressive, hooked teeth. As the cylinders rotate, they engage the cotton fiber/foreign matter mix and drag it over a screening surface. The screening surfaces generally consist of rods or bars mounted laterally adjacent the extractor (toothed) cylinder. The rods or bars are spaced apart a sufficient distance to permit larger particles of foreign matter to separate from the cotton attached to the teeth of the cylinder. The cotton fibers and foreign matter separate centrifugally, which is commonly referred to as a “sling off” process (see U.S. Pat. No. 2,848,635 to Vandergriff). Some cotton will sling off with the foreign matter and this mass of cotton/foreign matter is passed to one or more additional toothed cylinders (i.e., extractors) where the remaining cotton is further mechanically processed and reclaimed from the foreign matter. The cotton which remains engaged by the teeth of the cylinders is doffed by a rotating brush and delivered to the next process. 
     The process of extracting foreign matter from the seed cotton described above is a multi-stage process. The flow of seed cotton passes through the extractor to be processed by the toothed cylinder where the teeth engage the fibers and slings off the foreign matter. This separates the flow of seed cotton into two streams, one containing good cotton and some foreign matter, the other containing primarily foreign matter and some cotton. Unfortunately, the extraction process is not complete, as not all cotton fibers remain attached to the teeth (some cotton will sling off with the foreign matter) and not all the foreign matter separates from the cotton remaining on the teeth (some foreign matter may follow the cylinder and be doffed with the cotton). The first stream, comprising cotton and some foreign matter that was doffed from the extractor cylinder, generally does not receive further extraction. Instead, it will be passed along for treatment in the cylinder cleaner for further processing to screen out the remaining small trash particles. The second stream, comprising primarily foreign matter and some cotton, will generally pass to one or more additional extractors for further treatment. The cotton from the additional extractor(s) is then joined up with the cotton from the first or prior extractors in the cylinder cleaner. The foreign material separated from the cotton by the extractors is conveyed to a waste disposal system. 
     To improve the foreign material removal efficiency of extractors, a number of devices have been incorporated into the cleaning process over the years. One of these devices is the use of cylinders, having vanes or blades, that rotate in the opposite direction as the extractor cylinder such that the vanes or blades strip back the foreign material from the cotton. Another device that has been commonly used with extractors is a rotating brush cylinder made up of a cylinder covered with a wire brush material that is used to doff the cotton from the extractor teeth. Also utilized are flexible steel-wire brushes and saws, either singularly or in combination with each other, that separated cotton from the foreign material, generally prior to being treated by the extractor cylinder. 
     Cylinder cleaners, which are generally used after the extractors described above, primarily consist of cylinders having a number of pins protruding from the surface of the cylinder. The cotton is passed between the cylinders and a screen surface that is configured to facilitate the falling out of the small particles of foreign material remaining in the cotton stream after treatment by the extractor. To improve the efficiency of the cylinder cleaners, the feeder cleaning screens are typically inclined forty to forty-five degrees so that the screen will go higher between the cylinders. Over the years, to improve the separation efficiency of the cylinder cleaners the use of heated air and deflectors have been incorporated. 
     The devices utilized with extractors and cylinder cleaners to improve efficiency of the mechanical separation of cotton from foreign matter are generally successful in separating most of the cotton and seed from the foreign material. However, the mechanical action of these devices, as well as the extractor itself, tend to lower the grade of the cotton by damaging the spinning value. Lower grade cotton results in lower prices for the cotton produced through the ginning process. As a result, there exists a need for an apparatus that effectively and efficiently separates cotton from foreign material without harming the value of the cotton. 
     SUMMARY OF THE INVENTION 
     The tube density separator and method of the present invention solves the problems identified above. That is to say, the present invention discloses a tube density separator and method for effectively and efficiently separating cotton fibers from the foreign material harvested with the cotton. Specifically, the present invention discloses a tube density separator and method that utilizes a stream of flowing air and the density difference between cotton and the foreign materials to separate out the foreign material from the cotton without the harm to cotton quality that results from the mechanical separation processes typically in use today. The present invention is adaptable and suitable for use in most cotton ginning plants currently in operation without major modifications to those plants. 
     In the primary embodiment of the present invention, the tube density separator and method utilizes a generally vertical tube having an inlet and an outlet at generally opposite ends of the tube. Preferably, the inlet is at or near the bottom of the tube and is larger in cross-sectional diameter than the outlet, located at or near the top of the tube. The tube can have a uniform taper from its inlet to the outlet. At its inlet, the tube density separator receives a flow of cotton/foreign material mixture in air flowing through a piping system. If the tube density separator is placed between the dryer, such as a jet dryer, and the cylinder cleaners, hot air from the dryer can be utilized by the tube density separator. The inlet is sized to be greater in cross-section than the discharge from the piping system so that there will be a decrease in velocity of the air and a tumbling action. The decrease in air flow rate and the tumbling action will result in the heaver foreign materials dropping out of and separating from the cotton fibers. The use of dispersing rods that extend into the tube and the flow of cotton/foreign material up through the tube, further results in the foreign material separating from the cotton and falling out the bottom of the tube at the inlet. 
     To carry away the foreign material that separates and falls out due to the mechanical and gravitational effects inside the tube, a supply of air is sent across the bottom of the tube in a generally perpendicular relationship to the upward flow of cotton and foreign materials. Because the foreign material separated from the main flow of cotton/foreign material will contain some cotton, it can be sent to a reclaimer or other device for further separation of the foreign material from the associated cotton fibers. After reclaiming, the cotton fibers are transferred to downstream of the tube density separator where it rejoins the cotton that has passed through the tube density separator. The supply of air for carrying away the separated foreign material can be split off from the air flow through the tube density separator by splitting it into a primary air stream and a secondary air stream at or near the tube outlet. The primary air stream will carry the separated cotton fibers to the next processing step, such as a cylinder cleaner, and the secondary air stream will be circulated around to the inlet area to become the waste conveying air stream for conveying away the foreign material that was separated from the cotton fibers inside the tube. 
     The apparatus and method of the present invention removes a high percentage of the material which would normally be removed by stick machine extraction. In some cases, cylinder cleaning would be the only additional cleaning needed after the tube density separator and method of the present invention. To make use of the tube density separator, the commingled mass of cotton and foreign matter must be suspended in an air stream with a conveying velocity. The most likely location for obtaining such an air stream is in the line carrying the mass to the dryer or from the dryer. This duct work can be routed to the bottom of the tube density separator of the present invention and connected to its inlet duct. A common arrangement is for this conveying air to have a conveying velocity in the range of 4,000 feet per minute, which is a good velocity with which to enter the tube density separator unit. This is hot air, preferably from the dryer and on its way to the cylinder cleaner. This provides additional drying by exposing the material to the hot air. Although the separation process in the tube and the air used in the conveying process (as described) follows a circuitous route, it ends up in the cylinder cleaner with the cotton, which is where it would have gone had it not been side-tracked through the tube density separation process described herein. 
     The tube density separation apparatus and system of the present invention replaces at least one mechanical separation process. Its chief advantage over the existing art is to separate foreign matter by air, rather than using saws and brushes. This “air separation” is gentler on the cotton fibers and, therefore, should result in higher grades of cotton and more money to the farmer. With further refinement, it may replace the entire mechanical extraction process altogether. The tube density separator of the present invention can be used in series with one or more additional tube density separators (as many as desired) such that multiple tube density separators are used to further separate the cotton from the foreign matter. 
     Accordingly, the primary objective of the present invention is to provide tube density separator and method that utilizes flowing air and the gravity difference between cotton and the foreign material to separate the cotton fibers from the foreign material. 
     It is also an important objective of the present invention to provide a tube density separator and method that utilizes a substantially vertical tapered tube having an inlet at or near the bottom thereof for accepting a flow of cotton having foreign material combined therewith to separate out the foreign material from the cotton fibers. 
     It is also an important objective of the present invention to provide a tube density separator and method that utilizes a flow of air to carry away foreign material that has been separated from a cotton/foreign material mixture in the tube density separator. 
     It is also an important objective of the present invention to provide a tube density separator and method that utilizes one or more dispersal rods to break apart a mixture of cotton fibers and foreign material to further facilitate the gravity separation of the foreign material from the cotton. 
     It is also an important objective of the present invention to provide a tube density separator and method that is adaptable to current cotton ginning plants without extensive modifications to those plants, and is suitable for use with other cotton ginning equipment. 
     The above and other objectives of the present invention will be explained in greater detail by reference to the attached figures and the description of the preferred embodiment which follows. As set forth herein, the present invention resides in the novel features of form, construction, mode of operation and combination of processes presently described and understood by the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the best modes presently contemplated for carrying out the present invention: 
     FIG. 1 is a side view of a cotton ginning process utilizing the tube density separator of the present invention; 
     FIG. 2 is a cross-sectional plan view of the inlet area of the generally vertical tube taken through  2 — 2  in FIG. 1; 
     FIG. 3 is a view of the generally vertical tube for use in the present invention showing a possible placement of the dispersing rods; 
     FIG. 4 is a cross-sectional plan view of the generally vertical tube taken through  4 — 4  in FIG. 3; 
     FIG. 5 is a view of dispersing rods in a pipe for carrying cotton; and 
     FIG. 6 is a cross-sectional plan view of the pipe of FIG. 5 taken through  6 — 6  in FIG.  5 . 
    
    
     DETAILED DESCRIPTION 
     With reference to FIGS. 1 through 4, where like elements have been given like numerical designations to facilitate understanding of the present invention, the tube density separator of the present invention is designated generally  10 . The inventor has found that the initial separation of the cotton/foreign matter harvested from the field can be more easily and efficiently made through a process of density separation. This process can be done in a single stage or in multiple stages, i.e., with the use of one or more tube density separators in series, and can essentially eliminate the need for mechanical separation by the extractors. 
     The tube density separator  10  primarily comprises a generally vertical tube  12  into which the flow of cotton and foreign material in an air stream is projected at a conveying velocity. Tube  12  has a relatively large cross-section at its inlet  14  located at the bottom  16  of tube  12 . Generally opposite inlet  14  is outlet  18  located at or near the top  20  of tube  12 . In the preferred embodiment of the present invention, tube  12  has a uniform taper from bottom  16  to top  20  of tube  12 . The uniform taper facilitates the conveying of the cotton materials up to and past outlet  18  of tube  12 . The cotton, containing the foreign material, entering tube  12  at its inlet is transported by a flow of air, preferably, from a dryer unit, such as the jet dryer  22  shown in FIG.  1 . As such, the air will be heated and the cotton/foreign matter mixture will be relatively free of or have a low amount of liquid content. The dry cotton mixture in hot air further facilitates the operation of the present invention. 
     Pipe outlet  24  of the pipe  26  transporting the cotton/foreign matter mixture from jet dryer  22  in a ginning plant will have a fixed diameter, commonly twenty-four inches. The inlet  14  of tube  12  should have a diameter (i.e., thirty-six inches) that is greater than the diameter of pipe outlet  24  to permit the cotton/foreign material mass to lose velocity and drop out some of the foreign matter, which is of greater density than the cotton, from the cotton. This density difference applies to just about all foreign matter, even a grain of sand. Foreign matter and some cotton will accumulate temporarily at the bottom  14  of tube  12 , where the high velocity inlet air causes a tumbling action, which causes some of the heavier particles to fall out. The cotton which is in the tumbling mass will be conveyed upward through tube  12  as it is freed from the mass of foreign matter. The cross-sectional diameter of outlet  18  can be approximately the same as that of pipe outlet  24  so that the air flow in tube  12  will return to its initial conveying velocity. 
     An important factor in the success of the tube density separator  10  of the present invention is the method of getting the separated foreign matter out of the unit  10 . The inventor has found that one such way for removing this material from the unit is by having it fall through an opening into a air stream moving across inlet  14  of tube  12  in a generally perpendicular relationship to the upward flow of air and cotton/foreign materials, as shown in FIGS. 1 and 2, so as to convey the fallen material away. One way to accomplish this is through the use of an arrangement similar to that used with the dryer unit and process described in U.S. Pat. No. 5,533,276 to Vandergriff. As shown in FIG. 2, the preferred mechanism for receiving and removing the foreign material that separates from the cotton is to utilize a configuration that includes a generally circular pipe  28  that goes around the pipe which pneumatically conveys the cotton/foreign matter mixture to the tube  12 . The source of air conveying the cotton/foreign matter mixture enters inlet  14  from pipe  26  (the center of FIG. 2) in a generally upward direction. The air in circular pipe  28  that is used to transport away the foreign matter goes around pipe  26 . The foreign mater falls into the open portion of circular pipe  28  that faces generally upward to receive the foreign matter. The outer edges of circular pipe  28  is enclosed by the outer edge of the bottom  16  of tube  12 . 
     In the preferred embodiment of the present invention, a source of air is used to convey the material away. One method of supplying the air for conveying the foreign matter from the tube density separator  10  is with the use of skimmer  30  at the top  20  of tube  12 . Alternatively, a separate source of air (i.e., not part of the supply of air that carries the cotton/foreign matter material) can be utilized to convey the foreign material away from tube  12 . The preferred method of supplying air for the waste conveying air stream is to use skimmer  30  (such as that which is described in U.S. Pat. No. 3,069,730 to Vandergriff) to separate the flow of air up tube  12  into two approximately equal flow air streams, a primary air stream  32  containing cotton and (likely) some remaining foreign matter and a secondary air stream  34  having no cotton or other materials. As shown in FIG. 1, the secondary air stream  34  is passed through booster fan  36  to supply air to move the cotton and foreign matter out of the tube density separator  10  through use of circular pipe  28  (as shown in FIG.  2 ). It is important to balance the system so that no more than a small portion of the air from the waste conveying air stream  38  finds its way back into tube  12 , thereby flowing against the discharge of foreign matter. This balance can be accomplished with simple valves that can be adjusted to obtain the necessary air dynamics at the exit of skimmer  30  and elsewhere in the system. A slight positive pressure will eliminate excess amounts of air from re-entering tube  12 . In the preferred embodiment, the cotton and the other half of the air discharging from the skimmer  30  at the top  20  of tube  12 , flowing in primary air stream  32 , goes to cylinder cleaner  40  for further cleaning. 
     The waste conveying air stream  38  from tube density separator  10  of the present invention containing the foreign matter, as well as some cotton, can convey the foreign matter to one or more additional treatment devices. For instance, the foreign matter may be conveyed to a green boll trap  42 , shown in FIG. 1, which is also a type of density separator, where green bolls, rocks and other heavy particles are dropped out into a screw conveyor. The green boll trap  42  is a simple device generally known in the industry. From trap  42 , conveying air can deliver the foreign matter (and associated cotton) to reclaimer  44  consisting of a toothed cylinder and a doffer, similar to that described above for the extractor. In the reclaimer, the foreign matter is separated from the conveying air by centrifugal action, taking the foreign matter on to the toothed cylinder, while the air by-passes down a passage in the front of the machine. The toothed cylinder passes the material over grid bars spaced so that the foreign matter can pass while the cotton is engaged by the teeth on the cylinder until doffed by the rotating brush. The cotton is doffed back into the air stream which delivers it to the reclaimer. This “good” cotton from the toothed cylinder, with its conveying air, rejoins the primary air stream carrying the cotton after the skimmer  30  to cylinder cleaner  40 . This, of course, can be done at any convenient point in the conveying line. As with the foreign matter separated by the tube density separator  10 , the foreign matter separated out through the grids of reclaimer  44  is conveyed to a waste system. 
     The preferred embodiment of the present invention also utilizes one or more dispersal rods  46  positioned inside, at least partially, the interior  48  of tube  12 , as shown in FIGS. 1,  3  and  4 , to break up clumps and wads of cotton so as to further enhance the removal of trash and moisture from the cotton fibers. The need for dispersal rods  46  arises because the conveyance of fibrous materials in an air stream that flows through a piping system, having elbows and changes in velocity, tends to result in the conveyed material being formed into clumps and wads. To further improve the efficiency of the separation that is provided by the tube density separator  10 , these clumps and wads should be broken up and dispersed throughout the air stream. 
     The preferred method of breaking up the clumps and wads is shown in FIGS. 1,  3  and  4 . As shown in these figures, one or more dispersal rods  46 , having a proximal end  50  and distal end  52 , are inserted through the wall  54  of tube  12  such that distal end  52  is in the air stream that is conveying the cotton materials through the interior  48  of tube  12 . The configuration shown in FIG. 1 utilizes two groups of rods  46  projecting into tube  12 , a lower group  56  having four rods and an upper group  58  having four rods (the lower group  56  being the group lower in the flow through tube  12 ). In the preferred embodiment, each rod  46  slidably projects through block  60  mounted on the side wall  54  of tube  12  into the air stream that carries the cotton through the interior  48  of tube  12 . The blocks  60  should have a sealing mechanism, such as a rubber seal  62 , in the opening to seal around rods  46  so that hot air from inside the tube density separator is not allowed to escape while rods  46  are being slidably moved therein. If rods  46  are capable of being fully removed from tube  12  or block  60 , then the sealing mechanism should also be suitable (i.e., self-sealing) for sealing the opening where rods  46  are inserted to prevent loss of air from tube  12 . Dispersal rods  46  should be of sufficient length so that the end of the rods  46  in the air stream can be at or near the center of the air stream, if desired. In the preferred embodiment, with slidable rods  46 , the distance which distal end  52  of rods  46  project into the air stream can be adjusted by sliding rods  46  in or out of blocks  44  to adjust the flow of material through tube  12  and the amount of dispersing action by rods  46 . For instance, if full insertion of rods  46  into tube  12  results in too much resistance, the rods  46  can be withdrawn through blocks  60  a sufficient distance to lower that resistance. 
     As an alternative embodiment of the present invention, the rods  46  can be fixed inside tube  12 . Rods  46  can extend in a fixed manner from or through blocks  60  through wall  54  and into the interior of tube  12 . If desired, blocks  60  can be eliminated and the rods  46  affixed directly to the inside of wall  54  of tube  12 . In an alternative to rods  46 , various other devices can be utilized to accomplish the objectives of rods  46 , that is to further enhance the removal of trash and moisture from the cotton fibers. Such devices can include fins, fin-shaped inserts, blades and similar devices which are able to break up the clumps and wads and disperse the cotton and associated foreign matter throughout the air stream inside tube  12 . 
     In the preferred use of the dispersal rods  46 , the lower group  56  of rods  46  is located near the bottom  16  of tube  12 , as shown in FIG. 1, and comprises four rods approximately ninety degrees apart (along wall  54  of tube  12 ), as shown in FIG.  1 . Upper group  58  is located above lower group  56  (in the direction of air flow) and comprises four rods placed ninety degrees apart from each other, but staggered forty-five degrees from the lower group  56  of rods  46 . Viewed from a cut-away through tube  12 , whether from below or above, rods  46  would appear as shown in FIG.  4 . As shown in FIG. 3, additional groups  64  of dispersal rods  46  may be utilized further up tube  12  as desired for additional dispersing of the clumps and wads. In the preferred embodiment of the use of dispersal rods  46 , rods  46  are ⅝″ diameter metal rods approximately 30″ in length. The rods  46  are inserted through blocks  60  into interior  48  such that they are at an angle of approximately forty degrees off wall  54  of tube  12 . Rods  46  of other materials and sizes and placed at other angles can also provide the benefits described above. If desired, rods  46  can be pivotally mounted to blocks  60  or inside tube  12  so that the angle of the rods  46  relative to tube  12  can be adjusted for peak performance. 
     The use of dispersal rods  46  as set forth above also benefits the drying process. Because the tube density separator  10  will generally, but not exclusively, be used in the heated air line between the drying unit  22  and the cylinder cleaner  40 , the dispersion action of rods  46  aids the drying process by affording better exposure of the cotton fibers to the heated air. In fact, the use of dispersal rods  46  projecting into the side of the pipes  26  that are used to convey fibrous material in hot air would greatly enhance the moisture transfer (e.g., drying) by creating slippage between the air and the fibrous material. 
     As shown in FIGS. 1 and 5, dispersal rods  46  described above can also be used in the pipes  26  that convey cotton in a heated air stream as part of the drying process (the use of such a pipe  26  having dispersal rods  46  is shown on the far left side of FIG.  1 ). In a seed cotton drying system in a cotton gin, metal pipes are generally used to convey the cotton in heated air to and from the drying exposure chamber. The moisture transfer from the cotton to the air in the pipe  26  is generally very limited because the air and cotton are traveling at about the same speed. The use of dispersal rods  46  projecting through the pipe  26  into the air and cotton flow will disperse the cotton and slow it down as it makes contact with rods  46 . This contact creates slippage between the rate of flow of the air and the cotton fibers, thereby enhancing moisture transfer to the air. 
     The most advantageous place to locate the dispersal rods  46  is in the pipe  26  immediately following the mix-point, where the temperature is the highest. As shown in FIG. 5, one or more rods  46  (the configuration shown in FIG. 5 utilizes eight rods  46  in two groups of four similar to that set forth above for the tube density separator  10 ) are inserted through the pipe wall  66  into the air stream that is conveying the cotton materials. The rods  46  can project through blocks  60  mounted on the side of pipe  26 . As with the dispersal rods  46  in tube  12 , the rods  46  in each group of rods in pipe  26  are offset ninety degrees from each other and the second group of rods (i.e., those downstream of the first group of rods) are offset from the first group by forty-five degrees. All of the rods  46  can be positioned at an angle of forty degrees, or other angle sufficient to break apart the clumps and wads, from the pipe wall  66  and be slidably mounted in blocks  60  to allow the user to adjust the amount of rod  46  insertion if resistance becomes a problem. As with the tube density separator  10 , the blocks  60  should have a sealing mechanism that prevents the escape of air from inside of the pipe. The rods  46  can be fixedly mounted inside or to pipe  26 , as discussed with the rods  46  in tube  12 . 
     In use, the present invention is utilized in a cotton ginning plant to facilitate the separation of cotton from the mixture of cotton/foreign materials harvested. The user of the present invention supplies a mixture of cotton/foreign materials that is pneumatically disposed in a pipe  24  suitable to transport these materials to the tube density separator  10 . The material is received into the bottom  16  of tube  12  at inlet  14 . Because the bottom  16  of tube  12  has a larger cross-sectional area than pipe  24  (at inlet  14 ), turbulence is created and the tumbling action results in some of the foreign material separating from and falling out from the cotton/foreign material mixture. The supply of air from pipe  24  is conveyed up tube  12  and additional separating and falling out of the foreign material occurs. The foreign material that drops out is collected in circular pipe  28 . The user also supplies a waste conveying air stream  38  to transport the foreign material away from tube  12 . The separated cotton is transported away from the top  20  of tube  12  for further processing (as needed). As discussed above, the above process can be substantially improved by adding dispersal rods  46  to the interior  48  of tube  12 . Dispersal rods  46  further break apart and separate the foreign matter from the cotton being conveyed up tube  12 . To adjust the amount of resistence to the flow of material up tube  12  caused by rods  46 , the rods  46  can be configured to slide in and out of the interior  48  of tube  12  as desired. The waste conveying air stream can be obtained by skimming off a portion of the air flow flowing up the interior  48  of tube  12  (the preferred method). A skimmer  30  can be utilized to separate the air flow in the interior  48  of tube  12  into a primary air stream  32  and a secondary air stream  34 , such that the secondary air stream  34  has little or no cotton or other material and it can be used as the waste conveying air stream. 
     While there is shown and described herein certain specific alternative forms of the invention, it will be readily apparent to those skilled in the art that the invention is not so limited, but is susceptible to various modifications and rearrangements in design and materials without departing from the spirit and scope of the invention. In particular, it should be noted that the present invention is subject to modification with regard to the dimensional relationships set forth herein and modifications in assembly, materials, size, shape, and use.