Abstract:
A device and method for its use for separating particulate matter into fractional components. The device is characterized as being in the shape of a substantially vertical column having a feed port for feeding the particulate matter thereto. A top is provided for removing a light fraction of the particulate matter and a bottom for collecting a heavy fraction of the particulate matter and a longitudinal axis between the top and bottom portions of the column. Provision is made for drawing current of fluid such as air through the column which contains a channel characterized as having a series of angular bends with respect to the longitudinal axis, the bends being more acute to the longitudinal axis as the distance increases from the feed port.

Description:
TECHNICAL DESCRIPTION OF THE INVENTION 
     The present invention is directed to a device and method for using it in the separation of particulate matter having physical characteristics enabling fractional components of the particulate matter to be separated by subjecting them to various fluid velocities. The device includes a feed port and channel having a specific geometry for optimizing the separation of fractional components therein. 
     BACKGROUND OF THE INVENTION 
     The use of fluid flow under positive pressure or vacuum as an expedient for the separation of particulate matter into various fractional components is well known. Devices of this nature generally known as air classification have taken advantage of differences in density, particle size and particle surface smoothness to fractionate a mass of particulate matter in a wide variety of fields. 
     In the field of air classification, a critical aspect of achieving sufficient particle separation to achieve effective separation is a minor limiting factor. For example, oftentimes the physical characteristics of a particular mass of feed material to be separated has a composition where the attractive force between particles results in clumps of such particles being subject to the separation process. Separating feed of this nature requires different considerations than the separation of dry highly mobile particles. This is particularly the case when animal matter such as dried fish meal is to be separated into its meat component and scale and bone components. Also, harvested seeds which could include stems, leaves, soil and other foreign debris requiring separation can have a high moisture content depending upon the climactic conditions existing at the time of harvesting. None of the separators employing fluid flow traveling through a column accounts for clumping and other physical characteristics which may characterize the particulate feed matter made subject to the separation process. 
     It is thus an object of the present invention to provide a device for separating particulate matter into fractional components which is uniquely adapted to maximize particulate separation regardless of the moisture content and other physical characteristics of such matter. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a device for separating particulate matter into fractional components. The fractional components are characterized as having distinguishable physical characteristics enabling them to be separated by subjecting them to varying fluid velocities. 
     The device of the present invention comprises a substantially vertical column, a feed port for feeding particulate matter thereto, a top for removing a light fraction of the particulate matter and a bottom for collecting a heavy fraction of the particulate matter. The column has a longitudinal axis between the top and bottom together with means for drawing a current of fluid through the column. A channel is configured within the column, the channel being characterized as having a series of angular bends with respect to the longitudinal axis. The bends contained within the channel are more acute to the longitudinal axis as the distance increases from the feed port. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The sole FIGURE appended to the written description is a side plan view of this invention in partial cross-section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As noted previously, the present invention is directed to device  10  for separating particulate matter into fractional components. Although the nature of the particulate matter will be more thoroughly discussed hereinafter, generally, the particulate matter should broadly be composed of fractional components having distinguishable physical characteristics enabling them to be separated by subjecting them to varying fluid velocities. 
     Column  19  is generally oriented vertically and is ideally in the form of a column having a substantially rectangular cross-section. 
     The device of the present invention is provided with feed port  11  for feeding particulate matter within column  19 . As noted in the appended FIGURE, feed port  11  ideally is configured to introduce particulate matter closer to top  14  than bottom  15  of column  19 . The reason for this geometry is that upon introduction of particulate matter within column  19 , a fluid such as air flowing in the direction of arrow  30  will cause some of the light, less dense material through channel  13  and out of tubing  19  leaving the enriched coarser, heavier fraction of the feed material in the column which tends to precipitously drop below the feed point. The coarser fraction generally requires more column length to promote separation as the separating process continues. 
     Again, as noted in reference to the appended figure, channel  13  is provided with a series of angular bends with respect to longitudinal axis  12  which vary in profile. In the section proximate entry port  11 , these bends tend to be flatter in area  16  while as one progresses above and below feed port  11  along longitudinal axis  12 , these bends tend to become more acute. In fact, the side walls of channel  13  in the area of feed port  11  can be substantially parallel to longitudinal axis  12  while the side walls in areas  18  and  17  proximate the top and bottom of the column, respectively, can be approximately 45° to longitudinal axis  12  resulting in 90° elbow bends as the column is viewed in cross-section. 
     The angular bends within channel  13  have been configured to maximize particle separation. Specifically, the channel angles are arranged so that particulate matter entering feed  11  would initially impact upon obtuse angular side walls maximizing initial separation if clumping as a result of high moisture content or otherwise is a characteristic of the feed material. As noted previously, in this section, some light feed material is drawn through top area  13  of the separator leaving an enriched coarser fraction to fall below feed port  11 . As more of the “fines” are removed, particulate matter enters area  17  where the acute angular profile of the channel causes a pulsating effect. As the areas measured from apex to apex and side wall to side wall change air velocities vary within the channel noting that the multiple of area and horizontal air velocity remains constant. This pulsating effect serves to separate the particles within the channel and results in a more efficient product separation. 
     As separation continues within column  19 , less dense particulate matter is caused to travel in the direction of air flow, that is, in the direction of arrow  30  caused by a vacuum being drawn upon column  19  by motor  21 . This separated particulate matter is then caused to travel through output conduit  19  and into a separator. Product can be collected through the use of a filter or any other expedient as separation subsequent to involvement by column  19  is not necessarily the crux of the present invention. However, as a preferred embodiment, cyclone separator  20  can be provided whereby separated particulate matter traveling through conduit  19  can be caused to be further collected by drawing such a matter through outlet port  22  allowing further more dense components to be withdrawn from port  23  for possible recycling through column  19  (not shown). 
     Although a number of column channel dimensions can be selected in conjunction with appropriate air flows depending upon the nature of the particulate matter to be separated, it is generally believed that a column having a rectangular cross-section whereby the channel is provided with a width dimension of 12 inches and depth of 24 inches is ideal. If cross-sectional areas become greater than those recited, imbalances and inconsistencies in fluid flow can be set up at any given point within channel  13  reducing separation efficiency. Further, a vacuum created by motor  21  should ideally be created resulting in an a fluid flow in the direction of arrow  30  at a rate between approximately 6 to 15 meters per second. In each instance, one can match air flow and channel cross-sectional area to create the desired turbulence at various fractionation points. 
     As noted previously, the present invention can be employed to separate a wide variety of particulate matter. For example, fish meal and dried meal produced from other animal sources can be separated from bone and scale fragments as well as a variety of extraneous materials. Employing fish meal as an example, this particulate matter enters column  19  through feed port  11  where it meets the up drafting fluid stream traveling in the direction of arrow  30 . An initial separation of heavy and light particles takes place in region  16 . However, due to cohesion, product lumping and other factors, some of the light particles will proceed downward within the channel to area  17 . The rather flatness of the side walls in region  16  will aid in initial separation and the breakdown of clumped particles for further processing. In area  17 , where the side walls are configured to be 45° to longitudinal axis  12 , different cross-sectional areas cause the channel velocity to increase from v to 1.4 v. This changing velocity pattern facilitates a breakup of product lumps and enhances separation between particles increasing the separation efficiency of the apparatus. 
     In dealing with fish products, the present invention effectively separates fish meat from scale and bone fraction (ash) in dried fish powder (fish meal). The invention takes advantage of the differences in particle density, shape, surface characteristics and moisture content of the fish meal on the one hand and bone and scale on the other to effect appropriate separation. The ash content collected in the vicinity of bottom  15  is to exceed 20% and preferably 30% or higher. The ash fraction is to be practically free of muscle meat. Such a fraction is suited for extraction of gelatin or other constituents contained in fish bones and scales. Alternatively, this fraction that can be further processed by hydrolysis to increase digestibility which is clearly a post-invention consideration as the invention further contemplates recycling product back through feed  11  either from conduit  23  or bottom  15 . 
     The present invention can also be employed as a seed cleaning expedient by enhancing the removal of extraneous material such as stems and leaves from the seeds themselves. It is quite apparent that the moisture content, clumping propensity, density and surface characteristics between seeds, leaves and stems makes the present invention ideally suited to perform this cleaning function. In addition, it is noted that seeds of low and high germination rates and those which are hybrid and non-hybrid varieties are of different densities and oftentimes display varying surface characteristics which again makes the present invention ideally suited to perform separation. As such, through the use of this device, the germination rates of seeds can be enhanced and hybrid and non-hybrid seeds separated. 
     A further use of the present invention is to classify crystalline products such as sugar and salt in order to increase the classification of such crystalline materials by particle size. In applying, for example, sugar particles to confectionery products, it is important that the sugar particles be of a substantially uniform size or dimension. The present invention can increase the concentration of uniformly consistent crystalline material for this purpose noting that such crystalline materials when subjected to turbulent fluid velocities tend to separate. 
     A yet further use of the present invention is in dust removal in size classification in the production of spices such as onion and garlic powders. In addition to dust removal, products such as onion salt and garlic salt require that the onion and garlic particles be of substantially the same density as the salt incorporated therewith. Unless uniformity is achieved, during the shipment and settlement of the product, all of the salt would tend to segregate from the onion or garlic powder resulting in an unacceptable product. Through the practice of the present invention, uniform density and size are achieved for further spice preparation and packaging. 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim and the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.