Patent Publication Number: US-2017355161-A1

Title: Compression screw for producing animal feed

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/866,926, filed Sep. 26, 2015, which will issue at U.S. Pat. No. 9,738,047 on Aug. 22, 2017. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Technical Field of the Disclosure 
     The present embodiment relates generally to compression screws employed to prepare animal feed products, such as dry grains, pellets, cubes, and tubs. 
     Description of the Related Art 
     In the field of animal feed processing, dried distiller grain (DDG) or dried distiller grain with solubles (DDGS) is a major feed source for farm livestock. This is due in part to the increased commercial interest in ethanol production. Generally, DDG and DDGS include an average 88% dry matter and 12% moisture. The dry matter is in the form of particulates formed from grinding grain kernels like corn during the process of producing ethanol from grain. Due to its chemical composition, particulates, typically, do not flow like liquids or melted plastics. Therefore, when compression screws are used to prepare the DDG or DDGS as animal feed, it typically does not flow through the flight geometry of the screws, because DDG and DDGS consist, on average, of 88% dry matter (particulates). 
     Farmers often use animal feed as part of a daily diet to provide energy, protein, minerals, and vitamins to livestock. These animal feed can be formed as grains, pellets, cubes, or tubs. In some conventional methods, the pellets, cubes or tubs are formed by compressing dried grains with the addition of binder materials or supplements that help the resulting product become dense and cohesive. Even with these additives, these animal feed products can fall apart or crumble. Thus, it may be desirable to produce a pellet, cube or tub having the highest protein and fat content, as naturally possible. A system and method is needed that produces a sufficiently dense animal feed product, such as pellets, cubes, and tubs, having the highest fat and protein content, without adding any binders, which are non-natural additives like molasses. 
     Some of the conventional animal feed producing methods require a heating or curing process applied to the product after it is formed in order to boil off the corn oil, which also lowers the protein level. Thus, there is a need to provide a method that does not require a heating or curing process after the pellet, cube, or tub is produced. 
     It may be desirable to provide a compression screw that is designed such that DDG or DDGS (dried grain) is capable of flowing through the screw geometry during the preparation process. It also may be desired to provide a compression screw system and method that produces animal feed in the form of grains, pellets, cubes or tubs, without the use of a heating or curing process. It may also be desirable to provide an animal feed producing system and method that does not use additives. 
     SUMMARY OF THE DISCLOSURE 
     The present teachings may satisfy one or more of the above-mentioned desirable features. Other features and/or advantages may become apparent from the description which follows. 
     In various embodiments, one or more screws are included in the compression screw assembly to create compression of the treated material. The compression can be created through the use of a wide variety of different kinds of screw. The screw can have a variety of configurations. For instance, the first screw and the second screw can be designed to rotate in a counter clockwise direction which creates a positive displacement pump that enables the grains to move forward in relation to the plurality of screws from the feed section to the tip section and allows the grains to be in constant contact with the hot surfaces of the plurality of screws and barrels. The moisture present in the grains is trapped within the grain, which helps to provide lubricity in the grains. The presence of the moisture trapped at a high temperature creates a lubrication property that enhances the grains ability to flow. 
     In various embodiments, the animal feed producing system provides restrictive areas created by the geometry of one or more screws to generate perpendicular compression, lateral compression, and/or a combination thereof. The perpendicular compression can be created by forcing the grain through tighter cavities of the flights and roots of the screw. The lateral compression can be created by changing the number of flights and/or the pitch of the flights of the screw. 
     In the following description, certain aspects and embodiments will become evident. It should be understood that the invention, in its broadest sense, could be practiced without having one or more features of these aspects and embodiments. It should be understood that these aspects and embodiments are merely exemplary and explanatory and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The skilled artisan will understand that the drawings described below are for illustrative purposes only. The drawings are not intended to limit the scope of the present teachings in any way. 
       Elements in the figures have not necessarily been drawn to scale in order to enhance their clarity and improve understanding of these various elements and embodiments of the invention. Furthermore, elements that are known to be common and well understood to those in the industry are not depicted in order to provide a clear view of the various embodiments of the invention, thus the drawings are generalized in form in the interest of clarity and conciseness. 
         FIG. 1  shows a perspective view of a compression screw assembly of the animal feed producing system according to the present teachings; 
         FIG. 2  shows a perspective view of the compression screw assembly of the animal feed producing system, illustrating a plurality of flights and roots of a first screw and a second screw in accordance with the present teachings; 
         FIG. 3  shows a perspective view of the compression screw assembly illustrating grains passing through a feed section of the plurality of screws in accordance with the present teachings; 
         FIG. 4  shows a perspective view of the compression screw assembly illustrating compressed grains at the plurality of flights and roots at the middle sections of the first screw and the second screw in accordance with the present teachings; 
         FIG. 5  shows a perspective view of the compression screw assembly illustrating the feed section and a plurality of middle sections in the plurality of screws in accordance with the present teachings; 
         FIG. 6  shows a perspective view of the compression screw assembly illustrating different set of flights and roots in the first and second screws of the animal feed producing system in accordance with the present teachings; and 
         FIG. 7  shows a perspective view of a feed tub according to the present teachings. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Reference will now be made to various embodiments, examples of which are illustrated in the accompanying drawings. However, these various exemplary embodiments are not intended to limit the disclosure. On the contrary, the disclosure is intended to cover alternatives, modifications, and equivalents. 
     Throughout the application, description of various embodiments may use “comprising” language, however, it will be understood by one of skill in the art, that in some specific instances, an embodiment can alternatively be described using the language “consisting essentially of ” or “consisting of.” 
     For purposes of better understanding the present teaching and in no way limit the scope of the teachings, it will be clear to one of skill in the art that the use of the singular includes the plural unless specifically stated otherwise. Therefore, the terms “a,” “an” and “at least one” are used interchangeably in this application. 
     Unless otherwise indicated, all numbers expressing quantities percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. In some instances, “about” can be understood to mean a given value ±5%. Therefore, for example, about 100° F., could mean 95-105° F. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
     In various embodiments, a system  100  can be configured to accommodate a wide range of compression screws with differing structures or geometries that create compression on the treated material. For example, in various embodiments, the apparatus  100  may include one or more screws.  FIGS. 1-6  depict various exemplary embodiments of compression screws that can be employed in apparatus  100 . The examples shown in  FIGS. 1-6  illustrate dual or twin screws. Those skilled in the art would recognize that a single screw, a triple screw, a plurality of screws, or a combination of a variety of screws may be used to compress the treated material. 
     In various embodiments employing twin or multiple-screw extruders, the screws can rotate in the same direction (co-rotating) or opposite direction (counter-rotating). The screw can include multiple sections that consist of non-intermeshing flights, fully intermeshing flights or a combination of both types of flights. In some embodiments, such screw extruders may be modular, and the screw design can be changed by rearranging the feeding, venting, and mixing elements along the screw shaft. 
     In various embodiments, the screw(s) are configured to include various mixing zones. In some embodiments, the system  100  employs a set of twin intermeshed screws having various mixing zones. In such an embodiment, the screw can be designed wherein each section has uniquely different sets of flight geometry to perform specific compression functions. For example, sections of the screw geometry can be configured to create perpendicular compression, lateral compression, or a combination thereof. Perpendicular compression can be created by forcing the treated material through tighter cavities of the flights and roots of the screw. Lateral compression can be created by employing a screw configured to have changes within different sections to the number of flights and/or the pitch of the flights. 
     As discussed above, because DDG and DDGS consist, on average, of 88% dry matter (particulates), it typically does not flow through the flight geometry of the screws  146 ,  148 . However, according to the present teachings, the particulate is pushed forward by a set of twin screws  146 ,  148  with the unique geometry as illustrated through  FIGS. 1-6 , as will be explained in more detail below, such that when positioned, timed, and rotated in specified direction, this creates an effect on the particulate that flows like a fluid under pressure. Namely, this means, for every rotation of the screw, the grain moves forward from a feed section towards the tip of the screw. With each rotation, it forces the grain through particular areas of the flights, as well as the root of the screws, where the grain is compressed. This point of compression is unrelated to the restriction created by a conventional die(s), located downstream of the tip of the screw. Rather, this compression occurs due to the design of the screw. 
     As illustrated in the exemplary embodiment of  FIG. 1 , the compression screw assembly  124  includes a plurality of screws  146 ,  148  and a plurality of barrels  132 . In the preferred embodiment, the plurality of screws  146 ,  148  includes a first screw  146  and a second screw  148 . The first and the second screws  146 ,  148  include, as shown in  FIGS. 1 and 5 , a feed section  140 , a plurality of middle sections  142 ,  144  and a tip section (not shown). The feed section  140  is adaptable to receive the grains  134  from the feeding hopper (not shown). The feed section  140 , the plurality of middle sections  142 ,  144  and the tip section (not shown) include a plurality of flights  138  and a plurality of roots  136 . The flights  138  are the section of the screws  146 ,  148  that pushes the material as the screw rotates. The roots  136  are located in the flow channel of the screws  146 ,  148 . 
     According to one example, the first screw  146  and the second screw  148  rotate in a counter clockwise direction which creates a positive displacement pump that enables the grains  134  to move forward in relation to the plurality of screws  146 ,  148  from the feed section  140  to the tip section and allows the grains  134  to be positioned in constant contact with the hot surfaces  150 ,  152  of the plurality of screws  146 ,  148  and barrels  132 , respectively. The moisture present in the grains  134  is trapped within the grain, which helps to provide lubricity in the grains. The presence of the moisture trapped at a high temperature creates a lubrication property that enhances the grains ability to flow when the grains  134  pass through a reduced surface area between the plurality of flights  138  and the plurality of roots  136 . The dry grains are sheared utilizing the sharp edges of the plurality of flights  138  and the roots  136 . 
     As illustrated in  FIGS. 1-6 , the screws  146 ,  148  are designed such that each includes uniquely different set of flight geometries to perform specific compression functions.  FIG. 1  illustrates the feed section  140  where the grains  134  are fed into the point of origin in the flights  138  of the screws  146 ,  148  installed within a screw assembly  124 . The flights  138  are the ridges of the screws  146 ,  148 , and the roots  136  are the bottom portions created between the flights  138  of the screws  146 ,  148 . In this example, the screws  146 ,  148  rotate in a counter rotating direction indicated by the solid-line arrow B (in  FIG. 1 ) which advances the grain  134  in a forward direction as shown by the solid-line arrow A in  FIG. 1 . 
     In other embodiments, the screws  146 ,  148  may co-rotate relative to each other. In some embodiments, the system  100  may be designed to include multiple sets of screws. For example, the system may be configured to include a set of screws that counter-rotates and another set of screws that co-rotates. In this exemplary screw assembly  124 , the screws  146 ,  148  are positioned such that their flights are parallel to each other so that one flight  138  from one screw  146  is situated very tightly between two flights  138  from the other screw  148 . 
     When positioned, timed, and rotated, for example, in a counter clockwise direction, this configuration, as the screws rotate, enables the grain  134  to be forced and compressed in several areas located on the flights and the roots of the screws, as illustrated in  FIGS. 1-6 . This creates a positive displacement pump that enables the grains  134  to move forward in relation to the plurality of screws  146 ,  148  from the feed section  140  to the tip section and allows the grains  134  in constant contact with the hot surfaces  150 ,  152  of the plurality of screws  146 ,  148  and barrels  132  respectively. The moisture present in the grains  134  is trapped within the grains which enhances the lubricity of the grains  134  as it passes through a reduced surface area between the plurality of flights  138  and the plurality of roots  136 . 
     As is shown more detail in  FIGS. 2-4 , the grains  134  are forced and compressed in several converging areas (indicated by the solid-line arrow C) located on the flights  138  and the roots  136  of the screws  146 ,  148 . The compression is created by the reduced surface between the plurality of flights  138  and the roots  136 . The edges of the flights  138  and roots  136  entrap the grain  134  within the area indicated by arrow C. As the grains  134  get compressed between the flights  138  and the roots  136 , a perpendicular compression (perpendicular to the flow of material which is from the feed section  140  to the tip section (not shown) of the screws  146 ,  148 ) is created. This perpendicular compression derives at least two beneficial effects (by design) on the material. First, one benefit is that, it creates a mechanical compression which generates mechanical heat which directly applies heat to the grains  134 . Secondly, the perpendicular compression changes the mechanical properties of the grains  134 , thereby making fine granules of the grains  134  that are substantially modulus such that these granules can be pushed into smaller orifices of die(s) (not shown) located downstream from the tip section (not shown) of the screws  146 ,  148 . Namely, the grains should be sufficiently fine so as to flow like a fluid. Further, this granule sized grains are bound into a dense form. In addition, each time the grains are compressed by the screws, air present in the grain is removed. This removal of air is one of the factors that allow the grains to be compressed into a more condense form in the die. 
     The edges of the plurality of flights  138  are intentionally designed to be very distinct and sharp so that they can shear the grains into a very fine particulate. Shearing is an effective way to apply heat to the grains  134 , because it self-generates heat during the process. An additional advantage of the animal feed producing system  100  is that, the plurality of screws  146 ,  148  rotates at higher rotation per minute (RPM) which increases the shear rate at an exponential rate by design which in turn reduces the operating cost of applying heat as well as breaks down the particulate to make it more compressible and bindable. 
       FIG. 5  illustrates a transition section from the feed section  140  to a more aggressive first middle section  142  to a less aggressive middle section  144 . In this transition section, more compression force occurs because more flights  138  are included per linear inch. This causes increased compression force and generates the production of more heat. Also, a backup region  156  is provided while the grain  134  is transitioning from this first middle section  142  to the second middle section  144 . The backup region  156  causes a backup of grain flow which creates lateral compression in the material similar to the compression created by forcing the grain through the smaller orifices in the die(s). In the backup region  156 , the grain slows down, because of the transition and grain backs up in the flow creating the lateral compression. As the grain advances to the less aggressive middle section  144 , the grain encounters less aggressive compression because fewer flights are provided within this section. 
       FIG. 5  illustrates another example of lateral compression provided by the design of the screw. In  FIG. 5 , the screws  146 ,  148  are designed such that there are changes in the number of flights and changes in the flight pitch. In  FIG. 5 , there are transitions from section  158  having fewer flights  138  spaced apart with a more forward angle of pitch  154  to an intermediary section  160 , then to a section  162  having more flights  138  with a far less forward pitch  164 . At the intermediary section  160 , the grain  134  experiences less flow and more compression forces applied onto the grain  134 . At section  162 , the flow of the grain increases. The transition from sections in the screws  146 ,  148  comprising different number of flights and flight pitches is another form of creating lateral compression. This compression force applied onto the grain is produced as a result of the screw design. Thus, the lateral compression can be performed onto the grain at regions of the screw which has nothing to do with having a conventional die with restrictive orifices positioned downstream from the plurality of screws  146 ,  148 . 
     In  FIG. 6 , as the grain travels through the points of compression, initially, the grain flows faster through section  158 , because the angle of pitch  154  is the most forward. Next, the grain slows down to its slowest speed through section  160 , because the angle of pitch is the least forward. Then, the grain speeds up through section  162 , but at a rate slower than in section  158 , because the angle of pitch  164  is less forward than the angle of pitch  154 . On the other hand, the material flows through section  162  faster than section  160 , because the angle of pitch  164  is more forward than the angle of pitch  166 . 
     Furthermore, section  160 , in  FIG. 6 , functions as an additional compression zone. Due to the generally flatness of the pitch  166  in section  160 , this backs up the flow of the grain into a back-up region  168  or a back-up region  170 , depending upon the direction of the grain. Backing up of the grain into back-up region  168  or back-up region  170  creates additional compression onto the grain. When the grain travels in the direction of arrow E, back-up region  168  is developed at positions  172  in front of section  158 . In contrast, when the grain travels in the direction of arrow F, back-up region  170  is developed at positions  174  in front of section  164 . 
     Thus, for example, when travelling in the direction of arrow E, the grain travels relatively fast through section  164 , then slows through section  160 , and speeds up in section  164 , but not as fast as in section  158 . As the grain travels through section  160 , the pressure created in the back-up region  168  is then released. As the grain advances through the twin screws, the grain may encounter several alternating stages of compression and release. 
     In general, the repeated compression and release as the grain transitions between sections of the multiple screws having different numbers of flights and/or pitches generates substantial shear stress on the grain. The shearing of the grain provides an economical and cost effective manufacturing process that does not require the addition of heat to maintain the process after the initial start-up. During the startup, as the motor and gearbox (not shown) begin to rotate the screws, a heating mechanism can be utilized to heat the barrel of the screws to approximately 220 F. After the grains start flowing through the screws, the heat of the barrel of the screws is turned off, because the shearing and compression forces generate a substantial amount of heat. 
     Thus, in the preferred embodiments, following the initial startup, the heat is turned off, no supplemental heat is added, and only the motor and gearbox are used to rotate the screws. Therefore, the process according to the present teachings creates a mechanical compression that generates mechanical heat which directly applies heat to the grains, which provides an economical advantage over conventional processes. 
       FIGS. 1-6  depict embodiments of different screw geometries having various restrictive areas to create the perpendicular compression (created by forcing grain through tighter cavities of the flights and roots) and the lateral compression (created by changing the number of flights and/or the pitch  154 ,  164  of the flights  138 ). Exemplary embodiments of the screws can have various configurations, such as uniform mixing sections, various mixing sections, a meshed section, a non-meshed section, a lateral compression section, a perpendicular sections, a back-up section, and a combination thereof. 
     Various embodiments of the animal feed producing devices  100  described herein enable the production of grains, pellets, cubes, and tubs without the addition of binders and fillers to avoid negatively affecting the nutritional value of the final product. Various embodiments of the distiller grain pellet producing devices produces a livestock feed material in the various forms of distiller dried grains having high shipping durability, high quality, and high nutritional value. The final product provides optimum nutritional value in a very compact and efficient form. Various embodiments extract and collect grain oils and moisture from the distiller dried grains during the production process. Various embodiments produce various structural forms, for example, in the form of pellets, cubes, or tubs having various configurations such as round, square, rectangular or oblong. 
     Various embodiments of the device provides a high-protein and fat content product, without additives, that can be spread onto the ground as livestock feed in the form of pellets or cubes and is capable of enduring various weather conditions. Various embodiments provide a method that does not require heating or curing after the products exit the device. 
     Optionally, oils, water, and vapors can be extracted from the distiller grain as it exits the device. 
     In various embodiments, after exiting the die (not shown), the distiller grain can be cut into nutritional pellets or cubes having a desired length or shape and discharged from the device into a container. The pellets may also be referred to as range cubes. 
     In various embodiments, in addition to producing pellets/cubes, device  100  may be employed to produce a final product shaped as large tubs having distiller grains compressed therein. Farmers often use animal feed supplements in the formed as solid blocks or solidified in tubs. The solid feed supplements are usually placed about the area in which the livestock grazes such that the livestock can feed on a free-choice basis. The tubs may weigh approximately 200 pounds and the density of the tubs limits the intake of the supplement, for example, to roughly 2-pounds of product per day, which allows the livestock eating the product to meet their daily requirements. 
     In an exemplary embodiment directed towards producing the solid tubs shown in  FIG. 7 , the final product of animal feed composition is dispersed into a container, such as a feed tub  700 .  FIG. 7  is a perspective view for such an exemplary feed tub container with the animal feed supplement  702  solidified therein. In this example, the feed tub has an open top end  704 , a closed bottom end  706 , and a surrounding side wall  708 . The open top end  704  is defined by an annular rim  710 . The rim  710  of the tub  700  may further include a downturned lip  712  to aid in grasping of the container by a user. 
     The tub  700  can be made in a variety of configurations having various sizes and shapes. For example, rectangular, square, oval, triangular and the like are suitable configurations for the feed tub. Furthermore, the tub can be quite deep or shallow, and its width and length dimensions can be varied to provide for the desired characteristic in such containers. 
     The feed tub  700  may be fabricated from plastic or any other suitable conventional material. The feed tub  700  is suitable for manufacture, for example, by injection molding, compression molding, extrusion molding, blow molding, thermoforming, and vacuum forming. 
     In use as a feed tub, the edible feed supplement is contained in the tub  700  and accessed by the livestock through an open top end  704  which exposes the edible feed supplement. While the opening  704  is shown as being generally circular, it may have any desired shape including without limitation polygonal and/or irregular peripheries. In various embodiments, the edible feed supplement has a texture that the livestock licks, thereby increasing consumption time. While embodiments of the present technology are described herein primarily in connection with a solid animal feed, the concepts are also applicable to other animal feed products having a high-fat content, with no additivities, such as dry grain, cubes, range cubes, calf cubes, mini-cubes, pellets, or any other suitable animal feed product. 
     In various embodiments, a wide variety of different kinds of pellets, cubes or tubs can be produced from various loose granular materials using substantially the same device. 
     The foregoing description of the preferred embodiment of the present teachings has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the present teachings not be limited by this detailed description, but by the claims and the equivalents to the claims appended hereto.