Patent Publication Number: US-8118582-B1

Title: Method and apparatus for producing biobased carriers from byproducts of biomass processing

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application Ser. No. 61/042,046 filed Apr. 3, 2008, which is hereby incorporated by reference in its entirety 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of biological and chemical product dispersion, and more particularly, to biobased carriers and the apparatus and method of manufacturing same for dispersal of themselves and of biological and chemical molecules carried thereby. 
     BACKGROUND OF THE INVENTION 
     Control of insect pests, rodents of non-desirable plants is typically achieved through the use of pesticides. Along with fertilizers, such pesticides, including fungicides, insecticides, rodenticides, plant growth regulators, enzymes and other similar products, are often dispersed via spherical, biobased pellets or granules that are used as carriers for such biological or chemical agents. 
     Biobased carriers made from renewable feedstocks include corn, soybean and wheat, but supplies and costs of such feedstocks can fluctuate greatly with the growing world market and the discovery of alternative uses therefor. For instance, corn cobs, which are used for the manufacture of the pesticide carrier, DG Lite®, are in increasing demand in the field of ethanol production. Consequently, the supply of corn cobs for DG Lite® is diminishing and the cost is rising. What is needed is an alternative source for biobased carriers for pesticides, fertilizers, and other applications. 
     SUMMARY OF THE INVENTION 
     The present invention relates to the production of custom designed spherical dry pellets (granules) from wet distillers grains and gluten feed and gluten meal, coproducts of dry-grinding/dry milling and wet milling, respectively, for fuel ethanol and starch production from starchy grain feedstocks like corn, sorghum (milo), and wheat, etc. and methods of their preparation (production) using a rotary drum dryer or rotating drum granulator. Custom designed spherical dry pellets here refers to pellets that can be produced to a custom desired diameter and internal structure as determined by their end use. Such pellets utilize liquid binders from corn ethanol production, vis-à-vis condensed distillers solubles or thin stillage, glycerol (glycerine) or polymer. When wet distillers grains are blended with condensed distillers solubles, the resultant product is dried distillers grains with solubles (DDGS). The aforementioned pellets could also be produced for the sole purpose of improving the bulk physical and flow properties of distillers grains with soluble (DDGS) sold as livestock feed or as carriers to disperse biological or chemical molecules such as agro-chemicals (pesticides for turf or crop applications and grain protectants, rodent baits, etc.) or enzymes. The invention contemplates both the apparatus and method for producing custom designed DDGS pellets as well as the pellets produced thereby. The method contemplates DDGS, gluten feed, gluten meal pellet production from wet distillers grains from corn-to-ethanol production using dry-grind processing, dry-fractionation, wet milling, or similar processes thereof. 
     In one embodiment, an apparatus for producing biobased carriers for dispersal of biological and chemical molecules includes a premixer having a cavity for receiving a coproduct of a wet biomass process and a binder and being operable to premix the coproduct and binder to produce a substantially homogeneous DDGS mixture; a high shear mixer having a receptacle for receiving the DDGS mixture and being operable to shear mix the mixture and produce very small DDGS particles; and, an agglomerator having an interior chamber sized and configured to receive and transform the DDGS particles into substantially spherical DDGS pellets. 
     It is an object of the present invention to provide an improved method and apparatus for producing biobased carriers for pesticides, fertilizers, and other applications. 
     Other objects and advantages will become apparent from the following description of the preferred embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an apparatus  10  for producing biobased carriers from byproducts of biomass processing in accordance with one embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of a nucleation enhanced particle  26  created by apparatus  10  for producing biobased carriers from byproducts of biomass processing of  FIG. 1 . 
         FIG. 3  is a schematic view of an apparatus  10  for producing biobased carriers from byproducts of biomass processing in accordance with another embodiment of the present invention. 
         FIGS. 4 and 5  are plan views of custom sized spherical pellets produced by apparatus  10  for producing biobased carriers from byproducts of biomass processing of  FIG. 3 . 
         FIG. 6  is a graph showing the particle size distribution for pellets  27  produced by apparatus  10  for producing biobased carriers from byproducts of biomass processing of  FIG. 3 . 
         FIG. 7  is a graph showing the particle size distribution for pellets produced in typical fuel ethanol plants. 
         FIG. 8  is a cross-sectional view of a pellet  27  created by apparatus  10  for producing biobased carriers from byproducts of biomass processing of  FIG. 1 . 
         FIG. 9  is a plan view of custom sized spherical pellets produced by apparatus  10  for producing biobased carriers from byproducts of biomass processing of  FIG. 3 , the data for which is shown in Table 2. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated herein and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described processes, systems or devices, and any further applications of the principles of the invention as described herein, are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     The present invention relates to the production of size specific dispersible pellets that can be used as carriers for both chemical and biological agents such as enzymes, pesticides, herbicides, fungicides, rodent bait poison and the like, animal vaccinations, animal medications and animal supplements, as well as for dispersing nutrients through this medium. Size specific here means that the pellets can be made to a desired, reasonably consistent, substantially spherical shape. Because the pellets can be made to custom size (500 to 6000 microns geometric mean size), they can thus possess a range of bulk physical properties that correlate to particle size. 
     Referring to  FIG. 1 , there is shown schematically an apparatus  10  for producing biobased carriers from byproducts of biomass processing in accordance with one embodiment of the present invention. Apparatus  10  generally includes a premixer  11 , a high shear mixer  12 , and an agglomerator  13 . Apparatus  10  may further include a cooling bed  15  and/or classifier  16 . Apparatus  10  generally operates to (1) blend in premixer  11  a combination of wet biomass processing coproduct  21  and a binder  22 , producing DDGS (dried distillers grains with solubles) paste  24 ; (2) shear mixing in high shear mixer  12  the DDGS paste  24  from premixer  11  to form nucleation enhanced particles (NEPS)  26 ; and, (3) agglomerating in agglomerator  13  the NEPS  26  from high shear mixer  12  to form desired sized biobased carriers or pellets  27 . 
     Wet biomass processing coproduct  21  contemplates substantially any wet coproduct from a biomass processing operation such as, and without limitation, those resulting from the fermentation of starchy grain or cellulose feedstocks to make alcohol (as in distilleries); the fermentation of lignocelluloses to make ethanol; and, the fermentation of pre-fractionated grain to make ethanol. As used herein, coproduct includes any of the intended, secondary and/or unintended products of the biomass processing operation. One preferred coproduct  21  is wet distillers grain (WDG)  32  (known in distilleries as brewers grain), which is a coproduct of fuel ethanol production from starchy grain feedstocks like corn, sorghum (milo), and wheat. Coproduct  21 , to be suitable for processing by apparatus  10 , is contemplated to be a wet feedstock having a 50-65% moisture content (wet basis). Some coproducts  21  may fall within this desired moisture content range directly after the operation that produced them, but others may require an additional drying step or the addition of a dry finely ground feedstock polymer, biomass, etc. to achieve the desired 50-65% moisture content range. Such additional drying step is performed by any suitable dryer operable to dry the coproduct to the desired moisture content and may include a rotating drum dryer and/or a fluidized conveyor bed. 
     Binder  22  is contemplated to include condensed distillers solubles (CDS) (also known as “the syrup”), thin stillage or glycerol (glycerine) or polymer. Other binders may be used instead, so long as they achieve the desired internal granule structure, nucleation, coalescence and layering during pellet growth, as described herein. One preferred binder is the CDS, which flows better when heated. One embodiment of apparatus  10  therefore includes a heater  35  operable to heat at  36  the CDS so it will readily flow into premixer  11 . 
     Premixer  11  is a horizontal, trough type mixer having a cavity (not shown) with one or more stirring arms, screws, paddles or the like operable in the cavity to receive and evenly mixing target materials to a powder or paste state. The output DDGS paste  24  has a granulated cookie-dough or wet sand-type consistency and is directed by a chute device  28  or other suitable structure or positionment to the inlet (not shown) of high shear mixer  12 . Premixer may comprise any other suitable device capable of receiving and mixing the received materials to a substantially homogeneous state. 
     In one embodiment, high shear mixer  12  is a commercially available high shear mixer which, upon receipt of DDGS paste  24  in a cavity or similar mixture receiving receptacle, mechanically declumps and pulverizes it, or shear mixes it. That is, high shear mixer  12  breaks up the DDGS paste constituents to such a small degree that very small DDGS particles are formed that consist of coproduct particles  21  that are coated with a thin film of binder CDS  22  ( FIG. 2 ). These resulting DDGS particles are nucleation enhanced particles (NEPS)  26 , which are directed out of high shear mixer  12  via a suitable chute device  29  or other suitable structure or positionment to the inlet (not shown) of agglomerator  13 . The NEPS  26  are in the range of between about 300 to 500 microns in diameter. While they could be larger, the high stress shearing action of high shear mixer  12  will typically uniformly create NEPS in this range, which contributes to the particular agglomeration and resulting pellet production of the present invention. 
     Alternative embodiments are contemplated ( FIG. 3 ) wherein high shear mixer  12   a  comprises a trough type mixer having high-shear means that includes one or more stirring arms, screws, paddles or the like, or any similar device. The high-shear device also including a screen  30  across which the DDGS paste  24  is forcibly moved or rubbed (by an arm, screw or paddle or the like) to shear mix the subject paste  24 . DDGS paste  24  particles sufficiently broken down thereat, that can pass through the mesh size of screen  30 , constitute the desired NEPS and pass out of high shear mixer  12   a  and are directed via chute device  29  to agglomerator  13 . 
     Alternative embodiments are contemplated wherein high shear mixer  12  comprises any suitable device operable to shear mix the DDGS paste  24  and convert it into NEPS  26 , including, for example a device providing ultrasonic cavitation to the paste  24 , with or without additional rotor-stator mixing structure. 
     Agglomerator  13  comprises a rotary drum dryer  39 . Rotary drum dryer  39  generally includes a cylindrical metal reactor, or drum  40  that is inclined at its inlet end  41  slightly from the horizontal. Drum  40  defines an interior chamber  44  sized and configured to receive and manipulate the NEPS  26 . A heat and blower source (not shown) located at one end of drum  40  provides a heat flow to raise the temperature of and dry NEPS  26  as they pass through drum  40 . The heat flow may be either cocurrent with or countercurrent to the direction of flow of NEPS  26  toward the drum outlet  42 . As drum  40  rotates about its axis  43 , the NEPS  26  therein are conveyed through the drum toward the outlet  42  at the lower end  49  of the drum. Lifters  45  extending inwardly on the inside of drum  40  raise the NEPS  26 , carrying them to near the top of the drum  40  before allowing them to fall through the, heated gas flowing therethrough. The drying heat is contemplated to range from 400° F. to 1000° F., but this value may vary depending on whether the heat flow is cocurrent or countercurrent, as well as on the other parameters attendant to the desired size of the resulting DDGS pellets  27 . 
     The drum rotation and heat flow act on the NEPS  26  to cause a nucleation, coalescence, layering and drying of the NEPS  26 . That is, two or more NEPS  26 , with their still wet outer film coating of CDS  33  coalesce to form a single body and, as drum  40  with its lifters  45  rotates, numerous such bodies (as at  48 ) form, each comprising multiple NEPS  26 . When these bodies  48  repeatedly rotate into a ball, they grow in diameter as they move toward outlet  42  until they harden and dry to form spherical pellets. In another embodiment, drum  40  is a drum granulator, having no lifters, which acts somewhat differently upon the coalescing bodies  48  of NEPS, still acting, however, to continuously roll the bodies into compacted, spherical DDGS pellets. Ultimately, the coalesced groups of NEPS  26  have formed individual, substantially equal and consistent diameter DDGS pellets  27  that comprise numerous, densely packed balls of the (now dry) wet biomass processing coproduct  21 , each coated (within each pellet  27 ) with a film (or larger coating) of binder  22 . ( FIG. 8 ) Once the binder  22  has dried, coalescence and layering of the NEPS  26  (that is, of coproduct  21  and binder  22 ) has stopped, and the DDGS pellet  27  has reached its maximum size. Thus, the final size of DDGS pellet  27  can be substantially predetermined by: varying the drying parameters of agglomerator  13  (the rotational speed and number of revolutions of the drum  40  and the speed, direction and temperature of heat flow therethrough); the inclination of drum  40 ; the number and configuration of lifters  45  within drum  40  (or absence of the lifters, as in a drum granulator); and, the composition and amount of the binder  22  (here, condensed distillers solubles (CDS)  33 ) and, to a lesser extent, of the coproduct  21  (here, wet distillers grain (WDG)  32 ). Thus, for example, the greater the percentage of the binder (CDS  33 ) versus the starting biomass coproduct (WDG  32 ), the longer it will take the coalescing NEPS  26  to dry, and the more NEPS  26  will join together as a pellet and the larger the diameter of the pellet  27 . 
     It is noted that while a faster drying time may achieve a certain pellet diameter by specifically terminating further mutual adhesion and coalescence, such earlier than average drying time may leave the core coproduct  21  (e.g. wet distillers grain (WDG)) with more moisture than desired, especially if drum granulators with no heat addition are used. Additional heating, such as before cooling bed  48 , by any suitable means is contemplated to remove additional moisture, as desired. Alternatively, one or more of the other factors affecting pellet size can be adjusted to attain both desired pellet size and overall moisture content. In one embodiment, pellets of 10% moisture content or below are desired for normal feed augmentation. 
     Another characteristic of forming DDGS pellets  27  from NEPS  26  is an increased density due to the coalescing of particles by rolling action to form a pellet. Each such rotation more closely packs the nucleated NEPS by layering together. In addition, the resulting, substantially spherical, more densely packed DDGS pellets exhibit superior flow characteristics over less dense and more irregularly shaped DDGS materials. 
     Upon exiting agglomerator  13 , the DDGS pellets  27  are cooled using fluidized cooling bed  15 , a rotary drum cooler (not shown) or other suitable cooling device. Thereafter, the DDGS pellets  27  exit the cooler  15  and pass through a suitable classifier  16  to sort the pellets into their various size categories. In one embodiment, classifier  16  is gravity table, a vibrating device that sorts particles into various size categories. In another embodiment, classifier  16  is a vibrating screening device of multiple, stacked and increasing mesh size screens with or without elutriation to remove fine particles. The smaller the pellet, the farther down it falls through the decreasing screen hole sizes until it exits by virtue of failing to pass though a particular screen size. 
     In one embodiment, apparatus  10  operates to produce custom designed biobased carriers from wet biomass processing coproduct  21  and binder  22  as follows: wet distillers grains (WDG)  32  and condensed distillers solubles (CDS)  33  are admixed at a percent weight/weight ratio of between 70:30 and 85:15 to premixer  11 . Premixer  11  completes the preliminary mixing and outputs the resulting blended mixture as DDGS  24  paste into high shear mixer  12 . The high shear mixer  12  shear mixes the DDGS paste  24 , producing nucleation enhanced particles (NEPS)  26 , which are then directed into agglomerator  13 . Agglomerator  13  rotates and injects a drying airflow, which results in mutual coalescence, nucleation and layering of the coproduct  21  and binder  22  (growth) until the binder  22  dries enough to cease adhering NEPS  26  together into a spherical pellet. 
     In one embodiment, the process of the present invention is ideally suited for application in existing ethanol plants that are most ideal, least cost centers for production of custom designed pellets. This is because in ethanol plants, there exists the feedstock, wet distillers grains and solubles (condensed distillers solubles or thin stillage) for pellet production. Additionally, rotary drum dryers, one of the major equipment units that is needed for simultaneous agglomeration and drying of the pellets, are available in fuel ethanol plants for drying wet distillers grains, gluten feed and gluten meal. Grain ethanol plants (dry grind, dry milling and wet milling) are thus preferred sites for pellet production from wet distillers grains with solubles. In addition, cost savings would be realized in reduced wet feedstock transportation costs and in sharing already existing handling infrastructure in the fuel ethanol plants. 
     Results of bench-scale studies using the methodology described herein are shown in the scanned images of  FIGS. 4 and 5 . Specifically, custom designed spherical pellets were produced using wet distillers grains and with condensed distillers solubles (CDS) or thin stillage (TS) as a binder and for duration in the agglomerator  13  at 30 minutes and 60 minutes, as shown. The resulting custom sized spherical pellets (granules) are shown sorted to sieve  4 - 6  and sieve  8 , respectively. 
     The present invention contemplates production of the DDGS pellets from coproducts from bioprocessing of any and all starchy grains, as well as feed meal from oil feeds, such as soybean meal, cotton seed meal, sunflower meal, gluten feed, gluten meal, and the like. 
     The term DDGS is used herein for the referenced resulting mixture, regardless of the composition of the initial wet biomass processing byproduct  21 . 
     Referring to Table 1 below, there are shown physical properties tests for two different pellets produced in accordance with the present invention (Rows 2 and 3), which show more highly dense pellets than those from DDGS produced in typical fuel ethanol plants (Row 1) wherein wet distillers grain (WDG) is simply mixed with condensed distillers solubles (CDS) in a trough mixer and then dried in a rotary dryer. The first row represents control values from DDGS produced in the normal operation from corn fuel ethanol plants. The pellets produced in accordance with the present invention (Rows 2 and 3) and the control pellets (row 1) were all produced from the same WDG and CDS source. 
     The custom designed pellets of the present invention achieve particle size diameters as high at 3300 microns compared to 910 microns ranges for regular DDGS. As shown in  FIG. 6 , the particle size distribution for pellets  27  of the present invention is skewed to the left, showing that the majority of the pellets were forced toward large sized pellet formation by the present process. Also, this reduced the spread of particle sizes, thus increasing uniformity. The particle size distribution graph for typical DDGS pellets (i.e. row 1 of Table 1) will typically comprise a bell curve distribution ( FIG. 7 ). 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Physical properties of custom designed biobased pellets from DDGS 
               
            
           
           
               
               
               
            
               
                   
                   
                 Bulk Physical Properties 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Particle density 
                 Bulk density 
                 Geometric mean 
               
               
                 Row 
                 Treatments 
                 (kg/m3) 
                 (kg/m3) 
                 diameter (pm) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1 
                 DDGS (from  
                 1290.5 
                 458.1 
                 910 
               
               
                   
                 typical ethanol  
                   
                   
                   
               
               
                   
                 plant) 
                   
                   
                   
               
               
                 2 
                 WDG:CDS - 
                 1309.0 
                 529.3 
                 3300 
               
               
                   
                 80:20 (% w/w) 
                   
                   
                   
               
               
                 3 
                 WDG:TS - 
                 1315.0 
                 480.7 
                 3160 
               
               
                   
                 80:20 (% w/w) 
               
               
                   
               
            
           
         
       
     
     In another bench-trial using the procedure and apparatus of  FIG. 3 , the resulting DDGS pellets  27  exhibited the characteristics shown in the fourth column of Table 2 below. The coproduct  21  was WDG; the binders were all CDS; and, the resulting pellets tested were sizes 8 and 12 sieve. The values compared in Table 2 to the subject DDGS carriers of the present invention are for currently available mineral and biobased pesticide carriers. As shown in Table 2, the DDGS carriers of the present invention had higher bulk density, comparable resistance to attrition and favorably low moisture content. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 A comparison of the physical properties of carriers. 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Mineral 
                 Biobased 
                 DDGS 
               
               
                   
                   
                 Carriers 
                 Carriers 
                 Carriers 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Bulk density (kg/m 3 ) 
                 512-577 
                 336 
                 523.8 
               
               
                   
                 Moisture content (%) 
                  3-10 
                 8-10 
                 4.9 
               
               
                   
                 Resistance to attrition (%) 
                 75-90 
                 &gt;99 
                 84-93 
               
               
                   
                 Angle of repose (°) 
                 NA 
                 NA 
                 31.5 
               
               
                   
                   
               
            
           
         
       
     
     The pellets produced in these tests ( FIG. 9 ) used CDS as a binder and produced spherical pellets with a favorable range of physical particle and bulk characteristics. 
     One of the significant benefits of apparatus  10  is that it enables production of substantially consistent spherical biobased carrier pellets of any desired size within a broad size range. Table 2 shows typical desired particle sizes for common carrier applications. Agree and statement is suitable. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Typical particle sizes of carriers. 
               
            
           
           
               
               
               
            
               
                   
                 Application: 
                 Size range (microns): 
               
               
                   
                   
               
               
                   
                 Aerial 
                 2360-4750 
               
               
                   
                 Lawn and Garden 
                 1180-2760 
               
               
                   
                 In-furrow 
                 300-710 
               
               
                   
                 Typical agricultural broadcast 
                 300-710 
               
               
                   
                 Special pneumatic distribution 
                 180-425 
               
               
                   
                 DDGS granules (size 8) 
                 2380-3350 
               
               
                   
                 DDGS granules (size 12) 
                 1410-2380 
               
               
                   
                   
               
            
           
         
       
     
     The present invention is targeted at producing dry dispersible pellets from wet distillers grains and using condensed distillers solubles, thin stillage or a glycerol (glycerine) or polymer as a binder. The pellets are capable of carrying biologically and chemically active molecules which can be easily deployed and released to their activity sites. The release of the chemical or biological agents can be controlled by the design of the pellet&#39;s internal structure using a polymer matrix additive such as chitin, and the like. The pellets possess better granular properties, namely bulk physical and flow properties than the initial wet feedstock or DDGS. The aforementioned invention can also be used to produce consistent uniform sized spherical pellets with improved bulk physical and flow properties. 
     Apparatus  10  contemplates its input raw material to be any wet coproduct from a biomass processing operation. Alternative embodiments are contemplated wherein the input raw material is not a coproduct, but instead comprises an unprocessed biomass, such as ground dry biomass, wood saw dust, starch or other polymer. Also, chemical and/or biological matter may be added with the initial raw materials (coproduct  21  and binder  22 ) to modify the internal structure of the pellets for the purposes of their end use as biobased carriers of chemical and biological active ingredients. It is contemplated that the active ingredients of chemical or biological origins that are carried and dispersed by the biobased carrier mentioned herein can be added at the premixer  11  with other polymers used for controlling its release. In some cases it is contemplated that the DDGS pellets  27  will first be produced and the active chemical or biological ingredients will then be applied to the pellets using methods known in the industry such as spray coating, drum coating, and the like. Other applications are contemplated, such as for active ingredients of biological origin, wherein the active ingredient is inoculated into or onto the pellet which then grows on the pellet in the right temperature and relative humidity environments. Based on the description herein, some of the active ingredients will be either on the surface of the pellet (or granule) for immediate release or within the pellet for timed release. 
     Alternative embodiments are contemplated wherein the premixer  11  and high shear mixer  12  are combined into a common unit that receives and initially mixes the coproduct  21  and binder  22  and then performs a high shear mixing action to the premixed coproduct and binder material. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.