Abstract:
The present invention is directed to improved preconditioners ( 12 ) especially useful for the production of high meat-content pet foods. The preconditioners ( 12 ) include an elongated housing ( 16 ) with one or more elongated, axially rotatable mixing shafts ( 18, 20 ) therein, each having a plurality of outwardly extending mixing elements ( 42, 44 ). The preconditioner ( 12 ) is provided with apparatus ( 56 ) for directing relatively large quantities of heated non-steam gas into the preconditioner ( 12 ) in lieu of most or all of the steam normally used with preconditioners. This serves to heat material passing through the preconditioner ( 12 ) without the addition of substantial moisture.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of U.S. patent application Ser. No. 12/787,302, filed May 25, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/767,547, filed Apr. 26, 2010, both of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with improved preconditioners for use with downstream extruders, wherein the majority or all of the thermal energy input to the preconditioner is in the form of heated non-steam gas, such as ambient air. More particularly, the invention is concerned with such preconditioners, as well as methods of processing using the preconditioners, wherein high meat content pet feeds can be produced without creation of excess moisture conditions within the feeds, which can plug conventional preconditioners. 
     2. Description of the Prior Art 
     A large volume of pet feeds, such as cat or dog feeds, is produced by extrusion. Generally speaking, a dry ingredient mixture containing respective quantities of grain protein, starch, and fat is fed to an extrusion system which serves to fully cook and form the starting ingredients as a complete feed. The extrusion systems typically include a preconditioner, such as that shown in U.S. Pat. No. 4,752,139, which serves to moisturize and partially pre-cook the starting ingredients, as well as a downstream extruder. During processing with such preconditioners, steam and/or water are injected into the preconditioner housing, and mixing shafts supporting paddles are rotated at a constant speed and at a preset rotational direction. 
     The extruder includes an elongated barrel presenting an inlet coupled with the outlet of the preconditioner, and a downstream, restricted orifice die. One or more elongated, axially rotatable, helically flighted screws are situated within the barrel in order to move the preconditioned ingredients along the length of the barrel, toward and through the outlet die. Generally, the extruder serves to heat and subject the ingredients to increasing levels of shear within the barrel, with the final cooking and shaping occurring at the die. A rotating knife is normally used to cut the extrudate into an appropriate size. 
     Premium pet food manufacturers increasingly wish to add fresh meat to the dry ingredients during extrusion processing. These types of feeds command higher prices in the marketplace. In the past, the practical maximum level of meat addition was about 40% by weight. If greater quantities of meat were used, the preconditioner would tend to plug up, making processing difficult or impossible. 
     A new generation of preconditioners is disclosed in U.S. Pat. No. 7,448,795. These preconditioners include an elongated housing with a pair of internal mixing shafts with outwardly extending paddles. The shafts are powered by individual variable speed drive mechanisms allowing infinite adjustment of the rotational speed of the shafts, as well as the ability to rotate the shafts in the same or opposite directions. With these improved preconditioners, much higher levels of meat can be added to feed formulations, on the order of 40-60% of the dry ingredients, by weight. However, it has been found with such high-meat mixtures that the native moisture content of the meat precludes addition of enough steam to the preconditioner to achieve the desired levels of cook. Thus, while higher meat quantities can pass through the preconditioner without plugging, insufficient cook levels are achieved for proper downstream extrusion. 
     There is accordingly a need in the art for modified preconditioners, extrusion systems, and methods which cannot only handle high meat feeds, but also achieve a sufficient level of cook for efficient downstream extrusion. 
     Animal feed products can also be produced using pellet mills or pellet presses. These devices are greatly different than extrusion cookers, and do not include an elongated barrel with internal(s) which are axially rotatable and helically flighted. Moreover, these types of processes use very little steam and typically have a maximum recipe moisture limitation over about 18%. If greater moisture levels exist, the processes generally will not work. 
     The following references are pertinent: U.S. Pat. Nos. 4,028,030, 4,659,299, 4,812,324, 4,929,163, 6,344,228, 7,396,151, and 7,404,262; U.S. Published Applications: 2006/0251791, 2006/0093718, 2008/0075808, 2008/0260913, 2008/0118607, 2008/0069926, 2008/0069927; and EP Publications: 1027836 and 0610789. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems outlined above, and provides an improved preconditioner especially adapted for use with a downstream extruder. Broadly speaking, the preconditioner is operable to precondition material for subsequent processing thereof by heating and/or moisturizing the material and achieving a level of cook of the material. The preconditioner includes an elongated housing presenting a material inlet and a material outlet and having at least one elongated, rotatable mixing shaft therein. Apparatus is coupled with the preconditioner housing in order to introduce non-steam heated gas into the housing during passage of material therethrough, in order to intimately mix the gas with the material as a partial or complete replacement for steam and/or water conventionally used with preconditioners. 
     As used herein, “non-steam heated gas” refers to a gas, which is not wholly in the form of steam and preferably having an absolute humidity of up to 50%, more preferably up to about 25%. The gas may be a mixture of gases such as air or a relatively pure gas. The non-steam heated gas may contain some steam, up to about 25% by volume, and more preferably up to about 15% by volume. Most preferably, the heated gas contains essentially no steam, so that the total heat input to the preconditioner consists essentially of the hot gas. In practice, the gas is ambient-derived air free of steam at any ambient absolute or relative humidity and is heated to a level of from about 150-750° C., more preferably from about 350-700° C., and most preferably from about 450-600° C. 
     The gas introduction apparatus is preferably in the form of a burner and a blower operably coupled with the preconditioner housing. More generally, the gas introduction apparatus has a powered heating device providing an extra heat input derived from the operation of the device but not from the preconditioning/extrusion process itself. Thus, the gas introduction apparatus does not wholly rely upon recovered heat, as in the case of recycling of exhaust gasses or effluent gasses from a pellet cooler or the like. Such heat recovery expedients do not provide sufficient quantities of highly heated gas required in the present invention. Examples of powered heating devices include fuel-fired burners, radiant heaters. 
     Advantageously, the apparatus is designed to introduce relatively large volumes of gas into the housing, normally at a cubic meter/hour rate of from about 60-240 times (more preferably from about 125-200 times) the cubic meter volume of the preconditioner housing. Thus, if a given housing had a volume of 100 cubic meters, the broad range of introduction rates would be from about 6,000-24,000 cubic meters/hour. In order to obtain adequate preconditioning, it is also desired to add from about 100,000-200,000 (more preferably from about 140,000-180,000) kJ/hr of thermal energy to the preconditioner. In the context of the present invention, at least about 60%, and more preferably from about 70-100%, of the total thermal energy input is derived from the introduced non-steam hot gas. The preferred preconditioner of the invention is also very efficient in terms of energy transfer. That is, the preconditioner should be operable to transfer from about 60-90%, and more preferably from about 80-88%, of the total thermal energy input to the material being preconditioned. 
     In particularly preferred forms, the preconditioner should be of the type described in U.S. Pat. No. 7,448,795 incorporated by reference herein. Such a preconditioner includes a pair of elongated, laterally spaced apart, axially rotatable shafts each having a plurality of outwardly extending mixing elements or paddles, with a drive assembly operably coupled with the shafts and capable of individually adjusting the speed and/or rotational direction of the shafts during passage of material through the preconditioner. The drive assembly is advantageously in the form of a pair of variable speed drives so that the respective shaft speeds can be infinitely varied. Also, the mixing elements of the shafts are axially offset and intercalated for maximum material mixing and self-wiping of the shafts and mixing elements. 
     The invention also provides extrusion assemblies made up of a preconditioner as described above with a downstream extruder, the latter including an elongated barrel separate from the preconditioner housing and having an inlet and a restricted orifice die outlet. At least one (and preferably two) elongated, helically flighted, axially rotatable screw assemblies are located within the barrel and are operable to move the material from the inlet toward and through the outlet. In such extrusion assemblies, the preconditioner material outlet is coupled with the barrel inlet. During extrusion, the material being processed is subjected to increasing levels of temperature, pressure and shear in order to create formed and cooked final extrudates. 
     The preconditioners and extrusion assemblies of the invention are particularly suited for the production of food or feed products having relatively high quantities of meat therein. A typical example would be pet foods having large amounts of fresh, uncooked meat as a part of the starting recipe. Thus, the invention provides a method for extruding such products by providing a starting material including respective quantities of protein, starch, and fat and containing at least about 30% by weight meat (more preferably, at least about 40% by weight, and most preferably from about 42-60% by weight), based upon the total weight of the dry ingredients taken as 100% by weight. This starting material is then preconditioned by passing the material through a preconditioner in accordance with the invention with the simultaneous introduction of non-steam heated gas into the preconditioner housing. This serves to heat and at least partially cook the material before downstream extrusion. Generally, the material leaving the preconditioner has a moisture content of from about 25-30% by weight, wet basis. 
     The protein content of the starting material is typically derived from a variety of sources, such as the meat as well as grain proteins (e.g., soy, wheat, corn, milo). The total protein content is usually between about 5-60% by weight, more preferably from about 20-45% by weight. The starch content of the starting feed material would normally be from about 0-45% by weight, whereas the fat content would usually be from about 5-25% by weight, where all of the foregoing percentages are based upon the total weight of the material taken as 100% by weight. The moisture content of the product exiting the extruder is typically in the range of from about 30-35% by weight, wet basis. 
     The meat content of the starting material may be selected from the group consisting of beef, pork, mutton, horse, venison, fowl, fish, and mixtures thereof, but in principle any meat could be used. 
     While the preconditioners of the invention make use of heated non-steam gas as a thermal energy source, other types of thermal energy may be used as well. For example, steam could be introduced into the preconditioner along with the non-steam gas, but it is preferred that at least about 50%, and more preferably at least about 70%, of the thermal energy to the preconditioner be derived from the non-steam gas. This is particularly the case where high meat concentration starting materials are used, and in many of these instances, the preconditioning is carried out without the introduction of water or steam into the preconditioner housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially schematic side view of a preconditioner in accordance with the invention, operably coupled with a downstream extruder; and 
         FIG. 2  is a vertical sectional view of the preconditioner illustrated in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, an extrusion system  10  is illustrated in  FIG. 1  and generally includes a preconditioner  12  operably coupled with a downstream extruder  14 . The system  10  is operable to receive starting materials with initial preconditioning and ultimate extrusion to create highly cooked, finished food or feed products. 
     The preconditioner  12  is of the general type disclosed in U.S. Pat. No. 7,448,795, and includes an elongated mixing vessel or housing  16  with a pair of parallel, elongated, axially extending mixing shafts  18  and  20  extending along the length thereof. The shafts  18 ,  20  are operably coupled with individual, identical variable drive devices  22 , the latter in turn connected with a digital controller (not shown). 
     In more detail, the housing  16  has an elongated, transversely arcuate sidewall  26  presenting a pair of elongated, juxtaposed, intercommunicated chambers  28  and  30  (see  FIG. 2 ), as well as a material inlet  32  and a material outlet  34 . The chamber  28  has a larger cross-sectional area than the adjacent chamber  30 , as is readily apparent in  FIG. 2 . The sidewall  26  has access doors  31  as well as conventional water and/or steam injector assemblies (not shown) along the length thereof. The opposed ends of the housing  16  have end plates  38 ,  40 , as shown. 
     Each of the shafts  18 ,  20  has a plurality of radially outwardly extending mixing elements  42  and  44 , which are designed to agitate and mix the starting materials fed to the preconditioner, and to convey the material from inlet  32  toward and out the outlet  34 . The elements  42  are axially offset relative to the elements  44  and the elements  42 ,  44  are in intercalated (i.e., the elements  42  extend into the cylindrical operational envelope presented by shaft  20  and elements  44 , and vice versa). Although the elements  42 ,  44  are illustrated as being substantially perpendicular to the shafts  18  and  20 , the invention is not so limited; rather, the elements  42 ,  44  are adjustable in both length and pitch at the discretion of the user. Again referring to  FIG. 2 , it will be seen that the shaft  18  is located substantially along the center line of chamber  28 , and that shaft  20  is likewise located substantially along the center line of the chamber  30 . 
     The drives  22  are identical in terms of hardware, and each includes a drive motor  46 , a gear reducer  48 , and a coupling assembly  50  serving to connect the drive to a corresponding shaft  18  or  20 . The drives  22 ,  24  also have variable frequency devices  52 , which are designed to permit selective, individual rotation of the shafts  18 ,  20  in terms of speed and/or rotational direction independently of each other. In this way, each of the shafts  18 ,  20  can be individually rotated through an infinite range of speeds. 
     In preferred forms, the preconditioner  12  may be conventionally supported as indicated at  54 , or if desired may be mounted on weighing devices such as load cells which are coupled with the digital controller. The use of load cells permits rapid, on-the-go variation in the retention time of material passing through the housing  16 , as described in U.S. Pat. No. 6,465,029, incorporated in its entirety by reference herein. 
     The use of the preferred variable frequency drives  22 ,  24  allow high-speed adjustments of the rotational speeds of the shafts  18 ,  20  while avoiding any collisions between the intercalated mixing elements  42 ,  44 . 
     The preconditioner  12  further includes apparatus  56  for the introduction of non-steam hot gas into housing  16 . In this case, the apparatus  56  includes a fuel-fired burner  58  operably coupled to an inlet  60  on housing  16 . This apparatus thus serves to heat and introduce large volumes of ambient air into housing  16  where, owing to the rotation of the mixing shafts  18  and  20 , the hot air comes into intimate thermal contact with the material being processed. Thereafter, the air passes outwardly through downstream vent  62 . It will thus be observed that the flow of hot air is in co-current relationship relative to the flow of material being processed within housing  16 . Of course, countercurrent flow of such hot air could also be employed. 
     The extruder  14  is itself entirely conventional and well known to those skilled in the art. Generally speaking, an extruder of this type includes an elongated, multiple-section barrel with a material inlet and a restricted orifice die outlet. One or more elongated, axially rotatable, helically flighted screw assemblies are located within the barrel and serve to subject the preconditioned material from preconditioner  12  to increasing levels of temperature, pressure, and shear to create the final products. 
     The following examples set forth preferred apparatus and methods in accordance with the invention. It is to be understood, however, that these examples are provided by way of illustration only, and nothing therein should be considered as a limitation upon the overall scope of the invention. 
     EXAMPLE 1 
     In this example, a series of test runs were carried out using the modified preconditioner of the invention, as illustrated in  FIGS. 1-2  and including the apparatus  56  for the introduction of hot ambient air into the preconditioner housing. The preconditioner was coupled with a downstream twin screw extruder (Wenger Model TX 760). The extruder is of the type disclosed in U.S. Pat. No. 7,521,076, incorporated by reference herein. 
     In each run, standard dog food dry recipe ingredients were fed to the preconditioner and extruder, along with fresh chicken meat in the amounts set forth below. In Runs 1-3, steam was added to the preconditioner, whereas in Runs 4-5, no steam was used. 
     
       
         
               
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Product 
               
             
          
           
               
                   
                 Pet Food 
                 Pet Food 
                 Pet Food 
                 Pet Food 
                 Pet Food 
               
             
          
           
               
                   
                 Run Number 
               
             
          
           
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
               
             
          
           
               
                   
                 Extruder Model 
               
             
          
           
               
                   
                 TX760 
                 TX760 
                 TX760 
                 TX760 
                 TX760 
               
             
          
           
               
                   
                 Preconditioner Model  
               
             
          
           
               
                   
                 Units 
                 450 HIP 
                 450 HIP 
                 450 HIP 
                 450 HIP 
                 450 HIP 
               
               
                   
               
             
          
           
               
                 Dry Recipe Parameters 
                   
                   
                   
                   
                   
                   
               
               
                 Dry Recipe Moisture Content  
                 % wb 
                 5.53 
                 4.53 
                 4.53 
                 4.53 
                 4.53 
               
               
                 Dry Recipe Temperature 
                 ° C. 
                 11 
                 11 
                 13 
                 11 
                 11 
               
               
                 Dry Recipe Rate 
                 kg/hr 
                 1000 
                 1000 
                 1000 
                 1000 
                 1750 
               
               
                 Burner Parameters 
                   
                   
                   
                   
                   
                   
               
               
                 Combustion Air 
                 m3/hr 
                 78 
                 78 
                 78 
                 78 
                 78 
               
               
                 Burner Sizing 
                 kJ/hr 
                 263764 
                 263764 
                 263764 
                 263764 
                 263764 
               
               
                 Ambient Air Temperature 
                 ° C. 
                   
                   
                   
                 34 
                 34 
               
               
                 Inlet Air Temperature 
                 ° C. 
                   
                   
                   
                 542 
                 538 
               
               
                 Exit Air Temperature 
                 ° C. 
                   
                   
                   
                 56 
                 56 
               
               
                 Preconditioner Parameters 
                   
                   
                   
                   
                   
                   
               
               
                 Large Shaft Speed/Rotation 
                   
                 80 F 
                 80 F 
                 80 F 
                 80 F 
                 80 F 
               
               
                 Small Shaft Speed/Rotation 
                   
                 800 R 
                 800 R 
                 800 R 
                 800 R 
                 800 R 
               
               
                 Steam Flow to Preconditioner 
                 kg/hr 
                 78 
                 83 
                 70 
                 0 
                 0 
               
               
                 Adjusted Steam Flow to 
                 kg/hr 
                 78 
                 83 
                 83 
                 0 
                 0 
               
               
                 Preconditioner 
                   
                   
                   
                   
                   
                   
               
               
                 Water Flow to Preconditioner 
                 kg/hr 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Process Water Temperature 
                 ° C. 
                 9 
                 9 
                 9 
                 9 
                 9 
               
               
                 Meat Addition 
                 kg/hr 
                 700 
                 750 
                 750 
                 750 
                 1313 
               
               
                 Meat Temperature 
                 ° C. 
                 40 
                 34 
                 35 
                 31 
                 41 
               
               
                 Meat Moisture 
                 % wb 
                 68 
                 68 
                 68 
                 68 
                 68 
               
               
                 Preconditioner Discharge 
                 ° C. 
                 66 
                 66 
                 66 
                 50 
                 48 
               
               
                 Temp 
                   
                   
                   
                   
                   
                   
               
               
                 Preconditioner Weight 
                 kg 
                 101 
                 101 
                 100 
                 88 
                 106 
               
               
                 Extruder Barrel Parameters 
                   
                   
                   
                   
                   
                   
               
               
                 Extruder Shaft Speed 
                 rpm 
                 600 
                 600 
                 600 
                 600 
                 600 
               
               
                 Motor Load 
                 % IQ 
                 13 
                 13 
                 14 
                 16 
                 31 
               
               
                 Power Meter 
                 kW 
                 8.3 
                 8.4 
                 10.3 
                 10.4 
                 20.8 
               
               
                 Steam Flow to Extruder 
                 kg/hr 
                 101 
                 102 
                 100 
                 140 
                 213 
               
               
                 Water Flow to Extruder 
                 kg/hr 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Process Water Temperature 
                 ° C. 
                 25 
                 25 
                 25 
                 25 
                 25 
               
               
                 Extruder Motor Power 
                 hp 
                 150 
                 150 
                 150 
                 150 
                 150 
               
               
                 Rated Shaft Speed 
                 rpm 
                 730 
                 730 
                 730 
                 730 
                 730 
               
               
                 Final Extruder Temperature 
                 ° C. 
                 47 
                 93 
                 88 
                 88 
                 88 
               
               
                 Extruder Pressure 
                 psig 
                 200 
                 225 
                 250 
                 350 
                 450 
               
               
                 Product Properties 
                   
                   
                   
                   
                   
                   
               
               
                 Preconditioner Discharge 
                 % wb 
                 33.79 
                 33.62 
                 34.04 
                 31.79 
                 32.02 
               
               
                 Moisture 
                   
                   
                   
                   
                   
                   
               
               
                 Extruder Discharge Moisture  
                 % wb 
                 36.33 
                 35.42 
                 38.21 
                 35.82 
                 35.18 
               
               
                 Extruder Discharge Density  
                 kg/m3 
                 592 
                 626 
                 608 
                 548 
                 613 
               
               
                 Product Temperature at Inlet  
                 ° C. 
                 87 
                 94 
                 94 
                 96 
                 94 
               
               
                 of Cooling Belt 
                   
                   
                   
                   
                   
                   
               
               
                 Product Temperature at 
                 ° C. 
                 51 
                 76 
                 77 
                 74 
                 76 
               
               
                 Discharge of Cooling Belt 
                   
                   
                   
                   
                   
                   
               
               
                 Product Temperature at 
                 ° C. 
                   
                 37 
                   
                   
                   
               
               
                 Discharge of Pneumatic 
                   
                   
                   
                   
                   
                   
               
               
                 System 
                   
                   
                   
                   
                   
                   
               
               
                 Dry Recipe Calculations 
                   
                   
                   
                   
                   
                   
               
               
                 Dry Recipe Specific Heat 
                 kJ/kg · 
                 1.649 
                 1.622 
                 1.622 
                 1.622 
                 1.622 
               
               
                   
                 ° C. 
                   
                   
                   
                   
                   
               
               
                 Dry Recipe Energy 
                 kJ/hr 
                 18139 
                 17842 
                 21086 
                 17842 
                 31224 
               
               
                 Preconditioner Calculations 
                   
                   
                   
                   
                   
                   
               
               
                 Steam Enthalpy 
                 kJ/kg 
                 2721 
                 2721 
                 2721 
                 2721 
                 2721 
               
               
                 Steam Energy 
                 kJ/hr 
                 212238 
                 225843 
                 225843 
                 0 
                 0 
               
               
                 Water Energy 
                 kJ/hr 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Meat Energy 
                 kJ/hr 
                 93160 
                 84843 
                 87338 
                 77356 
                 179111 
               
               
                 Energy From Hot Air 
                 kJ/hr 
                   
                   
                   
                 139229 
                 179538 
               
               
                 Calculated Moisture in 
                 % wb 
                 34.3 
                 34.8 
                 34.8 
                 31.7 
                 31.7 
               
               
                 Preconditioner 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Heat Adjustment 
                 kJ/kg · 
                 0.30 
                 0.30 
                 0.30 
                 0.30 
                 0.30 
               
               
                 Factor 
                 ° C. 
                   
                   
                   
                   
                   
               
               
                 Specific Heat in 
                 kJ/kg · 
                 2.72 
                 2.74 
                 2.74 
                 2.65 
                 2.65 
               
               
                 Preconditioner 
                 ° C. 
                   
                   
                   
                   
                   
               
               
                 Product Mass Flow in 
                 kg/hr 
                 1778 
                 1833 
                 1833 
                 1750 
                 3063 
               
               
                 Preconditioner 
                   
                   
                   
                   
                   
                   
               
               
                 Thermal Energy Added in 
                 kJ/hr 
                 305398 
                 310686 
                 313181 
                 216585 
                 358649 
               
               
                 Preconditioner 
                   
                   
                   
                   
                   
                   
               
               
                 Total Thermal Energy in 
                 kJ/hr 
                 323537 
                 328528 
                 334267 
                 234427 
                 389873 
               
               
                 Preconditioner 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Thermal Energy in 
                 kJ/kg 
                 182 
                 179 
                 182 
                 134 
                 127 
               
               
                 Preconditioner (as is) 
                   
                   
                   
                   
                   
                   
               
               
                 Preconditioner Discharge 
                 kJ/hr 
                 288093 
                 292350 
                 297706 
                 207858 
                 345800 
               
               
                 Energy 
                   
                   
                   
                   
                   
                   
               
               
                 Calculated Preconditioner 
                 ° C. 
                 67 
                 66 
                 67 
                 51 
                 48 
               
               
                 Discharge Temperature 
                   
                   
                   
                   
                   
                   
               
               
                 Calculated Preconditioner 
                 min 
                 3.41 
                 3.31 
                 3.27 
                 3.02 
                 2.08 
               
               
                 Retention Time 
                   
                   
                   
                   
                   
                   
               
               
                 Extruder Barrel Calculations 
                   
                   
                   
                   
                   
                   
               
               
                 Steam Enthalpy 
                 kJ/kg 
                 2770 
                 2770 
                 2770 
                 2770 
                 2770 
               
               
                 Steam Energy 
                 kJ/hr 
                 279770 
                 282540 
                 277000 
                 387800 
                 590010 
               
               
                 Water Energy 
                 kJ/hr 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Total Mass Flow in Extruder 
                 kg/hr 
                 1879 
                 1935 
                 1933 
                 1890 
                 3276 
               
               
                 Barrel 
                   
                   
                   
                   
                   
                   
               
               
                 Total Mass Flow in Extruder 
                 kg/hr 
                 1299 
                 1329 
                 1327 
                 1327 
                 2326 
               
               
                 Barrel (10% moisture basis) 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Heat in Extruder 
                 kJ/kg · 
                 2.516 
                 2.526 
                 2.526 
                 2.489 
                 2.47 
               
               
                 Barrel 
                 ° C. 
                   
                   
                   
                   
                   
               
               
                 Thermal Energy Added in 
                 kJ/hr 
                 279770 
                 282540 
                 277000 
                 387800 
                 590010 
               
               
                 Extruder Barrel 
                   
                   
                   
                   
                   
                   
               
               
                 Thermal Energy in Extruder 
                 kJ/hr 
                 567863 
                 574890 
                 574706 
                 595658 
                 935810 
               
               
                 Barrel 
                   
                   
                   
                   
                   
                   
               
               
                 Extruder Motor Power 
                 kW 
                 111.9 
                 111.9 
                 111.9 
                 111.9 
                 111.9 
               
               
                 Total Mechanical Energy 
                 kJ/hr 
                 29880 
                 30240 
                 37080 
                 37440 
                 74880 
               
               
                 Total Energy 
                 kJ/hr 
                 597743 
                 605130 
                 611786 
                 633098 
                 1010690 
               
               
                 Total Specific Energy (as-is) 
                 kJ/kg 
                 318 
                 313 
                 316 
                 335 
                 309 
               
               
                 Total Specific Energy (10% 
                 kJ/kg 
                 460 
                 455 
                 461 
                 477 
                 435 
               
               
                 moisture basis) 
                   
                   
                   
                   
                   
                   
               
               
                 Total Specific Energy (as-is 
                 kJ/kg 
                 598 
                 605 
                 612 
                 633 
                 578 
               
               
                 dry recipe) 
                   
                   
                   
                   
                   
                   
               
               
                 Calculated Moisture in 
                 % wb 
                 37.8 
                 38.2 
                 38.2 
                 36.8 
                 36.1 
               
               
                 Extruder Barrel 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Thermal Energy In 
                 kJ/kg 
                 302 
                 297 
                 297 
                 315 
                 286 
               
               
                 Extruder Barrel (as is) 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Mechanical Energy 
                 kJ/kg 
                 16 
                 16 
                 19 
                 20 
                 23 
               
               
                 (as-is) 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Mechanical Energy 
                 kJ/kg 
                 23 
                 23 
                 28 
                 28 
                 32 
               
               
                 (10% moisture basis) 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Mechanical Energy 
                 kW-hr/ 
                 6.4 
                 6.3 
                 7.8 
                 7.8 
                 8.9 
               
               
                 (10% moisture basis) 
                 mton 
                   
                   
                   
                   
                   
               
               
                 Specific Mechanical Energy 
                 kJ/kg 
                 30 
                 30 
                 37 
                 37 
                 43 
               
               
                 (as-is dry recipe) 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Mechanical Energy 
                 kW-hr/ 
                 8.3 
                 8.4 
                 10.3 
                 10.4 
                 11.9 
               
               
                 (as-is dry recipe) 
                 mton 
                   
                   
                   
                   
                   
               
               
                 Specific Thermal Energy (as-  
                 kJ/kg 
                 585 
                 593 
                 590 
                 604 
                 542 
               
               
                 is dry recipe) 
                   
                   
                   
                   
                   
                   
               
               
                 Temperature Behind Die 
                 ° C. 
                 126 
                 124 
                 125 
                 135 
                 125 
               
               
                 Thermal to Mechanical 
                   
                 19.6 
                 19.6 
                 15.9 
                 16.1 
                 12.7 
               
               
                 Energy Ratio 
               
               
                   
               
             
          
         
       
     
     EXAMPLE 2 
     In this series of runs, additional high meat pet feed products were prepared. The dry recipe included 53% by weight corn, 22% by weight poultry meal, 15% by weight soybean meal, and 10% by weight corn gluten meal. The added meat was fresh MD chicken meat having a moisture content of 72.83% by weight, fat 14.54% by weight, and protein 12.63% by weight. The extruder was a standard Wenger TX760, as set forth in Example 1. Two Wenger Model 450 preconditioners were used. The first precondition was of the type described herein, including hot air introduction. The second preconditioner was downstream of the first and was a standard preconditioner. The output from the second preconditioner was fed into the extruder. 
     Run 6 was a control with the dry recipe, heated air, and water only to the first preconditioner, with steam introduction to the downstream extruder. Runs 7-10 were similar, with Run 7 including 38% by weight fresh heated meat (23° C.); Run 8 including 38% by weight cold meat (5° C.); Run 9 including 50% by weight fresh cold meat; and Run 10 having 76% by weight fresh cold meat. 
     
       
         
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Run Number 
                 6 
                 7 
                 8 
                 9 
                 10 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Raw Materials 
               
             
          
           
               
                 Feed Rate (lbs/hr) 
                 2,200 
                 2,200 
                 2,200 
                 2,200 
                 2,200 
               
               
                 Bulk Density (lbs/cu ft) 
                 38.0 
                 38.0 
                 38.0 
                 38.0 
                 38.0 
               
             
          
           
               
                 Hybrid HI DDC (Line 4) 
               
             
          
           
               
                 Water (lbs/hr) 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Water (% to Feed Rate) 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.0% 
               
               
                 Steam (lbs/hr) 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Steam (% to Feed Rate) 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.0% 
               
               
                 Small Shaft Direction 
                 REV 
                 REV 
                 REV 
                 REV 
                 REV 
               
               
                 (F or R) 
                   
                   
                   
                   
                   
               
               
                 Small Shaft Speed 
                 800 
                 800 
                 800 
                 800 
                 800 
               
               
                 (RPM) 
                   
                   
                   
                   
                   
               
               
                 Small Shaft Load (%) 
                 50.0% 
                 52.0% 
                 52.0% 
                 56.0% 
                 NA 
               
               
                 Small HP 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                 Small SME (kWHr/Ton) 
                 14.1 
                 17.6 
                 17.1 
                 22.8 
                 NA 
               
               
                 Large Shaft Direction 
                 FWD 
                 FWD 
                 FWD 
                 FWD 
                 FWD 
               
               
                 (F or R) 
                   
                   
                   
                   
                   
               
               
                 Large Shaft Speed(RPM) 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                 Large Shaft Load (%) 
                 80.0% 
                 74.0% 
                 68.0% 
                 77.0% 
                 NA 
               
               
                 Large HP 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                 Large SME (kWHr/Ton) 
                 13.8 
                 14.9 
                 13.4 
                 18.0 
                 NA 
               
               
                 Total DDC SME 
                 27.9 
                 32.5 
                 30.5 
                 40.8 
                 NA 
               
               
                 (kWHr/Ton) 
                   
                   
                   
                   
                   
               
               
                 Weight (lbs) 
                 NA 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 Retention Time (Minutes) 
                 NA 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 Downspout Temp (Deg F.) 
                 131 
                 132 
                 132 
                 129 
                 NA 
               
               
                 Meat Temperature (F.) 
                 NA 
                 75 
                 5 
                 5 
                 5 
               
               
                 Meat Addition (lbs/hr) 
                 0 
                 836 
                 836 
                 1,100 
                 1,672 
               
               
                 Meat Addition 
                 0.0% 
                 38.0% 
                 38.0% 
                 50.0% 
                 76.0% 
               
               
                 (% to feed rate) 
                   
                   
                   
                   
                   
               
             
          
           
               
                 450 HIP (Line 1) 
               
             
          
           
               
                 Water (lbs/hr) 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Water (% to Feed Rate) 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Steam (lbs/hr) 
                 162 
                 167 
                 166 
                 157 
                 166 
               
               
                 Steam (% to Feed Rate) 
                 7.4% 
                 7.6% 
                 7.5% 
                 7.1% 
                 7.5% 
               
               
                 DDC Small (L) Shaft 
                 REV 
                 REV 
                 REV 
                 REV 
                 REV 
               
               
                 Direction (F or R) 
                   
                   
                   
                   
                   
               
               
                 DDC Small (L) 
                 800 
                 800 
                 800 
                 800 
                 800 
               
               
                 Shaft Speed (RPM) 
                   
                   
                   
                   
                   
               
               
                 DDC Small (L) Shaft 
                 9.1% 
                 10.1% 
                 9.9% 
                 10.1% 
                 NA 
               
               
                 Load (%) 
                   
                   
                   
                   
                   
               
               
                 DDC Small (L) HP 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 DDC Small SME 
                 13.0 
                 14.4 
                 13.3 
                 14.4 
                 NA 
               
               
                 (kWHr/Ton) 
                   
                   
                   
                   
                   
               
               
                 DDC Large ® Shaft 
                 FWD 
                 FWD 
                 FWD 
                 FWD 
                 FWD 
               
               
                 Direction (F or R) 
                   
                   
                   
                   
                   
               
               
                 DDC Large ® Shaft 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                 Speed (RPM) 
                   
                   
                   
                   
                   
               
               
                 DDC Large ® Shaft 
                 7.1% 
                 8.4% 
                 8.1% 
                 8.5% 
                 NA 
               
               
                 Load (%) 
                   
                   
                   
                   
                   
               
               
                 DDC Large ® HP 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 DDC Large SME 
                 11.0 
                 11.1 
                 10.8 
                 12.1 
                 NA 
               
               
                 (kWHr/Ton) 
                   
                   
                   
                   
                   
               
               
                 Total DCC SME 
                 24.0 
                 25.5 
                 24.1 
                 26.5 
                 NA 
               
               
                 (kWHr/Ton) 
                   
                   
                   
                   
                   
               
               
                 Cylinder Weight (lbs) 
                 235 
                 265 
                 257 
                 260 
                 NA 
               
               
                 Cylinder Retention 
                 5.97 
                 4.96 
                 4.82 
                 4.51 
                 NA 
               
               
                 Time (Minutes) 
                   
                   
                   
                   
                   
               
               
                 Cylinder Downspout 
                 162 
                 168 
                 172 
                 171 
                 169 
               
               
                 Temp (Deg F) 
                   
                   
                   
                   
                   
               
             
          
           
               
                 TX-760 (Line 1) 
               
             
          
           
               
                 HP 
                 150 
                 150 
                 150 
                 150 
                 150 
               
               
                 Water (lbs/hr) 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Water (% to Feed Rate) 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.0% 
               
               
                 Steam (lbs/hr) 
                 186 
                 136 
                 161 
                 169 
                 116 
               
               
                 Steam (% to Feed Rate) 
                 8.5% 
                 6.2% 
                 7.3% 
                 7.7% 
                 5.3% 
               
               
                 RPM 
                 500 
                 500 
                 500 
                 500 
                 500 
               
               
                 Load (lq)(%) 
                 25.4% 
                 26.5% 
                 25.7% 
                 26.0% 
                 NA 
               
               
                 SME (lq) (kW-Hr /Ton) 
                 22.3 
                 17.8 
                 17.1 
                 16.0 
                 NA 
               
               
                 (As-Is) 
                   
                   
                   
                   
                   
               
               
                 Load (l) (%) 
                 36.1% 
                 36.3% 
                 35.7% 
                 35.9% 
                 NA 
               
               
                 SME (l) (kW-Hr /Ton) 
                 31.7 
                 24.3 
                 23.7 
                 22.1 
                 NA 
               
               
                 (As-Is) 
                   
                   
                   
                   
                   
               
               
                 Final Head Temperature (F.) 
                 203.0 
                 212.0 
                 213.0 
                 219.0 
                 223.0 
               
               
                 Knife RPM 
                 1,200  
                 1,800 
                 1,800 
                 1,800 
                 1,800 
               
             
          
           
               
                 Total Process 
               
             
          
           
               
                 SME (lq) (kW-Hr /Ton) 
                 74.2 
                 75.8 
                 71.7 
                 83.3 
                 NA 
               
               
                 (As-Is) 
                   
                   
                   
                   
                   
               
               
                 SME (l) (kW-Hr /Ton) 
                 83.6 
                 82.3 
                 78.3 
                 89.4 
                 NA 
               
               
                 (As-Is)