Abstract:
An improved, continuous process for the production of animal feed supplements including an apparatus for carrying out such process is provided. Broadly, the process includes continuous preparation of a preblend including molasses and vegetable fat, followed by continuous cooking of the preblend in an elongated cooking zone and batch cooking assembly. The cooked preblend is then continuously treated for removal of moisture and partial cooling thereof, whereupon dry ingredients (e.g., vitamins and protein sources) are added and the resultant feed supplement is continuously cooled and packaged.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with an improved, continuous process and apparatus for the manufacture of animal feed supplements. More particularly, the invention pertains to such an improved process wherein, in preferred forms, a molasses-based preblend is continuously passed through an indirect thermal interchange continuous cooker and a batch-cooking assembly followed by moisture removal and partial cooling; a dry mixture including vitamins and proteinaceous ingredients is then added to the cooked preblend, and the resultant feed supplement is further cooled and packaged. 
     2. Description of the Prior Art 
     Animal feed supplements, as used herein, are manufactured nutritional products intended to supplement the basic forage, hay, grain or other diet of livestock such as bison, domesticated cattle, sheep and horses. Molasses-based feed supplements have long been used to enhance the diets of livestock, particularly cattle. Such supplements are commonly in the form of a solid block and are placed in a stockyard for ad libitum consumption by the animals. Molasses-based feed supplements have in the past been produced on a batch basis. For example, U.S. Pat. No. 4,749,578 describes a process for the manufacture of molasses feed blocks wherein molasses and other ingredients are mixed, cooked, cooled and packaged on a batch basis. This manufacturing technique is inherently costly and time-consuming. 
     U.S. Pat. No. 5,482,729, incorporated by reference herein, describes a continuous process for the manufacture of molasses feed blocks which includes cooking the molasses composition in an elongated, indirect thermal exchange cooker, passing the cooked molasses composition through a cyclone separator and serial vacuum tank for removing moisture from the cooked composition. However, this arrangement presents several problems. The molasses starting materials for use with the &#39;729 process must have relatively low moisture contents (generally less than about 25% by weight) and are generally more expensive than other sugar-rich materials with higher moisture contents. In addition, this process utilizes a single stage cooker to cook the molasses mixture. In order to effectively cook the molasses mixture, the operating temperature within the cooker must be relatively high, approximately 320° F., thereby running the risk of scorching the molasses mixture within the cooker leading to expensive downtime and cooker maintenance. 
     Accordingly, there is a real and unsatisfied need for an improved continuous process for the manufacture of animal feed supplements which employs lower cooking temperatures and allows for the use of less expensive carbohydrate-rich starting materials with relatively high moisture contents when compared with highly refined molasses. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems noted above, and provides a continuous process and apparatus for the manufacture of animal feed supplements, and particularly molasses-based supplements. 
     Broadly speaking, the process of the invention involves first continuously preparing a preblend including respective amounts of carbohydrate material and fat. The carbohydrate material may comprise any sugar-based material palatable to animals and can further include significant amounts of moisture and protein. Advantageously, carbohydrate material for use with the invention may comprise up to about 50% by weight water, preferably up to about 40% by weight water, and more preferably between about 20–30% by weight water. Preferably the carbohydrate material is chosen from the group consisting of molasses, including cane and beet molasses, concentrated separator by-product (CSB), corn steep liquor, soybean whey and mixtures thereof. As used herein, concentrated separator by-product refers to a high-protein, high-moisture product produced during processing of beet molasses. While most preferably the carbohydrate material will comprise molasses, as molasses costs increase, significant amounts of corn steep liquor, a by-product of dextrose processing, CSB, and soybean whey may be used in lieu of some or all of the molasses. In preferred embodiments, the carbohydrate material will comprise between up to 100% soybean whey (more preferably between 10%–60%, most preferably 10%–40%) and 10–60% corn steep liquor (more preferably between 10–30% corn steep liquor). In yet other preferred embodiments, the carbohydrate material may comprise 100% CSB. Preferably, the fat used in preparing the preblend is a vegetable fat, such as corn or soy oil. The preblend typically contains from about 60–80% by weight carbohydrate material and from about 5–10% by weight of fat. Preferably, the preblend contains from about 65–75% by weight carbohydrate material, from about 3–7% by weight fat, and from about 4–20% protein. 
     In the next step, the preblend is continuously passed into and through an elongated cooking zone where the preblend is heated and at least partially cooked. Such partial cooking is preferably accomplished via indirect, countercurrent thermal heating; in practice, the cooking zone comprises a conduit through which the preblend is directed; the conduit being contacted with a heated cooking fluid. More preferably the cooking zone includes an annular preblend-conveying zone with inner and outer heating fluid-conveying zones respectively disposed adjacent the inner and outer margins of the annular zone. Steam or other thermal interchange media, such as hot oil, is continuously passed in countercurrent relationship to the preblend passing through the annular zone of the cooker. In any case, the preblend passing through the elongated cooking zone should be heated to a temperature of between about 240°–320° F., more preferably between about 260°–300° F., and most preferably between about 260°–270° F. In order to achieve these temperature conditions using the preferred cooker, the preblend would normally be present in the cooking system for a period of from about 1–5 minutes and preferably between about 2–3 minutes. 
     The partially-cooked preblend, is directed into a continuous batch-cooking assembly, operating under atmospheric pressure, for completion of cooking, thereby flashing moisture from and lowering the temperature of the preblend. The batch-cooking assembly comprises a plurality of batch cookers arranged in parallel. Preferably the assembly will comprise at least three such cookers and is located downstream from the elongated cooking zone. At any given time, at least one cooker is filling with preblend from the elongated cooking zone and at least one cooker is emptying thereby providing a continuous output stream of cooked preblend. Preferably, the batch cookers employ indirect thermal interchange to heat the preblend to a temperature of between about 255°–290° F., more preferably between 260°–280° F., and most preferably between about 262°–268° F. Steam is the preferred heat transfer media in this regard. In order to accomplish heating the preblend to the preferred temperatures, the residence time of the preblend within the batch cooker is preferably about 10–60 minutes and more preferably about 15–25 minutes. 
     At the conclusion of the cooking step, the cooked material is continuously passed into and through a moisture-removal zone, preferably in the form of a vacuumizer tank operably connected to a vacuum pump. This serves to remove moisture from the cooked preblend, and also lowers the temperature thereof. Normally, the moisture content of the cooked preblend is lowered to a level of from about 1.5–10% by weight (more preferably from about 2–5% by weight), whereas the temperature of the cooked preblend is lowered to a level of from about 150°–220° F. (more preferably from about 200°–210° F.). 
     In the next step, dry components are added to the preblend to form a substantially homogenous and flowable feed supplement. Such dry components include the usual vitamins and proteinaceous ingredients, and use can be made of plant and/or animal protein sources. The feed supplement is then continuously cooled and packaged into quantities of desired size. This cooling step will comprise either allowing the material to cool under ambient conditions or by continuously passing the supplement onto an endless, moving belt with a packaging station at the end of the belt. In order to enhance cooling, water is sprayed against the underside of the belt. 
     The improved process of the present invention is approximately 20% faster or alternatively produces approximately 20% more product in the same amount of time as compared to the process disclosed in U.S. Pat. No. 5,482,729. The increased production occurs without extra labor and results in valuable energy savings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The FIGURE is a schematic flow diagram illustrating the preferred apparatus and method steps used for the continuous production of animal feed supplements in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the FIGURE, apparatus  10  for the continuous manufacture of animal feed supplements is illustrated. Broadly, the apparatus  10  includes a preblending assembly  12 , an elongated cooker  14 , a batch cooking assembly  15 , a moisture removal station  16 , a dry mix preparation assembly  18 , a blender  20  and a cooling/packaging assembly  22 . 
     In more detail, the assembly  12  includes individual, stirred tanks  24  and  26  for holding supplies of vegetable fat (e.g. corn or soy oil) and molasses. The tanks  24 ,  26  are connected to a liquid blender  28  via lines  30 ,  32 , the latter having variable speed pumps  34 ,  36  interposed therein. The outlet  40  of blender  28  is coupled with a transfer conduit  42  leading to cooker  14 . 
     The cooker  14  is in the form of a continuous, open loop, indirect thermal interchange device. In detail, the cooker  14  includes a steam boiler  44  and a continuous conduit system  46  operably coupled with boiler  44 . In preferred embodiments, the conduit system  46  includes an innermost, central, steam-conveying pipe, an annular preblend-conveying imperforate conduit disposed about the central pipe, and an outermost, annular, steam-conveying pipe disposed about the annular conduit (latter components not shown). As shown in the FIGURE, conduit system  46  is connected to boiler  44  for flow of steam through the steam-conveying pipes of conduit system  46  in the direction indicated by arrows  54 . However, the preblend from assembly  12  passes through transfer conduit  42  to an inlet  56  in communication with the annular conduit. Thus, the preblend from blender  28  passes through conduit  42  and thence through conduit system  46  in countercurrent relationship with the flow of steam through conduit  46 . While in cooker  14 , the preblend is heated and undergoes at least partial cooking. Again referring to the FIGURE, a preblend outlet  60  is provided, the latter being coupled to transfer conduit  61 . The outlet  60  is in communication with the preblend conveying conduit of conduit system  46 , thereby allowing cooked preblend to pass from cooker  14  to assembly  15 . 
     Assembly  15  includes four batch cookers  62 – 65  arranged in parallel and operating under atmospheric pressure. The batch cookers  62 – 65  are supplied with steam from boiler  44 . During operation of assembly  15 , the entire stream of preblend conveyed in conduit  61  is directed into a single batch cooker,  62  for example, whereby a portion of the preblend moisture flashes off and the temperature of the preblend is lowered. Once cooker  62  has reached its operational capacity, the entire stream of preblend in conduit  61  is directed into another batch cooker  63 , for example. While cooker  63  is filling, the preblend contained within cooker  62  is heated and cooked. Once cooker  63  has reached capacity, the stream of preblend in conduit  61  is directed into cooker  64 . While cooker  64  is filling, the material within cooker  63  is heated and cooked, and cooker  62  empties the cooked preblend into transfer conduit  66 . The cycle of alternating cookers filling, cooking, and emptying is such to supply conduit  66  with a continuous stream of cooked preblend. Cooker  65  is generally not employed during normal operation of assembly  15 , but rather acts as a backup cooker to handle any surge in apparatus  10  production or should one of cookers  62 ,  63 ,  64  be taken offline for maintenance. The batch cookers  62 – 65  are equipped with vents  69  which are open to the atmosphere to allow for removal of moisture from the preblend during cooking thereof. 
     The moisture removal station  16  includes a vacuumizer tank  67  and vacuum pump  68 . As will be apparent to those skilled in the art, cooked preblend passes from conduit  66  into and through vacuum tank  67  for removal of moisture and cooling of the preblend. The underflow from tank  67  travels by way of pipe  72  to blender  20 . 
     The assembly  18  includes individual holding tanks  74  and  76  for the dry ingredients and vitamins and minerals desired for incorporation into the feed supplement. The tanks  74 ,  76  are connected by conduits  78 ,  80  and appropriate augers (not shown) with a ribbon mixer  82 . The output from mixer  82  is conveyed through conduit  84  and a transfer auger (not shown) to a holding bin  86 ; the latter has a pipe  88  leading to blender  20  as shown. 
     The blender  20  includes variable speed controls. The outlets of pipes  72  and  88  are in communication with the mixing screws of the blender. The outlet from the mixing screws is in the form of a completed feed supplement which is substantially homogeneous and flowable. This flowable mixture passes from the mixing screws and is deposited onto an endless, moving stainless steel belt  92 . The belt moves in the direction illustrated by arrow  94 , and thereby serves to continuously deposit cooled feed supplement into drums  96  or other appropriate containers at the end of the belt remote from the mixing screws. Preferably, water is sprayed via heads  98  against the underside of the belt  92 , thereby maximizing the cooling effect during passage of the feed supplement along the belt. 
     In practice, the molasses and vegetable oil in tanks  24 ,  26  are metered into blender  28  at the preferred ratios noted above. Since molasses varies in moisture content from area to area and refinery to refinery, direct weighing of uncooked molasses is not always determinative of specific operating conditions to be used at various steps throughout the process. Operating conditions, such as cooker temperatures and residence times, may need to be adjusted based upon the moisture content of the molasses fed to the process. The output from blender  28  passes through the cooker  14  which in practice is about 120 feet long. In cooker  14 , the preblend is heated to a temperature of between about 260°–300° F. The preblend has a residence time within cooker  14  of about 1–5 minutes. Upon exiting the cooker  14 , the preblend is directed to one of the batch cookers  62 , for example, for additional cooking. The particular batch cooker  62 – 65  to which the incoming stream of preblend is directed is automatically controlled so that at least one batch cooker  62 – 65  is filling at any given time. In assembly  15 , the preblend undergoes further cooking at a temperature of between about 260°–280° F. The preblend remains in the batch cooker  62  for about 10–60 minutes. Preferably, three batch cookers  62 – 64  will be in operation at any given time. One cooker  62  will be receiving preblend from cooker  14 , one cooker  63  will be cooking the preblend, and one cooker  64  will be emptying cooked preblend so that a continuous stream of preblend may be supplied to moisture removal station  16 . A fourth batch cooker  65  may be employed to handle overflow from cooker  14  resulting from preblend flow rate changes. Following cooking, the preblend passes into vacuum tank  67 , the latter having a vacuum of about 21–24 inches of mercury. This causes the product to release steam and moisture, to a level of about 2% to 4% by weight, along with a lowering of the temperature of the product to between about 200°–220° F. 
     The dry ingredients from tanks  74  and  76  are conveyed by the augers to ribbon mixer  82 , the latter resting on an electronic scale. The mixture is held in blender  82  then conveyed to holding bin  86 . 
     The cooked preblend in tank  67  is pumped and the dry ingredients in bin  86  are augered into the mixing screw section  20  with both regulated by variable speed controls. The latter is operated to produce a substantially homogeneous and flowable product at a temperature between about 150°–200° F. The product is then conveyed on belt  92  for cooling and packaging. During packaging, the product has a temperature of about 140° F. and is in a taffy-like state. Once packaged, the product is set aside for complete cooling to ambient temperature, where it becomes hardened like rock candy. 
     EXAMPLE 
     A 6400 lb/hr stream of beet molasses having a moisture content of 23% by weight was blended with a 340 lb/hr stream of hydrolyzed soy oil to produce a liquid mixture having a moisture content of 23% by weight. All moisture contents expressed herein are based upon the weight of the entire mixed wet stream being 100%. The mixture was fed at a temperature of 100° F. (ambient temperature) to an indirect heat interchange continuous pipe cooker having a length of 120 feet and an internal cooking chamber having a diameter of 1½ inches. While inside the continuous cooker, the liquid mixture was heated to a temperature of 270° F. at a pressure of 40 psi over a period of 2 minutes during which the mixture was partially cooked. Upon exiting the continuous cooker at 270° F., the liquid mixture was fed into one of four batch cookers arranged in parallel operating under atmospheric pressure and ambient temperature. Upon entering the batch cooker, a portion of the liquid mixture&#39;s moisture flashed off and the mixture temperature was lowered to 245° F. The moisture content of the liquid mixture after flashing was 8% by weight. The mixture was then cooked inside the batch cooker for 25 minutes to a temperature of 265° F. The cooked liquid was discharged into a vacuum tank operating at a vacuum of 24 inches of mercury and the temperature of the liquid mixture was lowered to 212° F. Upon exiting the vacuum tank, the liquid mixture had a moisture content of 2% by weight. The liquid mixture was blended with a 2600 lb/hr stream of dry ingredients comprising 38% by weight of assorted minerals and vitamins and 62% by weight of meal proteins, the dry ingredient stream having a moisture content of less than 5% by weight. The blended product had a temperature of 170° F. The final product had a moisture content of 4% by weight immediately prior to packaging in open topped containers and exhibited taffy-like consistency. After cooling, the product was hard and crystallized. 
     The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.