Abstract:
A positionable gas nozzle assembly having a nozzle tube for injecting and directing pressurized air or other inert gas into a pellet slurry so as to increase the velocity of the slurry from a pelletizer to and through a dryer. The variably positionable nozzle tube can be inserted, retracted and/or intermediately positioned either manually or using an automated control system. The automated control system preferably includes a pneumatic cylinder movably engaged with a carriage that is fixedly coupled to the nozzle tube. The pneumatic cylinder contains a piston that is magnetically coupled with the carriage such that movement of the piston in response to the injection of pressurized air into the cylinder also moves the carriage and the nozzle tube to obtain the variable positions.

Description:
This application is a continuation-in-part application of co-pending U.S. application Ser. No. 12/213,204, filed Jun. 16, 2008, and hereby claims the priority thereof. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to underwater pelletizing systems and, more particularly, to a gas injection nozzle for use with such systems. 
     2. Description of Related Art 
     Those skilled in the art have found it beneficial, and sometimes necessary, to produce pellets that crystallize, either partially or fully. To help achieve that crystallization, the assignee of the present invention has disclosed the use of a nozzle through which pressurized air or other gas can be injected into the pellet slurry to help decrease the retention time of the pellets in the transportation liquid between the upstream pelletization process and the downstream drying and subsequent processes in U.S. Pat. No. 7,157,032; U.S. Patent Application Publication Nos. 2005/0110182 and 2007/0132134; World Patent Application Publication Nos. WO 2005/051623, and WO 2006/127698, all of which are owned by the current assignee of the present invention and are incorporated herein by reference as if fully set forth in their entirety. 
     Similarly, WO 2007/027877 discloses the use of a nozzle through which pressurized air or other gas can be injected into the pellet slurry to facilitate aspiration of the liquid from the pellets in the pellet slurry. Moisture content of the pellets is lowered by reducing the retention time of the pellets in the transportation liquid between the upstream pelletization process and the downstream drying and subsequent processes. The reduced retention time also results in more of the internal heat of the pellets formed being retained, and thus reduces the moisture available for uptake by the pellets. This application, also owned by the current assignee of the present invention, is also incorporated by reference herein in its entirety. 
     Under certain conditions, pellets can clump or form agglomerates during the pelletizing process. The formation of pellet agglomerates can have many causes, of which sticky pellets is both common and frequent. When these agglomerates form they have the tendency to get caught in so-called “hang-up points”, a term used herein to describe locations throughout the process where pellets and/or agglomerates of pellets tend to get hung-up and remain, often forming an obstructive build-up. As an example, agglomerates of pellets can form when “drooling”, excessive flow of molten material through the die holes, occurs at the die plate, thus creating an undesirably large pellet. Large pellets are not the only problem. Pellets of desirable size can create a problem as well. Sticky pellets, or pellets that are still soft, that come into contact with the nozzle can be “smashed” and stick to the nozzle due to their stickiness and the velocities at which they are traveling. Eventually more and more pellets come into contact with those stuck on the nozzle and pellets begin to adhere to each other creating a mass of pellets, also referred to as an agglomerate. Eventually the mass of pellets can become large enough to disrupt the flow of transport liquid and pellets through the transport pipe. This disruption can force the pelletization process to be stopped. 
     One such hang-up point has been found to exist in pelletization lines utilizing the apparatus and process of inserting pressurized gas described in the afore-identified patents and applications, namely the point at which the gas insertion nozzle is located within the pellet transport pipe. According to these prior embodiments, the nozzle used to inject the air is as illustrated in  FIG. 1  and generally designated by the reference numeral  200 . The prior art fixed nozzle tube  210  is attached, preferably by welding, into elbow  202  at juncture  214 . This fixed nozzle assembly  200  cannot be removed to facilitate start-up. It can further serve as a potential source for occlusion by pellet agglomeration as it cannot be maneuverably positioned to permit free flow of the pellet slurry about the periphery of the fixed nozzle pipe  210 . Similarly, the fixed position limits the degree to which the air or other gas being injected can be controlled through valve regulation. 
     Therefore, a need exists for a positionable nozzle that can be adjusted to optimize the crystallization and/or drying of pellets produced by an underwater pelletizing system. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present invention to provide a positionable nozzle through which pressurized gas is introduced into the transport apparatus of an underwater pelletizer to increase the velocity of a pellet slurry being transported from a pelletizing process to and through a drying process while controlling the dynamics of the slurry flow through changes in the position of the nozzle. 
     Another object of the present invention is to provide a positionable nozzle having a nozzle tube and collar that slides within a housing attached to a seal transition collar and affixed to an elbow within the transport pathway between the pelletization apparatus and the drying apparatus. 
     Still another object of the present invention is to provide a positionable nozzle in accordance with the preceding objects that is adjustable between at least a fully inserted or forward position and a fully retracted position, with positioning of the nozzle to make such adjustment being accomplished manually or by means of an automated control system that uses mechanical, pneumatic, hydraulic, electrical, electronic or other methods, singularly or in combination, as may be suitable for a particular application. 
     A still further object of the present invention is to provide a positionable nozzle in accordance with the preceding objects that can be manually or automatically adjusted using any of the methods set forth in the immediately preceding object to inject pressurized gas in one or more intermediate or partially inserted positions. 
     A further object of the present invention is to provide a positionable nozzle in accordance with the preceding objects that is angularly positioned within the lumen of the elbow to which it is attached such that the angle ranges from approximately 0° from the centerline of the downstream assembly to a maximum angle defined by contact of the outside of the nozzle tube with the inside surface of that downstream assembly. 
     Yet another object of the present invention is to provide a positionable nozzle that is concentrically centered about the centerline of the downstream equipment. 
     Still a further object of the present invention is to provide a positionable nozzle through which pressurized gas is introduced that increases the velocity of a pellet slurry being transported from a pelletizing apparatus to and through a drying apparatus such that the internal heat of the pellets is retained to facilitate drying of the pellets such that the moisture content of the pellets leaving the drying apparatus is less than approximately 1.0% by weight, more preferably less than 0.5% by weight, and most preferably less than 0.25% by weight. 
     An additional object of the present invention is to provide a positionable nozzle through which pressurized gas is introduced to increase the velocity of a pellet slurry being transported from a pelletizing apparatus to and through a drying apparatus such that the internal heat of the pellets is retained to facilitate both drying and crystallization of the pellets. 
     A further object of the present invention is to provide a positionable nozzle in accordance with the preceding object through which pressurized gas is introduced that increases the velocity of a pellet slurry being transported from a pelletizing apparatus to and through a drying apparatus such that the pellets leaving the drying apparatus are crystallized at least 20% by weight, more preferably at least 30% by weight, and most preferably at least 40% by weight. 
     Yet a further object of the present invention is to provide a positionable nozzle that can be retracted at least partially to prevent pellet hang-up during start-up of the pelletization process, and that can be moved forward to expedite the flow of the pellet slurry into and through the transport pipe and to facilitate the aspiration of the transport liquid away from the pellets as they move through the transport pipe. 
     A still further object of the present invention is to provide a positionable nozzle having any of a number of cross-sectional shapes, inner surface variations or internal structures in order to produce specific desired effects on the flow of the pellet slurry. 
     In view of these and other objects, the present invention is directed to an injecting device for use with an underwater pelletizer apparatus that extrudes and cuts polymer strands into pellets which are conveyed as a water and pellet slurry through transport piping to a centrifugal dryer. The injecting device includes a positionable nozzle assembly having an adjustable injection position to introduce a pellet speed expediter into the water and pellet slurry to increase a velocity of the pellet slurry to and through the dryer such that more internal heat of the pellets is retained. The nozzle assembly is adjustable between a fully inserted position in which a nozzle tube of the assembly is positioned forwardly within the transport piping and a fully retracted position in which the nozzle tube is withdrawn from the transport piping to provide wholly unobstructed flow of the slurry through the piping. Preferably, the positionable nozzle assembly is configured so that the nozzle tube can be positioned, manually or through the use of an automated control system, at not only the fully inserted and fully retracted positions but also at various intermediate positions between the fully inserted forward position and the fully retracted position. 
     These benefits together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cut-away and cross-sectional illustration of a prior art fixed nozzle configuration. 
         FIG. 2  is a schematic illustration of an underwater pelletizing system including an underwater pelletizer and transport piping with a positionable nozzle connected to a centrifugal dryer in accordance with the present invention. 
         FIG. 2   a  is an enlarged view illustration of the positionable nozzle of  FIG. 2 . 
         FIG. 3  is a cut-away and cross-sectional illustration of a portion of the positional nozzle and transport piping of  FIG. 2   a  with the nozzle tube in a retracted position. 
         FIG. 4  is a cut-away and cross-sectional illustration of a portion of the positional nozzle and transport piping of  FIG. 2   a  with the nozzle tube in an inserted forward position. 
         FIG. 5  is a schematic top view of a portion of the positional nozzle and transport piping of  FIG. 2   a  with the nozzle tube in the inserted forward position. 
         FIG. 6   a  is a cut-away and cross-sectional illustration of a portion of the positional nozzle and transport piping of  FIG. 2   a  using an automated control system with the nozzle tube shown in a retracted position. 
         FIG. 6   b  is a view of the nozzle tube housing taken along line  6   b - 6   b  of  FIG. 6   a.    
         FIG. 6   c  is a cut-away and cross-sectional illustration of the automated control system embodiment of  FIG. 6   a  with the nozzle tube shown in an inserted forward position. 
         FIG. 6   d  is a view of the nozzle tube housing taken along line  6   d - 6   d  of  FIG. 6   c.    
         FIG. 7  is a partial cutaway view of a magnetically coupled rodless cylinder for use in the automated control system of  FIGS. 6   a - 6   d.    
         FIG. 8  is a diagram showing a control circuit for the automated control system of  FIGS. 6   a - 6   d.    
         FIG. 9   a  is an illustration of the forward orifice of a nozzle tube containing perpendicularly oriented straight fins in accordance with the present invention. 
         FIG. 9   b  is an illustration of the forward orifice of a nozzle tube containing perpendicularly oriented contoured fins in accordance with the present invention. 
         FIG. 9   c  is an illustration of a semicircular forward orifice for a nozzle tube in accordance with the present invention. 
         FIG. 9   d  is an illustration of a conchoidal to C-shaped forward orifice for a nozzle tube in accordance with the present invention. 
         FIG. 9   e  is an illustration of a nozzle tube with tapered terminus in accordance with the present invention. 
         FIG. 9   f  is an illustration of a nozzle tube with a decreasingly conical tapered bore in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although preferred embodiments of the invention are explained in detail, it is to be understood that other embodiments are possible. Accordingly, it is not intended that the invention is to be limited in its scope to the details of constructions, and arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being or carried out in various ways. Also, in describing preferred embodiments, specific terminology will be resorted to for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. Where possible, components of the drawings that are alike are identified by the same reference numbers. 
     The positionable nozzle assembly according to the present invention helps to enhance the crystallization of various polymeric materials and also facilitates drying of those and other materials while eliminating a possible hang-up point for agglomerates that has been encountered with prior designs. With pressurized air or other gas injected into the pellet transportation pipe, the velocity of the pellet slurry is increased. The result is a decrease in time that the pellets are subjected to the transport liquid due to that increased velocity as well as the aspiration of transport liquid away from the surface of those pellets. Due to the increased velocity, the retention time of the pellets in the transport liquid is less, allowing the pellets to retain more internal heat than had they been subjected to the transportation liquid for a longer period. In effect, it is the increase in retained internal heat that aids in the crystallization of the pellets. This effect is further enhanced by the aspiration of the transport liquid away from the surface of the pellets such that loss of heat to the transfer liquid is reduced. 
     To achieve the maximum throughput of the pellets, the present invention allows the geometry and positioning of the nozzle to be adjusted. This is important to the velocity at which the slurry is transported from the pelletizer to the dryer which, in turn, impacts the efficiency of the system in separating the pellets from the transport liquid by aspiration and increasing the amount of internal heat retained by the pellets. Changing the geometry and positioning of the nozzle can also serve to alter the flow pattern of the slurry through the transport pipe, creating more or less turbulence to meet specific requirements associated with the material being processed. 
     Turning now to  FIG. 2 , the positionable nozzle in accordance with the present invention, generally designated by the reference numeral  100 , is assembled into the transport piping, generally designated by the reference numeral  15 , that connects the pelletization apparatus  10  to the drying apparatus  20  and any subsequent post-processing. A melting and mixing apparatus, not shown, connects to the pelletizer  10  to which is attached inlet pipe  12 . Transport liquid is introduced through inlet pipe  12  into the cutting chamber of pelletizer  10  where it mixes with the pellets to form the pellet slurry. The pellet slurry exits through outlet pipe  14  into and through sight glass  16  and then past the positionable nozzle assembly  100  in transport piping  15 . A pellet speed expediter is injected and directed into the transport piping through the positionable nozzle assembly  100  to reduce the time the pellets are subjected to the transport liquid. The pellet speed expediter is preferably air in view of its inert nature and ready availability. However, other gases having inert characteristics such as nitrogen or similar gases could be used. The expedited pellet and transport liquid passes through transport pipe  18  into and through dryer assembly  20  wherein the pellets are dewatered and dried. Details of the expedited pellet and transport liquid follow below. 
     The melting and mixing apparatus, not shown, can be any prior known apparatus or combinations thereof and can include, without being limited thereto, melt vessels, single screw extruders, twin screw extruders, static mixers, continuous mixers, Banbury-type mixers, and the like as is known to those skilled in the art. 
     The pelletizer  10  can be a water ring pelletizer, an underwater pelletizer, and the like, and is preferably an underwater pelletizer fitted with an extrusion die as is well known to those skilled in the art. Transport liquid can be any liquid and is preferably water. In addition to water, other liquids useful in pelletization in accordance with the present invention include alcohol, water-alcohol mixtures, mineral oil, vegetable oils, glycol mixtures, etc. Optionally, the water or other transport liquid can contain additives including, but not limited to, flow modifiers, coatings, defoamers, cosolvents, and the like. As used herein, when references are made to “liquid” or “water” in connection with the transport liquid, such references are intended to refer to any liquid suitable for use as a transport liquid, with or without additives, and not just water. 
     The materials being pelletized and transported in accordance with the present invention can be polymers, waxes, and other extrudable materials that are conventionally processed by pelletization. As examples, the materials can include polyolefins, polyesters, polyethers, polythioethers, polyamides, polyamideimides, polysulfones, polycarbonates, polyurethanes, fluoropolymers, vinyl polymers, biodegradable polymers, and copolymers thereof. Materials that are typically crystallized before further processing are especially suitable for processing in accordance with the present invention, and preferably the materials can be dried to a moisture content of less than 1% by weight and crystallized to a level of at least 20%. Even more preferably, the materials can be dried to a moisture content less than 0.50% moisture by weight and crystallized to a level of at least 30% by weight, and most preferably the materials can be dried to a moisture content less than 0.25% by weight and crystallized to a level of at least 40% by weight. 
     Alternatively and optionally, the materials to be pelletized in accordance with the present invention can contain any conventional filler and combinations of fillers and/or other additives as are known to those skilled in the art. The fillers can include cellulosic powders and/or fibers, biomaterials including powders and fibers, and the like. 
     The dryer  20  in  FIG. 2  can be at least one of a dewatering device, filtration device, vibratory dewatering device, fluidized bed, tumble dryer, centrifuge, dryer, centrifugal dryer, and is preferably a self-cleaning centrifugal dryer. However, any separating apparatus for separating the liquid from the pellets in the liquid and pellet slurry can be used in the present invention. Post-processing can include but is not limited to at least one of cooling, enhanced crystallization, heating, additional drying, sizing, solid state polycondensation or solid state polymerization, packaging, and the like as is well known to those skilled in the art. 
     One embodiment of the positionable nozzle assembly  100  according to the present invention is shown in more detail in the enlarged view of  FIG. 2   a . The assembly includes a valve  104 , a pipe  106 , a check valve  108 , and a nozzle tube  110  which is partially inserted into elbow  102  and not visible, as indicated by the dotted line. The nozzle tube  110  is inserted into elbow  102  at insertion point  112  and extends into the lumen of elbow  102  to the juncture  114  of elbow  102  and effluent pipe  116 . Inlet gas line, not shown, is attached to valve  104 , which is preferably a ball valve. 
     The pellet slurry passing through sight glass  16  (see  FIG. 2 ) passes through influent pipe  118  and into and through elbow  102 , where it interacts with the pressurized gas, preferably air, before passing into effluent pipe  116  and through valve  120 . Influent pipe  118 , elbow  102 , and effluent pipe  116  can be a single piece of pipe that has been modified by bending to shape the elbow and to allow insertion of nozzle tube  110 . Preferably, however, the influent pipe  118 , elbow  102 , and effluent pipe  116  are separate components that are attached together, such as by threaded engagement or welding. Influent pipe  118  and effluent pipe  116  can be the same diameter as elbow  102 , or they can be of different diameter than the elbow  102  in which case they are preferably tapered to the diameter of elbow  102 . According to a preferred embodiment, influent pipe  118  and elbow  102  are the same diameter and effluent pipe  116  taperingly decreases in diameter from the juncture  114  with elbow  102  to the attachment with pipe extension  122  leading to and connecting with valve  120 . Valve  120  is connected, preferably by threaded engagement or by welding, to transport pipe  18 . 
     Optionally, effluent pipe  116  and pipe extension  122  can be disconnectedly attached by a quick disconnect connection  125  as illustrated in  FIG. 2   a . The quick disconnect connection  125  can be any suitable pipe quick-disconnect assembly. Such a connection facilitates ease of access to the elbow and nozzle assembly for inspection, cleaning, maintenance, and repair as needed. 
     Influent pipe  118 , elbow  102 , effluent pipe  116 , and nozzle tube  110  are preferably made of metal including tool steel, vanadium steel, carbon steel, hardened steel, stainless steel, nickel steel, and the like, but can also be made of wear resistant industrial grade plastic. These components are more preferably made of stainless steel and most preferably made of low carbon stainless steel. 
     Check valve  108  is preferably placed between a receiver tank (not shown) and the elbow  102  and prevents water and pellets from backing up into the receiver tank. Check valve  108  allows pressurized air or other gas to flow through it, but when air or other gas is not passing through it, pressure from the transport liquid will cause check valve  108  to shut, thus preventing a back flow of transport liquid and pellets. Alternatively, an automated valve, preferably an electromechanical valve with an actuator, can be substituted for check valve  108 . 
     Valve  104  allows the operator to control the flow rate of the pressurized air or other gas. Preferably a ball valve, valve  104  is attached, such as by bolting, welding, or threaded attachment, to nozzle tube  110 . Valve  104  is most preferably attached sequentially to pipe  106 , check valve  108 , and nozzle tube  110 . Optionally and alternatively, an electromechanical valve can be substituted for both valve  104  and check valve  108 . 
     Valve  120  can further regulate the velocity of the pressurized air or other gas. Valve  104  can be closed to allow conventional pelletization processing without the need for pressurized gas injection. Both valve  104  and valve  120  are optional and either can be used alone without the other. Preferably, valve  104  is present for regulation of the pressurized gas and more preferably, valve  104  and valve  120  are used in synergistic combination for the greatest control and regulation of the pressurized air or other gas. 
     The positionable nozzle assembly is preferably located as shown in  FIG. 2  and detailed in  FIGS. 2   a ,  3 ,  4 , and  5 . A transport conduit as embodied in a transport pipe  18 , see  FIG. 2 , is preferably straight with the air or other gas being injected into elbow  102 .  FIGS. 2   a ,  3 , and  4 , are preferably in line with the axis of transport pipe  18  to maximize the effect of the injection on the pellet slurry and to uniformly aspirate the pellet slurry. The location of elbow  102 , or equivalent structure such as a “Y” configuration, is preferably in the first elbow after the pellet slurry leaves pelletizer  10 . However, the elbow  102  can be located in an optional elbow further from pelletizer  10 , not shown, and prior to dryer  20 . Optionally a multiplicity of nozzle tubes can be inserted in at least one elbow to synergistically facilitate transport to and through at least one transport pipe  18 . 
       FIG. 3  illustrates a portion of the positionable nozzle assembly  100  in a fully retracted position relative to the elbow  102 . As shown, the rearward end of the nozzle tube  110  is surrounded by collar  122  which guides the rearward end as the nozzle tube slides within cylindrical housing  128 . The nozzle tube  110  and collar  122  can be of a single body construction, but preferably the nozzle tube  110  and collar  122  are separate components attached together, such as by welding. The nozzle tube  110  and collar  122  are preferably welded at each end of the collar, at weldment  124  and weldment  126 . 
     The nozzle tube  110  and collar  122  are variably positionable and are freely slideable through the housing  128 . The forward end  130  of the housing  128  is threadingly attached to a seal transition collar  132  which is attached to elbow  102  at juncture  112 . The forward end of the nozzle tube  110  is slidingly supported within the central bore  133  of the collar  132 . Within the housing  128  and circumferentially positioned about the nozzle tube  110  is a tension spring  134 . At least one guide pin  136  is attached to the collar  122 . The guide pin  136  aligns with and is positionable within at least one groove  138  in housing  128  as detailed in  FIG. 5 . For larger transport pipes and nozzle assemblies, it is preferable to have at least two guide pins  136  that align positionably within at least two respective grooves  138  in the housing  128  to provide greater adjustment capability. Groove  138  is linearly elongate with the length of housing  128  and forms at least one angular recess  140  as shown in  FIG. 3 , or multiple recesses  140 ,  141  as shown in  FIG. 5 . 
     Returning to  FIG. 3 , tension spring  134 , preferably a coiled spring, seats on the forward face of collar  122  as well as on the rearward face of the seal transition collar  132 . In  FIG. 3 , the tension spring  134  is expanded for the retracted position of the nozzle tube assembly.  FIG. 4  shows the tension spring  134  compressed in the forwardmost position of the positionable nozzle assembly  100  in which the nozzle tube  110  is fully inserted into the lumen of elbow  102 . As shown, when fully inserted the collar  122  is received in the housing  128 , and guide pin  136  is locked in angular recess  140  as more clearly illustrated in  FIG. 5 . When the nozzle tube is only partially inserted, on the other hand, the guide pin  136  would be locked in angular recess  141 . 
     Nozzle tube  110  preferably is sealingly positioned in seal transition collar  132 ,  FIGS. 3 and 4 . Sealing is achieved by any mechanical means known to those skilled in the art including O-rings, “quad” rings, mechanical seals, and the like without being limited thereto. Preferably sealing is achieved using at least one O-ring  142  retained in a circumferential groove  144  in seal transition collar  132 . O-ring  142  fits sealingly about the diameter of nozzle tube  110  such that nozzle tube  110  can be sealingly and slidably positioned through the at least one O-ring  142 . Preferably at least two O-rings  142  are sealingly positioned in at least two respective circumferential grooves  144 . Most preferably, a multiplicity of O-rings  142  are sealingly positioned in an equal multiplicity of circumferential grooves  144 . 
       FIG. 5  illustrates a portion of the positionable nozzle assembly  100  in which the nozzle tube  110  is fully inserted into the lumen of elbow  102  approximately flush with juncture  114  as comparably illustrated and described above for  FIG. 2   a . Collar  122  has been inserted into housing  128  and guide pin  136  has moved through groove  138  to be firmly positioned in angular recess  140 . 
     Nozzle tube  110  can be generally positionable throughout a range from outside the exterior of elbow  102  within the lumen of seal transition collar  132  to at least the juncture  114  and optionally beyond. Preferably the fully retracted position is approximately flush with the exterior of elbow  102  and the fully inserted position is approximately at the juncture  114 . 
     Movement of the nozzle tube  110  within the positionable nozzle assembly  100  can be accomplished by any suitable method including manual or, preferably, through the use of one or more automated control systems including pneumatic, electrical, electronic, and hydraulic devices and methods, alone or in various combinations, and can optionally include programmable logic control, PLC. It is also possible to combine manual and automated control capabilities within the same nozzle assembly. Manual control necessitates specific placement of the positioning as determined by the angular recess  140  positions. If movement is automated, however, a multiplicity of positions can be made available. Use of guide pin(s)  136  and the associated groove(s)  138  and angular recesses  140  and  141  in  FIG. 5 , for example, would not be expected to be necessary for control using an automated control system. 
     A preferred embodiment of a positionable nozzle according to the present invention with an automated control system for positioning of the nozzle is shown in  FIGS. 6   a - 6   d . In this embodiment, the nozzle is moved to the desired position pneumatically using a pneumatic cylinder controlled by the user. The pneumatic cylinder is preferably a magnetically coupled rodless cylinder, generally designated by reference numeral  154 , which magnetically engages a carriage  160  that is fixedly connected to the nozzle tube  110  and collar  122  by a bracket or pin  162 . As shown, in  FIGS. 6   a  and  6   c  the pin  162  is preferably connected between the carriage  160  and collar  122 , which in turn is welded onto nozzle tube  110 . However, the pin  162  could be connected directly to the nozzle tube  110 . The pin  162  can be connected to the carriage  160  and collar  122 /nozzle tube  110  by any suitable connection method as would be known by persons of skill in the art, but is preferably bolted to the carriage  160  and collar  122 . The pin  162  passes through the housing  129  which surrounds the nozzle tube  110  and collar  122  by means of slot  139  in the housing  129  as shown in  FIGS. 6   b  and  6   d.    
     One such magnetically coupled rodless cylinder useful in the present invention is manufactured by SMC Corporation of America under Series CY1B. As shown in  FIG. 7 , the rodless cylinder  154  includes a cylinder tube  170  having a piston  172  therein that is equipped with a first magnet  174 . A second magnet  175  is supported in a body  176  of the carriage  160  outside the cylinder tube  170 . 
     A control circuit for moving the nozzle tube  110  using the pneumatic cylinder is outlined in  FIG. 8  and generally designated by reference numeral  190 . With reference to the nozzle tip  155 , the pneumatic cylinder  154  has a first air inlet  156  at its distal end  157  and a second air inlet  158  at its proximal end  159 . To move the nozzle tube  110  to the fully inserted forward position shown in  FIGS. 6   c  and  6   d , a jog-in mechanism such as push button  180  is activated, which changes the position of an air operated block valve  181 , to inject pressurized air into the first air inlet  156 . The air also is injected into a check valve  184  at the second air inlet  158  at the proximal end  159  which opens the check valve  184  and releases the pressurized air that was already in the proximal or forward end of cylinder  154 , thus causing the piston  172 , along with the carriage  160  that is magnetically engaged therewith, to move forwardly, with pin  162  moving in the slot  139  to the position shown in  FIG. 6   d.    
     Conversely, to move the nozzle tube  110  from the inserted position to a retracted position as shown in  FIGS. 6   a  and  6   b , a jog-out mechanism such as push button  182  is activated, which changes the position of an air operated block valve  181 , to inject pressurized air into the second air inlet  158 . The air also is injected into a check valve  185  at the first air inlet  156  at the distal end  157  which opens the check valve  185  and releases the pressurized air that was already in the distal or back end of cylinder  154 , thus causing the piston  172 , along with the carriage  160  that is magnetically engaged therewith, to move forwardly, with pin  162  moving in the slot  139  to the position shown in  FIG. 6   b . In between positioning events, check valve  184  and check valve  185  at the cylinder  154 , as controlled by the control circuit  190 , hold the nozzle tube in place by not allowing air to be released from either air inlet  156  or air inlet  158 . Check valve  184  and check valve  185  also provide speed control to moderate how quickly movement of the nozzle tube is effected. 
     The pressurized air used to move the piston and carriage  160  can be supplied from various air sources, such as an air tank compressor as is known by persons of skill in the art. With this pneumatic embodiment, any number of intermediate positions of the nozzle tube between the fully inserted ( FIGS. 6   c  and  6   d ) and fully retracted ( FIGS. 6   a  and  6   b ) positions can be realized through control of the amount of pressurized air being injected into the air inlets  156 ,  158 . Similar movement and control of the nozzle tube could alternatively be obtained through the use of a linear pneumatic cylinder, a hydraulic cylinder and power unit, or a servo-motor or a stepper motor together with a ball screw or acme screw, instead of the magnetically coupled rodless cylinder  154 , as would be known to those skilled in the art. However, the magnetically coupled rodless cylinder is preferred for the present invention. 
     It is also possible in accordance with the present invention that the preferred automatic control system for moving the nozzle can be combined with a manual movement of the nozzle tube, if desired. 
     Preferably nozzle tube  110  can be placed in a retracted position during the “start-up” of pelletizer  10  to eliminate its presence as an obstruction in the transport piping  15 . Unwanted agglomerates can easily be formed during the beginning phase of the pelletization process and allowing the pellet slurry to use the full inside diameter of transport piping  15  as facilitated by the retraction of nozzle tube  110  is beneficial. 
     Positionable nozzle assembly  100  is designed to allow the operator(s) to inject pressurized air or other gas into transport pipe  18  while having the option to adjust the location of the nozzle tube  110  in relation to the transport pipe  18  and the elbow  102 . The extent to which nozzle tube  110  can be retracted and inserted while still creating the desired aspiration is dependent upon, but not limited to, at least one of flow rate, pellet to transport liquid ratio, transport liquid temperature, diameter of the elbow  102  relative to the transport pipe  18 , distance between the elbow  102  and the dryer  20 , and the type of material being pelletized. 
     It is to be understood, as illustrated in  FIGS. 2   a ,  3  and  4 , that the outside diameter of nozzle tube  110  will be smaller than the inside diameter of elbow  102  at juncture  114 , for example. In this regard, the space in the lumen should be large enough to allow the combined largest dimensions of at least two pellets, as measured using pellets of the maximum size for the particular pelletizing system, to pass between the exterior of the nozzle tube  110  and the interior of elbow  102  at juncture  114 . Stated another way, the clearance area between the outside diameter of the nozzle tube and the inside diameter of the elbow lumen is large enough to allow at least two pellets, each having a maximum dimension for the pelletizer, to pass side by side therethrough without blocking, or clogging in, the clearance area. By way of example, without being limited thereto, one embodiment of the present invention is that of a 0.75 inch nominal nozzle tube  110  in combination with a 2 inch nominal nozzle influent pipe  118  to elbow  102 , a 2 inch nominal elbow  102 , and a 1.5 inch transport pipe  18  from elbow  102  to dryer  20 . Another embodiment is that of a 0.75 inch nominal nozzle tube  110  in combination with a 3.0 inch nominal elbow  102 , and a further embodiment is that of a 0.5 inch nominal nozzle tube  110  in combination with a 2.0 inch nominal elbow. 
     The orientation of the nozzle tube  110  in relation to the juncture  114  of elbow  102  in  FIG. 2   a  can be concentrically centered about the centerline of that juncture  114 , or reflected above the centerline, below the centerline, to the right or left of the centerline, or at any angle circumferentially about that centerline where the angle formed between the centerline of the nozzle tube  110  and the centerline of the juncture  114  of elbow can range from 0° to a maximum deflection. Maximum deflection is defined as that degree of deflection at which the exterior of nozzle tube  110  touches the interior of the juncture of elbow  102  and/or any apparatus into which the nozzle tube extends downstream of that juncture  114  of elbow  102 . Preferably the nozzle tube  110  is concentrically positioned and collinear about that centerline of juncture  114  of elbow  102 . It is understood that the centerline of juncture  114  of elbow  102  is colinear with the centerline of transport pipe  18  downstream of that juncture  114 . 
     The forward orifice  146  of nozzle tube  110  can be of any shape including round, square, rectangular, oval, polygonal, and the like and is preferably round. The diameter of the forward orifice  146  can be larger than, smaller than, or equal to the diameter of the nozzle tube  110  and is preferably equal thereto. When the diameter of forward orifice  146  is not equal to that of the nozzle tube  110 , the diameter taperingly increases or decreases, respectively, for only that portion of the nozzle tube  110  that is not in contact with the most proximate O-ring  142 ; see  FIGS. 3 and 4 . The diameter of the distal orifice  146  cannot, however, be larger than the inside diameter of the seal transition collar  132 . A decreasing taper  150  is illustrated in  FIG. 9   e  for the terminus of nozzle tube  110 . Similarly the forward orifice  146  can be semicircular as illustrated in  FIG. 9   c  or conchoidal to C-shape as in  FIG. 9   d.    
     The inside of nozzle tube  110  can be provided with many different variations including but not limited to at least one of spiraled, contoured, rifled, or tapered inner surfaces, and many combinations thereof.  FIG. 9   f  illustrates a conically tapered nozzle tube  110  wherein the taper decreases toward the forward orifice  146 . 
     The inside of nozzle tube  110  can also or alternatively contain one or more fins  152  as shown in  FIGS. 9   a  and  9   b . The fins can be straight and angled at 90° relative to the circumference of the nozzle tube  110 , as illustrated in  FIG. 9   a , or at a lesser angle. Similarly, the fins can be bent or contoured relative to the circumference of the nozzle tube  110  as illustrated in  FIG. 9   b . The fins can be of any length ranging from less than to equal the length of the nozzle tube  110 , and their height cannot exceed the radius of nozzle tube  110 . Preferably the fins  152  are less than the length of the nozzle tube  110  and are smaller in height than the radius of nozzle tube  110 . When multiple fins are included, they can also be placed at any angle in relation to each other and can be the same or different in construction. The purpose of the fins is to facilitate the creation of more turbulent flow within the transport pipe  18 . More particularly, the flow of the aspirated pellet slurry can range from laminar to turbulent. Without intending to be bound by any theory, the injection of the air or other gas into the pellet slurry aspirates the transport liquid from the pellets such that the transport liquid is transported in a laminar fashion along the inner surface of the transport pipe  18  while the vapor mist and pellets are propagated in a more turbulent flow through the center of transport pipe  18  along the length of the transport pipe  18 . In some cases, more turbulent flow may be desired, in which case fins may be advantageously added. 
     In accordance with the present invention, pressurized air or other gas can flow through nozzle tube  110  continuously or intermittently, most preferably continuously. This pressurized gas can be used to convey the pellets at a high velocity as described. This high velocity gas flow can be achieved using compressed gas producing a volume of flow exemplarily of at least 100 cubic meters per hour using a standard valve  104  for regulation of the pressure to at least 8 bar through the transport pipe  18 . The pipe  18  is standard pipe diameter, preferably 1.5 inch pipe diameter. To those skilled in the art, flow rates and pipe diameters will vary according to the throughput volume, material composition including filler, transport liquid temperature, level of crystallinity desired, level of moisture desired, and the size of the pellets and granules. The high velocity gas effectively contacts the pellet water slurry, generating water vapor by aspiration, and disperses the pellets throughout the slurry line to propagate those pellets at increased velocity to the dryer  20 , preferably at a rate of less than one second from the pelletizer  10  to the exit of the dryer  20 . The high velocity aspiration produces a mixture of pellets in an air/gas mixture which may approach 98-99% by volume of the gaseous mixture. Through adjustment of the nozzle tube insertion depth as well as the addition of surface variations inside the nozzle, the flow characteristics of the slurry within the transport piping can be altered. 
     Returning now to  FIG. 2   a , the angle formed between the vertical axis of influent pipe  118  and the longitudinal axis of the transport pipe  18  can vary from 0° to 90° or more as required by the variance in the height of the pelletizer  10  relative to the height of the entrance  22  to the dryer  20  as shown in  FIG. 2 . This difference in height may be due to the physical positioning of the dryer  20  in relation to the pelletizer  10  or may be a consequence of the difference in the sizes of the dryer and pelletizer. The preferred angle range is from about 30° to 60°, with the more preferred angle being about 45°. The enlarged elbow  24  into the dryer entrance  22  facilitates the transition of the high velocity aspirated pellet/water slurry from the incoming transport pipe  18  into the entrance  22  of the dryer  20  and reduces the potential for pellet agglomeration into the dryer  20 . 
     The outside surface of nozzle tube  110  and the inner lumens of influent pipe  118 , elbow  102 , effluent pipe  116 , and transport pipe  18  can be coated with surface treatments to reduce abrasion, erosion, corrosion, wear, and undesirable adhesion and stricture. These surface treatments can be at least one of nitriding, carbonitriding, and sintering. Similarly the heretofore mentioned surfaces can undergo high velocity air and fuel modified thermal treatments, electrolytic plating, electroless plating, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatments, and electrolytic plasma treatments, singly and in combinations thereof. These treatments metallize the surface, preferably fixedly attach metal nitrides to the surface, more preferably fixedly attach metal carbides and metal carbonitrides to the surface, even more preferably fixedly attach diamond-like carbon to the surface, still more preferably attach diamond-like carbon in an abrasion-resistant metal matrix to the surface, and most preferably attach diamond-like carbon in a metal carbide matrix to the surface. Other ceramic materials can be used and are included herein by way of reference without intending to be limited. The coating thickness should not exceed approximately 0.002 inches without appropriate modification to the diameters of the parts through which the coated surface must pass sealingly. 
     While the invention has been disclosed in its preferred forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents as set forth in the following claims.