Abstract:
An apparatus for processing materials provides a material processing chamber, formed from an enclosure having a top and a bottom. The bottom has an opening therein, and a shaft extends through the opening and into the chamber. A bearing assembly may be arranged about a lower portion of the shaft, the bearing assembly including a bearing extension arranged about a portion of the shaft. The bearing extension has a portion thereof extending through the opening of the bottom of the chamber. A first seal assembly forms a first seal between the bearing extension and the bottom of the chamber, and a second seal assembly forms a second seal between the bearing assembly and the shaft.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Industrial dryers are used for drying a wide range of materials, such as dyes, bleach, sugar, flame retardants, carbon, fungicides, vitamins, and wood chips. These driers may include large drying chambers, where the materials are exposed to drying conditions for a period of time. Such drying conditions may include heat, desiccants, or continued movement of the materials. For example, the Turbo-Dryer®, manufactured by Wyssmont®, provides a large drying chamber with a number of trays stacked therein. The trays may rotate about a central shaft extending through the drying chamber and connected to a drive source. The material passes down each tray in the stack as the trays rotate, and heat is applied through a duct connected to the drying chamber. As a result, the material is thoroughly and evenly dried. 
         [0002]    Because the drying chamber includes openings for apparatus such as the central shaft, it also presents an opportunity for drying conditions such as heat or gasses to escape. This results in increased consumption of energy and resources, and thus increased costs. 
         [0003]    Currently, assemblies for sealing the openings are inadequate for processing materials under certain operating conditions such as where a closed environment is required or desirable. For example, as shown in  FIG. 1 , rotatable shaft  32  extends through an opening in a bottom plate  14  of the dryer. The shaft  32  is connected to a reducer  84  and a turntable sweeper  80  above a turntable  82 . The turntable  82  is further connected to a first casting  70 , which is connected to drive gears  88 , located outside the drying chamber  89 . Accordingly, while an upper portion of the first casting  70  extends above the opening in the bottom plate  14  into the drying chamber  89 , a lower portion of the first casting  70  resides below. Thus, as the first casting  70  rotates air may escape through a space between the dryer bottom  14  and the casting  70 . 
         [0004]    As an attempt to solve this problem, seals have been placed between the dryer bottom  14  and the casting  70 . For example, a seal plate  12  may be connected to the dryer bottom  14  and extend towards the casting  70 . A packing gland  18  further extends towards the casting  70 , with packing material  16  supported at a junction thereof by follower  31 . However, this seal has proven ineffective in preventing leakages in certain applications. For example, problems arise as the first casting  70  rotates. Additionally, due to the size of the opening in the dryer bottom between the seal plates  12 , a greater opportunity for leakage is presented. However, such size is necessitated by the positioning of the first casting  70 . 
         [0005]    Due to the deficiency of existing seal assemblies in preventing leakages, quantities of heat, gasses, and other agents employed within the dryer are wasted. In turn, costs of operating the dryer are increased, and resources are depleted more quickly. Accordingly, an improved sealing assembly is desired. 
       SUMMARY OF THE INVENTION 
       [0006]    An apparatus for processing materials according to an embodiment of the present invention provides a material processing chamber, formed from an enclosure, having a top and a bottom. The bottom has an opening therein, and a shaft extends through the opening and into the chamber. A bearing assembly may be arranged about a lower portion of the shaft, the bearing assembly including a bearing extension arranged about a portion of the shaft. The bearing extension has a portion thereof extending through the opening of the bottom of the chamber. A first seal assembly forms a first seal between the bearing extension and the bottom of the chamber, and a second seal assembly forms a second seal between the bearing assembly and the shaft. 
         [0007]    In the above embodiment, the first seal assembly may comprise a seal plate connecting the dryer bottom and the bearing extension. As desired, packing material may be positioned proximal to a junction of the seal plate and the bearing extension. Optionally, a pressure purge, delivering a gas such as nitrogen, may provide increased pressure to an area surrounding the junction of the seal plate and the bearing extension. 
         [0008]    The second seal assembly may include a casting surrounding the shaft, with packing material positioned between the casting and the shaft. Similar to the first seal assembly, a pressure purge may provide increased pressure to an area of the packing material. 
         [0009]    An apparatus for processing materials according to another embodiment of the present invention includes a material processing chamber formed from an enclosure having a top and a bottom, the bottom having an opening therein. The apparatus further includes a shaft extending through the opening within the bottom and into the chamber, a bearing assembly concentrically arranged about a lower portion of the shaft, and a bearing extension connected to the bearing assembly and concentrically arranged about a portion of the shaft. The bearing extension may have a portion thereof extending through the opening of the bottom of the chamber. Further included is a seal assembly forming a seal between the bearing extension and the bottom of the chamber. 
         [0010]    An apparatus for processing materials according to an even further embodiment of the present invention includes a processing chamber formed by at least one surrounding wall, a top wall, and a bottom wall having an opening. This apparatus further includes a rotatable shaft extending through the opening within the bottom and into the chamber. A bearing assembly having an extension surrounds the shaft as it extends through the opening within the bottom wall. A sealing system provides a seal about the extension of the bearing assembly as it extends through the opening within the bottom. The sealing system comprises a plate surrounding the extension within the opening, the plate attached to the bottom, and an enclosure coupled to the plate and the extension of the bearing assembly, the enclosure positioned proximal to a juncture of the plate and the extension. Further, packing material is provided within the enclosure for forming a seal at the juncture, and a gas source supplies a gas under pressure within the enclosure. A compression member associated with the enclosure applies a compressive force to the packing material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a cross-sectional view of a sealing assembly according to prior art. 
           [0012]      FIG. 2  is a cross-sectional view of an apparatus according to an embodiment of the present invention. 
           [0013]      FIG. 3  is a cross-sectional view of a first sealing assembly and a second sealing assembly according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 2  shows an example of an apparatus  100  for processing materials according to an embodiment of the present invention. In this example, the apparatus  100  may be used to process (e.g., to dry) various materials, such as salts, powdered milk, or chemicals, as they undergo processing. In view of the improved seal assembly, to be described, the apparatus  100  has particular applications where a closed environment is desirable, such as in pyrolizing various materials (e.g., polymers). The apparatus  100  has particular application where toxic or reactive gasses may be used or are generated with the apparatus during use. The apparatus  100  includes a chamber  110 , in this instance a drying chamber, wherein the materials are processed. The apparatus  100  further includes at least one drive assembly  160 , which may power operations within the chamber  110 , though being located outside. 
         [0015]    The drying chamber is cylindrically enclosed by sidewall  116  which extends around the circumference of the chamber  110 , a top plate  112 , and a bottom plate  114 . The chamber  110  is supported on a base  174  by supports  170  and connected expansion joints  172 . The expansion joints  172  may be wheels attached to the supports  170 . Alternatively, the expansion joints  172  may be wheels attached to the base  174  underneath the supports  170 . In either embodiment, the expansion joints  172  enable the supports  170  to move as the chamber expands due to, for example, increased heat or gasses therein. This reduces stress applied to the structure of the apparatus  100 . 
         [0016]    Inside the chamber  110 , the material to be processed may be placed on one or more stacked trays  120 . Each tray is connected to a stanchion  126  which is attached around a shaft  130 . Coupled to the stanchions  126  is a turntable  182 . According to one embodiment, the turntable  182  is connected to a second shaft which surrounds the shaft  130 . 
         [0017]    As will be further described below, a bearing assembly  250  may also be attached to the turntable  182  as well as to drive gears  280 , directly or indirectly. Accordingly, the drive gears  280  cause the bearing assembly to rotate, which in turn causes the turntable  182  to rotate. Further, the turntable  182  will cause the stanchions  126  and trays  120  to revolve. 
         [0018]    A tray wiper  122  in the nature of a flat flexible panel may be positioned above each tray  120 . As each tray  120  rotates, the tray wiper  122  transfers the material to the next tray. A rigidly mounted leveler  125  brushes across a top of the material placed thereon, thereby leveling the material and exposing materials underneath the top portion to the environment within the chamber  110 . The material that is spilled by the tray wiper  122  falls onto catch plate  124 . This plate  124 , angularly positioned with respect to the trays  120 , causes the material which is spilled off a tray  120  above to fall into a tray  120  below. In this manner, the material being processed cascades downwardly from the top tray to the bottom tray. 
         [0019]    According to one aspect, a turntable sweeper  180  may be positioned above the turntable  182 . The turntable sweeper  180  may prevent complications potentially caused by materials falling onto the turntable  182 . 
         [0020]    As the processed material is being rotated and moved as described above, further drying elements may be implemented within the chamber  110 . For example, several sets of fan blades  140  may be included in the chamber  110  to facilitate circulation of gasses therein. The fan blades  140  may be connected to respective rings  142  which are coupled to the * shaft  130  by keys  146 . The shaft  130  may extend beyond the bearing assembly  250  and connect to a reducer  190  at its lower end. The reducer  190  may be powered electrically, or by other sources such as a battery, steam, gas, or a mechanical crank. As the reducer  190  causes the shaft  130  to rotate, fan blades  140  would in turn rotate, thus pushing air across the trays  120 . 
         [0021]    The processed material may further be exposed within the chamber  110  to air or gasses provided through an inlet  152 . For example, a duct may be connected to the inlet  152 , and heated air, gasses, desiccants, or other inert, reactive, or non-reactive gasses may be provided to the chamber  110  through the duct. An exhaust  150  provides an outlet for the air or gasses. According to one embodiment, ducts connected to the exhaust may lead to a conditioning unit further connected to the inlet  152 , thereby allowing the air or gasses to be recycled through the chamber  110 . 
         [0022]    The bearing assembly  250  provides additional support for the turntable  182 , stanchions  126 , and trays  120 . The bearing assembly  250  may be formed of any of a variety of materials. Materials with increased strength and durability may be desirable in light of the weight supported by the assembly  250 . Examples of such materials include steel, such as stainless steel, cast iron, or any of a variety of other metals. 
         [0023]    The bearing assembly  250  includes a support plate  252  attached beneath the turntable  182 , an extension  254  extending alongside the shaft  130 , and a base plate  256 . According to one embodiment, the extension  254  may be cylindrical, surrounding a portion of the shaft  130 . The support plate  252  and base plate  256  may be circular, and thus connected to the extension  254  around its circumference. 
         [0024]    To prevent the air or gasses provided to the chamber  110  from escaping, seal assemblies are placed around the shaft  132  and near the opening  118 . As better seen in  FIG. 3 , a first seal assembly  210  is implemented to prevent leakages through the opening  118  in the bottom plate  114 . A seal plate  212  is connected to the bottom plate  114  and extends to the bearing extension  254 . A clamp  214  may be used to secure the seal plate  212  to the bottom plate  114 . 
         [0025]    Packing material  216  may be positioned at a point where the seal plate  212  meets the bearing extension  254 . The packing material  216  may be vinyl, asbestos, or any other type of packing material. According to one embodiment, the packing material  216  may include a lantern ring  236 . Additionally, a follower  234  may be positioned beneath the packing material  216 . The follower  234  may be supported by gland  232  and stiffener  230 . 
         [0026]    According to a further aspect, the first sealing assembly  210  may additionally include a purge  220 , such as a nitrogen purge, to operate in conjunction with the packing material  216  and surroundings. For example, a source may provide nitrogen gas through the purge  220  to the packing material  216 . According to one embodiment, the nitrogen gas would cause the packing material  216  to expand. However, the lantern ring  236 , follower  234 , gland  232  and stiffener  230  will provide a boundary or even a reactive force against the packing material  216 . Thus, the packing material  216  will be forced to fill any openings between the seal plate  212  and the bearing extension  254  as it expands. 
         [0027]    A second seal assembly  260  may be implemented to prevent leakages along the shaft  130 . For example, air or gasses may leak through a space  292  between the turntable  182  and the shaft  130 , further through a space  294  between the support plate  252  and the shaft  130 , and downwardly along a length of the shaft  130 . Accordingly, second seal assembly  260  may be implemented as described in more detail below. 
         [0028]    As mentioned above, the shaft  130  may extend to connect to the drive assembly  160 . As shown in  FIG. 3 , the bearing assembly  250  extends around a portion of the shaft  130 . According to one embodiment, the bearing assembly  250  may include a first casting  270 , which connects to drive gear  280 . A second casting  272  may partially reside within the first casting  270 , with bushings  276  positioned between the first casting  270  and second casting  272 . The first and second castings  270 ,  272  may be formed of any of a variety of materials. For example, the castings  270 ,  272  may be plastic, ceramic, polymer, metal, or any other material. 
         [0029]    According to one embodiment, the first casting  270  and bearing assembly  250  may rest partially on top of the second casting  272 . In this regard, the first casting  270  and bearing assembly  250  may rotate as the second casting  272  remains stationary. Such rotation may be facilitated by the bushings  276 , as well as by thrust bearing  278 . The thrust bearing  278  may be spheres or rollers held in place between the first casting  270  and second casting  272 , thereby reducing friction between the elements. 
         [0030]    The second seal assembly may be located between the second casting  272  and the shaft  130 . Similar to the first seal assembly  210 , the second seal assembly  260  may include packing material  266  positioned between the second casting  272  and the shaft  130 . Gland  262  may be positioned beneath the packing material  266 , and a purge  290  may be fed to the packing material  266 . The purge  290  may provide a gas or fluid, such as nitrogen. The gland  262  keeps the packing material  266  compressed, thereby preventing any leakage. As seen in the second seal assembly  260  of  FIG. 3 , the gland  262  may be an “L” shaped piece of metal or plastic supported underneath the packing material  266 , as opposed to the combination of follower  234  and straight gland  232  used in the first seal assembly  210 . 
         [0031]    As can be seen, the first seal assembly  210  prevents leakages through the opening  118  while the second seal assembly  260  prevents leakages through and/or around the shaft  130 . These seal assemblies  210 ,  260  may be used either alone or in conjunction with one another. Regardless, each assembly  210 ,  260  permits rotation of the shaft  130  and the bearing extension  254  without sacrificing resources. 
         [0032]    As mentioned above, the purges  220 ,  290  provided in the first and second seal assemblies  210 ,  260  may cause the packing materials  216 ,  266  to expand. Alternatively or additionally, the purges  220 ,  290  may provide an increased air pressure to areas surrounding the seals. Accordingly, the increased pressure with respect to the pressure in the chamber  110  prevents air or gasses from escaping the chamber  110 . 
         [0033]    Although the chamber  110  in the apparatus  100  described above is a drying chamber, it should be understood that the first sealing assembly  210  and the second sealing assembly  260  may be used to prevent leakages from any type of material processing chamber. For example, the chamber  110  may encapsulate processes for, inter alia, freezing, grinding, purifying, pulverizing, separating, or sublimating. Further, the chamber  110  may be any of a variety of sizes and shapes. 
         [0034]    Moreover, the inlet  152  may provide any of a variety of fluids or gasses to the chamber  110 . Accordingly, while providing hot air and a desiccant may be most desirably provided to a drying chamber, providing a different type of gas or fluid may be more desirable for a different process. 
         [0035]    Further, the gasses or fluids provided through purges  220  and  290  may vary in relationship to the gasses or fluids in the chamber  110 . For example, nitrogen gas (N 2 ) may provide a higher pressure at the first and second seal assemblies  210 ,  260  to further prevent gasses from escaping the chamber  110 . However, if a process within the chamber  110  involved circulation of nitrogen gas, a different gas may be provided through purges  220 ,  290 . 
         [0036]    Shaft  130  may be formed of metal or any variety of other materials. Further, although the apparatus  100  as described herein includes a rotating shaft  130 , the shaft  130  may be capable of other motions, such as gyrating. 
         [0037]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.