Support ring for pellet dryer screen

Abstract: A pellet dryer screen support (30) including a two piece annular ring (31a,31b) which encircles and supports a center portion of the screen (14) from an external housing (12) to maintain the screen in cylindrical configuration and in concentric relation to a bladed rotor (16) rotatably positioned within the screen (14).

Description: Field of the Invention The present invention relates to a centrifugal pellet dryer comprising a dryer screen, a housing enclosing said screen and a screen support for rigidifying and supporting said screen. Such a centrifugal pellet dryer is known from, for example, US 3,458,045. Description of the Prior Art Centrifugal pellet dryers are well known and include an outer housing, a cylindrical screen oriented in the housing and a bladed rotor mounted in the screen for moving a slurry of water and pellets upwardly within the screen to enable discharge of water through the screen by centrifugal force. A slurry inlet is provided along with an outlet for water and an outlet for the dried pellets. Centrifugal pellet dryers of this type are disclosed in U.S. Patent Nos. 3,458,045; 4,565,015; 4,896,435 and 5,265,347 commonly owned by the Assignee of this application. In the operation of such dryers, the screen must be maintained in a cylindrical configuration concentric with the periphery of the rotor to maintain efficient operation of the dryer. While the above patents include structures for supporting the screen, the center portion of the cylindrical screen may become deformed from its cylindrical configuration due to the center portion not being adequately supported from the housing. In addition to the above mentioned patents, some dryers or material separators are rotated about a horizontal or inclined axis. The following U.S. patents disclose various horizontally disposed or inclined rotatable drums having perforated surfaces to separate materials: 264,824; 301,803; 319,572; 533,457; 1,596,428 and 2,536,054. Also, additional prior patents including a vertical screen and conveyor structure are disclosed in U.S. Patent Nos. 411,799; 4,017,387; 4,178,246; 4,570,359; 4,476,019; 5,187,880 and 5,611,150. The above mentioned patents disclose various screens or perforated members for receiving materials and which rotate or are provided with a rotor interiorly mounted with structures being illustrated for supporting the stationary screen or perforated member. However, none of the above patents discloses a two piece, rigid ring oriented in encircling contact with the central portion of a cylindrical screen in a centrifugal pellet dryer with the two piece ring including an outwardly extending flange for supporting engagement with brackets an the interior of the dryer housing. US 3,458,045 shows a centrifugal pellet dryer according to the preamble of claim 1. The screen support of the pellet dryer of US 3,458,045 comprises a one piece annular member engaging the internal periphery of the screen. Radial tabs extend from the external surface of said annular member through the said screen and are connected to corner braces that are secured to the outer housing of the pellet dryer. However, this screen support is not suitable for one piece dryer screens. Furthermore, the mounting of said screen support is inconvenient. Furthermore, US 3,581,407 shows no pellet dryer, but a grain conditioner having a support ring for a grain tank, said support ring consisting of a collar without rigidifying flanges. It is an objective of the present invention to provide a centrifugal pellet dryer with an improved screen support that is suitable for supporting both one piece screens and two piece screens and allows a more convenient mounting of the support structure and provides for a rigid support of the screen. According to the present invention, this objective is achieved by a centrifugal pellet dryer according to claim 1. Preferred embodiments of the invention are laid down in the dependent claims. Consequently, the screen support comprises a plurality of substantially rigid ring segments separably connected at end portions thereof and encircling and engaging the external periphery of the screen, at least one of said ring segments including a structure for supporting in association with said housing said screen, and wherein each of said ring segments includes an arcuate band for engagement with said screen and a radially extending flange on the external surface of said band in rigid perpendicular relation thereto for rigidifying said band, said flange extending substantially throughout the entire length of said band. The pellet dryer may include a vertically disposed housing having the cylindrical screen supported therein with a bladed rotor oriented in the screen for conveying a slurry of water and plastic pellets upwardly through the screen to enable centrifugal forces to discharge water outwardly through the screen while the dried pellets are discharged from an upper end of the screen and housing in a well known manner. The support ring is oriented generally in the vertical central area of the screen and is circular in configuration and of two piece construction to enable the support ring to be assembled on the exterior of the screen to maintain the central portion of the screen in a cylindrical configuration concentric with the rotor to enable effective upward conveyance of the slurry and effective discharge of water through the screen. The support ring is provided with an outwardly extending peripheral flange supportingly engaged by and connected to support brackets oriented in peripherally spaced relation an the interior of the housing thereby effectively supporting and maintaining the cylindrical configuration of the central portion of the screen. The supporting structure is provided for the central portion of an elongated, vertically disposed cylindrical screen in a centrifugal pellet dryer used for separating water from a slurry of water and plastic pellets which are conveyed upwardly in the screen by a bladed rotor with water being discharged centrifugally through the screen and dried pellets.discharged from an upper end portion of the screen. The structure for supporting the central portion of the screen also rigidly encircles and engages the screen to maintain its cylindrical configuration and maintain its concentricity with respect to the rotational axis of the bladed rotor. The center support ring includes an annular band provided with a radially extending peripheral flange on the external surface thereof for rigidifying the band thus forming a rigid ring engaged with the cylindrical screen. Preferably, the radial. flange includes bolt receiving apertures to connect the flange to brackets an the interior of an outer housing of the pellet dryer. Preferably, the ends of the radial flange includes a depending end flange with adjacent end flanges an the peripheral flange being connected together by separable fasteners to rigidly connect the multiple components defining the annular ring and enabling assembly and disassembly of the annular ring in relation to the cylindrical screen. According to yet another preferred embodiment of the invention, the annular ring including a wide inner band and a narrow outer band member integral with the inner edge of the radial flange and in contact with the inner band with the abutting ends of the inner band and the outer band member being staggered in relation to each other to more effectively rigidify the annular ring. These 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 apart hereof, wherein like numerals refer to like parts throughout. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic sectional view illustrating the center support ring of the present invention incorporated into a centrifugal pellet dryer; Figure 2 is a top plan view of the center support ring; Figure 3 is a side elevational view of the center support ring; Figure 4 is a detailed plan view of the relationship between the band and outer band member on a radial flange and end flanges on the ends of the radial flange; Figure 5 is a fragmental elevational view illustrating the manner in which the end flanges on the outer band member on the radial flange are interconnected by a separable fastening bolt; and Figure 6 is a further detailed plan view of a segment of the center support ring illustrating the weld connection between the flange, the outer band member and band forming the annular ring. DESCRIPTION OF THE PREFERRED EMBODIMENT Although only one preferred embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its scope to the details of construction 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 practiced or carried out in various ways. Also, in describing the preferred embodiment, 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. Referring to the drawings, Figure 1 illustrates a centrifugal pellet dryer generally designated by reference numeral 10 and which includes a vertical housing 12 in which a cylindrical screen 14 is mounted. The screen 14 encloses and is concentric to a rotor generally designated by reference numeral 16 which includes a central shaft 18 and inclined blades 20 to elevate a slurry of water and plastic pellets from an inlet 22 at the bottom of the screen 14 to an outlet 24 at the upper end portion of the screen. Water is discharged through the screen 14 and discharged through a water outlet 26 at the bottom of the housing 12. The upper and lower ends of the screen are supported by annular ring-like members 28 or other well known and conventional support structures such as those disclosed in the aforementioned commonly owned prior patents. The center support ring of the present invention is generally designated by reference numeral 30 and is oriented at a central portion of the vertical height of the screen 14 in order to support and maintain the cylindrical configuration of the screen 14 and to maintain the concentricity of the screen 14 with the rotational axis of the shaft 18. The center support ring 30 is supported by a plurality of bracket structures 32 secured at peripherally spaced points in the interior of the housing 12. The specific structure of the center support ring 30 is illustrated in Figures 2-6 and includes a cylindrical band 34 consisting of two semicircular elements joined at diametrically opposed locations by separable fastener structures 36. The band 34 includes a band member 38 and an outer band member 40 in connected relation substantially throughout their length. The vertical height of the band member 38 may be in the order of 3 inches and the outer band member 40 may be 1 inch in height. Centrally located on the exterior of the band member 38 and at the upper edge of outer band member 40 is a rigidifying flange 42 that is rigidly fixed to the exterior of the inner band member 38 generally at the central location thereof with the flange 42 being welded to the exterior of the inner band member 38 and along the top edge of outer band member 40. The flange 42 may be about 2 inches wide and includes a plurality of peripherally spaced bolt holes 44 for receiving bolts 46 which extend through corresponding holes in the brackets 32 attached to the housing 12 thereby separably connecting the center support ring 30 to the interior of the housing 12 to support the center support ring and thus support and rigidify the central portion of the screen 14. The semicircular segments of the annular ring 34 are interconnected by a fastener bolt assembly 48 which extend through depending flange ends 50 at the opposite ends of the flange segments 42 as illustrated in Figure 5. The flanges 50 are formed by bending end portions of the flange segments 42 downwardly and provided with apertures. The flanges 50 are spaced apart slightly to enable assembly and rigidified connection between the semicircular segments of the annular support ring 30. As illustrated in Figure 4, the inner band member 38 has terminal ends 52 which are generally aligned with the space between the flanges 50 with the outer band member 40 including end edges 54 which are staggered in relation to the end edges 52 so that a telescopic over lapping joint is provided between the band members 38 and 40 as illustrated in Figure 4. As illustrated in Figure 6, the flange 42 is welded to the narrow outer band 40 at spaced areas 56 thereby forming a rigid assembly of the flange 42 and outer band member 40. The location of the bolt holes 44 may vary depending upon the configuration of the housing and the location of the supporting brackets 32. The center support ring 30 can be easily assembled onto the screen by positioning the semicircular segments of the ring 30 around the central portion of the screen 14 and connecting the end flanges 50 by the use of fastening bolts 48. This rigidifies the central portion of the screen and maintains its cylindrical configuration and maintains its concentricity with the rotational axis of the rotor 16. The flange segments 42 are then connected to the brackets 32 on the housing 12 by the assembly bolts 46 thus providing support for the center support ring and the central portion of the screen 14. The configuration of the housing may vary and the location of the brackets on the housing may vary depending upon the shape and configuration of the housing. The slurry inlet, water outlet and pellet outlet and the structure for driving the rotor are all well known structures operating in their usual manner. The center support ring provides an easily assembled and effective structure for supporting and maintaining the cylindrical configuration of the central portion of the screen in various types of centrifugal plastic pellet dryers. The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of claim 1.

Claims: A centrifugal pellet dryer comprising a dryer screen (14), a housing (10) enclosing said screen (14), a screen support (30) for rigidifying and supporting said screen, characterized in that said screen support (30) comprises a plurality of substantially rigid ring segments separably connected at end portions thereof and encircling and engaging the external periphery of the screen (14), at least one of said ring segments including a structure (42) for supporting in association with said housing (10) said screen (14), and wherein each of said ring segments includes an arcuate band (38, 40) for engagement with said screen and a radially extending flange (42) on the external surface of said band (38, 40) in rigid perpendicular relation thereto for rigidifying said band (38, 40), said flange (42) extending substantially throughout the entire length of said band (38, 40). The dryer as defined in claim 1, wherein a telescopic overlapping joint is provided between the said ring segments to provide a rigid connection therebetween. The dryer as defined in one of the preceding claims, wherein said flange (42) includes end flanges (50) in perpendicular relation to said flange (42) and in perpendicular relation to said band (38, 40) and separable fastening structures (48) interconnecting said end flanges (50) to separably connect adjacent ends of adjacent ring segments. The dryer as defined in one of the preceding claims, wherein each of said ring segments is semicircular in configuration for encircling engagement with a cylindrical screen (14) for maintaining the centrifugal configuration of said screen (14) and supporting the screen (14) in concentric relation to a bladed rotor (16) within the screen. The dryer as defined in one of the preceding claims, wherein said screen support (30) is oriented generally at a central portion of an elongated vertically disposed screen (14). The dryer as defined in one of the preceding claims, wherein each ring segment includes an inner band (38) of cylindrical configuration for engagement with said screen (14), a reinforcing band (40) on the exterior of said inner band (38) and having a vertical height substantially less than the inner band (38), wherein said peripheral flange (42) extends outwardly from the upper end of said reinforcing band (40) in perpendicular relation to the reinforcing band (40) and said inner band (38). The dryer as defined in claim 6, wherein each of said ring segments reinforcing band (40) and perpendicular flange (42) are semicircular in configuration. The dryer as defined in one of the preceding claims, wherein said flange (42) includes bolt openings (64) for detachable support from brackets (32) on an interior of said housing (10). The dryer as defined in one of the preceding claims, wherein each end of each perpendicular flange (42) is provided with an end flange (50) perpendicular to the flange and perpendicular to said arcuate band (38, 40), a separable fastener (48) interconnecting said end flanges (50) for assembling the semicircular ring segments in encircling contact with said screen (14). The dryer as defined in one of claims 6 to 9, wherein said inner band (38) has end edges (52) oriented in staggered relation to end edges (54) of said reinforcing band (40) whereby end portions of the inner band (38) and the reinforcing band (40) are in overlapping staggered relation.

Inventors: HUMPHRIES TONEY REID II, NICCUM TODD ANTHONY, WOODSON WILLIAM DOUGLAS, HUMPHRIES, TONEY REID, II., NICCUM, TODD ANTHONY, WOODSON,WILLIAM DOUGLAS
Applicants: GALA INC, GALA INDUSTRIES, INC.
Application year: 2000
Main classification: F26B5
IPC codes: F26B5, B29B9, F26B17