Abstract:
A device for feeding a granular material from an upstream source to a downstream location such as a mobile container. The device comprising a conduit for receiving a flow of said granular material and which has an outlet for delivering granular material to said location. Then device further comprises a delivery system for delivering a stream of gas to the conduit to entrain and accelerate at least a portion of the granular material flowing therethrough, and an apparatus for directing the gas stream so that granular material is propelled from the outlet in a plurality of directions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority under 35 U.S.C. § 119 to British Patent Application No. 9809478.2 filed May 5, 1998. 
     BACKGROUND OF THE INVENTION 
     A. Field of the Invention 
     The present invention relates to a feeding device for delivering granular material or the like. Particularly, but not exclusively, the invention relates to a device for feeding granular material into a container. More particularly still, the invention in one embodiment provides a device for top entry feeding of granular material such as polymer beads, into containers such as rail cars. 
     B. Description of the Related Art 
     It is conventional to transfer granular materials from the end of a process or production line into mobile containers, such as railcars, for transport. Currently transfer of the granular material to the container is essentially a two stage process in which the material is first conveyed to large elevated storage silos using pneumatic pipe lines. Such silos typically have massive steel support structures which must be capable of withstanding extreme weather conditions and even earthquakes. From the silos, the material may then be discharged under gravity to fill mobile containers positioned below. Typically, the material may exit the silo via a delivery system comprising two delivery tubes (forming in appearance an inverted V shape) to deliver material to opposite ends of a trailer in an attempt to maximize filling. 
     A disadvantage of the conventional systems mentioned above is the relatively high construction cost associated with the provision of multiple large elevated silos. In addition, such systems have limited filling efficiency. 
     It is an object of the present invention to obviate or mitigate the above disadvantages. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a device for feeding a granular material from an upstream source to a downstream location, the device comprising a conduit for receiving a flow of said granular material the conduit having an outlet for delivering said granular material to said location, means for delivering a stream of gas to the conduit to entrain and accelerate at least a portion of the granular material flowing therethrough, and means for directing the gas stream so that granular material is propelled from the outlet in a plurality of directions. 
     With the device according to the present invention there is no need to provide large expensive storage silos since material can be continuously fed from a supply line, such as a conventional pneumatic supply line, to a container, or succession of containers. Moreover, because the material is projected from the device in a plurality of directions, container filling efficiency is improved. An embodiment of the present invention may be used to fill a container with a filling efficiency of greater than 96% of the volumetric capacity of the container. 
     With referred embodiments of the invention material is delivered to the device in a dense phase (e.g. plug flow) at a low velocity (typically less than 8 ms −1 ) which minimizes damage to the material. The material is however distributed by the device in a lean phase, evenly mixed with the gas stream. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is a half sectioned side elevation of a feeding device according to the present invention; 
     FIG. 2 is a plan view from above of the feeding device of FIG. 1; 
     FIG. 3 is an expanded view of a detail of the feeding device of FIG. 1; 
     FIG. 4 is a cross sectional view of the device of FIG. 1 taken on the line A—A; 
     FIG. 5 is a cross sectional view of the device of FIG. 1 taken on the line B—B; and 
     FIG. 6 is a schematic drawing illustrating operation of the device of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The particular embodiment of the invention illustrated in the drawings is a device designed for top entry feeding of polymer beads into containers such rail cars. Referring to the drawings, and particularly FIG. 1, the device comprises a hopper  1  which receives the polymer beads via a flanged inlet  2 . At its lower end, the hopper  1  has downwardly tapered section la which tapers inwardly to a delivery chute  3  which has a flared lower end terminating in a radial flange  4 . The top of the hopper  1  is closed by a cover plate  5  which is fitted with a filtered air vent  6 . The top end of an air pipe  7  (which extends axially along the hopper  1 ) protrudes through a collar  30  at the center of the cover plate  5  and terminates in a flanged air inlet  8 . The axial position of the air pipe  7  is maintained (and is adjustable) by a bolt  31  which extends through the collar  30 . 
     The air pipe  7  extends along the axis of the hopper  1  and a short distance into the delivery chute  3 , the lower end of the air pipe  7  being centralized within the delivery chute  3  by spacers  11 . A generally conical deflector  9  is fitted within the bottom opening of the air tube  7  by way of radial mounting members  10 . A frusto-conical member  12  is fitted around the air tube  7  in the tapering portion la of the hopper  1 . The frusto-conical member  12  tapers outwardly towards the walls of the hopper  1  so that an annulus  13  is defined between the member  12  and the narrowing wall of the hopper portion la. The member  12  is fixed to the air pipe  1  by way of a collar portion  12   a  which receives a bolt  14  which can be tightened onto the air pipe  7 . This arrangement allows adjustment of the axial position of the member  12  to adjust the width of the annulus  13 . 
     An insert outlet member  15  is mounted within the opening of the delivery chute  3 . The insert member  15  is hollow and comprises a generally cylindrical portion  15   a  and an outwardly and downwardly flared lower deflector portion  15   b  which terminates with a radial flange  15   c . A radial outlet  20  is defined between the flange  4  of chute  3  and the flange  15   c . The insert member is supported by a collar  16  which is slidably mounted within the delivery tube  3 , and members  17  which extend between the portion  15   a  of the insert member  15  and the collar  16 . The collar  16  is secured in position by a nut and bolt arrangement  18  which allows for the position of the collar, and thus the position of the insert member  15 , to be axially adjusted within the delivery tube  3 . 
     The inter-relation and function of the various components of the device will now be explained by the following description of the operation of the device. 
     The device is designed to receive polymer beads delivered from a pneumatic conveyor (not illustrated) to the inlet  2 . The device is particularly adapted to receive the polymer beads at a relatively low velocity (typically 4 to 8 meters per second), which is carefully controlled (in accordance with known techniques) to provide plug phase flow. That is, polymer beads are metered into the pneumatic supply line at a carefully controlled rate to ensure formation of discontinuous “plugs” of material which are effectively interspersed with “cylinders” of compressed air. This is a known form of supply system which has been used to deliver granular material from production lines to conventional storage silos. The system is advantageous in that it minimizes damage to the material. However, the flow rate is insufficiently high to fill, for instance, conventional railway cars in an efficient manner. The device of the present invention provides additional propulsion to increase the feed velocity of at least some of the polymer beads and effect a high container filling efficiency. 
     The air/polymer beads delivered to the hopper  1  will establish a cyclonic motion within the hopper  1  around the central air tube  7 . This serves to separate the polymer beads from the air; the relatively heavy beads will fall within the hopper  1  whereas the supplying air is exhausted via the filtered air vent  6 . Material within the hopper  1  will fall through the annulus  13 , defined within the tapered portion la of the hopper  1  by the frusto-conical member  12  and into the delivery chute  3  (passing between the spacers  11 ). 
     A jet of compressed air is supplied to the delivery chute  3  via air pipe  7  (from a centrifugal fan or roots type blower or similar source positioned at the air pipe inlet  8 ). The air stream from the air pipe  7  is deflected radically by the conical deflector  9  which functions to produce a generally annular air flow towards the outlet of the delivery tube  3  which will entrain the polymer beads which fall through the annulus  13 . Thus, the majority of the polymer beads flowing through the delivery chute  3  will be entrained and accelerated by the air flow from the air pipe  7  and conveyed through the annular gap  19  to the radial outlet  20 . Whilst most of the polymer beads will be conveyed in this way to the radial outlet  20 , turbulence in the region of the deflector  9  (i.e. the point at which the air stream from air pipe  7  mixes with the polymer beads) will cause some of the beads to fall under gravity through the insert  15  and vertically out from the portion  15   b.    
     The overall effect of the device, which is schematically illustrated in FIG. 6, is to deliver the majority of the polymer beads in a generally radial direction (firing the beads towards the walls of a container  21  through a 360° angle) whereas a smaller portion of the beads will be gravity fed in a vertical direction. The effect is to provide a distribution of the polymer beads which results in very efficient filling of the container  21 . 
     The device is specifically designed to allow adjustment of various components to adapt the device for feeding a variety of different materials, having different bulk densities and granule sizes, and at different rates. That is: 
     i) The position of the frusto-conical member  12  on the air pipe  7  may be adjusted (by releasing the bolt  14  and sliding the collar  12   a  along the pipe  7 ) to vary the width of the annulus  13  through which the granular material is metered into the air stream from the air pipe  7 . 
     ii) The axial position of the insert  12  within the delivery chute  3  can be adjusted (by releasing the nut and bolt arrangement  18  and sliding the collar  16  along the tube  3 ) to adjust the width of the annulus  19  and the cross-sectional area of the radial discharge outlet  20 . 
     iii) The collar and bolt arrangement  30  and  31  allows for adjustment of the position of the central air pipe  7  to vary the axial distance between the deflector  9  and the insert  15 . 
     It is envisaged that in most applications the width of the annulus  13  will be adjusted within the range 5 to 50 mm, the axial separation of the deflector  9  from the top of the cylindrical portion  15   a  of insert  15  will be adjusted between 20 and 100 mm, and the cross-section dimension of the radial discharge annulus will be adjusted to a width of between 10 and 100 mm. By carefully setting up the device for a particular material it has been found possible to fill mobile containers such as railcars to a level in excess of 96% of their volumetric capacity. 
     It will be appreciated that the device described above is not limited in its application to feeding polymer beads. The device could be utilized to feed any other material of an essentially particulate or powdered nature which can be entrained within an air stream. Neither is it necessary to deliver the material to the device in a plug phase flow. It will be readily apparent to the appropriately skilled person that many modifications can be made to the detail of the embodiment described above which is provided as an example only.