GB2082758A

GB2082758A - Cooling Pellet Material

Info

Publication number: GB2082758A
Application number: GB8122979A
Authority: GB
Original assignee: Koppers Co Inc
Current assignee: Beazer East Inc
Priority date: 1980-08-21
Filing date: 1981-07-24
Publication date: 1982-03-10
Also published as: DE3131425A1; AU7279981A; BR8104833A; FR2488985A1

Abstract

A method and apparatus for cooling pellet material is disclosed in which a stream of pellet material (22) to be cooled is introduced into an upright cooler and is then split into four substantially equal streams (40, 42, 44, 46), each of which is thereafter enclosed as a separate column. Each of the separately enclosed columns of pellet material is cooled and the cooled pellet material is removed from the cooler in one or more outlet streams. <IMAGE>

Description

SPECIFICATION Method and Apparatus for Cooling Pellet Material This invention relates to a method and apparatus for cooling pellet material.

The necessity of cooling and, to some extent, drying newly formed animal feed pellets and other pellet material is well known, see for example U.S.

Patent Specifications Nos. 2,849,806, and 3,842,516, the disclosures of which are incorporated herein by reference. A limitation of the construction of the apparatus disclosed in U.S. Patent Specification No. 2,849,806 is the relatively great overall height required for a given throughput. The construction disclosed in U.S.

Patent Specification No. 3,842,51 6 seeks to overcome this problem by providing a pellet cooler of lower overall height than that disclosed in U.S. Patent Specification No. 2,849,806 or, more generally, a pellet cooler that will permit a more favourable utilization of available space.

U.S. Patent Specification No. 3,842,516 discloses a cascade-type cooler with particular attention being given, inter alia, to the elimination of clogging of the air exhaust duct with pellet fines. Under circumstances of controlled product input, when the input pellet material is naturally resistant to producing fines, the apparatus disclosed in U.S. Patent Specification No.

3,142,516 works well, but it has been found that if the pellet material to be cooled is not highly resistant to the production of fines, problems occur with clogging which results in nonproductive downtime for cleaning. Accordingly, it is an object of this invention to avoid the fines problems encountered with certain uses of the cooler described in U.S. Patent Specification No.

3,842,516 while contemporaneously providing a cooler characterized by en nced space utilization as compared with what is possible with the cooler construction described in U.S. Patent Specification No. 2,849,806.

According to one aspect of the invention there is provided a method for cooling pellet material which method comprises introducing pellet material to be cooled into an upright cooler; splitting said pellet material in said cooler into at least four substantially equal streams of pellet material; enclosing each of said four streams of pellet material as a separate column of pellet material; individually cooling each of said separately enclosed columns of pellet material; and removing the cooled pellet material from the cooler in at least one outlet stream.

According to another aspect of the invention there is provided an apparatus, for cooling pellet material, comprising an upright cooler provided with: (a) inlet means whereby, in use, pellet material to be cooled can be introduced into said upright cooler; (b) splitting means whereby, in use, the pellet material can be split in said upright cooler into at least four substantially equal stream of pellet material; (c) means for ;;c),Slr ,g ea tL!? .?t s.- rour streams of pellet materiai as a separate column of pellet material; (d) cooling means whereby, in use, each of said separately enclosed columns of pellet material can be cooled; and (e) outlet means whereby the cooled pellet material can be removed from said upright cooler in one or more outlet streams.

In a preferred embodiment of the invention, the pellet material is introduced into the upright cooler at the top thereof and is then split into a pair of downwardly divergent primary pellet streams and then each of said streams of said pair of primary pellet streams is itself split into a pair of downwardly divergent secondary pellet streams thereby to produce four substantially equal st-earns of pellet material. Each of the four streams of pellet material is thereafter separately enclosed in a vertical column and ambient air is passed from one side to the other side of each column to cool each column.Adjacent columns of the cooled pellet material are then reformed into a pair of streams, whereafter the cooled pellet material is either removed as a pair of outlet streams or the pair of cooled streams is reformed into one outlet stream and removed as one outlet stream from the upright cooler.

For a better understanding of the invention, and to show more clearly how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Fig. 1 is a partly schematic, side elevation of a single discharge pellet cooler according to the invention; Fig. 2 is a front elevation of the pellet cooler of Fig. 1; Fig. 3 shows schematically and in side elevation the operation of the single discharge pellet cooler of Figs. 1 and 2; Fig. 4 is a schematic detail of a portion of the inlet of the pellet cooler of Figures 1 to 3: Fig. 5 shows schematially and in side elevation the lower portion of a double discharge pellet cooler according to the invention; Fig. 6 shows interior details of part of one-half of a single discharge pellet cooler, taken about its centre line; and Fig. 7 shows interior details of part of one-half of a double discharge pellet cooler, taken about its centre line.

With reference to the drawings and, in particular, Figs. 1 to 4 thereof, there is illustrated at 10 an embodiment of a pellet cooler according to the invention having a single discharge. Pellet cooler 10 essentially comprises an inlet and splitting portion 12, a cooling column assembly 14, and a discharge portion 1 6. Also included are a pair of exhaust ducts 18 (one of which is shown in Fig. 2) for connection either separately or conjointly to a fan or fans (not shown) to cause the passage of ambient air, at a desired flow rate, through the cooling column assembly 14.

Referring now in more detail to the inlet and splitting portion 12, there is shown an upwardly open, generally rectangular inlet 20 through which pellet material 22 to be cooled can be introduced into upright pellet cooler 10.

Extending from side to side across inlet 20 and located generally centrally thereof is a triangular top, or inlet, diverter 24 for splitting the feed of pellet material into a pair of substantially equal, diverging primary pellet streams (as can be seen in Fig. 3). Top diverter 24 is attached at its ends to the walls of inlet portion 12 by means of screws 26 or the like extending through transverse slots 28 (one shown) in a manner such that a degree of lateral positioning of top diverter 24 is possible in order to facilitate the splitting of the feed stream of pellet material 22 substantially eveniy.

A pair of laterally spaced, downwardly divergent plates 30 and 32 are disposed below the diverter 24 and form support surfaces for continued divergent flow of the pair of primary pellet streams As is best illustrated in Fig. 3, support plates 30 and 32 terminate at a selected location where it is desired to split each stream of the pair of primary pellet streams into a pair of downwardly divergent secondary streams thereby to produce four substantially equal streams of pellet material. For this purpose, inlet and splitting portion 12 is provided with two triangular bottom diverters 34 and 36 each extending from side to side of the inlet portion 12 and each of which is disposed in a respective downwardly divergent path of travel of one of the pair of primary pellet streams.As each of the primary pellet streams strikes its respective bottom diverter, the stream is split at the apex of the bottom diverters into a pair of downwardly divergent secondary streams.

Moreover, to facilitate control of the equalization of these newly produced streams, two expedients are employed. Firstly, with particular reference to Figs. 1 and 4, a preselected number of bridge elements 38 of a preselected width are arranged to bridge the gap between the lower termini of plates 30 and 32 and the apices of the bottom diverters 34 and 36. In this manner a selected portion of the pellet material is permitted to bridge the gap while another portion tends to fall of its own weight into the gap.

Secondly, the slope of the bridge elements 38, as best seen in Fig. 1, is less than the slope of plates 30 and 32 so that the outwardly divergent anguiar momentum of the pellet material is to some extent interrupted, thereby also causing pellet material to enter the gap as opposed to bridging the gap. In this manner substantial equalization of the four streams of pellet material can be achieved.

Considering now the cooling column assembly 14, there are four cooling columns shown at 40, 42, 44 and 46. Between columns 40 and 42 and underlying bottom diverter 34, there is an air exhaust chamber 50. Between columns 44 and 46 and underlying bottom diverter 36, there is an air exhaust chamber 52. Moreover, between columns 42 and 44 and closed at least at the top thereof, there is an ambient air inlet channel, or corridor, 54. Stainless screens 56 form the opposing walls of exhaust chambers 50 and 52 and, accordingly, form one wall of each of the cooling columns 40, 42, 44 and 46.A bank of hinged louvres 57 form the other wall of each of the cooling columns, i.e. the opposing wails of air inlet corridor 54, and the outer facing front and rear walls 55 and 58, respectively, of cooling column assembly 14 (or, the outer facing walls of cooling columns 40 and 46). In this manner there are provided four cooling columns, each having one wall consisting of a bank of hinged louvres 57 and an opposite wall consisting of a stainless screen 56. For reasons that should become clearer hereafter, there is located at or near the bottom of each air exhaust chamber 50 and 52 an elongate fines cleanout vane 60 that extends the full width of these chambers and is suitably mounted for up to 1 800 rotary movement therein by means of an external crank handle 62.Also, as shown in Fig. 1, the sides of chambers 50 and 52 are closed but each is provided with a convenient hinged inspection door 64, at the lower portion thereof, to permit fast inspection of this area. The other sides of chambers 50 and 52 are connected to the transition exhaust ducts 1 8.

The discharge portion 1 6 of the pellet cooler 10 shown in Figs.1,3 and 6 has a single discharge and that of the pellet cooler 10 shown in Figs. 5 and 7 has a double discharge. Since many of the components of both types of discharge are identical or substantially identical, simultaneous description of both types of discharge will follow, using common reference numerals where appropriate. With particular reference to Figs. 3 and 5 on the one hand and to Figs. 6 and 7 on the other hand, both types of discharge essentially comprise an eccentric drive 66 including a drive motor 68 (Fig. 2), pairs of feed control gates 70, a pair of shake feeder assemblies or oscillating shoes 72, and a discharge outlet or outlets 74.The principal distinction between the single and double discharge embodiments of the invention is the addition to the oscillating shoes 72 of the single discharge embodiment of a supplementary chute or shoe base 76 to direct the pellet material from the control gates 70 to a single outlet 74. Both are equipped with a plurality of flexible or resilient, upstanding, shoe support springs or the like 78 (generally two per side for each oscillating shoe 72), as well as a pair of shoe drive straps 80 interconnecting the eccentric drive 66 with the oscillating shoes 72. In the single discharge embodiment, when the feed gates 70 are raised, the cooled pellet material is convergingly reformed from a pair of adjacent cooling columns into a pair of pellet streams and thereafter the pair of pellet streams is reformed into one outlet stream and the cooled pellet material is removed as one outlet stream. Conversely, in the double discharge embodiment, after reforming pairs of adjacent cooling columns into a pair of cooled pellet streams, the pair of pellet streams is removed as a pair of outlet streams.

Mechanical controls for operation of pellet coolers according to this invention include an elongated control vane 82, extending across cooler column 40 and attached to rotatable sheave 84 and counterweight 86. Sheave 84 is attached to a cable that passes around pulley 88 and connects to one end of feed gate control bar 90. As shown, control bar 90 is connected through bell cranks 92 to feed gate control rods 94 which, in turn, connect to feed gate operating levers 96. Operating levers 96, which are fixedly attached through bearings 98 to gate arms 100, will rotate gates 70 between the closed position shown and an elevated or open position for flow out of the cooled pellet material, as control vane 82 moves clockwise toward a vertical position.

Additional mechanical controls may include a pneumatic piston-cylinder 102 and cable 104 or the like, to provide override operation of control vane 82 for emptying the cooler at the end of a run.

In operation, hot pellets, flowing into the inlet and splitting portion 12, from a pellet mill or the like, are split into a pair of substantially equal, downwardly divergent, primary pellet streams.

Thereafter, each of the pair of primary pellet streams is itself split into a pair of downwardly divergent secondary pellet streams thereby to produce four substantially equal streams of pellet material. Each of the stream of pellet material flow downwardly to fill its respective cooling column 40, 42, 44 and 46. A bank of hinged louvres form one wall and a stainless screen forms the other wall of cooling columns 40, 42, 44 and 46. The weight of incoming pellets as they rise in the cooling columns pivot the hinged louvres 57 outwards or downward and open passages for air to be drawn by a fan (not shown) through the column of hot pellets. The portion of the louvres against which the pellets reside is perforated to enhance the ambient airflow.In time, all of the louvres 57 are actuated and, as the pellet material builds up against control vane 82, it rotates blockwise (as shown), opening feed gates 70. Thus, depending on whether a single or double discharge unit is operating, the cooled pellets are convergingly reformed from adjacent columns into a pair of pellet streams, whereafter the cooled pellet material is either removed as a pair of outlet streams or the pair of cooled streams is reformed into one outlet stream and removed as one outlet stream from the cooler.

Thereafter, the operation of the cooler involves a continuous flow of pellet material from top to bottom of the cooler until flow of feed material is either interrupted or its operation is otherwise terminated. In other words, the input regulates the output. Periodically, the fines cleanout vane 60 can be dumped and the fines emptied into the cooler discharge, thereby to eliminate fines buildup and ultimately eliminate the potential of cross contamination between subsequent runs of different pellet materials.

Claims

1. A method for cooling pellet material which method comprises introducing pellet material to be cooled into an upright cooler; splitting said pellet material in said cooler into at least four substantially equal streams of pellet material; enclosing each of said four streams of pellet material as a separate column of pellet material: individually cooling each of said separately enclosed columns of pellet material; and removing the cooled pellet material from the cooler in at least one outlet stream.

2. A method according to Claim 1 wherein ambient air is passed transversely of each column of pellet material to cool each of said separately enclosed columns.

3. A method according to Claim 1 or 2, wherein said pellet material introduced into the cooler is split into a pair of primary pellet streams; and each stream of said pair of primary pellet streams is split into a pair of secondary streams thereby to produce said at least four substantially equal stream of pellet material.

4. A method according to Claim 1,2 or 3, wherein adjacent columns of said cooled pellet material are reformed into a pair of streams of cooled pellet material; and said pair of streams of cooled pellet material is reformed into one outlet stream which is thereafter removed from the cooler.

5. A method according to Claim 1, 2 or 3, wherein adjacent columns of said cooled pellet material are reformed into a pair of streams of cooled pellet material; and said pair of streams of colled pellet material is then removed from the cooler as a pair of outlet streams.

6. A method according to any one of Claims 1 to 5, wherein periodically fines of cooled pellet material are added to said at least one outlet stream.

7. A method of cooling pellet material which method comprises introducing pellet material to be cooled into a vertical cooler; splitting said pellet material in said cooler into a pair of downwardly divergent primary pellet streams; reducing the downward slope of a portion of each of said pair of primary pellet streams; contemporaneously splitting each stream of said pair of primary pellet streams into a pair of downwardly divergent secondary pellet streams thereby to produce four substantially equal streams of pellet material; enclosing each of said four streams of pellet material as a separate column of pellet material; passing ambient air from one side to the other side of each column of pellet material to cool each of said separately enclosed columns; reforming adjacent columns of said cooled pellet material into a pair of streams; and removing the cooled pellet material from the vertical cooler in at least one outlet stream.

8. A method according to Claim 7 wherein said pair of streams of cooled pellet material is reformed into one outlet stream which is thereafter removed from the vertical cooler in one outlet stream.

9. A method accordiing to Claim 7, wherein said pair of streams of cooled pellet material is removed from the vertical cooler as a pair of outlet streams.

10. A method of cooling pellet material substantially as hereinbefore described with reference to the accompanying drawings.

11. Apparatus, for cooling pellet material, comprising an upright cooler provided with: (a) inlet means whereby, in use, pellet material to be cooled can be introduced into said upright cooler; (b) splitting means whereby, in use, the pellet material can be split in said upright cooler into at least four substantially equal streams of pellet material; (c) means for enclosing each of said four streams of pellet material as a separate column of pellet material: (d) cooling means whereby, in use, each of said separately enclosed columns of pellet material can be cooled; and (e) outlet means whereby the cooled pellet material can be removed from said upright cooler in one or more outlet streams.

12. Apparatus as claimed in Claim 11 wherein said cooling means includes means for passing ambient air transversely of said means for enclosing each of said four streams of pellet material whereby, in use, each of said separately enclosed columns of pellet material can be cooled.

1 3. Apparatus as claimed in Claim 11 or 12 wherein said splitting means includes means for splitting said pellet material in said upright cooler into a pair of primary pellet streams and means for splitting each stream of said pair of primary streams into a pair of secondary pellet streams thereby to produce said at least four substantially equal streams of pellet material.

14. Apparatus as claimed in Claim 11, 12 or 13, wherein said outlet means includes means for reforming adjacent columns of said cooled pellet material into a pair of streams; means for reforming said pair of streams into one outlet stream; and means for removing said cooled pellet material from the upright cooler in one outlet stream.

1 5. Apparatus as claimed in Claim 11, 12 or 13 wherein said outlet means include means for reforming adjacent columns of said cooled pellet material into a pair of streams; and means for removing said pair of streams of cooled pellet material from the upright cooler as a pair of outlet streams.

1 6. Apparatus as claimed in Claim 11, 12, 13, 1 4 or 1 5 which includes means for periodically adding fines of cooled pellet material to said at least one outlet stream.

1 7. Apparatus, for cooling pellet material, comprising an upright cooler provided with: (a) inlet means at the top of said upright cooler whereby, in use, pellet material to be cooled can be introduced into said upright cooler; (b)(i) means for splitting said pellet material into a pair of downwardly divergent primary pellet streams; (b)(ii) means for reducing the downward slope of a portion of each of said pair of primal y pellet streams; (b)(iii) means for contenporaneously splitting each stream of said pair of primary pellet streams into a pair of downwardly divergent secondary pellet streans thereby to produce four substantially equal streams of pellet material; (c) means for enclosing each of said four streams of pellet material as a separate column of pellet material;; (d) means for passing ambient air from one side to the other side of each column to cool each of said separately enclosed columns; (e)(i) means for reforming adjacent columns of said cooled pellet material into a pair of streams of cooled pellet material; and (e)(ii) means for removing the cooled pellet material in one or more outlet streams.

18. Apparatus as claimed in Claim 17 wherein there is provided means for reforming said pair of streams of cooled pellet material into one outlet stream; and means for removing said one outlet stream of cooled pellet material from the upright cooler.

19. Apparatus as claimed in Claim 1 7 wherein there is provided means for removing said pair of streams of cooled pellet material from said upright cooler as a pair of outlet streams.

20. An apparatus for cooling pellet material substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.