Method and apparatus for processing discrete commodities

BACKGROUND OF THE INVENTION

The present invention relates generally to the processing of discrete commodities and more particularly to the processing of the discrete commodities of the type consisting of compacted powdery materials and/or having adhering thereto solid particles of their base material or of other materials.

This invention is particularly applicable to the processing of such granular or powdery materials as fodder, fertilizers or the like which have undergone “cubing” or “pelleting, that is compacting into the form of cubes or pellets. However, it is by no means limited in this manner and will be described hereafter with reference to this particular application only as an example of a highly advantageous field of employment.

It is well known, as already suggested above, to “cube” or “pellet'’ such powdery materials as fodder, fertilizers and analogous materials by compacting quantities of such materials into discrete bodies which may have various different shapes and sizes, for instance small cylindrical bodies having a diameter ranging between approximately 2 and 16 mm and a length ranging between approximately 5 and 15 mm. Of course, these dimensions are again only given by way of example and are not limiting in any sense. These bodies will hereafter for the sake of convenience of identification be referred to as “commodities” or “discrete commodities.”

The conventional approach to the treatment of such materials comprises four stages, namely the initial compacting of the powdery material into discrete commodities, the cooling of these commodities in a special cooler to reduce their temperature which usually becomes elevated either as a result of the pressure to which the material has been subjected during compacting, or because of steaming to which the material is sometimes subjected during the compacting stage, “crumbing” to obtain the desired size for the individual discrete commodities by passing them through a crumber between rollers whose j distance from one another is adjustable, and sifting to remove adhering solid particles, usually in an inclined sifter to which a reciprocating motion is imparted by means of an eccentric cam. Conventionally, the compacted discrete commodities are taken from the press in which they have been compacted, to a cooler which is located higher than the press, for instance by means of a bucket elevator or the like. Once the commodities are discharged from the cooler they pass in intermittent batches through the crumber (which can be eliminated if no need for it exists) and the sifter. In some instances of the prior art the solid particles which have been separated from the discrete commodities in the sifter are recovered and conveyed back to the compacting press, for instance by a bucket elevator ora small pneumatic conveyor.

These known prior-art constructions are by no means inoperative. However, they do not permit the continuity of processing in all stages of operation, they are relatively complex and therefore require undesirably large technical and economic expenditures, they require expensive erection and maintenance services and they have very large space requirements.

SUMMARY OF THE INVENTION

The present invention avoids the disadvantages outlined above. More particularly, the present invention provides a method of processing discrete commodities in which all stages can be carried out continuously and in which cooling of the commodities and removal and recovery of the separable solid particles are accomplished in a single operation, thus saving time and labor and reducing the complexity of the installation.

Furthermore, the present invention provides for an apparatus which is considerably simpler than those known from the prior art and which thus requires smaller economic and technical investments and needs considerably less main tenance and repair. The space requirements of the apparatus according to the present invention are also much smaller than is known from the prior art.

In accordance with one feature of our invention we provide 5 a method of processing discrete commodities wherein the commodities are advanced in a predetermined direction along a confined path from an inlet towards an outlet of the path, and wherein the commodities are contacted in an upstream section of the path with a concurrent flow of gas, and in a ¹⁰ downstream section of the path with a countercurrent flow of gas. In this manner not only obtain cooling of the commodities in a most advantageous manner, but the same gas which effects cooling of the commodities also serves to remove the 15 separable solid particles from the commodities so that they may be recovered for further use.

By providing the two oppositely directed gas streams we assure that those of the commodities which have already passed downstream beyond the confluence of the two gas streams will 20 not be contacted by the separated solid particles being removed from the commodities which newly enter at the inlet of the confined path and which have of course still a maximum percentage of separable solid particles adhering to them.

The invention also concerns an apparatus for carrying out 25 this method, and this apparatus comprises in accordance with another feature of our invention a housing which includes an inlet and an outlet spaced from the inlet, and conveying means which is arranged in the housing and which is operative for conveying discrete commodities with adherent separable solid 30 particles from the inlet towards the outlet of the housing. Gasstream producing means is associated with the housing and is operative for producing a first stream of gas which flowing direction from the inlet towards the outlet concurrently with the commodities, and a second stream of gas which flows in ³⁵ direction from the outlet toward the inlet in counterflow to the commodities.

In the apparatus according to our invention we utilize a vibratory conveyor of the type which is generally known and wherein the discrete commodities advance in a helical path. In utilizing this type of conveyor we have had excellent results, a fact which is somewhat surprising in view of the technical prejudice according to which the use of such a conveyor for materials of the type in question was expected to lead to such problems as undesirable chalking and pulverization, as well as to insufficient cooling. In fact, our apparatus successfully combines solutions to requirements—-namely to prevent disintegration of the compacted discrete commodities and thorough cooling of the same—which heretofore appeared to 50 be contradictory where the utilization of a vibratory conveyor was involved.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construc55 tion and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a somewhat schematic, partially broken away sectional elevation of an apparatus embodying our invention.

FIG. 2 is a section taken on the line A-A of FIG. 1.

FIG. 3 is a view taken along line 3-3 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Discussing now the drawing in detail, we have diagrammatically illustrated a press of conventional construction in which 70 the raw material, such as fodder, fertilizer or the like, is introduced in powdery or granular state and is compacted into individual bodies, the “discrete commodities” to which reference is being had throughout this specification. This press is of any conventional well known construction and need not 75 be further described.

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From the press the discrete commodities, which are identified with reference numeral 1, are supplied, in a manner which is of no consequence for the purposes of the present invention, to the inlet 2 of an apparatus 3 which embodies our present invention. The drawing illustrates that the apparatus 3 comprises a vibratory conveyor which, in the illustrated embodiment, is a substantially vertical vibratory elevator having a plurality of helical convolutions 4. This type of vibratory conveyor is well known, both as to its construction and its principle, and a detailed discussion of either of these is therefore not necessary. The conveyor 4 is externally surrounded or encompassed by a housing or shell 5, and preferably the housing 5 is connected to the conveyor 4 in such a manner as to be gastight therewith except for the inlet 2 and the outlet.

In accordance with the present invention we provide, in the illustrated embodiment, a ventilator or fan 7 whose air intake 6 communicates with the interior of the housing 5 intermediate the inlet 2 and the outlet thereof. In the illustrated embodiment this communication takes place at a location substantially midway between the inlet and outlet although such location is not fixed and could, for instance, be provided at a point located in a range midway between the inlet and outlet and two-thirds from the inlet towards the outlet.

The important point is that the communication takes place intermediate the inlet and the outlet because by this expedient we obtain two currents of air, namely a concurrent flow of air moving in direction from the inlet 2 towards the outlet along with the discrete commodities which move in the same direction, namely vertically in the illustrated embodiment, and a countercurrent flow of air which moves from the outlet in the direction towards the inlet 2 in countercurrent to the movement of the discrete commodities. These airstreams of course contact the commodities moving along the helical convolutions of the conveyor 4, and effect efficient cooling of these commodities. At the same time, however, the airstreams effect removal of dust and solid particles adhering to or admixed with the discrete commodities and this dust and solid particles are withdrawn through the intake 6 of the fan or ventilator 7. It is clear, of course, that the space between the successive convolutions of the conveyor 4 and the width of the path defined thereby must be such as to obtain, as a function of the volume of moving air, an airspeed which is sufficient to carry along the solid particles. Such calculations are simple and will be readily obvious to those skilled in the art.

Solid particles withdrawn from the interior of the housing 5 through the air intake 6 of the fan or ventilator 7 are advantageously conveyed to a decanter room, hopper or cyclone 8 which is not illustrated in detail because it is entirely conventional, and from there are fed to the feed conveyor 9 whose feed screw 16 conveys them to the press for conversion into compacted discrete commodities.

Reference numerals 10 indicate vibrators of known construction which, unlike conventional arrangements, however, in the illustrated embodiment are connected to the housing 5 rather than to the vibratory conveyor 4 itself. Customarily, such vibrators are connected to the central support column 11 but in the illustrated embodiment we obtain, by connecting them via special connecting arrangements to the housing 5, a construction in which the inlet 2 for the compacted commodities can be arranged at a very low level of the structure 3, almost at the very bottom thereof, and this of course makes it possible to greatly reduce the height of the overall structure, particularly in view of the fact that it permits the elimination of that lower portion of the central column 11 to which the vibrators are normally connected and which is not usable for purposes of material conveyance.

If desired the arrangement may be used in conjunction with a crumber 13 which is located exteriorly of the structure 3, as illustrated in FIG. 1. If such a crumber 13 is in fact used, and it is again emphasized that it may be omitted, then the discrete commodities 1 are fed thereto in the manner obvious from FIG. 1. Upon passing through the crumber 13 it is then necessary to sieve the commodities treated in the crumber 13 so as to free them from the dust produced during the crumbing treatment during which, as is well known, the commodities are partly crushed. For this purpose we provide, if the arrangement is used in conjunction with the crumber, a supplemental path 12 in form of a guideway corresponding substantially to the guideway which fashions the convolutions of the vibratory conveyor 4. This supplemental path or guideway 12 is arranged upwardly of the intake 6 in the illustrated embodiment and consists of a trough or sieve which may for example be fashioned from perforated sheet metal. The supplemental path 12 is located intermediate two adjacent convolutions of the vibratory conveyor 4 and, because it need be only short, its length may for instance correspond to one-half or two-thirds of one of the helical convolutions. The commodities treated in the crumber 13 fall onto or are conveyed to the path 12 and pass therealong, as a result of vibratory conveyance, to the bagging outlet 14. During passage over the path 12 the dust is removed in the same manner as solid particles have been previously removed during passage of the discrete commodities 1 along the vibratory conveyor 4.

It is clear, of course, that if no resort is had to the crumber 13, then the path 12 will also not be present and the cooled and cleaned discrete commodities will instead be discharged via the discharge channel or conduit 15 to the bagging outlet 14.

With the apparatus according to the present invention the relatively delicate compacted commodities may be thoroughly and rapidly cooled and freed from adhering solid particles, or from solid particles admixed therewith, without damage to the commodities and at a speed and continuity of operation not heretofore known. It is also clear, particularly from a consideration of the drawing, that the apparatus according to the present invention is compact and can be readily disassembled into its constituent components, all of which are prefabricated selfcontained units. This makes it possible to assemble and disassemble the apparatus according to the present invention rapidly and without the need for trained personnel with specialized skills. The absence of rotary members of the type necessary in conventional apparatus of this type for conveying and sifting purposes greatly reduces the need for maintenance and repair.

It will be understood that the illustrated embodiment has been shown by way of example only and is not to be considered limited. Modifications will readily occur to those skilled in the art and do not require deviation from the basic inventive concept. Thus, movement of air by suction, as illustrated in the embodiment hereindiscussed, can be replaced by producing airstreams under pressure, and for this purpose a fan or blower can be provided at each of the opposite ends of the vibratory conveyor, or a single fan or compressor can be utilized with each of its two sides (namely the intake side and the output side) being connected to one end of the housing 5. Of course, if suction is replaced by pressure, the air intake 6 will be replaced by a simple conduit into which the two airstreams can enter and which is connected with the member 8. Also, another gas can be utilized instead of air, it being understood that such gas must be chemically inert with reference to the commodities which are being treated. Auxiliary cooling may be provided, for instance by circulating a liquid through a jacket provided on the housing 5, or through cooling channels provided in the vibratory conveyor 4, or both. Finally it must again be emphasized that while the present invention has been described herein with reference to the treatment of fodder and fertilizers, it is by no means so limited and is applicable wherever discrete articles, which are admixed or which have adhering thereto solid particles, must be separated from such solid particles and/or be cooled.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.

While the invention has been illustrated and described as embodied in the treatment of discrete commodities, it is not

3,545,609 intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that otl ers can by applying cunent knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.