DISCHARGE DEVICE

Abstract: A discharge device is presented with a product reservoir (1) and close to the bottom thereof a number of rotable juxtaposed cylinders (5-10). Each cylinder (5-10) is at its circumference provided with a slot-shaped opening (12) giving access to the inside of the cylinder. When the cylinders (5-10) are at a stand-still they form an effective barrier for the product in the product reservoir (1). Upon rotation of the cylinders (5-10) however a regular discharge of the product is obtained.

Description: The invention relates to a discharge device for use in a countercurrent cooler or the like according to the preamble of claim 1. Discharge devices of this type are meant for a controlled discharge of a product from a product reservoir, thereby enabling a good cooling air passage through the product. Such discharge devices are constructed in such a way that always only the lowermost part of the product mass present in the product reservoir will be discharged. In a known discharge device of this type (as described in DE-C-331.126) the discharge elements comprise solid cylinders with longitudinally extending surface grooves. These cylinders are separated only by guiding walls. It is an object of the invention to further improve this discharge device. As a result the discharge device according to the invention is characterized as appears from the characterizing portion of claim 1. The cylinders that substantially mutually adjoin define an effective supporting plane for the product present in the product reservoir. However, because according to the invention the cylinders are hollow and comprise said perforations over their entire circumference the cooling air at all times can pass these cylinders without problems. Further the flow resistance of the cooling air or the like flowing through the discharge device is minimized. Always again when a slot-shaped opening is positioned at the top of a cylinder where the product is supported by the cylinder this product flows into this slot-shaped opening. During the successive rotation of the cylinders the slot-shaped openings filled in this way shall be emptied at a certain moment, namely when the slot-shaped openings are positioned at the lower side of the cylinders. The discharge velocity of the discharge device is substantially independent from the type of product. The problem of pulverising the product (such as between stationary and moving parts), thereby producing the so-called "fines", does not; the product can without restrictions flow into and out of the slot-shaped openings of the cylinders. Furthermore, the slot-shaped openings cover the entire product supporting plane of the discharge device when the cylinders rotate such that a complete discharge occurs, this means that no product remains in the product reservoir. When the cylinders are at a stand still the product can not pass these cylinders irrespective the position of these cylinders; however, the cooling air can. From FR-A-1.546.792 it is known to provide a cylinder of a discharge device with openings ("perforations"). These however are only positioned at one side of the cylinder, thus not allowing air to pass through the cylinder, but only into and out of it at the same side. According to a preferred embodiment of the discharge device according to the invention all cylinders can rotate in the some direction of rotation. As a result it is prevented that the product will be pulverised in the pinch between two adjoining cylinders. Further it is advantageous if a wall section extends inwardly from the rearmost edge of each slot-shaped opening as seen in the direction of rotation, whereas another wall section meets the inner end of the first-named wall section, which other wall section extends spirally in the direction of rotation and together with the circumferential wall of the respective cylinder defines a narrowing channel that communicates with the inside of the cylinder. A result of the described special design of the cylinders is that product quantities that during the rotation of the cylinder possibly have reached the enterior of the cylinders via the perforations will flow via the channel along the circumferential wall of the cylinder and will eventually leave the cylinder via the slot-shaped opening. Moreover it is preferred if the slot-shaped openings of the different cylinders take in mutually different angular positions regularly divided in circumferential direction. This results in a regular discharge of the product. Due to this the capacity of further machining devices for the product positioned behind (or below) the discharge device can be minimized. Hereinafter the invention will be elucidated by means of the only figure in which an embodiment of the discharge device according to the invention is schematicly illustrated. The discharge device illustrated in the figure is positioned close to the bottom of a product reservoir 1 which is part of a counter current cooler or the like. Below the discharge device air suction openings 2 are provided through which, by means of a not shown air suction device, air is sucked through the discharge device and the product reservoir 1. Below the discharge device and the product reservoir 1 an outlet section 3 known per se having an outlet opening 4 for the product is provided. The discharge device itself comprises a number of juxtaposed and substantially mutually adjoining cylinders 5-10. The center lines 11 which constitute the axes of rotation of the cylinders 5-10 all extend horizontally and mutually in parallel. In the shown embodiment the central lines 11 of the cylinders 5-10 moreover are all positioned in one horizontal plane. At their circumference all the cylinders 5-10 are provided with a slot-shaped opening 12 extending mainly in the longitudinal direction of the cylinders. The direction of rotation of the cylinders 5-10 is indicated by a curved arrow. As appears clearly this direction of rotation is the same for all cylinders. The cylinders 5-10 are shaped hollow whereby a wall section 14 extends inwardly from the rearmost edge 13 (see for example cylinder 5) of the slot-shaped openings 12 as seen in the direction of rotation, whereas another wall section 15 meets the inner end of the first named wall section 14 which other wall section 15 extends spirally in the direction of rotation and together with the circumferential wall of the respective cylinder 5-10 defines a narrowing channel 16 that communicates with the inside of the corresponding cylinder 5-10. Generally the slot-shaped openings 12 will extend in the longitudinal direction of the cylinders 5-10 in parallel with the center lines 11. It is possible however that the slot-shaped openings 12 are somewhat spirally shaped. As appears clearly from the figure the slot-shaped openings 12 of the different cylinders 5-10 take in mutually different angular positions regularly devided in circumferential direction. In the shown embodiment of the discharge device six cylinders 5-10 are provided wherein in circumferential direction the slot-shaped openings 12 are off-set 60° or a multiple thereof relative to the other slot-shaped openings 12. To prevent that a high friction occurs between the outer wall of the rotating cylinders 5-10 and the product present thereabove, which could lead to an undesired influence on this product, the cylinders 5-10 are rotated slowly when the discharge device functions. For example the rate of rotation can be 1-2 r.p.m.. The cylinders 5-10 are manufactured from perforated material, such that the air sucked in via the air suction openings 2 can easily pass the cylinders irrespective whether these are at a stand-still or rotating. In the shown position part of the product present in the product reservoir 1 can flow in the cylinders 5, 8 and 10 via the openings 12. In fact cylinder 10 is in the position in which this flowing in of the product has just started. During the proceeding rotation of cylinder 10, for example towards the position represented now by cylinder 8, the product can flow into the cylinder via the opening 12. Generally only part of the channel 16 between the wall portion 15 and the circumferential wall of the cylinders will be filled by the product. In the position of cylinder 7 the product can no longer enter the cylinder. Moreover in this position the discharge of the product is not possible either. Only after that the opening 12 has passed guide elements 17 and for example has reached the position of cylinder 9 the product can leave the cylinder via the slot-shaped opening 12. The outflow of the product from the cylinder is possible until shortly after reaching the position of cylinder 6. With its upper side cylinder 5 adjoins closely a horizontal wall section of the product reservoir 1; this prevents that some of the product would be pulverised in the pinch between the circumferential wall of cylinder 5 and the vertical side wall of the product reservoir 1. By means of the illustrated discharge device an almost continuous discharge of the product present in the product reservoir 1 can be obtained. The discharge velocity hereby depends on the velocity of rotation of the cylinders 5-10. As a result of the opposite directions of rotation no pulverisation of the product (production of "fines") occurs. The continuous discharge moreover prevents the occurence of product bridges above the discharge device. This effect is further enhanced by the scooping action of the slot-shaped openings 12 of the cylinders 5-10. The illustrated discharge device principally is fit for products with different pellet dimensions. However, it is possible to adapt the dimensions of the perforations of the material from which the cylinders are manufactured in correspondence with the product. Filling the product reservoir 1 is possible in any position of the cylinders 5-10, for if the cylinders are at a stand still the product cannot pass these cylinders. However, by means of these cylinders a complete product discharge is possible whereby product remainders present in the cylinders are discharged therefrom after only one extra revolution of the cylinders. As elucidated before the discharge device according to the invention has the important advantage that it creates an effective barrier for the product when the cylinders do not rotate. This advantage can be used cleverly by positioning two discharge devices of the type according to the invention above each other in a counter current cooler. In such a case it is possible to quickly change the product whereby the new product already can be applied above the upper discharge device when the old product is still present between both discharge devices. The only demand is that the upper discharge device is at a stand still. Generally the cylinders 5-10 of the discharge device are mounted in heavy bearings resulting in a shock-free reliable action which is also fit for very hard pellets. The invention is limited to the embodiment described before, which can be varied within the scope of the claims.

Claims: Discharge device for use in a counter current cooler or the like having a product reservoir (1), with a number of periodically moving discharge elements (5-10) positioned close to the bottom of the product reservoir (1), whereby the discharge elements comprise a number of juxtaposed and substantially mutually adjoining cylinders (5-10), the centerlines (11) of which extend horizontally and mutually in parallel, wherein each cylinder (5-10) at its circumference is provided with a slot-shaped opening (12) extending mainly in the longitudinal direction of the cylinder (5-10) and wherein the cylinders can be rotated around their respective centerlines (11) for discharging the product, characterized in that the cylinders (5-10) are hollow and comprise perforations over their entire circumference such as to allow cooling air to pass from below through said cylinders towards the product reservoir (1) irrespective of the rotational position of said cylinders. Discharge device according to claim 1, characterized in that all cylinders (5-10) can rotate in the same direction of rotation. Discharge device according to claim 1 or 2, characterized in that the slot-shaped opening (12) is somewhat spirally shaped. Discharge device according to one of the claims 1-3, characterized in that a wall section (14) extends inwardly from the rearmost edge (13) of each slot-shaped opening (12) as seen in the direction of rotation, whereas another wall section (15) meets the inner end of the first-named wall section (14), which other wall section (15) extends spirally in the direction of rotation and together with the circumferential wall of the respective cylinder (5-10) defines a narrowing channel (16) that communicates with the inside of the cylinder (5-10). Discharge device according to one of the claims 1-4, characterized in that the centerlines (11) of all cylinders (5-10) are positioned in one horizontal plane. Discharge device according to one of the claims 1-5, characterized in that the slot-shaped openings (12) of the different cylinders (5-10) take in mutually different angular positions regularly divided in circumferential direction. Discharge device according to one of the claims 1-6, characterized in that at discharging the product the cylinders (5-10) rotate at a rate of 1-2 r.p.m..

Inventors: VINK, JOHANNES ALBARTUS
Applicants: VINK, JOHANNES ALBARTUS
Application year: 1989
Main classification: B65G65
IPC codes: B65G65