GB2047212A - Spiral chute - Google Patents

Abstract

A chute for feeding a raw coal bunker has a cladding of plates 1, for example of ceramic material or steel, secured on a concrete substrate by means of hydraulic cement or synthetic resin mortar. The plates 1 are longer in the flow direction than transversely thereto; the longitudinal joints 2 extend parallel and the transverse joints 3 extend at an acute angle to the flow direction. Spiral elements 4, which terminate the chute surface cladding at the interior of the spiral chute and have a convex and smooth surface 6, are provided with a coarse serration 5 on the underside. <IMAGE>

Description

SPECIFICATION Spiral chute The invention relates to a spiral chute, particularly (but not solely) for feeding a raw coal bunker, the chute surface being cladded with plates, for example of ceramic material or steel, cemented to a substrate, e.g. by means of hydraulic cement mortar or synthetic resin mortar.

Spiral chutes of this kind have been used for a long time for feeding raw coal bunkers constructed of concrete, and such chutes can be arranged within or in front of the bunker wall or within the actual bunker chamber. Ceramic material, such as fused basalt, and various kinds of steel are used for the chute surface cladding of such spiral chutes. The cladding plates are mounted on concrete, accompanied by the formation of joints, which are filled with hydraulic cement mortar or synthetic resin mortar. Both the longitudinal and the transverse joints of the chute surface cladding form an angle with the flow direction of the goods.

The use of the above-mentioned plates, with which joints are formed transversely to the flow direction, suffers from the disadvantage that bulk goods are transported very irregularly on such a base and a jumping motion is imparted to such material. The serious consequences of such irregular running of the stream of bulk goods comprise a measurable reduction of the particle size, particularly of coal, and relatively rapid wear of the chute surface cladding.

Another disadvantage of the known chute surface cladding is due to the possibility of damage to the spiral edge caused by large dropping parts of the bulk goods and by foreign bodies, perhaps to such an extent that the entire chute surface cladding is deprived of a support and on the other hand no sliding motions can take place in this edge region.

By contrast it would be desirable to substantially avoid particle reduction resulting from conveying and to reduce wear of the chute surface cladding in the interests of cost saving and to provide a spiral chute which cannot easily be damaged in its edge region and furthermore ensures a durable support in the edge region for the entire chute surface cladding.

According to the invention, plates which are longer in the flow direction than transversely thereto are laid in the flow direction and shaped so that the longitudinal joints extend parallel and the transverse joints extend at an acute angle to the flow direction, and the undersides of spiral terminal elements, which terminate the chute surface cladding towards the interior of the spiral and have a convex and smooth surface, are provided with a coarse serration.

Preferably the spiral terminal elements are produced of impact-resistant material, for example cast steel, and the remainder of the chute surface cladding is produced from ceramic material. Further more, it has been found advantageous for the cladding plates to be laid in hydraulic cement mortar and for the spiral terminal elements to be secured by means of adhesive.

The technical advance of the spiral chute according to the invention is due mainly to the fact that subsequent processing by vertical conveying is simplified by avoiding further particle reduction of the bulk goods and that furthermore the high cost of repair and down times of the chute are avoided by reducing wear.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure lisa partial and schematic view of one embodiment of a spiral chute; Figure 2 shows another embodiment of a spiral chute disposed in front of a bunker wall, in crosssection; and Figure 3 is a partial view of the surface cladding of the inlet of a spiral chute.

Referring first to Figure 1, cladding plates 1, which are longer in the flow direction (arrow) than trans verselythereto, are laid in hydraulic cement mortar so that the longitudinal joints 2 extend parallel with the flow direction and the transverse joints 3 form an angle which is as acute as possible with the flow direction. The plates 1 constitute part of the surface cladding of a spiral chute formed in the concrete wall 7 of a raw coal bunker.

Spiral terminal segments 4, of the edge of the chute orientated towards the interior of the bunker, have a smooth convex surface 6 which is extended in the downward direction. By contrast to the cladding plates 1, which are of ceramic material, the segments 4 are of impact-resistant material (cast steel) because this region is regarded to be particularly in danger of impact due to being struck by foreign bodies.

To improve adhesion, the underside of each spiral terminal element 4 is provided with a coarse serration 5. Further, the spiral terminal elements 4 are secured by means of an adhesive on the chute substrate (concrete). As a result the spiral terminal segments 4 form a support for the remainder of the chute surface cladding, laid in cement mortar, thus resisting the detachment of the ceramic plates 1 from the bond.

As can be seen by reference to the partial plan view of Figure 3, in the chute inlet construction cladding plates 1 are again used which are constructed longer in the flow direction than transversely thereto and by virtue of a chamfered transverse edge avoid unsteady and irregular running of the bulk goods.

It is feasible within the scope of the invention, more particularly in the case of repair or rearrangement of worn spiral chutes, to adopt intermediate solutions according to which the chute surface lining is provided in conventional manner with the exception of the edge region. In such cases the edge region of a spiral chute of this kind can be readily covered by spiral terminal segments 4 which are secured by adhesive.

The chute surface cladding can be provided not only on a chute laid on a concrete base as shown in the embodiment according to Figure 1 but also can be applied to other structural forms of spiral chutes which are disposed within a bunker chamber, either enclosed or open form. An embodiment of this kind is illustrated in Figure 2. The support structure of the spiral chute, comprising precast ferroconcrete components, is fixed to the wall 7 of the bunker. The cladding of the chute is as described above with reference to Figure 1.

Since there are hardly any sliding motions of the bulk goods in the region of the edge and for this reason there is hardly any wear which smoothens the surfaces, it is advisable for the spiral terminal segments 4 to be ground or coated before being installed. This particularly facilitates automatic clearance of the spiral chute as the bunker is emptied.

Claims (6)

1. A spiral chute having a surface cladding cemented to a substrate, the cladding comprising (a) plates which are longer in the flow direction than transversely thereto, the plates being arranged to provide longitudinal joints extending parallel to the flow direction and transverse joints extending at an acute angle to the flow direction, and (b) spiral terminal elements defining the edge of the cladding at the interior of the spiral chute, the surface of each terminal element being convex and smooth, the underside of each terminal surface adjacent the substrate being serrated.

2. A spiral chute as claimed in claim 1, in which the terminal elements are of impact-resistant material and the plates are of ceramic material.

3. A spiral chute as claimed in claim 2, in which the terminal elements are of cast steel.

4. A spiral chute as claimed in any of claims 1 to 3, in which the plates are laid in hydraulic cement mortar, and the terminal elements are secured to the substrate by means of an adhesive.

5. A spiral chute substantially as described herein with reference to, and as shown in, the accompanying drawings.

6. A raw coal bunker having a spiral chute as claimed in any preceding claim.