Diseño Y Aplicación De Chutes Para Alimentadores

Design and Application of Feeders for the Controlled Loading of Bulk Solids onto Con... Página 1 de 39

DESIGN AND APPLICATION OF FEEDERS FOR THE CONTROLLED LOADING OF BULK SOLIDS ONTO CONVEYOR BELTS
A.W. Roberts Department of Mechanical Engineering The University of Newcastle N.S.W., Australia.

SUMMARY The efficient operation of conveyor belts for bulk solids handling depends to asignificant extent on the performance of the gravity feed system. The attainment of controlled feeding with a minimum of spillage and belt wear is of major importance. In addressing this problem, this paper focuses attention on the design requirements of the mainly used feed system comprising a gravity flow hopper, feeder and chute. The specific function of these three components is briefly outlined andthe need for the hopper and feeder to be designed as an integral unit is stressed. Various types of feeders are reviewed and methods for determining feeder loads and power requirements are presented. The interaction between the flow pattern developed and wall pressures generated in mass- flow hoppers and the manner in which these influence feeder loads is discussed. A simplified methodology ispresented for the design of belt feeders and feed hoppers with extended skirtplates for feeding directly onto conveyor belts. The design procedures are illustrated by example 4. Mention is made of the basic design requirements of feed chutes with particular reference to the need for careful consideration of the bulk solid flow properties and the friction characteristics of chute lining materials. 1.INTRODUCTION Of the various modes at transporting bulk solids, belt conveying is clearly one of the most effective and reliable and well suited to handling bulk solids over a wide range of tonnage rates. The success of belt conveyors depends on a number of factors, not the least of which is the initial feeding of the bulk solid onto the belt and to the efficient transfer of solids from one belt toanother at conveyor transfer stations. With the future trend towards higher belt speeds and narrower belts in order to achieve higher economic efficiency [1-8], much attention will need to be given to the design of belt feeding systems which will guarantee high feeding rates with minimum of spillage and belt wear. While the basic objectives of an ideal feeding arrangement for loading conveyorbelts are fairly obvious [9-11], it is important that they be noted. Such objectives may be summarised as follows: Free and uniform flow of material without segregation at a pre-determined flow rate in the same direction as the belt travel and preferably at the same speed. Uniform deposition of material about the centre of the belt, Avoidance of material spillage and dust problems. Minimisation ofabrasive wear and impact damage. The feeding of bulk solids onto belt conveyors is normally controlled by a gravity flow hopper/feeder combination and, in the majority of cases, the solids are finally directed onto the belt through a gravity flow chute. The feed hopper may be a part of a surge bin as in Figure 1(a) or a part of a stockpile reclaim system as in Figure 1(b). Alternatively it may be aseparate dump hopper for unloading trucks or rail wagons as in Figures 1(c) and 1(d) respectively. Feed rates are controlled by the hopper and feeder as an integral unit while the feed chute in the flow directing and feed velocity controlling device. It is important that the interactive roles of these three components as an integrated system be understood; hence some elaboration is warranted:

i.Gravity Flow Hopper - The hopper geometry and internal wall friction characteristics in conjunction with the flow properties of the bulk solid establishes the type of discharge flow pattern and maximum potential rate

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29-11-2006

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