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The evolution of the pipe-conveyor
International Bulk handling Technology BV www.ibtbulk.nl
For over a 100 years belt conveyors are used for the transportation of bulk goods. Limited investment and low operational costs per ton conveyed caused major developments in the design and utilization of this concept with respect to the capacities conveyed and the uninterrupted length without transfers per conveyor.
Despite all the advantages a disadvantage of the conventional troughed belt conveyor is the occurrence of dust because of product becoming airborne, and spillage of product at the return side of the conveyor due to inadequate cleaning of the belt at the head section. The increased demands for the reduction of spillage and dust have been a stimulus for the development of several kinds of enclosed/folded belt conveyor systems.
It is a fact that in many instances commonly used systems are utilized when the use of another conveyor system would give advantages with respect to economics, technique and environmental Reasons. However it remains difficult to introduce new systems and displace the more conventional systems. The pipe-conveyor concept has already existed for more than twenty years and over a thousand systems have been installed worldwide, operating at a reliability that in many occasions is superior to conventional systems. Still most of the users of belt conveyor systems are not really familiar with this concept.
Explosion venting of bucket elevators
P. Holbrow, G.A. Lunn, Tyldesley
This paper is a report of an experimental programme on the explosion protection of bucket elevators by venting. The project was a collaborative effort with funding by the Health and Safety Executive and manufacturers and users of bucket elevators through the British Materials Handling Board. Two bucket elevators were used in the project—a single leg elevator and a twin-leg elevator.Four dusts were used with Kst values up to 211 bar m s and dust clouds were produced by dust injection and by normal operation. Reduced explosion pressures were measured and guidance has been derived from the results. This guidance is in terms of vent spacing as a function of the Kst value of the dust. Crown Copyright 2002 Published by Elsevier Science Ltd. All rights reserved
MOTOR SELECTION For BELT-CONVEYOR DRIVES
Garry E. Paulson, P. Eng.
Rated power is the motor parameter always specified when motors are selected for a belt conveyor—motor slip is usually ignored. This paper shows how the running and starting characteristics of a belt conveyor are influenced by slip. It shows that high-slip motors improve load sharing between directly coupled motors, and it shows that high-slip motors reduce the effect of belt stretch to improve load sharing between belt-coupled drums. The interaction between stretch and slip is illustrated graphically to show the percentage of connected power available to a conveyor without overloading the motor(s) driving the secondary drum. If the power requirement for the conveyor has been determined correctly and if the power available is inadequate, the stretch-to-slip ratio is too high—probably the result of an inadvertent selection of high-efficiency motors with low slip and poor starting characteristics. With these motors, mechanical devices that introduce slip are required if the conveyor is to operate near design capacity. A preferable solution is to avoid the problem by using directly coupled high-slip motors to improve load sharing and increase starting torque.Examples are given of two motors that eliminate the need to introduce slip mechanically.