Report 2004.TL.6841, Transport Engineering and Logistics.
The objective of proper screw conveyor design and selection is to obtain
high volumetric efficiency while keeping power requirements to a minimum.
To satisfy this purpose, several factors need to be considered: the actual
properties of the material to be conveyed, the conveyor geometry, rotation
speed, inclination angle, the pitch length, the intake opening, and even
the operation conditions.
In this report, some general theoretical analysis is presented to make the
performance of screw conveyors much clearer. The structure is as follows:
All models depicted in this report permit the determination of the
optimal volumetric efficiency or power requirements with taking account of
the parameter interaction among screw geometry, the screw speed, the angle
of inclination, the intake length, the screw pitch, the clearance and also
the properties of the material to be conveyed.
- Chapter one gives an overall view about screw conveyors, from the
basic structure of the screw conveyor to those who had done remarkable
researches in screw conveyor field.
- In chapter two, some screw conveyor calculations based on actual material
properties are introduced. The actual material properties can be obtained
by the standard bulk solid material shear test. Comparing the calculation
results with that of DIN standard 15262 'Screw conveyors foor loose bulk
materials', it is evident that the DIN standard at its existing revision
is not sufficient and not applicable.
- Chapter three introduces the dimensional analysis to develop general
prediction equations for the volumetric capacity and the power requirement.
Some published data are used. Parameter interaction determines to obtain
the optimal volumetric capacity and the power requirement.
- Chapter four mainly focuses on the effects of the granular vortex motion
on the volumetric performance and chapter five focuses on the effects of
the radial clearance geometry on the power consumption.
- In chapter six, because of the extensive uses of screw feeders, screw
feeder as the special kind of screw conveyor is concerned, and also some
models are made to predict the volumetric efficiency and the torque needed.
The screw torque can be consider as the indication of the required power.
- At last, there is the conclusion on the previous chapters of the report.
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