Abstract
Rotary kilns are advanced thermal processing systems which are used to process solid material at
elevated temperatures. Rotary kilns operate by holding the processed material at a specific
temperature for a specific amount of time. There are two main types of rotary kilns i.e. directly fired
and indirectly fired rotary kilns. In directly fired rotary kilns, the process material is in direct contact
with the combustion flame and flue gases. On the other hand, for the indirect fired kiln, the process
material is in an inert environment, which prevents direct contact with the combustion flame and flue
gases.
Due to the elevated operating temperatures, complex loading scenarios arise. These may lead to
mechanical deformations such as axial distortion, transverse distortion, blistering, necking, banana
distortion, misalignment and kinks. These behaviours complicate structural performance assessments
of rotary kilns. Furthermore, due to the equipment’s size and harsh working environment, it makes it
difficult to conduct structural performance tests to obtain experimental data. Therefore, numerical
modelling tools may be applied to optimise the design of the rotary kilns.
The main purpose of this work was to develop a numerical model for the structural performance of a
direct-fired rotary kiln pilot plant, developed by Drytech International Pty. Ltd, and to validate the
model by using experimental data. The main study focused on the stress and stain state of the kiln for
three load cases namely (1) when the empty kiln is rotating (2) when the kiln is rotating and loaded
without heat and (3) when the kiln is rotating and loaded with heat.
Through real time strain measurements, transient response validation data was obtained. The
experimentally gathered strain measurements were transformed, and the principal stress and strain
state was calculated for each point in time. A validated transient finite element numerical model was
then develop using Abaqus CAE.
Percentage fill and temperature was varied using the numerical model to determine the influence that
these parameters had on the direct-fired rotary kiln pilot plant. The investigation confirmed that the
structural behaviour of the direct-fired rotary kiln pilot plant is influenced by fill percentage and
temperature i.e. the strain and stress variation is dependent on the response of the kilns structure to
different load applications.
To further develop the study on direct-fired rotary kilns, full scale experimental data should be
gathered from full-scale industrial kilns and validated by the use of a numerical modelling tool such as
Abaqus CAE.
M.Ing. (Mechanical Engineering)