Abstract
M.Ing.
The performance and reliability of induced draft fans are of ever growing
concarn in industry, especially in the power generation industry. The
reliability and plant efficiency depend on the design conditions of all plant
components. Induced draft fans handle high temperature flyash-laden flue
gas, and are often plagued by mass-flow deficiencies and excessive vibration
in fossil fuel powerplants [1].
In this research an existing induced-draft fan is analysed to investigate the
occurrence of high stresses forming on the impeller, as these stresses lead to
cracks appearing on the centre plate of the impeller. The basic approach
used to address this problem is implementing the Finite Element Method
starting with different cantilever beam configurations to simulate the
connection of the blade with the centre plate. Geometries are kept constant
to facilitate in the practical set-up implementation stage of the dissertation.
The practical set-up is used to verify the results obtained from the Finite
Element Method program, and it serves as a benchmark test for evaluating
the further use of the chosen Finite Element Method program.
A simplified Finite Element Method model is presented for the induced draft
fan. Static and frequency analyses are done to determine the characteristics
of the fan structure. Lastly an advanced dynamic analysis is done on the
specific fan. Different ramp force functions are used to simulate different
start-up curves for the fan. A conclusion will be drawn from the dissertation,
and recommendations will be made for similar future research work.