| Summary: | A test facility was constructed to conduct experimental investigation of erosion
caused by gas-borne ash particles. The test facility was used to carry out the main
objective of the study which was the determination of the critical angle of attack that
gives maximum erosion on the target material, mild steel, and the effect of particle
velocity and concentration on the erosion of the target material. The tests were carried
out using ash samples from three different Eskom fossil-fuelled power stations,
namely Matimba Power Station, Matla Power Station and Lethabo Power Station. The
selection of the ash samples was based on the ash chemical composition that has the
highest content of the chemical elements that have a significant influence in the
material erosion of the target material. These chemical elements are quartz and other
abrasive materials. These ash samples had a high content of these erosive materials.
The first test that was carried out in this study was the determination of the critical
angle of attack that gives maximum erosion on the target material. It was decided to
start by doing this test because the velocity and concentration tests needed a
predefined critical angle of attack that gives maximum erosion on the target material.
During the velocity and concentration tests the angle of attack was kept at the
predefined critical angle of attack.
The results in this study indicate that the critical angle of attack that gives maximum
erosion on the target material is at 27º ± 3º orientation of the target surface. The
velocity test results indicate that the material erosion rate increases with increasing
velocity. The results produced a power relationship between erosion rate and velocity.
In this power relationship the velocity exponent for the three ash samples was found
to be in the range between 2.42 and 3.64. The concentration test results also indicate
that the material erosion rate increases with increasing particle concentration. These
results produced a linear relationship between erosion rate and particle concentration.
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