The fouling of surfaces during the manufacture of liquid products is a
serious problem for the foods industry. However, it also affects many
other production processes such as paint manufacture and the producti
on of detergents, the latter being of primary interest for this work.
The use of cleaning chemicals to remove soil layers is considered high
ly undesirable. Not only does the disposal of the effluent produced ca
use environmental problems but also the costs involved make chemical c
leaning economically unfavourable. By studying the damaging effects of
purely physical erosion processes on thin deposited layers using wate
r as the sole cleaning agent it is hoped that an understanding of the
mechanisms governing erosive cleaning can be developed. If the efficie
ncy of cleaning is maximised to such an extent that chemicals can be r
emoved from the cleaning process then it should be possible to recycle
cleaning water for use as process water. Potential erosion processes
include liquid flow, impact by liquid jets and cavitation induced by u
ltrasound. Two rigs have been developed to study cleaning by liquid fl
ow and jets while a commercial ultrasonic vibrator has been used to st
udy the effects of cavitation. The aim throughout has been to compare
the efficiencies, with respect to volume of cleaning water, of the dif
ferent processes and to understand how individual parameters affect th
e efficiency of each process. The experimental techniques used in this
study include high speed photography, flow visualization, and computa
tional image analysis.