Electrostatic precipitators (ESP) are used for gas cleaning in almost every section of cement
manufacture. Application of ESP is studied, keeping in view Indian conditions. The characterisation
of dust emissions has been done for different units, such as rotary kiln and raw mill, alkali
by-pass, clinker cooler, cement and coal mill, in terms of exit gas quantity, temperature, dew point,
dust content and particle size. It is seen that all these characteristics have a wide range of variance.
The ESP system must effectively deal with these variations. The fundamental analytical expression
governing the performance of ESP, i.e. the Deutsch equation, and that for particle migration
velocity, were analysed to predict the effect of major operating parameters, namely particle size,
temperature and applied voltage. Whereas the migration velocity (and the efficiency) varies directly
with the particle size, it is proportional to the square and square root of applied voltage and absolute
temperature of the gas, respectively. The increase in efficiency due to temperature is not seen in
dc based ESP, perhaps due to more pronounced negative effect on the applied voltage due to the
increase in dust resistivity at higher temperatures. The effect of gas and dust characteristics on the
collection efficiency of ESP, as seen in the industrial practice, is summarised. Some main process
and design improvements effectively dealing with the problem of gas and dust characteristics have
been discussed. These are gas conditioning, pulse energisation, ESP-fabric filter (FF) combination,
improved horizontal flow as well as open top ESP.