Enhanced fly ash recovery by the promotion of agglomeration

Gas cleaning devices used for fly-ash recovery at coal-fired power stations depend on particle size for their efficiency. The finer the particles the less efficient the units; the larger the particles, the lower the operating costs of the power station. Any means by which agglomeration can be achieved should be considered in order to improve the efficiency of power station operation. This paper reports a laboratory study on the effect of chemical additives on the agglomeration of fly-ash particle in a moving gas stream. In-situ measurements of particles size distributions showed that, of the chemicals tested, water promoted agglomeration most significantly, with the median diameter more than doubling from 16 um to 40 um. The injection of small quantities of water into power station exhausts potentially provides significant saving in the cost of air pollution control.