PATCHY CLEANING OF RIGID GAS FILTERS .2. EXPERIMENTS AND MODEL VALIDATION

Rigid ceramic filters have emerged as the most promising technology fo r cleaning of hot gases due to their resistance to attack by aggressiv e gases and high temperatures. Their potential may be further extended by using them in combination with injection of a dry sorbent to remov e acid gases and other chemical contaminants. A crucial factor in thei r successful utilisation is the ability of the cleaning pulse to remov e the deposited cake effectively from the filter surface. In this stud y, laboratory experiments have been carried out using a single ceramic candle filter. The non-steady-state behaviour of the filter in the in itial period of filtration was followed. 'Patchy' cleaning of the filt er was observed and is consequently identified as the major cause of t he inefficiency of filter cleaning indicated by the measured residual pressure drops. A simple correlation has been proposed to determine th e cleaned fraction from pressure differences as a measure of the effic iency of cleaning. The conditioning curves have been successfully simu lated using a recently developed probabilistic model and it has been s hown that the model can also be applied to simulate the experimental r esults obtained in a pilot plant operating at high temperatures. The m odelling results are consistent with the experimental observation that patchy cleaning with a thin residual dust layer in the cleaned areas can explain the conditioning behaviour. Copyright (C) 1996 Elsevier Sc ience Ltd