Reverse-flow catalytic burners: response to periodical variations in the feed

A deep investigation has been carried out about the behaviour of a reverse- flow combustor for the treatment of low-VOC concentration waste gases, in t he presence of periodical variations in the feed characteristics. Two kinds of variations have been taken into consideration: in the inlet concentrati on and in the flow rate. In both cases, the variations cause relevant fluct uations in the maximum temperature of the bed and in conversion. These fluc tuations, especially for long feeding cycle periods, can endanger the corre ct operation of the reactor. In addition, for particular ratios between the feeding cycle period and the flow-reversal cycle period, the interaction b etween the two cycles may cause serious problems of instability, represente d by large low-frequency fluctuations of the maximum temperature in the cas e of variations in the inlet concentration, and by a dangerous flow asymmet ry in the case of variations in the flow rate. The criteria to avoid these problems are presented. (C) 2001 Elsevier Science Ltd. All rights reserved.