Abstract: Fouling of flue gas expander has been a tricky problem currently for the operation of the device. In this paper, the force acting on catalyst fine particles was analysed, and the sintering mechanism of catalyst fines was discussed. The influence of fines concentration, particle size and catalyst element composition on the fouling of flue gas expander was analysed. Meanwhile, the fouling process of catalyst particles in flue gas expander was further discussed. The conclusion is as follows: the key condition of fouling is the existence of high concentration of catalyst fine particles. Fine particle size, element enrichment and high temperature environment have made the molten compounds on the surface of fine particles, the high fines concentration and low flow rate in the local area of flue gas expander as well as the appropriate temperature range created conditions for the fusion compounds to be adhered, sintered and fouled in the flue gas expander.

Key words: flue gas expander, fouling mechanism, fouling process, sintering