Influence of sintering on the growth rate of particulate fouling layers

This article addresses the question; why the gas-side temperature affects the rate of particulate fouling of heat exchangers? An experiment was carried out in a gas-cooler of a full-scale biomass gasifier to investigate the influence of the gas-side temperature on the strength, structure and growth rate of particulate fouling layers. It is observed that the particulate fouling rate in the gas cooler decreases with sintering, which is a function of the gas-side temperature. Detailed impaction experiments are carried out to investigate the influence of sintering on the removal of particles from a particulate fouling layer due to an incident particle impact as well as the sticking of an incident particle to a particulate fouling layer. Sintering of a fouling layer lowers significantly the ability of an incident particle to stick to the fouling layer or to remove particles out of the layer. However, particles that are still able to deposit on the sintered fouling layer will not sinter immediately, and can be removed due to the incident particles impact. The removal of newly deposited particles on a fouling layer due to incident particles becomes easier as sintering of the fouling layer takes place. Accordingly, it may be stated that sintering reduces the fouling rate of heat exchangers by lowering the deposition of new particles and increasing the removal rate of newly deposited particles. This explains why the growth rate of particulate fouling layers decreases with the gas-side temperature. (c) 2006 Elsevier Ltd. All rights reserved.