Analysis of fouling in refuse waste incinerators

Gas-side fouling of waste-heat-recovery boilers, caused mainly by the depos ition of particulate matter; reduces the heat transfer in the boiler. The f ouling as observed on the tribe bundles in the boiler of a Dutch refuse was te incinerator varied from thin and powdery for the economizer to thick and sintered for the superheater. Analysis of process data showed that both ty pes of layers resulted in a 27% decrease of the heat transfer coefficient o f the bundles. To determine the important mechanisms in the deposition of particles, layer s taken from the different bundles are analyzed using electron microscopy. The analysis revealed the existence of a melt ill the thick deposit. The me lt, giving rise to a liquid phase, increases the sticking efficiency of the deposit and leads to larger deposition rates. For the economizer and the s uperheater the actual deposition rate is calculated from the change in heat transfer On the basis of a comparison between the calculated deposition ra tes and deposition rates to be expected in, the case of a pure diffusion an d thermophoresis process, it is shown that for both types of deposits inert ia-controlled transport is the dominant transport mechanism of particles.