Investigation of ash deposit formation on heat transfer surface of boilers using coals and biomass

Abstract

Combustion of coals and biomass in boiler furnaces leads to formation of fireside deposits on irradiated and convective surfaces. This problem is not a new one, but it became one of the main operational problems in boilers using low rank coal and some sort of biomass. In the paper presented are the results of research of ash deposit processes in laboratory conditions. An experimental furnace was used for these purposes. The experiments were performed on a tubular experimental furnace which ensures appropriate temperature and mass transfer conditions for physical and chemical transformations of the mineral matter of fuel as in real conditions. The main working parameters can be varied in wide ranges. The influence of grinding fineness, excess air and wall surface temperature was analysed. Also, an ash related problems during coal and biomass combustion was considered. Key empirical correlations for slagging and fouling were tested. Two types of Serbian coals (Kolubara and Kosovo) and several biomasses were analysed. It was shown that many sorts of biomass and Kosovo coal have a great propensity to slagging and fouling.