Mechanism research on coking of the heating surface of biomass furnaces

Biomass combustion has been tested in a drop-tube furnace, and the ash deposits on a heating surface have been sampled. The physical and chemical characteristics of the deposits were analyzed using TEM. The laboratory results have been compared with the ash deposit samples obtained from a biomass-fired power plant furnace. The results from both the laboratory and the plant samples indicate that most of the alkali chloride has been homogeneously converted into alkali sulfate in flue gas before depositing on the heating surface, and sulfate aerosols play a dominant role in the formation of biomass ash deposits. Potassium, sodium, sulfate and oxygen are the key species contributing to the formation of coking in biomass furnace and the content of chloride is little. Temperature affects the element consist of the coking particle indistinctively in the experimental range. Finally, major pathways of alkali sulphation and the role of sulfate aerosols formed in the biomass-ash deposition are proposed.