生物质燃烧设备受热面结焦的机理研究

Mechanism Research on Coking of the Heating Surface of Biomass Furnaces

在沉降炉内模拟了生物质的燃烧及灰焦在受热面上的形成过程，利用TEM对模拟受热面上生物质的结焦颗粒的理化特性进行分析，并将沉降炉试验结果与某通用生物质直燃设备结焦的特性进行对比。结果表明最初在受热面上沉积的是10-100nm的含硫盐气溶胶颗粒，K、Na、S和O是生物质结焦根部的主要元素组成而cl元素含量很低，试验范围内壁温对结焦颗粒的元素组成影响不显著。该结果意味着氯化物碱金属盐在气相中已被硫化生成含硫的碱金属盐。

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 eoking in biomass furnace and the content of chloride is little. Temperature affects the element consist of the coking particle indistinetively in the experimental range. Finally, major pathways of alkali sulphation and the role of sulfate aerosols formed in the biomass-ash deposition are proposed.