The Role of Kaolin in Prevention of Bed Agglomeration during Fluidized Bed Combustion of Biomass Fuels

Abstract

Agglomeration of bed material and fuel ash may cause problems during fluidized bed combustion of biomass fuels. Previous results have shown that a “sticky” coating, which covered the original bed material and consisted of Ca-K-silicates, was directly responsible for the bed agglomeration during biomass combustion. The melting behavior (stickiness) of these coatings was very sensitive to the potassium content. Prior studies have also indicated that bed agglomeration could possibly be prevented by introducing low-cost additives such as kaolinite. The objectives of the present work were, therefore, to illustrate the effect of kaolin addition on the actual agglomeration temperature of two troublesome biomass fuels, and to contribute to the understanding of the role of kaolin in prevention of bed agglomeration. By controlled agglomeration experiments in a 5 kW bench scale fluidized bed reactor, the critical temperatures for agglomeration in a normal quartz bed when firing wheat straw or bark were determined to...