Predicting bed agglomeration tendencies for biomass fuels fired in FBC boilers:: A comparison of three different prediction methods

In this paper a comparison between three different types of techniques to predict the bed agglomeration tendency of a FBC (fluidized-bed combustor) was performed. The three techniques were the standard ASTM ash fusion test, a compression strength based sintering test and a lab-scale combustion test. The tests were performed on 10 different types of biomasses. The results showed significant differences in the predicted bed agglomeration temperatures depending on which technique was used. The ASTM standard ash fusion test generally showed 50-500 degrees C higher temperatures than the sintering tests or the lab-scale FBC combustion tests. The sintering test showed, in five cases, 20-40 degrees C lower sintering temperatures than what was detected as the bed agglomeration temperature with the lab-scale FBC. In two cases, a significantly lower sintering temperature than the bed agglomeration temperature was detected, and in three eases, a significantly higher sintering temperature was detected than the bed agglomeration temperature. The detailed results and their relevance is discussed in the paper.