Effect of semi-continuous water washing on the combustion behaviors of agricultural organic solid waste

Combustion of agricultural organic solid waste (AOSW) was an ideal solution for their resource utilization in view of their massive annual production and great potential for reduction of fossil fuel utilization. However, high alkali and alkaline earth metals (AAEMs) content in the feedstock can arose severe fouling and slagging issues and thus prohibiting its vast utilization. In this study, a semi-continuous water washing method was proposed to preliminarily remove AAEMs from agricultural organic solid waste and its effects on the combustion behaviors of washed solid product were investigated. Results showed that the combustion index S were improved to 2.63 × 10^-6, over 68 % of the total ashes were removed from the cotton stalk, and 96.3 %, 89.0 % and 74.7 % of K, Na and Mg were effectively removed, respectively. Moreover, the softening temperature of low temperature ash from the washed sample was as high as 1450 °C, 538 °C higher than the low temperature ash from the original sample; the base acid ratio and fouling index were improved from high slagging and fouling risk (1.7 and 90.8) of the original organic solid waste to low and medium risk (0.4 and 3.5), respectively. All these results signified the contributing effect of proposed semi-continuous water washing method on the combustion of agricultural organic solid waste. In a word, this study provided a promising method for fouling and slagging inhibition during the agricultural organic solid waste combustion.