Influence of Ammonium Dihydrogen Phosphate on Combustion Performance and Ash Characteristics during Combustion of Zhundong Coal. Issue 11 (2nd November 2019) - Gao, Manda
ABSTRACT: In this study, the co-combustion of Zhundong coal and NH4 H2 PO4 was investigated in a laboratory-scale tube furnace. The ash fusibility, combustion performance, and ash characteristics were quantified by experimental approaches. This study also used Gibbs free energy theory to analyze the chemical reactions. The results showed that NH4 H2 PO4 can extend the burning time of coal and reduce combustion intensity. Moreover, NH4 H2 PO4 significantly changed the composition of ash, which was caused by reactions between alkali/alkaline earth metals and NH4 H2 PO4, increasing the sodium retention ratio of the formed ash. In addition, the newly formed phosphate crystals (i.e., Mg2 P2 O7, AlPO4, and Ca3 (PO4 )2 ) with higher melting temperatures contributed to the increase in fusion temperature of the formed ash, and the sodium-containing crystals (i.e., Na2 CaP2 O7 and NaMg4 (PO4 )3 ) contributed to the increase in the sodium retention ratio. Furthermore, NH4 H2 PO4 had a significant effect on the microcosmic structure, with ash showing more rough and sintering being inhibited.