Study on Water Wash Pretreatment and Al-Si Additives to Relieve the Sintering Behavior of Fungus Bran Combustion Ash

Abstract

This study focuses on the sintering phenomenon that easily occurs during the direct combustion of molded fuel made from fungus bran (FB). To investigate the key factors influencing sintering, experiments are designed and conducted using a muffle furnace and a high-temperature drop furnace. The experimental results show that the combustion temperature is the primary factor triggering the sintering phenomenon. To effectively mitigate this issue, this study proposes two improvement strategies: water washing pretreatment and the use of additives. The analysis shows that water washing pretreatment effectively removes K and Mg elements, with the removal rates increasing as the washing temperature and time increase. Specifically, the removal rate of K ranges from 37.68% to 55.91%, and that of Mg ranges from 33.16% to 58.52%. Water washing pretreatment also reduces the degree of sintering; at 1400 °C, the TSF (tendency to slag formation) of the fuel increases by 25–40% after pretreatment, with a greater increases observed at higher washing temperatures and longer durations. Kaolin, used as an additive, significantly raises the ash melting point of FB and alleviates sintering, while P2O5 exacerbates it. Increasing the proportion of kaolin does not significantly enhance the TSF of high-temperature ash, but raising the P2O5 content from 5% to 10% lowers the TSF by 10–20% at the corresponding temperature.