This study aims to improve the understanding of the formation and prevention of deposits caused by the introduction of alternative fuels in the cement industry. Experiments were conducted with cement mineral materials in a laboratory-scale entrained flow reactor. To simulate the temperature conditions in a cement calciner, two different deposit probe systems were used: a high probe surface temperature (HPST) deposit system with a probe surface temperature range of 700-1200 °C and a low probe surface temperature (LPST) deposit system with a probe surface temperature range of 500-700 °C. The effects of fed materials (raw meal, hot meal, bypass dust), flue gas temperature (700-1200 °C), deposit probe surface temperature (550-1200 °C), gas velocity (0.9-2.7 m/s), and experimental duration (5-60 min) on the deposit formation rate were investigated. The results revealed that the concentration of KCl in the fed materials has a large influence on deposit formation. In HPST experiments with furnace temperatures ranging from 700 to 1100 °C, the bypass dust has a higher deposition rate than hot and raw meals, due to a large amount of K and Cl (>10 wt %) in the bypass dust, which forms melts and increases the stickiness between impacting particles and deposits. In LPST experiments, the presence of KCl facilitated the deposit formation rate by providing a sticky layer on the deposit probe via condensation, resulting in a higher deposition rate of bypass dust than the raw meal. An increase in gas velocity showed a negative effect on the deposit formation rate due to an increase in rebound. The present study suggests that keeping the calciner wall temperature at 900-1100 °C and a low level of KCl content would effectively reduce the deposit formation, thereby increasing the equipment life and reducing the operating cost during cement production.
© 2022 The Authors. Published by American Chemical Society.