Inerting effect of CaCO3 powder on the combustion characteristics of wood dust layer

Abstract

The influence of the typical inert powder, calcium carbonate (CaCO3), on the combustion temperature and spread pattern of wood dust layer was investigated using an experimental apparatus designed to study the ignition characteristics of deposited dust. The findings demonstrated a gradual decline in the combustion temperature of wood dust layer as the mass fraction of CaCO3 increased. A notable decrease in combustion temperature was observed when the CaCO3 mass fraction ranged from 40% to 60%. In the absence of initial wind speed, the high-temperature burning area of the dust layer was significantly reduced as the CaCO3 mass fraction increased. Concurrently, the red sparks at the front end of the burning front diminished, and the color of the combustion residue transitioned from charcoal black to charcoal gray. With the presence of initial wind speed, prominent red sparks were observed at the front end of dust layer combustion when the CaCO3 mass fraction was low, while the red sparks decreased and darkened as the CaCO3 mass fraction increased. CaCO3 primarily influenced wood dust combustion through heat absorption and oxygen adsorption. The coupling effect of increased initial temperature and wind speed under CaCO3 inerting contributed to the overall rise in wood dust combustion temperature. According to the wood dust layer combustion temperature-CaCO3 mass fraction Exp1 model, employing CaCO3 with a mass fraction exceeding 40% resulted in a more effective inerting performance.