Investigation of air and rice husk cold flow structures in the suspension furnace chamber through a simulation study

Rice husk combustion in the suspension furnace is not an easy matter. Until now, there are still many obstacles faced in its process as characterized by low combustion conversion. The main cause is the poor air-particle contact as well as the probability of particle elutriation out of the furnace chamber before combustion completely occurs. Thus, in-depth and detailed understanding of air and rice husk cold flow structures in the furnace chamber, as proposed in this study, becomes necessary. The simulation study was conducted using Reynold stress model (RSM) for fluid flow quantification whereas discrete phase model was utilized for particle flow quantification. The simulation results reveal that cylindrical chamber gives a more significant particle residence time rather than rectangular chamber for every similar excess air amount. Besides, providing burner with a tangential air inlet of 90o results in high turbulence, intense swirl phenomenon, and long particle residence time. Moreover, the furnace chamber equipped with a smaller burner diameter and longer burner length together will augment the air-particle contact in the furnace chamber. Despite providing the best condition for the furnace, the design must not forget to consider the economical aspect.