Moving bed heat transfer and fluidized elutriation

Graduation date: 1985Two problems relating to the processing of solid streams are\ud treated in two sections.\ud The first section is the study of heat transfer between an\ud immersed cylinder and a moving bed of solids: An instrumented heated\ud cylinder was placed in the flow stream of a moving bed of solids with and\ud without countercurrent air flow and the heat transfer coefficients were\ud measured between the bed and the cylinder. Runs were made with five\ud different types of solids, with wide range of thermal properties ( thermal conductvities of 0.04 to 380 W/m.K, and heat capacities of 380 to\ud 2300 J/kg.K ) and sizes ( 0.27 to 2 mm ) at various gas and solids\ud velocities. The obtained heat transfer coefficients ranged from 20 to\ud 600 W/m².K . A model for heat transfer between an immersed cylinder and\ud a flowing packed bed of solids, and a predictive equation, derived from\ud theory and experimental observations, were proposed. Also, the resulting\ud heat transfer coefficients were empirically correlated. The findings\ud were then discussed and compared to past related published work.\ud The second section is the study of elutriation from fluidized\ud beds: Elutriation characteristics of widely different solids ( density\ud from 920 to 5900 kg/m³ )were measured in three different fluidized beds, 0.1, 0.3 and 0.9 m in size, having high freeboard ( 7.5 m ), using gas\ud velocities of up to 3.5 m/s. The experimental findings were compared\ud with previously reported results and all the variables were well\ud correlated with a simple empirical expression based on the terminal\ud velocity of the particles and the velocity of the gas