(319f) Entrainment Calculations Via Bubble Dynamic Modeling for Applications at Elevated Pressure and Temperature

Calculations of entrainment rate from an operating gas-solid fluidized bed have been problematic even under ambient operating conditions.  Entrainment correlations available in the literature were mostly developed through multiple-regression of selected dimensionless groups employing limited database in term of particle properties (size, density, and distribution), bed diameter, bed height, distributor plate characteristics, and operating conditions.  Thus the entrainment rates calculated from those models can differ by several orders of magnitude.  Their extrapolation to elevated pressure and temperature is doubtful.  A new mechanistic entrainment model has been developed by considering the bubble dynamics of a gas-solid fluidized bed.  The development of bubbles is followed from their formation at the distributor plates of different designs, their growth through bubble coalescence, and their eruption at the bed surface.  The solids carried in the bubble wake are assumed to be ejected into the freeboard forming the primary particles to be entrained.  The actual entrainment rate is, however, based on the freeboard design (height and expanded section).  The entrainment rate calculated from the model was compared to a proprietary data point estimated from an operating commercial unit operating at elevated pressure and moderate temperature.