Modeling of heat transfer in granular flow in rotating vessels

Heat transfer in particulate materials affects a wide variety of applications ranging from multi-phase reactors to kilns and calciners. In catalyst manufacturing, heat transfer through granular media (catalyst) occurs in the impregnation and calcinations stages. We use the discrete element model to simulate flow, mixing, and heat transport in granular flow systems in rotary calciners and impregnators. Granular flow and heat transport properties are taken into account in order to develop a fundamental understanding of their effect on dryer and calcination performance. Simulations have shown that as rotation speed decreases, both heat transfer and temperature uniformity of the granular bed for both calciner and impregnator increase. Depending on baffle size, baffles can either increase or decrease heat transfer in double cone impregnators. Granular cohesion does not affect heat transfer in the range of values examined. 2006 Elsevier Ltd. All rights reserved.

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Experimentally validated computations of heat transfer in granular materials in rotary calciners

Publisher Summary Bed–to–surface heat transfer can be calculated with good reliability, if particle-residence times and their population near the surface are known The mechanism of heat transfer between boiler tubes and the fluidized bed is very complicated because of the many fluidized-bed variables and the variations in heat-transfer tube design Correlations are empirically developed on the basis of the observed data with limited attention to the mechanisms of the heat-transfer process This chapter reviews the design application of local as well as total heat-transfer coefficients for horizontal and slanted tubes, and for vertical tubes Single tubes and tube banks in different orientations to the bed are also considered The fundamental mechanisms of wall–to–bed heat transfer are reviewed and the criteria for evaluation of correlations for full-scale application are examined Particle movement is a complex function of the particle and gas properties, fluidization velocity, gas distributor, and geometry of the bed This approach generally gives the designer a good degree of assurance, requires a judicious choice of a representative system as well as the expense of pilot scale development The consideration must be given to the unsteady-state conduction component, the radiation component, and the gas convective component in boiler design

Heat Transfer Between a Gas Fluidized Bed and Immersed Tubes

A model of heat transfer in gas fluidized beds

On the optimum transfer coefficient at an exchange surface in a gas-fluidized bed

Function space methods for analysis of nonadiabatic tubular reactors with axial mixing-I. Uniqueness criteria of the steady state and computation of the steady state profiles

Satish Agrawal

Papers

On the optimum transfer coefficient at an exchange surface in a gas-fluidized bed

Function space methods for analysis of nonadiabatic tubular reactors with axial mixing-I. Uniqueness criteria of the steady state and computation of the steady state profiles