SIMULATION OF STEADY-STATE HEAT AND MASS-TRANSFER IN A ROTARY KILN INCINERATOR

Simulation is presented for steady-state heat and mass transfer in the combustion chamber of a rotary kiln. The gas-phase region in the chamber is divided into 3x8x4 computational volumes in r-, theta-, and z-coordinates, respectively. Conservations of mass and energy are formulated in each volume, in which convection and radiation transfers coupled with energy balance and volatilization of waste bed are considered with plug flow model. The volatilization rate of wastes is considered by using the volatilization model for a mixture of cellulose and toluene. The governing equations for all computation cells together with the boundary and auxiliary conditions constitute a nonlinear system of equations and are solved numerically. Effects of percentage excess air, rotation speed and inclination angle of the kiln at a fixed waste loading level are examined and discussed. Comparisons between two waste volatilization models are also made.