THE EFFECT OF PARTICLE COMPOSITION AND TEMPERATURE ON THE DEPOSITION OF 2 WESTERN UNITED-STATES COALS IN A LAMINAR DROP-TUBE FURNACE

A mathematical model of a laminar drop-tube furnace was used to examin e the effect of variations in the size, composition and physical prope rties of ash particles on deposition. Experimentally determined size a nd composition distributions for the fly-ash of two Western US coals ( Dietz and Utah Blind Canyon) were used as input to the model. Particle trajectories in the furnace were simulated through the boundary layer to the cooled deposition surface. Particles of less than 25 mum coole d significantly before impacting the plate. Radiation had little effec t on the particle temperature at impaction. Particle-capture efficienc y was determined from the particle composition and temperature at impa ction, based on the particle viscosity. Sticking coefficients were cal culated from the particle impaction-capture efficiencies and compared with experimental values. Deposit size and shape were approximated fro m the deposition-rate data, and the temperature profile through the de posit was calculated.