A NEW MODEL FOR THERMAL VOLATILIZATION OF SOLID PARTICLES UNDERGOING FAST PYROLYSIS

A new model is proposed for representing the thermal volatilization of solid particles under the conditions of fast pyrolysis. The solid, initially at low temperature, is suddenly immersed into a high-temperature medium where it decomposes to gaseous products, the external surface of the particle being exposed to a high heat flux from the medium. As heat penetrates into the solid by conduction, the decomposition reaction occurs at rate which increases with temperature. Equations for simultaneous heat and mass balances are derived and numerically solved, yielding the internal temperature profile and the rate of shrinkage of the particle, from which the time for total consumption is easily deduced.