A dynamic model of an industrial pneumatic dryer is constructed for the purpose of modelling the variations in product quality as a consequence of the variations in die feed. Rigorous mechanistic modelling is augmented with empirical assumptions to result in a nonlinear system of ordinary differential equations. A new short-cut method for rite computation of the evaporation rate is introduced. Simulation results are compared with actual measurements and show! that our model follows quite well the behaviour of the real plant in spite of the relative simplicity of the model.