Numerical Simulation of the Pyrolysis of Solid Waste in an Externally Heated Rotary Kiln

A computational model was developed to predict the pyrolysis process of municipal solid waste in externally heated rotary kiln. The model was calculated assuming solid waste and gas are one-dimensional flow. The heat transfer coefficient among solid waste, gas and inner cylinder of kiln, which is variously affected by kiln structure and operation condition, was acquired by a scale model examination. A flexible computational grid was adopted in the model, which could change its shape according to the height of solid waste layer in each time step. The accuracy of this model was verified by comparison with the pilot scale experiments and the actual plant data. The predicted transient temperature profile is in good agreement with experimental data. Compared to the actual plant data, temperature prediction error is less than 10% at inner cylinder wall, pyrolysis gas, and solid waste.