Prediction of the performance of a rotary kiln incinerator in treating rice hulls

摘要

Paddy rice is the most important agricultural product in Taiwan. A large amount of rice hulls is produced after paddy rice is harvested. Rotary kiln incinerators are widely used for heat treatment of many kinds of industrial wastes. Because rice hulls are very hard to burn in an incinerator equipped with stationary beds, this study examined the burning of rice hulls in a rotary kiln industrial incinerator. The inclined rotary kiln, which rotates at a suitable speed, provides a stirring junction that introduces oxygen into the burning rice hulls. The speed of rotation and the dimensions of the cylinder affect the residence time of the treated rice hulls. A turbulent gas flow exists inside the combustion chamber of a rotary kiln incinerator leading to optimal mixing of combustible gases. Therefore, rice hulls can be completely incinerated. This study simulated the full-scale flow field of a co-current rotary kiln incinerator using the computational fluid dynamics (CFD) code FLUENT The standard k-ε turbulence model was used. The velocities, the temperature, and the pyrolysis of rice hulls inside the rotary kiln incinerator are discussed and analyzed. The results of the simulation are compared with experimental data and could be helpful in suggesting a new solution for the heat treatment of rice hulls or other agricultural residue.