Numerical Modeling of the Temperature Distribution in a Commercial Hazardous Waste Slagging Rotary Kiln

Abstract

The gas, wall, and bed temperatures in a hazardous waste incineration kiln were studied using a commercially available, CFD-based, reacting flow code, which included radiation heat transfer. The model was compared to field measurements made on a co-current flow, 35 MW slagging rotary kiln. Cases were run to determine the sensitivity of the predictions to changes in the model assumptions and to simulate the normal variation in combustion inputs. The model predictions of the peak bed temperature, of the axial temperature profile, and of the gas temperature at the exit-plane were consistent with the measurements at a full-scale waste incinerator during normal operation. The model and the field observations both indicate that the peak bed temperature occurs near the middle of the kiln and that the difference between the peak bed temperature and the exit-plane gas temperature depends on the inlet flows. The geometry of the transition between the kiln and the secondary combustion chamber and the fuel-to-air equivalence ratio have the greatest effect on the calculated temperature distribution. Modeling studies provide useful information such as the relationship between available measurements and the temperature at inaccessible locations inside a full-scale kiln.