Rotary Kiln Simulator

Purpose

The pilot-scale rotary kiln simulator is designed to simulate the thermal treatment of soils, the processing of minerals, and the recovery of energy from waste materials. The kiln permits the continuous monitoring of bed temperature and gas-phase composition. Samples of solid material can be removed from the kiln bed at desired intervals and analyzed for extent of reaction or degree of contaminant removal. Therefore the kinetics of mineral processing and soil decontamination can be determined for a variety of heating rates and residence times, and useful correlations are easily obtained with nonlinear least squares fitting routines. In addition, a variety of rotary kiln models are also available to predict full-scale performance. Some of the recent applications of the rotary kiln simulator are characterizing the potential for formation of chlorinated dioxins and furans during combustion of propellant binder residue, thermal treatment of hydrocarbon-contaminated soils, calcination of hydrated lime, combustion profiles of solid wastes for application to mid-kiln firing in cement kilns.

More Pictures

Physical Description

The residence time of the solids in the kiln corresponds to the distance from the feed end in a continuously fed facility. Solids are fed to the kiln with a removable loading chute. A thermocouple extends into the bulk region of the bed and provides continuous measurements of the temperature. The inside temperature of the wall is measured with thermocouples embedded in the refractory lining of the kiln. The exhaust gases leaving the kiln are continuously monitored for NO_x, SO₂, O₂, CO, and CO₂. The exhaust stream can also be continuously analyzed for hydrocarbons using a total hydrocarbon analyzer and a gas chromatograph/mass spectrometer. The later permits the major vapor-phase species to be identified. The figure below presents a flow diagram of the rotary kiln simulator. The small, pilot-scale rotary kiln simulator is fired with natural gas at the rate of 130 kW, and the exhaust gases exit to a 100-kW secondary combustion chamber or afterburner. The inside dimensions of the kiln are 2-by-2 ft and standard operating temperatures range from 300 to 1200°C (600 to 2200°F).