Kinetics of Selenium and Cadmium Vaporization During Coal Combustion in a Fluidized Bed

Abstract

In order to understand the transformation behaviors of selenium and cadmium during coal combustion, the kinetic studies were conducted by using an online analysis system of trace elements in flue gas. The analysis system is based on a modified inductively coupled plasma optical emission spectroscopy (ICP-OES) and can measure the concentrations of trace elements in flue gas quantitatively and continuously. The standard aerosol for calibration is produced by applying an ultrasonic nebulizer. The results of online analysis showed that selenium and cadmium concentrations in flue gas increase with a rise in temperature. Selenium is more easily released than cadmium during coal combustion. Based on the results of selenium and cadmium concentrations in flue gas, the release rates of selenium and cadmium during coal combustion were determined, respectively, at the particle level. The higher the temperature is, the higher the release rates of selenium and cadmium are, although the release rates are not proportional to the temperature. This indicates a strong influence of temperature on selenium and cadmium release kinetics.