Development and Application of Optical Diagnostics of Alkali Vapours for Solid Fuel Combustion

Abstract: Background: High amounts of alkali in the fuel, such as potassium and sodium in combination with high amounts of chlorine increase the chances of high-temperature corrosion, deposit growth and slagging and fouling. These risks need to be reduced to avoid losses in revenue due to unplanned stops and costs related to increased maintenance. Aims:This research targets the development of a new cell to produce calibration spectra of good quality that render accurately-determined alkali chloride concentrations. Similarly, it aims to develop new measurement techniques that can be used to determine the concentration and formation of alkali. Methods:UV absorption measurement on sublimated vapour from potassium chloride under well-defined conditions, which subsequently can be converted into an accurate calibration spectrum. Differential Absorption Light Detection and Ranging technique adapted to measurements in the combustion environment using one optical access port. Laser-induced Photofragmentation Fluorescence imaging for formation studies of alkali compounds. Results:This work has resulted in a calibration cell able to provide alkali vapour of well-controlled conditions and Laser-induced Photofragmentation Fluorescence imaging set-up for the formation studies of alkali compounds. It has been shown in the laboratory environment that the Differential Absorption Light Detection and Ranging technique can be used for alkali chloride measurements. Discussion:Prospectively the work aims at contributing to the development of more efficient combustors with low levels of emission and reduced operational problems and also increase the academic knowledge of alkali compound formation during biomass combustion.