LIBS measurements and numerical studies of potassium release during biomass gasification

Abstract

This paper reports on a joint numerical and experimental investigation of the release of potassium from biomass during gasification process. In this work, laser-induced breakdown spectroscopy (LIBS) was adopted to measure quantitatively the concentration of potassium from gasifying biomass. The effect of temperature on the potassium release is investigated in hot gas mixture of CO2, H2O with different concentration of O2. A biomass thermochemical conversion model is employed to study the physical and chemical processes inside the particle. A sub-model is developed to simulate the various stages of potassium release during biomass conversion and to improve the chemical kinetic mechanism and chemical kinetic constants of the release rate. Two stages of the potassium release associated to devolatilization and char reaction and ash-cooking stages are proposed. The rate of release of potassium during char reaction and ash-cooking stages follows a first order Arrhenius expression as 2.5×105±0.2exp(-266×103/RT). The kinetics rate constants along with the reaction path appear to be able to predict the potassium release with an acceptable accuracy.