Transformation and Release of Potassium, Chlorine, and Sulfur from Wheat Straw under Conditions Relevant to Dual Fluidized Bed Gasification

Abstract

The release and transformation of potassium (K), chlorine (Cl), and sulfur (S) from biomass during thermochemical conversion processes may lead to problems, such as the corrosion and fouling of heat transfer surfaces, agglomeration of bed material, and the poisoning of catalysts used in the downstream processes of gasifiers. To predict and to mitigate effectively these problems, information regarding the quantity and mechanism of the release of these elements under relevant operating conditions is required. In the present work, the release of K, Cl, and S from wheat straw under conditions relevant to dual fluidized bed gasification were quantified in a laboratory-scale bubbling fluidized bed reactor. During the pyrolysis step, the bed temperature ranged from 550 to 900 °C, while the residence time for the fuel in the reactor was fixed at 3 min. The char samples obtained from the pyrolysis step were partially combusted at the same temperature at which they were produced for an additional 3 min. The fractio...