Investigation of the effect of alkali metal sorbents on the release and capture of trace elements during combustion of straw

This work deals advanced information on the effect of alkali metal sorbents on the release and capture of trace elements, with special focus on potassium and sodium, during combustion of straw. Investigated sorbents were fly ash, bentonite, kaoline and bauxite. The lab-scale release and sorption experiments were done with pure straw and straw/sorbent mixtures at 1200 degrees C. The hot gas was analysed by Molecular Beam Mass Spectrometry. Species of interest were (HCl+)-H-36 (m/z = 36), K-39(+) (m/z = 39), (SO2+)-S-64(m/z = 64), and (KCl+)-K-74 (m/z = 74). The release of (HCl+)-H-36 and K-39(+) as well as (KCl+)-K-74 showed a strong correlation which proofed a recently proposed capture mechanism. All sorbents lowered the released amount of alkali metal species significantly. Bentonite and fly ash showed the best capture performance for potassium. (C) 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved.