Influence of temperature on the release of inorganic species during high temperature gasification of Rhenish lignite

Na-, K-, Cl, and S-species are of concern due to their relation to problems of corrosion and fouling in IGCC power systems. The aim of this work was to get more information on the influence of temperature on the release of Na-, K-, S-, and Cl-species. Therefore, lab-scale gasification experiments with four different lignites at 1100 degrees C, 1400 degrees C, and 1700 degrees C were carried out. The hot gas was analysed by molecular beam mass spectrometry. The results show a strong influence of temperature on the release. Two release phases, devolatilisation and char reactions phase, were observed. The phase of main release was devolatilisation. The main species released were (H2S+)-H-34, (HCl+)-H-36, K-39(+)/(NaO+)-Na-39, (NaCl+)-Na-58, (COS+)-C-60, and (SO2+)-S-64, (KOH+)-K-56 and (KCl+)-K-74 were released with signal intensity slightly above the signal background. The quantified data show several effects of the temperature on the release. The release trends of (HCl+)-H-36 and (NaCl+)-Na-58 are contrary. Evidences are given that the major release mechanism is the dissociation of carboxylic bond Na species. The mechanism is able to explain the temperature dependence as well. (C) 2010 Elsevier B.V. All rights reserved.