Journal article
Release of K, Cl, and S during Pyrolysis and Combustion of High-Chlorine Biomass
The release of critical ash-forming elements during the pyrolysis and combustion of corn stover has been investigated through controlled lab-scale experiments supported by multicomponent and multiphase thermodynamic equilibrium calculations. Fuel samples were treated under isothermal conditions ranging from 500 to 1150 °C, under both pyrolysis and combustion atmospheres.
The volatilized material was quantified by means of mass balances based on char and ash elemental analysis, compared to a corresponding feedstock fuel analysis. Close relations between the observed K and Cl release are found, suggesting that Cl is the main facilitator for K release through sublimation of KCl, determined to begin as the reaction temperature approaches 700-800 °C.
K is present in abundance relative to Cl, and the K release is found to cease as the fuel reaches complete dechlorination. In addition, around 50 wt% of the Cl is released at temperatures below 500 °C, presumably as HCl formed through ion-exchange reactions with functional groups in the organic matrix.
Complete dechlorination was achieved under combustion conditions as the temperature exceeded 800 °C. Approximately 50 wt% of the feedstock S is released at temperatures below 500 °C. This low-temperature release is related to the decomposition of the organic matrix, releasing the organically associated S.
Under combustion conditions, the S release increases gradually at temperatures exceeding 800 °C, eventually reaching complete desulfurization at 1150 °C. The silicate/ alumina chemistry is found to play a significant role in the alkali retention. The Si-rich sample is capable of retaining all excess K not released as KCl.
Language: | English |
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Publisher: | American Chemical Society (ACS) |
Year: | 2011 |
Pages: | 4961-4971 |
ISSN: | 15205029 and 08870624 |
Types: | Journal article |
DOI: | 10.1021/ef201098n |
ORCIDs: | Johansen, Joakim Myung , Frandsen, Flemming and Glarborg, Peter |