Paper details

Title:

Decomposition of Tar Model Compound Toluene by Treatment with the High-temperature Hydrogen/Oxygen Flame

Author(s):

Granovskii, M., Gerspacher, R., Pugsley, T., Sanchez, F.

Document(s):

Abstract:

A complete decomposition of all organic molecules generated as a result of biomass gasification into simple inorganic species like CO and H2 (syngas) means both an improved energy efficiency and technological robustness of the process of renewable synthesis gas (syngas) production. The syngas could be then converted into synthetic fuels, chemicals or electricity. A contamination of the produced syngas with polyaromatic hydrocarbons (PAH) promotes an origination of tar which, when the temperature of the gas becomes lower, deposits on the inner surfaces of the downstream equipment inducing its fouling and possibly its failure. A non­catalytic method of tar decomposition includes mixing of gasification products with plasma gas (usually air) generated by its heating to extremely high temperatures (50000C and higher) in a high­voltage electrical field. Combustion products at temperatures of the oxy­fuel flames could be also considered as plasma due to a presence of ionized particles, radicals and free electrons. The effect of continuous injection of the hydrogen/oxygen high­temperature flame into the blend of gases containing toluene in order to decompose the latter has been studied in the present work. Toluene in the mixture with nitrogen and steam (reaction mixture) was selected as a tar model compound because it has been regarded by many researchers as a precursor of heavier polyaromatic compounds in high temperature gasification processes. The experimental results indicate that treatment of the reaction mixture with the stoichiometric hydrogen/oxygen flame leads to the reforming of toluene into H2 and CO. A certain excess of oxygen in the flame promotes almost complete toluene decomposition into syngas in the regime of its partial oxidation. In spite of some reduction in the amount of syngas produced, that excess oxygen in the hydrogen/oxygen flame could be efficiently applied to the syngas contaminated with tars; this allows the original syngas heating value to remain unchanged. A mechanism of hydrogen/oxygen flame influence on tar destruction/decomposition pathways is also discussed. Hydrogen and oxygen could be technically produced by electrolysis of water. The efficiency of electricity utilization to make the hydrogen/oxygen flame in order to decompose volatile organic compounds and tars will be a subject for our following studies.

Keywords:

bioenergy, combustion, hydrogen, syngas, tar, thermochemical conversion

Topic:

Biomass Conversion Technologies for Heating, Electricity and Chemicals                  

Subtopic:

Gasification for synthesis gas production

Event:

19th European Biomass Conference and Exhibition

Session:

VP2.4.1

Pages:

1530 - 1538

ISBN-13:

978-88-89407-55-4

ISBN-10:

88-89407-55-7

Paper DOI:

10.5071/19thEUBCE2011-VP2.4.1

Price:

FREE