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Inorganics play many roles in biomass gasification

M.Sc. Jason Kramb studied the role of inorganic elements in biomass gasification, focusing on catalytic effects in char gasification and removal of toxic metals from the product gas.

The behavior of char in a gasifier has been shown to be strongly affected by the presence of inorganics in the parent fuel, and this can influence the overall operation and efficiency of the gasification process. Emissions of inorganic compounds during gasification, especially from chemically treated wood, can be toxic and gas cleaning systems can be a significant overall cost.

Spruce and birch woods were leached of the naturally occurring ash forming elements and loaded with varying amounts of calcium or potassium. These woods were then gasified in either an isothermal thermogravimetric analysis device or a bubbling fluidized bed reactor. In the case of the spruce wood gasified using the thermogravimetric analysis device, char conversion models were evaluated against the measured data and an empirical model was developed which uses the concentration of calcium and potassium in wood to predict the conversion rate behavior of the char when gasified in CO2. The results from the fluidized bed gasification tests of birch wood showed that calcium was the primary active catalyst in the wood and the increased reactivity resulting from calcium doping was clear even in the much larger scale of a fluidized bed compared to the thermogravimetric analysis. The potassium doped samples did not exhibit increased reactivity in the fluidized bed due a nonreactive layer of secondary char being deposited on the char surface.

The behavior of arsenic in the product gas of chromated-copper arsenate wood was modeled using equilibrium calculations and measured experimentally in a bubbling fluidized bed. The equilibrium model accurately predicted that the product gas could be cleaned by cooling the gas below 260°C and filtering to remove condensed arsenic.

Public defense of doctoral dissertation on Friday, 13 January

M.Sc. Jason Kramb will defend his doctoral thesis titled “The Role of Inorganics in Biomass Gasification: Catalytic Effects on Char Reactions and Toxic Emissions” on Friday, 13 of January 2017, starting at 12:00 in Konetalo room K1702 at Tampere University of Technology. Professor Tobias Richards, University of Borås, Department of Resource Recovery and Building Technology will act as the opponent. The custos will be Professor Jukka Konttinen from the Laboratory of Chemistry and Bioengineering.

The dissertation is available online at http://urn.fi/URN:ISBN:978-952-15-3897-1.

Further information: Jason Kramb , 0400 299614

News submitted by: Sanna Kähkönen
Keywords: science and research, energy