Exposure studies of refractory materials for biomass gasification
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Gasification is a technology mostly used to convert fossil feedstock to syngas. Biomass could be used as a feedstock instead but that puts different demands on, among other things, the materials in these reactors.
In this work, two candidate materials for the inner lining in biomass gasifiers (63 and 85 weight percent Al2O3) have been exposed to three synthetic ashes, K2CO3-CaCO3-SiO2, K2CO3-CaCO3 and K2CO3 at 1050°C in CO2 atmosphere for 7 days in a muffle furnace to reproduce analogous chemical attack that would occur in a real gasifier. Samples were investigated with SEM-EDX for morphological and compositional effects and with XRD for crystalline phases at chosen distances from the exposed surface.
A heterogeneous melt that prevented deep penetration of alkali was produced when Si was present in the ash composition. In the absence of Si, it turned out that only K was affecting the materials. K attacked the matrix and transported into the material and attacking grains. For the material containing more alumina potassium was found in continuously decreasing amounts down to 7-8 mm from the exposed surface. The other material showed a distinct border between affected and pristine matrix about 5 mm from the exposed surface. The affected part seemed to have been filled out and signs of expansion could be seen. The XRD analysis of the pristine and exposed refractories revealed significant differences. In the exposed ceramics the new phases; Leucite, Kalsilite, Kaliophilite, K(2-x)Al(2-x)SixO4 and Wollastonite were observed.
Place, publisher, year, edition, pages
2013. , 38 p.
Gasification, biomass, high alumina refractories, alkali, slag
IdentifiersURN: urn:nbn:se:umu:diva-66449OAI: oai:DiVA.org:umu-66449DiVA: diva2:606774
Subject / course
Master of Science Programme in Energy Engineering
2013-01-24, A201, X, Håken Gullessons väg 20, Teknikhuset, A201, Umeå, 13:59 (Swedish)
UppsokPhysics, Chemistry, Mathematics
Boström, Dan, professorBackman, Rainer, professor
Eklund, Robert, Universitetslektor