Ash Properties of Ilmenite Used as Bed Material for Combustion of Biomass in a Circulating Fluidized Bed Boiler
Journal article, 2014

Both agglomeration of bed material and corrosion of heat transfer equipment are issues related to combustion of biomass in a fluidized bed boiler. The biomass-ash component potassium is considered a major contributor for both phenomena. In this study, the conventionally used bed material, silica sand, was replaced with up to 40 wt % by the natural ore ilmenite in Chalmers 12 MWth circulating fluidized bed (CFB) boiler. In this study the purpose was to evaluate the physical and chemical changes ilmenite undergoes during this process. Close observations revealed that ilmenite underwent segregation of iron to the surfaces and an enrichment of titanium in the particle core. The ash formed a calcium-rich double layer on the particle, surrounding the iron layer. A diffusion of potassium into the particle core was also seen which led to the formation of KTi8O16. In addition to evaluating how ash components interact with the material, the ilmenite was leached and investigated as a possible potassium capturer. Leaching experiments on the used ilmenite showed that calcium and potassium were leachable to a very limited degree, namely, to less than 0.2 and 1 wt %, respectively, of the total content. The diffusion of potassium into the core of the particle could reduce both agglomeration and corrosion issues and could thereby be of great value for the improvement of the resistance of the bed material agglomeration in the fluidized bed boiler.

Author

Angelica Corcoran

Chalmers, Energy and Environment, Energy Technology

Jelena Maric

Chalmers, Energy and Environment, Energy Technology

Fredrik Lind

Chalmers, Energy and Environment, Energy Technology

Henrik Thunman

Chalmers, Energy and Environment, Energy Technology

Pavleta Knutsson

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Martin Seemann

Chalmers, Energy and Environment, Energy Technology

Energy & Fuels

0887-0624 (ISSN) 1520-5029 (eISSN)

Vol. 28 12 7672-7679

Driving Forces

Sustainable development

Subject Categories

Energy Engineering

Areas of Advance

Energy

DOI

10.1021/ef501810u

More information

Created

10/8/2017