Article · High-temperature corrosion and ash · Bed materials and oxygen carriers
Ash Properties of Ilmenite Used as Bed Material for Combustion of Biomass in a Circulating Fluidized Bed Boiler
A. Corcoran, J. Marinkovic, F. Lind, H. Thunman, P. Knutsson, M. Seemann
Energy & Fuels 28, 7672–7679 (2014) · 103 citations
In plain language
Ilmenite draws potassium into its core
Up to 40 wt% of the sand in Chalmers' 12 MW boiler was replaced by the natural ore ilmenite. Iron moved to the particle surfaces, titanium concentrated in the core, the ash formed a calcium-rich double layer, and potassium diffused into the core to form KTi8O16. Locking potassium inside the particle could reduce both bed agglomeration and corrosion.
Abstract
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 MW th 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 KTi 8 O 16 . 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.
Abstract as indexed by OpenAlex.
BibTeX
@article{corcoran-2014-properties-ilmenite-material,
author = {Corcoran, A. and Marinkovic, J. and Lind, F. and Thunman, H. and Knutsson, P. and Seemann, M.},
title = {Ash Properties of Ilmenite Used as Bed Material for Combustion of Biomass in a Circulating Fluidized Bed Boiler},
journal = {Energy \& Fuels},
year = {2014},
volume = {28},
number = {12},
pages = {7672--7679},
doi = {10.1021/ef501810u}
}