Experimental and Modeling Studies of Pulverized Biomass Combustion: Analysis of Flames, Superheaters, and Gaseous and Particulate Emissions

Niko Niemelä

Research output: Book/ReportDoctoral thesisCollection of Articles

Abstract

Bioenergy has an important role in climate change mitigation scenarios, and biomass use is projected to increase significantly in the future. Mainly residue feedstocks from e.g. forestry, agriculture and industry will be available for combustion applications. Currently, residue usage in combustion furnaces is limited due to its problematic ash composition. Another difficulty with biomass combustion is the emission of airpollutants, such as NOx, soot (black carbon), and fine particulate matter. The development of clean and efficient combustion systems requires detailed understanding of the physical and chemical processes inside combustion furnaces, which are fundamentally coupled with the intrinsic properties of biomass, such as devolatilization reactivity and elemental ash composition.

This thesis examines pulverized biomass combustion technology. The biomass combustion process, emission formation, inorganic ash behavior, and superheater phenomena are studied at a detailed level for raw and pretreated biomass. Experiments and simulations were conducted in a laboratory scale drop-tube reactor, a pilot scale combustion reactor, and a full-scale district heating plant. This combination provides insight into the influence of biomass properties on the combustion process and emission formation. This detailed scientific understanding can eventually be used for emission reduction and for widening the range of feedstocks suitable for biomass heat and power generation.

The major contributions of this thesis are the various modeling approaches that were developed for characterizing the furnace processes for different biomass feedstocks. These include simulation methods for biomass devolatilization, soot and inorganic fine particle formation, and superheater analysis. The results of this thesis show that complicated furnace phenomena are accurately represented by these models, and the models can ultimately aid the development of clean and efficient combustion systems.
Original languageEnglish
Place of PublicationTampere
PublisherTampere University
ISBN (Electronic)978-952-03-2348-6
ISBN (Print)978-952-03-2347-9
Publication statusPublished - 2022
Publication typeG5 Doctoral dissertation (articles)

Publication series

NameTampere University Dissertations - Tampereen yliopiston väitöskirjat
Volume577
ISSN (Print)2489-9860
ISSN (Electronic)2490-0028

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