Mechanisms of agglomeration in fluidized bed: Reactions between potassium carbonate and silica

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Abstract

Agglomeration is one of the main operational problems in fluidized bed combustion of biomass. Agglomeration is induced by interaction between the potassium species present in biomass and the bed materials (i.e. silica sand). To understand agglomeration mechanisms in biomass combustion, mixtures of model potassium compounds (KCl, K2SO4 and K2CO3) and silica sand were tested in bench scale fluidized bed reactors indicating that only potassium carbonate is able to react with the silica sand particles forming low melting point potassium silicates. The objective of this work is to reveal the reaction mechanism between K2CO3 and silica sand, which can be an important step in understanding overall agglomeration mechanism in fluidized bed combustion of biomass. The results indicate that the reaction between K2CO3 and silica sand occurred in solid-solid phase with reasonably high reaction rate under fluidized bed combustion temperature (> 800 °C). The initial reaction stage is dominated by surface diffusion of the salt molecules invading fresh silica sand surface, followed by the formation of a thin product layer. The reaction further proceeds by diffusion through the formed product layer. The reaction rate is dependent on temperature, CO2 partial pressure, particle size and mixing of the reactants. The experimental data obtained in this work provide a basis for further modeling of the agglomeration process in fluidized bed combustion of biomass.
Original languageEnglish
Publication date2017
Number of pages8
Publication statusPublished - 2017
Event12th International Conference on Fluid Bed Technology (CFB-12) - AGH University of Science and Technology., Krakow, Poland
Duration: 23 May 201726 May 2017

Conference

Conference12th International Conference on Fluid Bed Technology (CFB-12)
LocationAGH University of Science and Technology.
CountryPoland
CityKrakow
Period23/05/201726/05/2017

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