A conversion-class model for describing fuel conversion in large-scale fluidized bed units
Artikel i vetenskaplig tidskrift, 2017

Solid fuel conversion in fluidized beds is often modelled with the use of population balances, where the fuel conversion process is divided into a number of classes based on for example fuel particle size. The present work investigates and evaluates different methods for the discretisation of the fuel conversion process into classes, as well as the number of classes necessary to yield a satisfactory accuracy. A discretisation method, which defines classes based on the conversion degree (rather than size or density) and that is valid for all conversion regimes, is proposed. The results show that application of the proposed class division method for modelling biomass gasification in a fluidized bed gives an accuracy that is up to ten times higher than that given by a distribution with equally large classes. For all three conversion processes of biomass gasification (drying, pyrolysis, and char gasification), discretisation into 6 classes is sufficient to yield errors of around 1%, when compared to the continuous conversion curves given as input to the conversion class discretisation model (generated by a particle model in the present work). In line with this, when the conversion class model is used in a semi-empirical 1D model of indirect biomass gasification, the resulting char conversion in the gasifier does not change significantly when more than 3–6 char conversion classes are used.

fluidized bed

population balance

fuel conversion

gasification

combustion

fuel classes

Författare

Louise Lundberg

Chalmers, Energi och miljö, Energiteknik

Robert Johansson

Chalmers, Energi och miljö, Energiteknik

David Pallarès

Chalmers, Energi och miljö, Energiteknik

Henrik Thunman

Chalmers, Energi och miljö, Energiteknik

Fuel

0016-2361 (ISSN)

Vol. 197 42-50

Drivkrafter

Hållbar utveckling

Ämneskategorier

Energiteknik

Styrkeområden

Energi

DOI

10.1016/j.fuel.2017.01.090