A 1-dimensional model of indirect biomass gasification in a dual fluidised bed system
Paper in proceedings, 2014

A 1-dimensional model is used to analyse how solids material circulation, biomass reactivity and gas mixing affect the char conversion in the Chalmers 2-4 MW indirect biomass gasifier. For the geometry and operational conditions particular to this unit, the model predicts a peak in char conversion for a solids circulation rate of around 3 kg/s. Char conversion is found to increase substantially with biomass reactivity and the level of gas mixing. At the experimental rate of solids circulation (6 kg/s), modelled char conversion values lie between 9% and 39% and are thus quite far from the experimental value of 2% (although potentially ranging between 0 and 10% due to experimental uncertainty). An explanation of the higher char conversion provided by the model could be the uncertainty in the reactivity of the biomass used. A further possible explanation, which has been studied by means of modelling in this work, is the gas mixing. The model uses expressions for the gas mixing which have been derived from measurements in smaller lab units with a high-pressure drop gas distributor, i.e. which induce a better gas mixing than the limited one existing in the large-scale unit studied here, caused by the presence of large bubbles and regions with weak fluidisation.

Author

Louise Lundberg

Chalmers, Energy and Environment, Energy Technology

David Pallarès

Chalmers, Energy and Environment, Energy Technology

Robert Johansson

Chalmers, Energy and Environment, Energy Technology

Henrik Thunman

Chalmers, Energy and Environment, Energy Technology

11th International Conference on Fluidized Bed Technology, CFB 2014; Beijing; China; 14 May 2014 through 17 May 2014

607-612

Driving Forces

Sustainable development

Subject Categories

Energy Engineering

Areas of Advance

Energy

More information

Created

10/7/2017