Advanced simulation of biomass gasification in a fluidized bed reactor using ASPEN PLUS

Biomass gasification technology has improved over the years. However tar remains the bottleneck for gas cleaning, plant design and process modelling etc. Tar is a very complex material and its composition depends on many parameters like operating conditions, temperature, pressure, heating rate, oxygen carrying agent and reactor designs etc. While modelling tar, it is a common practice to either assume that gas is tar free or it is loaded over any heavy cyclic hydrocarbon. This is an over simplified approach. It is also a common assumption in literature that tar is inert and does not take part in reaction. The paper has taken into consideration both the challenges: it has defined tar and its cracking kinetics in the model. A mathematical model of biomass gasification in bubbling fluidized gasifier has been developed in ASPEN PLUS. A sub-model for tar generation and cracking is included in this study. The model is capable of dealing with wide variety of biomasses and fluidizing agents, i.e. air, oxygen, steam and carbon di oxide or a mix of these gases. A comparison with experimental data and other simulation results was done. Results show that defining tar and its kinetics significantly improves model performance and its credibility. (C) 2016 Elsevier Ltd. All rights reserved.