Author(s)

M.S. EIKELAND & R.K. THAPA

Abstract

The energy from biomass can be utilized through the thermochemical conversion processes of pyrolysis and gasification. Biomass such as wood chips is heated in a gasification reactor to produce a synthesis gas containing CO, H₂ and CH₄. The gas can be further processed to bioproducts or fuels. The thermo-chemical process involves devolatilization of wood followed by steam gasification, CO₂ gasification, methanation, water gas shift reactions and methane reforming. To optimize the performance of the reactor, it is important to study each of the reactions separately.

The reactions are simulated individually using the chemical process optimization software Aspen Plus. The results are compared with simulations performed with the Computational Particle Fluid Dynamic (CPFD) software Barracuda VR 15. The CPFD methodology solves the fluid and particle equations in three dimensions with the transient flow and is time-consuming. Aspen Plus is one dimen- sional and solves the included reactions fast.

The results of the Aspen Plus and CPFD simulations, given as product gas compositions (CO, CO₂, CH₄  and H₂), show that each reaction contributes to the product gas composition differently. Comparison between Aspen Plus and CPFD simulations of individual gasification reactions show good agreement. However, when all reactions are included in the simulations, there is a deviation in the volume fraction of product gas composition.

Keywords

Aspen Plus, biomass gasification reactor, CPFD, dual fluidized bed, reaction kinetics, steam gasification.