Stepwise analysis of gasification reactions with aspen plus and CPFD

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, H 2 and CH 4 . The gas can be further processed to bioproducts or fuels. The thermochemical process involves devolatilization of wood followed by steam gasification, CO 2 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 dimensional and solves the included reactions fast.The results of the Aspen Plus and CPFD simulations, given as product gas compositions (CO, CO 2 , CH 4 and H 2 ), 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.

A review of biomass gasification modelling

“…The complexity and dimensions of the model are also increased with the desired model outputs, that is, with more detailed reaction kinetics and reactor hydrodynamics. However, because it has been frequently reported that the complex solid-fluid contact patterns of fluidized bed gasifiers may result in larger deviations from ideal equilibrium compositions (and ideal mixing), kinetic-hydrodynamic modelling is a particularly common approach chosen for modelling fluidized bed gasifiers, as argued by several authors [25,28,37,38,42,51,54,56,64]. The promise of potentially more accurate results motivates about 34% of the researchers who model gasification to employ simulations that model the kinetics of key reactions (see Fig.…”

“…[25,37,56]), Kin-total (e.g. [27,28,38,52,64,72,73,81,83,85]), and Ki/Eq (CRF) (e.g. [31, 40-42, 58, 121]) approaches.…”

Performance analysis of power generation by wood and woody biomass gasification in a downdraft gasifier

“…After pyrolysis, RGibbs is applied for simulation of the biomass gasification. This reactor computes the syngas composition by minimizing the Gibbs free energy based on complete chemical equilibrium assumption [57][58][59][60][61]. Input streams to the RGibbs are decomposed biomass and air then combustion and reduction reactions will be occurred inside of the reactor.…”