Steam‐air blown bubbling fluidized bed biomass gasification (BFBBG): Multi‐scale models and experimental validation

Abstract

in Wiley Online Library (wileyonlinelibrary.com)During fluidized bed biomass gasification, complex gas-solid mixing patterns and numerous chemical and physical phenomena make identification of optimal operating conditions challenging. In this work, a parametric experimental campaign was carried out alongside the development of a coupled reactor network model which successfully integrates the individually validated sub-models to predict steady-state reactor performance metrics and outputs. The experiments utilized an integrated gasification system consisting of an externally-heated, bench-scale, 4-in., 5 kWth, fluidized bed steam/air blown gasifier fed with woody biomass equipped with a molecular beam mass spectrometer to directly measure tar species. The operating temperature (750-8508C) and air/fuel equivalence ratio (ER 5 0-0.157) were independently varied to isolate their effects. Elevating temperature is shown to improve the char gasification rate and reduce tar concentrations. Air strongly impacts the composition of tar, accelerating the conversion of lighter polycyclicaromatic hydrocarbons into soot precursors, while also improving the overall carbon conversion.

Multi-scale modelling of fluidized bed biomass gasification using a 1D particle model coupled to CFD

“…However, studies of Mermoud et al [25] and Van de Steene et al [26] show the relevance of particle size on the conversion time based on experimental data and single particle modelling. Bates et al [27] conducted a time scale analysis of biomass particles in a fluidized bed environment and state that heat transfer limitations dominate pyrolysis and drying as these processes show rather fast kinetics. They found a Biot number close to 1 for 6 mm particles which means internal temperature gradients are present.…”

Modeling Biowaste Biorefineries: A Review

“…Other contributions include the kinetic-compartmental model for the gasification of potassium-containing cellulose (Egedy et al, 2018), the compact kinetic biomass gasification model (Goyal and Pepiot, 2017), and the multi-scale model of biomass gasification in a steam-air blown bubbling fluidized bed reactor (Bates et al, 2017). Due to their high resemblance to the already discussed kinetic models in section 4.1, these models will not be further discussed.…”

Bubbling fluidized bed methanation study with resolving the mesoscale structure effects

“…For the mass and heat transfer in the particle scale, it is necessary to evaluate the relative importance of the external diffusion, internal diffusion, and chemical reactions to determine the effectiveness factors ( η j ) in Equations . According to the work of Bates et al, timescale analysis is an effective method to identify the relative importance of various transfer phenomena and chemical reactions. The timescales of mass and heat transfer due to different processes (Table ) are compared to determine the rate‐determining step of mass and heat transfer.…”