Continuum theory for dense gas-solid flow: A state-of-the-art review

In this work, an Euler–Euler multiphase CFD model is proposed for continuous fast pyrolysis of biomass in a fluidized-bed reactor. In the model, a lumped, multi-component, multi-stage kinetic model is applied to describe the pyrolysis of a biomass particle. Variable particle porosity is used to account for the evolution of the particle's physical properties. Biomass is modeled as a composite of three reference components: cellulose, hemicellulose, and lignin. Pyrolysis products are categorized into three groups: gas, tar vapor (bio-oil), and solid char. The particle kinetic processes and their interactions with the reactive gas phase are modeled with a multi-fluid description derived from the kinetic theory of granular flows. A time-splitting approach is applied to decouple the convection and reaction calculations using a synchronized time step. The CFD model is employed to study the fast pyrolysis of both cellulose and bagasse in a lab-scale fluidized-bed reactor. The dynamics, particle heating, reaction of the biomass phase, char formation, elutriation, and spatial distribution of tar and gas inside the reactor are investigated. The yields of tar, gas, and char are also discussed.

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A CFD model for biomass fast pyrolysis in fluidized-bed reactors

Numerical simulation of heat transfer in packed pebble beds: CFD-DEM coupled with particle thermal radiation

CFD-DEM coupled with thermochemical sub-models for biomass gasification: Validation and sensitivity analysis

Review and implementation of CFD-DEM applied to chemical process systems

CFD simulation of dense particulate reaction system: approaches, recent advances and applications

Dense particulate reaction system (DPRS) is quite common in many engineering fields such as energy conversion, petro-chemical processing, mineral processing, chemical engineering and pharmaceutical manufacturing. These kinds of processes are extremely complex involving both physical changes and chemical changes. Understanding the fundamentals governing the gas–particle flow and coupled heat and mass transfer is of paramount importance to the design, control and optimization of DPRS of various types. Computational fluid dynamics (CFD) has been recognized as a useful tool to achieve this goal. This paper provides a review of the CFD work in the simulation. The CFD approaches are categorized into Eulerian–Eulerian and Eulerian–Lagrangian ones. Detailed description and coupling scheme of gas–particle flow and chemical reaction of the two approaches are presented separately. An updated survey of published CFD studies is summarized. The developed models are shown to primarily involve Eulerian multi-fluid model, CFD-DEM (discrete element method) model and/or MP-PIC (multiphase particle-in-cell) model. Their respective advantages and limitations in application are analyzed. Finally, challenges and needs for future research are discussed.

Guanwen Zhou

Papers

CFD simulation of dense particulate reaction system: approaches, recent advances and applications

CFD Simulation of Dense Particulate Reaction System: Approaches, Recent Advances and Applications

Experimental tests on co-firing coal and biomass waste fuels in a fluidised bed under oxy-fuel combustion

Simulation of coal pressurized pyrolysis process in an industrial-scale spout-fluid bed reactor

Experimental study on characteristics of pressurized grade conversion of coal