Abstract

In this article, numerical investigations on mixing and heat transfer of solid refused fuel (SRF) particles in a bubbling fluidized bed are carried out. The numerical model is based on the Eulerian–Eulerian approach with empirical submodels representing gas–solid and solid–solid interactions. The model is verified by experimental data from the literature. The experimental data include SRF vertical distribution in SRF–sand mixtures of different sand particle sizes (d_{mathrm{pm}} = 654,810 and 1110 upmum) at different fluidization velocities (u/u_{mathrm{mf}} = 1.2–2.0). We proposed magnification of drag force exerted by the gas on SRF particles based on Haider and Levenspiel (Powder Technol 58(1):63–70, 1989) drag coefficient. The proposed model shows good agreement with the experimental data at high fluidization velocities ( u/u_{mathrm{mf}} = 1.5–2.0) and poor predictions at low fluidization velocities (u/u_{mathrm{mf}} = 1.2–1.5). Heat transfer results showed that the present model is valid and gives good agreement with the experimental data of wall–bed heat transfer coefficient.

Highlights

  • Fluidized beds offer excellent mixing and heat transfer characteristics which make them efficient in thermal conversion applications, i.e., combustion/gasification of low-grade coal, biomass, and solid refused fuel (SRF) [38]

  • The overall fuel concentration within the fluidized bed combustor is very low compared to the bed material (2–5 mass%) [27]; the big differences in the density and size ratios can significantly affect the homogeneity of the bed [32]

  • A considerable number of experimental and theoretical studies were performed to investigate hydrodynamics and combustion/gasification of SRF/municipal solid waste (MSW) [4, 5, 7, 20, 22,23,24,25, 31, 36, 39, 43,44,45, 47], but few studies have been concerned with simulation of this complex binary mixtures particles in fuel-sand bubbling fluidized beds [41, 42]

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Summary

Introduction

Fluidized beds offer excellent mixing and heat transfer characteristics which make them efficient in thermal conversion applications, i.e., combustion/gasification of low-grade coal, biomass, and solid refused fuel (SRF) [38]. A considerable number of experimental and theoretical studies were performed to investigate hydrodynamics and combustion/gasification of SRF/MSW [4, 5, 7, 20, 22,23,24,25, 31, 36, 39, 43,44,45, 47], but few studies have been concerned with simulation of this complex binary mixtures (irregular shape and large size) particles in fuel-sand bubbling fluidized beds [41, 42]. This figure indicates the variation on Gidaspow drag force calculated using different sphericity ratio drag coefficients.

Results and discussion
Conclusions
ANSYS FLUENT
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