Publicou 6 edições por ano
ISSN Imprimir: 1940-2503
ISSN On-line: 1940-2554
Indexed in
INFLUENCE OF DUST ON THE HEAT TRANSFER IN A FIXED BED REACTOR
RESUMO
This investigation focuses on the influence of dust on heat transfer in a fixed bed reactor. Industrial application shows that the heat transfer with dust is significantly smaller than without dust. To determine the reason for this effect, a laboratory-scale fixed bed reactor was built and transient temperature profiles measured at different positions in the fixed bed. In the experimental study, a three-phase system (solid, solid, gas) including dust is compared with a two-phase system (solid, gas) for three different bed materials, such as mono- and polydisperse solid iron spheres, direct reduced iron ore, and char particles. The measured data were evaluated by using a modified two-phase model with separate heat balances for a pseudohomogenous solid and a gas phase which were solved by analytical approximation and a numerical method using a commercial program, Aspen Custom Modeler. For determination of the heat-transfer coefficients, parameter estimation was done using the internal program Nelder Mead algorithm. The results were compared with established correlations and data from literature and show significant influence of dust on the heat-transfer rates due to channeling effects caused by local dust accumulation. Due to particle size distribution and different specific surfaces, the reduction of the gas-solid heat-transfer coefficient for char and direct reduced iron ore is less pronounced than for mono- and polydisperse solid iron spheres. The heat-transfer coefficient decreases to 6% in comparison with the results without dust.
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