DOI: 10.1615/ICHMT.2008.CHT
ISBN Print: 978-1-56700-253-9
ISSN: 2578-5486
INFLUENCE OF DUST ON THE HEAT TRANSFER IN A FIXED BED REACTOR
SINOPSIS
Objective of the investigation is the influence of dust on the 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 full 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 pseudo homogenous solid and a gas phase which was solved by analytical approximation and numerical method using commercial program Aspen Custom Modeler®. For the determination of the heat transfer coefficients parameter estimation has been done using the program internal 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 channelling effects caused by local dust accumulation. Due to particle size distribution and different specific surfaces the reduction of the heat transfer coefficient gas-solid for char and DRI is less pronounced than for mono- and polydisperse full iron spheres. The heat transfer coefficient decreases to six percent in comparison with the results without dust.