Operational stability and productivity of an iron-making blast furnace relies on the permeability of the bed, which is adversely affected by the accumulation of unburnt coal and fine coke powder resulting from Pulverised Coal Injection (PCI) and coke degradation. Stable operation at a high PCI rate necessitates an understanding of gas-fine powder distribution, which is affected by the cohesive zone, and raceway shape and size. A computational study of a laterally injected gas-fine powder flow through a tuyere, into a packed bed is conducted in the presence of raceway and cohesive layers. An experimental correlation is used to predict the static holdup. The effect of operational parameters such as gas flow rate, particle and fine properties, and structural parameters such as cohesive zone configuration, porosity, and tuyere protrusion are analysed. Sensitivity analysis shows raceway shape, size, and interaction with the cohesive blocks affects the distribution and accumulation of fine powder.
Gaseous flow through ultra-tight porous media, e.g. shale and some high-performance insulation materials, is often rarefied, invalidating an analysis by the continuum flow theory. Such rarefied flows can be accurately described by the kinetic theory of gases which utilizes the Boltzmann equation and its simplified kinetic models. While discrete velocity methods (DVM) have been successful in directly solving these equations, the immense potential of a particle-based solution of the variance-reduced Boltzmann-BGK (Bhatnagar-Gross-Krook) equation for rarefied flows in porous media has not been exploited yet. Here, a parallel solver based on the low variance deviational simulation Monte Carlo (LVDSMC) method is developed for 3D flows, which enables pore-scale simulations using digital images of porous media samples. The unique advantage of this particle-based formulation is in providing additional insights regarding the multi-scale nature of the flow and surface/gas interactions via two new parameters, i.e. pore and surface activity respectively. Together, these two parameters can identify key flow properties of the porous media. The computational efficiency and accuracy of the current method has also been analysed, suggesting that this new solver is a powerful simulation tool to quantify flow properties of ultra-tight porous media.
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