Heat transfer characteristics of petroleum coke particle packed bed: An experimental and CFD simulation study

Abstract

Due to the complexity of the internal pore structure of petroleum coke loose particle-packed beds, measuring their thermal conductivity has always been a challenging problem. This work independently developed an experimental apparatus for testing the thermal conductivity of petroleum coke particle-packed beds and constructed a forward calculation model for the heat transfer process, which was based on one-dimensional unsteady heat transfer. Using the Sparse Nonlinear OPTimizer (SNOPT) algorithm, a mathematical relationship between the thermal conductivity λ of the coke bed, temperature T, and equivalent particle diameter d_p was established through inverse modeling. Concurrently, a digital model of the petroleum coke particle packed bed was derived utilizing three-dimensional computed tomography (CT) scanning technology, and a pore-scale gas–solid radiation heat transfer model was formulated based on CFD simulation technology, thereby further elucidating the heat transfer mechanism within the petroleum coke particle packed bed. The research results indicate that the temperature predicted by the established thermal conductivity model aligns well with experimental data. Further CFD simulation studies demonstrate that a smaller particle size leads to a larger temperature difference between the wall and the center of the packed bed, while a higher gas velocity results in a smaller temperature difference, with a linear correlation observed between these two factors. At high temperatures, thermal radiation between particles in the porous petroleum coke-packed bed plays a dominant role. The research outcomes can offer significant theoretical support for a profound analysis of the heat transfer behavior of petroleum coke-packed beds within a vertical shaft calciner.