Metals in petroleum fractions have a deleterious effect on the refining equipment and catalyst. They corrode the equipment, plug the catalyst pores, and create irregularities in the system. With reference to today's petroleum industry, the fast depletion of light crude has created the need to process heavier crudes with much higher metal content. Hence, the need to remove traces of harmful metals and restrict their accumulation in feed stocks has become a pressing issue. In this context, we review developments over the past decade in regard to the methods of metal removal with a focus on unconventional methods, such as the use of molecularly imprinted polymers, supercritical fluids, and irradiation. Other methods of demetallization discussed include the usage of nanocatalysts, micro-organisms, and certain solvents. The removal of vanadium and nickel were reviewed most, because of the abundance of these elements in the crude.

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Gas-fluidization of Geldart A particles was simulated for a domain of lab-scale dimensions. Hydrodynamics of homogeneous regime and transition to bubbling were studied. In this context a detailed fine mesh simulation study is presented for the first time, using the state-of-the-art two-fluid model (TFM). The effect of particle density was investigated. The fine mesh simulations were analyzed for insights into bed transition from homogeneous to bubbling regime and the effect of interparticle forces (IPFs). Simulations reveal that transition to bubbling occurs over a velocity range rather than at a discrete velocity. We propose an index to quantify the effect of IPFs on bed expansion. During homogeneous expansion this IPF index was found to drop exponentially with velocity. It became negligible as bubbling ensued which is in line with the literature. The simulated average bed voidage was found comparable to the corresponding Eulerian−Lagrangian and experimental data.

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