Optimization of Residual Oil Hydrocrackers: Integration of Pump-Free Ebullated Bed Process with Membrane-Aided Gas Recovery System

摘要

The ebullated bed residual oil hydrocracking is a well-established technology wherein the vacuum residue (VR) of crude oil is converted into light valuable oils. This research work targeted to optimize the hydrocracking process by integrating the pump-free ebullated bed reactor (PF-EBR) with a membrane-based gas synthetic recovery system. A PF-EBR hydrocracking unit with a feed capacity of 3 x 10(6) t/a (ton per annum) of vacuum residues was modeled by the axial dispersion model; the 5-lump axial dispersion model and the finite difference model for PF-EBR and membrane unit were developed and packaged as self-defined extensions in Aspen HYSYS, allowing the integrated process to be evaluated in high efficiency and accuracy; the proposed model was further validated by the experimental data of the pilot and 5 x 10(4) t/a industrial unit. The results of process optimizations showed that the membrane-aided separation system demonstrated better performance than the conventional condensation system in separating hydrogen and hydrocarbons from bulk refinery gas. The recovery of hydrogen from the reactor effluent resulted in 30.0% drop in reactor fresh makeup hydrogen cost; the membrane-based system separated the light hydrocarbons from refinery flash gases, which boosted the net profit of hydrocarbon recovery by 80%, leading to $122.3 x 10(6)/a increase in the total product sale (about 7% of the hydrocracker total sale). This study bridged the gap between theoretical models and industrial PF-EBR processes and provided a designing framework for the integrate process of PF-EBR VR hydrocracking and gas synthetic recovery system. The described improvements implied significant reductions in energy cost, carbon footprint, and operational cost; the estimated reduction in CO2 emissions is around 2.6 x 10(4) t/a; all are attributed to the thorough gas recovery.