Evaluation of co-volume mixing rules for bitumen liquid density and bubble pressure estimation |
| |
Authors: | Richard A McFarlane Murray R Gray John M Shaw |
| |
Institution: | 1. Alberta Research Council Inc., 250 Karl Clark Road, Edmonton, Alberta, Canada T6N 1E4;2. Department of Chemical and Materials Engineering, University of Alberta, 116th St., 92nd Ave., Edmonton, Alberta, Canada T6G 2G6 |
| |
Abstract: | The Peng–Robinson cubic equation of state (CEOS) is widely used to predict thermodynamic properties of pure fluids and mixtures. The usual implementation of this CEOS requires critical properties of each pure component and combining rules for mixtures. Determining critical properties for components of heavy asymmetric mixtures such as bitumen is a challenge due to thermolysis at elevated temperatures. Group contribution (GC) methods were applied for the determination of critical properties of molecular representations developed by Sheremata for Athabasca vacuum tower bottoms (VTB). In contrast to other GC methods evaluated, the Marrero–Gani GC method yielded estimated critical properties with realistic, non-negative values, followed more consistent trends with molar mass and yielded normal boiling points consistent with high temperature simulated distillation data. Application of classical mixing rules to a heavy asymmetric mixture such as bitumen yields saturated liquid density and bubble pressure estimates in qualitative agreement with experimental data. However the errors are too large for engineering calculations. In this work, new composite mixing rules for computing co-volumes of asymmetric mixtures are developed and evaluated. For example, composite mixing rules give improved bubble point predictions for the binary mixture ethane + n-tetratetracontane. For VTB and VTB + decane mixtures the new composite mixing rules showed encouraging results in predicting bubble point pressures and liquid phase densities. |
| |
Keywords: | CEOS cubic equation of state GC group contribution HTSD high temperature simulated distillation HVGO heavy vacuum gas oil PRCEOS Peng&ndash Robinson cubic equation of state SCE supercritical extraction SG specific gravity vdW van der Waals (cubic equation of state or mixing rule) VLE vapour&ndash liquid equilibrium VTB vacuum tower bottoms from Athabasca bitumen |
本文献已被 ScienceDirect 等数据库收录! |
|