Simulation of Lift-pipe Drying of Oil Shale Using Aspen

In previous works on modelling the oil shale retorting processes, ASPEN was used in conjunction with detailed models of reactors to perform heat and mass balances as well as to size reactors. Because the processes involve recycle loops and therefore require iterative calculations, this approach requires long computing time. A more efficient approach is to incorporate reactor performance equations which are derived from the data generated by the detailed models into the ASPEN flowsheets. These equations indirectly take into account the rates of various reactions, heat and mass transfer and the dynamics of the process units. The development of performance equations for two-stage lift-pipe drying and preheating of raw oil shale is described. Performance equations are presented for the two-stage drying unit of a hypothetical commercial plant producing 55,000 barrels of shale oil per day.