Experimental and Modeling Study of Residual Liquid Recovery from Spent Sand in Bitumen Extraction Processes from Oil Sands

摘要

Disposing solid residue with high liquid content into the environment may impact the immediate ecosystem and its surroundings. In bitumen recovery process from oil sands, it is environmentally and economically desirable to effectively recover as much of the liquid trapped in the spent solids as possible, prior to releasing it into the environment. An experiment was designed to investigate the effect of capillary force to enhance liquid recovery by using a thin, semipermeable layer as the membrane. The results indicate that by employing a membrane at the outlet, and pressurizing the air above the sand bed, the average liquid saturation can be decreased by 50%; however, the maximum pressure applied is restricted by the physical characteristics of the membrane. A mathematical model is developed to predict the liquid saturation profile along the sand pack during transient and steady-state conditions, and results are validated against measured average saturation using two different sand types. Results suggest that more liquid can be recovered from the spent sand bed by increasing the height of the bed; however, the required time to achieve the maximum recovery is increased as well. This method can be applied to reduce the liquid content of spent sand from any process before it is disposed of, thereby reducing possible hazards which may affect the environment.