Abstract:
Aiming at the phenomenon that wax crystal particles at mesoscopic scale aggregate on the pipe wall to form a macroscopic paraffin layer, the filtered two-fluid model was used to study the liquid-solid two-phase flow and heat transfer characteristics of heavy oil accompanied by solid asphaltene transported in horizontal pipelines. By comparing the simulation results obtained from the homogeneous drag model(Gidaspow model), the Filtered model without wall correction(Filtered model Ⅰ), and the Filtered model with wall correction(Filtered model Ⅱ), the distribution laws of parameters such as the time-average asphaltic residues volume fraction, the solid pressures, and the correction to filtered interphase heat transfer coefficient along the radial direction were obtained. At the same time, the influence of pipe wall temperature on the temperature distribution and heat transfer coefficient of heavy oil was analyzed. The results show that compared with the Gidaspow model, the filtered model can show the changing law of the non-uniform flow structure of wax crystal particles on liquid-solid two-phase flow. It is revealed that the predicted pressure drops based on Filtered model Ⅱ corresponds well with the experimental data, and the Filtered model Ⅱ simulation results decrease as wax particle volume fraction increases. Obviously, when the volume fraction of wax particles increases to 12%, the error of the sub-lattice model with wall correction is only 4.1%, while the error between ZAMBRANO simulation and experimental pressure drop is 12.9%. The mesoscopic-scale flow behavior of particle clusters is detailedly reproduced with a filtered model considering wall correction, providing a new strategy for the prediction of wax aggregation and flow process during heavy oil transportation.