Modeling wax deposition in pipelines

A multicomponent liquid-wax hydrodynamic model that incorporates phase equilibria and a full non-Newtonian behavior is proposed. In this model, molecular diffusion through the boundary layer induced by a temperature gradient between the liquid and the exterior pipe wall is assumed to be the dominant mechanism for deposition. Numerical solutions to the conservation equations for Newtonian and non-Newtonian flow regimes in a model pipe are presented, and results on calculated radial mass flux and wax deposition profiles as a function of time and position in a vertical pipeline are discussed in detail. The results are compared with predictions from a previous model developed by Svendsen (Svendsen, J. A. (1993). Mathematical modeling of wax deposition in oil pipeline systems. AIChE J. 39(8):1377-1388.) and with experimental flow data for a binary mixture reported by Cordoba and Schall (Cordoba A. J., Schall C. A. Application of a heat method to determine wax deposition in a hydrocarbon binary mixture. Fuel 2001 80:1285-1291). Good agreement in both cases is found.