Mitigation of crude oil fouling by turbulence enhancement in a batch stirred cell

A compact batch stirred cell has been used to investigate crude oil fouling on bare mild steel test probes and on similar probes fitted with thin wires to promote turbulence and increase surface shear stresses. The results show that, under otherwise identical operating conditions, the fouling rate on the surface of the probe fitted with wires was significantly lower than on the surface of the bare probe. Moreover, the fouling resistance data using the wired probe were seen to be much more scattered over time which suggests that the additional turbulence, and hence the associated additional shear stress, and perhaps even the associated uneven circumferential shear stress distribution, were creating a greater random removal of the fouling deposit from the surface. CFD simulations of the fluid flow for both the bare and wired probes were conducted using the commercial multiphysics package Comsol 4.2. The CFD simulation results show that the surface shear stress indeed varies in a periodic manner around the wired probe surface, being greater immediately in front of a wire, and lower immediately behind a wire in respect of the flow direction. The CFD simulation results show that, for otherwise identical conditions, the shear stress on the wired probe was significantly greater than that on original bare probe even at the point of lowest circumferential shear stress. The CFD results thereby allow better interpretation of the experimental fouling data on the enhanced surface.