Mass transfer in relation to flow induced corrosion of the bottom of cylindrical agitated vessels

Abstract

The diffusion controlled corrosion of the base of agitated vessels with flat and conical bottom was studied using the diffusion controlled dissolution of copper in acidified dichromate technique. Variables studied were impeller rotation speed, inclination of the conical bottom, physical properties of the solution and the presence of drag reducing polymers. For the present case where four blade 45° pitched turbine impeller was used in a baffled agitated vessel, the rate of diffusion controlled corrosion of the flat bottom was given by the equation Sh=0.586Sc 0.33Re 0.658 while for the conical bottom the data were correlated by the equation Sh=0.204Sc 0.33Re 0.7(L/r) −0.33. Drag reducing polymers were found to inhibit diffusion controlled corrosion only in agitated vessels with flat bottom, they were found to have little effect on the rate of corrosion of conical bottoms.