Measurement of wax deposition on a cold steel disk has been conducted with a 5 wt% solution of n-tetracosane dissolved in n-decane as a function of flow velocity across the disk, the temperature of the disk and the temperature of the bulk oil. A novel "Cold Disk" Wax Deposition Apparatus (CoDWaD) capable of producing "field like" wax deposits with relatively small volumes of oil in a matter of minutes was used to create deposits. The apparatus was found to reproduce the accepted variation of deposition rate in terms of the temperature difference between the cold wall (disk) and bulk fluids, the variation of deposition rate with flow velocity, and the variation of hardness (oil content) of the deposit with time found in flow loop experiments. It was also observed that the fraction of wax in the deposit (high molecular weight compounds (i.e. C_(24)H_(50))) increased gradually with increasing flow rate for the same test duration and that deposition occurred when the fluid velocity was effectively zero (no stirring). A final confirmation of the binary mixture results was conduced with a North Sea crude oil. This result is consistent with the observations of Singh et al., 1999 (J. Rheol., 43, 1437).
展开▼
