Wax deposition in single phase flow

Abstract

A series of experiments on wax deposition from oil have been performed in a 50-m long by 43.4 mm ID jacketed flow loop at Tulsa University. Tests were performed on a 35°API crude oil from the Gulf of Mexico with a wax appearance temperature (WAT) of 120°F. The series of tests were designed to determine temperature and flow rate effects on the deposition rate and fraction of oil in the deposit. The deposit thickness in the flow loop was determined using five methods; pressure difference, energy balance, the spool piece volume change (LDLD), ultrasonic transit time, and direct measurement in a test section. Samples of the deposits were analyzed at the conclusion of each test for included oil. The effect of the difference in temperature between the oil and pipe wall showed a simple increasing deposition rate with temperature difference. The change in deposition rate was a weak function of oil temperature relative to WAT. The variation in deposition rate with flow velocity gave large differences between laminar and turbulent flow. Deposit oil contents decreased with increasing flow velocity. The fraction of oil in the deposit decreased with time in turbulent flow tests but did not change in laminar tests.