زهرا دست باز

The present study is aimed at fabricating a stable aqueous suspension drag reducer from polymers and to investigate its performance under crude oil pipeline conditions using Taylor-Couette setup. Suspensions of polyisobutylene (PIB), styrene butadiene rubber (SBR), and polystyrene (PS) were made by emulsification method and their stability and their behavior were eva‎luated using turbidimetry tests, zeta potential, rheological behavior, and etc. The turbidity eva‎luation results for PIB suspension showed that most of the samples still retained their turbidity after one day. SBR samples also showed acceptable stability after 7 days. The turbidity results for samples made of PS also indicated the relative stability of these samples. The zeta potential of all samples was between -40 to -70 mV and therefore, all samples were electrostatically stable. The frequency sweep test was performed for the most stable samples and through the measurement of the storage and loss modulus, the elastic behavior and viscosity of the suspentions were determined qualitatively. The results showed that the storage modulus of samples containing 2 g of PIB polymer, 0.45 g of surfactants and the ratio of co-surfactants of 0.66, and also containing 3 g of SBR polymer and 0.50 g of SLS and the ratio of co-surfactants 0.66 was always higher than their loss modulus. But for PS polymer suspension, the loss modulus was always higher than the storage modulus. Generally speaking, stability conditions (suspension without sedimentation, creaminess or flocculation) were achieved for a number of samples of all three polymers. A stable suspension sample of each polymer, in addition to a commercial suspension sample made in Iran, was separately added to Tehran refinery crude oil and the reduction in drag was eva‎luated. The reduction of the drag was strongly dependent on the rheological behaviors caused by different concentrations of the polymer in the crude oil. For samples where the loss factor diagram in terms of frequency was around the value of 1 and the phase angle was about 45°, the amount of drag reduction was higher. In addition, the operational conditions showed that the reduction of the drag up to an optimal concentration (about 15.0 ppm) is a function of increasing concentration and then decreases. An increase in angular velocity (flow turbulence) showed different results, but an increase in temperature to 15°C (from 25 to 40°C and then 55°C) caused more drag loss. The optimum amount of drag reduction occurred at 15.0 ppm concentration of PIB (~40%) and for SBR (~27%) at temperatures of 25, 40 and 55°C and Reynolds number of 300,000, where the drag reduction of the PIB sample was almost close to the maximum. The drag reduction for commercial sample was ~45%. PS suspensions showed the lowest amount of drag reduction (≤10%) among all samples. Viscous solid-like behavior and insufficient elasticity were interpreted as the reason for the lowest amount of drag reduction in this polymer.

تعليق پليمري، كاهش دهنده¬ درگ، جريان نفت خام در خط لوله، دستگاه ديسك چرخان، رئولوژي

Polymer Suspension, Drag Reducer, Crude Oil Flow in Pipeline, Rotating Disc Apparatus, Rheology

Zahra Dastbaz

Seyyed Nezameddin Ashrafizadeh