Effect of Molar Ratio of Counter-Ions to Cationic Surfactants Treating Trimethylolethane Hydrate Slurries

Abstract

Experimental studies on flow characteristics and particle size distributions of trimethylolethane (TME) hydrate slurries treated with drag-reducing surfactants have been conducted to investigate the effect of the molar ratio of counter-ions to surfactants. Oleylbishydroxyethylmethylammonium chloride is used as the drag-reducing surfactants. The molar ratio of sodium salicylate supplying counter-ions to surfactants is adjusted from 0 to 100 while the concentrations of TME in water and of surfactants remains constant at 25 wt% and at 2000 ppm, respectively. Results unexpectedly indicate that the drag reduction is greatest when the molar ratio of the counterions to surfactants is 20 against the fact that the higher molar ratio shows the higher drag reduction in water case. This indicates that some interaction between the counter-ions and TME molecules occurs and that it disturbs the formation of rod-like micellar structures causing the drag reduction. Thus, a molar ratio of counterions to surfactants of 20 is concluded to be the optimum for the drag reduction although it has a detrimental effect on the particle size under the present experimental conditions used.