Effect of SDS/THF on thermodynamic and kinetic properties of formation of hydrate from a mixture of gases (CH4+C2H6+C3H8) for storing gas as hydrate

In this work, the effect of sodium dodecyl sulfate (SDS) and combined effect of sodium dodecyl sulfate (SDS) and tetrahydrofuran (THF) on thermodynamic and kinetic properties of CH4+C2H6+C3H8 hydrate formation have been studied. Four different concentrations of sodium dodecyl sulfate (100 ppm, 500 ppm, 1000 ppm and 1500 ppm) have been used to see its effect on phase equilibrium condition and formation kinetics. Though sodium dodecyl sulfate (SDS) does not vary the pressure–temperature condition of hydrate formation, it has a prominent favorable effect on induction time, gas consumption, storage capacity and formation rate. The addition of 3% (mol) tetrahydrofuran (THF) to water + SDS system results in large shifts in phase equilibrium boundary to lower pressure and higher temperature. It has been noticed that the addition of tetrahydrofuran further enhances the formation rate. So the mixture of sodium dodecyl sulfate (SDS) and tetrahydrofuran (THF) can be effectively used as promoter for storing natural gas as hydrate.

The figure shows the amount of gas consumed during hydrate formation in pure water, water+SDS and water+SDS+THF systems. Addition of 1500 ppm SDS to water increases the gas consumption by almost 1.9 times with respect to pure water system. It is also noticed that addition of 3% (mol) THF to the water+1500 ppm SDS system further increases the gas consumption up to 4 times with respect to pure water.Figure optionsDownload as PowerPoint slide