Effect of surfactant carbon chain length on hydrate formation kinetics

Abstract

An experimental study was conducted on the effect of the addition of surfactants on hydrate formation kinetics. A series of surfactants with sodium sulfonic acid groups in common but with different carbon chain lengths (C4, C12, and C18) were tested, and the effects of the carbon chain length and concentration were systematically investigated. Hydrate formation rates were measured by a batch-type method with a high-pressure vessel made of stainless steel, with 100 mL inner volume, and the hydrate formation rate determined by the rate of pressure decrease caused by hydrate formation. The hydrate formation rate of xenon increased with the addition of the surfactants in the lower concentration range, and the acceleration showed a maximum at a certain concentration, but decreased with further concentration increases. For a given weight concentration, the surfactant with the shortest chain length (C4, butanesulfonic acid sodium salt) showed the highest acceleration (about 2.5 times larger than for pure water). The acceleration from the C4 surfactant was greater for methane hydrate formation, where the hydrate formation rate was about 5 times greater than that without surfactant. Energy saving potential was estimated when the C4 surfactant was applied to a natural gas transportation scenario in the form of hydrates; it was estimated that power consumption can be reduced by about 40% with the use of the C4 surfactant in the hydrate formation process.