Dehydrating gas by using clathrate hydrates

Abstract

In this study, an approach to utilize hydrates in a positive perspective by using them to dehydrate the gas stream was investigated. Tetrahydrofuran (THF) and water was applied as the model system to examine the dehydration capacity of the gas hydrates. Simple laboratory setups were built to conduct a series of experiments.THF solutions that were prepared for the dehydration experiments were of two types: stoichiometric (21 vol% THF) and supersaturated (30 vol%, 40 vol% and 60 vol% THF). Hydrate crystal layers and hydrate slurry were formed from these solutions and were utilized to dehydrate the wet gas stream which was composed of water saturated nitrogen gas. The effect of the addition of salt and an oil phase in the hydrate particles were also examined. Moreover, the affinity of the nitrogen towards the water molecules in the hydrate slurry was inspected. This was done by bubbling the dry nitrogen through the slurry. To quantify the moisture in the gas stream before and after the dehydration, a dew point meter was used.The results showed that gas dehydration was possible when the hydrate concentration was more than 30 vol%. The addition of 3 wt% NaCl in the water phase did not improve the gas dehydration while the addition of an oil phase added moisture in the gas. In addition, the nitrogen gas showed strong affinity towards the water molecules in the slurry.