Evaluation of mass transfer characteristics of gas molecules during hydrate formation by using dimensionless numbers

Abstract

The mass transfer characteristics of gas molecules during hydrate formation by bubbling gas were evaluated using dimensionless numbers. First, the mass-transfer coefficient K_L and the specific surface area a of a gas–liquid were evaluated from hydrate formation with the gas mixture in a rising-bubble-type hydrate-based gas separation system. Based on the results, the mass-transfer characteristics during hydrate formation were expressed by dimensionless numbers. It was clear that the Sherwood number during hydrate formation, Sh_g,hy, could be evaluated by Sh (Sherwood number), Sc (Schmidt number), Ga (Galilei number) and Bo (Bond number), and γ (the inhibition ratio at the gas-liquid interface). During hydrate formation, the value of γ in pure water was 58.9 %. As the sodium dodecyl sulfate was added, the values of Sh_g,hy increased. The values of γ in the SDS aqueous solution systems were calculated to be 41.4 % at 100 ppm SDS and 9.50 % at 300 ppm SDS. This result suggested an increase in the area of the effective gas-liquid interface for mass transfer by adding the surfactant.