Contribution of Ultra-Fine Bubbles to Promoting Effect on Propane Hydrate Formation.

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Engineering

Background:

• Gas hydrates are crystalline solids formed from water and small gas molecules.
• Understanding hydrate formation is crucial for energy transport and storage.
• The "memory effect" in gas hydrates, where prior formation influences subsequent nucleation, is not fully understood.

Purpose of the Study:

• To experimentally investigate the effect of ultra-fine bubbles (UFBs) on propane hydrate formation.
• To determine the stability of UFBs in water under experimental conditions.
• To elucidate the mechanism behind UFB-induced hydrate formation and its relation to the hydrate memory effect.

Main Methods:

• Preparation of propane (C3H8) hydrate using UFB-infused water solutions.
• Two methods were used: using dissociated hydrate water and generator-prepared UFB-included water.
• UFB number density and stability were measured over time; hydrate nucleation probability and induction times were compared with and without UFBs.

Main Results:

• UFB number density remained significant (up to 10^9 mL^-1) for at least 2 days.
• Nucleation probabilities were approximately 1.3 times higher in UFB-containing water.
• Induction times for bulk hydrate formation were significantly shortened with UFBs.

Conclusions:

• High number density of UFBs in water demonstrably promotes propane hydrate formation.
• UFBs contribute to hydrate formation even in water without prior hydrate exposure.
• The findings support the gas dissolution hypothesis as a more likely explanation for the hydrate promoting effect.