Dissertation/Thesis Abstract

Surfactant Effect on Hydrate Crystallization Mechanism
by Dann, Kevin, M.S., San Jose State University, 2017, 84; 10284664
Abstract (Summary)

Gas hydrates pose economic and environmental risks to the oil and gas industry when plug formation occurs in pipelines. A novel approach using interfacial rheology was applied to understand cyclopentane clathrate hydrate formation in the presence of nonionic surfactant to achieve hydrate inhibition at low percent weight compared to thermodynamic inhibitors. The hydrate-inhibiting performance of low (CMC) concentrations of Span 20, Span 80, Pluronic L31, and Tween 65 at 2 °C on a manually nucleated 2 μL droplet showed a morphological shift in crystallization from planar shell growth to conical growth for growth rates below 0.20 mm 2/min. Monitoring the internal pressure of a droplet undergoing planar hydrate crystallization provided a strong correlation (up to R = –0.989) of decreasing interfacial tension to the shrinking area of the water-cyclopentane interface. Results from the high-concentration batch of surfactants indicated that while initial hydrate growth is largely suppressed, the final stage of droplet conversion becomes rapid. This effect was observed following droplet collapse from the combination of large conical growths and low interfacial tensions. The low-concentration batch of surfactants saw rapid growth rates that diminished once hydrate shell coverage was completed. The most effective surfactant was the high-concentration Tween 65 (0.15 g/100mL), which slowed hydrate growth to 0.068 mm2/min, nearly an order of magnitude slower than that found for pure water at 0:590 mm2/min. High molecular weight (1845 g/mol) and HLB (10.5) close to 10 contribute to a large energy of desorption at an interface and are believed to be the sources of Tween 65's hydrate-inhibiting properties.

Indexing (document details)
Advisor: Rosenfeld, Liat
Commitee: Chang, Lilian, McNeil, Melanie
School: San Jose State University
Department: Engineering
School Location: United States -- California
Source: MAI 56/05M(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Chemical engineering, Petroleum engineering, Materials science
Keywords: Crystallization, Cyclopentane, Hydrate, Morphology, Rheology, Surfactant
Publication Number: 10284664
ISBN: 9780355068313
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