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Title: Increasing Gas Hydrate Formation Temperature for Desalination of High Salinity Produced Water with Secondary Guests

Journal Article · · ACS Sustainable Chemistry & Engineering
DOI:https://doi.org/10.1021/sc400160u· OSTI ID:1127501

We suggest a new gas hydrate-based desalination process using water-immiscible hydrate formers; cyclopentane (CP) and cyclohexane (CH) as secondary hydrate guests to alleviate temperature requirements for hydrate formation. The hydrate formation reactions were carried out in an isobaric condition of 3.1 MPa to find the upper temperature limit of CO2 hydrate formation. Simulated produced water (8.95 wt % salinity) mixed with the hydrate formers shows an increased upper temperature limit from -2 °C for simple CO2 hydrate to 16 and 7 °C for double (CO2 + CP) and (CO2 + CH) hydrates, respectively. The resulting conversion rate to double hydrate turned out to be similar to that with simple CO2 hydrate at the upper temperature limit. Hydrate formation rates (Rf) for the double hydrates with CP and CH are shown to be 22 and 16 times higher, respectively, than that of the simple CO2 hydrate at the upper temperature limit. Such mild hydrate formation temperature and fast formation kinetics indicate increased energy efficiency of the double hydrate system for the desalination process. Dissociated water from the hydrates shows greater than 90% salt removal efficiency for the hydrates with the secondary guests, which is also improved from about 70% salt removal efficiency for the simple hydrates.

Research Organization:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research; National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States)
Sponsoring Organization:
USDOE Office of Fossil Energy (FE)
OSTI ID:
1127501
Report Number(s):
A-NETL-PUB-007
Journal Information:
ACS Sustainable Chemistry & Engineering, Vol. 1, Issue 10; ISSN 2168-0485
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English