Hydrate Composite Particles for Ocean Carbon Sequestration: Field Verification

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• 作者：Costas Tsouris ; Peter Brewer ; Edward Peltzer ; Peter Walz ; David Riestenberg ; Liyuan Liang ; and Olivia R. West
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：April 15, 2004
• 年：2004
• 卷：38
• 期：8
• 页码：2470 - 2475
• 全文大小：514K
• 年卷期：v.38,no.8(April 15, 2004)
• ISSN：1520-5851

文摘

This paper reports on the formation and dissolution ofCO₂/seawater/ CO₂ hydrate composite particles producedduring field experiments in Monterey Bay, CA using a CO₂injector system previously developed in the laboratory.The injector consisted of a coflow reactor wherein waterwas introduced as a jet into liquid CO₂, causing vigorousmixing of the two immiscible fluids to promote the formationof CO₂ hydrate that is stable at ambient pressures andtemperatures typical of ocean depths greater than~500 m. Using flow rate ratios of water and CO₂ of 1:1and 5:1, particulate composites of CO₂ hydrate/liquid CO₂/seawater phases were produced in seawater at depthsbetween 1100 and 1300 m. The resultant composite particleswere tracked by a remotely operated vehicle system asthey freely traveled in an imaging box that had no bottomor top walls. Results from the field experiments wereconsistent with laboratory experiments, which wereconducted in a 70 L high-pressure vessel to simulate theconditions in the ocean at intermediate depths. The particlevelocity and volume histories were monitored and usedto calculate the conversion of CO₂ into hydrate andits subsequent dissolution rate after release into the ocean.The dissolution rate of the composite particles wasfound to be higher than that reported for pure CO₂ droplets.However, when the rate was corrected to correspond topure CO₂, the difference was very small. Results indicate thata higher conversion of liquid CO₂ to CO₂ hydrate isneeded to form negatively buoyant particles in seawaterwhen compared to freshwater, due primarily to the increaseddensity of the liquid phase but also due to processesinvolving brine rejection during hydrate formation.