ISSN: 2578-4846
Authors: Sai Kiran B, Rama Rao G and Prasad PSR*
Gas clathrates or the gas hydrates are the solid ice particles encapsulating gas molecules (commonly methane - CH4 and carbon dioxide - CO2) within the water cavities, at moderately high-pressure and low-temperature conditions. The petroleum extraction process from the deep-sea environment favours the occurrence of hydrates, and CO2 hydrates require milder p, T conditions than CH4 hydrates. Thus, chocking the pipeline network and obstructing the petroleum flow; leading to a substantial economic loss and hazardous. Conventional hydrate inhibitors (methanol, ethanol, glycols, Amino acids, and ionic liquids, etc.) are used, which are chemically toxic, costly, and required in large volumes (30-50 wt %). Therefore a suitable additive preventing plug formation is on high demand. The present study disclosures the use of three green leaf extracts Azadirachta indica (Neem - NL), Piper betel (betel - BL), and Nelumbo nucifera (Indian lotus - LL) in low dosage (0.5 wt %) on the CO2 hydrate formation. Experiments are conducted in the isochoric method, with 0.5 wt % green-additives. The hydrates nucleate at higher subcooling (̴ 7-9 K), and the conversion is about ̴ 33-40 %. The induction time is nearly the same both pure- H2O and H2O with LL, whereas, it is ̴3 and 4 times higher for NL and BL. The hydrate growth kinetics also indicate significant retardation (2 – 4 times). Thus, these bio-additives, in low-dosage, could be an effective THI and also KHI for preventing the CO2 hydrates plugs.
Keywords: CO2 hydrates; Flow assurance; Low dosage; THI; KHI; Bio-additives
