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Gas hydrates have been proposed as a potential technology for a number of applications, such as separation of gas mixtures, CO2 capture, transportation, and sequestration, methane storage & transportation, and seawater desalination. Most of these applications will benefit from reduced induction time of hydrate nucleation, enhanced hydrate growth rate, and maximum water-to-hydrate conversion. The addition of surfactants to the gas–water system serves this purpose in a very effective manner. Our group studies the effect of different surfactants on gas hydrate formation kinetics; works carried out through molecular dynamics simulations shows possible mechanisms of action through which these surfactants affect hydrate formation kinetics. Enhanced rate of hydrate nucleation and growth kinetics may be linked to micelle formation, reduced surface tension in the presence of surfactants, and enhanced solubility of hydrate forming gases. Enhanced mass transfer and change in crystal morphology resulting in better gas–water interactions also contributes to faster growth kinetics.
Gas hydrates (Clathrates) are non stoichiometric, crystalline, inclusion compound formed by water and small gas molecules like methane, carbon dioxide or high volatile hydrocarbon like THF. The gas hydrates are formed when gas and water mixtures are subjected to high pressure and/or low temperature conditions. These conditions are frequently encountered in subsurface environments of deep sea sediments and permafrost regions. Thus methane and other natural gas hydrates are found stored in the earth in large quantities. High concentration of methane in natural gas hydrates are potentially a huge energy resource and puts it at par with other conventional fuel resource like coal and oil reservoirs. Thus developing methods for commercial production of natural gas hydrates is of enormous economic and strategic importance for India. Thanks to the efforts of NGHP program of Government of India, gas hydrates are known to occur in numerous marine environment around Indian offshore. Our research focus is to simulate hydrate formation in sediments at laboratory in order to develop potential recovery methods. Macro level experimental measurement for gas hydrate formation and decomposition kinetics to molecular level characterization of gas hydrate sample through different analytical techniques are routinely carried out in the group. Understanding of gas hydrate stability and kinetics is also done by employing molecular dynamic simulation. It is also of our interest to understand and develop suitable additives for promoting and inhibiting hydrate formation for different application.
Methane gas storage and transportation via clathrate hydrates is proposed to be a potential solution for large-scale energy storage. We intend to study the formation and decomposition kinetics of methane hydrates (MH) in a laboratory-scale unstirred crystallizer. Focus is also on enhancing the storage capacity by enhancing water to hydrate conversion. Moreover, we are also interested in studying the stability of hydrates and dissociation kinetics by measuring the rate of hydrate decomposition at different temperatures.
CO2 sequestration by hydrate formation in porous sediments is being looked upon in the group. Siliceous materials with high porosities like pumice and fire hardened red clay (FHRC), can be used as packing materials in a fixed bed setup to study hydrate formation kinetics. It was observed that pumice as the porous medium showed better hydrate formation kinetics resulting in 46 mol % water to hydrate conversion in 5 h. Moreover, kinetics was enhanced with decrease in the bed height of pumice; this suggests that at field scale adaptation of CO2 sequestration in geological formations, mass transfer limitations would be significant. The effects of particle size on hydrate formation kinetics were also investigated. It was observed that hydrate formation kinetics was enhanced with decrease in the particle size fraction.
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