BURLA SAI KIRAN
Osmania University, Physics, Undergraduate
Immense gas hydrate reservoirs have been reported in the Krishna-Godavari Basin, India. They mostly constitute methane gas and could serve as an alternative energy source. For efficient exploitation of methane from hydrates, it is crucial... more
Immense gas hydrate reservoirs have been reported in the Krishna-Godavari Basin, India. They mostly constitute methane gas and could serve as an alternative energy source. For efficient exploitation of methane from hydrates, it is crucial to know the region's stability conditions. The present study reports the stability and equilibrium conditions of methane hydrates, synthesized with seawater obtained from the Krishna-Godavari Basin. At Station MD161/02/GH, the water samples are collected at depths ranging from 500 to 1,500 m. The influence of salinity on methane hydrate formation and dissociation in the presence of seawater is established. The hydrate dissociation patterns in seawater and saline water (4 wt% NaCl) are similar and follow the phase equilibrium around 6 wt% NaCl. The identical dissociation behavior of the two systems ascertains seawater to have ~4 wt% salinity. The salinity concentration varies little with depth because the hydrate dissociation temperatures are th...
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Abstract The molecular exchange is a frontline technology in the process of gas recovery from natural gas hydrate deposits. In such a case, the caged methane (CH4) molecules are exchanged with carbon dioxide (CO2). The process efficiency... more
Abstract The molecular exchange is a frontline technology in the process of gas recovery from natural gas hydrate deposits. In such a case, the caged methane (CH4) molecules are exchanged with carbon dioxide (CO2). The process efficiency depends on several factors, including pressure (p) and temperature (T) of the injected gas. There are quite a few conflicting views on the guest-guest exchangeability; mainly, it is unclear if the process is by molecular diffusion or by the reformation of hydrates. This study reports the replacement of CO2 by CH4 in primeval CO2 hydrates, below ice-melting temperature. Intuitively such a process is least preferred because CO2- hydrates are thermodynamically more stable than CH4- hydrates. We varied the injected gas (CH4) pressure in the range of 0.7–8.5 MPa. The co-existence of Raman signatures specific to caged CO2 & CH4 molecules supports the molecular replacement in virgin CO2 hydrates. Further, the diffusion of CH4 in both 51262 & 512 cages of sI hydrates offers a path for the mixed hydrate formation. Subsequently, the hydrate dissociation pattern also supports the rapid growth of mixed hydrates.
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Rapid and efficient methane hydrate conversions by utilising the water molecules confined in intra- and inter-granular space of silica powders.
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Abstract Gas recovery from the natural gas hydrate (NGH) deposits is a current topic of interest. Apart from the conventional thermal stimulation, depressurisation and chemical injection methods, the guest molecular replacement method in... more
Abstract Gas recovery from the natural gas hydrate (NGH) deposits is a current topic of interest. Apart from the conventional thermal stimulation, depressurisation and chemical injection methods, the guest molecular replacement method in hydrates offers dual advantage such as retention of their structural stability, and as a sink for carbon dioxide (CO2). However, the molecular exchangeability shows significant variance and the mechanism is also incomprehensible. This study is aimed at probing the stability of gas (CH4 & CO2) hydrates in the presence of CO2/CH4, N2 and their mixtures at low-pressure (~1.0 MPa) conditions. The selected experimental conditions help gain insight into the guest-guest exchange. Evaluation of gas pressure during the dissociation process indicates the presence of mixed hydrates. The micro-Raman investigations elucidate the occurrence of mixed hydrate seed crystals, encasing both CH4/CO2 molecules of initial hydrates, and also the molecules from the injected gas. The characteristic signatures of CH4 & CO2 molecules in hydrate systems broadly agree with the literature data, while that of N2 pointedly closer to the gas phase signature, indicating its role as a help-gas to promote replacement/rearrangement of guests in hydrate lattice.
Research Interests: Engineering and Elsevier
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This study reports methane (CH4) gas storage capacity along with TetraHydroFuran (THF) as guest molecules in mixed hydrates. This process has been studied in two reactors of 100 and 400 mL capacity, having 4.5 and 7.5 cm internal diameter... more
This study reports methane (CH4) gas storage capacity along with TetraHydroFuran (THF) as guest molecules in mixed hydrates. This process has been studied in two reactors of 100 and 400 mL capacity, having 4.5 and 7.5 cm internal diameter respectively, in non-stirred configuration. Experiments were conducted in each reactor at constant initial gas pressure (7.5 MPa) and by increasing the height of the solution from 1 to 8 cm, resulting in volume scale-up factor of 5. The total CH4 gas uptake (moles) passes through a maximum at around 50% volume of the reactor indicating a transition from gas-rich to solution rich conditions. Observed variations in gas uptake are within ±20% of the maximum, upon different solution volume from 35% to 70% of reactor’s volume. Another set of experiments were conducted keeping the amount of the solution constant and increasing gas pressure in the range of 0.5–11.0 MPa. The gas uptake increased upon an increase in the gas pressure, but this is at least 40...
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Research Interests: Engineering and Chemistry
Storage of greenhouse gases in the form of gas hydrates is attractive and is being pursued rigorously in recent times. However, slow formation rate and inefficient water to hydrate conversion are the main hindering factors. In this... more
Storage of greenhouse gases in the form of gas hydrates is attractive and is being pursued rigorously in recent times. However, slow formation rate and inefficient water to hydrate conversion are the main hindering factors. In this report, we examine the role of two amino acids (0.5 wt%), l-methionine (l-met) and l-phenylalanine (l-phe) on the formation of gas hydrates using methane (CH), carbon dioxide (CO) and their mixtures as guest molecules. Experiments are conducted under non-stirred and isochoric configurations. The hydrate conversion efficiency of both amino acids is identical for hydrates formed with CH and mixture of (CO+CH). However, the hydrate conversion is significantly less in CO hydrates in l-phe system. Addition of amino acids to the water dramatically improved the kinetics of hydrate formation and 90% of maximum gas uptake in hydrate phase occurred in less than an hour. The water to hydrate conversion is also very efficient (>85%) in the presence of amino acids....