Hydrate formation and particle distributions in gas–water systems

Crystal growth phenomena of CH4 + C3H8 + CO2 ternary gas hydrate systems

“…The previous methane-water tests reported by Akhfash et al (2013) and Aman et al (2015) were performed without measurements of motor torque: F transition was previously identified through a combination of visual observations, hydrate growth rate, and measurements of the motor current required to maintain a constant mixing velocity. While measurements of motor current provided insight into the resistance-to-flow generated by the hydratein-water dispersion, the signal-to-noise ratio was low compared to measurements of the motor torque.…”

“…As the system was operated isochorically, the cell pressure decreased with temperature; hydrate nucleation was identified by a sharp decrease in cell pressure that deviated from the isochoric cooling curve, and was confirmed visually in each experiment. As discussed by Akhfash et al (2013) and Aman et al (2015), the sapphire cell and stainless steel enclosure exchange heat effectively with the glycol bath. As a consequence, hydrate formation typically increased the cell temperature by less than 0.2 K during the first hour of growth, which was readily corrected by the PID algorithm.…”

“…Laboratory studies by Akhfash et al (2013) and Aman et al (2015) provided further insight to the nature of F transition , which was observed to increase with the degree of mixing in a sapphire autoclave. That is, increasing turbulence allowed the aqueous phase to maintain additional hydrate in a homogeneous suspension; a similar increase in F transition was observed when monoethylene glycol (10 wt%) was added to the aqueous phase.…”

“…Ward et al / Journal of Natural Gas Science and Engineering xxx (2016) 1e9 process is given by Akhfash et al (2013). After the cell pressure and temperature reached steady state and the primary hydrate growth period ceased, the system was heated at a rate of 2 K/hr to 20 C to dissociate all hydrate.…”

“…Gas hydrate was formed in a high-pressure sapphire visual autoclave apparatus, described in detail by Akhfash et al (2013). The apparatus consisted of DB Robinson-type sapphire cell (150 mm length, 38.2 mm outer diameter, 12.8 mm wall thickness), in which fluids were mixed by a vane-and-baffle geometry impeller that was magnetically coupled to a Groschopp direct-drive DC motor capable of providing up to 1750 RPM (Fig.…”