Methane hydrate production using a novel spiral‐agitated reactor: Promotion of hydrate formation kinetics

Abstract

To enhance hydrate formation kinetics, we presented a novel spiral‐agitated reactor, where hydrates were synthetized in pure water systems, and fast hydrate kinetics was observed under extremely mild conditions. Hydrates can nucleate within 4 min under 3.5 MPa and 275.15 K at a rotating speed of 60 rpm, and large water‐to‐hydrate conversion (>85%) was obtained at a moderate condition of 4.85 MPa, 275.15 K, and 30 rpm with an average methane uptake of 139.78 V/V, demonstrating that pure water systems are feasible for hydrate‐based solidified natural gas (SNG) technology. Numerical simulations of flow fields inner the reactor were carried out, and four mechanisms behind the excellent promotion were proposed, dual‐agitation, two‐way convection, interfacial impact and micro bubbles, which significantly improve mass transfer, giving rise to fast hydrate nucleation and growth kinetics. These findings suggest extraordinary performance of spiral agitation, and this may pave way on the industrial application of hydrate‐based SNG technology.

Enhanced hydrate formation under mild conditions using a novel spiral‐agitated reactor

“…Therefore, fast growth of hydrates under mild conditions suggests the premise to realize the industrial application of hydrate‐based SNG technologies, while considerable gas storage should also be available. Keep this in mind, we proposed a novel spiral‐agitated reactor recently, and it was found that spiral agitation can induce fast hydrate nucleation even under extremely mild conditions 40 . In this work, hydrate formation kinetics in the spiral‐agitated reactor was further evaluated, and exciting findings were obtained.…”

“…Keep this in mind, we proposed a novel spiral-agitated reactor recently, and it was found that spiral agitation can induce fast hydrate nucleation even under extremely mild conditions. 40 In this work, hydrate formation kinetics in the spiralagitated reactor was further evaluated, and exciting findings were obtained. The promotion of spiral agitation on hydrate formation was first investigated in pure water, and enhanced hydrate formation was observed under low revolving speeds.…”

The synergy of spiral agitation and nano-promoters significantly enhances hydrate formation under mild conditions

“…A novel spiral-agitated reactor was used, the schematic diagram of which is presented in Figure S1, and more details can be found in our previous publications 24,35 . The high-pressure reactor is composed of a stainless-steel cylinder and a stirring rod, and the effective volume of the reactor is 581.71 mL.…”

“…The storage capacity is close to 70 V/V at 3.8 MPa, while it goes up to 139.54 V/V and 144.54 V/V at 5 MPa for the inclined angle of 35°and 45°, respectively, and water-to-hydrate conversion is more than 85%. Besides, it is worth noting that the convection 35 of liquid phase inner the spiral-agitated reactor intensifies with the increase in the inclined angle, so the mass transfer between gas and liquid is enhanced at large inclined angle, leading to the increase in conversion, but when the driving force was feeble, this effect was inconspicuous.…”

“…Recently, we proposed a novel spiral-agitated reactor 35 , and fast hydrate nucleation was observed in pure water. Hydrate induction time is less than 4 min at 3.5 MPa and 60 rpm, suggesting excellent promotion of spiral agitation on hydrate nucleation, and this also guarantees fast hydrate growth rate in the original agitation stage.…”