Abstract
This study reports the visual observation on the growth and formation of clathrate hydrate crystals in the stream of flowing liquid water presaturated with methane gas. Experimental apparatus used in the present study is devised by inserting a porous pipe inside the reactor thereby allowing the hydrate crystals to form and grow in the liquid water stream. The morphology of methane hydrate crystals grown in liquid water stream varied depending on the system subcooling temperature, ΔT_<sub> . ΔT_<sub> is defined as the difference between equilibrium temperature of the hydrate, T_<eq> and system temperature, T_<ex>. The crystal growth in the bulk of liquid water was observed when ΔT_<sub> > 4.5 K. When ΔT_<sub> is in the range of 4.5 K - 9.0 K, polygonal flat plate crystals were observed growing from the porous pipe surface. At 9.0 K to 10.0 K, the crystal morphology enters the transition phase, where the polygonal flat plate crystals started to change into dendritic crystals. When the subcooling temperature, ΔT_<sub> is greater than 10.0 K, polygonal crystals were completely replaced by the dendritic crystals. On the basis of these observation results, continuous supply of the guest substance will enhance the growth of methane hydrate as the crystals formed in the present study were larger in terms of particle size compared to the previous study. (Ohmura et al., Crystal Growth Design, 5(3), 2005.)
