Page 306 - Handbook Of Multiphase Flow Assurance

Experimental study of hydrate crystal growth 305

FIG. 10.64 Planar crystal of THF hydrate grown (a) with 0.5 wt% of high molecular weight PVP in solution at 1 °C
(supercooling of 3.4 K), and (b) with 0.1 wt% of high molecular weight PVP in solution at 3 °C (supercooling of 1.4 K).

In case of VC-713 inhibition at 3.4 K supercooling, the plane of hydrate did not grow
thicker. Instead, other planes and defects appeared on the surface of the original plane. With
VC-713 hydrate crystals simultaneously started to grow on sample tube glass walls without
the original crystal plane reaching the glass walls.
The problem of the two-dimensional growth is interesting because the plate perimeters
also appear to be {111} based on observing a thick hydrate plates which grew from a solution
with 0.1 wt% PVP of high molecular weight. However, at higher inhibitor concentrations in