The use of a hydrate-based
technology in seawater desalination
is an interesting potential hydrate application since salt ions would
be excluded from the hydrate crystal lattice. In order to better understand
the hydrate-based desalination process, experiments have been conducted
using cyclopentane (CyC5, sII) hydrates, which can be formed at atmospheric
pressure and temperatures below 7.7 °C. The hydrate formation
experiments were performed at various subcoolings for aqueous solutions
with different salinities in a bubble column. The hydrate formation
times decreased and the hydrate conversion increased with increasing
subcooling and agitation. Various hydrate-former injection methods
were studied, with the most effective method involving spraying finely
dispersed CyC5 droplets (around 5 μm in diameter) into the water-filled
bubble column. The latter method resulted in a 2-fold increase in
seawater conversion to hydrate crystals compared with injecting millimeter-scale
CyC5 droplets. A desalination efficiency of 81% (the salinity decreased
from 3.5 to 0.67 wt %) was achieved by using a three-step separation
method, including gravitational separation, filtration, and a washing
step. Washing the hydrate sample using filtered water decreased the
salinity from 1.5 wt % in the solid hydrates before washing to 1.05
wt % after washing
