Synergistic promotion mechanisms
As mentioned above, hydrate growth kinetics is significantly enhanced by
the synergistic effect of spiral agitation and nano-promoters under mild
conditions.
Since methane uptake rate corresponds to hydrate kinetics, its variation
under different conditions was analyzed, and the schematic diagram of
methane uptake rate for different scenarios were
given
in Figure 5(a). For high pressure (5 MPa), the rate curve is divided
into two sections, a fast uptake stage with stirring (Stage I) and a
slow uptake stage for hydrate static formation (Stage II).
In
comparison, it is clear from Figures 5(b) and 5(c) that the rate
profiles can be divided into three stages at 3.8 MPa. An initial stage
for hydrate stable growth (Stage I), following by a hydrate quick growth
stage (Stage II), and finally a hydrate slow growth stage occurs under
static condition (Stage III). In addition, compared with pure water and
-COO-@PSNS systems, an obvious “secondary uptake”
stage appears in -SO3-@PSNS systems as
seen in Figure 5(c).