Fig. 5-Schematic diagram of Anti-agglomerants affecting hydrate
bridge in pure water system
3.2 Effect of initial flow rate on flow characteristics. The
flow curves of hydrate slurry under different initial flow rates in pure
water system were showed in Fig. 6 . The flow characteristics of
hydrate slurry under the initial flow rates of 230 L / h, 380 L / h and
550 L / h were investigated. The stable flow time of hydrate slurry was
23 min, 25 min and 30 min, respectively. Obviously, increasing the
initial flow rate can significantly prolong the plugging time of hydrate
slurry. From the perspective of hydrate nucleation, this may be due to
the inhibition or delay of hydrate nucleation caused by high shear,
which makes it difficult to reach the critical size required for hydrate
formation. Moreover, high flow rate increases the flow friction ( heat
generated ), weakens the cooling effect of temperature control system,
inhibits the nucleation and growth of hydrate in the pipeline
transportation system, and thus prolongs the induction period of
hydrate. From the perspective of hydrate plugging mechanism,
high-velocity fluid can not only destroy the formed hydrate polymer, but
also reduce the probability of coalescence between hydrate particles,
which greatly reduces the risk of plugging. Excessive flow velocity also
increases the wall shear rate, making it difficult for hydrate particles
to adhere to the wall. Hydrate deposition on the wall surface can reduce
the flow area of slurry, so the flow shear rate of the deposition
surface increases rapidly during hydrate deposition. When the surface
flow shear rate reaches the critical point, the sediment will begin to
fall off.