Plug Formation

When ionic liquid acts as the carrier fluid (Fig. 4.10), the formation cycle was almost three times faster (Xf = 0.35 and formation frequency of 2.86 Hz) than the previous case. The break up point moves downstream and the dispersed medium 

4 liquid-liquid Flows in Micro and Small Channels. .. 

10 Phase averaged vector fields in the water for different stages of the aqueous plug formation, when ionic liquid is the carrier fluid. Twenty instantaneous fields per stage were averaged 

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Primary hemostasis is the first phase of hemostasis consisting of platelet plug formation at the site of injury. It occurs within seconds and stops blood loss from capillaries, arterioles, and venules. Secondary hemostasis, in contrast, requires several minutes to be complete and involves the formation of fibrin through the coagulation cascade. 

S. V. Kosyak, V. S. Danyushevskij, M. E. Pshebishevskij, and A. A. Trapeznikov. Plugging formation fluid transmitting channel— by successive injection of aqueous solution of polyacrylamide and liquid glass, buffer liquid and aqueous solution of polyacrylamide and manganese nitrate. Patent SU 1797645-A, 1993. 

T. Palermo, A. Sinquin, H. Dhulesia, and J. M. Fourest. Pilot loop tests of new additives preventing hydrate plugs formation. In Proceedings Volume, pages 133-147. 8th Bhr Group Ltd et al Multiphase 97 Int Conf (Cannes, France, 6/18-6/20), 1997. 

Following endothelial injury, vessel-wall response involves vasoconstriction, platelet plug formation, coagulation, and fibrinolysis regulation. In normal circumstances, platelets circulate in the blood in an inactive form. After injury, platelets undergo activation, which consists of (1) adhesion to the subendothelium,... 

Fig. 10 Illustration of the dosing-disk filling principle (A) view looking down on the dosing disk (B) side view (projected) showing progressive plug formation. Note the placement of strain gauges on the piston to measure tamping and plug ejection forces (see text). (From Ref. 37.)...

P Heda. A comparative study of the formulation requirements of dosator and dosing disc encapsulators. Simulation of plug formation, and creation of rules for an expert system for formulation design. PhD dissertation, University of Maryland, Baltimore, 1998. 

PK Heda, FX Muller, LL Augsburger. Capsule filling machine simulation I Low force compression physics relevant to plug formation. Pharm Devel Tech 4(2) 209-219, 1999. 

P Yeski, M Marvola. Design and use of equipment for simulation of plug formation in hard gelatin capsule filling machines. Acta Pharm Fennica 100 19-25, 1991. 

JR Britten, MI Barnett, NA Armstrong. Studies on powder plug formation using a simulated capsule filling machine. J Pharm Pharmacol 48 249-254, 1996. 

Shah KB, Augsburger LL, Marshall K. An investigation of some factors influencing plug formation and fill weight in a dosing disk-type automatic capsulefilling machine. J Pharm Sci 1986 75(3) 291-296. 

Dyadin et al. discover that H2 forms a clathrate hydrate at high pressures up to 1.5 GPa 2004 Camargo et al. and BP/SINTEF introduce cold flow concept to prevent hydrate plug formation without the need of chemical additives... 

The objective of this chapter is provide an overview of how solid masses of hydrates (plugs) form, means of preventing and encouraging plug formation, and means of dissociating plugs once they have formed. 

Figure 8.8 (See color insert following page 390.) Plug formation via aggregation in an oil-dominated system. (From Turner, D.J., Clathrate Hydrate Formation in Water-in-Oil Dispersions, Ph.D. Thesis, Colorado School of Mines, Golden, CO (2004). With permission.)...

Conceptual Overview Hydrate Plug Formation in Oil-Dominated Systems... 

In Figure 8.8 six steps are involved in hydrate plug formation ... 

As the hydrate deposition on the wall becomes thicker (Point C), narrowing of the flow channel occurs. The deposition forms irregularly (Point D) so that a nonconcentric annulus increases the pipeline pressure drop. Steps 1-3 are in the stages of hydrate plug formation marked early in the top of Figure 8.9, with a gradual upstream pressure increase. 

The five studies of hydrate formation given in Section 8.1 are of two types. The first three case studies show thermodynamic (time-independent) methods to prevent plug formation. However, the second type provides a closer, mechanistic look at the physical kinetics (time-dependent) hydrate formation and agglomeration. A goal of this section is to show how these two methods provide two different methods of plug prevention. 

Forty-six case studies of hydrate plug formation and remediation are recorded in Hydrate Engineering (Sloan, 2000). In every case, hydrate plugs were remediated. In addition, a rule of thumb is that most of the offshore flowline shut-ins are less than the 10 h no touch time, which requires no antihydrate operation before restart (J.E. Chitwood, Personal Communication, August 1, 2003). However, hydrate prevention methods are very expensive, as shown in the above Canyon Express and Ormen Lange examples, or in the fact that deepwater insulation costs are typically U.S.Sl million per kilometer of flowline. 

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