Liquid slugs

Warped bedplate, compressor, or 15. Liquid "slugs" striking wheels. 

Liquid Overflow Inflow exceeds outflow Liquid slug How Blocked or restricted liquid outlet Level control system failure High liquid level... 

These units cannot handle liquid slugs or dirt particles hence, they require gas/vapor cleaning before entering the unit. For units with cooling jackets and automatic temperature regulation of the process gas, the temperature can range as high as 302°F [20]. 

In vertical flow, axial symmetry exists and flow patterns tend to be somewhat more stable. However, with slug flow in particular, oscillations in the flow can occur as a result of sudden changes in pressure as liquid slugs are discharged from the end of the pipe. 

If air is injected so that the mixture velocity is increased to buL, then the total length of liquid slugs in the pipe will be (1 /b)l. Then, neglecting the pressure drop across the air slugs, the two-phase pressure drop — APTp will be given by ... 

Slug/semi-annular flow. Here both slug and semi-annular flows were present. The vapor velocity increased with the heat flux and the rear of elongated bubbles began to break up (Fig. 2.30d). Coalescence was no longer clean and created a churn-like zone where the liquid slug had been. 

Semi-annular flow. Liquid slugs were non-existent (Fig. 2.30e). A liquid film formed at the tube wall with a nearly continuous central vapor core, truncated periodically by churning liquid-vapor zones, which disappear gradually. 

At relatively low liquid superficial velocities, increasing the mixture volumetric flux led to longer bubbles and shorter liquid slugs, eventually leading to the merging of elongated bubbles, and the development of the slug-annular flow pattern, repre-... 

At a given flow condition, different flow patterns were observed which can be classified into five distinct patterns depending on the interfacial configuration liquid alone (or liquid slug), gas core with a smooth thin liquid film, gas core with a smooth thick liquid film, gas core with a ring-shaped liquid film, and gas core with a deformed interface. 

For all flow conditions tested in that study, a bubbly flow pattern with bubbles much smaller than the channel diameter (100 pm) was never observed. While liquid-only flows (or liquid slugs) containing small spherical bubbles were not observed, small droplets were observed inside gas core flows. Furthermore, no stratified flow occurred in the micro-channel as reported in previous studies of two-phase flow patterns in channels with a diameter close to 1 mm (Damianides and Westwater 1988 Fukano and Kariyasaki 1993 Triplett et al. 1999a Zhao and Bi 2001a). 

Interphase mass transfer between liquid-liquid slugs... 

Slug flow can be subdivided into two main parts (Fig. 3.34) a liquid slug zone of length is, and a film zone of length if. The liquid slug zone can be aerated by dispersed bubbles, with a liquid holdup, Rs. As the gas starts to penetrate through... 

Note that the average void fraction of a slug unit depends only on the liquid and gas flow rates, the dispersed velocity ub, the translational velocity w, and the void fraction within the liquid slug, a, and it is independent of the bubble shape or bubble length, the liquid slug length, as well as the film thickness in the film zone (Barnea, 1990). 

The acceleration loss, Apa, results from the force needed to accelerate the liquid in the film around the Taylor bubble from its velocity, ULTB, to that of the liquid slug, ULLS. 

The frictional pressure gradient in the liquid slug can be calculated using Eqs. (3-103) and (3-104), when the flow rates of liquid and gas are written in terms of the flow rate on the slug. Thus,... 

Barnea, D., and N. Brauner, 1985, Holdup of the Liquid Slug in Two-Phase Intermittent Flow, Int. J. Multiphase Flaw 77 43-49. (3)... 

Dukler, A. E., and M. G. Hubbard, 1975, A Model for Gas-Liquid Slug Flow in Horizontal and Near Horizontal Tubes, Ind. Eng Chem. Fundam. 14(4) 337. (3)... 

Fig. 10. Top images Improved flow distribution of the liquid-liquid slug flow at 80°C and 5 bar at the reactor inlet (left) and the reactor center (right). Less regular flow distribution of the liquid-liquid slug flow at 20°C and 1 bar at the reactor inlet (left) and the reactor centre (right)...

Where relief valves are provided on liquid storage tanks or vessels, where there is a possibility of liquid release, i.e., liquid slug, careful evaluation of the release disposal system (e.g., flare header) needs to be undertaken. In some cases, a liquid slug may block a header from releasing pressure and defeat the purpose of the pressure release system. 

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