The vortex breaker

In this design, vertical baffles are used to break the vortex. The number of baffles used depends on the nozzle diameter. Table 3.11 is often used as a preliminary guideline to design a vortex breaker. The position of fhe draw nozzle is also important a vessel-flushed nozzle may not be always recommended, particularly if the incoming fluid contains inert or gummy material. The internal nozzle projection (50 to 100 mm) is often used to avoid draining of solids along with the liquid stream. 

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Vortex Breaker A desnce located inside a vessel at the outlet connection. Generally consisting of plates welded together to form the shape of a cross. The vortex breaker prevents cavitation in the liquid passing through the outlet connection. 

The pressure drop (top LHS of Fig. 2.1) depends on the diameter, length and type of pipe and fittings, the elements for process control, the configuration, the velocity and the layout for NPSH. The latter, NPSH, depends on the vapor pressure, the temperature, the design of the vortex breaker, the NPSH required by the pump, the vertical component of the configuration. The resultant pressure drop expressed as a function of the volumetric flowrate summarizes the system needs. 

I have a personal dislike of this widely used device. The idea of the vortex breaker is to prevent swirling liquid from conveying vapor into the draw-off nozzle. Sometimes though, trash lost in the tower during a turnaround gets caught on the vortex breaker. Since the draw nozzle typically is located in a sump below the seal pan, it may be hard to inspect. In some cases, it would be best to just cut off the vortex breaker. This is fine if the nozzle exit velocity is less than 3 or 4 ft/s. 

If you must use a vortex breaker, please consult my book. Process Design for Reliable Operations, to see how one can design a draw-off sump to prevent the vortex breaker from fouling. 

The vortex breaker is used in almost all liquid-draw nozzles. There are several types of vortex breakers used the most common one is shown as Figure 3.7. 

The pump may have formed a vortex at high flow rates or low liquid level. Does the vessel have a vortex breaker Does the incoming flow cause the surface to swirl or be agitated ... 

Reentrainmeut from the bottom of the cyclone can be prevented in several ways. If a typical long-cone dry cyclone is used and hquid is kept continually drained, vortex entrainmeut is uuhkely. However, a vortex breaker baffle in the outlet is desirable, and perhaps a flat disk on top extending to within 2 to 5 cm (0.8 to 2 in) of the walls may be... 

When the pressure relief device is set to open at greater than 15 psig (critical flow will result), it is normally not uecessaiy to be concerned about the pressure drop in the separator. If the hquid is to be drained from the separator during the emergency blowdown, a vortex breaker and false bottom should be used (Fig. 26-18, view BB). 

A vortex breaker should be provided for the vessel drawoff nozzle. Kern shows some types. 

As liquid flows out of the exit nozzle, it will swirl and create a vortex. Vortexing would carry the gas out with the liquid. Therefore, all liquid outlet nozzles should be equipped with a vortex breaker. Figure 12-0 shows several vortex breaker designs. Additional designs can be found in the Pressure Vessel Handbook. Most designs depend on baffles around or above the outlet to prevent swirling. 

The unit shown in Figure 4-49 has been used in many process applications with a variety of modifications [18,19,20]. It is effective in liquid entrainment separation, but is not recommended for solid particles due to the arrangement of the bottom and outlet. The flat bottom plate serves as a protection to the developing liquid surface below. This prevents re-entrainment. In place of the plate a vortex breaker type using vertical cross plates of 4-inch to 12-inch depth also is used, (Also see Reference [58].) The inlet gas connection is placed above the outlet dip pipe by maintaining dimension of only a few inches at point 4. In this type unit some liquid will creep up the walls as the inlet velocity increases. 

The sizing procedure is presented in Guidelines for Pressure Relief and Effluent Handling Systems (AIChE-CCPS, 1998). Figure 23-53 shows the dimensions of a cyclone separator designed in accordance with this procedure. If liquid is continuously drained from the cyclone to a separate accumulator, a vortex breaker and false bottom should be used (Fig. 23-53, view BB). 

Vortex breeker. It is normally a good idea to include a simple vortex breaker, as shown in Fig. 8, to prevent a vortex from developing when the liquid control valve is open. A... 

An associated problem concerning a water-dump-valve vortex reaching up into the interface can also cause oily effluent water even if the Interface is clear. This can be eliminated by the installation of a vortex breaker installed over the interior of the outlet. 

Many draw nozzles, especially those in the bottom of vessels, plug because of the presence of vortex breakers. Many designers routinely add complex vortex breakers to prevent cavitation in pumps. But vortex breakers are needed only in nozzles operating with high velocities and low liquid levels. Corrosion products, debris, and products of chemical degradation can more easily foul and restrict nozzles equipped with vortex breakers. 

The submergence of suction line water intakes in the basin should be such as to avoid vortex formation and, consequently, air entrainments. Figure 7.1 provides recommended minimum submergence depths for different fluid velocities. In some cases it may be impractical to adhere to these velocity limitations, and higher suction velocities must be accepted. In such cases, a vortex breaker can be employed (Figure 7.2). 

Bottom liquid outlets. Sufficient residence time must be provided in the bottom of the column to separate any entrained gas from the leaving liquid. Gas in the bottom outlet may also result from vortexing or from forthing caused by liquid dropping from the bottom tray (a waterfall pool effect). Vortex breakers are commonly used, and liquid-drop height is often restricted. Inadequate gas separation may lead to bottom pump cavitation or vapor choking the outlet line. 

Accumulators are not separators. In one application, an acciunulator placed after a total condenser provides reflux to a fractionator and prevents column fluctuations in flow rate from affecting downstream equipment. In this application the accumulator is called a reflux drum. A reflux drum is shown in Figure 6.3. Liquid from a condenser accumulates in the drum before being split into reflux and product streams. At the top of the drum is a vent to exhaust noncondensable gases that may enter the distillation column. The liquid flows out of the drum into a pump. To prevent gases from entering the pump, the drum is designed with a vortex breaker at the exit line. 

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