Predict and prevent air entrainment in draining tanks. The proper use of vortex breakers at tank outlets can prevent entrained vapors from flowing downstream

You are here: Homepage > Search

Predict and prevent air entrainment in draining tanks. The proper use of vortex breakers at tank outlets can prevent entrained vapors from flowing downstream

Rochelle, Steve G. / Briscoe, Marvin T. jun.

During tank draining a potential for a swirling vortex can exist, which can entrain air or gases into the discharge flow. Problems such as vacuum collapse of the tank, over-pressurization of the receiving tank or a failure of the vapor seal between the tanks can result. The formation of vortexes can be blocked or prevented by using a vortex breaker. A variety of such breakers is known. For example the vortex breaker from Process Industries Practices comprises a baffle arrangement, either a flush with the bottom of the tank or suspended just off the tank bottom. Another designs rely on a circular plate for tanks with bottom drainage, a square top grating, a square section of grating, a 4-blades cross-pattern on top of a nozzle, extended above the tank bottom, a circular plate suspended above the tank bottom plus an 'X-bar' shape to form the 4-bladed cross-pattern, a combination of a 2-bladed and a 4-bladed cross-pattern and a horizontal top plate made from solid or porous grating. Rotonics Manufacturing shows an anti-siphon device for side-exit nozzles. Plotting the Froude number versus the H/D-ratio (H = height or depth of the liquid's free surface over an exit pipe's entrance, D = the exit pipe diameter) enables to distinguish between the locations of self-venting, vapor-entrainment and no-entrainment/runs full and to predict when a vortex breaker is needed to prevent vapor entrainment. Using data from an actual tank it is possible to block out the three operating ranges mentioned above as a function of different liquid heights and flow rates. With the help of this Froude number-H/D plot the user can evaluate conditions under which the risk of vapor entrainment can occur.

Access

Access via TIB

Check availability in my library

Order at Subito €

Export, share and cite

Document information

Title :

Predict and prevent air entrainment in draining tanks. The proper use of vortex breakers at tank outlets can prevent entrained vapors from flowing downstream

Additional title:

Vorhersage und Verhinderung des Lufteintrags beim Tankentleeren. Die angemessene Verwendung von Wirbelbrechern an Tankauslässen kann mitgeführte Dämpfe davon abhalten, abwärts zu strömen

Contributors:

Rochelle, Steve G. (author) / Briscoe, Marvin T. jun. (author)

Published in:

Chemical Engineering, New York ; 117 , 12 ; 37-43

Publication date :

2010

Size :

7 Seiten, 11 Bilder, 1 Tabelle, 30 Quellen

ISSN :

0009-2460

Type of media :

Article (Journal)