8 replies to this topic

[J_Leo]

Dear all,

I have a question regarding the criteria for the usage of vortex breakers in drums.
Do we always need a vortgex breaker at the liquid outlet if it is at the suction of a pump? What if there is no pump in the downstream?

Thank you in advance for any inputs.

Regards,
Leo

Edited by J_Leo, 23 March 2012 - 09:28 AM.

[kkala]

I have a question regarding the criteria for the usage of vortex breakers in drums.
Do we always need a vortgex breaker at the liquid outlet if it is at the suction of a pump? What if there is no pump in the downstream?

1. There is no need of vortex breaker in case that LLLL is high enough to exclude vortex formation. See http://www.cheresour...or-suction-pipe and http://www.cheresour...op-storage-tank '> http://www.cheresour...op-storage-tank , point (β). Required submergence for drums to avoid vapor intrusion is same as for open tanks to avoid air intrusion.
Besides vortex breaker may have risk of plugging and needs "cleaning" from time to time.
2. I think vortex breakers are more usual in horizontal drums, where every cm of liquid height represents a rather big volume of capacity; especially when risk of plugging does not exist. E.g. we have always specified vortex brakers in deaerator surge drums.
3. If there is no pump downstream, no vortex breaker seems necessary, since vapor intrusion will not cause cavitation. However, in case of air above the drum liquid directed to another drum also collecting a flammable liquid, a safety assessment should be made.
The latter case is not common, there has been no practical experience, opinions would be welcomed.

Edited by kkala, 23 March 2012 - 12:05 PM.

[ankur2061]

Leo,

Vortex breakers should be provided in all liquid lines irrespective of type of vessel (horizontal or vertical) or whether the line goes to a pump suction or a gravity flow line. This is specifically applicable when the liquid outlet is from the bottom of the vessel.

Vortex breakers prevent gas entrainment in the liquid at low submergence levels. While this may be particularly helpful in a liquid line connecting to a pump you also don't want gas entrainment in a gravity or gas-pressure assisted liquid drain line.

Ensuring submergence in vessels where there is continuous liquid movement out is difficult. A vortex breaker is an added insurance against gas entrainment. I would recommend to provide vortex breakers in all liquid outlet lines irrespective of whether the line goes to a pump or is gravity drained.

A great discussion on vortex breaker can be found at:

http://eng-tips.com/....cfm?qid=268143

A typical P&ID for a 3-phase separator with a liquid outlet by gravity has a vortex breaker as per the link below:

http://www.enggcyclo...arator-vessels/

Hope this helps.

Regards,
Ankur.

[J_Leo]

Thank Kkala and Ankur for your great inputs.

In our company practice guidlines, there is a graph shows when to use a vortex breaker. It is related to the liquid level and the outlet velocity in the pipe no matter if there is a pump downstream. I think it is reasonable.

I check with some of my colleagues, they believe that a vortex breaker is needed when there is a pump downsteam, otherwise a vortex breaker is not needed.

I do think it is more conservative to provide a vortex breaker at the bottom of the drum.

Leo

[kkala]

Vortex breakers have also disadvantages, since their cleaning is not always easy or convenient. So this has to be taken into account. Besides vortex breakers are not recommended for liquids containing solids.

[ankur2061]

Leo,

For vessels that contain solids (sand etc.) vortex breakers can be placed raised from the bottom. This is called a non-flush vortex breaker. Refer the link below:

http://www.cheresour...ical-separator/

Regards,
Ankur.

[kkala]

http://www.cheresour... fix#entry67483 '> http://www.cheresour... fix#entry67483 has the attachment "submergence.pdf" concerning criteria and design of vortex breakers, useful even in case of drums.
Searching for vortex breaker applications on slurries, I have been informed that there are in refineries. However phosphoric acid tanks or even waste water tanks in a fertilizer industry (both containing gypsum - CaSO4.2H2O) did not have them installed, evidently due to main problem of precipitated gypsum. Strong air vortex is recalled in a waste water tank there, but no thought of vortex breaker. Thus applicability of vortex breakers on slurries should be decided for each individual case, based on experience and available data.

[Bobby Strain]

I would always install a vortex breaker. They are cheap. You would spend more money deciding when/if to use one than the cost of the vortex breaker. A single vertical plate with width of 2x the outlet diameter and height the same as the width, weld in place.

Bobby

[kkala]

In case of slurry, Bobby, there can be plugging. This depends on the specific (slurry) case. The article referred in post No 7 (attached to the post of breizh) notes: "In general, vortex breakers should also be used judiciously to reduce capital and maintenance costs, and because they may be susceptible to fouling or plugging by solids".