Large gas bubbles in gasoline storage tanks

[antoinecom]

I am interested in determining the effect of injecting nitrogen at 5 barg into the bottom of a gasoline storage tank at atmospheric pressure.
I would like to determine if the "shock" of this gas would cause a significant wave(s) at the liquid surface.

 

[LSThill]

antoinecom (Mechanical)

API 653 Tank Inspection, Repair, Alteration,
and Reconstruction APPENDIX B—EVALUATION OF TANK BOTTOM SETTLEMENT, B.2 Types of Settlement, B.2.1 ELEVATION MEASUREMENTS, B.3 Determination of Acceptable Settlement,
B.3.3 INTERNAL BOTTOM SETTLEMENTS OR
BULGES.

 

[JoeTank]

I've never heard of this situation causing any tank or bottom problems. Make sure you have adequate venting to handle this problem. API-2000 might give you the info needed.

One problem that has occurred during gas injection is floating roof damage. I have investigate a couple of roof sinkings that occurred after latge slugs of gas were inadvertantly injected into the tank product.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[antoinecom]

Gentlemen, I should explain that my main concern was the effects of a continuous flow of nitrogen at 5 barg being suddenly introduced into a tank containing gasoline. (Hence the "large bubble") The line is 12"NB and the tank is 7.5 metres diameter by 6.0 metres high. There is a "floating" suction arm that might be susceptible to damage if the stored gasoline was seriously disturbed by the nitrogen flow.

 

[tkequipments]

First question would be which size of floating suction line you are using, and with which kind of swing joint.
If you are using a non symetrical swing joint, you may face troubles.
In order to avoid this, you could use a diffuser (12"x16" for instance) with holes equally distributed. This would decrease the effects of the nitrogen bubble.

 

[hacksaw]

you must use a diffuser period. otherwise you'll have all sorts of problems