4 replies to this topic

[David A.]

Greetings,

Currently I'm designing a "Produced Water Stoarge Tank", and the client is insisting they would prefer using instrument air for blanket gas.

I proposed using Fuel gas for balnket and Nitrogen for back-up. The storage tank holds produced water that has already gone through water treatment process, in my opinion I think instrument air in the tank can lead to oxygennation of produced water which portends a possibility for an explosive atmosphere in the tank.

The client's arguement is that the Produced water is already treated and the hydrocarbon content will be very low and cannot pose any safety risk. Can compressed instrument air be used as blanket gas? Has anyone come across this concept before, is it a safe process?

I'd really appreciate your expert opinions on this.

Thanks

[fallah]

David,

 

If the HC content cannot pose any safety risk and water isn't a demin one, there is no need to blanket gas; if water is demin one - e.g., for boiler make up - it should be blanketed with an inert gas, e.g. nitrogen.

[David A.]

Fallah,

 

Thanks for your response. The water isn't demin and HC content cann't pose any safety risk, but I also think the balnket gas can help provide some constant pressure in the tank during pump out to prevent the tank from collapsing.

[fallah]

 

David,

 

Because HC content cannot pose any safety issue, you can provide the protection against tank collapsing by proper free vent to the atmosphere.... 

[David A.]

Thanks Fallah, very much appreciated