Atmospheric Tank Nozzle Sizing 2

[eriskawk]

Hi everyone,

I am currently sizing a vent nozzle of an atmospheric tank contains produced water.

I have followed the API 2000 and already got my vent requirement is 992 Am3/hr of air.
but, I am stuck in the nozzle velocity criteria to determine the size of the nozzle.

does anyone have any advice of what reference to find the maximum velocity criteria for a vent nozzle?
I found in some articles and forums said it is kept under 10 m/s. but I need some valid reference to attach them to my calculation & report.

thanks!

 

[RVAmeche]

If you're buying a vent, the make/model you select will determine the nozzle based off the capacity and working/design pressures.

If it's going to be a gooseneck vent (open to atmsophere) and you need something to point to other than rules of thumb, the Groth Model 5000 gooseneck vent capacity (basically a flanged elbow spool) may be what you're looking for.

 

[LittleInch]

Holy moses -10 m/sec for a vent!!

An order of magnitude wrong there for an atmospheric tank.

The most basic diameter ROT is the same as the liquid inlet, but if this fluid is gassing off then at least 50% more.

Why are you sweating this? If in doubt make it bigger. Costs nothing.

Just quote Engineering norms and pluck 0.5 or 1.0 m/sec out of thin air. There are too many variables for any code to tell you - what's important is to keep the pressure in the tank below something like 4 inches of water column to classify it as "atmospheric". There are plenty of posts here on what "atmospheric" means. And it's very low.

API 650 classifies it as 1kPa.

So you can spend time and effort doing a study and calculations or just go with 0.5 or 1 m/sec.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

LttleInch gives good advice. This type of vent should be sized based on the MAXIMUM allowed design pressure that the tank will tolerate

A velocity of 10m/sec is screaming ..... Where did you get this reference for a tank vent nozzle ? ... Please share

Do not be afraid to "upsize" the vent by one pipe size for conditions that your boss has not yet told you aboiut

See page #4/5 of this GROTH Model 5000 vent document:

https://d3opzdukpbxlns.cloudfront.n...n1hACK~I2Q__&Key-Pair-Id=APKAI33AGAEAYCXFBDTA

What is the size and maximum liquid inflow rate of your water tank ?

MJCronin
Sr. Process Engineer

 

[don1980]

The real constraint is the vent line's pressure drop and not its velocity. Sizing an atm vent pipe is simply a line sizing exercise in which the pressure drop is limited to the max allowable pressure in the protected vessel. For example, if the max allowable tank pressure is 1 kPa, then the vent pipe must be sized for a max pressure drop of 1kPa at the required vent relief rate.

 

[AlmostRetired]

A good rule of thumb that I learned many years ago was that the vent nozzle should be at least one size bigger than the largest inlet or outlet nozzle on the tank.