Wet Gas Flow Meter Uncertainty

[Ulon]

Dear all,

I beleive that taking the accuracy required for the Wet Gas meter will be called the uncertainty. Is it the correct practise?

How do we determine an accuracy of a Wet Gas meter since it's two phase. Meter that works fine with gas usually doesn't do so for liquid. I'm going to take the gas measurement accuracy to be the accuracy of the Wet Gas meter, is it okey?

Please guide me,

Many Thanks

 

[dcasto]

These are the defacto experts in two phase flow to date.

http://www.ceesi.com/

 

[veec]

K Lab of Norway are worth a look.

 

[zdas04]

NO that is not ok. This was the topic of my Master's theses and I can tell you that gas saturated with water vapor does not have the repeatability or uncertainty required of dry-gas measurement (instead of system uncertainty of 0.5% you should expect over 1%). Add liquid water and the uncertainty goes to over 10% and often over 20%.

"Accuracy" is a nebulous term that really has no place technical discussions.

"Uncertainty" means "You don't know". If your uncertainty is 1% and the flow rate calculates to 100 MCF/d then all you know for certain is that the actual number is between 99 and 101 MCF/d. Trying to imply an "accuracy" value to an intermediate number within that range is simply wrong and wildly inappropriate.

In order to get acceptable uncertainty in an inherently multi-phase system you have to either lower your expectations (problem is that you won't have a good basis for deciding what to lower them to) or remove the liquid prior to measurement. There is not a third option.

David

 

[Ulon]

I'm agree with you david...

anyway still we need to have a direction when dealing with this wet gas measurement?

 

[dcasto]

look into API RP 70, 85, 86 and 87.