V-Cone in wet gas measurement

[lacajun]

Have any of you used the V-cone in wet gas measurement? If you have, how did it perform? Any feedback you can provide would be appreciated.

Thanks!

Pamela K. Quillin, P.E.
Quillin Engineering, LLC

 

[zdas04]

Yes, I use them all the time for wet gas measurement. In one application I had an AGA-3 meter (with flow conditioners) feeding 5 V-cones and two crappy AGA-3 tubes. The crappy tubes then fed 7 or 8 v-cones respectively. The crappy meters were 10-15% lower than the sum of their V-cones and the operator wanted to rip the V-cones out but had the good sense to call me before he spent the money. I compared the good tube to the two crappy tubes plus the 5 V-cones and got a loss of 7%, not good. Then I compared the good tube to the 20 V-cones (ignoring the existence of the crappy tubes) and the maximum error (hourly data for 30 days) was 0.8% and the average error was 0.125%--far better than the published uncertainty.

The AGA-3 tube with a flow conditioner did a great job. The V-cones did the same job for a fraction of the cost. I'm a big fan of the V-cone.

Another client had V-cones on the wellhead and a decent AGA-3 tube at the compressor station. The average error was over 20%. Lots of people were bad mouthing V-cones. McCrometer's rep went to the wells and found: (1) in a natural gas field the guy setting the v-cones up had left the default gas analysis for air in the RTU; and (2) he chose orifice calculation instead of V-cone calculation (big difference in how you calculate β ratio). They put in the right gas analysis (SG 0.65 instead of 1.0) and the right calcs and now the sum of the wells is around 0.75% higher than the AGA-3 tube. Funny thing is that EVERYONE in the company had heard about the crappy v-cone measurement, but NO ONE has heard that it was operator error instead of equipment failure. I did a HAZOP on another system last month and two different people questioned my choice of V-Cones for the project. We finally had to pull current field data to show that the "problem" had been fixed.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[lacajun]

David, thanks for the response. I have a quote coming from them.

Pamela K. Quillin, P.E.
Quillin Engineering, LLC

 

[roydm]

You will need to be carefull that the impulse tubing is self draining or if you have to mount the transmitter below run the tubing up for a couple of feet then down to a drainpot with the transmitter self draining.

 

[zdas04]

Better than self-draining, make them close coupled. The distance between the ports lends itself to direct attachment of a 5-ball manifold that you can attach a 3-N-1 transmitter directly to--no tubing at all.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[lacajun]

This one can easily be close coupled. Thanks for the tip!

Pamela K. Quillin, P.E.
Quillin Engineering, LLC