Use of a Control Valve as a flow meter??

[leggy]

We are having problems with some ultrasonic flow meters installed recently on the oil outlet of a first stage seperator.

It would appear that we are getting sufficient water or gas in the oil to prevent the meters from working.

As a quick fix for this we are looking to use a control valve mounted downstream of the meter to approximate the flow vs %open.

Has anyone used this before ? What sort of accuracy was achieved?

We are looking to calculate the flow based on the Cv of the valve.

Any helpful tips??

We can program the DCS to calculate the flow.

Leggy

 

[bcd]

Hi,

Do an internet search on "NELFLOW". Such a product is commercially available. Their literature should help in identifying the accuracy.

BCD

 

[leggy]

Thanks, I have looked at this and it could be useful.

What we are trying to do is use an existing 12" Globe Valve from Fisher rather than shut in to change out.

 

[hacksaw]

accurracy is +/- 20% unless you have a valve that has calibrated in a flow lab.

just put a valve down stream of your current meter. this can create back pressure that will help prevent gas from coming out of solution and allow for proper dis-engagement in the separator. It does not have to be calibrated, the meter should work fine.

The caveat is that your piping system has been appropriately sized and in such a way as to keep the pipe liquid full..

good luck

 

[zdas04]

Even calibrated in a lab, a proportional valve is never more accurate than around 15%. You could probably get the backpressure benefits with an inexpensive orifice plate between two flanges downstream of the ultrasonic meter.

David

 

[209larry]

leggy,

You can use control valve to measure flow if you have critical flow condition and there is no phase change which I think is not possible since you have saturated condition.

An alternative is to relocate your US flow meter way below your vessel to prevent gas breakout. Three to four meters below normal liquid level and preferably flow direction of ultrasonic meter is downwards.

Also opt changing your ultrasonic meter to coriolis meter. There is no minimum straight length requirement for coriolis meter and can accept gas breakout. Water cut, volumetric and mass flowrate, totals can be displayed and accessed in some coriolis meters.

Regards,

209larry

 

[4carats]

I know Valtek (now FlowServe) make a control valve with pressure and temperature sensors in it for measuring flow, except I do not know how good it is.