Have a mixed natural gas liquids stream that has a smallish fraction (5%) of ethane with the balance being heavier hydrocarbons.

Pressure 300 psig
Temperature 170F
Flow rate about 250GPM

Having trouble measuring this stream, a turbine meter was tried, and removed(unknown why it was removed, before my time) have had some success with an annubar measurement, but due to foreign objects in stream, have damaged two elements. Probably why the turbine meter didn't last either. Annubar was repeatable, but I do not think, absolutely accurate. Going to try a coriolis meter, but I fear that won't work because the ethane is boiling and will cause entrained vapors.

anybody have any suggestions?
I want as accurate as possible.

 

If foreign particle are present to damaged rigid sensor like ANNUBAR than definately Turbine was also damaged due to the entrapped particles in process. Was clogging a problem with ANNUBAR or it broke in line? Considering the process to laden with heavy dirty/particles I would recommend you to use Clamp On Ultrasonic Flow Meter (UFM), it would be an excellent choice over Coriolis as UFM is a non-intrusive technology hence there won't be any damaged to the flow meter.

Further clarity on process will help to understand the application better to recommend the most optimum & long lasting solution.

 

small SS bolts coming out of umstream process vessels, seem to have caused blunt damage to the annubar (right on the pressure sensing port). I took a few of these bolts out of downstream control valves.

I thought about UltraSonic, but I believed it's signal to be attenuated by vapor in a liquid stream. Is this not correct?

 

Coriolis will potentially aggravate the problem as it is a high pressure drop device and may encourage more vapour break out.

However, some manufacturers can now manage entrained gas in the flow stream so it is worth talking to both Emerson and Foxboro who both claim this capability to measure mass flow even with entrained gasses.

However, you may find these are the conventional complex tube shape meters and they will not like solid objects such as bolts trying to flow through them.

Of course, the question is, why are these bolts in the flow stream and isn't that the problem and not finding a meter to handle them?

 

Hopefully, the upstream equipment is out of bolts.

I believe that we have some damage due to flow reversal in an upstream fractionation tower. We might have a bubble tray or two damaged, but we are still getting acceptable performance, from a process perspective.

It is Emerson that we are dealing with(formally MicroMotion) and I am aware of the claim that they can do entrained vapor, but you nailed my concern about the pressure drop inherent with a coriolis meter.

anybody have any luck with something similar?

 

Nobody has anything else?

 

Since it was a operational problem to damage ANNUBAR, I would still select ANNUBAR if that performed well in past on the application. If required install two partial ANNUBAR sensors wherein signals can be integrated to a single DP Transmitter which will definately give you better measurement as well as will act as a redundant system too (In case of failure).

 

Hi

As you said the coriolis flow meters are the best suitable solution.
The coriolis meters accurate than any other flow meter in dual phase applications.

Please give me the process parameters like pressure, temp, line size, viscocity & density. I will let you know the pressure drop...

Rgds,

 

I understand E&H has entered into the entrained gas capability with Promass A, i think. Promass is single tube and reasonably straight so may give the best pressure drop results.