9 replies to this topic

[ankur2061]

Hi,

Earlier practice for measuring gas flow in pipeline has been to use thermal mass flow meters and turbine meters.

However, there is an increasing shift towards using ultrasonic flow meters.

Is there a particular reason for it? What accuracies and turndowns are we talking about when using ultrasonic flowmeters? What are the economics vis-a-vis thermal and turbine meters?

Why would flare gas measurement require an ultrasonic flowmeter? Is it now mandatory in the U.S.and EU to measure and keep records of flaring and venting? Do any international standards give any guidelines about flare gas measurement and monitoring?

Guys, so many questions. Just hope somebody could answer.

cheers
ankur2061

[JoeWong]

Is there a particular reason for it? What accuracies and turndowns are we talking about when using ultrasonic flowmeters? What are the economics vis-a-vis thermal and turbine meters?

Why would flare gas measurement require an ultrasonic flowmeter? Is it now mandatory in the U.S.and EU to measure and keep records of flaring and venting? Do any international standards give any guidelines about flare gas measurement and monitoring?

Guys, so many questions. Just hope somebody could answer.

Some opinions...

Ultra sonic flowmeter has the following benefits / advantages compare to other type of flowmeters ;

- Low TURNDOWN (can be as low as 2750-to-1)
- "Zero" pressure drop)
- No internal, insertion and moving parts
- Can tolerate certain amount of condensed liquid
- Take higher operating temperature **
- Not affected by gas composition
- No maintenance

** My personal experience upto 260 degC.

Read the following basically answer most of your queries.

• The Future of Flare Gas Measurement
• How much do you flare? How to measure flowrates of flare gas accurately and reliably.
• Use Ultra-Sonic Flowmeter in FLARE Gas Header for emission monitoring

JoeWong

[Zauberberg]

Thanks for the links, Joe; really interesting materials.
Flowcontrolnetwork has a bunch of wide-subject literature available online.
http://www.flowcontr...om/magazine.asp

[AA Mishra]

Ultrasonic flow meters are not reliable.


Regards

[JoeWong]

As highlighted by (sorry, can't find the earlier post), heat tracing may affect measurement of Ultra-Sonic flowmeter.

JoeWong

[ankur2061]

Hi Joe,

Thanks for all the input. It is really good stuff.

One more question!

What are the regulatory guidelines for flare gas measurement given by regulatory bodies like EPA and others (I don't know which is applicable in EU), if any?

[JoeWong]

Hi Joe,

Thanks for all the input. It is really good stuff.

One more question!

What are the regulatory guidelines for flare gas measurement given by regulatory bodies like EPA and others (I don't know which is applicable in EU), if any?

ankur2061

Can't help you much other than advise you to find those information in the following Links...If you are kind enough, once you have answer to your questions, please post them here for the benefits of all.

• EPA
• EU

Lets learn together...leaning is continuous process in life.

JoeWong

[Radionise]

Preferrably, the flow measurement device for flare gas header is a non-intrusive type. The last thing you want in your flare / vent system is some obstruction or blockage in the header or pipe.

I can't comment on how reliable an ultrasonic meter is, but at the very least, if there is a need to replace, maintain or repair anything with the measurement device, you can proceed without shutting down the flare system, or as a matter of fact the whole plant.

[VikingUK]

In my experience ultrasonic flowmeters are not too accurate at the low pressures involved in flare systems. You need at least 5 bar to get an accurate reading.