I saw this question from Rajeev Jain and wanted to open it up to the refining community:
hi team , i need guidance on which type of solution or instrument or wireless device for flare measurment at refinery and fertiliser
Here's some guidance lifted out from the obscurity of my email inbox:
"Concerns in measuring flare gas are to ensure that the continuous purge is flowing (linear velocity of 0.1 ft/sec) up to nearly sonic velocity during a pressure relieving event. Perhaps an Annubar in the actual flare lines and a small flow meter (could be a Micro Motion) at the purge gas source for each branch of the header.
Another possible option is the GE Panametrics’ ultrasonic meter, which claims to be able to determine molecular weight of the gas which refiners may want to help them determine which relief valve is relieving (or leaking), something that the Annubar cannot do."
Another person noted:
"It’s really 2 measurements in one application: Annubars are good for upset conditions but generally can’t handle the purge flows unless a separate meter is installed in a smaller purge line."
One other person on the email string offered:
"We would be very interested in seeing the actual process conditions. It seems that every flare is different and the more we can learn about the application the better off we will be. We generally have had trouble measuring the purge flow in flare applications with Annubar primary elements."
If anyone else has anything to add, please jump in!