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Gas flow measurement in large stacks

Gas flow measurement in large stacks

Gas flow measurement in large stacks

(OP)
Hi everybody,
have anybody any experience on combustion flue gas flow measurement in large stacks?
Large means 40m. with 5m. diameters + 50m. with 4m. diameter. Total 90 m.
Flow is about 100.000 SCFM at 700°F.

I'm oriented on S-type pitot tube as claimed by the EPA code (mot mandatory in my case).

But I'm not sure about the accuracy and repetability  I can get.
Another problem is the location, in order to meet the 5 diam. straight run upstream and downstream the only suitable place is 64m. height (!!). Of course the maintenance dpt. is not happy.

Suggestion/Improvements?

Thanks.

RE: Gas flow measurement in large stacks

The multihole pitot devices like the Annubar or the Meriam Accutube work well in this sort of application. They measure and average the velocity over 4 zones, so they tend to give you a more representative reading than a single-point aircraft-type pitot.   These devices can even be installed in an elbow, if you follow the instructions.  
Since your pipe diameter is so large, I would use one with both ends supported.  Then gather the signal with a draft-range D/P transmitter.  

RE: Gas flow measurement in large stacks

Single point pitot is actually preferred for EPA measurements. Pull the code and you'll see why.


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