Large line mixed gas flow
Large line mixed gas flow
(OP)
I've looked at most everything I can think of for this application.A mixed gas by volume % of SO2:11.73, O2:11.73, CO2:0.14, N2:76.4. The pipe is 86" diameter, 10mm wall CS. Norm flow 78,000 Cu ft/hr, 150 deg F., upstream press -2PGIG. minimal up/downstream diameters too as per the attached.
I've looked at averaging pitot tubes, thermal mass, ABB Torbar and Meriam Accutube. Trying to sort out if just taking taps inside/outside the elbow might work or a transit time gas meter?
All suggestion gladly taken.
Thanks, Dave
I've looked at averaging pitot tubes, thermal mass, ABB Torbar and Meriam Accutube. Trying to sort out if just taking taps inside/outside the elbow might work or a transit time gas meter?
All suggestion gladly taken.
Thanks, Dave





RE: Large line mixed gas flow
RE: Large line mixed gas flow
RE: Large line mixed gas flow
I'm still stuck on this one if anybody can help.
Thanks
RE: Large line mixed gas flow
1) Install an avg. pitot in plane with the top elbow. Install it 1.5d in front of the bottom elbow in the vertical section (with limited straight-run, better to cheat on the downstream side). No reason you shouldn't get good repeatability (accuracy would have to be "estimated").
2) To improve accuracy, cross two avg. pitots in the same location and a) manifold them to one common DP transmitter or b) install a DP transmitter on each avg. pitot and average the combined signals in the DCS. I prefer option 2 for redundancy.
3) For ultimate accuracy, perform a dual axis pitot traverse while the avg. pitot(s) are in line (installed and operating). Calibrate the avg. pitots based on the traverse data.
Obviously others may have differing opinions, but I've seen many piping/duct scenarios in coal fired power plants (primary air, secondary air, air to pulverizers) that have less straight-run. It's tough measurement with limited options (especially in the large duct sizes) and you have to live with a degree of inaccuracy, although repeatability should be very good if the meter is installed correctly and all variables are considered.
I assume the SO2 is dry?
If the application is "blessed" by the manufacturer, you could always ask for a trial (delayed billing) based on performance.
Hope this helps.