Steam meter: high turndown

[david23]

Hello,

We currently have vortex meters installed however there are a lot of problems with the measurement of lower flowrates.
So I'm looking for a steam meter with a turndown of at least 15:1, preferably higher. As far as I can tell Vortex and DP meters are not very suitable candidates.

A possible solution that I know is an ultrasonic meter, does anyone have any experience with this? e.g. Cost, accuracy,...

Calorimetric flow meters may als be a solution. However I can't find any manufucturer? Same question here: any experience with cost, accuracy,..?

Are there other solutions besides the ones mentioned above?

Thanks

 

[danw2]

Kurz, Sierra and Thermal Instrument all offer heated element, thermal dispersion flow meters. I can not vouch for any of them on steam however, never having tried one on steam.

I have had excellent success with that technology for ambient temperature gases, but when I tried it on hot asphault, it did not work well, in fact it didn't work at all.

Dan

 

[Cat3347]

What are your flow rates? Is this saturated steam? What is the pressure? What is the line size?

Vortex meters are excellant steam flow meters....but they must be sized for the entire flow range. Many just give a maximum rate, and go from there. Wrong. Have you looked at integral reducers on the meter itself to increase the velocity of the steam?

Averaging Pitot Tubes are also used quite often, but you are at the mercy of the dP transmitter. New advances (ie. multi-range) have increased turn down ratios.

I have not seen any ultrasonic flow meters for steam in the field.

 

[ScottyUK]

We have a split range measuring system on our IP (~25 Bar) steam system based on an orifice plate but with two DP cells rather than the normal one. One cell is rated for full DP range and one sensitive cell calibrated to cover the bottom 10% or so of the range. The handover between the cells is performed by the DCS. It has proven both reasonably accurate and reasonably reliable.


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