Steam Dryness
Steam Dryness
(OP)
Does anyone know of any instrument or device that can measure steam dryness and superheat? I've been looking at test kits like ( http://www.steamquality.co.uk ) but kits like this are very dependent on the user's procedure to gain any measure of repeatability. I was hoping for something more automated that wouldn't take as much training and finesse to achieve accurate & repeatable results. Any help that anyone can provide would be greatly appreciated.





RE: Steam Dryness
Usually you can determine steam quality based on temperatures and pressures through the header.
RE: Steam Dryness
RE: Steam Dryness
The transformation through the throttling valve is isenthalpic (well not precisely isenthalpic as the enthalpy is not constant from the beginning to end of the process, but the initial and final enthalpy is the same) so h1 = h2.
Now:
h1 = hf1 + x*hfg1
Where:
hf1 = enthalpy of water at pressure P1 (known)
x = dryness (unknown)
hfg1 = enthalpy of evaporation at pressure P1 (known)
You can measure h2, knowing P2 and T2 (this temperature should be above the saturation temperature Ts2 at reference pressure P2).
h2 = hf2 + hfg2 + cps*(T2 – Ts2)
hf2 = enthalpy of water at pressure P2 (known)
hfg2 = enthalpy of evaporation at pressure P2 (known)
cps = specific heat of steam is state 2 (known)
Ts2 = saturation temperature at pressure P2 (known)
T2 = temperature of steam in state 2 (measured)
Being h1 = h2 and solving for x
x = [hf2 + hfg2 + cps*(T2 – Ts2) –hf1] / hfg1
I also suggest:
ASME Performance Test Code 19.11 Steam and Water Purity in the Power Cycle
RE: Steam Dryness
If anyone else knows of a device or sensor that does this please let me know. As always, thanks for the help!
RE: Steam Dryness
I'd try to contact Spirax. Those guys have a wealth of experience with steam.
http://www.spiraxsarco.com/us/
RE: Steam Dryness