Calculating Superheated steam press drops in pipes
Calculating Superheated steam press drops in pipes
(OP)
I'm searching for a useful formula to calculate pressure drops in pipes with superheated steam. I've tried using the original Babcock formula, but this doesn't seem to work for high pressure superheat steam. The pipe in question is DN150, 90 metres (with numerous elbows and valves) and the steam is at 83 bara (initial), 525 degC, 15.41 kg/s.
Can anyone point me in the right direction.
Cheers
Can anyone point me in the right direction.
Cheers





RE: Calculating Superheated steam press drops in pipes
What degree of accurracy are you shooting for?
RE: Calculating Superheated steam press drops in pipes
RE: Calculating Superheated steam press drops in pipes
This superheated pipe feeds a power steam turbine. I already know the pressure drop from plant instrumentation. I want to know what the pressure drop would be if the pipe was a bigger diameter, then I can carry out a feasibility study of bigger pipe increase against increased steam turbine output. The accurracy of the calculation is not essential, 20% will give me a good idea.
RE: Calculating Superheated steam press drops in pipes
Your could try the following formula
DP=(8.10569E+6*W^2*SV/D^4)*((F*L*1000/D)+K)
Where
DP= pressure drop in bar
W= flow rate kg/s
SV= specific volume m^3/kg
D= pipe bore mm
L= pipe length m
F= friction factor = 0.015 to 0.02 for DN150 depending on Reynolds number and pipe thickness
K= sum of loss factors for bends etc
typical values are
entrance = 0.5
exit = 1.0
3D bend = 0.18
globe valve = 5.1
Hope this helps
athomas236
RE: Calculating Superheated steam press drops in pipes
change out of HP steam piping is a practical impossibility unless you are putting new boilers on-line.
with existing boilers and TG's, the degree of superheat is the big player.
the best improvements are insulation and making certain the SH's are working at peak efficiency. We got an extra 2% just bringing the steam temperature up to design.
if you are running CS pipe you have some specific steam temperature limitations to consider so you cannot just arbitrarily increase superheat.
good luck,
RE: Calculating Superheated steam press drops in pipes
RE: Calculating Superheated steam press drops in pipes
Why can't you contribute in this thread
Thread507-29593
RE: Calculating Superheated steam press drops in pipes
If the steam is flowing at less then 0.2 Mach no, then an incompressible flow procedure will work.
A simple method is
DP ( psi) = (nVh) * Vh
nVh = number of velocity heads lost = Sum ( fL/d), including pipe straight length, bends, inlet , exit, valves, etc.
Vh ( psi)= (sv/12) * (W/1E5/A) **2
where sv= spec vol. ft3/lbm
W= lb/hr
A= pipe flow area , ft2
If you prefer a more acurate European approach, I believe they use the Gnielinski model on that side of the pond.