Steam Flow Through Gate Valve
Steam Flow Through Gate Valve
(OP)
I am having trouble calculating the mass flow rate of saturated steam through a gate valve. Inlet and outlet pressures and properties (density, enthalpy etc.) are known along with orifice size (full open gate valve). I cannot figure out, however, the proper equation to use in the calculation of the mass flow. My old fluids book (Perry's as well) only deals with compressibility of perfect gases. Saturated steam is definately not a perfect gas. Choked flow is also not a factor (dealing with low pressures - 50 psia inlet / atmospheric outlet).
Any direction is greatly appreciated!
jproj
Any direction is greatly appreciated!
jproj





RE: Steam Flow Through Gate Valve
Does that help, or have I misundersatood your question?
RE: Steam Flow Through Gate Valve
I suggest getting/borrowing a copy of Crane's technical paper 410. It will have the equations in there for compressible flow. How big is this valve? If you really have (about) 35 psi dP across just an open gate valve, that steam is really going to move.
If you have a size, I can give you a rough estimate but Crane would be your best bet.
RE: Steam Flow Through Gate Valve
TD2K:
I am curious about the Darcy equation (Crane equation 1-11). I take it that the 0.525 value is a conversion factor. I am calculating the conversion factor to be 0.473 ... (1/144)*(32.2*144)^0.5 ... any insight?
Also, for a 4" line (50 psia inlet) with a 4" gate valve (wide open, discharge to atm) I calculate approx. 24,000 to 27,000 #/hr (depending on the conversion factor used). Is this in the ballpark?
Thanks for the help, I appreciate it!!
jproj
RE: Steam Flow Through Gate Valve
I'll have to take a look at the question you raised on the Darcy equation in a bit.
RE: Steam Flow Through Gate Valve
When I worked through it starting out from equation 1-4, I got the same 0.525 as Crane does for equation 1-11. If you still have problems (or care
I also did a hand check of my spreadsheet that I used to come up with the 31,000 lb/hr and got essentially the same answer. Are you including any 4" pipe in determining the total K for the system that could account for your lower flow rate?