Two phase downflow pipe sizing
Two phase downflow pipe sizing
(OP)
I'm trying to confirm the sizing of a line from a partial condenser to a flash drum. The line runs vertically down from the condenser to the drum. I've got a two phase mixture, roughly 50:50 mass flow liquid to vapour. I'm attempting to confirm that fluid hammer will not be a problem (or as an alternative, the flow regime).
My first though was Fr<0.31 for self venting flow, but I can't convince myself that this is valid for co-current vapour and liquid down flow. Any suggestions are gratefully received.
My first though was Fr<0.31 for self venting flow, but I can't convince myself that this is valid for co-current vapour and liquid down flow. Any suggestions are gratefully received.





RE: Two phase downflow pipe sizing
RE: Two phase downflow pipe sizing
RE: Two phase downflow pipe sizing
I2I
RE: Two phase downflow pipe sizing
Good luck,
Latexman
RE: Two phase downflow pipe sizing
http://virtualpipeline.spaces.msn.com
"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain
RE: Two phase downflow pipe sizing
An alternative would be to install 2 lines - I have seen it done this way for condensers. Put a gooseneck (or water seal or P trap - whatever you like to call it) in the liquid line to ensure only liquid travels down that leg. And then put in a separate line from the condenser, connected where no liquid will enter it, to allow dry vapor to travel to the flash drum.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Two phase downflow pipe sizing
As was rightly stated, it's a pilot plant, so I'm more interested in smooth operation (and therefore data). A liquid leg and vapour balance line was one of the possible process options I considered for this.
I'm going with the easy option though, pushing the line size up a bit.
RE: Two phase downflow pipe sizing
I would target about 0.3 psi/100 ft and be done with it. Also, a larger pipe cannot hurt you, as it is downflow. Downflow is almost always annular flow (thus you cannot use typical flow regime maps).
Also, there typically is no pressure recovery (due to elevation change) in 2-phase down flow.