Estimation of two-phase flow in control valves

[MPalC]

I'm trying to review litterature in how to estimate rates in control valves under two-phase flow conditions. My application will be in petroleum, so there is chance of mass transfer between the two phases.

I've found some relevant litterature written for sizing and calculation of relief valves:
Tran and Raynolds: "Sizing of relief valves for two-phase flow in the Bayer Process"

http://www.hatch.ca/Light_Metals/Articles/sizing_relief_valves.pdf

Leung: "Easy Size Relief Devices and Piping for Two-Phase Flow", Chemical Engineering Prgress, Des 1996, pp 28-50.

However, this literature is meant for relief valves, where critical conditions mainly apply. I need to consider more generally. Does any of you know good methods or references on this topic?

 

[UmeshMathur]

MPalC:

Your question needs to be defined a bit more precisely: do you want information on sizing valves under 2-phase flow conditions? "Estimating rates" would appear to imply that you want to back-calculate flows based on pressure drop or something similar. You should know that this is nearly impossible to do with any reliability even for single phase flow.

 

[MPalC]

UmeshMathur,

Yes, I want to back-calculate. When the pressure drop is given, I want to calculate the mass rate. In addition to pressure drop, there could be several other properties availible, but I was looking for general correlations. It would also be helpful to investigate the sizing equations under 2-phase flow, even though that is somewhat the "back door" in this case.

 

[UmeshMathur]

MPalC:

I am unaware of any method to help you do this, as the pressure drop in 2-phase flow varies drastically depending on the flow regime. In any case, 2-phase flow correlations even in horizontal circular tubes are not that accurate. The same DP could theoretically result from different total flows with differing L/V ratios. Unfortunately, nobody can pretend to estimate DP across a valve, not knowing the 2-phase flow regime, with any reliability whatsoever - even if the L/V ratio was known.

Further, nobody even tries to meter flow in a pipeline after a 2nd phase develops. Usually, the stream is at a single phase somewhere else where it can be metered, so you might want to examine the P&IDs upstream or downstream.

If the 2 phase stream was formed by mixing other streams, their individual flows must be measured at an appropriate location.

Sorry I can't sound more encouraging.