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Best dP correlation for two-phase steam?

Best dP correlation for two-phase steam?

Best dP correlation for two-phase steam?

(OP)
What correlation have you guys used with good success to calculate dP for two-phase steam?  I am using Beggs-Brill-Moody but it's not a very good match with the field data - the error is about 20%, which is too high.  This is a 70% quality, 550 psig system.  I also tried Dukler and LM but they were worse.

Any thoughts/ideas/miscellaneous ramblings welcomed...

Thanks!
Pete
pjchandl@prou.com

RE: Best dP correlation for two-phase steam?

Spirax/Sarco has a table that indicates steam leaks to ambient through various sized orifices at various pressures, but it didn't seem to indicate steam quality. I assume the table relates to saturated vapor. Interpolating from the table, 550 psig through a ½" orifice would give 3,430 lb/hour flow. What is the opening size?

Have you tried Bernoulli's equation (using 1.57 lbm/ft3 density at that quality)? -Chas

RE: Best dP correlation for two-phase steam?

In europe the big fuss is OLGA. It has a SS HYSYS plugin. Its not something you can "do by hand"

Try this link: http://www.olga2000.com/

Best Regards

Morten

RE: Best dP correlation for two-phase steam?

Beggs-Brill is good for only for cross country pipeline/flowline having diameter 8 inch or less.For small lengths (e.g. inplant piping) and where the total pressure drop is less than 10%  of the inlet pressure, API-14 E equation gives the better results.

RE: Best dP correlation for two-phase steam?

Beggs-Brill is good for calculating the pressure drop in  cross country pipeline/flowline having diameter 8 inch or less.For small pipe lengths (e.g. inplant piping) and where the total pressure drop is less than 10%  of the inlet pressure, API-14 E equation gives the better results.

RE: Best dP correlation for two-phase steam?

(OP)
When you say API 14E gives better results, have you done the calcs and checked them against field data?

Thanks!
Pete
pjchandl@prou.com

RE: Best dP correlation for two-phase steam?

(OP)
Bernoulli's equation is an energy balance equation.  It has the friction loss term in it so I still need some way to calculate the friction loss.

I should have mentioned that I am using the PipePhase software to do these calculations - I am not doing them by hand.

So far the best match is with the Dukler equation, with BBM in 2nd place.  The problem is - the correlations are overpredicting the dP by a huge margin, like 200%, relative to the field data, on the longest runs of pipe (several thousand feet).  I guess I will have to manually adjust the pipe to make the correlation match the field data.  The problem with that is - it fouls up the heat transfer calcs, which fouls up the accuracy of the steam quality predictions... oh well...

Thanks!
Pete
pjchandl@prou.com

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