Water and Hydrocarbon Dew Point temperature 1

[SanjayPatel]

Can somebody tell me how to calculate Water and Hydrocarbon Dew Point Temperature of natural gas OR refinery fuel gas without help from any simulation?

 

[1969grad]

See GPSA Engineering Data Book.

 

[22082002]

Handbook of chemical engg. calculations by Nicholas P Chopey..!

 

[MortenA]

set up the equations of e.g. Soave-Redlich-Kwong and solve them yourselv. Its not that hard - if you only have to do it for one state and have the pure component data.

Best regards

Morten

 

[joerd]

Read thread391-53663
This also contains a link to an online dewpoint calculator at

http://www.questconsult.com/~jrm/thermot.html

(kudos to Kbander)

Cheers,
Joerd

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[dcasto]

Try this: Water in pounds/MMSCFD =(10^(3.5551-0.94283*LOG(absolute pressure)+0.01576*(Temperature F-31)))

 

[zdas04]

dcasto,
I've been looking for an equation like that one for several years. Do you have a reference for it?

When I plot the data from your equation on the same plot as data from the GPSA fig 20-3, the equation shows a family of semi-log straight lines (of course), but the GPSA data shows a distinct downward curve at higher temps. Below 100F the match is outstanding. By 150F the equation is 80% higher than GPSA, and at 200F it is over three times as large.

The GPSA data looks to be dead straight in the book, but picking points off it gives you a curve. I've got three different versions of the GPSA plot (going back to the 1960's) from other sources and I got the same points from all three, and the three isobar's I picked points from gave me three parallel lines--all with a downward curve.

Now I'm really confused.

David

 

[dcasto]

David,

The equation is a form of the fugacity equation of partial pressure. I got it from and O&GJ article years ago. I've tried todo a linear regression using the GPA tables with the EXCEL.

Highlite the stuff below, then copy paste to and excel blank sheet to see all the cells.

SUMMARY OUTPUT Constant (1/t)^2 (1/t)^3 ln(p) (ln (p))^2 (ln (p))^3 (ln(p/t))^2 (ln(p/t))^3
ln( water ) = 13.29315 (4,261,306.00) 662,351,880 1.8362996 -0.36872304 0.01679344 0.1751796 -0.0086638038
Regression Statistics
Multiple R 1
R Square 1
Adjusted R Square 1
Standard Error 2.66844E-12
Observations 14

ANOVA
df SS MS F Significance F
Regression 7 62.71211606 8.958873722 1.25817E+24 4.56498E-72
Residual 6 4.27235E-23 7.12059E-24
Total 13 62.71211606

Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Lower 95.0% Upper 95.0%
Intercept 13.29315 4.078E-10 32597200865 5.62629E-62 13.29315 13.29315 13.29315 13.29315
X Variable 1 -4261306 5.00461E-05 -85147693311 1.7712E-64 -4261306 -4261306 -4261306 -4261306
X Variable 2 662351880 0.015687353 42222028294 1.19143E-62 662351879.9 662351880 662351879.9 662351880
X Variable 3 1.836299599 3.32517E-10 5522417297 2.37973E-57 1.836299599 1.8362996 1.836299599 1.8362996
X Variable 4 -0.36872304 9.70528E-11 -3799201784 2.24466E-56 -0.36872304 -0.36872304 -0.36872304 -0.36872304
X Variable 5 0.01679344 7.6343E-12 2199736334 5.95772E-55 0.01679344 0.01679344 0.01679344 0.01679344
X Variable 6 0.1751796 5.0335E-11 3480274334 3.79859E-56 0.1751796 0.1751796 0.1751796 0.1751796
X Variable 7 -0.008663804 8.15032E-12 -1063002241 4.67841E-53 -0.008663804 -0.008663804 -0.008663804 -0.008663804