Effectiveness of dew point hand calculations?
Effectiveness of dew point hand calculations?
(OP)
Hi all,
I have been posting through the week about dew point calculations etc and I thank everyone for their help.
What I would like to know is how effective are the hand calculation for a natural gas stream. Composition is as follows;
Component Mol %
CO2 1.39
N2 1.78
C1 77.25
C2 8.47
C3 6.10
iC4 1.31
nC4 2.28
iC5 0.54
nC5 0.01
C6 0.40
C7 0.06
C8 0.02
C9 0.03
C10+ 0.02
When I do the calculation at 35bar the hand calculation shows a dew point around 52oC but HySys shows a temperature of 26.65oC.
Are hand calculations effective with multicompent streams?
Thanks,
R
I have been posting through the week about dew point calculations etc and I thank everyone for their help.
What I would like to know is how effective are the hand calculation for a natural gas stream. Composition is as follows;
Component Mol %
CO2 1.39
N2 1.78
C1 77.25
C2 8.47
C3 6.10
iC4 1.31
nC4 2.28
iC5 0.54
nC5 0.01
C6 0.40
C7 0.06
C8 0.02
C9 0.03
C10+ 0.02
When I do the calculation at 35bar the hand calculation shows a dew point around 52oC but HySys shows a temperature of 26.65oC.
Are hand calculations effective with multicompent streams?
Thanks,
R





RE: Effectiveness of dew point hand calculations?
you can get exactly the same accuracy if you repeat the same procedures.
With simplified procedures some errors should be expected, most important contribute is the way you estimate the fugacities.
Nowadays there are many tools which do these calc's so you have alternatives.
RE: Effectiveness of dew point hand calculations?
If you are using some simple EOS based on lab work based around typicals for 1 site, then expanding outward to the real world won't work. Most simple dew point calcs I've seen stop at C6.
If you modify your examples C10 plus to be 50% C10 and 50% C11, the dew point changes 6 degrees F. Based on your nC5 being wrong, it is most likely to be .0035 mole fraction.
Look through threads here about dew point of gas discussions and how the gas industry is in a quandry on how to quickly see dew points of gas streams in real time.
RE: Effectiveness of dew point hand calculations?
RE: Effectiveness of dew point hand calculations?
RE: Effectiveness of dew point hand calculations?
What does confuse me however is the offshore dew point analyser reads -20oC for that composition at 35 bar. HySys and my calculations would suggest that -20oC would be around 0 bar. Does anyone know if the analyser takes the inline pressure and produces the result at 0 bar?
I can send you the pdf versions of the campbells if you wish? I have all 4 volumes.
RE: Effectiveness of dew point hand calculations?
finally, if you have doubts about the values calculated (given composition and pressure) by simulator use another tool (see my previous post) to verify.
RE: Effectiveness of dew point hand calculations?
The industry has spent millions trying to do what you are trying, finding a cheap and simple dew point analysis, and we can not agree. If you really think you have stumpled onto something, why not present your solution to the industry at the GPA convention.