HC Dew Point Temperature vs Stream Temperature of Fuel Gas

[asade]

Hi All,

From the fuel gas system HYSYS model I developed, I noticed that the HC dew point of the gas @ stream condition is 62.22 deg.F. The stream condition are temperature @62.23 deg.F and pressure @ 250 psig. The fluid is a fuel gas to be supplied to a GTG.
1) Would this close HC dew point temperature to stream temperature affect the property of the fuel gas to the GTG?
2) Should I consider the installation of a heater to increase the flow temperature when the FG condition required by the GTG is within the range of 45.8 - 48 deg.F and 242 - 250 psig?


I am what I am by His grace

 

[PaoloPemi]

for standard hydrocarbon's mixtures you may generally consider 1-2 degrees K of accuracy (depending from several factors) in dew point calc's with well tuned Soave Redlich Kwong or Peng Robinson models, at least that is my experience with a different software (Prode Properties), considering those errors you may observe the formation of some condensate in your line,
depending from amount of condensate the properties (composition of vapor phase, density, viscosity) may change, the condensate may also cause problems in a line designed for vapor phase,
if the amount of condensate is very low perhaps you can separate the liquid, differently a heater or different unit.

 

[MortenA]

I take it this FG in model comes right out of a separator? ANY gas right out of a separator has a dew point similar to the operating temperature (thats thermodynamics and convetion).

Your engineering specs will prpably have something on margin for fuel gas wrt dew point. Choke back pressure and usually you will see some condensation - and then your FG will once again be "wet", compress it and usually it will superheat somewhat - but not so much as to prevent condenasation if you cool it afterwards to a "Normal" temerature.