# Thread: Gas : water/Hc dew point

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## Gas : water/Hc dew point

HI to all

i have a gas stream, i want to calculate the maximum water and Hc dew point betwen two ranges of pressure, this by hysys?

any one can help me

thx

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## Re: Gas : water/Hc dew point

do u know how to calculate dew point hysys.....set composition, desired pressure...ex: MDC + water mixture 50% each, 1 atm...you define the stream with this compostion without temp. then vary the temp..intially u will find only vapor fraction...as you vary the temp u will find there are both liquid & vapor fraction for the stream..the temp at which liquid fraction appears is the dew point...( the temp at which first drop liquid forms or condenses is dew point).

Then repreat the process with different values of pressure

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## Re: Gas : water/Hc dew point

since you wish to calculate the dew point (temperature) in a range of pressures a simple way is to calculate the dew point line or the phase envelope, to do that I use a different software (Prode Properties a simulator which works in Excel and Matlab, as I prefer these tools) but I presume your simulator can to the same.
To evaluate the contribute of water you can calculate the dew line (or the phase envelope) with and without water, that 'll permit to observe the additional two-phases area due to water presence.
To calculate VLE for hydrocarbons plus water take care to select the right thermodynamic model.