Calculate water dewpoint in line gas transmission

[dimas_brata]

Hi guys,

Would you like to inform us how to calculated water dewpoint in line gas transmission, we know that the boundary limit for water content approx.7 - 10 lb/mmscf (may vary several country) to avoid internal corrosion or hydrate formation. For your information that we usually use manual chandler chamber (chilling process) to define tdew >> use the graph with refers some pressure, we can find water content. But my question is which pressure we will choose? The line gas pressure or the pressure @ chandler chamber. Please help me within several reason.

many thanks

[carlo.stenali]

water dew point is difficult to calculate cause water is a polar, non ideal fluid,
you may consider the thermodynamic models developed by GERG,
EOS with complex mixing rules, models as CPA etc.
you can calculate water dew point as well as vapor-liquid-liquid phase envelope,
hydrate formation temperature and pressure
directly in Microsoft Excel with a library for process simulation as prode Properties,
see this thread :

[link Point to another website Only the registered members can access]
the method you utilize (chilled mirror) to measure the dew point is accurate but you measure the dew point of the mixture which can be higher than water dew point (if some heavy HC is present in mixture)

if you know the composition, for example as result of GC online analysis or laboratory)
you can calculate the HC dew point and water dew point (see the above thread about PRODE PROPERTIES),
also you can calculate these values ONLINE (see Prode thermodynamic server)

Read more:

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