Freeze-Out Analysis Calculations for a Stream with a Very Low Water Content

Lili Lyddon

November 22, 2006

When ProMax performs the freeze-out analysis calculations for a stream with a very low water content (e.g. dehydrated natural gas), the water dew point may not be calculated or the value may not be meaningful. In most cases a liquid water phase will not form, or will not be thermodynamically stable for the current conditions. Sublimation will occur instead of condensation, meaning that the water goes from the vapor phase directly to solid phase (hydrate and/or ice), never forming a liquid phase. I have noticed that even when a water dew point is predicted for cases with very low water content, the dew point is always lower than the hydrate formation temperature. In this case the number is not meaningful and has a yellow cell background color. For obvious reason this number should not be used in any calculations such as water dew point specifications for a sales gas stream. The solids formation temperature should always be used since it is higher.

Authored by Lili Lyddon - BR&E Technical Support / Help Author