bubble point pressure vs absorber bottom pressure 2

[pmoneysh]

Dear experts,
This query is based on simulation results (aspen hysys).

What I thought was scrubber or column bottom pressure would be at bubble point which corresponds to bubble point pressure. However, the vapor pressure at the scrubber bottom temperature (with the same composition) is estimated to be higher than the column bottom pressure. How can I explain this situation?

For example, the scrubber bottom pressure is 1.028 bar at temperature 45.82oC. Bubble point pressure is estimated at pressure=1.05 though temperature and composition are kept constant.

 

[Jessica Walliams]

The bubble-point pressure of a hydrocarbon liquid at a given temperature is the vapor pressure of that liquid at the same temperature. If the composition and temperature of a hydrocarbon liquid are known, its vapor pressure can be determined by calculating the bubble-point pressure.

 

[MortenA]

You say a scrubber, is this like a flash drum or a vessel where you a scrubbing a gas stream (say natural gas) with a liquid, say TEG to remove water?

Best regards, Morten

 

[pmoneysh]

To make my point understandable without confusion..... I am getting liquid phase even below the bubble point pressure. And the vapor phase is produced only at vacuum pressure.
I cannot plot the phase envelope due to some required changes to be made on thermodynamic model.

 

[MortenA]

Have you checked the calculated composition of this phase - could is be pure water? Most cases phase diagram is calculated on a dry basis - but if your stream has water it can form a water phase...