Issues with the outlet of the flash tank
Thread Content
The flash tank has three outlets: one at the top and two at the bottom (one for water and one for liquid). When simulating hydrocarbon systems, I paid special attention to these two outlets; I used the two lower outlets to simulate them. By comparing the convergence results, I found slight variations in some parameters, while others remained unchanged, as this system does not contain water. I would like to ask: for a system without water, is it okay to choose any of the lower outlets? ； For aqueous systems (where the water content is not negligible), must the outlet for water and the outlet for the liquid be specified?
The water decant option in PRO/II is a special case of a three-phase flash. If this option is selected and water is present in the system, a pure water phase is separated as the second liquid phase, and this phase is not taken into account in the equilibrium flash calculations. This option is available for various thermodynamic calculation methods such as Soave-Redlich-Kwong or Peng-Robinson. It’s not necessarily necessary to separate the water; what matters is whether there is a need for separation.
I’m using V7.1; when using a water-free system, selecting water/2nd liquid caused problems, but things worked fine after switching to liquid. Previously, with V5.0, I also chose water/2nd liquid and there were no issues. I don’t understand why