6 replies to this topic

[81totototo]

Hi dears
How to avoid dense phase in hysys to depressurise supercritical hydrocarbon gas.
Please if anyone has any information help me.

[PaoloPemi]

I am not sure to understand the question,

 

if your starting point is outside VLE area in dense phase

you must start from dense phase and go on

will all points,

 

or am I misunderstanding the question ?

[81totototo]

How

[PaoloPemi]

perhaps, with a little effort,

you may try to explain with more details the problem,

and someone will give an opinion.

[Sharma Varun]

There is a dense phase tuning factor, search in the HYSYS help, you can set its value between 0.5 to 2 this may solve your problem.  

 

We had similar case of high pressure depressurisation involving supercritical phase,where HYSYS was giving different results for every run. Try following:

 

1. In the introduction of the "Phase Order" tab at the Fluid Package property view (Basis Environment), Set the "User specified primary components" radio button, & select Methane for primary component in Liquid-1 and Water in Liquid-2. There is no water at all in the feed to the DPU, but this helps anyways. HYSYS seems to work better when two liquid phases are explicitly specified, even if this does not actually takes place.
2. Other than this, you must set a small integrating step (0.05 seconds) and very small recycle efficiencies (this seems to me more and more a must for DPUs).
3. A last thing in this case: check mark the option "Prevent temperature cross" at the DPU property view, Design/Heat flux page. Otherwise, the inner wall temperature will end up being lower than the corresponding fluid temperature. 

varun

Edited by Sharma Varun, 04 October 2013 - 04:44 AM.

[PaoloPemi]

so it would seem a specific problem of the procedure

which may not work as expected in supercritical area,

thanks for the comment.

[Sharma Varun]

so it would seem a specific problem of the procedure

which may not work as expected in supercritical area,

thanks for the comment.

 yes indeed it is a specific problem related to behaviour of HYSYS dynamic deprssurisation utility in super critical phase, rather it was a problem with earlier version of HYSYS which they took care off in Ver 7.2 by introducng DPT factor & with further improvements in version 7.3. So please note that this dense phase tuning factor is available only in later HYSYS versions  & one won't find it in version 7.1

Edited by Sharma Varun, 04 October 2013 - 07:19 AM.