3 replies to this topic

[ChemEng01]

Hey Guys

 

I have set up a dynamic HYSYS model to calculate downstream pressure and temperature with respect to time during a system pressurisation.

 

Is there any way I can specify my downstream conditions prior to pressurisation?

 

HYSYS dynamics will give results assuming the initial temperature will be the worst cases isenthalpic flash temperature. In reality it wont because it will mix with the fluid already in the downstream system before pressurisation.  

 

Thanks for any advice

 

[serra]

if you are pressurizing a vessel sure you can define the volume and initial conditions (p,t) for the fluid inside the vessel...

if, for some reason, you can't do that a simple trick that I use in Excel with Prode Properties is to mix

two streams, for fluid inside vessel (at t, p conditions) mass flow is M (volume / density)

while mass flow m*dT defines the amount of fluid added on a specified dT

it's a simple way to solve the differential equations whch define the system...

[Zauberberg]

The easiest way - although not automated - is to track the desired variables via dynamic charts and stop the integrator manually once you see that the required condition (e.g. vessel pressure) has been reached.

 

The fully automated way is to introduce the target condition in the "Event Scheduler" module (Simulation Menu --> Event Scheduler) and define actions within the flowsheet following up the desired event. This would be, for example, to close the pressurization valve (set OP to zero) when the vessel pressure reaches target value.

 

You can find all relevant information in Aspen manuals (User Guide), and particularly in Hysys Dynamics, also available at: https://www.ualberta...micModeling.pdf

[ChemEng01]

Thanks guys

 

That's helped me a lot

 

cheers