2 replies to this topic

[marchese85]

Hello !!!!!
I'm working on a dynamic simulation in hysys (batch distillation) ... I'm having a big problem with a condenser. The flow of vapour is about 250 kg / h. I've set a heat exchanger volume equal to 0.08 m3 . When I start the simulation the mass balances are correct (although with some inaccuracy), but the compositions of the incoming steam and condensate (fraction of steam is zero) don't correct. How do I solve the problem ????.
I tried to reduce the step size and modify the execution rate of composition and flash calculation, but without results.
how can i do????...i'm desperate...please help me!!!!!
thanks in advance!!!!
p.s. sorry for my bad english

Edited by marchese85, 07 September 2010 - 04:41 PM.

[Bharat Abhyankar]

Hi marchese85,

I have faced similar problems with HYSYS dynamics, and I understand that it can be very irritating.

1) In order to understand your column, draw and specify your system. Can you attach a simple sketch?
2) Is it a Partial condenser or a Total one?
3) If its a Partial type, are you able to maintain column overhead pressure?
4) If its a total condenser, increase its UA and try to stabilize the column that way.
5) Dynamic Simulation is nothing but a Pressure Flow solver. If you can state what Pressure and flows you have fixed in your simulation, I may be able to help you further...

Keep Simulating!

[Bharat Abhyankar]

Hello Marchese85,

Do you observe vapor in the pump suction (P-100) when it starts destabilizing? (In the snap shot the pump is cavitating)
I guess that the problem could be associated with the phase flip in the Condenser.

Try the following:

1) Make sure the "Holdup Volume" of following valves is zero:
___a. reflux valve
___b. nitro aco valve
___c. RV-100

2) Is water present in overhead? In the phase detection option, manually set the water content in the vapor to 60% for separate phase detection.

Regards,