Dear All
I am doing blowdown calculation for two- phase separator vessel on hysis.
I am using heat input model as FIRE API521.

My vessel design pressure is 15 barg and operating pressure is 12 barg and operating temperature is 100 deg F.

What the temperature and pressure I should consider for blow down calculation.

This blow down valve is design to operate on High-pressure switch and manually by operator

Please help me.

Thanks
Deepak

Deepak,
I would suggest you blowdown from High-High pressure trip setpoint with maximum liquid inventory (high level alarm).

I am not sure what type of facilities you have. The API521 Fire module is considering Pool fire. Please assess the potential of jet fire.

JoeWong

Thanks Joe
i wouul do that but in case of pool fire as iam doing what temprature at blowdown i should consider

I would guest you can base on the temperature generated by HYSYS. Personally, i would think the temperature have quite minimum impact to blowdown as compare to pressure.


JoeWong

Hi Joe

I have seen great impact by start temperature also and hysis is not calculating any temperature increase with time during depressurization. So I am not sure about what you are recommending.

Hope if you can give some other idea or shall I take normal operating temperature

Deepak

You may assess what the possible maximum normal operating from the system. This probably will give you maximum blowdown rate.

JoeWong