3 replies to this topic

[go-fish]

Hi,

I am a budding process engineer. I am interested in knowing if one can simulate pressure drop across a temperature dependent control valve.

I am using Pro II and trying to simulate a process heater using a rigorous heat exchanger where steam inlet is throttled based on the outlet temperature of the process fluid. My design case has delta T as 20 deg. C and turndown case has delta T as 10 deg. C. The process fluid flow rate is constant and steam flow is required to be throttled in the turndown case.

Thanks

[Zauberberg]

Nothing uncommon - that is exactly how the equipment works in reality. By opening or closing steam control valve the pressure in the exchanger channel head varies, thus varying the condensing temperature of steam. The steam header pressure is constant, and by varying control valve position you are varying DP across the valve, and the channel head pressure changes accordingly.

Read more in the attached file:

Attached Files

•  Steam Heaters.pdf   83.67KB   57 downloads

[go-fish]

Nothing uncommon - that is exactly how the equipment works in reality. By opening or closing steam control valve the pressure in the exchanger channel head varies, thus varying the condensing temperature of steam. The steam header pressure is constant, and by varying control valve position you are varying DP across the valve, and the channel head pressure changes accordingly.

Read more in the attached file:

Thank you for the reply. Is there any way by which I can get dP across the steam control valve for various positions like 100% open, 70% open, 50% open? Does simulators have any in-built library from popular control valve vendors where I can just select % opening and the output automatically adjusts the pressure?

[Zauberberg]

You can try to play with that in Dynamics mode. Size the valve based on the information you have and Solver will calculate DP values based on flow-DP correlations. If you don't have any information about the valve, size it by yourself and plug design figures into Hysys - it shouldn't be more complicated than that.

For general valve characteristics, download: http://www.documenta.../book/cvh99.pdf or: http://www.engr.sjsu...otes/OZ1000.pdf