2 replies to this topic

Hi, 1st time to be here to ask for the help from you.

Steam turbine is modeled in Hysys with expander module. Performance curve(AVF-Power-Efficiency at different speeds) from vendor were inputted into expander module. At the discharge of steam turbine, two phases of H2O is expected according to the design value of the process(It is a condensing turbine). As I expected the simulation results should show the same expander power with normal AVF at normal speed as I inputted in performance curve, but to my surprise, the operating point of expander is not at the performance curve, the calculated fluid power of expander by Hysys is lower than the value according to steam turbine performance curve.
But for the other steam turbines models which are back pressure turbines, the calculated fluid power can be exactly the same as that of performance curve.
Why does it occur, are there any special calculation methods in Hysys to calculate condensing turbine?

Thanks in advance!

[joerd]

Did you use the correct thermo package (ASME steam or NBS steam)?
Did you make sure not to overspecify your problem? For example, if you specify both power vs AVF and discharge pressure, Hysys will ignore the curve (I think).

Did you use the correct thermo package (ASME steam or NBS steam)?
Did you make sure not to overspecify your problem? For example, if you specify both power vs AVF and discharge pressure, Hysys will ignore the curve (I think).

joerd:
Thanks for your reply.
>>Did you use the correct thermo package (ASME steam or NBS steam)?
Answer: ASME steam is used.
>>Did you make sure not to overspecify your problem? For example, if you specify both power vs AVF and discharge pressure, Hysys will ignore the curve (I think).
Answer: Dynamic specification is as below: Duty of expander is specified, also the option of "Use Characteristic Curve" is checked.
Speed controller is used to control the turbine IGV OP then to control the expander speed.
The specification way is also as same as other back-pressure turbines.