Expander Main Window
This window is used to specify the input data for the expander. The minimum input data requirements are entries for the outlet conditions -- pressure or work to be generated, and its adiabatic efficiency. If the outlet pressure is specified, PRO/II calculates power recovered and the resulting outlet temperature. Alternatively, specifying work determines the corresponding letdown pressure.
Pressure or Work Specification (required)
Select one of the following parameters and enter its corresponding value:
Outlet Pressure : The pressure of the product stream leaving the expander.
Pressure Ratio : The ratio of the outlet absolute pressure / inlet absolute pressure. This value must be greater than zero and less than one.
Pressure Drop : Decrease in outlet pressure over the lowest feed stream pressure. This value must be positive.
Work : The desired amount of power to be produced by the expander.
A relative tolerance (0.001% by default) is used to converge the calculations when work is specified.
Efficiency Specification
Adiabatic Efficiency
The default efficiency of the expander is 100%, which can be changed if desired.
Polytropic Efficiency
The default efficiency of the expander is 100%, which can be changed if desired.
Outlet Temperature Estimate (optional)
Supplying a good estimate for this value often speeds convergence.
Minimum Outlet Pressure (optional)
Supplying this value when work is specified allows PRO/II to reset the work specification, if the calculated outlet pressure is less than this minimum value.
Alternatively, instead of entering a value for most of the above parameters, the numeric values may be referenced using the Define system to any available unit operation or stream parameter calculated elsewhere in the simulation. See Expander Parameters Available for Cross-Referencing for more details.
Product Phases Button
If there are two or more product streams leaving the expander, this button becomes available. You must then specify the phase condition of each of the product streams through the Product Phases Window which is displayed when this button is pushed.
Refer Isentropic Calculations in the PRO/II Reference Manual for complete technical details.
Related Topics
Expander Unit Operation - Technical Information