Typically 150 000 m3/h actual flow of air is something I have seen for axial; this figure is for ambiant air conditions at inlet, on hot site (40 degC) but spinning at much higher speed then yours.
since air MW=28 is about two times the MW=18 of water (very roughly) and if I keep mass flow constant, this would correspond 300 000 m3/h actual flow for the steam. You can calculate back the mass flow based on 40 degC and then lower it further to match your temperature.
Also to precise that my minimum is defined to be 'Minimum axial = maximum centrifugal'...
Remember I have made a comparison based on different speeds, so be carefull...
I think when flow is defined; 25kPa has more to do with adding more stages to the axial machine...
Except if you perform a precise calculation/sizing, procedure would be that by knowing number of stages and speed, you could define diameter or blade height at inlet and then minimum flow would follow.
My guess only....
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