Has anyone seen ( ie can refer me to Companies, locations , Industries , etc ) or operated centrifugal pumps both as a pump and then in reverse as a power recovery device all withthe same unit ?
There are peek hydro power stations operating like that. They are called “reversible” as far as I remember. During periods of low power demand they pump water in a reservoirs-lakes well above their level but at demand peeks they operate as turbines. Therefore when operating as a pump that turbine/pump impeller should be coupled to a power source and when operating as a turbine to a generator. Or maybe there is something like electrical motor/generator, which can be switched to either mode.
I haven’t seen that turbine/pump impeller but it could well be something resembling a centrifugal pump impeller and at the same time a centrifugal turbine rotor. Maybe those two things don’t differ a lot (for incompressible fluid - water) in which case it was quite easy to design something in-between.