Centrifugal screw pump or impeller 3

[Shafayat Ahmmed]

Hi Altruists,
I have attached a photo of a pump shaft with impeller.
I have come to know about centrifugal screw pump but here in our power plant i have seen a turbine drainage pump (it pumps condensate to a tank than to WTP again) which have both screw impeller and closed impeller.
Can anyone tell me which type of pump is this and how does this work?

 

[Compositepro]

This is a centrifugal pump with an flow inducer at the inlet. The screw allows the centrifugal pump to operate at a lower NPSH (net positive suction head) without cavitation. Hot condensate can flash into steam with the slightest drop in pressure.

 

[Shafayat Ahmmed]

Thanks Compositepro!!
I am here only for a week now and already impressed by the help i am getting.
Hope one day i can also contribute.

 

[LittleInch]

Can't add anything to that. It works by gently helping the flow into the eye of the impellor to reduce NPSHR.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EdStainless]

And don't be surprised if you see other ones of these and they look very different.
Each pump mfg tends to use their own style.
These are also used in cases where you know that you are pumping a two phase flow and want to prevent the gas from collecting and blocking fluid entrance to the eye.

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P.E. Metallurgy, consulting work welcomed

 

[bimr]

fixing an inducer to combat cavitation in pump: