On Monday, May 29, 2017 at 1:55:58 PM UTC-4, XCjEwCš›†� ï¼*ｉｇｈｔｙ •¬ ï¼·ï½�ｎｎï½�ｂｅ †’š›CkYyoU wrote:
wrote on 5/29/2017 1:04 PM:
On Monday, May 29, 2017 at 8:13:36 AM UTC-4, wrote:
On Sunday, May 28, 2017 at 4:04:30 PM UTC-4, wrote:
On Sunday, May 28, 2017 at 11:35:39 AM UTC-4, wrote:



You are over thinking the situation. A multistage pump has a bunch of identical sections all turning at the same speed. Each stage increases the pressure. So you might have a 6 stage pump with each stage increasing the pressure by 10 psi. Which makes for a fairly efficient pump which will supply water at 60 psi. Google it.


From Wik

Multistage centrifugal pumps
Multistage centrifugal pump[5]

A centrifugal pump containing two or more impellers is called a multistage centrifugal pump. The impellers may be mounted on the same shaft or on different shafts. At each stage, the fluid is directed to the center before making its way to the discharge on the outer diameter.

For higher pressures at the outlet, impellers can be connected in series. For higher flow output, impellers can be connected parallel.

A common application of the multistage centrifugal pump is the boiler feedwater pump. For example, a 350 MW unit would require two feedpumps in parallel. Each feedpump is a multistage centrifugal pump producing 150 l/s at 21 MPa.

All energy transferred to the fluid is derived from the mechanical energy driving the impeller. This can be measured at isentropic compression, resulting in a slight temperature increase (in addition to the pressure increase).



Dan

Thanks, Dan. I read that -- and maybe 100 more pages over the past few days. None of them really explain it. To say that the energy is derived from the impeller is axiomatic. It doesn't explain what's going on inside the second stage.

Rather than try to go through it in detail, I'll post something if I find a good explanation.


You don't have enough smarts to process too much information at once,
ED. Please do yourself a favour by looking at this impeller of a simple
centrifugal pump:

https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/bd60670ae9dc5e37fdc08142df0462d2/large.JPG

To give your brain a chance to comprehend, please imagine all the valves
are closed. The fluid is trapped inside the centrifuge, with no way in,
and no way out.

The impeller keeps spinning 'round and 'round. The impeller is trying to
throw the fluid (which is slotted in the empty space in the impeller)
radially outward. Because of this, the fluid is exerting pressure
radially outward against the wall of the casing.

Do you still have difficulty, Ed?

Thanks, Wannabe, but I understand how a centrifugal pump works. What I don't understand is the effect of feeding one with a high pressure head of water.