Pump Hous Intake design

[escheir]

Hi everybody,

What do you think about a pump house intake design with two vertcal turbine pumps positioned in line, one behind the other, in a narrow channel.

Any comments?

Erik

 

[SlideRuleEra]

Do both pumps be operate simultaneously? Or will only one, or the other, but not both, be in use at any given time?

http://www.SlideRuleEra.net

 

[rmw]

Vertical sump pumps have tight parameters with respect to distance from the bottom, side and rear walls. I think the first pump in the series would have issues whether or not both pumps ran simultaneously, while the second one would be OK, assuming its sump dimensional requirements were met.

rmw

 

[ccfowler]

It certainly does not seem to be a good idea. It would be much better to segregate the flows well upstream of the two pumps. If you have to use this arrangement due to space constraints, I suggest that you be very careful and creative in splitting the flow passage.

 

[vanstoja]

Where space constraints exist, such as in shipboard pump piping, as many as three centrifugal pumps operating off a common inlet header have been used without necessarily creating problems. Ideally, the inlet piping takeoffs from the header should have identical geometries, ie, same length and same bend angles (if needed) otherwise pumps operating together in parallel can have slightly different performance due to differing inlet flow angles to the impellers which can cause system flow instabilities. It is better that the last pump in line for a common header have a 90 degree bend takeoff into the inlet pipe (rather than a tee) because a "deadend" piping termination in the header beyond the last tee connection can create blockage at the takeoff point with distorted inlet flow to the last pump.

 

[Artisi]

how close together and how wide in realtion to the pumps.

as you can see from the comments already - an installation like this is suspect.

Naresuan University
Phitsanulok
Thailand

 

[tronical]

Why would you design it like that

if one pump is off, then that stationary pump is just uselessly adding losses as the water has to be pumped through these tight clearances.

if you think you need two pumps for that much extra head, you should get a bigger bowl and add more stages to the VTP.

if you think you need a standby pump in series incase of more head needed later, a vtp on top of it is not a good idea, neither is a vtp mounted horizontally else where.. what i would do is have a horizontal centri pump down the line, as many as you need. Have 2 parallel lines with valves to control the path of liquid, so when you need the pumps, you can control the fluid to go in the pumps line and switch on the pumps.

two vtps in serial? i dont think so


Tronical

 

[Artisi]

The concept of 2 or more pumps in line in a single inlet channel can be a problem, that is not to say that it cannot be done but the the physical dimenensions of the layout dictate that there are better arrangements usually using less real estate.

For interest - what size pump units are you talking about.

Naresuan University
Phitsanulok
Thailand

 

[ChickenSoop]

this is a bad design, but still if 2 pumps have to be run at once - you have to test them out first. If this is only at the design stage - don't build it this way.

For testing - be careful. Check pressure, flows and vibration readings. If you see any problems on testing - they will never work. If you run through the tests ok - put on vibration sensors and hook them into your control panel for constant monitoring and automatic shutdown.

If one pump chokes off the other - expect cavitation and turbulence, heavy vibration will take out the bearings, and maybe the whole rotating assembly.

 

[jonelv]

I may be in a minority from looking at the other posts but what you describe looks to me like a 'trench type' sump arrangement. I have seen these arrangements with multiple vertical pumps work well. The design parameters for such sumps are covered by ANSI/HI. The higher velocities present may well be beneficial if you are pumping sewage or similar. A word of caution though - such arrangements may well be more prone to vortexing or pre-rotation problems than more 'conventional' sumps particularly when operating pumps in parallel and would almost certainly require correct use of baffles, cones, splitter plates etc. A hydraulic model to make sure you get the design right is strongly recommended. So if you need a small footprint solution or self-cleaning sump is important then such sumps may well be acceptable. Hope this helps.

 

[stanier]

You should invest in Pumping Station Design SANKS. this classic texts includes good and bad designs.


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