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Pump Surge

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#1 Ericp

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Posted 25 March 2015 - 09:40 AM

Hi I am new to this forum.
 

I have a question
Are surge and water hammer different ?
Can the pump line experience surge if pump trips ? or power failure. if yes, I am not able to understand how ? 
Will the case be same for compressors too ?
if anyone have good article about pump and compressor surge and  water hammer can you please upload it for me. 

 

Thanks
Eric
 



#2 fallah

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Posted 25 March 2015 - 12:09 PM

Eric,

 

Can the pump line experience surge if pump trips? Or power failure...

 

Yes,  mostly due to sudden fluid velocity change from the value corresponding to normal flow rate toward zero....The case will be the same for compressors too, but with much lower intensity due to handling the gas rather than liquid...

 

By Googling you will find many materials regarding the surge...



#3 Zauberberg

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Posted 25 March 2015 - 12:19 PM

I haven't heard of cases of surging in gas lines, since gas is compressible fluid.

 

On the other hand, surging might occur in long distance liquid lines, depending on many conditions. Surges do not occur in short in-plant process piping. There is not enough liquid mass to develop high momentum.

 

Recently I have come across an interesting article on water hammer traveling over 10km long water line. The article is attached to this post.

 

Attached Files



#4 Shauno

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Posted 07 April 2015 - 09:43 AM

I have done some water hammer analysis (a.k.a surge analysis/transient analysis) modeling in the past. I have done this for water and liquid propane and have had accurate results for both. A good software to use is AFT Impulse- it's easy to use and their manual provides enough info to get started. The attached document describes the basics of the phenomenon, analysis and there is a plethora of other documentation you can find via Google (including a free demo of AFT Impulse).

 

As for compressor surge, I don't have a lot of experience with it but my understanding is that as a centrifugal compressor discharge is restricted, the discharge pressure rises and this can result in a flow reversal through the compressor (e.g. pressure moves from discharge through compressor to suction). As a result, there is a pressure wave that will move back and forth through the compressor. To prevent this, most large centrifugal compressors have surge control systems that prevent the compressor from operating too far back on its curve- this is done by opening a recycle valve/flow path when flows and pressures reach certain criteria (i.e. min flow or high discharge pressure).

 

Hope this helps.

Attached Files






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