8 replies to this topic

[Julien123456789]

Dear All,

I have a basis question on surge phenomenon of compressor.

Could you explain me  shortly what is it and when does it happen ?

I am trying to read something on the internet but it is hard to understand for me now.

 

Thank you so much,

 

Julien

[fallah]

Julien,

 

Surge in centrifugal compressors is a condition following which the amount of gas to be compressed by them isn't sufficient for the speed of the compressor hence the blades lose their forward trust causes the reverse flow of fluid then reverse movement of the shaft...

[Julien123456789]

Thank you so much Mr. Fallah,

In my opinion, whenever a compression is still in service in a closed system, the discharge pressure  at compressor outlet nozzle seems always bigger than its at inlet nozzle.

How can it cause a reserve flow ?

Why don't we hear this problem on a centrifugal PUMP ?

 

Julien

Edited by Julien123456789, 29 April 2016 - 11:35 AM.

[fallah]

Julien,

 

Yes, in a working compressor the discharge pressure is always higher than the suction and based on this reason when the demand to the discharge flow will be zero or lower than a minimum value (corresponding to the surge point) the flow can be reversed from high pressure side i.e. discharge to low pressure side i.e suction side through the compressor itself otherwise the antisurge line/valve facility is already provided. 

 

The pumps also will be protected by minimum flow line recycled back to the suction line or suction vessel. The reverse flow which can be occured in centrifugal compresors due to compressibility of the gas and potential of the energy stored in a compressed gas, cannot be happened in a centrifugal pump due to incompressibility of liquids and the energy which is transferred to the fluid by the pump will be mostly converted to thermal energy when no demand to the pump's discharge flow

[Art Montemayor]

This is a very important question that all Chemical Engineers should thoroughly understand and be prepared to deal with in the industrial world of gas processing.  This is not my opinion, but a fact of reality.  The subject is a complex one, but also one that can be enjoyably understood when explained by an expert in process machinery.

 

I have taken the liberty to copy just a short portion of Norm Lieberman's excellent treatment of the subject found in his book, "A Working Guide to Process Equipment" - a book that every chemical engineer should own, read, and study in detail.  In fact, every book published by Norm is a treasure house of valuable engineering knowledge.

 

I hope this helps out a lot of engineers that presently lack the expertise and knowledge of dealing with the subject of centrifugal compressor surge.

 

 What is a Centrifugal Compressor Surge.docx   339.97KB   96 downloads

[Art Montemayor]

All:

 

To add more emphasis and give additional leads on understanding not only centrifugal compressor surge, but also important practical engineering tips on solving everyday process problems in an operating plant or refinery, go to:   http://asknormlieberman.blogspot.com/

 

There, you will probably enjoy reading how Norm Lieberman solves everyday problems and gives some very expert engineering advice.  You will have access to videos showing Norm and his explanations as well as a listing of all his published books and how to purchase them.  I highly recommend everyone to visit this site and explore all the valuable information and hints that Norm gives.

 

I am attaching one of Norm's practical methods of explaining how a centrifugal compressor surge is controlled and why it is done that way.

 

 Centrifugal Compressor Surging.docx   965.81KB   63 downloads

[Julien123456789]

Dear Mr. Fallah, Mr. Art Montemayor,

Thank you so much for your valuable explantation and information.

This is a very good news for starting my week.

I take notes what you mean.

 

Have a nice day,

 

Julien

[breizh]

Hi Julien ,

Consider the resource attached to support your work . This will supplement documents provided by Art and Fallah .

 

Hope this helps

 

Breizh

[Julien123456789]

Many thanks Mr. Breizh,

I try to get it !

 

Julien