6 replies to this topic

[zorro1234]

Hi all, 

 

I'm trying to find more information on hotwell design for barometric condenser tail pipe seal and found few confusing info. Read documents attached.  

 

I'm actually facing problem in my plant where the vacuum pump is drawing the barometric water in the hotwell tank to the pump discharge. 

 

I was told that is due to insufficient submerge height of the seal pipe due to insufficient hotwell volume but I has doubt on this. 

 

My condenser tailpipe outlet is 11m above the hotwell, and my tailpipe is 700mm submerged if measured from the hotwell overflow line. 

 

Could anybody advise the hotwell volume design for a proper barometric leg seal ? 

 

Thank you. 

 

Attached Files

•  OMI_BARO_1097.pdf   169.28KB   29 downloads
•  213.PDF   87.04KB   27 downloads

[Bobby Strain]

You should illustrate your system.

 

Bobby

[zorro1234]

Hi Bobby, 

 

Please find below sketch that explains the system. 

 

Water is gushing out at the vacuum pump vent even when the system is just doing vacuum test with no load.  

 

Thank you. 

Attached Files

•  Capture.PNG   31.18KB   4 downloads

[breizh]

Hi,

Some literature to support :

https://www.bicmagaz...arometric-legs/

 

Underneath a design with volume consideration (page 228) .

http://www.iqytechni... Technology.pdf

 

What is the volume of your barometric leg versus the volume of the tank (part immersed) ?

Is your barometric leg a single pipe ? No flange ?  

 

Good luck 

Breizh

[katmar]

You are definitely breaking the seal at the bottom of the barometric leg.  The clue is that you are pulling water over an 11 m height, which is normally impossible.  The only way I can see that you would find copious amounts of water reporting in the vacuum pump is if air is being drawn in through the bottom of the barometric leg.  This air will lower the density of the fluid in the barometric leg and this would result in more than 11m being required to balance the vacuum.  You are basically using the barometric leg as an air-lift pump.

 

You have omitted 2 critical dimensions that would allow us to evaluate the design.  The volume of water that is provided by the hotwell when the level drops by 700 mm must be sufficient to fill the barometric leg to around 10 m.  Unless we know the ID of the hotwell and of the barometric leg we cannot calculate whether or not this is a problem.

 

Don't forget also that when you shut down the vacuum pump the water in the barometric leg will rush down into the hotwell.  There must either be sufficient headroom above the overflow pipe from the hotwell to accommodate this, or you need a large overflow pipe.

[Bobby Strain]

It's also possible that you have damage somewhere that restricts flow in the downpipe. Or, maybe a leak in the downpipe that allows air entry. Is this a problem with an old installation that has recently occurred? And, you should note when it was observed and what else was happening at the time. That's where you should always start an investigation.

 

Bobby

[latexman]

What kind of vacuum pump, please?