7 replies to this topic

[Azeotropic Thunder]

Hi,

 

I have a 30,000L vessel rated for -7 mbarg vacuum.

 

The vessel holds hot water with traces of HCl.

 

The vessel has an 8" vent which connects to a vent header that goes through a wet scrubber and extract fan. Several other similar vessels also vent to this same scrubber.

 

The vessel is typically at atmospheric pressure or very slight vacuuum.

 

The vessel has an open 4" overflow pipe, that also acts as a vent.

 

The vessel has a 4" bottom outlet.

 

The vessel has no vacuum breaker.

 

if the vessel overflow gets blocked, and I empty the contents of the vessel, will I create a vacuum and possibly implode the vessel? or will the vessel in-breath some air from the scrubber extract system?

 

 

Many thanks!

[latexman]

if the vessel overflow gets blocked, and I empty the contents of the vessel, will I create a vacuum and possibly implode the vessel?

 

Yes, and maybe.  What is the maximum suction pressure (0 flow) of the extract fan?

 

or will the vessel in-breath some air from the scrubber extract system?

 

Yes, probably.

 

Without an accurate P&ID and fluid flow calcs there is uncertainty. 

[fallah]

Hi,

 

I have a 30,000L vessel rated for -7 mbarg vacuum.

 

The vessel holds hot water with traces of HCl.

 

The vessel has an 8" vent which connects to a vent header that goes through a wet scrubber and extract fan. Several other similar vessels also vent to this same scrubber.

 

The vessel is typically at atmospheric pressure or very slight vacuum.

 

The vessel has an open 4" overflow pipe, that also acts as a vent.

 

The vessel has a 4" bottom outlet.

 

The vessel has no vacuum breaker.

 

if the vessel overflow gets blocked, and I empty the contents of the vessel, will I create a vacuum and possibly implode the vessel? or will the vessel in-breath some air from the scrubber extract system?

 

 

Many thanks!

 

You should do a hydraulic study on whole system including emptying and vent lines to evaluate if in-breathing rate would be adequate to prevent the vessel to be subject to the higher specified vacuum (-7 mbarg)... 

[breizh]

Hi,

Pay attention, an overflow is not a vent!

Do you have nozzles available on your tank?

Breizh 

[shvet1]

Subject to hydraulic study

[Azeotropic Thunder]

 

if the vessel overflow gets blocked, and I empty the contents of the vessel, will I create a vacuum and possibly implode the vessel?

 

Yes, and maybe.  What is the maximum suction pressure (0 flow) of the extract fan?

 

or will the vessel in-breath some air from the scrubber extract system?

 

Yes, probably.

 

Without an accurate P&ID and fluid flow calcs there is uncertainty. 

 

max suction pressure of fan is -35 mbarg

[latexman]

 

 

max suction pressure of fan is -35 mbarg.

I have a 30,000L vessel rated for -7 mbarg vacuum.

 

The potential for a problem is there.  To prove there is no problem requires a fluid flow study.  It's probably easier and cheaper to size and install a vacuum breaker on the tank.  As breizh asked, do you have any spare nozzles?  Or, can you tee into an existing nozzle for this application?

[breizh]

Hi,

To me, performing hydraulic calculation is always good (clean equipment) but how do you take into account the packing of the column clogged over the time.

You need an additional device to protect your tank in case of vacuum.

Breizh