5 replies to this topic

[arun.psarathy]

Dear all,

 

I have a spherical tank to store butadiene at -5°C. The amb conditions are 35°C. the sphere is insulated(PUF Insulation, 35mm) cladding type. my doubt is that will there be any gap inbetween the cladding and if yes then how can one estimate the amount of condensation in those gaps. logically there should be some small gaps between the claddings and there will be condensation in these gaps which can in due time result in rust formation.

 

I want to calculate the amount to condensation of water droplets in these gaps on the sphere surface.

 

Thanks in advance

 

 

 

 

[gregga]

I am not sure I understand your question.  Are you concerned about the gap between the wall of the vessel and the insulation or concerned about the gap between sections of insulation butting together? 

 

First of all, you should have a good coating on the metal surface before the insulation to provide protection of the metal surface if (when) moisture is present.

 

If the concern is the former, you can do a calculation of heat passing thru layers to determine the temperature of the air layer. 

 

If the concern is the latter, I suggest using two layers of insulation such that the seams are overlapped.

 

I don't think you are going to have puddles of water condensing and running out the bottom.

[Art Montemayor]

arun.psarathy:

 

In my experience dealing with the type and quality of insulation you are describing, I recommend you not waste your time trying to "calculate" the quantity of water droplets that are going to form on your vessel's outer shell, directly below the insulation.

 

First of all, you are not going to have water droplets.  What will appear will be solid water ice chunks that will progressively grow as time goes by.  Eventually you will have to rip out all the insulation and re-install new insulation and, hopefully, a good VAPOR BARRIER.  A vapor barrier is the key and most important feature to a sucessful low temperature insulation installation and it rests on the detailed specifications of the owner and the skill and abilities of the installation contractor.  Even the most successful vapor barrier ever applied will eventually degrade and allow atmospheric moisture to creep into the crevices between the tank wall and the insulation, depositing ice crystals.

 

That is where your time and efforts are better spent and not on generating academic calculations.  I have never heard of anyone trying to do what you describe - and I seriously doubt if there exists a credible algorithm that would predict what you seek.

[arun.psarathy]

Gregga:

 

 

i was referring to the gaps in between the insulation sections..

[arun.psarathy]

Art Montemayor:

 

 Thanks for your comments...  we are also going ahead with two layers of vapor barrier on the sphere.

[breizh]

My experience with Butadiene in Indonesia producing latex tells me nothing to worry , just perform the normal maintenance on your sphere and make sure no insulation is missing .

 

Breizh