Absorption tower, sulfuric acid production 1

[ali-gct-meca]

Hi,

I work as a mechanical engineer in a plant for the production of sulfuric acid, we are going to reconstruct an absorption tower : where acid is sprayed form the top ... as it descends, it comes to contact with a gaz going in the opposit direction ... hence the absorption ... i am wondering about the codes and standarts that are used for the design of such equipement ASME or API 650, knowing that the gaz pressure does not excced 1.15 bars, my reaserch through the internt guided me to believing that most towers are designed according to ASME, but we have a flat bottom , and i know for a fact that ASME does not deal with flat bottom tanks
Can any one guide me !

 

[JStephen]

"1.15 bar = 16.679339871 pound/square inch"
In the US, state boiler and pressure vessel codes will generally require ASME for vessels/ tanks over 15 psi.
Elsewhere in the world, that could vary and you'd need to confirm local requirements.
As you note, ASME does not address flat-bottom tanks where the bottom is supported by the foundation, rather than by its own rigidity.
If the vessel is small enough, you could still use a flat head or blind flange designed per the code.
Otherwise, consider a skirt or legs with formed bottom.

API-650 addresses tanks up to 2.5 psi.
API-620 addresses field-erected tanks up to 15 psi and is sometimes used for shop-fabricated tanks as well.
I'm not familiar with this application, so I can't say what's "usually" done.

 

[MJCronin]

Can you post pictures of the old tower ? ... Are any old plans available ?

Is there a PID available or other document showing temperatures as well as pressures ?

Can you provide details or pictures showing where it has failed ?

MJCronin
Sr. Process Engineer

 

[HTURKAK]

Er. ali-gct-meca (Industrial),

The info that you are looking for is more than analysis of a PV .. If the only info. is the analysis of absorption tower with design pressure 1.15 bars , that will be probably the easiest part of the problem..In this case, with a hybrid approach, you may perform the design analysis as per ASME PV code for the upper portion and API -620 FOR the flat bottom..

However, process design ,the material selection, acid resistant lining, packing and supporting system ... and performance requirements..are more curucial

I will suggest you to look past info ( as built docs..) and get in touch with original licence provider and equipment supplier..

http://www.sulphuric-acid.com/techmanual/strong acid/sa_towers.htm

 

[ali-gct-meca]

MJCRONIN,

Please find attached the required scketches

 

[JStephen]

That configuration would lend itself to an API-620 design. If possible, reduce the pressure to 15 psi and use API-620. Otherwise, add a bottom F&D head with skirt support. If there are no legal requirements to the contrary, you could design it as a non-code vessel using API-620 design and higher pressure than covered by API-620, but that is a less desirable procedure.

 

[ali-gct-meca]

Thank you everyone, that was truly helpful

 

[MJCronin]

Better quality and better quantity information always gets you better answers ....

MJCronin
Sr. Process Engineer