VOC absorption process tips 1

[cpspower]

hi guys
can you recommend a VOC (mainly ethanol and ethylacetate) ABsorption process? (note: not ADsorption !)
I have seen some suggestions based on oils.
Why can't I use water as an absorbent?
thanks a lot!
Andreas

 

[siretb]

Ethyl acetate is not much soluble in water, but has some solubility.
A scrubbing process design with water is certainly feasible, the operating conditions L/G would depend on the concentration.
Also, you have to decide if you want to reclaim the product (ethyl acetate will slowly react with water to yield ethanol and acetic acid).
After the water has grabbed the ethanol and the EtOAc what do you do?
distillate and get the products (along with acetic acid). this will not be easy.
do a liquid liquid extraction (then why not use a oil in first place?)

So the problem is not remove the components from the gas, but is: recover them after. Yet some design could probably work, but we would to know more about your requirements, constraints, and other data.

 

[bimr]

It would be helpful is you gave some preliminary dscription of your process or industry.

 

[cpspower]

hi again
it's basically about removing ethanol and ethylacetate from an air stream at 1 atm and room temp. The concentration of the two is quite low, about 0.5% (together) of the air massflow. I am looking for a solution with water as absorbent if possible.
thanks again!

 

[cpspower]

I forgot to mention the most important thing! the primary purpose of the process shall be to recycle both the ethanol in the purest form possible...
cheers
Andreas

 

[786392]

Ailthough fairly good advice already you have,
I feel; as if some inert atmosphere may be nitrogen blanketed KOD or knock out vessel) be employed with the subject stream of air containing the liquids of interest are "knocked down" with some impingement plate 45 degrees from vertical.Thus making liquids separate from this and

thereafter some further treatment steps might be needed to "collect" , "separate" and subsequently recycle the two liquid streams of interest 'as pure as possible'.Nitrogen blanket may help
1) improved purity.
2)Fire/Ignitable mixture formation possibilities.

Best Regards
Qalander(Chem)

 

[siretb]

Hello

As told such process is feasible. The recovery of the scrubbed ethanol and the scrubbed Ethyl acetate is feasible by distillation but is costly in terms of energy.
You may consider other options, like pervaporation.
Again Ethyl acetate reacts with water

EtOAc + H20 <--- equilibrium --> EtOH + AcOH

EtOAc ethyl acetate ; EtOH Ethanol ; AcOH acétic acid

Without spending much time, I cannot tell the extent of this reaction. With a packed column, I think it will be limited, but do not ignore it.

Considering that the enthalpy of vaporisation of oils is lower than the one of water, considering the hydrolisis reaction, I'd say that unless you flowrate is small, you'd be better off with an oil-based scrubber.