15 replies to this topic

[dpunnn]

I had a problem in the toluene gas line after the packing scrubber (without water).

 

The toluene gas (I highlight yellow) is supposed to exit through the roof chimney in gaseous form, but in fact after exiting the chimney it is condensed (in acidic condition) thus corrosive the surrounding area underneath.

 

I am thinking of making a new line to connect the chimney into a closed tank filled with water, so that the toluene gas does not escape, but mixes with water and is discharged into the ditch.

 

What do you guys think, experts here?

 

Thanks for your attention.

 

I also attached the drawing.

Attached Files

•  Screenshot 2024-08-07 154650.jpg   63.65KB   1 downloads

Edited by dpunnn, 07 August 2024 - 03:51 AM.

[breizh]

Hi,

 

An option is to use activated carbon to clean the gas stream after absorption step.

Note: I've difficulty to read your PId , a simple sketch will help.

Edit: Toluene is carcinogenic material, it cannot be released t atmosphere without treatment, same to water drain.

You definitely need to talk to your supervisor and or the safety manager at your place.

Breizh 

Attached Files

•  activatedcarbonfilter.xls   179KB   6 downloads
•  carbon adsorbers chapter 7th edition.pdf   1.02MB   7 downloads

[Pilesar]

Toluene does not mix with water. Your short description of this process suggests much hazard.

[shvet1]

common problems have common solutions

https://eippcb.jrc.e...emical-sector-0

https://eippcb.jrc.e...chemical-sector

Edited by shvet1, 09 August 2024 - 04:22 AM.

[carlos infante]

Toluene discharged to the environment is forbidden at any country, it is a cancerígenas substance.

 

Be careful 

 

carlos

[shvet1]

incorrect

Toluene is classified as group 3 "Not classifiable as to its carcinogenicity to human"

https://monographs.i...ed-by-the-iarc/

 

This is the reason why toluene is so popular as solvent and thinning agent.

[breizh]

Shvet1,

your comment about "popular solvent" is not relevant, extreme care is required using this chemical. Same for Xylene/Benzene.

https://pubmed.ncbi....ih.gov/3053447/

Consider reading the link above.

Breizh

[shvet1]

Sorry, breizh

I had tried and found no references that toluene is not a popular solvent. All my personal experience tells me the opposite.

Concerning 'extreme care' and links - see the page of relevant US authority, toluene is still not classified in US/EU or any other jurisdiction as cancerogenic or extremely toxic

https://pubchem.ncbi...fullscreen=true

 

Toulene is reasonably cheap, readily available on demand at any volume, having low VP, low toxicity, high affinity to hydrocarons, totally soluble in most non-polar substances, chemically stable, well researched - for this reason toluene is an attractive carrier, ballast or solvent in process industry, particularly in a topicstarte's chemical facility.

Edited by shvet1, 12 August 2024 - 09:14 AM.

[shvet1]

@dpunnn

in addition to the files posted above see

https://www3.epa.gov...r1/fadsorb.pdf 

[dpunnn]

thank you for the answers and references, I have explored some of the references you provided. 

I am interested with technology of Condensation Scrubber, Cyclones, and carbon adsorber, but I actually just want a simple way, because it's only for a small amount of toluene and a limited budget.

 

Thank you also for the reminder regarding the hazards of toluene, in this factory toluene is used as an organic solvent in the liquid-liquid extraction tower, the residue of this toluene is in the form of gas which I try to eliminate through the vent / chimney pipe, but it becomes condensation (maybe included in the water condensate). I have simple PFD and my plan for overcome this trouble (attached). But i concern with flammability hazard of toluene.

 

what do you experts think?

 

Thanks

Attached Files

•  My Plan.jpg   41.81KB   0 downloads
•  Simple PFD.jpg   41.47KB   0 downloads

[shvet1]

...this toluene is in the form of gas which I try to eliminate through...

eliminate or recover?

[dpunnn]

...this toluene is in the form of gas which I try to eliminate through...

eliminate or recover?

Thanks for your reply,

 

 I try to eliminate / remove, not to recover

[shvet1]

In your case an exhaust air treatment system will be more expensive than this liquid stripping system as a whole. Excessive solvent losses are a part of this process design and therefore are hard to be overcome.

think twice before suggesting modification options to bosses

 

To achieve a distinguishable result a mist eliminator can be added above the liquid distributor. This options is still some sort of palliative care but may be enough to achieve your goals.

Edited by shvet1, 13 August 2024 - 05:43 AM.

[dpunnn]

 

In your case an exhaust air treatment system will be more expensive than this liquid stripping system as a whole. Excessive solvent losses are a part of this process design and therefore are hard to be overcome.

think twice before suggesting modification options to bosses

 

To achieve a distinguishable result a mist eliminator can be added under the liquid distributor. This options is still some sort of palliative care but may be enough to achieve your goals.

 

Dear shvet1, thanks for your reccomendation, I will learn this item "Mist Eliminator". I think it's a great option for this matter.

[shvet1]

for a brief view consider the 'demister' device fotos and drawings under this link 

https://vff.com/file..._130421_WEB.pdf

[breizh]

Hi,

Can you share a mass balance of your system and let you provide data about your operation system (T,P), including the liquid recycled stream?

Can you share the details of the column (diameter, packing height, packing material, packing size) to evaluate the existing design?

 

Note : Water and Toluene forms an azeotrope. Toluene is not soluble in water.

 

One option,if you don't want to consider adsorption right after the scrubber, is to cool down (HX) the gas stream and to split the mixture (non-condensable + condensable material) in a separator Liquid/Gas. 

Most probably you will need a Canister with A/C to clean the residual Toluene in the gas stream prior to atmosphere.

The liquid phase (condensate) should be routed to a decanter to separate Organic phase (toluene) from aqueous phase (water).

 

Hope this is helping you.

 

Breizh

Attached Files

•  Air stripper.pdf   1.99MB   3 downloads