Emissions abatement help 1

[shaunmiller]

Looking for a little info on scrubbing techniques to help with the BAT (best available techniques)section of a PPC application. What I would like to know is:

Possible methods of scrubbing a low volume, low conc (20-250ppm)VOC(isopropyl alcohol) stream, and their advantages/disadvantages. Already searched for possible ways to scrub VOC's but could find no design info, basically want to demonstrate that it is not economically feasible to scrub these emissions.

Ways of scrubbing acid vapours (HF, HCl, HNO3 mix)and alkaline vapours(ammonia, caustic) other than using wetted packed columns. Especially any info on dry scrubbing techniques. Again, want to justify the use of wetted packed columns to perform the scrubbing operation as opposed to other techniques.

Any information is much appreciated.

Cheers
Shaun.

 

[siretb]

1) alternate scrubbing mthods, other than packed columns
acid gases

wet: trays; empty towers with special nozzles, using either lime, limestone, caustic or sodium carbonate.

the advantages of wet are: superiore removal efficiencies. Low stoechiometric factors, good efficiency for heavy metals

dry: well etsablished. maion drawback is the stoechiometric factor, much above one, meaning a fair amount of contaminated solids to be disposed of

semi-dry: well established, stoechiometric ratio less than with dry, but much above 1.

ammonia: two options
wet, using acidic scrubbing. usually done at the same time as HCl/Hf removal, in the same scrubber
catlytic: using SCR NOx removal catlysts
dryt does not work and semi dry does not work

isopropanol/VOC
the wet option is to add activated carbon as a slurry in your column. Patented.
the dry option is to pass the gases through an activated carbon bed, and steam regenerate (if concentration is high enough) or just dsispose of the spent carbon (low concentration)
RTO and reburning is a good way to get rid of large concentrations of carbon.
It is also possible to absorb the isopropanol in an organic solvent, and regenerate by distillation. I doubt that with only 250 ppm it is economical.


To sum up, I think that a properly designed system, with two columns, is capable of handling your problem. The VOC problem will be dealt with by activated carbon injection, .
For acidic components, best reagent is Caustic, but if flowrate is high, consider limestone.
A ^packed colmmun is usually a good choice, because you mention low volume.
Hope this helps

 

[shaunmiller]

Siretb, thanks for taking the time to reply to my post, the information you have provided is very useful.

Regards,
Shaun.