methanol vapor condensation

[atiaran]

I have an application where 22,500 cfm of plant exhaust air contains 1500 ppm of methanol vapor. We are looking at various technologies to treat, and someone mentioned condensing the methanol to bring the concentration down before sending the remaining air to APC equipment. Would this actually accomplish a reduction? Wouldn't there be a secondary stream of condensed methanol and water that would need to be addressed?

Thanks.

 

[Montemayor]

atiaran:

To add any help, experience or recommendations we have to have some basic data:

1) What is the composition of you gas stream? Is it saturated with water?

2) What is the gas stream's temperature (& pressure)?

3) State the TYPE of MeOH ppm you mean. As a chemical engineer you know this is not obvious since it can be on a volume or a mass basis. Without knowing this specifically, nothing can be discussed on a serious level.

4) What is your scope basis? i.e., it it to economically recover the MeOH? Or is it to remove the MeOh for subsequent "clean" emission of the gas to the atmosphere?

All the above are essential in order to evaluate what can be done. Presumably you are presently considering adsorption (using Activated Carbon?) as a viable candidate solution. Cooling-condensing such a large gas stream (especially at low pressure) can be exorbitant - although this is not enough reason yet to discard it.

Is this an academic engineering problem or a real life application?


Art Montemayor
Spring, TX

 

[atiaran]

1) Assume that it is saturated with water.
2) Temperature is ambient. Unsure of pressure in ducting to outside atmosphere. (Client does not know).
3) Concentration is ppmv.
4) Recovery of MeOH is not goal. The idea was that it would reduce the concentration of the methanol in the airstream to make the APC potentially less costly.

Carbon and biofiltration are the current technologies being evaluated (real life). A 90+% removal efficiency is desired. The ppmv is high for a biofilter to achieve this, but the client seems intent on trying a configuration that will include biofiltration.

I personally don't think condensation is a feasible (read cost efficient) option to combine in the solution, but I must pursue it to satisfy the client's questions and curiosity.

Thanks.

 

[saxon]

atiaran, Instead of looking at end of pipe treatment for the VOC, first take a look at the source of the VOC emission and reduce it or eliminate it there if possible. This may eliminate the need for pollution control equipment at the end of pipe. It will certainly also help the overall material balance of the plant, which will reduce operating costs.

Hope this helps.
saxon

 

[tjsharpe]

Have you looked at a molecular sieve solution? Some of the new materials are custom designable for higher specificity. NASA has worked in this area on a small scale that may be upgradeable.

 

[25362]

Since it has been said that methanol is removed from air by rain, would it be logical and practical to think about a chilled water scrub to catch methanol from an air stream ? See the pertinent environmental impact section in

http://www.speclab.com/compound/c67561.htm