Distillation of Methanol liquor

[AUKevin]

Our process currently involves using hot water for extracting sodium chloride by-product from our powder. I am very interested in using MeOH in order to reduce the NaCl and other contaminates in a more timely manner. My questions are :
1) How hard would it be to distill and recover 2400 gallons of MeOH saturated with NaCl and water ?
2) Does anyone on this board currently recover MeOH at their plant ?

 

[DeltaCascade]

Need more info - what do you mean by "timely manner"?

I wonder if your original plant design already considered this, and perhaps rejected it in a screening study at the Design Basis Memorandum stage? I guess NaCl is soluble in MeOH, and that you will recover MeOH as distilate while separating it from the water-NaCl in the distillation column bottoms? You will be introducing plant fire hazards: MeOH burns with an invisible flame, etc. This alone may require costly plant layout changes?

Energy required for continuous distillation could be estimated with total mass and energy balance and relux ratio determination (a quick web search will help with that).

Good luck...

 

[AUKevin]

No, MeOH was not considered at startup. The "timely manor" I was talking about is referring to our current decant cycle time. We currently spend anywere from 10 - 12 hours decanting with hot water. The hot water works good enough for dissolving and carrying away the NaCl present, but does not help us with the other contaminants. Some of the other contaminants are organic-tin materials.

 

[DeltaCascade]

Interesting. A batch process with mineral salts AND organo-tins, etc, to be extracted, presumably from a fine powder. i guess your process is frequent enough to require recovery of methanol and not just evaporation or evaporation and flaring. one would also presume that the contaminant production can't be eliminated in the first place. i wonder what your industry is? what are you producing?
If you tell us more, we'd be better equipped to converse.
Depending upon concentrations, the NaCl would reduce organic salt contaminants' solubility in water (salting out). Perhaps introducing the water in stages, first stage to get rid of inorganic salt, and you may be able to get away with cold water for this, then decanting to remove all water, and then doing a second (or more) stage(s) with hot water (assuming no retrograde solubility) to remove the organic salts with NaCl-free water? You may be able to use less hot water and even less water overall? Just a thought. You are likely doing this already?
Info on contaminant solubilities in hot and cold water and in hot and cold salt water, and hot and cold methanol, would help. Is salting out an issue? Is leaching time required due to solid particle porosity and diffusion? Have you considered purifying the solvent for recycle with reverse osmosis to remove NaCl and activated carbon to remove organo-tins? Oops, the carbon would also remove solvent. Maybe there is a second membrane that would pass solvent but not the contaminant, enabling high % solvent recycle?
Methanol distillation is well established technology, of course .. but it sounds like you may just need to flash or evaporate it and condense it to recycle essentially all of the solvent? Why would you need to separate the water from the methanol? Can you demonstrate that the organic contaminants won't decompose and distill or just distill over with the methanol? Your batch frequency would enable sizing of equipment and operatingn costs.
Nuff said from a non-specialist in this area!? Hopefully we'll hear more. Good luck.

 

[AUKevin]

Delta,

I would be glad to discuss this further, but via e-mail. I really don't want to disclose any more about our process here on the internet. Leave your e-mail addy

 

[sriramchemical]

I have a mixture of Tetrahydrofuran and water in the ratio of water 5 % and the rest tetrahydrafuran.I want to have Tetrahydrafuran with water content of less than 0.05%. can any one suggest some techniques to solve my problem.

 

[johngerhart]

recovering methanol from water is very common , well documented in the literature and often used as a sample for college courses . There are lots of configurations ; this is an energy intensive separation . Penn State has modelled it .