NMP recovery
NMP recovery
(OP)
I currently have an exhaust stream that contains the solvent NMP (N-methyl-2-pyrrolidone). I would like to condense the NMP in the exhaust and recover it to use as a solvent to clean or resell to others. The exhaust stream is at a temperature of about 120 degrees Celsius. The concentration of NMP in the exhaust is very low, somewhere on the order of less than 5%.
I am thinking that a chiller or heat exchanger should work for this. Does anyone have any suggestions regarding where I can find more information to help me develop this process?
Thank you in advance.
I am thinking that a chiller or heat exchanger should work for this. Does anyone have any suggestions regarding where I can find more information to help me develop this process?
Thank you in advance.





RE: NMP recovery
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI
RE: NMP recovery
I'm not planning on making a heat exchanger unit. I just want to buy one and am interested in knowing if anyone has already done this for NMP or a similar solvent. NMP is kind of like paint thinner.
RE: NMP recovery
Where does your NMP exhaust from? i.e. What do you use it for? NMP boils @ 202°C atm. NMP recovery can be done on site by vacuum distillation to remove residue.
RE: NMP recovery
RE: NMP recovery
RE: NMP recovery
At 120 Celsius, NMP would have a VP of ~ 8 kPa, meaning that its concentration is actually below saturation if the stream is at or above atmospheric pressure. You don't detail about the cooling agent, and whether there are other compounds that could condense together with NMP.
Please note that condensers of trace solvent quantities from effluent gases using large {Δ]T condensers would tend to form fogs difficult to capture. When looking to install an indirect condenser of NMP you should warn the supplier of this potential result.
Besides, you didn't identify the gaseous stream, and don't say whether there are mist or dust present to serve as nuclei for fog condensation.
Fog -consisting of droplets less than 10 micron in diameter- forms because the heat-transfer rate is greater than the mass-transfer rate, so that NMP undergoes quick chilling and condensation midstream before reaching the condenser wall.
RE: NMP recovery
Recovery of NMP is usually done by distillation. Depending on your exhaust stream and process this can be done by a small additional tower or some additional trays in existing towers. Depending on your process you may have to use a vacuum distillation as mentioned by chasewick (e.g. aromatic extraction).