NMP recovery 1

[stabone]

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.

 

[Yorkman]

You will need to find the condensing temperature of N-methyl-2-pyrrolidone, also you will need to find the latent heat of condensation for the vapor and how many degrees of superheat the vapor is at when the exhuast is at 120 C. I'm not familiar with the chemical, but how will it react to the materials it comes in contact with in the liquid state leaving the heat exchanger.


I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[stabone]

I understand I need those things, but does anyone know of any suppliers of heat exchanger units that can accomplish my goal?

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.

 

[andmil]

Most of our heat exchangers are plate/braised type exchangers with NMP/cooling water. Try Alfa Laval

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.

 

[wfn217]

Try Stone Process Equipment.

 

[chasewick]

Vacuum Distillation is the solution. Try

http://www.wastechengineering.com.

They make a line of vacuum distillation systems and have experience with NMP recovery.

 

[25362]

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.

 

[BaAn]

If your unit is using NMP as a solvent in an extractive distillation process it might be more economical to recover the NMP for reuse in your process.
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).