How to recover used nitrogen

[nanthakumar]

Hi

need some opinion on how to recover back used nitrogen. Can i rework the nitrogen gas we are venting out to atmosphere by re routing the nitrogen pipeline to atmosphere back for process usage.

N.B. The nitrogen is used in the fluidise dryer system. Based on pressure control in the dryer, excess nitrogen is vented out to atmospere.

Thanks

 

[saleda]

we also use liquid nitrogen in our process to have -92 deg C temp. and nitrogen is vented in atmosphere. particularly for we don't have any application for it. but i hope u can repressurize it and reuse it.

 

[RaRo]

After filtering the nitrogen which you probably do, just dry heat and recompress it to feed your fluidise dryer.
You will need a condenser (finned tubes works well) to remove whatver you got from drying, a simple filter, and a gas compressor (probably root type if you work below 0.8 barg).

 

[zdas04]

In short, it is just economics. If you can recover the N2, clean it up, and recompress it for a better NPV than venting it and buying new for the next step then you should. I've done these calcs and they are VERY sensitive to your required rate of return and cost of capital. If you can get capital for 1% and your company is happy with a positive NPV at a 4% ROCE then recovery will be a slam dunk. If your cost of capital is 4% and required ROCE is 20% then venting generally looks really good.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

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