Ammonia Stripping And Absorption

Hi,

I am struggling to get to grips with ammonia nitrogen (NH3-N) in dirty water, and if this water is evaporated, how much of ammonia will be in the gas phase and then how much of that might recondense into water in the absorber?

Details in attached

I have 2 columns filled with 50 mm plastic Pall Rings, almost 12 m tall.

1st column does the stripping and 2nd column does the absorption/condensation

1st step is to estimate how much ammonia will be evaporated into the air+ water vapour stream in the 1st column, then when this air+vapour is transferred to the 2nd column, where the water vapour will be condensed , how much of that ammonia might re-condense into the water stream.

Then the "same" air (minus water evaporated + with ammonia) is sent back to the evaporator column.

Any hints or ways to tackle this using mass transfer coefficients, Henry’ constant, .. will be appreciated.

Ideally, I would like to have the ammonia in gaseous phase and very little transferred to the condenser water - any thought/s ideas?

Best regards,

Nick

Sorry, with attachment.

Hi,

A few documents to support your work .

note :

* I don't understand your schematic ! should not be fresh air entering the stripper ? 

https://www.katmarso...re.com/pcol.htm

Good luck

Breizh 

Edited by breizh, 30 May 2020 - 02:25 AM.

Hi,

There are differences between traditional stripper-absorber and our arrangement.

We use same air - different from traditional stripping- and we do an inversion of temperature.

Essentially, the idea is to use air already in the columns, and only transfer evaporated water from one column (evaporator) to the other (condenser), condense the water and then return the "dry" air back to the column. This means that any volatiles and ammonia will remain in gas phase and gradually reach equilibrium. There is no off gas treatment at the moment due to the same air being used.#

This also implies that ammonia may re-condense - I don't "think" the re-condensed value will be higher as  ammonia remains in gasous form in the air stream that is recycling back and forth. Also the water vapour produced is much more than the ammonia gas.

Nick

Hi ,

You may download a copy of Winsorp from Rashig or similar  to perform your calculation .

I've attached 2 print out for desorption and absorption of NH3 .

note : height of bed seems too big , the flow rate of gas seems  too small .

Good luck 

Breizh