3 replies to this topic

[ETHAN]

Dear members:
what is the range of temperatures that i can make a stripping for ammonia water solution and to minimize the water vapor slip with ammonia vapor for ammonia recovery process,,, i asked my self if there is a balance between the heat load for stripping purpose and the condensing efficiency and how i can condense the max. value of ammonia without traces of water slip

[siretb]

I am not sure I understand your question.

The temperature level will be, of course pressure dependent.
If you want to strip NH3, and get in the bottoms almost ammonia-free waters, then there will exist a minimum vapor rate (the bottoms rate) very similar to a minimum reflux rate. And minimum stages
The temperature, at this level will be givne by the pressure.

At the other end (top) you will want to condensate. If you want to have ammonia beyond a certain concentration, you'll need rectifying stages where you enrich the mixture in ammonia. The temperature will be given by the condensation curve at the given pressure.

To be practical, just consider that as a plain distillation. This approach will give your answers, and a design.
For the temprature at the condenser the key question is: what is the ammonia purity desired. 10%? 25%? more?

[ETHAN]

I'm agree with you in the point of temperature depend on pressure
but i want to know how to deal with ammonia - water system and make a stripping with max. content of ammonia on the top with traces of water
also a clean water on the bottom without any traces of ammonia ... how can i find the optimum range of temperatures to execute this process

[pawan]

Dear Ethan
Basically you are trying to establish the column operating pressure if I could understand your question / objective coorectly. Actually first it depends on utilities available like in all other cases of distillation. So when you talk about traces of water at the top means its almost pure ammonia which has -33 C condensing temp at atm pressure so you need a condensing utility of less than this. Therefore, if you want to use CW in condenser then you need operating pressure ~18 bar which is against the requirement of stripping. So its a balance between all utilities cost specific to your site.

Now ammonia stripping also requires pH to be more than ~12 below that its very difficult to remove all residual ammonia at the bottom. Further, heating utility cost is also a factor as above.