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Hi all,

I am a senior undergrad in Chem E working on my design project, and have run into a problem.

A quick summary of what I am trying to figure out:
Coming out of the top of a flash separator is a stream with about 95% ammonia (rest is water) - stream is all vapor - which mixes with a makup stream of 4% ammonia hydroxide in a "mixer".
To make the process physically achievable, the stream out of the mixer should be all liquid so it could be pumped. When modeling this in Aspen however, the mixer outlet stream has a vapor fraction of 0.57.
Is there some type of unit operation that can replace this theoretical "mixer" to achieve a stream that is all liquid?
I attached a drawing with all mass flows, temps, pressures for the streams.

Currently looking into condensing the flash vapor into a liquid before sending into the mixer (which will mean will have to condense to about -33 C) which will require alot of refrigerant! Part of my design project is to optimize and find the best ways to achieve the desired goal taking cost into account.

Any ideas would be greatly appreciated!

Thanks!
AQ

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•  diagram.doc   24.5KB   21 downloads