The fundamentals of Chemical Engineering design are called out very adequately in Perry's Chemical Engineer's Handbook. The packed tower is good for smaller diameter liquids which tend to foam. The packed tower often has a greater surface transfer area than a plate tower and where there are weaker liquid concentrations, the packed tower is often better.

The best reference for calculating tower heights, plates etc. is Perry's. Probably available in your local chemical engineering school library, or available through interlibrary loan. Also, a quick search through "chemical stripper design" on Google shows up a number of computer programs, including one in the Carnegie Mellon civil engineering school at: http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA275724 and its' supporting document and the program can be obtained through that source.