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the right. The strategy employed here is to locate a vapor composition, within the
distillation column, which is to be withdrawn as a sidestream, to the right of a tangent
drawn from the left base of the phase envelope along the envelope (see the heavy
line on Figure 14.10). When water is added to such a location, the composition of
a condensed vapor is within the envelope and forms two phases, one being mesity
oxide - rich, which is removed. The aqueous phase is recycled and mixed with the feed
to the column.
Workshop 14.2f Many trial runs are required to estimate the number of stages, the
locations of the feed and sidestreams, the value of the reflux ratio, and flow specifica-
tions for a product and the sidestream. A good look at the composition profile of the
column vapors should provide an estimate of the sidestream location. Use of sensitivity
studies will aid in establishing column specifications.
Workshop 14.2g When linking the column and the decanter, one may experience
convergence failure. This may result due to the fact that the flow rate of the recycle
stream will vary during the iterations. This is an important factor to take into account
when establishing or altering the column specifications to accommodate the recycle
stream. For example, a total distillate flow specification may need to be changed to a
distillate/feed specification. Occasionally, a block within a process will fail to converge
during the iterations but is converged at the conclusion of a run. This is not a problem
as long as all blocks and recycles are converged satisfactorily at the conclusion of the
run.
Workshop 14.2h Reducing the reflux ratio and making small adjustments to other
column details, such as the number of stages, to the result of Workshop 14.2g will
produce a completed conceptual design.
REFERENCES
Arlt, W., Macedo, M. E. A., Rasmussen, P., and Sorensen, J. M., Liquid-Liquid Equilibrium Data Collec-
tion , Data Series in Chemistry, Vol. V, Parts 1 - 4, Dechema, Frankfort am Main, Germany, 1979 - 1987.
Dunlop, J. G., M.S. thesis, Brooklyn Polytechnic Institute, 1948.
Kojima, K., Kato, M., Sunda, H., and Hashimoto, S., Kagakukogaku , 32, 3371 (1968).
Seader, J. D., and Henley, E. J., Separation Process Principles , 2nd ed., Wiley, Hoboken, NJ, 2006.
Shell Oil Company, Technical Bulletin, Mesityl Oxide.
Stephen, H., and Stephen, T., Solubilities of Inorganic and Organic Compounds , Macmillan, New York,
1964.
Van Winkle, M., Distillation , McGraw-Hill, New York, 1967.
Wankat, P. C., Equilibrium Staged Operations , Prentice Hall, Upper Saddle River, NJ, 1988.
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