Document Type

Dissertation

Date of Award

Spring 5-31-1982

Degree Name

Doctor of Engineering Science in Chemical Engineering

Department

Chemical Engineering and Chemistry

First Advisor

Edward Charles Roche, Jr.

Second Advisor

Arthur Greenberg

Third Advisor

John E. McCormick

Fourth Advisor

Denis L. Blackmore

Fifth Advisor

Gordon Lewandowski

Abstract

A rigorous multistage distillation model was developed for use with non-ideal multicomponent systems. A subsidiary computer program was also developed to handle the problem of two liquid phases after condensation of a vapor.

Using the program developed, entrainer entry location and rate effects have been investigated via computer simulation for azeotropic distillation columns. The specific example used to verify the procedure was an ethanol dehydration column using benzene as the entrainer. The results indicate that the entrainer should enter the column two to five theoretical stages above the feed. The optimum entrainer rate was also determined.

The overhead vapor product from the azeotropic column, upon condensing to a subcooled liquid, forms two liquid phases in the accumulator. A two-liquid phase separation model was used to deal with the liquid phase splitting. This model has been validated using published data for nonideal ternary and quaternary systems. A study of the accumulator temperature effect on liquid phase splitting was also accomplished for the ethanol dehydration column. The results indicate that at lower accumulator temperatures the benzene loss in the heavy phase can be reduced.

Finally, the azeotropic distillation model and the two-liquid phase flash model were included in a representation of a complete industrial ethanol purification plant. Incorporated in the plant simulation is the azeotropic column, two-liquid phase accumulator, a benzene stripping column and an ethanol recovery/water purge column. The ability of this model to converge on the benzene entrainer stream was verified.

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