Determination of vaporization efficiencies for packed columns at steady state operation

Abstract

Experimental data were collected for a packed distillation column which was operating at a commercial natural gasoline plant. This column was packed with two-inch Pall Rings. The top section was three feet in diameter and the bottom section was four feet in diameter. Each packed section was 17 feet in length. The steady state data collected included the flow rates and the compositions of all terminal streams and a temperature profile for the packed sections. The concepts of the mass transfer section and the heat transfer section were developed during the course of this investigation. The application of these concepts allows packed distillation columns to be treated in the same manner as distillation columns with plates. Each mass transfer section is mathematically described by the mass transfer relationship, which in turn can be regarded as the definition of the vaporization efficiency for each component. The vaporization efficiency is defined as the composition of the vapor leaving a section divided by the composition calculated on the basis of the temperature and composition of the liquid leaving the section. A proof that there exists a one-to-one correspondence between vaporization efficiencies and overall mass transfer coefficients is presented. The heat transfer section relates the temperature of the vapor leaving a section with the temperature of the liquid leaving a section. ...