A charge of 100 lbmol of benzene (B), monochlorobenzene (MCB), and o-dichlorobenzene (DCB) is being distilled in a batch rectifier that consists of a total condenser, a column with 10 theoretical stages, and a partial reboiler. Following the establishment of total reflux, the first operation step begins for a boilup rate of 200 lbmol/h and a reflux ratio of about 3. At the end of 0.60 h, the following conditions exist for the top three stages in the column:

Liquid Mole Fractions:

In addition reboiler and condenser holdups at 0.6 h are 66.4 and 0.1113 lbmol, respectively. For benzene, use the preceding data with (13-36) and (13-39) to estimate the liquid-phase mole fraction of benzene leaving Stage 2 at 0.61 h by using the explicit-Euler method with a ∆t of 0.01 h. If the result is unreasonable, explain why with respect to stability and stiffness considerations.

Transcribed Image Text:

Top Stage Stage Stage 3 Temperature, °F V, lbmol/h 271.2 267.7 272.5 206.1 209.0 209.5 L, lbmol/h 157.5 158.0 158.1 M, lbmol 0.01088 0.01092 0.01087 Vapor Mole Fractions: B 0.0994 0.0449 0.0331 MCB 0.9006 0.9551 0.9669 DCB 0.0000 0.0000 0.0000