Quality of the Feed: The thermal condition of the feed plays an important role in the feed location and the number of plates required to achieve a particular level of separation.  For a given feed composition, find the bubble point and dew point.

Heat required to vaporize one mole of benzene at feed temperature, HGB = cpB(TB - TF) + λB.

Heat required to vaporize one mole of toluene at feed temperature, HGT = cpT(TB - TF) + λT

Heat required to vaporize one mole of feed at feed temperature, HG = xFHGB + (1 - xF)HGT

Latent heat of vaporization of feed at bubble point, Hλ = xFλB + (1 - xF)λT

Quality of feed, q = HG/Hλ

Module for Calculation of quality of feed:

xF feed composition, mole fraction
TF feed temperature, deg C
TB bubble point, deg C
cA heat capacity of A, cal per mol per deg C
cB heat capacity of B, cal per mol per deg C
λA latent heat of vaporization of A, cal per lb per mol
λB latent heat of vaporization of B, cal per lb per mol