Transport Processes and Separation Process Principles (Includes Unit Operations) Fourth Edition

11.6. FRACTIONAL DISTILLATION USING ENTHALPY–CONCENTRATION METHOD

11.6A. Enthalpy–Concentration Data

1. Introduction

In Section 11.4B the McCabe–Thiele method was used to calculate the number of theoretical steps or trays needed for a given separation of a binary mixture of A and B by rectification or fractional distillation. The main assumptions in the method are that the latent heats are equal, sensible heat differences are negligible, and constant molal overflow occurs in each section of the distillation tower. In this section we shall consider fractional distillation using enthalpy–concentration data where the molal overflow rates are not necessarily constant. The analysis will be made using enthalpy as well as material balances.

2. Enthalpy–concentration ...