## Distillation: The Theory, 2nd Revised Edition

By Alfons Vogelpohl

**Contents:**

Preface|VII

Introduction|XII

1 The principles and modes of distillation|1

1.1 Simple distillation|1

1.2 Flash distillation|2

1.3 Multistage distillation|2

2 Assumptions and problem reduction|5

3 The basic equations of distillation|6

3.1 Mass balance|6

3.2 Vapour–liquid-equilibria|7

3.2.1 Ideal mixtures|7

3.2.2 Real mixtures|7

3.3 Mass transfer correlations|8

3.4 Distillation in a packed mass transfer section |9

3.4.1 Distillation at total reflux (L/V = 1)|9

3.4.2 Effect of the ratio of the mass transfer coefficients|10

3.4.2.1 Mass transfer resistance exclusively in the vapour phase (k = ∞)|10

3.4.2.2 Mass transfer resistance exclusively in the liquid phase (k = 0)|10

3.5 Distillation in a mass transfer section with theoretical stages |11

3.6 Distillation at partial reflux (L ̸= V)|12

3.7 Simple distillation|15

3.8 Reversible distillation|16

4 Distillation of ideal mixtures|17

4.1 Binary mixtures|17

4.1.1 Distillation at total reflux|17

4.1.1.1 Mass transfer section with a packing|17

4.1.1.2 Mass transfer section with theoretical stages|18

4.1.2 Distillation at partial reflux|18

4.1.2.1 Mass transfer section with a packing or theoretical stages|18

4.1.3 Distillation column with a rectifying and a **stripping section**|20

4.1.3.1 McCabe–Thiele-diagram|20

4.1.3.2 Limiting flow ratios (Minimum reflux condition)|21

4.1.3.3 Optimal feed location|24

4.1.3.4 Optimal flow ratios|25

4.2 Ternary mixtures|27

4.2.1 Distillation at total reflux and simple distillation |27

4.2.1.1 Vector field of the differential equation|27

4.2.1.2 Field of distillation lines|28

4.2.1.3 Effect of the mass transfer resistance|30

4.2.2 Distillation at partial reflux|32

4.2.2.1 Vector fields at partial reflux|34

4.2.2.2 Distillation spaces and separation lines|34

4.2.2.3 Calculation of the distillation lines|38

4.2.3 Reversible distillation|41

4.2.4 Product domains|42

4.2.4.1 Product domains in reversible distillation|42

4.2.4.2 Product domains of the mass transfer and theoretical stage concept based distillation (adiabatic distillation)|45

4.2.5 Distillation column|46

4.2.5.1 Distillation at the limiting flow ratios|46

4.2.5.2 Distillation at non-limiting flow ratios|54

4.2.5.3 Optimal feed location|55

4.2.6 The fundamental equation of distillation|58

4.2.6.1 The line function of distillation|59

4.2.6.2 The potential function of distillation|59

4.3 Quaternary mixtures|59

4.3.1 Distillation lines|59

4.3.2 Product domains|61

4.3.2.1 Reversible distillation|61

4.3.2.2 Adiabatic distillation|63

4.4 Multicomponent mixtures|64

4.4.1 Distillation at total reflux|67

4.4.2 Distillation at partial reflux|68

4.4.2.1 Product compositions|69

4.4.2.2 Sequencing of distillation columns|70

4.5 The conceptual design of the distillation of

multicomponent mixtures|74

4.5.1 Initial conditions|74

4.5.2 Determination of the product flow rates|75

4.5.3 Determination of the distillation lines|75

4.5.3.1 Numerical solution of the differential equations|75

4.5.3.2 Distillation spaces and distillation lines based on the algebraic solution

of the differential equations|75

5 Distillation of real mixtures|76

5.1 Zeotropic mixtures|77

5.1.1 Binary mixtures|77

5.1.1.1 Enthalpy-concentration-diagram|77

5.1.2 Ternary mixtures|78

5.1.2.1 Distillation at total reflux|79

5.1.2.2 Distillation at partial reflux|79

5.1.2.3 Product domains and minimum flow ratio|80

5.1.3 Multicomponent mixtures|82

5.2 Azeotropic mixtures|82

5.2.1 Binary mixtures|82

5.2.2 Ternary mixtures|84

5.2.2.1 Distillation at total reflux|85

5.2.2.2 Distillation at partial reflux|91

5.2.3 Multicomponent mixtures|94

6 **Computer programs**|95

7 References|96

8 Nomenclature|98

9 Glossary|101

A Appendices|102

A.1 Coordinate transformation|102

A.2 Distillation of an ideal five-component mixture|103

A.2.1 Conceptual design|103

A.2.2 Geometry of the distillation column [17, 57] |105

Index|106