58012 - Thermodynamics for Chemical Engineering

Learning outcomes

Aim of the course is the introduction of the basic elements for the characterization of  physical and chemical equilibria and for the calculation of the properties of mixtures.

Course contents

The course is an introduction to Chemical Engineering Thermodynamics, concerning multi-phases and multi-components systems.

The basic elements will be introduced for the characterization of physical and chemical equilibria and for the calculation of the properties of mixtures. Contents.

1.       Solution Thermodynamics
Partial molar properties, Gibbs-Duhem equation and relative applications. Maxwell equations for multi-components systems.  Chemical potential, fugacity, activity and activity coefficients: definitions, properties, relationships. Raoult's reference state.
Ideal and non-ideal mixtures. Property changes of mixing. Heat effects on mixing processes: heat of mixing and heat of solution; specific heat of a mixture. Literature data. Heat of formation of compounds in solutions. Enthalpy-composition charts. Material and energy balances on non-ideal mixtures.
Excess properties, correlative liquid mixtures models. Introduction to some simple models (Margules, Van Laar, e NRTL): discussion and calculation of the corresponding adjustable parameters. The Redlich-Kister expansion

2.       Stability
Stability and equilibrium: application to multicomponents mixtures. Criterion for phase equilibria for non reactive systems. The Gibbs phase rule.

3.       Liquid vapour equilibria
Raoult's equation: the Poynting factor and simplifications. Raoult's law for ideal mixtures. L-V equilibrium diagrams for binary systems at low to moderate pressures. (T,x), (p,x) and (y,x) diagrams for ideal systems and non-ideal systems showing positive and negative deviations; lever rule applications. Azeotropes. Volatility.
Boiling point and dew point calculations for ideal and non-ideal mixtures; solution procedures and discussion of the corresponding algorithms. Calculation of equilibrium conditions for different specifications. Applications to equilibrium condensers/evaporators.

4.       Equilibrium stage.
Degree of freedom analysis (Duhem's theorem). General statement of multi-phases multicomponents equilibrium problems.

5.       Liquid-liquid and liquid-liquid-vapour equilibria.
L-L equilibrium diagrams for binary systems; solubility diagrams and partial miscibility; consolute temperatures.
L-L-V equilibrium diagrams; heterogeneous azeotropes. The limiting case of completely immiscible liquids. Boiling point and dew point calculations for multicomponents systems containing water and hydrocarbons. The effect of incondensable components.

6.   Gas-liquid systems (brief introduction): gas solubility, Henry's law.

7.   Chemical-reaction equilibria
Independent reactions. Thermo-Chemistry fundamentals (summary).
Equilibrium criteria for chemical reactions. The standard Gibbs energy change and the equilibrium constant of a reaction. Effect of temperature. Evaluation of equilibrium constants: application and discussion about different calculation procedures, depending on the available data in literature. Approximations. Effect of pressure, inert compounds and reactants composition on the equilibrium conditions.
Calculation of equilibrium conversions in gas-phase multiple reactions, for ideal gas mixtures. Discussion of the calculation procedures for gas-phase reactions in ideal mixtures.
Material and energy balances on isothermal and adiabatic reactors.

9.       Simultaneous chemical and physical equilibria.
General Gibbs Phase Rule.
Reactions in heterogeneous systems: dissociation pressure of a solid.

Readings/Bibliography

·         J. M. Smith, H.C.Van Ness, M.M. Abbot, Introduction to Chemical Engineering Thermodynamics, 5th ed., Mc Graw Hill, 1996

·         R.C. Reid, J.M. Prausnitz, B.E. Poling, The properties of gases and liquids, 4th ed. Mc Graw Hill, 1988

·         S. Sandler, Chemical Engineering Thermodynamics, 2nd nd 3rd ed., Wiley

·         Denbingh, I principi dell'equilibrio chimico, Casa Editrice Ambrosiana.

·         Teacher's notes.

Office hours

See the website of Serena Bandini