Distillation Underlying Principles of Distillation

Slides:



Advertisements
Similar presentations
APPLICATIONS Applications of Raoult’s law
Advertisements

A Selection of Chemical Engineering Problems Solved using Mathematica
Goal 1: Design a flash drum
Vapor and Liquid Equilibrium
Phase Equilibrium II - Two Component System. How many components and phases in this system? 2 components and 1 liquid phase Method to separate ethanol.
Experiment 6: Fractional Distillation Reading Assignment –Experiment 6 (pp ) –Operation 29.
Chemistry.
School of Electrical Engineering
Distillation Underlying Principles of Distillation
Chapter 16 Chemical and Phase Equilibrium Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 5th edition by Yunus.
2 –component solutions General: A (solvent) and B (solute) arbitrary if the solutions are completely miscible properties that define solution: P, T, 
Chapter 14-Part VII Applications of VLLE.
Separation Trains Azeotropes
Batch Distillation Gavin Duffy School of Electrical Engineering Systems DIT Kevin St.
Figure Figure 2 Chem 334 Expt. #3
Separating Azeotropic Mixtures CHEN 4460 – Process Synthesis, Simulation and Optimization Dr. Mario Richard Eden Department of Chemical Engineering Auburn.
Solution Thermodynamics: Applications
Liquid Phase Properties from VLE Data SVNA 12.1
PHASE EQUILIBRIUM (GROUP SECOND) 1) Muhammad Shafique 2) Noor Yussuf 3) Noor Nadia Syahira 4) Norfaizah 5)Nur Alya 6) Nur Azahariah 7) Wan Muhammad Hakimi.
CHE 205 $200 $400 $600 $800 $1000 Vapor/Liquid Equilibrium Energy Balances Multiphase Systems Nonreactive Processes $600.
Bubble Point and dew point Calculations
Solution Thermodynamic:
Designing a Separations Process Without VLE Data by Thomas Schafer - Koch Modular Process Systems, LLC This presentation utilizes as it’s example a problem.
Distillation. What is distillation? In general, a distillation is the process that includes the vaporizing a liquid from a pot and the subsequent condensation.
Advanced Thermodynamics Note 9 Vapor/Liquid Equilibrium: Introduction
ERT 313 BIOSEPARATION ENGINEERING DISTILLATION
FLASH CALCULATION A flash is a single-equilibrium stage distillation in witch a feed is partially vaporized to give a vapor richer in the most volatile.
Chemical Thermodynamics 2013/ th Lecture: Mixtures of Volatile Liquids Valentim M B Nunes, UD de Engenharia.
Vapor pressure and liquids Vapor : A gas that exists below its critical point Gas : gas that exists above its critical point ِNote : A gas can not condense.
5.4 Phase diagrams of binary systems Φ min =1, F max =3 C=2, F=2-Φ+2=4-Φ Predict by phase law: Three dimentional diagram T, P, x Intercepting plane graph---two.
CHEE 311J.S. Parent1 1. Science of Thermodynamics Concerned with knowing the physical state of a system at equilibrium. A concise (mathematical) description.
Dr Saad Al-ShahraniChE 334: Separation Processes  Nonideal Liquid Solutions  If a molecule contains a hydrogen atom attached to a donor atom (O, N, F,
SEQUENCING OF AZEOTROPIC DISTILLATION COLUMNS
Vapor-Liquid Equilibrium (VLE) at Low Pressures
Unit Operations Lecture Nov McCabe-Thiele – AZ diagrams 2 Ethanol – Water Binary (1.013 bar):
McCabe Thiele Graphical Equilibrium-Stage
Distillation ... A Separation Method.
Ethylene glycol, HOCH 2 CH 2 OH, boils at 198 o C and melts at -13 o C. What happens to the melting point of water if you add antifreeze? Melting point.
ERT 313 BIOSEPARATION ENGINEERING DISTILLATION Prepared by: Miss Hairul Nazirah Abdul Halim.
Ideal Gases.
THERMODYNAMICS OF SEPARATION OPERATIONS
The Simplest Phase Equilibrium Examples and Some Simple Estimating Rules Chapter 3.
Distillation... A Separation Method. Background Concepts - Definitions Vapor Pressure – Gas pressure created by the molecules of a liquid which have acquired.
CBE 417 “Unit Operations” Lecture: 3 7 Sep 2012.
R AOULT ’ S L AW The partial vapour pressure of a component in a mixture is equal to the vapour pressure of the pure component at that temperature multiplied.
Two Component Systems Limited to the mixtures two miscible liquids Graphs include: 1.Vapour pressure vs composition of mixture 2.Boiling point/temp. vs.
June 16, 2009 – Class 43 and 44 Overview
Vapor Pressure. Pressure of the vapor present when equilibrium is achieved between the rate of vaporization and the rate of condensation. At the boiling.
CHEE 311J.S. Parent1 4. Chemical Potential in Mixtures When we add dn moles of a component to n moles of itself, we will observe (?) a change in Gibbs.
Fractional Distillation Boiling point of mixtures Separation of mixtures by distillation.
Liquid-Vapor Phase Equilibrium Distillations will be performed in hood.
THERMODYNAMICS OF SEPARATION OPERATIONS
APPLICATIONS Applications of Raoult’s law
Introduction to phase equilibrium
Ideal and Dilute Solutions 2/21/2016. Master Thermodynamics Equations.
1. Write down the vapor-liquid equilibrium (VLE) equations for a binary system assuming that the vapor phase is ideal and the liquid phase follows Raoult’s.
Noorulnajwa Diyana Yaacob PPK Bioproses Universiti Malaysia Perlis MULTIPHASE SYSTEM.
Chapter 14: Phase Equilibria Applications Part II.
Phase Equilibrium II - Two Component System
Chapters 8-9 Phase Diagrams
FACULTY OF ENGINEERING TECHNOLOGY & RESEARCH
Ideal solutions for 3rd semester By T.Sweta Department of chemistry
Liquid-Liquid Phase Equilibrium
Boiling Points - Distillations
Enthalpy vs. Composition – Ponchon-Savarit Plot
SEQUENCING OF AZEOTROPIC DISTILLATION COLUMNS
Distillation.
Lecture Notes Week 1 ChE 1008 Spring Term (03-2).
Minimum Boiling Point Azeotrope
Presentation transcript:

Distillation Underlying Principles of Distillation Azeotropes and VLE Data Gavin Duffy School of Electrical Engineering Systems DIT Kevin Street

Learning Outcomes After this lecture you should be able to …. Define an azeotrope Derive a relationship for liquid and vapour phase mole fractions using Dalton’s and Raoult’s laws Develop vapour liquid equilibrium data from vapour pressures or from relative volatility Generate vapour pressures from the Antoine equation Create an equilibrium curve for a binary mixture

A strange looking VLE – An Azeotrope EA and Eth form an Azeotrope at 55% EA Azeotrope

The Azeotrope An azeotrope is formed when the liquid and vapour compositions are the same Separation by conventional distillation is not possible Dewpoint and bubble point are the same at the azeotrope Usually occurs at a particular mole fraction. Outside this point separation is possible Can have a minimum or maximum boiling point azeotrope Can limit the separation and purity of the product Changing the pressure can be the solution – Extractive Distillation

Min BP Azeotrope – EA Ethanol

Max BP Azeotrope - Water Formic Acid Other azeotropic mixtures include [water - nitric acid] [water - hydrochloric acid] and many [water – alcohols]

Activity - Azeotrope Check the Ethanol Water T-x-y diagram from earlier. Does it form an azeotrope? If so, at what point? What are the consequences? What can we do?

When equilibrium data are not available How can you decide if distillation will be a suitable separation technique if you don’t have T-x-y data? You have to make your own! Oh No! Can be difficult We need vapour pressures. These are obtained by Looking them up in a book Calculating them Use VP’s from book and construct a graph of VP v T From VP’s we can determine mole fractions The vapour pressures are needed at specific temperatures so they can be hard to find in the books.

1. Partial Pressure, Dalton and Raoult Dalton’s Law Pa = yaP Pa is the partial pressure, ya is the vapour mole fraction and P is the total pressure Raoult’s law – applies to an ideal mixture Pa = Poaxa Poa is the vapour pressure, xa is the liquid mole fraction We assume we are dealing with ideal mixtures.

Combining Dalton and Raoult… From Raoult’s law and Dalton’s law, we have: Therefore, if we know the vapour pressure we can calculate the mole fractions of the liquid and vapour phases You can then plot an x-y diagram or a T-x-y diagram. Remember, this is for constant pressure only.

2. From Relative Volatility  This is another way to get mole fractions. We can determine the relative volatility from the Vapour Pressures. Use the definition of relative volatility and Raoult’s law to get the following:  is a function of VP which is a function of T. (If you need just one  then take the average of  at the two b.p.’s). Next, include Dalton’s law to get an expression for mole fractions:

How do you get Vapour Pressures? Vapour pressures are needed at specific temperatures. 1. We could look up the books for data but you are unlikely to find them at the right temperature. Worth a try. 2. They’re in the book but for different temperatures. This is good. We can plot VP v T, join the dots and use this graph to give us the VP at the right temperature. 3. There’s nothing in the books. You have to calculate them. Use the Antoine equation or other such equations.

VP Option 2 - graph of VP v Temp From Perry, for example, find a table of vapour pressures for different temperatures. Plot VP on the y-axis against T. Put both components on the one curve. Get VP for any T from the curve A P B Temp

Antoine equation The Antoine equation relates vapour pressure to temperature Where P = pressure of the saturated vapour (mmHg) T = Temperature (K) A, B, C = Antoine coefficients Perry and the CRC handbook have Antoine coefficients

Clausius-Clapeyron Equation See example 6.1-1 in Felder and Rousseau

Acvtivity – Toluene and Benzene Choose one of the following mixtures and determine how easy it will be to separate by distillation. Benzene and Toluene,  = 2.5 Ethylene Glycol and Water,  = 81 Acetic Acid and Acetic Anydride,  = 1.9 Butane and Pentane,  = 3.5 Construct a T-x-y or an x-y curve for this binary system. Pressure = 1 atm For data – Use  or data + equations

Activity – Eth H2O Ethanol and Water are separated by distillation. The T-x-y data are given as follows. Perry is a source for data (limited) Fermentation gives an ethanol conc of about 15%. What happens when the mixture is boiled? What is the highest conc of eth that can be achieved in this way?