Ch.E-206: Mass Transfer Fundamentals

Dr. Anam Asghar

University Vision and Mission

UET’s VisionTo generate knowledge for global competitiveadvantage and become a leading world classresearch University.

UET’s Mission To play a leading role as a University of Engineeringand Technology in teaching, research, innovationand commercialization that is internationallyrelevant and has a direct bearing on nationalindustrial, technological and socio-economicdevelopment.

http://www.uet.edu.pk/aboutuet/aboutinfo/index.html?RID=about_uet_future_vision

Department Mission

The mission of the undergraduate program of the Department of ChemicalEngineering encompassed three key aspects:

i) Education: To offer an outstanding academic program to enable graduates masterprocess synthesis, design, and operations knowledge and develop excellenttechnical, technological and leadership skills

ii) Research: To provide a vibrant interdisciplinary research program in engineeringscience, creating novel and sustainable solutions to serve public interests in areassuch as health, energy and environment.

iii) Social Responsibility: To promote inclusive, safe, collaborative and respectfulcommunity for learning and work with integrity.

http://www.uet.edu.pk/faculties/facultiesinfo/department?RID=introduction&id=4

Program Educational Objectives (PEOs)

PEO-1: To prepare graduates with strong technical education for practicing andapplying the principles of Chemical Engineering and with excellent communication skillsto enable them have successful careers in a variety of industrial and professionalenvironment.

PEO-2: To prepare graduates for rapidly changing technological environment with thecore knowledge central to multidisciplinary development and personal improvementthroughout their professional careers.

PEO-3: To enable graduates pursue continued lifelong learning through professionalpractice, further graduate education, or other training programs in engineering sciencesor other professional fields.

PEO-4: To enable graduates achieve professional success with an understanding andappreciation of ethical behavior, social responsibility, and diversity, both as individualsand in team environments.

http://www.uet.edu.pk/faculties/facultiesinfo/department?RID=introduction&id=4

Program Learning Outcomes (PLOs)

PLO-1 Engineering Knowledge PLO-7Environment and

Sustainability

PLO-2 Problem Analysis PLO-8 Ethics

PLO-3Design/Development of

SolutionsPLO-9 Individual and Team Work

PLO-4 Investigation PLO-10 Communication

PLO-5 Modern Tool Usage PLO-11 Project Management

PLO-6 The Engineer and Society PLO-12 Lifelong learning

http://www.uet.edu.pk/faculties/facultiesinfo/department?RID=introduction&id=4

Course Content

• Introduction to Mass transfer and its applications;

• Mass conservation equations for single and multi-component mixture

• Principles of diffusions transfer between phases; Fick’s law

• Analogies with momentum and heat transfer

• Steady state Diffusion in gases and liquids

• Transient diffusion

• Mass transfer theories

• Mass transfer coefficients through various geometries and flow patterns

• Equilibrium stage operations: Equipment for stage contacts, Distillation: Flash distillation, Continuous distillation with reflux.

• Design of plate and packed columns.

Course Learning Outcomes (CLOs)

CLO Statement Cognitive level Mapping with PLO

CLO-1: Identify the basic principles and practical examples of

steady state mass transfer mechanismsC-1 PLO-1

CLO-2: Estimate mass transfer coefficients and interpret them to

predict mass transfer rates for both external and internal flows and

across phase boundaries.

C-1 PLO-1

CLO-3: Apply mass transfer theories to solve equilibrium stage

operation for intended separation processes.C-3

PLO-2

CLO-4: Distinguish between plate and packed column and

investigate the influence of transfer units on process efficiency.C-4 PLO-2

Course Evaluation

4 Quizzes : 20%

Mid Term : 30%

Assignments : 10%

End Term : 40%

75% attendance is compulsory to sit in Exams

Course Evaluation

Quiz-1 15-02-2018

Quiz-2 15-03-2018

Quiz-3 23-04-2018

Quiz-4 10-05-2018

Recommended Books

Unit Operations of Chemical Engineering by W. L. McCabe, J. C. Smith, and P. Harriott.

Principles of Mass Transfer and Separation Processes” by B. K. Dutta

Recommended Books

• Coulson and Richardson’s Chemical Engineering — Volume 1: Fluid Flow, Heat Transfer and Mass Transfer” by J. M. Coulson, J. F. Richardson, J. R. Backhurst, and J. H. Harker

Coulson and Richardson’s Chemical Engineering

— Volume 2: Particle Technology & Separation

Processes” by J. F. Richardson, J. H. Harker, and J.

R. Backhurst

• Separation Process Principles by J. D. Seader, and E. J. Henley.

• Mass Transfer Operations by R. E. Treybal.

• Fundamentals of Heat and Mass Transfer by F. P. Incropera, D. P. DeWitt, T. L. Bergman, and A. S. Lavine.

Recommended Books

• This course is designed to introduce a basic study of the phenomenaof mass transfer, to develop methodologies for solving a widevariety of practical engineering problems relevant to mass transfer,and to provide useful information concerning the performance anddesign of particular systems and processes

Course Objective

Introduction

• Separation of mixtures constitutes a major class of operations in the chemical process industry (CPI) and allied industries.

• Some mixtures are amenable to separation by purely mechanical techniques.

• There are many other mixtures, like gas and liquid mixtures (or solutions) in general, which cannot be separated by any of the Mechanical techniques

Mass Transfer??

• Mass transfer is the transport of a species from one point to another in a single phase or from one phase to another generally in the presence of a difference in concentration (or partial pressure) called the driving force

Continued• The driving force gives a measure of how far a system is away from

equilibrium.

• The larger the departure of a system from equilibrium, the greater is the driving force and the higher is the rate of transport.

• Water exposed to air will absorb oxygen faster if it has a low concentration of oxygen. If a limited volume of water eventually gets saturated with oxygen, it loses its ability to absorb gas any further.

Types of Mass Transfer

Diffusional:

A purely diffusional mass transfer occurs in the absence of any

macroscopic motion in the medium.

Convective

Mass transfer occurs in a fluid medium which is in some sort of motion.

The stronger the flow field and mixing and turbulence in a medium, higher is

the rate of mass transfer

Role of Separation Processes

• Separation of mixtures accounts for about 40 to 70% of both capital and operating costs of a chemical industry.

• The cost of separation of high-value products from a dilute solution (as in the case of recovery and concentration of bio products) may entail even 90% of the operating cost of a plant.

Two-Phase Systems

• Gas or (vapor)-liquid Contact

• Liquid-liquid Contact

• Solid-liquid Contact

• Gas-solid Contact

Vapor-Liquid Contact

• Separation of a soluble species from a gas mixture by using a solvent is called ‘gas absorption’. This is a gas–liquid contacting operation.

• A typical application is the separation of CO2 from the ammonia synthesis gas using a solvent like aqueous ethanolamine or carbonate–bicarbonate buffer

Liquid-Liquid Contact

• If some or all of the components have low volatility and are thermally unstablein a liquid mixture or solution, it becomes convenient to introduce a suitableliquid, called solvent, into the separation device to extract the targetcompounds. This is liquid–liquid extraction.

• The desired species is recovered from the extract by using another separationtechnique, say distillation or crystallization

• Separation of pencilline from the fermentation broth by using an ester like butyl acetate…

• Final product recovery is done by crystallization

Example

Solid-Liquid Contact

• One type of solid–liquid contact operation aims at solubilizing or extracting a target substance from a solid matrix. This is ‘solid–liquid extraction’ or ‘leaching’.

• Some typical examples are acid-leaching of ores or extraction of oil from flaked oil seeds or fragrance from flowers.

Gas-Solid Contact

• Separation of a solute from a gas mixture can sometimes be done by adsorption in a solid material. The adsorbed solute is recovered frequently by thermal stripping.

• Another important application of gas–solid contacting is for drying of a moist solid using a drying gas.