Introduction to Chemical Engineering

Unit-2
Definition of Chemical Engineering, Basic Concepts in Chemical Engineering: Unit
Operations, Basic laws, Useful mathematical methods, Units and Dimensions.

Definition of Chemical Engineering

Chemical engineering is a branch of engineering that combines the physical and life sciences
with applied mathematics and economics to design, develop, and optimize processes for
producing, transforming, transporting, and using chemicals, materials, and energy. Chemical
engineers work in a wide range of industries, including pharmaceuticals, healthcare,
construction, pulp and paper, petrochemicals, food processing, specialty chemicals,
microelectronics, polymers, and biotechnology.

Chemical engineers are involved in many areas, including:

 Process development
Chemical engineers design and develop large-scale processes for converting raw materials
into products.

 Process optimization
Chemical engineers work to maintain and improve processes.

 Sustainability
Chemical engineers are key in initiatives that promote energy efficiency, sustainable
development, and eco-friendly solutions.

 Collaboration
Chemical engineers work with other engineering disciplines, such as materials science,
computer science, mechanical engineering, electrical engineering, and civil and
environmental engineering.

Some examples of chemical engineering processes include: Refining crude oil by distillation,
Producing insulin through a fermentation process, and Creating catalytic converters for
reducing automotive emissions.

What is a simple definition of chemical engineering?

Chemical engineering involves the production and manufacturing of products through

chemical processes. This includes designing equipment, systems, and processes for refining
raw materials and for mixing, compounding, and processing chemicals.

Dr Bandi Chandra Sekhar

 Introduction to Chemical Engineering
What is called a chemical engineer?
A chemical engineer is a professional equipped with the knowledge of chemistry and other basic
sciences who works principally in the chemical industry to convert basic raw materials into a variety of
products and deals with the design and operation of plants and equipment.

కెమికల్ ఇంజనీర్ అంటారు?

కెమికల్ ఇంజనీర్ అనేది కెమిస్ట్రీ మరియు ఇతర నురాథమిక శరస్తరరీల ఩రిజా ఞనంతో కూడిన నుర ా ఫెషనల్, అతను నురాథమిక
ముడి ఩దారరాలను వివిధ ఉతపతత
ర లుగర మారచడానికి మరియు నురలంటల
ల మరియు ఩రికరరల రూ఩కలపన మరియు
ఆ఩రేషన్తో వ్యవ్హరించడానికి ఩ాధానంగర రస్తరయన ఩రిశ్రమలో ఩ని చేస్తర రడు.
What is the best definition of chemical?
A chemical is any substance that has a defined composition. In other words, a chemical is always made
up of the same "stuff." Some chemicals occur in nature, such as water. Other chemicals are
manufactured, such as chlorine (used for bleaching fabrics or in swimming pools).

Who is the father of chemical engineering?

George E Davis
George E Davis, who is considered to be the 'father' of the profession, suggested as far back as 1880
that the group which the following year became known as the Society of Chemical Industry, should be
named the Society of Chemical Engineers.

What is the duty of a chemical engineer?

A Chemical Engineer conducts research, analyzes data, and designs solutions to improve production
processes and equipment. They work on minimizing waste, increasing product quality, and
implementing safety procedures. They collaborate with a team of engineers, run simulations, and
communicate findings to stakeholders.

What is the basic concept of chemical engineering?

At its core, chemical engineering is a discipline that combines natural and life sciences with
mathematics and economics to design, develop, and optimize processes for producing, transforming,
and transporting materials.

Why is chemical engineering important?

Chemical engineering is responsible for fulfilling everyday needs such as clothes, food and energy.
Chemical engineers devise these production processes while also remaining mindful of managing
resources, making sure health and safety standards are adhered to, and protecting the world's
environment.

What is the scope of chemical engineering?

Graduates of chemical engineering can work in a variety of engineering fields,
including nanotechnology, petrochemicals, pharmaceuticals, mineral refinement and processing,
biotechnology, and so on

What are the concepts of chemical engineering?

Processing and manufacturing of chemicals in industries is based on many operations such as heat
transfer, mass transfer, fluid flow, distillation, evaporation, absorption, drying, leaching, mixing,
crystallization, adsorption, and humidification.
Dr Bandi Chandra Sekhar
 Introduction to Chemical Engineering
What is the life of a chemical engineer?
In addition to laboratory work, chemical engineers also spend time in offices and meeting rooms. They
collaborate with colleagues, discuss project progress, and brainstorm solutions to challenges. They
often work in multidisciplinary teams, which allows for a diverse range of perspectives and expertise.

Basic Concepts in Chemical Engineering: Unit Operations

Prominent unit-operations and unit-processes in chemical industry

A detailed summary of various prominent unit operations/processes and their functional role
in the chemical plant are summarized in Table along with suitable figures.

Category Unit operations/processes Functional role

a) Centrifugal pump
b) Reciprocating pump a) To pressurize liquids and gases.
fluid operations
c) Compressor b) To depressurize gases
d) Expander
a) Crusher
solid operations a) To reduce the size of solids
b) Grinder
a) Cyclone separator
b) Centrifuge
Solid-fluid a) To separate solid particles from solid-
c) Electrostatic precipitator
separators liquid/gas mixtures
d) Classifier & Thickener
e) Liquid-liquid separator
a) To either remove or add heat to process
streams so as to meet desired conditions in
a) Shell & Tube heat exchangers
other units.
Heat exchangers b) Fired heaters and furnaces
b) Either utilities or other process streams
c) Coolers
are used to carry out heating/cooling
requirements.
a) Phase separation
b) Distillation
c) Absorption
a) To separate a feed into products with
d) Stripping
different compositions.
Mass transfer units e) Adsorption
b) A third agent (heat or compound) is
f) Extraction
usually used to carry out separation.
g) Leaching
h) Crystallization
i) Membrane
a) Completely stirred tank reactor
(CSTR) a) To carry out reactions in homogenous fluids
b) Plug flow reactor (PFR) (gases/liquids).
Reactor units
c) Packed bed reactors (PBR) b) To carry out catalytic and multi-phase
d) Slurry & Trickle bed reactions.
reactors

Table 1: Important unit operations/unit processes and their functional role in chemical process
technology.

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 Introduction to Chemical Engineering
Process Technology Functional Role
Reactors - Central and most
a) CSTR important process
b) Batch-Reactor technology in process flow
c) PFR
d) Packed bed reactor
- Carry out desired reactive
e) Trickle bed reactor
f) Fluidized bed reactor
transformations

a) CSTR - Well mixed reaction

system

- Homogenous liquid/gas
phase reaction

- Most easy configuration

- Temperature control
through Jacket

- Reactant instantaneously
reaches lowest
CSTR concentration

-Mostinexpensive to design
and operate

b) Batch Reactor - Has a simple design, with

the requirement of very
little
supporting equipments
- Ideal for small scale
experimental studies on
reactor kinetics
- Can be used industrially
for treatment of very small
quantities
of materials.

c) PFR - Homogenous liquid/gas

phase reaction
- Reactant gradually
reaches low concentrations
- Good control over
temperature
- Temperature control
through jacket (not shown)

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 Introduction to Chemical Engineering
d) Packed Bed Reactor (PBR) - Heterogeneous reaction

- Packing to act as catalyst

- Packing packed in tubes

- Shell fed with

cooling/heating fluid
(optional)

- Most common in
process flow sheets

e) Trickle Bed Reactor - Multi-phase reaction

- If the reaction is not

catalytic, packing serves to
enhance interfacial area

- If the reaction is catalytic,

packing acts as a catalyst
as well

- Complicated design

Dr Bandi Chandra Sekhar

 Introduction to Chemical Engineering
f) Fluidized bed reactor - Provides highest mass,
heat and hence reaction
rates for solid-fluid
reactions

- Very commonly deployed

in petroleum refineries
(catalytic cracking)

- Complicated accessories
(shown) and control
system required

- The accessories are for

catalyst re-generation and
transport.

Process Technology Functional Role

Separators:
- Most important
a) Batch distillation process technology
b) Continuous distillation - Provides desired
c) Absorption separation between
d) Stripping phases and streams
e) Liquid-liquid extraction - Located next to the
f) Leaching reactor as 100 %
g) Crystallization conversions are very
h) Drying rare in industrial
i) Flash separator practice
j) Membrane separator
k) Packed bed contactor

a) Batch distillation column

- Used to separate a
liquid mixture based on
relative volatility
(differences in boiling
points)
- Operated in batch
mode

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 Introduction to Chemical Engineering

b) Continuous distillation (Fractionator) - The most important

separation technology in
process flow sheets
- Provides very pure
products
- Differences in boiling
points is the working
principle
- Energy intensive
operation
- Usually multi-
component distillation is
apparent in industrial
practice

c) Absorption column - Used to absorb

components
from gaseous
stream
- Solvent is
used
- Usually
followed with
stripper to re-
generate the
fresh solvent
- Operated at
low
temperature
and
moderate/hig
h pressure

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 Introduction to Chemical Engineering
d) Stripper
- Steam/Hot gas is used
to strip the gas
- Regenerated solvent
used for absorption

e) Liquid Liquid extraction

- Used to separate
components from a
liquid with a liquid
solvent
- Consists of a series of
mixers and separators
- Produces extract (rich
with solvent and
components extracted)
and raffinate (product
with lean extractants)

f) Leaching - A liquid solvent

extracts components
from a solid
- High interfacial area
between solid/liquid is
required to enhance
extraction capability

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 Introduction to Chemical Engineering

g) Crystallization - Used to crystallize

solids from a
slurry/super-saturated
solution

- Fine crystals added to

serve as nucleating
agent

h) Spray drier
- Liquid slurry is sprayed
in the form of droplets

- Hot gas (air) dries the

solid

- Enables very good

control over the
product particle size

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 Introduction to Chemical Engineering
i) Rotary drier - Through rotation, an
agitated liquid film is
dried to obtain the
dried solid.

j) Flash separator - Very common

technology to separate
liquid streams at high
pressure and lower
temperatures.

- Upon pressure
reduction/heating, low
boiling components
separate as vapor phase
and yield a liquid phase.

- Complete separation
only possible for fewer
components

k) Membrane separation - A semi-permeable

barrier (membrane) is
used to separate feed
streams based on
concentration
difference/pressure
difference.

- Various types of
processes available

- New technology in
process industries.

Dr Bandi Chandra Sekhar

 Introduction to Chemical Engineering
l) Packed bed contactor - Used for
absorption/stripping
operations

- Packing serves to
enhance gas/liquid
interfacial area

Basic laws

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