Overview of Chemical Reactor Design and Operation

 
Chemical Reactor
 
Design-
 CHE 222
The field that 
studies 
the 
rates 
and 
mechanisms 
of chemical  reactions and the
design 
of 
the reactors 
in 
which 
they take
 
place
 
Prof. Dr. Asma abd el-
sattar
Professor of Chemical Engineering,
Faculty of Engineering - Minia University
 
Professor 
asma abdelsattar
 
asmaabdelsattar11@yahoo.com
 
Assistant Lecturer
 Eng. Rasha Hussien
engchemical799@gmail.com
 
3
 
Contact
 
Information
 
Text 
Book
 
Chemical
Reaction
Engineer
i
ng
Third
 
Edition
 
Octave
 
Levenspiel
Department 
of Chemical
 
Engineering
Minia 
University
 
 
 
4
 
Overview of Chemical Reactor
 
Design
 
Typical 
chemical
 
process
Chemical 
reaction 
engineering 
(or 
reactor design
) is 
the engineering 
practice
concerned with the 
exploitation of chemical 
reactions 
on 
a 
commercial scale.
Its 
goal 
is 
the 
successful 
design and operation of chemical
 
reactors.
 
Thermo
d
y
na
m
i
c
s
Mass
 
transfer
 
4
 
Chemical
 
kinetics
Heat
 
transfer
 
Fluid
 
mechanics
Economics
 
Input
 
Ou
tput
 
Performance
 
equation
relates input to
 
output
 
Contacting pattern 
or how 
materials
flow through and contact each other in
the 
reactor, 
how early or late they 
mix,
their 
clumpiness 
or state of aggregation.
By their very nature 
some materials 
are
very 
clumpy, 
for instance, solids and
noncoalescing 
liquid
 
droplets.
 
Kinetics 
or how fast 
things 
happen. If
very fast, then 
equilibrium 
tells 
what
will 
leave the 
reactor. 
If not so fast, then
the rate of 
chemical 
reaction, and
 
maybe
heat and 
mass 
transfer too, 
will
determine what will
 
happen.
 
Information needed to 
predict 
what a 
reactor 
can
 
do
Output 
= 
f 
[input, kinetics,
 
contacting]
 
(1)
 
5
 
Overview of Chemical Reactor
 
Design
 
Develop 
appropriate 
performance equations by 
reaction
 
types
Classification of 
chemical 
reactions useful in reactor
 
design
 
It depends on 
how 
we 
choose 
to 
treat 
them
, and this in turn depends on
 
which
description 
we 
think 
is 
more
 
useful
.
 
6
 
Overview of Chemical Reactor
 
Design
 
Reaction rate is the key
 
issue
 
If the rate of change in 
number 
of 
moles 
of component 
i 
due to reaction
 
is
dN
i
/dt
, 
the rate of reaction 
is 
defined 
as
 
follows.
 
Based on 
unit 
volume 
of reacting
 
fluid,
 
𝑖
𝑖
 
𝑉
 
𝑑𝑡
 
1
 𝑑𝑁
𝑖
𝑟 
 
=
 
=
 
𝑚𝑜𝑙𝑒 
𝑖
 
𝑓𝑜𝑟𝑚𝑒𝑑
(𝑣𝑜𝑙𝑢𝑚𝑒 
𝑜𝑓
 
𝑓𝑙𝑢𝑖𝑑)(𝑡𝑖𝑚𝑒)
 
(2)
 
Overview of Chemical Reactor
 
Design
 
Based on 
unit mass 
of 
solid 
in 
fluid-solid
 
systems,
 
𝑖
𝑖
 
𝑟
 
 
𝑊
 
𝑑𝑡
 
1
 
𝑑𝑁
𝑖
=
 
=
 
𝑚𝑜𝑙𝑒 
𝑖 
𝑓𝑜𝑟𝑚𝑒𝑑
(𝑚𝑎𝑠𝑠 𝑜𝑓
 
𝑠𝑜𝑙𝑖𝑑)(𝑡𝑖𝑚𝑒)
 
7
 
(3)
 
Based on 
unit 
volume of 
solid 
in 
gas-solid
 
systems,
 
𝑖
𝑖
 
 
𝑟
 
=
 
1
 
𝑑𝑁
 
𝑖
𝑖
 
𝑉
𝑠
 
𝑑𝑡
 
𝑚𝑜𝑙𝑒 
𝑖
 
𝑓𝑜𝑟𝑚𝑒𝑑
= 
(𝑣𝑜𝑙𝑢𝑚𝑒 
𝑜𝑓
 
𝑠𝑜𝑙𝑖𝑑)(𝑡𝑖𝑚𝑒)
 
(5)
 
Overview of Chemical Reactor
 
Design
 
Reaction rate is the key
 
issue
Based on 
unit 
interfacial 
surface 
in two-fluid systems or
based on 
unit surface 
of solid 
in gas-solid
 
systems,
 
𝑖
𝑖
 
𝑟
 
′′
 
1
 
𝑑𝑁
𝑖
 
𝑚𝑜𝑙𝑒 
𝑖
 
𝑓𝑜𝑟𝑚𝑒𝑑
=
 
𝑆 
 
𝑑𝑡
 
=
 
(𝑠𝑢𝑟𝑓𝑎𝑐𝑒)(𝑡𝑖𝑚𝑒)
 
(4)
 
Based on 
unit 
volume of 
reactor
, 
if 
different 
from the rate based on unit
volume of
 
fluid,
 
 
𝑟
𝑖
 
=
 
1
 
𝑑𝑁
 
𝑖
𝑖
 
𝑉
𝑟
 
𝑑𝑡
 
𝑚𝑜𝑙𝑒 
𝑖
 
𝑓𝑜𝑟𝑚𝑒𝑑
=
(𝑣𝑜𝑙𝑢𝑚𝑒 
𝑜𝑓
 
𝑟𝑒𝑎𝑐𝑡𝑜𝑟)(𝑡𝑖𝑚𝑒)
 
8
 
(6)
 
Relationship between these
 
definitions:
 
Overview of Chemical Reactor
 
Design
 
Variables 
Affecting the Rate of
 
Reaction
 
In 
homogeneous 
systems the 
temperature
, 
pressure
, 
and 
composition
 
are
obvious
 
variables.
 
Heat 
and 
mass transfer 
may 
play important roles in determining the rates
of 
heterogeneous
 
reactions.
 
9
 
Broad classification 
of 
reactor
 
types
 
Overview of Chemical Reactor
 
Design
 
(a) The batch 
reactor. 
(b) The steady-state flow 
reactor. 
(c), (d), and (e) 
Various 
forms 
of the
semibatch
 
reactor
 
10
 
Broad classification 
of 
reactor
 
types
 
11
 
Overview of Chemical Reactor
 
Design
 
Batch
 
Reactor
 
12
 
Flow
 
Reactor
 
Overview of Chemical Reactor
 
Design
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Chemical reactor design involves studying the rates and mechanisms of chemical reactions, as well as the design of reactors for these reactions on a commercial scale. This field combines principles from thermodynamics, chemical kinetics, fluid mechanics, mass transfer, heat transfer, and economics to ensure the efficient operation of chemical reactors. Performance equations are crucial in predicting reactor behavior, considering factors like input materials, kinetics, and contacting patterns. Reactor design also involves developing appropriate performance equations based on reaction types and understanding reaction rates.

  • Chemical reactor design
  • Chemical reactions
  • Reactor operation
  • Performance equations
  • Kinetics

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  1. Chemical Reactor Design- CHE 222 The field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place Prof. Dr. Asma abd el- sattar Professor of Chemical Engineering, Faculty of Engineering - Minia University

  2. Contact Information Professor asma abdelsattar asmaabdelsattar11@yahoo.com Assistant Lecturer Eng. Rasha Hussien engchemical799@gmail.com 3

  3. Text Book Chemical Reaction Engineering Third Edition Octave Levenspiel Department of Chemical Engineering Minia University 4

  4. Overview of Chemical Reactor Design Typical chemical process Chemical reaction engineering (or reactor design) is the engineering practice concerned with the exploitation of chemical reactions on a commercial scale. Its goal is the successful design and operation of chemical reactors. Thermodynamics Chemicalkinetics Fluidmechanics Masstransfer Heattransfer Economics 4

  5. Overview of Chemical Reactor Design Performance equation relates input to output Input Output Contacting pattern or how materials flow through and contact each other in the reactor, how early or late they mix, their clumpiness or state of aggregation. By their very nature some materials are very clumpy, for instance, solids and noncoalescing liquiddroplets. Kinetics or how fast things happen. If very fast, then equilibrium tells what will leave the reactor. If not so fast, then the rate of chemical reaction, andmaybe heat and mass transfer too, will determine what willhappen. Information needed to predict what a reactor cando Output = f [input, kinetics, contacting] (1) 5

  6. Overview of Chemical Reactor Design Develop appropriate performance equations by reactiontypes Classification of chemical reactions useful in reactor design It depends on how we choose to treat them, and this in turn depends on which description we think is more useful. 6

  7. Overview of Chemical Reactor Design Reaction rate is the keyissue If the rate of change in number of moles of component i due to reaction is dNi/dt, the rate of reaction is defined as follows. Based on unit volume of reacting fluid, (2) 1 ??? ???? ? ?????? (???????? ?????)(????) ? = = ? ?? Based on unit mass of solid in fluid-solid systems, 1 ??? ???? ? ?????? (???? ?? ?????)(????) (3) ? = = ? ?? 7

  8. Overview of Chemical Reactor Design Reaction rate is the keyissue Based on unit interfacial surface in two-fluid systems or based on unit surface of solid in gas-solid systems, 1??? =? ??=(???????)(????) ???? ? ?????? (4) ? Based on unit volume of solid in gas-solid systems, ???? ? ?????? = (???????? ?????)(????) =1 ?? ???? (5) ? Based on unit volume of reactor, if different from the rate based on unit volume of fluid, ???? ? ?????? =1 ?? ???? = (6) ?? (???????? ???????)(????) 8

  9. Overview of Chemical Reactor Design Relationship between thesedefinitions: Variables Affecting the Rate ofReaction In homogeneous systems the temperature, pressure, and composition are obvious variables. Heat and mass transfer may play important roles in determining the rates of heterogeneous reactions. 9

  10. Overview of Chemical Reactor Design Broad classification of reactortypes (a) The batch reactor. (b) The steady-state flow reactor. (c), (d), and (e) Various forms of the semibatch reactor 10

  11. Overview of Chemical Reactor Design Broad classification of reactortypes Ideal for small-scale experimental studies on reaction kinetics or small amounts of material are to be treated industrially. Batch Ideal for industrial purposes when large quantity of materials is to be processed and when the rate of reaction is fairly high to extremely high. Good product quality control can be obtai- ned (oil industry). Steady-state flow It offers good control of reaction speed because the reaction proceeds as reactants are added. It was used from the calor- imetric titrations in the laboratory to the large open hearth furnaces for steel production. Semibatch 11

  12. Overview of Chemical Reactor Design Batch Reactor FlowReactor 12

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