Chemical reaction Engineering basics notes of B.E.

1. Chemical Reaction Engineering (CRE) is the field that
studies the rates and mechanisms of chemical reactions and
the design of the reactors in which they take place.
TODAY’S LECTURE
Introduction
Definitions
General Mole Balance Equation
Batch
CSTR
PFR
PBR

2. Chemical Reaction Engineering
Chemical reaction engineering is at the heart of virtually
every chemical process. It separates the chemical engineer
from other engineers.
Industries that Draw Heavily on Chemical Reaction
Engineering (CRE) are:
CPI (Chemical Process Industries)
Dow, DuPont, Amoco, Chevron

5. Materials on the Web and CDROM
http://www.engin.umich.edu/~cre/

11. Developing Critical Thinking Skills
Socratic Questioning
is the
Heart of Critical Thinking
R. W. Paul’s Nine Types of Socratic
Questions

12. Let’s Begin CRE
Chemical Reaction Engineering (CRE) is
the field that studies the rates and
mechanisms of chemical reactions and the
design of the reactors in which they take
place.

13. • A chemical species is said to have reacted
when it has lost its chemical identity.
Chemical Identity

14. • A chemical species is said to have reacted
when it has lost its chemical identity.
• The identity of a chemical species is
determined by the kind, number, and
configuration of that species’ atoms.
Chemical Identity

15. • A chemical species is said to have reacted
when it has lost its chemical identity.
1. Decomposition
Chemical Identity

16. • A chemical species is said to have reacted
when it has lost its chemical identity.
1. Decomposition
2. Combination
Chemical Identity

17. • A chemical species is said to have reacted
when it has lost its chemical identity.
1. Decomposition
2. Combination
3. Isomerization
Chemical Identity

18. • The reaction rate is the rate at which a
species looses its chemical identity per unit
volume.
Reaction Rate

19. • The reaction rate is the rate at which a
species looses its chemical identity per unit
volume.
• The rate of a reaction (mol/dm3/s) can be
expressed as either
the rate of Disappearance: -rA
or as
the rate of Formation (Generation): rA
Reaction Rate

20. Reaction Rate
Consider the isomerization AB
rA = the rate of formation of species A per unit volume
-rA = the rate of a disappearance of species A per unit volume
rB = the rate of formation of species B per unit volume

21. Reaction Rate
• EXAMPLE: AB
If Species B is being formed at a rate of
0.2 moles per decimeter cubed per second, ie,
rB = 0.2 mole/dm3/s

22. Reaction Rate
• EXAMPLE: AB
rB = 0.2 mole/dm3/s
Then A is disappearing at the same rate:
-rA= 0.2 mole/dm3/s

23. Reaction Rate
• EXAMPLE: AB
rB = 0.2 mole/dm3/s
Then A is disappearing at the same rate:
-rA= 0.2 mole/dm3/s
The rate of formation (generation of A) is
rA= -0.2 mole/dm3/s

24. Reaction Rate
• For a catalytic reaction, we refer to -rA',
which is the rate of disappearance of
species A on a per mass of catalyst basis.
(mol/gcat/s)
NOTE: dCA/dt is not the rate of reaction

25. Reaction Rate
Consider species j:
• rj is the rate of formation of species j per
unit volume [e.g. mol/dm3/s]

26. Reaction Rate
• rj is the rate of formation of species j per
unit volume [e.g. mol/dm3*s]
• rj is a function of concentration,
temperature, pressure, and the type of
catalyst (if any)

27. Reaction Rate
• rj is the rate of formation of species j per unit
volume [e.g. mol/dm3/s]
• rj is a function of concentration, temperature,
pressure, and the type of catalyst (if any)
• rj is independent of the type of reaction system
(batch reactor, plug flow reactor, etc.)

28. Reaction Rate
• rj is the rate of formation of species j per
unit volume [e.g. mol/dm3/s]
• rj is a function of concentration,
temperature, pressure, and the type of
catalyst (if any)
• rj is independent of the type of reaction
system (batch, plug flow, etc.)
• rj is an algebraic equation, not a
differential equation

29. General Mole Balance

30. General Mole Balance

31. Batch Reactor Mole Balance

32. CSTR
Mole Balance

33. Plug Flow Reactor

34. Plug Flow Reactor Mole Balance
PFR:
The integral form is: V
dFA
rA
FA 0
FA

This is the volume necessary to reduce the entering molar flow rate (mol/s) from FA0 to the
exit molar flow rate of FA.

35. Packed Bed Reactor
Mole Balance
PBR
The integral form to find the catalyst weight is: W 
dFA

rA
FA 0
FA

FA0 FA  
rAdW 
dNA
dt


36. Reactor Mole Balance Summary

37. Fast Forward to the Future
Thursday March 20th, 2008
Reactors with Heat Effects

38. Production of Propylene Glycol in an Adiabatic
CSTR

39. What are the exit conversion X and exit temperature T?
Solution
Let the reaction be represented by

48. KEEPING UP

49. Separations
These topics do not build upon one another
Filtration Distillation Adsorption

50. Reaction Engineering
These topics build upon one another
Mole Balance Rate Laws Stoichiometry

51. Mole Balance
Rate Laws
Stoichiometry
Isothermal Design
Heat Effects

52. Mole Balance Rate Laws

53. Mole Balance
Rate Laws
Stoichiometry
Isothermal Design
Heat Effects

62. Batch Reactor Mole Balance

63. Batch Reactor Mole Balance

64. Batch Reactor Mole Balance

65. Batch Reactor Mole Balance

66. Batch Reactor Mole Balance

67. Continuously Stirred Tank Reactor
Mole Balance

68. Continuously Stirred Tank Reactor
Mole Balance

69. Continuously Stirred Tank Reactor
Mole Balance

70. C S T R
Mole Balance

71. CSTR
Mole Balance

72. Plug Flow Reactor

73. Plug Flow Reactor Mole Balance
PFR:

74. Plug Flow Reactor Mole Balance
PFR:

75. Plug Flow Reactor Mole Balance
PFR:

76. Plug Flow Reactor Mole Balance
PFR:

77. Plug Flow Reactor Mole Balance
PFR:

78. Plug Flow Reactor Mole Balance
PFR:
The integral form is: V
dFA
rA
FA 0
FA


79. Plug Flow Reactor Mole Balance
PFR:
The integral form is: V
dFA
rA
FA 0
FA

This is the volume necessary to reduce the entering molar flow rate (mol/s) from FA0 to the
exit molar flow rate of FA.

80. Packed Bed Reactor Mole
Balance
PBR

81. Packed Bed Reactor Mole
Balance
PBR
FA0 FA  
rAdW 
dNA
dt


82. Packed Bed Reactor Mole
Balance
PBR
FA0 FA  
rAdW 
dNA
dt


83. Packed Bed Reactor Mole
Balance
PBR
FA0 FA  
rAdW 
dNA
dt


84. Packed Bed Reactor Mole
Balance
PBR
The integral form to find the catalyst weight is: W 
dFA

rA
FA 0
FA

FA0 FA  
rAdW 
dNA
dt


85. Reactor Mole Balance Summary

86. Reactor Mole Balance Summary

87. Reactor Mole Balance Summary

88. Reactor Mole Balance Summary

98. Chemical Reaction Engineering
Asynchronous Video Series
Chapter 1:
General Mole Balance Equation
Applied to
Batch Reactors, CSTRs, PFRs,
and PBRs

99. http://www.engin.umich.edu/~cre

106. Chemical Reaction Engineering
Chemical reaction engineering is at the heart of virtually
every chemical process. It separates the chemical engineer
from other engineers.
Industries that Draw Heavily on Chemical Reaction
Engineering (CRE) are:
CPI (Chemical Process Industries)
Dow, DuPont, Amoco, Chevron
Pharmaceutical – Antivenom, Drug Delivery
Medicine – Tissue Engineering, Drinking and Driving

107. Compartments for perfusion
Perfusion interactions between
compartments are shown by arrows.
VG, VL, VC, and VM are -tissue water
volumes for the gastrointestinal,
liver, central and muscle
compartments, respectively.
VS is the stomach contents volume.
Stomach
VG = 2.4 l
Gastrointestinal
VG = 2.4 l
tG = 2.67 min
Liver
Alcohol
VL = 2.4 l
tL = 2.4 min
Central
VC = 15.3 l
tC = 0.9 min
Muscle & Fat
VM = 22.0 l
tM = 27 min

109. Chemical Reaction Engineering
Chemical reaction engineering is at the heart of virtually
every chemical process. It separates the chemical engineer
from other engineers.
Industries that Draw Heavily on Chemical Reaction
Engineering (CRE) are:
CPI (Chemical Process Industries)
Dow, DuPont, Amoco, Chevron
Pharmaceutical – Antivenom, Drug Delivery
Medicine –Pharmacokinetics, Drinking and Driving
Microelectronics – CVD

110. Reaction Rate
Consider the isomerization AB
rA = the rate of formation of species A per unit volume

111. Reaction Rate
Consider the isomerization AB
rA = the rate of formation of species A per unit volume
-rA = the rate of a disappearance of species A per unit volume

112. Reactor Mole Balance Summary