Chemical reaction engineering is that engineering activity which is concerned with the exploitation of chemical reactions on commercial scale. The areas of different fields of science like: Oil Refining Pharmaceuticals Biotechnology Chemical Industries Sustainable Development

1. Contents:
 Batch Reactor and Plug Flow Reactor by
Aamir Shahzad
 Mixed Flow Reactor by
Hafiz Shoaib Munir
 Reactions by
M. Waqas Nawaz
 Stoichiometry by
Ateeq U Rehman

2. MIXED FLOW REACTOR/CSTR

3. Definition
•The continuous flow stirred-
tank reactor (CSTR), also known as back-mix
reactor.
•In a perfectly mixed reactor, the output
composition is identical to composition of the
material inside the reactor, which is a function
of residence time and rate of reaction.

4. MFR/CSTR
• A continues stirred tank reactor(CSTR) is a vessel to
which reactants are added and products removed while
the contents within the vessel are vigorously stirred
using internal agitation.
• At steady state, the flow rate in is must be equal to
flow rate out.

5. Basic Terms
• Back Mixing:
The tendency of reacted chemicals to
intermingle with unreacted feed in reactors, such as stirred
tanks, packed towers, and baffled tanks.
• Residence Time Distribution:
The residence time
distribution (RTD) of a chemical reactor is a probability
distribution function that describes the amount of time
a fluid element could spend inside the reactor

7. Mole Balance on CSTR

8. APPLICATIONS
• CSTRs are most commonly used in industrial
processing , primarily in homogeneous liquid-phase
flow reactions, where constant agitation is required.
• Fermentors are CSTRs used in biological processes in
many industries, such as brewing, antibiotics and
waste treatment.
• In fermenters, large molecules are broken down into
smaller molecules, with alcohol produced as a by-
product.

9. Methane Gas tank Fermentation tank

10. ADVANTAGES
Cheap to construct.
Good temperature control is easily maintained.
Reactor has large heat capacity.
Interior of reactor is easily accessed.

11. DISADVANTAGE
•Conversion of reactant to product per volume of reactor
is small compared to other flow reactors.

12. Batch Flow & Plug Flow Reactor
•Presented by
Aamir Shahzad

13. REACTORS
Definition:
A reactor is a system (volume) with boundaries. Mass may enter
and leave across boundary.
Characteristics:
System:
1. Closed or intermittent: no mass enters or leaves during reaction(s) are
batch or semi-batch reactors
2. Open (control volume): mass enters/leaves during reaction(s) are
continuous flow reactors

14. Batch Reactor
Introduction:
 The batch reactor is the generic term for a type
of vessel widely used in the process industries.
 Vessels of this type are used for a variety of process
operations such as solids dissolution, product
mixing, chemical reactions, batch
distillation, crystallization, liquid/liquid extraction
and polymerization.
 In some cases, they are not referred to as reactors but have a
name which reflects the role they perform (such
as crystallizer, or bioreactor).

15. Construction:
A typical batch reactor consists of a tank with
an agitator and integral heating/cooling system.
These vessels may vary in size from less than 1 litre to
more than 15,000 litres.
They are usually fabricated in steel, stainless steel, glass-
lined steel, glass or exotic alloy.
Liquids and solids are usually charged via connections in
the top cover of the reactor.
Vapours and gases also discharge through connections in
the top. Liquids are usually discharged out of the bottom.

16. Heating and Cooling Systems
• Products within batch reactors usually liberate or absorb heat during
processing.
• Even the action of stirring stored liquids generates heat.
• In order to hold the reactor contents at the desired temperature, heat
has to be added or removed by a cooling jacket or cooling pipe.
• Heating/cooling coils or external jackets are used for heating and
cooling batch reactors. Heat transfer fluid passes through the jacket or
coils to add or remove heat.
• Within the chemical and pharmaceutical industries, external cooling
jackets are generally preferred as they make the vessel easier to clean.

17. Working Principle:
A batch reactor has neither inflow nor outflow of
reactants or products while the reaction is being
carried out.
This is an unsteady state operation where
composition changes with time.
However, it is assumed that at any instant the
composition throughout the reactor is uniform (in
composition and temperature etc), because of
efficient stirring.

18. Advantages
 The advantages of the batch reactor lie with its versatility.
 A single vessel can carry out a sequence of different operations without
the need to break containment.
 This is particularly useful when processing toxic or
highly potent compounds.

19. Applications:
Batch reactors are often used:
 In the process industry.
 In many laboratory applications, such as small scale production and inducing
fermentation for beverage products.
 In medical production.
 for experiments of reaction kinetics, volatiles and thermodynamics.
 Highly used in waste water treatment.
 Effective in reducing BOD (biological oxygen demand)of influent untreated
water.

20. Plug Flow Reactor
20
 Fluid passes through the reactor with no mixing of earlier and later
entering fluid, and with no overtaking.
 It is as if the fluid moved in single file through the reactor.

21.  In an ideal plug flow reactor, it is assumed that there is no mixing of the medium
along the long axis (X-axis) of the reactor although there may be lateral mixing in
the medium at any point along the long axis (ie the Y-axis).

22. Assumptions:
 Plug flow
 Steady state
 Constant density (reasonable for some liquids but a 20% error for
polymerizations; valid for gases only if there is no pressure drop, no
net change in the number of moles, nor any large temperature change)
 Single reaction occurring in the bulk of the fluid (homogeneously).

23. Applications:
Plug flow reactors are used for some of the following applications:
 Large-scale production
 fast reactions
 Homogeneous or heterogeneous reactions
 Continuous production
 High-temperature reactions

24. Advantages and Disadvantages of Plug flow Reactor
Advantages:
 Easily maintained as there are no moving parts.
 High conversion per unit volume.
 Unvarying product quality.
 Good for studying rapid reactions.
Disadvantages:
 Poor temp control.
 Hot spots may occur when used for exothermic reactions.

25. Order of Reaction
•Presented by
M. Waqas Nawaz

26. Order Of Reaction
For a general reaction between A and B where
‘a’ moles of A and ‘b’ moles of B react to form ‘c’ moles
of C and ‘d’ moles of D .
aA + bB cC + dD
We can write rate equation

27. R = [A]a[B]b
The exponent ‘a’ and ‘b’ gives the order of reaction with
respect to the individual reactant.
Thus
Overall order of reaction = (a+b)

28. Define :
The sum of all the exponent to which the
concentration in the rate equation are raised.

29. Facts
The order of react is an experimentally determined quantity and can
not be determined by simply looking at the reaction equation.
The sum of exponents in the rate equation may and may not be same
as in chemical equation .

30. The Chemical reaction are classified as
 Zero
 First
 Second
 Third
The order of reaction provides valuable information about
mechanism of a reaction.

31. Order of Reaction
Decomposition of nitrogen pentaoxide involves the following equation
2N2O5 2N2O4 + O2
Rate = K [N2O5]
First Order reaction

32. Hydrolysis of tertiary butyl bromide
(CH3)3CBr + H20 (CH3)3COH + HBr
Rate = k [ (CH3)3CBr ]
pseudo First order reaction

33. Finding order of reaction
• Method of Hit and Trail
• Graphical method
• Differential method
• Half life method
• Method of Large Excess