Chapter 1 Lecture 2 Kzks

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CCB 3043Kinetics and Reactor Design

CHAPTER 1: Mole

Balances

Lecture 2

Failure is a step forward to success


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Topics

Lecture

1:

Chemical Identity

Reaction Rate

Lecture

2:

General Mole Balance Equation

Mole Balance for Different Reactor

Types

Lecture

3:

Mole Balance for Different Reactor

Types

Examples


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Types of Reactor:

1. Batch reactor

2.

Continuous-Stirred Tank Reactor(CSTR)

3. Plug Flow Reactor (PFR) or

Turbular Reactor4. Packed Bed Reactor (PBR)


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Industrial reactors

Types of reaction

Liquid phase reaction Gas phase reaction

Semi batch reactor,

CSTR Tubular reactor


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Different types of reactor:

1) Batch reactor Physical shape: Tank

Used for:

small scale operation process that is not suitable for continuous operation.

Advantage: High conversion longer residence time

DisadvantageHigh cost

Product variability

Not for large-scale operation


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2) Continuous-Stirred Tank Reactor (CSTR) Physical shape: Tank

Continuous Flow, Steady state, Perfectly mixed

Used for: Liquid phase reaction

process that is suitable for continuous operation.

Advantage: Continuous operation

Disadvantage Not for non-ideal mixing


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3) Plug Flow Reactor (PFR) Physical shape: Cylindrical pipe

Continuous Flow, Steady state, Perfectly mixed

Used for:Gas phase reaction

Reaction rate varies axially NOT radially.

Reactant Product


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4) Packed Bed Reactor (PBR)

Physical shape: Cylindrical

Continuous Flow, Steady state, Perfectly

mixed

Used for:

Fluid-solid heterogeneous reaction (catalyst)

Reactant Product


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Photos of real reactor systems

Batch reactor


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CSTR



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PFR


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IN OUT + GENERATION = ACCUMULATION

For species A:Any REACTOR with volume V

UNIT: moles/time

FAO FA GA dNA/dt

Number of moles of speciesA in a system

Rate of generation of speciesA in a system


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IN OUT + GENERATION = ACCUMULATION

FAO

FA

GA

dNA/dt


dtdNdVrFF

dt

dNGFF

A

V

AAA

A

AAA

0

0


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Mole Balance For Different

Reactor Type Batch reactor

dt

dNVr

A

A

dt

dNdVrFF

AV

AAA 0

dt

dNVr

A

A.


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Reactor Type

dt

dNdVrFF

AV

AAA 0 Continuous stirred

tank reactor (CSTR)

A

AA

r

FFV

0

00

AAA

VrFF


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Reactor Type Plug Flow Reactor

(PFR)

dt

dNdVrFF

AV

AAA 0


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Reactor Type Packed Bed Reactor

(PBR)

-rA

= mol A reacted

time. mass of catalyst


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SUMMARYReactor Mole Balance Remarks

Batch Well mix, no

spatial

variation,

unsteady stateCSTR Well mix, no

spatial

variation,

steady state

PFR Steady state

PBR Steady state

dt

dNVr

A

A


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Assignment:

Due Thursday Next Week:6th June, 2013

Essentials of Chemical ReactionEngineering, H. Scott Fogler

1. P1-3A2. P1-13B (a) and (c)


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ANY QUESTION ???

Documents

Chapter 1 Lecture 2 Kzks