Scribd
Upload
557 views6 pages

Chemical Reaction Engineering

This document summarizes key concepts in chemical reaction engineering including: 1) Common reactor types like batch, continuous stirred tank (CSTR), plug flow, and packed bed reactors. 2) Equations to calculate conversion, reactor volume, and catalyst weight for different reactor configurations. 3) Concepts like reactors in series, space time, reaction stoichiometry, and determining rate constants. 4) Types of multiple reactions like parallel, series, and independent reactions.

Uploaded by

Ajay Sagar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
557 views6 pages

Chemical Reaction Engineering

This document summarizes key concepts in chemical reaction engineering including: 1) Common reactor types like batch, continuous stirred tank (CSTR), plug flow, and packed bed reactors. 2) Equations to calculate conversion, reactor volume, and catalyst weight for different reactor configurations. 3) Concepts like reactors in series, space time, reaction stoichiometry, and determining rate constants. 4) Types of multiple reactions like parallel, series, and independent reactions.

Uploaded by

Ajay Sagar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 6

Placement Team, Chemical Engg, IIT Madras 2012

Chemical Reaction Engineering


Rate of a reaction= -rA

How fast a reactant is consumed to form the product.


Three basic reactions are decomposition, isomerisation and combination
In heterogeneous cases like catalysis, rate is defined as the number of moles of A
consumed per mole of the catalyst used.

Standard mole balance:


In-Out + Generation = Accumulation

I. Batch Reactors
Used for small scale operations
Testing and R&D
Production of expensive products
Advantage- High conversion
Disadvantage: Costly, high variability

II. Continuous Stirred Tank Reactors(CSTRs)


Always operated at steady state
Most commonly used reactor type
Also called as back-mix reactor
Major assumption: contents are well mixed
No time or position dependence of temperature, concentration or reaction rate in the
reactor
Major assumption: Exit stream has same concentration as that of the reactor.

1|Page
Placement Team, Chemical Engg, IIT Madras 2012

III. Plug flow reactor:


Concentration varies continuously in the axial direction
No radial variation in reaction rate

IV. Packed bed reactor


Reaction takes place on the surface of the catalyst.
Reaction rate is a function of the mass of the catalyst rather than of reactor volume

V. Conversion (XA) = moles of A reacted/ Moles of A fed

Maximum conversion is equilibrium conversion.

Time taken to reach a particular conversion X:

2|Page
Placement Team, Chemical Engg, IIT Madras 2012

For CSTR:

For a conversion X, the volume of the reactor V is calculated as:

For PFR:

Reactor volume V can be calculated as:

For a Packed Bed Reactor:

The weight of the catalyst required can be calculated as:

VI. Reactors in Series:

3|Page
Placement Team, Chemical Engg, IIT Madras 2012

For CSTRs in series:

PFRs in series:

4|Page
Placement Team, Chemical Engg, IIT Madras 2012

Hence PFRs in series as good as a single PFR with the combined size.

VII. Space Time


Also known as holding time or mean residence time.
Obtained by dividing reactor volume by volumetric flow rate.

VIII. Stoichiometry
For a reaction,

For a reversible reaction, equilibrium constant is defined as:

5|Page
Placement Team, Chemical Engg, IIT Madras 2012

Determining the rate constant for any reaction(k):

Arrhenius method:

IX. Multiple reactions

Parallel Reactions Series reactions

Independent Reactions

References:
Fogler
Levenspiel

6|Page

You might also like