Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
1
Dr.-Eng. Zayed Al-Hamamre
Chemical Reaction Engineering
Isothermal Reactor Design
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
2
Content
Batch Reactor
Design of CSTR Reactors
o Single CSTR
o CSTR’s in Series
o CSTR’s in Parallel
Design of PFR Reactors
Flow Through a Packed Bed
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
3
Isothermal reaction design
algorithm For conversion
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
4
Algorithm Isothermal reactor
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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5
For constant volume batch reactors
Batch Reactors
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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6
calculate the time necessary to achieve a given conversion X for the irreversible second-order
reaction
Example
and
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
9
Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
13
Example Cont.
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CSTR’s Design
Knowing that
This equation applies to a single
CSTR or to the first reactor of
CSTRs connected in series.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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A Single CSTR
CSTR’s Design
For a first-order irreversible reaction
For liquid-phase reactions, there is no volume change during the course of the reaction,
also
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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CSTR’s Design
The Damkohler number
Is the ratio of the rate of reaction of A to the rate of convective transport of A at the
entrance to the reactor
Give us a quick estimate of the degree of conversion that can be achieved in continuous
flow reactors
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
17
CSTR’s Design
For a first-order liquid-phase reaction in a CSTR
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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CSTR’s in Series
CSTR’s Design
The effluent concentration of reactant A from
the first CSTR can be found
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
19
CSTR’s Design
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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CSTR’s Design
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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CSTR’s Design
Conversion as a function of the number of tanks in series for
different Damkohler numbers for a first-order reaction
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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CSTR’s in Parallel
CSTR’s Design
If the reactors are of equal size, operate at the same temperature,
and have identical feed rates.
The conversion will be the same for each reactor
The rate of reaction in each reactor
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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CSTR’s Design
The total molar flow rate
Since
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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A Second-Order Reaction
CSTR’s Design
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CSTR’s Design
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
the single CSTR volume to achieve 80% conversion
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
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PFR Reactors Gas-phase reactions are carried out primarily in tubular reactors where the flow i s generally
turbulent
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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For the reaction
PFR Reactors
For the isothermal operation,
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Known that
PFR Reactors
For reaction in a Gas Phase
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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PFR Reactors
For the isothermal operation,
the effect of volume change with reaction
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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PFR Reactors
there i s no change in the number of mole with reaction
fluid moves through the reactor at a constant
volumetric flow rate as the conversion increases
there is a decrease in the number of moles in the gas phase
the gas molecules will spend longer in the reactor than
they would if the flow rate were constant resulting in a
higher conversion
there is an increase in the number of moles in the gas phase
then the volumetric flow rate will increase as the
conversion increase and the molecules will spend less time
in the reactor resulting in a lower conversion
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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38
PFR Reactors
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Determine the plug-flow reactor volume necessary to produce 300 million pounds of ethylene a
year from cracking a feed stream of pure ethane. The reaction is irreversible and fallows an
elementary rate law. We want to achieve 80% conversion of ethane. operating the reactor
isothermally at 1100 K at a pressure of 6 atm.
Example
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
For 2-in. schedule 80
pipes in parallel that are
40 ft in length.
The number of pipes
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Pressure Drop and the Rate Law
PFR Reactors
In packed-bed reactor
Since And for
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PFR Reactors
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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PFR Reactors
Flow Through a Packed Bed
The pressure drop in a packed porous bed to be calculated
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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For PBR operating at steady state,
Flow Through a Packed Bed
or
but
hence
Combining with Ergun Equation
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
mass of catalyst per volume of reactor bed
let
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
or
and
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
Two coupled first-order
differentia1 equations
In conclusion, for isothermal reactors
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
then
or
or
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Flow Through a Packed Bed
or
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Flow Through a Packed Bed
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example For the case where a second-order reaction
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Example
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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Example Calculate the catalyst weight necessary to achieve 60% conversion when ethylene oxide is to be
made by the vapor-phase catalytic oxidation of ethylene with air
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
Tel. +962 6 535 5000 | 22888
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Example Cont.
Chemical Engineering Department | University of Jordan | Amman 11942, Jordan
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SemiBatch Reactor