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BIBLIOGRAPHYBIBLIOGRAPHY
Octave Levenspiel, Chemical Reaction Engineering, Third
Edition, John Wiley & Sons, New York, 1999
Ronald W. Missen, Charles A. Mims, Bradley A. Saville,Introduction to Chemical Reaction Engineering and Kinetics,
John Wiley & Sons, New York, 1999
E. Bruce Nauman, Chemical Reactor Design, Optimization, and
Scale-up, McGraw-Hill, New York, 2002
Lanny D. Schmidt, The Engineering of Chemical Reactions,
Oxford University Press, New York, 1998
Chemical ReactorsChemical Reactors
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BIBLIOGRAPHY (Cont.)BIBLIOGRAPHY (Cont.)
Holland, C.D., Anthony, R.G., Fundamentals of Reaction Engineering,
Prentice-Hall Inc., Englewood Cliffs, 1979. Froment, G.F., Bischoff, K.B., Chemical Reactor Analysis and Design, John
Wiley & Sons, New York, 1979. Lee, H.H., Heterogeneous Reactor Design, Butterworth Publishers, Boston,
1985. Levenspiel, O., The Chemical Reactor Omnibook+, OSU Book Stores Inc.,
Corvallis, 1984. Danckwerts, P.V., Gas-Liquid Reactions, McGraw-Hill, New York, 1970. Denbigh, K.G., Turner, J.R., The Chemical Reactor Theory - an Introduction,
2
nd
edition, Cambridge Univ. Press, 1971. Hill, C.G. jr., An Introduction to Chemical Kinetics and Reactor Design, John
Wiley & Sons, New York, 1977. Tarhan, M.O., Catalytic Reactor Design, McGraw-Hill, New York, 1983 Lavric, V., Chemical Reactors, 1996 (UPB lithography)
Chemical ReactorsChemical Reactors
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ExaminationExamination
Written test multiple choices, five variants to select from; free access to alldocumentation
The rules of grading:
A) no answer checked, Zero points;
B) all answers checked, Zero points;
C) for the rest, the following formula applies:
where gstands for the number ofgood answers checked,pgstands for the weight
fraction of the answergand b stands forbad answers checked.
Examples:C.1 in all, three good answers ( weight each), all checked: since no
bad answer is checked;
C.2 two good answers and one bad:
C.3 no good answer and one bad answer: Zero
Chemical ReactorsChemical Reactors
1gg pP
b
13 3 10 1
P
12 13
1 1 3P
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Definition:
The Chemical Reactor is the confined space where a
chemical process develops, resulting in transformation of
some species (reactantsreactants) in others (productsproducts), under strict
observation of the mass conservation laws.
Chemical ReactorsChemical Reactors
Every industrial chemical process aims towards economicalleconomicallyfabricating a desired productdesired product from a variety of starting materials
through a succession of treatment steps, which can be abstracted in
a general processing flowsheet.
The Hybrid Chemical Reactor, ensures in situseparation of
the valuable product or intermediate, not only lowering the
overall production costs, but increasing the process rate due
to higher chemical driven forces.
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The flowsheet of a typical chemical process
Chemical ReactorsChemical Reactors
Products
Row materials
Pre-chemical
processing physi-
cal treatment Chemical processingstages
Post-chemical
processingphysical treat-
ment steps
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Design of the chemicalreactor - many alternatives
can be proposed for a process.
Optimum solution concerns
not just the chemical reactor.
One design may have lowchemical reactor cost, but the
materials leaving the unit may
be such that their treatment
requires much higher costs.
The economics of the over-all
process must be considered
Chemical ReactorsChemical Reactors
Predictions not suffi-
ciently close to reality
Abstraction
RealityThe process to be known
and studied
Mathematical Model
The reality as we
are able to predict it
Physical ModelThe reality as we
are able to grasp
Simplifying
Assumptions
Boundary
Conditions
Improvement
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Information used in chemical reactor modeling
Chemical ReactorsChemical Reactors
Automation
& ControlThermo-
dynamics
Stoichiome
try & Ki-
netics
Balance
equations
Chemical
Reactor
Modeling
Momentum
transport
Heat
transport
Mass
transport
Phases
flow
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Classification of chemical reactions useful in reactor modeling
Chemical ReactorsChemical Reactors
Oxidation of SO2
to SO3
Reduction of iron ore to
iron and steel
Cracking of crude oilGas-liquid absorption with
reaction
Attack of solids by acids
Oxidation of ammonia to produce
nitric acid
Roasting of ores
Ammonia synthesisBurning of coal
Hetero-geneous
Enzyme and microbial reactions
Reactions in colloidal systemsFast reactions such as burning
of a flame
Most liquid-phase reactionsMost gas-phase reactions
Homo-
geneous
CatalyticNon-catalytic
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chemical species are denoted byAj, wherej=1,,Swith Sbeing the number
of all chemical species involved in the chemical process;
stoichiometric coefficients are denoted by j, for a single reactions and ij for
multiple reactions, with i=1,,R, where Rstands for the total number of
chemical reactions between the Schemical species; the stoichiometric coefficients for products are positive, while for reactants
are negative, to show the progression of the chemical process
Elements of systematicElements of systematic
stoichiometrystoichiometry
Single reactions1
0S
j j
j
A
Multiple reactions1 1
0R S
i j j
i j
A
0A rank
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Measuring the progress of a chemical process - quantifying the degree of
participation of a molecular species in this chemical process
intensive units - normalized value, independent of the starting point
extensive units/variables their values will depend upon the initial quantity
of each and every species participating at the chemical process
As intensive variable, theconversion is the widest used;
As extensive variable, the degree of advancement or the reaction extentarethe
widest used.
The rule of thumb advocates that, for a single reaction chemical process,
conversion is the appropriate measure of transformation, while the degree of
advancement should be used for all other cases.
Measuring the progress of theMeasuring the progress of the
chemical processchemical process
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The conversion
Single reaction chemical process
Measuring the progress of theMeasuring the progress of the
chemical processchemical process
1
0S
j j
j
A
dr
k
ka A b B q Q s S K K
The degree of transformation for each reactant species is given by
the fractional conversions
0 0
0 0
; A A B BA BA B
N N N N X X
N N
0
0
AB A
B
NbX X
a N
0 1 A A A N N X
0 B A BA A
b N N M X
a
0Q A QA A
q N N M X
a
0S A SA A
s N N M X
a
0
0
jA
jA
A
NM
N
Limiting reactant
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The degree of advancement / The extent
Single reaction chemical process
Measuring the progress of theMeasuring the progress of the
chemical processchemical process
1
0S
j j
j
A
0
; 1, 2, ,
j jA A
j
N N
j S
K
0j j A A jN N
Multiple reaction chemical process
0
; 1, 2, ,j jA A i
i
ij
N Ni R
K
0
1
j j
R
A A ij i
i
N N
0
1 1
S R
T ij i
j i
N N
1 1
0R S
i j j
i j
A
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Molar concentration
Single reaction chemical process constant volume
Composition of the chemical mixtureComposition of the chemical mixture
Single reaction chemical process variable volume
j
j
A
A
NC
V
0j
j
A A jA AC C M X a
0
0
0 1 1j
jj
A jA A jA A
A A
A A A A
N M X M Xa aC C
V x X
0 1
00 1
0 1 0
1
for gas phase reactions
for liquid phase reactions
A A
AA A
A A A
A
X X
XX X
A
X X X
X
N N
NV V
V
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Molar fraction
Single reaction chemical process
Composition of the chemical mixtureComposition of the chemical mixturej
j
A
A
T
Ny
N
0
0
1 1
j
jj
A jA A jA A
AS Sj j
A jA A jA A
j j
N M X M Xa ay
N M X M X a a
Multiple reaction chemical process
0 0
1 1
0
1 1 1 1
1
j j
j
R R
A ij i A ij M ii i
A S R S R
ij i ij M i
j i j i
N yy
N
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ThermodynamicsThermodynamics the heat liberated or absorbed during the chemical process
the maximum possible extent of reaction
ThermodynamicsThermodynamics
0 0
1
lnj
S
j A
j
G G RT K
,1
j
S
p j p Aj
C C
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Chemical kineticsChemical kinetics concerned with the rates and mechanisms of chemical reactions;
search for the factors that influence the rate of reaction;
tool for: gaining insight into the reacting systems nature, understanding how
chemical bonds are made/broken, and estimating their energies and stability;
the mode of reaction of compounds provides clues to their structure;
the basis for important theories in combustion and dissolution;
permit satisfactory design of equipments to effect the reactions on a technical
scale
in polymerization processes: the stoichiometry and kinetics are complex. A
polymer is always a mixture of macromolecules having different chain lengths -statistics can be used, to simplify the mathematical treatment, lumping the infinite
number of conservation equations (polymers and/or free radicals) into an easier
mathematical model, focused on several characteristics of the molecular mass
distribution, like mean, dispersion and symmetry;
Chemical kineticsChemical kinetics
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Equilibrium of Elementary Reversible Reactions
Chemical kineticsChemical kinetics
,d
r
k
Ck
A B Q S K
forward d A Br k C C reverse r Q S r k C C
, , 0S forward S reverser r Equilibrium
d R SC
r A B
k C CK
k C C
Molecularity and Order of Reaction Homework
Temperature dependent term of a rate equation Homework
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Chemical Processes KineticsChemical Processes Kinetics
Searching for a mechanism (Lavric, 1996)
homework