Design of homogeneous reactots, Application, Equation

1. GROUP A

2.  Reactor design uses information, knowledge, and experience
from a variety of areas-thermodynamics, chemical kinetics,
fluid mechanics, heat transfer, mass transfer, and economics.
 Chemical reaction engineering is the synthesis of all these
factors with the aim of properly designing a chemical reactor.
 To find what a reactor is able to do we need to know the
kinetics, the contacting pattern and the performance equation.
 This is called a performance equation.

3.  Performance equation of any reactor is function of inputs, contacting
pattern and reaction kinetics.
 Inputs:
For a chemical reaction in puts are reactants. Performance and design of
reactor depends upon quality, purity, temperature of reactants.
 Contacting pattern:
Contacting pattern or how materials flow through and contact each other in a
reactor, how early and late they mix, their clumpiness or state of aggregation.
 Reaction kinetics:
Kinetics tells how fast things will happen. If very fast, equilibrium tells what
will leave the reactor. If not fast then rate of chemical reaction or maybe mass
and heat transfer will determine what will happen.

4.  Homogeneous reaction is a one in which the reactants are in single phase. Or to
put it blatant terms, in homogeneous reaction one reactant can easily collide with
another reactant to form the product. Unlike heterogeneous reaction there are no
mass transfer constraints.
 Some homogeneous reaction examples

5.  Mol balance:
 We get;

6. In terms of moles(Nj)
In terms of concentration(Cj)
In terms of conversion(X)

7.  Mol balance:
 We get;

8. In terms of flowrates:
In terms of concentration
In terms of conversion

9.  Mol balance:
 We get;

10. In terms of flowrate
In terms of concentration nil
In terms of conversion

11.  The algebraic equation that relates –ra to the species concentration is called the
kinetic expression or rate law.
-ra = (k(T))(fn(Ca,Cb,……)
 Where k is called the rate constant and is a function of temperature.
 These relationships between rate and fn(Cn) is certainly observed by experiments
but functional dependence may be postulated through a theory. The most general
form of dependence is the power law model which is expressed as

13.  Irreversible reactions:
Irreversible reactions are those where equilibrium does not exist. The reaction stops
when the reactants are completely converted.
 Reversible reactions:
Reactions reaction can proceed in either directions weather towards products or
reactants depending upon equilibrium constant Ke.

14.  Some important conversions to remember.

15.  For batch systems:

16.  For flow systems:

17.  When the moles of entering reactants are not equal to the moles of the products
then the system is said to be variable volume system.
 Example:
 For batch reactor:
Where V is equal to

18.  And
 For flow systems:
 Where volumetric flow rate can be expanded to

19.  Putting together concentrations for variable volume systems for the reaction;

20.  In liquid phase reactions, the affect on concentration is insignificant even by large
pressure drops. So we completely ignore pressure drop when it comes to liquids.
But for the gas phase reactions, the concentration of species is directly
proportional to the total pressure, so pressure drop causes a significant change in
concentration of gas phase reactions
 Differential expression for pressure drop is as follows;

21. Steps
for
reactor
design

22.  Chemical Synthesis
 Pharmaceutical Manufacturing
 Food and Beverage Industry
 Petrochemical Industry
 Biotechnology and Enzyme Reactions
 Waste Treatment and Environmental Applications
 Research and Development
 Pilot Plants

23.  Water Treatment: CSTRs are commonly used in water treatment processes, such as
the removal of contaminants
 Fermentation Processes: CSTRs are extensively used in fermentation processes for
the production of various products, such as alcoholic beverages
 Chemical Synthesis: CSTRs find application in chemical synthesis, particularly for
reactions that require continuous mixing and control over reaction parameters
 Bioreactors: CSTRs are commonly used as bioreactors in the biotechnology and
pharmaceutical industries.
 Chemical and Petrochemical Industry: CSTRs are utilized in the chemical and
petrochemical industry for a wide range of processes.

24.  Petrochemical Processing: PFRs are commonly used in the petrochemical industry for
processes such as catalytic cracking, hydrocracking, and reforming.
 Chemical Synthesis: PFRs find application in chemical synthesis processes that require
precise control over reaction conditions and high product selectivity.
 Gas-Phase Reactions: PFRs are well-suited for gas-phase reactions where reactants are
in the gaseous state.
 Specialty Chemical Production: PFRs are used in the production of specialty chemicals,
including fine chemicals, pharmaceutical intermediates, and high-value compounds.
 Continuous Flow Processes: PFRs are employed in continuous flow processes, where
reactants are continuously fed into the reactor and products are continuously withdrawn.
 Polymerization: PFRs find application in polymerization processes, particularly for the
production of linear polymers.