chpr5501 adv. reaction eng. part 1
DESCRIPTION
Lectures 1, 2, and 3TRANSCRIPT
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CHPR5501: Advanced Reaction Engineering and Catalysis
Winthrop Prof. Mike Johns
School of Mechanical and Chemical Engineering
University of Western Australia
Storage for
feedstock
A
R-102
R-101C100
C101
E100 E101E102
E103
E104
E105
E106
V100
V101
P100
P101
Storage for
feedstock
A
R-102
R-101
Storage for
feedstock
A
R-102
R-101C100
C101
E100 E101E102
E103
E104
E105
E106
V100
V101
P100
P101
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Evolving Course Outline CHPR5501: Advanced Reaction Engineering and Catalysis
Winthrop Professor Mike Johns
Week / Start Date Tuesday 9:00-9:45
Thursday 10:00-10 :45
Thursday 11:00-11:45
1 / 23 Feb 2015 L1:Reaction Engineering Intro
L2: Reactors: Type and Modelling
L3: Reactors: Type and Modelling
2 / 2 March 2015 L4: Reactors Residence Time Distributions
> Release of Tutorial 1: Reactors: Intro, Modelling
and RTDs
L5: Reactors Residence Time Distributions
Release of Assign. 1 (Group):
Gas-to-Liquid Submit by: 4:30 pm 20th
April 2015 (Monday)
L6: Heterogeneous Reactions
3 / 9 March 2015 NO LECTURE
L7: Heterogeneous Reactions
> Release of Tutorial 2: Heterogeneous Catalysis
L8: Electrochemical Reaction Origins of
Corrosion
4 / 16 March 2015 L9: Electrochemical Reaction Origins of
Corrosion
L10: Electrochemical Reaction Origins of
Corrosion
Tutorial 1: Reactors: Intro, Modelling
and RTDs
5 / 23 March 2015 L14: Fluidised Bed Reactors
L11: Corrosion Types
Tutorial 2: Heterogeneous Catalysis
6 / 30 March 2015 L15: Fluidised Bed Reactors Release of Assign. 2:
(individual) HYSYS Simulation
Submit by: 4:30 25th May (Monday)
L12: Corrosion Types L13: Corrosion Types > Release of Tutorial 3:
Corrosion
Mid-Term Break
Lecturers: Assist. Prof Agnes Haber/ Assist. Prof Einar Fridjonsson
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Evolving Course Outline Continued
Stuff in Red Bold Does Not Change
Assignment 1 (Group): Literature Survey and Technical Assessment 20 % Assignment 2: (Individual) Reaction kinetics and Simulation 15 % Mid-term Test: 10 % Exam: 55 %
7 / 13 April 2015 L16: Fluidised Bed Reactors
Release of Tutorial 4: Fluidisation
L17: Polymer Reaction Chemistry
Tutorial 3: Corrosion
8 / 20 April 2015 Tutorial 4: Fluidised Bed Reactors
L18: Polymer Reaction Chemistry
L19: Polymer Reaction Chemistry
Release of Tutorial 5: Polymer Reaction
Chemistry
9 / 27 April 2015 Mid-Term Test (30 Minutes)
L20: Bioreactors Tutorial 5 Polymer Reaction
Chemistry 10 / 4 May 2015 L21: Bioreactors
L22: Bioreactors
Release of Tutorial 6: Bioreactors
L 23: Catalysis - Introduction
11 / 11 May 2015 L24: Catalysis: Effectiveness Factor
L25: Catalysis: Effectiveness Factor
L26 Catalysis: Deactivation and Characterisation
12 / 18 May 2015 L27: Catalysis: Deactivation and Characterisation
Release of Tutorial 7: Catalysis
Tutorial 6 Bioreactors
Exam Preparation: Example Examination
Script
13/ 25 May 2015 Tutorial 7: Catalysis
Exam Preparation: Example Examination
Script
Exam Preparation: Example Examination
Script
Lecturers: Assist. Prof Agnes Haber/ Assist. Prof Einar Fridjonsson
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Sample Of Reaction Engineering Flow Sheet
Note series of reactors (Constant Stirred Tank Reactors)
Reactors: Introduction
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Reactions must often be catalysed with the catalyst being present either in the same physical phase (Homogenous) or (predominately) as a solid phase (Heterogeneous) Hence the distinction between Homogeneous and Heterogeneous Catalysis Heterogeneous Catalysis usually simplifies the phase separation of reactants/products and the catalyst but does require consideration of mass transfer to and from the catalytic surface.
Reactors: Introduction
Examples of Solid (heterogeneous) Catalysts
Note that many catalysts are impregnated on to the surface of a catalyst support providing a high surface-to-volume ratio. Examples of supports are Alumina, Carbon and Silica
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Batch: A fixed amount of material is processed (reacted) in a given time. Continuous: Material flows continuously into and out of the reactor.
Homogeneous Reactors
The reactors above are usually assumed to be WELL MIXED: the composition is the same throughout the vessel. In the case of the perfect Constant Stirred Tank Reactor (CSTR), the exit composition is assumed the same as that in the vessel. Cooling and heating are usually provided to such reaction vessels via either an external jacket or internal coils or both.
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CSTRs are good for liquid reactions. They are generally cheap and easy to run. A process might contain a series of CSTRS as in the example on slide 4.
Tubular or Plug Flow Reactor Geometry
> The tube can be a single, or a (parallel) bundle of, tubes not that dissimilar to a shell and tube heat exchanger. > Conditions change along the length of the reactor. Perfect plug flow assumes piston displacement and no mixing in the axial direction but perfect mixing in the radial direction. > Its a convenient way to pack catalyst pellets into a tube (of course thats heterogeneous Catalysis)
MOST REACTORS ARE IN BETWEEN A CSTR AND A PLUG FLOW REACTOR IN PRACTICE
Homogeneous Reactors
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Before Reactor design, the following are essential physical-chemical characteristics of the reaction taking place:
All of the above are of course functions of temperature - we will assume isothermal operation initially.
Homogeneous Reactors
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Rate of Reaction - r
A + B D + F
: a + b order
kf kb
Homogeneous Reactors
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Example Question
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Homogeneous Isothermal Reactors
It is common to use the dimensionless quantity, fractional conversion (XA), to convey extent of reaction.
Here defined for reactant A: NA0 number of kmols of A at time zero, NA is the number left.
Batch Reactor
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Let us consider a constant volume system:
A 4B
Homogeneous Isothermal Reactors
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Let us consider a constant pressure (gas) system:
A 4B
Homogeneous Isothermal Reactors
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Returning to the reaction rate:
From above two equations ([1] and [2]):
[1]
[2]
Homogeneous Isothermal Reactors Const. Pressure Batch Continued
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Example Question
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Analysis of Constantly Stirred Tank Reactors
Homogeneous Isothermal Reactors
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Example Homogeneous Isothermal Reactors
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Homogeneous Isothermal Reactors
Thats a 6.1 m diameter reactor! Likely in reality to be a series of reactors.
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Aside: Distinction between Space Time and Residence Time
Space Time ts: time required to process a volume of feed equal to the void volume of the reactor. For previous example: ts = V/Q1 = 229/1 = 229 s. Residence time t: actual time the fluid resides within the reactor. Only if the molar density of the fluid is constant will ts = t. In the previous example, the molar density is not constant. The number of kmols in the system increases via the ratio 1 -> (1+XA) : To maintain a constant pressure in a reactor of constant volume, the volumetric flow-rate leaving the reactor must increase accordingly. Q2 = Q1(1+XA) = 1(1.35) = 1.35 m
3/s Therefore t = V/Q2 = 229/1.35 = 170s.
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CSTR Liquid Phase Reaction Homogeneous Isothermal Reactors
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Homogeneous Isothermal Reactors
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Example Question
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Plug Flow Reactors (Gas Phase)
Homogeneous Isothermal Reactors
[7]
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Shown previously - slide 17
Homogeneous Isothermal Reactors (Slide 17)
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Homogeneous Isothermal Reactors
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Plug Flow Reactor (Liquid Phase) Homogeneous Isothermal Reactors
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Let us consider a graphical representation of a CSTR and a PFR
Homogeneous Isothermal Reactors
Consider a 1st order reaction:
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Homogeneous Isothermal Reactors
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Homogeneous Isothermal Reactors
The optimum depends on the shape of the curve:
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CSTRS in Series 1st order reactions Homogeneous Isothermal Reactors
For n CSTRs in series:
(Shown Previously)
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Example Question
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Product Degradation Batch Reaction
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Product Degradation Continuous Reactor
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Product Degradation Continuous Reactor