chpr5501 adv. reaction eng. part 1

CHPR5501: Advanced Reaction Engineering and Catalysis

Winthrop Prof. Mike Johns

School of Mechanical and Chemical Engineering

University of Western Australia

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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

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



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


Script


Script

Lecturers: Assist. Prof Agnes Haber/ Assist. Prof Einar Fridjonsson

Sample Of Reaction Engineering Flow Sheet

Note series of reactors (Constant Stirred Tank Reactors)

Reactors: Introduction

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

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.

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


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.


Rate of Reaction - r

A + B D + F

: a + b order

kf kb


Example Question

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

Let us consider a constant volume system:

A 4B


Let us consider a constant pressure (gas) system:

A 4B


Returning to the reaction rate:

From above two equations ([1] and [2]):

[1]

[2]

Homogeneous Isothermal Reactors Const. Pressure Batch Continued

Example Question

Analysis of Constantly Stirred Tank Reactors


Example Homogeneous Isothermal Reactors


Thats a 6.1 m diameter reactor! Likely in reality to be a series of reactors.

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.

CSTR Liquid Phase Reaction Homogeneous Isothermal Reactors

Example Question

Plug Flow Reactors (Gas Phase)


[7]

Shown previously - slide 17

Homogeneous Isothermal Reactors (Slide 17)

Plug Flow Reactor (Liquid Phase) Homogeneous Isothermal Reactors

Let us consider a graphical representation of a CSTR and a PFR


Consider a 1st order reaction:


The optimum depends on the shape of the curve:

CSTRS in Series 1st order reactions Homogeneous Isothermal Reactors

For n CSTRs in series:

(Shown Previously)

Example Question

Product Degradation Batch Reaction

Product Degradation Continuous Reactor

chpr5501 adv. reaction eng. part 1

Documents

catalysis tutorial

bioreactors tutorial

corrosion types tutorial

advanced reaction engineering

catalysis introduction

polymer reaction chemistry

catalysis exam preparation

heterogeneous catalysis