Unseen examination

70

Coursework

30

Qualifying Condition(s) 

A weighted aggregate mark of 40% is required to pass the module

To introduce students to: -

Heterogeneous Reactors

a)      The complications when mass transfer affects the observable kinetics of a reactor using examples of gas-solid reactions; a comprehensive introduction to shrinking core models will be presented.

b)      The design of fixed bed reactors including the complications associated with pressure drop, axial dispersion and heat transfer.

c)      The analysis of fluidisation and fluid bed reactors

Catalytic Reactors

a)      The design, simulation and interpretation of data from heterogeneous reactors to catalytic reactors.

b)      Some of the complicated interactions between intrinsic kinetics, mass transfer and heat transfer.

c)      The concept of effectiveness factor and how it may be calculated and measured.

d)      Basic experimental techniques for measuring kinetics and isotherms associated with the above.

Upon successful completion of this part of the module, you will be able to:

Heterogeneous Reactors

·       Select and use an appropriate shrinking core model to analyse experimental data and design reactors with specified, simple flow patterns in spherical, cylindrical and plane geometries.

·       Formulate and solve simple axially dispersed plug flow models and be able to include and justify the use of Danckwerts Boundary Conditions and use appropriate values of axial Peclet number.

·       Calculate pressure drops in packed beds over a wide range of particle Reynolds numbers and understand the critical role played by voidage in these equations.  

·       Derive and use the Carmen-Kozeny and Ergun equations in the appropriate situations.

Catalytic Reactors

·       Derive and use Langmuir, Freundlich and Toth isotherm equations.

·       Describe in detail experimental techniques to measure adsorption isotherms

·       Select and use an appropriate model combining external film mass transfer, intra-particle diffusion and intrinsic surface kinetics.

·       Design a simple catalytic PFR using the above models.

·       Interpret experimental results in terms of these models.

·       Specify additional experiments to distinguish between possible alternative models.

·       Discuss the causes of loss of catalyst performance.

Fluid Bed Reactors

·       Describe the three phase theory of Davidson and Harrison

·       Describe the Kunii and Levenspiel model of FBRs

·       Discuss the effects of bubble size and reaction kinetics on the conversion in comparison to CSTRs and PFRs

Case Studies – Describe and discuss:

·       Car exhaust converters

·       SEREBAR reactors for ground water treatment

Heterogeneous Reactors

• Introduction to heterogeneous reactors

   

• Gas-solid reactors and reactions

   

• Shrinking core models with external film control, ash diffusion control and reaction control.

   

• Variable size particles

   

• Effective diffusivity and tortuosity in ash layers

   

• Combined resistances

   

• Reactor design

   

• Axial dispersion and Danckwerts Boundary Conditions

   

• Asymptotic solutions, evaluation of axial Peclet number

   

• Pressure drop in packed beds, Darcy, Carmen-Kozeny and Ergun derivations and applications

   

• Introduction to catalysis and catalytic reactors

   

• Loss of catalyst performance – shrinking core analysis

   

• Car exhaust reactors – an example of extreme design requirements

   

Catalytic Reactors

• Introduction and revision on catalytic reactors

   

• Pore diffusion in slab, spherical and cylindrical geometries

   

• Effective diffusivity and tortuosity

   

• Mathematics of spherical and cylindrical pellets.

   

• An aside on Error, Bessel and Modified Bessel functions.

   

• External film mass transfer.

   

• Surface kinetics, Langmuir-Hinchelwood and Eley-Rideal

   

• Experimental techniques – Carberry basket and Berty reactors

   

• Non-isothermal reactors.

   

• Catalytic reactor design