Chemical Process Development (Scale up issue in chemical industry) A. Hisyam Faculty of Chemical and Natural Resources Engineering University Malaysia Pahang

Resources E. Tirronen and T. Salmi, Chemical Engineering Journal 91 (2003) 103-114 G. Donati and R. Paludetto, Catalysis Today 34 (1997) 483-533

Chemical process development may have one of the following objectives Design and construction of a new plant (grass root designing) The design and development of a new process for an old process (modernizing an existing plant) Modifications and additions to existing plant; usually carried out by the plant design group (process modification)

Phases of chemical process development Conceptual chemical phase Conceptual process development phase Chemical and process development phase and process engineering phase Commissioning and start up phase

Conceptual chemical phase Identification of different chemical routes Do you know how many ways we can produce eugenol from clove oil? Generation of alternative chemical synthesis pathways process schemes Find other possible ways to produce ethanol other than fermentation from glucose Preliminary experiments Preliminary process scheme Preliminary cost estimation

Conceptual process development phase Mass balance Preliminary heat balance Preliminary block diagram and flowsheet Gantt Chart for scheduling Production capacity Cost estimation Preliminary safety evaluation

Gantt chart

Chemical and process development phase and process engineering phase Dynamic reactor model generation and calculation Dynamic separation model generation and calculation Scale up of process and equipment Control design Dynamic utility calculation Dynamic waste and emission calculation

Commissioning and start up phase Operator training Troubleshooting Model validation Optimization Process improvements

Chemical and process engineering

Process models Kinetic models Reactor models Liquid phase Gas phase Interfacial fluxes Solid-liquid reaction Catalytic reaction

Scale up issue Similarity principle says that “For any two dynamically similar systems, all the dimensionless numbers necessary to describe the process have the same numerical value”.

Similarity Geometrical Kinematic Dynamic

Scale up procedure Describe the process using a complete set of dimensionless numbers Match these numbers at different scales

Dimensional analysis Dimensional analysis is a method for producing dimensionless numbers that completely describe the process. The analysis should be carried out before the measurements have been made, because dimensionless numbers essentially condense the frame in which the measurements are performed and evaluated. It can be applied even when the equations governing the process are not known.

Dimensional analysis Newton (Np) Froude (Fr) Reynolds (Re) P - power consumption [ML2T-5] ρ - specific density of particles [M L-5] n - impeller speed [T-1] d - impeller diameter [L] g - gravitational constant [LT-2] η - dynamic viscosity [M L-1 T-1]

Résumé Dimensional Analysis provides a powerful scientific technique for scale up This technique is proven by a century of engineering applications Rational scale-up should replace empirical approach

Thank you This material is downloadable from: http://allaboutchem.wordpress.com