(123e) Benefits of Modeling for the Scale-up of Processes: Illustration on the Aspects of Heat Transfer for a Batch Reactor

Process development is now increasingly based on the use of simulation software that enables chemists and chemical engineers to understand the characteristics of these processes and define the possible areas of improvement in terms of operational safety, product quality and operating costs, on all phases of scale-up: from the laboratory to the pilot plant and then to the industrial unit. In processes using discontinuous chemical reactors (or fermenters), extrapolation is a particularly complex stage in the development phases.

Process extrapolation techniques are based on the principle of similarity (geometric, kinematic, dynamic, chemical and thermal) [1]. The implementation of these principles in a specialized software (BatchReactor) makes it possible to determine the characteristics of the reactor at a larger scale, based on the data collected at the laboratory stage. The rigorous modeling of the equipment allows the process engineer to refine the sizing for scale-up. This methodology will be presented on various examples, focusing on the heat transfer in batch reactors. A good control of the temperature throughout the reaction process makes it possible to guarantee the quality of the products and in many cases the safety of operation. The cooling (or heating) of the reactor will evolve throughout the production batch as these three parameters governing the heat exchange evolve: the exchange area (since the level in the tank is changing), the temperature difference (since the temperature in the reactor is changing), as well as the heat exchange coefficient (since the properties of the mixture in the vessel evolve). All these parameters must be correctly taken into account in the reactor model so that the designer can rely on accurate simulation results.

Data from laboratory experiments are of primary importance. Engineers and chemists should work together early in process development to allow the project team to think about potential large-scale problems long before scale-up. If possible, lab devices have to be scaled-down from industrial ones. Thermodynamic and kinetic models are the basis of a good modeling. Experimental work can be reduced with the help of a standardized protocol (e.g. Bourne protocol [2]) and/or the modeling of laboratory data (e.g. using BatchReactor). When a batch reactor model is built from laboratory data, it can be used to analyze invariant effects on scale-up and study synthesis at the industrial scale.

Keywords: batch chemical reactor; scale-up; modeling; heat transfer

References

[1] Kresta S.M., Etchells III A.W., Dickey D.S., Atiemo-Obeng V.A., (2016), Advances in Industrial Mixing, a Companion to the Handbook of Industrial Mixing.

[2] Bourne J.R., (2003), Org. Process Res. Dev., 7: 471 - 508.