(39b) How to Successfully Scale-up Batch Reactors

Process development is now increasingly based on the use of simulation software that enables 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 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). The implementation of these principles in a specialized software makes it possible to determine, from the exploitation of the data collected at the laboratory stage, the characteristics of the reactor on a larger scale. The rigorous modeling of the equipment thus determined allows the process engineer to refine the sizing carried out. This methodology will be presented on various examples, particularly relating to heat transfer in batch reactors. Indeed, only 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 the operation. However, the cooling (or heating) of the reactor will evolve throughout the production batch because the three parameters governing the heat exchange will 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 process fluid evolve). All these parameters must be correctly taken into account in the reactor model so that the designer can rely on accurate simulation results.