(97d) Shape Design of a Tubular Microreactor with Desired Product Distribution

Micro chemical process technologies offer much improved controllability of reaction conditions such as residence time, temperature and concentration distributions. A large number of papers say that the product yield and selectivity in microreactors are higher than those in conventional reactors. However, the design and operation conditions are actually determined by trial and error. In this research, a design approach for the microreactor with a desired residence time distribution (RTD) of a viscous fluid is proposed. The velocity profile of laminar flow and the interaction by molecular diffusion should be treated in the microreactor design. The proposed approach can systematically determine the microreactor geometry by using Taylor dispersion model and Computational Fluid Dynamics (CFD) simulation. The effectiveness of the proposed method is confirmed through a case study and test experiments. In addition to the control of RTD, the minimization of the molecular weight distribution (MWD) for continuous radical polymerization in a tubular microreactor is investigated. The model for the prediction of temperature and concentration in a non-thermal polymerization microreactor is developed. In the model, the polymerization mechanisms consisting of initiation, propagation, chain transfer, combination termination, and gel effect are considered. After modeling, the effect of design parameter, operating conditions (imperfect feed mixing etc.), transport and kinetic parameters, and solution parameters on the polymer properties is examined. The simulation results show that the inadequate reactor design and operation generate hot-spots that give rise to a condition called thermal runaway, which is characterized by an undesired product distribution.