Simulation of three-stage nylon 6 reactors with intermediate mass transfer at finite rates

A three-stage isothermal nylon 6 reactor with a kinetic scheme incorporating ring opening, polycondensation, polyaddition, cyclic dimer formation, and reaction with monofunctional acids has been modeled. In the first and third stages, removal of the condensation by-product, water, is prevented. The second stage of this sequence, however, involves finite rates of diffusion of water to cocurrently flowing inert gas bubbles. the number-average chain length of the polymer obtained in this reactor differs substantially from that obtained assuming instantaneous water removal and is a function of the various design variables. It is observed that several choices of these design variables can be made to obtain the same product, thus emphasizing the need for more comprehensive optimization studies than hitherto carried out.