The simulation of hydrolytic polymerization of ϵ‐caprolactam in various reactors

Abstract

SynopsisThe concrete simulation models dealiig with the kinetic behavior of the hydrolytic polymerization of e-caprolactam (CL) in various polymerization reactors used in the industry were described, and the method for their numerical solutions was presented. The characteristic data of the polymerization such as the concentrations of CL, end group, water, c-aminocaproic acid, cyclic dimer, and the hot-water-soluble component, conversion, number average, and weight average molecular weights, and solution and melt viscosities can be calculated at every stage of the polymerization reaction, at every part of the reactors, and/or at the outlet of the reactors. The calculated values based upon the models were found to be quite compatible with the observed values for the reactors. The applicability of the technique was well confirmed for the quality control, process control, modification of existing plants, and development of new chemical process plants.

Simulation of an industrial nylon 6 tubular reactor

“…Unfortunately, there is considerable uncertainty in the values of the viscosity of the reaction mass. The value of about 40 P at the end of typical industrial reactors, as reported by M a~h e l k a r ,~~ differs significantly from that of about 550 P obtained using the correlations of T a i et al 13 under similar conditions. Such discrepancies in estimates of viscoSity, particularly at high conversions, are not limited to nylon 6 systems and are common in other systems, too.…”

Simulation of Nylon 6 Polymerization in an Industrial Two‐Step VK Tubular Reactor

“…Sitting1 has summarized the evolution of various reactors ranging from batch reactors operating under high pressure (to avoid vaporization) to cascades of stirred tank reactors in combination with tubular reactors. In the last several decades, a considerable amount of research has been reported on the simulation and optimization of nylon 6 reactors 2–16. And meanwhile, most of earlier functional studies focused attention on isothermal reactors without vaporization of water and other low‐molecular‐weight compounds and have helped spawn the values of rate and equilibrium constants for various main and side reactions associated with the hydrolytic polymerization.…”

“…And meanwhile, most of earlier functional studies focused attention on isothermal reactors without vaporization of water and other low‐molecular‐weight compounds and have helped spawn the values of rate and equilibrium constants for various main and side reactions associated with the hydrolytic polymerization. To name a few, Tai and co‐workers15–19 have supplied the best‐established thermodynamics and kinetic constants and studied some commonly used industrial reactors. Gupta et al10–14 have simulated several kinds of single tubular reactors, on the basis of a comprehensive chemistry scheme.…”

“…The kinetic scheme of Table 1 does not include the amide interchange reactions,21 which does not modify molecular weight but incites polydispersity index (PDI) to its equilibrium value more rapidly. The rate and equilibrium constants used in this work were given by Tai et al15–19 (see Table 1). Taking into consideration the moments equations given in previous works of S. K. Gupta et al22 and adding those regarding bifunctional chain‐endings studied by Tang et al,7,23 a complex mathematical model has been built up.…”

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

“…They used their data to simulate various commonly used industrial reactors. 18 Gupta et al19-21 obtained the entire molecular weight distribution (MWD) for various isothermal polymerizations by solving the mass balance equations numerically. They used two kinetic models for the formation of macrocyclic compounds based on the work of Jacobson and Stockmayer22 and Andrews et al 23 and studied their effect on the MWDs.…”