Modeling of industrial nylon-6,6 polycondensation process in a twin-screw extruder reactor. I. phenomenological model and parameter adjusting

Abstract

This article describes a mathematical model for the finishing stage of nylon-6,6 polycondensation in a twin-screw extruder reactor. In the model, the extruder is conceptually divided into two regions. The first one is the partially filled degassing zone, which is operated under low pressure and where the evaporation of water from the polymer takes place. The rate of evaporation is considered to depend on an overall mass transfer coefficient and is limited by the water-polymer physical equilibrium. In the second region, which is fully filled, the polymer flow is assumed to be plug-flow and, in this region, the reversible polycondensation reaction occurs, as well as degradation reactions. A comparison with experimental data obtained in an industrial plant shows fairly good agreement with model predictions after optimal fitting of the rate coefficients.

Modeling of industrial nylon-6,6 polymerization process in a twin-screw extruder reactor. II. Neural networks and hybrid models

“…The steady-state phenomenological model (Giudici et al 1 ) using the plug flow assumption proved to be robust for predicting the CA and CC values for the nylon 6,6 processes compared with the experimental data. However, the prediction of RV by an empirical polynomial equation as a function of M n gave values lower than the expected industrial data (mainly at low values of RV).…”

“…One way to quantify the degradation is to compare the CA variation with the CC variation along the extruder. Giudici et al 1 presented the ratio of differences of the input and output values of CA and CC. If no degradation occurs, the ratio should be 1.…”

“…Two sets of experiments were used to feed the neural network. One consists of the 21 planned experiments made in the industrial plant, dis-cussed in Giudici et al 1 An additional 44 planned experiments were run in a pilot screw extruder reactor. The main reason for using the data from the pilot plant was that the values of CA and CC can be changed at the extruder entrance.…”

“…Although the phenomenological modeling of the nylon-6,6 extruder process gives a reasonable prediction from the industrial point of view (Giudici et al 1 ), the nature of the process presents some difficulties, such as the complex nature of the flow in the extruder, the condensate removal (mass transfer limitations), and the kinetics of polycondensation and degradation reactions. The lack of internal or intermediate measurements along the industrial extruder reactor represents a limitation for a detailed model validation.…”

Simulation Model of Polyamide-6,6 Polymerization in a Continuous Two-Phase Flow Coiled Tubular Reactor

“…Previous works on nylon-6,6 polymerization reactor modeling have been focused on different reactor types: batch autoclaves, 14,15 different prepolymerization reactors, 16 CSTRs, 17 thin or wiped film reactors, 18,19 vented twin-screw extruder reactors, [20][21][22] and flasher tubes. 1 In the present work, a mathematical model for polyamide-6,6 polycondensation in a two-phase flow continuous tubular reactor (flasher tube) followed by a continuous stirred tank reactor under catalyzed and uncatalyzed conditions is presented and validated using industrial data.…”