Modeling of solid‐state polycondensation. II. Reactor design issues

Abstract

ABSTRACT:The relative merits of the moving packed bed, fluidized bed, and stirred bed reactors for solid-state polycondensation are discussed along with methods for improving these designs. A general model to describe continuous solid-state polymerization reactors is then developed and illustrated by a case study of a moving packed bed reactor showing the relative importance of operating variables. The model also predicts the dynamic behavior in response to several process inputs.

Solid State Polymerization of Poly(Ethylene Furanoate) and Its Nanocomposites with SiO2and TiO2

“…The problem is complicated since besides chemical kinetics, describing the rate of change of the concentration of the species as a function of time, diffusion phenomena should be incorporated that result in additional variation with the distance from the interface. Having two independent variables, partial differential equations must be set and solved including a number of kinetic, diffusional, and crystallization parameters . Furthermore, the results of these models were used to fit only a few experimental data points.…”

Simulation of continuous solid‐phase polymerization of nylon 6,6. III. Simplified model

“…In these processes, polymer particles with moderate molecular weight are heated to a temperature between their glass transition temperature and melting temperature and polymerized to higher molecular weights. [1][2][3][4][5][6][7][8][9] In our previous work, 10,11 a reactor model was developed to describe the dynamics of a continuous SPP process for nylon 6,6 in a moving bed reactor. Temperature, moisture-content, and particle-property profiles over the height of the bed and within the polymer particles were determined at different reaction times under various operating conditions.…”

Solid‐State Polymerization of Poly(ethylene terephthalate): The Effect of Water Vapor in the Carrier Gas

“…Most published studies regard the modeling and analysis of the diffusion phenomena inside the polymer particles, [7][8][9][10][11][12][13][14][15][16][17][18][19][20] neglecting mass transfer limitations on the particles surface, which can be associated to the properties of the gas phase. [21][22][23] Despite that, although particle models are fundamental to provide understanding about how reaction kinetics interacts with transfer phenomena, external mass transfer resistance can exert enormous influence on the solutions obtained with the help of diffusion-reaction models. [24] However, most published PET models assume that external mass transfer resistance is negligible, which is equivalent to assuming that the velocity of the carrier gas is sufficiently large and that the volatiles concentrations in the gas phase are null.…”

“…As already mentioned, the large majority of available PET particle models neglect the existence of mass transfer resistance on the particles surface; however, even when this mass transfer resistance is considered, constitutive equations derived from other particulate systems are used for prediction of mass transfer coefficients without any independent experimental validation. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Model fitting is usually attained through re-estimation of diffusion coefficients within the polymer matrix, using experimental data obtained from sorption experiments as initial guesses. [25][26][27][28] In summary, it seems clear that the main focus of the PET SSP literature regarding mass transfer phenomena has been the polymer-side diffusion mechanism, which does not necessarily describe continuous industrial PET processes appropriately.…”