From semi-batch to continuous tubular reactors: A kinetics-free approach

Abstract

A methodology, which does not require any kinetic information, for the rigorous transformation of an isothermal, homogeneous semi-batch process into an equivalent continuous side-fed tubular reactor was developed. Once the semi-batch process parameters are known, the proposed methodology allows for easily defining all the process parameters of a side-fed tubular reactor that guarantees the same performances as the original semi-batch process, in terms of conversion and product characteristics. Two different case studies were selected to investigate the potential of the proposed approach: a copolymer synthesis and the production of a fine chemical, clearly showing the need of a rigorous transformation of the semi-batch process into the continuous one since productivity and product quality are strongly affected by the feeding policy.

Solution Polymerization of Acrylic Acid Initiated by Redox Couple Na-PS/Na-MBS: Kinetic Model and Transition to Continuous Process

“…These quantities are reported in Figure 10 as a function of N d . Low values of N d will have higher deviations from the desired properties as these configurations are more similar to a batch reactor rather than a SBR [7]. It can be seen that for a high number of reactors in series (above 20 elements), the continuous system perfectly reproduces the SBR product both in terms of average molecular weight and polydispersity.…”

“…The recipe of tests SBR7 was chosen for the transition to a continuous process. The kinetics-free procedure for isothermal systems detailed in [7] was used to determine the process and geometrical parameters of the continuous series of PFRs at different number of reactors in the series, N d . The procedure allows to choose arbitrarily the total inlet mass flowrate and the cross-sectional area, which were set to 1.00 g s −1 and 20.3 cm 2 , respectively.…”

“…Then, the model for the continuous system is presented, with reference to tubular reactors. Finally, a kinetics-free procedure, which details can be found elsewhere [7,8], is applied to adapt the recipe already effective in SBR to a continuous production process based on a series of tubular reactors with intermediate feed streams.…”

“…For the first reactor in the series ṁprev i = ṁ0 i is the mass flowrate of species i fed at the entrance of the series of PFRs. The values of the inlet and intermediate feedrates, along with their composition, are computed through a kinetics free procedure according to the number of reactors in the series, N d , starting from a given SBR recipe [7,8]. All reactors in the series are assumed to have the same geometrical parameters (length and cross-sectional area).…”

“…This way, more severe conditions can be used with reduction of both reaction times and downstream utilities. Several methods were developed to shift polymerization processes from batch to continuous, by means of modular reactors (given a particular process) [5,6] or tubular reactors with distributed and localized side injections (for any homogeneous system regardless the chemical kinetics) [7,8].…”