Internal Heat Integration and Controllability of Double Feed Reactive Distillation Columns, 1. Effect of Feed Tray Location

Abstract

The impact of altering feed tray locations (for the purpose of saving energy) on the controllability of double feed reactive distillation (RD) columns is evaluated for two case studies: a hypothetical ideal RD column and a methyl acetate RD column. Energy savings of 18.3% and 36.4% over the conventional design (feed immediately above and below the reactive zone) is achieved for the ideal and methyl acetate systems, respectively. A steady-state bifurcation analysis shows that, for both systems, output multiplicity, with respect to reboiler duty, occurs at a fixed reflux rate for the different designs (conventional/altered feed tray location). The output multiplicity is eliminated at a fixed reflux ratio. Closed-loop dynamic simulation results show that the controllability of the internally heat integrated ideal RD column deteriorates, compared to the conventional design. Unlike the conventional design, temperature-based inferential control is infeasible and compositionbased control structures must be used. For the methyl acetate column, on the other hand, heat integration by altering the feed locations entails no loss in controllability using two-point temperature inferential control.

Control of Quaternary Ideal Endothermic Reactive Distillation with and without Internal Heat Integration

“…Even as the energy consumption is reduced via heat integration, the controllability of the column must be ensured at the conceptual design stage, since RD columns are highly nonlinear [17,23]. The literature reports are conflicting with some claiming improved controllability with internal heat integration [34,35,51,52] and still others demonstrating the opposite [46,47]. Therefore, one has to seek an internally heat-integrated design for the ideal endothermic RD system for better energy efficiency and systematically compare its controllability with the basic design.…”

“…The design of efficient and easily implementable control structures for such energy-efficient distillation systems is significant for the effective realization of heat energy savings [44]. However, very few articles explored temperature inferential control of such processes [35,37,38,[45][46][47]. In this contribution, temperature-based inferential control with cascaded distillate and bottoms product purity control is evaluated for the basic and internally heat-integrated RD column designs for the generic, ideal, endothermic, twofeed, two-product RD system.…”

Control of Reactive Distillation Column: A Review

“…Kumar and Kaistha published a series of articles on RD control (Singh et al 2007;Kumar & Kaistha 2008d;2008a;2008e;2008b;2008c;. Kumar and Kaistha published a series of articles on RD control (Singh et al 2007;Kumar & Kaistha 2008d;2008a;2008e;2008b;2008c;.…”

A review: control of reactive divided wall distillation column

“…Kumar and Kaistha studied the effect of internal heat integration by catalyst redistribution on the controllability of an ideal and a methyl acetate reactive distillation (RD) column [27].They also evaluated the two-temperature control structure for a methyl acetate reactive distillation (RD) column on the basis of ratio control scheme [28]. Volker et al [29] studied the heterogeneously catalyzed esterification of methanol and acetic acid to methyl acetate in a semi batch process in a reactive distillation column.…”