Synthesis of Two-Point Linear Controllers for Binary Distillation Columns

Two-Point Composition−Temperature Control of Binary Distillation Columns

“…Summarizing, the functioning of the proposed CT control design methodology has been tested with three different case examples, in the presence of measurement, actuator, and (holdup dynamics, nonideal thermodynamics) modeling, as well as (feed rate, composition, temperature, and enthalpy) load disturbances. With a more systematic and simpler design, the proposed control approach yields a behavior that equals or outperforms those obtained with previous nonlinear 10 2I−4O cascade controllers, as well as linear dual composition, two-point temperature, and linear 8,9 cascade schemes.…”

“…The representation of matrixes A c and A T in product form (eq 5) displays a fundamental structural property of the 2I-4O control structure: A c and A T are linearly dependent. In our previous separate 2I-2O DC 3 and TPT 18 designs, the product representation was not needed, because the C-T structural interconnection was not an issue.…”

“…Summarizing, there are only two candidate CT control structures: (i) a decentralized C component (eq 13a) with a decentralized (with P ) D 1 in eq 7) T component (eq 13b), and (ii) a decentralized C component (eq 13a) with a one-way decoupling (with P ) O 12 in eq 7) T component (eqs 13b and 13c). In other words, the combined component design approach has considerably reduced the 49-structure search problem that must be tackled when the direct combination of previous separate DC 3 and TPT 18 control designs approach is pursued.…”

“…The production of many intermediate and final products in the chemical and petrochemical industries is heavily dependent on energy-intensive distillation columns, and their efficient (minimum energy consumption) operation requires the regulation of distillate and bottoms compositions . The related dual composition (DC) control problem has been studied extensively with linear , and nonlinear control schemes . In high-purity columns with poor input-to-composition output sensitivity and measurement dead times, these control schemes may exhibit sluggish responses, because the control actions occur after the entire composition profile has been upset by disturbances.…”

Output-Feedback Dissipative Control of Exothermic Continuous Reactors

“…Advanced nonlinear control studies have been performed in the chemical process systems engineering field, the related state of the art can be seen elsewhere, and here it suffices to mention that: (i) with a few exceptions (Alvarez et al [1991], Viel and Jadot [1997], Antonelli and Astolfi [2003]) most of the studies lack rigorous stability and performance assessments, and (ii) only the optimality-based MPC (which stems from industrial control developments) has reached the stage of acceptance for plant scale testing or implementation (Eaton and Rawlings [1990]). Recently, in the context of polymer reactor (Gonzalez and Alvarez [2005], Diaz-Salgado et al [2007]) and distillation column outputfeedback control studies (Castellanos-Sahagun and Alvarez [2006]) with constructive nonlinear control, connections between PI, inventory and MP control designs have been identified, and the closed-loop stability assessment and tuning aspects have been handled either with conceptual arguments or with the small gain theorem. The dissipativity notion offers a unifying framework to handle design-oriented tools in constructive control (Sepulchre et al [1997]) according to fundamental connections between optimality, passivity, robustness and dissipativity, with emphasis on interlaced observer-control designs and rigorous stability assessments.…”