Evaluation of ratio control schemes in a two-temperature control structure for a methyl acetate reactive distillation column

A two-temperature control structure for a methyl acetate reactive distillation (RD) column, originally proposed by [Roat, S.D., Downs, J.J., Vogel, E.F. and Doss, E.J., 1986, Integration of rigorous dynamic modeling and control system synthesis for distillation columns, in Chemical Process Control CPC III, Morari, M. and McAvoy, T.J. (eds.) (Elsevier, New York.)], is modified to incorporate ratio controllers in three different configurations between the column inputs. Closed loop results for these three configurations, namely, acetic acid feed in ratio with the methanol feed, methanol feed in ratio with the acetic acid feed and the two fresh feeds in ratio with the reboiler duty (through-put manipulator) show that the control performance for load disturbances does not improve and may deteriorate when the two fresh feeds are fed in ratio (acetic acid to methanol or methanol to acetic acid). The deterioration in performance is attributed to input multiplicity and unfavourable dynamic interaction between the control loops. Tighter product purity control is achieved for a through-put change when the two feeds are fed in ratio with the reboiler duty, the through-put manipulator. It is also shown that an alternative design that avoids input multiplicity exhibits better control performance. The results highlight the need for considering the non-linear effects in column and control system design for RD processes.

[1]  Manfred Morari,et al.  Predicting multiple steady states in distillation: Singularity analysis and reactive systems , 1997 .

[2]  William L. Luyben,et al.  Practical Distillation Control , 1992 .

[3]  Moses O. Tadé,et al.  Conversion inference for ETBE reactive distillation , 2000 .

[4]  N. Kaistha,et al.  Internal Heat Integration and Controllability of Double Feed Reactive Distillation Columns, 2. Effect of Catalyst Redistribution , 2008 .

[5]  Cheng-Ching Yu,et al.  Temperature Control of Heterogeneous Reactive Distillation , 2004 .

[6]  M. Morari,et al.  Chemical process control-CPC III : Elsevier, Amsterdam, 1986 (ISBN 0-444-99532-3). xi + 932 pp. Price $153.25/Dfl. 345.00. , 1987 .

[7]  Cheng-Ching Yu,et al.  Control of different reactive distillation configurations , 2006 .

[8]  P. Daoutidis,et al.  Modeling, Analysis and Control of Ethylene Glycol Reactive Distillation Column , 1999 .

[9]  Achim Kienle,et al.  Nonlinear control of a reactive distillation column , 2003 .

[10]  Cheng-Ching Yu,et al.  Design of reactive distillations for acetic acid esterification , 2005 .

[11]  K. Sundmacher,et al.  Reactive distillation : status and future directions , 2003 .

[12]  Robert S. Huss,et al.  Multiple steady states in reactive distillation: kinetic effects , 2002 .

[13]  Sigurd Skogestad,et al.  Optimal control and on-line operation of reactive batch distillation , 1994 .

[14]  A. Ciric,et al.  Steady State Multiplicities in an Ethylene Glycol Reactive Distillation Column , 1994 .

[15]  E. Gilles,et al.  Steady-state multiplicities in reactive distillation columns for the production of fuel ethers MTBE and TAME: theoretical analysis and experimental verification , 1999 .

[16]  Muhammad A. Al-Arfaj,et al.  Comparison of Alternative Control Structures for an Ideal Two-Product Reactive Distillation Column , 2000 .

[17]  B. R. Young,et al.  Modeling and Model Predictive Control of Composition and Conversion in an ETBE Reactive Distillation Column , 2005 .

[18]  Devrim B. Kaymak,et al.  Comparison of two types of two-temperature control structures for reactive distillation columns , 2005 .

[19]  Moses O. Tadé,et al.  Model gain scheduling control of an ethyl tert-butyl ether reactive distillation column , 2003 .

[20]  V. Agreda,et al.  High-purity methyl acetate via reactive distillation , 1990 .

[21]  Muhammad A. Al-Arfaj,et al.  Comparative control study of ideal and methyl acetate reactive distillation , 2002 .

[22]  V. Pinjala,et al.  Consider reactive distillation , 1992 .

[23]  Devrim B. Kaymak,et al.  Evaluation of a two-temperature control structure for a two-reactant/two-product type of reactive distillation column , 2006 .

[24]  Reactive distillation for synthesizing ethyl tert-butyl ether from low-grade alcohol catalyzed by potassium hydrogen sulfate , 1996 .

[25]  Rajamani Krishna,et al.  Multiple solutions in reactive distillation for methyl tert-butyl ether synthesis , 1993 .

[26]  Cheng-Ching Yu,et al.  Relay Feedback Tests for Highly Nonlinear Processes: Reactive Distillation , 2006 .

[27]  Charles F. Moore.  Selection of Controlled and Manipulated Variables , 1992 .

[28]  N. Kaistha,et al.  Temperature Based Inferential Control of a Methyl Acetate Reactive Distillation Column , 2007 .

[29]  Moses O. Tadé,et al.  MULTIPLICITY AND PSEUDO-MULTIPLICITY IN MTBE AND ETBE REACTIVE DISTILLATION , 1998 .

[30]  Moses O. Tadé,et al.  Pattern-based predictive control for ETBE reactive distillation , 2003 .

[31]  Moses O. Tadé,et al.  A Multi-Objective Control Scheme for an ETBE Reactive Distillation Column , 2000 .

[32]  Moses O. Tadé,et al.  Two-point control of a reactive distillation column for composition and conversion , 1999 .

[33]  N. Kaistha,et al.  Steady State Analysis of Reactive Distillation Using Homotopy Continuation , 2005 .