JOURNAL OF POLYMER ENGINEERING

VOLUME 20:1, PAGE 51, 2000, ABSTRACT

OPTIMIZATION OF THE FIRST STAGE CONTINUOUS REACTOR-SEQUENCE IN POLYESTER MANUFACTURE FROM PURIFIED TEREPHTHALIC ACID

 Charles D. Immanuel and Santosh K Gupta

 Department of Chemical Engineering, Indian Institute of Technology, Kanpur, 208016, India, and Department of Chemical and Environmental Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore, 119260

 ABSTRACT

 A simplified model has been used for the first stage of polyester manufacture from purified terephthalic acid (PTA) and ethylene glycol (EG). This consists of a sequence of three continuous-flow stirred tank reactors (CSTRs) in series, with a recycle stream from the last reactor to the first one. The model gives the conversion of PTA and EG, the number-average molecular weight (Mn), and the concentrations of several undesired compounds (diethylene glycol, acetaldehyde, water and acid end groups) in the product under different operating conditions. A preliminary optimization study (under steady state operation) indicates the best values to be used for some of the 'decision variables', e.g., the feed ratio (R[) of EG to TPA, recycle ratio (RR), temperature (T|, i = 1, 2, 3) of the three reactors and their residence times (t;, i = 1, 2, 3). Near-optimal conditions have been found for R, = 1.5, RR = 0.05. Ti = 215@C, T; = 220@C, Ty = 225@C, with the individual values of the residence times (for a specified total residence time of three hours) being relatively unimportant. Such exploratory optimization studies, using judgment or intuition to study the several performance indices or objectives, are necessary to develop insights for complex industrial 2000   Optimization of the First Stage Continuous Reactor-Sequence in Polyester Manufacture from Purified Terephthalic Acid systems and are required for formulating meaningful optimization problems involving multiple objective functions and constraints.

 'To whom correspondence is to be addressed. On leave from I.I.T., Kanpur, to NUS Singapore. E-mail: cheskg@nus.edu.sg

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