Indian Journal of Fibre & Textile Research Vol. 29. June 2004. pp. 233-238 Techno-economic control systems for polyester manufacturing A A Itagi'. Mandar Shete. Kapil Asher & Nitin Kanade D.K.T.E Society's Textile and Engineering Institute. Ichalkaranji 416 liS . India Received 2 July 2002; revised received 28 November 2002; accepted 24 February 2003 A new approach for process control in polyester manufacturing plants is prese nt ed. which is based on the di stributed control system and simulation. enabling a high degree of automation. The technology see ms to be stable process with operational ease providing protection against misguidance and wastage. Although a hi gh initial investment is called for nonetheless high investments can be recovered in just three years of installing this technologically superior a nd economically viable control system. Keywords: Distributed control system. Polyester. Progra mm able logic controller IPC Code: Int. CI. 7 G06F 9/00 1 Introduction Through the decades, the process system for polyester manufacturing control architecture has witnessed technology advances. In the industrial sectors, it has moved from pneumatic controls (some still around) to electronics (vacuum tubes) to transistors to integrated circuits. Direct digital controls (DOC) led to distributed control system (DCS). Automation has undergone a paradigm shift with innovations in electronics and control to achieve its current form where complex processes take place merely with a push of a button or even click of a mouse. The new age smart instruments, name ly digital communications, sophisticated control systems and the concept of completely integrated factory, are all set to change manufacturing forever. With robotic- controlled plants, networking with TCP/IP, optic fibre and satellite communication, the automation indeed has come a long way. Today, sitting in the comforts of the room or even while globetrotting, a CEO can visualize and control operations and manufacturing process on the plant floor. Polyester manufacturing is a very sensitive and delicate process which requires a high degree of engineering knowledge and excellent equipment and more so precise equipment control to guarantee desired quality. Although the textile is under a sustained recession, the technology solutions are available to the manufacturer to reduce manufacturing "To whom all the correspondence should be addressed. Phone: 2425114; Fax:+91-230-2423329; E-mail: aaitagi@hotmail.com costs by better machine control. The process control in polyester manufacturing needs multi-attention as there are many a parameters to take stock of, necessitating a limited degree of automation and, in the present work, this is precisely the reason to undertake a training and study project to validate the new approach which is based on the di stributed control system (DCS) for process control in polyester manufacturing right at the place of its usage (industry). Study has been carried out at Indorama Synthetics [India] Ltd and Sanghi Polyester Ltd, to observe the technical and economical feasibility of DCS technique in polyester manufacturing pl ants. 2 Digital Control Mechanism Digital systems are any computerized systems or microprocessor-based devices used for the control or data acquisition. 2.1 Distributed Control System The distributed control system is a comprehensive hardware and software package that encompasses all the functionality required to implement control and data acquisition functions. This includes operator graphic interface (VDUs), alarm package, historical data collection package, continuous and discontinuous control, and standard hardware communication capability to the other digital systems. This system along with programmable logic controller (PLC) and supervisory control and data acquisition system (SCADA) offer wide ranging applications for control and data acquisition. A typical DCS system is shown in Fig. I