A Control system design approach for continuous mixer and extruder

Abstract

A holistic design and development approach is proposed for process machine Control System of a Continuous Mixer and Extruder (CME). In this approach five frameworks are discussed to improve and standardize development cycle and machine life cycle.

Unlike traditional batch mixers, continuous mixer provides an economical alternation for big capacity mixing processes. CMTI has designed and developed a CME for a chemical processing research laboratory. The CME developed by CMTI is a fully automated system with all control operations automated for all process automation i.e., from silo to bin.

A top-down design approach is followed for control systems design. As recommended by ISA-88 norm, abstraction of equipment units allowed compartmentalization of operations. Further, abstraction enabled mapping operational requirements across life cycle from development to maintenance. The design is carried out considering all possible operations required throughout machine life cycle. This approach allowed for accelerated development, isolated unit testing, seamless integration and system testing.

A holistic approach in design and development of control system enables machine to be operated at variety of phases of development life cycle and machine life cycle. This is achieved with five major frameworks incorporated into the system.

The control system designed and developed consists both hardware and software. Software is developed into multiple Programmable Logic Controllers (PLCs). A network of multiple PLC systems and a central PLC that coordinates all control operations. This architecture forms a Distributed control system (DCS).