• Economics: Target of any meaningful business is to maximize its profit. In order to achieve that, one needs to minimize the production cost, losses, wastage, energy requirement and human labour. A good control system should ensure an optimum level of performance that maximizes the profit conforming to all safety & environmental regulations, product specifications and operational constraints.

All these criteria listed above demand the need for continuous monitoring of the process operation as well as external intervention (control) to guarantee satisfactory performance. This is accomplished through rational arrangement of paraphernalia (sensors, transducers, controllers, actuators, alarms, computers) and personnel (engineers and operators), which together constitute the control system.

I.2   Conceptual Block Diagram of a Control System

A conceptual block diagram of a controlled chemical process is shown in Fig. I.1.

Fig; 1.1