TOWARDS IMPROVED AUTOMATION FOR DESALINATION PROCESSES .1. ADVANCED CONTROL

The desalination process industries have largely tried to solve contro l problems by conventional rather than modern control techniques that are attracting widespread industrial applications and revolutionizing process control as a result of advances in control theory. Control sys tems are designed from mathematical models that are generally imperfec t descriptions of real processes. It is widely accepted that conventio nal PID or PI controllers may not provide satisfactory performance in view of nonlinearity and uncertainty in the real world of desalination processes. It is essential that control systems operate satisfactoril y over a wide range of process conditions. The practice of multi stage flash (MSF) desalination process control, process design, optimizatio n, conspicuously lags behind contemporary theoretical developments. Co nventional process control techniques do not ensure the safest and the most profitable operation of processes when compared with advanced pr ocess control which uses the knowledge of process economics and provid es insight into the process to maintain essential variables at optimum setpoints. This paper is an attempt to promote excellence and innovat ion in desalination engineering and to remove barriers to advanced pro cess control. Attempted here is brief clarification of some aspects of advanced control strategies in terms of answers to the questions: Adv ance control strategies: What are they? Where and when are they applic able? and What can be expected of them? Although the reference here is to MSF plants, some of the observations and remarks are also relevant to process control practice in general. In the end, the conclusions p oint out the complexity of the real world control problem which behove s us to advocate the application of techniques such as self-optimizing control strategies and artificial intelligence (AI) leading to an int egrated system of intelligent control.