The role of rule based control in the process industry

The author believes that industry is now entering a new era where on can realistically consider ways of not only achieving good product quality but can now coincidentally aim to optimise the process with respect operating parameters and procedures of the unit. The author considers how rule based control emerged out of the need to find a solution to controlling and optimising those processes that were known to be complex and difficult to model and yet not particularly demanding on the process operators. The techniques are now well established and the benefits arising out of its application have been shown to be much greater than originally targeted giving audited paybacks as short as three months. This is probably due to the formal combination of the pragmatic approach to control of the process operators with that of the technical experts in the form of process engineering and central technical personnel. The potential range of applications for rule based control is probably unlimited since in its simplest from it can be made to mimic conventional PID control and yet can be very easily extended to successfully handle a wide range of special or unique conditions