The proposed scheme includes two discrete-time PID controllers with integral anti-windup and a Smith predictor to provide the required regulation, while the minimisation problem is analytically solved online, by estimating the unmeasured disturbances present in the process and solving the associated linear program. This, as well as the presence of constraints in the process manipulated variables results in a complex, nonlinear closed-loop system and hence, the manual tuning of the two PID controllers according to some given performance objectives, becomes a difficult task. GAs are successfully applied to the automatic tuning of the PID controllers, and simulation results are presented to demonstrate the effectiveness of the proposed control scheme.