This paper presents the extension of the hardware-software experimental system SENFpHCTRL initially developed for wastewater pH control, for monitoring other parameters (total suspended solids, extractable, biochemical and chemical oxygen demand, phenols and chlorides) from other chemical processes of a treatment plant, such as: precipitation, coagulation and flocculation, oxidation and reduction (processes briefly presented at the begining of the paper). The process of expanding the SENFpHCTRL system involved the adding to the initial expert system of a set of heuristic knowledge for other parameters and the development of the system graphical interface. It is also presented the adapted form of the system hardware component at PC and microcontroller level and the results of the simulations made with the extended system.

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The opportunity analysis of using two Proportional-Integral (PI) controllers, tuned with Skogestad�s variant of Simple Internal Model Control based (SIMC) method, for controlling the top and bottom compositions of a propylene/propane distillation column represents the paper aim. The SIMC method for PID controllers is the simplest and extremely good model in tuning procedures. Because the distillation process is nonlinear, the process model is described by a reunion of different linear models, for the different process operating ranges and, for each operating range, different sets of controllers� tuning parameters are computed using SIMC tuning method. In order to validate the experimental results a comparison is made with the case when the PI controllers are tuned using Ziegler-Nichols (ZN) method that uses the step response and process approximation exactly as Skogestad�s variant of SIMC.

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