EXPERIMENTS WITH A STIRRED TANK HEATER

Comparing the controller parameters in Thble 7.4, the IMC-PID design rules produce both a larger proportional gain and a larger integral time constant as compared to the new rules. However, it is primarily the smaller integral time constant associated with the new rules that produces the fast disturbance rejection. 

Simple first order plus delay models for this process were derived firom step response tests. For controlling the temperature of the outlet water stream, the manipulated input variable is the steam valve position and the process output variable is the outlet water temperature, measured at one of three thermocouples located at different distances from the tank outlet. The tests involved introducing a step change in steam valve position, with the temperature controller in manual, and observing the response in the outlet water temperature at each of the three thermocouples. Simple graphical methods were used to calculate the parameters of the first order plus delay models. 

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