Fuzzy Logic controller for glycerin bleaching temperature control

Controlling a process with significant lag is always a challenge task. The response is slow and can cause instability of the controller. In this work the Fuzzy Logic controller is purposed to control the heating stage for glycerin bleaching process. The Fuzzy PD and Fuzzy PI controllers are designed with different sets of membership function and rules. 3, 5 and 7 membership functions with 9, 25 and 49 rules are compared and evaluated to find the suitable set for this application. It was found that the implementation of Fuzzy Logic controller with 25 rules is sufficient to give good control for glycerin bleaching heating process.