Fuzzy TBT control of multi-stage flash desalination plants

摘要

The paper describes the application of fuzzy algorithms to thecontrol of top brine temperature (TBT) of multi-stage flash (MSF)seawater desalination plants. A linearized model of a six inputs and sixoutputs 18-stage MSF plant is considered in this study. The transferfunction matrix of this model is subjected to interaction between theloops. The design of fuzzy logic controller (FLC) for one of theimportant loops, namely the TBT loop is considered in detail. A set offuzzy rules that make the controller look like aproportional-plus-derivative controller (PD-like FLC) is obtained andapplied to a first order plus dead time approximation of the plantmodel. In order to improve the performance, an integration effect isadded to the output of the PD-like FLC to produce PID-like FLC. A tunedversion of the latter controller has been applied to the full plantmodel in its nonparametric form. The fuzzy controller was found to givegood results compared to those obtained from the existing conventionalcontrollers