Robust QFT-based TBT control of MSF desalination plants

Scarcity of water resources along with population increase, industrializati on, and agricultural expansion in many regions of the world mandates the us e of modern technology to supply the increasing demands for potable water. Due to the complexity and large-scale nature of MSF plants, improving their reliability of operation under continuous and heavy loads while maintainin g their efficiency compared to other well known processes has not been stud ied thoroughly. However, there have been some simple preliminary efforts ba sed on limited static simulation and classical dynamic performance cases. R ecently, some rigorous control and automation applications of MSF plants ha ve been treated in the literature which showed some promising results in th e cultivation of modern control techniques to the problem. In this work the recently developed robust quantitative feedback theory (QFT) control techn ique is introduced and applied to the design of robust controllers for the top brine heater temperature (TBT) loop of large MSF plants. This paper foc uses on the design of robust linear controllers for the regulation of TBT o f large MSF desalination plants using the QFT approach. The particular Ii-s tage linearized model at the Abu-Dhabi Um-Annar plant was used as a test sy stem. The robust controller obtained has considerable advantages over conve ntional PID controllers in that it can handle plant parametric uncertaintie s due to disturbances or modeling errors.