Akademik Veri Yönetim Sistemi
2005 AIChE Spring National Meeting, Atlanta, GA, Amerika Birleşik Devletleri, 10 - 14 Nisan 2005, ss.3201
A typical waste-water effluent of a chemical process can contain several strong acids, weak acid as well as their salts. Thus, they must be neutralized before being discharged to the environment in order to protect aquatic life and human welfare. However, such processes are highly nonlinear and have time-varying characteristics. Therefore, the control of pH is a challenging problem where advanced control strategies are often considered. In this study, the aim is to design a pH control system that will be capable of controlling the pH-value of a plant waste-water effluent stream having unknown acids with unknown concentrations using a new on-line identification procedure. A model predictive controller, MPC and a Fuzzy Logic Controller (FLC) are proposed and applied to a laboratory scale pH neutralization system. The characteristics of the upstream flow is obtained by a small identification reactor which has ten times faster dynamics and which is working parallel to actual neutralization tank. In the control strategy, steady-state titration curve of the process stream is obtained using the data collected in terms of pH value from the response of the identification reactor to a step input in base flow rate and using the simulated response of the identification reactor for the same input. After obtaining the steady-state titration curve, it is used in the design of an adaptive model predictive controller (AMPC). In the FLC identification reactor is not used. The performance of the proposed controllers are tested mainly for disturbance rejection, set point tracking and robustness issues theoretically. The performance pf the MPC and FLC are compared with a conventional PI controller experimentally for disturbance rejection, set point tracking and the superiority of the FLC is verified.