Print ISSN: 1681-6900

Online ISSN: 2412-0758

Author : A. Mohsin, Hayder

Modeling and Control of pH Process for Weak Acid-Weak Base System

Karima M. Butrus; Hayder A. Mohsin; Ali R. Mohammad Jawad

Engineering and Technology Journal, 2012, Volume 30, Issue 1, Pages 51-66

This paper studies the model and control of pH neutralization process of waste water
system using different control schemes. An experimental investigation was conducted for
the dynamic behavior of neutralization process of waste water in a continuous stirred tank
reactor (CSTR).
A dynamic model for pH neutralization process in a continuous stirred tank reactor
(CSTR) is described by a first order plus dead time (FOPDT).
The pH value is calculated by solving the charge balance of the mixture. Good agreement
is obtained between the simulated and experimental responses. However, a small
differences between the responses due to the error in the measurements.
The conventional feedback control was studies in this work and the controller
parameters was tuned by Ziegler-Nichols reaction curve method to find the best values of
proportional gain (Kc), integral time (t I) and derivative time (t D). Artificial Neural
Network Model Predictive Control (ANN MPC) was used as another strategy to compare
with above strategy.
The ANN controller was compared with conventional controller and it was found that
ANN controller provides better control for the set point changes with low settling time
and lower overshoot. Whereas the conventional controller provides sluggish behavior in
set point change. Also it was found that the ANN controller provides better response to
regulated change than the conventional controllers where the PI and PID controllers
provide sluggish disturbance responses because the approximate FOPTD model has
relatively small time delay. As non-linear process the conventional feedback controller
was unable to control this system adequately.