Nonlinear pH control

A simple new method for designing nonlinear IMC controlles for SISO systems has been developed. The method has been applied to the neutralization of a simulated strong acid-strong base system. The objective of the control effort in this instance is to maintain the effluent pH at 7.00 in the presence of disturbances. An examination of the results shows that the controller provides perfect set point compensation and excellent disturbance rejection. The results also show that to implement this type of controller for pH control a fast CPU with extended precision capabilities and a fast analog-to-digital converter would be required.