Strong Acid Equivalent Control of pH Processes: An Experimental Study

The control of pH is widely recognized as a difficult problem. The Strong Acid Equivalent approach for control of pH processes consists of defining an alternate equivalent control objetive, the Strong Acid Equivalent, which is linear in the states and using a linear control law in terms of this new control objective. The Strong Acid Equivalent is then calculated on line from pH measurements given a nominal titration curve of the inlet stream. A laboratory system has been built to implement this method. Experimental results for the hydrochloric acid / sodium hydroxide and acetic acid / sodium hydroxide systems are given. The results show the control which can be achieved with the Strong Acid Equivalent method.