Process control systems serve two different purposes. Generally the first of these purposes is to effect a change in a certain output variable, commonly encountered in the startup of a process. The second of these is to regulate or hold an output variable constant despite any changes in an input variable, which usually cannot be easily managed [1]. In order to discuss process control, in detail it is necessary to define several terms. A control loop …showed first 75 words of 1924 total…

…showed last 75 words of 1924 total…Chemical Process Control: An Introduction to Theory and Practice, Prentice Hall, Englewood Cliffs, NJ, 1984. 4) Seborg, Dale E.; Edgar, Thomas F.; Mellichamp, Duncan A. Process Dynamics and Control, John Wiley and Sons, Inc. New York, NY, 1989. 5) Smith, Carlos A.; Corripio, Armando B. Principles and Practice of Automatic Process Control, John Wiley and Sons, New York, NY, 1985. 6) Perry, Robert H.; Green, Don W.; Maloney, James O.; Perry’s Chemical Engineers’ Handbook, 7th ed, McGraw-Hill, New York, NY, 1997.