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Expert system for control of anaerobic digesters
Author(s) -
Pullammanappallil P. C.,
Svoronos S. A.,
Chynoweth D. P.,
Lyberatos G.
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980405)58:1<13::aid-bit2>3.0.co;2-x
Subject(s) - dilution , control theory (sociology) , process (computing) , anaerobic exercise , constant (computer programming) , control system , computer science , process control , set (abstract data type) , sign (mathematics) , control (management) , mathematics , engineering , biology , thermodynamics , artificial intelligence , physics , mathematical analysis , programming language , operating system , physiology , electrical engineering
Continuous anaerobic digesters are systems that present challenging control problems including the possibility that an unmeasured disturbance can change the sign of the steady‐state process gain. An expert system is developed that recognizes changes in the sign of process gain and implements appropriate control laws. The sole on‐line measured variable is the methane production rate, and the manipulated input is the dilution rate. The expert system changes the dilution rate according to one of four possible strategies: a constrained conventional set‐point control law, a constant yield control law (CYCL) that is nearly optimal for the most common cause of change in the sign of the process gain, batch operation, or constant dilution rate. The algorithm uses a t test for determining when to switch to the CYCL and returns to the conventional set‐point control law with bumpless transfer. The expert system has proved successful in several experimental tests: severe overload; mild, moderate, and severe underload; and addition of phenol in low and high levels. Phenol is an inhibitor that in high concentrations changes the sign of the process gain. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:13–22, 1998.