Development of an automatic control system for monitoring an anaerobic fluidized-bed

Abstract

The start-up procedure of a laboratory fluidized-bed was monitored by an automatic control system. Twenty six days were necessary to increase the load from 1 to 35 kg COD/m3.d. The system took into account the pH of the liquid phase, the production of gas, and the concentration of hydrogen in the gas phase. These parameters were measured by on-line sensors. According to variations of these parameters, algorithm based on a principle very close to an expert system adjusted the flow-rate of the feeding pump. The automatic control system was tested in the following situations: perturbations in the process generated by large pH variations (± 0.2 to 0.7 pH unit) and organic overloads (from 50 to 100 kg COD/m3.d). After 44 hours of overloading, CH4 and CO2 concentrations in the gas phase were very useful to detect the deviation of the reactor.

Monitoring and control of an anaerobic upflow fixed‐bed reactor for high‐loading‐rate operation and rejection of disturbances

“…The system used only one process variable, methane production rate, to manipulate the dilution rate. Ehlinger et al (1994) and Moletta et al (1994) developed automatic systems based on the expert system principle to control laboratory-and pilotscale fluidized-bed reactors. The control algorithms used the information of pH, gas production rate, and its hydrogen content to calculate the variation in feed rate.…”

Critical analysis of engineering aspects of shaken flask bioreactors

“…Gas production (CH 4 and CO 2 ) is the earliest and most commonly used parameter for monitoring and control of the anaerobic process, and the use of gas flow as an online measured parameter in control systems is widespread (Renard et al, 1988(Renard et al, , 1991Boscolo et al, 1993;Ehlinger et al, 1994;Moletta et al, 1994;. Fluctuation noise in the gas flow measurements is common, and data filtering is often necessary if smooth gas measurements are needed for control purposes.…”

“…The CH 4 and CO 2 percentage can be measured using gas chromatographic methods or infrared measurements. The use of methane production as a process output for control is commonly employed (Renard et al, 1988(Renard et al, , 1991Ryhiner et al, 1992;Boscolo et al, 1993;Polihronakis, Petrou, and Deligiannis, 1993;Ryhiner, Heinzle, and Dunn, 1993;Chynoweth et al, 1994;Ehlinger et al, 1994;Moletta et al, 1994;Pullammanappallil et al, 1991Pullammanappallil et al, , 1992Pullammanappallil et al, , 1998. Pressure sensing is a reliable and straightforward technique for the on-line quantification of gas consumption or production in bioprocesses when only a single gas is involved (Anderlei et al, 2004).…”

Multi-objective cascade controller for an anaerobic digester

“…Rule-based expert systems have also been reported for the supervision and control of AWT systems [18][19][20][21][22]. Most of the recently published work about expert systems for AWT control is based on fuzzy logic [23][24][25][26][27].…”