0000000000046941
AUTHOR
V. Bartolozzi
Expert control of DO in the aerobic reactor of an activated sludge process
Abstract An expert control structure is proposed for the control of dissolved oxygen (DO) in a Nitrification Denitrification Biological Excess Phosphorus Removal (NDBEPR) plant to account for the several processes that are influenced by the DO concentration in the aerator. In the scheme a supervisory fuzzy controller determines the set point of an inner DO control loop where an Adaptive Robust Generic Model Control (ARGMC) controller is used. The fuzzy supervisory control has a hierarchical structure. Off-line measurements of biological parameters of influent and effluent streams can be used to periodically update the set points of the fuzzy controllers. The complete control scheme has been…
Integration of interlock system analysis with automated HAZOP analysis
Abstract The paper details the integration of a method for the analysis of interlock systems with a software support system for HAZOP analysis. The proposed software aims to enhance the potential of HAZOP in terms of depth and efficiency of the analysis. This enhancement is reached through the continuation of the hazard and operability analysis, limited to a group of events which may hold high risks for the plant and/or surrounding environment. The analysis technique of the emergency interlock systems and other plant protection measures proposed by the Center for Chemical Process Safety (CCPS) of the American Institution of Chemical Engineers (AIChE) has been assumed as a starting point. Th…
Qualitative models of equipment units and their use in automatic HAZOP analysis
Abstract The use of qualitative models in a support system for HAZOP analyses, in connection with an algorithm for finding the causes and the consequences of variable deviations, is described. The models use several representation structures among which mini-trees constitute the most important from the logical-functional point of view. The models are conceived both for continuous and batch plants. For the latter procedures, regulating the use of equipment units are also modelled using similar structures while equipment units are considered in various phases of their functioning. A brief description of the prototype support system, in which the models are implemented, is also given.
Automating HAZOP analysis of batch processes
Abstract A support system for the hazard and operabilty studies of batch processes is presented. The search of causes and consequences is automatically performed using similar qualitative models, in form of logic minitrees, for the phases of the operation procedure and the equipment units. More models are considered for the equipment units, one for each subtask in wich they are involved. The search algorithm is integrated by rules for subdividing the plant to be analysed in nodes.
A Laboratory Project for Advanced Control Methods: Control of a Neutralization Process
Abstract A neutralization process is used in a laboratory project for experimenting advanced control techniques. Students may choose among several techniques to experience the behaviour of advanced controller action: adaptive control, GMG control, fuzzy control, self tuning fuzzy control, neural control, neuro-fuzzy control. The experience in advanced self tuning controller based on fuzzy logic is proposed for the control of a neutralization process. The test of a self tuning controller based on fuzzy logic is a very important case because the resulting structure of the controller is easy to implement and modify: the final results are compared with those deriving from the application of a c…
Expert control of DO in the aerobic reactor of an activated sludge process
Abstract An expert control structure is proposed for the control of dissolved oxygen (DO) in a Nitrification Denitrification Biological Excess Phosphorus Removal (NDBEPR) plant to account for the several processes that are influenced by the DO concentration in the aerator. In the scheme a supervisory fuzzy controller determines the set point of an inner DO control loop where an Adaptive Robust Generic Model Control (ARGMC) controller is used. The fuzzy supervisory control has a hierarchical structure. Off-line measurements of biological parameters of influent and effluent streams can be used to periodically update the set points of the fuzzy controllers. The complete control scheme has been…
Adaptive Fuzzy Control of a Process with Bifurcations
Several fuzzy controllers with different structures have been considered for the control of systems with bifurcation. A mixed feedforward-feedback structure with some additional adaptation mechanisms have been checked by simulation in the control of a non-linear process constituted by a bubble column in which a slow kinetics auto-catalytic reaction takes place. Simulation results show the validity of some of the proposed controllers in avoiding the system reaching bifurcation and instability conditions.