ENHANCED CONTROL STRATEGY OF A SEMI-INDUSTRIAL BOILER BASED ON FAILURE DIAGNOSIS SYSTEMS: A STUDY CASE ON HYBRID AUTOMATION SYSTEMS

摘要

This study aimed at implementing an enhanced control strategy in a semi industrial boiler concerning the pollutants emission management in order to minimize operational risks due to sensor failures. The proposed control strategy is fault tolerant and it uses failure diagnosis systems in association with closed-loop online monitoring. The current work was developed based on a pilot plant that is part of the utility facilities installed in the Chemical Engineering Laboratory (LADEQ) at School of Chemistry, Rio de Janeiro Federal University. The experimental applications were carried out in a plant consisting of a vertical fire-tube boiler which generates 500 kg/h of water steam and a hybrid automation system based on analog devices and industrial fieldbus networks. The flue gas loop controls the exhaust gas emission levels of CO_2 measured by an in situ gas analyzer manipulating the flow of combustion air. An auxiliary selective control structure was developed to extend the capabilities of continuous standard control loop. Thus, a switch selector automatically decides which of the redundant values measured by a commercial gas analyzer is reliable.