Boiler Combustion Control System Optimization Strategy

The boiler is one of the most important equipments of the power plant production, andimproving the boiler control efficiency plays a crucial role on the whole enterprise interms of economic efficiency, safety and environmental protection. This dissertation takesthe boiler combustion system as the research object, which presents as a multi-input,multi-output, strongly coupled, and large time-delayed system. Analysising the mainparameters of the combustion and the conventiona control is not satisfactory, and thenprovide an advanced control method to control the system to make improvements, finallyachieve the purpose of improving control effect.Boiler combustion system is the core part of the three-boiler-system, and mostly affectsthe steam quality, burning economy, as well as operation safety of the overall system. Inthe conventional PID control procedure, the boiler combustion control performance isoften impaired by the fierce perturbations from inside or outside of the system. With themodern control theory developing, some advanced control concepts such as neuralnetwork, fuzzy control, expert control, and predictive control are combined with the PIDmethod for a much more effective control application.The distributed control system (DCS) is an important symbol of the rapid developmentof automation technique nowadays. As the power industry is becoming large-scaled andhighly automated, the wide application of DCS will be inevitable. The power industry aswell as other industries is enormously promoted due to the application, and not only theeconomical but also environmental demands are satisfied.In this dissertation, in order to facilitate the system analysis and improve the controlmethod, the boiler combustion system is divided into three independent subsystems: steampressure control system (fuel quantity control system), smoke oxygen content controlsystem (air supply control system), furnace pressure control system (air inducing controlsystem). With the structure and mechanism being analyzed, as well as the PID control,fuzzy control, and predictive control being fully researched, the proposed control methodsare combined with the DCS device. In order to optimize the combustion process, thesolutions of optimization are sent to the DCS, so that the devices are in proper monitoring.The specific optimization procedures are stated as following:1) In order to take fulladvantage of the fuzzy control and predictive control respectively, the two methods arecombined for the steam pressure control;2) For the purpose to achieve efficiency andsafety of the boiler system, the fuzzy-PID control is applied to control the furnacepressure as well as the smoke oxygen content.Finally, the numerical simulation is carried by the Matlab software. The results indicatethe practical value of this proposed method, as the fuzzy-predictive control and fuzzy-PIDcontrol can reduce the steady-state error, system response time and overshoot effectively.