Research On Strategy Of Combustion Optimization Online Control Of Utility Boilers

Boiler combustion optimization techniques are one of means to achieveefficient combustion boilers, low pollution emissions and save generating cost.Especially in recent years, as China’s increasingly demanding of power generationcompanies on energy conservation and levels of power plants automation, itsimportance has become increasingly prominent. Data shows that most of ourcoal-fired units present have such problems in varying degrees with insufficientoutput, short operating cycle, high heat loss of ash incomplete combustion andexhaust gas. Merely using traditional combustion optimization test can not reallyachieve long-term and effective results of combustion optimization, so it’s necessaryto profoundly research combustion optimization systems.According to the characteristic of fossil power plants, this thesis focus on thekey issues about modeling, optimization and control of boiler combustion systems,and the application on a600MW coal-fired unit. The simulation study andapplication in the real unit proved that the research can implement the synthesisoptimization control of boiler combustion, improve the running level of boilerinstruments to optimum and make it efficient and cleaner. The main work andcontributions of the thesis are as follows:(1) According to power marketcharacteristic and natural environment nowadays, three kinds of optimization objectswhich coordinated between economic efficiency and environmental protection wereproposed to deduce the calculation method of boiler operation cost. Using geneticalgorithm optimization of the three goals, the boiler thermal efficiency, NOxemissions and operational cost under three goals were obtained.(2) A combustionoptimization control strategy was proposed based on the combination of steadyoptimization and nonlinear predictive control. Dynamic nonlinear optimizationcontrol was achieved during the boiler combustion process. The simulation andrunning on site showed that the proposed optimization strategy could realize thedynamic optimization control of boiler combustion.(3) The established model wereputted into the boiler operation to obtain dosed-loop control of combustionoptimization of experimental data, after analyzing and comparing, combustionoptimization system enables the boiler thermal efficiency was improved by0.39%,NOx emissions was reduced by11.8%, the auxiliary electrical energy consumption was reduced by0.093%.