Evaluation Of Combustion State For Utility Boiler Based On Emissions Analysis

The operation of modern power plants is limited by more and more strict environmental rules, especially after Effectiveness of Kyoto Agreement and GB13223-2003 emission standard of air pollutants for thermal power plants took effect. My thesis researched into emissions of utility boilers, which aimed at judging combustion state based on emission analysis. Main content of my thesis can be summarized as follows:(1) An on-line monitoring model was built via analyzing mechanism of combustion process, achieving statistic laws of elements component of coal which was for power generation , and on-line measuring emissions. The methodology is based on the fact that emissions are products of coal combustion and combustion state, so calculation of coal information according to emissions is logical, meanwhile, statistic laws making the model usable.(2) The model, which bases on mechanism and statistic laws, needs much emissions information, however, part of information is unattainable because of equipment reason or technical reason in practical terms. In my thesis, soft-sensor models, such as water in coal, CO2 content in flue gas and so on, were built by indirect computation of measurable or easy-securable parameters.(3) After coal elements component can be attained on-line, the key point to control is the ratio of air and coal. Thesis tried to improve combustion economic performance via the excess air ratio, which had been amended via coal elements component. Thesis did not illustrate and calculate the economic index directly, and had the amended excess air ratio to supervise combustion. Thesis applied the amended excess air ratio to analyze representative operation states to point out their deficiency.(4) Combustion was taken as an economic process to build its ratio of output and input, while environmental charges were included in input. After standardizing, an efficiency index in general, which had a similar appearance to conventional thermal efficiency, was built. The efficiency index in general was used as measurement of representative operation states.(5) Optimization load distribution was studied, whose aim was maximizing the efficiency index in general. Comparison among distribution according to the efficiency index in general, practical load distribution and distribution according to coal consumption was made to achieve the conclusion that efficiency in general of single unit is unnecessarily improved after optimization load distribution according to the efficiency index in general, but efficiency in general of the whole power plant must be improved.