Mathematical Model Of The Power Station Boiler Fly Ash Combustible Content Prediction

The security and economy of boilers is of great importance in large coal burning plant. The fly ash combustible content is the important factor that influences the boiler efficiency, and it is an important economic index of thermal power plant. To forecast the fly ash combustible content timely can not only guide the pulverized-coal combustion of boiler to reduce the coal consumption but also improve the safety and economy of power unit operation. So it is of great importance and great value to study the formation cause and influence factors of fly ash combustible content.This paper takes combustion and heat transfer in boiler for research object, sets up one dimension combustion and heat transfer model by simplifying the flow, mix, combustion and heat transfer of medium in boiler and make the coupling calculation between combustion and heat transfer come true. So the general mathematical model for forecasting the fly ash combustible content is gained.The combustion model is based on the new idea for kinetics of char oxidation. And a coefficient named ash shell coefficient is introduced to modify the influence of ash shell covering the coke. The heat transfer model is mainly take account of enthalpy of flue gas and heat transfer by radiation. And the radiation heat transfer model with one-order imaginary plane method on the basis of fundamental principle of radiation and emissivity calculation. It can not only simplify the computation of large size engineering design computation but also satisfy the computational accuracy.Then currency program is designed in MATLAB, by which one-dimension temperature and unburned carbon content can be obtained. The program is general, it can be used in various boilers and coal types. The gas temperature distribution, consumption rate of coal and the ratio of carbon in ash can be predicated just by input furnace structure parameters, coal characteristic parameters and operating parameters to the program.This model is used for some 300MW boilers to calculate the gas temperatures and fly ash combustibles, Comparing with the measured results, it is proved that this method is reasonable and accurate.Finally, the influence of excess air coefficient, pulverized coal fineness and...