The Research Of Numerical Simulation On Effect Of Coal Characteristics On W-shaped Boiler Combustion

The high price of coal in recent years not only makes them use seriously low caloric coal but also makes the coal type fluctuate frequently, these problems has brought great influence on safe and economic operation of power station boilers. Therefore, researching on the effect of coal characteristics so as to improve the adaptability to more coals of boilers is very important to increase the safety and economy of boiler operation. Basing on the analysis of coal combustion characteristics, the effect of coal characteristics on combustion characteristics of W-shaped boilers was investigated with the method of numerical simulation.In view of this, researcher chose Taoshui coal, blended coal of Taoshui and Doulishan, Guiyang coal as the research object to conduct proximate analysis, ultimate analysis and calorific value analysis, the results showed that the volatile of blended coal was the highest, the carbon content and calorific value of Guiyang coal was the highest. Then their pyrolysis characteristic and combustion characteristic were analyzed comprehensively based on thermogravimetric curve. The results showed that the volatile release index and ignitability index of blended coal were the highest, and its ignition characteristic was the best; the combustion stability index, comprehensive index and comprehensive combustion characteristic index of Guiyang coal were the highest, and its combustion characteristic was the best; all indexes of Taoshui coal was the lowest, its combustion characteristic was the worst.With a 300MW W-shaped boiler of Zhuzhou power plant as the research object, researcher simulated the coal combustion process by FLUENT software. By analyzing the velocity field,oxygen field,temperature field,movement track of particles and burnout ratio of simulation results, researcher found that the hearth fullness and temperature distribution was the best, the overall temperature was the highest in furnace by combusting Guiyang coal; the even temperature in furnace by combusting Taoshui coa was lower than the even temperature in furnace by combusting Guiyang coal by 50℃, and the flame was not continuous. Changing coal did make obvious effects on pulverized coal residence time in furnace. Their burnout ratio were respectively 96.33%,97.06%,98.16%. The burnout ratio was increased by 1.44% when the coal fineness decreased from 16.9% to 6.5%.Test data and the numerical simulation results are almost same, so the results of boiler combustion numerical simulation are accurate. The research results can provide valuable references for choosing coal, blended coal mixed burning and boiler operation in power plants.