| In recent years, demand for energy grows as rapid economic growth and continuous development of the industrialization in China. Although coal cost and the pollutant emissions of units power generation reduce each year, but the total emission is still increasing. Thus air pollution has become an urgent problem in front of us that should be solved. At present, the technology of control SO2emissions has matured, so it is important to control the formation of nitrogen oxides during coal-fired.In this paper, the control methods for the anthracite combustion will be the main research objective. The anthracite combustion experiments are carried out in the thermal balance, fixed-bed, and W flame boiler in order to obtain the NOx formation characteristics and control strategy during combustion.Thermal balance test mainly research pulverized on combustion characteristics of pulverized coal. Three kinds of low volatile coal are tested and ignition temperature,flammability index,stable combustion index and burn index are obtained. It is found that the ignition temperatures are high and the flammability is bad, but the performance of stable combustion and the burn can still be. coal ignition temperature,flammability index,stable combustion index and burn index are closely related to the volatile matter content of coal, lower volatile means poorer combustion characteristics. Three different sizes of coal in Guizhou are tested on the thermal balance and found that the combustion performance is enhanced with decreasing particle size, but when the particle size reaches a certain range, it enhanced little with size difference, in which the scope of 100～150 mesh is the most economic and ideal.In the fixed-bed reactor, combustion tests are carried out to study the laws of NOx emissions. The results show that:with temperature increases, the generated peak of NOx increases, the width of curve shortens, and volatile combustion stage occurs in advances significantly; with the increase in oxygen concentration, NOx generation peak has been increased when the peak width changes little. The NOx formation characteristics have two obvious part, the first one corresponds to a volatile NOx, the flat section corresponds to coke NOX. The study of the influencing factors found that the temperature has a significant effect on the NOx conversion rate of anthracite coal. With temperature increases, anthracite NOx conversion rate reduces; and the conversion rate increases if oxygen concentration increases; there is an optimum particle size leading to the lowest NOx conversion rate during combustion.The paper using a 300MW"W"-shaped flame boiler as a prototype, according to the similar principles, calculates the furnace size, the wind rate, wind speed, coal-fired capacity, burning installation location, two or three winds and the installation location of wind burn. The result can meet the needs of thermal test bench, and can reflect the combustion system and air distribution ratio of the prototype well.The burning experiment for the Guizhou anthracite is carried out on 3.5MW"W" flame boiler in Zhejiang university. The paper also studies the influence for the boiler combustion and pollutant emissions by the exhaust gas air, secondary air, tertiary air and air distribution ratio. The results show that the appropriate reduction of the air can help to reduce the NOx emissions and increase boiler efficiency, and the equal air distribution ratio can also improve combustion condition. Conclusion of trial has a positive significance on actual boiler operation. |
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