Numerical Simulation On Low NO_x Combustion Of660MW Coal-fired Boiler

The worldwide environment pollution and energy use problem has been a seriousthreat to human survival and development, thus the controlling of NOxemissionsbecomes an important subject of power industry development. The coal-fired units canrun with high efficiency and low NOxemission by optimizing the operation. Therefore,the study of the mechanism of NOxproduction in coal combustion and its control methodis of great significance. Taking a supercritical660MW swirl-opposed boiler before andafter low NOxmodification as the research object, the research of the flow andcombustion of a single burner and the whole boiler’s combustion characteristic beforeand after the modification is performed using the method of numerical simulation andexperiment contrast, in order to obtain research results which are helpful to directindustrial application.First of all, the existing problems in actual operation of the boiler and the variousmodels used in the numerical simulation are simply introduced in this paper. Second,numerical simulation of single burner is carried out before and after the modification andthe flow&burning of the burner, the change of NOxproduction characteristics isobserved. The results show that the burner area temperature decreases after themodification, which is especially obvious nearby the vent. In addition, the NOxproduction rate in the region of the combustion after modification is relatively lower thanthat of before modification. Finally, numerical simulation is performed adopting the fullfurnace as the research object before and after the modification. The combustioncharacteristic is studied respectively under100%,75%and50%load, and the change oftemperature field and component field are compared before and after the modification atdifferent loads. The numerical simulation results are comparatively analyzed with theresults of the performance test. The results show that after the low NOxcombustionmodification, the problems of boiler burner nozzle falling off easily, high temperaturecorrosion of water wall and high concentration of NOxemission can be well solved. Atthe same time, the negative impact of the modification is small.