Abstract:As the new national environmental standards "Thermal Power Plant Air Pollutant Emission Standards" (GB13223-2011) published, which has increasingly stringent environmental requirements, in order to meet environmental requirements better and further reduce the denitration operation cost, based on a series of research, and for the currently coal cases, the necessity and feasibility analysis on modefication of low-NOx combustor for a 300MW coal-fired boiler of a power plant were studied. Finally, the newly developed multi-dimensional depth staged combustion system of a boiler plant was adopted. In order to examine the operation state of low nitrogen combustion system after modification and find out find the best working condition for the daily operation of power plant, according to national and industrial standards related, multi-dimensional depth grading combustion system (MDSS) was debugged, and pulverizing system test and combustion optimization adjustment test were carried on. Through a series of mill output characteristics test, mill separator baffles characteristic test, coal fineness adjustment test, as well as variable oxygen volume test on customary conditions, variable high over fired air volume test, variable angles of high over fired air damper test, variable oxygen volume test, mill commissioning combination test, variable low over fired air volume test, variable sandwich air volume test, the secondary air distribution test, load characteristics test, air preheater leakage test and so on, low nitrogen combustion burner adjustments were optimized, optimum operating conditions were found out, and boiler combustion was optimized in order to meet the emission requirements that NOx content in flue gas is lower than 300mg / Nm3 before denitration reactor inlet better, and prolong the life of expensive metal catalyst in SCR reaction to further reduce operating costs of SCR denitration devices, achieving energy saving, to make the boiler combusting more stable, reliable and economic, to prevent problems of serious water wall coking and hung coke on full screen superheater, to improve boiler efficiency and achieve modificating objectives.