Study On Combustion Optimization Of 1GW Ultra-supercritical Double Tangential Circle Boiler Burning Shenhua Blended Coal

In recent years,large capacity boiler units gradually are installed in China,while the four tangentialПtype boiler thermal deviation of exit flue gas increases with unit capacity being enlarged.Single furnace double tangential circle arrangement removes double sides in furnace water walls,effectively reducing the thermal deviation of flue gas at furnace exit,which have been widely adopted in the mega boiler furnace at home and abroad.Therefore,the research on the combustion technology of double circle pulverized coal combustion in coal-fired boilers is very beneficial for application of ultra-supercritical coal power generation technology in China.In this paper,one GW ultra-supercritical single furnace double tangential coal-fired boiler in a certain power plant in China has been chosen as the research object.Ultra-supercritical pulverized coal burners arrangement and the characters of furnace structure were studied.Operation optimizing was performed to improve pulverized coal combustion efficiency and reduce NO_x emission.Through the real furnace cold modeling,experiments were carried out to obtain the aerodynamic field in furnace conditions and surface wind speed distribution.The operation status of the burner parts at cold test condition was analyzed and the horizontal section speed distribution features were also obtained in order to fully grasp the characteristics of the furnace with double tangential circle.To improve the boiler thermal efficiency and reduce NO_x emissions,the boiler combustion system parameters were optimized,as oxygen concentration at furnace exit,the ratioes of different layer secondary air,burner swing nozzle angles and mills combination.Through the tests of boiler low load,the minimum load of the unit without auxiliary oil meets the boiler safety requirements.Through combustion optimization and adjustment,the boiler thermal efficiency of the unit under the rated load of 1GW was 94.7%,and the lowest of NO_x emission was 172.9 mg/Nm3.Units load can fall to 330 MW without auxiliary oil with combustion stabilization.The main steam parameters achieved the design values.