Transformation And Effect Research On New Burner With Low NO_X Emission Of 300MW Unit

Nitrogen oxides are one of the main pollutants in the atmosphere, which result in acid rain, photochemical pollution and so on. Since a lot of nitrogen oxides are produced in the burning process, utility boilers have become one of the major sources of nitrogen oxides. According to the recent the national and local standards, emissions concentration of nitrogen oxides are limited to less than 100 mg/m3, power plants are required to use low nitrogen burning technology to reduce nitrogen oxides emissions in the process of boiler operation.Working principle of double-scale low nitrogen burning technology is introduced, which is divided to three areas in longitudinal direction and is divided to two areas in horizontal direction; such arrangement can reach the purpose of fuel concentration separation and air concentration at different levels; so emissions concentration of nitrogen oxides is reduced; anti-clogging and anti-corrosion are also implemented.Basic operation situation of the fourth unit in the Shiheng Power Plant, coal milling machine and fuel system, combustion system, burner tilt and so on are introduced; the transformation of double-scale low nitrogen burner is also introduced, the structures of the burner, the secondary air room, SOFA room, the secondary air duct and so on are decrypted in details.After the transformation, cold state experiment is implemented. During the experiment, the first air speed in each layer of coal mill is adjusted to accurate, the character of secondary air damper is texted, fireworks experiment is organized to check airflow distribution and aerodynamic field. The results show that the airflow distribution is in good condition, the track of air closing to wall is obvious. Such provide the references to the hot state experiment.Then hot state experiment is implemented. The parameters such as excess air ratio, the adjustment of secondary air, the adjustment of SOFA, are optimized. The results show that emissions concentration of nitrogen oxides is reduced sharply, boiler efficiency is pretty high, carbon content in fly ash is obviously reduced, steam temperature fluctuate in the normal range, other economy indicators are in good condition.The results show that boiler efficiency changes with coal quality changing, but it maintains pretty good condition; when coal with high volatile is in the upper layer and coal fineness is lower, missions concentration of nitrogen oxides is reduced sharply; when unit load is 300MW, secondary air is allocated like straight tower; when unit load is less than 250MW, secondary air is allocated like thin tower; so boiler efficiency is boosted, emissions concentration of nitrogen oxides is reduced.