| Industrial boilers play an important role in economic development and national life.Traditional industrial boilers have low combustion efficiency and high pollutant discharge due to factors such as combustion organization and overall boiler technology.The pulverized coal industrial boilers have the characteristics of high efficiency,energy saving and clean emission.In recent years,it has developed rapidly under the background of energy saving and emission reduction.The pulverized coal industrial boiler industry has basically formed.In this paper,the research object was the central fuel-rich swirl coal combustion boiler of Harbin Institute of Technology The single-phase flow characteristics of the burner outlet was used to study and the burner was applied to a 29MW pulverized coal industrial boiler.The furnace combustion characteristics and NO_x generation characteristics were studied by numerical simulation and operating parameters were reasonably optimized.The research in this paper can provide reference for the research and development of industrial pulverized coal boiler burners.Firstly,a single burner was used as a prototype,and a 1:3 single-phase cold state test rig was built according to the cold modeling criterion.The three-dimensional velocity of the burner outlet area was measured by a hot wire anemometer system.The results of different air ratios showed that different air ratios had a great influence on the size of the recirculation zone and the maximum axial negative velocity.The air ratio increased from 1:3 to 3:1,and the maximum diameter of the recirculation zone increased from 1.1d to 1.4d,the area of the recirculation zone increased by 34%,and the maximum axial negative velocity on the burner centerline increased from3.6m/s to 9.8m/s.The results of different flue gas ratios showed that different flue gas ratios had a greater influence on the recirculation zone size and the maximum axial negative velocity.The flue gas ratio increased from 0:1 to 1:0,and the maximum diameter of the recirculation zone increased from 1.2d increased to 1.3d,the area of the recirculation zone increased by 19%,and the maximum axial negative velocity on the burner centerline increased from 3.4m/s to 7.0m/s.The numerical simulation was used to study the effect of the air ratio and the blending ratio of the flue gas of the outer secondary and the separated secondary air on the combustion characteristics and NO_x formation characteristics of the furnace.By analyzing the axial velocity distribution,temperature distribution,oxygen concentration distribution and NO concentration distribution of the center surface of the furnace,combined with the flue gas temperature and NO_x concentration at the outlet of the furnace.The air ratio and the blending ratio of the flue gas of the outer secondary and the separated secondary air were optimized.The numerical simulation results of different ratios of air rate showed that when the ratios of air rate was 1:3 to9:11,the NO_x emissions from the furnace outlet were in the range of 227 mg/m~3-238mg/m~3.When the ratios of air rate was greater than 9:11,the NO_x emission increased by 21%based on 227 mg/m~3.This paper recommended that the ratio of outer secondary air rate to separation secondary air rate was was suitable in the range of 1:3:to 9:11.The numerical results of different flue gas ratios showed that when the flue gas ratio was from 0:1 to 7:3,the NO_x emissions from the furnace outlet were in the range of 220 mg/m~3-231 mg/m~3,and when the flue gas ratio was 1:0,the NO_x emissions from the furnace outlet was 251 mg/m~3,which increased by 14%based on220 mg/m~3.In this paper,it was recommended that the ratio of the amount of flue gas blended by the outer secondary air and the separated secondary air was suitable in the range of 0:1 to 7:3. |
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