Numerical Simulation Study Of Air Classification Combustion In 58mw Pulverized Coal Fired Boiler

The formation of coal resources needs a very long process,and there is a certain amount of coal energy reserves on the earth.With the rapid development of human science and technology in the past two hundred years,the global energy crisis has been caused by the massive exploitation and consumption of energy.In addition,coal combustion in the furnace always accompanies with the generation of pollutants.Coal consumption is mainly in power plant boilers and industrial boilers.Nitrogen oxide is one of the pollutants in combustion products.In recent years,the state has paid more attention to the NO_X emission from boilers,so the problem of NO_X emission from coal-fired boilers needs to be solved urgently.In this paper,the NO_X simulation of a pulverized coal boiler in a thermal company is carried out,and the denitrification of the pulverized coal boiler by air staged combustion technology is studied.In this text,a 58MW pulverized coal fired boiler of a thermal company is studied.Its three-dimensional physical model is established and meshed according to its original size.Choose the appropriate mathematical model and calculation method,assume and define the boundary conditions of the model and simplify the model.Finally,using Fluent software to carry out numerical simulation of its combustion.Under the same load and parameters,the temperature of the experimental points on the boiler of the thermal company is measured,and the experimental data are processed and compared with the simulated values at the corresponding points.The results show that t he error between the experimental data and the simulation value is less than 14%(<20%),and the trend is approximately the same,which verifies the correctness of the whole numerical simulation model and the simulation method.And then,the distribution of NO_X in the furnace is obtained.Air classified combustion technology is used in this boiler.On the premise that the excess air coefficient at the furnace outlet is 1.2,the excess air coefficient in the main combustion zone is 0.75,0.8,0.85 and 0.9,respectively.The NO_X concentration at the outlet of the furnace under four different main combustion zone excess air coefficients was studied,and the denitrification under these four conditions was obtained.The results show that the denitrification effect is the best when the excess air coefficient in the main combustion zone is0.8.The average concentration of NO_X at furnace outlet decreased from 389.3mg/m~3 to 271.58 mg/m~3.This has met the national NO_X emission standards for in-service boilers.The denitrification effect is ideal.The contents of this paper and the conclusions obtained provide theoretical data support for the denitrification of the furnace.The excess air coefficient in the main combustion zone can be selected at about 0.8 when the tec hnology of air staged combustion denitrification is adopted.At the same time,the air classification combustion denitrification technology can also be combined with other denitrification methods to achieve a more ideal denitrification state,so the results of this paper provide some theoretical help for the denitrification method combined with air classification and other denitrification technologies.