| In recent years,in order to control the NOx emission and improve the efficiency of the boiler,the boiler unit is carrying out the low NOx transformation project.In addition,the boiler furnace temperature and the wall temperature of the water cooled wall are raised.In some boiler units,there is a serious problem of high temperature corrosion of the water wall,which produces a huge potential safety hazard.In order to solve the problem of high temperature corrosion of water wall tube,a variety of improvement methods have been put forward by domestic and foreign scholars,among which,the rational introduction of wall wind is of certain positive significance to improve the high temperature corrosion of water wall.In this paper,a 600 MW supercritical wall arranged hedge combustion boiler produced in a domestic factory is used as the research object.The type of the furnace is the English bar swirling burner(LNASB).Through the gas solid two-phase flow characteristics test and the numerical simulation method,the change of the flow field in the furnace under the different working conditions is studied.Situation.According to the cold gas solid two phase experimental modeling criterion,the cold gas solid two phase flow characteristic test rig was designed,installed,built and debugged in 1:9 ratio.Three dimensional Doppler velocimeter(PDA)is used to study the influence of different wind tunnel structures and operating parameters on the flow field in the furnace.The results show that when each burner corresponds to a wall wind nozzle,the penetration of the wall is stronger but the coverage is poor.With the increase of the wind speed,the rigidity of the jet is not easy to spread,the penetration of the wall air is strengthened,the air flow is better to the wall surface,and the wind rate of the wall is less than 4%.There is almost no effect on the flow field in the main combustion zone in the furnace.Compared with the previous working conditions,the wall wind coverage is strengthened and penetrability is weakened,but the general rules are similar in comparison with the previous working conditions.When each burner corresponds to a single wall wind nozzle,the ratio of the length and width of the nozzle is changed,and the influence on the main combustion zone and the near wall area of the furnace is not large,but the more narrow the nozzle is,the worse the wall wind stability is,the greater the inclination of the adherent wind is.The numerical simulation method is used to calculate the flow and combustion characteristics of the furnace in the furnace under the above working conditions.First,the three-dimensional modeling software Solid Works is used to model the full furnace of the 1:1 furnace.Then the grid division software ICEM is used to mesh the computational domain,and the numerical calculation is carried out by Fluent14.5,and finally the results were processed by Tecplot360.The results show that the temperature of the furnace near the central wall of the furnace near the central wall of the furnace can be reduced to less than 1000 K,and the temperature of the fume in the uncovered area of the adherent wind is at 1400K-1700 K.The concentration field of O2 and the concentration field of CO show that the oxygen content in the near wall area can be increased to more than 2% and the concentration of CO can be reduced to less than 1% after the introduction of the wall.The reduction atmosphere in the near wall area of the water cold wall of the furnace is greatly relieved,and the temperature of the flue gas is reduced.The effect of the high temperature corrosion on the water wall is relieved from the source,and there is almost no effect on the combustion in the furnace. |
PDF Full Text Request