| With the acceleration of urbanization in China,the amount of MSW is increasing rapidly.Effective treatment of municipal solid waste has become an urgent problem.Waste incineration is characterized by obvious capacity reduction,high harmless efficiency and recyclable resources.Incineration has become the main way of waste treatment.At the same time,with the increase of sewage treatment capacity,the urban sludge increases rapidly.The high calorific value waste incinerator has the characteristics of strong fuel adaptability and low pollutants.It is an important way for comprehensive and effective treatment of solid waste to burn the municipal domestic waste and the urban sludge in the high calorific value waste incinerator.The combined optimization design of grate type and air distribution of 900t/d high calorific value MSW incinerator was carried out by numerical simulation.By using the coupling method of FLIC and Fluent,the angle of furnace front and rear arch,the position of flue and the layout of burn out air duct were studied,the ratio of secondary air and burn out air,the position and angle of secondary air duct were optimized,and the physical and chemical changes of MSW material layer and the burn out rate of MSW were obtained Temperature field,component field and pollutant emission characteristics in the furnace under various working conditions.The results show that the flue gas flow field,component concentration and pollutant emission in the incinerator are consistent with the field data under the same conditions.With the decrease of grate speed,the maximum temperature of the bed increases by 111 K,and the main combustion zone moves forward by 0.7 m;when the grate speed is 15 m/h,the garbage is fully burned in the bed;When the front and rear arch angle is21°/35°,the flow in the furnace is more uniform,forming a more complete tangential circle,which is conducive to air flow disturbance and mixing,strengthening heat transfer and combustion,and reducing high-temperature corrosion of the water wall.When the front and rear arches are 10°/35°,the minimum NO_x content at the outlet is 262.5 mg/Nm~3.When the secondary air injection angles of the front and rear arches are 67°/47°respectively,the temperature distribution in the furnace is uniform and the high-temperature corrosion on the wall is weakened.The flue gas outlet temperature of the first flue gas reaches 907℃,and the furnace flame is distributed symmetrically in the center.The flue gas in the furnace is well mixed with the secondary air,and the NO_x emission is 132.5 mg/Nm~3;the ratio of the secondary air of the burnout air,the front arch and the rear arch are 0.38:0.46:0.16,and the secondary air of the furnace is greatly disturbed,The furnace flue gas and oxygen have a high mixing degree,the gas phase combustion is vigorous,the flue gas residence time in the furnace is extended,the combustible components are fully burned,the temperature field is concentrated in the middle of the furnace,and the NO_xemission is reduced.Based on the simulation of sludge mixing conditions in a 900t/d high calorific value MSW incinerator,the influence of sludge moisture content and mixing quantity on combustion process,flow field distribution,main components distribution of flue gas and pollutant emission characteristics in Guangzhou MSW incinerator was analyzed.In the simulation process,the best blending ratio is obtained.The results show that with the increase of sludge blending,the solid-phase combustion process of grate is delayed,the evaporation rate of water is increased,the temperature is decreased,the volatile analysis rate is decreased by about 70 kg/(m~2·h),the combustion rate of coke is decreased by about 10 kg/(m~2·h),and the NO_x emission is increased by 50.98 mg/Nm~3.With the increase of sludge moisture content,the temperature decreased about 25 K,and NO_x emission decreased.The effect of mixed sludge on the velocity vector field in the furnace is small... |
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