| In China,the process of harmless treatment of municipal solid waste is constantly advancing,and with it,the amount of fly ash brought by incineration is increasing.The fly ash is rich in heavy metals and dioxins and other harmful substances,and is listed in the"National List of Hazardous Wastes".Fly ash melting treatment technology has the advantages of volume reduction,harmlessness,resource utilization,etc.,and is currently widely used.Oxygen-enriched combustion technology has the advantages of low energy consumption,low cost and good environmental protection benefits,and is widely used in metal smelting,glass smelting and other fields.In view of the characteristics of high melting point,low heat transfer performance and low thermal melting process efficiency of incineration fly ash,oxygen-enriched combustion technology is applied to fly ash melting treatment technology.Compared with air combustion,oxygen-enriched combustion flame temperature is higher,and flue gas The increase in the concentration of triatomic gas improves the heat transfer effect in the melting furnace.Meanwhile,the speed of combustion is accelerated,the ignition temperature of the fuel is reduced,and the burnout time is reduced,which can greatly improve the combustion thermal efficiency and reduce the fuel consumption.The research basis of this paper is a set of material-stirred fly ash oxygen-enriched melting pilot platform designed and developed independently.The combination of theoretical calculation,numerical simulation analysis and field experiment is used to study the oxygen-enriched combustion process of natural gas in the fly ash melting furnace.The temperature distribution,velocity distribution and NOx emission can provide optimization and adjustment suggestions for actual combustion,and the simulation results are in good agreement with the experimental results.In this paper,the abstract physical modeling and meshing of the lance and furnace structure of the fly ash melting furnace are firstly carried out,and the appropriate mathematical model is selected for calculation.This paper makes research on the influence of factors such as oxygen concentration and excess air coefficient on combustion.The combustion temperature increases when the oxygen concentration increases,first increases and then decreases with the increase of excess air coefficient,and NO_x emission increases first and then decreases with the increase of oxygen concentration or excess air coefficient decrease,and peak at 60%oxygen concentration and excess air factor of 1.1.Secondly,the numerical simulation and experimental study of the oxygen-enriched combustion of natural gas in the fly ash melting furnace are carried out,and the influence of different lance numbers,lance arrangement angles,oxygen concentration and excess air coefficient on the combustion in the furnace is analyzed.The results show that the spray gun with the pentagonal tangent circle arrangement can achieve uniform temperature distribution in the furnace,and the torch jet has strong rigidity;in the structural design,adjusting the angle of the spray gun to reduce the diameter of the tangent circle can optimize the combustion conditions in the furnace;as the oxygen concentration increases,the combustion When the temperature increases,the NO_x emission is the highest at 60%oxygen concentration;when the excess air coefficient is 1.2,the combustion temperature can be increased and the NO_xemission can be controlled to be lower. |
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