Eddy Current Motion In A FLUENT-based Oxy-fuel Heating Furnace

Oxy-fuel combustion technology has the characteristics of high combustion efficiency,but combustion instability exists in industrial applications.MILD(Moderate & Intense Low Oxygen Dilution)combustion has the characteristics of less pollutant gas emission,but the two technologies have their own advantages and disadvantages.The combination of the two technologies will produce better combustion technology,that is,total oxygen MILD combustion technology.Therefore,this paper studies how total oxygen combustion can achieve MILD effect.All oxygen MILD combustion technology has the characteristics of high combustion efficiency and low emission of polluted gas.The whole oxygen MILD combustion technology mainly uses the flue gas suction reflux effect of the MILD combustion technology to achieve the MILD effect.Flue gas entrainment and reflux is the embodiment of gas eddy current movement.Therefore,this study mainly studies the effect of gas eddy current movement in furnace on total oxygen combustion reaching MILD state.The main research method of this subject is the combination of experiment and numerical simulation.Firstly,in the experiment,the total oxygen combustion is MILD by asymmetric nozzle high speed jet,and then numerical simulation is carried out according to the experimental conditions to verify the accuracy of the numerical simulation model.The effect of furnace gas eddy current motion on the MILD effect of total oxygen combustion was studied by numerical simulation.In the numerical simulation method,the eddy current movement of the gas in the furnace is changed mainly by changing two factors: first,the eddy current movement of the gas in the furnace is changed by changing the nozzle size,and then the eddy current movement of the gas in the furnace is changed by changing the nozzle spacing.When the numerical simulation is finished,the vortex structure in the furnace is identified by means of Liutex vortex structure identification method and Omega vortex structure identification method.Combined with streamline diagram,temperature cloud diagram,velocity,molar mass fraction of propane,oxygen and carbon dioxide,the effect of gas eddy current movement on total oxygen combustion is studied.According to the analysis,the eddy current movement of the gas in the furnace is mainly concentrated in m-0.8m 0.2 area,which is the main area of combustion reaction.The detailed analysis of the gas eddy current movement in the furnace shows that when there are a large number of vortex structures with different intensity in the eddy current MILD,the efficiency of total oxygen MILD combustion is higher.The efficiency of total oxygen combustion will decrease and even affect the MILD effect of total oxygen combustion.On the basis of experimental conditions and simulation results,it is known that the effective spacing of nozzles is 8 mm-12 mm,When the nozzle spacing is close to 8 mm,the combustion effect is the worst;When the nozzle spacing is close to 10 mm,the better the MILD effect of total oxygen combustion.By analyzing the eddy current movement of gas in furnace,the effect of gas eddy current movement on the MILD effect of total oxygen combustion is found,which provides some guidance for the application of total oxygen combustion technology in industry.