Study On Related Characteristics Of Flat Flame Clean Combustion Under Different Structures And Parameters Of Burner

The flat flame burner is a new type of combustion device.Compared with the traditional direct-flow burner,the flat flame burner has the advantages of less fluctuation of flame surface,uniform heating temperature and strong heating ability.Flat Flame combustion technology is of great significance in saving energy,improving heating efficiency,reducing pollutant emission and achieving high efficiency and clean combustion in industrial furnaces.The flat-flame clean combustion laboratory bench was designed and built by ourselves.Under the existing burner structure,the hot state experiments of flat-flame clean combustion was studied by changing the insertion depth of fuel tube and air excess coefficient,the experimental phenomena were observed and the measured data of thermoelement and flue gas analyzer were analyzed.The results show that the insertion depth of the fuel tube directly affects the mixing position of gas and air.With the increase of the insertion depth,the size of the combustion zone formed by the flame decreases gradually,and the peak temperature reaches above 1 000°C.The temperature distribution is uniform at the position of the flared expansion outlet,it burns more stable.With the increase of excess air coefficient,the mixing of rotating air flow and gas becomes more sufficient,and increases the combustion area.The excess air coefficient is too large to meet the requirements of the heat efficiency of the burner.It increases the heat loss of the burner.Therefore,the air excess coefficient 1.0～1.3 is considered in the industrial production process.The hot state experiment of air combustion was carried out by using gas swirl flow and arranging air pipes at the tangency of the flared expansion outlet.The flame phenomenon,the temperature field of flame surface in flat flame combustion,and the NO_Xconcentration field of flat flame combustion with different air entry angles and central wheelbase were studied.The results show that under the condition of the same central wheelbase the cutting angle of 90°is larger and rounder than that of 120°in combustion flame surface,the dynamic field formed by airflow rotation is stable,the temperature distribution is uniform,and the peak temperature and NO concentration are lower.When the central wheelbase increases at different cutting angles,the flame surface extends outward continually,the combustion flame area increases,the combustion becomes more stable,the peak temperature decreases,and the NO emission decreases.The commercial computational fluid dynamics software Fluent was used to simulate the burner after optimizing the parameters under the condition of pure oxygen combustion.Temperature field,flow field and CO₂concentration field of flat flame combustion under different excess oxygen coefficient were analyzed.According to the simulation:With the increase of oxygen excess coefficient,the recirculation area under the outlet of the fuel pipe decreases,which makes the area of the flame black center decrease,and the mixture of gas and oxygen is more sufficient,which is more conductive to the formation of flat flame combustion.The increase of excess coefficient of oxygen is beneficial to the full combustion of gas,but the excess coefficient should not be too large,otherwise the temperature of both sides of furnace will be reduced,which is decrease the heat efficiency of the burner.It is not conductive to the heating of the workpiece.At the same time,if the excess oxygen coefficient is too large,the concentration of CO₂in the furnace will be reduced,and oxygen will be doped in the flue gas,which is not conducive to the capture of CO₂.In general,when the excess oxygen coefficient is 1.15,the flat flame combustion is more favorable.