Research On Micro-hybrid Combustion Method Of Hydrogen-rich Fuel

Micro-mixing combustion technology is a new DLN(Dry Low NOx)combustion technology proposed for adapt to hydrogen-doped fuel,which is to increase the turbulence intensity in the nozzle by reducing the size of the burner,so that the fuel/air mixing in the premix section is more uniform,so as to achieve lower NOx emissions.Its special structural characteristics are similar to the flow field characteristics of cylindrical jets,which will form a separate small flame at the outlet of the burner,which can inhibit the phenomenon of tempering,hanging fire,selfignition and other phenomena when burning hydrogen-rich fuel,and can also shorten the residence time in the high temperature area.In,this regard,this paper will carry out the fuel/air mixing uniformity study and combustion characteristics of microhybrid burner based on 60%H2+40%CH4 hydrogen-rich fuel,and the main work is as follows:(1)The blending characteristics of micro-mixed burners with three different fuel/air blending methods were studied by numerical simulation method,and the differences in fuel/air mixing capacity of the three burners were compared and analyzed,and the mixing laws of different fuel/air mixing methods were obtained;Then,the effects of fuel/air jet aperture,premix section length,and burner nozzle size on the uniformity of fuel/air mixing were studied,and the design criteria were extracted.(2)The combination of experiment and numerical simulation was used to study the characteristics of the flow field,flame characteristics,NOx emission and combustion instability of the micro-hybrid model burner using the above hydrogenrich fuel at different flow rates.It is concluded that the flow field is similar to a cylindrical jet type small flame,and the velocity field simulated by the RANS-FGM model is basically consistent with the experimental results.The flame is relatively independent at the burner outlet,and the NOx emission results show that the burner has good applicability to running hydrogen-rich fuel.(3)Under the same experimental conditions,the nozzle size of the aforementioned micro-hybrid model burner was reduced,the change of fuel/air mixing level and flow field characteristics of the optimized microhybrid burner were studied,and the combustion characteristics of different hydrogen contents were studied to analyze the inhibitory effect of the optimized micromixed burner on NOx emissions.