Research On Improving Low NO_x Burners And Fuel/air Mixing Uniformit

Dry Low NO_x（DLN）combustion technology is mainly the use of thermal NO_x Zeldovich principle,by controlling the temperature of the main combustion zone within the range of1660～1922K,so as to reduce the generation of NO_x.Temperature is controlled mainly by adjusting the fuel/air equivalent ratio.However,it is not enough to focus only on the fuel-air equivalent ratio.If the mixture of fuel and air is not uniform,hot spots will be generated in the combustion chamber during the combustion process,accelerating the generation of NO_x.The many advanced DLN combustor were carried out on the premixed very meticulous research,but still not tall enough attention here in China,so based on the summary of the previous work,refer to the typical DLN fuel/air premixed combustion chamber structure,combined with their own graduation project,to explore the structure of homogeneous premixed combustion chamber experiments.In order to meet the requirements of enterprises on NO_x emission from burners,this paper designs a new structure scheme of low NO_x burner by theoretical analysis and numerical simulation,which has the lowest premix unevenness.After verifying the reliability of the mathematical model and grid independence,the numerical simulation of the prototype burner was carried out.Through the numerical simulation calculation,the calculation results of the temperature,internal fluid velocity,CH₄ concentration and NO_x generation concentration of the burner were obtained.It can be seen from the results that the mixing effect and combustion characteristics of LNB1.0 burner are not ideal.The design of 16 groups of burners is calculated by using the orthogonal experimental table.The premixed unevenness of the outlet section of the burner is obtained.The range analysis of premixed unevenness is carried out to obtain the ranking of structural parameters affecting the unevenness of fuel/air mixing.By selecting the minimum S_i,j values under different structural parameters,the optimal structural scheme of the burner is found out theoretically.Based on this,a new burner model LNB 2.0 was established.The numerical simulation results of the prototype burner LNB 1.0 and the new burner LNB 2.0 were compared qualitatively and quantitatively.It is concluded that the new burner LNB 2.0 has better performance both in cold mixing characteristics and hot combustion characteristics.