中度与极度低氧稀释(moderate or intense low-oxygen dilution,MILD)氧燃烧技术能同时实现低碳和超低NO_(x)排放,是一种创新性的燃烧技术。通过实验方法研究了不同稀释剂(N_(2)、CO_(2)和H_(2)O)、氧气浓度、当量比和氧化剂预热温度下...中度与极度低氧稀释(moderate or intense low-oxygen dilution,MILD)氧燃烧技术能同时实现低碳和超低NO_(x)排放,是一种创新性的燃烧技术。通过实验方法研究了不同稀释剂(N_(2)、CO_(2)和H_(2)O)、氧气浓度、当量比和氧化剂预热温度下甲烷非预混MILD氧燃烧和排放特性。实验发现,N_(2)、CO_(2)和H_(2)O稀释的所有工况中均没有观察到火焰。但N_(2)稀释时,炉内温度和NO排放都比较高,且当氧浓度、当量比或氧化剂温度增加时,NO排放急剧升高(>100×10^(-6)),因此无法实现较好的MILD氧燃烧。与之相比,CO_(2)或H_(2)O稀释下,炉内温度较低,NO排放也非常低(<10×10^(-6));并且NO排放对氧浓度、当量比和氧化剂温度的变化不敏感,能在更宽的范围内建立起低排放的MILD氧燃烧。此外,CO_(2)稀释时会产生较高的CO排放(>20×10^(-6)),但H_(2)O稀释下几乎没有CO排放,且NO排放最低(≈1× 10^(-6))。因此,H_(2)O稀释最有利于实现超低排放的MILD氧燃烧。但实际炉膛应用时需要注意防止H_(2)O稀释造成的炉壁汲水和因此导致的热效率降低、甚至熄火。展开更多
The laminar combustion characteristics of CH_(4)/air premixed flames with CO_(2) addition are systemically studied.Experimental measurements and numerical simulations of the laminar burning velocity(LBV)are performed ...The laminar combustion characteristics of CH_(4)/air premixed flames with CO_(2) addition are systemically studied.Experimental measurements and numerical simulations of the laminar burning velocity(LBV)are performed in CH_(4)/CO_(2)/Air flames with various CO_(2) doping ratio under equivalence ratios of 1.0–1.4.GRI 3.0 mech and Aramco mech are employed for predicting LBV,adiabatic flame temperature(AFT),important intermediate radicals(CH_(3),H,OH,O)and NO_(x) emissions(NO,NO_(2),N2O),as well as the sensitivity analysis is also conducted.The detail analysis of experiment and simulation reveals that as the CO_(2) addition increases from 0%to 40%,the LBVs and AFTs decrease monotonously.Under the same CO_(2) doping ratio,the LBVs and AFTs increase first and then decrease with the increase of equivalence ratio,and the maximum of LBV is reached at equivalence ratio of 1.05.The mole fraction tendency of important intermediates and NO_(x) with equivalence ratio and CO_(2) doping ratio are similar to the LBVs and AFTs.Reaction H+O_(2)⇔O+OH is found to be responsible for the promotion of the generation of important intermediates and NO_(x) under the equivalence ratios and CO_(2) addition through sensitivity analysis.The sensitivity coefficients of elementary reactions that the increasing of CO_(2) doping ratio promotes or inhibits formation of intermediate radicals and NO_(x) decreases.展开更多
基金The authors would like to thank the National Natural Science Foundation of China(52176095)Anhui Provincial Natural Science Foundation(2008085J25)the Project of support program for outstanding young people in Colleges and Universities(gxyqZD201830)for their financial support of this study.
文摘The laminar combustion characteristics of CH_(4)/air premixed flames with CO_(2) addition are systemically studied.Experimental measurements and numerical simulations of the laminar burning velocity(LBV)are performed in CH_(4)/CO_(2)/Air flames with various CO_(2) doping ratio under equivalence ratios of 1.0–1.4.GRI 3.0 mech and Aramco mech are employed for predicting LBV,adiabatic flame temperature(AFT),important intermediate radicals(CH_(3),H,OH,O)and NO_(x) emissions(NO,NO_(2),N2O),as well as the sensitivity analysis is also conducted.The detail analysis of experiment and simulation reveals that as the CO_(2) addition increases from 0%to 40%,the LBVs and AFTs decrease monotonously.Under the same CO_(2) doping ratio,the LBVs and AFTs increase first and then decrease with the increase of equivalence ratio,and the maximum of LBV is reached at equivalence ratio of 1.05.The mole fraction tendency of important intermediates and NO_(x) with equivalence ratio and CO_(2) doping ratio are similar to the LBVs and AFTs.Reaction H+O_(2)⇔O+OH is found to be responsible for the promotion of the generation of important intermediates and NO_(x) under the equivalence ratios and CO_(2) addition through sensitivity analysis.The sensitivity coefficients of elementary reactions that the increasing of CO_(2) doping ratio promotes or inhibits formation of intermediate radicals and NO_(x) decreases.
