天然气锅炉分级柔和燃烧模拟研究

燃气锅炉在我国应用广泛,随着煤改气的进行,应用越来越多, NO_x排放标准也越来越严格。降低NO_x的排放有利于减少空气污染。以小型天然气柔和燃烧炉膛为研究对象,通过数值模拟的方法研究燃料分级下的柔和燃烧特性,分析在不同当量比、不同热强度条件下轴向分级对炉膛烟气中NO_x生成的影响。结果表明,给定条件下柔和燃烧分级带来的NO_x减排收益随着二级燃料量的增加而减小,当二级燃料量在15%左右的时候可以最大程度地优化温度场分布,降低燃烧峰值温度,获得比较好的NO_x控制效果。随着当量比和热强度的提高,燃料分级带来的收益也会变大。

Investigation of Fuel-Staged MILD Combustion in a Natural Gas Boiler

The gas-fired boilers are widely used in China. With the progress of coal-to-gas conversion, more and more applications have been made, and NOx emission standards have become increasingly stringent. Reducing NOx emissions will play an important role in reducing air pollution.In this paper, the MILD combustioncharacteristics of a nature gas fired boiler with axial fuel-stagedwere studied by numerical simulations. The effect of the different equivalence ratio and heat release intensity on the NOx formation in furnace was studied. The results show that MILD combustion with axial fuel-staged can reduce the NOx formation and the NOxdecreases as the secondary fuel ratio increases under the given conditions. It will make the temperature field more uniform with lower peak temperature and lowerNOx emissions when the secondary fuel ratio is 15%.As the equivalence ratio and heat intensity increased, the effect on reducing NOxwith fuel staged combustion will be better.