混煤燃烧过程中的交互作用:煤种对混煤燃烧与NO_x排放特性的影响

Interaction of blended-coal combustion process: Influence of coal rank on combustion and NO_x emission characteristics

在沉降炉上开展了无烟煤、贫煤、烟煤、褐煤以及不同配比(25%,50%,75%)下混煤燃烧特性实验,研究了"炉外"和"炉内"两种掺烧方式下煤种对混煤燃尽及NO_x排放特性的影响。结果表明,不同煤种掺混燃烧时促进和抑制两种交互作用具有差异性。"炉外"掺烧方式下,挥发分含量差异较大的煤掺混时,交互作用明显;尤其是掺烧75%高挥发分煤时,对燃尽抑制作用表现最为显著,混煤的燃尽降低;挥发分含量差异较小的煤掺混时,交互作用相对较小,混煤的燃尽率在各掺混比例下基本接近计算线性燃尽率;混煤燃烧的NO_x排放特性随挥发分较高的煤的掺混比例增加基本呈线性变化的规律。"炉内"掺烧方式下,随两种煤延迟混合时间的增加,交互作用逐渐减弱,各单煤的燃烧独立性增强,混煤燃尽率逐渐接近计算线性燃尽率;挥发分含量差异较大的煤掺混时,改变混合时间,混煤燃尽率变化显著,挥发分含量差异较小的煤掺混时,各单煤燃烧独立性较强,改变混合时间,混煤燃尽率变化不明显;混煤NO_x排放量随延迟混合时间的增加而逐渐降低。

The influence of coal rank on the combustion and NOx emission characteristics are performed for four coals and their blended coals（ 25%,50% and 75%） under the out-furnace and in-furnace blending methods in this paper.The results show that these two opposite effects during the blended coal combustion,i. e. the promote function and the restrain function,are different under different types of coals.Under the out-furnace blending method,the interaction of blended coal is obvious when the volatile content of coals is widely different; especially,the burnout rate decreases obviously and the restrain function are found at the blending ratio of 75%.The interaction of blended coal is slight when the volatile content of coals is similar,the blended-coal burnout rate is closed to the linear principle.NOx emissions of blended coals follow the linear principle.Under the in-furnace coal blending method,the independent combustion of individual coals is enhanced as postponing the mixing time,and the blended-coal burnout rate is closed to the linear predicated value,the independent combustion of individual coals becomes stronger.For these coals with widely differentvolatile content,the effect of the mixing time on the burnout is significant; but for these coals with similar volatile content,the blended-coal burnout rate change is slight as postponing the mixing time.NOx emissions of blended coals decrease as postponing the mixing time.