混煤燃烧过程中的交互作用：机理实验研究与数值模拟

为深入研究混煤燃烧过程中的交互作用机理，在沉降炉上进行了贫煤和烟煤不同配比混煤(贫煤掺混烟煤比例0，25%，50%，75%，100%)燃烧特性的实验研究与数值模拟。结果表明，混煤燃烧过程中易燃煤对混煤燃烧的促进和抑制2种交互作用的竞争决定了混煤的燃烬特性，促进作用表现为烟煤优先燃烧，提高了燃烧初期的局部温度，促进了难燃煤的着火与燃烧；抑制作用则表现为易燃煤抢先燃烧消耗了大量氧气，导致难燃煤燃烧处于欠氧状态，阻碍了难燃煤的燃烧与燃烬。由于煤种差异大，交互作用影响明显，混煤实际燃烬率与计算线性燃烬率差异较大。掺混25%易燃煤时，促进作用在混煤燃烧中占主导地位，燃烬率高于按掺烧比例线性计算得出的计算线性燃烬率；当掺混50%易燃煤时，混煤燃烬率的出现“拐点”；进一步增加至75%时，抑制作用在混煤燃烧中占据主导地位，燃烬率明显降低。混煤燃烧NOx排放量与计算线性NOx计算值比较接近，其随着易燃煤的掺烧比例的增加而线性增加。

Interaction of blended-coal combustion process: Experimental study and numerical simulation of mechanism

In order to study the mechanism of interaction in the process of blended-coal combustion,the experiment and numerical simulation of the influence of out-furnace blending method on the combustion characteristics were performed under bituminous,lean coal and their blended coal (lean coal blends with bituminous of 0,25%,50%,75% and 100%) in this paper.The results show that the combustion of blended coal is impacted by two opposite effects:the promote function and the restrain function.The role of the two competition determines the characteristics of blended-coal combustion.The former is that the coal with higher volatile burns firstly,enhancing the local temperature to promote the low-volatile coal ignition.The latter is that the bituminous burns rapidly and consumes much oxygen to make the lean coal in lack of oxygen atmosphere,which hinders the coal combustion and burnout of the lean coal.As increasing the blended bituminous ratio,the temperature rising and O2 consume rates increase,the coal ignition advances,the concentrated combustion region moves forward.Due to the difference of coal quality,interaction effects are obvious,the practical linear-burnout degree is considerably different from the blended coal.When blending 25% bituminous,the promote function plays an important role in the combustion,the burnout degree is higher than the linear-burnout degree.When blending 50% bituminous,the burnout curve presents “turning point”.When further increasing the blending ratio to 75%,the restrain function plays an important role in the combustion,and the burnout degree decreases considerably.NOx emissions of blended coal is in consistence with linear NOx,and increase as the increase of the blending ratios.