掺混方式下混煤粒径分布对燃烧特性影响

火电厂不同煤种掺混方式分为先掺混后磨制（磨前掺混）和先磨制后掺混（磨后掺混）2种。为研究不同掺混方式下混煤的粒径分布及其对燃烧特性的影响,在相同磨制条件下,对4种煤样（龙坪无烟煤、万柳烟煤以及二者在不同掺混方式下掺混的混煤）进行制备,利用激光粒径分析仪及热重分析仪,对各煤样进行粒度测定及燃烧特性分析。结果表明,磨前掺混制得的煤粉粒度分布和燃烧特性均与万柳烟煤相似,小颗粒煤粉含量较多;磨后掺混制得的煤粉粒度分布和燃烧特性均与龙坪无烟煤相似,大颗粒煤粉含量较多;磨前掺混制得的煤粉着火特性、稳燃特性、燃尽特性和综合燃烧特性均优于磨后掺混制得的煤粉。

Effects of Particle Distributions on Combustion Characteristics under Different Coal Blending Patterns

There are two blending patterns of different coals, i.e., mixing before grinding and mixing after grinding in power plants. To study the effects of the blending pattern on the distribution of coal particles and the combustion characteristics, experiments and analysis on four kinds of coal grinded under the same conditions(including the Longping anthracite, the Wanliu bituminous coal and the two coals blended with the two blending styles) were conducted by the Easysizer 20 laser particle size analyzer and the thermogracimetric analyzer respectively. The experimental results show that the particle size and the combustion characteristics of the coal sample blended before grinding are similar to that of the Wanliu bituminous coal which is composed of much more portion of small particles, while the particle size and the combustion characters of the coal blended after pulverization is close to the Longping anthracite which consists of much more large particles. The coal blended before grinding outperforms those blended after grinding in the aspects of the ignition index, combustion stability, burn-out characteristics and comprehensive combustion characteristics.