超超临界1000MW机组加装SCR烟气脱硝装置后煤灰的变化特征分析

Variation characteristics of coal ash in an ultra supercritical 1000MW unit equipped with SCR denitration device

某超超临界1 000 MW机组加装选择性催化还原（SCR）烟气脱硝装置后空气预热器板结灰明显增加。对此,通过振筛机和标准筛,以及煤灰热重试验,对板结灰和飞灰进行了实验对比。结果表明：板结灰的热解失重量为10.5%,而飞灰的热解失重量不足1%,差异明显;升温速率对飞灰失重影响非常小;在粒径小于125μm时,飞灰中可燃物质量分数比较均匀,而当粒径大于125μm时,飞灰可燃物质量分数显著升高;粒径在≥50-63μm的飞灰中可燃物含量最高。

After the selective catalytic reduction（SCR）denitration device was installed in an ultra supercritical 1 000 MW unit,the hardened ash accumulated on surface of the air preheater increased significantly.Thus,the harden ash and fly ash collected from the above unit boiler were screened and thermogravimetric analysis was carried out to investigate their characteristics.The results show that,the paralysis weight loss rate of the harden ash is 10.5%,while that of the fly ash is less than 1%.The heating rate has less effect on its weight loss.For the fly ash particles with size less than 125μm,the combustible matters distribute evenly,while for the ones with size larger than 125μm,the fly ash combustion mass fraction increased dramatically.The combustible mass fraction reaches the highest in fly ash particles with size within the range from 50μm to 63μm.