煤粉燃烧过程中汞析出过程的数值模拟

Numerical simulation on mercury emission during coal combustion

利用计算流体动力学(CFD)对一台410 t/h四角切圆煤粉燃烧锅炉进行数值模拟研究,在CFD计算基础上加入了Hg反应的子模型,计算得出在燃煤过程中Hg的生成、形态转化以及不同Hg形态在炉内的空间分布.结果表明,通过对整个三维炉膛体积的Hg形态的摩尔分数积分,炉内气相Hg0占94.22%,HgO占4.96%,HgCl2仅有0.82%;HgO、HgCl2在炉内分布较均匀,HgO主要分布在燃烧器区域,HgCl2主要分布在燃烧器和炉膛出口区域;HgO和HgCl2在燃煤过程中的生成途径是相同的,HgO和O2之间存在强烈的关联;HgCl2和Cl2之间存在强烈的关联,而与HCl和Cl的关联性不强;温度仅是促使HgCl2摩尔分数升高的间接因素.

Numerical simulation of a 410 t/h tangentially coal fired furnace was performed on a computational fluid dynamics （CFD） software platform, into which a sub model of mercury was introduced. The mercury formation, distribution and transformation during the coal combustion were simulated. The results show that the gaseous Hg is 94.22% of the total, HgO is 4.96%, HgCl2 is 0.82% in the furnace, according to the integration of mercury mole fraction of the three-dimensional furnace; HgO, HgCl2 are well distributed, HgO distributed in the burner area, HgCl2 distributed in the burner area and the exit of furnace; the formation mechanism of HgO is same as HgCl2, and HgO has close relation with O2, while HgCl2 relates with Cl2 instead of HCI and Cl. High flue gas temperature improves HgCl2 mole fraction indirectly.