800MW机组制粉系统掺混冷炉烟改造设计及影响分析

Analysis on Retrofit for Blending Cold Flue Gas into Coal Pulverizing System of an 800 MW Unit

针对烟煤锅炉直吹式制粉系统大比例掺烧褐煤,为解决制粉系统磨制高挥发分褐煤易燃易爆等问题,提出了在制粉系统中掺混冷炉烟的改造方案,使褐煤掺烧比例达到50%以上,制粉系统末端含氧质量分数降低到16%以下。计算表明:从引风机出口抽取冷炉烟至一次风机入口的改造方案是可行的,能够满足制粉系统在各种运行工况下的防爆要求,并能提高制粉系统干燥能力。详细分析了改造后对锅炉产生的影响。

Aiming at the co-combustion of lignite at a high proportion in direct firing pulverizing system of a bituminous boiler and to solve problems such as the inflammability and explosion hazard of the high volatile lignite ground in the pulverizing system, etc., a retrofit scheme of blending cold flue gas into the pulverizing system is proposed, which makes the co-combustion proportion of lignite reach more than 50% and decreases the end oxygen content of the pulverizing system to lower than 16%. It is shown by calculation that the retrofit scheme of extracting cold flue gas from outlet of the induced draft fan to the inlet of the primary air fan is feasible and can meet the anti-explosion requirements and improve the drying capability of the pulverizing system under various operation conditions. At last, influences of the retrofit on the boiler are analyzed in detail.