循环流化床锅炉燃烧改性高硫煤的污染物排放特性

Pollutant emission performance of additive-upgraded high-sulfur coal in CFB combustion

为有效和清洁利用高硫煤资源,提出了利用复合添加剂的高硫煤改性技术,通过与低硫煤混烧,SO_2排放浓度不高于低硫煤单独燃烧时的排放,并通过改性煤技术,实现高硫煤混燃条件下总烟气SO_2的超低排放。为验证高硫煤改性技术的基本思想,在1 MW循环流化床燃煤试验系统中,对混煤、配煤及改性高硫煤燃烧过程中气体污染物排放特性进行了试验研究。研究表明,将含有复合添加剂的改性高硫煤与混煤混烧,SO_2排放浓度与混煤单独燃烧时的排放浓度基本持平;将部分高硫煤直接与混煤掺混后,再与部分改性高硫煤混烧,总化学计量摩尔比为2.5,连续试验21 h,SO_2平均排放浓度为21.5 mg/Nm^3,炉内脱硫效率达到98.8%;复合添加剂使其他燃煤污染物气体(N_2O、NH_3、HCN、HCl、HF、CH_4及CO等)的排放浓度均得到不同程度的减少。高硫煤改性技术是高硫煤实现清洁利用的有效途径。

A technology was proposed to upgrade the high-sulfur coal by utilizing the composite chemical additives. The technology aimed at achieving SO2 emission no higher than the base-coal when it was co-fired with the additive-upgraded high sulfur（AUHS） coal. Fur- thermore ,when the AUHS was co-fired with the base-coal ,the SO2 produced from both the base-coal and high sulfur coal could be re- duced to meet the strictest emission standard,e, g. ultra low emission standard（ i. e. 〈35 mg/Nm3 ）. To validate the technologic concept, experimental tests with a base-coal, a high-sulfur coal and their blend were combusted in a 1 MW pilot circulating fluidized bed （CFB） test facility. The results show that the SO2 emission is almost same as that of base-coal when 30% high-sulfur coal co-fired with the addi- tives. Further experiments demonstrate that co-firing the additive-containing high-sulfur coal with a blend of high sulfur coal and base- coal（ total high sulfur coal is 30% ） with an overall stoichenmistric ratio of 2.5 reduces the SO2 emission to 21.5 mg/Nm3. It is lower than the current national uhralow emission standard of 35 mg/Nm3. The in-situ sulfur removal efficiency is 98.8%. In addition, the additives used to upgrade the high sulfur coal also inhibit the production of other gaseous pollutants, such as N2 O, NH3 , HCN, HC1, HF, CH4 and CO reflected by the lower emissions of these pollutants. The investigation confirms that the technology presenting in this study is one of the most effective and economic solutions for clean utilization of high sulfur coals.