Reducing NOx Emissions for a 600 MWe Down-Fired Pulverized-Coal Utility Boiler by Applying a Novel Combustion System

详细信息    查看全文

• 作者：Lun Ma ; Qingyan Fang ; Dangzhen Lv ; Cheng Zhang ; Yiping Chen ; Gang Chen ; Xuenong Duan ; Xihuan Wang
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：November 3, 2015
• 年：2015
• 卷：49
• 期：21
• 页码：13040-13049
• 全文大小：628K
• ISSN：1520-5851

文摘

A novel combustion system was applied to a 600 MW_e Foster Wheeler (FW) down-fired pulverized-coal utility boiler to solve high NO_x emissions, without causing an obvious increase in the carbon content of fly ash. The unit included moving fuel-lean nozzles from the arches to the front/rear walls and rearranging staged air as well as introducing separated overfire air (SOFA). Numerical simulations were carried out under the original and novel combustion systems to evaluate the performance of combustion and NO_x emissions in the furnace. The simulated results were found to be in good agreement with the in situ measurements. The novel combustion system enlarged the recirculation zones below the arches, thereby strengthening the combustion stability considerably. The coal/air downward penetration depth was markedly extended, and the pulverized-coal travel path in the lower furnace significantly increased, which contributed to the burnout degree. The introduction of SOFA resulted in a low-oxygen and strong-reducing atmosphere in the lower furnace region to reduce NO_x emissions evidently. The industrial measurements showed that NO_x emissions at full load decreased significantly by 50%, from 1501 mg/m³ (O₂ at 6%) to 751 mg/m³ (O₂ at 6%). The carbon content in the fly ash increased only slightly, from 4.13 to 4.30%.