NOx Emission from a Circulating Fluidized Bed Boiler Cofiring Coal and Corn Stalk Pellets

详细信息    查看全文

• 作者：Hairui Yang ; Yuxin Wu ; Hai Zhang ; Xiaolong Qiu ; Shi Yang ; Qing Liu ; Junfu Lu
• 刊名：Energy & Fuels
• 出版年：2012
• 出版时间：September 20, 2012
• 年：2012
• 卷：26
• 期：9
• 页码：5446-5451
• 全文大小：304K
• 年卷期：v.26,no.9(September 20, 2012)
• ISSN：1520-5029

文摘

The NO_x emission from a circulating fluidized bed (CFB) boiler with 50 MW rated thermal output (50 MW_th) during the cofiring of anthracite coal and pelletized corn stalk biomass was investigated. Cofiring could improve combustion efficiency and, thus, the thermal efficiency of the boiler. However, contrary to most results found in bubbling fluidized bed (BFB) combustors and the one found in a CFB boiler burning rice husk, NO_x concentration in flue gas and fuel nitrogen conversion ratio increased with the biomass mass fraction. Several causes for such a contradiction were discussed and the configuration in combination with feedstock location of biomass was regarded as the most important one. In a CFB boiler, fuel is mostly burnt above the dense bed, opposite to that in a BFB boiler, and, thus, the average oxygen concentration above the dense bed, where biomass was fed, was higher. High bed temperature and high primary air ratio used for burning the anthracite coal increased NO_x emission and enhanced the variation trend. In addition, the catalyst-contained ash also could promote NO_x formation. The results indicated that biomass is not necessarily an effective cofiring fuel to reduce NO_x emission in a CFB boiler and in order to reduce NO_x emission, low primary air ratio, and locating the feedstock ports of biomass below the secondary air should be considered.