The simultaneous removal of NOx and SO2 from flue gas by direct injection of sorbents in furnace of waste incinerator

Abstract

A effective pollution source control technology (called SDNS) has been developed to simultaneously remove NOx and SO2 from flue gas by direct injection of fine denitration (DeNOx) and desulfuration (DeSOx) agents (named DNS and DSS, respectively) into the furnace of 300 t·d-1 waste incinerator. 75 % DeNOx efficiency and 95 % DeSOx efficiency could be acquired by simultaneous injection of 0.4 g·m−3 DNS and 0.6 g·m−3 DSS, and the SDNS system can run steadily with less than 80 mg·m−3 NOx and 10 mg·m−3 SO2 left in flue gas, which can be comparable with the complex and expensive tail-end purification processes of flue gas. The interaction and interspersion between the active components and the polymer in DNS and DSS facilitate their high reactivity with NOx and SO2 at high temperatures, and the synergistic effect between DNS and DSS in furnace further decreases their consumption. The composition analysis of ash demonstrates that the majority of injected fine DNS and DSS particles flowed out with the flue gas, and only a fraction of them was left in furnace. In addition, the simple SDNS process can not only lower the sorbent consumption but also cut down two-thirds of the investment and operating costs compared with the traditional DeNOx and DeSOx process. The demonstrated technological and economic advantages of the SDNS process signify its promising application prospect for the source control of NOx and SO2 emissions from small and medium-sized waste incineration projects.