SNCR (selective non-catalytic reduction) and SCR (selective catalytic reduction) combined process flue gas denitrification system of CFB (circulating fluidized bed) boiler

The invention discloses an SNCR (selective non-catalytic reduction) and SCR (selective catalytic reduction) combined process flue gas denitrification system of a CFB (circulating fluidized bed) boiler, wherein the system belongs to a boiler denitrification device. The SNCR and SCR combined process flue gas denitrification system comprises an SNCR denitrification device which is arranged at the upstream of flue gas and an SCR denitrification device which is arranged at the downstream of flue gas. The SNCR and SCR combined process flue gas denitrification system of the CFB boiler has the advantages that the comprehensive removal rate of NOx can reach more than 85 percent, the ammonia escape is less than 3ppm, the system is suitable for the high-dust severe environment of the CFB boiler and can meet the requirement of high denitrification efficiency, and especially under the situation that the NOx content at the outlet of the boiler is high when fuel with high content of nitrogen and volatile matters is used, the economy and the environmental performance are better. At the same time, since a flexible temperature interval and reducing agent injection selection scheme is adopted, the goal of denitrification of any kind of CFB boilers can be achieved.