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

Abstract

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.

Description

technical field [0001] The invention belongs to a boiler denitrification device, in particular to a CFB boiler denitrification device. Background technique [0002] At present, the mainstream technologies of flue gas denitrification devices in thermal power plants are SCR (Selective Catalytic Reduction) technology and SNCR (Selective Non-Catalytic Reduction) technology. The reactor between the preheaters removes NOx from the flue gas. A denitrification catalyst is arranged in the reactor, and the denitrification reducing agent is injected into the flue through the ammonia injection system arranged in the inlet flue to fully mix with the NOx in the flue gas. For conventional power plant boilers, the flue gas temperature at the outlet of the economizer is the temperature window required for the SCR denitrification reaction, and it is arranged with high dust, the denitrification efficiency is moderate, and the technology application is mature. However, for circulating fluidized...

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Problems solved by technology

For conventional power plant boilers, the flue gas temperature at the outlet of the economizer is the temperature window required for the SCR denitrification reaction, and it is arranged with high dust, the denitrification efficiency is moderate, and the technology application is mature. However, for circulating fluidized bed (CFB) boilers, the main It is characterized by high dust and low temperature at the outlet of the economizer. For some fuels with high nitrogen content and high volatile content, the NOx content at the CFB boiler outlet reaches or exceeds 400mg / Nm3 (6%O 2 , dry basis), the existing SCR (Selective Catalytic Reduction) technology can no longer meet the requirements

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