Full-load denitration device and denitration method for circulating fluidized bed boiler

Abstract

The invention discloses a full-load denitration device and method for a circulating fluidized bed boiler. A selective non-catalytic reduction method is generally adopted for denitration of the circulating fluidized bed boiler, the method does not need a catalyst, urea or ammonia is commonly used, NOx is reduced into N2, and the process is simple. The boiler is low in load, flue gas recirculation is adopted for reducing original emission of NOx, meanwhile, NOx is converted into high-valence oxides which are soluble in water in cooperation with ozone oxidation, the high-valence oxides are washed and removed, and no secondary pollution is generated. The system comprises a boiler (1), an SNCR (selective non-catalytic reduction) spray gun (2), an NOx monitor (4), an ozone spray gun (6), a desulfurizing tower (8), a recirculation fan (5) and a chimney (9), the SNCR spray gun is inserted into a boiler furnace outlet flue, and boiler flue gas passes through the desulfurization tower and then is discharged through a chimney; the recirculating fan is arranged behind the flue baffle valve, and recirculating flue gas is introduced into the boiler hearth; and the ozone spray gun is arranged in a flue between the NOx monitor and the desulfurization tower. The invention is used for the full-load denitration device and the denitration method of the circulating fluidized bed boiler.

Description

technical field [0001] The invention belongs to the field of boiler flue gas pollutant control and environmental protection, and in particular relates to a full-load denitrification device and method for a circulating fluidized bed boiler. Background technique [0002] Nitrogen oxides (NOx) produced by coal combustion in circulating fluidized bed boilers are one of the main air pollutants, causing serious environmental problems. Selective non-catalytic reduction (SNCR) is generally used for denitrification of circulating fluidized bed boilers. This method does not use catalysts, and urea or ammonia is commonly used to reduce NOx to N. 2 , the process is simple. However, SNCR technology has certain requirements on the reaction zone temperature (800°C~900°C, denitrification efficiency ~75%). During the start-up stage or low-load operation stage, the temperature drop in the reaction zone will greatly reduce the denitrification efficiency, which cannot meet the ultra-low emissi...

AI Technical Summary

Problems solved by technology

However, SNCR technology has certain requirements on the reaction zone temperature (800°C~900°C, denitrification efficiency ~75%). During the start-up stage or low-load operation stage, the temperature drop in the reaction zone will greatly reduce the denitrification efficiency, which cannot meet the ultra-low emission standard. (≤50mg / Nm 3 )

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