SNCR urea atomization spray gun, and denitration system and process

Abstract

The invention discloses an SNCR urea atomization spray gun, and a denitration system and process, wherein a steam pipe is arranged at a core part of the spray gun, a urea pipe is arranged at the periphery of the outer side of the steam pipe, a plurality of mixing holes are formed along the periphery of the outlet end surface of the steam pipe, and the mixing holes are communicated with the steam pipe and the urea pipe; a water-cooling casing pipe is arranged on the outer side of the urea pipe and communicated with a circulating cooling water main pipe, high-pressure steam serves as an atomizing medium, the atomizing impact force is large, the atomizing effect is fully guaranteed, the use amount of urea is saved, and the problems of mechanical atomization and compressed air atomization aresolved. Atomizing agent steam and unburned carbon in fly ash are subjected to a water gas reaction, generated reducing gas reduces part of NOx, the cost is further saved, and meanwhile, the situationthat the denitration effect is reduced due to the fact that compressed air is atomized to bring in oxygen is avoided; a water-cooling protective sleeve is arranged on the outer side of the spray gun to prevent the spray gun from being burnt out and blocked under severe working conditions, and the service life of a nozzle is effectively prolonged.

Description

Technical field [0001] The invention belongs to the technical field of circulating fluidized bed boilers, and specifically relates to an SNCR urea atomizing spray gun, a denitration system and a process. Background technique [0002] The spray gun is the core of the SNCR denitration system, and the stability of the spray gun performance is the key to ensuring the full mixing of the denitrification agent aqueous solution and the flue gas. The good atomization effect can atomize the denitration agent solution into small droplets to facilitate the reaction and save the amount of denitration agent. [0003] At present, the existing spray guns used in SNCR denitration systems mainly include the following types: single spray guns such as mechanical atomizing spray guns and air atomizing spray guns. This type of spray gun is generally suitable for fluids that are low in temperature or are not corrosive at high temperatures. Because in the SNCR denitrification system, the flue gas enviro...

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Problems solved by technology

Therefore, if the general nozzle is exposed to this environment for a long time, it is easy to burn out and block, which will lead to increased resistance and change in nozzle flow rate, resulting in poor mixing effect, reduced denitrification efficiency, and increased ammonia escape.

[0004] The mechanical atomization structure is simple, but the atomization effect is general;

[0005] Compressed air atomization effect is slightly better than mechanical atomization, but there are the following problems in the actual application process: 1) When the compressed air pressure is low, the atomization impact energy is low and the atomized droplets are large; and because the general air atomization spray gun on the market The designed atomized air and ammonia solution are in the same room, and they are easy to flow back to each other. When the pressure is low, the ammonia solution will be poured into the compressed air pipeline;

[0006] 2) The cost and energy consumption of high-pressure compressed air are relatively high;

[0007] 3) The air source in the plant is insufficient, etc. (some thermal power plants need to add air compressors if the air source is insufficient);

[0008] 4) The SNCR denitration reduction reaction requires a reducing atmosphere. When using compressed air atomization, the oxygen in the air is not only not conducive to the denitration reaction, but also part of the reducing agent (NH 3 ) is oxidized to NOx, reducing the denitrification efficiency

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