Fume gas denitration system of coal-fired boiler based on SNCR (Selective Non-catalytic Reduction) and SCR (Selective Catalytic Reduction) combination method

Abstract

The invention discloses a fume gas denitration system of a coal-fired boiler based on an SNCR (Selective Non-catalytic Reduction) and SCR (Selective Catalytic Reduction) combination method. The system comprises a boiler and a SCR denitration device, wherein the boiler comprises a hearth, a fume outlet of the hearth, a cyclone separator, returning charge device and a rear smoke channel; the fume outlet of the hearth is connected with the inlet of the cyclone separator; the lower part outlet of the cyclone separator is connected with a dense-phase zone of the hearth through the returning charge device; the rear smoke channel is connected with the upper part outlet of the cyclone separator; a primary economizer and a secondary economizer are arranged inside the rear smoke channel; an SNCR reducing agent ejecting device is arranged at the inlet of the cyclone separator, and / or at the outlet of the hearth, and / or at the upper part of the cyclone separator; the SCR denitration device is arranged between the primary economizer and the secondary economizer, and / or ahead the primary economizer, and / or behind the secondary economizer; and the SCR denitration device comprises an SCR denitration catalyst layer.

Description

technical field [0001] The invention belongs to the field of pollutant emission control of coal-fired boilers, and in particular relates to an SNCR+SCR combined denitrification system for coal-fired boilers. Background technique [0002] Nitrogen oxides are one of the main sources of air pollution, commonly referred to as nitrogen oxides (NO X ) mainly includes NO, NO 2 , N2O 3 , N 2 o 5 Among them, NO and NO are the main ones that pollute the atmosphere 2 . Under the action of sunlight, NOX will cause photochemical reaction and form photochemical smog, thus causing serious air pollution. NO since the 1970s X The problem of air pollution in China has been paid more and more attention. It has been found that: the harm to human health, high content of nitric acid rain, photochemical smog, ozone reduction and other problems are all related to low concentration of NO X It does, and it's far more harmful than was originally thought. [0003] Nearly 70% of my country's ni...

AI Technical Summary

Problems solved by technology

However, for circulating fluidized bed coal-fired boilers, its main features are high dust and low temperature at the outlet of the economizer. For some fuels with high nitrogen content and high volatile matter, the NOx content at the boiler outlet can reach or even exceed 500mg / Nm 3 (6%O 2 , dry basis), according to the "Emission Standard of Air Pollutants for Thermal Power Plants GB13223-2011", by July 2014, the NOx emission control standard for coal-fired boilers in thermal power plants will be 100, only relying on SCR technology to denitrify the flue gas requires a large investment , high operating costs, difficult to meet the smoke emission requirements

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