SCR denitration system and method

Abstract

The invention discloses an SCR denitration system and method. The denitration system comprises a kiln tail pre-heater, a kiln tail dust collector, a heat exchanger, an SCR reactor and a reducing agent system. According to the denitration method, heat of hot flue gas of a cement sintering system is used for heating low-temperature flue gas subjected to dust removal; flue gas containing nitric oxide does not need to be heated by additionally combusting fuel, so that the energy consumption of new energy sources and the secondary pollution to the environment are avoided; with the adoption of the SCR denitration system and method, high-temperature flue gas and the low-temperature flue gas are subjected to non-transferring type heat transferring, and the heat in the high-temperature flue gas can be effectively utilized; abrasion, blocking and poisoning phenomena on a catalyst by the dust carried by the high-temperature flue gas are also avoided, so that the temperature of the flue gas to be treated is in an efficient region of the catalyst; and the reaction efficiency of the nitric oxide and reducing substances is improved.

Description

technical field [0001] The invention relates to the technical field of environmental protection, and relates to an efficient SCR denitrification system and method. Background technique [0002] NO produced by combustion of fuel in cement industry kilns x , mainly composed of NO and NO 2 composition. NO x Combined with water and impurities in the air to form nitric acid and nitrate to form acid rain, it is one of the major air pollutants. Therefore, in 2010-2012, my country aimed at the domestic cement industry NO x In response to rising emissions, a series of regulations and related policies have been promulgated. The national "Twelfth Five-Year Plan for Energy Conservation and Emission Reduction" clearly stipulates that the cement industry NO x Binding targets for emitted air pollutants. The environmental protection department also revised and issued GB4915-2013 "Emission Standards of Air Pollutants for the Cement Industry". x and other emission control requirements...

AI Technical Summary

Problems solved by technology

However, the emission reduction performance of SNCR technology is greatly affected by the conditions of the cement kiln itself. In the application, it is affected by factors such as temperature, dust, reaction time, and mixing conditions. The actual denitrification rate is often less than 50%, which cannot meet the increasingly high requirements. emission standards

The temperature of the flue gas at the kiln tail is about 350°C after passing through the first-stage cyclone. Although the temperature at this time meets the conditions for the use of commercial vanadium-based catalysts, the extremely high dust concentration and trace amounts of alkali metals in the flue gas can easily cause catalyst wear , blockage or even poisoning failure, and will greatly reduce the efficiency of waste heat power generation

The second place is after the waste heat power generation boiler, after passing through the waste heat power generation boiler, the dust and SO in the flue gas 2 The concentration of alkaline earth metals and alkaline earth metals will be reduced, but the temperature of the flue gas will be reduced to below 200 ° C. If the SCR reactor is installed here, the catalyst used will hardly overcome the adverse effects of low temperature and dust in this range

The third place is after the bag filter, when the flue gas passes through the dust collector, the dust content is reduced to below 30ppm, and the SO 2 The content of alkaline earth metals and alkaline earth metals is also significantly reduced, which is beneficial to prolonging the service life of the catalyst, but the temperature of the flue gas is further reduced, which directly affects the reaction efficiency of nitrogen oxides and reducing substances

In order to achieve better denitrification efficiency, some low-temperature catalytic reduction systems use electricity or fuel heating to heat up the flue gas or catalyst, which has the problems of high operating costs and environmental pollution caused by supplementary combustion.

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