SCR (Selective Catalytic Reduction) denitration device for NOx control of rotary cement kiln

Abstract

The invention discloses an SCR (Selective Catalytic Reduction) denitration device for NOx control of a rotary cement kiln, wherein the rotary cement kiln is connected with a heat exchanger; a reducing agent injection system is arranged at the kiln tail part of the rotary cement kiln; the flue gas outlet of the rotary cement kiln is connected with the high-temperature flue gas inlet of the heat exchanger; the low-temperature flue gas outlet of the heat exchanger is connected to the flue gas inlet of a bag type dust collector; the outlet of the bag type dust collector is connected to the low-temperature flue gas inlet of the heat exchanger; the high-temperature flue gas outlet of the heat exchanger is connected to the flue gas inlet of an SCR reactor; the flue gas inlet of a desulfurizing tower is connected with the flue gas outlet of the SCR reactor. The three denitration technologies of SNCR (Selective Non-Catalytic Reduction), integrated dust collection and denitration and SCR are combined so that the flue gas of the rotary cement kiln is denitrated three times; specifically, firstly, NOx in the high-temperature flue gas has a selective non-catalytic reaction with a reducing agent at the tail of the kiln; secondly, the bag type dust collector provided with a denitration-functional catalytic filter bag is used for dust removal and secondary denitration; finally, the third time of denitration is performed in the SCR reactor; as a result, the denitration efficiency is greatly improved.

Description

technical field [0001] The invention relates to a technology for controlling pollutants discharged from a cement rotary kiln, in particular to a cement rotary kiln NO x Controlled SCR denitrification device. Background technique [0002] Nitrogen oxide NO x It is one of the main pollutants in the atmosphere, mostly NO, NO 2 form exists. National cement industry NO in 2010 x The emission amounted to 2 million tons, accounting for about x 10% of the total, second only to the power industry and motor vehicle exhaust emissions. Facing the increasingly serious problem of air pollution, my country has clearly proposed that during the 12th Five-Year Period, NO x The binding index of 10% emission reduction puts forward higher requirements for denitrification technology. For example, the NO x Emission limit is 100mg / m 3 ; "Cement Industry Air Pollutant Emission Standard" (GB4915-2004) stipulates the NO x The emission limit is 800mg / m 3 , its pair NO x The requirements are ...

AI Technical Summary

Problems solved by technology

[0003] Currently, flue gas denitrification technologies commonly used in industry are divided into two categories: dry method and wet method. Among them, the mature selective reduction method is currently the most widely used denitrification technology in the cement industry, mainly including selective non-catalytic reduction (SNCR) technology. and Selective Catalytic Reduction (SCR) technology, SNCR technology has simple equipment and less fixed investment, but its defect is that the denitrification efficiency is low, only 30-40%, far from meeting the emission standards; SCR technology can make NO x The removal efficiency reaches more than 90%, but the particulate matter, alkaline substances and SO contained in the flue gas 2 It will cause blockage and poisoning of the catalyst in the reactor, and reduce the denitrification efficiency and service life of the catalyst. Therefore, in order to maintain the efficient operation of the denitrification system, the catalyst needs to be replaced frequently, which increases the cost of denitrification

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