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Selective Non-catalytic Reduction (SNCR) Technology In The Ring Fluidized Bed Boiler Flue Gas Denitrification Engineering Applications

Posted on:2014-04-20Degree:MasterType:Thesis
Country:ChinaCandidate:K ChangFull Text:PDF
GTID:2261330398999132Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
At present, circulating fluidized bed (CFB) boiler has become the preferred high efficiency&low pollution combustion technology in China. Compared with ordinary coal-fired boilers, NOx emission of CFB boilers is much lower (only less than300mg/Nm3) because of the application of low NOx combustion technology. However, most of existing or newly built CFB boilers could not meet the new pollutants emission standard which was published in2011.So it’s an urgent task to carry on the NOx control project in CFB boilers by flue gas DeNOx process.Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) are the main DeNOx technology for universal engineering application.Although the DeNOx efficiency is lower than SCR(only30~60%when SCR is80~95%),but because SNCR system can be work in the furnace reactor that without expersive catalyst and large-volume reactor, therefore, the resulting advantages are low initial investment, short construction period and low operation cost.The engineering application of SNCR in CFB boilers is just beginning in China. Research on application of (SNCR) Technology in CFB boilers for flue gas DeNOx was studied in this work.This papers study on the the applicability according to NOx formation and control in CFB boilers, combined with the reaction principle, technical characteristics of SNCR technology. The research results and engineering application example indicate that NOx emission in CFB boilers could be controlled effectively by SNCR whatever urea, andydrous ammonia or aqueous ammonia will be used as reagent. SNCR applicated in CFB boilers, the NOx removal efficiency will be as high as40~70%when ammonia slip will be lower than8ppm. In50%~100%BMCR of boiler, the temperature of fule gas in the entrance of the cyclone separator at800~1000℃, which is in the optimum reaction temperature, the residence time of flue gas in the cyclone separator up to1.5-2.5s, the cyclone separator in gas solid two phase flow in favor of injecting ammonia and gas are fully mixed, these conditions to ensure the NOx and reagent is fully mixed reaction, achieve high DeNOx efficiency and reduced NH3escape.Considering the key fators like DeNOx efficiency, technical reliability, operation cost and investment and so on, SNCR is the optimal DeNOx technology for CFB boilers, it worthy for engineering application promotion.
Keywords/Search Tags:SNCR, NO_x, Fule gas DeNO_x, CFB boiler
PDF Full Text Request
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