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Experimental Study On NOx Emission Reduction By SNCR In Industrial Boiler

Posted on:2016-08-15Degree:MasterType:Thesis
Country:ChinaCandidate:Q WangFull Text:PDF
GTID:2191330473462937Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
Coal is the largest energy resources in China, which greatly promotes the economic and social development. However, environmental pollution caused by industrial production has become increasingly serious, especially the pollution of Nitrogen Oxide (NOx). In order to reduce the NOx emissions in industrial boiler, urea was used as reducing agent and the industrial boiler condition was simulated by self-designed unit furnace to study the experiment of SNCR denitration technology.The pyrolysis characteristics of urea were studied and analyzed at first, showing that the processes of pyrolysis can be divided into four stages. The gaseous products are NH3 and HNCO, in which the recovery of NH3 is higher than HNCO. Based on this, self-designed unit furnace is employed to study the SNCR denitration, focusing on the influence of temperature, NSR, oxygen concentration and different reducing agents on denitration effect. Experimental results show that the optimal denitration temperature of urea is 925℃, whose maximum denitration efficiency is 81%. And the denitration temperature window is 150℃ (875~1025℃), whose optimal NSR and oxygen concentration respectively is 1.5 and 2%. Although the overall NOx removal efficiency of liquid ammonia is better than urea, urea has a more preferable industrial prospect because of its physical advantages.The effects of the three additives, H2O2, Na2CO3, C2H5OH, on the NOxOUT denitration were studied at last. The results show that the three additives all can improve the active concentration of OH at low temperature, which can improve the denitration efficiency and broaden the denitration temperature window. Among which, the widening effect of C2H5OH is most significant which makes the denitration temperature shift 25℃ towards low temperature. The order of the three additives reducing the leakage of ammonia at low temperature is Na2CO3, C2H5OH and H2O2 from high to low. C2H5OH can increase the emission concentration of CO significantly; a trace of addictive can obviously improve the NOxOUT denitration effect; the advantage of Na2CO3 on improving the denitration effect is the most prominent among the three additives.
Keywords/Search Tags:nitrogen oxide, industrial boiler, urea, SNCR, additives
PDF Full Text Request
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