The Research Of The Application Of SNCR Denitration Technology For1060t/h Circulating Fluidized Bed Boiler

Nitrogen oxides is one of the three major pollutants from the flue gas of coal-fired boilerpower industry. With the implementation of national emission standards (GB13223-2011), theSNCR de-nitration technology is applied to CFB boiler to achieve national standards for NOxemissions. The key factors of efficiency in CFB boiler SNCR de-nitration were analysed andoptimized through of chemical dynamics software. Firstly, the key parameters werecalculated by using ammonia reducing in SNCR de-nitration system engineering according tothe mass balance calculation method, which provided key parameters for SNCR de-nitrationprocess numerical model. Secondly, SNCR key parameters and the SNCR de-nitrationprocess of containing additives were simulated, the key factors and additives affecting forde-nitration efficiency were analysed and optimized. At the same time, the acid dew pointtemperature was calculated for ammonia escape problem in the boiler that was equipped witha SNCR de-nitration device, and the NH4HSO4which affected the air preheater wsa analyzed.Finally, the appropriate amount of reaction temperature window and reducing ammoniainjection in the boiler SNCR de-nitration were determined.This paper analyzed the performance which was put forward for a second phase21060t/h CFB boiler of a power plant in Shanxi. According to the above content, thefeasibility was researched through the SNCR technology. The key parameters were calculatedby using ammonia reducing in SNCR de-nitration system engineering according to the massbalance calculation method. The ammonia injection point locations were selected and themethod of major system equipment was choiced. Combined with the oretical calculations andanalysis of engineering practice, it was concluded that the adiabatic type gas-solid cyclone separator technology of1060t/h CFB boiler adopting SNCR technology can achieve highde-nitration.The SNCR reaction of elementary reaction mechanism was constructed based on thechemical kinetics software, and the impact of the flue gas flow characteristics in cyclone ofSNCR technology was analyzed. To predict the effects of reaction conditions and additives onthe de-nitration efficiency and determine the appropriate amount of reaction temperaturewindow and reducing ammonia injection in the boiler SNCR de-nitration, SNCR andcontaining additives SNCR de-nitration process was simulated by using the key parameters ofengineering calculations in SNCR de-nitration system.The results show that the reaction of SNCR ‘temperature window’ is narrow which isfrom1107K to1350K, in this range, the interval of NO removal rate is greater than46%, theoptimum reaction temperature of system is about1200K. The reducing ammonia is mixedwith flue gas more fully, and the longer of the residence time in the cyclone, the moresufficiently for the reaction. The reducing agent of ammonia injection quantity is kept in theammonia nitrogen mole ratio of1.5up and down in the engineering practice. The rightamount of additive can make SNCR reaction ‘temperature window’ shift to low temperature,but the maximum de-nitration efficiency would be declined. For the problem of the ammoniaescape in the boiler equipped with a SNCR de-nitration device, the acid dew pointtemperature is383.6K, the NH4HSO4which affected the air preheater wsa analyzed. Thoseprovide the oretical data for the problem that caused air preheater ash blocking and corrosionafter installing SNCR system for the boiler.