Performance Research On Transformation Of NOx Emission Reduction In A330MW Coal-fired Power Plant Of Qingtongxia Aluminum Corporation

The rapid development of economy leads to the dramatic increase of NOx emissionsin industrial enterprises, which have serious effects on environment. Much moreattentions have been concentrated on environmental pollution problems. To find abalance between economic development and environmental protection, the problem ofenergy conservation and emission reduction should be solved urgently.Unlike many industrialized countries, the primary energy of China is coal. The totalinstalled capacity of pulverized coal-fired power plants is over700GW, which providingnearly80%of the gross electricity in China. These power plants constitute almost half ofthe total pollutant emission volume. Therefore, pollutant reductions in pulverizedcoal-fired power plants, including NOx, CO2, SO2etc, will contribute significantly to theeffort in reducing pollutants.In order to relieve the grim tendency of NOx emissions, the measures to reduceNOx emissions are discussed in present paper. The advantages and disadvantages ofcommonly used technical renovation and transformation technologies are investigated,such as air-staged combustion, fuel-staged combustion, low excess air coefficient, lowNOx pulverized coal combustors and selective catalytic reduction (SCR) technology.Taking a330MW coal-fired power plant of Qingtongxia aluminum corporation forinstance, a low NOx combustion technology of dual-scale is adopted, also the selectivecatalytic reduction technology (SCR) is selected to further reduce NOx emissions. Testsare carried out to evaluate the performance of unit after transformation, such as thethermal efficiency of boiler, emissions intensities of NOx and CO. The results show thatunder the loads of330MW and250MW, the thermal efficiency of boiler reaches93.39%and93.51%, respectively. The unburned carbon content in fly ash achieves2.78%and2.68%, respectively. The emissions intensity of CO is31.13μL/L and26.25μL/L,respectively. And emissions intensity of NOx in side A and side B reaches244.13mg/m3and224.95mg/m3under the load of330MW, respectively. While under the load of250MW, the value reaches to229.04mg/m3and220.86mg/m3, respectively. The metaltemperatures of platen reheater, low temperature superheater, rear plate superheater and partition platen are controlled in proper limitations. The results provide a theoretical basisfor the technological energy conservation of power plants.