The Numerical Simulation Of Nitrogen Oxides Reduction By Gaseous Fuel Reburning

Nitrogen oxides (NOx) are important precursors of acid rain formation,significant damage to the environment. NOx generates in coal combustion processis one of the main sources of nitrogen oxides. With the improvement ofrequirements for NOx emission control in China, effectively control the NOxemission in the process of coal is an important task of electric heating industry.Among numerous NOx emissions technology, reburning is considered to be one ofthe most economic and effective method. In this paper the technology for the studyof numerical simulation.Based on the reading and summarizes the related literature at home and abroad,It has been clear about the important influence factors of influencing gas reburningprocess, then have to carry out the reburning technology working conditions of220t/h coal-fired power station boiler by the following:Involved in the numerical simulation analysis and selection of calculationmodel, have not use reburning technology to original working condition wascalculated, and compared with industrial test data, the error is less than5%, thevalidation of pulverized coal combustion in the furnace of the correctness of thecalculation model. For two kinds of fuel gas flaring reduction NO submodel, theoverall combustion model and model based on the local equilibrium hypothesis ",get the NO concentration distribution along furnace height change trend, the overallexports of reburning model NO concentration to151ppm, based on the model of"local equilibrium hypothesis" is164ppm, the error is within acceptable range, sothe selection model based on the local equilibrium hypothesis"to calculate.The original condition, join the burning wind conditions and join the reburningfuel condition calculation and comparison, two technologies are able to reducefurnace NO emissions have obvious effect. Export commuted, the original conditionof NO concentration is663.8mg/m~3, the burning wind technology export NOconcentration is451.3mg/m~3, adopt reburning technology export NO concentrationof295mg/m~3.In the different way of secondary air with the wind, the burning rate and thewind outlet oxygen concentration of reburning conditions under the condition of combustion and emission are simulated. Results show that the equal air distributioncan well meet the needs of the burn tissue, maximum under the condition ofcontrolling temperature of play to the role of the OFA and reburning technology,NO emission reduction effect is good. α=0.7working condition withnature gas intoafter the temperature rise leads to more fuel N turning NO, so NO concentrationlevel is also higher exports of351mg/m~3. α=0.9and α=0.8, the working conditionof thermal deviation is small, and reached a low of299mg/m~3and295mg/m~3.Excess air coefficient, the greater the furnace exit the higher amount of O2, but noxemissions also decreases. NO concentration from reburning air nozzle to burnoutbetween wind jet cross section, condition by each conditions exports4.0%O2fell to240ppm is the lowest value, highest value it is mainly due to the reburning zonetemperature keep high level, make more pyrolytic hydrocarbon fuels for reducinghydrocarbon, thus achieved55.5%of the NO reduction rate.