Numerical Simulation Of The Trace Elements In The Combustion Process And Reaction Mechanism

Coal will be an irreplaceable energy for a long period of time in the future. Thein-depth treatment of pollutants in coal-fired flue gas has attracted the attention of thewhole society. In addition to SO2and NOx, the pollution control of mercury and otherheavy metals have also gradually to be taken seriously. In order to better control themetal elements in flue gas emissions, it is necessary to study the transformationmechanism of heavy metal elements in combustion. While lack of accurate data onthe mechanism of heavy metal element kinetics and the experiment of dynamic data isonly for some specific conditions, so the research into the dynamics of the mechanismand coming to an agreement are the problems to solve in heavy metal pollutioncontrol.Based on the above research background, relying on the National NaturalScience Foundation of China, the initial burning flame into the nuclear particlescoupled enrichment of heavy metal elements in the process and mechanism studies,by use chemical reaction kinetics software CHEMKIN and CFD software FLUENT,this paper conduct the numerical simulation and analysis to the homogeneousoxidation process of mercury in the temperature field.In order to control the emissions of mercury in flue gas, the oxidation reaction ofmercury, physical changes, precipitation Release Rules have been further studied. Onthis basis, this paper collected the NIST database and foreign literature, integrated the32-step mercury oxidation reaction mechanism, added6-step oxidation reactionmechanism of mercury proposed by Professor Xu Minghou in Wuhan additionally,simulated the mercury in real working condition of flue gas using CHEMKIN,compared and analyzed the concentration curves of mercury and its related importantproducts, compared the reaction rate and oxidation product under differenttemperatures comprehensively. Results showed that in the oxidation reaction of Hg,Cl2played a dominant role in morphological changes of mercury, and HCl second, Oelement played a small role only in the case of Cl element is rare. The final oxidationproduct is mainly HgCl2.1200k to1300k is the fastest mercury oxidation reactiontemperature range, the oxidation rate can reach more than90%. When the temperatureis below1200k, the consumption reaction rate of HgCl2began to accelerate, make theoxidation of mercury began to buffer, but the change is not big. In the final60%-90%of the mercury pollution will be under good control.Based on the results of analyzing of oxidation mechanism of mercury andimporting the32-step mechanism into the FLUENT software, this study starts out bysimple chemical reaction hypothesis, establishes the mathematical model of IDF, thenobtains the flow field and concentration field in different conditions, which are good agreement with the previous results.