The Numerical Simulation Of Flow Field In Cement Kilns SCR Reactor

Nitrogen oxides (NOx) is one of the main sources of air pollution, which can causehaze, photochemical smog and acid rain and other severe weather phenomena.Cement, thermal power generation and other high-temperature combustion industriesare the main source of NOx emissions. With China’s increasing emphasis on NOxcontrol, selective catalytic reduction (SCR) technology become more and morepopular, because of its high DeNOx efficiency. But related technology research onSCR more concentrated in thermal power generation and other industries, the researchon SCR catalyst formulations or SCR-DeNOx systems in cement industry arerelatively small.In order to solve this problem and come to design a low dust-efficient SCR reactor.Research using the commercial computational fluid dynamics (CFD) softwareFLUENT as a computing platform, combine with related research achievements andcement flue gas emissions data,2000-tonne cement kilns as a research object,comprehensive study the SCR reactor systems process design and flue gas flowcharacteristics and other conditions.Cement kilns SCR reactor process conditions, process layout and other issues werediscussed; the structure and the number of gate leaf affect the flow field uniformity ofthe distribution of the reaction flow passage, and the corner of the top of the reactorwere studied by using standard к-ε model and standard wall function model; usingspecies transport model to simulate ammonia and flue gas mixing conditions,ammonia injection grid (AIG) layout for different positions, different jet speeds werestudied; A numerical simulation is conducted in the whole reactor system; by settingthe relative standard deviation coefficient to examine the design of catalytic reactorentrance section of the flue gas velocity and ammonia concentration distributionwhether meet the requirements of industrial design.Cold experimental physical models designed by using modeling theory and designprinciples of similarity, flue gas velocity the relative standard deviation coefficientand the system pressure drop at the entrance of the reactor physics model catalyst layer were measured and calculated, and the results were compared with the results ofnumerical simulation.Research shows that a better structure of SCR systems channel and gate leaf mayhave good effect on changing the bias flow field, the degree of mixing ammoniafumes affected by the arrangement of the ammonia injection grid position, speed andother factors of the nozzle. The flue gas velocity and ammonia concentrations at thecatalyst layer inlet section of the reactor compute from numerical simulation can meetthe requirements of industrial design. The numerical simulation results can bettermatch the measurements obtained by cold model.Generally speaking, the SCR system flow distribution optimization and relatednumerical simulation provided by the results of this study can give great support incement industry SCR system design.