Design And Numerical Simulation For Denitration Engineering Of Flue Gas From Coal Combustion

Considerable nitrogen oxides (NOx) were emitted from coal burning. With theincreaseing of NOxemissions, more and more attentions have been paid on the elimination ofnitrogen oxides. Selective Catalytic Reduction (SCR) for flue gas denitration has been widelyused in the world due to its established technique and high efficiency. In China, it has alsobeen considered as the main technology for NOxcontrol. Besides experimental studies,Computational Fluid Dynamics (CFD) software can also be used to simulate SCR denitrationsystem in order to provide key parameters for denitration engineering design andimprovement of flue system, guide vanes and the injection system.The denitration system was designed in this paper, including the reactor structure, thearrangement types of the entrance and exit of the flue system, the selection of the catalystsinside the reactor, the injection pipes and the nozzles in the ammonia injection grid, thenumber of the guide vanes and the size and the arrangement position of the commutatedgridiron.According to the specific design requirements and technical parameters, and combinedwith the results of numerical simulation, the reactor structure size was designed based onliteratures and national standards by this paper, the reactor size:4.4m*3m*6m; flue section:3m*1m; bend diameter:1m; bend diameter:2m; horizontal flue:1.5m; the vertical flue:3m.In order to study the effects of flow field, the ammonia injection grid and the catalyst bed wereintroduced into the reactor. It was found that the presence of catalyst bed leads to the increaseflow resistance in this system. However, the velocity field above the ammonia injection gridwas uniform and meets the standard of CV<15%. To overcome the non-uniformity of velocitydistribution inside the reactor, the guide vanes was introduced but no obvious effects werefound for the temperature field and velocity field. Thus, the commutated gridiron wasintroduced to improve the uniformity of velocity distribution, but the result is still notsatisfactory. Conclusively, the denitration engineering design can be guided and optimizedbased on numerical simulation results.