Numerical Simulation Of Hybrid SNCR-SCR

Hybrid SNCR-SCR technologies have broad application prospects, because it can reduce denitration catalyst, simplify the structure of SCR denitration tower, and alleviate the advantages of the air preheater corrosion and plugging problems.However, with the diverse and uncontrollable form in combustion, the proportion of the reducing agent and catalyst flue gas in the upstream of the first floor of SCR reactor of did not reach the engineering requirements, affecting the denitration efficiency and ammonia slip.Based on CFD software, combined with domestic and international research, the flow field and concentration of reducing of a 300MW boiler reactor were studied. What’s more, optimizing the flow field and concentration of reducing is in the way of adding deflector and rectifier grille, so that the deviation of the inlet velocity and concentration field of the first floor under full load conditions were 5.29% and 4.3%.Numerical simulations were conducted to study the SNCR process under the condition that reducing agent is 10% urea solution. Establishing many mathematical such as reductant injection and droplets heated and evaporated, turbulent mixing between reducing agent and flue gas, and heater transfer, the study of SNCR process under turbulent mixing restrictions and full load conditions were conducted. The results showed that appropriate mathematical model and calculation method is feasible and applicable to numerical simulation of the furnace SNCR denitration reaction. When the ammonia ratio is 1.3,1.5 and 2.0, the denitration efficiency were 35%,36% and 36.5%, and the ammonia escape were 15ppm,25ppm,50ppm.Lots of numerical simulation about hybrid SNCR-SCR technologies were conducted, in order to optimizing the flow field and concentrition in the SCR tower by adding up ammonia gun and changing their positions. The results showed that under full load operating conditions, using spray gun and nozzle gun is an effective way to meet the requirements of concentration field of reducing in SCR, the standard deviation of ammonia ratio in the catalyst inlet is 4.8%, and the results also proved that hybrid SNCR-SCR technologies own good validity and reliability.