| The technology of Selective Catalytic Reduction is advanced and efficient, and it is the most widely used in the power plants. The denitrification reactor is the key equipment of the Selective Catalytic Reduction technology, so it is very important to study on the denitrification reactor. In this paper, numerical simulation and optimization on a typical structure in the 600 MW power plant were studied with the COMSOL software. The results show that:(1) A three dimensional model of the SCR denitration reactor including turbulent flow, heat transfer and reactions was established. Checking mesh and the models show that the 1m thickness and 500000 elements can reach the accuracy requirements. The results show that the Velocity of flow in the reactor increases from the left to the right of the reactor; and the gas entrances into the catalyst layers with a predetermined angle, the angle is large on the both sides of the catalyst layers, the max value is 90°, that is to say, the gas entrances into the catalyst layers vertically. The angle in the center-right part of the catalyst layers is small, and the minimum value is 70°. The temperature in the left of the reactor was higher than that in the right, the temperature difference was about 3K, the distrabution of the temperature in the catalyst layers is similar, and the difference is uniform; The concentration of NH3 and NO in the left of the reactor is higher than the right; The NO concentration at the outlet is 1.02×10-3mol/m3,and the NH3 concentration at the outlet is 9.24×10-4 mol/m3, therefore the denitration efficiency of the reactor is 66.06%, the ammonia slip rate is 22.81%.(2) Factors related to the performance of the catalyst layers were studied by simulation. Results show that as the velocity of the flue gas increases, the efficiency of the catalyst layers decreases from 77.88% to 21.99%, the escape rate of the ammonia increases from 1.27% to 21.99%; the pressure loss increases from 253 Pa to 591Pa; when the temperature reaches 550 K, the max denitration efficiency of the reactor reaches 70.01%; while the escape rate of the ammonia decreases with the temperature increasing, when the temperature beyonds 550 K, the slip rate of the ammonia changes little; As the ration of the NH3/NO changes from 0.9 to 1.2, the denitration efficiency of the catalyst layers increases from 67.47% to 74.66%, while the slip rate of the ammonia increases from 7.05% to 22.37%; As the hight of the catalyst layer increases from 1.6m to 2.4m, the denitration efficiency of the catalyst layers increases from 64.01% to 73.89%, the slip rate of the ammoina decreases from 17.82% to 5.91%, and the pressure loss increases from 337 Pa to 506Pa; The multi-objective optimization on the operating parameters(T,x0,v) and structural parameter(L) was established, the results of the Multi-objective optimization show that T=550.3K, x0=0.93, L=2.3m, v=2.0m/s, compared to the initial values, the denitration efficiency is improved by 11%, the slip rate of the ammoina decreases by 82%, and the pressure loss decreases by 8.4%.(3) The radius of the Ammonia injection hole gradually increases from 30 mm to 70 mm, the denitration efficiency of the reactor increases from 66.06% to 71.71%, the slip rate of the ammoina reduces from 25.85% to 20.20%, when the radius of the Ammonia injection hole reaches 60 mm, the denitration efficiency and the slip rate of the ammoina change little; As the hight of the No.1 deflector installation increases, the denitration efficiency decreases gradually and the slip rate of the ammoina increases gradually, when the hight reaches 12.0m, the denitration efficiency and the ammonia slip rate change little, As the No.1 deflector vertical offset distance increases, the denitration efficiency decreases at first and then increases again, the minimum and maximum relative errors are 1.7% and 9.2% respectively; As the hight of the No.2 deflector installation increases, the denitration efficiency decreases gradually and the slip rate of the ammoina increases gradually, when the hight reaches 12.55 m, the denitration efficiency and the ammonia slip rate change little; As the No.2 deflector vertical offset distance increases, the denitration efficiency decreases at first and then increases again, the minimum and maximum relative errors are 3.2% and 8.2% respectively. As the hight of the catalyst layer increases, denitrification reactor denitration efficiency increases firstly and then decreases gradually, wherein the minimum and maximum relative error of 1.5% and 3.5%.(4) The multi-objective optimization was established,the result of the Multi-objective optimization shows that r=0.061 m,H1=11.550 m,H2=11.050 m, and the denitrification efficiency is 78.02%, the ammoina rate is 13.02%, and the pressure loss is 421.95 Pa,compared to the initial value, the denitration efficiency is improved by 15.7%, the slip rate of the ammoina decreases by 43%, and the pressure loss changes little. |
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