Research On Optimization Of Denitrification System In Power Plant

Nitrogen oxides (NOx) are one of the major air pollutants, which do harm tohuman health seriously. Nitrogen oxides are also one of the major sources of acid rain,which could generate photochemical smog. Meanwhile, nitrogen oxides participate indestroying the ozone layer. In2011, the emissions of nitrogen oxides met morestringent restrictions because of the implementation of the "Thermal Power Plant AirPollutant Emission Standards". Selective catalytic reduction (SCR) become the firstchoice in nitrogen oxides control field in coal-fired power plants due to its highdenitrication rate, reliable performance, simple structure and so on. However, inoperation of SCR flue gas denitrification systems, the energy consumption of thesystem was increased, ammonia and nitrogen oxides could not mix evenly, escapedammonia blocked the equipment in downstream. This paper focuses on the energysaving of the SCR system and the adjustment of parameter of the ammonia injectiongrid(AIG).Induced draft fan and dilution air fan are major energy consumption equipmentsin SCR system. The overall energy consumption of the system is affected by theoperating status of the induced draft fan and dilution air fan. The performancemodeling of SCR major energy equipment was established by thermodynamicanalysis, mathematical modeling and data fitting. The relationship among equipmentenergy consumption, unit load, change of coal quality, de-NOx performance wasfound and the characteristic curve of equipment energy consumption in operation wasdrawn. The characteristics of denitrification system power consumption was analyzedquantitatively by combining operation data of300MW unit, specific optimizationsolution of major energy consuming equipments was proposed. In order to the mixingfunction of the AIG, the mixing effects of AIGs with different parameter weresimulated by using FLUENT simulation software and the standard deviation in mixeddistance of2meters was obtained. A nonlinear function of the standard deviation ofthe ammonia concentration and the parameters of the AIG was obtained by using datafitting method. The optimal layout of AIG was obtained through solving the equation. The energy consumption of denitrification system was reduced and the mix effect ofammonia and NOXwas improved by adjusting the above two aspects. This paper, to acertain extent, provides a theoretical basis for the transformation of flue gasdenitrification system in coal-fired power plant.