Research On Transformation System And Selection Of Denitrification Process Of A Coal-Fired Utility Boiler

With the acceleration of industrialization process and the development of the power industry, the consumption of coal was increasing year by year. Nitrogen-oxide as the main power plant boiler emissions, which can lead to serious atmosphere pollution. Therefore,how to decrease the NO_x emissions by adopting efficiently measures has become a big challenge. Based on a 240t/h tangentially fired boiler in self-generation power plants, this paper choose reasonable denitrification process and research on transformation system according to the actual situation of the power plants, The main contents are as follows:(1) Based on the effects of safety, economy and reformation, the dual-scale Low NO_x Combustion Technology & SCR denitrification process are confirmed as the final project.(2) All air outlet areas of the combustion system are checked by theoretical calculation.Meanwhile, areas and heights of the overfire air nozzle are designed. The rate of primary air was determined as 29% and the total circulation area was 0.9412m~2, The rate of auxiliary air was determined as 25.84% and the total circulation area was 0.712m~2, The rate of tertiary air was determined as 21% and the total circulation area was 0.3125m~2.(3) To assure the temperature of exit gas in the hyperthermia coal economizer and keep the optimal activity of the catalyst as well as the secure operation of the boiler, this paper carries out two kinds of renovation program for the tail heating surface. Finally, through the calculation of heat and smoke resistance, the researchers add 4 heat exchanger bundles to the hyperthermia coal economizer and decrease 2 heat exchanger bundles from the low temperature coal economizer.(4) After the final analysis to the actual operating data, the outlet gas temperature of the hyperthermia coal economizer decreases from 404.5? to 370? after renovated which fulfilled the requirements of the optimal active temperature of SCR catalyst, and the outlet gas temperature of the low-thermal coal economizer decreases from 266.5? to 255?, the hot- air temperature decreases from 325.7? to 306?, the exhaust gas temperature decreases from 139.6? to 131?. Apart from the low temperature of the outlet gas of low-thermal coal economizer and hot-air temperature, each data has achieved the standard and fulfills the renovation requirements.