Preparation And Process Conditions Of Desulfurization And Denitrification For Coal Fired Flue Gas

With the development of science and technology, the problem of energy and environment has become a topic of common concern. The energy consumption of our country is mainly dominated by coal,and coal combustion generating a large number of emissions of SO₂ and NO_X is the main reason for the formation of acid rain, haze and photochemical,which caused serious damage to human and ecologicalenvironment. Therefore, the emissions control of SO₂ and NO_X are becoming the focus on environmental protection research. In a large number of desulfurization and denitrification methods of the flue gas treatments the technology of simultaneous desulfurization and denitrification possesses the lower cost and simpler equipment, and becomes an emphasis of development because of its no mature in technology in the world.For the catalyst of desulfurization and denitration, copper and vanadium compound Co – Ni-Cu- V /ZSM- 5,an enlarge reseach was complected by using the dipping process of preparation.The conversions of SO₂ and NO_X removal are considered as the ordinate and the gaoland the best preparation method is determined by using a small device and BET and appearance analysis,and the best catalyst was chosen with the equal volume impregnation method and dry step by step, such as impregnating copper vanadium first, and then dipping nickel and cobalt, repeated twice to soaked and boiled, drying and calcinating, the enlarginged catalyst preparation 10 times was finished.According to the pilot plant design and above experiments of desulfurization and denitration for the catalysts the experiments of the reaction condition,like temperature,space time,fractional CO2 and O2,have carried out in a 50 g catalyst scale.The best reaction conditions are determined as the temperature is 450 ℃, the inlet flow rate is 5.5 L/min, and better range of raw gas composition. The conversions of SO₂ and NO reachs more than 50% and 85%,respectively. The activation of the catalyst was well kept for 100 h in continuous running.The deactivation of the catalyst was renewable at 500 ℃ and in air,whose activation may be recovered to 80%. At the same time, the reaction and deactivation mechanisms were analyzed and temporary poisoning deactivation caused by elemental sulfur is considered as the main deactivation reason.In this paper the coal boiler of four tons was chosen as the object of the study and design by using catalytic integration process of desulfurization and denitration at the same time. On the basis of the current research results and in order to finish the national latest emissions standards of SO₂ and NO_X as the goal the preliminary design study has carried on. The material balance, heat calculation and calculation of main equipments of system are fulfilled and the useful results are obtained. Under the reaction conditions of desulfurization denitration the two reactions are all exothermic, can be spontaneous, and their biggest conversions could reach 100% and 93.5%,respectively. The adiabatic rise of temperature of reactor is 2.8 K, and the catalyst weight of the reactor is 14.888 tons, and the heat exchange area of the exchanger is 218.45 m2. After the converted gas is absorbed the total sulphur oxides and nitrogen oxides are both less than 200 mg/m3.