Experiment Of Denitration From Sintering Flue Gas By Using Oxidizing Agents And Engineering Test

Combustion of fossil fuels and ore in the sintering process of iron and steel industry results in the formation of nitrogen oxides （NO_x）,which occupied more than 48% among the various process in iron and steel industry. At present, the majority of sintering production line was equipped with facilities for sintering flue gas desulfurization in iron and steel industry, but without denitration equipment setting, it is urgent to pay attention to the removal of NO_x from sintering gas. On the one hand due to the long sintering process time, kinds of fuel and raw material, large temperature variation etc, gas from sintering process has the characteristics of low temperature, low NOX concentration, therefore the NO_x removal technologies widely used in coal-fired power plant is not appropriate for the removal of NO_x from sintering flue gas, on the other hand, the desulfurization and denitration were operated by two steps, which needs big initial investment in devices.On the basis of the technical and economical evaluation for different oxidant, the oxidizing agents of NaClO and KMnO₄/NaClO were choosed for the oxidation denitration from sintering flue gas. And a simulation experiment platform, which is a simplified model of a kind of industrial spray tower of Nanjing Iron & Steel Co., Ltd, was set up for the simulation experiments of oxidation denitration from sintering flue gas on a laboratory scale. The effects of various operating parameters, i.e. initial gas temperature （Tg）, initial solution pH, molar ratio of NaClO/KMnO₄ （M）, initial NO inlet concentration （CN） and SO₂ initial inlet concentration （Cs）, were systematically investigated in the experiments, according to results of the simulation experiments of oxidation denitration from sintering flue gas, the most optimal experimental conditions was found initial solution pH=10, Tg=50℃, ms=6 when using NaClO/Ca（OH）₂, in this case the average removal efficiencies of NO and SO₂ could reach 98% and 60%, respectively; and the most optimal experimental conditions for oxidizing agents of KMnO₄/NaClO was solution pH=5.5, Tg=50℃, M=3 （mp=0.1, ms=0.3）, in this case the average removal efficiencies of NO and SO₂ could reach 98.8% and 70.9%, respectively.The engineering test was carried out on the sintering flue gas desulfurization process of 2×180m2 sintering plant in Nanjing Iron & Steel Co., Ltd. The test results indicated that in the case of pH=10、ms=6、Ca（OH）₂ mass concentration=30%, the average removal efficiencies of NO and SO₂ were 20% and 98% respectively when using oxidizing agents of NaClO; in the case of solution pH=5.5、M=3（mp=0.1,ms=0.3）, Ca（OH）₂ mass concentration=30%, the average removal efficiencies of NO and SO₂ were 30% and 98% respectively when using oxidizing agents of KMnO₄/NaClO. It indicated that the oxidizing agents of NaCIO and KMnO₄/NaClO could.used for the simultaneous removal of NO and SO₂ from sintering flue gas.