Study On The Adaptation Of Air Preheater For Selective Catalytic Reduction And Catalysts

With the rapid development of China’s national economy, the growing demand for electricity makes boiler NOx emissions from coal-fired power plants increased year by year, causing serious environmental pollution, restricting sustainable social and economic development seriously and threating to national health. With the most stringent emission standards promulgated and implemented by the Ministry of Environmental Protection, new coal-fired power plant’s denitration device synchronization construction and built power plant’s traditional denitration unit transformation is being stepped up. Using air preheater for SCR as a new way of denitration can alleviate the adverse effects of the installation of denitrification equipment for the boiler system caused effectively has good prospects.Scholars at home and abroad have done in-depth research on traditional vanadium-titanium class SCR denitration catalyst and low temperature SCR denitration catalyst. On the basis of summarizing the results of previous studies, this paper screened denitration catalyst of relatively high efficiency in the air preheater operation temperature ranges, coated catalyst on regenerative air preheater element surface for denitration research. On the basis of meeting the national emission standards, bring forward a novel form of air preheater structure.Firstly, choosing Fe, Mn, Ce as the active material of the catalytic reduction, using TiO2 as a carrier, Preparing of 12 species of SCR denitration catalyst of vanadium-titanium-based,manganese-cerium-titanium-based, impregnation method. After denitration activity test, the Mn0.4-Ce0.07/TiO2 has relatively high denitration efficiency in the temperature range 125～200 ℃. It’s removal efficiency of NO can reach 93.70%, can be used in the simulation segment denitrator of low temperatures. The Mno.4-Ceo.07/TiO2 has relatively high denitration efficiency in the temperature range 200-300 "C. It’s removal efficiency of NO can reach 99.09%, can be used in the simulation segment denitrator of middle temperatures. The Mno.4-Ceo.13/TiO2 has relatively high denitration efficiency in the temperature range 300～400 ℃. It’s removal efficiency of NO can reach 91.18%, can be used in the simulation segment denitrator of high temperatures.Secondly, coating the chosed SCR denitration catalyst on the surface of the air preheater heat storage element for denitration test. By increasing the volume of a catalytically effective the temperature ranges in three area per unit method to study simulation denitrator variation of NOx removal efficiency. The results showed that: denitration efficiency of the three temperature ranges with the increase in unit volume increases the effective area of the catalytic denitration device simulation. Denitration efficiency in low temperature and middle temperature ranges into a functional form of growth with the increase in unit volume of a catalytically effective area. Denitration catalytic efficiency of the high temperature section of the effective area per unit volume increases with the number of functions in the form of pairs of growth. By varying the concentration of the three temperature ranges entrance NO to study its influence on the analog denitrator denitration effects produced. The results showed that:with the increase of inlet NO concentration, denitration device simulation denitration efficiency of three temperature ranges are increased, while exports emission concentration of NO increases.Finally, according to the selection of the type of SCR denitration catalyst, simplified model for the air preheater both high and low temperature ranges. Comparing different high and low temperature ranges simulation denitrator highly efficient denitration ratio conditions, checking this height ratio of 1.5, simulation of the denitration apparatus catalytically effective area per unit volume of 0.62 m2/m3. Chosing the Mno.4-Ceo.13/TiO2 in the use of high temperature section and the Mno.4-Ceo.07/TiO2 in the use of low temperature. On the inlet concentration of 500ppm NO test conditions, analog denitrator denitration efficiency of 89.84%, NO emission concentration at the outlet was 66.96 mg/m3, reaching the current national standards. At a temperature, NO inlet concentration and oxygen content fluctuate, analog denitration devices are maintaining high efficiency of denitrification, export NO emission concentration was maintained at 100mg/m3 or less. New analog denitration apparatus showed good SCR denitration adaptability.