Mechanism And Experimental Study On Improving Efficiency Of SCR Denitrification Synergist

The existing SCR denitrification system of coal-fired power plant is widely applied,mature and reliable technology for flue gas purification at present,however,the further improvement environmental indicators,the need for low load denitrification and the removal of the higher concentration of NO_x are more stringent for the existing SCR denitration systems.Aanlysis of the current status of the study on the fast SCR reaction and the preoxidation of NO by commonly used oxidants,the comparative experimental study of denitrification characteristics between fast SCR reaction and standard SCR reaction is carried out in this paper,the most suitable oxidant is chosen as a denitrification synergist for the fast SCR reaction,the fast SCR reaction is realized by using denitrification synergist preoxidizing part of NO in the flue gas to improve the reaction rate and denitrification efficiency of the existing SCR denitrification system.The comparative study of the characteristics of fast SCR reaction and standard SCR reaction,fast SCR reaction can adapt to a wider temperature window and maintain high efficiency,the temperature characteristics of fast SCR reaction can be better adapted to the requirements of low load or full load denitrification.the high reaction rate of fast SCR reaction can used to deal with flue gas with high speed velocity,which is avoiding additional flue gas resistance due to increasing the number of catalyst layers and reducing overall initial investment and operation cost of SCR system.The concentration of NO_x in the range of 410⁸20 mg/m³ has little effect on the denitrification efficiency of fast SCR reaction,and the fast SCR reaction is more advantageous in the treatment of high concentration NO_x flue gas,it can better adapt to the change of the concentration of denitration reactor inlet and have important theoretical significance and application value to achieve ultra-low emission of high concentration NO_x boiler,such as W flame boiler.A comprehensive comparison and analysis of the physical and chemical properties,oxidation properties,economy,safety and environmental protection of the commonly used oxidants.H₂O₂ was selected as denitrification synergist for achieving fast SCR reaction.The oxidation mechanism and performance of denitrification synergist H₂O₂ are simulated and analyzed by Chemkin software and the experimental study.With the increase of temperature,the decomposition rate and the oxidation rate of H₂O₂ increased significantly,OH?hydroxyl radical?is the dominant factor in high efficiency oxidation of NO,When H₂O₂ is not excessive,the main product of NO oxidation is NO₂.With the increase of volume concentration ratio of H₂O₂ and NO,the amount of NO₂ increases.The presence of SO₂ has little effect on the oxidation of NO by H₂O₂.Using of denitrification synergist preoxidation NO coupled fast SCR reaction to realize the process of improving removal of denitrification.From the influence of H₂O₂ carrier gas flow on denitration efficiency,it is found that denitrification efficiency increases with the increase of H₂O₂ carrier gas flow rate when the H₂O₂ carrier gas flow rate increases to 0.2 L/min,and the denitrification efficiency increase up to 10%.The optimum oxidation effect was obtained near the H₂O₂ carrier gas flow rate of 0.2 L/min,which reached the required NO/NO₂ molar ratio conditions for the fast SCR reaction.The influence of temperature on denitration efficiency showed that when the carrier gas flow rate of H₂O₂ was 0.2 L/min,the denitrification efficiency increased significantly with the increase of temperature from 275 to375?.The influence of NO_x concentration on the denitrification efficiency is analyzed,the change of NO_x concentration between 410⁸20 mg/m³ has little effect on the denitrification efficiency of fast SCR reaction.The results of the coupling experiment coincide with the previous study on the comparative analysis of the fast SCR reaction and the standard SCR reaction.Calculation of the activity,volume and life of the catalyst under two reaction conditions by fast SCR reaction and standard SCR reaction,the fast SCR reaction can increase the amount of flue gas purification,reduce the loading amount of the catalyst and prolong the service life of the catalyst,which is very considerable for reducing overall initial investment and operation cost of SCR system in power plant.