A Simulation Study Of NO_x Flue Fas Treatment System Based On Hydroxyl Radicals

Diesel engine occupies an irreplaceable position in the ship power system, it not only produces normal combustion products, but also produces a large amount of harmful substances in the process of combustion, NOx is one of the main pollutants of a Marine diesel engine.With the continuous development of shipping industry, air pollution is becoming more and more serious caused by ship diesel engine exhaust emissions.In view of the increasingly serious ship flue gas pollution problem, this paper put forward a denitration method with hydroxyl radicals formed by gas phase and liquid phase in ultrasonic environment.The gas phase denitration method is that the ozone from the power which discharges with high frequency and high voltage under atmospheric pressure and ultrasonic spray containing H2O₂ and H2O+under ultrasonic wave injected into reactor to form hydroxyl free radical and oxygen active particles, and finally those particles react with nitric oxide to generate HNO₃. Liquid denitration method is that the flue gas mixing with ozone are injiected into deionized water, and finally generating HNO₃ through the ultrasonic strengthening reaction to form hydroxyl free radicals.The application of the kinetic theory and methods illuminates chemical reaction mechanism on hydroxyl free radicals conversion of oxygen- active particles based on ozone and ultrasonic water fog in the smoke circumstances,discusses the hydroxyl free radical oxidation reaction process of removal. This paper designs the experiment system according to the principle of hydroxy denitration,and simulates the gas in flue gas denitration reactor with a mixture of ozone and ultrasonic spray based on Fluent software. This paper analyzes the main influence factors affecting denitrogen of the ozone formation and the oxidation of nitric oxide through the experiment and establishes the appropriate technological denitration conditions of hydroxyl free radical oxidation.Finally making a system simulation based on hydroxy denitration test with Aspen Plus software.The simulation results based on Fluent software show that all ozone and water fog are well mixed in reactor.The experimental results show that the concentration of ozone was positively related with the discharge current and inversely correlated with O₂ intake flow. in the reactor, the oxidation rate of ozone to nitric oxide is more than 90%. Gas denitration rate can be up to44.4% and 91.8% respectively when the mole ratio of ozone to nitric oxide was 1.0 and 2.0under ultrasonic environment, The liquid phase denitrification rate is up to 84.5% when the molar ratio of ozone to nitric oxide was 1.0 under ultrasonic environment.The denitration efficiency increases as the temperature increases first and then decreases if simulating the liquid phase of denitration system based on Aspen Plus software.The denitration efficiency is very high At a temperature of 90 to 160?.The denitrification rate increases with the molar ratio of ozone and nitric oxide. The denitration efficiency can reach 87% when the optimal molar ratio from 0.8 to 1.