Study On No Removal From Marine Flue Gas By NaClO₂ Mist Based On Ultrasonic Atomization

Shiping has the advantages of large capacity,high reliability,and good economical.It is the most important transport tool in international trade.The diesel engines are commonly used as marine power plants.They cause high NOx content in the exhaust gas after combustion,which lead to serious pollution to the atmosphere and the environment.To meet the requirements of relevant emission laws and regulations,shipping countries in the world are actively developing marine NOx reduction technologies.EGR and SCR technologies are more mature,but there are still some shortcomings,limited their widely application.Wet oxidation technology can simultaneously remove a variety of pollutants,the system is simple and reliable,it's operating costs are low,it has been the research hotspot on NOx removal in marine exhaust gas at present.However,the traditional wet scrubber is bulky and occupies more space in the ship.At the same time,the method requires a large amount of washing liquid to be stored on board,which affects the practical application of the wet oxidation and denitrification technology.The diameter of aerosol particles generated by ultrasonic atomization is extremely small.It can greatly enhance the gas-liquid mass transfer efficiency.This paper carried out denitrification experiments based on small ultrasonic atomization reaction device.The effects of several process parameters on NOx removal were investigated,such as different oxidants mist,gas flow,NaClO2 concentration,NO concentration,solution pH,reaction time,atomization power.The related reaction mechanism was discussed and analyzed.The results showed that,the oxidation efficiency of NO by NaClO2 mist was higher than that of NaClO and H2O2 mist.The carry mist gas flow affeted atomizing rate and droplet diameter,it had a dual effect on the NOx removal.With the increasing of NaClO2 concentration,the NOx removal rate continued to increase.With the increasing of NO concentration,the molar ratio of NO to NaClO2 increased continuously,while the NO removal rate decreased.During the pH value vary from 4 to 11,the removal rate of NO remained at a stable level.Only when the pH was increased to 12,the NO removal rate decreased significantly.NaClO2 mist exhibited a relatively stable and high NOx removal efficiency in a wide range of NaClO2 solution pH.The reaction time required for denitrification of NaC102 mist was short.When the reaction time was 0.27 s,the reaction can still be sufficiently carried out.It help reduce the size of reaction device.Ultrasonic atomization power can affect the NOx removal by affecting the atomizing rate.The parallel experimental results showed that the ultrasonic atomization denitrification technology can achieve high removal efficiency,the data were stable and reliable,and had a certain application value.Based on experimental research,this paper designs an exhaust gas comprehensive treatment system by ultrasonic atomizing NaClO2.The system can achieve coordinated removal of multiple pollutants.It produce less residual waste after denitrification,which convenient on-board storage.In this paper,denitrification energy consumption was calculated taking the 5S35ME-9B as an example.The results show that the operating power of ultrasonic atomizer is 2.78 kW,accounting for 0.06%of main diesel engine power.NaClO2 mist used for marine exhaust gas denitrification has the good feasibility and broad application prospects.