| Marine diesel engine has become a major source of air pollution in port areas along the coast,in order to reduce exhaust pollution from ships on the environment,the Yangtze River Delta region in China has run a pilot ship emissions control area.In this context,the research of the ship exhaust after-treatment devices is important.Therefore,a set of dust removal and denitrification dual function ship SCR system ceramic catalytic-filter is designed on the basis of relevant studies.First,the structure of the ceramic catalytic-filter is verified by design criteria proposed by Tian Guishan,and the result is correct;And,the optimum size of the ejector combination is determined by simulation method:the nozzle diameter and blowing distance equal to 6mm and 60mm,it has the best ejector effect,and the entrainment ratio is equal to 1.93 at this time.Next,the forward flow state of gas is analyzed by FLUENT software,the distribution of radial filtration velocity on the outer surface of the differently shaped ceramic filter is obtained,when the dead end having a diameter of 40mm,the gas has the best forward flow uniformity;And,cleaning process is analyzed by transient simulation,the conclusions are obtained:the cleaning process is divided into eight stages,at about 3.2s after the start of cleaning,it recovers to a stable state of the forward filter.When the dead end having a diameter of 30mm or 40mm,the overall length of the ceramic filter have a greater cleaning pressure.Finally,in order to be able to simultaneously play the denigration and dust removal function at the same time,the structure of the ceramic filter and the ejector is optimized.And,it leads to the following conclusions:when using optimization method that expanding the ejector outlet alone a straight line,it has a poor result of improving the reverse ejector effect,so,it is decided to use the dual structure optimization method of increasing the thickness of the ceramic and prolonging the ejector. |
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