Study Of Urea Storage And Injection Unit Of Marine SCR System

At present, the threat of air pollution on human life has become increasingly become prominent.with the substantial increasing in the number of ships in the world, air pollution caused by ships can not be ignored. In1997, the International Maritime Organization (IMO) add MARPOL Annex VI in the Conference of the Parties,the Convention aims to reduce air pollution caused by ships. NOxis the major gaseous pollutant generated by the ship, NOx form photochemical smog and acid rain.In2016, the International Maritime Organization (IMO) will enforce stricter tier3standard of the MARPOL Convention Annex VI about NOx-Improving fuel injection pressure of Marine diesel engine and reducing the combustion temperature can reduce the NOx content in the exhaust, but these techniques can only reduce NOx content marginally. At present, only two kinds of technology can reach the tier3standard of the2016Convention which is post-processing of diesel exhaust and exhaust gas recirculation technology. After reading a lot of information we compare the two technologies applying to the ship, the thesis use the SCR system (Selective Catalyst Reduction) to make NOx in the exhaust convert to nitrogen with catalyst for reducing the NOx content.After analyzing working principle of the SCR system, by means of comparing and analyzing various kinds of reducing agent, the thesis chose urea solution with the concentration of32.5%as the reducing agent in the system reaction.Taking5S35ME-B diesel engine for example, the thesis utilize calculation formula of gas mass flow given by IMO to ascertain quantity demanded of the urea, and then propose the design plan of the urea storage tank. Referring to the SCR technology of Coal Power Plant, we design ship SCR injection system with partitioned type, and display the results by the figure. The key technology of the urea injection system is mixability of NH3and exhaust and gauging accurately and supply of NH3. This thesis uses the formula to prove its feasibility of utilizing a solenoid valve to supply the urea solution accurately, and set a static mixer to ensure a mixture of NH3and exhaust.The SCR technology of marine diesel engine is a practical new technology. The thesis establishes the foundation for the development of SCR technology,. This system also increases fuel economical efficiency of the diesel, and makes the ship to reduce its damage to the environment while driving social growth.