Study On Metal Corrosion And Coating Failure Of Ballast Tank Based On Inert Flue Gas Deoxygenation Method

The invasion of aquatic organisms caused by the discharge of ballast water posed a serious threat to marine ecological security.In order to address the ecological hazards caused by the discharge of ballast water,the International Maritime Organization(IMO)adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments(hereinafter referred to as the Ballast Water Convention)in 2004.In2017,the IMO approved the amendment to Section B B-3 of the Ballast Water Convention,which specified the implementation time for different standards of the Ballast Water Convention.The technology of treating ship’s ballast water with inert flue gas deoxygenation method has been experimentally validated and proven to effectively kill most aquatic organisms in ballast water,meeting the standards of the Ballast Water Convention.However,due to the treatment technology changing the dissolved oxygen concentration and p H value of the ballast water,the metal/coating system of the ballast tank faces a new corrosion system.Therefore,it is increasingly important to study the impact of this treatment technology on metal corrosion and coating failure in the ballast tank.This article focused on the inert flue gas deoxygenation method for treating ship ballast water,and conducted the following research:(1)This article reviewed the current research on inert flue gas deoxygenation method for ballast water treatment,and theoretically analyzed the deoxygenation mechanism and biological killing mechanism of this technology.It showed that the biological killing mechanism of this technology was not influenced by a single factor,but was the result of a comprehensive effect of multiple factors.(2)Through static immersion corrosion tests in the laboratory,using weightlessness and surface morphology observation methods,the effect of inert flue gas deoxygenation ballast water treatment technology on the corrosion of marine carbon steel was studied.At the same time,the influence of salinity changes on the corrosion of carbon steel in ballast water treated with inert flue gas deoxygenation method was explored.The study showed that the corrosion of carbon steel in seawater treated with inert flue gas deoxygenation method was significantly reduced.Both the corrosion rate of carbon steel and the severity of carbon steel corrosion significantly decreased.(3)Through static immersion corrosion tests in the laboratory,using surface morphology observation method,the effect of inert flue gas deoxygenation ballast water treatment technology on the coating failure of ballast tanks was studied.At the same time,the influence of salinity changes on the coating failure of ballast water treated by inert flue gas deoxygenation method was explored.The study showed that the inert flue gas deoxygenation ballast water treatment technology can effectively slow down the process of coating failure of ballast tanks.(4)Hydraulic cavitation sterilization technology can synergistically work with the technology of treating ship’s ballast water with inert flue gas deoxygenation method to enhance the sterilization effect.Therefore,based on Solidworks Flow Simulation,this article also numerically simulated the cavitation flow field of a Venturi tube under different inlet mass flow rates,exploring the impact of changes in inlet mass flow rate on the flow velocity and turbulent kinetic energy inside the Venturi tube.The study showed that as the inlet mass flow rate increased,the fluid velocity and turbulent kinetic energy inside the Venturi tube significantly increased,and the distribution range of high-speed jets was wider,while the distribution range of turbulent kinetic energy continued to expand.