Dilution Method To Replace The Study Of Ships' Ballast Water

The paper discusses the design of the "Dilution" BW (i.e. ballast-water) system which is applied on ship.Firstly, the paper introduces the environment pollution, which results from the harmful Aquatic organisms and pathogens in BW. Then it introduces the worldwide feedbacks for the pollution. IMO (International Maritime organization) has been actively engaged in seeking a solution to this problems, which developed and issued a set of Guidelines and International convention for the control and management of ship' ballast water and sediments. At the same time, IMO also has been studied the current BW management methods, some of which are applied on ship and another of which are under studying. Among those BW management methods, only the exchange of BW at sea is accepted by IMO. There are three ways of exchanging BW at sea, namely "Sequential" "Flow-through" and "Dilution". "Dilution" remains the advantages of the "Flow-through" process, but it avoided the issues of over pressuring and accumulation of water on deck. People paid close attention to it recently. So "Dilution" will become better exchange of BW at sea in the future.Secondly, the paper has done some researching on the problems emerged when the "Dilution" BW exchange is applied on board, on the base of which the design principles of "Dilution" BW system and equipment are brought forward, emphasis on discussing water power computation of the ballast water system. Used the finite element method computation pipe network resistance thus obtains the ballast water system the line pressure distributed situation. The paper also has carried on the computation to the ballast tank hydraulic loss and has provided the theory basis to the ballast pump optimized design. The overpressure to the ballast tank has been carried on the discussion. The paper also gets the function between the rated flow and the rated pressure of the pump on ships whose BW pipe net is uniform and line is different, which provides a new method for the selection of BW pump.Last, through design of ballasting system of 1700 TEU containership, the paper offers the references for the design of BW system when applying theDilution BW exchange, and it is practical.