Study On Cathodic Protection Design Technology Of Ship Internal Tank

Erosion of ship liquid tanks is the main factor which affects life of inshore engineering and conveyance ships. Moreover erosion of ballast water tank is the most notable. At present measure applied abroad is the method that cathodic protections (sacrificial anode or additional current) add up to protective coating. Because of alternation of dry and wet in ballast, its erosion is more intense than other structure; In addition, inside structure of ballast water tank is very complex, shield effect to protective current also becomes a key problem in cathodic protection design.Numerical simulated calculation based on boundary element method promoted the development of modern cathodic protection technology. This thesis takes into account effect of cathodic protection parameters and factors to ballast water tanks' protection on the basis of criterion's request on hull cathodic protection. Applying the way of numerical simulated calculation, this thesis put forward a cathodic protection design project for ballast water tanks, solved the problem of shield effect and realized optimized design.The following work has been done for completing the thesis. Writing sacrificial anode design calculation program based on DNV cathodic protection design; Establishing calculation model of typical ballast water tank and dispersing the model for the first step, writing mesh dissection former handle program by FORTRAN and VB, getting model first-step dispersing information of cells and nodes; Mesh dissecting the model and getting information of mesh cells and nodes, calculating the distribution of protective potential and protective current density on bulkhead and structures and sacrificial anodes consuming state by numerical simulated calculation; Using the result of numerical simulation calculation and BP Artificial Neural Networks arithmetic, writing program to imitate the non-line relation between distribution of sacrificial anodes and junfangcha of protective potential; Writing program to optimize sacrificial anodes distribution according to Genetic Algorithms and validating the feasibility of this method by example. Finally relevant software is developed.The project put forward in this thesis is the same with cathodic protection design of other type liquid tanks .It also has reference value for cathodic protection design of hulls in large and medium-sized ships.