Research On Ballast Water Allocation Optimization Model And Application For PGC-based Complex Ballast System Of Floating Cranes

As the key equipment for large-scale offshore operations,floating cranes are widely used in rescue and selvage projects,offshore wind power installation,offshore oil and gas development and other projects.With the development of floating crane in the direction of large-scale,automation and heavy-duty,the efficiency and safety of ballast system has become an urgent need at present.As a new ballast system,Pump,Gravity self-flow and Compressed air(PGC)composite ballast system can achieve high-efficiency ballast.It plays an important role in large-scale hoisting ship.Based on the analysis of the operation process of the PGC composite ballast system,the optimal model of dynamic allocation of ballast water and its optimal solution strategy were established,and the optimal ballast scheme database was developed to realize the real-time extraction and efficient formulation of optimal ballast schemes.The main research work of this paper includes:(1)Based on analyzing of the working principle and operation flow of the PGC complex ballast system,the hydrostatics of ships and optimal theories,the optimization model of ballast water allocation is built to minimize the ballasting time of floating cranes.In this model,the variations of water height levels in all ballast tanks are taken as the variables and the hull balance in the ballasting process is taken as the constraint conditions.Thus,an optimization model of ballast water efficient allocation for PGC-based complex ballast system in revolving floating cranes is done,which can provide theoretical model support for ballast water allocation optimization and its computer aided design.(2)Aiming to the characteristics of the optimization model,the solution strategy and model based on dynamic programming are studied.Engineering case analysis shows that PGC complex ballast system can decrease ballasting time by 84.3%because of its hardware advantages.Different ballast tanks have different sensitivity to different lifts.For example,No.4(S)ballast water tank is a key factor affecting ballasting time,which can be used to reduce ballasting time by nearly 30%.(3)Aiming at the problem of low efficiency in ballast scheme formulation,a ballast scheme design method based on ballast water allocation scheme database is proposed.The optimal solution database under different engineering conditions is obtained by optimizing model and solving algorithm.According to the key factors in the formulation of the scheme,the similar scheme can be retrieved as the ballast scheme of the new problem,so as to realize the real-time invocation of the optimal ballast scheme of the ship under different working conditions,which can greatly improve the formulation efficiency of the ballast scheme.(4)Finally,the hardware system design of the PGC ballast system is carried out,including the overall system composition,crane control system,ballast control system and ballast pipeline system,which can provide technical support for the engineering application of PGC ballast system.This paper can provide theoretical model and solution method support for ballast water allocation CAD of PGC-based complex ballast system,and provide technical support for dynamic computer control of ballast water allocation and automatic ballast system design,so as to improve construction safety and efficiency of floating cranes.