Device Development And Control Technology Of Deep Sea Mining Sediment Plume

The deep sea floor is rich in polymetallic nodules and other mineral resources with abundant reserves and high quality.All maritime powers are increasing their investment in the exploitation of deep sea mineral resources.However,research shows that deep-sea mining will cause irreparable damage to Marine ecology,which seriously restricts the commercial exploitation of deep-sea mineral resources.Among them,the deep-sea harvester operation has a particularly obvious environmental impact caused by the disturbance of sediment plume,which has a great damage to the seabed ecological environment and biodiversity,seriously interferes with the normal operation of sonar,deep-sea camera,submarine photography and other systems,and also affects the frequent failure of harvester due to the infiltration of particles.However,there is no effective method to inhibit sediment diffusion.In this context,a method of precise suction and solid-liquid separation of sediment disturbed by harvester is proposed in this paper,so as to effectively inhibit sediment diffusion.Firstly,based on Euler’s solid-liquid two-phase flow model,the characteristics of sediment dispersion disturbed by harvester head and track were analyzed in view of the harvester model developed by China Ship Scientific Research Center.Based on this,the sediment plume suppression device was developed,and the structure and size of suction port were optimized by numerical simulation.The influence of suction speed on particle capture rate was analyzed by simulation.The sediment suppression device test system was built,the sediment suction test scheme was proposed,and the simulation analysis results of particle capture rate were verified.The main work and conclusion of this paper are as follows:(1)This paper summarizes the development equipment of deep-sea mineral resources,the characteristics of seafloor sediments and their effects on deep-sea environment,the theory and simulation of solid-liquid two-phase flow,and points out the deficiencies of the current methods and equipment of sediment plume suppression.(2)Based on Euler’s theory of solid-liquid two-phase flow and Fluent,a fine numerical simulation model of harvester head and track was established by using fluid dynamics simulation software Fluent,and the influence of harvester speed on the diffusion characteristics of the disturbed sediment of harvester head and track was analyzed in detail,including diffusion speed and volume fraction.(3)According to the characteristics of sediment disturbance and diffusion,a sediment plume suppression device was developed,and a numerical simulation model of suction nozzle turbulence was established.Based on the characteristics of suction range and pipe pressure,the structure and parameters of suction nozzle opening Angle,opening size and inner diameter of suction circle were optimized.A parallel discrete phase simulation model of sediment discharge and suction was established to analyze the effect of suction speed on sediment capture capacity.(4)The sediment plume suppression device test system was built,the sediment suction test scheme was proposed,and the test error was analyzed.The influence of suction flow rate,suction interval and simulated discharge flow rate on the sediment suppression effect was tested,and the accuracy of the simulation results of sediment capture rate at the suction port was verified.