Deep-sea Mining Passive Heave Compensation System Parameter Design And Simulation Study

Heave compensation system (HCS) is the essential equipment which guarantees the normal operation of hydraulic lifting deep sea mining system. At present, the researches on heave compensation system of deep sea mining system are not too many, and those researches are exclusively focusing on the active compensation system which needs power supply and has high compensation precision. Actually, as the compensation precision requested for HCS of deep sea mining system is not high, the study of the simple passive compensation system with no power consumption is reasonably meaningful.A passive heave compensation (PHCS) with accumulator is proposed in the light of 5000m deep sea poly-metallic mining system of China. The study methods which include mathematical simulation and multi-field co-simulation and modeling are comprehensively used; the following which are researched in the working process of mining system contain: the main influence factors, the control effect, the response of system in the condition of random wave, the influence on system caused by the access methods of accumulator, the analysis of the reason why compensation efficiency can not be improved ulteriorly, and exploratory study on improving system. The main results and conclusions are as following:1. According to the work condition of heave compensation, the response of mining vessel and the random wave in grade four ocean condition are obtained by numerical simulation, a PHCS with accumulator is presented, working principles and characteristics of PHCS are analyzed, main parameters of system are designed;2. Mathematical model in the working process of PHCS is built, the main influence factors are discussed, design and selection of corresponding parameters are completed, and control effect of the system is researched. The results indicate that the PHCS with the parameters that the volume of accumulator is 20 m~3 , the diameter of pipe is 0.05m and the length of pipe is 0.5m, has fairly good compensation effect in the concentrated frequency of the grade four ocean condition and the compensation efficiency is more than 80% in the condition of random wave.3. Methods of multi-field modeling and simulation are used, the general simulation model of PHCS is built, access methods of accumulator to system are discussed. The results indicate that the superior plan is that firstly insert the lord, then accumulator which is adopted by preliminary precewise pressurization; the compensation process of PHCS is analyzed, the results indicate that compensation capability of PHCS can be improved by adjusting pressure changes of accumulator.4. A kind of improved PHCS with throttle valve is presented, the compensation characteristics in different ocean frequency of the new system are studied; the results show the PHCS with throttle valve whose open degree is fixed has fairly good inhibitory effect on ocean wave of low frequency.5. A testing system which is based on LabVIEW is built for the performance of accumulator in the process of heave compensation. The influence which the accumulator acts on hydraulic system is studied. The experimental results have validated the accumulator's effects on heave compensation system.