The Simulation Test Research On Mechanical Behavior Of The Lifting Pipe System Of Deep-Ocean Mining

With the gradual shortage of land mineral resources, the marine extremely rich mineral resources are becoming the Strategic focus of the world's resource exploitation. The exploitation of deep-ocean mineral resources is becoming a great subject relating to the long-term development of China, one of the world's emerging economies.The lifting pipe system is the key component of deep-ocean mining system and it includes heave compensation device, rigid pipe, buffer, pump and hose. According to the engineering background of the deep ocean poly-metallic nodule mining and the technical scheme of China's ocean mining system, simulation test scheme of mechanical behavior of the lifting pipe system is proposed and the installation is built up in the lab. The simulation test system is able to perform the following tests:heave compensation, mechanical behavior analysis of the lifting pipe, hydrodynamics analysis of launching and retrieving process. The tests can validate the simulation research, provide boundary conditions and hydrodynamic coefficients for simulation research, and further can provide theoretical analysis and technical reference for the actual mining operations and sea trials.The main research achievements are as follows:1. A simulation test scheme of mechanical behavior of the lifting pipe system of deep-ocean mining which is convenient for performing in the lab is proposed. The mining ship motion simulator is basis of the simulation test system. A Stewart 6-DOF platform is chosen to simulate the motion of mining ship and all the simulation tests are performed upon the simulator.2. The functions of the simulation test system of mechanical behavior of the lifting pipe system is proposed. The three simulation test installation schemes of heave compensation, mechanical behavior analysis of the lifting pipe, hydrodynamics analysis of launching and retrieving process are proposed respectively. At last, the laboratory construction scheme based on the three tests is put forward.3. The sea wave is described and the response of the mining ship in the sea is simulated. According to the response of the mining ship and similarity principles, the motion parameters of the mining ship motion simulator is determined. The mining ship motion simulator is designed and built up to simulate the heave, pitch, roll motion and any desired motion of the mining ship. PID control is chosen. To determine PID control parameters, mathematics model of valve control cylinder drive system is established and is validated by simulation tests. Based on the math model, PID control parameters are adjusted in Simulink and are further readjusted during the tests to ensure better control effect. The motion tests are performed and the results show that the mining ship motion simulator can move under the predetermined attitudes of given periods and amplitudes and is able to simulate the motion of mining ship.4. The detailed installation scheme of heave compensation system with gimbal platform for pitch and roll compensation and electro-hydraulic system for active heave compensation is proposed and built up. PID control is chosen to complete the active heave compensation. PID control parameters are determined as the same way of mining ship motion simulator. The parameters are adjusted in Simulink first and then are further readjusted during the tests to ensure better control effect. Heave compensation tests under various sea conditions are performed and the compensation effects exceed expected goal. The influencing factors of heave compensation are found.5. The detailed installation scheme of hydrodynamics analysis of launching and retrieving process of mining system is proposed and built up. The simulation tests of water entry of the miner is carried out and the test results are agree with the simulation results.It is concluded that the simulation test installation provides a reliable and effective platform for mechanical behavior research of lifting pipe system of deep-ocean mining. The simulation test system of mechanical behavior of lifting pipe system is proposed and realized. Simulation tests of heave compensation and hydrodynamics analysis of launching and retrieving process are performed. The paper provides a new idea for research of mechanical behavior of lifting pipe system of deep-ocean mining.