Research On The Pressure-maintaining System For Methane Hydrate Transfer Device

Methane hydrate has been found in deep sea and tundra in the past 20years, and identified as a new alternative clean energy resource. Methane hydrate only exists in high-pressure and low-temperature, and depressurization could cause volume expansion and destroy its structure. After sampling the sediment with methane hydrate from deep sea to ship at in-situ pressure, methane hydrate would be destroyed when transferring to lab because of the lack of pressure core transfer devices. This thesis is aimed at providing a pressure maintaining solution, which is a key subsystem of pressure core transfer devices. There have been many papers in sediment sampling at in-situ pressure, but how to transfer the sediment from ship to the lab without pressure loss is still a problem to be solved. And this thesis is designed to provide a solution to the problem.This thesis can be divided into six chapters as follows.Chapter ? introduced the background of the gas hydrate sampling and transferring technology, and illustrated the research purpose and contents at the end of the chapter.Chapter ? expounded components of the pressure core transfer device, which the pressure maintaining system was designed to be compatible with, and illustrated its working process. Then it introduced the overall design of pressure maintaining system after comparing some common measures to maintain pressure and combining the needs of pressure core transfer device.Chapter ? researched the key component of pressure maintaining system, which is the accumulator. It deduced the mathematical model of accumulator, analyzed the relationship between structure parameters and the ability of absorbing capacity.Chapter ? used AMESim to analyze the absorbing capacity of pressure maintaining system, discussed how some working parameters would influence the simulation results. With the simulation results, it would be easier to design the system with better performance.Chapter ? described the hardware prototype of the pressure maintaining system. And some experiments were conducted to test the function of the prototype.Chapter j? illustrated a summary about all the research work and gave a prospect about the further research.