INTEGRITY, SAFETY AND EFFICIENCY IN LNG TRANSFER-IMPACT OF EMERGENCY SHUTDOWN AND RELEASE OPERATIONS

摘要

Caused by the global increase of demand for natural gas the interest in offshore liquefaction, transport and re-gasification grows rapidly. The installations that are presently developed are in essence copies of the onshore systems that are already many years in operation. However, the fact that the installation is installed on a ship imposes limitations and leads to special system requirements. An important issue is that offshore offloading systems, in contrast to ship-to-shore offloading, have to function under harsh sea conditions. Systems should be flexible to deal with the ships moving relative to each other and extreme cases may require instantaneous disconnection. Besides, the offloading system has to transfer LNG at the highest possible rate, which requires that the equipment has to withstand high flow velocities and pressures. At present ship-to-ship transfer systems are being developed that apply loading arms or flexible pipes and hoses. Such systems have already been successfully operated in a number of cases. A question that remains appropriate continuously is whether the integrity of such a system can be guaranteed under all circumstances and in all configurations. This is of particular relevance in corrugated hose/pipe systems, where due to the inner profile local pressure and velocity fluctuations occur near the hose/pipe wall, a potential cause for bubbles to form. These vapor bubbles can affect the flow behavior and impose operational complications. The research described enables development of tools for the prediction of safe operation conditions and optimization of the LNG transfer and transport systems.