Control points of pre-cooling rate during LNG unloading

The focus and risk points in liquefied natural gas (LNG) terminal operation are LNG ship loading and unloading, especially the control of pre-cooling rate during LNG unloading. Most of LNG terminals on the world are not very experienced in loading and unloading, as well as control of pre-cooling rate. According to the available pre-cooling data of LNG ships in a LNG Terminal, the control and influence of pre-cooling rate during LNG loading and unloading and the operation safety in the unloading process are analyzed. In the unloading process, too high pre-cooling rate is a main reason for leakage at the flange of unloading arm quick coupler. According to unloading safety requirements and loading/unloading experience, the pre-cooling rate at the LNG Terminal is controlled at about 2 ℃/min, so that the entire unloading process is less affected and accidents can be effectively prevented or reduced.