大型LNG接收站反输装船方案研究

Research on Ship Re-loading Scheme for Large LNG Receiving Terminals

随着国内LNG贸易迅速发展,在新建或已建LNG接收站增加反输装船功能,可更好地保障周边天然气的供应。LNG反输装船可利用已有的常规罐内泵,也可增设专门用于LNG装船的大流量、低扬程装船泵,两种方案各有优劣,需结合LNG接收站自身特点进行选取。结合工程实例,对反输装船的方案选择、工艺流程、码头方案、反输装船操作步骤、减少BOG的操作方式进行探讨。增设专用LNG装船泵,可兼顾远期反输大型LNG运输船,对接收站气化外输功能影响较小,且BOG产生量远低于利用常规罐内泵反输装船。为降低反输船内的BOG量,保持船舱内LNG的过冷条件,返装船船舱压力大于储罐压力是较优的操作方式。在实际运行中尽量避免同时进行卸船和反输装船操作。

With the rapid development of domestic LNG trade,adding the function of ship re-loading at newly built or existing LNG receiving terminals can better guarantee surrounding supply of natural gas.LNG ship re-loading can use the existing conventional in-tank pump,or add a large-flow,low-lift loading pump specially designed for LNG shipment. Both schemes have their own advantages and disadvantages and they need to be selected in combination with the characteristics of the LNG receiving terminals. Combined with engineering examples,the options for the ship re-loading schemes,the process flow,the jetty plan,the ship re-loading operation steps,and the operation mode of reducing BOG are discussed. The addition of special ship-loading pumps can take into account the long-term re-loading of large LNG carriers,which has less impact on the gasification and external transmission function of the terminal,and the BOG rate is much lower than that of the ship re-loading using conventional in-tank pumps. In order to reduce the amount of BOG in the ship and maintain the overcooling condition of the LNG in the ship cabin,the pressure of the ship’s cabin is greater than the tank pressure is a better operation mode. It should be avoided to conduct ship unloading and ship re-loading at the same time.