Author(s): Sam Bash; Yifan Zheng
Linked Author(s): Yifan Zheng, Sam Bash
Keywords: Hydraulic transient analysis Liquified Natural Gas Loading arm valves Valve closure time
Abstract: A valve closing time sensitivity analysis of liquefied natural gas (LNG) loading arm XVs (on-off type control valves) and shoreline XVs is presented in this paper as a part of an LNG loading system hydraulic transient analysis. The objective of this study is to evaluate the LNG loading system response to these changes in terms of pressure and dynamic loads. A case study loading system is composed of two LNG storage tanks and one loading berth with three liquid loading arms and one hybrid arm. Specifically, the scope of this study includes the Current Base (assess any change to existing surge risk profile based on the current actual valve closure times and at different flow rates), and the Sensitivity Study (conduct sensitivity case, for different flow rates, valve closure times, and pump shut down intervals). After running different scenarios, a recommended closure time was proposed for the case study, which resulted with the maximum transient pressures under the pressure limits. The maximum dynamic loads are also provided for further investigation for piping design purpose. The transient analysis indicated that, to avoid load exceedance to the system piping for the current actual valve timing, the loading system should operate at a lower specific loading rate at about 80% of maximum flow rate; in order to operate the loading system at 100% loading rate, it is necessary to stagger the closing of loading arm XVs, such that total XV closure time is more than 2 seconds between two loading arm XVs when operating any three out of four loading arms, in order to have transient loads within limit.
Year: 2025