(31b) Gas Interchangeability – Quality Issues and Solutions for US LNG Terminals

Currently, there are a number of liquefied natural gas (LNG) receiving and re-gasification terminals under planning or construction in the United States (US). The terminal owners/operators are looking for ways to build flexibility into the terminal design to be able to receive imported LNG from different sources in the world. Gas interchangeability is one of the key issues with multiple sources of LNG that terminal design must address as the re-gasified LNG must meet certain gas quality to be delivered to a specific pipeline.

Gas originating from different parts of the world varies in composition. This variation, among other things, is in the level and type of hydrocarbon components. Such differences can create gas quality issues for end users as the non-methane hydrocarbons may burn too hot at the burners (producing higher NOx emissions) or may cause liquid drop out when the pressure is reduced for local distribution or so called city gate.

The pipeline gas quality requirements in the United States vary region by region due to the traditional sources and users in the region. Solutions to meeting pipeline gas quality can also vary due to the available industries and infrastructures in the region. This paper discusses various regional pipeline and regulatory requirements and how the LNG re-gasification terminal in a specific region, importing LNG from various parts of the world, can utilize different methods suitable for the region, as well as economically achieve the gas quality requirements.