NGL PRODUCT QUALITY ISSUES AND TREATMENT OPTIONS FOR LNG RE-GASIFICATION TERMINALS

摘要

There are currently a number of liquefied natural gas (LNG) receiving and re-gasification terminals under planning or construction in the United States (US). The terminal owner operators are looking for ways to build flexibility into the terminal design to be able to receive imported LNG from different sources. Heating value (BTU) control is one of the key issues with multiple sources of LNG that terminal design must address. US based terminals are required to meet a heating value of 1100 Btu/SCF (GCV) or less, pipeline gas specification. To achieve this BTU levels from many imported LNG sources containing higher than 1100 Btu/SCF, Natural Gas Liquids (NGL) extraction is considered as a solution.In the NGL extraction process for the imported LNG terminal, there are quality issues that also need attention in the terminal facility design. For example, the sulfur contaminants that contained in the imported LNG feed gets concentrated while processing the NGL and finds its way into the extracted NGL products (Mixed Y-grade or Ethane and other product if fractionated). This is a concern for meeting liquid product specification such as copper strip # 1 test, when LNG source contains sulfur contaminants. The selection of a sulfur removal processes for the NGL product needs numerous technical, economic, and environmental considerations.This paper discusses NGL product specifications requirements for a Gulf-Coast LNG terminal and reviews the challenges in meeting these requirements. The paper compares key process design alternatives to treat the NGL and ethane products and provides guidelines for the selection in meeting product quality specifications.