Environmental and Economical Evaluation of Integrating NGL Extraction and LNG Liquefaction Technology in Iran LNG Project

Abstract

The combination of changing global markets for natural gas liquids (NGL) with the simultaneous increase in global demand for liquefied natural gas (LNG) has stimulated an interest in the integration of NGL recovery technology with LNG liquefaction technologies. Historically, the removal of “heavy” or high-freezing-point hydrocarbons from the feed to LNG plants has been characterized as “gas conditioning” and achieved using one or more distillation columns. While some attempts to provide reflux to the distillation columns marginally enhanced NGL recovery, little emphasis was placed on maximizing NGL recovery as a product from the LNG process. As such, the integration of the two processes was not a priority. Integrating state-of-the art NGL recovery technology within the CoP LNGSM Process1, formerly the Phillips Optimized Cascade LNG Process, results in a significant reduction in the specific power required to produce LNG, while maximizing NGL recovery. This corresponds to a production increase in both LNG and NGL for comparable compression schemes as compared to stand-alone LNG liquefaction and NGL extraction facilities. In addition, there are potential enhancements to the overall facility availability and project economics and environmental impacts using the integrated concept. This integrated concept has been applied to three ongoing international NGL/LNG projects using the CoP LNG Process in Iran LNG project. In this respect, simulation has been performed in THERMOFLEX software. Moreover, thermo economic analysis has been applied for economic and thermodynamic analysis of base and integrated cases through computer code has been provided here. Finally, the base and integrated case have been evaluated and comprised in view of thermodynamics, economics and environmental impacts.