(30c) Cost Effective and Practical Ngl Stripping Processes

Nitrogen dilution has been widely used to reduce imported LNG High Heating Values (HHV). However, pipeline gas specification limits place considerable restriction on nitrogen injection's ability to adjust regasified LNG HHV and component requirements. This process also requires high operating costs in nitrogen generation.

While securing LNG supply through long-term contracts will continue to play an important role, acquiring spot LNG from scores of foreign producers will also be a popular practice. Since imported LNG has wide compositional variations, many LNG receiving terminals need to have the heating value lowered by heavy component (C2+) stripping. Natural Gas Liquid (NGL) stripping from LNG is more versatile than nitrogen injection and can generate additional revenue if suitable demand for higher value extracted components exists.

Many NGL stripping processes have been developed and are commercially available. This paper presents an overview of several processes and discusses their advantages and limitations.

This paper proposes a new NGL stripping process that integrates the Boil-off gas recondensing system, low pressure feed LNG and reflux of the stripped natural gas stream. Operability and flexibility with respect to inlet LNG feed variations is evaluated.