Handling LPG Components In LNG Plants

Natural Gas Liquid (NGL) recovery is an inherent part of most Liquefied Natural Gas (LNG) production trains. The requirement serves many purposes, such as adjusting the heating value of the product LNG, mitigating the freezing risks caused by specific intermediate and heavy components, and enhancing economic returns by selling NGL separately. In recent years attention has been paid to enhance the overall plant efficiency by integrating the refrigeration requirements of LNG and NGL sections.

This paper shows different heating value specifications in different regions of the world. Therefore, an LNG plant may be required to produce different grades of LNG products to meet the market demands. An ideal design of NGL facilities should be sufficiently flexible to allow operators to adjust the level of NGL recovery. In other words, operators can recover the maximum amount of NGL for sales or leave the NGL components in LNG to maximize its heating value.

This paper presents these NGL technologies which have been proven and implemented in existing LNG plants. The NGL process configurations are classified into five categories and discussed. Additionally, the paper uses a traditional scrub column as an example to highlight the process parameters available to operators for regulating the levels of NGL recovery.