Optimal sizing of small scale liquefied natural gas storage using numerical cascade pinch analysis

Abstract

Increasing demand for liquefied natural gas (LNG) at the inaccessible area through pipeline has provided a solid platform for the emergence of new small scale LNG (ssLNG). The key challenges related to the ssLNG business are relatively expensive supply chain due to the diseconomy of small scale and meeting the security of supply and demand with limited supply alternatives available. Nevertheless, the market has increasingly become the preferred delivery method for natural gas (NG) because LNG can be produced at remote locations and distributed to end-users conveniently. To date, extensive works with a variety of objectives have been developed in an attempt to optimise the ssLNG supply chain in terms of conversion, transportation, and utilisation yet an optimal synthesis of LNG for small scale market has not been adequately investigated. The activity of loading and unloading of LNG in supply port terminals needs sufficient capacity of LNG storage tank. Designing an adequate capacity is necessary in order to secure reliable supplies of LNG as well as to offset fluctuations in the supply and demand of LNG. This work aims to ease industrial planner to design an optimal capacity of ssLNG storage by implementing a well established numerical cascade approach based on Pinch Analysis technique and proposed a new numerical approach of small scale LNG-Storage Cascade Analysis (ssLNG-SCA). Based on the proposed tool, the minimum amount of LNG supply for operation has been reduced from 2,100 m3 to 1,400 m3 due to the stored amount of excess LNG supply (700 m3) during start-up with the existence of ssLNG storage tank. The developed ssLNG-SCA in this work shows a significantly reduced storage capacity from 24,000 m3 to 6,300 m3 thus eliminate the need to provide for a larger and higher price of LNG storage tank. The storage offers delivery of NG to virtual trading hubs to meet end-user demand which inaccessible to the high-pressure pipeline.