Concept design of topside process for offshore LNG bunkering terminal

Abstract

This study proposes the concept design of offshore LNG bunkering terminal that would play a critical role in the LNG supply chain for LNG-fuelled ship propulsion. It is recommended that the bunkering terminal should be located offshore for the sake of improved safety, rapid LNG distribution and space availability in the vicinity of the port. LNG bunkering terminal should satisfy the various design requirements to perform its functions. The principal functions of the offshore installation include importing LNG from LNG carriers, storing it temporarily, and exporting the stored LNG to LNG bunkering shuttles or LNG-fuelled ships. One of the most critical issue is the treatment of Boil-off gas (BOG) generated from several sources in the storage systems of the bunkering terminal. Several methods of handling BOG seem feasible. The employment of a pressure vessel is considered the most effective and safe alternative. As a case study, the concept design for Busan port is carried out by analyzing the statistics of visiting ships, estimating the required LNG consumption, determining the hull structure and anticipating the design cases. After design basis is established, fundamental engineering calculations are performed to satisfy the cargo operations of LNG import, LNG storage, and LNG export. The results obtained include the number of target LNG-fuelled ships and LNG bunkering shuttles, LNG demand, capacity and type of hull structure for the bunkering terminal. To estimate the process specifications and equipment features of the topside systems, the BOG generated from several sources is calculated. Dynamic process simulation is also conducted to estimate the design pressure of the pressure vessel in Busan.