Mark E. Ehrhardt

Shipboard Reliquefaction for Large LNG Carriers

Abstract Shipboard reliquefaction technology has been applied for the first time on the new Q-Flex and Q-Max liquefied natural gas (LNG) carriers to enable the use of slow-speed diesel engines to achieve higher efficiency and lower emissions than conventional LNG carriers. Qatargas 2 and ExxonMobil have qualified this new reliquefaction technology for use on the new ships and have overseen the development, construction, and operation of the reliquefaction systems. Further details of the design, qualification and development activities, and operating modes of the reliquefaction systems for the first Q-Flex and Q-Max ships are discussed in this paper.

Subsea LNG Transfer System

Many offshore liquefied natural gas (LNG) import terminal designs have been proposed by industry in the last several years. Most base-load offshore LNG import terminals currently under development utilize either a bottom-founded structure, such as a gravity base or a jacket structure, or a floating structure such as a moored ship-shape hull. In either case, LNG transfer from the LNG carrier (LNGC) to the LNG import terminal is performed through side-by-side offloading. LNG transfer is accomplished with loading arms equipped with constant motion swivels and a wire-guided connection system. Side-by-side offloading has acceptable availability for mild environmental conditions. However, when applied in more severe environments, this type of LNG transfer system can limit the terminal throughput because of low berthing and offloading availability.