Parallel Loading Systems
The overall motivation in developing the HiLoad Parallel Loading System (PLS) was to move the LNG “delivery point” at conventional LNGCs (midship manifold) closer to a ship shaped FLNG and thereby reduce the length of the LNG flexibles which again will reduce the pressure drop and boil-off gas. At the same time the system shall keep the LNGC safe in position a distance away from the FLNG at any time.
A distance of 100 m is selected as the “safe distance” between the FLNG and the LNGC during the LNG offloading operation, with the purpose of keeping the LNGC’s position within the DP operating envelope, using the thrusters and DP system on the HiLoad LNG. The LNGC rudder and main engine in constant “Dead Slow Ahead” mode is used to provide heading control.
DP Side Loading Systems
The HiLoad DP Side Loading (DSL) system has been developed to overcome the challenges given for traditional side by side systems. The conventional LNGC is maneuvered towards the FLNG by use of the DP system on the HiLoad LNG, removing the need for tugs. The heading control is enabled using the LNGC rudder and main engine in constant “Dead Slow Ahead” mode.
Simulations of the DP station keeping and heading control capability of the HiLoad LNG docked to a LNGC have been conducted. A large LNGC was used in the simulations, representing more than 95% of the world-wide LNGC fleet in operation.
Simulations were performed for several conditions, specified by a wave spectrum, wind spectrum and current speed and their directions.