Study Of The LNG-FSRU Mooring System

As a new type of offshore petroleum engineering equipment,LNG-FSRU effectively solves many shortcomings of land-based natural gas receiving stations.The mooring system can make LNG-FSRU moored in the working sea for long time.Accurately predicting the movement characteristics and mooring forces of LNG-FSRU with different loading conditions under the combined action of wind,wave and current.It can ensure the safety of the mooring system.By this way,the LNG-FSRU has long-term,high-efficiency and safe production.This paper takes the 350000m~3 LNG-FSRU as the research object.The study according to the following ideas:Establish LNG-FSRU physical model;Divide the grid to obtain the LNG-FSRU hydrodynamic calculation model;Analysis the ship motion response characteristics and tank sloshing in the frequency domain analysis;Predict the mooring force,motion response and equivalent stiffness curve of the mooring system.The specific work is as follows:(1)Briefly introduce the basic theory of LNG-FSRU mooring system type and wave load calculation;Define the key points of the design of tower soft yoke single mooring system;Introduce the frequency domain calculation and time domain calculation theory and calculation steps of hydrodynamic calculation software AQWA.(2)Establish the LNG-FSRU hydrodynamic model,using AQWA-LINE to calculate the motion response characteristics of LNG-FSRU under different loading conditions under wave loading,analysis the characteristics of LNG-FSRU motion response.Different loading states against LNG-FSRU effects the motion response of LNG-FSRU;further verify that the tank sloshing resonates with the swinging motion of the LNG-FSRU.(3)Establish a coupled hydrodynamic model of the LNG-FSRU mooring system and set up the wind wave current load.The AQWA-DRIFT was used to study the motion response of LNG-FSRU with different loading states and the maximum mooring force of the mooring system under different combinations of wind and wave flow conditions.What's more,the longitudinal restoring force curve of the mooring system of soft steel arm was studied.