Offshore Structure Assembly Using Carrier Vessel Arms
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The construction of offshore structures with wind turbines, such as spar-type floating structures, often requires the use of expensive crane vessels to install towers, which is challenging due to wind and wave conditions, and involves complex and costly processes for assembling and mooring.
Innovation Solution
A method of constructing offshore structures by separating the upper and lower structures, where the lower structure is kept upright in the water and the upper structure is moved onto the carrier vessel using arm-shaped structures, allowing for the integration of the two without a crane vessel, using ballast adjustments and winches for vertical movement, and enabling safe mooring without the need for crane vessels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a crane vessel is used to install the tower on the float, then the tower can be installed on the upper portion of the float, but the construction cost increases and the operation becomes more complex
Solution Approach 1:
The offshore structure is divided into an upper structure (tower with wind turbine) and a lower structure (float), which are manufactured and transported separately. This segmentation allows each component to be handled independently, eliminating the need for crane vessels during assembly at the installation site.
Solution Approach 2:
A carrier vessel equipped with special arm-shaped structures serves as an intermediary transport and positioning device. The carrier vessel carries both the upper and lower structures and uses its arms to lower the upper structure onto the lower structure, replacing the traditional crane vessel function.
2Ease of manufacture
If the tower is hung down by a crane vessel, then the tower can be installed on the float, but the tower and float swing due to wind effects
Solution Approach 1:
The carrier vessel performs the installation function itself using its own arm-shaped structures, eliminating the need for external crane vessels. The carrier vessel's self-contained mechanism allows controlled lowering of the upper structure without introducing additional swinging problems.
3Ease of manufacture
If a crane vessel is used for tower installation, then the tower can be positioned on the float, but the construction cost increases
Solution Approach 1:
The carrier vessel is designed with multi-functionality, serving as both a transport vessel for the upper and lower structures and as an installation vessel with arm-shaped structures for positioning. This eliminates the need for separate crane vessels, reducing overall construction costs.
4Ease of manufacture
If the upper structure is carried separately and installed using a crane, then the tower can be mounted on the float, but the operation becomes more complex and time-consuming
Solution Approach 1:
The upper and lower structures are prepared and transported to the installation site in advance using the carrier vessel. The carrier vessel's arm-shaped structures are pre-positioned to receive and lower the upper structure, enabling rapid assembly without waiting for crane vessel arrival or complex positioning operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for safe and cost-effective construction and mooring of offshore structures without the need for crane vessels, reducing installation complexity and costs, and enabling easier handling of large structures in challenging weather conditions.
Implementation Method 1
a carrier vessel (20) including a ballast tank and a pair of arm-shaped structures (23) protruding from an end portion, which is a bow or a stern, of a hull of the carrier vessel (20) in a bow-stern direction
Implementation Method 2
an in-water keeping step of keeping part or whole of the lower structure (12) in an upright standing state in water
Data Source
AI summary
An offshore structure is separated into an upper structure and a lower structure. Part or whole of the lower structure is kept in an upright standing state in water. The upper structure is moved to above the lower structure kept in the upright standing state. A uniting step includes one or both of raising the lower structure to arrange the lower structure on a lower side of the upper structure and lowering the upper structure to arrange the upper structure on an upper side of the lower structure by submerging part of a carrier vessel on which the upper structure is mounted while being held by a pair of arm-shaped structures of the carrier vessel and integrating the lower structure with the upper structure. In this way, an offshore structure is moored safely at an offshore installation site without using a crane vessel.