Crane Sheave Block Dynamics for Monopile Up-Ending
Solution Overview
Problem
Current methods for up-ending large monopiles, such as those used in offshore wind turbine installations, face challenges in controlling the lower end of the structure during rotation and often require synchronized operation of multiple cranes, which is impractical for many vessels due to asymmetric loading and space constraints.
Innovation Solution
A crane system with a base structure, slew bearing, and three main hoisting systems, each comprising a hoisting cable, sheave block, and winch, where the sheave blocks are pivotable and arranged side-by-side to allow for controlled rotation of the monopile, reducing torsion loads and enabling efficient up-ending without the need for synchronized crane operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two cranes are used to lift both ends of the monopile for up-ending, then control of both ends is improved, but device complexity and synchronized operation requirements increase
Solution Approach 1:
The patent combines the functions of two separate cranes into a single crane system. The crane housing integrates two hoisting systems with sheave blocks arranged side-by-side, allowing one crane to perform the up-ending operation that previously required two cranes, thereby eliminating synchronized operation requirements while maintaining control over both ends of the monopile
Solution Approach 2:
The crane's hoisting system is segmented into multiple independent hoisting systems (first and second hoisting systems) within a single crane, each with its own sheave block and hoisting cable. This segmentation allows independent control of load distribution to different parts of the monopile while being managed by a single crane's control system, avoiding the complexity of coordinating two separate cranes
2Force
If two cranes are used for up-ending, then lifting capacity is improved, but space requirements and vessel configuration constraints increase
Solution Approach 1:
The patent merges two crane functions into one crane by providing the crane housing with two hoisting systems. This consolidation maintains the lifting capacity needed for up-ending operations while eliminating the need for additional crane mounting space on the vessel, directly addressing the space constraint problem
3Device complexity
If sheave blocks are fixed on the boom, then structural simplicity is improved, but torsion loads on the boom increase during asymmetric loading
Solution Approach 1:
The patent makes the sheave blocks dynamic by allowing them to pivot about a horizontal second pivot axis that is perpendicular to the sheave rotation axis. This dynamic capability enables the sheave blocks to adjust their orientation in response to asymmetric loading conditions during up-ending, thereby reducing torsion loads on the boom while maintaining structural simplicity
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 stable and controlled up-ending of large monopiles, reducing torsion loads and eliminating the need for synchronized crane operations, making it feasible for vessels with limited space and crane capacity.
Implementation Method 1
a slew bearing; a crane housing moveably mounted to the base structure via the slew bearing to allow the crane housing to rotate relative to the base structure about a substantially vertical slewing axis
Implementation Method 2
the sheave block of each main hoisting system is pivotable about a substantially horizontal second pivot axis that is perpendicular to the sheave rotation axis of the one or more sheaves of the sheave block
Implementation Method 3
each main hoisting system comprises: a hoisting cable; a sheave block with one or more sheaves that are rotatable about a sheave rotation axis
Data Source
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AI summary
A method for up-ending a longitudinal structure, e.g. a monopile, e.g. as a foundation of an offshore wind turbine. Use is made of a crane comprising a boom that is moveably mounted to a crane housing to allow the boom to pivot relative to the crane housing about a substantially horizontal first pivot axis. The crane comprises three main hoisting systems. The method comprises the following steps: a) providing a longitudinal structure with an upper end and a lower end in a substantially horizontal orientation; b) connecting the middle hoisting block of the three main hoisting systems and one of the outer hoisting blocks of the three main hoisting systems to the upper end of the longitudinal structure; c) connecting the other outer hoisting block of the three main hoisting systems to the lower end of the longitudinal structure; and d) operating the respective winches of the three main hoisting systems until the longitudinal structure is in a substantially vertical orientation with the upper end above the lower end.