Hydro-Pneumatic Boom Restraint for Offshore Crane Load Loss
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Solution Overview
Problem
Offshore cranes face challenges in handling large and heavy piles due to the risk of boom collision and damage from sudden load loss, vessel roll, and wire slack during overboarding, especially when installing offshore wind turbine foundations in deep waters.
Innovation Solution
A heavy lift crane equipped with a hydro-pneumatic boom restrainer system that includes hydraulic cylinders, gas buffers, and a control system to monitor load and vessel roll, engaging the boom to prevent upward pivoting and collision by switching to an active mode upon load loss or roll detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the boom is positioned in a raised, substantially vertical position to handle long and heavy piles, then the crane can reach deeper water locations, but the boom becomes vulnerable to collision with the crane structure during load loss
Solution Approach 1:
The patent applies beforehand cushioning by introducing a hydro-pneumatic boom restrainer system that includes hydraulic cylinders and gas buffers. These components are pre-positioned to engage the boom before collision occurs, absorbing impact energy and preventing the boom from striking the crane structure during load loss events.
Solution Approach 2:
The patent uses an intermediary approach by introducing a boom restrainer system as a mediator between the boom and the crane structure. This restrainer, comprising hydraulic cylinders and gas buffers, acts as a buffer zone that prevents direct contact between the boom and crane structure while allowing controlled movement within safe parameters.
2Stability of the object's composition
If ballast tanks are used to stabilise the vessel during overboarding, then the vessel remains level, but sudden load loss causes the vessel to tilt and the boom to pivot upwards
Solution Approach 1:
The patent implements feedback by using sensors to continuously monitor load conditions and vessel roll angle. When load loss or excessive roll is detected, the control system activates the hydro-pneumatic boom restrainer to counteract the upward pivot movement, creating a closed-loop control system that responds dynamically to changing conditions.
Solution Approach 2:
The patent applies pneumatics and hydraulics by using a hydro-pneumatic boom restrainer system that combines hydraulic cylinders with gas buffers. This system uses fluid pressure and gas compression to provide controlled resistance against boom upward movement, effectively counteracting the tilting effect caused by load loss on the stabilised vessel.
3Adaptability or versatility
If the boom is allowed to pivot freely to accommodate load variations, then the crane can adapt to different loading conditions, but the boom may pivot beyond the vertically upright position and collide with the crane structure
Solution Approach 1:
The patent applies dynamics by creating a dynamic restraint system that adapts to different boom positions and loading conditions. The hydro-pneumatic restrainer provides variable resistance based on the boom's position and the detected load conditions, allowing free movement within safe parameters while preventing excessive pivot beyond the vertically upright position.
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
Reduces the risk of boom collision and damage to the crane and vessel by damping upward movement, preventing wire slack, and maintaining controlled boom positioning during load loss or vessel roll, enhancing safety and stability.
Implementation Method 1
a gas buffer for each cylinder, wherein each gas buffer is mounted to the corresponding cylinder, and is connected to the hydraulic circuit of the corresponding cylinder via a medium separator, wherein the gas buffer forces the cylinder in an extend position, and wherein the volume ratio between the cylinder and the buffer is such that the cylinder acts as a progressive spring
Implementation Method 2
multiple hydraulic cylinders, each having a hydraulic circuit and a cylinder rod with a cylinder head, wherein the cylinders are mounted on the crane structure with the cylinder heads directed towards the boom of the crane
Data Source
AI summary
A crane for use on an offshore vessel is provided with a boom restrainer, wherein the boom restrainer is a hydro-pneumatic boom restrainer, for reducing upward pivoting of the boom, when the boom is in the top zone, wherein the boom restrainer includes: multiple hydraulic cylinders, each having a hydraulic circuit and a cylinder rod with a cylinder head, wherein the cylinders are mounted on the crane structure with the cylinder heads directed towards the boom of the crane, preferably are mounted on a stay of the crane structure, a catcher for each hydraulic cylinder, wherein each catcher is mounted on the boom and is configured for receiving the cylinder head of the corresponding hydraulic cylinder, and to lock the cylinder head, preferably pivotable locks the cylinder head, relative to the boom, when the boom pivots upwards in the top zone; a gas buffer for each hydraulic cylinder, wherein each gas buffer is mounted to the corresponding hydraulic cylinder, and is connected to the hydraulic circuit of the corresponding hydraulic cylinder via a medium separator, wherein the gas buffer forces the hydraulic cylinder in an extended position, and wherein the volume ratio between the hydraulic cylinder and the gas buffer is such that the hydraulic cylinder acts as a progressive spring, e.g. the gas buffers each have a size in the range of 1000-1400 litre, for example 1200 litre and the hydraulic cylinders each have a size in the range of 800-1000 litre, for example 900 litre, and preferably the ratio between the volume of the gas buffer and the volume of the associated hydraulic cylinder is 4:3.