Hydro-pneumatic Tensioner Fluid Retention Device
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Solution Overview
Problem
Current pull-up riser tensioner systems require large volumes of hydraulic fluid, leading to weight, packaging, and cost issues, with time-consuming maintenance processes due to the need for frequent fluid replacement and limited access to tension rings on offshore platforms.
Innovation Solution
The implementation of a pull-up cylinder accumulator system with a small internal hydraulic fluid dam within the hydro-pneumatic cylinder, reducing fluid requirements and utilizing additional internal volume as a high-pressure accumulator, allowing for a smaller external accumulator and enabling fluid replacement without disconnecting from the tension ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large volume of hydraulic fluid is used to maintain fluid contact with dynamic seals, then seal lubrication is ensured, but the system weight and external accumulator size increase significantly
Solution Approach 1:
The patent introduces an internal hydraulic fluid dam nested within the cylinder piston assembly. This internal dam stores hydraulic fluid directly at the seal interface, eliminating the need for large external fluid volumes. The nested structure allows the fluid reservoir to be integrated within the existing cylinder components, reducing overall system weight while maintaining adequate lubrication of dynamic seals throughout the stroke range.
2Reliability
If the high-pressure accumulator is sized to hold all hydraulic fluid plus gas volume, then fluid retention is ensured, but the accumulator becomes very large presenting packaging and cost problems
Solution Approach 1:
The patent extracts the hydraulic fluid storage function from the external high-pressure accumulator and relocates it to an internal dam within the cylinder piston assembly. This separation allows the external accumulator to be significantly reduced in size, as it only needs to handle pressure regulation rather than bulk fluid storage. The internal dam contains the hydraulic fluid volume needed for seal lubrication, eliminating the need for a large external accumulator and resolving packaging and cost issues.
3Ease of repair
If hydraulic fluid is replaced by disconnecting the cylinder from the tension ring, then fluid maintenance is achieved, but the process becomes time-consuming with limited platform access
Solution Approach 1:
The patent segments the hydraulic fluid storage system into a removable internal dam component within the cylinder piston assembly. This segmentation allows the fluid-containing component to be independently accessed and replaced without disconnecting the entire cylinder from the tension ring. The internal dam can be serviced through existing access points on the platform, dramatically reducing maintenance time and improving ease of repair compared to full cylinder disconnection.
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 solution reduces the size and weight of the tensioner system, simplifies maintenance by allowing fluid replacement without stroking the cylinder, and decreases the overall cost and complexity of the system, enhancing safety and efficiency.
Implementation Method 1
The high-pressure accumulator 204 serves as a gas 'spring.' Under normal operation, the high-pressure accumulator 204 holds both hydraulic fluid and a gas media such as nitrogen or compressed air.
Implementation Method 2
The low-pressure accumulator 206 serves to maintain a near constant pressure on the piston side of the hydraulic cylinder 202 over the stroke range
Implementation Method 3
The cylinders 102 serve to maintain a near constant tension on the production or drilling riser 106 as the platform 108 moves in multiple planes due to wind, waves, platform movements, and other natural events.
Data Source
AI summary
A cylinder accumulator system is disclosed. The system includes a cylinder comprising a cylinder rod, a cylinder barrel coaxial to the cylinder rod, a cylinder end cap coupled to the cylinder barrel and the cylinder rod, and a cylinder piston assembly disposed within the cylinder barrel. The cylinder piston assembly further includes a dynamic sealing arrangement, which comprises one or more dynamic seals. The system further includes a first annular volume coaxial to the cylinder rod and the cylinder barrel, and a second volume disposed within the cylinder piston assembly. The system also includes a piston disposed within a bore of the second volume and between a hydraulic fluid located on a first side of the piston and a gas media located on a second side of the piston. The system also includes an external high-pressure accumulator, a low-pressure accumulator, and one or more tube manifolds coupling the external high-pressure accumulator and low-pressure accumulator to the cylinder.