Bearing Arrangement Flame Path Protection
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Solution Overview
Problem
Existing low voltage electric swivel (LVES) bearings in FPSO/FLNG swivel stacks are limited to Ex d IIA standard due to high precision requirements and cost, and cannot operate effectively in gas group IIB conditions, lacking standardized flame path protection and requiring complex maintenance.
Innovation Solution
A bearing arrangement with annular interfaces coaxial to the swivel axis, featuring annular bearings with ball bearing openings and seal rings, allowing for standardized and certifiable JIB type bearings that reduce precision tooling needs, lower costs, and simplify assembly and inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extreme precision machine tools are used to create flame path in prior art bearings, then flame path protection is achieved, but manufacturing cost increases and gas group IIB certification is not reachable
Solution Approach 1:
The bearing is divided into two separate bearings (first bearing and second bearing) with各自独立的 flame path interfaces. This segmentation allows each bearing to have its own standardized flame path design, eliminating the need for complex precision machining of a single integrated flame path, thereby reducing manufacturing costs while maintaining flame path protection for both IIA and IIB gas groups
Solution Approach 2:
The invention changes the flame path interface design from a localized precision-machined path to annular interfaces with standardized dimensions. The annular interface parameters (inner diameter, outer diameter, width) are defined with reasonable tolerances that can be achieved with standard machine tools, eliminating the need for extreme precision while maintaining flame path integrity
2Ease of manufacture
If standardized JIB type bearings are implemented with annular interfaces, then manufacturing precision requirements are reduced and costs lower, but flame path protection must be maintained
Solution Approach 1:
The annular interfaces are designed with specific local geometric characteristics (inner radius, outer radius, width) that create the flame path function. These localized geometric features provide the necessary flame path protection while the overall bearing structure can be manufactured with standardized, lower precision requirements using conventional machine tools
Solution Approach 2:
The invention converts the potential harm of standardized, lower-precision manufacturing into a benefit by designing the annular interface geometry such that standard tolerances still ensure adequate flame path protection. The annular shape with defined dimensions transforms manufacturing variability into a reliable, certifiable design for both IIA and IIB gas groups
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
The solution provides improved flame path protection, reduced maintenance needs, lower fabrication costs, and increased reliability by standardizing the bearing design, enabling operation in both IIA and IIB gas groups and extending the operating lifetime through lubricant use.
Implementation Method 1
each annular interface is configured as a flame conducting path
Implementation Method 2
each annular interface comprises lubricant to reduce wear of each annular interface during operation
Data Source
AI summary
A electric swivel, LVES, in a swivel stack, includes an annular outer element defining a cylindrical chamber around an axis S and an cylindrical inner element coaxial with the outer element. The cylindrical chamber is sealed at an upper side with an annular cover and is configured for rotation relative to the inner and outer element around the axis S. The inner element includes at an inner radial side first and second bearing parts defining an inner bearing. The outer element includes at an outer radial side first and second bearing parts defining an outer bearing. The inner bearing includes an inner annular interface between the first and second bearing parts, the outer bearing includes an outer annular interface between the first and second bearing parts. Each of the annular interfaces is coaxial with the inner and outer element, and each annular interface is configured as a flame conducting path.