Frictional Support Element for Thermal Cycling Vessels
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Solution Overview
Problem
Industrial pressure-tight vessels used in delayed petroleum coking processes experience structural failures due to extreme thermal cycling, particularly at the welds between the support skirt and vessel shell, leading to cracking and fatigue-related issues.
Innovation Solution
A support element that utilizes bearing and frictional forces instead of welds to support the vessel, with a tapered bearing section and a larger contact area to reduce thermal stresses and fatigue, optionally including a pre-stressed annular upper section and high-temperature mastic for improved thermal conductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the vessel is supported by welded support skirt, then the structure provides strong support, but the welds experience high stress concentrations and fatigue during thermal cycling
Solution Approach 1:
The invention removes the welded connection between the support skirt and vessel shell, extracting the harmful weld joint from the system. The support element is instead attached to the bottom of the vessel, separating the support function from the thermal cycling zone, thereby eliminating stress concentrations at the knuckle area while maintaining structural support.
Solution Approach 2:
The support element acts as an intermediary component between the vessel and the foundation. It provides mechanical support while being positioned away from the thermal cycling zone, mediating between the need for strong support and the need to avoid thermal fatigue at the vessel shell.
2Reliability
If the support element uses bearing and frictional forces instead of welds, then fatigue resistance improves, but the connection mechanism becomes more complex
Solution Approach 1:
The invention changes the fundamental parameters of the connection mechanism from welded (permanent, rigid) to friction-based (mechanical, flexible). The support element utilizes frictional forces between its surface and the vessel bottom, combined with bearing forces, to provide support without thermal cycling exposure, thereby improving fatigue resistance while maintaining manageable complexity.
3Stress or pressure
If the bearing section provides larger contact area, then thermal stresses are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The bearing section is designed with a tapered configuration that provides progressively increasing contact area from top to bottom. This local quality variation optimizes the stress distribution, with the larger contact area at the bottom providing better heat dissipation and stress distribution where it is most needed, while maintaining manageable manufacturing tolerances.
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 enhances fatigue resistance and reduces stress concentrations, leading to a more durable and long-lasting vessel structure capable of withstanding extreme thermal cycling without premature failure.
Implementation Method 1
the new support element supports the vessel primarily by bearing and frictional forces
Implementation Method 2
providing a more uniform temperature gradient between the vessel and the support element
Implementation Method 3
a layer of high-temperature mastic can be applied between the vessel and bearing surfaces on the support element to further improve thermal conductance
Data Source
AI summary
A structure for extreme thermal cycling has a support element that supports a vessel primarily by bearing and frictional forces rather than by welds. The support element has a bearing portion that tapers inwardly beneath a knuckle that separates a cylindrical section of the vessel from a sloped lower section. The bearing portion of the support element follows that slope, providing an extended area of contact between the support element and the vessel. An annular section of the support element can be heated and expanded before placing it around the cylindrical section of the vessel to provide pre-stressing. If required, a strap may extend downwardly from the vessel over an upper edge of the support element.