Linked Coke Drum Support for Thermal Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coke drums experience low cycle fatigue stresses at the circumferential drum to skirt weld due to differential expansion and contraction during temperature changes, leading to potential skirt failure and costly maintenance in delayed coking processes.
Innovation Solution
A pivoting link assembly is affixed between the coke drum and supporting structures, allowing for reduced-stress thermal expansion and contraction through a circumferential connection plate and segmented links that pivotally connect to ground links, reducing stress on the connection and enabling the drum to expand and contract without exerting undue stress on the support system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed support system is used to securely hold the coke drum, then the drum is stable and prevented from tipping, but the drum experiences high stress during thermal expansion and contraction leading to low cycle fatigue
Solution Approach 1:
The support system transitions from a fixed rigid connection to a dynamic articulated linkage system. The quadrilateral linkage mechanism allows the drum support position to adjust dynamically during thermal expansion and contraction cycles, converting the static fixed support into a dynamic adaptive support that maintains stability while accommodating dimensional changes.
Solution Approach 2:
The invention changes the geometric parameters of the support system by using a quadrilateral linkage mechanism with specific length relationships (where the sum of lengths of opposite sides are equal). This parameter configuration enables the linkage to move through a controlled arc, changing the support geometry dynamically to accommodate drum expansion while maintaining structural integrity.
2Ease of operation
If the coke drum is elevated to allow coke removal, then coke can be discharged from the bottom, but the drum becomes more susceptible to tipping from wind and seismic forces
Solution Approach 1:
The elevated drum is supported by a dynamic articulated linkage system rather than fixed rigid supports. This dynamic system provides both elevation for coke removal and active stabilization against lateral forces, as the linkage can adjust its configuration to resist wind and seismic loads while maintaining the elevated position.
Solution Approach 2:
The support system is segmented into multiple articulated components (links and joints) forming a quadrilateral mechanism. This segmentation allows the support structure to distribute and actively respond to various forces including gravitational load, wind pressure, and seismic forces, providing both elevation and stability simultaneously.
3Strength
If a rigid skirt connection is used to support the drum weight, then the support structure is simple and strong, but the weld experiences high stress during thermal cycles causing fatigue failure
Solution Approach 1:
The rigid fixed connection is replaced with a dynamic articulated linkage system that maintains structural strength through its geometric configuration while eliminating the thermal stress concentration at weld points. The linkage mechanism distributes forces through multiple joints and members, preventing stress concentration that leads to fatigue failure.
Solution Approach 2:
The articulated linkage acts as an intermediary mechanism between the drum and the ground support. This intermediate system transmits the drum weight and accommodates thermal expansion through controlled mechanical movement, mediating the thermal-stress relationship and preventing direct stress transmission to the drum-skirt weld.
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 linked coke drum support system effectively reduces stress on the skirt connection, prolongs the lifespan of the coke drum support system, and minimizes the risk of failure by allowing for thermal expansion and contraction without imposing additional stress, thus enhancing operational reliability and reducing maintenance costs.
Implementation Method 1
allowing for reduced-stress thermal expansion and contraction
Implementation Method 2
supporting structures capable of supporting the weight of the coke drum
Data Source
AI summary
A linked coke drum connection to minimize the stresses experienced by the joint between the coke drum and the supporting structure of the coke drum is described. The connection may be attached to a circumferential connection plate attached to the coke drum or directly to the drum. Some embodiments connect to a segmented circumferential connection plate. The connection includes a coke drum link, a connecting link, and a ground link. The links are pivotally connected with connecting pins. As the coke drum is heated and expands, the connecting link pivots outwardly about a point centered in the connecting pin in the ground link.