Multiport Valve Seat Loading for Continuous Coker Switching
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Solution Overview
Problem
Coker switch valves (CSVs) face issues such as flow interruption, coke formation, valve seizure, misalignment, uneven seat loading, leakage, excessive steam consumption, and complex maintenance due to the use of bellows resilient members and steam purging, leading to reduced efficiency and reliability.
Innovation Solution
A multiport valve with a sealed semi-trunnion arrangement supporting a spherical flow control element, featuring a larger outlet bore than the inlet, and a bonnet and body design that biases resilient members to maintain alignment and equalize stresses, reducing leak paths and operating torque, and allowing for simplified steam purging and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CSVs use bellows resilient members to load valve seats, then the valve can maintain sealing, but the bellows are prone to fouling and provide additional leak paths
Solution Approach 1:
The patent removes the bellows resilient members from the valve seat loading mechanism entirely. Instead, the valve seats are loaded directly by the weight of the ball and the mechanical structure of the valve body, eliminating the intermediate bellows component that caused fouling and leak paths while maintaining sealing reliability
Solution Approach 2:
The patent introduces a new intermediary mechanism - a resilient member positioned between the ball and the valve seats - that transfers the ball's weight to the seats without requiring bellows. This intermediary resolves the contradiction by providing reliable seat loading while avoiding the fouling issues of bellows
2Adaptability or versatility
If the CSV switches between coke drums, then flow can be diverted, but there is a brief interruption causing 40% reduction in process flow
Solution Approach 1:
The patent designs the valve with multiple outlet ports and a ball that can be positioned to maintain flow paths during switching. The preliminary arrangement of flow paths and outlets allows for smoother transitions between drums, reducing flow interruption by preparing alternative flow routes in advance
Solution Approach 2:
The patent employs a dynamic switching mechanism where the ball can be rotated to different positions to align with various outlet ports. This dynamic positioning allows for more flexible and continuous flow diversion compared to fixed-position valves, maintaining productivity during switching operations
3Ease of manufacture
If the CSV uses flanged piping connections with bellows resilient members, then the valve can be assembled, but coupling pipe line loads to seat loads complicates the loading
Solution Approach 1:
The patent segments the loading paths by separating pipe line loads from valve seat loads. The valve body and seat assembly are designed as independent load-bearing components, with the ball's weight directly loading the seats through a simplified mechanism that does not require coupling with external piping loads, thereby reducing complexity
4Adaptability or versatility
If thermal growth in piping system changes mechanical strains on end connections, then the valve can accommodate expansion, but the loading on seats becomes unbalanced
Solution Approach 1:
The patent employs a resilient member positioned between the ball and the valve seats that acts as a counterbalancing element. This resilient member compensates for unbalanced loads caused by thermal expansion by providing a restoring force that maintains seat loading balance, allowing the valve to accommodate thermal growth without compromising seating stability
5Reliability
If high loading stresses are applied to valve seats, then the valve can maintain sealing, but operating torque increases
Solution Approach 1:
The patent changes the physical parameters of the valve seats by enlarging their diameter and modifying their geometry. This allows the seats to distribute loads more effectively, maintaining reliable sealing with lower contact stresses and thereby reducing the operating torque required to rotate the ball, while still achieving adequate sealing force
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 minimizes flow interruption, reduces steam consumption, prevents coke formation, maintains alignment, and simplifies maintenance, enhancing switching reliability and reducing operational complexities.
Implementation Method 1
A sealed multiport valve incorporates a like plurality of resilient members, each biasing a respective one of the outlet valve seat assemblies against the flow control element
Data Source
AI summary
Multiport valve with outlets transverse to the inlet useful as a coker switch valve. A sealed lower sleeve assembly provides semi-trunnion ball support. An upper part of the outlet seat recesses is formed in the bonnet, and a lower part in the valve body, which together bias a resilient member to load the seats, independently of end connections. Before bonnet assembly, when the ball is rotated to face a body outlet, there is sufficient space in the seat recesses to insert the seat, slide the seat onto the ball, and then insert the resilient member. When all the seats and resilient members are in place, engagement of the bonnet biases the upper part of the resilient members to load the seat. In valve operation, an enlarged ball outlet bore can straddle two outlet ports and maintain process media flow during switching. Also, methods of assembling, operating, and servicing the valve.