Coker Switch Valve Locking and Position Indication Under Shear Pin Failure

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Solution Overview

Problem

Delayed coking systems face issues with coker switch valves seizing due to heavy oil exposure, leading to potential damage and misreporting of valve positions, and lack a positive locking mechanism to prevent inadvertent switching to bypass, posing a fire hazard.

Innovation Solution

A system with a shear pin linkage and locking plate mechanism that allows the valve stem to be rotated into alignment positions for directing heavy oil to coke drums or bypass, featuring a coaxial indicator rod for accurate position indication and a locking plate with lobes and pins to prevent unintended switching, ensuring the valve's true position is maintained.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a shear pin linkage is used to protect against over-torqueing, then valve and actuator damage is prevented, but the actuator continues to turn and misreport valve position

Engineering Contradiction:

Improveprotection against over-torqueingVSAvoidvalve position information

Core Design Contradiction:

StrengthVSLoss of information

Solution Approach 1:

The system divides the torque transmission path into separate segments: the shear pin linkage protects the actuator by shearing under excessive torque, while the indicator rod remains directly coupled to the valve stem to independently track and report the true valve position, separating the protection function from the position indication function

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The indicator rod acts as an intermediary element that directly connects to the valve stem and transmits position information to the indicator without being affected by the shear pin failure, providing accurate position feedback even when the actuator-stem linkage is broken

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If locking pins are used to prevent inadvertent switching, then safety is improved, but the system lacks positive locking in bypass mode allowing accidental switching to open drums

Engineering Contradiction:

Improveprevention of inadvertent switchingVSAvoidfire hazard from switching to open drum

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system applies different locking characteristics to different operational modes: two locking pins provide positive locking for drum positions (A and B), while a single locking pin provides protection for bypass position, creating localized safety features tailored to the specific risks of each mode

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The locking pins are positioned and configured in advance to prevent inadvertent switching before it can occur, with the bypass locking pin specifically arranged to block accidental rotation into the open drum position, proactively eliminating the fire hazard

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11174963B2Coker switch valve operating system and method

Publication Date: 2021.11.16 FLOWSERVE PTE LTD

AI summary

An operating system for switching a coker switch valve to drum A, drum B, and bypass. The system has a shear pin linkage between the actuator and the valve stem and a position indicator independent of the actuator, to maintain functionality in the event of shear pin failure; and/or lockout functionality to prevent an inadvertent switch to bypass when switching between drum A and drum B and to lock down bypass mode to prevent an inadvertent switch from bypass to an open drum.