Transfer Station Bypassing Valve Positioner in Control Loop

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Solution Overview

Problem

Existing process control systems require deactivation or shutdown of the process loop when valve positioners need to be repaired or replaced, disrupting the operation of actuators and valves.

Innovation Solution

A transfer station with three flow paths and fluid control devices allows for bypassing the valve positioner, enabling manual control of the process loop during maintenance, and balancing the output pressure to ensure seamless resumption of control after repairs or replacements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If the valve positioner is repaired or replaced, then the positioner can be maintained or replaced, but the process loop must be deactivated or shutdown

Engineering Contradiction:

Improvevalve positioner repairVSAvoidprocess loop operation

Core Design Contradiction:

Ease of repairVSProductivity

Solution Approach 1:

The system is divided into separate functional segments: the valve positioner, the actuator, and the control loop. By segmenting the pneumatic control system and providing alternative pathways (bypass flow paths), the positioner can be isolated and repaired without isolating the entire process loop, allowing maintenance while maintaining productivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A bypass valve assembly acts as an intermediary device between the positioner and actuator. This intermediary provides alternative pneumatic pathways that allow the actuator to receive control signals or manual input signals when the positioner is being repaired, enabling positioner maintenance without shutting down the process loop.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of repair

If the process loop is deactivated for positioner repair, then the positioner can be safely maintained, but the actuator and valve position become fixed and cannot be adjusted

Engineering Contradiction:

Improvevalve positioner maintenanceVSAvoidactuator position adjustment

Core Design Contradiction:

Ease of repairVSEase of operation

Solution Approach 1:

The bypass valve assembly serves as an intermediary that maintains the connection between control inputs and the actuator during positioner repair. This intermediary pathway allows operators to manually adjust actuator position or receive control signals without the positioner, preserving ease of operation while enabling safe maintenance of the positioner.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bypass valve assembly provides multi-functionality: it can handle manual control signals, automatic control signals from the control system, or simply maintain pneumatic pressure to the actuator. This universal capability ensures the actuator remains operable through multiple control methods during positioner repair.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If a bypass system is implemented, then the process loop can remain active during positioner repair, but the system complexity increases with additional flow paths and control devices

Engineering Contradiction:

Improveprocess loop continuityVSAvoidtransfer station structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The bypass valve assembly is merged with the existing positioner and actuator components into an integrated transfer station. By combining these functions into a single assembled unit with internal flow paths, the system achieves process loop continuity while minimizing the increase in overall system complexity compared to separate distributed components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bypass valve assembly is nested within or integrated with the positioner and actuator assembly. The flow paths are arranged such that the bypass functionality is contained within the existing structural envelope, adding complexity only where necessary while maintaining a compact integrated design.

Inventive Principle:

Principle #7Nested doll (Nesting)

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

Enables maintenance of control valve position without disrupting the active process loop, allowing for repair or replacement of valve positioners without venting supply pressure to the atmosphere, and ensures smooth transition back to normal operation.

Implementation Method 1

a manifold defining first, second, and third flow paths, the first flow path enabling fluid to flow from a supply pressure to a valve positioner

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

A method of enabling a positioner to be bypassed includes adjusting a regulator output pressure to be similar to a positioner output pressure

Methodology Applied

Scientific EffectPressure regulation:

Data Source

PatentEP2681457B1Method and assembly for bypassing a positioner in an active control loop

Publication Date: 2018.12.05 FISHER CONTROLS INT LLC

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AI summary

Methods and apparatus for bypassing a positioner in an active control loop are described. An example actuator assembly includes a pneumatic actuator and a transfer station. The transfer station includes a body defining flow paths that enable fluid to flow between a supply pressure, a valve positioner, and the pneumatic actuator and between the supply pressure and the pneumatic actuator to bypass the valve positioner without disrupting a process loop including the valve positioner. The transfer station also includes a plurality of fluid flow control devices to control the fluid flow through the flow paths.