Valve Control Failure Detection With Pressure and Position Feedback
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Solution Overview
Problem
Control devices using digital (On/Off) electro-pneumatic converters face challenges in detecting and recovering from failures, particularly when the initial high current fails to open the converters, leading to intermittent or complete failures, which can result in unscheduled shutdowns and require manual intervention.
Innovation Solution
The implementation of a failure detection system that monitors sensor feedback data over time to detect differences in pressure and position, triggering reissuance of input signals to attempt to resolve failures and restore normal operation, including tracking and reporting failures to facilitate proactive maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If digital (On/Off) electro-pneumatic converters are used with initial high current to open converters, then power consumption is reduced and control is simplified, but failure detection and recovery capability deteriorates leading to intermittent or complete failures
Solution Approach 1:
The system performs preliminary actions by issuing command signals to open converters before actual failure occurs. The sequential opening of first and second converters with predetermined timing creates a preparatory state that enables automatic recovery when failures are detected, preventing complete system shutdown.
Solution Approach 2:
The system implements feedback mechanisms by monitoring the operational state of converters and automatically adjusting control signals. When a converter failure is detected through lack of expected response, the system feeds back recovery commands to attempt opening closed converters, creating a closed-loop control system that maintains reliability despite power reduction.
2Measurement precision
If converters are controlled with digital On/Off signals and high current application, then control precision is improved, but the system becomes more susceptible to failures requiring manual intervention
Solution Approach 1:
The system performs self-service by automatically detecting converter failures and issuing recovery commands without manual intervention. The control device monitors converter states and autonomously attempts to recover from failures by reissuing open commands, eliminating the need for operator intervention and maintaining precise digital control.
Solution Approach 2:
The system takes preliminary recovery actions by automatically issuing command signals when failures are detected. Rather than waiting for manual intervention, the system proactively attempts to recover converters by reopening closed converters through automated control signals, maintaining operational continuity.
3Device complexity
If the system uses sequential converter opening with predetermined time intervals, then converter control is simplified, but failure detection capability is reduced
Solution Approach 1:
The system uses feedback to detect failures by monitoring whether converters respond as expected to control signals. The failure detection logic analyzes the relationship between commanded actions and actual converter states, identifying failures when discrepancies occur despite simplified sequential control timing.
Solution Approach 2:
The system applies partial action by issuing control signals to only one converter at a time with predetermined intervals. This sequential approach simplifies control while the failure detection mechanism compensates by monitoring each converter's response individually, detecting failures when expected responses do not occur within the predetermined timing framework.
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
This approach enables automatic detection and recovery from failures, reducing the likelihood of unscheduled shutdowns and allowing for timely maintenance, thereby improving the reliability and efficiency of process control systems.
Implementation Method 1
The solenoid includes a coil wrapped around a core that is positioned adjacent a moveable armature. The coil may be electrically activated to cause the armature within the solenoid to move between a first (closed) position and a second (open) position
Data Source
AI summary
Methods and apparatus to detect and/or recover from failures in valve control devices. An apparatus includes an input signal generator to provide a digital input signal to a first converter. The first converter corresponds to one of a supply converter or an exhaust converter. The supply converter controls actuation of a supply relay to deliver pressurized fluid to an actuator operatively coupled to a valve in a process control system. The exhaust converter to control actuation of an exhaust relay to exhaust the pressurized fluid from the actuator. The digital input signal triggers application of a current to the first converter to open the first converter. The apparatus further including a failure detector to: determine a difference in at least one of a pressure in the actuator or a position of a flow control member in the valve; and detect a failure when the difference satisfies a failure threshold.