In today’s industrial landscape, failure detection is critical to operational safety and efficiency. Not all key instrumentation issues can be efficiently diagnosed by the conventional onboard electronics, which keeps maintenance teams in the dark and puts operations at risk.
CCC has made the next step in instrument diagnostic technology by combining local device diagnostic with process behavior analysis. This holistic approach helps identify failures by verifying that the process behaves as it would when the device is healthy, or identifying measurements that indicate something is wrong even though the built-in failure detection electronics have not flagged an issue. CCC’s experts have designed these tools to increase safety, minimize process disturbance and maximize reliability.
Available on the Prodigy control platform, CCC’s instrument diagnostic tools help operators reduce the risk of key failures.
Verify the health of anti surge and steam control valves using a partial-stroke test designed to minimize process disturbance.
Detect which of the two dual redundant transmitters failed if their signals start drifting away from each other.
Identify transmitter freeze, even if the signal remains within the valid range and looks healthy when observed visually.
Anti surge valves are key to preventing highly destructive compressor surge events. But even the most high-quality mechanical device lacks 100% reliability, and anti surge valve failures often go undetected because the device is designed to stay closed when the compressor is loaded. The same can happen to the turbine steam valve, which often stays in the same position. CCC’s Valve Exerciser verifies the health of the most important valves surrounding the compressor in less than one minute — without disturbing the process.
The design conditions for most anti surge control valve applications keep the recycle valves closed, which means that many sites only open these valves during startup and shutdown operations or low-load periods. As a result, control valves can operate in the same position for an extended period of time, ranging from several weeks to even months. While the valve is closed, a range of issues can occur with the positioner, actuator or plug. Maintaining a fully closed position can also cause deposit buildup around the valve stem and seat. This buildup tends to increase stiction, which can prevent the valve from moving without delay when the anti surge or shutdown systems command it to open. And even if it opens, the recycle line can be blocked by hydrates or something else.
Throughout CCC’s commissioning experience, our engineers have witnessed these complex dynamics firsthand — and leveraged them to develop a more effective diagnostic tool.
If mechanical failure prevents the valve from moving when requested or a deposit buildup prevents flow from going through the recycle line, the compressor could surge and cause devastating effects. This scenario also applies to steam turbine main control valves, which stay in the same position for long periods but must move precisely to avoid mechanical damage and process instability.
Although many modern actuators include self-testing features designed to better detect anomalies, invoking such tests without care could introduce instability into the running process. Because the scope of self-tests is typically limited to the actuation system and valve, these tools do not evaluate the system’s effectiveness in controlling the underlying process. In other words, they rarely indicate if the flow is actually going through the pipe — and if they do, this testing won’t be quick or automatic.
With CCC’s Valve Exerciser, users are equipped with real test data and can later analyze the condition of the anti surge valve and steam turbine main control valve during maintenance activities. By doing so, they can prevent process disruptions due to degraded condition of the valve and, in severe cases, machine damage caused by surging or overspeed.
With high execution speed and I/O channels precision, CCC is uniquely positioned to sense all the data involved with even the smallest valve movements. To test the valve performance, Valve Exerciser generates a partial stroke test in the steady-state condition. This test evaluates three configurable signals spanning both process parameters and valve position feedback:
If the Valve Exerciser detects that the process response is below the baseline or the positioning is not fast enough, it generates an alarm that alerts operators to address the valve condition and plan maintenance. This test is designed to have minimal effect on the process, all while verifying valve health in less than one minute.
CCC’s advanced diagnostics functionality helps operators enhance not only their detection capabilities but the overall performance of both anti surge valves and steam turbine main control valves.
This functionality is also available from the DCS with proper MODBUS configuration.
When a transmitter signal drifts, it threatens the accuracy of signal measurements. Faulty measurements can trigger a control system reaction that causes units to go offline, unnecessary recycling and/or a trip. The result is a major process disturbance.
In systems with dual redundant transmitters, one signal’s drift can cause unwarranted actions, despite nominal signal redundancy. This drift can occur for many reasons, from impulse line blockages, moisture or leakage to transmitter malfunction or electrical issues.
CCC’s Transmitter Drift Detection minimizes the risk of process disturbances by precisely detecting transmitter drift in a dual redundant pair — even if the signal remains within the valid range and looks healthy when observed visually.
Despite its potential for major process disturbances, transmitter drift often goes undetected by conventional solutions. Because industry practice is to utilize the safest minimum or maximum values for the selection method, the signal often stays within a valid range even when drift is present.
The deployment of smart instruments has improved diagnostic coverage. But despite these advancements, CCC’s commissioning experts have continued to witness a substantial number of transmitter drift incidents.
When the signals in a redundant pair disagree, CCC Transmitter Drift Detection identifies which one is valid through correlation with numerous measurements, including pressure ratio and flow. This gives operators the information required to prevent the control system from acting based on a malfunctioning signal, which could trigger a process disturbance.
Leveraging unparalleled commissioning experience, CCC designed our algorithm to overcome key limitations of conventional diagnostic tools:
Also called a “stale” signal, transmitter freeze can be caused by plugged or closed impulse lines, or a transmitter malfunction that causes the signal to remain at a constant value. But no matter the cause, this significant failure prevents the control system from reacting to process changes, leading to unsafe conditions that require immediate intervention from operation personnel.
CCC’s Transmitter Freeze Detection algorithm identifies “stale” signals even when they remain within a valid range — and automatically alerts maintenance personnel to the issue.
Despite the significant safety risks of transmitter freeze, the issue often goes unnoticed by conventional detection methods because a frozen signal can stay within a valid range. These solutions are not equipped to identify how signal characterizations change when a transmitter fails to update its output value or when isolation valves on a pressure transmitter are closed.
CCC’s Transmitter Freeze Detection tool precisely calculates the amplitude of signal noise, generating an alarm if the figure falls below normal expected values. This timely, effective detection method alerts maintenance personnel to the instance of transmitter freeze and triggers an applicable feedback algorithm that keeps the compressor safe and efficient while operators fix the problem.
CCC is uniquely equipped to understand the nuances of how signal characteristics change during transmitter freeze scenarios. By measuring the amplitude of a signal’s noise, our advanced algorithm identifies when it becomes “frozen” or remains within tolerance for an extended period. This tolerance is chosen to be less than typically observed values.
Can be applied to any transmitter or essentially to any controller input channel.
Contact your sales representative today to discover how CCC’s suite of instrument diagnostic tools can help your operation minimize process disturbance and maximize reliability.