How to monitor the take-off and internal leakage of the safety valve in real time (wirelessly)?Issuing time:2024-04-02 10:51 Innovation technology application series of online monitoring and early warning for major hazards (1) Chemical enterprises have a large number of major hazards and dangerous processes in their production. If these risks are not effectively controlled, it can easily lead to material leaks, fires, explosions, and other disastrous consequences. To ensure the safety of the production process, enterprises not only adopt safe processes but also have set up automatic control systems, alarms with human intervention, safety instrument systems, and mechanical release for active protection at multiple levels. As the last line of defense, the most typical device for mechanical release is the safety valve. I. The role of safety valves and the importance of monitoring pop-off events and internal leaks in real time Safety valves are automatic mechanical devices designed based on different process conditions. They are preset with an activation pressure and quickly activate to safely release pressure when the pressure exceeds the limit, thus preventing malignant accidents. Ensuring the effectiveness of safety valves can largely eliminate major safety accidents. However, if safety valves have internal leaks, are not replaced or recalibrated in time after activation, they may not work properly at critical moments, leading to leaks, fires, explosions, and other serious consequences. Moreover, the activation of a safety valve is defined as an accident, requiring timely accident analysis and corresponding rectification. Therefore,real-time understanding of the status of safety valves, especially internal leaks and activation events, is crucial for safety control. II. Pain points in monitoring the status of safety valves As purely mechanical devices, safety valves do not rely on external power or air sources and are not connected to DCS systems, making it extremely difficult to accurately and timely understand their operating status. Currently, chemical enterprises mainly monitor the status of safety valves through routine inspections, patrols, and judgments based on upstream and downstream process pressures. However, these methods have issues such as failing to detect internal leaks in safety valves in a timely manner, being unable to capture pop-off events in real time, and having difficulty in quickly locating the position of a safety valve pop-off. These problems pose significant hidden dangers to safety management.
Routine inspections: The current practice of routine inspections (at least once a year by a third-party professional organization for safety valve verification) is a standard method stipulated by the state. It only provides a result of whether the safety valve was qualified at the time of inspection and cannot monitor the real-time status of safety valves during operation.
Manual patrols: Manual patrols rely on hearing (such as the sound of internal leaks or pop-offs in safety valves), touch (such as changes in pipeline temperature), or temperature measurement tools. However, they are affected by environmental noise, operator experience, and other factors. Especially when there are a large number of safety valves or they are installed in high positions, it is not only impossible to detect internal leaks and pop-offs in real time, but misjudgments or missed judgments are also likely to occur. In addition, manual patrols often fail to detect slight leaks (presented as minor sounds, temperature, or vibration changes) and short-duration leaks, as well as short-duration pop-off events.
Upstream and downstream process pressure judgment: For example, installing a pressure transmitter on the upstream pipeline of the safety valve to monitor pressure changes. However, the pop-off of a safety valve is a local phenomenon, and the pressure change mainly occurs around the safety valve itself and its surrounding area. Therefore, even if the pressure transmitter can capture pressure changes, due to installation position, environmental temperature, medium properties, etc., it may not accurately reflect the pop-off information of the safety valve.
Moreover, especially in the context of torch scenarios, since the number of safety valves connected to the torch network is very large (for example, more than 1000 safety valves may be connected to a 1 million-ton ethylene unit), when abnormalities occur in the torch, it is difficult to quickly and accurately locate which safety valve has popped off or leaked through pressure judgment. Traditional methods take several hours or even days to find the problematic safety valve. During this time, the safety valve may continue to discharge or leak, causing significant economic losses and posing a great safety hazard. III. Solutions To solve the above problems, Xiao'an Digital Intelligence independently developed a wireless intelligent real-time monitoring system for safety valves. The system consists of Monitor A120, WirelessHART communication protocol, and upper computer software. The system realizes real-time monitoring and high accuracy with low false-positive rates for safety valve internal leakage and pop-off states through comprehensive judgment of three-dimensional data generated by the vibration information when the safety valve pops off, ultrasonic information produced by the fluid passing through the safety valve, and temperature changes in the pipeline caused by the fluid with very constant temperature characteristics passing through the safety valve, along with scientific algorithms with strong anti-interference capabilities (such as external noise, mechanical vibrations from pipes and other equipment).
Monitor A120 Monitor A120 is installed at the outlet pipeline of the safety valve, collecting real-time vibration, ultrasonic, and temperature signals of the safety valve. It combines digital signal processing and edge computing to transmit calculation results through WirelessHART wireless communication protocol to the gateway, which is then connected to the safety valve state monitoring platform.
Non-invasive, simple and fast installation, intrinsically safe (explosion-proof level: Ex ia IIC T4 Ga), adaptable to harsh environments in chemical plants, and low power consumption.
Monitors can be directly installed on any type and size of safety valve outlet pipeline without changing any valve and pipeline structure or requiring any hot work, simple and fast installation.
WirelessHART communication protocol WirelessHART has self-organizing and self-adapting features, managing multiple communication paths and maintaining continuous data flow in case of blockages. This highly reliable wireless architecture maintains data reliability greater than 99.99% even in harsh RF environments. At the same time, the WirelessHART protocol seamlessly integrates with existing process automation technology, and device configuration and tuning are compatible with conventional HART instruments, allowing for fast, safe, and low-cost network expansion.
Upper computer software The upper computer software is the user interface and management center of the safety valve monitoring system. It intuitively displays the enterprise's safety valve events (internal leakage, pop-off) situation, including dashboard overview, a list of all safety valve events, analysis, push notifications, and closed-loop management functions.
The following figure shows the real-time operating status list of safety valves:
The following figure shows the analysis of a single safety valve pop-off and internal leakage event:
IV. Case display and effect evaluation Xiao'an Digital Intelligence installed a wireless intelligent real-time monitoring system for safety valves at a chemical plant and also compared it with a similar product from an internationally renowned manufacturer. Xiao'an Digital installed A120 and the comparable product's instrument (which monitors from ultrasonic and temperature dimensions) at the same safety valve outlet.
As shown in the figure below, nitrogen passes through a pressure regulator from a 0.6MPa pressure reduction to 0.2MPa and is delivered to the unit for purging nitrogen. To prevent the pressure regulator from failing and causing nitrogen pressure to overpressure and damage downstream equipment, a safety valve with a set pressure of 0.3MPa (numbered 01PSV103) is installed downstream of the pressure regulator. Once the pressure exceeds 0.3MPa, the safety valve pops off to release pressure.
Note: Since nitrogen is at room temperature and there is no obvious temperature change at the safety valve outlet even when the safety valve pops off or leaks, monitoring the temperature change at the safety valve outlet is not very practical in this case. Case 1: Safety valve pop-off event on November 18, 2023
On November 18, 2023, the system detected obvious abnormalities in both ultrasonic and vibration signals at the safety valve outlet (see figure below), indicating a pop-off. This judgment was verified by the customer's DCS historical data, proving the effectiveness of the system's multi-dimensional data comprehensive analysis.
Analysis: In this case, the temperature monitoring did not provide valuable information due to the constant temperature nature of nitrogen. However, the ultrasonic and vibration data corroborated each other, successfully determining the pop-off event of the safety valve. This demonstrates the advantage of multi-dimensional monitoring in complex industrial environments.
Case 2: Safety valve state judgment on April 26, 2023
The system detected an abnormality in the ultrasonic signal of this safety valve (see figure 1 below), but no abnormality was detected in the vibration (see figure 2 below). Therefore, it was determined that the safety valve did not pop off or leak. In this scenario, the comparable product only detected an ultrasonic abnormality (see figure 3 below) and likely judged a pop-off. Subsequent verification by the DCS pressure history data confirmed that the pressure transmitter near the safety valve did not show a pressure reaching the set pressure value of 0.3MPa during that time, indicating that the safety valve did not pop off (see figure 4 below). The cause of the ultrasonic abnormality was that the safety valve pipeline was affected by a sudden increase in nitrogen flow in the main pipeline due to specific production operations (the use of nitrogen suddenly increases during certain production operations, while it may not be used or used less at other times).
Analysis: This case indicates that single-dimensional monitoring data may lead to misjudgments in the presence of external interference.
Through these two cases, it is evident that Xiao'an Digital's wireless intelligent real-time safety valve state monitoring system can quickly determine internal leakage and pop-off events through a combination of vibration, ultrasonic, and temperature multi-dimensional logic, with high accuracy.
V. System advantages summary
Real-time monitoring The system collects and analyzes real-time data on the vibration, ultrasonic, and temperature of the safety valve through Monitor A120 and quickly uploads it to the upper computer software via WirelessHART protocol. This means that as soon as there is an abnormal situation such as internal leakage or pop-off of the safety valve, the system can immediately capture these changes and provide feedback to the operator in real time.
High accuracy and low false-positive rate The system uses scientific and continuously upgradable optimization algorithms that can effectively eliminate interference factors such as external noise, mechanical vibrations from pipes and other equipment.
Simple and fast system deployment and operation The non-invasive design makes the installation of the monitor quick and simple, requiring no hot work. Simply clamp the monitor onto the outlet pipeline of the safety valve with a clip, and it can be completed in minutes. The system can be quickly deployed and is easy to maintain. The user interface of the upper computer software is designed to be straightforward, with quick access to necessary functions and simple operation processes. No complex training is required to get started.
In addition, the software provides rich data views and analysis tools, offering multi-dimensional information and closed-loop management functions to ensure effective management from real-time monitoring of safety valve internal leakage/pop-off events, notification of relevant personnel, automatic generation of logs, to feedback on handling results. |
