Pressure safety valves (PSVs) play a vital role in ensuring the safe operation of industrial processes and equipment by preventing overpressure situations that could lead to serious accidents causing injuries or even fatalities, as well as significant environmental damage. PSVs are particularly crucial in high-pressure hydrogen systems due to the safety challenges associated with hydrogen gas. These challenges include the highly flammable nature of hydrogen gas, and the fact that it can cause embrittlement in certain materials, potentially compromising the integrity of system components over time.
In a presentation at the Emerson Exchange EMEA 2024 in Düsseldorf, Luis Sancho, reliability manager at the ILBOC refinery in Cartagena, Spain, stressed the importance of investing in the best possible safety devices for hydrogen applications. This includes not only PSVs but also ultrasonic detectors to monitor equipment and trigger an early warning system in the event of a gas leak.
Sancho explained that in hydrogen applications, the use of modulating action pilot operated (MAPO) PSVs delivers several benefits. They provide precise control over the relief pressure by modulating the valve’s opening in response to changes in system pressure. This allows for more accurate pressure regulation, ensuring that hydrogen systems operate within safe limits without experiencing unnecessary pressure fluctuations. MAPO valves can also mitigate pressure spikes more effectively than conventional relief valves by gradually opening and closing in response to pressure variations. This helps to minimize the risk of sudden pressure surges that could lead to equipment damage or safety hazards. In addition, robust MAPO valves are designed for high reliability and durability, making them well suited to demanding hydrogen service conditions.
Sancho then told delegates that there are several benefits to using a soft seated PSV rather than a metal seated valve in hydrogen applications. Crucially, soft seated valves provide enhanced sealing performance and tight shut-off, thereby minimizing the risk of hydrogen leaks. Soft seated valves also typically require less maintenance than metal seated valves, resulting in a longer service life and reduced downtime for maintenance activities. Furthermore, soft seats materials are compatible with hydrogen gas, which minimizes the risk of material degradation or embrittlement over time.
Although the risk of hydrogen gas leaks can be minimized, it is inevitable that they will still occasionally occur. Sancho said that when this happens, it is crucial to detect the leak as quickly as possible. He described how two Emerson devices – the Rosemount™ 708 Wireless Acoustic Transmitter and the Rosemount Incus Ultrasound Gas Leak Detector – are providing reliable gas leak detection at the ILBOC refinery in Cartagena.
When pressurized hydrogen gas leaks from a valve, it produces high-frequency acoustic waves or noise. The Rosemount 708 Wireless Acoustic Transmitter is equipped with an acoustic sensor that can detect this noise. The transmitter processes the acoustic signals it receives from the sensor using advanced algorithms, to distinguish the signals from background noise and identify them as potential gas leaks. The transmitter then wirelessly transmits an alarm signal to a central control system or monitoring station, enabling appropriate response actions to be triggered. The continuous, real-time monitoring provided by the device helps to prevent the potential safety hazards, environmental impacts, and equipment damage associated with uncontrolled hydrogen gas leaks. Sancho explained that a single Rosemount 708 Wireless Acoustic Transmitter enables ILBOC to monitor several PSVs at the same time, even when they are separated by tens of meters.
The Rosemount Incus Ultrasound Gas Leak Detector utilizes four ultra-sensitive acoustic sensors to provide continuous monitoring and detection of the high-frequency sound waves produced by the release of pressurized hydrogen gas. The device has been engineered to withstand the most extreme conditions and is unaffected by inclement weather, wind, leak direction, and gas dilution or stratification. Sancho explained that the comprehensive coverage provided by this array of sensors makes the device ideally suited to monitoring large areas. He told delegates that at the Cartagena refinery, a single Rosemount Incus Ultrasound Gas Leak Detector provides reliable gas leak detection for an entire compressor shelter.
