At the Emerson Exchange EMEA 2024 in Düsseldorf, Javier Garbin, energy efficiency leader at Repsol, outlined a project to identify leaks from safety valves to support the goal of being a net zero emissions company by 2050.
One of the largest sources of CO2 emissions in an industrial complex is routine flaring. In addition to being a source of emissions, this is also a loss of product. Discharges from the flare network are classified as either identified (due to fuel gas network control, reactor regenerations and emergency unit stops) or unidentified (due to safety valve leaks or discharges, or open manual valves).
At the Repsol Tarragona facility in Spain, the olefins unit has a large amount of equipment in a very small space. Due to the high number of safety valves that are connected to the flare collector, it is very difficult to identify valve leaks. One method is to use acoustic “listening” devices, because gas leaks through small holes generate noise in the ultrasonic frequency.
In 2003, Repsol installed wired acoustic sensors to monitor 83 pressure safety valves (PSV). The experience was not positive due to the poor reliability of the measurements. As a result, the equipment was taken out of service.
Repsol is committed to achieving net zero emissions and has joined the World Bank’s ”Zero Routine Flaring by 2030” initiative. To support its “zero routine flaring” plan, Repsol decided to re-explore ways of preventing unidentified flare discharges. In 2017, Repsol initiated a pilot project to monitor 33 PSVs and 17 steam traps using wireless acoustic sensor technology from Emerson. The application was particularly challenging for wireless technology because of the large amount of equipment in a very small space, including infrastructure up to 100 meters in height.
Mounting Emerson’s wireless acoustic sensors to the safety valves was easy.
The Emerson wireless solution is based on the WirelessHART international standard, which utilizes a mesh topology to transmit data reliably. To ensure the wireless network coverage was optimal for the equipment installed both at high points and at ground level, several repeaters were installed. The non-intrusive wireless acoustic sensors were easy to install and help to strengthen the mesh network by also acting as signal repeaters. The Emerson wireless solution was easily integrated into the existing industrial wireless plant network by simply connecting the WirelessHART gateways directly to network access points.
The wireless acoustic technology from Emerson has proven to be effective in monitoring the condition of safety valves. During daily operations meetings, the noise and temperature measurements are checked to determine if a PSV is leaking. Also, the flare visual camera and the header flow meter are used to monitor the performance of the system. The pilot project lasted six months, with the objective being to test the reliability of the PSV monitoring system. During the trial, the system’s response to forced flare discharges was tested on 10 safety valves by forcing their discharge through bypass valves. Repsol determined that noise from other adjacent sources (other leaks) can affect the measurement, but the system can be adjusted to suppress ambient noise.
In 2023, Repsol decided to expand the number of safety valves being monitored and increase the number of different applications using the existing wireless network. This included monitoring steam turbine vibration, air blower vibration, quench oil pump vibration, cold box production stream pressure, steam reboilers temperature measurement, and 30 safety showers.
