Problem visualised

Visual flame detection technology is making an impact in the offshore sector by preventing false alarms and production stoppages, writes Jose Sanchez.

The Haewene Brim is the latest floating production storage and off-loading installation to embrace a combination of 3D flame detection modelling and intelligent visual-flame detection technology in order to reduce false alarms and process interruptions.

Visual flame detection is regarded as a technology with some significant benefits over the capabilities of triple-IR detection in oil and gas processing facilities. It is specifically used to deal with detection issues around radiative transfer, an electromagnetic radiation transfer that can be caused by sunlight reflecting on rippling water, as well as by vibrating heat sources such as gas turbines, diesel generators or even exhaust pipes. Triple-IR detectors, which are designed to compare three specific wavelength bands within the infrared spectral region, can become desensitised in these environments and even false alarm.

Visual flame detectors, however, are immune to the radiative energy transfer effect because they work by processing live video images to detect the characteristic properties of flames visually, through flame-detection algorithms. As a result, the technology is currently experiencing something of a surge in demand in the offshore sector, in particular on FPSO units. This is because these contain large flare stacks, the heat from which can reflect on the surfaces on the deck, causing triple-IR detectors to false alarm.

This issue was faced by Bluewater Energy Services, a manufacturer and designer of FPSOs, which wanted to reduce the number of false alarms initiated by existing triple-IR flame detection configurations on the Aoka Mizu FPSO.

Looking for a solution, Bluewater initiated a project with Micropack, a company that manufactures intelligent visual

flame detectors and is also known to specialise in fire and gas mapping services.

The 3D modelling software Haz Map 3D was used to design a flame-detection layout around the apparatus and process equipment on the FPSO, including the testing of several voting configurations. The voting system determines when a manual or an automatic response is needed: one detector in alarm may only require a manual intervention, while two detectors may lead to an automatic release of extinguishing agent, for example, or the shutting down of a process. Micropack's business development manager Graham Duncan explains that the flame-detector layout is specific to the type, model and sensitivity used. Using the software, Micropack determined the optimum configuration of detector number and types that could provide the required level of safety while potentially saving on cost.

As a result of the mapping study, two years ago 26 triple-IR detectors on the Aoka Mizu FPSO were replaced with Micropack’s FDS301 visual flame detectors.

The approach was so successful that Bluewater contacted Micropack again, this time to work on the Haewene Brim FPSO, where multiple false alarm episodes were being experienced from the existing IR3 flame detectors. These were leading to costly production stoppages during its deployment in the Pierce field, 265km east of Aberdeen, Scotland. As a result of the modelling work, in 2017 a number of triple-IR detectors were replaced with FDS301 visual flame detectors on the Haewene Brim FPSO. The work was completed on board in just 10 days.

Purported to be the most advanced of its type, the FDS301 is the third-generation intelligent visual flame detector made by Micropack. At the heart of the detector is a flame-detection algorithm that has been developed over the course of 22 years to provide high levels of false alarm immunity in the most challenging of environments. It uses a dual-camera system with one camera providing a live colour video feed to the operator while the second uses near-infrared technology to detect flames visually.

The Haewene Brim FPSO (above) and the Aoka Mizu FPSO (below) were both fitted with visual flame detectors to prevent stoppages as a result of false alarms.

The unit is able to record a fire 8.5 seconds before and after an alarm, which not only provides ‘black box’ functionality through an SD card, but also enables the operators to implement preventative measures after incident analysis.

Building on its experience and growing presence in the offshore sector, Micropack, has recently secured another significant offshore contract. The company will be installing over 200 visual flame detectors on a mega-project in the Gulf of Mexico.

INDUSTRIAL FIRE JOURNAL third quarter 2018

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