IR cameras aid leak detection at BP Chemicals

London - BP Chemicals is employing infrared cameras to explore how infrared gas leak technology can minimise fugitive emissions at its site in Saltend, east Yorkshire. The facility produces acetic acid with the company’s proprietary methanol carbonylation technology, Cativa.

Effective leak detection is a site priority at Saltend and one of a number of procedures for ensuring safe operation.

Dr Geoffrey Wilcox, senior technologist at the site, said: “We have several established programmes that help us to comply with both regulatory and local requirements.”

He added: “To support these aims we have many systems for measuring, monitoring and reporting. Some are fixed and some are portable such as personal measurement devices.”

Infrared gas detection is not new to BP Chemicals at Saltend but since last evaluating its potential, the technology has been subject to considerable development.

One of Wilcox’s colleagues at BP in Naperville, US, environmental and loss control specialist Dave Fashimpaur, had chosen a FLIR GasFindIR HSX thermal imaging camera that was easily portable and designed for real-time leak detection rather than non-contact analysis.

Purchased in 2005, this camera has been central to Fashimpaur’s troubleshooting work. He said: “There’s no set-up involved. When you switch the camera on it has to cool down to the required temperature but after that you get your images immediately.

“There’s no post-processing involved and I just play the video footage back via Windows Media Player.”

The camera allows him to inspect wide areas efficiently and to pinpoint the source of a leak.

Fashimpaur added: “I’m looking for motion in the black-and-white image. Of course that could be steam or metal tags waving in the breeze so my judgement is informed by experience but by changing the lens I can capture the complete scene or a small detail.”

The 25mm lens is the most popular but Fashimpaur also has 50mm and 100mm for longer range inspection.

This was one of three FLIR GasFindIR cameras recently employed to check plant integrity at the Saltend site.

Fashimpaur used his HSX model to detect a range of gases, including methane and methanol that are both predominant at the UK plant; HSX is able to detect 20 different gases in total.

In addition, a long-wave (LW) version of the camera was used that is capable of detecting acetic acid, acetic anhydride and ammonia, three of the total of eight products processed at Saltend.

Completing the set was a brand new camera in the FLIR GasFindIR range.

This model is specifically designed to detect carbon monoxide, CO.

To a greater or lesser degree, the majority of process gases at BP Chemicals are hazardous but CO is certainly in a class of its own.

Even in the low parts per million it can cause serious health problems and BP ensures that any of its personnel that could potentially come into contact with CO carry personal monitors at all times.

The carbon element of CO is obviously a potential environmental problem too so the detection of any leaks is doubly important.

All three cameras pinpointed several gas leaks.

In the case of the FLIR GasFindIR HSX camera there had been some previous evidence of leakage at the plant entry point for natural gas from which carbon monoxide is produced.

To enhance safety, odour is added to the natural gas.

CS Chung, a process engineer, said: “We were able to smell the leak but didn’t know its exact location.”

The HSX camera found the culprit to be a leaking flange that has since been tagged for repair during the next maintenance shut down.

One of the main sources for the natural gas used in the process is the BP terminal at nearby Dimlington.

The site processes in the region of 900 million standard cubic feet of North Sea gas daily.

The infrared survey at Dimlington confirmed more than 99% of components were leak-free. However the HSX camera was able to trace the source of an odour at a condensate sump and small leaks around compressor flange plates.

This FLIR GasFind HSX camera is designed for outdoor use.

For that purpose it comes complete with selectable frame acquisition rates to suit the ambient temperature.

Too great a heat results in a saturated image and too cold, insufficient detail.

This feature ensures optimum performance whatever the ambient temperature so that the FLIR GasFindIR can be used with equal efficiency for inspecting hot compressors or sites characterised by permanent ice.

Unlike other gases at Saltend, CO doesn’t have the advantage of odour and therefore unless the emission exceeds the alarm setting of a personal monitor or a fixed detector, a leak will remain undetected.

The first small escapes that the FLIR GasFindIR CO camera found were from an infeed pipe and a heat exchanger flange, both part of an electrically driven compressor.

From a gantry in an adjoining covered section of the plant, the camera was then used to inspect a series of steam driven compressors.

Two further CO leaks were found. In high-sensitivity mode both were clearly visible as plumes of gas. “

The FLIR GasFindIR LW was primarily developed for the detection of the greenhouse gas, sulphur hexafluoride (SF6), but its wider capabilities made it a good choice for BP.

It can also ‘see’ acetic acid and therefore provided clear images of small emissions from the vapour space in tankers and from a vent in the roof of the loading bay.

It also identified small escapes from automatic loading arms whose emissions are largely controlled by recovery systems.

Ammonia is another gas detectable by this LW camera and this was seen in a vent situated 20m above ground level with the camera position at a distance of 150m or so.