8 Safety
Optical Gas Imaging Camera Helps Improve Environment and Safety at Borealis Stenungsund
Steve Beynon, Business Development Manager EMEA for GF Cameras & Optical Gas Imaging at FLIR Systems Tel: +44 1604 641180 • Email:
steve.beynon@
flir.com
Many petrochemical plants handle invisible gaseous hydrocarbons. Most of these gases pose some sort of safety aspects. Tey may be toxic, or can cause health issues in case of long term exposure. Others are highly flammable, explosive even, and most of them will have a negative impact on the environment if they enter the atmosphere in large quantities. Tat is why leak detection is of vital importance in these petrochemical plants.
One of such plants is the Borealis high-pressure, low-density polyethylene (LDPE) plant in Stenungsund, Sweden, which produces LDPE products for the cable and wire sector and has an annual production capacity of 350,000 tonnes. The Borealis cracker facility delivers the main ingredient: ethylene, which is converted into polyethylene in a high-pressure polymerisation process.
Ethylene is a highly flammable hydrocarbon. To further increase the safety within the plant and reduce the environmental impact, Borealis has purchased an optical gas imaging camera from FLIR Systems. With this gas leak detection tool Borealis ensures that no gas leak escapes the attention of the process operators.
This doesn't mean that they stopped using sniffers altogether, stresses Schiller. "We use the sniffers alongside the optical gas imaging camera. We use the optical gas imaging camera to detect the leak and then use the sniffer to quantify the leak." Schiller was surprised to see how sensitive the FLIR GF306 optical gas imaging camera turned out to be. "I detected leaks where the sniffer gave a reading of below 100 ppm, especially when operating in the High Sensitivity Mode this camera is surprisingly sensitive, it can be used to detect even smaller gas leaks from about seventy meters. This enables the operator to perform these inspections from a safe distance."
High Sensitivity Mode
The High Sensitivity Mode (HSM) is a special feature included in all GF-Series optical gas imaging cameras. It is an image subtraction video processing technique that effectively enhances the thermal sensitivity of the camera. The HSM feature subtracts a percentage of individual pixel signals from frames in the video stream from the subsequent frames, thus enhancing the differences between frames, which helps leaks stand out more clearly in the resulting images.
Shift supervisor LDPE Jan Åke Schiller was skeptical at first, but is now convinced of the potential of optical gas imaging cameras.
Leaks show up in the optical gas imaging footage as a smoke like vapour
An optical gas imaging camera is a quick, non-contact measuring instrument that can visualise gas leaks in real time. Where many other measuring instruments only present the inspector with a number, optical gas imaging cameras present visual information, making the leak detection process more intuitive. Optical gas imaging cameras can also be used in hard-to-access locations, since they can detect small leaks from a distance. "When we started testing this relatively new technology I was at first very skeptical", says shift supervisor LDPE Jan Åke Schiller. "But seeing these optical gas imaging cameras in action I quickly realised that they had an immense potential for leak detection here at the polyethylene plant and in petrochemical plants in general."
Advantages of optical gas imaging
Before the purchase of a FLIR GF306 optical gas imaging camera Schiller and his colleagues used so-called 'sniffers', devices which measure the concentration of a certain gas in one single location and generate a concentration reading in parts per million (ppm). "The main advantage of the optical gas imaging camera is that it provides you with the possibility to detect gases visually", says Schiller. "Where sniffers just give you a number, an optical gas imaging camera allows you to detect gas leakage anywhere within the field of view of the camera. This speeds up the inspections considerably. Now that we have the optical gas imaging camera we do a quick scan at every startup. With a quick scan we cover approximately 80% of the entire plant in about thirty minutes. You would need a team of ten people with sniffers to work for two full days to reach the same result."
A sniffer must be held in exactly the right spot to detect a gas leak. Optical gas imaging cameras can detect gas leaks anywhere within their field of view.
All leaks to be repaired are reported to the maintenance crews. In this part of the process the use of optical gas imaging cameras also has an advantage over sniffers, according to Schiller. "When you are using sniffers you have to describe the exact location of the leak using words which can be difficult sometimes. With the optical gas imaging camera we can simply attach a video file to the work order and the maintenance crew will see for themselves where the leak is located. This allows me to spend less time on generating leak reports and more time out in the plant, detecting leaks, or performing other duties."
Higher inspection frequency
Due to the fact that these inspections are much less time consuming now that he uses the FLIR GF306 optical gas imaging camera the leak detection frequency has increased significantly, according to Schiller. "When we only had sniffers we did other yearly inspections. To cover all of the pipework that this plant contains, which is all in all over 100 kilometres in length, it takes a
Polyethylene is used to produce a wide variety of plastics, from wiring insulation to car dashboards.
In the control room all gas flows throughout the plant are closely monitored.
The small gas leak detected with optical gas imaging camera is quantified with a sniffer. As the concentration is below the threshold this leak does not get a high priority.
APRIL / MAY 2013 •
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