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FLIR’s thermal-imaging technology has the ability to monitor stored material that has the potential to self-combust. Of particular relevance to the mining industry, the technology is being used by companies such as the Dangjin Coal-Fired Power Complex (DGFPC) in South Korea, the Nástup Mines Co-operation in Tusimice, Czech Republic, and Dutch bulk-handling company OBA to ensure the safe handling of coal.

Averting coal self-combustion with FLIR thermal imaging

Coal starts to oxidise when exposed to air and this causes a rise in temperature. Initially, this is slightly above ambient temperature but if left unchecked it can rise to more than 400°C, causing the coal to burst into flames.

During the pre-combustion oxidisation process, the coal can also produce large amounts of methane and carbon monoxide gases. These toxic and explosive gases can make it harder for fire-fighters to control any subsequent fire, so early detection of any temperature rise is vital.

Thermal imaging acts as an early-warning system by spotting any abnormal rise in temperature before any fire breaks out. A fixed mounted camera can be used economically to constantly survey an indoor or outdoor area day and night, in rain or snow and through fog and smoke. Not only does it provide an early warning of potential fire; it pinpoints its source too.

To transport coal to its boilers, the DGFPC uses a belt conveyor of several kilometres in length. It is especially important that the coal’s temperature is continually monitored during transportation as movement increases its potential for spontaneous combustion.

To protect assets and personnel and ensure continued productivity, DGFPC installed several fixed mounted thermal-imaging cameras. These devices detect the slightest rise in temperature and automatically trigger an alarm and activate an automatic sprinkler system. This is possible because the type of camera the plant’s management chose has multiple I/O ports.

One of the cameras is installed in the coal store, recording the temperature of the material as it enters the conveyor system. As the coal is transported to the boilers, at a speed of 4m per second, several additional cameras check its temperature in transit. All are connected to a TCP/IP network using a standard Ethernet cable. Through the network, the thermal data is shared with a programmable logic controller that immediately stops the conveyor belt and activates the sprinklers when the camera triggers the alarm.

A similar system is used by the Nástup Mines Co-operation to continually and automatically monitor a coal pile that occupies a site approximately 800 x 200m in size. For the purpose, the five cameras are mounted on steel masts at strategic locations around the site. The thermal data they collect is transmitted via 3km of fibre-optic cable to the control room.

The cameras are configured to generate a direct alarm output to an operator if the pre-determined temperature threshold is exceeded. An acoustic alarm and display on the control room monitor concurrently draws the operator’s attention to the location of the potential spontaneous fire.

The ability to monitor piles of coal rather than rely on spot measurement was also the reason why OBA opted for fixed mounted thermal imaging. The company operates two terminals in the port of Amsterdam for handling a variety of commodities including biomass and coal.

Several European countries impose additional requirements for the transportation of coal. A multilateral agreement makes it mandatory for the temperature of a coal load — before, during and after the loading process — to be below 60ºC. Accordingly, every ship load of coal that leaves the terminal to Germany, for example, needs to carry a valid temperature monitoring certificate. The company used to outsource this job, which added costs to the operation, but thanks to its investment in thermal imaging OBA can now perform that task itself, adding value to the service it provides.

The technology is now used to visualise the entire stretch of conveyor belts from coal store to ship, a distance of around 900m. This allows coal temperature to be monitored up to the last moment before loading. The thermal video images are sent over IP to a central control room where they are continuously monitored. A proprietary software system provides a colour-coded visual guide: green indicates a safe temperature; amber, rising temperature; and red, danger of self-combustion.

OBA also uses handheld thermal-imaging cameras to regularly determine the temperature of its storage coal piles. They also give site engineers greater intelligence in the event of an amber warning from the control room. The fixed cameras determine the location of the potential problem and handheld versions provide the means for further investigation. And as thermal imaging is a non-contact technology, it allows the job to be done without compromising personal safety.

FLIR Systems specialises in technologies that enhance perception and awareness.  The company brings innovative sensing solutions into daily life through its thermal imaging and visible light imaging technology and systems for measurement, diagnosis, location and advanced threat detection.  Its products improve the way people interact with the world around them, enhance productivity, increase energy efficiency and make the workplace safer.

FLIR Systems has six operating segments – surveillance, instruments, OEM and emerging markets, maritime, security and finally, detection. Of these six, ‘instruments’ is of greatest interest to trade and industry and the second largest segment in the company’s portfolio. This division provides devices that image, measure and assess thermal energy, gases and other environmental elements for industrial, commercial and scientific applications.

These products are manufactured across five production sites, three in the USA and two in Europe; Sweden and Estonia.

A model to suit every application and budget
The options that FLIR Systems provides for measuring temperature and studying thermal performance have never been greater.  Not only does the company offer a huge range of models to suit all thermal application needs but the technology is also affordable and very easy to use.  Thermal cameras now come in various shapes, sizes and degrees of sophistication and FLIR continues to invest heavily in the development of new and complementary technologies to differentiate itself from competitors.

An important milestone in the development of thermal imaging has been the introduction of the FLIR Lepton® core, a micro longwave detector, the size of a mobile SIM.  This has allowed thermal imaging to be repackaged to meet the needs of an even wider audience and, in combination with another new technology called Infrared Guided Measurement – IGM™ – has led to the development of a range of test and measurement meters with imaging capability.

Another important growth area for FLIR thermal imaging is in continuous monitoring to assure quality and safety.  Through its introduction of discrete fixed mounted thermal cameras which are fully compliant industry standard plug-and-play protocols, FLIR Systems has provided industry with infrared machine vision which is instantly ready for quick and easy network installation.

Protecting assets and people from fire is an area for which thermal imaging is least known but, thanks to FLIR Systems’ development, it is now one of the most cost-effective methods available.  Its application flexibility and rapid return on investment present an attractive proposition for any site or safety manager.

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