Fire safety: prevention is better than cure

Kuchl, 29.08.2016

Peter Streinik, UNTHA’s head of business unit waste, recently authored an article for Recycling Today. He was asked to look at the combustible nature of materials present within typical Energy from Waste (EfW) streams, and the extent to which this makes alternative fuel production plants vulnerable to fire. He then went on to look at what can be done to mitigate the risks and prevent potentially devastating blazes from breaking out. If you missed the resulting article, you can read it in full, here…

“The risk of fire or explosion within the inherently hazardous EfW industry cannot be ignored. In fact, it is a commonly quoted statistic in Austria, for example, that one in five waste plants will be struck by a fire in its lifetime.”

Specially-engineered technological solutions – tailored to the plant concerned – are therefore becoming increasingly important. More needs to be done to suppress fires before they can take hold.

So what can shredder manufacturers do? Is it possible to equip waste processing technology so that they can ‘fight’ the fire?

Yes. Carefully positioned UV, infrared, heat and spark detectors on a shredder’s inlet hopper and discharge conveyor, for example, can instantly sense when a fire is likely to begin. In the event of a significant temperature increase, extinguishing nozzles, strategically positioned in the same place as the sensors, can automatically spray a controlled amount of water onto the targeted area. This means that, if the risk is within the shredder, the materials can be cooled and/or the fire put out before anything is discharged from the machine. If the problem is on the conveyor, the nozzles prevent hot, glowing fractions from entering the pile of output material, where a fire could otherwise propagate. An alarm can even be activated to enable an operator to start a manual extinguishing process, and/or alert the fire brigade.

Explosions are somewhat different. These can be caused if a foreign object such as an aerosol tin bursts due to heat or compression, or if a small electrical spark creates an ignition when it reacts with high volumes of dust. To prevent such scenarios, more responsible equipment manufacturers are further reducing risk ‘by design’. Some EfW shredders, for example, are now purposefully engineered to have a slower rotor speed, without compromising throughputs. As a result, they don’t generate as much dust and the lower tip speed means the potential for a spark is lessened.  Anti-explosive Atex-specification motors and electronics can also be installed.

Of course, the shredder cannot solve every fire risk. The storage of readily-combustible, mixed input waste materials is often the root cause of a blaze, for example, hence why sprinkling systems must be installed throughout such facilities. And robust cleaning regimes should be deployed throughout the day to rid the wider facility of dust and debris, thus minimising the likelihood of a fire outbreak.

However, with a wealth of expertise to hand, plant manufacturers need to ensure they play their part.

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