Rembe GmbH Safety + Control
Woodchips and pellets are the most important non-fossil fuels and are even burned in conventional coal-fired power stations. Woodworking processes account for around 28% of industrial explosions making them the most dangerous in any industry in terms of frequency. Explosions in food processing plants come a close second at just under 27%. In contrast, only 10.5% of explosions occur in the coal sector.
"Explosions require three ingredients – a fuel (e.g. combustible dust), oxygen and a source of ignition," says Dr. Johannes Lottermann. These "perfect explosive conditions" are to be found in virtually all woodworking operations from chipboard plants to sawmills. Silos, sieves, dryers and other facilities contain wood dust and oxygen while moving parts and drying processes provide ignition sources such as sparks or hot surfaces.
Preventive explosion protection concepts seek to reduce the probability of an explosion occurring by stopping the accumulation of explosive dust particles and/or eliminating sources of ignition. Yet none of these measures – either alone or in combination – provides 100% protection. "This is why it is essential to install measures, e.g. in accordance with BGI 739-2, that protect against the consequences of explosions in virtually all woodworking plants," explains Lottermann.
A number of different approaches are available:
- explosion-proof construction, i.e. the plant can withstand an overpressure of up to 10 bar
- explosion relief: the pressure of the explosion is relieved precisely via predetermined breaking points – for example through a bursting disc
- explosion suppression using rapid reaction fire extinguishing systems
In complex plants, it is also advisable to install explosion isolation measures that prevent damage being caused to upstream or downstream units by flames or pressure.
Lottermann advises that the risk of explosions in woodworking plants is a major issue and should be given top priority. A competent partner should therefore always be consulted in the development of effective protection concepts.
"We must raise awareness of the dangers of dust explosions in woodworking plants," says Lottermann. "It is the only way to prevent catastrophes that endanger the lives and health of workers and jeopardise the plant productivity and profitability. Operators often ignore the long-term consequences of an extended production standstill: customers seek out alternative suppliers as a short-term solution – and never return."