The incident occurred on October 29, 2020, just after 8 a.m. at the new Kronospan OSB manufacturing plant.
It was confirmed that the explosion occurred in one of the halls where raw material (wood chips) used for the production of OSBs was prepared. Part of the technological installation and the adjacent hall were also engulfed by the flames. According to unofficial reports, two large filters as tall as a two-storey building were engulfed by the flames, and the entire installation caught fire from the inside. The company commented on the incident: …we stress that none of our employees were injured. Our plants are equipped with specialized firefighting systems, which were activated and significantly reduced the scale of the fire…’, said Marlena Bogdan-Marut to the media.
Fortunately, firefighters were able to quickly reach the site of the incident, as the nearest station is just a few kilometres away. Firefighters were at the scene only minutes after they had received a report of three explosions at the Kronospan site. They had already been alerted by the enormous bang of the explosion which could be heard even on the other side of Strzelce Opolskie, as described by witnesses.
The explosion was followed by a fire, which caused thick smoke to rise over the destroyed hall for several dozen minutes. Firefighters were able to bring the fire under control just before noon. The hall where the incident occurred has been destroyed. Fortunately, all 112 employees working in the danger zone were able to escape from the affected areas prior to the arrival of the fire brigade.
As a representative of WOLFF GROUP, Zbigniew Wolff assisted in ensuring the protection of multiple installations operated by businesses from the woodworking industry against explosions. Wolff explains that explosions are not an infrequent occurrence in this sector. On the contrary, the number of such incidents is relatively high compared to other industries. According to sources, wood dust is responsible for up to 30% of all industrial explosions.
Wolff goes on to explain that it will probably take some time to determine the causes of today’s incident. However, our experience shows that wood dust explosions usually occur in dust extraction units (filters/cyclones), bucket elevators, silos and scraper and belt conveyors..
There are many factors that can lead to the ignition of an explosive atmosphere. However, past experiences show that special attention should be paid to flameless fires, which can occur in equipment such as scraper and belt conveyors. These fires begin with small incipient fires, caused by saw dust coming into contact with an overheated component of the conveyor – most frequently as a result of friction caused by a malfunction of the device. These incipient fires are extremely hard to detect and can cause an explosion or fire directly inside the conveyor or be transported to other equipment where they can cause an explosion and/or fire.
Ignition sources are also likely to occur in pneumatic conveying systems. In this case, damaged fans or static electricity can create sparks that will be transported to different areas of the production facility, posing a huge hazard.
The force of a wood dust explosion is enormous. However, we are not defenceless in the face of this hazard. The ATEX Directive applicable in this area stipulates that three methods of protection must be used:
- elimination of explosive atmospheres
- imiting ignition sources
- limiting the effects of an explosion
It is difficult to eliminate dust or use effective inerting in the woodworking industry, so there is not much we can do about the first item. However, we do have several options available when it comes to items 2 and 3. A range of solutions can be used, starting from systems used for detection and extinguishing of incipient fires, moving on to the use of effective dust extraction systems, and ending with the use of systems that minimize the effects of the explosion, such as explosion suppression, relief and decoupling.
To conclude, I would like to comment on the dust extraction systems that I touched upon before. There is a misconception in the industry that these systems eliminate the risk of explosion. However, extraction systems can only reduce the risk of an explosion in areas where dust is extracted. This does not mean that the risk is eliminated, it is merely transferred to the dust extractor. This is why it is so important to protect this type of equipment against the effects of an explosion.