A fire, followed by an explosion, occurred on a drying line of an alfalfa dehydration plant specialised in the production of animal feed. A blockage was detected on the drying line lock at around 8:30 a.m. The operator stopped the hot air and alfalfa supply, automatically causing the hatch to open on the drum’s inlet. These actions allowed the cyclone to be unclogged. A few minutes after the system was restarted, the operator noticed that the hatch was not closed properly. The associated sensor was no longer operational. Embers were visible at the drum’s inlet, and the plant was again shut down. The operator attempted to spray down the embers, but the hoses were not operative because the two 60 m³ fire reserve tanks were empty. The operators extinguished the embers by connecting to the drinking water network (low flow rate). A second blockage was detected at the cyclone unit, preventing the line from restarting. While on their way to the site to clear the cyclone, the operators noted wisps of smoke and embers inside the unit. They began spraying water while also trying to unclog the system, but a product collapse caused an explosion to rip through the cyclone. The blast caused the cyclone’s vents to rupture. The blast spread inside the drum, passing through the open hatch and causing some roofing elements to fly off. The operators stopped the unclogging operation, exited the plant and called the fire brigade at 12:34 p.m. Upon arriving at the site, they were able to extinguish the fire in the cyclone and the fumes caused by the incandescent ashes that had spread throughout the plant due to the high dust content. The fire was brought under control at around 1:30 p.m. The site was shut down, and the power was disconnected.

The emergency services alerted the prefecture, which informed the Classified Installations Inspectorate. The fire would have been brought under control more quickly had the emergency services got there earlier, as they had the necessary equipment to connect to the site’s flexible 200 m³ tank. The fire brigade noted that this was the fourth incident at the site in a year, and the Inspectorate stated that it had never been informed.

The damage was only material: vents and some roofing panels to be replaced, damaged to the trap door, cable tray to be cleaned, for a cost of €19 k. The extinguishing water was confined in the lagoon, 5 t of non-compliant alfalfa, classified as bio-waste, was sent to a methanisation plant. One operator reported redness on a calf.

Following this accident, the Inspectorate asked the operator to clean the plant before restarting thoroughly. The extinguishing water was to be analysed and then treated according to the results. The Inspectorate also reported that the tanks are exclusively dedicated to fire reserves and must be filled and their volumes monitored daily. As the site’s danger study only considers the site’s storage facilities, the Inspectorate asked the operator to update it for the site’s dehydration/granulation operations. The operator should also review its accident procedures, particularly in calling emergency services and reporting information to the Classified Installations Inspectorate. A draft for an additional prefectoral decree was also proposed to manage these measures.