In a starchy product plant transforming by-products into animal food, the co-product dryer was restarted around midnight subsequent to maintenance operations requiring hotspot work. During this start-up process, fire broke out at the dryer and the electrical tracing ducts. Staff extinguished the fire and switched the tracing at the electrical cabinet. Steam was then introduced for 2 minutes into the dryer, whose fans were turned off by employees. At about 2 am, they noticed smoke exiting from both the cooler located downstream and the main filter exhaust (250-m³ bag filter). At 3 am, the safety crew set up water nozzles to flood the cooler. At 3:50, following thermal camera inspections, the team manager assessed the fire to be well under control. As a precaution, the nozzles were left in operation and more steam injected for 6 min into the dryer. At 6:30 am, once the dust removal circuit had been started up by opening a valve, the logistics specialist turned on the co-product loading conveyor. Fire broke out at the main filter. The operator activated the internal emergency plan at 6:40; fire-fighters drained the dust via a worm screw set up at the bottom of the filter. They relied on 2 variable-rate nozzles to extinguish incandescent particles on the 3rd floor and cool equipment on the 4th floor. The internal emergency plan was lifted at 10:05 am. Some 15 min later, fire-fighters reset the worm screw, which had been locked in place. They proceeded with a final thermal camera inspection. No injuries were reported and no redundancies planned. The filter was slightly damaged, and the installations could be restarted the next day.

When the dryer was turned back on and due to the presence of still incandescent particles after hotspot work, the dust deposited inside the pipes ignited and spread to the electrical tracing ducts. The main filter still contained embers that subsequently ignited through the air inflow generated by start-up of the dust removal system, or else embers found in the settling pot were suctioned, triggering fire in the filter sleeves.

In response to an analysis of this accident, the operator adopted the following measures: drawing up a checklist for cases of smoke or fire detection; developing a detailed list of dust removal network items to be inspected during long downtime periods within the targeted zone; building inspection hatches on the horizontal parts between cyclones, fans and the firebox; studying the possibility of injecting steam into the filter and installing a spark sensor along with a temperature probe; creating a procedure for starting the dryer; incorporating this type of accident into the internal emergency plan; and allocating 5 min for the injection of inerting steam when operating in manual mode.