Pollution
Humain
Environnement
Economique

At around 5:30 p.m., the flue-gas cleaning system of a debinding furnace at an auto parts company caught fire during a pyrolysis operation. The fire was under control by the time the firefighters arrived. The site’s 50 employees were evacuated. The fire was extinguished at around 7:25 p.m. The employees returned to the site. A similar accident occurred at the same site in November 2017 (ARIA 50636).

Malfunction of a flue-gas cleaning catalyst (VOC)

The operator’s analysis of the event’s causes revealed a problem with monitoring and maintenance of the furnace catalysts. In order to play their full role, the catalysts must be heated by an element to 400 °C. Unfortunately, on the day of the accident, the element short circuited. The insufficient operating temperature allowed tar deposits to build up. These deposits ignited due to the propagation of heat fluxes from the pyrolysis operation underway in the furnace.

Although the operator had noticed in the past that the catalyst had an abnormally low temperature, this did not prevent him from carrying out pyrolysis operations in the furnace. Furthermore, staff likely to work on the furnaces had no knowledge of the temperature readings because they were not communicated internally.

Environmental consequences

When the catalyst malfunctioned, it generated smoke that contained out-of-limit VOC concentrations. These releases lasted for several weeks.

Measures taken

The inspection authorities for classified facilities asked the operator to provide it with:

  • a fault tree for each accident (ARIA 50636 and 50827);
  • the furnace restart/shutdown procedures and the pyrolysis procedure;
  • the in-house procedure for recording and taking into account furnace parameters (including the catalyst temperature);
  • the procedure for removing or bypassing alarms;
  • the results of the air-quality measurements.

Lastly, the operator stepped up monitoring of the catalysts pending the implementation of another smoke treatment technique.