A fire broke out at 4:15 p.m., in a non-hazardous waste incineration and energy recovery plant. The fire was located in the lower part of the fume extraction duct in the clinker area and spread over the entire height of the duct opening on the plant’s roof. The incineration line involved was shut down, and the power supplies were cut as a preventive measure. The operator informed the neighbouring plants while the site’s designated firefighting personnel fought the fire with the available fire extinguishers and hoses. The deployment of fire hoses on the upper floors proved to be difficult. Nevertheless, the fire was extinguished at 4:45 p.m. The fire brigade was called as a precaution but did not need to intervene. They requested that the 6 m³ of waste involved in the fire be evacuated and sprayed down with water.

Consequences and post-accident follow-up

The waste that had been sprayed down was returned to the pit for processing once all risk of a renewed fire had been eliminated. An employee was taken to the hospital for safety reasons, having suffered from smoke inhalation. The incineration line was put back into service the next day.

Causal analysis

In the early afternoon, a blockage was reported in the clinker extractor and was being resolved by the operations team. The clinker extractor is the element that receives and cools the clinker before removing it from the furnace. This jamming was the result of a weld failure on the water jacket of the waste inlet chute. As a result, the leaking water spread over the grate and wet the waste still present in the furnace, causing degraded combustion. The unburnt waste created a blockage in the clinker extractor. This required that the extractor’s liquid seal be drained in order to remove the waste. While clearing the blockage, incandescent waste exited the extractor and started a fire on the plastic strips present at this level. The fire then spread to the fume extraction duct of the clinker area, also made of plastic. According to the facility operator, the incident could have been avoided had the technician, ordinarily present at the extractor exit, been at his workstation. His role was to monitor the quality of outgoing waste and to extinguish any incandescent elements.

Measures taken

In order to avoid a similar incident, the operator:

• installed a metal duct for the extraction of clinker fumes existing facade of the plant instead of on the roof;
• removed the plastic strips on the extractors;
• installed a flame detector on the clinker extractors;
• added fire hoses on the upper floors of the unit;
• modified the extractor’s emptying system;
• created an operating procedure requiring that a technician be present at the exit of the extractor when waste blockages are being cleared.