Pollution
Humain
Environnement
Economique

Shutdown since the day before in order to change a boiler joint, the surfin alcohol production unit of a distillery restarted at 10.30 am. During the process, the installation’s alcohol vapours and non-condensables were sucked up by the vacuum pump and entered a scrubbing column. The circuit was equipped with an air intake control valve 1 m upstream of the pump. The pump tripped at 12.50 pm, 5 minutes before the technician noticed on site fires breaking out on the thermal insulation foam above the pump and in the alcohol vapour and non-condensables suction pipe. The electricity was cut off and the manual valves on the pump discharges were closed. The technician, 5 site firefighters and 3 other members of staff intervened using 3 powder extinguishers, and cooled the vacuum pump using 1 nozzle.

The vacuum pump, manual valves, automatic valve and the electrical installation were dismantled to determine the cause of the fire. The section of circuit located between the pump and the air intake valve had turned quite blue and the metal was torn on the ‘non-condensables inlet’ volute.

On the day of the accident, the pump that had been running for 2 hours overheated following malfunction of its cooling system. At the same time, a leak on the air intake control valve, according to the technician, allowed the emission of alcohol vapours which then ignited on contact with the hot pump. Following the fire, the operator added a flowmeter to the vacuum pump’s cooling water make-up system and 2 temperature sensors on the pump’s backflow and on the alcohol vapour and non-condensables suction system; these 3 measuring devices were connected to an alarm in the control room.