Safety PLC Burner Management System
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Industrial Accident: a boiler explosion (puff) destroyed a large industrial steam generator. The gas-fired burner was controlled by a new stand-alone burner management system (BMS) that used an ISA 84 Safety Instrumented System (SIS) design with a safety PLC. The BMS interfaced with a non-SIS plant-wide Distributed Control System (DCS) that should have regulated fuel flow only after the burner flame was ignited and proven. Excess fuel in the fire box exploded following repeated attempts to light the burner from the DCS operator control panel.
The forensic investigation involved hardware and software analysis on the safety PLC and its interface to the DCS. Relevant aspects of ISA 84 and NFPA 85 were analyzed in regard to the stand-alone BMS and the DCS with which the BMS interacted during and after the light-off sequence.
Additional information on boiler/burner-related engagements can be found here.
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