Inadequate process safety led to Queensland clinker explosion, report finds

AN INVESTIGATION into a generator explosion at a coal-fired power station in Queensland, Australia, has identified several process safety shortcomings that contributed to the incident.

State-owned CS Energy has released an incident report detailing the explosion in the C3 boiler unit at its Callide Power Station site on 4 April.

The power station comprises two plants, Callide B and C, each with two generating units: B1 and B2, and C3 and C4.

The report outlines the causes of the explosion and steps to improve safety. The power station, which suffered an explosion at the C plant in 2021, was found to have “ineffective” clinker management, design flaws and gaps in operator training.

Brian Gillespie, CEO of CS Energy, said: “The CS Energy leadership team acknowledges that what happened on Unit C3 was not good enough. We have a new leadership team who is listening and acting.”

Design and management issues

Callide C3 has a maximum capacity of around 466 MW and was expected to stay open for more than a decade, reports The Australian.

The incident was triggered when a large clinker broke away from the unit’s furnace wall and released steam as it fell into the water hopper of the Submerged Chain Conveyor (SCC).

Although no one was injured in the explosion, the report found that pressure from unburnt pulverised fuel in the unit furnace could have caused serious harm to anyone nearby.

CS Energy’s investigation – using Root Cause Analysis (RCA) and the Incident Cause Analysis Method (ICAM) – identified 37 operational failures.

The root cause was poor clinker management, particularly around deloading, with further failures in flame detection equipment contributing significantly. Additional factors included gaps in process safety training, staffing shortages, weak safety leadership and inadequate maintenance.

Learning experience

Among the report’s 22 recommendations, CS Energy highlights operationalising process safety as a key priority, focusing on practical frontline tools, signal awareness, reporting and execution of critical controls.

The company says the recommendations revealed “deeper organisational and cultural issues” that must be resolved to restore confidence in the plant.

CS Energy stated: “This investigation confirmed that the incident was not isolated or unforeseeable, but the result of long-standing and systemic weaknesses in technical safeguards, operational controls, leadership oversight and safety governance at CS Energy.”

Gillespie said that the company has already completed several actions in response to the report, with new management in place.

He said: “CS Energy worked closely with Workplace Health and Safety Queensland to meet their requirements for the continued operation of Unit C4 and the safe return to service of Unit C3. All technical root causes (clinker management, boiler protection systems, combustion systems and coal quality) have been rectified.”