Unit at Kusile power station expected to remain offline after duct failure

Unit 1 at Eskom’s Kusile power station is expected to remain offline for a few months after a duct failure.

The power utility said on Wednesday that a section of the Kusile unit 1 flue gas duct (similar to a house's chimney) exiting the sulphur dioxide absorber failed on the horizontal rubber expansion joint as well as the compensator (a bend to direct flue gas up the chimney and allow for thermal expansion of the chimney).

The failure occurred on October 23 while the unit was on forced shutdown for flue gas de-sulphuration recirculating pump repairs.

Eskom said investigations and assessments are in progress to establish the cause of failure and extent of damage.

“While it is uncertain at this point, it is anticipated the unit may remain offline for a few months and this duration shall become clearer over the next few weeks. Access to the area has also been restricted as part of precautionary measures,” it said.

Consultations with various specialist stakeholders, including the original equipment manufacturer, are in progress to determine the best course of action to restore the plant as quickly as possible.

The failed section of the Unit 1 flue gas duct is located inside the flue chimney.

The ducts are made from steel sections welded together and surrounded by a windshield, which is made of reinforced concrete that also houses the unit 2 and 3 flue gas ducts.   

The power utility said unit 2 was offload at the time while unit 3 was generating electricity. Unit 4, whose FGD duct is housed in a separate flue chimney, is currently on load generating full load to the national grid. 

“As part of precautionary measures put in place, the return to service of unit 2 has been put on hold while unit 3 continues to run at stable load.”

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