Eskom warns Kusile unit will be offline for months after chimney failure

Eskom has revealed that a section of the Kusile unit 1 flue gas duct has failed and could remain offline for months.

The power utility explained that the duct is similar to a chimney, providing a channel for exhausting gases from the power station.

On 23 October 2022, a section of the duct exiting the sulphur dioxide absorber failed on the horizontal rubber expansion joint and compensator.

“[The compensator] is a bend to direct flue gas up the [duct] and allow for thermal expansion of the chimney,” Eskom explained.

Eskom said the failure happened while unit 1 was on forced shutdown for flue gas desulphuration recirculating pump repairs.

“Investigations and assessments are in progress to establish the cause of failure and to ascertain the extent of the damage, as well as the recovery scope of work,” Eskom stated.

“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.”

Eskom said access to the area had been restricted as part of precautionary measures.

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

Eskom explained that the failed section of unit 1’s 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 unit 3 flue gas ducts, it said.

Unit 2 was offline at the time of the failure, while unit 3 was generating electricity. Eskom will keep this offline for the time being, as a precautionary measure.

Unit 4 is currently providing its full capacity to the national grid, and its flue gas desulphurisation duct is housed in a separate chimney.

“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,” Eskom said.

Eskom is currently implementing all-day load-shedding after increasing power cuts from Wednesday morning to preserve emergency generation reserves.

Its reserves consist of diesel for its open-cycle gas turbines and water housed in dams at pumped storage schemes.

Now read: Moody’s upgrades Eskom debt outlook to positive for first time since start of load-shedding

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Eskom warns Kusile unit will be offline for months after chimney failure