FL Utility Blast: Accident Waiting to Happen

Wednesday, May 31, 2017 @ 01:05 PM gHale


Well over two years ago, before the violent rupture of a highly pressurized metal tube crippled the Lakeland, FL-based Lakeland Electric’s McIntosh Unit 2, a plant worker had filed a request to replace worn tubing in the area where the April 26 failure occurred.

Those repairs were never made.

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The high-pressure explosion on Unit 2 happened April 26 at 1:17 p.m., launching debris and steam as superheated water rapidly released from the high-pressure system.

Two contract workers in the vicinity of the blast were covered with mud and soot, but there was no evidence of burns or injuries, Lakeland Electric General Manager Joel Ivy said at the time. Regardless, the workers were sent to the city’s in-house clinic for checkups.

Eight years and two months before the accident, a technical consultant inspecting recent work done inside Unit 2′s boiler recommended the utility perform a deeper metallurgical analysis on its pressurized parts if Lakeland Electric intended to continue subjecting the then-33-year-old generator to a high degree of operational stress.

That analysis was never performed.

Within the next 10 years, Lakeland Electric, like many utilities around the country, will be making important decisions about how to modernize its generators and continue producing power for customers into the future.

In the world of electric utilities where decisions have $100 million stakes, the ability to wait is a benefit. In an environment where technological improvements and regulatory changes can mean decades of benefit, more time is always an advantage.

In the meantime, utilities have to continue maintaining their aging plants. In the U.S. the average age of a generator, weighted to the individual unit’s size, is almost 30 years, according to U.S. Energy Information Administration data.

Lakeland’s three most important generators, Units 3 and 5 at the C.D. McIntosh Power Plant and Unit 8 at the Larsen Memorial Power Plant, were started in 1982, 2001 and 1992, respectively. Part of Larsen Unit 8 was built in 1956.

No one was injured by the sudden explosion caused by superheated water flashing into steam, twisting metal and throwing debris. About 15 minutes prior to the failure, plant workers had been gathered near the blast zone.

The incident, coming during a year of unrelated mechanical troubles for the city-owned electric utility, shook Lakeland Electric and city officials. Lakeland Electric management told the city Utility Committee they will reduce workers’ exposure to areas around the aging boilers and will rethink how the older, second-line equipment like Unit 2 will be maintained in the future.
The utility is still not certain of the problem’s root cause, but the early hypothesis was it was in a faulty weld which a testing regimen may not have identified.

The power plant will also institute safety zones around the more exposed high-pressure systems on the boiler units.

This was an excerpt from The Ledger newspaper report.



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