Explosion in coal feed system causes CPS shutdown of Deely unit

Texas municipal utility CPS Energy said that its coal-fired, 420-MW Deely Unit 1 experienced an explosion on Sept. 10 and that Unit 1 will likely be down for several weeks as the cause is determined and repairs are made.

An initial investigation showed that the cascade building – a part that feeds coal into silos before it’s moved into the plant – was damaged. The plant’s fire suppression system deployed as it was designed to do, CPS noted. The plant was online at the time of the explosion, with the plant taken offline for safety reasons and to investigate further.

Unit 1 will likely be down for several weeks as crews work to replace the cascade housing that was damaged in the explosion, CPS said in a Sept. 12 statement. Two employees received minor injuries from falling debris.

The Deely plant has two coal units, with GenerationHub data showing Unit 1 with 435 MW of net summer capacity and Unit 2 with 436 MW of net summer capacity.

The root cause of the explosion is still under investigation by CPS Energy. The company said it has spoken with the Texas Commission on Environmental Quality and expects to report the incident as a deviation from normal operations.

David Herbst, senior vice-president of power generation, said that coal dust in a silo caught fire, ultimately causing damage to the cascade building. He said explosions like this are a hazard in the industry.

Power plant coal dust is highly combustible, CPS noted. In the Deely units, CPS Energy said it burns ultra-low-sulfur coal transported from coal mines in Wyoming, which has resulted in about 30% less SO2 emissions than using low-sulfur coal. This Powder River Basin coal is known to be dusty and special dust suppression and fire prevention methods need to be used when it is being utilized. U.S. Energy Information Administration shows that Deely suppliers earlier this year included the Coal Creek and Black Thunder mines of Arch Coal (NYSE: ACI), the Cordero mine of Cloud Peak Energy (NYSE: CLD) and the North Antelope Rochelle mine of Peabody Energy (NYSE: BTU).

The cascade structure has since been stabilized. Specialized contractors are being brought in to help with clean-up and repairs. Officials are working to determine the cost for repairs. Because demand for power has eased with cooler temperatures, there is no concern for a shortage of power, and customers should not see any difference in their service, CPS noted.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.