“We identified the problem with the system and ... while troubleshooting, the power supply went off,” Parnell said. “That caused interruption of power to the control system, which essentially shut down the systems that were connected to that portion of the control system, resulting in a trip of all five heat recovery steam generators, as well as the steam turbine and the flue-gas desulfurization system.”
Technicians identified the problem, repaired and tested the power supply and returned the plant to service within 24 hours, Parnell said.
Jan. 7 was when the second shutdown occurred, he said.
“The nature of the shutdown caused some additional shocks to the high energy piping system that wound up liberating some debris that occurs normally in those systems,” he said “We’re not talking about a dump truck full of materials, we’re talking about a couple of five gallon buckets spread across all of the steam piping and several vessels.”
The material got into the strainer that protects the pumps, causing SunCoke to have to take those pumps out of service and launch backups, which also experienced problems.
“We reached the point where we couldn’t keep up with it, so we shut the plant down in a controlled fashion,” Parnell said.
SunCoke worked to resolve the problem with 20 to 30 people working around-the-clock in various shifts, he said. Operations did not resume until noon on Monday.
There was never a question of a safety risk or hazardous emissions during the shutdown, Parnell said.
“We take these things very seriously,” he said. “We do not have a cavalier attitude and say “you know, that stuff is going to happen.’ It’s not supposed to happen. We identify and resolve literally hundreds of conflicts that could lead to situations like this.
“Quite frankly we were surprised. We went into that troubleshooting well-prepared and the OEM (original equipment manufacturer) even said that he had not seen that happen before.”
SunCoke officially produced its first run of coke — a steelmaking raw material — at the end of last year. The company has signed an agreement to sell all of the coke and energy produced at the plant to AK Steel for the next 20 years.
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