A stuck valve led to the release of tons of hot petroleum coke from a Delaware City Refinery Wednesday morning, forcing a shutdown and sending up a huge, sooty steam plume as workers cooled the area, officials said.
An undetermined amount of coke exited the unit, but there was no fire, said Department of Natural Resources and Environmental Control (DNREC) environmental engineer Ravi Rangan.
The “coker,” one of only a few like it in the country and world, can process up to 57,000 barrels a day of the grainy, end-of-the-line leftover from crude oil refining.
“The issue has been addressed and the situation is under control at this time,” said Michael Karlovich, spokesman for PBF Energy, the refinery’s owner.
“All refinery personnel are safe and accounted for and initial monitoring indicates no known community impact,” Karlovich said.
Rangan said DNREC is awaiting more information and a report. As much as 70 tons of coke might have been inside at the time workers attempted a regular maintenance process to clear clumped-up coke from the system, he said. So far, no other details are available.
Grainy coke circulates continuously inside the coker at temperatures up to about 900 degrees fahrenheit, Rangan said. The process, unlike more common drum cokers that process the material in batches, extracts fuels from refining leftovers that could end up sold abroad as fuel.
Although the Delaware City unit has a 57,000 barrel limit on daily throughput, production levels at the time of the incident were not immediately available. Rangan said the company was working to quickly restore operations.
Sudden shutdowns without quick restarts can be a costly maintenance headache with continuous cokers, industry officials have said in the past. The coker also plays an important role in maximizing revenues for the Delaware City operation, which specializes in heavier, higher sulfur crudes that generate more coke.
The plant has a 191,000 barrel per day limit on crude processing, although officials have said that movement of other partially refined hydrocarbons through the plant can boost daily output to 210,000 barrels per day.