That explosion caused no fatalities or serious injuries, but did cause a number of residents around the plant to shelter in place for about five hours.
That coal gasification facility, which has since restarted operations, consists of a series of processes designed to produce mixtures of carbon monoxide and hydrogen from coal and to purify the gas stream for making methanol and acetic anhydride.
TDEC noted that in the gasifier process, coal slurry is mixed with pure oxygen and heated under pressure to produce a mixture of carbon monoxide and hydrogen.
“Excess oxygen also creates a substantial fire/explosion hazard when combined with hydrogen gas,” TDEC said in its report.
The October 4 incident, said TDEC, occurred during a gasifier switch. A ball valve failed to fully close during water flushing of the slurry feed lines of a non-working gasifier. Oxygen began to accumulate in the system at high pressure and temperature.
TDEC noted the gasifier was shut down at 9:38 a.m. A series of explosions happened at 10:50 a.m.
“Failure of an equipment item is generally considered a malfunction event, but failures that are caused by poor maintenance, careless operation, or other preventable upset condition or equipment breakdown are not considered malfunctions,” said the TDEC report.
TDEC concluded no enforcement action is recommended for excess emissions resulting from the event and recommended Eastman review its processes.
Eastman reported the net costs of the disruption, repairs and reconstruction of the coal gasification facility and restart of operations reduced fourth quarter 2017 pretax earnings by $112 million. In addition, lost sales revenue attributed to the coal gasification disruption was limited to approximately $40 million, primarily in the Chemical Intermediates segment. The cash impact of the incident in fourth quarter 2017 was minimal, with working capital benefits and insurance reimbursement largely offsetting cash expenditures for disruption and repairs.