|About the Database
|LDEQ Accident Number
|Amount of Release
|Residual Cat Cracking Unit
|Cause: On September 5, 2014 Motiva Enterprises in Norco reported a potential release of n-butane adn 2-butene.
On August 14, 2014 the Residual Cat Cracking Unit (RCCU) had an unanticipated flaring event at the RCCU Elevated Flare when the RCCU's Debutanizer Overhead Accumulator began to unexpectedly overpressure. Pumps located at the Debutanizer received a false indication that a valve was in the closed position causing the pumps to shut down. Once the pumps shut down, the liquid level in the Debutanizer Overhead Accumulator increased with the unit column pressure. The valve on the Debutanizer Overhead Accumulator was opened to the flare to relieve the column pressure and to prevent any relief valves (RVs) in the unit from relieving to the atmosphere.
Notes: Operations investigated and verified that the system reading was false and the valve was not closed. Action was taken to bypass the valve and the pumps were able to start again. Once the pumps were restarted, the pressure stabilized in the unit and the flaring stopped. The electrical department investigated the issue and discovered that the wiring was no longer in good condition. The electrical department replaced the wiring to the pump valve indicator.
|Cause: On August 8, 2014 Motiva's Hydrocracking Unit (HCU) flared process gas at the HCU Elevated Flare (FE-301) due to the shutdown and subsequent start up of the unit. HCU safely shutdown to repair a ruptured tube on a fin fan cooler. The ruptured tube caused a diesel release that remained in secondary containment.
Data gathering and calculations confirm no reportable quantities were exceeded during the release. However, the permitted maximum hourly emission rate limit for benzene, particulate matter, and volatile organic compounds were exceeded.
Notes: Operations was able to isolate the fin fan to stop the diesel release. The unit was restarted on August 14.