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Louisiana Refinery Accident Database

Valero (1238), Meraux

LDEQ Accident Report

Pollutants Released

Accident Classified As: Reportable Quantity

Cause of Problem: Equipment Failure

On January 8, 2014, at approximately 21:00 hrs, Valero exceeded the reporting threshold for Sulfur Dioxide at the South Flare. Valero implemented its procedure for checking high sulfur sources (PSV's, process vents, etc.), but found no obvious discharge into the flare header. After performing several searches for the source and not finding any valves out of position, Valero compared several gas samples to the composition of the gas being flared in the South Flare. Because of similarities in composition, Valero believes that source of total sulfur for this incident was the recycle gas section of the Ultra Low Sulfur Diesel Hydrotreater (DHT). The unit was shut down and restarted on 1/7/14 due to a cold weather related instrument malfunction. Valero inspected all connections between the DHT recycle gas section and the South Flare but could not determine a definite source. Valero initially believed that the source of sulfur was likely a weeping Pressure Safety Valve (PSV) on the DHT recycle gas section, so all the PSV's nt hte DHT recycle gas section were sent out for testing and repair during shut down. SO2 emissions at the South Flare returned after turnaround and reinstallation of the PSVs, indicating that the weeping PSV was not the source. Valero now believes that the cause was a continuous source and the total sulfur concentration of the recycle gas became elevated due to the shut down and start up on 1/7/14. The total sulfur returned to baseline levels after the DHT returned to normal operating conditions.

Discharge Preventable - Yes

Notes/Remedial Actions

South Flare SO2 emissions decreased below the RQ on 1/9/14. Valero continuously monitors the total sulfur and flow at the South Flare.