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Valero (1238), Meraux

Releases of Pentane

LDEQ Accident Number
Accident Date
Point Source(s) Notes Amount of Release

API Seperator
Cause: On October 9, 2012, Valero experienced excess emissions of hydrocarbon vapor at the API Separator. Approximately 7 AM that morning, Valero personnel coming into work noticed an unusual odor that was traced to periodic openings of the pressure relief valves on the covered bays of the API Separator. After discovering the release of light hydrocarbon vapors to the atmosphere, Valero applied water sprayed on the area and began to search the refinery for the source of light hydrocarbons. Valero determined the source to be the water draw line off the ROSE Water Knock-Out Drum. The normal path for this water draw line is from the Water Knock-Out Drum to the Oily Water Stripper then to the API Separator. During this event the Oily Water Stripper was shutdown and bypassed so the Water Knock-Out Drum was sent directly to the API Separator. The ROSE unit was in the process of being inventoried with pentane prior to unit start-up. Valero believes that the water level went low in the Water Knock-Out Drum, possibly due to a faulty level indication, and a water/pentane mixture was pumped directly to the API Separator. The pentane then vaporized in the bays of the API and lifted the relief valves. Valero has determined the root causes of this incident to be: 1. Inadequate Procedure: The ROSE start up procedure lacked any steps verifying that the OWS is operating prior to ROSE start up; 2. Poor Equipment Design: The Water Knock-Out Drum level control bridle is susceptible to plugging due to dirty water in the drum. Valero has also determined the following to be contributing factors to this incident: 1. It is difficult to detect hydrocarbons leaving the ROSE unit in the water sent to the OWS. The pentane content of the water stream was not recognized by operations and there is no detector or alarm to notify operations. 2. The API Separator pressure indication was not working properly and provided no warning. 3. The OWS was offline due to lack of feed. The OWS does not have a standby operating mode for low, intermittent flows.

Followup: Yes

Notes: Valero submitted a verbal report on October 9, 2012 and a written report on October 16, 2012, with a follow up report on December 10, 2012, and a final follow up February 6, 2013. The duration of the event lasted 8.25 hours.
32,654.0 pounds