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Valero (1238), Meraux

LDEQ Accident Report

Accident #98709
State Police #07-04781
Accident Date2007-08-16
Report Date 2007-08-23
Follow-up Date 0000-00-00
Follow-up: No Information Provided

Pollutants Released

Pollutant Duration Point Source Greenhouse Gas Criteria Pollutant Ozone forming chemical Amount of Release
Sulfur Dioxide90hFLARE - #3 TGT BypassNOYESNO1,031.0 pounds

Accident Classified As:

Cause of Problem: Process Upset

This shutdown and the subsequent release can be attributed to a process upset. The incident occurred as MOUSA was troubleshooting deviant values in the air demand ratio as part of an effort to proactively diagnose potential problems in the unit. As MOUSA took a flow indicator offline to examine it, the air-to-fuel ratio drifted off-specification, triggering a safety shutdown of the unit on loss of flame in the TGT feed heater

Discharge Preventable - Yes

Notes/Remedial Actions

There was a problem with the air demand ratio controller on the #3 Tail Gas Treater. While the company was troubleshooting the problem they placed the unit on manual control. The unit then proceeded to drift off of the settings and reached a condition where the unit took an automatic safety shutdown. The shutdown could probably have been averted if the ratio drift had been anticipated so this shutdown was due to an unanticipated process upset but the next time the ratio controller has a problem theany should be able to avert a shutdown by carefully monitoring the air demand ratio. - LDEQ report. This incident is listed as being preventable but the only information in that section is that MOUSA did not anticipate this event in the development o