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Shell Chemical East (26336), Norco

LDEQ Accident Report

Accident #137810
PDF AvailablePDF
State Police #12-01442
Accident Date2012-03-12
Report Date 2012-03-19
Follow-up Date 0000-00-00
Follow-up: No

Pollutants Released

Pollutant Duration Point Source Greenhouse Gas Criteria Pollutant Ozone forming chemical Amount of Release
Carbon Monoxide24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NOYESNO523.5 pounds
Nitrogen Oxide24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NOYESYES96.2 pounds
Particulate Matter24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NOYESNO18.1 pounds
Volatile Organic Compounds (VOCs)24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NONOYES249.6 pounds
Butadiene24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NONOYES16.1 pounds
Benzene24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NONOYES13.0 pounds
Ethylbenzene24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NONOYES1.2 pounds
Toluene24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NONONO9.1 pounds
Xylene24mOL-5 Elevated Flare FE-101 (EPN 6-84); OL-5 Ground Flare FG-101 (EPN 7-84)NONONO4.7 pounds

Accident Classified As: Below Reportable Quantity (BRQ)

Cause of Problem: Instrument Failure

On March 12, 2012 Shell Chemical's OL-5 Unit Operators got an indication that the Process Gas Compressor (PGC) first stage control valve had opened to the flare system due to high suction pressure. The PGC turbine had slowed down causing the kickback valves to open. Slowdown of the turbine was caused by a high level in the surface condenser. The materials were released from OL-5 Elevated Flare FE-101 (EPN 6-84) and OL-5 Ground Flare FG-101 (EPN 7-84).

Discharge Preventable - Yes

This incident was preventable by Shell. The instrument malfunction was unexpected but could be prevented by maintaining the enclosure.

Notes/Remedial Actions

OL-5 Operations lowered the surface condenser level and the kickback flows to lower the first stage suction pressure. These actions stopped the flaring. All materials routed to flare were combusted with an approximate destruction efficiency of 99.5% released from the OL-5 Elevated Flare and Ol-5 Ground Flare to the atmosphere and dispersed naturally. Maintenance was called in to troubleshoot the surface condenser level indication. Instrument mechanics checked level controller and found dirt on the flapper nozzle. The nozzle was cleaned and proper operation of the control valve was checked. Instrument mechanics also found the door to the instrument center in the open position, which possibly allowed dirt into the enclosure. Operational rounds have been updated to include the task to check enclosure doors. Propylene is listed in the LDEQ's Verbal report as having been released as well, but there is no mention of it later on in the follow-up report from Shell. The measurements were obtained by adding the same pollutants from both flares together. Initial report states material did go offsite. Air was monitored around the perimeter of the facility. No reportable quantities were exceeded, but permit levels were exceeded for ethylbenzene, toluene, and xylene.