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Shell Chemical East (26336), Norco

LDEQ Accident Report

Accident #148176
PDF AvailablePDF
State Police #13-01697
Accident Date2013-04-19
Report Date 2013-04-25
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 Monoxide3hOL-5 Elevated Flare, FE-101NOYESNO2,101.7 pounds
NOx3hOL-5 Elevated Flare, FE-101NONOYES386.3 pounds
Particulate Matter3hOL-5 Elevated Flare, FE-101NOYESNO681.6 pounds
Volatile Organic Compounds (VOCs)3hOL-5 Elevated Flare, FE-101NONOYES1,204.9 pounds
1,3-Butadiene3hOL-5 Elevated Flare, FE-101NONOYES32.5 pounds
Benzene3hOL-5 Elevated Flare, FE-101NONOYES29.7 pounds
Ethylbenzene3hOL-5 Elevated Flare, FE-101NONOYES2.7 pounds
Toluene3hOL-5 Elevated Flare, FE-101NONONO20.9 pounds
Xylene3hOL-5 Elevated Flare, FE-101NONONO10.8 pounds

Accident Classified As: Below Reportable Quantity (BRQ)

Cause of Problem: Process Upset

On April 19, 2013 Shell Chemical's OL-5 Process Unit experienced an unexpected upset that led to flaring at the OL-5 Elevated Flare (EPN 6-84). The flaring was caused by high pressure on the process gas compressor (PGC) first stage suction drum. A pressure increase on the suction drum was due to the PGC slowing down as a result to the loss of vacuum on the compressor surface condenser. The surface condenser vacuum was lost due to a faulty level indication causing the loss of vacuum on surface condenser. The PGC upset also caused OL-5 cold-side to flare propylene off the outlet of the map converters because of a low flow shutdown of the converters.

Discharge Preventable - No

This incident was not preventable by Shell. The malfunction of the surface condenser level transmitter was unexpected.

Notes/Remedial Actions

OL-5 operations field verified the level int he PGC surface condenser and took corrective actions to safely return the unit to normal operating conditions and stop the flaring. OL-5 Maintenance repaired the PGC surface condenser level transmitter. Control systems adjusted the vacuum alarm setting for the PGC surface condenser to warn operators before the surface condenser vacuum is lost. Final calculations confirm that no reportable quantities were exceeded. The maximum permitted limits were exceeded for particulate matter, ethylbenzene, toluene, and xylene.