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Shell Chemical East (26336), Norco

Releases of Highly Reactive Volatile Organic Compounds (HRVOCs)

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

OL-5 Ground and Elevated Flares
Cause: On October 11, 2013, Shell Chemical's OL-5 Process Unit experienced an unexpected power failure which resulted in the shutdown of several pumps in the OL-5 Process Unit leading to a process upset and flaring at the OL-5 Ground Flare and OL-5 Elevated Flare. Several breakers in the main central control room were lost. The transformer that supplies power to these breakers tripped unexpectedly. This resulted in the shutdown of several pumps in the OL-5 Process Unit. Most of the pumps that shutdown had back-up spare pumps available and the spare pumps either automatically started or operations manually started them. The ethylene product pump did not have a back-up spare pump available. OL-5 was unable to send ethylene product to the downstream pipeline. This resulted in an inability to remove ethylene product from OL-5's C2 Splitter column and the pressure of the C2 Splitter increased. Elevated pressure in the C2 Splitter column was controlled by relieving to the OL-5 Ground Flare and OL-5 Elevated Flare.

Followup: Yes

Notes: To minimize impacts, spared pumps automatically started and operations started spare pumps manually that do not auto start. After securing and stabilizing the unit, OL-5 operations contacted electrical engineering and maintenance to repair the tripped transformer. On the evening of October 11, 2013, repairs to the transformer were completed, the transformer was placed back in service and flaring stopped. It has been determined that there are not any measures that could be taken to prevent the recurrence of this incident or a similar incident. Report states that all released materials were dispersed naturally in the atmosphere from the OL5 Ground and OL5 Elevated flare stacks. Shell Chemical confirmed that reportable quantity for Highly Reactive Organic Compounds (ethylene and propylene) was exceeded. The maximum permitted limits were exceeded for carbon monoxide, nitrogen oxide, particulate matter, and volatile organic compounds.
1,460.0 pounds

OL5 Elevated Flare (EPN 6-84) and Ground Flare (EPN 7-84)
Cause: On the night of September 8, 2013, Shell Chemical's OL-5 Unit experienced plugging of their online recycle filter located on the bottom of the pyrolysis fractionator (pyrofrac). Once plugged, the level at the bottom of the pyrofrac increased resulting in the level of the quench drum to decrease. This resulted in diversion of feed from several furnaces at OL-5. While stabilizing the OL-5 process unit, operations personnel experienced an upset in the process streams that resulted in flaring at the OL-5 Elevated Flare and OL-5 ground flare.

Followup: Yes

Notes: To minimize impacts, OL-5 operations made various process adjustments, while taking the furnaces off line. These adjustments stabilized the unit and reduced, eventually eliminating, the flaring. These adjustments also prevented the unit from shutting down. To prevent future occurrences, additional filters will be installed to create a robust filtering system. Report states that all released materials were dispersed naturally in the atmosphere from the OL5 Ground and OL5 Elevated flare stacks. Initial report stated that no reportable quantities were exceeded. Following the investigation and calculations, Shell Chemical confirmed they exceeded the reportable quantity for highly reactive volatile organic compounds.
664.0 pounds

DU-5 Unit
Cause: On September 12, 2014, Motiva's DU-5 unit received a shipment of crude oil that contained an unusually large amount of water. DU-5's normal operations removes the water from the crude and sends the water to the unit desalters. The large volume of water that was removed from the crude formed an emulsion which caused the desalter level instrumentation to malfunction. After the desalters, the water is routed to the sour water drum, but due to the instrumentation malfunction on the desalter, the water sent to the sour water drum exceeded the volume that could be pumped from the drum. The water sent to the sour water drum overflowed into the Low Pressure Flare Header. Once the water overflowed to the Low Pressure Flare Header, the liquid went to the Shell Chemical LP Utilities East Flare Pot and was combusted at the Utilities East Flare.

Followup: No


OL5 Unit RV
Cause: On 4/15/14, Shell Chemical's OL5 Unit flared process gas at the OL5 Ground Flare due to a relief valve (RV) on the ethylene product heater unexpectedly lifting. The pressure transmitters and gauges throughout the ethylene product system did not indicate any abnormal unit operation. It was determined that the relief valve malfunctioned by lifting prematurely.

Followup: Yes

Notes: To minimize additional unit upsets and impacts, operations personnel verified the readings from the pressure transmitters and gauges throughout the ethylene product system. Operations personnel safely removed the malfunctioning RV from services and subsequently replaced it. The malfunctioning RV was replaced on 4/22/14. Note that some reporting inconsistencies should lead to questions about the actual amounts released. For example, the refinery report suggests that total VOCs and HRVOCs are the same in the reporting documents. Further, some calculation errors seem apparent, as seen in the last row of table V.5; researcher asserts that the value in the last cell should be 0.23 rather than 100.23.
100.2 pounds