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|LDEQ Accident Number
|Point Source(s)||Notes||Amount of Release|
|OL-5 Elevated Flare, FE-101 (EPN 6-84); OL-5 Ground Flare, FG-101 (EPN 7-84)|
RCCU CO Heater and Flue Gas Scrubber (EPN 2-91)
RCCU CO Heater and Flue Gas Scrubber (EPN 2-91); OL-5 Elevated Flare, FE-101 (EPN 6-84); OL-5 Ground Flare, FG-101 (EPN 7-84)
|Cause: On May 8, 2012, the Motiva Enterprise's Residual Catalytic Cracking Unit (RCCU) was struck by lightning during a heavy rainstorm event resulting in an unforeseen shutdown of the RCCU CO Heater and Flue Gas Scrubber (EPN 2-91). Consequently, an Instrument Protective Function (IPF) associated with the CO Heater's force draft fans automatically tripped the system's main fuel gas burners to safely secure the heater as per design. Motiva operations then worked to stablize the RCCU process unit and assess the damages to the RCCU CO Heater resulting from the lightning strike.
The causal analysis generated from the investigation of this incident revealed simultaneous alarms and IPF shutdowns for multiple pieces of equipment associated with the RCCU CO Heater during the time of the incident. A time stamp taken from the RCCU alarm summary noted that several pieces of equipment simultaneously shutdown at 5/8/2012 17:24:34. The pieces of equipment affected from this incident are listed below: CO Heater Forced Draft Fan Electric; CO Heater Forced Draft Fan Turbine; CO Heater Pilot Gas; RCCU Refrigeration Compressor Lube Oil; RCCU Main Air Blower Flow to Fluffing Rings; RCCU Cooling Water Pump Lube Oil Systems.
The data proved that the signals initiating the multiple trips were not generated by the processes themselves, but by a non-process related influence. The investigation team determined that a bolt of lightning struck somewhere in close proximity of the junction boxes for the different pieces of equipment near the RCCU CO Heater. Consequently, this caused an inadvertent energy pulse to either stop current on the analog systems, or provide enough voltage to energize the trip signal and shutdown the equipment listed above.
On May 8, 2012, Shell Chemical's OL-5 Process Unit experienced an unexpected shutdown of the OL-5 Process Gas Compressor (PGC) due to weather conditions which led to flaring at the OL-5 Elevated and Ground Flares. Weather conditions in the area caused issues in a Motiva Unit leading to a curtailment of the sites steam supply. As per site load shedding policies OL-5 was instructed to shut down the PGC which is a consumer of steam.|
Notes: Motiva: The RCCU initiated a unit shutdown in a controlled manner following all operating and safety procedures in order to minimize excess emissions to the atmosphere. As part of the initial shutdown procedure, operating rates were reduced significantly leading up the unit showdown. Simultaneously, a maintenance work plan was developed and executed in a effort to re-establish normal operations of the RCCU CO Heater. At this time electrical inspectors were called in to visually inspect the associated junction boxes for this shutdown system. Additionally, enhanced monitoring of the shutdown system was performed to assure that no damage had occurred as a result of the lightning strike. Once the maintenance work was complete, the RCCU CO Heater was returned to service. Operations then worked to stabilize the CO Heater operations, and began to reverse the shutdown process following all operating and safety procedures. Motiva completed IPF checks to confirm that the instrument protective functions for this system are functioning as needed. Shell Chemical LP.-East: Furnaces in OL-5 were taken off feed after the PGC was shutdown to minimize flaring. The OL-5 process unit was secured until the steam supply was restored to normal conditions to allow for a safe restart of the PGC. In their original final report, Shell Chemical LP - East Site indicated that the permit level for benzene was exceeded; they sent a corrected final report on August 9, 2012 explaining that the permit level for benzene was not exceeded as indicated in the earlier report. As seen on first table Date/Time: 5/8/12 17:25 - 5/9/12 17:25 for section V.a. carbon monoxide was released about reportable quantities. In addition to carbon monoxide being above reportable quantity, benzene was as well although it was not reported as such. The reportable quantity for benzene is 10 lbs with the total amount of benzene being released from Shell Chemical LP - East Site being 967.9 lbs. The LDEQ sent out an emergency responder, Nicole Hardy, who took atmospheric samples from May 8, 2012 at 17:40 to 5/9/12 at 23:30 for a total of 1 day, 5 hours and 50 minutes; all of the samples came back as being below the Permissible Exposure Limits. Although they do not report the pollutant as exceeding reportable quantity - the facility released quantities that exceeded reportable quantities for benzene during the 2 days of this event. The initial verbal notification was made on May 8, 2012. There was an initial written notification (follow up report to verbal notification) made by both Shell chemical and Motiva on July 3, 2012. The first written notification was not made in a timely manner as per state regulations. Since the July 3rd report was their first written notification following the initial verbal notification, therefore they missed the 7 day deadline to make written notification (the deadline would have been May 15, 2013; it would be 48 days late as it was written 55 days after the accident). Another follow up report termed the "final release report" was made by both Shell chemical and Motiva on August 2, 2012. A final follow up report termed the "corrected final release report" was made by by Shell chemical on August 9, 2012 - there was no corrected final report made by Motiva.