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Motiva Enterprises (1406), Norco

Releases of Isobutylene

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

Cause: On 2/27/2014, an unexpected leak occured on Motiva's Residual Catalytic Cracking Unit (RCCU) second cyclone dip leg. Due to the location of the leak, the catalyst leak cound not be safely repaired while the unit was fully operations. A partial shutdown of the RCCU was conducted to stop the leak and complete repairs. While the unit was partially shut down, flaring occured intermittently at the RCCU Elevated Flare (EPN FE201) to safely stabilize equipment that was still operational. During the start up of RCCU, untreated dry gas was flared at the GO1 Elevated Flare.

Followup: Yes

Notes: To minimize additional unit upset and to safely repair the catalyst leak , the RCCU Unit was partially shut down in a safe manner. The catalyst leak was stopped and the second cyclone dip leg was repaired. The original report and the first follow up report included in the event description that untreated dry gas was flared at the GO1 Elevated Flare during the start-up of RCCU. This was not included in the final follow up report. Additionally, two follow up reports were sent by Motiva, the first dated 4/24/2014 to provide a 60 day follow up. In this correspondence it is stated that they will provide a second update within 60 days, as data gathering and investigation was ongoing. The final follow up report was received on 6/24/2014.
41.0 pounds

Elevated Flare (FE-201)
Cause: Motiva's RCCU Unit had a relief Valve (RV) on its Debutanizer Column lift and relieve to atmosphere. The RV lifted as its designed pressure setting after a pressure transmitter failed in the unit causing a pressure control valve to fail into closed position. Once this valve did not move to open position, the pressure within the Debutanizer Column built up and over pressured causing the RV to relieve as designed. To help relieve the pressure in the debutanizer column and to stop the RV from relieving the material was routed to the flare. Isobutane, Isobutene, N-Butane, Propane, and Propylene were potentially released from Motiva's Residual Catalytic Cracking Unit's (RCCU) Elevated Flare (FE-201).

Followup: No

Notes: Data gathering to perform calculations and investigation are ongoing. Shell will provide and update within 60 days as required by LAC 33:1:3925.A.3.