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Valero (26003), Norco

LDEQ Accident Report

Accident #150290
PDF AvailablePDF
State Police #13-03552
Accident Date2013-08-09
Report Date 2013-08-16
Follow-up Date 2013-10-08
Follow-up: Yes

Pollutants Released

Pollutant Duration Point Source Greenhouse Gas Criteria Pollutant Ozone forming chemical Amount of Release
Nitrogen Dioxide6d 14hr 24mFlares 1,2,3,4&5; FCCU; GDU; Boiler B-401C, B-401D, & 401-ENOYESYES8,065.0 pounds
Carbon Monoxide6d 14hr 24mFlares 1,2,3,4&5; FCCU; GDU; Boilers B-401C & B-401DNOYESNO18,171.0 pounds
Particulate Matter6d 14hr 24mFlares 1,2,3,4&5; FCCU; GDU; Boiler B-401C, B-401D, & 401-ENOYESNO336.0 pounds
Sulfur Dioxide6d 14hr 24mFlares 1,2,3,4&5; 30, 1600, & 3700 TOX; FCCU; GDU; Boilers B-401C, B-401D, & 401-ENOYESNO71,472.0 pounds
Hydrogen Sulfide6d 14hr 24mFlares 1,2,4&5; 30, 1600, & 3700 TOX; Coker No. 2 Steam VentNONONO652.0 pounds
Volatile Organic Compounds (VOCs)6d 14hr 24mFlares 1,2,3,4&5; Coker No. 2 Steam Vent; Boilers B-401C, B-401D, & 401-ENONOYES3,764.0 pounds
1,3-Butadiene6d 14hr 24mFlares 1,2,3,4&5NONOYES12.0 pounds
Benzene6d 14hr 24mFlares 1,2,3,4&5; Coker no. 2 Steam VentNONOYES26.0 pounds
Ethylbenzene6d 14hr 24mFlares 1,2,4&5; Coker no. 2 Steam VentNONOYES0.4 pounds
Formaldehyde6d 14hr 24mFlares 1,2,3,4&5NONOYES1.0 pounds
Naphthalene6d 14hr 24mCoker No. 2 Steam VentNONOYES2.0 pounds
Hexane6d 14hr 24mFlares 1,2,3,4&5NONONO263.0 pounds
Cresol6d 14hr 24mCoker no. 2 Steam VentNONOYES0.2 pounds
Polycyclic Aromatic Hydrocarbons6d 14hr 24mCoker no. 2 Steam VentNONOYES1.0 pounds
Toluene6d 14hr 24mFlares 1,2,3,4&5; Coker no. 2 Steam VentNONONO15.0 pounds
Xylene6d 14hr 24mFlares 1,2,3,4&5; Coker no. 2 Steam VentNONONO9.0 pounds
Phenol6d 14hr 24m6d 14hr 24mNONONO0.1 pounds
Phenylamine6d 14hr 24m6d 14hr 24mNONONO0.1 pounds

Accident Classified As: Reportable Quantity

Cause of Problem: Power Failure

On August 9, 2013, at approximately 22:51 hrs, Valero experienced an interruption in power supply caused by a surge arrestor electrical fault. The interruption caused the shutdown of multiple process units and resulted in excess emissions from the boilers, Sulfur Recovery Units (SRUs), Fluid Catalytic Cracking Unit (FCCU), Gasoline Desulfurization Unit (GD), Coker Unit, and refinery flares. During recovery process of the power loss event, shutdowns occurred to both the Hydrocracker unit (HCU) and Ultra-low sulfur diesel unit (ULSD) resulting in flaring. Both unit shutdowns were related to the shutdown of their recycle gas compressors. The HCU's recycle gas compressor malfunctioned due to a low steam pressure which was directed related to the power loss event. The ULSD shutdown due to a malfunction of the recycle gas compressor's primary lube oil pump, and a delayed response for the startup of the secondary lube oil pump. We are unable to determine if the shutdown of the ULSD was directed related to the power loss event. However, the emission contributed to the HCU and ULSD shutdowns are considered as part of the same power loss event and are included herein.

Discharge Preventable - No

Several process units shutdown as a result of a sudden loss of power, which was not reasonably preventable. Evidence identified through a third part analysis of the failed arrestor suggests that the energy handling capability of the surge arrestor was less than nominal, possibly due to a design flaw. The design flaw is a likely cause since the secondary arrestor, which passed electrical tests, showed similar signs of degradation in the areas of the failed arrestor. Prior to the arrester failure monthly thermal scans of the substation were conducted and nothing abnormal was indicated. Shutdown of the ULSD unit due to the loss of the lube oil pump was also not considered reasonably preventable. Two lube oil pumps, one turbine and one electric, were in place to provide the recycle gas compressor with appropriate amounts of lube oil. Reasons for the loss of the primary turbine are unknown but may be a result of changes in the steam supply following the power loss. A secondary electric turbine was in place but did not start as expected to prevent the unit shutdown.

Notes/Remedial Actions

The power loss caused the Crude Unit and Vacuum Unit to shut down immediately, thus preventing the manufacture of intermediates that feed subsequent process units. Downstream units were placed in circulation mode through manually closing valves, lowering reactor temperature and restarting tripped equipment such as compressors and pumps. Steam production was also increased as available to allow units to continue in circulation mode until power was restored. The HCU and ULSD units were re-started to reduce excess emissions. In addition, the flare gas recovery unit remain in operation during the entire incident to reduce the amount of flared gas. To prevent recurrence, the following procedures will be adopted: 1) Perform thermal scans of the surge arrestors in the Prospect and Good Hope Substation yards. 2) Perform routine thermal scans of the surge arrestors in the Prospect and Good Hope Substation yards. 3) Complete the evaluation of all existing Valero owned surge arrestors in the Prospect and Good Hope Substation yards to determine if they are of the same age and model of the T3 arrestors that have shown signs of degradation. To data, the surge arrestors on T4 transformers have been identified as being of the same vintage and design as the failed arrestors and will be the first targeted for replacement as will all arrestors of this design. 4) Evaluate one of the non-failed surge arrestors removed from service to determine if any degradation has started to occur. 5) Develop a plan to routinely replace all surge arrestors in 230KV service at 10 year intervals. 6) Review this incident and emergency procedures with affect personnel. 7) Evaluate raising the autostart pressure setting on the auxiliary lube oil pump. 8) Evaluate increasing the trip time delay on the low-low lube oil shutdown. 9) Consider installing a valve on the make-up hydrogen at the ULSD unit battery limits to prevent fresh hydrogen from being introduced to the unit during a period of malfunction. 10) Add to existing Emergency Operation Procedure to account for Diamond Green Diesel, which is connected to the ULSD. 11) Contact corporate hydrocracking specialists to determine if the logic should be modified to initiate high rate depressurization upon loss of recycle gas compressor. Reportable quantities were exceeded for H2S, SO2, NOx, and VOCs.