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Valero (1238), Meraux

Causal Factor: Power Failure

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

South Flare
Cause: Power interruption to units. Shut down units due to the safety procedures that caused smoke to be released at South Flare.

Followup: No

Notes: RQ not exceeded. Followed operations to secure and re-start the units.Sulfur Recovery Units remained online throughout.Power interruption cause is under investigation.
Sulfur Dioxide: 235.0 pounds

North and South Flares
Cause: Refinery experience a total loss of electrical power. A transfer switch located in the Entergy substation next to the refinery shorted out and tripped both incoming electrical feeders to the refinery. Immediately following there was significant flaring from both the North and South flares. Power was restored after about 90 minutes. The majority of units were back in stable operation by 04/14/12

Followup: No

Notes: Complaint received: On 4/11 at 5:05 am was large dark orange flaring. On 4/12 at 5:12 am was high flare bluish in color. Had been observing a substantial amount of flaring for approximately a month and all of them other than the flare observed on 4/12 have been dark orange. Flares occuring during daylight have black trails associated with them. Cannot tell in the dark if these trails are present. At 6:00-615 am the flare goes into idle mode. The last time a blue flame was observed was when Murphy was using a high jet system. Surveillance conducted in the area on 4/17/12 states that a large flare or smoke was not observed at this time. All equipment in the refinery was shut down, including the process units, steam boilers and instrument and plant air compressors. Power was restored after about 90 minutes. Once power was restored efforts were begun to restart refinery utility systems in preparation for a sequential startup of the process units. Immediately following the loss of power was significant flaring from both the North and South flares. Flaring dissipated once pressures in the unites were stabilized but some flaring did continue. Due to all boilers in the plant having to be shut down, it was not possible to provide steam to the flares so the flares did smoke even when the hydrocarbon flow rates tot he flares were moderate to minimal. Once the boilers were restarted and steam system pressures were adequate, steam flows to the flares were re-established and the smoking was eliminated. Individual unit startups occurred during the following days. On occasions during the startup period, steam relief valves did relieve to the atmosphere causing noise conditions noticeable off site. These steam relief valve events were primarily the results of the changing demands on the steam systems as they worked through the startup process.


North Flare & South Flare
North Flare, South Flare, #2 SRU Incinerator, #3 SRU Incinerator
Cause: The root cause of the event was found to be equipment failure at the Entergy substation adjacent to the refinery. Due to a total power interruption at the refinery, units underwent safety shutdowns, which included venting high rates of gases to the North Flare and the South Flare. There were periods of excess opacity at both flares, as there was no controlling steam available. The boilers were also affected by the power outage. As startups proceeded, the refinery experienced some noise from relief valves and some additional sulfur dioxide emissions at the North Flare. Entergy reported that the power interruption was caused by a severe electrical fault at a 13.8 kV tie breaker at the Meraux Substation. Entergy found no evidence to support a definitive root cause. There was some evidence of bird nesting in the immediate area of the fault.

Followup: Yes

Notes: The refinery shut down all units, per written procedures. Once power was restored to the refiner, the refinery assessed and methodically restarted each unit. The refinery received one citizen complaint for odor during this event.

Sulfur Dioxide: 15,199.0 pounds
Hydrogen Sulfide: 135.0 pounds

South Flare; #3 SRU; Area 1 Fuel Drum: Boiler B-7, Boiler TB-01, MDH Heaters; Area 2 Fuel Drum: Reformer Charge Heater; Hydrocracker Boilers Fuel Drum: Boiler B-5, Boiler B-6
South Flare; #3 SRU; Area 2 Fuel Drum: Reformer Charge Heater
Cause: On April 5, 2013 at approximately 08:47, Valero experienced excess emissions of Sulfur Dioxide and Hydrogen Sulfide at the South Flare, the #3 Sulfur Recovery Unit (SRU), and several refinery fuel gas fired sources due to a loss of power to the refinery's Distributed Control System (DCS). The DCS is a computerized system used to monitor and control the refinery process units. At the time of the incident, the most refinery units were shutdown for planned maintenance, only the Reformer, Naptha Hydrotreater (NHT), MiddleDistillate Hydrotreater (MDH), #3 SRU, and the four boilers remained in service. In order to perform work on the electrical distribution system, a temporary generator was installed to power vital loads, including the DCS. Additionally, the DCS Uniterruptible Power Supplies (UPSs) were bypassed for protection so that battery backup was not available. This temporary power generator dropped offline due to loss of communications between the generator and the engine driving the generator. The root cause of the loss of communications was a loose termination connection on a communications cable. The loss of the DCS caused the immediate shutdown of the remaining refinery units. Upon shutdown of the #3 SRU, field operators cut stripping steam to the #2 Amine unit to prevent acid gas flaring. This allowed some H2S to enter the refinery fuel gas system which was then combusted to SO2 as the fired sources were returned to service. The bulk of the SO2 emissions came from the actuation of a Pressure Safety Valve in the MDH that vented H2S containing material to the South Flare.

Followup: Yes

Notes: The DCS was restored in less that 25 minutes. Valero restarted all four boilers, the #3 SRU, and the MDH. The Reformer Charge Heater was re-lit as part of a controlled shutdown and the NHT was shutdown. SO2 emissions from the North Flare occurred on 4/5/13 from 08:47 to 4/5/13 22:51 for a duration of 14.1 hours (14 hours and 6 minutes). An estimated 2417 pounds of SO2 and 10 pounds of H2S were released. Power to the DCS was quickly restored and the affected units were shutdown in a controlled manner. The rental company technician for the generator quickly identified the loose termination connection as the issue, corrected the loose termination, and placed the generator back online in approximately ten to fifteen minutes. Power to the DCS was quickly restored and the affected units were shutdown in a controlled manner. Valero requested a backup generator from the rental company as a spare for the one that had tripped, which arrived later that day.
Sulfur Dioxide: 2,417.0 pounds
Hydrogen Sulfide: 10.0 pounds

North Flare, South Flare, Area 1 Fuel Drum, Area 2 Fuel Drum, Area 4 Fuel Drum, HC Heaters Fuel Drum, HC Boilers Fuel Drum, #2 SRU, #3 SRU
Cause: On February 10, 2013, Valero Refining - Meraux LLC (Valero) experienced excess emissions of sulfur dioxide (SO2) and Hydrogen Sulfide (H2S) from all in service refinery heaters and boilers, the #2 and #3 Sulfur Recovery Unit (SRU) Incinerator Stacks, and the North and South Flares due to an unexpected shutdown of the #3 SRU. Shortly after the #3 SRU shut down the #2 SRU tripped offline as well. The #2 and #3 SRUs generated excess emissions due to these shutdowns and the subsequent start ups. Additionally, with both SRUs shutdown, the Amine units became saturated with H2S and were no longer capable of removing H2S from gaseous refinery process streams. As a result, the H2S concentrations in the refinery fuel gas and hydrotreater recycle gas systems began to increase. Elevated concentrations of H2S were then combusted in the refinery's heaters and boilers and in the North and South Flares. Root Causes: 1. Loss of 4160 Volt power to the #3 SRU Main Air Blower and #2 Lean Amine Pump. The investigation identified a 30 second power loss but was unable to identify the exact root cause because the plant power monitoring system was not running at the time. 2. The #2 SRU trip was caused by the failure to switch the acid gas interconnect line control scheme from flow control to pressure control. The episode occurred from approximately 06:42 on 2/10/13 to 01:13 on 2/13/13 for a duration of 66.5 hours.

Followup: Yes

Notes: Valero initiated the Sulfur Shedding Procedure and followed the MACT UUU SSM Plan to recover the #2 and #3 SRUs. Valero received reports of multiple citizen complaints called into the St. Bernard Fire Department. The wind direction of 2/10/13 placed the Valero Community Ambient Monitoring Site downwind of the refinery during the period of highest emissions and mobile ambient monitoring was performed by Valero and a third party. The highest single monitoring reading was 2.8ppm SO2; odors may be detected at this level.
Sulfur Dioxide: 93,347.0 pounds
Hydrogen Sulfide: 304.0 pounds