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Valero (1238), Meraux

Causal Factor: Instrument Failure

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

#3 Sulfur Recovery Unit #5 - 00
South Flare - EPN # 3 - 77
Cause: Malfunction of temperature monitor resulted in a shutdown

Followup: No

Notes: There were 28 complaint calls made to the refinery!
Sulfur Dioxide: 27,860.0 pounds
Sulfur Dioxide: 341.0 pounds

#3 Sulfur Recovery Unit Incinerator
South Flare - EPN # 3 - 77
Cause: A contract programmer set the equipment so that it was "too sensitive" to process paremeters and thus triggered a safety shut down of the unit.

Followup: No

Notes: Two incidents were reported in one letter (see next row). The original incident released a big volume of SO2 through the South Flare; restarting produced the emissions in the Tail Gas Treater. The report specifically says that this was NOT due to human error (despite the programmer's setting)
Sulfur Dioxide: 29,362.0 pounds
Sulfur Dioxide: 239.0 pounds
Sulfur Dioxide: 8,595.0 pounds
Sulfur Dioxide: 212.0 pounds

DHT Sour Gas Compressor/ DHT Overhead Receinver
Cause: the incident was triggered by a faulty level reading in the DHT Overhead Receiver (reading 30% less than actual). The compressor shut down when the knockout pot downstream of the DHT Overhead Receiver alarmed on high liquid level. The level gauge apparently failed due to scale (rust) plugging the instrument.

Followup: No Information Provided

Notes: The incident is listed as preventable even though the only information included in that section is that MOUSA did not anticipate the accumulation of scale during the extended shutdown of the vessel. Remedial Measures - the DHT unit had been shut down for 110 days. MOUSA is working on plans to prevent scale formation by securing the Overhead Receiver under an inert atmosphere in any future extended shutdowns. Note: the flare resulted from an automatic safety shutdown of the DHT Sour Gas Compre - but nonetheless, the incident was triggered by a faulty level reading in the DHT Overhead Receiver - the level gauge having failed due to scale (rust) plugging the instrument.
Sulfur Dioxide: 261.0 pounds

FLARE - #2 SRU Startup / plant instrument air
Cause: the episode was a result of a January 29th shutdown due to an emergency safety shutdown of the unit following a malfunction of plant instrument air.

Followup: No Information Provided

Notes: This incident was not preventable because these levels of emissions are consistent with out SSM Plan. Remedial Measures - regarding the #2 SRU startup, no Corrective Actions are warranted. Regarding the instrument air failure, please refer to correspondence related to SERC Incident Number 08-00537. (at this time we do not have a copy of this)
Sulfur Dioxide: 308.0 pounds

Instrument Air Compressor - #3 SRU Malfunction
Cause: the air register to the Incinerator failed closed, starving the Incinerator of combustion air and resulting in a flameout in the #3 SRU Incinerator. The air register malfunctioned due to ice formation in the instrument. (overnight temperatures in the area were below freezing). The root cause was moisture in the instrument air from an instrument air compressor.

Followup: No Information Provided

Notes: This incident was preventable because the instrument air line was not run through a drier, and MOUSA has no standard to address this issue. Remedial Measures - MOUSA published a standard that all instrument air from compressors must be run through driers.

Hydrogen Sulfide: 51.0 pounds


Cause: On June 29, 2013, the sulfur analyzer started reading heightened amount of SO2 releasing although all sources indicate normal SO2 levels, no units were in upset, and no flames were at flare.

Followup: No

Notes: Rescinded notification made for SERC incident #13-02879 on 6/29/13. The initial notification was made based on erroneous data provided by malfunctioning analyzer. No RQs exceeded. Analyzer has been fixed. Facility would like to rescind the notification made on 6/29/13.


None Reported
Cause: A control valve needed adjusting. The problem was made known due to citizen complaint. Two days later, the same valve required adjusting upon notification of complaint.


Notes: After being notified of citizen complaint, a facility crew investigated the plant and identified a control valve in the Alky unit as the source of the loud sound being complained of. Adjustments were made to the process to reduce the sound coming from that valve. Another complaint was issued two days later on January 21, 2013 about a high pitched sound currently occurring. The same valve was identified as the source and was adjusted again. Operations personnel were subsequently instructed to keep the flow rate through the valve in a range that should minimize sound being produced by the valve. Investigation as to engineering changes that can be made to the valve to address this issue are underway.