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Valero (26003), Norco

Causal Factor: Instrument Failure

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

Coker wet gas compressor
Cause: The WGC tripped several times due to a high level indication in the interstage drum. This indication was a fase reading due to an accumulation of debris in the level chamber of the radar detector.

Followup: Yes

Notes: Will place the level chamber on a cleaning schedule to facilitate the removal of debris no later than April 15, 2005.
Sulfur Dioxide: 23,000.0 pounds

T-150-5 transfer pump
Cause: Pressure gauge on T-150-5 transfer pump broke off allowing oil to spill from the tank

Followup: Yes

Notes: No original incident report.Pump was shut down and blocked in. Vacuum trucks were dispatched to recover free soil, the tank was cleaned of any oil clinging to the side, and crews began excavating any contaminated soil.
Vacuum Bottoms, Gas Oil, 6 Oil: 210.0 gallons

Vacuum jet tower receiver
Cause: Vacuum tower jet receiver pressured up causing the liquid level in the seal legs to backup and create a higher discharge pressure on the vacuum ring pumps. The increased pressure at the jet receiver resulted in the drum PSV lifting to the flare. The increased pressure on the discharge of the ring pumps cause al 3 pumps to trip on high amps. The ring pumps were drained and restarted at which time the flaring stopped. Exact cause of incident unknown.

Followup: No

Notes: Emissions were minimized by roperations reducing charge to the unit. The overhead receiver was drained, the ring pumps were de-inventoried to start up level, and the ring pumps were restarted to reestablish the vacuum on the vac tower and stop the flaring of gases.
Sulfur Dioxide: 1,200.0 pounds

Thermal Oxidizer #2, Flares #1,2,3,4
Cause: On Oct 24, 2007, Valero shut down the West Plant units. There was a communication issue with the Process Logic Controller (PLC) , resulting in the shutdown of the Crude Unit. The shutdown of the Crude Unit cascaded and caused the Vacuum, Coker, and Hydrotreater Units to shutdown as well. Consequently, problems began with the East Plant Units that resulted in flaring and an upset of their SRU 30.

Followup: Yes

Notes: Since the incident consisted of shutdown events that led to a flaring/incinerating event, the units were restarted as soon as the communication issue was resolved.


Flares 1 and 2
Cause: Guardian over speed device malfunction causes WGC to trip

Followup: No

Notes: Emissions minimized by immediately restarting WGC. A series of follow-up reports reveal that Valero did not know age or maintenance history of WGC upon purchase of facility from Orion. Valero has now replaced major components of WGC and plans to replacethe guardian over speed device next.

Carbon Monoxide: 162.0 pounds
Particulate Matter: 1.0 pounds
Volatile Organic Compounds: 61.0 pounds
Hydrogen Sulfide: 16.0 pounds
Nitrogen Oxide: 30.0 pounds

3700 TOX (EQT 0195)
Cause: Due to the malfunction of a float switch, the 3700 Sulfur Recovery Unit (3700 SRU) tripped offline at approximately 03:59 on 12/15/09. As a result the SO2 levels at the 3700 Thermal Oxidizer (3700 TOX or EQT 0195)were elevated from approximately 04:03 am to 11:44 am.

Followup: Yes

Notes: The 3700 SRU feed stream was redistributed and the unit was restarted.
Sulfur Dioxide: 1,049.9 pounds

FLARE: flare #1 & #2
Cause: Wet gas compressor (WGC) in the delayed coking unit malfunctioned resulting in SO2 emissions to Flares #1 and #2. A level indicator on the coker tower HCGO tray malfunctioned. FLARE.

Followup: Yes

Notes: RQ. Reportable quantities for sulfur dioxide were exceeded. See Root Cause Analysis for more information. DLEQ report, Refinery letter, and follow-up letter all included in file.
Sulfur Dioxide: 4,529.0 pounds
Volatile Organic Compounds (VOCs): 80.0 pounds
Hydrogen Sulfide: 12.0 pounds
Carbon Monoxide: 212.0 pounds
Particulate Matter: 2.0 pounds
Nitrogen Oxide: 39.0 pounds

3700 and 30 SRU
Cause: The sulfur dioxide levels at 3700 and 30 unit thermal oxidizers were elevated due to failure of a pressure transmitter on the 3700 unit overhead accumulator. Valero estimated that the RQ for sulfur dioxide was exceeded at approximately 1:10 am and the RQ for hydrogen sulfide was not exceeded. The failing transmitter gave false indications in both the overhead accumulator pressure and the stripper overhead pressure. This prompted operational moves in the unit to shift loads in an effort to return the SRUs to stead operation.

Followup: Yes

Notes: After the local pressure gauges in the field were verified, it was determined that a single pressure indication was malfunctioning and operational moves were made to restore normal operating conditions. The following corrective actions were identified to prevent recurrence of this incident: (1)Repair both the overhead accumulator and the stripper overhead pressure transmitters and have separate pressure readings on the DCS. (2)Revise the DCS page to reflect both pressure indications. (3) Ensure the DCS and logic changes are covered by the management of change (MOC) process. (4) Conduct training with Operators on this incident. (5)Have the pressure control valve 37-4182-A inspected during the 2014 turnaround.
Sulfur Dioxide: 1,333.5 pounds