Connect With Us:

Louisiana Refinery Accident Database

Valero (1238), Meraux

LDEQ Accident Report

Pollutants Released

Accident Classified As: Reportable Quantity

Cause of Problem: Equipment Failure

On March 1, 2013 at approximately 16:15, Valero experienced excess emissions of Sulfur Dioxide at the North Flare due to an over-current trip of the East Crude Overhead Compressor. The West Crude Compressor was down for repairs and unavailable. The East Crude Overhead Compressor tripped offline at 15:23 and was started at 16:36. Valero was unable to immediately re-start the East Crude Overhead Compressor due to a 1 hour lockout timer that prevents re-start after tripping on over-current. When the trip occurred, Valero was in the process of shutting down another refinery unit for a planned maintenance outage. Normally, crude off-gas is lined up to this unit. The compressor tripped offline on over-current while Valero was redirecting the crude off-gas to an alternate destination. The pressure at this alternate destination was approximately 60psig higher than the compressor discharge prior to the switch. Valero determined the root cause of the trip to be that the electric motor on the East Crude Compressor was undersized and not capable of routing the crude off-gas to the higher pressure destination when fully loaded. Contributing factors include: 1. The West Crude Compressor was down for repairs and unavailable. 2. The crude tower was operating at elevated pressures due to degradation of the internal structures. This increased the work load (horsepower) on the off-gas compressor. 3. Approximately 40 minutes elapsed between the compressor trip and the reduction in Crude Unit charge rate.

Discharge Preventable - Yes

The release was preventable.

Notes/Remedial Actions

Flaring from the Crude Overhead occurred from 15;23 to 16:38 and the Total Sulfur concentration in the North Flare returned to normal by 17:20. Valero immediately put all available crude overhead fin-fans in service to reduce crude overhead pressure and minimize flaring. Valero later cut crude charge rate to reduce the production of off-gas. Valero re-started the East Crude Overhead Compressor as soon as the lockout timer expired. To prevent recurrence: 1. Valero will upgrade both of the curde compressors with higher horsepower electric motors. 2. Valero will modify the "Loss of Crude Compressor" procedure to specify a more prompt reduction in crude charge rate. 3. Valero will modify the operations procedure for lining up crude off-gas stream to include unloading the compressor to control motor amps also to include running both compressors in parallel (if available). 4. Valero will bring the motor amp indications into the DCS for both compressors.