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Accident # | 158089 |
State Police # | 14-03618 |
Accident Date | 2014-08-15 |
Report Date | 2014-08-20 |
Follow-up Date | 2014-10-14 |
Follow-up: | Yes |
Pollutant | Duration | Point Source | Greenhouse Gas | Criteria Pollutant | Ozone forming chemical | Amount of Release |
Sulfur Dioxide | Flare 1 | 3h 6m | NO | YES | NO | 6,400.0 pounds |
Hydrogen Sulfide | Flare 1 | 3h 6m | NO | NO | NO | BRQ |
Accident Classified As: Reportable Quantity
On August 15, 2014, electrical feed from a power substation tripped offline, causing multiple units to shutdown. An investigation of the incident found the cause to be the failure of a sudden pressure relay on transformer T-3 at the PS-2 substation. This provided a false trip input into the transformer differential relay. The relay logic reacted to the input by isolating the transformer, thus de-energizing power to Buss 3, which shut down several pieces of equipment. Maximum hourly permitted emissions rates for sulfur dioxide, hydrogen sulfide and volatile organic compounds from Flare 1 were exceeded. Neither report includes emissions totals for hydrogen sulfide.
Initial report states that incident is under investigation and, thus, a determination has not been made about whether the accident was preventable. The follow-up Root Failure Analysis does not include information about preventability.
At the time of the accident, Valero energized an alternate source of power to supply the equipment. The Diesel Hydrotreater (DHT), Naptha Hydrotreater (NHT), and Continuous Catalytic Reformer (CCR) Units tripped off-line. Valero left them down until reliable power was restored. The FCCU and Crude Units reduced rates to minimize emissions. Flare gas recovery remained in operation to recover some of the gases sent to the flare header. A Root Cause Analysis identified several corrective actions to be taken by Valero, including: 1) Communicate the incident to affected personnel (Estimated completion date: 10/31/14), 2) Work with Electrical Safety and Reliability network (ESARN) to develop a recommendation for routine testing/inspection of sudden pressure relays on transformers(Estimated completion date: 12/31/14), 3) Develop a list of refinery substations that would benefit from MAIN-TIE-MAIN auto transfer scheme and prioritize implementation (Estimated completion date: 12/31/14), 4) Review the power source for refinery analyzers and develop a prioritized list of analyzers that would benefit from moving from a Purchased Power source to a UPS source (Estimated completion date: 12/31/14), 5) Develop a written guideline for restorations of power for the refinery following power loss scenarios at Prospect and Good Hope Substations (estimated completion date: 12/31/14).
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