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Accident # | 136563 |
State Police # | 12-0194_12-0184_12-0186 |
Accident Date | 2012-01-14 |
Report Date | 2013-02-26 |
Follow-up Date | 0000-00-00 |
Follow-up: |
Pollutant | Duration | Point Source | Greenhouse Gas | Criteria Pollutant | Ozone forming chemical | Amount of Release |
Sulfur Dioxide | 2d 7h | Unit 59 South Flare, Unit 45 Thermal Oxidizer, Unit 220 Thermal Oxidizer, Unit 234 Thermal Oxidizer, and Unit 33 Sour Water Tank | NO | YES | NO | 500.0 pounds |
Accident Classified As: Reportable Quantity
The incident began on January 14, 2012 at 02:25 hours and ended at approximately 09:35 hours on January 16, 2012. The incident lasted roughly 55 hours. On January 14, 2012, hydrocarbon carryover from the Unit 19 Sour Water Stripper caused Unit 220 (sulfur unit) and Unit 45 Thermal Oxidizer to trip. As a result, a sulfur dioxide (SO2) plume was released from the Unit 45 Thermal Oxidizer. During the release, hydrocarbons from the ammonia acid gas header were steamed out to flare. Units were then shutdown to limit environmental impact. Approximately four hours after Unit 220 startup the following day, a similar incident took place. Hydrocarbon carryover from the unit 19 sour water stripper caused Unit 220, 234, and Unit 45 Thermal Oxidizers to trip. The thermal oxidizer released a plume of SO2 to the atmosphere. During this incident, the flare valve on the fuel gas absorber knockout drum opened to flare to relieve pressure on the drum. Hydrocarbon from the carryover was also sent to the sour water storage tank which resulted in the tank venting to the atmosphere. The flare valve from the fuel gas absorber knockout drum was closed at approximately 09:30 on January 16; the incident was then determined to be secure.
The release was not preventable. The large quantity of hydrocarbon liquid carryover to unit 19 Fuel Gas Absorber Knock-out drum was not anticipated.
During the initial upset, Cargill was notified of the plume. All work within the Marathon refinery was put on hold and the plant's Air Monitoring Team (AMT) was dispatched. The data collected is included in attachment 2. The contents of the Unit 19 Sour Water Storage Tank and ammonia (NH3) acid gas header were then purged to eliminate existing hydrocarbons. Similar actions were taken to mitigate emissions from the second incident. Units were shutdown, the AMT was activated, and fire water was introduced to limit emissions from the sour water tank. The incident was determined to be secure when the flare valve from the fuel gas absorber knockout drum was closed to the South Flare. The refinery report mentions that sulfur dioxide was released above RQ, but no calculations were provided. It states calculations are located in the attachment, but LABB could not locate said attachment. The RQ for SO2 is 500 pounds.
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