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Valero (26003), Norco

LDEQ Accident Report

Accident #157325
State Police #14-03014
Accident Date2014-07-09
Report Date 2014-07-16
Follow-up Date 2014-09-05
Follow-up: Yes

Pollutants Released

Pollutant Duration Point Source Greenhouse Gas Criteria Pollutant Ozone forming chemical Amount of Release
Hydrogen Sulfide1hEQT 0360 Flare No. 4NONONO8.6 pounds
Carbon Monoxide1hEQT 0360 Flare No. 4NOYESNO13.6 pounds
Nitrous Oxide1hEQT 0360 Flare No. 4YESYESYES8.1 pounds
Particulate Matter1hEQT 0360 Flare No. 4NOYESNO0.1 pounds
Volatile Organic Compounds (VOCs)1hEQT 0360 Flare No. 4NONOYES17.9 pounds
Sulfur Dioxide1hEQT 0360 Flare No. 4NOYESNO1,597.7 pounds

Accident Classified As: Reportable Quantity

Cause of Problem: Equipment Failure

The Hydrotreater/Hydrocracker (HTHC) recycle compressor malfunctioned, which initiated a shutdown of the HTHC and led to a reportable quantity of sulfur dioxide. The cause of the malfunction is under investigation while the unit is being repaired. Permitted emissions for H2S, VOC and SO2 was exceeded for 1 hour. The unit depressured in approximately 15 minutes, however, due to the excess production of hydrogen following the HTHC shutdown, Valero continued to flare hydrogen. Valero submitted a Notification of Case by Case insignificant activity on July 11, 2014 to cover emissions from Hydrogen flaring; therefore, hydrogen flaring was not considered within the duration of this event. Valero exceeded hourly permitted emissions for hydrogen sulfide, volatile organic compounds and sulfur dioxide at Flare 4 for one hour.

Discharge Preventable - No

The incident was not reasonably preventable. Upon investigation, it appears that liquid carryover in the dry gas seal system caused seal failure leading to the shutdown of the compressor. This is the first observance of such a problem in about 7 years of reliable operation of this machine. Furthermore, the original design and results of our routine inspections of this compressor (during maintenance turnaround) did not provide cause to expect this malfunction.

Notes/Remedial Actions

Shutdown of HTHC unit. Air monitoring was conducted downwind of the refinery. No procedures or preventive measures given at the time of the report. Follow up report lists the following measures identified to prevent recurrence: 1) Review this incident with affected personnel and attach sign off sheet 2) Investigate installing knock out put upstream on dry gas seal (DGS) panel inlet filters with continuous blowdown 3) Investigate the need for level indication and drains on the make-up gas (MUG) discharge pulsation dampers 4) Use recycle gas to supply panel when sufficient differential pressure is available and modify procedures accordingly 5) Evaluate the functionality of the TriLogger system and determine if upgrades are needed 6) Review the lubrication program for HTHC compressors 7) Run drain lines from the dry gas seal panel filters to a safe location for liquid removal