|About the Database
|LDEQ Accident Number
|Amount of Release
|RCCU Flare (EPN 8-84)
|Cause: On December 5, 2013, the three-hour rolling average for teh amount of hydrogen sulfide to the RCCU Flare exceeded its 162 ppm limit and teh 500 pound reportable quantity was exceeded on December 6, 2013 at 15:00 hours. The hydrogen sulfide to the RCCU FLare exceeded teh monitoring capabilities of teh flare's hydrogen sulfide analyzer. As a result, Operations monitored the hydrogen sulfide concentrations by sampling the flare header while trying to identify the source/sources of the elevated hydrogen sulfide.
On December 6, 2013 it was discovered that the dry gas specific gravity analyzer, AT-3812 was incorrectly routed to the flare. By correcting this line up, the hydrogen sulfide in the flare header was reduced and no further hydrogen sulfide reportable quantities were exceeded as a result of this incident.
Notes: Immediately, Operations began a search for the source of hydrogen sulfide routing to the flare. Operations found that the sample return from the dry gas specific gravity analyzer, AT-3812, was incorrectly routed to the flare. On December 6, this stream was rerouted to the RCCU wet gas compressor. Operations flushed the RCCU Elevated flare knock drum and the maintenance drop out drum (which were suspected to be contaminated with hydrogen sulfide as a result of the recent shutdown activities). Unit rate increases were delayed and unit feed rates were maintained during the duration of this incident. To prevent re-occurrence of this incident, routing AI3812 correctly has been included in a Job Aid that Operations developed for troubleshooting situations in which there are high hydrogen sulfide concentrations at the RCCU Flare. Report states that releases of sulfur dioxide exceeded Reportable Quantity only on December 5 and 6. Sulfur Dioxide also exceeded reportable quantity limits on the December 7.
|4-84 Hydrocracker Flare (FE-301)
|Cause: On September 3, 2013, the first and second stages of Motiva's Hydrocracker Unit (HCU) shut down. The shutdown was caused by an instrumentation failure that controlled the lube/seal oil system for the HCU recycle compressors.
On September 6, 2013, the Hydrocracker unit began startup operations.
Notes: Immediately after the unit was shut down and secured, maintenance and engineering immediately investigated and identified the instrumentation failure. The instrumentation and engineering groups are developing an inspection list for the next planned unit shutdown to look for deficiencies in the unit instrument systems. No reportable quantities were exceeded; however the permitted maximum hourly emission rate limit was exceeded for Benzene and Sulfur Dioixide.
|4-84 Hydrocracker Flare (FE-301)
|Cause: On February 18, 2013 Motiva Enterprises in Norco experienced a relase of benzene, butane, flammable gas, hydrogen, hydrogen sulfide, propane, and volatile organic compounds to the atmosphere due to a release valve on the dubutanizer relieving at the Hydrocracking Unit (HCU) and flaring at the Hydrocracker Flare (EPN 4-84). The flaring was caused by an unexpected shutdown of the second stage of the Hydrocracker Unit.
On February 18, 2013 at 0628 hours, the atmospheric relieve valve on the debutanizer at Motiva's Hydrocracking Unit (HCU) relieved, ultimately leading to the second stage of the HCU shutting down. The atmospheric release from the debutanizer column was due to a tube rupture on one of the upright exchangers in the second stage of the HCU. The second stage of the HCU was shutdown to stabilize the unit and minimize safety risks.
Notes: This release began on February 18, 2013 and ended on March 13, 2013. The repair of the ruptured tube on the upright exchangers in the second stage of the HCU was completed on March 11, 2013. Start up activities began once a pressure test was completed on the previously damaged exchanger and were completed on March 13, 2013 at 1600 hours. While the repair was being completed, high purity hydrogen was flared and emissions were below the permitted limits. It was determined that the cause of the tube rupture was as a result of stress corrosion cracking. To prevent this accident from reoccuring, the method to decontaminate the exchanger will change. During the next unit turnaound, the exchanger will be decontaminated using a different wash, which will prevent stress corrosion cracking.
|Cause: On August 8, 2014 Motiva's Hydrocracking Unit (HCU) flared process gas at the HCU elevated flare (FE-301) due to a unit upset. Contractors working in the area inadvertently opened a valve to supply instrument air to their project, but reduced necessary air supply to HCU resulting in loss of instrument air to various pressure relief valved (PRVs). These PRVs, designed to fail in the open position, released process gas to the flare due to loss of instrument air as a safety mechanism causing the unit upset at the HCU.
Notes: Report was submitted by Motiva Enterprises, however the AI number provided was for Shell Chemical Plant-East Side. Motiva and Shell Chemical are located on the same lot and share many processes.
|Butane-butylene reactor, emergency depressuring valve
|Cause: A malfunction of the solenoid on the emergency depressuring valve caused a release of butylenes and highly reactive volatile organic compounds from the OL5 Ground Flare (FG-101).
Notes: Shell Chemical confirmed that no reportable quantities were exceeded. However, the maximum permitted limits for carbon monoxide, nitrogen oxide and particulate matter were exceeded at the OL5 Ground Flare (FG-101). Solenoid was immediately replaced once the emergency depressuring valve was safely isolated from the process.
|charge pump, Hydrocracking Unit
|Cause: Motiva's Hydrocracking Unit (HCU) flared process gas at the HCU Elevated Flare (FE 301) due to the partial shutdown of the HCU. A seal leak was discovered on the charge pump on the second stage of the HCU. Due to the location of the leak, the unit had to partially shut down to complete repairs. Flaring of hydrogen will continue intermittently to stabilize the remaining operating equipment. Flaring ceased once the charge pump was repaired and the unit returned to stable operating conditions. Flaring occurred on June 1 (367 minutes) and June 7 (1069 minutes).
Notes: After the unit was shut down and secured, maintenance and engineering investigated and identified that a seal failure occurred. A repair plan was promptly developed and executed. Due to this incident being a repeat issue in a short period of time, Motiva chartered a full investigation. Findings from this investigation resulted in the installation of additional check valves to control pressure swings and to help manage the integrity of pump seals.