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Valero (1238), Meraux
Releases of Hydrogen Sulfide
| LDEQ Accident Number Accident Date |
Point Source(s) | Notes | Amount of Release |
| 95731 2007-04-28 | Heat Exchanger in the Distillate Hydrotreater (DHT) Unit | Cause: weld failure- release came from a small hole in the side of a heat exchanger in the Distillate Hydrotreater (DHT) Unit. Followup: No Information Provided Notes: There is no information as to whether this incident was preventable or not. Remedial Measures -the distillate hydroeater was removed from service and the exchanger was sent off for failure evaluation. The exchanger is scheduled to be repaired and returned to the plant in about 10 days. At that time, the Distillate Hydroeater will be returned to service. | 53.0 pounds |
| 103034 2008-02-12 | FLARE - South Flare | Cause: the incident occurred shortly after a line of sever storms swept through the area. MOUSA experienced a malfunction (loss of flame) at the South Flare. Followup: Yes Notes: This was a self report to LDEQ from Murphy. At the time this report was made the incident was under investigation and a root cause analysis was not available. Bucket Brigade was not provided with a copy of the follow up report. | 104.0 pounds |
| 102619 2008-01-21 | FLARE- pressure relief valves in the #2 SRU complex / North and South Flares | Cause: leaking pressure relief valves in the #2 SRU complex. Followup: No Information Provided Notes: This incident was not preventable because the PRV malfunctions were not predictable events, as recognized by NSPS for flares that exempt PRV leakage. Also, permitted emission rates at both the North and South flares are based on estimated provided by a refinery-wide survey. not on monitoring data. NOTE: In the report Murphy acknowledges the flow to the North Flare could not be reliably ascertained (no reason given why it couldn't be), the quantity can only be estimated. It was estimated that ave sulfur dioxide emissions from this incident were 200 pounds per hour at the North Flare. They claim that MOUSA is currently on the process of developing an advanced flow monitoring system for both flares. I cam up with the total amount of sulfur di | |
| 102451 2008-01-20 | Instrument Air Compressor - #3 SRU Malfunction | Cause: the air register to the Incinerator failed closed, starving the Incinerator of combustion air and resulting in a flameout in the #3 SRU Incinerator. The air register malfunctioned due to ice formation in the instrument. (overnight temperatures in the area were below freezing). The root cause was moisture in the instrument air from an instrument air compressor. Followup: No Information Provided Notes: This incident was preventable because the instrument air line was not run through a drier, and MOUSA has no standard to address this issue. Remedial Measures - MOUSA published a standard that all instrument air from compressors must be run through driers. | 51.0 pounds |
| 112011 2009-01-13 | #3 SRU Incinerator | Cause: The flame on #3 SRU Incinerator's burner went out. Followup: No Notes: RQ not exceeded. Burner was re-lit to resume normal operations. Cause is under investigation. | 15.0 pounds |
| 127860 2010-11-22 | FLARE: #2 SRU [#1-93]; North Flare [EPN 20-72] | Cause: Refinery letter indicates that facility flared sulfur dioxide from the North Flare due to the shutdown of the #2 SRU. Emissions were also released from the incinerator stack. A root cause analysis will be conducted to determine the trigger for the shutdown.
FOLLOW-UP: Level indicator failed at #1 SWS Overhead Receiver and #1 SWS Off-Gas knockout Pot (SA-V-102). This caused erratic flame at SRU furnace ultimately causing safety shutdown. Root cause was formation of ammonia salts plugging the level indicators; this was "the result of insulation and steam tracing on these level indicators that did not conform to design conditions. Some insulation was not in place and some steam tracing was not in contact with the process piping." DEFERRED MAINTENANCE. Followup: No Notes: RQ. Shut down unit and steamed out level indicators. Restored the insulation and steam tracing on the level indicators to design conditions. | 15.0 gallons |
| 126231 2010-09-08 | #2 FCCU Reactor Vessel | Cause: Refinery letter states that a small hole developed in the #2 FCCU reactor vessel. Followup: No Notes: BRQ. The hole was repaired, and the unit was returned to service. | 0.0 pounds |
| 135917 2011-12-14 | #3 SRU Incinerator stack | Cause: On December 14th Valero experienced excess emissions of sulfur dioxide and hydrogen sulfide at the #3 SRU Incinerator (EPN #5-00) due to automatic safety shutdown of the #3 SRU. Varying rates of emissions were released at the #3 SRU Incinerator stack while the #3 Tail Gas Treater (TGT) was bypassed as Valero worked to restart the unit. Followup: No Notes: Valero immediately enacted its Sulfur Shredding Plan to reduce the amount of acid gas routed to the unit, thereby reducing the emissions to the incinerator. The wind was from the NE at 5-10 mph during the incident. No allegations of impact were received from neighbors in the surrounding community. The episode occurred from approximately 12:45 pm until 6:40 pm on 12/14/11 and from 9:00 pm until 6:20 am on 12/15/11. Valero followed its operating procedures as described in MACT UUU Startup, Shutdown and Malfunction Plan in securing and restarting the unit. | 35.0 pounds |
| 144600 2012-11-11 | discharge piping of #2 HiJet discharge piping of #2 HiJet and North Flare North Flare | Cause: Valero experienced excess emissions of hydrocarbon vapors and H2S from a pin-hole leak on the discharge piping of the #2HiJet. The #2 HiJet collects low pressure sour gas from several units in the refinery, compresses it, and routes it to amine treatment for use in the refinery fuel gas system.
In the final written notification dated March 11, 2013, Valero determined the root cause to be inadequate system design for corrosion prevention. The leak was caused by pitting corrosion on a piping elbow that was installed in 2010. This short service life indicates an aggressive corrosion mechanism that was not originally anticipated by Valero. Valero conducted ultrasonic and radiography surveys of this line and discovered lower than expected wall thickness in some areas and debris or sludge building obstructing flow in several locations. Low points allowing moisture and solids buildup can cause areas of aggressive corrosion in wet, hydrogen sulfide service. Valero also believes that the pipe metallurgy in this case, carbon steel, should be re-evaluated for fitness for service under these particular process conditions. Followup: Yes Notes: Valero quickly diverted the gases normally collected by the #2 HiJet to the flare and shut down the #2 HiJet. Valero then reduced charge rates of the affected units to minimize SO2 emissions at the flare and began the process of transferring some of the diverted gases to the #1 HiJet for recovery. The #1 HiJet has a lower capacity than the #2 HiJet and cannot take all the gases collected by the #2 HiJet. The Vacuum Unit Hotwell Offgas remained in the flare and lean amine to the Hotwell Offgas Scrubber was maximized to reduce SO2 emissions at the flare. Valero discovered that the valve separating the leaking pip and the #1 Amine Low Pressure Knock Out Pot was leaking by and sour gas continued to leak to the atmosphere. Valero installed a temporary hose upstream of the leak to allow the leaking section of the piping to be pressurized with Nitrogen and swept to the flare from a point downstream of the leak. Within minutes of starting the Nitrogen sweep, H2S was no longer detected in the area and the Total Sulfure Analyzer on the flare indicated a significant increase in the flare line. This caused SO2 emissions at the North Flare to exceed RQ. Valero installed a clamp on the leaking section of the pipe and restarted the #2 HiJet Valero issued a second and final follow up report to this incident on March 11, 2013 in which Valero determines the root cause of the release to be inadequate system design for corrosion prevention and believes pipe metallurgy should be re-evaluated. | 131.0 pounds |
| 143178 2012-09-23 | North Flare | Cause: Units were in a start up after a leak on a refinery fuel gas line required a shutdown. Followup: No Notes: According to the notification report submitted by the facility, the facility reported a release from the fuel gas system. The fuel gas leak did not release a reportable quantity of flammable gas, however sections of the fuel gas system had to be isolated to perform repairs. Valero completed the start up of the Reformer and NHT according to procedure. Fuel gas leak happened 9/22/12. Sulfur dioxide release during Reformer/NHT startup happened 9/23/12. | 3.0 pounds |
| 143176 2012-09-23 | North Flare | Cause: Valero reported excess emissions of sulfur dioxide and hydrogen sulfide at the North Flare during a start up of the Reformer unit. Valero continuously measures SO2 and H2S emissions at the North Flare. After 15 hours of Hydrogen flaring, the indicated sulfure content began to rise in an erratic, saw-toothed trend that was inconsistent with process conditions. Routine grad sample monitoring of this Hydrogen confirmed it to be essentially sulfur free. Within 1 hour of the end of Hydrogen flaring, the Total Sulfur readings returned to normal and the erratic saw-toothed trend stopped.
Valero has evaluated the plant conditions and data recorded during this event and has concluded that the indicated Total Sulfure concentration was in error for the last 7 hours of flaring. Valero does not know what caused the erroneous readings, but the erratic, saw-toothed pattern trend was similar to previous episodes when the sample lines have become plugged with liquids. Valero will continue to investigate this event and work to identify and correct the cause of the erroneous readings. Followup: No Notes: 40 pounds of sulfur dioxide and less than 1 pound of hydrogen sulfide were released at the North Flare. Valero will work with the manufacturer to determine the cause of the Total Sulfur Analyzer malfunction and any possible corrective actions. | 1.0 pounds |
| 143223 2012-09-03 | North Flare | Cause: Incident occurred following Hurricane Isaac at the North Flare during start up of the Hydrocracker unit.
Valero has determined the cause to be the system design of the Hydrocracker/Hydrotreater Unit. Under normal operations, gases produced in the Hydrocracking/Hydrotreating Reactors, including H2S, are completely stripped out by steam in the Ore-Fractionator Stripper and sent to amine contractors for treatment; they do not pass into the Fractionator and on to the Fractionator Overheard Receiver. Consequently, the Fractionator Overhead Receiver was not designed with gas handling capabilities.
Manual venting to the flare is the only available method of controlling an increase in pressure caused by gas carryover from the Pre-Fractionator Stripper.
The design deficiency becomes apparent during unit start up because gases are produced prior to the ability to introduce stripping steam to the Pre-Fractionator Stripper. Stripping steam cannot be introduced until the unit is at the proper operating temperature. Operational experience has shown that even once stripping steam can be introduced, its use is limited at the low charge rates during a start up because excess steam causes erratic flows in the heater passes and delays the completion of the start up.
A contributing factor in this event was that De-Asphalted Oil (DAO), a higher sulfur content feed, was introduced to the Hydrotreater prior to reaching adequate stripping steam rates in the Pre-Fractionator Stripper. Followup: Yes Notes: Valero will engineer and install a "start-up vent" that will direct the gases vented from the Fractionator Overhead Receiver to be collected by the refinery's HiJet, treated for H2S removal, and used in the refinery fuel gas system. Valero will also revise the Hydrocracker/Hydrotreater startup procedure to delay the introduction of DAO into the Hydrotreater feed until adequate stripping steam rates have been established. According to the LDEQ's list of reportable quantities, the reportable quantity for sulfur dioxide is 500 pounds. | 1.0 pounds |
| 141477 2012-07-22 | North Flare, South Flare, #2 SRU Incinterator Stack; Vaccuum Tower Bottoms North Flare, South Flare, #2 SRU Incinerator Stack, Vacuum Tower Bottoms Crude Unit Fire | Cause: Valero experienced a fire in the Crude Unit. Valero reported excess emissions of sulfur dioxide, hydrogen sulfide, and particulate matter from the fire, flaring at the North Flare and South Flare and excess emissions at the #2 Sulfur Recovery Unit (SRU) Incinerator Stack.
Valero was in the process of starting up the Crude Unit following an electrical transformer failure which occurred in the Vacuum Unit on July 20. Incident number 141430 associated with the power failure describes details about the power failure and emissions released directly related to the event on that date. An 8 inch piping elbow in the Crude Unit failed, releasing Vacuum Tower Bottoms (VTB) onto adjacent piping and equipment. The hot product ignited, creating a fire in the pipe rack and a pool fure beneath the Crude Unit desalters and several nearby heat exchangers. The crude unit fire began at 0130 hours on July 22, 2013. The fire was "contained" at 0330 hours, and was extinguished at 0650 hours. The total time duration of the fire was 5.4 hours. The total flaring duration lasted 40.5 hours.
Valero concluded that the triggering event was the failure of a piping elbow which resulted from a thinned wall due to high-temperature sulfidation corrosion. The elbow was of carbon steal construction, in a service requiring chrome alloy construction. Valero concluded that the root cause was that poor quality control practices and procedures were utilized when the elbow was installed in 1990 by the previous owner of the refinery. Followup: Yes Notes: Shutdown procedures were quickly initiated for all refinery units while the Valero Emergency Response Team responded to the fire. During the event and for part of the day, periodic flaring occurred as units were placed in safe condition. The fire lasted for a duration of 5 hours 24 minutes. Flaring associated with the refinery shutdown occurred for a duration of 40 hours 30 minutes. Sulfur dioxide, estimated at 2534 pounds, and hydrogen sulfide, estimated at 27 pounds, was released at the North Flare, South Flare, and the #2 SRU Incinerator Stack. Sulfur dioxide, estimated at 3382 pounds, and hydrogen sulfide, estimated at 5 pounds, was released from the uncontrolled burning of Vacuum Tower Bottoms in the fire. Before Completion of the repairs and startup of the Crude Unit, Valero conducted PMI testing of all piping circuits potentially subject to sulfidation corrosion in the Crude and Vacuum Units. During this process, some pipin and one additional carbon steel elbow were discovered and replaced. Valero will increase the inspection frequency from once every ten years to once every 2-3 years, which is more frequent than the 5-year inspection interval specified by industry standards for Class 1 piping. | 32.0 pounds |
| 141430 2012-07-20 | North Flare, South Flare, and #2 SRU Incinerator Stack | Cause: Valero experienced excess emissions of SO2 and H2S at the North Flare, South Flare, and #2 Sulfur Recovery Unit (SRU) Incinerator Stack due to a sudden electrical transformer failure that cut power to several process areas within the refinery.
Valero determined the root cause to be an electrical failure caused by water intrusion into the air terminal chamber on the 13.8 KV side of the transformer and inadequate insulation on the bus bar and connections. It appears that when the transformer was installed the 13.8KV incoming cables were too short to reach the transformer bushing so a field designed buss work and air terminal chamber was used. This locally designed air terminal chamber proved inadequate to protect the transformer breaker were improperly set and allow too much current to flow to the fault which caused voltage to sag across the reinfery and unnecessary tripped loads that upset other units. Followup: Yes Notes: The refinery initiated shutdown procedures for all affected units and followed the MACT UUU SSM Plan to recover the #2 Sulfur Recovery Unit (SRU) and #2 Tail Gas Treater (TGT). The #2 TGT was bypassed during the upset and subsequent startup. All refinery transformers were visually inspected for signs of water intrusion. Water was found in one other transformer of the same design which was removed and the air terminal box was sealed. The damaged transformer was replaced and a new overhead cable was used to replace the underground cable that was too short. Relay trip settings were changed to better coordinate and protect equipment and prevent unnecessarily upsetting other units. Valero has initiated a project to design and install appropriate terminal boxes in place of the locally designed ores for the three remaining transformers of the same design on site. According to the LDEQ's list of reportable quantities, the reportable quantity for SO2 is 500 pounds. | 19.0 pounds |
| 138647 2012-04-10 | North Flare & South Flare North Flare, South Flare, #2 SRU Incinerator, #3 SRU Incinerator | Cause: The root cause of the event was found to be equipment failure at the Entergy substation adjacent to the refinery. Due to a total power interruption at the refinery, units underwent safety shutdowns, which included venting high rates of gases to the North Flare and the South Flare. There were periods of excess opacity at both flares, as there was no controlling steam available. The boilers were also affected by the power outage. As startups proceeded, the refinery experienced some noise from relief valves and some additional sulfur dioxide emissions at the North Flare.
Entergy reported that the power interruption was caused by a severe electrical fault at a 13.8 kV tie breaker at the Meraux Substation. Entergy found no evidence to support a definitive root cause. There was some evidence of bird nesting in the immediate area of the fault. Followup: Yes Notes: The refinery shut down all units, per written procedures. Once power was restored to the refiner, the refinery assessed and methodically restarted each unit. The refinery received one citizen complaint for odor during this event. | 135.0 pounds |
| 138540 2012-04-03 | North Flare | Cause: An unplanned shutdown and subsequent startup of the Hydrocracker Unit (HCU) occurred. The HCU charge pump tripped after its lube oil pump failed. Possible causes offered by Valero, as of 06/15/12, include a lightning strike and an equipment malfunction. The cause is under investigation at this point, and the refinery promised a follow up letter with the results of the investigation. Followup: Yes Notes: Per written procedures, the refinery shut down and started up the Hydrocracker Unit. | 49.0 pounds |
| 137051 2012-02-07 | North Flare | Cause: The emissions occurred during startup of the Hydrocracker Unit after a planned maintenance turnaround. The exact cause is under investigation, as of 02/14/12. Followup: No Notes: The refinery made some pressure adjustments in the unit to reduce the emission rate at the flare, and then the startup was completed. The incident is under investigation, which will result in a plan to prevent recurrence. | 30.0 pounds |
| 150231 2013-08-08 | #2 SRU | Cause: Valero experienced excess emissions of SO2 and H2S at the #2 Sulfur Recovery Unit (SRU) and several refinery fuel gas-fired sources due to an unexpected shutdown at the #2 SRU.
Valero Maintenance personnel were in a satelite equipment building to replace a cooling fan on the Uninterruptable Power Supply (UPS). When an electrician opened the cabinet to identify the cooling fan, the UPS shut down and power was lost to several key fueling-gas valves on the #2 Sulfur Recovery Unit (SRU). The valves moved to their fail safe position (shut) and the #2 SRU shutdown. Followup: No Notes: The electrician manually restored power to the #2 SRU fuel gas valves via the manual bypass switch on the UPS. After the Shutdown of the #2 SRU, Valero cut stripping to the #1 Ademine Unit to prevent acid gas flaring. This eventually resulted in increased Sulfur Dioxide emissions from heaters due to elevated hydrogen sulfide in the fuel gas system. The static switch control card was replaced and the UPS was returned to service approximately two hours after it had failed. Valero will also evaluate the following actions to further decrease the likelihood of re occurrence: 1) Replacing the UPS with a newer, more reliable model, 2) Changing out the 120 VAC fuel gas valves to 24 VDC valves that are then powered by the more reliable Distributed Control System (DCS) power supplies. Performing a test of the DCS power supply. | 16.0 pounds |
| 150026 2013-07-30 | Pressure safety valve in Hydrocracker Unit | Cause: On 7/30/2013, SPOC received a citizen complaint of black smoke released due to flaring from Valero-Meraux. The environmental manager stated that flaring had occurred at the time of the complaint. The flaring (north flare) was a result of a mixture of primarily hydrogen and some VOC's released by a pressure safety valve on the hydrocracker unit. The flaring continued for 16 hours when processes were stabilized at the ROSE unit. Followup: No Notes: LDEQ took no further action | |
| 148798 2013-05-17 | North Flare, #2 and #3 SRU, Heaters, Reboilers | Cause: On May 17, 2013 at approximately 15:43, Valero experienced excess emissions of Sulfur Dioxide at the North Flare, the #2 and #3 Sulfur Recovery Units, and several refinery fuel gas-fired sources due to an unexpected shutdown of the #3 SRU. The #3 SRU shut down on high burner pressure caused by a plugged condenser seal leg.
After several unsuccessful attempts to unplug and restart the #3 SRU, Valero determined that the unit could not be restarted and completely shut down the unit. The Gas-Oil Hydrocracker/Hydrotreater was also shut down and refinery charge rates were reduced accordingly.
Valero opened up the unit for inspection and discovered that catalyst from one of the reactor beds had migrated into the condenser and caused the plugging in the seal legs. Valero could not definitively identify the exact cause of the catalyst migration, but believes that it was most likely due to improper catalyst loading during the last catalyst replacement in 2010. Followup: Yes Notes: Valero immediately initiated its sulfur shedding procedure and attempted to unplug the #3 SRU condenser and restart the #3 SRU. Valero transferred as much of the remaining sulfur load to the #2 SRU as the unit's capacity would allow. Before the sulfur shedding procedure reduced the sulfur load to within the capacity of the #2 SRU, hydrogen sulfide entered the refinery fuel gas system and was combusted to sulfur dioxide in the refinery heaters and boilers. Hydrogen sulfide concentrations in the refinery fuel gas system returned to less than the 162 ppm NSPS Subpart J limit at approximately 05:14 on May 18, 2013. To prevent recurrence, Valero reloaded the #3 SRU with new catalyst and ensured that the catalyst was properly loaded and supported with additional support media. Valero plans to install a smaller mesh screen on top of the existing quarter inch screen that currently supports the catalyst bed and support media. | 10.0 pounds |
| No LDEQ Reported 2013-05-03 | North Flare | Cause: On May 3, 2013 starting at approximately 02;00, Valero experienced excess emissions of Sulfur Dioxide and Hydrogen Sulfide at the North Flare during startup of the Gas Oil Hydrocracker/Hydrotreater Unit (HCU) following a planned maintenance outage and catalyst replacement. Because the catalyst was new, this particular startup include a procedure for sulfiding the catalyst prior to resuming normal operations. Sulfiding consists of circulating the feed in the reactors with an additive chemical to produce H2S, which is then maintained at a high concentration in the Recycle Gas for a period of time to allow the sulfides to deposit on the catalyst.
Based on an initial assessment of the available data, excess emissions during the HCU startup are associated with the following:
1. The pressure safety valve (PSV) on the fractionator tower opened to flare.
2. The PSV on the Cold Separator was found to be leaking by the flare.
3. The Recycle Gas Compressor tripped and activated an automatic unit depressurization to flare.
4. The PSV on the Cold Separator opened to the flare.
5. The PSV on the Fractionator Tower opened to flare a second time.
This incident is currently under investigation and Valero will submit additional information upon completion. Followup: No Notes: While the PDF of the attached document bears the LDEQ # 147895, this number is also linked to an incident of a different date (April 5, 2013). Valero reduced pressure to reseat PSV's that had lifted and attempted to stop the leakage on the Cold Separator PSV. Sulfur dioxide estimated at 3131 pounds and hydrogen sulfide estimated at 34 pounds were released during the "start up period" 5/3 02:00 to 5/4/13 22:00. Sulfur dioxide emissions associated with the leaking Cold Separator PSV have continued at approximately 20-30 pounds/hour. As of 08:00 on 5/10/13, an additional 3932 pounds of sulfur dioxide and 43 pounds of hydrogen sulfide are estimated to have been released. | 77.0 pounds |
| 148510 2013-05-03 | Cold Separator PSV in the Gas Oil Hydrocracker/Hydrotreater Unit | Cause: On May 3rd 2013, starting at approximately 2:00, Valero experienced excess emissions of sulfur dioxide and Hydrogen Sulfide at the north flare during startup of the gas oil Hyrdocracker/ Hrydrotreater Unit (HCU) following a planned maintenance outage and catalyst replacement.
Excess emissions during the HCU startup were associated with the following events:
1. The Pressure Safety Valve (PSV) on the Fractionator Tower opened to the flare
2. The PSV on the cold seperator was found to be opened to the flare
3. The Recycle Gas Compressor (RGC) tripped and activated an automatic unit depressurization to the flare.
4. The PSV on the Cold Seperator Opened to the Flare
5. The PSV on the Fractionator Tower opened to the flare a second time
Valero determined the root cause of the PSV actuations to be inadequate startup procedure.
Valero determined the root cause of the RGC trip to be an instrument technician lifting the instrument wires for a thermocouple that provided a shutdown interlock. Contributing factors to this root cause were:
1. Neither the operator nor the instrument technician was aware that this thermocouple provided a shutdown interlock
2. The instrument technician did not reference any documentation to verify that this transmitter was a possible Safety Critical Instrument
3. The reference documentation was inadequate
4. The instrument was not labeled in the field as a Safety Critical Instrument contrary to Valero standard procedure
7/2/2013 report states that written notification was submitted on 5/10/2013. This documentation is not available on the LDEQ document database. Followup: Yes Notes: Valero reduced pressure to reseat PSVs that had lifted and attempted to stop the leakage on the Cold Separator PSV. Valero shut down the HCU on 5/13/13 and replaced the Cold Separator PSV. Valero will revise HCU startup procedure to include a maximum charge rate limit and maximum Cold Separator pressure limit during sulfiding and also to ensure that the Cold Separator pressure control valve is initially lined up for feed introduction into the unit. Valero repaired the thermocouple and corrected the documentation to reflect that it is a Safety Critical Instrument. Valero has also labeled this instrument in the field. Valero will also finalize a Safety Critical Instrument List in the HCU to provide a reference document for all critical instruments and to label these instruments in the field. | 109.0 pounds |
| 147895 2013-04-05 | South Flare; #3 SRU; Area 1 Fuel Drum: Boiler B-7, Boiler TB-01, MDH Heaters; Area 2 Fuel Drum: Reformer Charge Heater; Hydrocracker Boilers Fuel Drum: Boiler B-5, Boiler B-6 South Flare; #3 SRU; Area 2 Fuel Drum: Reformer Charge Heater | Cause: On April 5, 2013 at approximately 08:47, Valero experienced excess emissions of Sulfur Dioxide and Hydrogen Sulfide at the South Flare, the #3 Sulfur Recovery Unit (SRU), and several refinery fuel gas fired sources due to a loss of power to the refinery's Distributed Control System (DCS). The DCS is a computerized system used to monitor and control the refinery process units.
At the time of the incident, the most refinery units were shutdown for planned maintenance, only the Reformer, Naptha Hydrotreater (NHT), MiddleDistillate Hydrotreater (MDH), #3 SRU, and the four boilers remained in service. In order to perform work on the electrical distribution system, a temporary generator was installed to power vital loads, including the DCS. Additionally, the DCS Uniterruptible Power Supplies (UPSs) were bypassed for protection so that battery backup was not available.
This temporary power generator dropped offline due to loss of communications between the generator and the engine driving the generator. The root cause of the loss of communications was a loose termination connection on a communications cable.
The loss of the DCS caused the immediate shutdown of the remaining refinery units. Upon shutdown of the #3 SRU, field operators cut stripping steam to the #2 Amine unit to prevent acid gas flaring. This allowed some H2S to enter the refinery fuel gas system which was then combusted to SO2 as the fired sources were returned to service. The bulk of the SO2 emissions came from the actuation of a Pressure Safety Valve in the MDH that vented H2S containing material to the South Flare. Followup: Yes Notes: The DCS was restored in less that 25 minutes. Valero restarted all four boilers, the #3 SRU, and the MDH. The Reformer Charge Heater was re-lit as part of a controlled shutdown and the NHT was shutdown. SO2 emissions from the North Flare occurred on 4/5/13 from 08:47 to 4/5/13 22:51 for a duration of 14.1 hours (14 hours and 6 minutes). An estimated 2417 pounds of SO2 and 10 pounds of H2S were released. Power to the DCS was quickly restored and the affected units were shutdown in a controlled manner. The rental company technician for the generator quickly identified the loose termination connection as the issue, corrected the loose termination, and placed the generator back online in approximately ten to fifteen minutes. Power to the DCS was quickly restored and the affected units were shutdown in a controlled manner. Valero requested a backup generator from the rental company as a spare for the one that had tripped, which arrived later that day. | 10.0 pounds |
| 147349 2013-03-15 | North Flare | Cause: On March 15, 2013 at approximately 08:40, Valero experienced excess emissions of Sulfur Dioxide at the North Flare during a planned shutdown of the Hydrocracker/Hydrotreater Unit.
Valero was conducting a normal shutdown for a planned maintenance turnaround. During start ups and shut downs, H2S containing gases can pass through the Pre-fractionator stripper and accumulate in the Fractionator Overhead Receiver. The Fractionator Overhead Recveiver has no means of removing this gas, so Valero must vent it to the flare to prevent the pressure safety valve from lifting. The root cause of excess sulfur dioxide emissions from the Hydrocracker/hydrotreater during start ups and shutdowns has been identified from previous incidents to be inherent to the original design of the unit. Followup: No Notes: As a corrective action for previous incidents, Valero designed a vent line that will direct the gases vented from the Fractionator Overhead Receiver to the refinery's HiJet so that these gases will no longer need to be flared during startups and shutdowns. Valero will install this vent line during this maintenance turnaround. SO2 emissions from the North Flare occurred on 3/15/13 from 08:40 to 3/16/13 00:00 for a duration of 15.34 hours (15 hours and 20 minutes). Valero completed the shutdown of the Hydrocracker/Hydrotreater Unit according to procedure. Valero will install the vent line designed to prevent the Fractionator Overhead Receiver from being flared. | 12.0 pounds |
| 147203 2013-03-08 | North Flare | Cause: On March 8, 2013, at approximately 01:34, Valero experienced excess emissions of Sulfur Dioxide at the North Flare during the start up of the Hydrocracker/Hydrotreater Unit.
On March 5, 2013, Valero discovered an oil leak on an electrical transformer in the Reformer Unit. In order to de-energize and repair the transformer, Valero conducted a controlled shutdown of the refinery. The root cause of excess SO2 emissions from the Hydrocracker/ Hydrotreater during start up has been identified from previous incidents to be inherent to the original design of the unit. The most recent previous incident, SERC Incident # 12-05963, occurred on 9/3/12.
As a corrective action for the 9/3/12 incident, Valero designed a vent line that will direct the gases vented from the Hydrocracker/Hydrotreater Fractionator Overhead Receiver to the refinery's HiJet so that these gases will no longer need to be flared during startup. Valero was planning to shutdown the Hydrocracker/Hydrotreater on 3/15/13 and install this vent line prioer to this unplanned shutdown to repair the transformer. Followup: No Notes: Valero completed the start up of the Hydrocracker according to procedure. Valero will shut down the Hydrocracker/Hydrotreater on 3/15/13 as originally planned and install the vent line designed to prevent the start up gases from being flared. | 6.0 pounds |
| 147091 2013-03-01 | North Flare | Cause: 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. Followup: Yes Notes: 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. | 8.0 pounds |
| 146616 2013-02-10 | North Flare, South Flare, Area 1 Fuel Drum, Area 2 Fuel Drum, Area 4 Fuel Drum, HC Heaters Fuel Drum, HC Boilers Fuel Drum, #2 SRU, #3 SRU | Cause: On February 10, 2013, Valero Refining - Meraux LLC (Valero) experienced excess emissions of sulfur dioxide (SO2) and Hydrogen Sulfide (H2S) from all in service refinery heaters and boilers, the #2 and #3 Sulfur Recovery Unit (SRU) Incinerator Stacks, and the North and South Flares due to an unexpected shutdown of the #3 SRU. Shortly after the #3 SRU shut down the #2 SRU tripped offline as well. The #2 and #3 SRUs generated excess emissions due to these shutdowns and the subsequent start ups. Additionally, with both SRUs shutdown, the Amine units became saturated with H2S and were no longer capable of removing H2S from gaseous refinery process streams. As a result, the H2S concentrations in the refinery fuel gas and hydrotreater recycle gas systems began to increase. Elevated concentrations of H2S were then combusted in the refinery's heaters and boilers and in the North and South Flares.
Root Causes:
1. Loss of 4160 Volt power to the #3 SRU Main Air Blower and #2 Lean Amine Pump. The investigation identified a 30 second power loss but was unable to identify the exact root cause because the plant power monitoring system was not running at the time.
2. The #2 SRU trip was caused by the failure to switch the acid gas interconnect line control scheme from flow control to pressure control.
The episode occurred from approximately 06:42 on 2/10/13 to 01:13 on 2/13/13 for a duration of 66.5 hours. Followup: Yes Notes: Valero initiated the Sulfur Shedding Procedure and followed the MACT UUU SSM Plan to recover the #2 and #3 SRUs. Valero received reports of multiple citizen complaints called into the St. Bernard Fire Department. The wind direction of 2/10/13 placed the Valero Community Ambient Monitoring Site downwind of the refinery during the period of highest emissions and mobile ambient monitoring was performed by Valero and a third party. The highest single monitoring reading was 2.8ppm SO2; odors may be detected at this level. | 304.0 pounds |
| 158394 2014-08-28 | Gas Condensation Unit | Cause: Community complaint of foul odors from near Valero submitted on August 28.
According to the e-mail from Mr. Stubbe (Manager Environmental Engineering), the project and turnaround activities that commenced in late July continue. The letter explained that a review of refinery operations from the evening of 8/28-29 revealed only a single incident that occured approximately half an hour after the complainant's call to SPOC. While demolishing a section of piping on the Gas Condensation Unit, a small quantity of liquid exited a flange. This is believed to have set off the alaram on the nearby worker's personal H2S detector. No Reportable Quantities (RQ) were exceeded, no emergency condition existed, and no odor complaints were received from inside or outside the plant.
During this period, the wind was blowing from the ESE at approximately 3-5 mph. Background levels of H2S and SO2 were measured at the Community Air Monitoring Station on Ventura Drive.
*Starting 7/28/14, the refinery executed a planned shutdown of several process units for project work and scheduled maintenance. Affected units include the Hydrocracker, the FCCU, the Alkylation Unit and the ROSE unit. Followup: No Notes: Related to incident #'s 158330, 158905, 158516, and 158452. | |
| 158330 2014-08-26 | Cause: According to the e-mail received from Mr. Stubbe, the project and turnaround activities that commenced in late July continue. Valero has been preparing its flare headers for binding and piping tie-in work associated with the upcoming Flare Gas Recovery Project. In order to ensure stable combustion at the flares, Valero has periodically introduced NSPS J-compliant fuel gas into the headers. The flares appearance (flame size, color, etc) has varied more than normal due to these activities. No unusual odor or noise has been observed. There were no reportable upsets or malfunctions during this period. The wind was variable. It blew from ESE during the evening of the 26th, later switched to northeasterly, and then returned to ESE during the afternoon of the 27th. Hydrogen sulfide concentrations measured at the Ventura Drive air monitoring station remained within their normal band (0.003-0.006 ppm). One citizen complaint was received during this period regarding vehicle and pedestrian noise along the refinery's eastern fence line. This appears to be unrelated to the complaints received by your office.
*Starting 7/28/14, the refinery exectued a planned shutdown of several process units for project work and scheduled maintenance. Affected units include the Hydrocracker, the FCCU, the Alkylation Unit, and the ROSE unit. Followup: No Notes: related to previous incidents with LDEQ#s 158905, 158516, and 158452 | ||
| 158125 2014-08-16 | Ultra Low Sulfur Diesel Hydrotreater Pressure Safety Valve | Cause: On August 16, 2014 at approximately 22:00, Valero exceeded the reporting threshold for sulfur dioxide (SO2) emissions at the South Flare. Valero calculates flare SO2 emissions based on continuous monitoring of flow and total sulfur concentration in the flare header. The reporting threshold is exceeded when the 24-hour aggregate exceeds the baseline average SO2 emissions by 500 pounds.
Sour water generated in the Ultra Low Sulfur Diesel Hydrotreater (ULSDHT) is accumulated in the High Pressure Stripper Receiver before flowing to one of the two Sour Water Strippers. At approximately 20:00 on August 16th, Valero personnel began redirecting sour water from the #2 Sour Water Stripper to the #1 Sour Water Stripper. During this process, the liquid level increased in the Stripper Receiver and sour water entered the ULSDHT Fractionator, where it flashed into steam. This caused a sudden pressure increase in the overhead line which, in turn, caused a Pressure Safety Valve (PSV) to open to the South Flare.
The root cause of this incident was an improper valve line-up. Operators lacked a clear and adequate procedure for switching between the two Sour Water Strippers, and the high-high alarms did not allow sufficient time to respond to the rising liquid level in the Receiver. Followup: Yes Notes: The feed to the ULSDHT was reduced and sour water was drained from the Stripper Receiver. The sulfur concentration in the South Flare returned to normal. Level alarms in the Stripper Receiver were set to a lower level, allowing additional response time during an upset. Operations procedures were revised to more clearly describe the process of rerouting sour water from one stripper to another. | 9.0 pounds |
| 156601 2014-06-07 | South Flare | Cause: Leaking PSV on compressor in Diesel Hydrotreater Unit to blame for the release.
On June 8, 2014 at approximately 12:00 hours, Valero exceeded the reporting threshold for Sulfur Dioxide (SO2) emissions at the South Flare. Valero calculates flare SO2 emissions based on continuous monitoring of flow and total sulfur concentration in the flare header. The reporting threshold is exceeded when the 24-hour aggregate exceeds the baseline average SO2 emissions by 500 pounds.
Sulfur concentration in the south flare began to increase at 2100 on 6/7/14. At 0830 on 6/8/14, Valero began to flare sweet (low sulfur) propane while starting up the depropanizer section of the alkylation unit, which had been shut down for a week for repairs.
At the same time as this startup, SO2 mass emissions increased to 100-120 lbs/hr. Valero executed its procedure for checking high sulfur sources (Process Safety Valves) and identified a leaking PSV in the diesel hydrotreater unit. Compressor was shut down, and the sulfur concentration returned to normal. Followup: No Notes: There remains some uncertainty about the accuracy of the monitoring at the south flare, as sulfur-free flaring from the alky depropanizer should not have increased SO2 emission rate. Valero provided verbal notification before reaching the emissions threshold. Valero implemented its procedure for checking high sulfur sources (process safety valves (PSV), process vents, etc) and identified a leaking PSV on a compressor in the Diesel Hydrotreater Unit. The compressor was shut down and the sulfur concentration in the South Flare returned to normal. | 17.0 pounds |
| 154085 2014-02-23 | South Flare (EQT 0049, EPN 3-77) | Cause: Valero exceeded the reporting threshold for flammable gas emissions at the South Glare due to a loss of flame. Valero had recently shut down a Diesel Hydrotreating Unit and was purging the unit with Nitrogen to the South Flare. The pilot flame sensor alarmed int the Control room and personnel visually inspected the South Flare and discovered that the flame had been extinguished. Valero stopped the Nitrogen flow and attempted to relight the South Flare, but was delayed because electrical power to the ignition system was off. Valero quickly restored electrical power and re-lit the flare. The pilot flame sensor alarmed cleared and visual evidence of a flame was observed. Followup: No Notes: Valero stopped the Nitrogen flow and re-lit the South Flare. Valero provided verbal notification within one hour of exceeding the reportable quantity for flammable gas. Valero received no citizen complaints and did not conduct a downwind ambient air monitoring. The incident is under investigation so no specific plan of action has been put into effect to prevent recurrence. | 1.6 pounds |
| 153744 2014-02-10 | #2, #3 SRU | Cause: On February 10, 2014 Valero Refining-Meraux experienced excess emissions of sulfur dioxide (SO2) and Hydrogen Sulfide (H2S) from all in-service refinery heaters and boilers, and the #3 Sulfur Recovery Unit (SRU) Incinerator Stack and the North Flare due to an unexpected shutdown of the #3 SRU. Later the #2 SRU tripped offline as well, resulting in excess emissions from that unit. The #3 and #2 SRUs generated excess emissions due to these shutdowns and the subsequent start ups. Additionally, the Amine units became saturated with H2S and were no longer capable of removing H2S from gaseous refinery process streams. Increased H2S concentrations in the refinery fuel gas and hydrotreater recycle gas systems resulted in excess emissions in the refinery's heater and boilers, and in the North Flare. Followup: No Notes: There seems to be a major equipment malfunction that occurred causing the incident however there is no mention of the cause or how it will be prevented in the future. All emissions point sources involved in the accident: No 1 Crude Heather, NTH Charge Heather, NHT Debut Reboiler, NHT Depent Reboiler, Platformer Charge Heater, Platformer Debut Reboiler, Vacuum Heaters, No 2 Alky Reboiler, Hydrocracker/Hydrotreater/Fractionator Charge Heaters, Boiler B-5, Boiler B-6, North Flare Stack, SRU #2 Incinerator, SRU #3 Incinerator | 72.0 pounds |
| 153609 2014-02-07 | North Falre, #2 SRU Incinerator, & Area 2 Fuel Drum | Cause: On 2/7/2014, Valero exceeded the reporting threshold for sulfur dioxide (SO2). While attempting to identify the source of the increased odor in the North Flare header, the #2 sulfur recovery unit (SRU) shutdown.
Valero determined the root cause of the elevated sulfur in the North Flare and the unexpected shutdown of the #2 Sulfur Recovery Unit (SRU) to be open block valve(s) on the Flare Knockout Blowcase [i.e. operator error]. This blowcase is used to periodically drain liquids from either a nearby flare knockout pot or the sour water offgas line feeding the #2 SRU. Liquids are drained into the blowcase and are then pressurized out with natural gas to the #1 Sour Water Stripper. With one or more of the block valves out of position, H2S passed from the sour water offgas line into the North Flare header. Later, to remove the accumulate liquids, the blowcase was pressurized with the block valve(s) still open causing a surge in pressure and flow and possibly entraining liquids through the sour water offgas line to the #2 SRU main burner. The resulting disturbance in the flame pattern was detected by the SRU fire eyes and the unit shutdown. Followup: Yes Notes: Valero conducted a search for the source of sulfur in the North Flare as soon as it was detected. Valero initiated the refinery's sulfer shedding procedure and shifted sulfur loads to the #3 SRU after the #2 SRU shutdown. This incident is similar to an incident that occurred on 5/7/12. Valero discovered that one corrective action from this earlier event has not yet been completed. This action was to install check valve(s) on the lines that drain the sour water offgas line to the blowcase. These check valve(s) could have prevented the shutdown of the #2 SRU, but not the elevated H2S in the North Flare. In addition to installed these check valves, Valero will review the procedure for operating the blowcase and conduct refresher training with the operators. Valero will also modify the current piping configuration that allows water to accumulate in the sour waster offgas line, thereby eliminating the need to periodically drain this line using the blowcase. This work will occur during the next turnaround. | 6.0 pounds |
| 153218 2014-01-08 | South Flare (EQT 0049, EPN 3-77) | Cause: On January 8, 2014, at approximately 21:00 hrs, Valero exceeded the reporting threshold for Sulfur Dioxide at the South Flare. Valero implemented its procedure for checking high sulfur sources (PSV's, process vents, etc.), but found no obvious discharge into the flare header.
After performing several searches for the source and not finding any valves out of position, Valero compared several gas samples to the composition of the gas being flared in the South Flare.
Because of similarities in composition, Valero believes that source of total sulfur for this incident was the recycle gas section of the Ultra Low Sulfur Diesel Hydrotreater (DHT). The unit was shut down and restarted on 1/7/14 due to a cold weather related instrument malfunction. Valero inspected all connections between the DHT recycle gas section and the South Flare but could not determine a definite source.
Valero initially believed that the source of sulfur was likely a weeping Pressure Safety Valve (PSV) on the DHT recycle gas section, so all the PSV's nt hte DHT recycle gas section were sent out for testing and repair during shut down. SO2 emissions at the South Flare returned after turnaround and reinstallation of the PSVs, indicating that the weeping PSV was not the source. Valero now believes that the cause was a continuous source and the total sulfur concentration of the recycle gas became elevated due to the shut down and start up on 1/7/14. The total sulfur returned to baseline levels after the DHT returned to normal operating conditions. Followup: Yes Notes: South Flare SO2 emissions decreased below the RQ on 1/9/14. Valero continuously monitors the total sulfur and flow at the South Flare. | 7.0 pounds |
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