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Refinery power failures: causes, costs and solutions Power outages typically lead to damaging costs for refiners. Strategies are needed to minimise them Patrick J Christensen, William H Graf and Thomas W Yeung Hydrocarbon Publishing Company

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bout 90 seconds into the second half of the 2013 Super Bowl, the American football championship game, half of the stadium lost power — a 34-minute delay caused by a malfunction in a faulty electrical relay that was supposed to monitor the electrical load. This event not only caused much frustration between the teams, fans and workers trying to fix the problem but also cost the broadcast network advertising revenue. The point is that we all take electricity for granted until the lights go out. For most of us, we just endure until the power comes back on. For refineries, however, there are more serious consequences that occur when power is lost. This article is the first of a two-part series examining technology-driven strategies to mitigate refinery power failures and minimise impacts on company earnings. Part 1 discusses the causes and financial costs when a refinery suffers a power disruption. Part 2 focuses on mitigation technologies available to refiners for minimising power disruptions and unplanned shutdowns as well as overall strategies to reduce financial impacts.

Refinery shutdowns happen on a daily basis

average of 1.2 shutdowns per day. As Figure 1 shows, 46% of the shutdowns were due to mechanical breakdowns, 19% were caused by electrical disruptions and power failures, 23% were the result of maintenance, and the last 12% were because of other causes, mostly fires that occurred at the refinery. While some incidences last only a couple of hours, many last multiple days and even weeks. About 92% of maintenance-related shutdowns were unplanned, many due to leaks in piping and different units.

Major causes of power disruptions As Figure 2 shows, 17.6% of refinery power disruptions were the result of electrical equipment failures or refinery processing units having electrical problems. This includes transformers malfunctioning or the FCC unit suffering an electrical failure. Some 16.4% of causes were due to weather events. This includes hurricanes, lightning strikes and wind causing power lines to fall or units to be knocked out of service. While accidents due to weather cannot be avoided,

Electrical: 19% Other: 12%

Hydrocarbon Publishing Company collected data from reports published by the US Department of Energy’s Energy Assurance Daily. The information analysed focused on power failures and disruptions at US refineries. Maintenance: 23% Mechanical: 46% From 2009 to 2012, there were over 1700 refinery shut- Figure 1 Overall shutdowns downs, which equates to an 2009-2012, %

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Surges: 1.9% Breakdown: 17.6%

Weather: 16.4%

Other: 1.9%

Fire: 1.9%

Unspecified: 60.4%

Figure 2 Causes of power disruptions 2009-2012, %

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proper maintenance of cause problems. Power lines can Rotary equipment: 7.0% processing units and electrical be knocked down, lightning Refinery Unspecified equipment can help avoid strikes can disrupt units, and rain processing equipment: units: 24.6% 12.3% breakdowns. can interfere with the steam Unfortunately, over 60% of supply. These are a few of the the causes of electrical examples that show how weather disruptions are not specified. can cause a refinery shutdown. Most of the unspecified In February 2010, Valero’s power failures were listed as Ardmore, Oklahoma, refinery “a power failure occurred at experienced thunderstorms that the refinery and caused flarcaused temporary power outages ing” or similar statements. at several units, reducing runs. Electrical equipment: 56.1% There are multiple reasons Valero reported that it was restorwhy the reports were so Figure 3 Breakdowns causing power ing full production at the plant the vague: the refiner did not disruptions 2009-2012 next day. On 1 December 2011, a know the reason at the time wind storm caused a power outage of the report, there are confidentiality policies and forced several units offline at Chevron’s El that prevented the refinery from reporting the Segundo, California, refinery, halting production causes, or the refinery for whatever reason did until 7 December. Among the affected units was not want to be very specific in its report. The a CDU that caught on fire in the aftermath of the fact that so many are unspecified makes it diffi- electrical failure. Flaring occurred as a result of cult to minimise power disruptions. Therefore, the incident and during the subsequent restart any prevention and protection strategies process. Fire damage to the CDU, six days of deployed by a refinery should include detailed inactivity and flaring all adversely affected the bookkeeping of failed equipment so that statis- refinery’s bottom line. tical analyses or predictive analytics can be In March 2009, Motiva’s Port Arthur, Texas, performed in identifying exact causes to reduce facility experienced lightning that led to a power future incidents, as discussed in part 2 of this outage and also stated a fire. The lightning article. caused a crude unit, two hydrotreaters and a In Figure 3, 56.1% of the failing units were delayed coker to shut down. Unlike Motiva’s electrical equipment such as circuit breakers, experience, in July 2009, Pasadena Refining’s switchgears, transformers and substations. Some Pasadena, Texas, complex experienced a light24.6% of power disruptions were caused by ning strike that disabled all power to the Red refinery processing units such as the FCC unit Bluff Tank farm, which resulted in loss of feed to having electrical issues. About 7% of problems the refinery’s crude unit. The feed was restored were the result of rotary equipment such as with a backup generator, and the refinery was motors and compressors having electrical prob- able to run using backup power and keep operalems. About 12% did not specify the unit or tions online despite the loss of power to the tank equipment that was having problems. farm. In April 2012, Valero’s Norco, Los Angeles, From 2009 through 2012, there were about facility experienced a power surge caused by 320 power disruptions at refineries in the US. In lightning, which caused the hydrocracking unit this section, some of their experiences are to trip. Emissions of sulphur dioxide and hydroreviewed. All of these disruption events were gen sulphide were released during the flaring gathered from the US Department of Energy’s caused by the shutdown. Energy Assurance Daily publication. We chose Although high wind and debris are the most events that provided a clear picture of the causes commonly cited causes of hurricane damage, for and impacts from power disruptions. Gulf Coast refineries in the US, where hurricanes hit most often and hardest, the greatest hurricane Weather problems damage is the result of flooding. Hurricane Isaac, The most common weather event that causes which touched down in Louisiana 28-29 August power failures is a thunderstorm. High winds, 2012, caused extensive flooding, forcing nine lightning strikes, heavy rain and flooding can all Louisiana oil refineries with a collective capacity

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of 2.2 million b/d to shutter about 42% of that capacity by 29 August due to power outages. Backup generators are typically only used for refineries’ most important units. Flood control measures commonly employed at refineries and petrochemical plants on the Gulf Coast include dikes and levees to guard against rising waters, but each storm is different. Normal shutdowns usually take three days, but hurricanes are often unpredictable, making it difficult to schedule a proper shutdown procedure. Restarting after a hurricane is determined by electrical outages on and off-site, so it could take days or weeks. As a result of Superstorm Sandy in late October 2012, Phillips 66’s 238 000 b/d Bayway refinery in the state of New Jersey was idle for over three weeks due to electrical damage sustained from salt water flooding.

Electrical equipment failures Electrical breakdowns are nothing new to any industry. Many units require simple maintenance checks that can help avoid sudden breakdowns. Fires can easily occur in oil or gas-insulated units such as transformers. In January 2009, ExxonMobil’s Beaumont, Texas, coker was shut for unplanned electrical repairs. In July 2010, Citgo’s Lake Charles, Los Angeles, refinery had a fire break out due to faulty electrical wiring, which led to an emissions release. In February 2012, PBF Energy’s Delaware City, Delaware, plant had an electrical issue with the CDU. Two compressors in the catalytic cracker were inoperable due to an electrical issue, which led to flaring. These electrical problems can be easily seen and fixed during routine maintenance before the failures occur. Substations, whether owned by the utility company or the refinery, tend to break down if not properly maintained. In October 2009, Valero’s McKee, Texas, plant had a substation malfunction, which forced units offline. Substation malfunctions have occurred more frequently than many people think. In March 2010, Chevron’s El Segundo, California, refinery shut down due to fire at a substation. And, in August 2011, Tesoro’s Kapolei, Hawaii, complex had a power outage due to a failure at one of the local electric utility’s substations. In May 2010, BP’s Texas City, Texas, refinery had a power blip caused by switchgear failure. Switchgear failures also occur quite frequently.

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The relay that failed at the Super Bowl was a part of the switchgear setup that supplied power to the stadium. Switchgears operate as a protective device against overcurrent and arc flashes. They also need to be properly maintained to avoid failures. A few types of switchgear are oil or gas insulated. A stray spark can cause these to catch on fire and fail. Then there are the obscure reasons that cannot be predicted and happen so infrequently that it is hard to protect against. In November 2012, Valero’s Corpus Christi, Texas, had a power loss that led to flaring due to a rodent contacting the primary power transformer. Transformers that can be accessed should be protected to allow only those working on them to get to them. In February 2010, Western Refining’s Yorktown, Virginia, had an unidentified unit shutdown due a temporary power blip caused by a goose flying into a nearby power line. Unless power lines are put underground, it is difficult to protect them from animals and debris.

Power surges and fluctuations Power surges also occur frequently and can be prevented with circuit breakers or switchgear. In August 2009, ExxonMobil’s Baytown, Texas, complex had a power surge that triggered a small fire in a pipe rack at the refinery’s chemical plant. Power surges can cause fires and cause breakdown in different units. In April 2011, Sunoco’s Philadelphia, Pennsylvania, refinery had a power surge that knocked compressors offline. In May 2011, Phillips 66’s Wilmington, California, facility had a power fluctuation occur, temporarily shutting down several refinery units. Normal operations were restored the next day.

Multiple unit shutdowns Since most refinery units are integrated and sometimes share the same power supply, power failures could lead to the shutdown of these integrated units and the production loss of many refined products, thereby magnifying potential damages. In June 2009, Tesoro’s Kenai, Alaska, facility experienced a power outage. The hydrocracker and isomerisation unit were shut to make repairs. In April 2011, BP’s Texas City, Texas, plant experienced an external power failure that knocked BP’s plant and other refineries in the area offline. Several units, including an alkylation unit, coker

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depreciation and amortisation) of $1 a barrel and a utilisation rate of 85% are assumed. 12000 Depending on cash margins, 10000 profit penalties on the refinery could be considerable, as 8000 projected in Figure 4. A threeday shutdown of a FCC unit 6000 with a cash margin of $1/bbl at 4000 the time of the incident could cost a refinery over $200 000. 2000 On the other hand, when the cash margin was $5/bbl prior to 0 0 1 2 3 4 5 6 7 a shutdown for a week, the Production-time lost, days monetary penalty could be as high as $2.4 million. Refineries Figure 4 Net profit loss due to shutdown on the US West Coast and in the Mid-West can see cash margins and FCC unit were out of commission for more as high as $20/bbl and sometimes higher. A than a week. This amount of downtime leads to a seven-day outage during margins this high can substantial loss in profits. lead to a loss of almost $12 million. Of course, exact loss for each refinery is plant specific. Production loss and profit penalties Nowadays, the loss is even higher, as the FCC When a power failure occurs, a refinery unit or unit is considered an important source for polyunits, or an entire facility must be shut down mer-grade propylene and light cycle oil (LCO) and production is lost. A refiner could post a loss for the production of middle distillates.2 instead of profit in a quarter, and adverse finan- Moreover, steam and power from the regeneracial impacts are further magnified when refining tor turbo-expander contribute part of the plant margins are poor. utilities.3 In a gasoline-centric refinery, gasoline is a mixture of FCC gasoline, alkylate, reformate, Case study hydrocrackate gasoline and also possibly some Phillips 66’s Bayway, New Jersey, refinery was straight-run gasoline from the still tower. down from 28 October to 20 November 2012 However, both FCC and alkylation units contrib- due to Superstorm Sandy. According to the ute to about one half of the gasoline volumes. company, the expenses related to the storm were According to a study initiated by the US $56 million before tax.4 This loss did not include Department of Energy, a loss of one barrel of missed production for over three weeks. Based FCC input will result in a loss of one barrel of on the refinery’s nameplate gasoline production gasoline based on statistical analysis.1 The capacity of 145 000 b/d and distillate production one-for-one relationship is said to be appropri- capacity of 115 000 b/d5, an utilisation rate of ate because of the physical tie-ins between 85% and average spot market prices of gasoline different operating units and limitations in stor- of $2.812/gal and $3.084/gal for distillates in age and distribution systems that transfer New York Harbor during the shutdown period, intermediate feedstocks between units. The FCC estimated revenue loss was over $650 million. unit is the primary production unit in a refinery, Net profit loss ranged from $5.3 million for cash drawing feedstock from the distillation tower margins of $1/bbl to $26.5 million for cash and providing feedstock to the alkylation unit. margins of $5/bbl. US refineries outside the East For a rough estimate, a US Gulf Coast refinery Coast should expect a bigger financial impact, with an average- sized FCC unit of 80K b/d will since East Coast refiners are known to have lose $68K a day for a downed unit if cash much lower refining margins than their peers in margins (which is defined as gross margins other parts of the country. minus operating costs, before interest, taxes, and From a business point of view, missed Net profit/loss, $000’s

14000

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Cash margins = 1 $/b Cash margins = 5 $/b Cash margins = 10 $/b Cash margins = 15 $/b Cash margins = 20 $/b Cash margins = 25 $/b

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shipments to retail outlets at a time of strong demand can lead to a price surge at the pump, resulting in public outcry and possible governmental investigations.6 Undoubtedly, both environmental and retail price issues will generate negative media coverage and severely damage a company’s public relations. A rapid shutdown also increases the danger of mechanical damage. Subsequent repairs to damaged mechanical parts as well as costs of downtime can make power failures even more costly than the earlier estimates. Furthermore, unit shutdowns and restarts are known to reduce energy efficiency and increase the carbon footprint of the operation.

Potential legal liabilities Aside from missed production, outages prompt unnecessary flaring of hydrocarbons to avoid unsafe conditions. Over the past 10 years, the US EPA has entered into settlements with 28 different refineries that are aimed at restricting emissions by the oil industry. The EPA has acquired consent decrees from 105 US refineries in 32 states and territories since December 2000. All of the settlements have involved at least one of four primary pollution types: NOx, SOx, benzene and volatile organic compounds (VOCs). Furthermore, all of the violations involved one or more four key refinery components: the FCC unit, SRU, flares and heaters/ boilers. Excessive flaring can lead to environmental concerns and incur fines imposed by environmental agencies. The potential liability due to a prolonged flaring can cost a refiner a huge sum. For illustration purposes, a fire caused by a corroded pipe that led to subsequent excessive emission at its 245 000 b/d Richmond, California, refinery in August 2012 had forced Chevron to pay $10 million to individuals, area hospitals, city agencies and the Hazardous Materials Program as of January 2013. There are approximately 24 000 civil claims that have been levied against the firm as a result of the flaring at Richmond. Emergency shutdowns because of power failure can also pose safety issues. Sometimes a refinery shutdown will force the need to evacuate workers for safety reasons. In April 2010, BP’s Texas City, Texas, plant experienced an electrical outage that shut off all power and steam to the refinery and forced the evacuation

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of non-essential workers from the plant. Safetyrelated incidents can result in the loss of life along with the potential for millions of dollars in fines and civil lawsuits, not to mention any negative publicity from the event. Previously, BP paid over $87 million in fines issued by OSHA along with undisclosed amounts in civil suits related to an explosion and subsequent fire at its Texas City, Texas, refinery on 23 March 2005 that resulted in 15 worker deaths and over 170 injuries.7

Conclusion As previously noted, about 19% of refinery emergency shutdowns in the US between 2009 and 2012 were caused by power disruptions because of severe weather, poor power quality and electrical equipment malfunctions. Costs to refiners amount to millions of dollars every year due to lost production, repairs to damaged equipment, sending valuable material to flare, possible fines for excessive emissions, and so on. Therefore, equipment vendors, maintenance and reliability servicing companies and refinery technology developers have been seeking technical approaches to prevent power failures, protect equipment, speed up restarts and salvage damaged components. A few of the techniques available include approaches to examine transformer failure due to switching transients, perform transformer end-of-life evaluations, undertake early fault detection and diagnosis in an FCC unit, reduce arc flash energy, predict and diagnose medium-voltage switchgear and rotating machines, and other latest techniques. Power grid reliability can be threatened by anything from severe weather to cyberterrorism. CHP/cogeneration is said to be a good way to preserve power reliability through natural disasters. In the near future, microgrids will play an important role in refinery power reliability and security. Since there are many options available and refiners are often limited by tight budgets, the cost-effective strategy is first to combine electrical outage data and process reliability models and identify the most vulnerable equipment and units. The results assist in sound decision-making on what options and investments to choose in minimising power failures. Finally, disciplines such as actuarial science and enterprise asset management should be included in overall refinery operations management. The objective is to

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ensure that the plant can achieve utmost reliability and highest energy efficiency to maximise profitability while fulfilling safety and environmental requirements. This article is the first of a two-part series from a white paper called Refinery Power Failures: Causes, Costs, and Solutions from Hydrocarbon Publishing Company. The paper is an excerpt from a multi-client strategic report called Refinery Power Outage Mitigations: Latest Technologies and Strategies to Minimize Financial Impacts, to be published in June 2013. Special thanks to Baldwin A Yeung, PE of SAIC, who provided technical assistance for this paper.

1 US Energy Information Administration, Refinery Outages: Description and Potential Impact on Petroleum Product Prices, March 2007. 2 Fluid Catalytic Cracking, 4Q2012 issue of Worldwide Refinery Processing Review, Hydrocarbon Publishing Company (http://hydrocarbonpublishing.com/store10/product.php? productid=B21204&srchkey=) 3 Carbonetto B, Pecchi P, Going ‘green’ with FCC expander technology, Hydrocarbon Processing, Jan 2011, 79. 4 www.phillips66.com/EN/newsroom/news_releases/2013 NewsReleases/Pages/01-30-2013.aspx

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5 www.phillips66.com/EN/about/our-businesses/refiningmarketing/refining/Pages/index.aspx 6 Feinstein to FTC: Investigate Spikes in California Gas Prices, www.feinstein.senate.gov/public/index.cfm/pressreleases?ID=d5f32f54-4bec-490e-a350-f68797cef1d7 7 BP Texas City Violations and Settlement Agreements. OSHA website. www.osha.gov/dep/bp/bp.html Patrick J Christensen is Project Manager, Hydrocarbon Publishing Company, with seven years’ refining experience. He holds a BS degree in chemical engineering from Drexel University. William H Graf is Technology Analyst, Hydrocarbon Publishing Company, and holds a BS degree in physics from HampdenSydney College. Thomas W Yeung is Principal and Managing Consultant, Hydrocarbon Publishing Company.He is a licensed professional engineer in New York State and holds a BS degree in chemical engineering from University of Wisconsin-Madison, a MS degree in chemical engineering from University of Connecticut-Storrs, and a MBA from New York University. Email [email protected]

LINKS More articles from: Hydrocarbon Publishing Company More articles from the following categories: Power Generation Reliability & Asset Management

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Refinery power failures: causes, costs and solutions: part 2 Technologies are discussed to help refiners formulate strategies in managing risks and crisis due to emergency shutdowns, thereby minimising financial loss William H Graf, William F Vukovich and Thomas W Yeung Hydrocarbon Publishing Company

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art 1 of this series (PTQ, Q3 2013) discussed balloon caused a short circuit in a substation at how electrical disruptions and power fail- ExxonMobil’s Torrance, California, refinery in ures at refineries regularly cause enormous the US resulting in the evacuation of workers damage in terms of lost production, excessive and elevated flaring. repair costs, and can lead to environmental and Refineries require a lot of power to operate. safety concerns, raising the questions of how The overall mitigation strategy primarily consists these outages can be prevented and how an of two parts: risk management and crisis affected refinery can be brought back online as management (see Figure 1). In handling risk quickly as possible. In this article, vital preven- management, a refinery must install the most tion techniques, protective devices, quick restart reliable equipment available in the market that equipment, and supply security methods will be can withstand disruptions caused by weather, discussed. power surges, blackouts, and any other outside Electricity is the lifeblood of the refinery oper- elements. Since no equipment is perfect, reliabilation. Optimal design and excellent construction ity engineers and operators still need to prepare mean nothing if the plant cannot receive a for worst-case scenarios as well as the most consistent and reliable power supply. Plant shut- frequently occurring possibilities. This is where downs, whether planned or unplanned, will they utilise prevention techniques to detect and decrease production and reduce profits, as fix problems before they lead to a power failure, shown by US refiner HollyFrontier, which and select protective equipment accordingly. reported a loss of $98 million for Q1 2013 When a problem does arise, the second part of because of planned and unplanned shutdowns.1 the strategy — crisis management — comes into Not only is power reliability essential for prof- play. This involves the recovery technologies that its, it is also important for national fuel supply security and environmental concerns. Refinery outage mitigations On 8 July 2013, Eni’s Taranto refinery in Italy suffered a leak of untreated fluid following a power outage. Italy’s industry Crisis Risk management management ministry declared that the refinery must invest in a power feed system to prevent further blackouts, or else the refinery would Prevention Protection Recovery Restart lose its permits.2 The necessity of flaring following electrical failure is common, as on 30 May 2013 when a simple Mylar Figure 1 Refinery outage mitigations

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allow for safe shutdown and continued operation, and the restart methods that will not lead to the same problem that caused the previous failure.

Prevention and protection One of the most important preventative measures a refinery can take is to have an efficient maintenance programme. Studies show thatthe failure rate of electrical equipment is three times higher for components that are not part of a scheduled preventative maintenance programme as compared to those that are.3 Accordingly, maintenance is often a high priority for refiners; at a National Petrochemical & Refiners Association’s (NPRA) conference in the US, a Gulf Coast refinery representative said that his company spends about 20% of the maintenance budget on proactive activities. It focuses on rotating equipment and predictive and preventative maintenance programmes such as oil analysis, vibration analysis, thermal imaging, and craft training programmes. An East Coast refinery representative added that his company spends about 15% to 20% on proactive maintenance and in the long term will have it up to 65% to 70% of the budget.4 Protective measures will keep refining equipment from being damaged or failing when exposed to hazards such as arc flashes or short circuits. This requires the proper selection of distributive equipment including transformers, switchgears, motor control centres, motors and cables that can handle extreme conditions, and are able to withstand dangerous events. This also necessitates the proper selection and use of equipment such as protective relays, circuit breakers and grounding devices in order to protect distributive equipment from dangerous conditions. Good protective technology can also protect operators and other personnel from injury. The following sections discuss the causes of and remedies to major equipment failures in a refinery, with specific refinery applications to show the latest technologies adopted. Transformers

Transformers are an essential part of power distribution. They increase or decrease voltage for downstream distribution and operation. A properly operating transformer keeps the electrical system and load at optimal utilisation voltage levels.

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Almost every malfunction is a result of the failure of the device’s insulation system. The insulation is what keeps the transformer in electrical balance and, when the insulation ceases to function, the entire transformer is susceptible to immediate failure. Faults, heat and mechanical damage will lead to insulation failure, but the electrical engineer can avoid these issues by selecting a unit capable of withstanding expected operating and fault conditions. A study done by Hartford Steam Boiler during a 20-year period showed that 13% of all transformer failures in the US were caused by inadequate maintenance. It is important for maintenance personnel to check the insulator fluid. These tests will indicate the health of the transformer. Regular testing such as an insulation resistance test, dielectric absorption test, power factor test, dissolved gas in oil test, acidity test, colour test, and insulating liquid test will allow reliability engineers to track a transformer’s degradation and determine if replacement or repair is necessary.3 The right transformer will provide the correct level of power for refinery units. In May 2013, it was announced that Siemens will be providing 220kV/110kV power transformers and 35kV/10kV distribution transformers as part of the electrical system for China National Petroleum Corporation’s planned Guangdong Petro-chemical Refinery.5 Switchgears

Switchgear is a combination of electrical enclosures, buses, protective relays, circuit breakers, fuses, controls and indicating devices that are used to distribute power to and protect other electric equipment. Receiving power from generators or transmission cables, they will distribute their power to other switchgear (or switchboards) and motor control centres. Arcing is a major threat to switchgear safety and reliability. Major arc flashes and blasts will ruin the switchgear and nearby equipment, and endanger nearby workers. An arcing event can cost a refinery as much as $15 million per incident.6 Plant engineers should select arc-resistant models that utilise quick sensing and switching to de-energise arcs. An easy maintenance programme can be set up for switchgears. A maintenance engineer should inspect insulators and conductor supports for

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signs of cracking, broken pieces and other physical damage or deterioration. Operators should examine all bolts and connecting devices for signs of deterioration, corrosion or overheating, and ensure that bolts and connecting devices are tight, according to manufacturer’s specifications.3 Switchgear is an extremely important electrical unit for refineries. Outdated units should be upgraded to protect the refinery from arc flashes and other possible failures. In July 2013, ABB installed its 11 kV Unigear ZSI switchgear with REA arc-quenching technology at the Total Lindsey Oil Refinery (LOR) in the UK. Motor control centres

A motor control centre (MCC) is used to group a number of combinations of motor controllers together with a common power bus. A MCC gives operators easy and safe control over a number of different motors throughout the facility. Motor controllers serve several key functions: starting or stopping the motor it controls, interrupting the current of the motor, and providing overcurrent protection. Since its construction is very similar to that of switchgear, MCCs can experience similar failures. This includes failure to the protective circuit breakers and fuses, loose connections in the cables and, of course, arcing. Manufacturers are employing the same arc-mitigating technology used in switchgear to protect MCCs from failing or harming personnel, so an engineer would be wise to choose units with this feature. Motors are the most important unit for refinery processing units to operate. The motor control centre is even more critical in providing protection and the right electrical levels for the motors. Eaton was rewarded a $3 million contract from Valero Energy (US) in July 2013 for its arc-preventative FlashGuard motor control centres, 285 of which were installed in new or existing units.7 Motors

As far as consumption of electric energy goes, nothing in a refinery comes close to the amount of power provided to motor-driven devices. Motor-driven equipment will typically account for 70% of energy consumption in refineries, so special attention must be paid to their proper selection and operation.8 The number of motors in any refinery will be in the thousands, and the

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safe operation of all of them is essential to smooth production. Everything from pumps, compressors, fans and other rotary devices is considered motor driven, and steps can be made to protect and improve the reliability of these essential parts of any refining process. One of the main reasons for motor failures is overheating. Overheating will degrade a motor’s insulation and necessitate de-rating of the motor. This can be a result of excessive current from faults or frequent start-ups. Technological considerations such as switching to variable-speed drives (VSDs) or soft starters, and good maintenance practices will improve reliability. Using modern motors can help increase efficiency, which then decreases operating costs. An April 2011 case study by Rockwell Automation reported a 30-41% reduction in energy consumption and decreased downtime for China’s Daqing Refinery Plant after it switched from its throttling system to Rockwell’s PowerFlex 7000 MV VSD and a 6kV inverter.9 Cables

A refinery will use miles of cable for power distribution, motor operation and process control. Its ability to transport signals and current will impact the entire refinery’s ability to operate. Protection of all the cables is vital for any part of a process. Cables will suffer from degradation to their insulation through heat and contamination. Parts of a cable that heat up from excessive current or external factors will be vulnerable to water trees and short circuits. Cables surrounded by polymer insulation are especially vulnerable to the damage caused by water trees. Cables should be inspected for sharp bends, physical damage, excessive tension, oil leaks, pits, cable movement, soft spots, cracked jackets, damaged fireproofing, poor ground connections, deterioration, and corroded or weakened cable supports. Maintenance workers should inspect for wear at entrance points and at supports, and inspect potheads for oil or compound leakage and for cracked or chipped porcelain.3 A rejuvenation technique called cable injection is one option to fix damaged polymer insulation. Novinium provided this service to the Hess Port Reading Refinery in Perth Amboy, New Jersey (US), in 2010 to rejuvenate its medium-

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voltage cable after the refinery suffered from short circuits.10 Protective relays

Relays are essential to any electrical system. They are used in all parts of the system, from the generators and substation to the transmission lines and load. Protective relays detect abnormal system conditions and direct the circuit breakers to operate in the proper manner, to correct any abnormality. A condition known as hot-switching is a common cause of relay degradation, especially in older electro-mechanical equipment. Large differences in potential across a relay will cause this to happen. The electrical engineer must be sure that the relay chosen is capable of withstanding the voltage and current levels that occur during normal operation and fault conditions. Inspection, maintenance, and testing of protective relays should be done annually by an operator to ensure proper and reliable operation. Relays should be inspected for physical damage and deterioration, gaskets and covers checked for damage and excessive wear, and repaired or replaced as necessary. Refinery maintenance personnel must also examine and clean the relay and enclosure of foreign materials, such as dust, dirt and moisture contamination.3 Upgrading old electro-mechanical relays to modern digital relays can help refineries better protect their units and monitor their electrical usage. Motor Oil Hellas Corinth Refineries S.A. (MOH) in Greece upgraded to SEL PowerMAX Power Management and Control System, a microprocessor relay system, to boost reliability after a 2005 power outage.11 Circuit breakers

Circuit breakers protect circuits and equipment from current and voltage spikes. Circuit breakers are designed to open and close by non-automatic means and to open the circuit automatically on a predetermined over-current without damaging itself. The device protects other units from overload or short circuit. Its basic function is to detect a fault condition. Unlike a fuse, circuit breakers can be reset after they have been tripped. Circuit breakers will face issues due to mechanical wear when overused, and dried-up lubrication when underused. Contaminants in the insulation,

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or the insulating medium escaping the breaker, are certain to lead to failure. Failure of a breaker will cause false trips that can harm operation and nearby workers. To maintain a circuit breaker, maintenance personnel should inspect for damage and broken or missing parts, make sure breaker contacts are clean and aligned, be sure that spring pressures are correct, check for leakage, see if the oil gauge is correct, and conduct an insulating oil test.3 Circuit breakers are the infantry of the electrical grid. Incorporating units that are robust for any condition and the correct setting for its position distribution line can save the refinery from failures. Back in 2010, Petroplus Coryton Refinery in Essex (UK) replaced LV circuit breakers with 3200A 3-pole Masterpact NW circuit breakers made by Schneider Electric, a model more suited to intense weather conditions.12 Grounding

A properly grounded (earthed) system will protect equipment and personnel from exposure to fault currents. Well-placed and -designed grounding will divert any faults to earth or a grounded bus. It is utilised throughout an electric system for equipment such as transformers and motors, and on conductive structures like storage tanks and pipes. Most electrical systems at refinery utilisation levels will use resistance grounding, where there is a resistor between the equipment and ground. This resistor, through factors such as corrosion and mechanical wear, can wear out and consequently leave a system ungrounded. Neutral grounding resistor (NGR) monitoring will immediately detect when a NGR has failed, and greatly decrease the amount of time a system is vulnerable to ground faults. I-Gard’s Sleuth high-resistance grounder has been installed during projects such as PetroCanada’s (now Suncor) 2005-2009 Refinery Conversion Project.

Recovery and restart Preventative and protective measures will make great strides towards decreasing downtime arising from power failures. But if a failure does occur, it is necessary to minimise loss in production and resume normal operation as quickly as possible. Even if the units are running at reduced rates, flaring can be reduced and production will not completely halt. The use of

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backup generators and uninterruptible power supply (UPS) can help get units back up and running, and get control rooms back online without missing a beat. Backup generators

When the power goes down, all the units have to stop. On-site generators give operators the ability to continue running units when the primary power goes down. These units are not usually used as the primary power due to fuel costs. The failure of the cooling system will lead to a rapid deterioration of the core insulation and conductors. Generator failures can be due to excessive rotor coil foreshortening, electrical grounds, mechanical imbalances and overheating. Again, the solution for these problems is an effective maintenance regimen to spot the problems before they occur. Backup generators can keep the power going when the utility fails or when maintenance requires the shutdown of the primary feed. In June 2012, Mid Refinery Company, part of Iraq’s Ministry of Oil, was provided with Cummins Power Generation’s C3300 D5 generator set to operate at 6.6kV for its refinery outside of Baghdad.13 Uninterruptible power supply

UPS is a device that acts as a backup power source. It is designed to detect power dips and power failures, and initiate a battery backup power once a problem is detected.14 A UPS should only be used in an environment that it is rated for. UPS system loads consist of digital control systems, programmable logic controllers, critical process instruments, fire and gas alarm panels, safety shutdown systems, process equipment control panels (boiler controls, compressor controls, and so on) and other critical electrical loads.15 The battery of a UPS is the weak link in the system. If the UPS is in a hot environment then battery life will be reduced. Vented lead acid batteries have an average life of 10- 15 years for plate arrangement and 15-20 years for tubular design. The Plante plate arrangement has increased battery life to 20-25 years. Nickel cadmium batteries, in vented or recombination arrangement, can have a life time of up to 25 years. Batteries should be kept below 25°C (77°F) to maintain good operation.16

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Maintenance for UPS systems can be challenging and require certified personnel. Trained workers should ensure that any areas of corrosion and deterioration are repaired as needed. They should clean and examine all electrical connections for signs of corrosion or deterioration, repair or replace as necessary, and ensure that all connections are tightened according to manufacturer’s specifications. They should also, as applicable, clean and test all breakers, disconnects and relays as prescribed elsewhere in these standards and as specified by the manufacturer, and check all system alarms and indicator lights for proper operation.3 UPS systems can not only provide backup power for control units, but can also be set to balance the electrical feed when the voltage is fluctuating. In July 2011, Emerson provided a UPS and generator package to Chevron’s (now Valero) Pembroke Oil Refinery (UK) for the sulphur recovery unit as a way to operate in the event of a grid failure and to operate emergency shutdown procedures without environmental impacts.17

Formulating strategies to mitigate power failures Every processing unit within an oil refinery was meticulously designed and planned on the assumption that it would receive a constant power supply. With that in mind, it is necessary to consider the steps that could be taken to ensure 24/7 production from every process. Risk management and crisis management must be practised to maximise productivity of the plant. Understand the impacts

Plant owners and managers must understand the lasting impacts outages will have on a company in order to appreciate the importance of mitigating refinery power failures. Figure 2 illustrates the impacts of refinery power failures. The financial implications have been stated earlier, where more downtime means less product and increased maintenance and repair expenditures. The sudden shutdown of large units presents a large array of safety and environmental concerns, where large amounts of dangerous chemicals can be released through flaring or ruptured lines; poor plant safety and environmental hazards are certain to lead to sanctions, lawsuits and, of course, bad media

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Energy efficiency

Financial performance

Plant safety and liability

tion of its report. The survey covers 120 companies from around the world that provide various technologies that are further discussed in the report. Six Sigma

Strategies for process improvement such as Six Sigma rely on identifying and removing defects within a process and carrying out proper operational practices by qualified personnel. This starts Environmental Asset concern and management with the initial design of the liability power system by the electrical engineer, where all factors such Figure 2 Impacts of refinery power failures as steady-state load requirements, ambient conditions, and quantified fault conditions are Technology suppliers surveyed thoroughly considered. Management and engineers must Technology Companies Transformers ABB, Eaton, GE, Schneider Electric, and Siemens AG also work with the vendors to be Switchgears ABB, Caterpillar, Eaton, GE, Schneider Electric, and Siemens AG certain that all the electric equipMotor control centres ABB, Eaton, GE, Schneider Electric, and Siemens AG Motors ABB, Baldor Electric Co., GE, Rockwell Automation, Siemens AG, ment installed is rated for the and Teco Westinghouse appropriate operating conditions. Cables General Cable, Nexans, and Novinium Operators and maintenance Protective relays ABB, Eaton, GE, Schneider Electric, Schweitzer Engineering Laboratories, and Siemens AG personnel must be properly Circuit breakers ABB, Eaton, GE, Schneider Electric, and Siemens AG trained and educated by the Grounding technologies i-Gard and Littlefuse Backup generators Aggreko, Caterpillar, Cummins Power Generation, GE, Kohler and vendors to know how to correctly Siemens run and check up on newly Uninterruptible power supply units Ametek Solid State Controls, Eaton, and Emerson provided equipment. Reliability engineers should have access to Table 1 operating and condition-based data to assess the state of all coverage and negative publicity. Sudden, equipment and notice any future problems. unplanned shutdowns are never good for the reliability of a refinery’s operating units, espe- Big data cially the larger ones. Motors and rotary Models should be developed not just for faults equipment are damaged when suddenly taken and degradation, but also for weather tracking in from full speed to a dead stop, and consume a case of incoming storms and lightning through great deal of energy while restarting. But if steps cloud, temperature and wind sensing. A refiner are taken to minimise unplanned failures, all of may want to borrow the idea from IBM, which these consequences can be reduced. recently announced that a combination of big data analytics and weather modelling technology Finding the most reliable electrical equipment can predict the performance of renewable Refineries need to work with electrical technol- energy.18 Since over 16% of refinery power ogy vendors to design and construct the most disruptions were caused by weather in the US reliable grid for each unit. This cooperation can from 2009-2012, refiners must ensure there are help refineries improve their energy security and adequate investments in on-site weather moniefficiency. Table 1 shows a list of selected major toring equipment, and also cooperate with local companies from those that were surveyed by weather authorities and tracking services so that Hydrocarbon Publishing Company in prepara- steps can be taken in a quick and efficient Reliability

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Power failure impacts

Negative publicity

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manner to prepare for any weather-related emergency and quickly mitigate any potential damage. Since there are many options available and refiners are often limited by tight budgets, the cost-effective strategy is first to combine electrical outage data, and process reliability models and identify the most vulnerable equipment and units. The results assist in sound decision-making on what options and investments to choose in minimising power failures. Disciplines such as predictive analytics, actuarial science and enterprise asset management should be included in overall refinery operations management. Power independence

Onsite power generation via combined heat and power (CHP) units and microgrids are worth consideration. The latest CHP and microgrid technologies can be incorporated into the design of a new refinery power grid that can be combined with other renewable energy generation units as a way to improve power supply security and reduce plant carbon footprint. This will also help refineries track the use of electricity to maximise efficiency and discover problems before they occur to keep power disruptions to a minimum, instead of depending on their utility provider. Furthermore, power grids are prone to outages because of weather, advancing age and potential cyber-attacks. Power disruptions due to poor infrastructure are common problems around the world. Get everybody on board to save bottom line

Refiners are advised to set a goal of “zero” power failure and “fastest” power recovery and share the goal with all the employees, including people working outside the plant. When a refinery shuts down, business profit is gone, thereby affecting everybody in the company, from the CEO to the maintenance worker. Any employees that offer key contribution in terms of ideas and innovations to increased reliability and availability of a power system should be offered financial incentive for avoiding power failures.

Conclusion No refinery can afford and tolerate power interruptions, as financial costs and potential liabilities due to environmental and safety incidents can run into millions of dollars a day. The

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responsibility of keeping a smooth operation not only lies with reliability engineers, operation managers and maintenance personnel, but also with senior management, who should allocate resources to invest in advanced technologies in protection, prevention and recovery now available in the market. Refiners are advised to take a holistic approach by managing risks and crisis in terms of mitigating power failures. Otherwise, stockholders, communities near the refineries and consumers are paying the price. This article is an excerpt from a multi-client strategic report called Refinery Power Outage Mitigations: Latest Technologies and Strategies to Minimize Financial Impacts, published in September 2013. Special thanks to Mr Baldwin A Yeung, P.E. of SAIC, who provided technical assistance for this article.

References 1 Zawadzki S, HollyFrontier vows less downtime at refineries, Thomson Reuters, 7 May 2013. 2 Paraskova T, Italy orders Eni to install power feed at Taranto refinery, Power Market Review, 6 Aug 2013, www.powermarket. seenews.com/news 3 Recommended maintenance practices for electrical distribution system equipment, The Hartford Steam Boiler, 2010, www.hsb.com 4 56th Annual NPRA 2002 Technology Q&A, NPRA, 2002 p8, 20, 21. 5 Siemens and China National Petroleum Corporation conclude framework agreement, 29 May 2013, Siemens Global, www.siemens.com/press/en/pressrelease/?press=/en/ pressrelease/2013/energy/oil-gas/eog201305036.htm 6 Franklin J, De-energizing arc-flash in oil & gas facilities, Oil & Gas Monitor, 6 Mar 2013, http://oilgasmonitor.com/deenergizing-arc-flash-oil-gas-facilities/4406/ 7 Eaton’s press release on Jul 16 2013, Eaton to Enhance Safety, Equipment Reliability for Valero Energy Corporation’s St. Charles Petroleum Refinery. 8 Electrical installations in petroleum processing plants, American Petroleum Institute, Jul 2004, p12. 9 Rockwell automation’s medium voltage drive solution helps China’s Daqing refinery plant reduce annual energy consumption by 41%, Apr 2011, www.emea.rockwellautomation.com/ oilandgas/en/docs/mv.pdf 10 Case study: Hess Port Reading Refinery, Perth Amboy, NJ, 2010. 11 Case study: automated power management system — an economical approach to greater operational dependability. 12 Petroplus refines its technology with retrofit from Schneider Electric, Schneider Electric, Mar 2011. 13 Cummins Power Blog press release on 6 Jun 2012, MICTA

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supplies and installs Cummins Power Generation Prime Power Solution at third site for Mid Refinery Company in Iraq. 14 Stout M, Effects of extreme temperatures. electrical construction and maintenance, 2012. 15 Cosse R Jr, Dunn D, Spiewak R, Is my UPS distribution system coordinated?, IEEE, 2004. 16 Eaton’s Power Xpert FMX Medium-Voltage Switchgear System optimized with SASensor for tomorrow’s Smart Grid, Eaton, 25 Jan 2012, www.eaton.com/Eaton/OurCompany/NewEvents/ NewsReleases/PCT_333811 17 Emerson Network Power’s Chloride Integrated Power solution keeps Pembroke Petroleum Pumping, 13 Jul 2011, Emerson News Release, www.emerson networkpowercomen-EMEA/About/NewsRoomNewsReleases/ PagesEmersonNetworkPower’sChlorideIntegratedPowerSolution KeepsPembrokePetroleumPumpingNewfacilityatChevron’s Pembroke refinerygets.aspx 18 IBM’s press release on 12 Aug 2013, Made in IBM Labs: IBM drives the future of renewable energy with new wind and solar forecasting system.

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William H Graf is Technology Analyst with Hydrocarbon Publishing Company and holds a BS degree in physics from HampdenSydney College. William F Vukovich is Technology Analyst with Hydrocarbon Publishing Company and holds a BS degree in chemical engineering from Lehigh University. Thomas W Yeung is Principal and Managing Consultant with Hydrocarbon Publishing Company. He is a licensed professional engineer (New York State) and holds a BS degree in chemical engineering from University of Wisconsin-Madison, a MS degree in chemical engineering from University of Connecticut-Storrs, and a MBA from New York University. Email: [email protected]

LINKS More articles from: Hydrocarbon Publishing Company More articles from the following categories: Power Generation Reliability & Asset Management

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