Part of the AXI International mission is to educate the public and industry professionals on not only the science behind diesel fuel, but the standards necessary to ensure optimal fuel quality. Below is a list of white papers that further deliver the message of fuel cleanliness standards and the impact AXI International has on hydrocarbon fuels.
A number of factors are driving the need for very clean fuel. The major factors are:
- Very difficult exhaust emission standards
- A growing shortage of service technicians to repair increasing complex and sophisticated equipment
- The cost of failures caused by dirty fuel. These failures result in downtime and loss of machine productivity.
What Is Clean Fuel?
The question of what is clean fuel has been the subject of debate for many years. Until recently, the definition of clean fuel was “Clear and bright”.
What does that mean?
How clear? How bright?
There is only one acceptable and meaningful way to measure and discuss fuel cleanliness. That is ISO cleanliness level.
What do we mean today when we say “Clean fuel”?
Bulk fuels are simply not delivered to sites at these cleanliness levels. Further confusion is introduced when sites attempt to determine fuel cleanliness by bottle
sampling. The only reliable way to sample fuel is in dynamic flow with a laser particle counter. Contaminated fuels and the associated cost of failures is something which can be controlled or eliminated
by the effective use of bulk filtration.
Follow this link to read entire white paper: Cat Bulk Filtration Paper
Report on Corrosion in Systems Storing and Dispensing Ultra Low Sulfur Diesel (ULSD), Hypotheses Investigation
September 5, 2012
Prepared by Battelle Memorial Institute, Columbus, OH
Clean Diesel Fuel Alliance
Mr. Prentiss Searles
American Petroleum Institute
1220 L. Street, NW
Washington, DC 20005-4070
Corrosion in Systems Storing and Dispensing Ultra Low Sulfur Diesel (ULSD), Hypotheses Investigation
Severe and rapid corrosion has been observed in systems storing and dispensing ultra low sulfur diesel (ULSD) since 2007. In addition, the corrosion is coating the majority of metallic equipment in both the wetted and unwetted portions of ULSD underground storage tanks (USTs). To investigate the problem in an objective manner, multiple stakeholders in the diesel industry, through the Clean Diesel Fuel Alliance, funded this research project. The design included the identification of retail fueling sites and the development of an inspection and sampling protocol to ensure uniform and thorough inspections of USTs. Fuel, water bottoms, vapor, bottom sediments, and scrape samples were taken from six sites: one that was not supposed to have symptoms (but did to a much lesser degree) and five that were to have the severe corrosion. Then, samples from the inspections were analyzed for genetic material and chemical characteristics. These data, in combination with information on additives, have allowed Battelle to draw conclusions with respect to three working hypotheses.
Specifically, the hypotheses are:
1) Aerobic and anaerobic microbes are producing by-products that are establishing a corrosive environment in ULSD systems;
2) Aggressive chemical specie(s) (e.g., acetic acid) present in ULSD systems is(are) facilitating aggressive corrosion; and
3) Additives in the fuel are contributing to the corrosive environment in ULSD systems.
All of the sites inspected contained microbes, although at different abundances. The dominant organism identified from three of the sites, Acetobacter, has characteristics pertinent to the corrosion observed in all of the sites, such as acetic acid production, ethanol utilization, low pH requirements, and oxygen. Although geographically on opposite sides of the country, from different fuel suppliers, and of relatively new construction materials, the presence of the organisms was relatively uniform. The traditionally expected hydrocarbon degrading organisms were found in insignificant abundances. This indicates that the inspected ULSD USTs are selective environments for these specialized, acetic acid producing organisms. Of note from the chemical analyses is that acetic acid was found to be ubiquitous (water bottoms, fuel, vapor, and scrapings) in all of the sites inspected. In addition, ethanol was unexpectedly identified and measured at five of the six sites. Components necessary for the organisms identified to proliferate were analytically determined to be present in the majority of the samples: trace amounts of ethanol, low pH, oxygen, and water were present in the diesel USTs inspected.
Finally, although additives could play a role in the corrosive environment, it is unlikely that they are the primary cause of the observed corrosion.
This project was designed to objectively investigate multiple hypotheses as to why ULSD USTs have been experiencing severe and rapid corrosion. The in-depth site inspections were performed on a limited number of sites and therefore may not be representative all of systems experiencing this phenomenon. Although it cannot be stated with statistical significance, ingredients necessary for the observed and chemically determined corrosion in this environment were present at the inspected sites. The most obvious issues causing this problem were the focus of this research and the development of corrosion at different sites could also be influenced by other factors (environmental, geographical, seasonal, etc.) not discussed in this report. The project final hypothesis for this investigation is that corrosion in systems storing and dispensing ULSD is likely due to the dispersal of acetic acid throughout USTs. It is likely produced by Acetobacter bacteria feeding on low levels of ethanol contamination. Dispersed into the humid vapor space by the higher vapor pressure (0.5 psi compared to 0.1 psi for ULSD) and by disturbances during fuel deliveries, acetic acid is deposited throughout the system. This results in a cycle of wetting and drying of the equipment concentrating the acetic acid on the metallic equipment and corroding it quite severely and rapidly.
The subject of this review is diesel fuel – its performance, properties, refining, and testing. A chapter in the review discusses diesel engines, especially the heavy-duty diesel engines ised in trucks and buses, because the engine and the fuel work together as a system. In addition, because environmental regulations are so important to the industry, the review examines their impact on both fuel and engine.
When the Lights Go Out…
it’s Too Late to Clean Your Tanks
Most Emergency Power and Engine Performance failures start in the Fuel Tank and are caused by the inherent instability of fuel.
Fuel degradation is a natural process that causes the formation of sediment, tank sludge and acid. It starts at the refinery and continues until the fuel has been used. Heat, pressure, temperature changes, water and microbial contamination accelerate the fuel breakdown process.
The mandated use of biofuels has caused a dramatic increase in fuel re-polymerization. This is causing rampant filter plugging, fuel injection system failures and a significant reduction of stored fuel shelf life.
Advancements in engine and injection system design demand perfect fuel. However, changes in fuel production methods combined with the use of biofuels are seriously endangering engine performance and the reliability of critical power. Traditionally, the solution has been to periodically replace stored fuel and clean tanks. This is a very expensive and only a partial solution at best.
AXI provides equipment based on its unique and innovative approach to fuel quality optimization, maintenance and tank cleaning to improve the stability, filtration and combustion of fuel.
Implementing AXI’s Green Clean Certified® equipment and fuel maintenance programs will eliminate the need for periodically cleaning tanks and replacing fuel. Optimizing and maintaining fuel quality preserves its integrity. It extends filter change intervals, protects engines and injection systems and reduces harmful emissions.
AXI Fuel Quality Optimization, Maintenance & Tank Cleaning provide Reliability and Protection of Engines & Turbines far beyond traditional filtration & separation.
An analysis of data center failures shows that focusing reliability efforts on generators is the best way to improve uptime.
Data Center Knowledge Magazine, 7×24: Generators Are Key to Improving Reliability By Rich Miller, November 15, 2011
When it comes to reliability, diesel generators are far and away the most important pieces of equipment in a data center, and regulatory mandates on fuel may be creating new problems that could raise generator failure rates.
Those were the key points made by Steve Fairfax, President of MTechnology, in a provocative keynote presentation Tuesday at the 7×24 Exchange Fall Conference in Phoenix. Fairfax, whose firm does “science risk” consulting work for both vendors and end users, said in-depth analyses of failure rates in data center components and systems yields counter-intuitive results, especially when it comes to maintenance.
“Generators are the most critical systems in the data center,”
said Fairfax, whose studies of failure data found generators played a role in between 45 and 65 percent of outages in data centers with an N+1 configuration (with one spare backup generator).
“Reducing generator failures has more than 10 times the impact of reducing other component rates. This is where you should be focusing your attention – on generators. That’s what will take you down.”
Fairfax identified three key threats to generator reliability:
- fuel quality problems due to old fuel mixing with newer fuel
- quality issues with new Ultra-Low Sulfur Diesel and biodiesel fuels
- wear and tear from efforts to start cold generators as quickly as possible
Fuel Tanks and the “Diesel Solera”
Fairfax said the leading problem with generators is not the failure to start, but the failure to run properly once the generator has started. A key factor in the “failure to run” scenario is fuel quality.
Fairfax highlighted a phenomenon he calls the diesel “solera,” a term for the process for aging wine by mixing small amounts of older vintages with newer wine. While the solera process can help improve wine, it can introduce reliability challenges when it occurs in a tank of diesel fuel – which happens when older fuel remains in the bottom of a tank when it is refilled.
“Every year we take some of the diesel fuel out and add fresh fuel,” said Fairfax. “When was the last time you emptied that tank and cleaned it out?”
Ultra-Low Sulfur Diesel and BioDiesel
Another factor is the regulatory requirement to use Ultra Low-Sulfur Diesel Fuel (ULSD). While ULSD improves the emissions profile of generators, Fairfax said data center operators should pay close attention to fuel quality and tank conditions. Ultra-Low Sulfur Diesel is less stable than older distillate diesel fuels, he said, with a maximum storage time of 6 months. “Stabilizers can extend that, but then you have an interesting chemistry experiment going on in your diesel tank,” said Fairfax, who says this could result in a higher incidence of leaks and accelerated wear on seals.
Fairfax offered three recommendations on managing this challenge:
- Empty and inspect fuel tanks whenever possible.
- Change your generator testing policies. “Test them as you will run them,” said Fairfax, who said tests should run for 24 to 72 hours to simulate an extended utility outage, which will draw down diesel supplies in ways not seen in shorter periods.
- Sample your diesel fuel on a regular basis to track fuel quality.
Biodiesel, which is mandated in several states (including Massachusetts, Washington and New Jersey), poses additional challenges. “Biodiesel has a completely different chemistry” than older diesel fuels, said Fairfax, who said biodiesel can dissolves sediments that could clog filters, and has even worse stability than ULSD.
10-Second Start Times
Fairfax noted the NFPA guide to Emergency Power Supply Systems calls for generators to be able to start in 10 seconds for life safety applications. While not all data centers are required to adhere to this, many follow the NFPA guidelines by default. Farfax said Mtechnology’s research found no basis for the 10-second guidance, which he said places high stress on the generators that can shorten lifespan and impact reliability. The 10-second target requires cold equipment to start with a wide-open throttle, creating the highest possible thermal and mechanical stress.
“You get a huge benefit by reducing stresses. One of the best things you could do to improve the reliability of generators is to increase the start time to 30 seconds.”
Unfortunately, a general consensus about diesel fuel being “good for life” is a common idea, but this belief is a myth. Many have found this out the hard way, especially in electric power generation. In order to avoid untimely shutdowns, it is imperative that a systematic approach be in place to avoid contaminated fuel.
With today’s fuel injection systems operating at such high pressures, utilizing extremely fine tolerances, the days of poor contamination control are over. Today’s injectors are extremely vulnerable, subject to wear and premature failure as diesel fuel ages and is not maintained properly.
Poor fuel maintenance can also lead to clogging and blockage of fuel filters. This can slow or even stop the flow of fuel, leading to engine starvation, injector damage, poor performance, and ultimately engine shutdown.
Unlike on-highway trucks and off-road machinery that consume fuel relatively quickly, diesel gensets store large amounts of fuel for extended periods. Stored diesel fuel can present symptoms of fuel degradation in as little as six months. In some applications, the genset will see very little use, allowing the fuel to age. This increases the formation of sediments and bacteria in the fuel. In these cases especially, it is critical that this energy source be maintained.
A few things to consider when maintaining the integrity of your diesel fuel supply:
- Have fuel samples been taken from three locations (bottom, middle, top) of tank, and evaluated to properly identify fuel quality?
- Have bacterial and fungal growth inhibitors been added to help combat the effects of fuel being stored for extended periods?
- Does the fuel supply have its own filtration? Does it have the ability to filter down to 0.5 microns under pressure, as well as a fuel/ water separator to aid in the effort to ensure clean fuel delivery?
- Has there been a thorough inspection of the fuel tank, including interior video inspection, complete equipment inspection (connections, gauges, monitoring devices) as well as identifying non-compliance issues?
- Are proper contamination control precautions being taken when replenishing fuel supply? It is important to ensure that the fuel that is received is from a reputable source, who also takes the proper precautions to ensure quality fuel delivery.
Utilizing these maintenance measures will contribute to the longevity and performance of your investment. A failure due to neglect should not be an option, and is easy to avoid if the proper procedures are put into place.
SINGAPORE (Reuters) – Indonesia’s inability to meet the rising energy needs of its businesses, from steelmakers to hotel resorts, threatens to put the brakes on growth in Southeast Asia’s largest economy.
The recent update of Indonesia’s sovereign debt rating by Fitch to investment status should help attract more investors. But analysts and industry watchers fear wasteful subsidies and rampant corruption will reduce crucial investment in the infrastructure needed to supply power.
“Indonesia is not fulfilling its full potential because of these energy and infrastructure problems,” said Erman Rohman, director of economic programs in Indonesia at The Asia Foundation, a San Francisco-headquartered nongovernmental organization.
“A business can’t grow when it is facing blackouts a few times a week,” he said.
Almost half of 13,000 companies surveyed by the foundation in 2010 and 2011 experienced power outages at least three times a week.
Indonesia is the world’s largest exporter of coal and the third-largest exporter of liquefied natural gas (LNG), but almost one-third of its citizens have no access to electricity. In outlying regions such as Papua, the figure rises to more than half.
A World Bank report for 2011 ranks Indonesia 161st among 183 countries in the ease of businesses getting reliable electricity supply, down three places from the previous year. In this category, Indonesia has received worse grades than Congo and Albania.
Recurring blackouts this year have forced hotels on the resort island of Bali to rely on diesel generators for back-up power, which costs more than regular power supplies.
“The situation has improved, but there are still blackouts from time to time. We have to use diesel which is more expensive and adds to our costs,” said a senior executive at a Bali hotel.
Due to poor transport links in the archipelago of more than 17,000 islands, movement of coal is hampered by lace of railroads. A lack of pipelines is on reason why only a small percentage of Indonesia’s rich natural gas deposits are being utilized to power industries at home.
“Indonesia needs to improve access to energy for the smaller islands to diversify the sources of growth now concentrated in greater Jakarta and Java,” said Ferry Wong, head of research at Citigroup Securities Indonesia.
Indonesia’s GDP is expected to grow by 6.3 percent next year, according to the country’s central bank, while electricity demand is forecast to rise a robust 6.2 percent, the Economist Intelligence Unit (EIU) estimates.
Heavy spending on subsidies and problems with land acquisition have held back investment in infrastructure.
Analysts say that with Indonesia growing at more than 6 percent a year, it needs to spend the equivalent of 5 percent of its gross domestic product a year to keep up with growing infrastructure needs.
While a newly-passed land acquisition law makes it easier for developers to secure land to build ports and power stations, there is political and public opposition to tackling subsidies.
The country’s utilities sell power to end-users at subsidized rates of $70-$75 a barrel of crude oil, well below market prices of $95-$105 a barrel, said Citigroup’s Wong.
“If oil prices continue to rise, this will be a risk to Indonesia’s economy because it puts a strain on the budget.”
Finance Minister Agus Martowardojo said on December 13 that this year’s fuel subsidy bill will total 168 trillion rupiah ($18.5 billion), up from the budgeted figure of 129.7 trillion rupiah because of increased demand and higher-than-expected average oil prices.
The government plans to remove fuel subsidies in April for private cars in Jakarta and Bali, but the selective nature of the cuts is likely to limit their effectiveness.
“Motorcycles are exempt from the subsidy (cut), and there are roughly 10 times more motorcycles than cars being sold in Indonesia,” said Martin Adams, an EIU energy analyst in Hong Kong.
State utility PLN cannot cover costs at current tariffs, which the government has been reluctant to raise, capping the power firm’s ability to fund investment, analysts said.
There are plans to raise electricity tariffs in 2012 by an average 10 percent on average for most customers, which would cut an estimated $1.1 billion from the state subsidy bill. But there is no certainty rates will be raised. Early this year, the government proposed a 15 percent hike, but the legislature thwarted the plan.
Underinvestment at the lower levels of government is also a problem, with only 14 percent of local government budgets allocated to infrastructure, compared with 60 percent for personnel, a study by the Asia Foundation shows.
“For road and bridge programs, the average funding allocated was only… around a quarter of the amount needed for periodic maintenance alone,” said the report, “Local Economic Governance 2011”, based on a survey of almost 13,000 businesses conducted for the foundation by Nielsen Indonesia.
Corruption is also a problem, and one that has been exacerbated by Indonesia’s decentralization after longtime strongman Suharto resigned in 1998. Unlike during his tenure, officials in local governments far from Jakarta have the power to permit or block projects, and some provincial civil servants have grabbed the chance to enrich themselves.
“The situation is worse than I had thought, people are paying up to $10,000 to $15,000 just to get these jobs, although their annual pay is just 10 percent of that,” said Rahman.
Bribery also puts off foreign investors at a time when Indonesia is seeking $100 billion of private investment to overhaul its creaking transport network.
DECLINING GAS OUTPUT
In recent years, Indonesia has shifted away from using oil towards gas to generate power as rising crude oil prices boosted subsidy bills and the country became a net oil importer in 2004.
PLN plans to cut oil’s share of the energy mix to 3 percent by 2013, from about 20 percent now. Analysts estimate that producing power from oil-based fuels costs it $15 per million British thermal units (mmbtu), but gas-fired power plants would only cost $12 per mmbtu.
But the lack of gas supply has prevented companies from taking advantage of the lower-cist fuel source, since producers earn more from higher-priced exports.
Gas shortages forced Krakatau Steel, Indonesia’s largest steelmaker, to shelve plans to expand production capacity, President Director Fatwa Bujang said this month.
In response to the shortage, the government is July freed private firms to import natural gas for the first time.
Indonesia will export 362 LNG cargoes this year, down 15 percent from 2010. It is building LNG import terminals with nearly 10 millions tons of capacity to meet demand.
The PLN, where Nur Pamudji was appointed as director last month, wants to boost the national electrification ration to more than 73 percent next year, from below 69 percent now.
To reduce blackouts, the utility plans to add 10,000 megawatts (MW) of generation capacity by 2014 to the existing 30,000 MW.
But even if realized, Indonesia’s energy woes could still cap its economic growth in the short term.
“The government realizes that it needs to remove subsidies, improve the business environment, install more generation capacity and extend the grid, but these are all long term undertakings and we can expect only gradual movement,” said EIU’s Adams.
(Additional reporting by Reza Thaher; Editing by Clarence Fernandez and Simon Webb)
©Thomson Reuters 2011 All rights reserved.
The treatment of carbon based fuels with AFC-705 has a significant effect on trace sulfur combustion chemistry. In diesel engines, gasoline engines and open flame applications (boilers) the use of AFC-705 treated fuel will significantly reduce sulfur oxide (SOx) emissions, and related sulfur acid corrosion problems.
AFC-705 does not react with the sulfur in the fuel nor does AFC-705 have any effect on the sulfur content of the fuel. AFC-705 does not effect fuel specifications at recommended treatment levels. Fuel containing one percent sulfur prior to AFC-705 treatment will still contain one percent sulfur after AFC-705 treatment. However, the use of AFC-705 will determine where the sulfur ends up and what its chemical state will be after combustion.
The combustion of sulfur in fuels invariably leads to the formation of sulfur dioxide S + O2 ® SO2 (1) and sometimes sulfur trioxide 2SO2 + O2 ® 2SO3 (2). Sulfur trioxide formation is catalyzed by vanadium pentoxide (V5+). This is the most stable oxidation product of vanadium, when vanadium containing fuels are burned in air 4V + 5O2 ® 2V2O5 (3). The catalytic effect is thought to relate to the reversible dissociation 2V2O5 ® 2V2O4 + O2 (4) at temperatures between 700O-1125O C. The sulfur trioxide reacts with water vapor to form sulfuric acid SO3 + H2O ® H2SO4 (5) which is primarily responsible for acid corrosion problems in combustion equipment.
AFC-705 affects the production of gaseous SOX emissions. It enhances the formation of CO2 during the combustion phase thus limiting the amount of SOX produced during the exhaust phase. The increased production of CO2 reduces the amount of excess O2 available for other reactions. The difference in the amount of CO2 produced during the combustion and the exhaust phases correlates to a temperature differential. This temperature differential results in lower exhaust temperatures and shorter heat transfer times.
Minerals contained in fuel are generally oxidized to metal oxides during the combustion process. When vanadium is oxidized to V5+the production of sulfur trioxide increases due to reversible dissociation, and sulfuric acid is ultimately formed. The use of AFC-705 inhibits the formation and reversible dissociation of V5+ during the exhaust phase by limiting the available O2, high temperatures, and time periods needed for these reactions to occur.
This greatly reduces the catalytic effect V5+ has on the formation of Sulfur trioxide and thus the formation of sulfuric acid. By reducing the catalytic effect of vanadium, AFC-705 promotes the combination of SOX compounds with other minerals in the fuel such as Na and Ni. This leads to the formation of stable mineral salts and mixed mineral sulfates found in the clinker or fly ash.
In this manner, AFC-705 decreases the gaseous sulfur emissions by increasing the particulate portion of the combustion residue products. AFC-705 treated fuels will therefore show slightly higher sulfate content in the ash than untreated fuel.
What do all of these true stories have in common? Poor fuel quality. In all of these cases, poor fuel quality shut down emergency standby power generators exactly when they were being counted on in the middle of a disaster. And the number of hurricanes, wildfires, blackouts, floods, earthquakes and the like in recent years has added significantly to the lore, though most are closely guarded stories and a PR person’s nightmare.
The frightful truth is that many emergency generators—an organization’s last line of defense in a catastrophe— will not perform as expected if and when that time comes. This article will share some insights into the issue to hopefully raise the percentage of emergency backup power systems that will operate as planned when needed.
At its essence, poor fuel quality is about what ends up in fuel that doesn’t burn well, and the complete story will surprise even veteran operations managers. Diesel fuel contaminants should be grouped into the following categories: Water; Microbial Growths; Inorganic Particulate Matter; and naturally forming Fuel Breakdown By- Products. The origins of them all can be traced to either a site-specific problem or in a fuel delivery from upstream in the supply chain.
Water is a widely acknowledged concern, but it need not be a problem as long as some manner of routine fuel maintenance is performed. If a tank is well-designed and is in good condition, with no means of water leaking in at the site, then only small amounts of water should be present. Water appears quite normally in most tanks through condensation.
This water can be removed easily through the use of a wide range of solutions that include absorptive eliminators and filters, coalescers, centrifuges and the like. All mobile tank cleaning systems used by tank cleaning services and permanently installed conditioning and filtration systems utilize one or more of these approaches and are effective at removal of normal levels of water content. A quality multi-spectrum additive often includes an emulsifier which can also pass small quantities through the system.
Microbial contamination (bacterial and fungal growth) is the most frequently mistaken problem. It only exists where there is water for it to grow in, so if you are diligent in carrying out a fuel maintenance program, you should never see the problem. Where it does exist in a long-ignored tank, microbes feed on the fuel, multiply and excrete waste products, all of which will end up clotting in your filters. These by-products are highly corrosive and pose a threat to many tanks.
The problem is that clogged filters are widely misinterpreted as containing microbial products, when they actually most often are deteriorated fuel by-products (sludge). This leads to endless streams of toxic biocides being needlessly dumped into tanks, which, when mistakenly used, make the problem worse. Often the result is diesel fuel now so spoiled that it needs to be disposed of and replaced, a costly and unnecessary consequence with serious environmental impacts. Not to mention that it may have sidelined the generator for several days. Again, take care of the water, and you’ll never need a biocide.
Inorganic Particulate Matter
Other particulate pollutants in diesel fuel are mostly dirt, rust and other metallic particles that find their way into the fuel either during the many tank transfers that occur in the supply chain or from a corroding tank somewhere along the line. It is infrequent that the level of particulate matter is very high and is generally welltreated through conventional filtration that accompanies a standard tank cleaning system or onboard permanent tank-side solutions.
|Fuel Breakdown By-Products
(most tank sludge)
||Process reversal through magnetic restorative conditioning in some:
Fuel Breakdown By-Products
Least understood is the natural process whereby organic fuels break down. Diesel and other fuels are naturally unstable, and actually less stable today due to modern refining techniques (catalytic cracking) that are designed to produce more fuel per barrel. Most major oil companies have documented on their Web sites that 6 to 12 months is the useful shelf life for their products, but the deterioration process starts as soon as the products leave the refinery.
This fuel breakdown is a process where agglomerating hydrocarbon chains bond together to create larger clusters. These larger compounds, present even in what visibly appears as clear and bright fuel, do not burn as efficiently. This incomplete combustion robs fuel economy, leaves carbon deposits on injectors and raises emissions, often with visible smoke and soot.
As the process continues, with even larger compounds being formed, the fuel begins to appear “dirty.” Eventually it progresses to forming sludge that falls to the bottom of the tank. This clotting fuel is the material that is commonly clogging fuel filters and shutting down generators. Often it may happen when a tank gets low and new fuel is poured in, agitating the sludge and dispersing throughout the fuel, releasing the threat that had been lying dormant. Or maybe the new fuel delivery came from such an agitated tank upstream in the supply line.
There are solutions. Some multi-spectrum additives on the market do have agents that can dissolve some of the sludge and others that will retard further deterioration for some number of months. Magnetic fuel conditioning runs the fuel across a magnetic field and its inductive properties reverse the process, separating carbon chains in what effectively returns deteriorated products back to fuel again.
The Bottom of the Barrel
Water and tank sludge, of course, drop to the bottom of the tank, and a too-often overlooked but critical concern is that any tank cleaning be done properly by getting to the bottom of the tank. Access is frequently a limiting factor, but an inspection port can be installed to alleviate this problem. Similarly, when installing a recirculating conditioning and filtration system, the pickup tube into the tank is optimized when near the bottom (not using the fuel system’s draw, which is several inches higher to avoid the very substances you wish to collect).
Take the Test
Any generator that is in a critical application ought to be a candidate for a routine fuel testing service, probably on a quarterly basis. All the talk about fuel quality means little if you don’t have a benchmark to measure from. Be sure to get your samples from both a midpoint and the bottom of the tank.
Put Fuel Maintenance into the Vocabulary
Too often, fuel condition is overlooked, mostly out of ignorance of the issue. When that happens, the extreme of fuel removal, replacement, and possibly extensive tank cleaning or even tank replacement, is the cost. That is, if you’re lucky and didn’t have a generator failure in a real emergency situation. Only the business in question can determine the cost in the case of a total failure. But, generally, they wouldn’t have a generator if total power loss was an acceptable outcome.
It is crucial that disaster-planning professionals become aware of the need for a fuel maintenance routine to assure the survival of critical systems in the event of an emergency. PEI members are perfectly positioned to advance this educational effort. It can also represent a value-add service, as well as potential source of revenue and profits. Perhaps most important, you will be participating in raising overall organizational survivability and reducing the human suffering and loss of life in the midst of the worst of catastrophes.
By: Hector Partidas
One of the most difficult and profit hurting problems found in the oil field is the build-up of deposits in the well bore, production string, flow lines and even in storage tanks. These deposits act as a restriction during build-up in the wellbore causing a gradual decrease in production and, in many cases, as a solid barrier for wellbore fluid flow. Unless remedial action is taken, this blockage may cause rod failures, tubing leakage and damaged pump parts plus lost production.
Over the years such remedial actions cost the Oil Industry Millions of dollars. Unfortunately, conventional treatment methods, either mechanical or chemical, are mostly focused in fighting the effects yet not the causes.
A third method based in an applied magnetic field is being used for effective removal and inhibition of both organic and inorganic deposits. By flowing well fluids through a strong magnetic field inside a housing the deposition pattern is altered without affecting the crude oil characteristics.
In this paper the deposition mechanism of both inorganic and organic deposits is reviewed and the use of the Magnetic Fluid Conditioner manufactured by Mag-Well, Inc, a Dallas based company is discussed.
Deposits are either organic or inorganic. Inorganic deposits are mainly compounds such as Calcium Sulfate, Calcium Carbonate and Barium Sulfate being usually referred to as mineral scale or simply scale. Organic deposits, on the other hand can be either in the form of paraffin or asphaltene compounds.
Deposition of Inorganic Deposits (Scale)
Deposition of scale from brine or connate water produced with oil is a common problem in many producing, injection and waste disposal wells.
Scaling takes place when the equilibrium of the brine is altered by changes in the state of the well fluids or by mixing incompatible waters caused by the drilling and production activities.
Before these activities take place, well fluids in the reservoir remain in a state of equilibrium. As the well is drilled and production starts, the pressure drop causes dissolved gases to come out of crude oil and destroys this equilibrium. This change causes deposits to form. Water from different zones may become mixed in the wellbore or injection water may mix with formation water. Incompatibility may result when one water contains a high concentration of calcium or barium and the other contains a high concentration of sulfate or carbonate ions in crude oil. As these waters mix, the resulting crude oil becomes saturated with calcium sulfate, barium sulfate or calcium carbonate and deposition occurs.
The deposition mechanism is mainly responsible for the physical properties of scale. A rapid deposition pattern will yield soft scales while a slower deposition pattern will form a hard and dense scale making it harder to remove. As a whole, physical form of scale can be grouped into three categories: thin, laminated and crystalline. Thin scale is the most permeable and easy to remove while laminated and crystalline scale are less permeable hence harder to remove.
Factors affecting deposition
Factors such as pressure drops, temperature changes, supersaturation, contact time, pH and the mixing or water can result in severe scaling problems. Formation of scale, however, is not normally caused by the action of a single factor nor the cause is common to the different types of scale. As changes in the equilibrium take place, interaction of these changes with other down-hole conditions play an important role on the deposition mechanism which will affect the final form of scale. This, in turn, has a significant effect on the method chosen to remove the scale.
Deposition of Organic Deposits (Paraffin and Asphaltene)
The chemistry of petroleum is a part of organic chemistry, which deals essentially with carbon compounds. About half a million different compounds of carbon have been found being the simplest those that contain only carbon and hydrogen, known as hydrocarbons.
Hydrocarbons have been divided into various series, differing in chemical properties. The four that comprise most of the petroleum’s are: the normal paraffin (alkanes), the isoparaffin (branched-chain paraffins), the naphthene (cycloparaffin) and the aromatic (benzene) series. Crude oils are referred to according to their relative richness in hydrocarbons of these groups, as paraffinic-base, naphthenic-base or mixed-base (naphthenic-paraffinic) oils.
They are saturated, straight-chain (aliphatic) compounds. By large, they are the most abundant hydrocarbons present in both gaseous and liquid petroleums.
All the members below pentane are gaseous at ordinary temperatures while those between pentane and pentadecane are liquid. The higher members are waxy solids.
Naphthene (Cycloparaffin) Series
These are saturated, closed-ring compounds having the general composition. Naphthenes resemble the paraffins in both physical and chemical characteristics but are more stable. Cyclopropane and methylcyclopropane are gases at ordinary temperatures and pressures. All the other members of the monocyclic naphthene series are liquid the most abundant being cyclopentane and cyclohexane (061112). Crude oils with high percentage of naphthenic members are also called “asphalt-base crudes” for the many complex asphaltic members from the higher boiling point ranges.
Paraffin Deposition Mechanism
Even a slight change in the equilibrium conditions results in the deposition of an amorphous and microcrystalline waxy material known as paraffin. Consistency of the deposit will vary from soft to hard and brittle. The higher the molecular weight of the materials forming the deposit, the harder and difficult becomes to remove it.
Paraffin is normally deposited in the wellbore extending up the production string and even in flow lines and storage tanks as a result of the cooling of the oil rising to the surface and flowing to the flow station. Paraffin wax may also precipitate and clog the pores at the face of the reservoir when the expanding gas cools as it enters the wellbore.
Loss in solubility as a result from changing the crude oil equilibrium conditions is the trigger for paraffin deposition. Temperature and pressure changes, evaporation and loss of dissolved gases are the main causes for altering the crude oil equilibrium.
Paraffins having the highest molecular weight and melting point are the first to separate from crude oil, that is, are less soluble. This mean that the solubility of paraffin waxes in a specific crude oil at a given temperature decreases with an increase in molecular weight and melting point.
Factors Affecting Paraffin Deposition
As stated above, loss in solubility of paraffin in the crude oil is the trigger, for deposition. One of the main causes for this loss in solubility is the temperature changes in the liquid.
Most of the temperature changes in the crude oil are the result of the cooling action produced by:
- heat radiation to the surroundings at it flows from bottom to surface
- gas lifting
- liberation dissolved gases
- vaporization of lighter petroleum fractions
- water injection
- Formation Orifice Effect (FOE)
No matter what the operator does to the oil, if the temperature of the crude oil reaches its Cloud Point, the paraffin will start precipitating. If the temperature continues to go down the small wax crystals begin an interlocking action until the crude oil will stop flowing. This temperature is known as the Pour Point. In summary, the higher the Cloud and Pour points are, the less able the crude oil is to keep the paraffin soluble.
Pressure has a direct effect on the solubility of the crude oil. It will keep the gas and the higher petroleum fractions in crude oil. However, to produce the well, it is necessary to have a pressure drop or drawdown. The higher the drawdown, the larger the cooling of the crude oil which normally takes place right at the formation face. Here, the tiny fluid passages in the formation act as orifices originating expansion of the gas followed by vaporization of the lighter components as the oil leaves the formation and enters the wellbore. This will cause the crude oil to cool down hence the solubility of the paraffin in the crude oil is lowered too. Another important effect of the loss of lighter components that is seen in old fields. As the field becomes older, the lighter components are constantly being removed from the crude oil even within the formation.
This action saturates the oil with paraffin even before it leaves the formation since the paraffin is more soluble in the lighter components of the crude oil than in the heavier ones. This is why, paraffin deposition is more severe the older the field becomes.
Formation fines such as sand and silt often act as a nucleus for the cohesion of the small wax particles suspended in the oil into larger particles. This will make the particles larger which will tend to separate more easily from the oil.
Asphaltene Deposition Mechanism
Asphaltenes are colloidal solutions, highly dispersed and stable. Asphaltene deposits are usually very hard and brittle hence making its removal more difficult. They are insoluble in petroleum naphthas but soluble in polar solvents like piridine, nitrobenzene, benzol, etc. Instead of melting when heated, they swell and decompose into coke-like material. Their apparent molecular weights are on the order of several thousand and their chemistry and molecular structure are indefinite. A typical analysis show the following approximate composition: C: 85.2; H: 7.4; S: 0.7 and 0: 6.7 percent. Asphaltenes are the major constituents of the solid bitumen gilsonite.
When the solution loses its ability to disperse the colloidally suspended solid particles asphaltene deposition takes place down-hole at wellbore and adjacent to the pay zone. In extreme circumstances, as in some fields in East Venezuela, the deposits can severely plug off the production string, wellhead and even flow lines.
Factors Affecting Asphaltene Deposition
The balance tending to hold the asphaltene in a stable suspension is susceptible to most of the same conditions causing paraffin deposition plus the composition of crude oil and the nature of the reservoir rock surface.
Magnetic Fluid Conditioners have been in use for some time to treat both inorganic and organic deposition in oil wells, cooling towers and other industrial complexes. The basics for the MFC’s in use in the oil industry is that by flowing well fluids through a strong magnetic field inside a housing the deposition pattern is altered without affecting the crude oil characteristics thus inhibiting the build up of solids in the well and production equipment.
There are three main components in a MFC: 1) The case or housing, 2) the magnetic material used and 3) the circuit design. The case or housing is where the permanent magnets are attached. The best material available so far is the series 300 stainless steel due to the tough conditions found in an oil well. The magnetic material is one of the most important components of the MFC since it will generate the magnetic flux which will act on the fluid passing through the tool.
Magnetic materials can be classified in a) soft non-retentive and b) hard retentive. The second group is the one most used today in MFC’s since they yield higher energy product along with high remanence and coercitive force which make them ideal for permanent magnets. The energy product (BH) is an indication of the magnetic energy available outside the magnet and the higher it is, the higher the flux density acting on the passing fluid. Along the years the progressive increase in the availability of higher energy product magnetic materials have enhanced the possibility for the designing of more powerful MFC’s. This means that today’s MFC’s are 1.5 to 2 times stronger than 2 years ago as the new rare earth magnetic material whose energy product is in the range of 30-40 MG-Oes. However, no matter the power of the magnet and the quality of the housing to hold it, the tool will no work properly if the circuit design is not the appropriate one.
Gruber and Carda (South Dakota School of Mines) proposed grouping the basic design of magnetic devices into four classes:
Class I. – This design consist of magnets, usually made of ceramics material, fastened to the outside of a pipe, sometimes short lengths of production tubing (pup joints), so the device can be screwed into the production string. This is the first generation design. It is the least likely to succeed because the magnetic energy is first absorbed by the steel case. The remaining energy acts mostly parallel to the fluid flow and the central mass of the fluid is not exposed to the magnetic energy. This is why most of the time multiple tools need to be placed in the production string. Because the magnetic energy also acts outside the tool, well logging is likely to be affected.
Class II. – This type of device makes provision to control the direction of flux (perpendicular to the fluid flow) and to compress the flux to increase its density in the fluid passage. The fluid is exposed in its entirety to the magnetic flux which assures that, in normal producing conditions, one tool is enough to treat the production of a given well. The permanent magnetic material does not give up its strength to the system so production well logs are not affected.
Improvements to this design by Mag-Well, Inc, have turned into the Second MFC Generation. No external power is required at all and there is no need to regenerate the internal magnets. The energy source comes from a slight pressure drop, which occurs when the fluid passes through the venturi inside the tool.
Class III. – This design consists of a magnet or series of magnets suspended as a core in the center of a ferromagnetic tube or pipe. The magnets are usually set longitudinally with closed packed opposing poles.
As for Type I design, here the portion of exposed fluid to possibility to compress flux density does not exist. This makes this design inefficient and would also need multiple tools to yield moderate results. Class IV. – This class contains some electromagnetic types, which are not practical in oil wells.
Mag-Well Magnetic Fluids Conditioners – The Second Generation
The basics of the MFC requires well conditions that fit into scope of the design. If the MFC is not properly designed for a particular well, it will not be fully efficient. The scope of the design comprise many parameters being the following the most relevant:
a) Flux density, direction and strength of the magnetic field. b) MFC internal velocity of the fluid being treated and c) Exposure time of the fluid to the magnetic flux inside the MFC.
Type H design is the only one able to allow a complete control on both density and direction of the magnetic field. With this in mind, Mag-Well, Inc has developed the Second Generation of MFC’s. Through a careful design based on the production rate, the MFC is designed to achieve a perfect balance between the magnetic field density and intensity and the velocity and exposure time of the fluid to be treated.
Producing mechanism is extremely important for the design of the MFC. For natural flow or continuous gaslift wells the internal flow area is one of the major parameters since it will control the velocity of the fluid inside the MFC The balance must be exact to achieve the right exposure time with the minimal pressure loss (needed to energize the permanent magnets) through the MFC. This guarantees that the flow area inside the MFC will not impose a restriction to the flow of fluids from the well. For reciprocal pumping or intermittent gaslift wells considerations are mainly based on the amount of fluid entering to the tubing string on each cycle. Critical parameters are the pump plunger diameter; stroke length and strokes per minute for pumping wells. For intermittent gaslift cycles per hour and amount of fluid per cycle are important design parameters. For wells producing through ESP or PCP the design criteria is more like the one for natural flow or continuous gaslift wells.
Depth of deposition is critical for the correct placing of the MFC in the tubing string. Formation temperature is also essential since it will dictate the type of material to be used for the permanent magnets and the rest of the components.
Based on the foregoing, it is necessary to collect the best set of data from the well to be treated so the MFC will be designed for those particular conditions. Gaslifted wells generate additional cooling of the fluid in front of the gaslift mandrels so the collection of data here is even more important. One of the common mistakes some operators make is to believe that if the MFC was efficient in well ‘A’ it will also be in well B’. The truth is that unless both wells falls within the same designing scope, chances are that it will not work with the same efficiency in the second well. There is an exception, however. In Maraven’s La Concepcion field, the MFC from well C-211 designed for 50 bpd, was installed in Feb 1994 in well C-200, a 25 bpd well with several rig jobs for paraffin deposition. During the remaining of 1994 the well produced without paraffin problems.
The MFC can treat either organic or inorganic deposits by changing only the exposure time of the fluid provided that the characteristics of the wells are similar.
Placing the MFC
Depending upon the amount of fluid passing through the MFC and the completion of the well, Mag-Well manufactures two types: Insert (1) and Tubing (T). For each type there are four series to match the tubing size: Series 300 for 2-3/8″, 500 for 2-7/8″, 700 for 3-1/2″ and 1000 for 4-1/2″ tubing.
The insert type has the advantage of placing it without manipulating the tubing. The 300 series can handle up to 750 bpd of fluid passing through the MFC, the 500 up to 1500 and the 700 series up to 3500.
In natural flow or gaslift wells, the insert type is run with wireline and set in the seating nipples of the production string.
In sucker rod pumping wells, the MFC is installed below the pump by only running it with the sucker rods.
The Tubing type is made up in the tubing string and its use is recommended when production rate exceeds the insert type capacity or those wells with ESP or PCP pumps. However, depending on the completion, insert types can be installed on wells with these types of submersible pumps.
The life of the tool is not known yet since some of the first of the 1000+ installed around the world are still in the wells. Mag-Well guarantees 7 years. It is believed that it could be between 10 and 12 years.
Experiences in Venezuela
3 MFC’s were installed in June 1992 for Maraven in La Concepcion, a field well known for its paraffin problems. Engineering Report IT-11269.93 dated May 1993 reported satisfactory results after 9 months of evaluation and recommended to install the MFC in more wells. In that period it was calculated that annual savings were in the order of US$ 40,000 in equipment and US$ 150,000 in production recovered. On the enclosed graphs one of the wells, C-211 was taken as example for comparison.
a) Remove and inhibit deposition
b) Neither external power nor maintenance needed
c) 100% safe for personnel, equipment and environment
d) Rig needed only for installation in pumping wells or with the tubing type. For natural flowing or gaslift wells the tool is set with wireline.
e) Cost effective and Long Service Life.
f) Can protect equipment from bottom hole up to tank farm storage
g) Well logging not affected.
a) Not a Full Bore tool when the Tubing Model is used.
Corney. John. “Advancements in the Use of Magnetics for Controlling Deposits and BS&W in Oil Wells”, 1993 Short Course, Texas Tech University, Short Course, Lubbock, TX Vera. Tarquino: Lopez. Antonio and Nunez Jose. “Evaluacion del Acondicionador Magnetico de Fluidos para Controlar la Depositacion de Parafina en La Concepcion”, Technical Report No. IT-11269.93, Maraven, May 1993. Maracaibo, October 1994.