Gas Turbines On-Board Ships
Density Limit in Fuel Oils
Engine Friendliness Numer (EFN)
The Benefits of One-Stop-Shop
Is the Status Quo Acceptable?
Common Sense in Bunker Fuel Selection and Testing
The next revolution in marine engines is definitely the gas turbine. It has come of age and many cruise ships and container carriers are seriously considering changing over from conventional diesel engines to gas turbines.
Gas turbines have come a long way. They can now use diesel fuels and, in a few instances, even use heavy fuel. The big question is can they use the residual fuel, which the slow speed diesel engines are currently consuming? If they can, we are certainly looking at a major change to gas turbines which weigh less, occupy less space, need less maintenance and have higher thermal efficiency. If they can't, what happens to the residual fuel that is left unused when more and more ships switch over to gas turbine engines and perhaps diesel fuels?
When we look at the specifications for IFO 180 and IF0 380 fuels, the most commonly used fuels in the marine industry, one parameter strikes the eye. The density value is maxed at 991 kg per meter cubed. The marine industry pays for fuel based on the mass not volume. Therefore, every supplier wants to supply fuel as near to 991 kg per meter cubed as possible. However, the conventional purifiers which most of the ships still carry, can handle a maximum density of 991 kg per meter cubed. So, what happens when a supplier supplies fuel at 991 kg per meter cubed and this fuel will not even be purified properly in the conventional purifier because its limit of efficient operation is also the same 991 kg per meter cubed? This fuel will get into the engine without getting properly purified and is likely to cause more damage to the machinery. Why can't we define the density limits of IFO 180 and IFO 380 to not 991 kg per meter cubed but 9850 kg per meter cubed? This will help in better purification and lesser damage to the machinery.
Viswa Lab Corporation has a unique benchmark of fuel quality called Engine Friendliness Number (EFN). EFN is a computer-generated index that provides a unique method of assessing quality of individual bunker supply, and gives fuel users better insight into how fuels will perform in service. Based on a scale of 1-100, the lower numbers represent less engine-friendly fuels which are nearer to the upper end of specification limits, and the higher numbers approaching 100 indicate more engine-friendly fuels which are nearer to the lower end of the specification limit. This benchmark has been used over thousands of samples in the last seven years and VLC has very useful and important statistical information, bunkering port performance, vendor analysis and product analysis from refineries around the world.
When we have less and less time in a day it can be very frustrating to get kicked around from place to place when you are trying to identify the problem with your machinery. If you suspect the fuel oil, the fuel testing lab tests it but if you also suspect lube oil the fuel testing lab will throw up its hands and you now have to look for a lube testing lab. What if you have to test the material or if you have to conduct a failure analysis? Then you have to go to a third or fourth lab. It is therefore a good idea to go to one single lab to fix all the problems.
An Article Published in Bunker News
Dr. R. Vis, Viswa Labs Corporation (Formerly of Analytical Services & Materials, Inc. (AS&M))
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ABSTRACT: The quality of the bunker fuel is not at a level where one can be happy with the status quo. Fuel-related damages are increasing and the contaminants and adulterations in the fuel have to be looked at. The main thing is the will power of the industry to rid itself of bad fuels which can cause enormous damage to marine machinery.
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We have to ask ourselves this question and seek an honest answer. It is not enough if an ISO standard and specification are now available and in use. It is not enough if the industry appears to be stable, big (16 billion dollars), and reasonably globalized. There are indeed many problems.This situation is analogous to the state of general public health. Everything appears well-defined and under control. Then, an unknown epidemic strikes and wipes out some lives. No one knows what and why. When the number of lives lost is not too many, no further research or follow-up is done - everything is forgotten. There are other ailments that take a toll on human life over time, and even these are not tracked since the damage is slow and gathers over time, and there is no shockingly quick loss of life. Only big ailments affecting a large number of people attract attention.
The current story of the bunker fuel is not very different. A "rogue" fuel - as it is called by the industry - makes its appearance, causes a lot of damage, often incapacitating the ship for days. The damages are referred to as "phantom" damages to the ship's machinery. Phantom damages due to rogue fuel can damage fuel pumps, cylinder liner, piston rings, cause excessive deposits in combustion and exhaust spaces, and turbocharger, often requiring replacement of expensive spare parts, often bringing the ship operations to a halt and ruining the schedules.
It is argued by some pundits of the bunker fuel quality that the industry can afford to ignore these phenomena since they occur in less than 0.1% of the bunker supplies. Considering that at least 150,000 bunkering operations take place globally, this means at least 150 incidents per year, which can cumulatively cause machinery damage annually amounting to $50-$100 million. Besides these major damages, there are innumerable minor damages in the form of increased wear rate, increased corrosion, and increased generation of waste products. These, collectively and independently reduce the efficiency of the plant, decrease the speed of the ship, and decrease MTBF (Mean Time Between Failures). The role of rogue fuel in causing insidious phantom damage has never been quantified, but can be guesstimated to run into millions of dollars.
The pity is that most of these damages are not even recognized, much less recorded. Only such of those damages which completely damage the machinery, disrupt the ship's schedule, and cause dangerous situations such as total blackout or drifting powerless mid-ocean, are the ones that are taken serious note of by the ship operators. Even here, since the process of testing the fuel, establishing that the fuel quality alone is the cause of the problem are so lengthy and tiresome, with no guarantee of success, that the operators sometimes find it easier to blame it on the ship staff and conveniently forget the whole incident after a few months. It is not difficult to attribute the cause of damage to overloading the engine or overheating the engine with inadequate cooling, improper operation of the fuel purification plant, etc. - all of which fall under the responsibility of the ship's operating engineers. Besides, insurance often covers "operator fault" and pursuing this line of thought also does not hurt monetarily!
What are the harmful substances in the fuel that have the potential to cause damage to the engine? Here, we are not talking about the substances that are analyzed, substances that are known to be present in the residual fuel. In fact, we are talking about substances that may have been added to the bunker fuel. The sources for these additions - adulterations may be a better word- are many. The black colored residual fuel conveniently accepts all kinds of stuff thrown into it and does not complain. It is the engine that complains! It is not necessary to establish every source of every chemical that could have been thrown into the bunker fuel. Why would an unscrupulous bunker supplier adulterate? Let me make it clear that there are two classes of bunker suppliers -- one that adulterates knowingly. The other wants to supply quality bunker fuel and may not even by aware of adulteration. They too supply bad fuel in good faith! The main reason for the adulteration is to cut costs and make more profits. The game plan would be to obtain substances which cost next to nothing and add it to bunker fuel and maximize profits without getting found out. Obviously, none will add a product which is high in sulphur or carbon residue. The analysis of the fuel will reveal this adulteration and possibly throw this fuel out of specifications. Then the whole business is lost, having killed the goose that lays the golden eggs. Sources for products which can be used for adulterating should be available easily. These sources must be eager to get rid of the product since there is a cost associated with the disposal of these products. Just to put some perspective into this, in the USA alone, 1.5 billion gallons of waste oil is disposed of every year -- some converted to diesel fuel, some converted to regenerated lube oil, and others incinerated. Here are some of the sources of products that are used to adulterate bunker fuel:
1) Every ship has one or more waste oil tanks. These tanks collect the sludge from the purifiers, drips and leakages of fuel or lube oil from the engine. These are unusable on board the vessel, and they have to be pumped out to waste disposal sites in various ports.There is a high cost associated with this disposal operation.
2) Industries produce waste oils - mostly lubricating oils used on the machinery - which need to be disposed of after they deteriorate and lose their properties. A prime example is the cutting oils from machine tool industry. These oils cool the cutting tools and also render the cutting process smooth. Due to arduous conditions under which they carry out this function, they deteriorate in quality over time and have to be disposed of. Of course there is a disposal cost associated with this.
Waste oil tanks contain substances that must be disposed of. Cutting oils often contain certain chlorides which are extremely harmful when they get into an engine. For instance, the refinery industry and the pipeline transportation industry are almost paranoid about organic chlorides. They will not allow any crude oil to enter their system that contains more than 3 parts per million (ppm) of organic chlorides. There is enough evidence of ruined refinery equipment as a result of processing crudes with greater than 3 ppm organic chlorides. Besides this, chlorides have the property of accelerating the corrosion process by factors of 50 to 400 particularly in presence of steel which is the manufacturing material for most marine machinery. There are substances such as degreasing agents, disposals from dry cleaning industry, all of which contain organic chlorides. There is a disposal cost associated with these industrial wastes since they are highly toxic and highly harmful if used in any machinery or equipment under exposed conditions.
So, what better way than to dump into this dark viscous uncomplaining undefined residual bunker fuel! Nobody is looking for it, nobody is likely to detect it, the harm it does is not instantly recognizable (unless too much quantity is adulterated due to ignorance or greed). Someone would pay to get it disposed of, and others (the bunker buyers) would pay for it when it is mixed with the bunker fuel. What a convenient temptation! One has to be almost a saint to resist it!
One other important factor that is often missed in assessing the damage caused by adulteration of bunker fuel is CCAI (combined carbon aromaticity index). Unfortunately, the only way the CCAI number is arrived at currently is through a mathematical computation of density and viscosity. When all kinds of things are thrown into the bunker fuel, they often have the effect of delaying ignition, resulting in late combustion, afterburning, and the attendant consequences. The principle attendant consequence is the burning up of the lube oil film on the cylinder liner surface, promoting high wear rate. In addition, afterburning also deposits unburned hydrocarbons in the combustion and exhaust spaces, including turbochargers. These deposits choke up passages, cause overheating, and generally reduce the engine efficiency. The bunker buyer looks at an acceptable CCAI number and goes with the impression that he has purchased a good fuel. However, the effects of adulteration and afterburning are insidious and damage accumulates over time. In deciding if we would like the status quo to continue, or to improve things in bunker fuel quality, the following points of view have to be addressed:
1) What is the real objection to mixing waste oils to bunker fuel? After all it is being done now on a wide scale and international shipping has not ground to a halt. Every waste disposal is associated with incinerating the waste product. Why not do that inside a diesel engine?
2) The marine industry is not a small one. The marine machinery is not inexpensive. The consequences of damage to machinery are not insignificant- they also impact on the time schedule, contractual obligations and the safety of the ship's crew. Can this industry continue to afford to use a fuel which is ill-defined, inadequately tested and lends itself to adulteration without the possibility of detection?
The two paragraphs above detail the two schools of thought in the bunker industry. It is both a philosophic and economic question.
If we take the aircraft industry we cannot even afford to think along any but the highest standard. This would be the case even if the aircraft carried no passengers and even if the pilot had facilities to eject out of the plane if it got into trouble. Here the choice is clear. Nothing but the best would do. If a better fuel costs more and if the air transportation had to bear this cost, so be it. The added cost is common to the whole industry and is accepted as a part of the technology cost. There are no doubtful points about the clear definition of the aircraft fuel, the method of controlling its quality during manufacture, storage and distribution. Let us face it. The aircraft industry is a glamorous one. If a plane crashes and fifty people die it will be front page news for several days. We have never heard of an aircraft which crashed because the fuel was adulterated. The U.S. government released 500 million dollars for research on aging aircrafts within days of the recent TWA crash off New York. About 150 seafarers have been dying every year due to ships sinking, fire etc. At best this makes news in the twelfth page of a newspaper in an insignificant corner.
There are concerns voiced about "industry practice", "enforcement problems", "increasing operation costs" and "what's wrong with status quo ?" First of all, if nothing is wrong with status quo and there are no problems with bunker fuel, why are we talking about this topic? There are problems and these problems are mounting. Even classification societies such as NKK have identified the seriousness of the problem and are documenting the incidence of fuel-related damage, analyzing the causes and suggesting solutions. Take away all the fancy talk, there is only one question. Do we have the will power to face this problem and eliminate it altogether? Do we have the vision to pay a little more but get a fuel which would be beyond reproach? To me the answer is simple. It is certainly do-able. Heavy and punitive fines can keep a bunker supplier from resorting to any adulteration. The bunker fuel should be purely a product of the distillation process. There should be nothing added to it at any point of time. The bunker fuel should be tested, at least on a random basis, not only for the parameters defined in the specifications but also for other likely sources. A strict vigilance and accounting system for waste products in ports and in ships should ensure that they do not find their way into bunker suppliers' tanks. There should be a mandatory barge sample analysis and a punitive damage threat over the barge operator to keep him honest and not attempt adulteration on the barge. If all this adds a few dollars to a ton to the cost of the bunker fuel, we should have the far sightedness to absorb it in the operating cost. This way, we will prevent catastrophic damages and losses overtaking a few unfortunate ships and raise the level of confidence in the quality of fuel with the rest of the industry.
We at AS&M have experienced a dramatic increase in fuel-related damages which we address as a part of our failure analysis services. We provide to our customers whose fuels and lubes we also analyze.
Contact - customerhelp@viswalab.com
Common Sense in Bunker Fuel Selection and Testing
by Dr. R. (Vis) Visweswaran
Viswa Lab Corporation
Houston, Texas, USA"The crown of all faculties is common sense. It is not enough to do the right thing; it must be done at the right time and place. Talent knows what to do; tact knows when and how to do it." - William Mathews
Common sense is not such a commonly available commodity! Every day in ship operations, one is required to make decisions. Though a lot of data is made available to make those decisions, mere numbers cannot dictate decisions. An undercurrent of common sense, previous experience, and general feel for the situation are the factors that will dictate the decisions. Some of the items on which decisions have to be made are listed below. Common sense solutions are provided for the guidance of the ship manager. These are based on the many years of experience of the author on all three aspects of the bunker-user (ship's engineer), impartial observer (surveyor), and analyst (lab in charge). It is hoped that this common sense approach will be useful for practical situations that arise in ship operations. These are only suggestions, not recommendations. Obviously, decisions have to be based on actual situations.
COMMON SENSE CONCERNS IN BUNKER FUEL SELECTION AND TESTING:
1. Choose 180 Grade or 380 Grade? Are there real benefits in 180 Grade that warrant paying $5/ton additional price?
2. Should the user go with oil majors and pay $3 - $5/ton more, or is it better to go to smaller players - bunker brokers?
3. If bunker fuel does not meet specs, what to do -- reject/throw out -- How far out of spec can be tolerated?
4. Costs of testing and not testing.
5. How reliable are lab results? Why do different labs put out different results?
6. What on-board treatment can solve bunker fuel problems?The above concerns are discussed below:
GRADE 180 OR GRADE 380? Difference:
Grade 180 - 7-15% distillate content
Grade 380 - 2-5% distillate content
Price of grade 180 is at least $3 - $5 more than grade 380
Why Choose 180?
Engine Maker recommendation
Perception that 180 is better than 380Our Experience:
Sulphur More of the 180 grade samples (0.7%) had more sulphur than 380 grade Si + Al More samples (0.5%) of grade 180 had more Al + Si than samples of grade 380
Na + V More (1.5%) samples of grade 180 were nearer to the undesirable 1:3 ratio of sodium and vanadium than these of grade 380.
EFN or Engine Friendliness Number is a computer-generated Index that provides a unique method of assessing quality of individual bunker supply, and gives fuel users better insight into how fuels will perform in service. Based on a scale of 1-100, the lower numbers represent less engine-friendly fuels which are nearer to the upper end of specification limits, and the higher numbers approaching 100 indicate more engine-friendly fuels which are nearer to the lower end of the specification limit.
Based on hundreds of samples received at the lab, it is clear that grade 380 is more engine-friendly than grade 180.
But the perception of many ship managers is that grade 180 is a better fuel and they are therefore willing to pay a higher price to get an inferior fuel. (This argument assumes that the engine manufacturer permits the use of both grades of fuel in the engine.)
ECONOMICS OF TESTING:
Say a vessel bunkers 8 times per year.
Annual cost per ship - : 8 x $250 = $2000
Say you bunker 1000 tons each time: @ $100 per ton
Total bunker cost is 8 x 1000 x 100 = $800,000
Testing cost as a proportion of bunker cost = 1/400
Testing cost as additional cost on a ton of bunkers = $100.25, i.e. 25 cents more per tonSay ship operation cost is $8,000 per day --
Bunker test cost per day = 2000 = $5.5
365
Bunker test cost as proportion of operation cost: 5.5 = 1
8000 1500CONCLUSION: TESTING COST IS A PITTANCE, AND THE QUESTION IS NOT IF YOU CAN AFFORD TO TEST, BUT CAN YOU AFFORD NOT TO TEST! COMPARISON: OIL MAJORS VS. BUNKER BROKERS
ITEM OIL MAJOR BUNKER BROKER
Share of the market for bunker supply in 1982 Oil majors, 54.2% Bunker brokers, 45.8%
Share of the market for bunker supply in 1993 Oil majors, 27.8% Bunker brokers, 72.2%
Price for bunker $4 - $5 more than bunker broker price (competitive price)
Supply services Better (where available) Varies, but available everywhere Testing Tested in their own lab Tested in any lab of convenience Warranties on quality of fuel More customer-friendly Likely to be stringent. Disputes Less likely. More likely Dispute resolution. Can be more protracted. Compromise more likely. Fuel quality Knows exactly what he is supplying Broker himself may not know and this may result in some undesirable fuel supply.COMMON SENSE IN BUNKER PURCHASE
1. Buy 380 grade if engine manufacturer permits use of this grade
2. Do test, it costs only 25¢ per ton of fuel
3. Try out only a reputed bunker broker and also test the fuel; you may save a few dollars per ton compared to what you pay to an oil major.LIMITS BASED ON COMMON SENSE:
How Much Out of Spec Can Be Tolerated?
The table below lists the various parameters and their values, as specified by the various grades of bunker fuel. The question is, how much out of specification can be tolerated? Here are some suggestions:Problem Limit Suggestion Remarks
High Density Limit 991 Extend to 996 if water <0.5% Operate as clarifierheat and settle and drain
High Viscosity 180 at 50°C380 at 50°C 225 at 50°C475 at 50°C Tank heating, fuel heating should be effective. At injection temp. viscosity difference is very low.
High Water 1% Extend to 3%-5% Related to density and whether it is salt water or fresh water
Carbon Residue 15% Increase by 20%, i.e. 18% carbon residue Do this for only one voyage. Inspect exhaust passages.
Ash 0.1% 25% higher, i.e. 0.13 Purify continuously. Oil soluble elements V, Zn, Mg cannot be reduced. Al, Si, Fe can be. Salt water in fuel increases ash.
Aluminum & Silicon 80 ppm 100-120 ppm Further purification can reduce it. Vanadium 300 ppm Increase 20%, up to 360 ppm Do this for only one voyage -- watch for Na:V ratio of 1:3.
Total Sediment 0.1% 0.2% Limits of precision of the test method allow this
Sulphur 5% -- Limit rarely crossed
CCAI 850 870 Usually a problem with high density -- low viscosity fuels.
Used lube oil contamination Expect emulsions if water is present in fuel. Expect transfer of metallic particles into engine.STANDARD SPECIFICATIONS:
HOW MUCH OUT OF SPEC CAN BE TOLERATED?The standards give ranges for "out of specification" under two categories: Repeatability - defined as the variance in results when the same sample is tested in the same lab, using the same method, by two different analysts. Reproducability - defined as the variance in results when the same sample is tested in two different labs, by two different analysts, using the same method. A single-lab system is preferable, where the quality can be maintained within much tighter limits. ASTM has criteria for repeatability, and is 2-3 times more stringent than reproducability. In other words, for example, pour point can vary only within 3°C in the same lab (repeatability) while in two different labs, it can vary as much as 6°C (reproducability). Density in the same lab can vary .0006 kg/m3 (repeatability) whereas in two different labs it can vary by .0015 kg/m3 (reproducability). If you want the highest quality, you must test the fuel in only one lab.
FACTOR REPEATABILITY REPRODUCABILITY
Density 0.0006 0.0015
Viscosity: ASTM 1.3% of mean + 8 cSt 4% of mean + 8 cSt
ISO 0.35% of mean 0.7% of mean
Water 0.1 or 2%, whichever is greater 0.2 or 10%, whichever is greater
Carbon residue (%C)2/3 X 0.077 (%C)2/3 X 0.245 Pour Point 3°C 6°C
Sulphur 0.017 (X + 0.8) 0.055 (X + 0.8)
Ash 0.001 to 0.00790.080 to 0.0180 0.0030.007 0.0050.024 AluminumSilicon IP-377 0.066x0.0643x 0.337x0.332x
Sediment: for residual for distillate 0.123 times square root of x0.048 times square root of x 0.341 times square root of x0.174 times square root of x
x = average valueSHIPBOARD FUEL TREATMENT SYSTEMS:
Bunker fuel as received at custody point is the bunker fuel that gets into the engine. What can shipboard treatment do? Every ship has considerable capability for fuel treatment onboard, and these well-known facilities are listed below, along with suggestions for imaginatively combining the facilities to obtain the desired fuel treatment:
o Heat the fuel, settle it, drain the water
o Purify it, remove water and heavier particles
o Clarify it and remove solid particles
o Two purifiers in series (remove excess water)
o Two clarifiers in parallel
o Various filters
o Heaters and automatic viscosity controllers
o Routine draining of water and particulates from service tanks
o Compatibility and stability tests
o Shipboard test kit
o Fuel additives
o Blending fuels on boardIt is hoped that the above analysis will help generate decisions that make sense; common sense!
Contact: - customerhelp@viswalab.com
