Fuel oil is a
fraction obtained from
petroleum distillation, either as a distillate or a residue. Broadly speaking fuel oil is any liquid petroleum product that is burned in a
furnace or
boiler for the generation of heat or used in an
engine for the generation of power, except oils having a
flash point of approximately
40 °C (104 °F) and oils burned in cotton or wool-wick burners. In this sense,
diesel is a type of fuel oil. Fuel oil is made of long
hydrocarbon chains, particularly
alkanes,
cycloalkanes and
aromatics. The term
fuel oil is also used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from
crude oil i.e. heavier than
gasoline and
naphtha.
In Australia the term 'distillate' refers specifically to
Diesel fuel [1]
Classes
The
ASTM
classification system was originally based on early refining and
combustion engineering practices and nomenclature. Some specifications
have changed over the years to reflect new refining practices and
refinery by-products. Other organizations have published modified
versions of the original six fuel specifications to assist operators of
older equipment find appropriate fuels from current refinery products.
[2]
Although the following trends generally hold true, different
organizations may have different numerical specifications for the six
fuel grades. The boiling point and
carbon chain length of the fuel increases with fuel oil number.
Viscosity
also increases with number, and the heaviest oil has to be heated to
get it to flow. Price usually decreases as the fuel number increases.
[3]
Number 1 fuel oil is a volatile distillate oil intended for vaporizing pot-type burners.
[2] It is the
kerosene refinery cut that boils off right after the heavy naphtha cut used for
gasoline. Older names include coal oil, stove oil and range oil.
[3]
Number 2 fuel oil is a distillate home
heating oil.
[2] Trucks and some cars use similar
diesel fuel with a
cetane number
limit describing the ignition quality of the fuel. Both are typically
obtained from the light gas oil cut. Gas oil refers to the original use
of this fraction in the late 19th and early 20th centuries - the gas oil
cut was used as an enriching agent for
carburetted water gas manufacture.
[3]
Number 3 fuel oil was a distillate oil for burners requiring
low-viscosity fuel. ASTM merged this grade into the number 2
specification, and the term has been rarely used since the mid-20th
century.
[2]
Number 4 fuel oil is a commercial heating oil for burner installations not equipped with preheaters.
[2] It may be obtained from the heavy gas oil cut.
[3]
Number 5 fuel oil is a residual-type industrial heating oil
requiring preheating to 170 – 220 °F (77 – 104 °C) for proper
atomization at the burners.
[2] This fuel is sometimes known as Bunker B. It may be obtained from the heavy gas oil cut,
[3] or it may be a blend of residual oil with enough number 2 oil to adjust viscosity until it can be pumped without preheating.
[2]
Number 6 fuel oil is a high-viscosity residual oil requiring
preheating to 220 – 260 °F (104 – 127 °C). Residual means the material
remaining after the more valuable cuts of crude oil have boiled off. The
residue may contain various undesirable impurities including 2 percent
water and one-half percent mineral soil. This fuel may be known as
residual fuel oil (RFO), by the Navy specification of Bunker C, or by
the Pacific Specification of PS-400.
[2]
Mazut
is a residual fuel oil often derived from Russian petroleum sources and
is either blended with lighter petroleum fractions or burned directly in
specialized boilers and furnaces. It is also used as a petrochemical
feedstock.
Bunker fuel
A sample of residual fuel oil.
Small molecules like those in
propane,
naphtha,
gasoline for cars, and
jet fuel have relatively low
boiling points, and they are removed at the start of the
fractional distillation process. Heavier petroleum products like
diesel and
lubricating oil
are much less volatile and distill out more slowly, while bunker oil is
literally the bottom of the barrel; the only things more dense than
bunker fuel are
carbon black feedstock and
bituminous residue which is used for paving roads (
asphalt) and sealing roofs.
Bunker fuel is technically any type of fuel oil used aboard
ships. It gets its name from the containers on ships and in
ports
that it is stored in; in the days of steam they were coal bunkers but
now they are bunker fuel tanks. The Australian Customs and the
Australian Tax Office define a bunker fuel as the fuel that powers the
engine of a ship or aircraft. Bunker A is No. 2 fuel oil, bunker B is
No. 4 or No. 5 and bunker C is No. 6. Since No. 6 is the most common,
"bunker fuel" is often used as a synonym for No. 6. No. 5 fuel oil is
also called
navy special fuel oil or just
navy special; No. 5 or 6 are also called
furnace fuel oil (
FFO); the high viscosity requires heating, usually by a recirculated low pressure
steam
system, before the oil can be pumped from a bunker tank. In the context
of shipping, the labeling of bunkers as previously described is rarely
used in modern practice.
Since the 1980s the
International Organization for Standardization
(ISO) has been the accepted standard for marine fuels (bunkers). The
standard is listed under number 8217, with recent updates in 2005 and
2010. They have broken it down to Residual and Distillate fuels. The
most common residual fuels in the shipping industry are RMG and RMK.
[4]
The differences between the two are mainly the density and viscosity,
with RMG generally being delivered at 380 centistokes or less, and RMK
at 700 centistokes or less. Ships with more advanced engines can process
heavier, more viscous, and thus cheaper, fuel. Governing bodies (i.e.
California, European Union) around the world are starting to limit the
maximum sulfur of fuels burned in their ports to limit pollution. This
is where Marine Distillate Fuels come into play. They have similar
properties to Diesel #2 which is used as road Diesel around the world.
The most common grades used in shipping are DMA and DMB.
[5]
|
This section needs attention from an expert in Energy. Please add a reason or a talk parameter to this template to explain the issue with the section. WikiProject Energy (or its Portal) may be able to help recruit an expert. (September 2008) |
Table of fuel oils |
Name |
Alias |
Alias |
Type |
Chain Length |
No. 1 fuel oil |
No. 1 distillate |
No. 1 diesel fuel |
Distillate |
9-16 |
No. 2 fuel oil |
No. 2 distillate |
No. 2 diesel fuel |
Distillate |
10-20 |
No. 3 fuel oil |
No. 3 distillate |
No. 3 diesel fuel |
Distillate |
|
No. 4 fuel oil |
No. 4 distillate |
No. 4 residual fuel oil |
Distillate/Residual |
12-70 |
No. 5 fuel oil |
No. 5 residual fuel oil |
Heavy fuel oil |
Residual |
12-70 |
No. 6 fuel oil |
No. 6 residual fuel oil |
Heavy fuel oil |
Residual |
20-70 |
Uses
Oil has many uses; it heats homes and businesses and fuels
trucks,
ships and some
cars. A small amount of
electricity is produced by diesel, but it is more polluting and more expensive than
natural gas. It is often used as a backup fuel for
peaking power plants in case the supply of natural gas is interrupted or as the main fuel for small
electrical generators.
In Europe, the use of diesel is generally restricted to cars (about
40%), SUVs (about 90%), and trucks and buses (virtually all). The market
for home heating using fuel oil, called heating oil, has decreased due
to the widespread penetration of
natural gas. However, it is very common in some areas, such as the
Northeastern United States.
Fuel oil truck making a delivery in North Carolina, 1945.
Residual fuel oil is less useful because it is so
viscous that it has to be heated with a special heating system before use and it contains relatively high amounts of
pollutants, particularly
sulfur, which forms
sulfur dioxide
upon combustion. However, its undesirable properties make it very
cheap. In fact, it is the cheapest liquid fuel available. Since it
requires heating before use, residual fuel oil cannot be used in road
vehicles,
boats
or small ships, as the heating equipment takes up valuable space and
makes the vehicle heavier. Heating the oil is also a delicate procedure,
which is inappropriate to do on small, fast moving vehicles. However,
power plants and large ships are able to use residual fuel oil.
Residual fuel oil was used more frequently in the past. It powered
boilers,
railroad steam locomotives and
steamships. Locomotives now use diesel; steamships are not as common as they were previously due to their higher operating costs (most
LNG carriers
use steam plants, as "boil-off" gas emitted from the cargo can be used
as a fuel source); and most boilers now use heating oil or natural gas.
However, some industrial boilers still use it and so do a few old
buildings, including in
New York City. The City estimates that the 1% of its buildings that burn fuel oils No. 4 and No. 6 are responsible for 86% of the
soot
pollution generated by all buildings in the city. New York has made the
phase out of these fuel grades part of its environmental plan,
PlaNYC, because of concerns for the health effects caused by fine particulates.
[6]
Residual fuel's use in electricity generation has also decreased. In
1973, residual fuel oil produced 16.8% of the electricity in the United
States. By 1983, it had fallen to 6.2%, and as of 2005, electricity
production from all forms of petroleum, including diesel and residual
fuel, is only 3% of total production. The decline is the result of price
competition with natural gas and environmental restrictions on
emissions. For power plants, the costs of heating the oil, extra
pollution control and additional maintenance required after burning it
often outweigh the low cost of the fuel. Burning fuel oil, particularly
residual fuel oil, produces uniformly higher
Carbon Dioxide emissions than natural gas,
[7] which affects the community's perception.
Heavy fuel oils continue to be used in the boiler "lighting up"
facility in many coal-fired power plants. Although on an enormous scale,
this use is analogous to lighting kindling to start a fire; without
performing this simple function it is difficult to begin the large-scale
combustion process.
The chief drawback to residual fuel oil is its high initial
viscosity, particularly in the case of No. 6 oil, which requires a
correctly engineered system for storage, pumping, and burning. Though it
is still usually lighter than water (with a specific gravity usually
ranging from 0.95 to 1.03) it is much heavier and more viscous than No. 2
oil, kerosene, or gasoline. No. 6 oil must, in fact, be stored at
around
100 °F (38 °C)
heated to 150–250 °F (66–121 °C) before it can be easily pumped, and in
cooler temperatures it can congeal into a tarry semisolid. The flash
point of most blends of No. 6 oil is, incidentally, about
150 °F (66 °C).
Attempting to pump high-viscosity oil at low temperatures was a
frequent cause of damage to fuel lines, furnaces, and related equipment
which were often designed with lighter fuels in mind.
For comparison, BS2869 Class G Heavy Fuel Oil behaves in similar fashion, requiring storage at
104 °F (40 °C), pumping at around
122 °F (50 °C) and finalising for burning at around 194–248 °F (90–120 °C).
Most of the facilities which historically burned No. 6 or other
residual oils were industrial plants and similar facilities constructed
in the early or mid 20th century, or which had switched from coal to oil
fuel during the same time period. In either case, residual oil was seen
as a good prospect because it was cheap and readily available. Most of
these facilities have subsequently been closed and demolished, or have
replaced their fuel supplies with a simpler one such as gas or No. 2
oil. The high sulfur content of No. 6 oil—up to 3% by weight in some
extreme cases—had a corrosive effect on many heating systems (which were
usually designed without adequate corrosion protection in mind),
shortening their lifespans and increasing the polluting effects. This
was particularly the case in furnaces that were regularly shut down and
allowed to go cold; the internal condensation produced sulfuric acid.
Environmental cleanups at such facilities are frequently complicated by the use of
asbestos
insulation on the fuel feed lines. No. 6 oil is very persistent, and
does not degrade rapidly. Its viscosity and stickiness also make
remediation of underground contamination very difficult, since these
properties reduce the effectiveness of methods such as
air stripping.
When released into water, such as a river or ocean, residual oil
tends to break up into patches or tarballs—mixtures of oil and
particulate matter such as silt and floating organic matter- rather than
form a single slick. An average of about 5-10% of the material will
evaporate within hours of the release, primarily the lighter hydrocarbon
fractions. The remainder will then often sink to the bottom of the
water column.
Maritime
In the
maritime field another type of classification is used for fuel oils:
- MGO (Marine gas oil) - roughly equivalent to No. 2 fuel oil, made from distillate only
- MDO (Marine diesel oil) - A blend of heavy gasoil that may
contain very small amounts of black refinery feed stocks, but has a low
viscosity up to 12 cSt so it need not be heated for use in internal
combustion engines
- IFO (Intermediate fuel oil) A blend of gasoil and heavy fuel oil, with less gasoil than marine diesel oil
- MFO (Marine fuel oil) - same as HFO (just another "naming")
- HFO (Heavy fuel oil) - Pure or nearly pure residual oil, roughly equivalent to No. 6 fuel oil
Marine diesel oil contains some heavy fuel oil, unlike regular
diesels. Also, marine fuel oils sometimes contain waste products such as
used
motor oil.
Standards and classification
CCAI and
CII
are two indexes which describe the ignition quality of residual fuel
oil, and CCAI is especially often calculated for marine fuels. Despite
this marine fuels are still quoted on the international bunker markets
with their maximum viscosity (which is set by the ISO 8217 standard -
see below) due to the fact that marine engines are designed to use
different viscosities of fuel.
[8] The unit of viscosity used is the
Centistoke and the fuels most frequently quoted are listed below in order of cost, the least expensive first-
- IFO 380 - Intermediate fuel oil with a maximum viscosity of 380 Centistokes (<3.5% sulphur)
- IFO 180 - Intermediate fuel oil with a maximum viscosity of 180 Centistokes (<3.5% sulphur)
- LS 380 - Low-sulphur (<1.5%) intermediate fuel oil with a maximum viscosity of 380 Centistokes
- LS 180 - Low-sulphur (<1.5%) intermediate fuel oil with a maximum viscosity of 180 Centistokes
- MDO - Marine diesel oil.
- MGO - Marine gasoil.
- LSMGO - Marine gasoil.
- LSMGO - Low-sulphur (<0.1%) Marine Gas Oil - The fuel is to be used in EU community Ports and Anchorages. EU Sulphur directive 2005/33/EC
The
density
is also an important parameter for fuel oils since marine fuels are
purified before use to remove water and dirt from the oil. Since the
purifiers use
centrifugal force,
the oil must have a density which is sufficiently different from water.
Older purifiers had a maximum of 991 kg/m3; with modern purifiers it is
also possible to purify oil with a density of 1010 kg/m3.
The first British standard for fuel oil came in 1982. The latest
standard is ISO 8217 from 2005. The ISO standard describe four qualities
of distillate fuels and 10 qualities of residual fuels. Over the years
the standards have become stricter on environmentally important
parameters such as sulfur content. The latest standard also banned the
adding of used lubricating oil (ULO).
Some parameters of marine fuel oils according to ISO 8217 (3. ed 2005):
Marine Distillate Fuels |
Parameter |
Unit |
Limit |
DMX |
DMA |
DMB |
DMC |
Density at 15°C |
kg/m3 |
Max |
- |
890.0 |
900.0 |
920.0 |
Viscosity at 40°C |
mm²/s |
Max |
5.5 |
6.0 |
11.0 |
14.0 |
Viscosity at 40°C |
mm²/s |
Min |
1.4 |
1.5 |
- |
- |
Water |
% V/V |
Max |
- |
- |
0.3 |
0.3 |
Sulfur1 |
% (m/m) |
Max |
1.0 |
1.5 |
2.0 |
2.0 |
Aluminium + Silicon2 |
mg/kg |
Max |
- |
- |
- |
25 |
Flash point3 |
°C |
Min |
43 |
60 |
60 |
60 |
Pour point, Summer |
°C |
Max |
- |
0 |
6 |
6 |
Pour point, Winter |
°C |
Max |
- |
-6 |
0 |
0 |
Cloud point |
°C |
Max |
-16 |
- |
- |
- |
Calculated Cetane Index |
|
Min |
45 |
40 |
35 |
- |
- Max sulfur content is 1.5% in designated areas. (since 1-07-2010 1% is max).
- The aluminium+silicon value is used to check for remains of the
catalyst after catalytic cracking. Most catalysts contains aluminium or
silicon and remains of catalyst can cause damage to the engine.
- The flash point of all fuels used in the engine room should be at
least 60°C (DMX is used for things like emergency generators and not
normally used in the engine room).
Marine Residual Fuels |
Parameter |
Unit |
Limit |
RMA 30 |
RMB 30 |
RMD 80 |
RME 180 |
RMF 180 |
RMG 380 |
RMH 380 |
RMK 380 |
RMH 700 |
RMK 700 |
Density at 15°C |
kg/m3 |
Max |
960.0 |
975.0 |
980.0 |
991.0 |
991.0 |
991.0 |
991.0 |
1010.0 |
991.0 |
1010.0 |
Viscosity at 50°C |
mm²/s |
Max |
30.0 |
30.0 |
80.0 |
180.0 |
180.0 |
380.0 |
380.0 |
380.0 |
700.0 |
700.0 |
Water |
% V/V |
Max |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
Sulfur1 |
% (m/m) |
Max |
3.5 |
3.5 |
4.0 |
4.5 |
4.5 |
4.5 |
4.5 |
4.5 |
4.5 |
4.5 |
Aluminium + Silicon2 |
mg/kg |
Max |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
Flash point3 |
°C |
Min |
60 |
60 |
60 |
60 |
60 |
60 |
60 |
60 |
60 |
60 |
Pour point, Summer |
°C |
Max |
6 |
24 |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
Pour point, Winter |
°C |
Max |
0 |
24 |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
30 |
- Max sulfur content is 1.5% in designated areas. (since 1-07-2010 1% is max).
- The aluminium+silicon value is used to check for remains of the
catalyst after catalytic cracking. Most catalysts contains aluminium or
silicon and remains of catalyst can cause damage to the engine.
- The flash point of all fuels used in the engine room should be at
least 60°C.(apart from those gaseous fuels such as LPG/LNG which have
special class rules applied to the fuel systems)
Transportation
Fuel oil is transported worldwide by fleets of
oil tankers making deliveries to suitably sized strategic ports such as
Houston,
Singapore,
Fujairah,
Balboa,
Cristobal,
Algeciras and
Rotterdam. Where a convenient seaport does not exist, inland transport may be achieved with the use of
barges. The lighter fuel oils can also be transported through
pipelines. The major physical supply chains of Europe are along the
Rhine.
See also
References
- Bunker Pricing Methodologies
External links
Source: http://en.wikipedia.org/wiki/Fuel_oil
|
|