Hello, nicki61-ga!
Thank you for an interesting question that will prompt me to learn
something new as well. I am also a layman concerning this subject, so
we can go on this journey together!!
Overview of Oil Refinery Products
**********************************
See "Refinery Output and Final Products" at
http://www.lmoga.com/refoutput.htm
This chart shows the products which are refined out of crude oil, as
well as their "refinery yield per barrel" percentage. It also depicts
many of the products made out of crude oil.
The Chevron Company has compiled a good overview of the oil refinery
process, written in terms that laymen like you and I can understand!!!
I have excerpted most of the information from the Chevron website
below:
What is a Refinery?
*******************
http://www.chevron.com/about/learning_center/refinery/
..a refinery takes a raw material--crude oil--and transforms it into
gasoline and hundreds of other useful products.
A typical large refinery costs billions of dollars to build and
millions more to maintain and upgrade. It runs around the clock 365
days a year, employs between 1,000 and 2,000 people and occupies as
much land as several hundred football fields. It's so big and
sprawling, in fact, that workers ride bicycles from one station to
another.
..Essentially, refining breaks crude oil down into its various
components, which then are selectively reconfigured into new products.
This process takes place inside a maze of hardware that one observer
has likened to "a metal spaghetti factory." Employees regulate
refinery operations from within highly automated control rooms.
Because so much activity happens out of sight, refineries are
surprisingly quiet places. The only sound most visitors hear is the
constant, low hum of heavy equipment.
The complexity of this equipment varies from one refinery to the next.
In general, the more sophisticated a refinery, the better its ability
to upgrade crude oil into high-value products. Whether simple or
complex, however, all refineries perform three basic steps:
separation, conversion and treatment.
The Separation Process
**********************
Modern separation involves piping oil through hot furnaces. The
resulting liquids and vapors are discharged into distillation towers,
the tall, narrow columns that give refineries their distinctive
skylines.
Inside the towers, the liquids and vapors separate into components or
fractions according to weight and boiling point. The lightest
fractions, including gasoline and liquid petroleum gas (LPG), vaporize
and rise to the top of the tower, where they condense back to liquids.
Medium weight liquids, including kerosene and diesel oil distillates,
stay in the middle. Heavier liquids, called gas oils, separate lower
down, while the heaviest fractions with the highest boiling points
settle at the bottom. These tarlike fractions, called residuum, are
literally the "bottom of the barrel."
The fractions now are ready for piping to the next station or plant
within the refinery. Some components require relatively little
additional processing to become asphalt base or jet fuel. However,
most molecules that are destined to become high-value products require
much more processing.
Conversion Processes that crack and/or rearrange molecules
***********************************************************
This is where refining's fanciest footwork takes place--where
fractions from the distillation towers are transformed into streams
(intermediate components) that eventually become finished products.
This also is where a refinery makes money, because only through
conversion can most low-value fractions become gasoline.
The most widely used conversion method is called cracking because it
uses heat and pressure to "crack" heavy hydrocarbon molecules into
lighter ones. A cracking unit consists of one or more tall,
thick-walled, bullet-shaped reactors and a network of furnaces, heat
exchangers and other vessels.
Fluid catalytic cracking: (gasoline)
...."cat cracking," is the basic gasoline-making process. Using
intense heat (about 1,000 degrees Fahrenheit), low pressure and a
powdered catalyst (a substance that accelerates chemical reactions),
the cat cracker can convert most relatively heavy fractions into
smaller gasoline molecules.
Hydrocracking: (mostly gasoline and jet fuel)
.. applies the same principles but uses a different catalyst, slightly
lower temperatures, much greater pressure and hydrogen to obtain
chemical reactions. Although not all refineries employ hydrocracking,
Chevron is an industry leader in using this technology to
cost-effectively convert medium- to heavyweight gas oils into
high-value streams. The company's patented hydrocracking process,
which takes place in the Isocracker unit, produces mostly gasoline and
jet fuel.
Cokers: (industrial fuel)
..use heat and moderate pressure to turn residuum into lighter
products and a hard, coallike substance that is used as an industrial
fuel.
Alkylation: (gasoline components)
..makes gasoline components by combining some of the gaseous
byproducts of cracking...a process, which essentially, is cracking in
reverse.
Reforming: (high-octane gasoline components)
..uses heat, moderate pressure and catalysts to turn naphtha, a light,
relatively low-value fraction, into high-octane gasoline components.
A simplified Refinery Drawing
*******************************
http://www.chevron.com/about/learning_center/refinery/chart.shtml
"From crude to crayons"
************************
http://www.chevron.com/about/learning_center/refinery/crayon.shtml
"Modern refineries can turn more than half of every barrel of crude
oil into gasoline. The rest of that barrel has many uses, including
being sold to special manufacturers for further processing. Following
are just a few products that get their start in a refinery:"
ammonia
antiseptics
bubble gum
crayons
denture adhesive
eyeglass frames
fertilizer
floor polish
guitar strings
heart valves
ice chests
insect repellant
life preservers
liquid detergent
mascara
paint
pingpong paddles
plastic beverage containers
roller-skate wheels
sneakers
synthetic fibers
telephones
tobacco pouches
volleyballs
Another simple overview of oil refining from the Mobil Website
**************************************************************
http://www.mobil1.com/index.jsp
The following information is taken from the Mobil site:
"Petroleum crude, as it comes out of the ground, is made up of rings
and chains of carbon and hydrogen molecules of different shapes and
lengths. These various components have different boiling points, and
therefore they can be separated through a process called fractional
distillation."
"Heating the crude oil with superheated steam to temperatures greater
than 1,112º F (600º C) causes the mixture to boil, forming a vapor.
The vapor enters the bottom of a long column and rises, passing
through condensing trays. Components with high boiling points will
condense and are collected on the lowest trays while short carbon
chains with low boiling points will collect on the cooler upper
trays."
Further Processing
******************
"Few of the components coming out of the fractional distillation
column are ready for market. They must be chemically processed to
create other base stocks. For example, gasoline is one of the major
products made by oil companies. Yet, only 40 percent of distilled
crude oil becomes gasoline. Instead of continually distilling large
quantities of crude oil, oil companies chemically process components
from the distillation column to increase the yield of popular
materials like gasoline."
Chemical processing can take place three ways:
**********************************************
Cracking large hydrocarbon chains into smaller ones.
Unifying smaller chains into larger ones.
Altering chains to make them into something else.
"The chemically processed compounds are treated to remove impurities,
such as organic compounds containing sulfur, nitrogen, oxygen, water,
dissolved metals and inorganic salts. Treating is done by passing the
compounds through:
A column of sulfuric acid, which removes unsaturated hydrocarbons
(those with carbon-carbon double bonds), nitrogen compounds, oxygen
compounds and residual solids (such as tars and asphalt).
An absorption column filled with drying agents to remove water.
Sulfur treatment and hydrogen-sulfide scrubbers to remove sulfur and
sulfur compounds.
End Products
************
After the compounds have been treated, they are cooled and then
blended together to make products such as:
Gasoline of various grades.
Lubricating oils of various grades (e.g., 10W-30, 5W-30).
Kerosene.
Jet fuel.
Diesel fuel.
Heating oil.
Chemicals for making plastics and other polymer materials.
Some excerpts from the Irving Oil Refining Website
**************************************************
http://www.irvingoilco.com/refining/ref_index.html
What a Refinery Does:
"The refinery's purpose is simple: to take crude oil, which is
virtually useless in its natural state,......and breaking the crude
oil down into its individual components; called "fractions", then
making these into useful products.
The Process:
"First the crude oil is heated to temperatures up to 371 degrees
celsius in large furnaces. This process is called fractionation.
Lighter components, such as gasoline, vaporize first and rise to the
top. Heavier components, such as diesel fuel, collect on trays lower
down the tower and are drawn off there. Finally what remains at the
bottom looks rather like tar. It's too heavy to vaporize, so it's
heated to even higher temperatures. At 427 degrees celsius it
separates into components such as heavy fuel oil and asphalt."
The goal:
... is to get the cleanest-burning gasoline and lowest-sulphur fuel
oils and to convert as much of the crude oil as possible into high
value products. The first processes involve breaking up - or cracking
- and reorganizing the large hydrocarbon molecules that come out of
the distillation process... Finally, there's blending; this is where
stocks from the various processes are mixed according to special
formulas to make products with specific characteristics.
Reference to the term "Naphta"
******************************
From "How is Gas Produced?"
http://www.earlham.edu/~chem/pages/gasoline/produced.html
"The crude oil is heated to 370 degrees to 470 degrees Celsius,
pumped into a fractioning tower, and separated into the following
major fractions. Because they are naturally occurring fractions of
crude oil, the naphtha fractions obtained by distillation are called
virgin naphtha, or straight run gasoline. Both the amounts of these
naphthas and their hydrocarbon compositions depend on the type of
crude oil being distilled. Thus, straight run gasolines differ widely
in such properties as specific gravity, vaporization characteristics,
and antiknock quality. The light naphtha fraction is usually of
sufficiently high ON to be used as a component of finished gasoline
without any more refining than is needed to remove undesirable
impurities. The heavy naphtha is catalytically reformed to
higher-octane blending stock. The kerosene and light gas-oil
fractions, referred to collectively as middle distillates, are used in
the production of kerosene, jet fuel, diesel fuel, and furnace oils.
The heavy gas-oil fraction may be used in heavy diesel fuel,
industrial fuel oil, and bunker oil."
Additional Reading
******************
"Petroleum Energy." Energy Information Administration
http://www.eia.doe.gov/kids/non-renewable/oil.html
(An extremely comprehensive site, written in simple terms, with
numerous of links.)
For a picture of Hovensa's Fluid Catalytic Cracking Unit!!!!:
http://www.hess.com/hovensa/fcc-day.htm
Well, I must say that I learned quite a bit from my research. It will
still take a bit of study to get some of these terms embedded in your
brain (and mine!)....like "hydrocracking" and "naphta"...but I believe
the above references do a good job of presenting this informtion in
laymen's terms.
If you need further clarification, or any of the links don't work
properly, please let me know.
Thanks again for your interesting question!
umiat
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