Detailed d
There are hundreds of different petroleum crude oil
sources worldwide and each crude oil has its own unique composition or assay. There are also hundreds of petroleum refineries
worldwide and each of them is designed to process either a specific crude oil
or specific types of crude oils. Naphtha is a general term as each refinery
produces its own naphthas with their own unique initial and final boiling
points and other physical and compositional characteristics.
Naphthas may also be produced
from other material such as coal tar, shale deposits, tar sands and the destructive
distillation of wood.
The major source of petroleum naphtha in a petroleum
refinery
The first unit process in a petroleum refinery is
the crude oil
distillation unit. The overhead liquid distillate from that unit is
called virgin or straight-run naphtha and that distillate is the
largest source of naphtha in most petroleum refineries. The naphtha is a
mixture of many different hydrocarbon compounds. It has an initial boiling point (IBP) of about
35 °C and a final boiling point (FBP) of about 200 °C, and it
contains paraffins, naphthenes (cyclic
paraffins) and aromatic hydrocarbons ranging
from those containing 4 carbon atoms to those containing
about 10 or 11 carbon atoms.
·
a virgin light naphtha with an IBP of about
30 °C and a FBP of about 145 °C containing most (but not all) of the
hydrocarbons with 6 or less carbon atoms
·
a virgin heavy naphtha containing most (but not all)
of the hydrocarbons with more than 6 carbon atoms. The heavy naphtha has an IBP
of about 140 °C and a FBP of about 205 °C.
It is the virgin heavy naphtha that is usually
processed in a catalytic reformer because the light naphtha has molecules with
6 or less carbon atoms which, when reformed, tend to crack into butane and lower
molecular weight hydrocarbons which are not useful as high-octane gasoline
blending components. Also, the molecules with 6 carbon atoms tend to form
aromatics which is undesirable because governmental environmental regulations
in a number of countries limit the amount of aromatics (most particularly benzene) that gasoline may
contain.
Types of virgin naphthas
The table below lists some typical virgin heavy
naphthas, available for catalytic reforming, derived from various crude oils.
It can be seen that they differ significantly in their content of paraffins,
naphthenes and aromatics:
Typical heavy naphthas
|
||||
Crude oil name
Location |
||||
Initial
boiling point, °C
|
149
|
140
|
149
|
150
|
Final
boiling point, °C
|
204
|
190
|
204
|
180
|
Paraffins,
liquid volume %
|
46
|
62
|
57
|
38
|
Naphthenes,
liquid volume %
|
42
|
32
|
27
|
45
|
Aromatics,
liquid volume %
|
12
|
6
|
16
|
17
|
Cracked naphthas
Some refinery naphthas also contain some olefinic hydrocarbons,
such as naphthas derived from the fluid catalytic
cracking, visbreakers and coking processes used in
many refineries. Those olefin-containing naphthas are often referred to as cracked naphthas.
In some (but not all) petroleum refineries, the
cracked naphthas are desulfurized and catalytically reformed (as are the virgin
naphthas) to produce additional high-octane gasoline components.
Other uses
Some petroleum refineries also produce small amounts
of specialty naphthas for use as solvents, cleaning fluids, paint and varnish
diluents, asphalt diluents, rubber
industry solvents, dry-cleaning, cigarette lighters, and portable camping stove
and lantern fuels. Those specialty naphthas are subjected to various
purification processes.
Sometimes the specialty naphthas are called petroleum ether, petroleum spirits, mineral spirits, paraffin, benzine, hexanes, ligroin, white oil or white
gas, painters naphtha, refined solvent naphtha and Varnish
makers' & painters' naphtha (VM&P) . The best way to determine the
boiling range and other compositional characteristics of any of the specialty
naphthas is to read the Safety Data Sheet (SDS) for the
specific naphtha of interest.
On a much larger scale, petroleum naphtha is also
used in the petrochemicals industry as
feedstock to steam reformers and steam crackers for the production
of hydrogen (which may be and is
converted into ammonia for fertilizers), ethylene and other olefins.
Natural gas is also used as feedstock to steam reformers and steam crackers.
PRICE
$460376.21/KG OR $209261.91/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
e-mail: emeabau@yahoo.com
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