U.S. patent application number 12/616547 was filed with the patent office on 2010-05-13 for systems and methods for producing n-paraffins from low value feedstocks.
This patent application is currently assigned to KELLOGG BROWN & ROOT LLC. Invention is credited to Faisal Mohmand, Kiran V. Shah, Anand Subramanian, Eric Wong.
Application Number | 20100116711 12/616547 |
Document ID | / |
Family ID | 42164223 |
Filed Date | 2010-05-13 |
United States Patent
Application |
20100116711 |
Kind Code |
A1 |
Wong; Eric ; et al. |
May 13, 2010 |
Systems and Methods for Producing N-Paraffins From Low Value
Feedstocks
Abstract
Systems and methods for producing n-paraffins are provided. The
method can include hydroprocessing at least a portion of a kerosene
fraction recovered from a thermally cracked hydrocarbon product to
produce a hydroprocessed kerosene product comprising n-paraffins.
The n-paraffins can be separated from the hydroprocessed kerosene
product to produce an n-paraffins product.
Inventors: |
Wong; Eric; (Houston,
TX) ; Subramanian; Anand; (Sugar Land, TX) ;
Shah; Kiran V.; (Sugar Land, TX) ; Mohmand;
Faisal; (Sugar Land, TX) |
Correspondence
Address: |
KELLOGG BROWN & ROOT LLC;ATTN: Christian Heausler
4100 Clinton Drive
HOUSTON
TX
77020
US
|
Assignee: |
KELLOGG BROWN & ROOT
LLC
Houston
TX
|
Family ID: |
42164223 |
Appl. No.: |
12/616547 |
Filed: |
November 11, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61113935 |
Nov 12, 2008 |
|
|
|
Current U.S.
Class: |
208/26 ;
196/14.5; 208/27 |
Current CPC
Class: |
C10G 69/06 20130101;
C10G 67/04 20130101; C10G 67/06 20130101 |
Class at
Publication: |
208/26 ;
196/14.5; 208/27 |
International
Class: |
C10G 57/00 20060101
C10G057/00; C10G 73/02 20060101 C10G073/02 |
Claims
1. A method for producing n-paraffins, comprising: hydroprocessing
at least a portion of a kerosene fraction recovered from a
thermally cracked hydrocarbon product to produce a hydroprocessed
kerosene product comprising n-paraffins; and separating the
n-paraffins from the hydroprocessed kerosene product to produce an
n-paraffins product.
2. The method of claim 1, wherein the kerosene fraction is
hydroprocessed in the presence of hydrogen and one or more
catalysts at a temperature of from about 200.degree. C. to about
420.degree. C. and a pressure of from about 3,000 kPa to about
8,000 kPa.
3. The method of claim 1, wherein the hydroprocessed kerosene
fraction further comprises at least 1 ppmw nitrogen-containing
compounds.
4. The method of claim 1, wherein the hydroprocessed kerosene
fraction has a bromine index of at least 10.
5. The method of claim 1, wherein the hydroprocessed kerosene
fraction further comprises at least 1 ppmw sulfur-containing
compounds.
6. The method of claim 1, wherein a kerosene fraction recovered
from an atmospheric distillation unit is mixed with at least one of
the thermally cracked hydrocarbon product and the hydroprocessed
kerosene product.
7. The method of claim 1, wherein separating the n-paraffins
comprises an adsorption process, a solvent extraction process, a
distillation process, or any combination thereof.
8. The method of claim 1, wherein separating the n-paraffins
comprises an adsorption process comprising: contacting the
hydroprocessed kerosene product with a first adsorbent material at
conditions sufficient to cause the first adsorbent material to
adsorb at least a portion of the n-paraffins; contacting the
adsorbed n-paraffins with a displacing medium at conditions
sufficient to cause at least a portion of the adsorbed n-paraffins
to be desorbed; and recovering the desorbed n-paraffins as the
n-paraffins product.
9. The method of claim 8, wherein the recovered n-paraffins
comprise one or more impurities, and wherein the adsorption process
further comprises contacting the recovered n-paraffins with a
second adsorbent material at conditions sufficient to cause the
second adsorbent material to adsorb at least a portion of the one
or more impurities to produce an n-paraffins product having a
reduced concentration of impurities relative to the recovered
n-paraffins.
10. The method of claim 9, wherein the impurities comprise aromatic
hydrocarbons, and wherein the n-paraffins product has a
concentration of less than about 100 ppmw aromatics.
11. The method of claim 1, further comprising: introducing an
atmospheric distillation tower bottoms, a vacuum distillation tower
bottoms, or a combination thereof to a thermal cracker to produce
the thermally cracked hydrocarbon product; and separating the
thermally cracked hydrocarbon product to produce a light
hydrocarbon fraction, a heavy hydrocarbon fraction, and the
kerosene fraction.
12. A method for producing n-paraffins, comprising: thermally
cracking a hydrocarbon feed to produce a thermally cracked
hydrocarbon mixture; selectively separating a kerosene fraction
from the hydrocarbon mixture; hydroprocessing at least a portion of
the kerosene fraction to produce a hydroprocessed kerosene
comprising n-paraffins, less than about 500 ppmw sulfur-containing
compounds, and less than about 200 ppmw nitrogen-containing
compounds; and separating the n-paraffins from the hydroprocessed
kerosene product to produce an n-paraffins product.
13. The method of claim 12, wherein the hydroprocessed kerosene
comprises at least 1 ppmw nitrogen-containing compounds and at
least 1 ppmw sulfur-containing compounds.
14. The method of claim 12, wherein the kerosene fraction has a
bromine index of at least 10.
15. The method of claim 12, wherein the hydrocarbon feed comprises
atmospheric distillation tower bottoms, vacuum distillation tower
bottoms, or a combination thereof.
16. The method of claim 12, wherein separating the n-paraffins
comprises an adsorption process, a solvent extraction process, a
distillation process, or any combination thereof.
17. A system for producing n-paraffins, comprising: a
hydroprocessing unit for hydroprocessing at least a portion of a
kerosene fraction recovered from a thermally cracked hydrocarbon
product to produce a hydroprocessed kerosene product comprising
n-paraffins; and a first separation unit for separating the
n-paraffins from the hydroprocessed kerosene product to produce an
n-paraffins product.
18. The system of claim 17, further comprising a thermal cracking
unit for thermally cracking a hydrocarbon feed to produce the
thermally cracked hydrocarbon product; and a second separation unit
for separating the thermally cracked hydrocarbon product to produce
a light hydrocarbon fraction, a heavy hydrocarbon fraction, and the
kerosene fraction.
19. The system of claim 17, wherein the first separation unit
comprises one or more adsorption/desorption units.
20. The system of claim 17, further comprising a third separation
unit for purifying the n-paraffins product to produce an
n-paraffins product comprising about 99 wt % or more n-paraffins.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application having Ser. No. 61/113,935, filed on Nov. 12,
2008, which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to
systems and methods for producing normal paraffins or linear
paraffins ("n-paraffins") from low value feedstocks. More
particularly, embodiments of the present invention relate to
systems and methods for producing n-paraffins from a kerosene
fraction recovered from a thermally cracked hydrocarbon.
[0004] 2. Description of the Related Art
[0005] N-paraffins are traditionally produced from a high quality
kerosene fraction of crude oil that is recovered from an
atmospheric distillation unit ("ADU"). Such kerosene fraction is
referred to as "straight-run kerosene." The n-paraffins product
separated from straight-run kerosene is often converted to linear
alkyl benzenes ("LAB") and used in the production of detergents.
Other uses of n-paraffins include chlorinated paraffins and
secondary alkane sulfonates ("SAS"). The n-paraffins product can
also be further purified and processed for use in higher quality
products, such as cosmetics, food-grade products, and specialty
lubes.
[0006] Conventional n-paraffins production processes must meet
strict processing conditions in order to separate the n-paraffins
from the straight-run kerosene. One particular processing condition
that must be met is the concentration level of impurities allowed
in the kerosene fraction must be low in order to separate the
n-paraffins therefrom. For example, nitrogen-containing compounds
(an impurity) must be reduced to a concentration below 1 ppmw in
order to meet the contaminant specifications of the process
required to separate the n-paraffins from the straight-run
kerosene. In order to reduce the amount of impurities to required
levels, the straight-run kerosene frequently requires severe
hydrotreating. Therefore, not only are n-paraffins produced from an
expensive hydrocarbon feed, i.e. straight-run kerosene, the
hydroprocessing conditions require special equipment and is
expensive to construct, operate, and maintain.
[0007] There is a need, therefore, for improved systems and methods
for producing n-paraffins from low value feedstocks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] So that the recited features of the present invention can be
understood in detail, a more particular description of the
invention may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0009] FIG. 1 depicts an illustrative n-paraffins production
system, according to one or more embodiments described.
[0010] FIG. 2 depicts an illustrative n-paraffins recovery system,
according to one or more embodiments described.
[0011] FIG. 3 depicts an illustrative n-paraffins purification
system, according to one or more embodiments described.
DETAILED DESCRIPTION
[0012] A detailed description will now be provided. Each of the
appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the
various elements or limitations specified in the claims. Depending
on the context, all references below to the "invention" may in some
cases refer to certain specific embodiments only. In other cases it
will be recognized that references to the "invention" will refer to
subject matter recited in one or more, but not necessarily all, of
the claims. Each of the inventions will now be described in greater
detail below, including specific embodiments, versions and
examples, but the inventions are not limited to these embodiments,
versions or examples, which are included to enable a person having
ordinary skill in the art to make and use the inventions, when the
information in this patent is combined with publicly available
information and technology.
[0013] Systems and methods for producing n-paraffins are provided.
The method can include hydroprocessing at least a portion of a
kerosene fraction recovered from a thermally cracked hydrocarbon
product to produce a hydroprocessed kerosene product comprising
n-paraffins. The n-paraffins can be separated from the
hydroprocessed kerosene product to produce an n-paraffins
product.
[0014] FIG. 1 depicts an illustrative n-paraffins production system
100, according to one or more embodiments. The n-paraffins
production system 100 can include, but is not limited to, one or
more thermal cracking units 105, one or more hydroprocessing units
115, one or more n-paraffins recovery units 120, and one or more
n-paraffins purification units 130. A hydrocarbon feed via line 103
can be introduced to the thermal cracking unit 105 to produce one
or more thermally cracked hydrocarbon products (three are shown
107, 109, and 111). The thermally cracked hydrocarbon products can
include, but are not limited to, a light hydrocarbon fraction via
line 107, a heavy hydrocarbon fraction via line 109, and a kerosene
fraction via line 111. In one or more embodiments, at least a
portion of the kerosene fraction via line 111 and a hydrogen
containing feed via line 113 can be introduced to the
hydroprocessing unit 115 to produce an overhead or off gas via line
117 and a hydroprocessed kerosene product via line 119. The
hydroprocessing unit 115 can convert olefins to n-paraffins and/or
reduce the concentration of sulfur, nitrogen, and/or
oxygen-containing compounds and other impurities contained in the
kerosene fraction in line 111. As such, the hydroprocessed kerosene
in line 119 can have a reduced concentration of impurities, such as
sulfur and nitrogen-containing compounds, and an increased amount
of n-paraffins relative to the kerosene fraction in line 111. The
hydroprocessed kerosene via line 119 can be introduced to the
n-paraffins recovery unit 120 to provide a kerosene raffinate via
line 121 and an n-paraffins product via line 123.
[0015] The hydrocarbon feed in line 103 can include any hydrocarbon
or combination of hydrocarbons containing n-paraffins. For example,
the hydrocarbon feed in line 103 can include one or more heavy
and/or low value hydrocarbons. Illustrative hydrocarbon feeds in
line 103 can include, but are not limited to, residues from the
atmospheric and/or vacuum distillation of petroleum crudes, crude
oils, heavy oils, visbroken resids, tars, coal liquids, oil shales,
oil sands, bitumens, waste oils, fractions thereof, derivatives
thereof, and combinations thereof.
[0016] In one or more embodiments, a second hydrocarbon feed via
line 106 can be introduced to the hydrocarbon feed in line 103, the
kerosene fraction in line 111, and/or the hydroprocessed kerosene
in line 119. The second hydrocarbon feed in line 106 can include
straight-run kerosene provided from an atmospheric distillation
unit, for example. In another embodiment, the second hydrocarbon
feed in line 106 can include n-paraffins having from 8 to 20 carbon
atoms. The second hydrocarbon feed in line 106 can have a
concentration of n-paraffins having from 10 to 14 carbon atoms
ranging from a low of about 10 wt %, about 15 wt %, or about 20 wt
% to a high of about 30 wt %, about 35 wt %, or about 40 wt %. The
second hydrocarbon feed in line 106 can have a concentration of
sulfur-containing compounds ranging from a low of about 50 ppmw,
about 60 ppmw, or about 80 ppmw to a high of about 115 ppmw, about
130 ppmw, or about 150 ppmw. The second hydrocarbon in line 106 can
have a concentration of nitrogen-containing compounds ranging from
a low of about 1 ppmw, about 2 ppmw, or about 3 ppmw to a high of
about 5 ppmw, about 10 ppmw, or about 15 ppmw.
[0017] The composition or make-up of the hydrocarbon feed in line
103, with or without addition of the second hydrocarbon in line
106, can include, but is not limited to, paraffins, olefins,
aromatics, and one or more impurities, such as sulfur-containing
compounds, nitrogen-containing compounds, oxygen-containing
compounds, heavy metals, e.g. nickel and vanadium, and the like.
The hydrocarbon feed in line 103 can have a concentration of
paraffins ranging from a low of about 5 wt % to a high of about 90
wt %. The hydrocarbon feed in line 103 can have a concentration of
n-paraffins having from 10 to 14 carbon atoms ranging from a low of
about 5 wt %, about 10 wt %, or about 15 wt % to a high of about 25
wt %, about 30 wt %, or about 35 wt %. The hydrocarbon feed in line
103 can have a concentration of olefins ranging from a low of about
5 wt %, about 10 wt %, or about 15 wt % to a high of about 20 wt %,
about 25 wt %, or about 30 wt %. The aromatics can include, but are
not limited to, monocyclic aromatics, such as alkyl-substituted
benzenes, tetralins, alkyl-substituted tetralins, indanes, and
alkyl-substituted indanes; and bicyclic aromatics, such as
naphthalenes, biphenyls, and acenaphthenes. The hydrocarbon feed in
line 103 can have a concentration of aromatics ranging from a low
of about 1 wt %, about 3 wt %, or about 5 wt % to a high of about
10 wt %, about 20 wt %, or about 30 wt %. The sulfur-containing
compounds can include, but are not limited to, mercaptans,
sulfides, thiophenes, and combinations thereof. The hydrocarbon
feed in line 103 can have a concentration of sulfur-containing
compounds ranging from a low of about 2 ppmw, about 100 ppmw, or
about 500 ppmw to a high of about 10,000 ppmw, about 20,000 ppmw,
or about 30,000 ppmw. The nitrogen-containing compounds can
include, but are not limited to, indoles, quinolines, pyridines,
and combinations thereof. The hydrocarbon feed in line 103 can have
a concentration of nitrogen-containing compounds ranging from a low
of about 1 ppmw, about 50 ppmw, or about 100 ppmw to a high of
about 600 ppmw, about 700 ppmw, or about 800 ppmw. The
oxygen-containing compounds, i.e. heteroatom containing compounds,
can include, but are not limited to, phenolics. The hydrocarbon
feed in line 103 can have a concentration of oxygen-containing
compounds ranging from a low of about 10 ppmw, about 50 ppmw, or
about 100 ppmw to a high of about 1,000 ppmw, about 3,000 ppmw, or
about 5,000 ppmw.
[0018] The second hydrocarbon in line 106, if added, can be mixed
or blended with the hydrocarbon feed in line 103, the kerosene
fraction in line 111, and/or the hydroprocessed kerosene in line
119 in any desired amount or ratio. For example, the second
hydrocarbon via line 106 can be introduced to the hydroprocessed
kerosene in line 119 to provide a hydrocarbon mixture having
nitrogen-containing compounds ranging from a low of about 5 ppmw,
about 10 ppmw, or about 15 ppmw to a high of about 60 ppmw, about
80 ppmw, or about 100 ppmw. As such, the volume or weight ratio of
the second hydrocarbon in line 106 to the hydroprocessed kerosene
in line 119 can depend, at least in part, on the desired level or
concentration of nitrogen-containing compounds. Other compounds
that can be used to determine the amount of the second hydrocarbon
in line 106 that can be introduced to the hydroprocessed kerosene
in line 119 can include, but are not limited to, the concentration
of sulfur-containing compounds, n-paraffins, oxygen-containing
compounds, aromatics, and any combination thereof. Similarly, the
amount of the second hydrocarbon introduced to the hydrocarbon feed
in line 103 and/or the kerosene fraction in line 111 can depend, at
least in part, on a desired level or concentration of one or more
compounds for that particular feed in the n-paraffins production
process 100.
[0019] In one or more embodiments, at least a portion of the
kerosene fraction in line 111 can bypass the hydroprocessing unit
115 via line 112 and can be introduced to the hydroprocessed
kerosene in line 119 and/or directly to the n-paraffins recovery
unit 120. For example, about 5 wt %, about 10 wt %, about 20 wt %,
about 30 wt %, about 40 wt %, or about 50 wt % of the kerosene
fraction in line 111 can bypass via line 112 the hydroprocessing
unit 115 and can be introduced to the hydroprocessed kerosene in
line 119 or directly to the n-paraffins recovery unit 120. In one
or more embodiments, the portion or amount of the kerosene fraction
via line 112 that can bypass the hydroprocessing unit 115 can
depend, at least in part, on the amount of straight-run kerosene in
line 106 and/or the concentrations of impurities in the kerosene
fraction in line 111 and/or the concentrations of impurities that
can be present in the hydroprocessed kerosene in line 119.
[0020] The thermal cracking process carried out in the one or more
thermal crackers 105 can convert the hydrocarbon feed introduced
via line 103 to coke and lighter hydrocarbons, which include the
kerosene fraction recovered via line 111. The thermal cracking unit
105 can include any thermal cracker suitable for thermally cracking
the hydrocarbon feed introduced via line 103. Illustrative thermal
cracking units 105 can include, but are not limited to, cokers,
visbreakers, or any other thermal crackers, and combinations
thereof. Cokers can include delayed cokers, fluid cokers, and/or
flexicokers. Visbreakers can include coil or furnace visbreakers
and/or soaker visbreakers.
[0021] The kerosene fraction recovered via line 111 from the
thermal cracking unit 105, with or without addition of the second
hydrocarbon in line 106, can contain a variety of different
hydrocarbon compounds and impurities. For example, the kerosene
fraction in line 111 can include, but is not limited to, paraffins,
olefins, aromatics, and impurities such as sulfur-containing
compounds, nitrogen-containing compounds, oxygen-containing
compounds, water, and combinations thereof. The kerosene fraction
in line 111 can include a mixture of hydrocarbons having from about
1 to about 80 carbon atoms. For example, the kerosene fraction in
line 111 can include a mixture of hydrocarbons having from about 1
to about 50, about 1 to about 60, or about 1 to about 70 carbon
atoms.
[0022] The kerosene fraction in line 111 can have a concentration
of paraffins ranging from a low of about 5 wt % to a high of about
30 wt %. The kerosene fraction in line 111 can have a concentration
of n-paraffins having from 10 to 14 carbon atoms ranging from a low
of about 5 wt %, about 7 wt %, or about 8 wt % to a high of about
15 wt %, about 20 wt %, or about 25 wt %. In at least one specific
embodiment, the kerosene fraction in line 111 can have a
concentration of n-paraffins having from 10 to 14 carbon atoms of
about 10 wt %, about 11 wt %, about 12 wt %, about 13 wt %, or
about 14 wt %. The kerosene fraction in line 111 can have a
concentration of olefins ranging from a low of about 5 wt %, about
10 wt %, or abut 15 wt % to a high of about 20 wt %, about 25 wt %,
or about 30 wt %. The kerosene fraction in line 111 can have a
concentration of aromatics ranging from a low of about 1 wt %,
about 3 wt % or about 5 wt % to a high of about 10 wt %, about 20
wt % or about 30 wt %. The kerosene fraction in line 111 can have a
concentration of sulfur-containing compounds ranging from a low of
about 2 ppmw, about 100 ppmw, or about 500 ppmw to a high of about
10,000 ppmw, about 20,000 ppmw, or about 30,000 ppmw. The kerosene
fraction in line 111 can have a concentration of
nitrogen-containing compounds ranging from a low of about 1 ppmw,
about 50 ppmw, or about 100 ppmw to a high of about 600 ppmw, about
700 ppmw, or about 800 ppmw. The kerosene fraction in line 111 can
have a concentration of oxygen-containing compounds ranging from a
low of about 10 ppmw, about 50 ppmw, or about 100 ppmw to a high of
about 1,000 ppmw, about 3,000 ppmw, or about 5,000 ppmw. The
kerosene fraction in line 111 can have a concentration of water
ranging from a low of about 10 ppmw, about 50 ppmw, or about 100
ppmw to a high of about 200 ppmw, about 300 ppmw, or about 400
ppmw.
[0023] In one or more embodiments, about 90 vol % of the kerosene
fraction in line 111 can be distilled at a temperature of from
about 205.degree. C. to about 300.degree. C., as determined
according to ASTM D-86. In one or more embodiments, about 10 vol %
of the kerosene fraction in line 111 can be distilled or vaporized
at a temperature of from about 155.degree. C. to about 165.degree.
C. In one or more embodiments, about 50 vol % of the kerosene
fraction in line 111 can be distilled or vaporized at a temperature
of from about 210.degree. C. to about 230.degree. C. In one or more
embodiments, about 90 vol % of the kerosene fraction in line 111
can be distilled or vaporized at a temperature of from about
255.degree. C. to about 275.degree. C. The kerosene fraction in
line 111 can have a bromine index ranging from about 5 to about
400, as measured according to ASTM D-1159. For example, the
kerosene fraction in line 119 can have a bromine index ranging from
a low of about 5, about 10, or about 15 to a high of about 50,
about 100, or about 200. In at least one specific embodiment, the
kerosene fraction in line 111 can have a bromine index of at least
20, at least 40, at least 60, at least 80, or at least 100.
[0024] The light hydrocarbon fraction via line 107 and the heavy
hydrocarbon fraction via line 109 can be further processed, blended
with other hydrocarbon feeds or hydrocarbon feedstocks, used as a
source of fuel, or the like. For example, the light hydrocarbon
fraction via line 107 can be separated to provide naphtha. The
heavy hydrocarbon fraction via line 109 can be recycled to the
hydrocarbon feed in line 103. In another example the heavy
hydrocarbon fraction via line 109 can be separated to provide coke,
bunker oil, fuel oil, heavy gas oil, and the like.
[0025] As discussed above, the kerosene fraction via line 111 can
be introduced to the one or more hydrocarbon processing units 115
to provide the hydroprocessed kerosene via line 119 and the off-gas
via line 117. The one or more hydroprocessing units 115 can include
any system, device, or combination of systems and/or devices
suitable for reducing the sulfur and nitrogen concentration of the
kerosene fraction introduced via line 111 by converting sulfur and
sulfur compounds to hydrogen sulfide ("H.sub.2S") and nitrogen and
nitrogen compounds to ammonia ("NH.sub.3"), for example. The
hydroprocessing unit 115 can be or include a hydrotreating unit, a
hydrocracking unit, or a combination thereof. At least a portion of
the converted sulfur and nitrogen compounds and other impurities,
such as converted oxygen-containing compounds, hydrogen, and other
light gases, can be removed as the off-gas via line 117. At least a
portion of the olefins contained in the kerosene fraction
introduced via line 111 can be converted to n-paraffins to produce
a hydroprocessed kerosene product via line 119 enriched in
n-paraffins relative to the kerosene fraction in line 111. In one
or more embodiments, the amount of olefins contained in the
kerosene fraction in line 111 that can be converted to n-paraffins
can range from a low of about 5% to a high of about 100 wt %.
[0026] The hydroprocessed kerosene in line 119, with or without the
addition of the second hydrocarbon in line 106, can include the
following components and amounts thereof. The hydroprocessed
kerosene in line 119 can have a concentration of paraffins ranging
from a low of about 5 wt % to a high of about 95 wt %. The
concentration of n-paraffins having 10 to 14 carbon atoms in line
119 can range from a low of about 20 wt %, about 22 wt %, about 24
wt %, or about 26 wt % to a high of about 27 wt %, about 30 wt %,
about 33 wt %, or about 35 wt %. In at least one specific
embodiment, the concentration of n-paraffins having 10 to 14 carbon
atoms in line 119 can be at least 25 wt %, at least 30 wt %, at
least 35 wt %, or at least 40 wt %. The hydroprocessed kerosene in
line 119 can have a concentration of olefins ranging from a low of
about 0 wt %, about 1 wt %, or about 3 wt % to a high of about 5 wt
%, about 7 wt %, or about 10 wt %. The hydroprocessed kerosene in
line 119 can have a concentration of aromatics ranging from a low
of about 1 wt % to a high of about 10 wt %. The hydroprocessed
kerosene in line 119 can have a concentration of sulfur-containing
compounds ranging from a low of about 1 ppmw or less, about 5 ppmw,
about 10 ppmw, about 20 ppmw, about 50 ppmw, or about 100 ppmw to a
high of about 250 ppmw, about 400 ppmw, or about 500 ppmw. In at
least one specific embodiment, the concentration of
sulfur-containing compounds in line 119 can be at least 1 ppmw, at
least 2 ppmw, at least 3 ppmw, at least 5 ppmw, at least 10 ppmw,
at least 15 ppmw, at least 20 ppmw, or at least 25 ppmw. In at
least one specific embodiment, the concentration of
sulfur-containing compounds in line 119 can be at least 30 ppmw, at
least 40 ppmw, at least 50 ppmw, at least 100 ppmw, at least 200
ppmw, or at least 250 ppmw. The hydroprocessed kerosene in line 119
can have a concentration of nitrogen-containing compounds ranging
from a low of about 1 ppmw or less, about 5 ppmw, about 10 ppmw, or
about 15 ppmw to a high of about 80 ppmw, about 150 ppmw, or about
200 ppmw. In at least one specific embodiment, the concentration of
nitrogen-containing compounds in line 119 can be at least 1 ppmw,
at least 2 ppmw, at least 3 ppmw, at least 5 ppmw, at least 10
ppmw, at least 15 ppmw, at least 20 ppmw, or at least 25 ppmw. In
at least one specific embodiment, the concentration of
nitrogen-containing compounds in line 119 can be at least 30 ppmw,
at least 40 ppmw, at least 50 ppmw, or at least 55 ppmw. In one or
more embodiments, the hydroprocessed kerosene in line 119 can have
a concentration of sulfur-containing compounds of from about 50
ppmw to about 400 ppmw and a concentration of nitrogen containing
compound of from about 5 ppmw to about 80 ppmw. The concentration
of oxygen-containing compounds in line 119 can range from a low of
about 10 ppmw, about 30 ppmw, or about 50 ppmw to a high of about
200 ppmw, about 400 ppmw or about 600 ppmw. In at least one
specific embodiment, the concentration of oxygen-containing
compounds in line 119 can be at least 50 ppmw, at least 75 ppmw, at
least 100 ppmw, or at least 125 ppmw. The hydroprocessed kerosene
in line 119 can have a concentration of water ranging from a low of
about 0 ppmw, about 5 ppmw, about 10 ppmw, about 50 ppmw, or about
100 ppmw to a high of about 150 ppmw, about 175 ppmw, or about 200
ppmw. In at least one specific embodiment, the concentration of
water in line 119 can be at least 10 ppmw, at least 25 ppmw, at
least 50 ppmw, at least 100 ppmw, or at least 150 ppmw.
[0027] The hydroprocessed kerosene in line 119 can have a bromine
index ranging from about 5 to about 220. For example, the
hydroprocessed kerosene in line 119 can have a bromine index
ranging from a low of about 10, about 25, or about 50 to a high of
about 100, about 150, or about 175. In at least one specific
embodiment, the hydroprocessed kerosene in line 119 can have a
bromine index of at least 10, at least 15, or at least 20.
[0028] The hydrogen containing gas via line 113 introduced to the
hydroprocessing unit 15 can contain about 50% vol H.sub.2 or more,
about 65% vol H.sub.2 or more, about 75% vol H.sub.2 or more, about
85% vol H.sub.2 or more, or about 95% vol H.sub.2 or more. The
balance of the hydrogen containing feed in line 113 can include,
but is not limited to, other components typically found in refinery
hydrogen, such as nitrogen, methane, and argon. The hydrogen
containing feed in line 113 can contain less than about 3% mol
H.sub.2S, less than about 1% mol H.sub.2S, less than 0.1% mol
H.sub.2S, less than about 0.01% mol H.sub.2S, or less.
[0029] The one or more hydroprocessing units 115 can include one or
more catalyst beds in any arrangement, configuration and/or
orientation. The one or more catalyst beds can include fixed beds,
fluidized beds, ebullating beds, slurry beds, moving beds, bubbling
beds, any other suitable type of catalyst bed, or combinations
thereof. The hydroprocessing unit 115 can be configured vertically
for upward or downward flow through the one or more catalyst beds,
or horizontally for lateral flow through the one or more catalyst
beds. The one or more catalyst beds can be axial beds, axial/radial
beds, radial beds, or any combination thereof. The one or more
catalyst beds can be cold gas quenched, inter-cooled using one or
more exchangers, or a combination thereof to control or otherwise
regulate the temperature of the one or more catalyst beds. In at
least one specific embodiment, the hydroprocessing unit 115 can
include a single hydroprocessing stage, i.e. a single catalyst
bed.
[0030] In one or more embodiments, any suitable catalyst or
combination of catalysts for converting sulfur and sulfur compounds
to H.sub.2S and nitrogen and nitrogen compounds to NH.sub.3, for
example. The catalyst can include, but is not limited to, any one
or more Group VIII metals of the Periodic Table of Elements, such
as cobalt, nickel, palladium, iron, derivatives thereof, or
combinations thereof. The catalyst can be combined with one or more
Group VIA, IA, IIA, and/or IB metals of the Periodic table of
Elements, such as molybdenum or tungsten, oxides thereof, or
combinations thereof. The catalyst can be supported. Illustrative
catalyst supports can include, but are not limited to, alumina,
silica-alumina, titania-zirconia, and the like.
[0031] The operating temperature of the one or more hydroprocessing
units 115 can range from a low of about 200.degree. C., about
225.degree. C., or about 250.degree. C. to a high of about
375.degree. C., about 450.degree. C., or about 500.degree. C. For
example, the operating temperature of the one or more
hydroprocessing units 105 can range from 200.degree. C. to about
420.degree. C. or about 260.degree. C. to about 355.degree. C. The
operating pressure of the one or more hydroprocessing units 105 can
range from a low of about 1,000 kPa, about 1,350 kPa, or about
1,450 kPa to a high of about 5,500 kPa, about 10,000 kPa, or about
13,500 kPa or more. For example, the operating pressure of the one
or more hydroprocessing units 115 can range from about 3,000 kPa to
about 8,000 kPa or about 1,350 kPa to about 5,550 kPa.
[0032] As discussed above, the hydroprocessed kerosene via line 119
can be introduced to the one or more n-paraffins recovery units 120
to provide the kerosene raffinate via line 121 and one or more
n-paraffins products via line 123. The one or more n-paraffins
recovery units 120 can include any system, device, or combination
of systems and/or devices suitable for separating at least a
portion of the n-paraffins from the hydroprocessed kerosene in line
119. For example, the n-paraffins recovery unit 120 can include an
adsorption/desorption process that selectively adsorbs the
n-paraffins from the hydroprocessed kerosene in line 119. The
adsorbed paraffins can then be desorbed to provide the n-paraffins
product via line 123. Other suitable separation processes can
include, but are not limited to, solvent extraction, distillation,
or combinations thereof.
[0033] The n-paraffins product in line 123 can include one or more
n-paraffins having from 6 to 30 carbon atoms. For example, the
n-paraffins product in line 123 can contain one or more n-paraffins
having from about 10 to about 14 carbon atoms or from about 10 to
about 18 carbon atoms, or from about 8 to about 16 carbon atoms.
The n-paraffins product in line 123 can have an n-paraffins
concentration of about 90 wt % or more, about 95 wt % or more, or
about 97 wt % or more. The n-paraffins product in line 123 can have
an n-paraffins concentration of about 97.5 wt % or more, about 98.5
wt % or more, or about 99 wt % or more. The n-paraffins product in
line 123 can have a concentration of n-paraffins having from 10 to
14 carbon atoms of about 97 wt %, about 98 wt %, or about 99 wt %
or more. The balance of the n-paraffins product in line 123 can
include various hydrocarbons, such as aromatic hydrocarbons, non
n-paraffins hydrocarbons having a range of compounds with varying
numbers of carbon atoms, sulfur-containing compounds,
nitrogen-containing compounds, and any combination thereof. The
n-paraffins product in line 123 can have a concentration of
aromatic hydrocarbons ranging from a low of about 100 ppmw, about
250 ppmw, or about 500 ppmw to a high of about 5,000 ppmw, about
10,000 ppmw, or about 20,000 ppmw. The n-paraffins product in line
123 can have a concentration of sulfur or sulfur-containing
compounds of less than about 15 ppmw, less than about 10 ppmw, or
less than about 5 ppmw. The n-paraffins product in line 123 can
have a concentration of nitrogen or nitrogen-containing compounds
of less than about 15 ppmw, less than about 10 ppmw, or less than
about 5 ppmw. The paraffin product in line 123 can have a bromine
index ranging from a low of about 1, about 3, or about 6 to a high
of about 10, about 12, or about 15. The paraffin product in line
123 can have a bromine index of less than about 25, less than about
20, less than about 15, or less than about 10.
[0034] The n-paraffins product in line 123 can be sold as a final
n-paraffins product, further processed to provide a purified
n-paraffins product, and/or used in the production of one or more
products that requires n-paraffins. The purified n-paraffins
product in line 123 can be distilled to obtain various fractions of
n-paraffins, and blends thereof, containing various ranges of
carbon numbers and respective molecular weights for the desired
product applications. In at least one specific embodiment, the
n-paraffins product in line 123 can be processed to provide linear
alkyl benzenes ("LAB"). For example, the n-paraffins can be passed
through a catalytic dehydrogenation zone where some of the
n-paraffins can be converted to olefins. The n-paraffins and olefin
mixture can then be introduced to an alkylation zone where the
olefins react with the aromatic substrate to produce linear alkyl
benzenes. The linear alkylbenzenes can then be converted to linear
alkylsulfonate ("LAS") by sulfonation. The linear alkylbenzenes can
also be used to produce a variety of anionic surfactants compounded
into detergents, cleaning compounds, bar soaps and laundry or
dishwashing detergents.
[0035] A "high quality" or first purified n-paraffins product can
be produced by introducing at least a portion of the n-paraffins
product in line 123 to the one or more n-paraffins purification
units 130 via line 125. The n-paraffins purification unit 130 can
provide one or more purified n-paraffins products (two are shown,
131, 133). The n-paraffins purification unit 130 can include, for
example, a hydroprocessing unit which can hydrotreat or
"hydro-polish" the n-paraffins product to provide a first purified
n-paraffins product via line 131 having a reduced concentration
sulfur-containing compounds, nitrogen-containing compounds,
oxygen-containing compounds, and/or olefins that can be present in
the n-paraffins product in line 123. The hydroprocessing unit can
be similar to the hydroprocessing unit 115 discussed and described
above.
[0036] The first purified n-paraffins product in line 131 can have
a concentration of aromatic hydrocarbons ranging from a low of
about 25 ppmw, about 100 ppmw, about 250 ppmw, or about 500 ppmw to
a high of about 3,000 ppmw, about 4,500 ppmw, or about 6,000 ppmw.
For example, the concentration of aromatic hydrocarbons in the
first purified n-paraffins product in line 131 can be less than
about 5,000 ppmw. The n-paraffins product in line 123 can have a
concentration of sulfur or sulfur-containing compounds of less than
about 10 ppmw, less than about 5 ppmw, or less than about 2 ppmw.
The n-paraffins product in line 123 can have a concentration of
nitrogen or nitrogen-containing compounds of less than about 10
ppmw, less than about 7 ppmw, or less than about 5 ppmw. The
paraffin product in line 123 can have a bromine index ranging from
a low of about 0.5, about 2, or about 3 to a high of about 5, about
7, or about 12.
[0037] An even "higher quality" or second purified n-paraffins via
line 133 can be provided by further purifying the n-paraffins
product introduced via line 125 to the n-paraffins purification
unit 130. For example, the n-paraffins product in line 125 or the
first purified n-paraffins product can undergo further purification
to remove at least a portion of the aromatic compounds contained in
the n-paraffins product in line 125 or the first purified
n-paraffins product to produce the second purified n-paraffins via
line 133. The second purified n-paraffins product in line 133 can
have an n-paraffins concentration about 99.1 wt % or more, about
99.3 wt % or more, or about 99.5 wt % or more. The concentration of
the aromatic hydrocarbons in line 133 can range from a low of about
0 ppmw, about 5 ppmw, about 10 ppmw, about 15 ppmw, about 20 ppmw,
or about 25 ppmw to a high of about 75 ppmw, about 100 ppmw, about
150 ppmw, or about 200 ppmw. The concentration of sulfur or
sulfur-containing compounds in line 133 can be less than about 3
ppmw, less than about 1 ppmw, less than about 0.5 ppmw, or less
than about 0.1 ppmw. The n-paraffins product in line 133 can have a
bromine index of less than about 7, less than about 5, less than
about 3, or less than about 2.
[0038] Any suitable separation/removal process can be used to
reduce the amount of aromatics in the second purified n-paraffins
product in line 133 relative to the n-paraffins product in line 125
and the first purified n-paraffins product. For example, an
adsorption/desorption process can be used to separate the aromatic
compounds from the n-paraffins product in line 125. Other suitable
separation processes can include, but are not limited to, solvent
extraction, adsorption/desorption, hydrogenation, sulfuric acid
treating, distillation, and combinations thereof.
[0039] Referring again to the one or more thermal crackers 105,
depending on the particular type of thermal cracker, the
hydrocarbon feed in line 103 can be heated to a temperature ranging
from a low of about 400.degree. C. to a high of about 900.degree.
C. and a pressure ranging from a low of about 100 kPa to a high of
about 6,500 kPa to produce lighter components which can be
recovered as a vapor and coke which forms as a solid residue in the
coking unit. In a delayed coking process, the hydrocarbon feed via
line 103 can be introduced to a coking drum, heated, and held at a
temperature of from about 400.degree. C. to about 500.degree. C.
and a pressure of from about 300 kPa to about 900 kPa, for example,
to deposit solid coke, while cracked vapors are taken overhead.
Coke produced in the thermal cracking process can be transported to
a storage area, used as a solid fuel, or the like. The cracked
vapors can be introduced to one or more separators to provide the
light hydrocarbon fraction via line 107, the heavy hydrocarbon
fraction via line 109, and the kerosene fraction via line 111.
[0040] In a flexicoking process, the hydrocarbon feed via line 103
can circulate between a reactor and a heater. More specifically,
the hydrocarbon feed via line 103 can be introduced into a
fluidized bed, along with a stream of hot recirculating material.
The fluidized bed can be at a pressure of from about 100 kPa to
about 300 kPa and at a temperature of from about 480.degree. C. to
about 590.degree. C., for example. From the fluidized bed, a coke
containing product can be circulated to a heater vessel, where it
is heated. The heated coke can be introduced from the heater to a
gasifier, where it reacts with air and steam. A gasifier product
gas, referred to as coke gas and containing entrained coke
particles can be returned to the heater and cooled by cold coke
from the reactor to provide a portion of the reactor heat
requirement. The recycle of the coke gas from the gasifier to the
heater can provide the remainder of the heat requirement. Hot coke
gas leaving the heater can be used to generate high-pressure steam
before being processed for cleanup. The coke gas can be introduced
to one or more separators to provide the light hydrocarbon fraction
via line 107, the heavy hydrocarbon fraction via line 109, and the
kerosene fraction via line 111.
[0041] In a fluid coking process, a fluidized bed reactor can be
used in conjunction with a burner to produce coke and lighter
hydrocarbons. The hydrocarbon feed via line 103 can be introduced
to a scrubber, where heat can be exchanged with a reactor overhead
effluent and the heaviest fraction of the hydrocarbons leaving the
top of the reactor can be condensed. The total reactor feed,
including both the fresh feed via line 103 and a recycle feed
condensed in the scrubber, can be injected into a fluidized bed of
coke in the reactor. The reactor feed can be at a pressure of from
about 100 kPa to about 300 kPa and can be heated to a temperature
of from about 700.degree. C. to about 900.degree. C., for example.
The coke can be deposited on fluidized coke particles, while the
hydrocarbon vapors pass overhead into the scrubber. The reactor
overhead can be scrubbed for solids removal and the high boiling
material can be condensed and recycled to the reactor. The lighter
hydrocarbons can be sent from the scrubber to one or more
separators to provide the light hydrocarbon fraction via line 107,
the heavy hydrocarbon fraction via line 109, and the kerosene
fraction via line 111. Heat required to maintain the fluid coker at
coking temperature can be supplied by circulating coke between the
reactor and the burner. A portion of the coke produced in the
reactor can be burned with air to provide the process heat
requirements. Excess coke can be withdrawn from the burner and sent
to storage, used as fuel in another process, or the like. The
thermal cracking step of fluid-cokers and flexicokers can be
similar. However, fluid-coking does not utilize the residual coke
produced with the coker distillate while flexicoking employs the
coke by-product for the production of low thermal value gas.
Flexicokers and fluid-cokers can be as discussed and described in
U.S. Pat. Nos. 2,813,916; 2,905,629; 2,905,733; 3,661,543;
3,816,084; 4,055,484 and 4,497,705, which are incorporated by
reference herein.
[0042] The term coil (or furnace) visbreaking can refer to thermal
cracking units where the cracking process occurs in the furnace
tubes (or "coils"). The hydrocarbon feed via line 103 introduced to
a coil visbreaker can be at a pressure of from about 150 kPa to
about 1,000 kPa and heated to a temperature of from about
425.degree. C. to about 540.degree. C., for example. The thermally
cracked hydrocarbons exiting the furnace can be quenched to halt
the cracking reactions. Quenching the cracked hydrocarbons exiting
the furnace can include exchanging heat with the hydrocarbon feed
in line 103 introduced to the furnace. In another example, a heat
transfer medium, such as gas oil, can be used to quench the
material exiting the furnace. The level or amount the hydrocarbon
feed in line 103 cracks can be controlled by regulating the speed
of flow of the hydrocarbon feed through the furnace tubes. The
quenched cracked hydrocarbon product can then be introduced to one
or more separators to provide the light hydrocarbon fraction via
line 107, the heavy hydrocarbon fraction via line 109, and the
kerosene fraction via line 111.
[0043] In a soaker visbreaker the majority of the cracking
reactions can occur in a drum (the soaker) located after the
furnace. The hydrocarbon feed introduced via line 103 can be at a
pressure of from about 200 kPa to about 6,500 kPa and heated to a
temperature and held (soaked) of from about 400.degree. C. to about
650.degree. C., for example. Soaking the heated hydrocarbon feed
for a pre-determined period of time allows the cracking reactions
to occur. The heated hydrocarbon feed can be soaked for a time
period ranging from about 5 minutes to about 60 minutes. After the
desired period of time, the cracked hydrocarbon product can be
quenched. The quenched cracked hydrocarbon product can then be
introduced to one or more separators to provide the light
hydrocarbon fraction via line 107, the heavy hydrocarbon fraction
via line 109, and the kerosene fraction via line 111. Lower
temperatures can be used in soaker visbreaking as compared to coil
visbreaking because the soaker visbreaker maintains the
hydrocarbons at an elevated temperature for a comparatively longer
duration than the coil visbreaking.
[0044] When a plurality of thermal crackers are used, those thermal
crackers can be arranged in series, parallel, or a combination of
series and parallel. For example, a first thermal cracker can
provide a first thermally cracked hydrocarbon which can be
introduced to a second thermal cracker to produce a second
thermally cracked hydrocarbon. In another example, two thermal
crackers, either the same or different, can crack two hydrocarbon
feeds in parallel, with the cracked hydrocarbons combined
thereafter to provide the thermally cracked hydrocarbon.
[0045] The one or more separators within the thermal cracking unit
105 can include any separator suitable for separating two or more
hydrocarbon fractions from the thermally cracked hydrocarbon
product. The separator can include any system, device, or
combination of systems and/or devices that can provide kerosene via
line 111, for example, splitting, distillation, and/or
fractionation. In one or more embodiments, one or more packing
materials, baffles, trays, plates, distributors, structured packed
beds, random packed beds, collectors, and/or empty spaces can be
disposed within the separator in any order, frequency, or
configuration. In one or more embodiments, the separator can be an
open column without internals.
[0046] FIG. 2 depicts an illustrative n-paraffins recovery unit
200, according to one or more embodiments. The n-paraffins recovery
unit 200 can include one or more heaters 205, one or more
adsorption/desorption units (two are shown, 225, 230), one or more
compressors 240, and one or more separators (two are shown 250,
260). The first and second separation units 225, 230 can each
include one or more adsorption/desorption beds (one is shown 226,
231, respectively). The hydroprocessed kerosene in line 119 can be
introduced to the heater 205 to provide a heated kerosene via line
207. The kerosene can be heated to a temperature ranging from a low
of about 90.degree. C. to a high of about 275.degree. C. The heater
205 can be or include a direct fired heater, a heat exchanger
within which heat is transferred from a heat transfer medium to the
hydroprocessed kerosene, or the like.
[0047] As illustrated, the n-paraffins recovery unit 200 includes
two adsorption/desorption units 225, 230, which can alternatingly
be used to separate, i.e. adsorb and desorb n-paraffins from the
heated kerosene in line 207. For example, the heated kerosene in
line 207 can be introduced via line 208 to the first
adsorption/desorption unit 225, which can adsorb at least a portion
of the n-paraffins contained therein and an n-paraffins-lean
hydrocarbon can be recovered via line 232. Once the
adsorption/desorption bed 226 has adsorbed a sufficient amount of
n-paraffins or has become saturated with n-paraffins, the heated
kerosene introduced via line 208 can be stopped and redirected via
line 209 to the second adsorption/desorption unit 230, which can
adsorb at least a portion of the n-paraffins to provide an
n-paraffins-lean hydrocarbon via line 233. A displacing medium or
desorbent via line 212 provided from a compressed displacing medium
in line 211 can be introduced to the first adsorption/desorption
unit 225, which can displace at least a portion of the adsorbed
n-paraffins to provide an n-paraffins-rich hydrocarbon via line
227. Once the n-paraffins have been displaced from the
adsorption/desorption bed 226, the introduction of the displacing
medium via line 212 can be stopped. Once the adsorption/desorption
bed 231 has adsorbed a sufficient amount of n-paraffins or has
become saturated with n-paraffins, the heated kerosene introduced
via line 209 can be stopped and redirected via line 208 to the
adsorption/desorption unit 225, provided the adsorbed n-paraffins
have been desorbed and recovered via line 227, which can again
adsorb at least a portion of the n-paraffins to provide the
n-paraffins-lean hydrocarbon via line 233. The displacing medium
can be recovered by heating to a temperature of from about
250.degree. C. to about 500.degree. C., for example. A displacing
medium or desorbent via line 213 provided from the compressed
displacing medium in line 211 can be introduced to the second
adsorption/desorption unit 230, which can displace at least a
portion of the adsorbed n-paraffins to provide an n-paraffins-rich
hydrocarbon via line 228. As such, the two adsorption/desorption
units 225, 230 can be alternatingly operated such that the first
adsorption/desorption unit 225 adorbs n-paraffins while the second
adsorption/desorption unit 230 desorbs n-paraffins and vice
versa.
[0048] As shown, the heated kerosene via lines 208, 209 and the
displacing medium via lines 212, and 213 are introduced to opposing
ends of the adsorption/desorption units 225, 230. As such, the
adsorption and desorption steps can be conducted counter-currently
with respect to one another. For vertically oriented
adsorption/desorption units 225, 230 the heated kerosene via lines
208, 209 can be introduced to the adsorption/desorption units 225,
230, respectively, such that the heated kerosene flows downwardly
therethrough. The displacing medium via lines 212, 213 can be
introduced to the adsorption/desorption units 225, 230,
respectively, such that the displacing medium flows upwardly
therethrough. In another example the co-current flow directions of
the heated kerosene and the displacing medium can be reversed.
Although not shown, the adsorption and desorption steps can be
conducted co-currently with respect one another.
[0049] The n-paraffins-rich hydrocarbons via lines 227, 228 can be
introduced to the separator 250 via line 229 and the
n-paraffins-lean hydrocarbons via lines 232, 233 can be introduced
to the separator 260 via line 234. The separator 250 can provide
the n-paraffins product via line 123 and a recycle displacing
medium via line 254 and the separator 260 can provide the kerosene
raffinate via line 121 and a recycle displacing medium via line
264. The recycle displacing mediums via lines 264, 254 can be
introduced to the compressor 240 to provide the compressed
displacing mediums via line 211. The separators 250, 260 can
separate the displacing medium from the n-paraffins-rich
hydrocarbons and the n-paraffins-lean hydrocarbons using any
suitable method. For example, the separators 250 can condense the
n-paraffinic hydrocarbons and recover the condensed
n-paraffins-rich hydrocarbons via line 123 and a gaseous displacing
medium via line 254. Similarly, the separator 260 can condense the
hydrocarbons in the n-paraffins-lean hydrocarbons introduced via
line 234 to provide a condensed n-paraffins-lean hydrocarbon via
line 121 and a gaseous displacing medium via line 264.
[0050] The displacing medium introduced to the first and second
adsorption/desorption units 225, 230 can include any material
capable of displacing the adsorbed n-paraffins. Suitable displacing
mediums can include a polar material or a material with substantial
polarizability compared to the normal n-paraffins. In one or more
embodiments, the displacing medium can be represented by the
general formula:
##STR00001##
[0051] where R, R', and R'' are each selected from the group
consisting of hydrogen and C.sub.1 to C.sub.5 alkyl radicals. For
example, the displacing medium can include ammonia ("NH.sub.3") and
C.sub.1 to C.sub.15 primary, secondary, and tertiary amines. Other
suitable displacing mediums can include, but are not limited to,
hydrogen, sulfur dioxide ("SO.sub.2"), C.sub.1 to C.sub.5 alcohols,
C.sub.1 to C.sub.4 alkanes, glycols, halogenated compounds such as
methyl and ethyl chloride and methyl fluoride, nitrated compounds
such as nitro methane, and carbon dioxide ("CO.sub.2"). In one or
more embodiments, a fresh or make-up displacing medium can be
introduced to the n-paraffins recovery unit via line 256. The
displacing medium can be compressed and circulated via the
compressor 240 within the n-paraffins recovery unit 200 or the
circulation can be accomplished via an external source by
integrating the system with the fresh or makeup line 256 and a
suitable provision to reject or return the lower pressure
displacing medium from line 254.
[0052] The adsorption/desorption beds 226, 231 can include any
suitable medium capable of adsorbing n-paraffins while allowing at
least a majority of the non n-paraffinic hydrocarbons, e.g.
branched and cyclic hydrocarbons, to pass through the
adsorption/desorption units 225, 230. For example, the
adsorption/desorption beds 226, 231 can include molecular sieves.
Illustrative molecular sieves can include crystalline zeolites
containing an alkali or alkaline earth metal, aluminum, silicon
and/or oxygen. The molecular sieves can be, natural or synthetic
and can have uniform pore spaces of from about 3 to about 15
Angstroms ("A"), depending upon the composition and conditions
under which the molecular sieves were prepared. Molecular sieves
having a pore size of about 5 .ANG. can separate the normal
n-paraffins from branched chain and cyclic compounds. Natural
zeolites, having suitable molecular sieve properties, can include
analcite, NaAlSi.sub.2O.sub.6.H.sub.2O, and chabasite, CaAl.sub.2
Si.sub.4O.sub.12.6H.sub.2O. Other naturally occurring material
suitable for use as molecular sieves can be as discussed and
described in the article "Molecular Sieve Action of Solids,"
Quarterly Reviews, vol. III, p. 293-330 (1949), published by the
Chemical Society (London). Synthetic zeolites having similar
properties can be as discussed and described in U.S. Pat. No.
2,306,610, where a material of the formula
(CaNa.sub.2)Al.sub.2Si.sub.4O.sub.12.2H.sub.2O is described, and in
U.S. Pat. No. 2,522,426, where a material of the formula
4CaO.Al.sub.2O.sub.3.4SiO.sub.2 is described. Other suitable
molecular sieves can be as discussed and described in an article by
Breck et al., which was published in the Journal of the American
Chemical Society, Volume 78, page 593 et seq. in December 1956.
[0053] The adsorption and desorption of the n-paraffins within the
adsorption/desorption units 225, 230 can be performed in a liquid
and/or vapor phase. The adsorption and desorption of the
n-paraffins in the adsorption/desorption units 225, 230 can be
carried out at a temperature ranging from a low of about 95.degree.
C., about 200.degree. C., or about 260.degree. C. to a high of
about 370.degree. C., about 425.degree. C. or about 485.degree. C.
For example, the adsorption of the n-paraffins can be carried out
in the vapor phase at a temperature of from about 95.degree. C. to
about 300.degree. C. with the heated kerosene via lines 208, 209
partial pressure low enough to prevent an undesirable amount of
condensation in the adsorption beds 226, 231. The partial pressure
of the heated kerosene introduced via lines 208, 209 can be about
0.01 to about 0.7 of the pressure that would condense a hydrocarbon
having a boiling point equal to the average boiling point of the
heated kerosene at the temperature of operation. The desorption of
the n-paraffins can be carried out at a temperature of from about
315.degree. C. to about 485.degree. C. and a pressure of from about
1.3 kPa to about 1,500 kPa with a sufficient amount of displacing
agent introduced via lines 212, 213 to displace at least a portion
of the adsorbed n-paraffins. Further adsorption and desorption
process conditions and can be as discussed and described in U.S.
Pat. Nos. 2,899,379; 3,248,322; 3,378,486; and 3,418,235.
[0054] Although not shown, the purity of the n-paraffins-rich
hydrocarbons via lines 227, 228 can be increased by pressurizing
and then depressurizing the adsorption/desorption units 225, 230
after adsorption of the n-paraffins and prior to the desorption of
the n-paraffins. For example, after the adsorption/desorption beds
226, 231 have adsorbed the desired amount of n-paraffins, the
heated kerosene via lines 208, 209 can be stopped and the pressure
within the adsorption/desorption units 225, 230 can be allowed to
increase to about 101% to about 500% of the adsorption pressure.
The adsorption/desorption units 225, 230 can then be depressurized.
The material that exists the adsorption/desorption beds 225, 231
during the pressurization and depressurization includes a majority
of any impurities, e.g. non n-paraffinic compounds, which can be
adsorbed or disposed within the adsorption/separation beds 226,
231. Although not shown, the purity of the n-paraffins-rich
hydrocarbons via lines 227, 228 can also be increased through a
temperature swing, e.g. increasing and then decreasing the
temperature of the adsorption/desorption units 225, 230 after
adsorption of the n-paraffins and prior to the desorption of the
n-paraffins.
[0055] The compressor 240 can include any device suitable for
compressing a gas, and/or multi-phase fluid, for example one or
more reciprocating, rotary, axial flow, centrifugal, diagonal or
mixed-flow, scroll, or diaphragm compressors or any series and/or
parallel combination thereof. The compressor 240 can have one or
more compressor stages with or without intercooling between
successive stages. In one or more embodiments, the pressure of the
compressed displacing medium in line 211 can range from about 101
kPa to about 5,000 kPa.
[0056] FIG. 3 depicts an illustrative n-paraffins purification
system 300, according to one or more embodiments. The n-paraffins
purification system 300 can include one or more hydroprocessing or
"hydro-polishing" units 305, one or more adsorption/desorption
units 320, 325, and one or more separators 340, 350. The
adsorption/desorption units 320, 325 can include one or more
adsorption/desorption beds (one is shown 321, 326,
respectively).
[0057] In one or more embodiments, the n-paraffins product in line
125 and a hydrogen containing gas via line 302 can be introduced to
the hydroprocessing unit 305 to further remove at least a portion
of any impurities that can remain therein to provide a first
purified n-paraffins product via line 307. The hydroprocessing unit
305 can be similar to the hydroprocessing unit 115 discussed and
described above with reference to FIG. 1. The hydroprocessing unit
305 can act as a "guard" bed to remove or reduce the amount of
impurities, such as sulfur-containing and nitrogen-containing
compounds. As such, in addition to the first purified n-paraffins
product via line 307, an off-gas via line 306 can be also be
recovered from the hydroprocessing unit 305. The off-gas can
contain at least a portion of the impurities converted within the
hydroprocessing unit 305. In at least one specific embodiment, all
or a portion of the first purified n-paraffins product in line 307
can be recovered as the purified n-paraffins or "LAB quality"
n-paraffins product via line 131. In at least one other specific
embodiment, all or a portion of the first purified n-paraffins
product in line 307 can be further processed via line 309 to
provide the second purified n-paraffins via line 133.
[0058] As illustrated, the n-paraffins purification unit 300
includes two adsorption/desorption units 320, 325, which can
alternatingly be used to separate, i.e. adsorb and desorb
impurities from the first purified n-paraffins in line 309. For
example, the first purified n-paraffins in line 309 can be
introduced via line 311 to the first adsorption/desorption unit
320, which can adsorb at least a portion of the impurities
contained therein and a second purified n-paraffins product can be
recovered via line 327. Once the adsorption/desorption bed 321 has
adsorbed a sufficient amount of impurities or has become saturated
with impurities, the first purified n-paraffins introduced via line
311 can be stopped and redirected via line 313 to the second
adsorption/desorption unit 325, which can adsorb at least a portion
of the impurities to provide a second purified n-paraffins product
via line 328. A displacing medium or desorbent via line 361 can be
introduced to the first adsorption/desorption unit 320, which can
displace at least a portion of the adsorbed impurities to provide
an impurity-rich effluent via line 322. Once the impurities have
been displaced from the adsorption/desorption bed 321, the
introduction of the displacing medium via line 361 can be stopped.
Once the adsorption/desorption bed 326 has adsorbed a sufficient
amount of impurities or has become saturated with impurities, the
first purified n-paraffins introduced via line 313 can be stopped
and redirected via line 311 to the adsorption/desorption unit 320,
provided the adsorbed impurities have been desorbed and recovered
via line 322, which can again adsorb at least a portion of the
impurities to provide the second purified n-paraffins product via
line 327. A displacing medium or desorbent via line 362 can be
introduced to the second adsorption/desorption unit 325, which can
displace at least a portion of the adsorbed impurities to provide a
second purified n-paraffins product via line 328. As such, the two
adsorption/desorption units 320, 325 can be alternatingly operated
such that the first adsorption/desorption unit 225 adsorbs
n-paraffins while the second adsorption/desorption unit 230 desorbs
n-paraffins and vice versa.
[0059] The first purified n-paraffins via lines 311, 313 and the
displacing mediums via lines 361, 362 can be introduced to the same
end or different ends (not shown) of the adsorption/separation
units 320, 325. As shown, the first purified n-paraffins via lines
311, 313 and the displacing mediums via lines 361, 362 can be
introduced to the same end of each adsorption/separation unit 320,
325. As such, the adsorption and desorption steps can be conducted
co-currently with respect to one another. Although not shown, the
first purified n-paraffins product via lines 311, 313 and the
displacing medium via lines 361, and 362 can be introduced to
opposing ends of the adsorption/desorption units 320, 325. As such,
the adsorption and desorption steps can be conducted
counter-currently with respect to one another. For example, for
vertically oriented adsorption/desorption units 320, 325 the first
purified n-paraffins product via lines 311, 313 can be introduced
to the adsorption/desorption units 320, 325, respectively, such
that the first purified n-paraffins product flows downwardly
therethrough. The displacing medium via lines 361, 362 can be
introduced to the adsorption/desorption units 320, 325,
respectively, such that the displacing medium flows upwardly
therethrough.
[0060] The second purified n-paraffins products via lines 327, 328
can be introduced to the separator 340 via line 329 and the
impurities via lines 322, 323 can be introduced to the separator
350 via line 324. The separator 340 can provide the second purified
n-paraffins product via line 133 and a recycle displacing medium
via line 344. The recycle displacing medium in line 344 can be
introduced to the separator 350 or directly recycled to a fresh or
make-up displacing medium in line 360. The separator 350 can
provide an impurity effluent via line 352 and a recycle displacing
medium via line 354, which can be introduced to the make-up
displacing medium in line 360. The recycle and make-up displacing
medium in line 360 can provide the displacing mediums introduced
via lines 361, 362 to the adsorption/desorption units 320, 325. The
separators 340, 350 can separate the displacing medium from the
n-paraffins-rich hydrocarbons and the n-paraffins-lean hydrocarbons
using any suitable method. For example, the separator 340 can
condense the second purified n-paraffins product to provide a
condensed second purified n-paraffins product via line 133 and a
gaseous recycle displacing medium via line 344. Similarly, the
separator 350 can condense the impurities introduced via line 324
to provide a condensed impurity effluent via line 352 and the
recycle displacing medium via line 354.
[0061] The displacing medium introduced to the first and second
adsorption/desorption units 320, 325 can include any material
capable of displacing the adsorbed impurities. Suitable displacing
mediums can include materials in the same class of molecules as the
predominant impurity to be removed from the first purified
n-paraffins in line 309. For example, the predominant impurity to
be removed from the first purified n-paraffins in line 309 can be
aromatic hydrocarbons. As such, desorbents suitable for desorbing
aromatic hydrocarbons can include nonpolar, alkyl-substituted
benzene. For example, a suitable desorbent for desorbing aromatic
hydrocarbons can be or include toluene.
[0062] The first purified n-paraffins product introduced via lines
311, 313 to the adsorption/desorption units 320, 326 can be
contacted in the liquid and/or vapor phase with a solid adsorbent.
In at least one specific embodiment, the adsorption of the
impurities within the adsorption/desorption units 320, 325 can be
performed in the liquid phase. The first purified n-paraffins
product can be heated to a temperature of from about 20.degree. C.
to about 250.degree. C. Back pressure regulation can be used to
promote or maintain the adsorption of the impurities in the liquid
phase.
[0063] The adsorption/desorption beds 321, 326 can include any
suitable medium capable of adsorbing one or more of any impurities
that may be present in the first purified n-paraffins introduced to
the adsorption/desorption units 320, 325, respectively. For
example, the adsorption/desorption beds 321, 326 can include
molecular sieves. Illustrative molecular sieves can include, but
are not limited to, zeolites of the faujasite family, which
includes natural and synthetic zeolites having an average pore
diameter of from about 6 to about 15 .ANG.. Representative examples
of molecular sieves include faujasites, mordenites, and zeolite
types X, Y, and A. The adsorbent can include an inorganic binder
such as silica, alumina, silica-alumina, kaolin, and/or
attapulgite. The zeolites can be subjected to cation exchange prior
to use. Cations that can be incorporated into the zeolites, through
ion-exchange processes, for example, include all alkali and
alkaline earth metals, as well as trivalent cations. The molecular
sieves can be in any form, such as extruded, beaded, or crushed
particles.
[0064] The adsorption and desorption of the impurities within the
adsorption/desorption units 320, 325 can be carried out under
liquid and/or vapor phase. The adsorption and desorption of the
n-paraffins in the adsorption/desorption units 320, 325 can be
carried out at a temperature ranging atmospheric temperature to
about 250.degree. C. For example, the adsorption of the impurities
can be carried out in the liquid phase at a temperature of from
about 100.degree. C. to about 150.degree. C. Further adsorption and
desorption process conditions and can be as discussed and described
in U.S. Pat. Nos. 5,109,139; 5,171,923; and 5,220,099.
[0065] Embodiments of the present invention further relate to any
one or more of the following paragraphs:
[0066] 1. A method for producing n-paraffins, comprising
hydroprocessing at least a portion of a kerosene fraction recovered
from a thermally cracked hydrocarbon product to produce a
hydroprocessed kerosene product comprising n-paraffins; and
separating the n-paraffins from the hydroprocessed kerosene product
to produce an n-paraffins product.
[0067] 2. The method according to paragraph 1, wherein the kerosene
fraction is hydroprocessed in the presence of hydrogen and one or
more catalysts at a temperature of from about 200.degree. C. to
about 420.degree. C. and a pressure of from about 3,000 kPa to
about 8,000 kPa.
[0068] 3. The method according to paragraphs 1 or 2, wherein the
hydroprocessed kerosene fraction further comprises at least 1 ppmw
nitrogen-containing compounds.
[0069] 4. The method according to any of paragraphs 1 to 3, wherein
the hydroprocessed kerosene fraction has a bromine index of at
least 10.
[0070] 5. The method according to any of paragraphs 1 to 4, wherein
the hydroprocessed kerosene fraction further comprises at least 1
ppmw sulfur-containing compounds.
[0071] 6. The method according to any of paragraphs 1 to 5, wherein
a kerosene fraction recovered from an atmospheric distillation unit
is mixed with at least one of the thermally cracked hydrocarbon
product and the hydroprocessed kerosene product.
[0072] 7. The method according to any of paragraphs 1 to 6, wherein
separating the n-paraffins comprises an adsorption process, a
solvent extraction process, a distillation process, or any
combination thereof.
[0073] 8. The method according to any of paragraphs 1 to 7, wherein
separating the n-paraffins comprises an adsorption process
comprising contacting the hydroprocessed kerosene product with a
first adsorbent material at conditions sufficient to cause the
first adsorbent material to adsorb at least a portion of the
n-paraffins; contacting the adsorbed n-paraffins with a displacing
medium at conditions sufficient to cause at least a portion of the
adsorbed n-paraffins to be desorbed; and recovering the desorbed
n-paraffins as the n-paraffins product.
[0074] 9. The method according to paragraph 8, wherein the
recovered n-paraffins comprise one or more impurities, and wherein
the adsorption process further comprises contacting the recovered
n-paraffins with a second adsorbent material at conditions
sufficient to cause the second adsorbent material to adsorb at
least a portion of the one or more impurities to produce an
n-paraffins product having a reduced concentration of impurities
relative to the recovered n-paraffins.
[0075] 10. The method according to paragraph 9, wherein the
impurities comprise aromatic hydrocarbons, and wherein the
n-paraffins product has a concentration of less than about 100 ppmw
aromatics.
[0076] 11. The method according to any of paragraphs 1 to 10,
further comprising introducing an atmospheric distillation tower
bottoms, a vacuum distillation tower bottoms, or a combination
thereof to a thermal cracker to produce the thermally cracked
hydrocarbon product; and separating the thermally cracked
hydrocarbon product to produce a light hydrocarbon fraction, a
heavy hydrocarbon fraction, and the kerosene fraction.
[0077] 12. A method for producing n-paraffins, comprising thermally
cracking a hydrocarbon feed to produce a thermally cracked
hydrocarbon mixture; selectively separating a kerosene fraction
from the hydrocarbon mixture; hydroprocessing at least a portion of
the kerosene fraction to produce a hydroprocessed kerosene
comprising n-paraffins, less than about 500 ppmw sulfur-containing
compounds, and less than about 200 ppmw nitrogen-containing
compounds; and separating the n-paraffins from the hydroprocessed
kerosene product to produce an n-paraffins product.
[0078] 13. The method according to paragraph 12, wherein the
hydroprocessed kerosene comprises at least 1 ppmw
nitrogen-containing compounds and at least 1 ppmw sulfur-containing
compounds.
[0079] 14. The method according to paragraphs 12 or 13, wherein the
kerosene fraction has a bromine index of at least 10.
[0080] 15. The method according to any of paragraphs 12 to 14,
wherein the hydrocarbon feed comprises atmospheric distillation
tower bottoms, vacuum distillation tower bottoms, or a combination
thereof.
[0081] 16. The method according to any of paragraphs 12 to 15,
wherein separating the n-paraffins comprises an adsorption process,
a solvent extraction process, a distillation process, or any
combination thereof.
[0082] 17. A system for producing n-paraffins, comprising a
hydroprocessing unit for hydroprocessing at least a portion of a
kerosene fraction recovered from a thermally cracked hydrocarbon
product to produce a hydroprocessed kerosene product comprising
n-paraffins; and a first separation unit for separating the
n-paraffins from the hydroprocessed kerosene product to produce an
n-paraffins product.
[0083] 18. The system according to paragraph 17, further comprising
a thermal cracking unit for thermally cracking a hydrocarbon feed
to produce the thermally cracked hydrocarbon product; and a second
separation unit for separating the thermally cracked hydrocarbon
product to produce a light hydrocarbon fraction, a heavy
hydrocarbon fraction, and the kerosene fraction.
[0084] 19. The system according to paragraphs 17 or 18, wherein the
first separation unit comprises one or more adsorption/desorption
units.
[0085] 20. The system according to any of paragraphs 17 to 19,
further comprising a third separation unit for purifying the
n-paraffins product to produce an n-paraffins product comprising
about 99 wt % or more n-paraffins.
[0086] Certain embodiments and features have been described using a
set of numerical upper limits and a set of numerical lower limits.
It should be appreciated that ranges from any lower limit to any
upper limit are contemplated unless otherwise indicated. Certain
lower limits, upper limits and ranges appear in one or more claims
below. All numerical values are "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
[0087] Various terms have been defined above. To the extent a term
used in a claim is not defined above, it should be given the
broadest definition persons in the pertinent art have given that
term as reflected in at least one printed publication or issued
patent. Furthermore, all patents, test procedures, and other
documents cited in this application are fully incorporated by
reference to the extent such disclosure is not inconsistent with
this application and for all jurisdictions in which such
incorporation is permitted.
[0088] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *