U.S. patent number 3,617,501 [Application Number 04/757,939] was granted by the patent office on 1971-11-02 for integrated process for refining whole crude oil.
This patent grant is currently assigned to Esso Research and Engineering Company. Invention is credited to Jackson Eng, John L. Tiedje.
United States Patent |
3,617,501 |
Eng , et al. |
November 2, 1971 |
INTEGRATED PROCESS FOR REFINING WHOLE CRUDE OIL
Abstract
The disclosure relates to a process for the refining of whole
crude oil to produce a maximum quantity of gasoline and distillate
products and a minimum quantity of industrial fuel oil. The process
features hydrotreating of whole crude oil as the first major
processing step.
Inventors: |
Eng; Jackson (Sarnia,
CA), Tiedje; John L. (Sarnia Township, Ontario,
CA) |
Assignee: |
Esso Research and Engineering
Company (N/A)
|
Family
ID: |
25049817 |
Appl.
No.: |
04/757,939 |
Filed: |
September 6, 1968 |
Current U.S.
Class: |
208/89;
208/97 |
Current CPC
Class: |
C10G
47/00 (20130101); C10G 69/00 (20130101) |
Current International
Class: |
C10G
47/00 (20060101); C10G 69/00 (20060101); C10g
023/02 () |
Field of
Search: |
;208/60,80,89,61,57,97 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gantz; Delbert E.
Assistant Examiner: Crasanakis; G. J.
Claims
What is claimed is:
1. An integrated process for producing light naphtha and heavy
naphtha from whole petroleum crude oil comprising the steps of:
a. passing said whole petroleum crude oil containing sulfur,
nitrogen and metal impurities directly to a hydrofining zone;
b. hydrofining said crude oil in the presence of a hydrofining
catalyst and hydrogen;
c. passing hydrofined crude oil to an atmospheric distillation
zone;
d. distilling an admixture of said hydrofined crude oil with
cracked products as hereinafter identified;
e. recovering a light naphtha fraction from said distillation zone,
and fraction being essentially free of mercaptans;
f. recovering a low sulfur, heavy naphtha reformer feedstock
fraction from said distillation zone;
g. passing a low sulfur, low nitrogen cracking feed fraction from
said distillation zone to a cracking zone;
h. cracking said fraction in the presence of a sulfur and
nitrogen-sensitive cracking catalyst, and
i. passing at least a part of the cracked products to the
atmospheric distillation zone of step (c) to provide said admixture
of step (d).
2. An integrated process for producing light naphtha, heavy naphtha
and a fuel oil fraction from whole petroleum crude oil comprising
the steps of:
a. passing said whole petroleum crude oil containing sulfur,
nitrogen and metal impurities directly to a hydrofining zone;
b. hydrofining said crude oil in the presence of a hydrofining
catalyst and hydrogen;
c. passing hydrofined crude oil to an atmospheric distillation
zone;
d. distilling an admixture of said hydrofined crude oil with
hydrocracked products as hereinafter identified;
e. recovering a light naphtha fraction from said distillation zone,
said fraction being essentially free of mercaptans;
f. recovering a low sulfur, heavy naphtha reformer feed stock
fraction from said distillation zone;
g. passing a low sulfur, low nitrogen atmospheric distillation
bottoms from said distillation zone to a vacuum distillation
zone;
h. recovering a low sulfur fuel oil and cracking feed fraction from
said vacuum distillation zone;
i. passing said cracking feed fraction to a hydrocracking zone;
j. hydrocracking said fraction at a temperature in the range of
650.degree. to 750.degree. F. and a pressure in the range of 1,000
to 3,000 p.s.i.g. in the presence of 5,000 to 10,000 s.c.f./B of
hydrogen and a catalyst comprising a metal hydrogenation component
and a crystalline aluminosilicate zeolite;
k. recovering hydrocracked products comprising a major amount of
naphtha, and
l. passing said hydrocracked products to the atmospheric
distillation zone of step (c) to provide said admixture of step
(d).
3. Process according to claim 11, in which the hydrofining catalyst
is cobalt molybdate on alumina.
4. Process according to claim 1, in which said cracking feed
fraction of step (i) boils in the range of about 650.degree. to
950.degree. F.
5. Process according to claim 1, in which the catalyst of step (j)
comprises a nickel-tungsten hydrogenation component on a support
comprising zeolite Y.
6. An integrated process for producing light naphtha and heavy
naphtha from whole petroleum crude oil comprising the steps of:
a. passing said whole petroleum crude oil containing sulfur,
nitrogen and metal impurities directly to a hydrofining zone;
b. hydrofining said crude oil in the presence of a hydrofining
catalyst and hydrogen;
c. passing hydrofined crude oil to an atmospheric distillation
zone;
d. distilling an admixture of said hydrofined crude oil with
cracked products as hereinafter identified;
e. recovering a light naphtha fraction from said distillation zone,
said fraction being essentially free of mercaptans;
f. recovering a low sulfur, heavy naphtha reformer feed stock
fraction from said distillation zone;
g. passing a low sulfur, low nitrogen cracking feed fraction from
said distillation zone to a cracking zone;
h. catalytically cracking said fraction at a temperature in the
range of 900.degree. to 950.degree. F. and a pressure in the range
of 5 to 25 p.s.i.g. in the presence of a cracking catalyst
comprising a crystalline aluminosilicate zeolite component
composited with an amorphous silica alumina component;
i. recovering catalytically cracked products;
j. passing a major proportion of said cracked products to the
hydrofining zone of step (b) for saturation of olefins in the
cracked products, and
k. passing a minor proportion of said cracked products to the
atmospheric distillation zone of step (c) to provide said admixture
of step (d).
7. Process according to claim 6 in which the hydrofining catalyst
of step (b) is nickel molybdate on a support comprising alumina and
1 and 10 weight percent silica.
8. An integrated process for producing light naphtha, heavy naphtha
and fuel oil from whole petroleum crude oil comprising the steps
of:
a. passing said whole petroleum crude oil containing sulfur,
nitrogen and metal impurities directly to a hydrofining zone;
b. hydrofining said crude oil in the presence of a hydrofining
catalyst and hydrogen;
c, passing hydrofined crude oil to an atmospheric distillation
zone;
d. distilling an admixture of said hydrofined crude oil with
cracked products as hereinafter identified;
e. recovering a light naphtha fraction from said distillation zone,
and fraction being essentially free of mercaptans;
f. recovering a low sulfur, heavy naphtha reformer feed stock
fraction from said distillation zone;
g. passing a low sulfur, low nitrogen atmospheric distillation
bottoms from said distillation zone to a vacuum distillation
zone;
h. recovering a low sulfur fuel oil and a cracking feed fraction
from said vacuum distillation zone;
i. cracking the cracking feed fraction of step (h) in a cracking
zone in the presence of a cracking catalyst;
j. passing at least a part of the cracked products to the
atmospheric distillation zone of step (c) to provide said admixture
of step (d).
Description
The first major processing unit in a conventional petroleum
refinery is a crude oil distillation tower. The tower is operated
to separate the crude oil into a number of petroleum fractions of
selected boiling ranges and these fractions are further refined to
provide end products having desired characteristics. Many
individual fractions are treated with hydrogen and a catalyst to
reduce their sulfur content and for other purposes. For this
reason, it is not uncommon for a modern petroleum refinery to have
five or six different hydrotreating or hydrofining units.
A refinery processing scheme is described in this disclosure which
will consolidate all of the hydrogen treating operations, except
hydrocracking and hydroforming, in a single unit. The disclosed
process is also designed to produce by cracking a maximum quantity
of petroleum oil boiling at less than about 1,100.degree. F., which
drastically reduces the quantity of low value fuel oil produced in
the refinery.
In the process, whole crude is hydrodesulfurized to produce a light
naphtha fraction suitable for blending into motor gasoline, a heavy
naphtha fraction in condition for reforming in the presence of a
sulfur sensitive catalyst and one or more desulfurized middle
distillate fractions such as kerosene, diesel fuel and home heating
oil.
In one preferred embodiment of the process a desulfurized fraction
boiling in the gas oil boiling range is hydrocracked to produce a
maximum quantity of motor fuel components. In another preferred
embodiment a desulfurized fraction boiling in the gas oil boiling
range is catalytically cracked to provide a desired product slate
including light naphtha, reformer feed stock and distillate
fractions boiling in the range of 300.degree. to 750.degree. F.
There are numerous advantages for the refinery processing scheme
described herein over a conventional refinery. One hydrotreating
unit replaces the light naphtha caustic treater, the hydrofiner
associated with the reformer, the virgin and cracked gas oil
hydrofiners and the residual oil hydrogenation unit. Reduced sulfur
corrosion and consequent maintenance savings are achieved. The
overall fuel oil production of the refinery is decreased and any
fuel oil that is produced is low in sulfur. The motor gasoline
produced is low in sensitivity and lead response is improved. The
number of refinery processing units is reduced to a minimum and
they are closely integrated for flexibility.
Further objects and advantages of the process of the invention will
be apparent from the following description and examples. The flow
sheet discloses one of the most preferred embodiments of the
invention.
In brief summary, the process comprises catalytically hydrotreating
a whole petroleum crude oil to remove sulfur, nitrogen, metals and
other contaminants and passing the treated crude to an atmospheric
distillation zone. Naphtha and distillate fractions are recovered
as products. A fraction boiling in the range of from about
180.degree. to 375.degree. F. is passed to a reforming zone. The
atmospheric bottoms fraction is passed to a vacuum tower. The
vacuum overhead is passed to a cracker which may be a cat cracker
or a hydrocracker. The vacuum bottoms fraction is recovered as low
sulfur fuel oil.
Suitable feed stocks for the refining process of the invention
comprise whole crude oil fractions, i.e., petroleum fractions which
have had no treating except perhaps desalting and removal of light
ends. The crude oil will have an initial boiling point in the range
of 0.degree. to 100.degree. F. and a 90 percent boiling point in
the range of 900.degree. to 1,200.degree. F. The oil will contain
from about 0.1 to 8 weight percent sulfur, preferably 0.5 to 4.0
weight percent sulfur, in the form of sulfur compounds such as
mercaptans, sulfides, thiophenes etc. The oil may also contain
nitrogen in the form of nitrogen compounds, phenols, naphthenic
acids, organometallic compounds and asphaltenes.
Referring to the drawing, a sulfur-containing whole crude oil is
passed by line 1 to hydrotreater 2. The oil is preferably preheated
by means, not shown, to a temperature in the range of 550.degree.
to 800.degree. F. A hydrogen-containing gas containing 70 to 100
percent hydrogen is supplied by line 3.
Broad Preferred
__________________________________________________________________________
Temperature, .degree.F. 550-850 650-775 Pressure, p.s.i.g.
200-5,000 300-2,000 Space Velocity, v./hr./v. 0.1-10 0.2-2 Gas
rate, SCF/Bbl. 300-5,000 500-2,000
__________________________________________________________________________
Suitable hydrotreating catalysts comprise one or more hydrogenation
metals supported on a suitable carrier material. The metals can be
metals per se but preferably they are in the form of metal oxides
or metal sulfides. Salts of Group VI and Group VIII metals are the
preferred hydrogenating components. Specifically, oxides or
sulfides of molybdenum, tungsten, cobalt, nickel and iron are used.
Alumina, alumina containing 1 to 10 weight percent silica, bauxite,
kieselguhr, etc., are suitable support materials. The most
preferred catalysts are sulfided cobalt molybdate or sulfided
nickel molybdate on alumina or silica alumina. The catalyst can be
employed in the form of a fixed bed, a slurry or a fluidized bed.
Liquid phase or mixed phase conditions are used in the
hydrotreater.
The hydrotreating step performs several functions, including
hydrodesulfurization, hydrosweetening, saturation of olefins,
hydrodenitrogenation, etc. Catalyst and reaction conditions are
selected in accordance with the characteristics of the crude oil
feed and the type and quantity of products desired. For example, if
a maximum amount of the gas oil boiling in the range of 650.degree.
to 1,050.degree. F. is to be hydrocracked, severe hydrotreating
conditions are used to reduce the sulfur and nitrogen content of
the gas oil to the lowest possible level. However, if a fairly
narrow fraction is to be hydrocracked or catalytically cracked in
the presence of a nitrogen tolerant synthetic zeolite catalyst, it
may be possible to use less severe hydrotreating conditions.
The hydrotreated whole crude is passed by line 4 to atmospheric
distillation tower 5. Conventional means, not shown in the flow
sheet, are used to purify hydrotreater hydrogen for recycle. A gas
fraction is recovered from tower 5 by line 6. A light naphtha
fraction boiling in the range of 75.degree. to 180.degree. F. is
recovered by line 7. This fraction is in condition for blending
into motor fuel without further treatment such as sweetening and
stabilization. A heavy naphtha fraction boiling in the range of
from about 180.degree. to 375.degree. F. is passed by line 8 to
hydroformer 9.
The hydroformer (reformer) is operated in the conventional manner.
Typical hydroforming conditions are set forth below in table II.
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table ii
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hydroforming Conditions
Broad Preferred
__________________________________________________________________________
Temperature, .degree.F. 880-1,000 900-970 Pressure, p.s.i.g.
50-1,000 100-750 Space velocity, 0.1-10 v ./hr./v. 0 .5-5 Recycle
gas rate, SCF/Bbl. 1,000-10,000 2,000-5,000
__________________________________________________________________________
Conventional catalysts are employed. Suitable hydroforming
catalysts comprise metals selected from the group consisting of
molybdenum, chromium, platinum and palladium on alumina. Hydrogen
is produced in the reforming operation and part of it is recycled
back to the reformer by line 10. Excess reformer hydrogen can be
used in hydrotreating and/or hydrocracking. Reformate is recovered
by line 11. Platinum and palladium hydroforming catalysts are
quickly deactivated by sulfur containing feeds. It is a feature of
this invention that the reforming feed fraction is desulfurized as
a part of the whole crude and thus no separate hydrofiner is needed
to process this fraction.
A middle distillate fraction boiling in the range of 300.degree. to
750.degree. F. is recovered from the atmospheric distillation tower
by line 12. If desired, a number of middle distillate fractions
such as kerosene, diesel fuel and home heating oil can be
recovered. The fractions have already been hydrofined by treatment
in the hydrotreater.
The desulfurized bottoms fraction from atmospheric distillation
tower 5 having an initial boiling point in the range of about
650.degree. to 750.degree. F. is passed by line 13 to vacuum
distillation tower 14. The purpose of the vacuum tower is to make a
fairly precise split of the bottoms fraction into cracker feed and
a low sulfur fuel oil product fraction recovered by line 15. The
cracking feed is passed by lines 16 and 17 to cracker 18. As stated
previously, the cracker can be a catalytic cracker or hydrocracker
depending on the feed and the type of product slate desired.
Assuming hydrocracking is the desired reaction in unit 18, a
fraction boiling in the range of about 650.degree. to 950.degree.
F. is passed by lines 16 and 17 to the hydrocracker. Hydrogen is
supplied by line 19. Hydrogen purification means of any
conventional type are employed, but these have not been shown in
the flow sheet.
Typical hydrocracking conditions are set forth below in table III.
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table iii
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hydrocracking Conditions
Broad Preferred
__________________________________________________________________________
Temperature, .degree.F. 600-800 650-750 Pressure, p.s.i.g.
500-5,000 1,000-3,000 Space velocity, v./hr./v. 0.1-5 0.5-2 Gas
rate, SCF/Bbl. 1,000-20,000 5,000-10,000
__________________________________________________________________________
Suitable hydrocracking catalysts comprise a hydrogenating component
and a cracking component. Suitable hydrogenation components
comprise metals or metal oxides of Groups VI and VII of the
Periodic Table, and particularly platinum, palladium, nickel,
tungsten and mixtures thereof. Suitable cracking components
comprise silica-alumina, silica-magnesia, silica-zirconia, and
other amorphous bases, but the most preferred cracking bases for
hydrocracking are the crystalline aluminosilicate zeolites known as
molecular sieves. A specific example is Zeolite Y, which is
commercially available from the Linde Division of Union Carbide
Corporation. Since the feed has already been treated in the
hydrotreater to remove sulfur and nitrogen contaminants, a
single-stage hydrocracker can be employed rather than a two-stage
system in which the first stage is relied on to hydrofine the feed.
Extinction recycle can be employed for materials boiling above
about 450.degree. F.
Hydrocracker effluent comprising gas, a light naphtha fraction
boiling in the range of about C.sub.5 -180.degree. F. and a heavy
naphtha fraction boiling in the range of about 180.degree. to
430.degree. F. is passed by lines 23, 24 and 4 to atmospheric
distillation tower 5. Thus, a single atmospheric distillation tower
5. Thus, a single atmospheric distillation tower serves both the
hydrotreater and the cracker. Extinction recycle can be employed
for the heavy ends from the hydrocracker if desired.
In another preferred embodiment the entire atmospheric bottoms
fraction in line 13 is hydrocracked. In this embodiment the vacuum
distillation tower is bypassed by closing valve 20 and passing the
bottoms directly into the hydrocracker via line 17.
When the refinery is being operated to provide significant amounts
of middle distillates, cracker 18 is a catalytic cracker. In this
case, line 19 for hydrogen addition would not be required. The
vacuum distillation tower is operated to produce a desulfurized
vacuum overhead fraction boiling in the range of 650.degree. to
1,050.degree. F. Typical catalytic cracking conditions are set
forth below in table IV.
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table iv
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catalytic Cracking Conditions
Broad Preferred
__________________________________________________________________________
Temperature .degree.F. 850-1,000 900-950 Pressure, p.s.i.g. 0-50
5-25 Space velocity, v./hr./v. 0.5-10 l-5
__________________________________________________________________________
Suitable conventional cracking catalysts include amorphous types
and mixtures of amorphous types with molecular sieves. Specific
examples include silica-alimina, silica-magnesia, silica-zinconia
and silica-alumina mixed with a minor proportion of a synthetic
crystalline aluminosilicate zeolite such as Type X or Type Y
Zeolite.
It is known that catalytic cracking produces olefin hydrocarbons
which are not desirable in gasoline. These may be saturated by
passing the cracked products through hydrotreater 2. In this
embodiment valves 21 and 22 are manipulated to pass all or part of
the cracked products via line 23 into line 1 and then into the
hydrotreater. The saturated olefins are then recovered from the
atmospheric distillation tower.
EXAMPLE 1
This example describes hydrotreating of 50,000 B/SD Rainbow crude
oil in conjunction with catalytic cracking of the hydrotreated gas
oil from the crude. The gas oil boils in the range of 650.degree.
to 1,050.degree. F. The object of the example is to demonstrate the
production of products that are acceptable without further
treatment for processing in a catalytic hydroformer and for
blending into motor gasoline, heating oil and heavy fuel oil.
The hydrotreating operation is carried out at preferred conditions
of 700.degree. F., 800 p.s.i.g and 1.0 LHSV (based on total volume
of crude and cracked distillate), and 1000 s.c.f. of hydrogen per
barrel of oil. The catalyst is sulfided cobalt molybdate supported
on silica-stablized alumina.
Table V below shows the characteristics of the crude oil as well as
the characteristics of the naphtha, reformer feed and middle
distillate cuts obtained from fractionating the hydrotreated oil.
##SPC1##
The light naphtha is free of mercaptans and has a high octane
response to tetraethyl lead because of its low sulfur content. The
reformer feed contains only 3 p.p.m. of sulfur and 1 p.p.m. of
nitrogen. Because of these low sulfur and nitrogen levels, this
material is suitable for direct reforming in the presence of a
platinum catalyst without the usual hydrofining treatment. The
middle distillate fraction contains only 0.10 weight percent sulfur
and thus the sulfur content is well below the requirements
necessary for minimizing air pollution.
Table VI lists the quality data for 13,900 barrels per day of
catalytic cracking feed and 4,100 barrels of vacuum pitch obtained
from 50,000 barrels a day Rainbow crude. Cracking catalysts are
very sensitive to nitrogen and this cracking feed contains only
about 0.06 weight percent nitrogen. Metals are also very low,
assuring minimum catalyst contamination in this respect. The
preferred cracking conditions are 900.degree. to 950.degree. F.
reactor temperature, 5 to 20 p.s.i.g. pressure, a regeneration
temperature of 1,100.degree. F. and a space velocity of 1 to 5
WHSV. The conversion to naphtha and lighter materials is about 60
percent the conversion to materials boiling at less than
700.degree. F. will exceed 98 percent. The pitch is a suitable low
sulfur fuel oil or fuel oil component for blending.
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TABLE VI
Column 1 2
__________________________________________________________________________
Stock Cat Feed Pitch
__________________________________________________________________________
B/SD 13,900 4,100 Cut Point, .degree.F. 700/1,050 1,050+ API
Gravity 27 18 Sulfur, Wt. % 0.30 0.74 Nitrogen Wt. % 0.06 Metals,
Iron p.p.m. o.3 6 Nickel 0.1 4 Vanadium 0.1 2 Conradson Carbon 0.09
11.4 Aromatic Rings, Wt. % 7.9
__________________________________________________________________________
EXAMPLE 2
This example describes hydrotreating a blend of 35 percent
Federated crude, 35 percent Rainbow crude, 15 percent Pembina and
15 percent Redwater crude. The 650.degree. to 950.degree. F.
hydrotreated gas oil fraction is cracked without additional
hydrofining. Hydrotreating conditions are more severe than those of
example 1. Preferred conditions are 700.degree. F., 1,500 p.s.i.g.,
0.8 LHSV and 2,500 s.c.f. hydrogen per barrel. The catalyst is
preferably sulfided nickel molybdate on an alumina support. Quality
data on the crude oil blend on the fractions from the hydrotreated
crude are given in table VII. The light naphtha and middle
distillate fractions are acceptable for blending into finished
products. The hydrotreated gas oil is hydrocracked at 720.degree.
F., 1,500 p.s.i.g. pressure, 1.5 v./v./hr. space velocity and 6,000
s.c.f. H.sub.2 /B. The catalyst is preferably nickel tungsten on
faujasite. The hydrocracked product is distilled in admixture with
the hydrofined crude oil. ##SPC2##
The integrated processing scheme described herein consolidates all
hydrofining operations in a single unit substantially reducing
investment and operating costs.
* * * * *