U.S. patent application number 14/931154 was filed with the patent office on 2017-05-04 for process for the production of petroleum tar pitch for use as a binder in the production of electrodes.
This patent application is currently assigned to INTEVEP, S.A.. The applicant listed for this patent is Intevep, S.A. Invention is credited to David Barros, Alexis Lira, Alejandra Marval, Yrem Muller, Mirian Rosas.
Application Number | 20170121834 14/931154 |
Document ID | / |
Family ID | 58635471 |
Filed Date | 2017-05-04 |
United States Patent
Application |
20170121834 |
Kind Code |
A1 |
Lira; Alexis ; et
al. |
May 4, 2017 |
PROCESS FOR THE PRODUCTION OF PETROLEUM TAR PITCH FOR USE AS A
BINDER IN THE PRODUCTION OF ELECTRODES
Abstract
A process for the production of petroleum tar pitch with the
using a fresh hydrocarbon feedstock, preheating it, treating the
heated feedstock and passing fractionating the treated feedstock
into gases, light distillates and a bottom fractionation stream,
then dividing the bottom fraction stream into a recycle stream and
a cracked fraction stream and using the cracked fraction stream in
a reduced pressure distillation tower so that the light cracked
fraction is fractionated light vacuum gas oil, heavy vacuum gas oil
and a high quality petroleum tar pitch.
Inventors: |
Lira; Alexis; (Caracas,
VE) ; Rosas; Mirian; (Caracas, VE) ; Barros;
David; (San Antonio de los Altos, VE) ; Muller;
Yrem; (Caracas, VE) ; Marval; Alejandra; (Los
Teques, VE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Intevep, S.A |
Caracas |
|
VE |
|
|
Assignee: |
INTEVEP, S.A.
Caracas
VE
|
Family ID: |
58635471 |
Appl. No.: |
14/931154 |
Filed: |
November 3, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25C 7/02 20130101; C10C
3/06 20130101; C10G 50/00 20130101 |
International
Class: |
C25C 7/02 20060101
C25C007/02; C10G 50/00 20060101 C10G050/00; C10C 3/06 20060101
C10C003/06 |
Claims
1. A process for the production of petroleum tar pitch comprising:
a. providing a fresh hydrocarbon feedstock; b. pre-heating at least
a portion of the feedstock in a furnace to a temperature of about
380.degree. to 480.degree. C.; c. feeding at least a portion of the
heated feedstock to a reactor and treating at least a portion of
the heated feedstock in the reactor under controlled conditions so
as to promote condensation and polymerization reactions; d. passing
at least a portion of the treated feedstock to a fractionating
tower wherein at least a portion of the treated feedstock is
fractionated into (1) gases, (2) light distillates and (3) a bottom
fractionation stream; e. dividing the bottom fraction stream into a
recycle stream and a cracked fraction stream; f. feeding the
cracked fraction stream to a reduced pressure distillation tower
wherein the light cracked fraction is further fractionated into (1)
light vacuum gas oil, (2) heavy vacuum gas oil and (3) a high
quality petroleum tar pitch; g. recycling the recycled stream and
admixing the recycle stream with the fresh feedstock; and h. mixing
the petroleum tar pitch with a refining element in the form of
anode grade coke, to create a petroleum tar pitch product.
2. A process according to claim 1 wherein the feedstock is a highly
aromatic hydrocarbon selected from the group consisting of
catalytic cracking decanted oil, lubricant extract, Heavy Coker
Gasoil (HCGO), Heavy Vacuum Gasoil (HVGO) and mixtures thereof and
has the following composition and properties: [Density@15.degree.
C., (gr/cc) 0.8-1.15 Solids Content, (wt. %) 0-0.1 Aromatics, (wt.
%) 54-85].
3. A process according to claim 1 wherein the light vacuum gas oil
has the following properties: [ASTM D-86 Initial Boiling Point,
.degree. C. 170-220 ASTM D-86 Final Boiling Point, .degree. C.
300-360 API Gravity 18-28 Aromatics, wt. % 45-80].
4. A process according to claim 1 wherein the heavy vacuum gas oil
has the following properties: [ASTM D-1160 Initial Boiling Point,
.degree. C. 250-320 ASTM D-1160 Final Boiling Point, .degree. C.
450-520 API Gravity 0-9 Aromatics, wt. % 45-95].
5. A process according to claim 1 wherein the petroleum tar pitch
has the following properties: [Conradson Carbon, (wt. %) 40-60
Density@15.degree. C., (gr/cc) 1.20-1.25 Mettler Softening Point,
(.degree. C.) 100-125 Quinoline Insoluble, (wt. %) 0-10].
6. A process according to claim 1 wherein the refining element
added is anode grade coke and it is added in an amount of between 5
to 20 wt. % of the petroleum pitch.
7. A process according to claim 1 wherein the finely divided anode
grade coke has the following properties: [Average Particle Size,
microns 12-110 Apparent Bulk Density, gr/cc 0.46-0.65 Water
Content, wt. % 0-0.2 Oil Absorption, cc/100 gr 60-75].
8. A process according to claim 1 wherein the petroleum tar pitch
product is delivered to a finishing station to be shaped.
9. A process according to claim 1 wherein at least a portion of the
feedstock is filtered to produce a feedstock having a solid content
of 100 ppmw.
10. A process according to claim 9 wherein the filtering is done by
centrifugal, electrostatic or mechanical techniques.
11. A process according to claim 9 wherein the filtering removes at
least 99% of solids.
12. A process according to claim 9 wherein the filtered feedstock
has the following composition and properties: [Conradson Carbon,
(wt. %) 0-7 Density@15.degree. C., (gr/cc) 0.8-1.1 Solids Content
(wt %) 0-0.01 Aromatics, (wt. %) 54-85].
13. A process according to claim 9 wherein the filtered feedstock
is heated to a temperature of between 380 and 480.degree. C. to
provide a heated feedstock.
14. A process according to claim 13 wherein the heated feedstock is
passed to a soaker reactor, plug flow reactor or batch reactor, and
wherein the feedstock is treated in the reactor at condensation and
polymerization conditions to provide a treated feedstock.
15. A process according to claim 14 wherein the conditions include
a temperature between 360 and 460.degree. C., a pressure between
1480 and 1825 kpA, the conditions are oxygen free and inert and are
held between 0.25 and 5 hours.
16. A process according to claim 14 wherein the treated feedstock
is passed to a fractionating tower wherein the treated feedstock is
fractionated into (1) gases, (2) light distillates and (3) a bottom
stream.
17. A process according to claim 1 wherein step (d) takes place
under the following conditions: [Temperature, .degree. C. 330-430
Pressure, kPa 101-850 in an inert environment and substantially
oxygen free].
18. A process according to claim 16 wherein the treated feedstock
is fractionated to yield: 2 to 8 wt. % C.sub.4-gases 3 to 8 wt. %
light distillates having an ASTM D-86 cut point of between
92.degree. C. and 220.degree. C. based on fresh feed and a bottom
stream.
19. A process according to claim 16 wherein the bottom stream is
divided into a recycle stream and a cracked fraction bottom
stream.
20. A process according to claim 19 wherein the cracked fraction
bottom stream has the following composition and properties:
[Conradson Carbon, (wt. %) 10-18 Density@15.degree. C., (gr/cc)
1.1-1.15 Solids Content, (wt. %) 0-0.01 Aromatics, (wt. %) 70-95
Softening Point, (.degree. C.) <25].
21. A process according to claim 19 wherein the recycle stream is
admixed with the filtered feedstock in a preferred ratio of between
2:1 and 3:1 by volume of recycle stream to fresh feedstock.
22. A process according to claim 19 wherein the recycle stream is
mixed with the filtered feedstock.
23. A process according to claim 19 wherein the recycle stream is
mixed with the filtered feedstock in a ratio of up to 3:1 by volume
recycle stream to fresh feedstock.
24. A process according to claim 19 wherein the cracked bottom
stream is further fractionated to yield Light Vacuum Gas Oil, Heavy
Vacuum Gas Oil and a high quality petroleum tar pitch.
25. A process according to claim 24 wherein the cracked bottom
stream is further fractionated under the following conditions:
bottom fractionator temperature 300-380.degree. C., 0.3-15 kPa
pressure, in an inert and a substantially oxygen free
environment.
26. A process according to claim 24 wherein the cracked bottom
stream is further fractionated to yield the following products:
[ASTM D-1160 End Point Wt. % Light Vacuum Gas Oil 300-360.degree.
C. 15-25 Heavy Vacuum Gas Oil 450-570.degree. C. 30-50 Petroleum
Tar Pitch 15-50].
27. A process according to claim 24 wherein the Heavy Vacuum Gas
Oil is recycled into the filtered feedstock in a ratio from about
0.25:1 by volume recycle stream to fresh feedstock.
28. A process according to claim 24 wherein the heavy vacuum gas
oil is recycled into the filtered feedstock in a ratio of about
between 0.5:1 to 0.8:1 by volume recycle stream to fresh
feedstock.
29. A process according to claim 1 wherein the refining element
further comprises fine divided carbon black.
30. A process according to claim 1 wherein the refining element
further comprises anode grade coke and low metals and sulfur
content coke.
Description
BACKGROUND OF THE INVENTION
[0001] High quality petroleum tar pitch can be used in a variety of
applications. One of the most important uses for high quality
petroleum tar pitch is in the manufacture of anodes made from
calcined petroleum coke and a binder pitch. The anodes are used in
the production of primary aluminum. Presently anodes for use by the
aluminum and steel industries are manufactured employing almost
exclusively coal tar pitch as the binder. There have been many
attempts in the past to produce petroleum tar pitch suitable for
use as a binder in the manufacture of electrodes.
[0002] In the metallurgical industry, the electrodes are made from
petroleum coke and pitch binder. Pitch typically requires the
presence of quinoline, and a high residual carbon content. The
addition of carbon black into pitch tar is typically done to
increase residual carbon and Quinoline insoluble content.
[0003] None of the foregoing processes have been able to produce
commercial petroleum tar pitch suitable for use as a binder in the
manufacture of electrodes for the aluminum and steel industries. It
is highly desirable to provide a process for the production of high
quality petroleum tar pitch which would allow for the economic
production of pitch suitable for the manufacture of electrodes.
[0004] Further objects and advantages of the present invention will
appear hereinbelow.
SUMMARY OF THE INVENTION
[0005] The invention is drawn to a process for the production of
petroleum tar pitch by first obtaining a fresh hydrocarbon
feedstock and then feeding that feedstock to a pre-heater and
thereafter feeding a soaker reactor for treatment under controlled
conditions so as to promote condensation and polymerization
reactions. The treated feedstock is thereafter passed to a
fractionating tower wherein the feedstock is fractionated into
gases, light distillates and bottom fraction, then dividing the
bottom fraction stream into a recycle stream and a cracked fraction
stream, then feeding the cracked fraction stream to a reduced
pressure distillation tower wherein the cracked fraction stream is
further fractionated into (1) light vacuum gas oil, (2) heavy
vacuum gas oil and (3) a high quality petroleum tar pitch, of a
quality suitable for use as a binder in the manufacture of
electrodes, the petroleum tar pitch is then mixed with a refining
element such as anode grade coke to improve the desired petroleum
tar pitch product and finally recycling the recycle stream and
admixing the recycle stream with the fresh feedstock
[0006] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWING
[0007] The FIGURE is a schematic flow diagram illustrating the
process of the present invention.
DETAILED DESCRIPTION
[0008] The present invention is drawn to a process for the
production of high quality petroleum tar pitch for use as a binder
in the manufacture of electrodes for the aluminum and steel
industries. The characteristics of a high quality petroleum tar
pitch are the following: [0009] [Conradson Carbon, (wt. %) 40-60
[0010] Density@15.degree. C., (gr/cc) 1.20-1.25 [0011] Mettler
Softening Point, (.degree. C.) 100-125 [0012] Quinoline Insoluble,
(wt. %) 0-10]
[0013] With reference to the FIGURE, as shown a fresh feedstock is
delivered via line 20 for treatment in the process of the present
invention. The fresh feedstock is preferably a highly aromatic
hydrocarbon stream. Feedstocks suitable and preferred for the
process of the present invention are characterized by the following
composition and properties: [0014] [Density@15.degree. C., (gr/cc)
0.8-1.15 [0015] Solids Content, (wt. %) 0-0.1 [0016] Aromatics,
(wt. %) 54-85].
[0017] Suitable hydrocarbon feeds include highly aromatic
hydrocarbon selected from the group consisting of catalytic
cracking decanted oil, lubricant extract, Heavy Coker Gasoil
(HCGO), Heavy Vacuum Gasoil (HVGO) and mixtures thereof.
[0018] The fresh feedstock as defined above can, if desired, be
delivered to a filtering station 1 wherein the hydrocarbon stream
is filtered so as to remove excess undesirable solids so as to
produce a filtered clean stream. In accordance with the present
invention it is desired that the product treated in the process of
the present invention have a solids content of between 0 to 0.01
wt. %. By filtering the fresh feed, the desired solid content can
be obtained. Typical filtration techniques such as centrifugal,
electrostatic or mechanical techniques can be used in the filtering
station 1. These techniques are sufficient to remove at least 99%
of the undesirable solids in the fresh feed stream. The filtered
stream preferably has the following properties: [0019] [Conradson
Carbon, (wt. %) 0-7 [0020] Density@15.degree. C., (gr/cc) 0.8-1.1
[0021] Solids Content (wt %) 0-0.01 [0022] Aromatics, (wt. %)
54-85]
[0023] The clean filtered stream is thereafter fed via line 21 to a
heater 2 wherein the stream is pre-heated. It is desirable in the
process of the present invention to mix the filtered stream with a
recycle stream in a manner to be described hereinbelow.
[0024] The stream fed to the heater or furnace 2 is pre-heated to a
temperature of between 380.degree. and 480.degree. C. and
thereafter is delivered via line 23 to a soaker type reactor 3. The
heated feedstock is treated in the soaker reactor 3 at a
temperature of from about 360.degree. to 460.degree. C., a pressure
of from about 1480 to 1825 kpa and a residence time of from about
0.25 to 5 hours. This treatment allows condensation and
polymerization reactions to take place in the soaker reactor. It is
preferred that the treatment in both the heater furnace and soaker
reactor take place in an oxygen-free environment and, preferably an
inert environment.
[0025] The treated stream from the soaker 3 is delivered via line
24 to a fractionating tower 4 where the feedstock is fractionated
into gases, which are taken off via line 25, light distillates
which are taken off via line 26 and a bottom fraction stream which
is taken off via line 27. The fractionator is operated under the
following operating conditions: a bottom fractionator temperature
of from about 330.degree. to 430.degree. C. and a pressure of from
about 101 to 850 kPa.
[0026] The yields from the fractionating tower 4 comprises 2 to 8
wt. % C4 -gases and 3 to 8 wt. % light distillates having an ASTM
D-86 cut point of between 92.degree. C. and 220.degree. C. based on
fresh feed. It is preferred that the treatment in the fractionating
tower 4 take place in an oxygen free environment and, preferably,
an inert environment.
[0027] The bottom fraction drawn off through line 27 is a cracked
fraction bottom stream having the following composition and
properties: [0028] [Conradson Carbon, (wt. %) 10-18 [0029]
Density@15.degree. C., (gr/cc) 1.1-1.15 [0030] Solids Content, (wt.
%) 0-0.01 [0031] Aromatics, (wt. %) 70-95 [0032] Softening Point,
(.degree. C.) <25]
[0033] In the preferred embodiment of the present invention, a
portion of the cracked fraction bottom stream is recycled back to
heater 2 or soaker reactor 3 and the remainder is further
fractionated in the manner discussed hereinafter.
[0034] The portion of cracked fraction forming the recycle stream
is preferably recycled via line 28 where it is admixed with the
fresh feed prior to delivery of the feed to the furnace 2. In
accordance with the present invention, the recycle delivered via
line 28 is mixed with the fresh feed in a ratio of up to 3:1 by
volume of recycle to fresh feed and preferably in a ratio of about
between 2:1 to 3:1. Recycling of the heavy cracked fraction via
line 28 is highly desirable in order to optimize the resulting
pitch properties obtained in the process of the present invention
upon further fractionation.
[0035] The remainder of the cracked fraction is delivered via line
29 to a further fractionating unit 5 such as a reduced pressure
distillation tower wherein the cracked fraction is further
fractionated into light vacuum gas oil taken off via line 30, heavy
vacuum gas oil taken off via line 31 and petroleum tar pitch taken
off line 33. The cracked fraction is fractionated in distillation
unit 5 at a bottom fractionator temperature of between 300.degree.
to 380.degree. C. and a pressure of between 0.3 to 15 kPa and
preferably in an oxygen-free environment. The petroleum tar pitch
resulting from the process of the present invention and drawn off
via line 33 is a high quality petroleum pitch having the following
properties: [0036] [Conradson Carbon, (wt. %) 40-60 [0037]
Density@15.degree. C., (gr/cc) 1.20-1.25 [0038] Mettler Softening
Point, (.degree. C.) 100-125 [0039] Quinoline Insoluble, (wt. %)
0-10]
[0040] This petroleum tar pitch is of high quality and suitable for
use as a binder in the manufacture of electrodes.
[0041] The yield of light vacuum gas oil taken off line 30 is
between 15 to 25 wt. %, the yield of heavy vacuum gas oil taken off
line 31 is from 30 to 50 wt. % and the yield of petroleum tar pitch
taken off line 33 is between 10 to 50 wt. % with all yields being
based on fresh feed. The light vacuum gas oil has an ASTM D-86 end
boiling point of between 300.degree. to 360.degree. C. and the
heavy vacuum gas oil has an ASTM D-1160 end boiling point of
between 450.degree. to 570.degree. C.
[0042] The petroleum tar pitch taken off via line 33 can, if
desired, be delivered to a mixer 6 where it is mixed with an
additive selected from the group consisting of fine divided anode
grade coke, carbon black, or mixtures thereof via line 36. In
accordance with the present invention it is desirable to use the
light vacuum gas oil taken off line 30 and heavy vacuum gas oil
taken off line 31 as the additive to the mixture 6. It is preferred
that the light vacuum gas oil or the heavy vacuum gas oil be mixed
with the pitch in an amount of between 3 to 15 volume percent. The
preferred light vacuum gas oil has the following composition and
properties: [0043] [ASTM D-86 Initial Boiling Point, .degree. C.
170-220 [0044] ASTM D-86 Final Boiling Point, .degree. C. 300-360
[0045] API Gravity 18-28 [0046] Aromatics, wt. % 45-80] The
preferred heavy vacuum gas oil has the following composition and
properties: [0047] [ASTM D-1160 Initial Boiling Point, .degree. C.
240-390 [0048] ASTM D-1160 Final Boiling Point, .degree. C. 450-580
[0049] API Gravity 1-4 [0050] Aromatics, wt. % 45-80]
[0051] The heavy vacuum gas oil can also be recycled into the
filtered feedstock in a ratio of at least about 0.25:1 by volume
recycle stream to fresh feedstock, but preferably a ratio of about
between 0.5:1 to 0.8:1 by volume recycle stream to fresh
feedstock.
[0052] A finely divided anode grade coke, carbon black, or mixtures
thereof is admixed with the petroleum pitch in mixer 6. The
proportion of the anode grade coke, carbon black, or mixtures
thereof mixed with the petroleum pitch should be between 5 to 20
wt. %. Suitable anode grade coke, carbon black, or mixtures thereof
for use in the process of the present invention has the following
properties: [0053] [Average Particle Size, microns 12-110 [0054]
Apparent Bulk Density, gr/cc 0.46-0.65 [0055] Water Content, wt. %
0-0.2 [0056] Oil Absorption, cc/100 gr 60-75]
[0057] The refining additives delivered via line 36 to mixer 6 have
the effect to increase Quinoline insoluble content, conradson
carbon and softening point. An additive of light vacuum gas oil or
heavy vacuum gas oil improves the wettability of the pitch which
would reduce the temperature and mixing time necessary when mixed
with calcining petroleum coke during the manufacture of electrodes.
The modified petroleum pitch product can be delivered via line 34
to a finishing station 7 where it is shaped as pencils or flakes
prior to being sent to storage via line 35.
[0058] The use of anode grade coke as additive refined with the
heavy vacuum gasoil showed improvements in the anodes properties.
The use of anode grade coke of the present invention is preferred
for multiple reasons. The availability of the product, the low
nickel and vanadium content, and the fact that it does not add
other foreign agents to the anode. The product performed well
during mixing and therefore resulted in excellent quality aluminum.
It is for these reasons that anode grade coke was chosen as the
preferred refining element
[0059] Further, in order to decrease the deposition of solids, a
reduction of residence time was implemented and an additional
recycling of a cleaner stream with less contaminant content was
introduced through line 32.
[0060] The process of production of tar pitch is a moderate thermal
cracking process, which uses polymerization reactions, cracking and
condensation to transform the load in a binder. The recycling step
is important because it increases the conversion rate and the
production of binder pitch.
[0061] It is to be understood that the invention is not limited to
the illustrations described and shown herein, which are deemed to
be merely illustrative of the best modes of carrying out the
invention, and which are susceptible of modification of form, size,
arrangement of parts and details of operation. The invention rather
is intended to encompass all such modifications, which are within
its spirit and scope as defined by the claims.
* * * * *