U.S. patent number RE28,974 [Application Number 05/412,159] was granted by the patent office on 1976-09-21 for process for making carbon black.
This patent grant is currently assigned to Cabot Corporation. Invention is credited to Merrill E. Jordan, Allan C. Morgan.
United States Patent |
RE28,974 |
Morgan , et al. |
September 21, 1976 |
Process for making carbon black
Abstract
A process is provided for making high-quality carbon blacks at
unusually good yields in a highly compact reaction space. The key
steps of the process are the generation of a very hot combustion
gas stream moving at very high speed in essentially plug flow by
burning a hydrocarbon gas in oxygen in a compact combustion zone
under conditions of very high heat release assuring the attainment
of temperatures of over 3,000.degree. F., and the transverse
injection into said highspeed combustion stream from the periphery
thereof of a plurality of individual streams of liquid hydrocarbon
make, each of which is injected under sufficient pressure to cause
same to enter said high-speed combustion stream at a linear
velocity of more than about 100 fett per second. Preferably, a
highly oxygen-enriched oxidant is used to burn the hydrocarbon
gas.
Inventors: |
Morgan; Allan C. (Sudbury,
MA), Jordan; Merrill E. (Walpole, MA) |
Assignee: |
Cabot Corporation (Boston,
MA)
|
Family
ID: |
27021653 |
Appl.
No.: |
05/412,159 |
Filed: |
November 2, 1973 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
606665 |
Jan 3, 1967 |
03619140 |
Nov 9, 1971 |
|
|
Current U.S.
Class: |
423/450; 422/150;
423/457; 423/455 |
Current CPC
Class: |
C01B
33/183 (20130101); C01G 23/07 (20130101); C09C
1/50 (20130101); C01P 2006/12 (20130101); C01P
2006/19 (20130101); C01P 2006/60 (20130101) |
Current International
Class: |
C01B
33/18 (20060101); C01B 33/00 (20060101); C01G
23/00 (20060101); C01G 23/07 (20060101); C09C
1/44 (20060101); C09C 1/50 (20060101); C09C
001/50 () |
Field of
Search: |
;423/455,456,457,450
;23/259.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Meros; Edward J.
Attorney, Agent or Firm: Schuyler, Birch, Swindler, McKie
& Beckett
Claims
What is claimed is:
1. A process for making high-quality carbon black at unusually good
yields and high volumetric production rates comprising
a. burning a hydrocarbon gas in oxygen in a compact combustion zone
under high-intensity conditions so as to generate a stream of
combustion gases having a temperature of over 3,000.degree. F. and
moving in essentially plug flow as it leaves the downstream end of
said combustion zone at an exit velocity of at least about 2,000
feet per second,
b. injecting transversely into said exiting stream of hot
combustion gases from the periphery thereof a plurality of
individual .Iadd.coherent .Iaddend.streams of hydrocarbon liquid
make under sufficient pressure to cause same to enter said exiting
stream at a linear velocity of more than about 100 feet per second,
and
c. quenching the resultant reaction mixture after carbon formation
has occurred.
2. A process as defined in claim 1 wherein the initial direction of
said injected streams of hydrocarbon liquid is substantially normal
to the direction of flow of said exiting stream of hot combustion
gases.
3. A process as defined in claim 1 wherein the combustion step (a)
of the process is carried out under conditions to achieve
substantially sonic velocity of the combustion gases as they leave
the downstream end of the combustion zone. .Iadd. 4. A process for
making high-quality carbon black at unusually good yields and high
volumetric production rates comprising:
a. establishing a turbulent, high velocity stream of combustion
gases in a compact combustion zone, said stream as it exits the
downstream end of said combustion zone having a temperature of over
3,000.degree. F. and moving in essentially plug flow at a rapid
velocity capable of shearing individual streams of hydrocarbon
liquid make injected thereinto as described in (b) below,
b. injecting transversely into said exiting stream of hot
combustion gases from the periphery thereof a plurality of
individual coherent streams of hydrocarbon liquid make under
sufficient pressure to cause same to enter said exiting stream at a
high linear velocity sufficient to assure rapid dispersal of said
hydrocarbon liquid make at a position sufficiently remote from the
hot walls of said injection zone to prevent smearing and coking of
the injected reactant on said walls, and
c. quenching the resultant reaction mixture after carbon formation
has occurred. .Iaddend..Iadd. 5. A process for making high-quality
carbon black at unusually good yields and high volumetric
production rates comprising:
a. burning a hydrocarbon with oxygen in a compact combustion zone
under high-intensity conditions so as to generate a turbulent, high
velocity stream of combustion gases having a temperature of over
3,000.degree. F., which stream, as it exits the downstream end of
said combustion zone, is moving in essentially plug flow at a rapid
velocity capable of shearing individual streams of hydrocarbon
liquid make injected thereinto as described in (b) below, and
b. injecting transversely into said exiting stream of hot
combustion gases from the periphery thereof a plurality of
individual coherent streams of hydrocarbon liquid make under
sufficient pressure to cause same to enter said exiting stream at a
high linear velocity sufficient to ensure rapid dispersal of said
hydrocarbon liquid make at a position sufficiently remote from the
hot walls of said injection zone to prevent smearing and coking
thereupon, and
c. quenching the resultant reaction mixture after carbon formation
has occurred. .Iaddend. .Iadd. 6. The process of claim 5 wherein
said hydrocarbon burned with oxygen is a hydrocarbon gas.
.Iaddend..Iadd. 7. The process of claim 4 wherein the velocity of
said stream of combustion gases is substantially sonic. .Iaddend.
Description
This invention relates to a novel burner for carrying out
combustion. The invention further relates to processes for making
pyrogenic solids which processes utilize the aforesaid novel
burner. In particular, the invention relates to novel processes and
apparatus for making carbon black.
Almost all commercial carbon black is presently provided by those
major processing techniques i.e. the channel process, furnace
process, and thermal process. Each of these processes have certain
limitations and result in blacks having unique properties which
distinguish them from the blacks produced by other processes.
Channel blacks have high rubber-reinforcing ability and extremely
good color intensity. The most intense color is obtained with
blacks having a diameter of about 90 angstroms, and intenseness of
the color gradually decreases as the particle diameter increases.
The color of furnace black usually ranges from a scale of about 84
to 96 and is less intense than the color of black produced by the
channel process described above. However, structure as determined
by ability to reinforce rubber, is greater in the blacks produced
in the furnace process than those produced by the channel process.
Thermal blacks have a much larger particle size than either channel
or furnace blacks, less rubber-reinforcing ability than either
channel or furnace blacks, and relatively poor color properties.
What makes the thermal blacks useful at all is the fact that their
low surface area and spherical particle shape adapts them for easy
incorporation in elastomers and use as fillers. Other types of
carbon black cannot be incorporated into plastics in anywhere near
the high loadings obtainable by use of thermal blacks.
The blacks having darker color are much more expensive to produce
than an equivalent quantity of thermal black.
It is seen from the above that each carbon black process produces a
black having particularly distinguishable physical properties and
also having distinguishable economic limitations.
The economic limitations are primarily due to the necessity of
operating at very high "percent combustion" when low scale, i.e.
high color, carbon blacks are manufactured.
The term "percent combustion" is, as will be understood by those
skilled in the art, a measure of the oxygen made available during a
given run relative to the amount required to satisfy the complete
oxidation of hydrocarbons present in the carbon-forming zone to
carbon dioxide and water.
In a number of commonly owned and copending applications (i.e. Ser.
Nos. 560,524 now abandoned, 560,705, now U.S. Pat. No. 3,443,901
filed June 27, 1966 by Wendell, Jordan, Burbine and Shelvey and
560,771 filed June 27, 1966 by Jordan, Wendell, Dannenberg and
Hardy and since refiled as Ser. No. 817,262), a number of novel and
compact apparatus and processes have been disclosed useful for
among other things, utilizing oxygen-enriched combustion to
facilitate production of a variety of novel carbon blacks and also
to produce a very wide range of blacks having properties which
include both those normally associated with channel blacks and
those normally associated with furnace blacks.
While a principal object of the instantly disclosed invention is to
provide apparatus and processes for improving oxygen-enriched
carbon-black processes still further, the instant invention is
based on utilization of novel burner apparatus which may also be
advantageously utilized in other chemical processing arts ranging
from the carrying out of combustion reactions to achieve an
extraordinary concentration of heat output to the advantageous
production of pyrogenic chemicals like titania, alumina and the
silica.
Thus, it is an object of the invention to provide an extraordinary
compact and high-rate burner capable of achieving extremely high
heat release within a very limited space.
Secondly, it is an object of the invention to provide means for
producing, at very high rates, pyrogenic products such as pyrogenic
oxides and carbon black.
It is a further object of the invention to provide a burner that
performs substantially adiabatically when utilized for combustion
of hydrocarbon with oxygen.
Moreover, it is a further object of the invention to provide means
for controlling the properties of carbon black produced by the
process of the invention and, in particular, means for controlling
the structure, surface area, and color properties of the black.
A further object of the invention is to achieve this control with
relatively little sacrifice in economical operation of the
carbon-forming process.
Other objects of the invention are in part obvious or in part set
forth below.
Applicants have achieved their objects by combining a vortex-type
burner capable of operation at an extremely high combustion rate
with a unique reactant feeding method.
In the specification and in the accompanying drawings are shown and
described an illustrative embodiment of the invention;
modifications thereof are indicated, but it is to be understood
that these are not intended to be exhaustive nor limiting of the
invention, but on the contrary are given for the purposes of
illustration in order that others skilled in the art may fully
understand the invention and the manner of applying it in practical
applications. The various objects, aspects and advantages of the
present invention will be more fully understood from a
consideration of the specification in conjunction with the
accompanying drawings.
In the drawings:
FIG. 1 is an elevation, partially in section, of a vortex burner of
the invention.
FIG. 2 is a schematic elevational view of the burner of FIG. 1 in
conjunction with further elements forming novel apparatus useful in
the manufacture of pyrogenic materials.
Referring to FIG. 1, it is seen that the apparatus described
therein comprises a burner 10 having a tangential entry port 12 and
an axial port 14. Port 12 feeds into an annular frustoconical flow
path 16 which discharges into throat section 19 of burner 10. Walls
18 of burner 10 diverge upwardly at divergent angle of about
5.degree. with the vertical before converging to form a relatively
narrow outlet 2 through which combustion gases may exit from the
enclosed combustion chamber 21.
An astonishing advantage of the high combustion rate burner
illustrated in FIG. 1 is that extraordinarily high heat output per
unit volume is achievable. For example, heat outputs of between
5.times.10.sup.8 and 10.times.10.sup.8 B.t.u. per hour per cubic
foot have been achieved when utilizing this burner with oxygen and
hydrocarbon gas feed.
In a typical example, with 800 cubic feet per hour of natural gas
having a fuel value of 1,000 B.t.u. per cubic foot and 1,600 cubic
feet per hour of oxygen. The heat output of the burner was
calculated at 800,000 B.t.u. per hour and 5.6.times.10.sup.8 B.t.u.
per hour per cubic foot of burner volume.
Moreover, this high heat output is achieved with a largely
adiabatic operation. Thus an even larger concentration of heat than
might ordinarily be expected from the indicated massive heat
release is delivered to the outlet of the burner.
It has been discovered that high heat release obtainable from
burners such as that illustrated in FIG. 1 are particularly useful
in the production of pyrogenic materials.
For such uses, it has been found particularly advantageous to have
combustion products from burner 10 carried through an adjacent
reactant-injection member 23 mounted immediately at outlet 20.
Member 23 comprises a cylindrical reactant feed chamber into which
reactants are supplied through conduit 27. Three holes 29 are
spaced around reacting injection zone 31 formed by member 23. It is
through these holes 29 that reactants are radially injected at high
velocities into zone 31. It has been found that such high
velocities promote rapid dispersal and evaporation of the injected
reactant in the stream of combustion products.
Among pyrogenic materials which can be formed in the apparatus are
carbon black, and such metallic oxide as silica, titania and
alumina; for example a hydrolizable salt of titania and alumina;
for example a hydrolizable salt of titanium such as TiCl.sub.4 may
be converted to titania.
In the formation of carbon black it has been found to be especially
desirable to inject the oil through holes 29 at an average linear
velocity of more than about 100 feet per second. Average linear
velocity of the combustion products at outlet 20 is desirably at
least about 3,500 feet per second. This velocity is approximately
at MACH 1 and is temperature dependent.
The high oil injection velocity not only prevents the smearing of
injected reactant along the walls of injection zone 31 but also
promotes the rapid dispersal and/or evaporation of the
reactant.
It has been discovered that the high-veolcity gas flow and high
heat concentrations achievable when the instant invention is
utilized allows an extremely rapid dispersal and evaporation of
hydrocarbon feedstock injected around the periphery of zone 31.
Furthermore the turbulent plug flow downstream of the hydrocarbon
injection area enables a more definite and uniform quench of the
carbonaceous product. Thus, the large amount of recirculation
present in conventional furnaces is entirely avoided.
In a typical embodiment of the invention, for example in each of
working examples 1 through 5, the nozzle is of the solid-cone
(30.degree. angle) spray pattern type and has an orifice of about
0.025 inches diameter. In some applications, the spinner assembly
of the nozzle can be removed and the 30.degree. cone is transformed
into a stream. The nozzle used in working examples 1 through 5 is
sold under the trade designation WDB series by the Delavan Company,
and has nominal discharge capacities of 2.8 gallons per hour at 40
p.s.i.g., 3.9 gallons per hour at 75 p.s.i.g., 5 gallons per hour
at 125 p.s.i.g., and 10 gallons per hour at 500 p.s.i.g.
These nozzle characteristics are described here only to complete
the description of the apparatus used and to indicate the type of
velocities required to avoid coking of heavy hydrocarbons when
injected into zone 31. Small holes without nozzles are also
usefully employed and are preferred for injection into higher
velocity gas streams.
Quench nozzles were of similar design but of approximately twice
the capacity for a given pressure.
Aromatic HB is a typical carbon-black make oil and has been used in
all of the working examples. An analysis of an Aromatic HB sample
follows:
______________________________________ A.P.I. Gravity +13.1
Viscosity, S.S.U. (130.degree.F.) 33 Viscosity, S.S.U.
(210.degree.F.) 31 % Asphaltenes 0.12 % Ash 0.002 % Sulfur 0.15 H/C
Ratio 1.15 % Distilled Boiling Point Initial Boiling Point
419.degree.F. 10% 443 20% 447 30% 450 40% 455 50% 459 60% 466 70%
472 80% 480 90% 498 End Point 550
______________________________________
Referring to FIG. 2, it is seen that an oxidizing gas and a fuel
gas are admitted to burner 10 through conduits 14 and 12
respectively. The oxidizing gas and fuel gas react to form an
extremely hot and highly turbulent, but essentially a plug flow, of
gases into injection zones 31 formed of member 23. Into this
injection zone 31 through holes 29 is injected carbon-black make
which is transformed into a vaporous or gaseous material almost
immediately. Pressures in zone 31 usually range from above about 0
to about 50 p.s.i.g. Temperatures range from about 3,500.degree. to
about 5,000.degree. F. Velocities upstream of the oil injection
reach about 2,000 to about 3,500 f.p.s. Under such conditions
unusually large concentrations of small, highly unstable carbon
black-forming species are created. It is believed that the unique
advantages of the instant process are in large part attributable to
these concentrations which are extraordinary not only in respect to
the number found per unit volume but also in respect to mole
percent to total atoms present in the decomposition products
present in, and effluxing from, zone 31.
Efflux from zone 31 passes into integrated reaction zone 35 and is
quenched therein by water quench spray emanating from nozzles 37.
It is a particular advantage of the process thus described that a
great measure of control can be exerted over the carbon-black
product thereof by controlling the average residence time in which
the carbon-forming species are exposed to the heat flux in zone 31
and until the efflux from the zone is subjected to initial
quenching.
EXAMPLE 1
The apparatus shown in FIG. 2 and described above was utilized to
make carbon black. The furnace reaction zone was 6 inches in
diameter and 76 inches in length. One quench nozzle sold under the
trade designation Spraying Systems 300215 was positioned axially at
the end of the furnace to spray 20 gallons per hour of water.
The make oil was preheated to 250.degree. F. Oxygen (1,600 standard
cubic feet per hour) and natural gas (800 standard cubic feet per
hour) were combusted in the burner of FIG. 1 and passed into zone
31. The preheated carbon-black make oil was injected into zone 31
at a rate of 12.5 gallons per hour.
The make oil was injected at a pressure 120 p.s.i.g. to assure its
rapid evaporation at a position sufficiently remote from the hot
walls of zone 31 to avoid any coking thereupon.
The "percent combustion" was 29.1. Yield was 35 percent based on
total carbon feed.
The black obtained is hereafter identified as Black A.
EXAMPLE 2
The apparatus shown in FIG. 2 and described above was utilized to
make carbon black. The furnace reaction zone was 2.5 inches in
diameter and 36 inches in length. The same quench technique was
used as for working example 1.
The make oil was preheated to 245.degree. F. Oxygen (1,600 standard
cubic feet per hour) and natural gas (800 standard cubic feet per
hour) were combusted in the burner of FIG. 1 and passed into zone
31. The preheated carbon-black make oil was injected into zone 31
at a rate of 12.5 gallons per hour.
The make oil was injected at a pressure of 100 p.s.i.g. to assure
its rapid evaporation at a position sufficiently remote from the
hot walls of zone 31 to avoid any coking thereupon.
The "percent combustion" was 29.1. Yield was 40 percent based on
total carbon feed.
The black obtained is hereafter identified as Black B.
EXAMPLE 3
The apparatus shown in FIG. 2 and described above was utilized to
make carbon black. The furnace reaction zone was 1 inch in diameter
and 13 inches in length. Four nozzles were positioned peripherally
to spray 6.5 gallons of water each at the end of the furnace.
The make oil was preheated to 250.degree. F. Oxygen (1,600 standard
cubic feet per hour) and natural gas (800 standard cubic feet per
hour) were combusted in the burner of FIG. 1 and passed into zone
31. The preheated carbon-black make oil was injected into zone 31
at a rate of 12.5 gallons per hour.
The make oil was injected at a pressure 200 p.s.i.g. to assure its
rapid evaporation at a position sufficiently remote from the hot
walls of zone 31 to avoid any coking thereupon.
The "percent combustion" was 31.2. Yield was 31.3 percent based on
total carbon feed.
The black obtained is hereafter identified as Black C.
EXAMPLE 4
The apparatus shown in FIG. 2 and described above was utilized to
make carbon black. The furnace reaction zone was 1 inch in diameter
and 13 inches in length. Four quench nozzles were positioned
peripherally to spray about 6.5 gallons per hour of water each at a
position 13 inches down the furnace from the injection zone.
The make oil was preheated to 250.degree. F. Oxygen (1,600 standard
cubic feet per hour) and natural gas (200 standard cubic feet per
hour) were combusted in the burner of FIG. 1 and passed into zone
31. The preheated carbon-black make oil was injected into zone 31
at a rate of 16.7 gallons per hour.
The make oil was injected at a pressure 260 p.s.i.g. to assure it
rapid evaporation at a position sufficiently remote from the hot
walls of zone 31 to avoid any coking thereupon.
The "percent combustion" was 31.2. Yield was 35.8 percent based on
total carbon feed.
The black obtained is hereafter identified as Black D.
EXAMPLE 5
The apparatus shown in FIG. 2 and described above was utilized to
make carbon black. The furnace reaction zone was 1 inch in diameter
and 20 inches in length. Four quench nozzles were positioned
peripherally to spray about 8 gallons per hour of water each at a
position 13 inches down the furnace from the injection zone.
The make oil was preheated to 250.degree. F. Oxygen (1,600 standard
cubic feet per hour) and natural gas (200 standard cubic feet per
hour) were combusted in the burner of FIG. 1 and passed into zone
31. The preheated carbon-black make oil was injected into zone 31
at a rate of 16.7 gallons per hour.
The make oil was injected at a pressure 280 p.s.i.g to assure its
rapid evaporation at a position sufficiently remote from the hot
walls of zone 31 to avoid any coking thereupon.
The "percent combustion" was 31.2. Yield was 35.6 percent based on
total carbon feed.
The black obtained is hereafter identified as Black E.
The following table lists the physical characteristics of the
carbon blacks the production of which has been illustrated by the
foregoing working examples:
TABLE
__________________________________________________________________________
Surface Percent Percent area, Percent DBP DPG Scale volatiles
M.sup.2 /gram extract absorption Tint absorption L.sub.c L.sub.a
__________________________________________________________________________
Black A 85 1.3 70.7 0.8 186 162 7.4 14.9 36.3 Black B 82 1.1 116.9
0.7 145 232 18.6 11.6 34.9 Black C 79 5.2 86.9 3.7 106 164 36.0
Black D 79 2.0 116.2 0.7 136 170 22.1 Black E 80 2.7 101.5 0.7 140
220 33.0
__________________________________________________________________________
A number of extraordinary and surprising results are obtained in
studying the properties of Blacks A through E together with the
processing techniques by which they were produced.
For example, the only important difference in the production of
Blacks A, B and C was the decreasing residence time of the carbon
as measured between injection of the oil make and quenching of the
black. This time was controlled by reducing the size of reaction
zone 35 and positions of quench nozzles 37. It will be noted that
the scale of the black falls from 85 to 82 and then to 79 as this
residence time is reduced. However, Black C does have higher
volatiles and extract than Blacks A and B. This fact, where it
interferes with the performance of the black can be overcome (most
surprisingly) by a large increase in the oil to gas ratio used in
the process. Thus when the oil is increased from 12.5 to 16.7
gallons per hour and the natural gas is decreased from 800 to 200
cubic feet per hour as between examples 3 and 4, the extract
content of the black produced drops from 3.7 percent to 0.7 percent
as seen by comparing Blacks C and D. This is an extraordinary
discovery for it not only allows the production of a low-scale
black having a low extract but also provides means for vastly
increasing the carbon-black production rate of a give
installation.
A further important and advantageous discovery is evident from a
comparison of working examples 4 and 5 and Blacks D and E produced
thereby. Thus, the apparatus of example 5 differed from that used
in example 4, only in the provision of an additional 7 inch long
section 38 downstream of the quench nozzles 37, as illustrated in
FIG. 2.
While the process of the invention has been illustrated with
respect to a particular apparatus, it will be clear to those
skilled in the art from the description of the process that other
apparatus can be contrived for carrying out the process. The
important criteria to be preserved are
1. The establishment of very hot combustion gases, at least
3,000.degree. F.
2. a very rapid velocity for shearing the carbon-black make,
advantageously about MACH 1 or more.
3. A sufficiently high rate of carbon-black make fuel added to the
combustion gases to provide a very high concentration of atoms in
the carbon-forming zone.
* * * * *