US3649207A

US3649207A - Apparatus for producing carbon black

Info

Publication number: US3649207A
Application number: US847680A
Authority: US
Inventors: Fletcher A Hinson Jr
Original assignee: Ashland Oil Inc
Current assignee: Ashland LLC
Priority date: 1969-08-05
Filing date: 1969-08-05
Publication date: 1972-03-14
Anticipated expiration: 1989-03-14

Abstract

A carbon black reactor adapted for producing fine control of the ''''structure'''' of the carbon black produced thereby by controlling the amount of axial gas which is fed with the hydrocarbon feedstock into the reaction zone of the reactor. In one embodiment, a controlled amount of process air is admitted into an annular conduit surrounding the feedstock inlet pipe through fine adjustment of the rotational position of an apertured surrounding sleeve. In another embodiment, a control valve adjusts the amount of axial air which is admitted with the feedstock.

Description

United States Patent Hinson, Jr.

[4 Mar. 14, 1972 [54] APPARATUS FOR PRODUCING CARBON BLACK [72] Inventor: Fletcher A. Hinson, Jr., Portland, Tex.

[73] Assignee: Ashland Oil & Refining Company,

Houston, Tex.

[22] Filed: Aug. 5, 1969 [21] Appl. No.: 847,680

[52] US. Cl ..23/259.5, 23/2094 [51] Int. Cl ..C09c 1/50 [58] Field of Search ..23/209.4, 209.6, 259.5; 260/679 [56] References Cited UNITED STATES PATENTS 2,121,463 6/1938 Wisdom ..23/209.4

3,057,688 10/1962 Williams.... ...23/209.4

3,060,003 10/1962 Williams ..23/209.4

3,211,532 10/1965 Henderson ..23/259.5 3,222,131 12/1965 Powell et al. ..23/209.4 3,390,960 7/ 1968 Forseth ..23/209.4 3,501,274 3/1970 Whittle et a1. ..23/259.5

Primary ExaminerEdward J. Meros Attorney-Walter H. Schneider [57] ABSTRACT A carbon black reactor adapted for producing fine control of the structure of the carbon black produced thereby by controlling the amount of axial gas which is fed with the hydrocarbon feedstock into the reaction zone of the reactor. In one embodiment, a controlled amount of process air is admitted into an annular conduit surrounding the feedstock inlet pipe through fine adjustment of the rotational position of an apertured surrounding sleeve. In another embodiment, a control valve adjusts the amount of axial air which is admitted with the feedstock.

3 Claims, 6 Drawing Figures PATENTEDMAR 14 1972 3, 649 207 sum 2 UF 4 INVENTOR Fleicher A. Hinson, Jr.

BY fida ATTORNEY PATENTEDHAR 14 I972 SHEET H []F 4 ATTORNEY APPARATUS FOR PRODUCING CARBON BLACK BACKGROUND OF THE INVENTION The preparation of furnace-type carbon blacks by the thermal decomposition of hydrocarbons is well known. In general, this method of preparation comprises decomposing a hydrocarbon feedstock by the heat generated from the buming of a portion of the feedstock and/or by subjecting it to heat generated by the combustion of a hydrocarbon fuel. By controlling the reaction conditions, e.g., rates, time, temperature, and the like, it is possible to produce various grades of furnace blacks classified according to particle size and surface area. Other physical properties of carbon black, however, particularly the property of structure for any particular grade, have been dependent, to a great extent, on feedstock composition. Thus, it has long been recognized that the degree of structure of carbon black generally increases as the feedstock from which it is produced increases in molecular weight, the higher structure blacks being produced from the higher molecular weight aromatic tar and tarry residues.

By the term structure as used throughout the specification and claims hereof is meant the degree of that phenomenon to which carbon black particles are associated or clustered to form chainlike, or rodlike, units of varying lengths and geometric configurations. Such formations may occur by virtue of the physical union of numerous particles and/or by virtue of the attractive forces between and among particles. In terms of the former, a minimum or low structure carbon black is accompanied by a minimum of physical union or twinning of particles with a substantial proportion of the particles discretely divorced each from all the others. As the degree of structure increases, an increase in the number of rodlike carbon black units as well as an increase in the length of such units is evidenced. In terms of the latter, a minimum or low structure results when the attractive forces between and among the carbon black particles decrease in magnitude below the point of interference. As these attractive forces increase, the degree of structure increases as a result of interferences between and among particles.

Since the structure of carbon black, and in turn the modulus of carbon black rubber compounds formed therewith, are so closely related to feedstock characteristics, it has long been the practice in order to modify structure without any form of aftertreatment of the carbon black, to replace one feedstock with another. The disadvantages to this practice are apparent. In the first place, obtaining a preselected structure by such a method is strictly a trial and error procedure. Secondly, the capacity to accurately maintain a preselected structure, once it has been obtained, is necessarily dependent on a continued source of supply of the selected feedstock composition. Conversely, any desired change of structure of the carbon black produced requires a replacement of the feedstock. In addition to these factors, moreover, is the more important fact that any structure variation obtained by feedstock replacement is marginal at best and is usually accompanied by an efi'ect, often adverse, on other properties of the carbon black rubber compound, notably tensile strength and/or abrasion resistance.

Because structure of carbon black is one of the several features which combine to make carbon blacks unique in the area of particulate solid matter, considerable effort has been spent in recent years in trying to control the structure of any given grade of carbon black produced from any given feedstock. In this respect, it has been recently discovered that any one of several techniques, when applied to the incomplete combustion furnace process, may be employed to modify structure at various fineness levels. A particularly effective technique for depressing structure involves decomposition of a feedstock in the presence of any of various extraneous additives as described, for example, in US. Pat. Nos. 3,010,794 and 3,010,795.

In Powell et al., US. Pat. No. 3,222,131, there is disclosed a process for the production of carbon black which discloses the control of structure by variations in the feedstock spray angle.

This manner of controlling carbon black structure has proved to be extremely effective, and it has the advantage of being able to produce both increases and decreases in structure level. More specifically, where the feedstock spray is established at a very narrow included angle, a relatively low value of structure is obtained whereas, with a large included angle in the spray pattern, there is relatively greater development of structure in the carbon black.

In carrying out the process of the above-mentioned Powell et al. patent, variation of the feedstock spray angle has been carried out primarily by using various types of spray nozzles in the feedstock injector, each of which is constructed to have a configuration which produces a predetermined included angle in the feedstock spray. Apparatus of this sort is eminently satisfactory for producing significantly different values of the spray angle, but is not particularly suited for making fine adjustments in structure, especially where such adjustments must be made frequently or continuously. The ability to make such fine adjustments is of considerable commercial significance, however, and may be necessary, for example, when variations in ambient atmospheric conditions occur suddenly and affect pressures, for example, in the various feedlines for fuel, feedstock and air to the carbon black reactor. Many of the uses to which carbon black is now put require that the structure be very precisely controlled, and it therefore becomes quite necessary to provide for an almost vemierlike control of structure, which control should be capable of being exercised without, of course, shutting down the reactor.

SUMMARY OF THE INVENTION It is an object of this invention to provide apparatus for exercising very fine control over the structure of carbon black produced in a carbon black reactor, and to enable such control to be exercised instantly and without requiring any shutdown of the carbon black reactor. This objective is met, according to this invention, by varying the volume rate of the axial air or other gas which is fed, together with the feedstock flowing in the same general direction, into the reactor. Thus, with a large volume of air being directed against the back of the feedstock spray, the spray cone is deflected inwardly and the included angle thereof is reduced so as to produce less structure in the resulting product. On the other hand, when the axial air volume rate is decreased, the spray angle is increased, with a resulting increase in the development of structure.

According to one embodiment of the invention, the axial air is controlled by providing an aperture of variable size between the annular chamber which conveys the process air into the reactor and the pipe which surrounds the feedstock spray line and which conveys the axial air. An adjustment external of the reactor is provided for controlling the size of this aperture in a smoothly variable or incremental manner. In another embodiment of the invention, the axial air is provided from an air source through a control valve to the annular chamber which surrounds the feedstock spray line and which conveys the axial air into the reactor so that by manipulation of the valve gradual control of the amount of axial air can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a carbon black reactor including the injector according to one embodiment of the invention;

FIG. 2 is an enlarged longitudinal sectional view of the injector assembly of the embodiment of FIG. 1;

FIG. 3 is a perspective view of the apparatus for controlling the axial air in the embodiment of FIGS. 1 and 2;

FIG. 4 is a longitudinal sectional view of a reactor including the injector of an alternative embodiment of the invention;

FIG. 5 is an enlarged longitudinal sectional view of the injector of the embodiment of FIG. 4; and

FIG. 6 is a sectional view taken along the section line 66 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a generally tubular reactor which is divided as shown into a first or heating zone 2, a second or reaction zone 3, and a quench zone 4 having quench ports 5. The reactor is generally similar in construction and operation to that disclosed in the Williams U.S. Pat. No. 3,060,003, the disclosure of which is incorporated herein by reference. As illustrated, the quench zone constitutes merely an extension of the reaction zone and is of substantially similar configuration. The heating zone, however, is of greater diameter and shorter length than the reaction zone. For optimum results, moreover, it is preferred that the diameter of the heating zone be greater than its length, although this is not a necessary limitau'on for operation of the apparatus in accordance with the present invention.

Heating zone 2 is provided with an inlet opening 6 through which injector assembly 7 projects thereinto, while quench zone 4 is provided with an outlet opening (not shown) for withdrawal of reaction products. Positioned in the inlet end of the reaction zone is a replaceable choke ring 8 of a high temperature resistant refractory material having an orifice 9. The length and shape of orifice 9 may vary and will depend to some extent upon the particular grade of carbon black to be produced. The choke ring illustrated has an orifice whose initial diameter is less than that of the reaction zone but which subsequently gradually increases until it is substantially the same as that of the reaction zone. Choke rings of uniform internal diameter may also be used. Each of the zones and their inlet and outlet orifices are formed by a high-temperature refractory insulation 11, the entire reactor in turn having an outer steel shell or casing 12.

As shown more fully in FIG. 2, injector assembly 7 is composed of substantially concentric tubular members 13, 14, and forming passageways l6, l7, and 18. That portion of tubular member 13 extending into opening 6 and heating zone 2 is recessed to receive a heat-resistant refractory insert 19, while a gas distribution plate, more fully described hereafter, is inserted between the inner ends of members 13 and 14.

Afiixed to the end of member 15 extending into the heating zone is a deflector through the center of which passes member 15 providing passageway 18 with communication to the heating chamber. Deflector 20 is similar in cross-sectional configuration to member 13 and is slightly removed from the inner end of members 13 and 14. Thus, an accurately defined circumferential orifice 21 bounded by insert 19 and the gas distribution plate, on the one side, and deflector 20, on the other side, is formed. The width of this opening may be readily varied by a simple adjustment to the deflector which will be subsequently more fully described. As are all portions of the reactor that are subjected to high combustion and reaction temperatures, the deflector is constructed of a high temperature refractory material. The inner surface of the deflector facing circumferential orifice 21 and the gas distribution plate are both composed of heat-resistant stainless steel. Thus, both parts may be maintained within close dimensional tolerances.

Extending through passageway 18 is a hydrocarbon feedstock member 22 having at its inner end a nozzle or injector 23. This nozzle may take any form but is of such design as to direct the feedstock towards orifice 9 in a vaporized or atomized form. The nozzle structures found to be particularly satisfactory are those which produce a so-called solid cone spray. That is, the outline of the spray is in the form of a cone having its apex at the tip of the nozzle, and the droplets in the spray are distributed throughout the cone. The included angle of the spray cone, measured in the absence of deflecting gases, will be limited to some extent by the position of the deflector in the heating chamber, and usually will not exceed about 180.

Connected with passageway 17 is a duct 24 which supplies an oxygen-bearing gas from a suitable source, which gas is then conveyed through passageways 17 and through orifice 21 to the heating chamber 2. Such oxygen-bearing gas, which may be air, shall hereinafter be referred to as process air. In addition, an apertured sleeve 25 which is rotatable about tubular member 15 provides an aperture of controllable size between passageway 17 and passageway 18 so that a controllable amount of the oxygen-bearing gas in duct 24 may be introduced into passageway 18 and caused to issue from the open end of passageway 18 adjacent the spray of feedstock issuing frorn nozzle or injector 23. Thus, the oxygen-bearing gas which flows through passageway 18, hereinafter referred to as axial air, surrounds the feedstock spray closely adjacent its point of origin.

Connected with passageway 16 and communicating therethrough and through orifice 21 with the heating chamber is a means 26 for introducing fuel. Entry of fuel from passageway 16 into orifice 21 may be by any suitable means for injecting it in a highly vaporized or atomized form so that a thorough mixing therewith of the process air will be obtained in the orifice.

The means for providing fine control of the amount of axial air admitted from duct 24 and passageway 17 into passageway 18 is shown in greater detail in FIG. 3. As shown, the inner tu bular member 15 is provided with an elongate through slot 15a. Fitted about the member 15 at the location of the slot is a tubular sleeve 25 which is freely rotatable about the member 15. As shown in FIG. 2, the left-hand end of sleeve 25 extends exteriorly of the reactor through suitable gastight packing glands or the like so that an operator may readily rotate the sleeve 25 about member 15 by means of handle 25a. Sleeve 25 is provided with a generally triangularly shaped opening 25b in its sidewall, the base of the triangle preferably having a length which substantially corresponds to the length of the slot 150 and member 15. It will be apparent that as the sleeve 25 is rotated about member 15, the effective size of the aperture through the two mating members can readily be adjusted in a very gradual manner so as to provide a very fine degree of control of the amount of axial air which is provided.

As previously described, variation in the amount of axial air makes possible an adjustment in the included angle of the feedstock spray. Although large variations in the spray angle are not obtainable through control of the axial air, it is possible to provide a very fine degree of control so that, in eflect, a vernier adjustment of this parameter may be obtained with corresponding precise adjustments in the structure of the carbon black produced by the reactor.

In operation of the apparatus of FIGS. l-3, process air is introduced through duct 24 and passes through passageway 17, being injected through the open end thereof into circumferential orifice 21. Simultaneously, a hydrocarbon fuel is introduced through inlet 26 and passes through passageway 16, being injected into orifice 21 through a plurality of circumferentially spaced ports. As the stream of process air flows radially outward passing the above-mentioned ports, it is at its maximum velocity and minimum static pressure. As the vaporized or atomized fuel is injected into the stream at a controlled velocity, a thorough mixing of fuel therein is rapidly obtained. The resultant fuel-air mixture flows radially outward following the contour of orifice 21 and is ignited as it passes into the heating zone. The burning mixture and its products of combustion continue the flow radially outward from the axis of the heating zone as a uniformly expanding disc towards the circumferential surface of the heating zone. It then follows a flow pattern as shown by the arrows in FIG. 1, tending to flow parallel to said circumferential surface towards the opposite end of the heating zone where it is directed radially inward toward the axis of the zone and orifice 9.

As hydrocarbon fuel and process air are introduced into the reactor, through their respective inlets, hydrocarbon feedstock as a vapor or finely divided liquid spray is introduced through inlet 22 to be injected into the heating zone through nozzle 23. This injection takes the form of an expanding cone directed towards orifice 9. The temperature of the feedstock is rapidly raised as it approaches orifice 9 and is thoroughly mixed with and dispersed into the hot combustion gases resulting from the burning of the hydrocarbon fuel. The resultant mixture of combustion products and feedstock passes through the orifice into the reaction zone where the cracking of the feedstock is terminated as desired by quenching the mixture with water or other suitable cooling medium introduced through quench ports 5. The cooled reaction gas with entrained carbon black then exits from the reactor through an outlet opening, not shown, for subsequent separation and collection of carbon black by means which form no part of this invention.

The inventive concept of this invention is applicable not only to a carbon black reactor of the type disclosed in FIGS. 1 and 2 which, as aforesaid, corresponds generally to the type of reactor disclosed in the Williams patent 3,060,003, but is equally applicable to the type of carbon black reactor disclosed in the Whittle et al. application Ser. No. 678,962 filed Oct. 30, 1967 now U.S. Pat. 3,501,274. In the type of reactor disclosed in such application, the process air is not introduced into a passageway which immediately surrounds the conduit conveying the feedstock and axial air to the reaction zone but is instead conveyed to the reaction zone through an annular passageway which is defined in part by a conically shaped hood which surrounds the inner conduit conveying the feedstock and axial air and also the separate conduits for conveying, respectively, the fuel and air which are admixed and burned in the heating zone.

Referring to FIG. 4, the

various elements

3, 4, 5, 8, 9, 10, ll, 12, and 19 are all similar to the corresponding elements shown in FIG. 1 and perform corresponding functions. The injector 30 of this embodiment is different from the injector 7 of FIG. 1, and the injector of this second embodiment is therefore shown in greater detail in FIG. 5. Thus, the injector comprises a generally conical shell 31 having a flange 32 at one end thereof for mounting the burner on the reactor. A sleeve 33 is supported on a cylindrical extension 34 of shell 31 by means of a plurality of vanes 35. The upstream end of sleeve 33 is contoured at 36 to conform to the inclination of conical shell 31 thereby to provide a circular space acting as a combustion supporting gas inlet. As a result of this gas inlet configuration, tees of the type shown at 24 in FIG. 1 are avoided, and lower combustion supporting gas pressure drops are achieved.

The downstream end of shell extension 34 is attached, e.g., by welding, to the upstream end of a forged header member 37. The outermost surface of header member 37 is smoothly curved, as illustrated, and a flared flange 38 having a curvature smoothly continuing that of header member 37 is attached, e.g., by welding, to the downstream end of header member 37. Flared flange 38 acts as the interior surface of a deflector structure generally similar in operation to that of deflector 20 described earlier. To this effect, a cast refractory material body 39 is attached to flange 38 with the aid of a plurality of stainless steel clips generally designated 40 which are welded to the flange 38.

The downstream end of a sleeve 33 is provided with a ring 41 having an interior curvature generally conforming to the curvatures of flange 38 and of forged header member 37.

Members

37, 38 and 41 thus cooperate with one another to provide a smooth streamlined continuation of the passageway for combustion supporting gas, terminating in an angular or ring-shaped orifice 42.

Forged header member 37 is provided with a central bore extending along the axis of the burner which is threaded at 43 for reception of an elongated pipe 44 through which the feed stock supply conduit 45 may pass. Pipe 44 provides a conduit for conveying axial air to be mixed with the feedstock, with the amount of axial air being controlled by the degree of opening of a valve 46 connected in pipe 44. Cast refractory member 39 is also supplied with a central bore 47 mating with and comprising a continuation of the bore which is threaded at 43 for reception of the feedstock supply nozzle. Header member 37 has a pair of interior chambers 48 and 49 for reception of atomizing air (when it is used) and a hydrocarbon fuel respectively. An air inlet pipe 50 is attached to the header member 37, and a fuel pipe 51 is also attached to said header member, with each of said pipes 50 and 51 being supplied with appropriate screw couplings 52 for attachment to the appropriate sources of air and fuel.

The arrangement of FIG. 5 operates, in general, in the manner previously described in reference to FIGS. 1 and 2, but unifies the deflector and burner proper, and simultaneously provides an improved arrangement of flow passages for combustion supporting gas, fuel, and atomizing air (when desired). While the arrangement of FIG. 3, as described, permits either liquid or gaseous fuels to be employed, it will be understood, of course, that similar provision may be made in the arrangement of FIG. 1.

In the embodiment of FIGS. 4 and 5, axial air is conducted from a suitable source of air or other oxygen-bearing gas (not shown) through valve 46 and through pipe 44 to be mixed with the feedstock which is admitted through the feedstock inlet pipe 45. Fine control over the included angle of the feedstock spray may be obtained by adjusting the amount of axial air provided in accordance with the degree of opening of valve 46, thereby making possible fine adjustment of the structure of the carbon black produced.

Other combustible and noncombustible gases may be used in addition to or in place of the axial air for van'ably deflecting the feedstock spray to narrowed included angles and thereby controlling the structure of the black in accordance with the invention. For instance, the use of steam and/or natural gas and/or reactor tail gas and/or nitrogen and/or other inert gas is suggested. Such other gases may be injected into a reactor equipped with a pipe 44 like that shown in the figure 4-6 embodiment of the invention by connecting said pipe with one or more sources of the desired gas(es) and means for regulating the flow, where use of a gas other than air results in the delivery of a higher or lower concentration of oxygen to the combustion zone than would be provided by the use of air, the rate of introduction of the main process airstrearn may be adjusted accordingly to maintain the desired overall molar ratio of fuel and hydrocarbon feedstock relative to oxygen in the furnace.

Through the use of the present invention, fine control of structure is maintained while holding substantially constant such other properties as particle size, tinctorial power, surface area, ash content and the like which characterize a given grade of carbon black. By substantially as applied to the constancy of such properties, it is intended to convey that such variations as occur in each of the properties fall generally within the permissible ranges of variation established for a. preselected grade of carbon black, e.g., l-IAF, ISAF, SAF, SPF and the like, which is being manufactured in the furnace. These and many other grades of black and the pennissible ranges of variation for the various characterizing properties therefor are widely recognized throughout the industry and sanctioned by such recognized authorities as the ASTM.

What is claimed is:

l. A fumace-type carbon black reactor having a generally tubular chamber including a generally tubular enlarged combustion zone at the upstream and thereof,

an axially disposed feedstock inlet adapted to discharge a feedstock into said combustion zone adjacent its central axis,

an axially disposed gas inlet adapted to discharge a gas into said combustion zone, admixed with said feedstock and also generally adjacent its central axis, first means for introducing both a fuel and an oxygen-bearing gas to said combustion zone for burning therein, comprising an annular passageway surrounding said gas inlet,

means for introducing said feedstock from said feedstock inlet into said combustion zone in a divergingly angled spray pattern,

and means for controlling the rate of flow of gas provided by said gas inlet comprising means defining an aperture of variable size between said annular passageway and said gas inlet.

cludes aperture means and further includes means extending externally of said tubular chamber for rotation of said sleeve to thereby adjust the size of the combined effective aperture through said pipe and said sleeve.

Claims

2. The apparatus of claim 1 in which said gas inlet comprises a pipe of circular cross section having an aperture therein, and said aperture defining means comprising a sleeve slidable on said pipe and so disposed that the effective aperture through said pipe aperture is dependent upon their relative positions.
3. The apparatus of claim 2 in which said sleeve also includes aperture means and further includes means extending externally of said tubular chamber for rotation of said sleeve to thereby adjust the size of the combined effective aperture through said pipe and said sleeve.