US3100689A - Carbon black manufacture - Google Patents

Description

Aug. 13, 1963 J. L. MASON, JR 3,100,589

CARBON BLACK MANUFACTURE Filed Aug. 21, 1958 5 Sheets-Sheet 1 FIG. I

\ MI: A vf \NVE'.NTOR

JAMES L. MASON, JR.

Aug- 13, 1963 J. L. MASON, JR 3,100,689

CARBON BLACK MANUFACTURE Filed Aug. 21, 1958 3 Sheets-Sheet 2 INVENTOR. JAMES L. MASON, JR.

Aug.,13, 1963 J. L. MASON, JR

CARBON BLACK MANUFACTURE s sheets-sheet s Filed Aug. 2l, 1958 mmPmDJO Z wmJNNOZ hmmm ....O mmEDZ OOM lNvENToP:A JAMES L. MASON, JR.

ma me-44M L )a n ATTZRQS United States Patent O This invention relates to the manufacture of carbon black and, more particularly, to improvements in processes therefor of the type in which a hydrocarbon oil, or similar liquid carbon-containing compound, is subjected to partial combustion in a relatively quiescent zone withl a restricted amount of oxygen, whereby a portion of the oil is burned and the remainder is decomposed to carbon black by the heat thus generated.

A process of this type has been described and claimed in United States Patent 2,779,665, in accordance with which a gently-owing, relatively uniform current of air is passed upwardly through the lower end of an unobstiuoted, vertically-elongated, heat-insulated furnace chamber and a gas-atomized spray of liquid hydrocarbon, of high molecular weight and high aromaticity, initiated in the lower end of the chamber, is injected upwardly into the chamber, at a relatively high velocity, in contact with the air, whereby a portion of the hydrocarbon is burned in the lower end Vof the chamber and there is established in the furnace chamber above the zone of combustion a lazy, substantially non-oxidizing or reducing upwardly rising atmosphere of hot furnace gases at a temperature above the decomposition temperature of the remaining hydrocarbons. p

In that operation, the hydrocarbon is sprayed upwardly through the upwardly rising air and hot furnace gases at an initial velocity suilicient to carry the spray high into the chamber but insufficient to cause `it to impinge on the upper wall thereof. The air is introduced into the lower end of the furnace chamber in an amount much smaller than that required to burn all of the hydrocarbon and at a rate, and in a manner, such as to establish a uniform, non-turbulent upwardly drifting current through the chamber at a velocity within the range of 1 foot to siX feet per second. Under these conditions, there is formed within the chamber a smoke blanket which fills the entire upper portion of the chamber extending downl' wardly for a distance approximating one-half to threefourths of the height of the chamber.

The process just described has been found especially advantageous in producing so-called high structure blacks, having high oil absorption characteristics, from highly aromatic oils, for instance creosote oils, cracked petroleum residues, coal tars, coal tar oils and the like. The present invention, in one of its aspects, constitutes an improvement in the process of said Patent 2,779,665, but its utility is not restricted to the specific operating conditions, or to the charging stock, therein described.

The oil absorption characteristics of a carbon black have been recognized to vary with the aggregate surface area of the black. As the mean particle diameter of the carbon black particles decreases, its surface area, frequently expressed as square meters per gram, generally increases. However, the oil absorption of carbon blacks is also known to be influenced by a characteristic of the black known as st1ucture, which is a joining together of the carbon particles to form reticulate chains. For a carbon black of a given mean particle diameter, a high oil absorption characteristic is an indication of such structure.

High structure is a desirable property of carbon black for some purposes. For instance, blacks having high structure improve the extruding properties of rubber ICC compositions compounded with such blacks. For other purposes, a low or moderate oil absorption or structure is more desirable.

A known way of controlling oil absorption, within limits, is by the selection of the feed stock to be decomposed for producing the carbon black. It is known that the use of paraffinic type feed stocks normally tends totproduce carbon blacks of low oil absorption for a given meanI particle diameter. On the other hand, the use of aromatic oils generally tends to produce carbon blacks of relatively higher structure and high oil absorption. However, the oil absorption characteristic of a carbon black is normally very difficult to control independently of surface area and charging stock.

Usually infurnace operation, conditions, such as air ratios and the like, are so set as to produce a carbon black of the required iineness, the oil absorption being independently controllable only within a relatively narrow range.

A disadvantage of using parainic oils for producing carbon blacks of low oil absorption is that the yield of carbon black per gallon of oil is relatively low. The aromatic feed stocks inherently produce higher yields, but also higher structure.

The present invention provides method and means whereby the oil absorption characteristics of a carbon black may be controlled and varied over a wide range, independently of the feed stock used and independently of the particle size range of the resultant black.

The invention also provides means whereby the productionrate of a given furnace may be greatly increased by increasing the charging rate without material change in the quality of the carbon black produced.

The invention will now be described and illustrated with reference t0 the following drawings of which:

FIG. 1 is a vertical sectional view of a carbon black furnace embodying means especially adapted to the carrying out of my improved process,

FIG. 2 is a transverse horizontal section along the line 2-Z of FIG. 1,

FIG. 3 is an enlarged somewhat fragmentary view, partly in section, of an assembly used in accordance with my invention for injecting the hydrocarbon oil into the furnace chamber, and

FIG. 4 is a graphic illustration of the increase in production rate of a given furnace made possible by my present invention.

The `furnace of FIG. 1 comprises a vertical elongated chamber 1 tof cylindrical cross-section surrounded by circular wall 2, tapering inwardly at its upper end, and constructed of suitable furnace refractory and heat-insulating materials, as is well-'known to the art. The lower end of the furnace chamber is provided with a partition 3 of furnace refractory, beneath which there is an lair chamber 4. A multiplicity of symmetrically positioned airducts 5 extend through partition 3 through which air passes from the air chamber into chamber 1 for supporting the partial combustion of the oil.

Combustion air is passed to the air chamber under moderate pressure from any convenient source through conduit 6 which ente-rs tangentially into the annular air duct 7 and passes therefrom into the air chamber 4 through the downwardly directed, symmetrically positioned perforations 8.

The rate at which airis introduced `through duct 6 [is so regulated las to obtain the desired quantity of air passing upwardly through chamber 1 at the desired velocity, usually within the range of l foot to 6 `feet per second, and more advantageously within the range of 1 foot to 3 feet per second, calculated for a temperature of 2400o F.

The oil to be partially burned and partially decomposed to carbon black is introduced into -the furnace chamber 3,1oo,ese

by means of the spray assembly represented at 9 and more clearly shown in FIG. 3 of the drawing and, with reference to which, the assembly will hereinafter be more fully described. n The resultant gaseous suspension of carbon black passes from the upper end of the chamber Ithrough iiue 1G into duct 1.1 leading to conventional carbonblack separating and collecting apparatus, not necessar] here to describe.

An essential feature of the present invention is the manner in which the oil is introduced into the furnace chamber, since it is by variation in this feature of the invention that the oil absorption or structure'characteristic of the resultant carbon black is independently controlled.

I have found most surprisingly that the oil absorption characteristic of a carbon so produced can be controlled at will and varied over a substantial range, independently of the type of charging'stock used 'and of the mean particle :diameter of the carbon black particle, by injecting the oil into the furnace chamber as a cluster of parallel, gas-atomized liquid sprays and varying the number of sprays of the cluster.

A spray assembly comprising a cluster of such sprays, which has been used with particular advantage in carrying out the present invent-ion, is illustrated by FIG. 3. The assembly shown comprises a cluster of 8 closely spaced, symmetrically arranged spray nozzles 9` so positioned thattheir respective axes are parallel. It will be understood that the number of spray nozzles in the cluster may be varied considerably depending upon the desired results. It appears to be essential, however, that the spaces between the nozzles be closed against the upward ow of air. AIn the apparatus shown, the body of the assembly meets that requirement.

The respective spray nozzles shown comprise an outer hollow cap 11 internally threaded into sleeve I2 at 13. Sleeve 12 is in turn threaded onto the upper end of nipple 14 at 15 and the lower end of the nipple is threaded at 16 into the cover plate i7 of the oil chamber 18 which constitu-tes the upper end of the housing 19 and which is separated by partition 20 from steam chamber 21 in the lower end of housing 19. These spray nozzles fare spaced apart a distance of 1% inches-2 inches between centers.

The nozzle also comprises `'an inner element composed of a tube 22 threaded into partition 20 'at its lower end and lopening into steam chamber l21. The passageway through this tube is constricted at its upper end to form an orifice -23 leading into the chamber within the hollow cap 11. The upper end of tube 22 is surrounded by helical guides 24.

In operation, oil under pressure is forced from the oil chamber upwardly through the annular duct su-rrounding tube Z2 and along the flights of the helical guides 25 into the cap 11. Steam under pressure passes from steam chamber 21 through tube 22 and is jetted ythrough orifice 23, forcefully impinging on, land atomizing, the oil land the resultant mixture is sprayed into the furnace chamber through orifices 25 extending through cap `11.

It will be understood that the invention is not restricted to the particular construction of the spray nozzle shown bu-t that other nozzles adapted to the gas atomization of liquid oils may be used. Most advantageous results have been obtained using spray nozzles having an angle of spread of about 30i degrees.

In the assembly shown, steam under pressure is fed to chamber 21 through steam conduit 26 which extends coaxi-aily through tube 27 forming an annular passageway 28 through which the oil, preferably preheated, is charged under pressure to chamber 18.

Due .to the high temperature of the furnace chamber, usually of the order of 2300 F. `or higher, there is danger of coke-forming pyrolysis of the oil being passed to the spray nozzles. I kavoid this difficulty by thermally insulating `the incoming oil'frcm the high temperatures of the furnace chamber.

In the assembly shown in FIG. 3, I provide an annular dead-air space 29 positioned coaxially with respect to the con-duit 28 and which, in turn, is surrounded by an annular passageway Sti formed by coaxially positioned cylindrical walls Si and 312 and'end wall 33. Water or other cooling medium is discharged into the inner end of conduit 3@ through pipe 34, iiows outwardly along tube 31 and is discharged through outlet tube 3S. The dead-air space 29 is vented through end wall E53` at 36 and tube 27 is held in position by lugs 37. Except as previously noted, the various elements of the assembly may be fastened together in any suitable manner, for instance by welding las indicated at 3S.

In practice, I have found it advantageous to fill the spaces between the spray nozzles with a plastic refractory material as protection from the high furnace temperatures.

As noted above, the oil absorption characteristics of the carbon black may be controlled :and regulated, in accordance with the present invention, gby varying the nurnber of spray nozzles of the cluster. While I am unable presently to account for this phenomena, I have found that, for a given ltype of charging stock, the oil absorption characteristic of the resultant carbon black can be materially decreased by increasing the number of spray nozzles of the cluster and, conversely, the oil absorption characteristic can be materially increased by decreasing the number of spray nozzles of the cluster.

Where 1 to 3 spray nozzles are used, `as described in the above-noted Patent No. 2,779,665, a carbon black of maximum structure, or oil absorption, for the particular feed stock, is obtained. But as the number of spray nozzles is increased, other conditions remaining constant, the structure of the resultant carbon black has been found to decrease. Similarly, as the number of spray nozzles is increased, the oil load, i.e. charging rate to the furnace, may be increased without material change in the qual-ity of the resultant black. I have, with advantage, used clusters of as many as 18 sprays. Clusters of even more than 18 sprays may be used but such large clusters tend to occupy too great a proportion of the cross-sectional area of the furnace chamber and operation becomes more idiiiicult to control.

This variation in oil absorption and structure can be effected, by my present method, regardless of the particular type of feed stock used, `as fwill be illustrated by the following speciiic examples.

EXAMPLE I This operation was carried out in apparatus substantially as shown in the drawings except that the number of spray nozzles in the `spray assembly used in the respective runs was varied as indicated. The diameter of the furnace chamber was 8.5 feet, I D. The feed stock used in each of these runs was creosote oil, land in each run the spread angle lTof the respective spray nozzles was about 30. The number of sprays and other yoperating conditions used in each run land the characteristics of the resultant carbon black lare set forth in the following tabulation:

Table I Run No 1 2 3 p.s.l Calculated steam, volume at 300 F., .h Initial spray nozzle velocity, ft./sec. (cale). Au' velocity, {11./sec. (calc.) Color rating, ABC

Oil absorption, gallons per lbs.-- Yield, lbs. per gallon Since ABC color value is an indication of mean particle diameter, it will appear that each of the carbon blacks produced was of the same fineness and, in spite of that fact and the fact that the same feed stock was used in each run, the oil absorption characteristics of the black dropped sharply with an increase in the number of sprays.

EXAMPLE I1 In each of `the following runs, the feed stock used was a No. 6 fuel oil of relatively low arcmaticity. The apparatus was the salme as that used in ythe preceding runs, except that the furnace diameter was 6\.5,feet, LD. The number of sprays and operating conditions and the characteristics of the resultant carbon black are set forth in the .following tabulation:

Table 1I Run No 1 2 3 4 Number oi sprays.. 3 4 5 8 Air volume, M c..h 32 32 32 32 Oil, g.p.h 180 180 180 180 Atcmizing steam, p.s. 40 40 40 40 Calculated steam volume at 290 F., cih- 2, 520 3, 360 4, 220 6,720 Initial Vspray nozzle velocity, it./sec.

(calc.) 686 686 686 636 Air velocity, It./Sec. (oalc.) 1. 43 1. 43 1. 43 1. 43 Color rating, ABC 54 55 55 Oil absorption, gallons per 100 lbs 14. 5 12. G 10. 4 8.0 Yield, lbs. per gallon 2. 2 2` 4 2. 6 2. 5

Here also the iineness of the resultant carbon blacks of the respective runs ywas practically the same, as indicated by ABC color, and the changing stock was identical. Neveritheless, there was a sharp decrease in oil absorption value with the increase in the number of sprays used.

EXAMPLE III In yfurther .series of runs using No. 6` fuel oil as 'the charging stock in the furnace lof the preceding example and under conditions set Vforth'in the following tabulation,

It has heretofore been found particularly diiiicult t0 vary independently the oil absorption characteristics of a carbon black produced .from parafiinic type oils such as No. 6 ifuel oil. The present invention provides means whereby this can be readily accomplished. Also, as shown by the yield increase in Tables II and III, the present invention provides means whereby the yield of carbon black per `gallon of :oil used may frequently be materially increased, without decrease in mean particle diameter, by increasing :the number of sprays used.

The air velocities 4given in `the foregoing tabulations were calculated for a temperature of 2400 F. The initial spray nozzle velocities `and steam volumes are approximate values calculated with-out taking into account expansion due to temperature increase on leaving the nozzle, the orifice discharge coeiiicient or the oil volume.

The relationship of permissible oil load to the number of sprays in the clusters used, lfor increasing production rate without change in quali-ty, is illustrated by the graph constituting FIG. 4 of the drawings in which the production rate in pounds of carbon black per hour is plotted against the number of sprays. In leach of these runs, the feed stock was No. 6 fuel oil, hereinafter more fully described, and the ratio of air to foil was maintained at .33 1, as in the preceding Example Ill.

The furnace used in these runs was that used in EX- a-mples II land III. In each instance, the ABC color value ci 4the resultant black was 50-51 and the oil absorption val-ue was 12J-12.4 `gallons of oil per 100 pounds of the black. The increase in production rate was, of course, due to an increase in chargingfrate, which would normally result in `a marked change in the quality of the black produced. However, by increasing the number of sprays, in accordance with my present invention, it was possible materially to increase the charging rate while maintaining the quality of the black substantially constant. possible, in accord-ance with m-y present invention, by varying the number of sprays used, independently to control the structure characteristics of the black |at -a given production rate or to materially increase production rate while holding the structure of the black constant.

rThe characteristics of the respective oils used in the foregoing runs are set iorth in 'the following tabulation:

Table IV Creosote No. 6 fuel oil oil It will Ibe understood that the invention is not restricted to the speciiic types of foil illustrated ybut is applicable generally to normally liquid hydrocarbons land similar carbon-containing compounds, referred to collectively in the appended claims as hydrocarbon oil.

In addition .to use in rubber compounding, the carbon blacks produced in accordance lwith my present invention are well `adapted for other uses. `For instance, the black so produced having the higher oil absorption characteristics are particularly useiul in the manufacture of dry cell batteries, :and the lower oil absorption blacks are particularly useful in `the manufacture 'of electrical resistors, electrodes 'and the like. In rubber compounding, the blacks of higher oil `absorption lare especially adapted for use with synthetic rubber, while the lower oil absorption carbon blacks are more desirable `for use in the compounding of natural rubber.

Without intending to be 'bound to iany theory las to why these surprising results are obtained, I advance the following as a possible explanation. Where :a single spray is used, the upwardly rising air is in Contact with the entire periphery of that spray tand imay readily be drawn into the interior :ot the spray by eduction. Where two or three sprays are used, a very substantial proportion of the periphery of ythose lsprays is also in contact with the rising air. However, where the number yof sprays is increased beyond three, there is developed within the interior of the cluster a zone in which there is a relatively high concentration of the hydrocarbon droplets. In conjunction with this, by reason of the Afact that the zone is shielded on all sides from the upwardly rising lair current by the surrounding sprays, and the fact that no air is permitted to rise between the spray nozzles, and the :fact that there is only a low degree 'of turbulence of the rising air by which it might be diffused into this zone, this zone of relatively high hydrocarbon concentration is also relatively free from oxygen.

As thc number of spray nozzle-s is increased, the horizontal area of this zone will also be increased and the shielding of this zone from the surrounding air current will become even more eiective. It is my present belief that the surprising decrease in oil absorption is, in some way, related to the lestablishing of this interior zone of high hydrocarbon, and low oxygen, concentration.

I claim:

1. In the process ttor producing furnace caribou blacks by the partial combustion of hydrocarbon oils whereby a Thus it isY oil is injected upwardly into 'the chamber as la high velocity gas-atomized spray initiated in the .-l-ower end of the chamber, whereby a portion of the hydrocarbon is burned in the lower portion of the chamber and there is established inthe furnace chamber above said zone of combustion a lazy, substantially non-oxidizing, upwardly rising atmosphere of hot lfurnace gases at a tempenature above the :decomposition temperature of the remaining hydrocarbons, the improvement which comprises injecting the oil into the fur-nace chamber as 4a cluster of closely spaced, gas-atomized spray streams having substantially parallel Y axes of symmetry arranged labout -a central Zone substantially coaxially with the vertical axis of the furnace charnber, the number `of the spray streams in the cluster being i-n excess of three, the spnay streams being suliiciently close to form a protective barrier to the entrance of lair later- `al-ly into said central zone, and shielding said central zone against passage of air upwardly thereinto.

2. The process of claim 1in which the upward velocity f the air current through the furnace chamber is within the range of 1 foot to 6 feet per second.

3. The process of claim 2 in which the upward Velocity of the air current through the chamber is within the range of 1 foot to 3 feet per second.

4. The process of claim l in which the hydrocarbon vused is a high molecular weight, highly aromatic residual oil.

5. The process of claim l in which the hydrocarbon used is a fuel oil relatively high in paraffinic constituents. 6. In the process 'for producing furnace carbon blacks by the partial combustion of hydrocarbon oils whereby a Vgently-ilowing, relatively uniform current of air is passed upwardly through the lower portion of an unobstructed, vertically-elongated furnace chamber and the hydrocarbon oil is injected upwardly into the chamber as a high velocity gas-atomized spray initiated in the lower end of the chamber, whereby a portion of the hydrocarbon is burned in the lower portion of the chamber and there is established in the chamber above said zone of combustion a lazy, substantially non-oxidizing, upwardly rising atmosphere of hot furnace gases at a temperature above Athe decomposition temperature of the remaining hydrocarbons, the method of controlling the oil absorption char acteristic of the resultant black which comprises injecting the oil into the furnace chamber as a cluster of closely spaced, gas-atomized spray streams" having substantially parallel axes of symmetry arranged about a central zone substantially coaxially with the vertical axis ofthe furnace chamber, the number of the spray streams in the cluster being in excess of three, the number of spray streams depending upon the desired low value in the oil absorption characteristic of the resultant black, the greater the number of oil streams, the lower the oil absorption characteristic, the spray streams being Sulliciently close to form a protective barrier to the entrance of kair laterally into said central zone, and shielding said central zone against passage of air upwardly thereinto.

7. In the process for producing furnace carbon blacks by the partial combustion of hydrocarbon oils whereby a gently-flowing,y relatively uniform current of air is passed upwardly through the lower portion of an unobstructed, vertically-elongated furnace chamber and the hydrocarbon oil is injected upwardly into the chamber as a high velocity gas-atomized spray initiated in the lower end of the chamber, whereby a portion of the hydrocarbon is burned in the lower portion of the chamber and there is established in the chamber above said zone of combustion a lazy, substantially non-oxidizing, upwardly .rising atmosphere of hot furnace gases at a temperature above the decomposition temperature of the remaining hydrocarbons, the method of increasing the production rate per unit volume of charging stock of a given furnace by increasing the hydrocarbon oil charging rate, without substantial change in the quality-of the resultant carbon black, which comprises injecting the oil into the furnace chamber as a cluster of closely spaced, gasatomized spray streams having substantially parallel axes of symmetry arranged about a central Zone substantially coaxially with the vertical axis of the furnace chamber, the number of the spray streams in the cluster being in excess of three, the number of spray streams depending upon the desired charging rate, the greater the number vof spray streams the higher the charging rate, the spray streams being sufficiently close to Iform a protective barrier to the entrance of air laterally into said central zone, and shielding said central zone against passage of air upwardly thereinto.

References Cited in the le of this patent UNITED STATES PATENTS 2,779,665 Heller Ian. 29, 1957

Claims (1)

1. IN THE PROCESS FOR PRODUCING FURNACE CARBON BLACK BY THE PARTIAL COMBUSTION OF HYDROCARBON OILS WHEREBY A GENTLY-FLOWING, RELATIVELY UNIFORM CURRENT OF AIR IS PASSED UPWARDLY THROUGH THE LOWER PORTION OF AN UNOBSTRUCTED VERTICALLY-ELONGATED FURNACE CHAMBER AND THE HYDROCARBON OIL IS INJECTED UPWARDLY INTO THE CHAMBER AS A HIGH VELOCITY GAS-ATOMIXED SPRAY INTITATED IN THE LOWER END OF THE CHAMBER, WHEREBY A PORTION OF THE HYDROCARBON IS BURNED IN THE LOWER PORTION OF THE CHAMBER AND THERE IS ESTABLISHED IN THE FURNACE CHAMBER ABOVE SAID ZONE OF COMBUSTION A LAZY, SUBSTANTIALLY NON-OXIDIZING, UPWARDLY RISING ATMOSPHERE OF HOT FURNACE GASES AT A TEMPERATURE ABOVE THE DECOMPOSTITION TEMPERATURE OF THE REMAINING HYDROCARBONS, THE IMPROVEMENT WHICH COMPRISES INJECTING THE OIL INTO THE FURNACE CHAMBER AS A CLUSTER OF CLOSELY SPACED,

Images