US2704242A - Apparatus for pyrolysis of hydrocarbons - Google Patents

Description

March 15, 1955 H. w. STRAUss APPARATUS FOR PYRoLYsIs QF HYDRocARBoNs Filed Dec. 5. 1950 2 Sheets-Sheet 1 l INVENTOR Hon/,4R0 W TRM/55 ATTORN EYS March 15, 1955 H. w. sTRAUss APPARATUS FOR PYROLYSIS OF HYDROCARBONS 2 Sheets-Sheet 2 Filed Dec. 5. 195o INVENTOR Hon/Ano W rRAu'ss ATTORNEYS APPARATUS FOR PYRoLYsIs oF HYDRocARBoNs Howard W. Strauss, Port Arthur, Tex., assiguor to Columbian Carbon Company, New York, N. Y., a corporation of Delaware Application December 5, 1950, Serial No. 199,245

1 Claim. (Cl. 23-279) It has previously been proposed to produce carbonv black from natural gas by intermittently passing the gas in contact with hot refractory materials, e. g., brickv checkerwork, and periodically reheating the checkerwork by burning a combustible gas in contact therewith. That procedure has the disadvantages of lack of continuity andlack of uniformity of temperature conditions and has been subject to the further objection that carbon deposits form on the refractory surfaces and tend to clog the passages through the checkerwork, through which the gas must pass.

These carbon deposits tend to insulate the refractory surfaces from the gaseous hydrocarbons and must be periodically removed, as by burning, or otherwise. Further, after the burning and the period of reheating, the system must be purged before productive operation can be resumed. Also, in order to prolong the period of productive operation and to promote greater uniformity of operating conditions during that period, extensive heat retaining refractories have been required, and to avoid objectional plugging of the system by carbon deposits, it has been customary so to construct the checkerwork as to provide relatively large passages therethrough, thus lessening the rate of heat conduction to and from the refractory mass.

The apparatus of my present invention avoids the difliculties heretofore experienced with that type of opera-` tion. It may be operated substantially without interruption, is compact, relatively inexpensive and has other advantages as will hereinafter appear.

A primary advantage of my present invention is that productive operation may be carried on continuously over long periods without interruption, either for cleaning or reheating. This is accomplished by providing the refractory surfaces in the form of a perforated refractory cylinder adapted to be rotatedabout its axis. One segment of this cylinder is continuously heated in a heating zone while the pyrolysis of the hydrocarbon is continuously effected by passing the hydrocarbon in contact with a different, previously heated segment of the cylinder in a pyrolysis zone, the cylinder being so positioned that during rotation successive segments of the cylinder pass successively through the heating zone and then through the pyrolysis zone and back to the heating zone for reheating.

In accordance with this invention, the gaseous hydrocarbon is continuously passed through the perforation, in contact with the freshly heated segment of the refractory cylinder and in this way substantially uniform temperature conditions are constantly maintained. Further, any carbon deposits formed on a segment of the cylinder in the pyrolysis zone may be burned therefrom in the heating zone, and in this way any accumulation of carbon which would tend to insulate the refractory surfaces from the hydrocarbons or to plug the passages through which the gases must pass through the refractory, is avoided.

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Thus, the temperature of the refractory surfaces and the rate of heat transfer therefrom may be maintained remarkably uniform. Further, the temperature of the refractory may be nicely controlled by adjustment of the rate of heating, the speed of rotation of the cylinder, and the rate of feed of the hydrocarbons, so as to eifect the desired extent of pyrolysis, i. e., either to form carbon black or a lesser degree of pyrolysis.

The invention will be further described and illustrated by reference to the accompanying drawings which represent conventionally and somewhat diagrammatically one particularly advantageous embodiment thereof.

Figure 1 of the drawings is a vertical section of the furnace along the lines 1-1 of Figure 2, and

Figure 2 of the drawings is a horizontal section of the furnace taken along lines 2 2 of Figure 1.

The furnace is enclosed by a vertically positioned, impervious cylindrical wall 1, an impervious roof wall 2, and an impervious floor wall 3, A cylindrical perforated refractory partition Wall 4 is positioned within the enclosure, coaxially with respect to the wall 1, so as to form an inner chamber 5 and an annular chamber 6. The outer wall 1 and the roof wall 2 are stationary and are supported by supporting members of any conventional type, for instance, as more particularly shown by the elements 7 of Figure 2. The floor Wall 3 is likewise stationary and is supported by the column S.

The perforated wall 4 is supported by, and, at its lower end, is securely fastened to an annular shaped sealing member 9. At its lower side, the member 9 is provided with an annular track 10 which rests upon, and is supported by, a plurality of lianged rollers 11. The member 9 is further provided with means adapted to cause its rotation about its axis such, for instance, as a toothed wheel 12, extending about the member 9 and securely fastened thereto, the toothed wheel 12 being adapted to cooperate with a driving gear, not shown in the drawing.

The oor wall 3, and the outer wall 1, are provided, respectively, with lianges 13 and 14 extending downwardly into annular trough- shaped depressions 15 and 16 in the sealing member. These annular trough-shaped de-. pressions are adapted to be filled with a powdered sealing' material such, for instance, as silicon oxide, magnesium,

oxide, or silica gel.

Within the inner chamber, there is an effluent chamber- 39 delineated by the impervious V-shaped wall 17 and ai segment of the perforated partition member. This wall 17 is supported by, and securely fastened to, the oor wall 3 and extends upwardly the entire height of the inner chamber and is securely sealed to the roof wall 2. The

touter edges of the V-shaped wall terminate just short of the inner surface of the cylindrical partition wall so as to permit free rotation of the latter.

Also extending over the entire height of the partition lwall, there is provided an inlet chamber 18 in open communication with the annular chamber and radially positioned with respect tothe eluent chamber. This inlet chamber `is delineated by the walls 19 which extend inwardly to a position just short of the outer surface of the ,perforated partition wall so as to form an effective seal between the inlet chamber and adjacent segments of the annular chamber while permitting free rotation of the perforated cylindrical partition.

Leading to the inlet chamber are a plurality of valved `hydrocarbon inlet conduits 20 spaced over the height of "the chamber and connected at their outer ends with the hydrocarbon manifolds 21. A plurality of blast burners, adapted to inject a blast flame into the annular chamber so as to impinge upon the perforated partition wall 4, are shown at 22 positioned diametrically opposite the inlet chamber and connected to the fuel gas manifold 23.

The inner chamber is provided with a stack gas outlet 24 and the effluent chamber is provided with an outlet 2S.

The several walls of the chamber, including the peri' forated partition Wall, are composed of highly refractory Iof the chamber should be well insulated material, advantageously a ceramic material, such as conventionally used as furnace refractories, and adapted to withstand extremely high temperatures. The outer walls to reduce heat Patented Mar. l15, 1955 4afronden losses. Where desired, la Vsuitable catalyst may be 'deposited on the walls of the perforations to promote the desired reaction.

In operation, the perforated cylinder is highly heated by blast lames impinging thereon from the blast burners 22. Under As'ome conditions, it may be desirable to use a single blastburnen'or some othertyp'e of heateradap'ted to -heat theperforated cylinder substantially uniformly over its entire height. For mypresent purpose, I `prefer to'use 'a plurality of blast burners 'uniformly spaced over the entireheight of the'furnace chamber, as shown.

During the heating, the refractory cylinder is, with advantage, rotated `about its axis 'and highly heated before introduction ofthe hydrocarbonto be decomposed is initiated. At leastasegment of the perforated cylinder sufiiciently'wide toextend pastthe inlet chamber should be thus preheated. Whenthe segment Aof the perforated cylinder within 'the'inlet zone has been brought to 'the desired temperature, the .gaseous hydrocarbon to be pyrolyzed is passed to the 4inlet chamber under sufficient pressure to force Ait through the perforations in that segment of therefractory cylinder moving past the inlet chamber.

It is desirable, of course,that thepassing'of the hydrocarbons through the perforations be as uniform as'possible over the entire height of the chamber and, for this reason, it is advantageous to introduce the hydrocarbon to the chamber through a plurality of inlet chambers uniformly spaced over its height.

Advantageously, the effluent chamber is maintained under a subatmospheric pressure so as to minimize loss of the hydrocarbon through `the narrow 'clearances betweenthe surfacesfof the cylindrical wall and the walls of the inlet chamber and etlluent chamber,1respectively. By maintaining thepressure'just sufficient to minimize such loss of hydrocarbon, the influx of combustion gases from the inner chamber is'also minimized.

After the apparatus had been brought up `to temperature and other operating conditions established, the process may be carried on continuously without interruption of theproductive cycle. Temperature conditions may be maintained constant, as previously noted, by regulation of the blast ames, `or other heating means, and the speed at which the perforated refractory cylinder is rotated.

In 'operations of this sort, whether in the production of carbon black, or to effect a lesser degree of pyrolysis, some carbon will almost inevitably be deposited on the perforated refractory cylinder. Insome types of operation, this is actually desirable, as the deposited carbon tends to catalyze the reaction. Also, 'a relatively thin deposit of carbon tends to seal the clearances between the surfaces of the perforated cylinder and the walls confining the inlet chamber and the eflluent chamber. However, where desirable, theblast burners may be so adjusted as to burnoff, in the 'heating zone, any carbon deposited on the perforated `cylinderin thelpyrolysis zone. Such burning-off-'of the carbon deposits 'may be facilitated by the use of a somewhat oxidizing blastame `in the heating zone.

It is generally preferred .that the perforated'refractory cylinder be rotated continuously as more uniform operation isthereby obtained. Howeveryif 'tlesired,`the cylinder may be intermittently rotated so as .to interpose a fresh, highly 'heated segment in the path of the hydrocarbons when theprevious segment has been cooled to some predetermined temperature.

The dimensions of the apparatus are subject to considerable variation dependingprimarily upon the desired capacity of the apparatus and extent of pyrolysis required. In the particular apparatusshown, the segment ofthe rotating cylinder within the pyrolytic zone is only about one-seventh of its circumference. This, ofcourse, may be increased, or decreased, as desiredywithout departing from the spirit ofthe present invention.

As illustrative of suitable dimensions of the apparatus, the perforated refractory cylindermay, for instance, 'be three feet indiameter and'three feet in' height, the walls thereof 'being four inches thickwith perforations 1% inch in diameter and positioned on 3A inch centers. The optimurnthiclcness vof the wall andsize and-positioning of perforationswvill `vary depending upon the contemplated operation and theextentfof `contact `and heating period required. `In thepyrolysis :of natural gas, for instance, the `temperature of the refractory cylinder should be sufficient to-heat the gas to a temperatureof: aboutf2500 l F. and a contact time of the order of 0.01 second will generally be found adequate. Where destructive decomposition of the hydrocarbon to produce carbon black is desired, the rate of throughput will ordinarily be reduced and, hence, the contact time will be very substantially increased.

In the heating zone, the `blast-llames of the hot products of combustion willimpinge directly on that segment of the refractory cylinder withinthat zone and will pass through the perforations thereof into `the inner chamber 5. The resultant flue `gases may be withdrawn from the chamber 'through the `outlet '24 and pass to a stack, or otherwise disposed of.

The hot pyrolysis gases from the effluent chamber are withdrawn therefrom through the outlet 25 and may be treated in various ways, depending upon the character and purpose :of the operation. In the production of carbon black, the etiluent gases, carrying particles of carbon in suspension, vmay be passed through conduit 26, through cooler 27 to carbon black precipitatorcollector Z8, suitable coolers and precipitators being wellknown to the art. The carbon black is thereby separated and collected at `29. From the precipitator-collector, the residual gases pass off 'through line 430 andmay be disposed of, as desired.

Usually, this residual lgas will containa substantial proportion of gas suitable for heating .purposes and may be used, to advantage, in the reheating of the rotating refractory cylinder. When such disposition of the gas is contemplated, `valve 31 maybe closed and valve '32, in conduit 33 opened and the residual gas passed through thecheck valve 34 'and line 35 to the fuel gas manifold'23. Where desired, this gas may be supplemented yby other Yfuel gas supplied'throug'h valved connection 36.

Where'pyrolysis is of a lesser `degree thanthat resulting in 'carbon black, -valve 37 in line 26 may be closed and the Aeffluent gases withdrawn through the valved connection 38.

Inthe production of carbon black, for instance, the hydrocarbon 'to Abe `pyrolyzed, in accordance with my present process, may consist primarily of methane, natural gas, for instance, or it may consist of hydrocarbons of higher molecular weight 'than methane, either normally gaseous, or adapted :to Vaporize Without objectionable coking. For instance, natural gas-enrichedby mixing the vapors of'higher molecularweight therewith, may be used either as such, or diluted with steam, or other diluent.

Suitable means for maintaining the efuent chamber under'areduced pressure'are'well knownto the art and need notherebe described. Itis, of course, usually desirable 'to place'such means lin the Aeffluent 'line beyond the `pointwhere the eiuentgaseshave 'been substantially cooled. Advantageously, it may be interposed in line 33 or 35, where the ,gases are to be used for reheating the refractory cylinder. 4Under other conditions,'it would be placed in line "30 `or 38.

I claim:

Apparatus for the pyrolysis of hydrocarbonscomprising a verticallyextending, stationary outer wall and top and bottom walls .delineating a vertically extending cylindrical 'furnacechamben a substantially uniformly, radially perforated refractory cylindrical `partition wall Iof `substantial thickness coaxially positioned in the furnacechambenextending substantially the fullheight of said chamber,` having an imperforate .portion extending through the said bottom wall` and being rotatably supported by means outsideof ,saidchamben sealingfmeans betweenthe lower-end` of saidpartition wallrand the side and vbottom walls ofthe furnace chamber, the said walls forming 4an annular chamber and `an inner chamber, means outside ofthe furnace .chamber for rotating said partition wall `aboutzitsvertical axis, an impervious partition wall within the inner chamber, `an eluent chamber'within theinnerzchamber delineated by `said top and bottom walls, `said imperviouszpartition .walls i within the inner chamber and a segment of Vthelperforated parti- `tion wall, `an inlet chamber separated from said annular chamber and radially lpositioned with respect to the etiluentchamber, the inner wallvof said inlet chamber being the segment of the'per'forated partition-forming a wall of the efuent chamber, a 4burner `port extending `through fthe outer-wall and'removed from the inlet chambenan inlet for passing Ahydrocarbons into ysaid inlet chamber and separate outlets from the effluent chamber and the 2,319,679 Hasche et al. May 18, 1943 inner chamber, respectively. 2,334,555 Howard Nov. 16, 1943 2,389,636 Ramseyer Nov. 27, 1945 References Cited in the le of this patent 2,558,861 Liggett July 3, 1951 UNITED STATES PATENTS 5 FOREIGN PATENTS 1,724,982 Trumble Aug. 20, 1929 543,093 Great Britain Feb. 10, 1942 2,106,137 Reed 1. Ian. 18, 1938 578,311 Germany June 12, 1933 2,246,345 Campbell June 17, 1941

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