DE1242305B - Plant for the production of carbon black - Google Patents

Description

GERMAN JfflVWt PATENT OFFICE

EDITORIAL

German class: 22f-14

Number: 1242 305

File number: C31260IVa / 22f 1 242 303 Filing date: October 29, 1963

Open date: June 15, 1967

The invention relates to an improved plant for the production of carbon black, and in particular one improved plant for the production of carbon blacks with good abrasion resistance, which are used as filler material for rubber Find use.

The production of soot from normally liquid hydrocarbons according to the so-called The oil black process is known per se. It is based on the incomplete combustion of hydrocarbons Material with air in a thermally insulated reactor, with some of the fuel through the developed heat of combustion is cracked. Various modifications to this general procedure have been described. In the generally practiced technical embodiment of the method as in the process on which this invention is based, a heating or fuel gas, such as natural gas, propane, vaporous petroleum distillate od. Ä., With a sufficient amount of a free Oxygen-containing gas, usually with air, burned in a reactor and this normally liquid starting product for the soot is sprayed into the resulting flame or its combustion products. Usually the soot furnace slightly more than the amount of air necessary for complete combustion of the heating gas is supplied, however, only a very small part of the soot oil is also burned.

In the German patent 1 201 506 related to the present invention of the inventor, it is essentially an all-metal reactor in which the pyrolysis reaction in a metal reaction tube provided with a heat-conducting, refractory lining is carried out, the required combustion air previously flowing around the outer surface of the reaction tube and thereby advantageously preheated will. The preheated combustion air is then referred to as a "semolina eliminator" Combustion guide device mixed with the heating gas in a turbulent manner and the mixture in the reaction tube burned. An excellent feature of this system, especially in terms of its application of the various embodiments of the present invention, is the relatively simple construction. the various parts that make up the carbon black furnace are designed so that regardless of the high reaction temperatures Each element can be shut down and cooled and then used in a fraction of the time Time that is required for corresponding measures in other systems can be dismantled can.

Plant for the production of carbon black

Applicant:

Continental Carbon Company, Amarillo, Tex.
(V.StA.)

Representative:

Dr. W. Gennershausen, patent attorney,
Frankfurt / M., Gärtnerweg 28

Named as inventor:

Norman Royce Higgins, Bakersfield, Calif.

(V.StA.)

Claimed priority:
V. St. v. America October 30, 1962
(234 032),

of March 27, 1963 (268 382)

The quality of the soot that is obtained by the method described depends primarily Line from the turbulence of the flame used for cracking, which in turn is caused by the Construction of the furnace is conditional. In general, the particle size of the soot is a function of the Turbulence is, namely the smaller the particle size, the more violent the turbulence is.

In principle, there are two ways of generating a flame that is as turbulent as possible at the moment customary technical systems for soot production using a cylindrical reactor. the one method is to create a continuous centrifugal flame on one End of the soot furnace. The soot oil intended for cracking is continuously fed axially into the flame or combustion gas vortex sprayed in. The second method uses a turbulent and im essentially longitudinally progressing flame generated at one end of the reactor and that Soot oil is continuously fed to the base of this flame.

The main advantage of the centrifugal flame method is the high soot yield. Interfering Kohleab- distinctions on the inner wall of the reactor do not occur in this method. The only disadvantage is that the number of types of carbon black that this

709 590/292

Way that can be generated is limited. On the other hand, the principle advantage of the longitudinal flame method is to be seen in the greater versatility with regard to the achievable carbon black qualities. on the other hand the known plants operating with longitudinal flame char very easily, and furthermore is at With the same type of carbon black, the achievable yield is lower than with the centrifugal flame method.

The system described in German Patent 1 201 506 is for operation with the centrifugal Constructed flame. The present invention is an improved system for Soot extraction, either by the centrifugal flame method or the longitudinal flame method can be operated. The system according to the invention is superior to the known systems in that when the longitudinal flame method is carried out no charring of the walls takes place and the soot yield to be achieved above is also much higher than in the known systems working with the longitudinal flame and in fact almost reached the yields attainable with the centrifugal flame method. When the system according to the invention is operated by the centrifugal flame method, soot qualities which show excellent abrasion resistance properties and of much improved Structural characteristics are as they were previously obtained by the centrifugal flame method. These types of carbon black are ideal as filling material for rubber goods.

The advantages listed are achieved in the system according to the invention for producing carbon black by turbulent pyrolysis of hydrocarbons, consisting of a reaction tube (11) FIG. 1, which is concentrically surrounded by a tubular housing (10) for supplying and preheating the combustion air in a countercurrent process and in front of one end of the reaction tube (11) forms a chamber (13) into which the devices for introducing heating gas, hydrocarbons and air axially protrude, wherein the reaction tube (11) is a metal tube with a smooth outer surface, a refractory, heat-conductive inner lining (12) and the same opening widths at both ends and mounted within the chamber (13) outwardly extended truncated cone-shaped extension (36) having a plurality Rows of radially extending slots (37 or 32) serve as a guide device for the combustion air, which is characterized in that the end of the frustoconical extension (36) facing away from the reactor reaches close to the end member (16) of the housing and is connected by one with a concentric opening provided lid (38) is completed and the thermally conductive, fire solid inner lining of the reaction tube in the initial part of the tube is designed so that it has the shape of a Venturi tube, the length of this Venturi tube-shaped section being substantially less than the total length of the reaction tube.

As already stated, these are the characteristic properties of the flame in such systems the cracking of the soot oil is of great importance; Yield, production speed and especially the soot quality is determined by the particular type and general conditions such as Temperature and turbulence of the flame are essential

influenced. The soot furnace described in the cited patent is provided with a device which serves to regulate the entry of the combustion air into the reaction chamber and thus the The flame and the cracking conditions prevailing at the point where the dissociation of the soot oil begins, to regulate.

Another feature of the improved system of the present invention is a modification

ίο this component referred to in the patent specification as the “grit eliminator” and in the following as the “combustion control device”. The extent to which the improved combustion control device differs from the previously used one can be seen most clearly from the description in connection with the drawings. It is pointed out in particular that the physical-technical difference between the two embodiments of this device appears to be slight, but the effect achieved thereby is, as already stated, very essential and considerable.

The explanations given below serve for a better understanding of the nature of the invention Appendix and the drawings.

F i g. 1 shows a longitudinal section through one based on the knowledge according to the invention Soot furnace, which was created by combining the heating burner with an injection device for the soot oil Component is only partially cut open so that the design features can be better recognized leaves;

F i g. Figure 2 is part of the longitudinal elevation of the furnace and is intended to illustrate a feature of the invention;

F i g. Figure 3 is a cross-sectional view taken on line 3-3 of Figure 2;

F i g. Figure 4 is part of the longitudinal elevation of the furnace and is intended to illustrate an embodiment thereof.

In Fig. 1 as in the other figures, the numeral 10 denotes an elongated metal housing which represents the outer casing of the soot furnace system according to the invention; Arranged concentrically therein is another elongated metal tube or reaction tube of a smaller diameter than that of the housing. This tube 11 is expediently held in a concentric position in the housing 10 by a plurality of spacer bars welded onto its outside. The reaction tube 11 is provided with a refractory inner lining 12, which preferably consists of a material with a relatively high coefficient of thermal conductivity. The refractory inner lining 12 has in most of the pipe 11 only the minimum thickness necessary for adequate protection of the pipe over a longer period of operation. This minimum thickness depends on the strength properties of the lining material used; For example, when using silicon carbide, a thickness of 5 to 13 mm is sufficient. Suitable other linings can be made on-site from conventional, malleable refractory materials, such as. B. from materials based on kaolin. It is advisable to use larger wall thicknesses and, if necessary, to reinforce the lining by reinforcing it with iron bars. In an operating reactor of the type described, a lining based on kaolin has a thickness of 50 mm

With a diameter of the metal pipe of 355 mm, it has proven to be sufficient over a long period of time even without reinforcement and has shown good thermal conductivity values. As already stated, the reaction tube improved according to the invention differs from the one previously used by the particular shape of the reaction zone. This zone is characterized here by a Venturi section, the neck of which lies in the vicinity of the inlet opening within the tubular component 11. The Venturi section can be formed by an appropriate configuration of the refractory lining 12 of the tube 11 and has only an insignificant effect on the overall heat transfer capability of the reaction tube combination. The downstream ends of the outer jacket or housing 10 and the inner tube 11 terminate with one another at the same height. The outer jacket 10 can consist of normal steel pipe and should be slightly longer than the inner pipe 11 so that it protrudes a bit at the upstream end and thus forms a practically open cylindrical chamber in which certain accessories of the system are arranged, including the Combustion control device 36 improved according to the invention.

The outer housing 10 can have a length of 3 to 4.5 m, and the inner tube 11 is correspondingly shorter by about 60 to 90 cm. Both can be standardized steel tubes, whereby the outer tube can have a diameter of 45 cm and the inner tube can have a diameter of 25 to 35 cm. When using a reaction tube of these dimensions, the neck of the venturi can be approximately 15 to 90 cm and more from the inlet opening of the tube. The cross-sectional constriction zone of the neck can be 20 to 90% and more, preferably 30 to 50% of the maximum cross-section of the reaction tube and then merge into the circular cross-sectional zone of the lined outflow end. Suitable opening widths of the convergent and the divergent angle of the Venturi section are between 7 to 15 and 4 ° or less, measured to the longitudinal axis of the reaction tube.

When the furnace is in operation, the combustion air enters through the air inlet openings 14 located near the furnace outlet tangentially into the annular space formed by the housing tube 10 and the inner tube 11 and flows helically towards the upstream end of the annular space . The air preheated in this way enters the chamber 13 through the slot-shaped openings 37 of the truncated cone 36 and mixes with the heating gas emerging from the burner openings 22. The combustion of the mixture begins already within the chamber 13 , and the resulting flame extends into the inner tube 11. The soot oil that is sprayed in is cracked as soon as it comes into contact with the flame. The resulting aerosol flows to the furnace outlet, where it is quenched by a water mist so that no further reactions take place and the temperature drops so far that it can be fed to a conventional soot separator.

The improved combustion control device 36 has the shape of a truncated cone jacket and is fastened with the smaller opening on the abutting end of the inner tube. The truncated cone jacket can

be made of a heat-resistant metal sheet made of stainless steel. The combustion control device is so long that its further opening is a few centimeters away from the end plate 16. The exact distance depends on the amount of air which is to enter the chamber 13 through the combustion control device. The aim should be to guide all air through the combustion guide device 36 , but it has proven to be useful to ίο about 10% of the total air along the inside of the end plate 16 through the opening in the center of the cover 38 of the truncated cone into the chamber 13 to direct. As a result, the end plate 16 and the abutting system parts such as the housing jacket are kept cool. The outer surface of the truncated cone is provided with several rows of air slots 37 which are arranged in concentric rings. In Fig. 1 these slots are shown in several rows, in a shovel-like manner that protrudes outward relative to the surface of the truncated cone. In the drawing, the slot zones are shown approximately the same size for the sake of simplicity. However, it has proven to be expedient to gradually widen the slot-shaped openings to the extent that the rings in which they are arranged approach the base of the truncated cone facing the end plate 16. The truncated cone is provided with the cover 38 at its base. This cover has a central opening which is so wide that the combined burner and injection device protrude and, moreover, the air flowing past the end plate 16 can enter the interior of the combustion control device. However, the diameter of this opening is still much smaller than the diameter of the smaller opening of the truncated cone.

The combined gas burner and soot oil injection device is shown in FIG. 1 denoted by the number 15. It extends through the end plate 16 therethrough, and forms with it, the closure element at the upstream end of the housing 10. In detail, the burner and the injection device consists of a tube 17 which axially passes through the end plate 16 and is rigidly fixed in an appropriate way, for example by means of a stuffing box. A tube 18 is arranged concentrically inside the tube 17 and preferably projects beyond the end of the tube 17 into the space of the cylindrical chamber 13 . A vertically arranged disk 19 closes the annular gap formed by the tubes 17 and 18 at the end protruding into the chamber 13 and is firmly welded to these tubes. The purpose of the disc 19 is to protect the flame from being blown out during operation of the furnace. The diameter of this disc is substantially larger than the outer diameter of the tube 17, but substantially smaller than the opening width of the refractory lined reaction tube 11 by means (not shown) mounts is concentrically mounted a feed pipe 20 within the pipe 18, which at approximately the same height as the corresponding end of the tube 18 ceases. Immediately behind the disk 19 are several radial openings 22 in the tube 17, which form a connection between the chamber 13 and the annular space formed by the tubes 17 and 18. The end in the soot furnace

the feed line 20 can be provided with an atomizer nozzle or can remain open if an easily evaporating oil is used to form soot. The other (outwardly protruding) end of the tube 17 is closed by an annular component 21 . The heating gas is supplied through the gas line 23. Behind the annular closure 21 , the air supply 24 is arranged, through which air is introduced into the annular chamber between the inside of the tube 18 and the outside of the line 20 . This annular chamber is closed off from the outside by the ring 25 . The air flowing axially around the oil line 20 emerges as a bundled jet around the oil mist flowing out of the line 20 or the atomizer nozzle and thus helps to direct the injected oil into the center of the tube 11. In addition, this axial air flow prevents the nozzle tip from becoming carbonized, which would impair the atomization capacity.

The carbon black oil can be used within the ranges shown in FIG. 1 can be sprayed in principle at every point of the cylindrical chamber 13 or also in the initial part of the reaction tube. Preferably, especially when using the longitudinal flame method, the spray head is attached at the level of the beginning of the inner tube 11.

The quenching part of the system connects to the outflow end of the refractory lined inner pipe 11; the number 26 in F i g. 1 refers to part of this section. This part can also consist of a cylindrical metal tube with the same outer diameter as the housing 10 and is lined with refractory material or insulating materials so that its inner diameter corresponds to that of the inner tube 11. The quenching part can be connected to the housing 10 and the inner tube 11 by a flange, this flange simultaneously serving as a closure of the annular space lying between the inner tube 11 and the housing 10. The attachment of the Hansches can be done by riveting or welding. In the quenching part 26 a gate 27 is arranged through which a water line 28 leads to the longitudinal axis of the pipe and ends there in a spray head 29 which is directed in the opposite direction to the flow of gas and soot emerging from the reaction pipe.

As already stated, the carbon black furnace improved according to the invention can be operated with the longitudinal flame method or also with the centrifugal flame method. The basic construction is the same for both versions. The only differences are in the position of the air slots of the combustion guide device and in the direction of the guide plates for the combustion air arranged in the annular gap between the tubes 10 and 11.

In Fig. 4 shows an apparatus which is provided for the production of carbon black by the centrifugal flame method. The combustion guide device is designated here by the number 34 , but is identical to that in connection with FIG. 1 apparatus 36 described except for the air guide device, in this case, the portion with the vanes 35, the arrangement of the remaining components is identical to the in F i g. 1 parts numbered in the same way.

The air guiding device consists of a series of equally spaced parallel to each other helically through the annular space between the tubes 10 and 11 , perpendicular to the outer wall of the tube 11 , the height of which corresponds to the distance between the two tube walls, whereby there must be enough space for the thermal expansions occurring under operating conditions. The section with the air guide vanes is expediently only a short distance from the inlet opening of the reaction tube 11. This practically prevents the combustion air from entering the chamber 13 or from striking the combustion guide device in a straight line. Any number of baffles can be used and their attachment is also optional. For example, they can with the inner tube 11 can be welded or a ge through the pipe 11 zo coated annular band or in a similar manner. In this construction, the baffles also serve as a holder and ensure the concentric arrangement of the outlet end of the reaction tube 11 within the housing jacket 10.
As during operation of the arrangement shown in Fig. 4, the combustion air flowing through the annular gap between the pipes 10 and 11 leaves the area of the air guide plates 35 in a helically wound manner, depending on the chosen angle of inclination of the guide plates to the axis of the entire system, and the majority of these Preheated air enters the chamber 13 in the form of an inwardly directed spiral. Here, the air mixes in a turbulent manner with the heating gas emerging from the radial openings 22 of the burner, and the resulting combustible mixture flows helically through the refractory-lined reaction tube 11. The mixture begins to burn in the chamber 13 . Due to the ratio of the opening widths of the chamber 13 and the venturi, the maximum temperature is only reached in the throat of the venturi. As already mentioned, the soot oil is injected above the point of maximum temperature and turbulence. Since velocities of the order of magnitude of the speed of sound occur, the - vaporous or finely sprayed - soot oil remains largely undissociated until it reaches the venturi throat, where it is then instantly and essentially completely cracked.

The in F i g. The embodiment shown in FIG. 2 is intended for operation according to the longitudinal flame method. This flame shape is generated in that the air is guided axially through the annular preheating space between the jacket 10 and the inner tube 11 . The combustion air occurs as in FIG. 4 through the air inlet openings 14 into the annular preheating space at its downstream end and is driven under pressure against the upstream part of the furnace, ie in the direction of the cylindrical chamber 13. The air entry through the openings 14 can also take place here in a tangential direction , because the air guiding device ensures a strictly axial air flow. In this case it consists of a plurality of guide plates 30 which run parallel to one another at the same distance and which run in the direction of the axis of the tube 11 and

Claims (1)

are fastened perpendicularly to the outer surface thereof or in a similar manner as in connection with FIG. 4 described are welded on a tape or a thin sleeve drawn over the Rohrll. The length of the guide plates can be between 60 and 120 cm, and they can also be used to hold the inner tube in the housing. It is advisable to use several such baffles. The plates are located in the region of the upstream end of the annular gap between the tubes 10 and 11. The upstream edges of the metal sheets can be pushed forward to the end of the gap, but they can also lie further downwards, as in FIG. 2 can be seen. The combustion control device arranged within the chamber 13, here designated by the number 31, has the same basic shape and the same dimensions as that in connection with FIG. 1 and F i g. 4 described combustion guide device 36 or 34. In contrast, in this embodiment, the air slots located in the conical stem jacket - here denoted by the number 32 - are arranged in concentric rings perpendicular to the longitudinal direction of the air movement. The slot-shaped openings 32 are preferably wider the closer they are to the end of the combustion control device facing the end plate 16 of the housing tube, which in turn is in the same way as in FIG. 1 described is completed with a cover 38. The in F i g. The apparatus shown in FIG. 2 is operated essentially in the same way as in connection with FIG. 4, with the exception that the air guiding means present in this modification causes a flame to advance substantially longitudinally in the reaction tube downstream. The burner used is identical to the burner component from FIG. 1. With this arrangement it is expedient that soot oil is sprayed in before the neck of the venturi, i. H. at the inlet opening of the reaction tube 11, so that the cracking of the carbon black oil takes place essentially in or near the throat of the venturi. Patent claims: 1. Plant for the production of soot by turbulent pyrolysis of hydrocarbons, consisting of a reaction tube (11), which is concentrically surrounded by a tubular housing (10) for supplying and preheating the combustion air in a countercurrent process and in front of one end of the reaction tube (11) forms a chamber (13) in which surface the devices for introducing heating gas, hydrocarbons and air protrude axially, wherein the reaction tube (11) is a metal tube with a smooth outer surface, a refractory, thermally conductive inner lining (12) and the same opening widths at both ends is and a frustoconical one that is fitted inside the chamber (13) and widened outward Extension (36) with several rows of radially extending slots (37 or 32) as a guide device serves for the combustion air, characterized in that the turned away from the reactor The end of the frustoconical extension (36) extends to close to the end member (16) of the housing and through a with a concentric opening provided lid (38) is closed and the thermally conductive, the refractory inner lining of the reaction tube is formed in the initial part of the tube in such a way that that it has the shape of a venturi tube, the length of this venturi tube-shaped section is significantly less than the total length of the reaction tube. 2. Plant according to claim 1, characterized in that the in the annular gap between Housing and reaction tube attached air guide devices (35) from a number in parallel consist of sheet metal strips running helically around the reaction tube, whose height corresponds to the gap width and which is perpendicular to the outside of the reaction tube are attached and arranged so that the air flowing through the gap in the form of a after inward spiral to the upstream end of the reaction tube and into the Chamber (13) flows. 3. Plant according to claim 1, characterized in that the attached in the annular gap Air guiding devices (30) from a number parallel to each other and parallel to Axis of the reaction tube (11) are made of sheet metal strips, the height of which is the width of the gap and the perpendicular attached to the outside of the reaction tube and so are attached that the air flowing through the gap in the direction of the axis of the reaction tube to the chamber (13) located at the upstream end of the reaction tube. Considered publications:
German Auslegeschrift No. 1 123 782;
French Patent No. 1,275,686;
British Patent No. 840 504;
U.S. Patent No. 2,851,337. 1 sheet of drawings 709 590/292 6. 67 © Bundesdruckerei Berlin