FR2645542A1 - METHOD FOR CONTROLLING THE SIZE OF THE AGGREGATES AND THE STRUCTURE OF CARBON BLACKS - Google Patents

Abstract

A method for controlling the aggregate size and structure of carbon blacks produced by a kiln carbon black reactor is disclosed. According to the invention, the temperature of the pyrolysis is lowered, but it is not stopped, in the effluent (the mixture of combustion gas and the feedstock where the pyrolysis occurs), preferably of about 444 degree (s) C, at a residence time of between about 0.0 seconds and about 0.002 seconds downstream of the most downstream point of feedstock injection. The invention applies in particular to the production of carbon blacks.

Description

The present invention relates to a method for controlling the size

aggregates and the structure of

carbon blacks.

  Carbon blacks are generally produced in a furnace reactor by pyrolysis of a hydrocarbon feedstock with hot combustion gases to produce combustion products containing

particulate carbon black.

  In a type of furnace carbon black reactor, as shown in US Patent No. 3,401,020 to Kester et al. Or US Patent No. 2,785,964 to Pollock, which will be referred to herein as after "Kester" and "Pollock", respectively, a fuel, preferably hydrocarbon, and an oxidant, preferably air, are injected into a first zone and react to form hot combustion gases. A hydrocarbon feedstock in gaseous form, vapor or liquid is also injected into the first zone and then begins pyrolysis of the feedstock.

  hydrocarbon. In this case, the pyrolysis indicates the.

  thermal decomposition of a hydrocarbon. The resulting mixture of combustion gases, where the pyrolysis takes place, then passes into a reaction zone where the reaction forming the black of the reaction occurs.

carbon.

  In another type of furnace carbon black reactor, a liquid or gaseous fuel reacts with an oxidant, preferably air, in the first zone to form hot combustion gases. These hot combustion gases pass from the first zone, downstream, through the reactor, into a reaction zone and beyond. To produce carbon blacks, a hydrocarbon feedstock is injected at one or more points into the path of the hot combustion gas stream. The hydrocarbon feedstock may be liquid, gaseous or vaporous and may be the same or different from the fuel used to form the flue gas stream. The first zone (or combustion zone) and the reaction zone may be divided by a constriction or zone of restricted diameter of a smaller cross-section than the combustion zone or the reaction zone. The feedstock can be injected into the path of the hot combustion gases upstream of

  or downstream of and / or in the restricted diameter zone.

  Furnace carbon black reactors of this type are generally described in the US patent reissue

  No. 28,974 and US Patent No. 3,922,335.

  Although two types of black reactors

  furnace carbon and processes have been described,

  that the present invention can be used with any other oven-carbon reactor or process where the carbon black is produced by pyrolysis and / or

  incomplete combustion of hydrocarbons.

  In the two types of processes and reactors described above and in other generally known reactors and processes, the hot combustion gases are at a temperature sufficient to effect the pyrolysis of the hydrocarbon feedstock injected into the gas stream. of combustion. In one type of reactor, as disclosed by Kester, the feedstock is injected at one or more points into the same zone as the flue gas is formed. In reactors or processes of other types, feedstock injection occurs in one or more

  points after forming the flue gas stream.

  In each reactor type, as the stream of hot combustion gases flows continuously downstream through the reactor, pyrolysis occurs continuously as the mixture of feedstock and combustion gases passes through the zone. of reaction. The mixture of feedstock and flue gas where pyrolysis occurs will be referred to hereinafter throughout

  description, "the effluent". The residence time of

  the effluent in the reaction zone of the reactor is sufficient and, under certain conditions, suitable for the formation of carbon blacks. "Residence time" indicates the time that has elapsed since the initial contact between the hot combustion gases and the feedstock. After forming carbon blacks with the desired properties, the temperature

  effluent is further reduced to stop pyrolysis.

  This decrease in the temperature of the effluent to stop the pyrolysis can be accomplished in any known manner, such as by injection of a fluid. cooling in the effluent. As is generally known to those skilled in the art, pyrolysis is stopped when the desired products of carbon black have been obtained in the reactor. One way to determine when pyrolysis is to be stopped is to sample the effluent and measure its level of toluene extract. The level of extract in toluene is measured by the American standard ASTM D1618-83 "Carbon Black Extractables - Toluene Discoloration". The quench nozzle is generally set at the point where the level of toluene extract in the effluent reaches an acceptable level for

  the desired carbon black produced in the reactor.

  After stopping the pyrolysis, the effluent generally passes through a bag filter system to separate

and collect the carbon black.

  In general, only one quench is used. However, Kester reveals the use of two quenchs to control certain properties of carbon blacks. Kester refers to the control of the properties of carbon blacks to impart the module, by heat treatment. This heat treatment is obtained by regulating water flows to two jet nozzles, which are placed in series in the smoke of the effluent in a carbon black furnace. The modulus of a carbon black is related to the performance of it in a rubber product. As explained in the article of

  Schaeffer and Smith, "Effect of Heat Treatment on Reinfor-

  "Properties of Carbon Black" (Industrial and

  ring Chemistry, Volume 47, N 6; June 1955, page 1286), hereinafter "Schaeffer", it is generally known that the heat treatment will aim to give the carbon black its properties imparting the module. However, as is better explained by Schaeffer, the change in the properties imparting the modulus of carbon blacks produced by heat treatment results from a change in the surface chemistry of carbon blacks. Therefore, the positioning of the nozzles as suggested by Kester, in order to subject the flue gas stream to different temperature conditions, affects the properties imparting the modulus of carbon black apparently by changing the surface chemistry of blacks. rather than affecting the

  morphology of carbon blacks in a discernible manner.

  On the other hand, use Kester, the two nozzles are placed at a position in the reaction zone where significant pyrolysis of the feedload has already occurred. Thus, it would appear that in the Kester process, at the time the effluent reaches the first tuyere, the properties of CTAB, hue, DBP and Stokes diameter of the carbon blacks were defined. This supports the conclusion that the change in properties imparting the modulus in Kester does not result from a change in the morphological properties of carbon blacks. Moreover, Kester attaches no importance to the position of the first nozzle relative to the feed injection point or the residence time and discloses no way to choose the

  position of the first quenching nozzle or cooling.

  U.S. Patent No. 4,230,670 to Forseth, hereinafter referred to as Forseth, suggests the use of two nozzles to stop pyrolysis. The two nozzles are separated from the point where a single nozzle would be placed. -The two nozzles are intended to better fill the reaction zone of the quenching fluid to more effectively stop

  pyrolysis. However, at Forseth, at the moment when

  fluent reaches the nozzles, the properties of CTAB, dye, DPB and Stokes diameter of carbon blacks were defined. U.S. Patent No. 4,265,870 to Mills et al. And U.S. Patent No. 4,316,876 to Mills et al. Suggest the use of a second nozzle downstream of the first nozzle to prevent degradation in the filter system. . In both patents, the first nozzle completely stops pyrolysis and is placed in

  a generally known position, and at the moment when the

  fluent reaches the first nozzle, the properties of CTAB, hue, DBP and Stokes diameter of carbon blacks were defined. The second nozzle further reduces the temperature of the flue gas stream to protect

the filter unit.

  U.S. Patent No. 4,358,289 to Austin, hereinafter "Austin", also relates to the prevention of degradation of the filter system by the use of a heat exchanger after the nozzle. In this patent also, the nozzle completely stops pyrolysis and is placed in a generally known position. At Austin, when the effluent reaches the first nozzle, the properties of CTAB, hue, DBP and Stokes diameter of

  Carbon blacks have been defined.

  U.S. Patent No. 3,615,211 to Lewis, hereinafter "Lewis", relates to a process for improving the uniformity of carbon blacks produced by a reactor and for expanding

  the life of a reactor. To improve the uniformity

  In order to maintain a substantially constant temperature in this area, Lewis suggests the use of a number of tuyeres placed throughout the reaction zone. A certain amount of the quenching fluid is injected into the nozzle which is placed furthest upstream in the reactor with a larger amount of quenching fluid injected at each subsequent downstream nozzle. The nozzle placed furthest downstream stops the pyrolysis. By maintaining a constant temperature in the reaction zone, the Lewis apparatus promotes the uniformity of the carbon blacks produced by the apparatus. However, the various nozzles do not control the morphology of the carbon blacks produced by the apparatus. However, it is generally desirable to be able to control the morphology of carbon blacks so as to produce carbon blacks well suited for a particular end use. It is also desirable to increase the size of aggregates and carbon black structure for a given surface area, because increased aggregate size and structure, represented by larger BOP, lower hue, and larger diameter. Stokes make

  carbon blacks better suited to certain end uses.

  Accordingly, the subject of the present invention is

  to provide a method for controlling the size of

  aggregates and the structure of carbon blacks.

  It is an additional object of this invention to produce carbon blacks having larger aggregate sizes and a larger structure for

surface area given.

  A method has been discovered that achieves these desirable goals. It has been discovered that the morphology of the carbon blacks produced in a furnace carbon black process can be controlled by lowering the temperature of the effluent without stopping the pyrolysis, preferably about 444 ° C, in one step. specified residence time of up to 0.002 seconds downstream of the point

  the most downstream of the injection of the feedstock.

  The decrease in temperature can be accomplished by locating a first nozzle at or within about 1.22 meters downstream of the most downstream point of feedstock injection and fluid injection. quenching. According to the present invention, the production of carbon blacks can be controlled to produce carbon blacks having specific morphological properties such as greater aggregate size and increased structure as shown by a higher DBP lower hue, increased Stokes diameter for a given surface area (CTAB). It has been further discovered that these morphological properties of carbon blacks can be further controlled by changing the amount by which the effluent temperature is decreased and / or by changing the residence time from the time of the most injected injection. downstream of the feedstock

  until the temperature of the effluent is reduced.

  In more detail, the present invention relates to a method for controlling the size of aggregates and the structure of carbon blacks produced by a furnace carbon black reactor by decreasing the temperature of, without stopping pyrolysis in the furnace. effluent

  (the mixture of combustion gases and feedstock

  wherein the pyrolysis occurs at a residence time of from about 0.0 second to about 0.002 seconds, preferably from about 0.0 to about 0.0015 seconds, downstream of the most downstream point of the injection. of the feedstock. The temperature of the effluent is decreased during the above-specified residence time, preferably about 444 ° C. and more preferably between about 28 ° C. and about 444 ° C. The effluent temperature can be reduced by a nozzle, preferably a nozzle injecting the quenching fluid into the effluent, which is at a point in the reactor so that the effluent

  soaked between about 0.0 and 0.002 seconds, preferably

  from about 0.0 to about 0.0015 seconds, downstream of the most downstream point of feedstock injection. Typically, so that the effluent is soaked in the specified residence time, the nozzle will be placed at or within about 1.22 meters of the

  the most downstream point of the injection of the feedstock

  tation. The tuyere lowers the temperature of the effluent, preferably about 444 ° C and more preferably between about 28 ° C and about 444 ° C, but does not stop the pyrolysis. According to the present invention, the amount by which the effluent temperature is decreased and the residence time at which the effluent temperature decrease can be changed independently or simultaneously to control the size of the aggregates and the structure of the blacks. of carbon that are produced by the reactor. In a reactor using a nozzle, injecting a quenching fluid, to reduce the temperature of the effluent within the specified residence times, this variation in the amount of which the effluent temperature has been lowered and the residence time at which the Decrease of the temperature of the effluent occurs can be accomplished by changing the amount of quenching fluid injected through the nozzle and changing the location of the nozzle respectively. After forming carbon blacks

  having the desired properties, the pyrolysis is stopped.

  The present invention enables the production of a carbon black having a larger aggregate size and a larger structure for a given surface area than the carbon blacks produced by a similar process where the effluent temperature is not not

  lowered during the specified time of residence.

  The method of the present invention has an advantage in that the size of the aggregates and the

  structure of carbon blacks can be controlled.

  Another advantage of the method of the present invention is that carbon blacks having a larger aggregate size and a larger structure can be produced, as shown by higher DBP values, hues more weaker and larger diameters of Stokes, for an area

  superficial given, as shown by CTAB.

  The invention will be better understood, and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory text which will follow with reference to the accompanying schematic drawing given by way of example only, illustrating an embodiment of the invention and wherein: - the single figure is a cross-sectional view showing an embodiment of the present invention

  in a carbon black reactor, indicating the location

  first and second nozzle.

  The figure shows a possible embodiment of the present invention. Although only a portion of one type of a spit carbon black reactor shown in the figure, as previously explained, the present invention can be used in any carbon black furnace reactor where Carbon is produced by pyrolysis and / or incomplete combustion of hydrocarbons. By

  elsewhere, although the following description explains a

  embodiment of the present invention using a nozzle, injecting a quenching fluid, to reduce the temperature of the effluent, as those of ordinary skill will appreciate, the present invention relates to any method for reducing the temperature of the effluent. effluent, preferably of specified quantities, during

  specified residence times from the injection point

  tion of the feedstock closest to the area

  of reaction. Similarly, although the description that follows

  relates to the use of a second nozzle to stop pyrolysis, as those skilled in the art will understand it, it relates to any process for

stop the pyrolysis.

  In the figure, a portion of a carbon black reactor 10 having, for example, a reaction zone 12 and a zone of restricted diameter 20, is equipped with a first nozzle 40, which is located in point 60 and in FIG. a second nozzle 42 which is placed at point 62 to inject a quenching fluid 50. The quenching fluid 50 may be the same or different for each nozzle. The flow direction of the hot combustion gas stream through the reactor 10 and the zones 12 and 20 is shown by the arrow. The quenching fluid 50 may be injected by the first nozzle 40 and the second nozzle 42 countercurrently or preferably in the same direction, with respect to the direction of the flue gas stream. Point 14 is the most downstream point of feedstock injection 30. As will be understood by ordinary skill, point 14 is the most downstream point for the injection of the load. power supply can be changed. The distance from point 14 to the point of the first nozzle 60 is represented by L-1 and the distance from the point furthest downstream of the injection of the feedstock, point 14, to

  point of the second nozzle 62, is represented by L-2.

  According to the illustrated embodiment of the present invention, the first nozzle 60 is placed to decrease the temperature of the effluent (the mixture of flue gas and feedstock o occurs

  pyrolysis) no later than 0.002 seconds, and preferably

  from 0.0 to 0.0015 seconds, residence time from the point furthest downstream of feedstock injection. Typically, so that the effluent is quenched within the specified residence time, the first nozzle will be placed at or within about 1.22 meters of the most downstream point of feedstock injection. Therefore, L-1 will be between 0.0 and about 1.2 meters. The quenching fluid is injected through the first nozzle 40 in order to reduce the temperature of the effluent preferably by an amount of up to 444 ° C. and more preferably from about 28 ° C. to about 44 ° C. provided, however, that the quenching fluid injected by the first nozzle 40

does not stop the pyrolysis.

  In addition, according to the present invention, the residence time of the most downstream injection point of the feedstock until the temperature of the effluent

  (the mixture of combustion gases and the feedstock

  where the pyrolysis occurs) is initially lowered and the amount at which the effluent temperature is lowered can be changed independently or simultaneously to control the size of the aggregates and the structure of the carbon blacks produced by the reactor. In the embodiment of the present invention shown in the figure, a change in L-1 will change the residence time from the moment of injection most downstream of the feedstock to the moment when the effluent temperature is lowered. By changing the quantity of quenching fluid injected, the quantity of which the temperature of the effluent

is lowered can be changed.

  As explained in the foregoing paragraph, in the embodiment of the present invention which is shown in the figure, depending on the size of the aggregates and the desired structure, L-1 is typically

  from about 0.0 to about 1.22 meters.

  The quenching fluid 50 decreases the temperature of the effluent, preferably in an amount of up to about 444 C and more preferably in an amount between about 28 and 444 C provided, however, that the pyrolysis is not stopped at the first nozzle 40 by the fluid of

  quenching or rapid cooling 50.

  After producing carbon blacks having the desired properties, the pyrolysis is stopped at point 62 by nozzle 42. Point 62 is a point at which the carbon blacks having the desired properties were produced by the reactor. As previously explained, point 62 can be determined in any known manner to select the position of a nozzle that stops pyrolysis. One method of determining the position of the nozzle which stops pyrolysis is to determine the point at which an acceptable level of toluene extract for the desired carbon blacks of the reaction is obtained. The level of toluene extract can be measured using the ASTM D1618-83 test

  "Carbon Black Extractables - Toluene Discoloration".

  L-2 will vary according to the position of point 62.

  The effectiveness and benefits of this

  invention will be better illustrated by the following example.

EXAMPLE

  To demonstrate the effectiveness of the present invention, experiments were conducted in a carbon black production process using two nozzles and changing the residence time from the moment of the injection to the most downstream of the charge. supply until the temperature of the

  the effluent has been reduced and the quantity of which the temperature

  ture of the effluent has been reduced. The residence time was changed by changing L-1. Process variables and results of two sets of carbon blacks

  in the experiments are summarized in the table given below.

  below, the set 1 comprising the tests 1, 2 and 3

  and set 2 comprising tests 4, 5 and 6.

BOARD

  Tempera- Tempera- Tempera- Deco-

Ture ture ture lora-

  In-residence before the tuyè- after 2nd tuyè- after tion Dst DBP

  The test seems to be the second nozzle of the Tein nozzle in the second stage.

  o m C m C CTAB te tolueneCDBP nm teux

  1 ---- 1437 ---- 1437 1.46 732 109.2 120.5 68 109.5 98.8 86

  2 I 0.0007 1437 0.49 1216 5.9 732 100.7 110.6 45 110.0 109.6 205

  3 0,0005 1437 0.305 1216 6.96 732 94.3 102.2 73 113.4 126.9 232

  4 ---- 1410 ---- 1410 5.2 732 91.6 114.6 77 95.2 94.1 148

  II 0.0004 1410 0.305 1243 11.8 732 93.4 106.1 78 106.4 101.5 213

  6 0,0004 1410 0.305 1188 12.5 732 91.4 105.0 41 107.1 103.3 220

rL u-n U ',

Notes TABLE

  Set I: Preheating: 482 C; Gas: 203 Nm / h; Air: 2265 m3 / h; Air / Gas: 11.11; Primary combustion: 4 3 123%; Volume combustion zone: 2.4.10 Q4cm3; Diameter injection area: 10.6 cm; Length

  injection area: 30 cm; Speed of fuel gas

  in the injection zone: 610 m / s; Oil: g / h; Oil injection pressure: 16 bar; Number of oil tips: 4; Oil nozzle diameter: 1.06 mm; Diameter reaction zone:

34 cm.

  The feed liquid feed (oil) had the following composition: H / C ratio: 91; Hydrogen: 6.89% by weight, 7.00% by weight; Carbon: 91, 1% by weight, 90.8% by weight; Sulfur: 1.1% by weight; API Density:, 6 / 15.6 ° C (15.5 ° C) = 5.0; BMCI (VISC-grav.) = 141 Set II: Preheating: 593 C; Gas: 212 m3 / h; Air: 2265 m3 / h; Air / Gas: 10.6; Primary combustion: 118%; Volume combustion zone: 2.4.104cm3; Diameter injection area: 10.6 cm; Length injection area: 30 cm; Speed of combustion gas in the injection zone: 700 m / s;

  Oil: 136 g / h; Oil injection pressure: -

  18.6 bars; Number of oil tips: 4; Oil nozzle diameter: 1.06 mm; Reaction Zone Diameter: 15.2 cm The feed liquid (oil) feed had the following composition: H / C ratio: 1.06; Hydrogen: 7.99% by weight, 7.99% by weight; Carbon: 89.7% by weight, 89.5% by weight; Sulfur: 0.5% by weight; API Density:, 6 / 15.6 C (15.5 C) = 0.5; BMCI (VISCgrav.) = 123 In both sets I and II, the liquid fuel used in the combustion reaction was natural gas with a methane content of 95.44% and a calorific value of 8232 kcal / m As will be generally understood by those skilled in the art, the process variables given in the Table represent the variable at a point in the reactor and are determined in the generally known manner. Each group of carbon black tests was made in a carbon black reactor similar to the reactor disclosed in Example 1 of

  U.S. Patent No. 3,922,335 to the exceptions noted in the Table.

  In the Table, the first nozzle indicates L-1, the distance between the most downstream point of the injection of the feedstock and the first nozzle. The

  temperature before the first nozzle indicates the temperature

  ture of the effluent before the first nozzle and the temperature

  after the first nozzle and the temperature after the second nozzle refer to the temperature of the effluent after the first nozzle and the mixing temperature of the feedstock and the combustion gases after the second nozzle, respectively. All quenching temperatures are calculated by conventional and well known thermodynamic techniques. The residence time, in the Table, indicates the amount of time after the most downstream point of feedstock injection, which elapsed before

  the temperature of the effluent is initially lowered.

  The second nozzle indicates L-2 that is determined empirically.

  using the extract level in toluene.

  After each run, the carbon blacks produced were collected and analyzed for CTAB, hue, Dst (Stokes mean diameter), CDBP, fluffy DBP, and toluene bleaching. Results for each test

are shown in the table.

  CTAB was determined according to the ASTM D 3765-85 test process. The hue was determined according to the ASTM D3265-85a test process. DBP of the fluffy carbon blacks was determined according to the process given in ASTM D2414-86. CDBP was determined according to the process given in ASTM D 3493-86. The toluene discoloration was determined according to

ASTM N D1618-83 test process.

  Ds5t (Stokes mean diameter) was determined by centrifugal disk photosedimentometry according to the

  description which follows. The following process is a modification

  citation of the process described in the Joyce-Loebl Disc Centrifuge Instruction Manual, Reference DCF4.008, published February 1, 1985, available from the Joyce-Loebl Company, Marquisway, Team Valley, Gateshead, Tyne & Wear, Great Britain), whose teachings are incorporated-: title of reference. The process is as follows. 10 mg of a sample of carbon black are weighed into a weighing vessel and then added to 50 cc of a solution of 10% absolute ethanol, 90% distilled water which is made 0.05% in the surfactant NONIDET P-

  (NONIDET P-40 is a registered trademark for a surfactant

  active manufactured and sold by Shell Chemical Co.). The suspension is dispersed by ultrasonic energy for 15 minutes using the Model W 385 apparatus manufactured and sold by Heat System Ultrasonics Inc., - Farmingdale, New York. Prior to the disc centrifuge test, the following data are entered into the computer that records the disc centrifuge data: 1. The density of the carbon black, taken as 1.86 g / cc; 2. The volume of the solution of carbon black dispersed in a solution of water and ethanol, which in this case is 0.5 cc; 3. The volume of the centrifuged fluid which in this case is 10 cc of water; 4. The viscosity of the centrifuged fluid, which in this case is taken to be 0.933 centipoise at 23 C; 5. The density of the centrifuged fluid which in this case is 0.9975 g / cc at 23 C; 6. The speed of the disk, which in this case is 8,000 rpm; 7.The sampling interval of data which,

in this case, is 1 second.

  The disc centrifuge operates at 8,000 rpm while the strobe works. 10 cc of distilled water is injected into the disc as a centrifuged fluid. The turbidity level is set to O; and i cc of the solution of% absolute ethanol and 90% distilled water is injected as a buffer liquid. The cutting and accelerating knobs of the disk centrifuge are then manipulated to produce a regular concentration gradient between the centrifuged fluid and the buffer liquid and the gradient is monitored visually. When the gradient becomes regular and there is no distinctive limit between the two fluids, 0.5 cc of carbon black dispersed in the aqueous ethanol solution is injected into the spinning disc and collection of data. If a current occurs, the test is stopped. The disc rotates for 20 minutes - following the injection of the carbon black dispersed in the aqueous ethanol solution. After 20 minutes of centrifugation, the disc is stopped, the temperature of the centrifuged fluid is measured and the mean of the temperature of the centrifuged fluid measured at the beginning of the test and the temperature of the centrifuged fluid measured at the end of the test. The test is entered into the computer which records the data of the disc centrifuge. The data are analyzed according to the standard Stokes equation and are presented using the following definitions: Carbon Black Aggregate: distinct rigid colloidal entity which is the smallest dispersible unit; it is largely composed of fused particles; Stokes diameter: the diameter of a sphere that

  sediment in a viscous environment in a field -

  centrifugal or gravitation according to the Stokes equation.

  A non-spherical object, such as a carbon black aggregate, can also be represented in terms of the Stokes diameter if it is considered to behave as a rigid and smooth sphere of the same density and sedimentation rate as the object. The units

  are expressed in diameters in nm.

  Stokes mean diameter (Dst): the point of the Stokes diameter distribution curve o 50% in

  sample weight is either bigger or smaller.

  This therefore represents the average value of the determination. As shown in the Table, the present invention allowed the production of carbon blacks having increased values of CDBP, fluffy DBP and Dst and decreased hues in comparison with the carbon blacks produced by the control carbon black process tests. and 4 using a single nozzle. This indicates that the carbon blacks of the present invention are characterized by aggregate size and

  increased structure. By the way, as shown -

  by the results for Ensemble II, the present invention enabled the production of carbon blacks having increased values of CDBP, fluffy DBP and Dst and decreased hues for a relatively constant CTAB value. This indicates that the present invention provides carbon blacks having increased size and aggregate structure for a given value.

from CTAB.

  As shown by the results for Set I, the present invention provides carbon blacks having increased values of CDBP, fluffy DBP and Dst and decreased hues in comparison to the carbon blacks produced by the process test. control carbon black N0 1 at different residence times at which the temperature of the effluent is initially lowered by the same amount. It is understood that DBP means dibutyl phthalate, and CDBP, dibutyl phthalate ground, giving

an absorption index.

R E V E N D I CATIONS

  1. A method for controlling the size of the aggregates and the structure of carbon blacks, characterized in that it comprises passing a stream of hot combustion gases through a reactor; injecting a feedstock into the stream of hot combustion gases at one or more points to form an effluent and start pyrolysis of the feedstock in the effluent; lowering the temperature of the effluent to a first point within a time period of 0.002 seconds downstream of the most downstream point of feedstock injection, without stopping the pyrolysis of the feedstock

in the effluent.

  2. A process according to claim 1, characterized in that the temperature of the effluent is lowered by one

  amount up to about 444 C.

  3. A process according to claim 1, characterized in that the temperature of the effluent is lowered by one

  amount between about 28 and about 444 C.

  4. A process according to claim 1, characterized in that the temperature of the effluent is lowered in a period of time between about 0.0 and about

  0., 0015 seconds from the most downstream point of the injection

tion of the feedstock.

  5. A process according to claim 3, characterized in that the temperature of the effluent is lowered in a period of time between about 0.0 and about 0.0015 seconds from the most downstream point of

  injection of the feedstock.

  6. A process according to claim 1, characterized in that the temperature of the effluent is lowered by

injection of a quenching fluid.

  7. A process according to claim 6, characterized in that the temperature of the effluent is lowered to a time period of between about 0.0 and about 0.0015 seconds from the most downstream point of the injection. of the feedstock. 8. A process according to claim 6, characterized in that the quenching fluid lowers the temperature of

the effluent up to about 444 C.

  9. A process according to claim 6, characterized in that the quenching fluid lowers the temperature of

  the effluent between about 28 and about 444 C.

  10. A process according to claim 7, characterized in that the quenching fluid lowers the temperature of

  the effluent between about 28 and about 444 C.

  11. A process for producing carbon blacks having a size controlled aggregates and structure, characterized in that it comprises: passing a stream of hot combustion gases through a reactor; injecting a feedstock into the stream of hot combustion gases at one or more points to form an effluent and start pyrolysis of the feedstock in the effluent; lowering the temperature of the effluent to a first point within a period of 0.002 seconds downstream of the most downstream point of feedstock injection, without stopping pyrolysis of the feedstock in the feedstock. 'effluent; further lowering the temperature of the effluent to a second point, downstream of the first point, to stop the pyrolysis of the feedstock in the effluent; and

  separate and collect the carbon black produced.

  12. A process according to claim 11, characterized in that the temperature of the effluent is lowered by one

  amount up to about 444 C.

  13. A process according to claim 11, characterized in that the temperature of the effluent is lowered by one

  amount between about 28 and about 444 C.

  14. A process according to claim 11, characterized in that the temperature of the effluent is lowered in a period of time between about 0.0 and about 0.0015 seconds from the most downstream point.

  injection of the feedstock.

  15. A process according to claim 13, characterized in that the temperature of the effluent is lowered in a period of time between about 0.0 and about 0.0015 seconds from the most downstream point.

  injection of the feedstock.

  16. A process according to claim 11, characterized in that the temperature of the effluent is lowered by

injection of a quenching fluid.

  17. A process according to claim 16, characterized in that the temperature of the effluent is lowered in a period of time from about 0.0 to about 0.0015 seconds from the most downstream point.

  injection of the feedstock.

  18. A process according to claim 16, characterized in that the quenching fluid lowers the temperature of

the effluent up to about 444 C.

  19. Process according to any of

  16 or 17, characterized in that the fluid

  quenching decreases the temperature of the effluent between

about 28 and about 444 C.