JP2003147225A - Method and apparatus for producing carbon black - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing carbon black, by which, in a heat exchanger for effectively recovering quantity of heat formed in a carbon black production process and heating air, a carbon layer precipitated and deposited on inner walls of a plurality of tube spaces through which high- temperature gas containing carbon black is passed can be reduced, and an apparatus therefor. SOLUTION: In this method for producing oil furnace carbon black by reaction between a hydrocarbon fuel and oxygen-containing gas, the method for producing carbon black comprises causing pressure change in a heat exchange system by providing a heat exchange process for subjecting the oxygen- containing gas to be used in a combustion gas flow formation process to heat exchange with a carbon black-containing gas flow discharged from a reaction termination process between the reaction termination process and a separation process and a process for introducing water to the carbon black-containing gas flow just before the heat exchange process. The apparatus therefor is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon black manufacturing method and a carbon black manufacturing apparatus, and more particularly to maintaining heating efficiency in a process of heating an oxygen-containing gas introduced into a furnace in a carbon black manufacturing process. And a manufacturing apparatus having means for satisfying the above.

[0002]

BACKGROUND OF THE INVENTION Carbon black is used as an industrial raw material, for example, as a rubber reinforcing agent in the tire manufacturing industry, automobile rubber product manufacturing industry, various paints, ink manufacturing industry, electrostatic toner manufacturing industry, etc. that take advantage of the characteristic of black. It is one of the important industrial products used widely.

Carbon black is obtained by thermally decomposing or incompletely combusting a hydrocarbon raw material, and most of it is produced by a furnace method by thermal decomposition in a reaction furnace (furnace) kept at a high temperature. The carbon black manufacturing process by the furnace method is performed according to the following flow.

As shown in FIG. 1, the hydrocarbon fuel from the inlet 22 and the oxygen-containing gas (usually air) from the inlet 22 of the front of the carbon black reactor 21, which is entirely covered with refractory. A high temperature combustion gas generation zone 24 by the combustion of a mixture of the following, a reaction zone 26 for introducing the feed oil 25 into the high temperature combustion gas flow in the middle to generate carbon black, and a cooling medium (usually water) on the downstream side thereof. A high temperature flow containing carbon black is generated in the reaction furnace 21 which is composed of the stop zone 28 in which the reaction is rapidly stopped by the cooling medium introduced through the introduction part 27.

The formation reaction of carbon black is 1500 to
It is carried out in a very high temperature atmosphere of 1800 ° C, and when the temperature of the components (excluding the cooling medium) introduced into the furnace is low, it causes a decrease in the ambient temperature, so it is heated in advance before it is introduced into the furnace. Since it has an advantageous effect on the production reaction, it is usually preheated and introduced.

The hot stream discharged from the reactor (typically 8
(Having a temperature of 00 to 850 ° C.) passes through the space of the heat exchanger in which a large number of tubular objects are installed, while the oxygen-containing gas (air) for maintaining the combustion of the hydrocarbon fuel is
The air introduced by the blower from the introduction part 30 in the upper part of the heat exchanger 29 and heated by the contact with the outer surface of the pipe through which the high-temperature flow flows is taken out from the lower part of the exchanger 29 and introduced into the heated air introduction part 23. It is introduced into the reaction furnace.

The indirectly cooled carbon black-containing gas stream passing through the tubes of the heat exchanger 29 is successively separated into a solid (carbon black) and a gas body 3
1 is introduced and carbon black is separated. The separated carbon black is provided to the user in a powdery state or through a granulating step depending on the application.

As the temperature of the air introduced into the furnace from the introduction section 23 after passing through the heat exchanger 29 becomes higher, the higher the temperature is, the more advantageous the reaction is for the carbon black production reaction. The temperature at the time of supplying the carbon black-containing gas stream to the exchanger 29 tends to be higher.

However, if the temperature of the air introduced into the furnace is increased by increasing the temperature of the inlet to the exchanger 29 to about 900 ° C. as the temperature of the gas flow increases, the carbon black-containing gas flow is divided into a plurality of tubes. By the carbonization reaction of undecomposed hydrocarbons present in a small amount in the carbon black adhering to the inner wall when passing through the inside, or the carbon deposition reaction by the decomposition reaction from carbon oxides (CO, CO ₂ ) contained in the gas flow. A carbonized carbon layer is formed in the tube.
The carbonized carbon layer acts as a heat insulating material as the deposition progresses, which lowers the efficiency of heat exchange and, in extreme cases, causes the tube to be blocked.
This tendency becomes more remarkable especially when the carbon black contains a large amount of undecomposed tar. Further, when the carbon deposit layer is desorbed from the inner wall surface of the tube and mixed in the product, it acts as a foreign substance (coke) that does not exhibit the characteristics as carbon black as described above, which causes a deterioration in quality.

It is considered that the following chemical reactions are mainly involved in the carbon black formation reaction and the generation of the carbon deposit layer on the tube surface of the heat exchanger 29. CmHn → mC + 1 / 2nH ₂ (carbon black forming reaction) CH ₄ + H ₂ O ⇔ CO + 3H ₂ (hydrogenolysis) 2CO ⇔ CO ₂ + C (carbon deposition reaction) CO + H ₂ ⇔ H ₂ O + C (carbon deposition reaction) The above chemical reaction In the equations, the latter two equations are related to the generation and growth of the carbon deposit layer and both are reversible reactions, but the reaction rate to the right side where the carbon deposit layer occurs is higher when the atmospheric temperature is higher. Become. That is, it means that carbon is more likely to be precipitated and deposited in the tube.

As the prior arts for solving the above-mentioned problems, the following three types are roughly disclosed. (1) The temperature of the gas flow supplied to the heat exchanger 29 is kept low to control the generation of a carbonized carbon layer in the tube, and the preheated air that has passed through this heat exchanger is passed through different heat generation sources. (Japanese Patent Publication No. 2-385, Japanese Patent Laid-Open No. 11-293141, etc.). (2) An antifouling agent that reduces the formation of a carbon layer on the inner wall surface is added to the carbon black-containing gas flow before it is introduced into the heat exchanger 29 (JP-A-5-222378 and JP-2944882). Such). (3) Carbon deposits are reduced by annealing the inner wall of the tube of the heat exchanger (Table 1-51-468).
No. 1 publication).

The above-mentioned method for reducing carbon deposits has the following drawbacks. In (1), since a heat source generator completely different from the carbon black production line or a burner section attached to these is required, an increase in equipment cost cannot be avoided. In the case of (2), it is necessary to add the third component for preventing adhesion to the raw material hydrocarbon, and accordingly, the installation of the third component introduction line and the introduction of the additional component increase the cost. In (3), it is impossible to avoid an increase in cost for annealing the inner wall of the pipe.

In addition, if the carbon layer adheres / deposits in the pipe to lower the heat exchange efficiency or if a pressure loss occurs due to internal clogging, the production activity is temporarily stopped to remove the carbon layer adhered / deposited. Generally, high-pressure water is sprayed on the inner wall surface to be stripped off, or steam and / or air is introduced to decompose and burn off. However, since the number of tubes installed inside is large and this work takes a lot of time, there is an extremely large loss of manufacturing time due to the removal of this carbon layer, including interruption (the tube cooling time is also It usually takes a few days including). Further, this removal work is required once every two weeks to several months, although it depends on the production conditions of carbon black, that is, the adhesion state inside.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to pass a high temperature gas containing carbon black in a heat exchange device for effectively recovering the amount of heat generated in the carbon black manufacturing process to heat air. It is intended to provide a manufacturing method and a manufacturing apparatus capable of reducing the carbon layer deposited / deposited on the inner walls of a plurality of tube spaces in a heat exchanger.

Another object of the present invention is to delay the generation of a carbon layer which grows to a predetermined thickness according to the inventions of claims 1 to 3, that is, to such a thickness that heat exchange efficiency decreases. Although it can be done, it cannot be completely eliminated. Therefore, the carbon layer produced little by little by continuous use of the heat exchanger 29 for a long period of time can be changed by a short time condition change of the heat exchanger 29 without completely stopping the manufacturing process. It is intended to provide a carbon layer removal method capable of recovering performance.

[0016]

A first aspect of the present invention is to provide a combustion gas flow generating step for generating a combustion gas flow by a reaction of a hydrocarbon fuel and an oxygen-containing gas, and a carbonaceous feedstock in the combustion gas flow. A carbon black generation step of spraying and introducing carbon black by thermal decomposition or incomplete combustion of the feedstock, and a reaction of stopping the reaction by introducing a cooling medium into the carbon black-containing reaction gas stream generated above. In the method for producing an oil / furnace carbon black comprising a stopping step and a separation step of collecting and separating a solid content (carbon black) from the cooled carbon black-containing gas stream, between the reaction stopping step and the separation step. The oxygen-containing gas used in the combustion gas flow generation step, between the carbon black-containing gas stream from the reaction termination step A carbon black characterized by generating a pressure change in the heat exchange system by providing a heat exchange step for exchanging and a step of introducing water into the carbon black-containing gas stream immediately before the heat exchange step. Manufacturing method. The second aspect of the present invention is
(A) A combustion gas generating part having a fuel hydrocarbon introducing pipe and an oxygen-containing gas introducing pipe, a carbon black reaction producing part having a raw hydrocarbon introducing pipe, and a reaction stopping part having a cooling water introducing pipe A carbon black reaction furnace composed of refractory, (B) a plurality of tubular objects having an inlet opening and an outlet opening are arranged in the downstream side of the reaction stop portion, and the upper plate and the lower plate other than the openings are arranged. And a water introducing means provided below the lower plate of the heat exchanging means, and a cylindrical heat exchanging means having an inlet and an outlet for the oxygen-containing gas. The present invention relates to a carbon black manufacturing apparatus. A third aspect of the present invention is the ratio (L) of the diameter (R) of the lower plate in the heat exchanging means to the distance (L) between the lower plate of the heat exchanging means and the water introducing portion of the water introducing means.
/ R) is 0.2 to 1.0. A fourth aspect of the present invention is to stop the introduction of the carbonaceous feedstock oil into the reaction furnace, and directly introduce the combustion gas flow generated by the reaction of the hydrocarbon fuel and the oxygen-containing gas into the pipe of the heat exchange step, The present invention relates to a method for removing carbonaceous deposits adhering to the inside of a heat exchange system pipe, which is characterized by burning and removing carbonaceous deposits therein.

That is, in the process gas after the carbon black generation reaction, the higher the temperature is, the higher the reaction rate of carbon deposition / deposition becomes, and it is predicted that the carbonaceous material adheres and grows in the plurality of tubes of the heat exchanger 29. However, in order to avoid this, a cooling medium, for example, water is introduced from the upstream side (reactor side) of the lower plate of the heat exchanger 29, and this water is instantaneously and explosively vaporized in a high temperature atmosphere. A carbon black manufacturing process and a manufacturing apparatus capable of eliminating a carbon layer formed by being deposited / deposited on the surface of the inside of a tube due to a pressure change when expanding to a carbon black, and preventing growth into a layer.
In addition, the present invention relates to a process capable of shortening the suspension period of the production activity when the carbon layer is formed.

It is one of the requirements of the present invention that the water introducing means is provided in the space before the introduction of the carbon black-containing gas stream from the reaction stopping step into the heat exchange multiple tube space.
However, it is more preferable to introduce water without spraying it. This is because if the water particles are too small, the pressure when evaporating explosively becomes weak. Further, as the water introducing means, it is upstream of the bottom surface which is the inlet surface of the plurality of tubular objects, but if this distance is too long, the pressure at the time of water evaporation introduced does not reach the desired pressure,
If the effect is not exhibited, and conversely it is too close, the entire system cannot be affected. Therefore, the distance (L) from the bottom surface to the water introduction portion and the diameter (R) of the lower plate in the heat exchanger 29 (R). )
It is preferable to install the water introduction site at a position where the ratio (L / R) of the water is 0.2 to 1.0. Further, the direction of the water inlet is preferably opposite to the flow direction of the high temperature process gas flow.

In the present invention, as described above, by introducing water from a specific position before the carbon black-containing gas stream from the reaction stopping step is introduced into the heat exchanger 29, a plurality of tubes of the heat exchanger 29 are introduced. The present invention provides a carbon black production process including a process for eliminating the formation of a carbon layer that adheres and accumulates on the inside of a water and a carbon black production device including a water introduction device for carrying out the process. The carbon layer adheres to the inside of the tube of the heat exchanger 29 due to the rapid pressure change caused by the instantaneous and explosive evaporation at the time of introduction.
The deposition can be delayed much more than before, but it is difficult to eliminate it at all. This is why the invention of claim 4 exists.

Adhesion of carbon layers in the tubes of the heat exchanger 29
When the deposition proceeds, the heat exchange efficiency decreases, but the degree can be easily determined because the difference between the inlet temperature and the outlet temperature of the heat exchanger 29 decreases (or the air preheating temperature decreases).

Conventionally, when a carbon layer adheres to and deposits on the insides of a plurality of tubes of the heat exchanger 29 and the carbon layers serve as a heat insulating material and the heat exchange efficiency decreases, the inner wall surface of the tubes is cleaned by the following method. Was being made. 1. Discontinue the introduction of fuel and feedstock into the reactor. 2. The heat exchanger 29 is left to stand until its temperature drops. 3. A high-pressure (usually 5 to 6 MPa) water spraying device is inserted into a plurality of tubes installed in the heat exchanger 29 to wash the inner adhering / depositing layer. 4. The reaction furnace is heated little by little to reach a specified temperature (usually 120
When the temperature reaches 0 to 1500 ° C., the feedstock oil is introduced to shift to the carbon black production process. When the heat exchange efficiency of the heat exchanger 29 is restored by such means, it takes 4 to 5 days from the stop to the cooling, the washing and the heating, and the return (the start of the feedstock oil introduction), and this period is complete. Since the production activity is stopped, the loss during that period is very large.

The process of the present invention for eliminating this, that is, the time for interrupting the production of carbon black as much as possible, that is, the method for removing the deposited and deposited carbon layer in the tube, is carried out as follows. (B) Stop introducing raw material oil into the reactor. (B) The combustion gas generated by the fuel hydrocarbon and the oxygen-containing gas (air) is introduced into the heat exchanger 29. At this time,
Due to the small amount of oxygen remaining in the combustion gas, the carbonaceous deposit inside the tube of the heat exchanger 29 is burned, and the deposited and deposited carbon layer is removed. After that, the introduction of fuel and air into the reaction chamber is usually stopped as a precaution, left for a while, and then the production of carbon black is restarted. The operations (a) and (b) are carried out in order to prevent the temperature inside the pipe of the heat exchanger 29 and the temperature of the heated air from damaging the inside of the device, especially the bottom surface and the inside of a plurality of pipes due to overheating of the temperature. Need to be carefully controlled.

Further, according to the removal method by such a process, at a predetermined inlet gas temperature of the heat exchanger 29, the air temperature after passing through the heat exchanger 29 has a predetermined value because the heat exchange efficiency is lowered. It is preferable to carry out the treatment when the temperature falls below the temperature.

[0024]

EXAMPLES Next, the present invention will be described in more detail by showing Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 [Comparison of Presence or Absence of Water Introduction by Heat Exchange Means] Production 11-12 apparatus shown in FIGS. 4, 5, 6 and 7 (for details, refer to Japanese Patent No. 2933117 and drawings). Was used to produce ISAF carbon black.
The dimensions of each component of this manufacturing apparatus were as follows. Flammable fluid introduction chamber 2 Inner diameter 450 mmφ Length 400 mm Oxygen-containing gas introduction pipe 3 Long side 400 mm Short side 100 mm Oxygen-containing gas introduction cylinder 4 Inner diameter 250 mmφ Length 300 mm Convergence chamber 8 Upstream end inner diameter 370 mmφ Downstream end inner diameter 80 mmφ Length 1600 mm Angle 5.3 ° Fuel Oil Introducing Device Inner Diameter of Fuel Oil Introducing Pipe 72 7 mmφ Inner Diameter of High Pressure Air Introducing Pipe 73 13 mmφ Air Pressure 0.3 MPa Inner Diameter of Low Pressure / Low Temperature Air Introducing Pipe 74 22 mmφ Air Pressure 0.05 MPa Reaction Chamber 12 Inner Diameter 140 mmφ

In addition, the reaction is continued and a in the rapid cooling chamber 13
As the cooling water spraying devices of to h, the one having the same structure as that disclosed in Japanese Utility Model Laid-Open No. 58-140147 (Applicant: Asahi Carbon Co., Ltd.) was attached. As the raw material oil and the fuel oil, those having the properties and compositions shown in Table 1 were used.

[0027]

[Table 1]

The carbon black production conditions were as shown in Table 2 to produce ISAF grade carbon black. At the same time, the physicochemical properties of carbon black at this time were also shown.

[0029]

[Table 2]

The operating conditions of the heat exchanger 29 are as follows. Total amount of wet gas introduced into the heat exchanger 8350 Nm ³ / hr Heat exchanger inlet gas temperature 880 ° C Heat exchanger outlet gas temperature 560 ° C Heat exchanger inlet air temperature 70 ° C Heat exchanger outlet air temperature 750 ° C Number of tubes (pipes) 84 Main tube length 14 m Tube diameter inside heat exchanger 8 cm Water introduction means: Water introduction at the center of a tubular body made by extending the outer frame of the heat exchanger downward from the lower end, as shown in FIG. Means were provided. The position of the water introducing means was set at a position 0.6 times the diameter of the heat exchanger cylinder (indicated by L in FIG. 2) measured from the lower plate constituting the lower end portion of the heat exchanger. The amount of water introduced was 400 l / hr, and the water introduction pressure was 0.3 MPa.

Carbon black was produced under the above conditions, and the difference in the presence or absence of water introduced from the downstream side of the inlet of the heat exchanger 29 was that the outlet air temperature at the heat exchanger 29 was 72.
The period until reaching 0 ° C. was measured. The fact that the difference between the inlet temperature and the outlet temperature of the heat exchanger is not small indicates that the carbon layer was formed in the pipe (tube) in the heat exchanger with a considerable thickness, and the heat exchange efficiency decreased. And
In this test, when the outlet air temperature reached 720 ° C, it was judged that the heat exchanger was at the limit of use. The results were as follows (see FIG. 3).

Comparative Example 1: No water introduction for 30 days (shown by the broken line in FIG. 3) Example 1: Water introduction for 65 days (shown by the solid line in FIG. 3) Thus, the carbon black inclusion in the heat exchanger 29 By introducing water prior to the introduction of the reaction gas, the carbon layer that adheres and deposits is less likely to be formed on the tube surface due to the explosive evaporation of water, and high heat exchange efficiency can be maintained for a long time that is more than twice that of the conventional method. it is obvious.

[Removal of Body Stack on Inner Wall of Heat Exchanger] In the above-mentioned manufacturing operation, the outlet air temperature in the heat exchanger 29 was lowered to 720 ° C. in 65 days, and the heat exchange efficiency was lowered. The carbon layer removal operation as described above was performed. First, the introduction of the feedstock oil into the reactor was interrupted. On the other hand, the combustion gas generated by the reaction between the hydrocarbon fuel and the oxygen-containing gas is
The reaction zone 26 and the stop zone 28 (the cooling medium is introduced) of the reaction furnace are directly passed through the heat exchanger into the heat exchanger composed of the "heat exchange area and the heat exchanger extension area including the water introduction device" shown in FIG. be introduced. Since oxygen remains in this combustion gas, the carbon layer adhering to and depositing on the inner surface of the tube in the heat exchanger is burned and removed. This processing operation was completed in only 3 hours. Then, the introduction of the hydrocarbon fuel and the oxygen-containing gas was stopped, and after 2 hours, the production of carbon black was restarted. Therefore, the time during which the production of carbon black was stopped was only 5 hours. On the other hand, when the production is stopped as in the conventional case and the tubes in the heat exchanger 29 are washed by spraying high-pressure water after cooling the reaction furnace, the production is started from the discontinuation (heating the cooled reaction furnace). It took 5 days until the temperature in the reaction furnace rises to the condition that the raw material oil can be introduced.

The production was stopped as in the conventional case, in which the delay of the carbon deposit layer accumulation due to the occurrence of the pressure change in the introduction of water into the extension region of the heat exchanger according to the present invention and the carbon layer removal operation were combined and the production was stopped as before. Comparing with the case where the pipe in the heat exchanger 29 is cleaned by spraying high-pressure water after cooling, the difference in operating time of the carbon black manufacturing apparatus is roughly as follows. Therefore, in the past, 1/7 (14.3%) [5 / (3
0 + 5) × 100%] time was incapable of manufacturing due to the removal of the carbon layer in the tube, whereas the present invention was only 0.3% [5 / (65 × 24 + 5) × 100%]. The downtime is eliminated, and the advantage of improving the operating ratio is very large.

[0035]

(1) The tube (piping) in the heat exchanger is produced by the method and apparatus for producing carbon black of the present invention.
Since the formation of the carbon layer deposited and deposited inside could be significantly delayed, the overall manufacturing efficiency could be significantly improved. (2) According to the carbon layer removing method of the present invention, the time required to stop the production of carbon black is significantly shortened as compared with the conventional removing methods.

[Brief description of drawings]

FIG. 1 shows a flow sheet of a schematic manufacturing process of carbon black.

FIG. 2 is a cross-sectional view showing an example of a heat exchange system which is a main point of the present invention.

FIG. 3 is a graph showing a change in temperature at the outlet of the heat exchanger with respect to the number of elapsed days depending on whether or not water is introduced into the extension area of the heat exchanger.

FIG. 4 is a vertical sectional front view of a reaction furnace used for producing carbon black according to the present invention.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is a partially enlarged view showing the forehead and fuel introducing means of FIG.

7 is a sectional view taken along the line BB of FIG.

[Explanation of symbols]

1 carbon black reactor 2 Flammable fluid introduction chamber 3 Oxygen-containing gas introduction pipe 4 Oxygen-containing gas introduction cylinder 5 current plate 6 space 7 Fuel oil spraying means 8 Convergence room 9 burner tiles 10 Raw oil spray device 11 Raw oil introduction chamber 12 Reaction chamber (reaction zone) 13 Reaction continued and emergency room cold room (stop zone) 21 Reactor 22 Hydrocarbon fuel introduction section 23 Heated air inlet 24 Combustion gas generation zone 25 raw oil 26 Reaction zone 27 Coolant introduction section 28 (Reaction) Stop band 29 heat exchanger 30 Air inlet 31 Separator 51 ring 71 Fuel oil spray tip 72 Fuel oil introduction pipe 73 Oxygen-containing gas introduction pipe 74 Oxygen-containing gas introduction pipe 75 Oxygen-containing gas conduit 76 Gas body conduit a Quenching water injection spray means b Quenching water injection spray means c Quenching water injection spray means d Quenching water injection spray means e Quenching water injection spray means f Quenching water injection spray means g Quenching water injection spray means h Quenching water injection spray means

Claims (4)

[Claims] 1. A combustion gas flow generation step for generating a combustion gas flow by the reaction of a hydrocarbon fuel and an oxygen-containing gas,
A carbon black production step of spraying carbonaceous feedstock into the combustion gas stream to produce carbon black by thermal decomposition or incomplete combustion of the feedstock, and a cooling medium in the carbon black-containing reaction gas stream produced above. In a method for producing an oil / furnace carbon black, which comprises a reaction-stopping step of stopping the reaction by introducing and a separation step of collecting and separating a solid content (carbon black) from the carbon black-containing gas stream after cooling, A heat exchange step is provided between the reaction stop step and the separation step, in which the oxygen-containing gas used in the combustion gas flow generation step is heat-exchanged with the carbon black-containing gas flow exiting from the reaction stop step. Along with the step of introducing water into the carbon black-containing gas stream immediately before the heat exchange step, Carbon black method of manufacturing, characterized by generating a pressure change in the exchange system. 2. (A) Combustion gas generation section equipped with fuel hydrocarbon introduction tube and oxygen-containing gas introduction tube, carbon black reaction production section equipped with raw material hydrocarbon introduction tube, and reaction stop equipped with cooling water introduction tube Part of the carbon black reactor (B), which is entirely made of refractory material, is provided with a plurality of tubular objects having an inlet opening and an outlet opening at the downstream side thereof, and is provided in an upper part except for the openings. And a water introducing means provided below the lower plate of the heat exchanging means, and (C) a cylindrical heat exchanging means which is hermetically sealed by a plate and a lower plate and has an inlet and an outlet for oxygen-containing gas. Characteristic carbon black manufacturing equipment. 3. The ratio (L / R) of the diameter (R) of the lower plate in the heat exchanging means to the distance (L) between the lower plate of the heat exchanging means and the water introducing portion of the water introducing means is 0. .2-
The carbon black production apparatus according to claim 2, wherein the carbon black production rate is 1.0. 4. The introduction of the carbonaceous feedstock oil into the reaction furnace is stopped, and the combustion gas flow generated by the reaction of the hydrocarbon fuel and the oxygen-containing gas is introduced as it is into the pipe of the heat exchange step,
A method for removing carbonaceous deposits adhering to inside a heat exchange system pipe, characterized by burning and removing carbonaceous deposits inside the pipe.