JPH059404A - Preparation of carbon black - Google Patents

Abstract

PURPOSE:To efficiently produce carbon black having a broader aggregate size distribution by operating a furnace in an improved manner. CONSTITUTION:The title process comprises the steps of combustion, feedstock oil injection, reaction, and reaction termination. The feedstock oil injection step is conducted in a throat part which consists of a cooling cell having a double-wall structure made of a metal and having a heat exchange function. Feedstock oil is injected from the circumference into the throat part at the depth corresponding to 10-40% of the diameter of the throat part. The air preheated by heat exchange by the cooling cell can be circulated and used as a combustion supporting gas for fuel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial production method for efficiently obtaining carbon black having a wide distribution of aggregate aggregates required for energy-saving tires.

[0002]

2. Description of the Related Art In recent years, as the performance of automobiles has been improved, carbon black as a tire member has also been required to have strict property requirements. For example, for energy-saving tires, the aggregate aggregate distribution should be as broad as possible. There is a strong demand for the development of carbon black having the changed properties.

Conventionally, as a means for producing carbon black having such a wide aggregate distribution of aggregates, a method in which the raw hydrocarbon oil is introduced in multiple stages in the axial direction of the production furnace has been effective. For example, in U.S. Pat.No. 4071496, a venturi-type carbon black manufacturing furnace is used, and the feed oil is radially divided and introduced from the furnace periphery into the venturi rear expansion part and the outlet wide-diameter cylindrical expansion part in the throat area. It is disclosed to obtain a carbon black having a broad aggregate distribution. British Patent No. 21
No. 51605 describes a method for producing a low-hysteresis carbon black in which the feedstock oil is divided into two stages and introduced into the front converging part and the narrow-diameter throat part of a venturi-type carbon black manufacturing furnace to broaden the aggregate aggregate distribution. It is shown. Further, in Japanese Patent Laid-Open No. 3-137167, the feedstock oil is divided into two stages and introduced into a tapered portion of a tapered furnace, and the jet angle at which the second stage feedstock oil is introduced into the furnace is restricted to a specific range. A manufacturing technique developed by the applicant of the present invention is disclosed, whereby a carbon black having a broad aggregated aggregate distribution is obtained.

In all of these prior arts, the common element is to introduce raw material oil in a divided manner so as to have a temperature distribution in each injection area. However, a large number of raw material oil injection nozzles (double cylinders) required for the divided introduction are used. Installing a water-cooling system causes a local cooling phenomenon on the brick wall of the furnace wall in the high temperature furnace near the nozzle position, and the flow of the combustion gas generated in the furnace head combustion region is disturbed, so that the operation surface Encourage the occurrence of coking, which is a difficulty in

Further, the conventional carbon black manufacturing furnace is
The inner wall of the furnace is constructed of refractory bricks, but this lined refractory material is made of alumina-based (high-alumina or ultra-high-alumina) bricks with a refractory temperature of about 1900 ° C even at the highest temperature site. When it is brought into contact with a combustion gas flow exceeding 2000 ° C, phenomena such as melting loss occur and the furnace cannot operate. For this reason, measures have been taken to protect the lining refractory material by methods such as forced cooling of the furnace body,
For example, the body of the carbon black manufacturing furnace is made of steel
A process in which a tubular structure is used, bricks are lined in the inner tubular portion, air is introduced into the double tubular gap to cool the furnace, and preheated air is circulated and used as combustion air (US Patent No. 30
No. 87796), a process of placing a steel coil in the lining brick of a taper type carbon black manufacturing furnace and feeding cooling water into the coil (US Pat.No. 4619812) has been proposed. .

The above method of forcibly cooling the furnace body can effectively prolong the life of the refractory lining material,
As for the furnace structure, there is a limit to the high temperature level of the combustion gas due to the fact that alumina-based refractory bricks are lined inside the furnace body. In addition, in the case of a brick-built furnace body, the phenomenon that splinters of bricks peel off during operation (spalling damage) is unavoidable, and this is a cause of product defects due to being mixed in the carbon black produced as grit. Become.

[0007]

The present invention is different from the conventional furnace structure in that the narrow-diameter throat portion forming the feed oil injection area is formed into a metal forced cooling double cylinder structure which does not use a lining refractory material. By using the designed furnace and setting the conditions for injecting the feedstock oil to the specified depth of the narrow throat, it is possible to produce carbon black with broad aggregate aggregate distribution with excellent operability. It was done.

[0008] Therefore, an object of the present invention is to provide a method for producing carbon black having a wide distribution of aggregate aggregates required for energy-saving tires with high productivity.

[0009]

The method for producing carbon black according to the present invention for achieving the above object comprises a combustion step of combusting a fuel to generate a high temperature combustion gas, and a high temperature combustion gas flow in a narrow throat section. In a process comprising a feed oil introduction step of injecting a feed hydrocarbon into the, a reaction step of converting the feed hydrocarbon into carbon black by a pyrolysis reaction, and a reaction stopping step of quenching the reaction gas to terminate the pyrolysis reaction, the feed material The narrow throat part that forms the oil introduction process is composed of a cooling cell with a metal double-cylinder structure that has a heat exchange function, and the raw material oil is surrounded by a depth position corresponding to 10 to 40% of the diameter of the narrow throat part. The structural feature is to inject from.

The combustion process, the feedstock oil introduction process, the reaction process and the reaction termination process, which are the prerequisite processes of the present invention, are not different from those of the prior art, but the first constitutional requirement of the present invention is that the raw material in the above process is used. The point is to use a furnace in which the narrow-diameter throat portion in the oil introduction step is configured as a cooling cell having a metal double-cylinder structure having a heat exchange function. This requirement is to form a wide temperature distribution in the axial direction and cross-sectional direction of the site by forcibly cooling the narrow-diameter throat part into which the feedstock is introduced directly from the surroundings, and to generate the aggregate aggregate distribution of the generated carbon black. It is for broadening. The cooling cell is formed of a metal material such as stainless steel, copper, or Inconel in a jacket shape having a cooling medium inlet pipe and a cooling medium discharge pipe. Its specifications are such that a refrigerant such as air can be efficiently heat-exchanged. It is designed appropriately in consideration of the flow velocity in the pipe. At this time, in order to prevent local heating in the cell, it is preferable to design the shape as dead space as possible.

Air or oxygen-enriched air is used as the cooling medium. In this case, in order to increase the combustion efficiency, it is preferable to circulate and use these media, which are fed into the cooling cell and heated by the heat exchange function, as the combustion supporting gas of the fuel.
In terms of equipment, it is sufficient to install a circulation path from the cooling medium discharge pipe to the fuel supply system.

The second constituent feature of the present invention is to inject the raw material oil from the periphery into a depth position corresponding to 10 to 40% of the diameter of the narrow throat portion. This condition is to ensure that the distribution of aggregate aggregates in the carbon black produced is broadened by introducing the feedstock above the temperature at which pyrolysis starts and with a large temperature gradient. If it is less than 10% of the throat diameter near the cell inner wall, the pyrolysis reaction does not proceed smoothly and the amount of unburned hydrocarbons and grit increases, and sometimes a large amount of coke adheres to the cell inner wall to block the pipe. Cause operational problems. On the other hand, when the feedstock oil is injected into the central portion where the diameter exceeds 40% of the diameter of the narrow throat portion, the temperature distribution in the cross-sectional direction due to the forced cooling cell is not utilized, and the aggregate aggregate distribution of the produced carbon black does not become broad.

[0013]

In the raw material introduction zone in which the narrow-diameter throat portion of the present invention is constituted by the cooling cell having the metal double-cylinder structure having the heat exchange function, the forced cooling action causes a temperature difference at the interface between the combustion gas flow and the cell inner surface. Based on the formation of a boundary film, without extremely lowering the temperature of the combustion gas blown through the central part of the furnace cross section,
Further, the high temperature combustion gas flow flows down without damaging the constituent metal material of the cooling cell. At this time, since the cooling cell can control the temperature distribution in the axial direction and the cross-sectional direction in the furnace depending on the air cooling conditions, it is not necessary to divide and introduce the feedstock in multiple stages as in the prior art, and thus the aggregate temperature can be increased to the pyrolysis temperature. It is possible to form a distribution width for broadening the distribution.

In addition to the above requirements, the narrow throat diameter
Stable carbon black with broad aggregate aggregate distribution by injecting the feedstock oil from the periphery to a depth position equivalent to 10 to 40%, that is, a region with a large temperature gradient in which sufficient high temperature combustion gas flows. And it becomes possible to generate efficiently.

Further, when air or oxygen-enriched air is used as a cooling medium flowing in the cooling cell, and the medium preheated by its heat exchange action is circulated and used as a combustion-supporting gas, promotion of combustion of fuel and high temperature Function effectively.

[0016]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples.

Examples 1 to 4 and Comparative Examples 1 to 3 Inner diameter 400 mm (taper outlet diameter 60 m) lined with alumina refractory bricks equipped with combustion burners in the furnace axial direction on the furnace head.
m), 500 mm long, 200 mm thick fireproof insulation layer, and a raw material consisting of a stainless steel double-tube cooling cell with an inner diameter of 60 mm, an outer diameter of 80 mm, and a narrow throat of 200 mm in length. Introduction area, inner diameter 100mm lined with alumina / silica refractory bricks, length 600mm, fireproof heat insulation layer thickness 100mm
And a reaction stop zone of 100 mm in inner diameter and 1000 mm in length, which was lined with alumina / silica refractory bricks and equipped with a quenching device, were installed in a carbon black production furnace. The stock oil injection nozzle was mounted from around the narrow throat, and the injection position of the nozzle tip was set so that it could expand and contract inside the cell. In addition, the exhaust pipe of the cooling cell was connected to the combustion chamber, and the cooling medium preheated was designed as a circulation path in which the entire amount is consumed as combustion-supporting gas.

Propane was used as the fuel and was supplied from the combustion burner, and air was used as the cooling medium of the cooling cell. The feedstock oil was atomized and injected radially into the combustion gas stream together with the atomizing nitrogen gas. The quench for stopping the reaction was set at a position 900 mm downstream from the entrance of the reaction stopping zone. As feedstock, specific gravity (15/4 ℃) 1.046, toluene insoluble content 0.14%, correlation coefficient (BMCI) 134, sulfur content 0.1%, initial boiling point 195 ℃, Na
An aromatic hydrocarbon oil having 3.0 ppm ion and 0.3 ppm K ion was used.

Carbon black was produced using the above production furnace under different generation conditions. In Comparative Example 3, the raw material introduction area lined with an alumina refractory brick of conventional structure (inner diameter 60 m
It is an example manufactured in a manufacturing furnace having m, length 200 mm). Table 1 shows the production conditions of each example, and Table 2 shows the characteristics of the obtained carbon black.

[0020]

[Table 1]

[0021]

[Table 2]

From the results shown in Table 1, all of the carbon blacks obtained in Examples 1 to 4 satisfying the requirements of the present invention have a larger ΔDst, which is an index of aggregate aggregate distribution, than Comparative Example 3 of the conventional method. It has suitable properties for energy-saving tires. In addition, since no refractory heat insulating material is used in the raw material injecting area, no grit is generated and smooth continuous operation is possible. However, the feed oil injection position was less than 10% of the diameter of the narrow throat portion. In Comparative Example 1, the pyrolysis reaction did not proceed smoothly, and thus the produced carbon black contained a large amount of coke-like grit and also the furnace wall. Coke adhesion was confirmed. Further, in Comparative Example 2 in which the raw material injection position was more than 40% of the diameter of the narrow throat, it was not possible to produce a carbon black having a wide aggregate aggregate distribution.

[0023]

As described above, according to the method for producing carbon black according to the present invention, carbon black having a broad aggregate distribution of aggregates can be efficiently produced in a stable furnace operation. Therefore,
It is extremely useful as a mass production technology of carbon black suitable for energy-saving tires.

Claims (2)

[Claims] 1. A combustion process in which a fuel is burned to generate a high temperature combustion gas, a raw material oil introduction process in which a raw material hydrocarbon is injected into a high temperature combustion gas stream in a narrow-diameter throat, and a carbon black is produced by a pyrolysis reaction of the raw material hydrocarbon. In the process consisting of a reaction step for converting into a raw material oil and a reaction stopping step for terminating the thermal decomposition reaction by quenching the reaction gas, a double-walled metal structure having a heat exchange function in the narrow-diameter throat part forming the feed oil introducing step. The method for producing carbon black, comprising: a cooling cell, and injecting the raw material oil from the periphery into a depth position corresponding to 10 to 40% of the diameter of the narrow throat portion. 2. The method according to claim 1, wherein air or oxygen-enriched air is introduced into the cooling cell as a cooling medium, and the air or oxygen-enriched air preheated by the heat exchange function is circulated and used as a combustion-supporting gas for fuel. Carbon black manufacturing method.