FR2666084A1 - Furnace for the manufacture of carbon black - Google Patents

Abstract

This furnace for the production of carbon black comprises a combustion zone, a reaction zone which has a section of small diameter and a reaction end zone, the internal wall of the furnace in the said combustion zone being made of an oxidised ceramic chosen from the group consisting of the following refractory materials (A), (B) and (C) and also at least one part of the inner wall of the furnace at the section of small diameter of the said reaction zone being made of an oxidised ceramic chosen from the group consisting of the following refractory materials (A), (B) and (C): (A) a refractory material based on zirconia and hafnium oxide, comprising a laminate consisting of a layer of zirconia and a layer of hafnium oxide which are at least partially stabilised, each of the layers comprising at least one oxide chosen from the group consisting of lime, magnesia, yttria and ceric oxide, (B) a refractory material based on zirconia comprising a laminate consisting of a layer of at least partially stabilised zirconia containing yttria and of a layer of at least partially stabilised zirconia containing lime, and (C) a refractory material based on alumina-yttria comprising a laminate consisting of a layer of alumina and a layer of yttria.

Description

OVEN OF MANUFACTURE OF CARBON BLACK
BACKGROUND OF THE INVENTION
The present invention relates to a carbon black furnace, and more particularly to a carbon black furnace which allows the temperature of the reaction zone to be raised in a remarkable manner.

 With the increase in performance of cars in recent years, the need for a more stringent pneumatic tire has also been felt. In particular, better abrasion resistance is required for large tires such as trucks, buses, etc.

The use of a carbon black having a high specific surface area and a coloring power, for example N-10O,
N-121 or N-234, has so far been considered satisfactory to achieve the above objectives with respect to the carbon black for loading the rubber of the tread of a tire.

 It is known from the state of the art that examples of factors important for making the carbon black described above having a small particle diameter (i.e., a high specific surface area) and a high color strength comprise a method according to which a high temperature combustion gas jet formed by the combustion of an oil is rotated at a high speed, a method according to which a hydrocarbon oil charge is thermally decomposed at a high temperature and a process wherein a charge of hydrocarbon oil is introduced into a jet of high temperature combustion gas with a high linear velocity.

 For example, US Pat. No. 2,851,337 discloses a process for preparing carbon black in which a venturi type carbon black furnace having a small diameter groove comprises a burner for supplying the hydrocarbon feed inserted into the groove in the direction normal to the axis of the furnace, while the linear speed of the jet of combustion gas at the throat is set at 46 m / s (150 feet per second), preferably 61 m / s (preferably 200 feet per second) at 1219 m / s (4000 feet per second) to bring the jet of combustion gas to a high temperature (with a combustion flame temperature ranging from 1093 to 1640 ° C (2000 to 3000) F)] in closer contact with the hydrocarbon charge.

 U.S. Patent No. 3,490,867 discloses a venturi type furnace wherein the furnace head has two combustion chambers for burning an oil, while high temperature combustion gas jets are converged. in the respective combustion chambers at a point, and inserting a charge oil injection nozzle at the inlet of the large diameter section of the upstream side of the venturi in the axial direction of the furnace.According to the description of the patent, the linear velocity at the small diameter groove is from 300 to 2600 feet per second, preferably 137 to 487 m / s (from 450 to 1600 feet per second), the temperature of the flue gas is 1929 to 1693 ° C (3500 to 2900 ° F), and the outlet temperature of the throat after injection of the filler oil is 1760 to 1427 ° C (3200 to 2600 ° F). "F).

 To apply the method of rotating the jet of high temperature combustion gas at a high speed or to impart a high linear velocity to a high temperature combustion gas jet at the feed oil introduction level in a carbon black manufacturing furnace actually in service, the supply air pressure must be high to the point that it becomes necessary to have large-scale power supply facilities. However, it is difficult to expect a significant improvement in properties to a degree corresponding to the provision of such large scale facilities.

 On the other hand, raising the temperature of the filler oil injection region not only serves as a useful means for efficiently producing a carbon black having a high specific surface area and also a high coloring power. , but can also make it possible to dispense with any installation of energy supply in the form of additional apparatus. Therefore, such a furnace is suitable as a mass production furnace for a carbon black for abrasion resistant tire.

 In a conventional carbon black furnace, an alumina brick (high or ultra-high alumina content) is used as the refractory lining material for the higher temperature locations, so that the brick comes into contact with a jet of combustion gas whose temperature exceeds the maximum temperature (about 1900 ° C) that the brick can withstand, phenomena such as peeling or melting appearing after a short period of time, which makes it difficult to drive the oven.

SUMMARY OF THE INVENTION
An object of the present invention is to eliminate the disadvantages of a conventional furnace described above for the manufacture of carbon black and to provide a carbon black manufacturing furnace capable of producing a carbon black having a specific surface area. and a high level of coverage by providing a combustion zone upstream of the feed oil introduction location, and a reaction zone having a structure capable of withstanding a high temperature exceeding 2000 ° C necessary for the thermal decomposition reaction.

The above-described object of the present invention can be achieved by a carbon black furnace comprising a combustion zone, a reaction zone having a small diameter section provided on the downstream side of said combustion zone and in connection therewith in the axial direction of the furnace, and an end-of-reaction zone provided on the downstream side of said reaction zone and connected thereto in the axial direction of the furnace, a jet of combustion gas at high temperature being formed in said combustion zone by the combustion of a fuel oil, a charge oil being introduced into said jet of high temperature combustion gas in said reaction zone to produce a carbon black by the thermal decomposition of said filler oil, said thermal decomposition ending in said end-of-reaction zone for quenching the carbon black formed, the inner wall of the furnace in said zone combustion apparatus being made of an oxidized ceramic selected from the group consisting of the following refractory materials (A), (B) and (C) and also at least a portion of the inner wall of the furnace at the small diameter section said reaction zone being made of an oxide ceramic selected from the group consisting of the following refractory materials (A), (B) and (C)
(A) a zirconia and hafnium oxide refractory material comprising a laminate composed of at least partially stabilized zirconia layer and hafnium oxide layer, each layer comprising at least one selected oxide in the group consisting of lime, magnesia, yttria and ceria,
(B) a zirconia refractory material comprising a laminate composed of an at least partially stabilized zirconia layer containing yttria and an at least partially stabilized zirconia layer containing lime, and
(C) a refractory material based on alumina-yttria comprising a laminate composed of a layer of alumina and a layer of yttria.

PREFERRED EMBODIMENTS OF THE INVENTION
The carbon black furnace according to the present invention comprises a combustion zone, a reaction zone, and an end-of-reaction zone provided in this order from the upstream side to the downstream side in the axial direction of the furnace. .

 The combustion zone is located at the furnace head and fuel oil and combustion air are introduced to form a jet of high temperature combustion gas by burning the fuel oil.

 The combustion zone is generally larger in diameter than the reaction zone. The reaction zone is located on the downstream side of the combustion zone. In the reaction zone, a hydrocarbon feed oil is injected into the high temperature combustion gas jet formed in the combustion zone for thermal decomposition to carbon black.

 The reaction zone comprises, in an exemplary venturi type carbon black furnace, a small diameter groove having a reduced diameter along its length from the upstream side to the downstream side, a section a small diameter (also called "straight length") having a given length following the groove, and a large diameter groove provided on the downstream side of the small diameter section and having a diameter gradually increasing along its length since its upstream side to its downstream side. The hydrocarbon feed oil is generally introduced into the small diameter section.

The present invention, however, is not limited to the venturi-type carbon black furnace and may be applicable to all carbon black furnaces having a reaction zone having a small diameter section.

 The small diameter section serves to give a high linear velocity to the jet of high temperature combustion gas formed in the combustion zone and, at the same time, to put the injected hydrocarbon feed oil in close contact with the jet of combustion. combustion gas at high temperature, whereby a homogeneous decomposition of the hydrocarbon feed oil is obtained.

The reaction completion zone has a diameter greater than that of the reaction zone. In this zone, the carbon black and gaseous by-product formed in the reaction zone are rapidly cooled to complete formation of the carbon black. In the carbon black furnace according to the present invention, the furnace inner wall in the combustion zone is made of a refractory material selected from the group consisting of the following elements (A), (B), and ( C), and also at least a portion of the inner wall of the furnace in the small diameter section of the reaction zone is formed of a refractory material selected from the group consisting of the following elements (A), (B), and (C)
(A) a zirconia-oxide refractory material
hafnium,
(B) a zirconia-based refractory material, and
(C) a refractory material based on alumina-yttria.

 The zirconia-hafnium oxide refractory material (A) has a structure comprising two layers consisting of a layer of zirconia and a layer of hafnium oxide laminated one on the other and can be prepared according to a process described in Japanese Patent Application No. 643398431.

 Specifically, the zirconia layer (ZrO 2) and the hafnium oxide layer (HfO 2) may respectively comprise a stabilized zirconia and a stabilized hafnium oxide each comprising at least one oxide (stabilizer) chosen from the group formed by lime (CaO), magnesia (MgO), yttria (Y203) and ceric oxide (CeO2).

The stabilized zirconia and the stabilized hafnium oxide described above are classified as partially stabilized zirconia and hafnium oxide and in zirconia and hafnium oxide completely stabilized according to the degree of stabilization. The partially stabilized zaffone and hafnium oxide are of the cubic system type while the zirconia and hafnium oxide are completely stabilized and are of the orthorhombic system type.

 The stabilized zirconia and hafnium oxide described above are milled and adjusted to obtain a particle size sufficient to allow dense compaction, a binder is added and kneaded, and the kneaded products are compacted in a mold so as to form respective layers having a predetermined thickness, pressure molded and sintered at 1500 ° C or more, preferably 1600 to 2000 ° C, to prepare a refractory material comprising a stabilized zirconia layer and a layer of stabilized hafnium oxide. In this refractory material, the boundary layer between the zirconia layer and the hafnium oxide layer is in the bonded state in the form of a solid solution so that no peeling phenomenon occurs.

 The zirconia refractory material (B) can be prepared according to Japanese Patent Application No. 339829/1989, ie by laminating a partially stabilized or completely stabilized zirconia layer (ZrO 2) containing yttria (Y20s), and a partially stabilized or completely stabilized zir cone layer containing lime (CaO) one above the other and sintering the laminate at 1500 ° C or more, preferably from 1600 to 1800 "C. Both layers are in a fully integrated state.

 The refractory material (C) based on alumina-yttria has a structure comprising two layers composed of a layer of alumina and a layer of yttria laminated one on the other and can be prepared according to a method described in Japanese Patent Publication No. 339830/1989, and the two layers are in the fully integrated state. Specifically, alumina (Al 2 O 3) and yttria (Y 2 O 3) are ground and set to correct particle, a binder is added and kneaded together, and the kneaded products are compacted in a mold to form the respective layers having a predetermined thickness, pressure molded and sintered at 1500 ° C or higher for preparing a refractory material comprising a layer of alumina and a layer of yttria firmly integrated with each other.

 As described above, according to the present invention, a refractory material selected from the group consisting of the elements (A), (B) and (C) described above is used for the inner wall of the combustion zone of the production oven. Also, according to the present invention, a refractory material selected from the group consisting of the elements (A), (B) and (C) described above is used for at least a portion of the inner wall of the small diameter section. in the reaction zone.

 As described above, all refractory materials (A), (B) and (C) have a layered structure comprising two layers. Although one or both of the two layers may be exposed to the interior of the fur, it is preferred to expose a particular layer within the oven. Thus, it is the hafnium oxide layer in the case of the refractory material (A), the zirconia layer containing yttria in the case of the refractory material (B) and the yttria layer in the case of refractory material (C) which is preferably exposed inside the oven.

 All refractory materials used according to the present invention can withstand a temperature exceeding 2000 ° C and have excellent resistance to scale, therefore, even if the temperature of the flue gas passes to a location including the refractory materials described. above 2000 ° C, the materials can be used sufficiently stably over a long period of time.

 In addition, the use of the refractory materials described above makes it possible to form a region whose high temperature exceeds 2000 ° C at the point of introduction of the charge oil, so that the introduced charge oil is decomposed thermally fast and homogeneous and the carbon black formed is in the form of homogeneous aggregates. This makes it possible to give the carbon black a high specific surface and a high coloring power for the same level of specific surface area.

 Since the introduction of the filler oil followed by the progress of the thermal decomposition reaction lowers the temperature of the reaction mixture gas in the reaction zone, a coating comprising a conventional high alumina refractory material is sufficient for the places downstream of the small diameter section and there is no need to coat these places with the refractory material according to the present invention. In particular, since the refractory material based on zirconia-hafnium oxide and the yttria-based refractory material are weakly resistant to a reducing atmosphere, they are not suitable for coating the furnace wall downstream of the refractory section. small diameter.

The invention will now be described in greater detail with reference to the following examples
EXAMPLE 1
(1) Oven structure
It is a carbon black reactor having a venturi type structure comprising: a combustion zone with a diameter of 1000 mm and a length of 1500 mm, the reactor head having an inlet of supplying air in the tangential direction and a combustion burner being inserted in the axial direction of the furnace; a reaction zone in the small diameter groove comprising, successively located downstream of the combustion zone in the axial direction of the furnace, a conical section having a length of 1000 mm and a decreasing diameter over this length of 350 mm up to 230 mm, a straight section having a diameter of 230 mm and a length of 500 mm and a conical section having a length of 600 mm and a diameter increasing over this length from 230 mm to 500 mm; and an end-of-reaction zone having a diameter of 500 mm and a length of 8000 mm located after the reaction zone and downstream thereof in the axial direction of the furnace, said end-of-reaction zone being equipped with a rapid cooling device.

(2) Refractory material used in the reactor
In the reactor described above, the combustion zone and the entire region on the upstream side of the feed oil introduction location were coated with a zirconia-hafnium oxide refractory material having the two-layer structure of a laminate comprising a zirconia layer (thickness: 30 mm) and a layer of hafnium oxide (thickness: 30 mm) bonded to each other in the form of a solid solution of in such a way that it is the layer of hafnium oxide that was exposed inside the furnace, while the region on the downstream side of the feed introduction place was coated with a conventional refractory material high alumina content.

(3) Production conditions of carbon black
An oil was introduced through the combustion burner into the combustion zone, and a filler oil was atomized and injected as radial jets from the periphery of the cross-section of the reaction zone and directed to the combustion zone. a flue gas stream at high temperature, by means of nozzles (6 nozzles) provided on the cross section of the reaction zone.

 Cooling water was provided at a location 2.4 mm from the entrance to the end-of-reaction zone.

 As regards the other conditions, the amount of air for the atomization of the fuel oil and the temperature for the preheating of the combustion air were respectively 150 Nm3 / h and 600 ° C.

(4) Properties of oil and filler oil
Fuel oil and feed oil used were hydrocarbons having the properties shown in Table I.

(5) Yield and properties of carbon black
form
The yield, properties, condition of the furnace wall and other indications concerning three types of carbon black (1-1, 1-2, 1-3) produced under various production conditions are given on the Table II.

EXAMPLE 2
Three types of carbon black (2-1, 2-2, 2-3) were produced in an oven configuration identical to that of Example 1 and under conditions specified in Table II, except the refractory lining material of the combustion zone and throat of the small-diameter zone has been changed to a zirconia-based refractory material having a bilayer structure comprising a zirconia layer containing yttria (thickness: 5 mm), having a degree of stabilization of 90% and a layer of zirconia containing lime (thickness: 55 mm) having a degree of stabilization of 84%, these two layers being laminated and integrated with each other and arranged in such a way that the zirconia layer containing yttria is exposed to bare inside the furnace.The yield, properties, condition of the furnace wall and other indications on the blacks of carbon formed are given in Table II.

EXAMPLE 3
Three types of carbon black (3-1, 3-2, 3-3) were produced in an oven configuration identical to that of Example 1 and under conditions specified in Table II, except the refractory lining material of the combustion zone and throat of the small-diameter zone has been changed to an alumina-yttria-based refractory material comprising a two-layer structure having a layer of alumina (thickness: 30 mm) and a layer of yttria (thickness: 30 mm) laminated and integrated with each other and arranged in such a way that the yttria layer is exposed inside the oven. The yield, properties, condition of the furnace wall and other indications on the carbon blacks formed are given in Table II.

COMPARATIVE EXAMPLE 1
Three types of carbon black (Comparative Example 1-1, 1-2 and 1-3) were produced in an oven configuration identical to that of Example 1 and under conditions specified in Table II, if The refractory coating material of the combustion zone and throat of the small diameter zone has been changed to a conventional alumina-based refractory material.The yield, the properties, the state of the wall of the furnace and other indications on the carbon blacks formed are given in Table II.

 The results shown in Table II show that in the examples, despite a flue gas temperature exceeding 1900 C at the place of introduction of the filler oil, no melting or peeling was observed after the reaction, that is, the condition of the furnace wall after reaction was good. Moreover, it was confirmed that the yield, the coloring power, the DBP dibutyl phthalate absorption index (standard ASDM), 24M4DBP (the dibutyl phthalate absorption index on a compressed sample), etc., at the three specific surface levels (nitrogen adsorption specific surface area: approximately 120 m2 / g, approximately 140 m2 g / g, and about 160 m 2 / g) were relatively better than those of the comparative example due to the fact that the thermal decomposition reaction in a high temperature flue gas became possible.

 As described above, the use of a carbon black production furnace according to the present invention allows the temperature of the flue gas in the thermal decomposition reaction zone to be raised to 1900 ° C. Furthermore, it is possible to work in a stable manner so that it becomes possible to mass-produce a carbon black having a high specific surface area and coloring power with high efficiency.

 As a result, the carbon black production furnace according to the present invention is very useful as a carbon black production furnace for rubber for large tires which require high abrasion resistance.

TABLE I

<tb> Properties <SEP> Fuel <SEP> Oil <SEP> of <SEP> charge
<tb> Specific <SEP> mass
<tb><SEP> (15/4 C) <SEP> 0.977 <SEP> 1.137
<tb> Insoluble <SEP> Materials
<tb> in <SEP><SEP> toluene <SEP> (%) <SEP> 0.01 <SEP> 0.05
<tb> BMCI <SEP>(<SEP>index> of <SEP> correlation
<tb><SEP> of <SEP> Desktop <SEP> of <SEP> Mines <SEP> 111 <SEP> 162
<tb> Content <SEP> in <SEP> sulfur <SEP> (%) <SEP> 0.09 <SEP> 0.51
<tb> Boiling point <SEP><SEP> ini
<tb><SEP> tial <SEP>("C)<SEP> 133 <SEP> 203
<tb> Content <SEP> in <SEP> ions <SEP> Na <SEP> (ppm) <SEP> 1.7 <SEP> 1.0
<tb> Content <SEP> in <SEP> ions <SEP> K <SEP> (ppm) <SEP> 0.6 <SEP> 0.3
<Tb>
TABLE II

<SEP> Example <SEP> 1 <SEP> Example <SEP> 2 <SEP> Example <SEP> 3 <SEP> Ex. <SEP> Comparative <SEP> 1
<tb><SEP> 1-1 <SEP> 1-2 <SEP> 1-3 <SEP> 2-1 <SEP> 2-2 <SEP> 2-3 <SEP> 3-1 <SEP> 3- 2 <SEP> 3-3 <SEP> 1-1 <SEP> 1-2 <SEP> 1-3
<tb><SEP> Material <SEP> refrao
<SEP> hide <SEP> for <SEP> the <SEP> zone
<tb><SEP> of <SEP> combustion <SEP> and <SEP> the <SEP> Zirconia / oxy <SEP> alumina /
<tb><SEP> Zirconia <SEP> Alumina
<tb> yttria
<tb><SEP> section <SEP> of <SEP> small <SEP> of <SEP> hafnium
<tb><SEP> diameter
<tb><SEP> flow <SEP> of air
<tb><SEP> feed <SEP> 8550 <SEP> 8550 <SEP> 8550 <SEP> 8550
<tb> (Nm3 / h)
<tb><SEP> debit <SEP> of <SEP> oil
<tb><SEP> feed <SEP> 755 <SEP> 692 <SE> 639 <SEP> 519
<tb><SEP> (kg / h)
<tb><SEP> rate <SEP> of <SEP> combustion <SEP> 110 <SEP> 120 <SEP> 130 <SEP> 160
<tb> (%)
<tb><SEP> flow <SEP> supply <SEP> in <SEP> oil <SEP> from
<tb><SEP> 2317 <SEP> 1957 <SE> 1736 <SE> 2308 <SEP> 1965 <SE> 1766 <SE> 2273 <SEP> 1949 <SEP> 1754 <SEP> 2316 <SEP> 1995 <SEP> 1831
<tb><SEP> load <SEP> (kg / h)
<tb><SEP> temperature <SEP> of <SEP> gas
<tb> of <SEP> combustion <SEP> at
<tb> introductory level <SEP>
<SEP> 2160 <SEP> 2120 <SEP> 2130 <SEP> 2080 <SE> 2090 <SE> 2060 <SEP> 1950 <SEP> 1970 <SEP> 1940 <SEP> 1850 <SEP> 1820 <SEP> 1860
<tb><SEP> tion <SEP> of <SEP> the oil <SEP> of
<tb><SEP> load <SEP> (C)
<tb><SEP> Yield <SEP> in <SEP> black
<tb><SEP> of <SEP> carbon <SEP> (% <SEP> in
<tb> weight <SEP> per <SEP> report
<tb><SEP> 47.4 <SEP> 44.2 <SEP> 42.0 <SEP> 46.0 <SEP> 43.8 <SEP> 41.1 <SE> 45.3 <SEP> 42, 1 <SEP> 39.7 <SEP> 43.6 <SEP> 40.6 <SEP> 38.1
<tb><SEP> at <SEP> oil <SEP> + <SEP> oil
<tb> of <SEP> load)
<tb><SEP> Flow <SEP> of <SEP> production
<tb><SEP> of the <SEP> black <SEP> of <SEP> carbo- <SEP> 1455 <SEP> 1200 <SEP> 1045 <SE> 1380 <SEP> 1165 <SEP> 1010 <SE> 1320 <SEP > 1090 <SEP> 950 <SEP> 1235 <SEP> 1020 <SEP> 895
<tb><SEP> ne <SEP> (kg / h)
<tb><SEP> adsorption <SEP> of iodine
<tb> (mg / h)
<tb><SEP> 118 <SEP> 141 <SEP> 162 <SEP> 123 <SEP> 146 <SEP> 160 <SEP> 121 <SEP> 144 <SEP> 157 <SEP> 120 <SEQ> 143 <SEP> 158
<tb><SEP> specific <SEP> surface
<tb><SEP> of nitrogen adsorption <SEP>
<tb><SEP> (m2 / g)
<tb><SEP> 121 <SEP> 139 <SEP> 160 <SEP> 126 <SEP> 147 <SE> 160 <SEP> 124 <SEP> 144 <SEP> 158 <SEP> 125 <SEP> 145 <SEP> 159
<tb> power <SEP> dye
<tb><SEP> 124 <SEP> 127 <SEP> 132 <SEP> 123 <SEP> 127 <SEP> 131 <SEP> 123 <SEP> 126 <SEP> 130 <SEP> 120 <SEP> 123 <SEP> 128
<tb><SEP> (%)
<tb><SEP> Absorption <SEP> DBP
<tb><SEP> (ml / 100 <SEP> g) <SEP> 120 <SEP> 121 <SEP> 117 <SEP> 118 <SEP> 118 <SEP> 119 <SEP> 117 <SEP> 116 <SEP> 117 <SEP> 118 <SEP> 115 <SEP> 117
<tb><SEP> Absorption <SEP> 24M4DBP
<tb><SEP> (ml / 100 <SEP> g)
<tb><SEP> 104 <SEP> 102 <SEP> 103 <SEP> 102 <SEP> 103 <SEP> 101 <SEP> 102 <SEP> 103 <SEP> 102 <SEP> 100 <SEP> 101 <SEP> 103
<tb> Status <SEP> of <SEP><SEP> Wall <SEP> in
<tb><SEP> dull <SEP> of the <SEP> furnace <SEP> after <SEP> B <SEP> B <SEP> P <SEP> B <SEP> B <SEP> P <SEP> B <SEP> P <SEP> B <SEP> B <SEP> B <SEP> P
<tb> running <SEP> of
<tb> long <SEP> duration
<Tb>
B = good P = Fair

Claims (6)

 (C) a refractory material based on alumina-yttria comprising a laminate composed of a layer of alumina and a layer of yttria.  (B) a zirconia refractory material comprising a laminate composed of an at least partially stabilized zirconia layer containing yttria and an at least partially stabilized zirconia layer containing lime, and  (A) a zirconia and hafnium oxide refractory material comprising a laminate composed of at least partially stabilized zirconia layer and hafnium oxide layer, each layer comprising at least one selected oxide in the group consisting of lime, magnesia, yttria and ceria,  characterized in that the inner wall of the furnace in said combustion zone is made of an oxide ceramic selected from the group consisting of the following refractory materials (A), (B) and (C) and also at least a part of the inner wall of the furnace at the small diameter section of said reaction zone is made of an oxidized ceramic selected from the group consisting of the following refractory materials (A), (B) and (C) ::  1. A carbon black production furnace comprising a combustion zone, a reaction zone having a small diameter section provided on the downstream side of said combustion zone and in connection therewith in the axial direction of the furnace, and an end-of-reaction zone provided on the downstream side of said reaction zone and connected thereto in the axial direction of the furnace, a jet of high temperature combustion gas being formed in said combustion zone by combustion a fuel oil, a charge oil being introduced into said jet of high temperature combustion gas in said reaction zone to produce a carbon black by the thermal decomposition of said charge oil, said thermal decomposition ending in said end-of-reaction zone for suddenly cooling the carbon black formed, 2. Production furnace according to claim 1, characterized in that the stabilized zirconia and the stabilized oxide of said refractory material (A) are respectively selected from the group consisting of a partially stabilized zirconia, a completely stabilized zirconia, a hafnium oxide partially stabilized and a completely stabilized hafnium oxide. Production furnace according to claim 1, characterized in that the stabilized zirconia containing yttria and the stabilized zirconia containing lime of said refractory material (B) are respectively selected from the group consisting of a partially stabilized zirconia containing yttria, a completely stabilized zirconia containing yttria, a partially stabilized zirconia containing lime and a completely stabilized zirconia containing lime. 4. Production furnace according to claim 1, characterized in that the side of the hafnium oxide layer of said refractory material (A) is exposed inside the furnace. 5. Production furnace according to claim 1, characterized in that the side of the zirconia layer containing the yttria of said refractory material (B) is exposed inside the furnace. 6. Production furnace according to claim 1, characterized in that the side of the yttria layer of said refractory material (C) is exposed inside the furnace.