Mfg. carbon black

DESCRIPTION

Foundation of the Invention

Carbon black is obtained by incomplete combustion of a hydrocarbon such as petroleum, natural gas and other well-known materials, at elevated temperatures. When separated from the reaction gases, the product is a spongy carbon black powder.

Carbon black can be obtained using a molecular weight or in stages such as, for example, of the type described and claimed in US Patent Reissue No. 28,974. The stepwise process consists of a primary combustion zone (first stage) where a stream of hot gaseous combustion products is formed; a second transition zone or zone where a liquid hydrocarbon feed is injected, either in pre-atomized form or in the form of coherent non-preatomized streams, substantially radially from the outer or inner periphery of the gaseous combustion stream inside of the preformed stream of hot combustion gases; and a third zone (the reaction zone) where the formation of the carbon black is verified before the term of the reaction by cooling.

However, there are cases where it is convenient to produce carbon blacks that, for a given surface area, are characterized by having a lower coloring power and a greater structure. Carbon blacks are useful in the preparation of rubber compounds that have increased mast and rebound values.

Consequently, the main object of the invention is to provide a new and improved process for the preparation of carbon blacks which, for a given surface area, are characterized by having a lower coloring power and a greater structure.

This and other objects, advantages and characteristics of the present invention will become apparent to the person skilled in the art after consideration of the following detailed description and attached claims.

Summary of the Invention

The process of the present invention comprises forming a gaseous stream of hot combustion by reacting a fuel or an oxidant in a first combustion zone or primary combustion zone. The relative pressure, or pressure above the environmental pressure, within the combustion zone is at least 51 mm of mercury. Preferably, the relative pressure within the combustion zone should be at least 152 mm of mercury and more preferably more than 254 mm of mercury. The feed is then injected into the gaseous stream of hot combustion in a substantially radial or axial manner. Preferably, the feed is injected into the combustion gas stream in the form of coherent streams not preatomized radially inwards or outwards from the inner and / or outer periphery of the combustor gas stream. It is also possible, when the feed is injected both from the outer periphery and from the inner periphery of the gaseous stream of combustioán, to inject said feed in a preatomized form from one of the peripheries and in a non-preatomized form from the other periphery.

After the injection of the feed into the gaseous stream of combustion, said gaseous stream of combustion, containing the feed, flows through the transition zone into a first reaction zone having a larger internal cross-sectional area than that shown by the transition zone. Preferably, the ratio of the area in the internal transverse section of the first reaction zone to that of the transition zone is between 1.1 and 4. From the first reaction zone, the gaseous stream of combustion flows into a throat area that has an area in internal cross section smaller than that of the transition zone. Preferably, the ratio of the area in the internal transverse section of the throat area to that of the transition zone will be between approximately 0.25 and 0.9.

From the throat area, a gaseous stream of combustioán, which contains the food, flows into a second reaction zone that has an area in internal cross-section greater than that of the throat area. Preferably, the ratio of the internal cross-sectional area of ​​the second reaction zone to that of the transition zone will be between approximately 1.1 and 16. Next, and within the second reaction zone, the carbon black formation process is terminated by injecting a cooling medium, such as water.

Brief description of the drawings

Figure 1 is a sectional, longitudinal, schematic view of a typical oven for the production of carbon black used in examples 1 and 3.

Figure 2 is a sectional, longitudinal, schematic view of a typical furnace for the production of carbon black used in Examples 2 and 4.

A detailed description of the furnace shown in Figure 2 and which was used in the process of the present invention is given below.

With reference to FIG. 2, there is shown an oven 1 consisting of 5 zones, a primary combustion zone 10, a transition zone 13, a first reaction zone 31, a throat zone 33 and a second zone of reaction 35 within which a cooling probe 41 is placed to terminate the carbon black forming reaction.

The combustion zone 10 is defined by the upstream wall 6 and by the side wall 4 and ends at point 12 which is the beginning of the transition zone 13. Through the wall 6 a conduit 8 has been introduced through from which fuel is introduced into the combustion zone 10. Through the side wall 4 a conduit 5 has been introduced through which an oxidant is introduced into the combustion zone 10. A flame stabilizer 11 attached to the tube 13 is contained within the combustion zone 10 which is inserted into the

006 984 combustion zone 10 through the hole 7 of the wall 6. Downstream of the combustion zone 10 and connected with the latter, is the transition zone 13 defined by the wall 17 which begins at point 12 and ends at point

14. Circumferentially located around the wall 17 there is a plurality of holes 21, oriented substantially radially, through which the feed can be injected into the transition zone 13.

Downstream of the transition zone 13 and connected to the latter, is the first reaction zone 31 defined by the wall 37. The zone 31 can be of varying length and width depending on the desired reaction conditions. However, the aorea in the internal transverse section of the first reaction zone 31 must be greater than that of the transition zone 13. Preferably, the ratio of the air in the internal transverse section of the first reaction zone to that of the transition zone was between 1.1 and 4. The wall 37 then converges at an angle of 45 ° to the center line of the furnace 1 and leads to wall 38 at point 32. Wall 38 defines the throat area 33. The aorea in the internal cross-section of the throat area 33 is inferior to the air in the internal cross-section of the transition zone 13. Preferably, the ratio of the aorea in the internal transverse section of the throat area 33 to the aortic in the internal transverse section of the transition zone 13 was between approximately 0.25 and 0.9. The downstream end 34 of the wall 38 leads into the interior of the wall 39. The wall 39 diverges in an angle of 30^° with respect to the central line of the furnace 1 and defines the second reaction zone 35. The air in the internal cross section of the second reaction zone 35 is superior to the area in the internal cross section of the throat area 33. Preferably, the relationship of the aorea in the internal transverse section of the second reaction zone 35 to that of the transition zone 13 was approximately 1.1 to 16. A cooling probe 41 is located through the wall 39 inside the second reaction zone 35 through which a cooling medium, such as water, can be injected to terminate the carbon black forming reaction .

In general, the process of the present invention for the production of carbon blacks of a given surface air, characterized by low coloring power and a superior structure, is carried out as follows.

In one of combustion, a suitable fuel is introduced through a conduit and, through another conduit, a suitable oxidant such as air, oxygen, mixtures of air and oxygen and the like. Suitable fuels for use in the reaction with the oxidizing current, in a combustion chamber, for generating hot combustion gases, include any easily combustible matter, in gaseous, vapor or liquid form, such as hydrogen, carbon monoxide , methane, acetylene, alcohols, kerosene, liquid hydrocarbon fuels and the like. In general, it is preferable to use hydrocarbons. For example, methane-rich streams, such as natural gas and modified or enriched natural gas, are excellent fuels, as well as other streams that contain high amounts of hydrocarbons, such as various hydrocarbon gases and liquids and refinery by-products that include fractions of ethane, propane, butane, pentane, fuel oils and the like.

As indicated here, primary combustion represents the amount of oxidant present in the first stage of the modular process divided by the amount of oxidant theoretically required for the complete combustion of the hydrocarbon present in the first stage of the process, to form carbon dioxide and water, multiplied by 100 to obtain a percentage. The primary combustion can range from 100 to 500%. In this way, a stream of hot combustion gases that flow at high speed is generated.

The relative pressure within the combustion zone is at least 51 mm of mercury. On the other hand, it has been found that the relative pressure within the combustion zone should be at least 152 mm of mercury and more than preferably 254 mm of mercury. Under these conditions, a stream of gaseous combustion products is obtained that possess enough energy to convert a hydrocarbonaceous feed, preferably liquid, producing carbon black, into the desired carbon black products. The resulting combustion gases, emanating from the combustion stage, reach a temperature of at least 1316^°C, the temperature being preferably more than at least 1649^°C approximately.

The hot combustion gases are discharged from the downstream end of the combustion zone at high speed, which is accelerated by passing the combustion gases through a transition zone of an airborne in smaller internal cross-section. The feed is injected into the gaseous stream of combustion, preferably at the midpoint of the transition zone. In addition, preferably, the feed is injected in the form of a plurality of coherent streams not preatomized in a substantially radial direction with respect to the flow of the gaseous to combustion stream, either from its outer periphery or from its inner periphery, through a plurality of holes. Likewise, the feed can be injected both at the midpoint of the transition zone and upstream of the midpoint of the transition zone. Suitable hydrocarbon feeds are unsaturated hydrocarbons such as acetylene; olefins such as ethylene, propylene and butylene; aromatics such as benzene, toluene and xylene; certain saturated hydrocarbons and volatilized hydrocarbons such as kerosenes, naphthalenes, terpenes, tars, ethylenic, aromatic cycle materials and the like. With respect to the previous injections of the feed at the defined points, the feed may be the same or different.

The amounts of feed, fuel and oxidant used were adjusted so that ob3

006 984 has a total combustion percentage between 15 and 60%, preferably between approximately 25 and 40%. Total combustion represents the total amount of oxidant used in the carbon black formation process divided by the amount of oxidant required for the complete combustion of the total amount of hydrocarbon present in the carbon black forming process, to obtain dioxide of carbon and water, multiplied by 100 in order to get a percentage.

From the transition zone , the gaseous stream of combustion, containing feed, flows into a first reaction zone that has an aorea in the internal transverse section greater than that of the transition zone, preferably being the ratio of the order of 1 , 1 to 4.0 approximately. The gaseous stream of hot combustion, which contains feed, then flows into a throat area. The air in the internal transverse section of the throat area is inferior to the air in the internal transverse section of the transition zone. Preferably, the ratio of the aorea in the internal transverse section of the throat area to that of the transition zone was approximately 0.25 to 0.9.

From the throat area, the gaseous stream of hot combustion, which contains feed, flows into a second reaction zone. The air in the internal transverse section of the second reaction zone is larger than the air in the internal cross section of the throat area. With reference, the air in the internal transverse section of the second reaction zone is greater than that of the transition zone, the reaction being preferably of the order of approximately 1.1 to 16.

Within the second reaction zone, a sufficient residence time is provided to allow the carbon black forming reactions to be verified before the cooling reaction time. An exemplary way of carrying out cooling is to inject water through a cooling nozzle. However, there are many other methods known in the art to cool the carbon black forming process. The hot effluent gases, which contain the carbon black products suspended therein, are then subjected to the conventional stages of cooling, separation and collection of the carbon black. The separation of the carbon black from the gas stream was easily carried out by any conventional means, such as a precipitator, a cyclonic separator, a bag filter or a combination of the above.

When determining the analytical properties of carbon blacks produced by the present invention, the following test procedures are used.

Iodine adsorption index

It is determined in accordance with ASTM-D-151081.

Coloring power

It is determined in accordance with ASTM D-326580.

Dibutyl Phthalate Absorption (DBP)

It is determined in accordance with ASTM D-241482. The recorded results indicate whether carbon black is spongy or pellet-shaped.

Crushed DBP Absorption Index (CDBP)

It is determined in accordance with ASTM D-349382.

Rubber compounds

When evaluating the behavior of carbon blacks of the present invention, the following formulations are used where the amounts are specified in parts by weight.

TABLE I

Rubber formulations

ASTM D-3192-79 ASTM D-3191-82

Formulation A Formulation B

Rubber recipe Synthetic natural rubber recipe

<td>TO</td><td>B</td><td>C</td>

<td>Polymer</td><td>(Rubber</td><td>(SBR1500-</td>

<td></td><td>natural)</td><td> 23,5 %</td>

<td></td><td> 100</td><td>styrene 76.5% butadiene) 100</td>

<td>Zinc oxide</td><td> 5</td><td> 3</td>

<td>Sulfur</td><td> 2,5</td><td> 1,75</td>

<td>Stereoic acid</td><td> 3</td><td> 1</td>

<td>Mercaptobenzothiazyl Disulfide</td><td> 0,6</td><td></td>

<td>N-tert-butyl- 2-benzotia- zosulfenamide</td><td></td><td> 1</td>

<td>Carbon black</td><td> 50</td><td> 50</td>

Being:

A. - Ingredient

B. - Parts by weight

C. - Parts by weight

The following test procedures are used to determine the phosphoric properties of a rubber compound containing carbon black produced by the process of the present invention.

Module and traction

The modulus and traction properties are determined according to the procedures described in ASTM D-412-80.

Rebound

It is determined according to the procedure shown in ASTM D-1054-79.

The process of the present invention for the production of carbon black having a lower coloring power and a larger structure could be more easily understood by reference to the following examples. As is logical, there are many other modalities of the invention, which will become apparent to the person skilled in the art, once the invention has been fully described, and it can therefore be recognized that the following examples are offered for illustrative purposes only and not they must be considered as limiting the scope of the invention.

006 984

Example 1

Using the furnace shown in Figure 1, which had a combustion zone identical to that of the furnace shown in Figure 2, preheated air was introduced into the combustion zone 10 at a temperature of 621 ° C, at a rate of 0.746 N / second and natural gas at a speed of 0.0225 mm³ N / second From the above, a stream of hot combustion gases was generated, in a primary combustion of 363%, which flowed downstream at high speed. The relative pressure within the combustion zone 10 was approximately 127 mm of mercury.

The feed was preheated to 204^° and injected radially inwards in the form of coherent streams not preatomized into the gaseous stream of hot combustion through 4 holes 21 at the midpoint of the transition zone 13. An aqueous solution of potassium was added to the gas stream. of hot combustion in a proportion of 1.1 g of potassium per hour. The amount of potassium added did not substantially decrease the level of carbon black structure. The transition zone 13 had a length of approximately 20 cm and an internal cross-sectional area of ​​142 cm². The holes 21, which were each 1.40 mm in diameter, were radially oriented and evenly spaced in a single plane around the circumference of the wall 17 of the transition zone 13. The feed was injected at a speed of 693 1 / hour. The pressure applied at each injection point of the feed was approximately 1159 kPa. The liquid hydrocarbon feed used in the present example had the following analytical properties.

<td>Hydrogen</td><td>(% in weigh)</td><td> 7,71</td>

<td>Carbon</td><td>(% in weigh)</td><td> 90,5</td>

<td>Sulfur</td><td>(% in weigh)</td><td> 1,4</td>

<td>DAP1</td><td> 15,6/15,6^°C</td><td> -1,6</td>

<td>FROM</td><td> 15,6/15,6^°C</td><td> 1,089</td>

<td>V</td><td> 54,4^°C</td><td> 280</td>

<td>V</td><td> 98,9^°C</td><td> 50,5</td>

<td>BMCI</td><td></td><td> 130</td>

Being:

DAP1.- AP1 density

DE.- Specific density

V.- SUS viscosity

BMCl.- (visc-dens)

The transition zone 13 was enlarged to form the reaction zone 31 which was surrounded by refractory and constituted by two sections, an upstream section that had an air in an internal cross section of 602 cm² and a length of 1.7 m, and a downstream section that had an internal cross sectional area of ​​923 cm².

The process was carried out in such a way that the total composition was 32.2%. The cooling nozzle 41 was located at a point 1.8 m downstream from the downstream end 14 of the transition zone 13.

The analytical properties of carbon black are given in Table II and the physical properties of rubber compounds containing carbon black are offered in Tables III and IV.

The present example was a control experiment since it was not a transition zone, as it was in the furnace shown in Figure 2 and used in Example 2.

Example 2

Using the oven shown in Figure 2, 10 preheated air at a temperature of 621 was introduced into the combustion zone^°C at a speed of 0.746 m³ N / second and natural gas at a speed of 0.0225 m³ N / second From the above, a stream of hot combustion gases was generated, at a primary combustion of 363%, which flowed downstream at high speed. The. relative pressure within the combustion zone 10 was approximately 579 mm of mercury.

The feed was preheated to 204^°Ce injected radially inwards in the form of coherent streams not preatomized into the combustion gas stream through 4 holes 21 at the midpoint of the transition zone 13. The transition zone 13 was approximately 20 m long and an air in internal cross section of 142 cm². The holes 21 were radially oriented, each with a diameter of 1.70 mm, and evenly spaced in a single plane around the circumference of the wall 17 of the transition zone 13. The feed was injected at a speed of 662 1 / hour. The pressure applied at each feed injection point was 586 kPa. The liquid hydrocarbon feed used in the present example was the same as in example 1. Potassium was not added to the gaseous stream of hot combustion produced in the present example.

The first reaction zone 31 has an internal cross-sectional area of ​​182 cm² and a length of 39.4 cm. The ratio of the air in the internal transverse section of the first reaction zone 31 to that of the transition zone is 1.28. The throat area 33 has an internal cross-sectional area of ​​81 cm² and a length of 18.3 cm. The ratio of the air in the internal transverse section of the throat area 33 to that of the transition zone 13 is 0.57. The wall 39 defines a second reaction zone 35 consisting of two sections: the upstream section of the second reaction zone 35 has an internal cross-sectional air area of ​​410 cm² and a length of 99 cm, and the downstream section has an internal cross-sectional area of ​​923 cm².Arelation of the cross-sectional area of ​​the section upstream of the second reaction zone 35 to that of the transition zone 13 is 2.9; and the reaction of the cross-sectional area of ​​the downstream section of the second reaction zone 35 to that of the transition zone 13 is of

6,5.

The process was carried out in such a way that the total combustion was 33.3%. The cooling nozzle 41 was located at a point 1.8 m downstream from the downstream end 14 of the

006 984 transition zone 13.

The analytical properties of carbon black are given in Table II and the physical properties of rubber compounds containing carbon black are offered in Tables III and IV.

The comparison of examples 1 and 2 reveals that the use of the process of the present invention translates into the production of a carbon black which, for a given surface area such as, for example, that reflected by the iodine adsorption rates of carbon black, it has a substantially higher level of structure, as reflected by DBP and CBDP measurements. On the other hand, the carbon black obtained by the present invention is characterized by a lower coloring power.

Furthermore, it has been observed that when the carbon blacks obtained by the processes of examples 1 and 2 are incorporated into natural and synthetic rubber formulations, the rubber compounds containing the carbon black of the invention process have a greater modulus and a higher bounce value.

Example 3

Carbon black was produced according to the procedure and apparatus shown in example 1, with the following exceptions. The combustion air was preheated to 477 C. Natural gas was introduced at a speed of 0.0431 m³N / second A stream of hot combustion gases was generated, at a primary combustion of 189%, which flowed downstream at high speed. The relative pressure within the combustion zone 10 was approximately 137 mm of mercury.

The holes 21 were 1.18 mm in diameter. The feed was injected at a rate of 670 1 / hour. The pressure applied at each injection point of the feed was 1198 kPa. No potassium was added to the gaseous stream of combustioin.

The process was carried out in such a way that the total composition was 30.5%. The cooling nozzle 41 was located at a point 3 m downstream from the downstream end 14 of the transition zone 13.

The analytical properties of carbon black are given in table V and the physical properties of rubber compounds containing carbon black are given in tables VI and VII. Example 4

Carbon black was obtained according to the procedure and apparatus shown in example 2, with the following exceptions. The combustion air was preheated to 482 C. Natural gas was introduced at a speed of 0.0431 m³N / second A stream of hot combustion gases was generated, in a primary combustion of 189%, which flowed downstream and at high speed. The relative pressure within the combustion zone was approximately 559 mm of mercury.

The holes 21 were 1.61 mm in diameter. The feed was injected at a rate of 643 1 / hour. The pressure applied at each injection point of the feed was approximately 690 kPa. No potassium was added to hot combustion gases.

The process was carried out so that the total combustion was 31.6%. The cooling nozzle 41 was located at a point approximately 3 m downstream from the garlic-water end 14 of the transition zone 13.

The analytical properties of carbon black are given in Table V and the fossil properties of rubber compounds containing carbon black are offered in Tables VI and VII.

Comparison of the carbon black data obtained in examples 3 and 4 reveals that the effects produced in examples 3 and 4 are practically similar to those observed in the comparison of examples 1 and 2 obtained by using a substantially primary combustion. more low.

TABLE II

Analytical properties

<td>TO</td><td>B</td><td>C</td>

<td>Power Colorant %</td><td> 112</td><td> 107</td>

<td>Iodine mg I index₂/ g carbon black</td><td> 99</td><td> 100</td>

<td>DBP Absorption pellets cc / 100 g</td><td> 121</td><td> 170</td>

<td>CBDB (24M4) cc / 100 g</td><td> 104</td><td> 124</td>

Being:

A. - Property

B. - Example 1

C. - Example 2

TABLE III

Physical properties of vulcanized natural rubber

AB * C *

300% module 15 minutes

<td>MPa 300% modules 30 minutes</td><td> +1,19</td><td> +3,01</td>

<td>MPa Traction, 30 minutes</td><td> +1,68</td><td> +3,15</td>

<td>MPa Rebound</td><td> +0,56</td><td> -2,06</td>

<td>60 minutes (%)</td><td> -5,3</td><td> -2,7</td>

Being:

A.- Property

B * .- Example 1. The data are offered with respect to IRB No. 5.

C * .- Example 2. Data are offered with respect to IRBN^°.5.

(See Table IV in the following page)

006 984

TABLE IV

Physical properties of vulcanized synthetic rubber

AB * C *

<td colspan="3">300% module</td>

<td>35 minutes M Pa</td><td> +0,63</td><td> +3,08</td>

<td>300% module 50 minutes M Pa</td><td> + 2,24</td><td> + 4,27</td>

<td>Traction, 50 minutes M Pa</td><td> - 0,17</td><td> - 0,45</td>

<td>Rebound 60 minutes</td><td> -3,6</td><td> -2,1</td>

A.- Property

B * .- Example 1. The data are offered with respect to IRB No. 5.

C * .- Example 2. The data is offered with respect to IRBNo. 5.

TABLE V

Analytical Properties

<td>TO</td><td>D *</td><td>AND*</td>

<td>Coloring power%</td><td> 110</td><td> 98</td>

<td>Iodine index mg L / g carbon black</td><td> 85</td><td> 83</td>

<td>DBP Absorption Pellets cc / 100 g</td><td> 134</td><td> 163</td>

<td>CBDB (24M4) cc / 100 g</td><td> 102</td><td> 111</td>

Being:

A.- Property

D * .- Example 3. Data are offered with respect to IRBN^°.5.

E * .- Example 4. Data are offered with respect to IRBN^°.5.

TABLE VII

Physical properties of vulcanized synthetic rubber

<td>TO</td><td>D *</td><td>AND*</td>

<td>300% module 35 minutes MPa</td><td> + 3,53</td><td> + 4,69</td>

<td>300% modules 50 minutes M Pa</td><td> + 3,11</td><td> + 4,44</td>

<td>Traction, 50 minutes M Pa</td><td> + 0,66</td><td> + 0,10</td>

<td>Rebound 60 minutes (%)</td><td> -1,5</td><td> - 1,5</td>

A.- Property

D * .- Example 3. Data are offered with respect to IRBN^°.5.

E * .- Example 4. The data are offered with respect to IRBNo. 5.

Describing sufficiently the nature of the invention, as well as the manner of carrying it out in practice, it should be noted that the provisions indicated above and represented in the attached drawings are subject to modifications in detail as long as they do not alter its fundamental principle.

Being:

A.- Property

D. - Example 3

E. - Example 4

TABLE VI

Physical properties of vulcanized natural rubber

AD * E *

Module at 300% minutes

<td>M Pa</td><td> + 2,87</td><td> + 4,48</td>

<td>300% module 30 minutes M Pa</td><td> + 2,80</td><td> + 4,20</td>

<td>Traction, 30 minutes M Pa</td><td> -0,56</td><td> -1,89</td>

<td>Rebound 60 minutes (%)</td><td> -3,2</td><td> -2,2</td>

006 984