IL27095A - Method for production of carbon black - Google Patents

Description

PATIENTS FORM NO. _ 3. 113 PATENTS AND DESIGNS ORDINANCE SPECIFICATION "IMPROVED METHOD FOR PRODUCTION OF CARBON BLACK" We, PHILLIPS PETROLEUM COMPANY, a company incorporated under the laws of the State of Delaware, United States of America of Bartlesville, State of Oklahoma, United States of America DO HEREBY DECLARE the nature of this invention and in what manner CASE 15 89 This invention relates to the production of carbon black by the furnace method wherein a reactant fluid and an oxygen-containing gas are introduced into a reactor at carbon black producing temperatures to produce carbon black. In one aspect this invention relates to a method for producing all of the commercially important grades of carbon black in a reactor of constant volume. In another aspect this invention relates to a method for operating a carbon black furnace under a wide range of pressures so as to produce carbon black having predetermined properties.

It is known to produce carbon black by contacting a liquid hydrocarbon, for example, a gas oil, in a highly dispersed form, with hot combustion gases in a furnace. One preferred process for producing carbon black by this method uses a reaction system of two cylindrical sections, one short section of large diameter, referred to hereinafter as the "combustion chamber", and an elongated section of considerably smaller diameter, referred to hereinafter as the "reaction chamber". The two chambers are coaxial and in open communication with each other. The combustion is provided with at least one tangential inlet through which a combustible mixture of fuel and oxidant is admitted to form a swirling body of hot combustion gas which travels in a generally helical path into and through the reaction chamber, thus providing a zone maintained at a carbon black forming temperature. A carbonaceous feed injected longitudinally and axially into the combustion chamber reacts to form carbon black. A furnace as above described is disclosed in United States Patent No. 2, 700 and is used to produce HAF (High Abrasion Furnace) types of carbon black. Fuel referred to herein includes any combustible hydrocarbon gas or vaporized hydrocarbon such as a vaporized hydrocarbon oil By combustion gases is meant such gases as result from the chemical reactions of burning under the particular circum-stances existing in the combustion zone. The combustion gases and the reactant hydrocarbon or "make" hydrocarbon pass through the combustion chamber and reaction chamber in a state of sufficient annular separation to prevent carbon deposition on the cylindrical walls thereof. The tangential ly added mixture is injected at sufficient velocity to flow spirally inward in the combustion chamber and substantially helically through the reaction chamber. These gases have sufficient centrifugal force to maintain a layer of the combustion gas adjacent the reaction chamber wall and accordingly prevent deposition of carbon upon this wall. The reactant hydrocarbon is converted or decomposed to carbon black by heat transferred to it by mixing at the interface between the hydrocarbon and the combustion gases and/or by radiation. The process is generally referred to as a tangential flame process of the precorabustion type.

Upon issuing from the reactor, the gaseous effluent carrying the carbon black is cooled, and the carbon black separated therefrom by any usual means old in the art, such as running the effluent through bags to screen out the carbon black, or by running the effluent through an electrical precipitator or through cyclone separators.

The tangential flame, precombustion type reactor described above is generally preferred for the production of HAF, ISAP and SAF types of furnace carbon black because of the excellence of product obtained; however, other types of reactors are utilized in the production of furnace carbon black, for example, FEF (Fast Extrusion Furnace) black is produced in a reactor, such as that shown in United States Patent No. 2,375,796.

In the production of furnace carbon blacks the operation is conducted so as to control certain specific properties of the carbon black produced such as surface area, structure, and pH. For example, surface area determined by adsorption of nitrogen is a particularly important property of carbon black and is one of the properties used in distinguishing among the various grades of carbon black produced. Thus as illustrative examples Fast Extrusion Furnace (FEF) black has a surface area of about square meters per gram as determined by nitrogen adsorption; High Abrasion Furnace (HAF) black has a surface area of about 76 square meters per gram; Intermediate Super Abrasion Furnace (ISAF) black has a surface area of about 108 square meters per gram; and Super Abrasion Furnace (SAF) black has a surface area of about 136 square meters per gram.

It has been determined that static pressure in the furnace black reactor section of a furnace black plant has a profound effect on the surface area of the carbon black produced. This effect can be controlled or reduced by manipulation of other process variables such as residence time and temperature by increasing or decreasing the volume of the reactor and by changing the ratio of air and gas admitted to the tangential ports of the precombustion chamber as well as varying the total throughput of materials through the reactor. It is not, however, always convenient or desirable to change these operating variables and under some conditions it has not been possible to control the sur ace area of the carbon black produced without extensive modification of the apparatus employed in producing the furnace carbon black. Furnace carbon black plants situated at various altitudes have required considerable differences in reactor dimensions in order to render the process compatible with the existing altitude.

Production of carbon black having a particle size larger than that of FEF black, such as GPF (General Purpose Furnace) black and having a surface area of about 2$ to 28, can be produced in an FEF reactor if the throughput and air- %e«oiI ratie are reduced! however thfs^operatlofi Is marginal because carbon tends to deposit in the reactor and grit resulting from the carbon deposits degrades the carbon black properties. At the present time HAF black is made in a long HAF reactor with low air rate, ISAF in a shorter HAF reactor at intermediate air rate; and SAF in a still shorter HAF reactor at high rates. The length of the reactor is determined by the position of the quench.

It is an object of this invention to provide a method for producing all grades of furnace carbon black in a single carbon black reactor. It is also an object of this invention to provide a method for producing large particle size carbon black at superatmospheric pressures. A further object of this invention is to provide a method for producing all of the various grades of furnace carbon black in a reactor of constant volume and at the same production rate.

According to the present invention there is provided a method for producing carbon black wherein a react-ant hydrocarbon fluid and an oxygen-containing gas are introduced into a carbon black furnace, maintaining said furnace at a carbon black forming temperature, and recovering carbon black therefrom, characterized by adjusting the static pressure within said furnace so as to produce carbon black having a desired surface area; and adjusting the re-actant feed rate to maintain a photelometer value of approximately 90.

All grades of carbon black can be made in one reactor having a constant volume by changing the pressure in the reactor and adjusting the ratio of the reactant fluid (oil) to oxygen-containing gas (air) so as to obtain a photelometer value of approximately 90. A photelometer value of about 85 or 95 is satisfactory. It has been found that any grade of carbon black having surface area values from about 2 to about 1 0 square meters can thus be produced in the same reactor at about the same production rate and thus it is no longer necessary to maintain different types of reactors to obtain different grades of furnace carbon black.

The surface area property of furnace black is particularly sensitive to pressure at pressures near atmospheric and often HAF, ISAP and SAP blacks can be made in the same furnace by merely adjusting the pressure with little or no change in the oil-to-air ratio; however, at the higher pressures needed to depress the surface area value to about 60 square meters per gram or lower, it is necessary to increase the oil-to-air ratio in order to obtain a photelometer value of about 90, The sole Figure illustrates a carbon black furnace for carrying out the process according to the invention.

The drawing illustrates a carbon black furnace of the tangential flame, precombustion type comprising an insulated shell 10 containing a precombustion chamber 11, a reactor section 12 and a quench section 13· Reactant feed, which can be oil, gas or a mixture of oil and gas, enters the precombustion chamber axially via conduit ll^ having therein a valve 1$. Air or a combustible mixture of gas and air is injected tangentially into the precombustion chamber 11 via conduits 16 and 17 having therein, respectively, valves 18 and 19. Reaction is terminated by a spray of water introduced into the reaction chamber 12 via conduit 21. A valve 22 is positioned in conduit 3 downstream from reactor 12 so as to maintain a desired static pressure in reactor 12. Conduit 23 exits into a carbon black recovery apparatus 2i which can be a filter device from which off-gases are removed via stack 25 and carbon black product is removed via conduit 26.

Pressure required for the oil feed is supplied by pump 27, pressure for the fuel gas is supplied by pump or compressor 28 and pressure for the air is supplied by pump or compressor 29.

The following example will be helpful in attaining an understanding of the invention. The example is intended to be illustrative of the invention and should not be con- strued as limiting the invention unduly.

EXAMPLE In a carbon black furnace as illustrated in the drawing, wherein the precombustion chamber is 12 inches in length and 37 inches in diameter and the reactor section is 12 inches in diameter, the quench is maintained 36 inches from the precombustion chamber 11 . The relationship of pressure, oil feed rate and surface area at a photelometer value of about 90 is shown in the following tabulation: TABLE Oil Feed Rate Surface Area Pressure Run No. Gal/hr. m2/g∞ psia 1 250 ikS 13 2 29 120 15 3 375 80 25 In the above runs the air rate is maintained constant at about 250 , 000 standard cubic feet per hour. The oil is 90 BMCI. About 16 , 700 cubic feet per hour of fuel gas is mixed with the air.

The test for photelometer value is described in United States Patent No. 3, 009 , 781;.

Although a tangential flame furnace has been described and illustrated, the invention is applicable to all types of carbon black furnaces.

Claims (1)

1. insufficientOCRQuality