GB840504A - Process and apparatus for production of carbon black - Google Patents

Abstract

<PICT:0840504/III/1> A furnace, for the production of carbon black by the decomposition of a substantially linear stream of make hydrocarbon in a surrounding spiral stream of hot combustion gases, comprises in axial alignment a substantially cylindrical first reaction zone 21 which has a diameter greater than its length, a Venturi choke 36 of which the inlet and outlet have substantially the same diameter, the diameter of each being smaller than that of the first zone, and a substantially cylindrical second reaction zone 37 which forms a continuation of the Venturi choke and which has a length greater than its diameter, the minimum crosssectional area of the Venturi being 50-80% of that of the second zone and the length of the Venturi being 50-200% of the diameter of the second zone. The Venturi choke may be tapered outwards on the inlet side from a point at which the cross-sectional area is substantially that of said second zone to merge with the outlet wall of said first zone forming a curved surface having a radius of curvature of 0.05-0.5 times the radius of the second zone. The throat of the Venturi throat may be streamlined forming a curved surface having a radius of curvature of at least 0.2 times the radius of the second zone. A small quantity of cooling gas, e.g. air, hydrogen, carbon monoxide, carbon dioxide, methane, or a mixture of two or more of these gases, may be passed around the make hydrocarbon injection pipe 22 through a pipe 23. Pipe 22 may terminate in a nozzle (Figs. 7 and 8, not shown) having a plurality of orifices inclined from the axis by an angle of 10-50 degrees, preferably 15-45 degrees. The hot combustion gases may emerge from a pair of burners 29 comprising a closed ended hydrocarbon fuel pipe having a plurality of peripheral openings surrounded by a pipe for the supply of an oxygen-containing gas (Fig. 3, not shown). In some cases the supply of fuel may be eliminated. The make and fuel hydrocarbons may be as gas e.g. methane, ethane, propane, butane, or a mixture of two or more of these gases, or a liquid, e.g. a gas oil which is 80% vapour at 775 DEG F. The oxygen-containing gas may be air, oxygen-enriched air, or air diluted with combustion product gas. All or a portion of the make hydrocarbon, fuel hydrocarbon, and oxygen-containing gas may be preheated (Fig. 4, not shown). The carbon black produced may be quenched by spraying with water from nozzles 44 or may be cooled slowly by indirect heat exchange with the atmosphere through the walls of the discharge conduit. Tables are given specifying runs using liquid hydrocarbon which is 70% vaporized at 770 DEG C. as make hydrocarbon, natural gas as fuel hydrocarbon, and air as oxygen-containing gas, and the properties of the resulting carbon black.