GB977622A - Carbon black - Google Patents

Abstract

<PICT:0977622/C1/1> <PICT:0977622/C1/2> <PICT:0977622/C1/3> Carbon black is produced by introducing hydrocarbons and air into the lower end of a furnace having an upper end provided with a restricted opening, partially combusting the hydrocarbons in a combustion zone in said furnace so that the resultant gases pass upwards from said combustion zone through a cracking zone, to and through a hood in said furnace and adjusting the height of the hood so as to vary the volume of the cracking zone according to the desired carbon black particle size, withdrawing the combustion gases through the restricted opening and separating the carbon black from the gases. The temperature of the combustion zone may be 1800-2400 DEG F., of the cracking zone 2200 DEG -2600 DEG F. and in the hood 2600-3000 DEG F. The furnace 10 (see Fig. 2) has a burner 100 having a semi-cylindrical upper section 101 provided with a plurality of spaced parts 125, a semi-cylindrical lower section 102 and conduits extending into the burner through the lower section for introducing gases. The upper section 101 which has a greater radius of curvature than the lower has spaced parts 125 distributed over the whole surface except along the longitudinal side edge portions extending upwardly 5 degrees from the edges. Each of the parts has a straight bore portion 126 (see Fig. 5), whose diameter is preferably 8/10 th the thickness of the plates forming the upper section and whose length is 2/10 th the thickness. The upper flared portion 127 of each bore preferably has a radius of curvature which is 6/10 th the thickness of the plate. The hood is adjusted by winches 91 which are driven by an electric motor 90. A scraper blade 130 is mounted in the burner to remove any deposited carbon black. Liquid hydrocarbons, e.g. oil may be introduced through spray heads 175 supplied by inlets 176. In use the furnace is first preheated to 1800-2400 DEG F. by natural gas. Usually the ratio of air to gas is between 4 to 1 and 8 to 1. As the hood is raised, the size of the particles of carbon black increases. The mixture of carbon black and gases from the furnace 10 (see Fig. 1) is cooled in primary cooler 13 and then moved by fans 14 and 15 to cyclones 16 and secondary cooler 18. The carbon is separated and collected in bins 20 and 24 and the gases exhausted to the atmosphere. The carbon may be pulverized and pelletized and then conveyed to a sizing shaker screen 30, rejected pellets being moved by the blower 32 back to pelletizer 28.