GB752262A - Thermal decomposition of sludges - Google Patents

Abstract

<PICT:0752262/III/1> In decomposing sludge resulting from the treatment of hydrocarbon oils with sulphuric acid or anhydride, into sulphur dioxide and coke by maintaining a continuously moving body of coke particles in continuous circulation in a closed cycle, indirectly heating the coke particles in the cycle, and adding sludge and intimately mixing it with the coke particles at the point of introduction to form an intimate mixture of sludge and coke, the mass of the coke particles at the point of mixing with the sludge is at least 5 times, preferably 15 times, the mass of the sludge, and the temperature of the coke particles is sufficient to produce a mixture with the sludge at least at the decomposition temperature of the sludge and not exceeding 500 DEG F., so that the slude is substantially immediately decomposed. The temperature of the mixture of sludge and coke particles should not exceed the decomposition temperature of the sludge by more than 50 DEG F., and is preferably 350-450 DEG F. sludge entering at 14 is mixed with hot coke particles, of size not more than 4 mesh, preferably 10 mesh, by mixer-conveyer 9 having paddles 10 radially mounted on driven shaft 12. 98 volume per cent sulphur dioxide is withdrawn from casing 8 through outlet 13. The coke particles at 300-400 DEG F., preferably 330 DEG F. pass through outlet 16 to casing 17 containing Archimedean screw on driven shaft 21, rotating at such a speed that the particles are thrown outwards by centrifugal force, and are lifted to duct 23. The particles are then conveyed by worm 1 through casing 3 to bank of vertical tubes 5 wherein they fall by gravity to hopper 7, while being indirectly heated by combustion gases from furnace 25 circulating in casing 27 round tubes 5. The combustion gases pass from casing 27 to casing 28 surrounding casing 17. The heated coke particles pass from hopper 7 back to mixer conveyor 9, and excess coke particles are withdrawn through outlet 6.