PRINCIPLES OF IMPROVING HEAT TRANSFER WITH AN EXTREMELY COARSE MIXTURE IN CYCLONES

Abstract

Experimental evidence is given for improving the thermal preparation between furnace gases and extremely coarse cement raw mix (90 microns 50% residue on a sieve) in cyclone heat exchangers in comparison with the thermal preparation of traditional finely ground raw mix (90 microns 14% residue on a sieve). The extremely coarse mixture makes it possible, when heated in cyclones above 200 ° C, to reduce the reactivated surface energy of the fired material and, thus, reduce its tendency to aggregation. The energy consumption for displacement of adsorption H₂O at 200 °C for an extremely coarse mixture is 10-25% less than for a conventional finely ground mixture. For heating up to 80% of the gas flow temperature, the heating time of the free-floating grain is <0.2-1 s. In fact, the passage time of a usually thin mixture through cyclones is 25-32 seconds and is caused by the massive formation of aggregates and limited heat transfer. The degree of decarbonization of an extremely coarse mixture after cyclones increases by 10%.