Waste gas circulation method and system for sintering apparatus

Abstract

Herein disclosed are both waste gas circulation method and system for effectively recovering waste heat from an on-strand type sintering apparatus which has its sintering and cooling zones extending continuously along a horizontal strand. The hottest waste gases coming from the final stage of the sintering zone and the front stage of the cooling zone, in which the sintering reaction of a charge mixture is completed, are subjected to heat recovery, and sulfur oxides in the hottest gases are prevented from condensing on the water pipe or pipes of a waste-heat boiler by preheating the water, which is supplied for the heat recovery, with the still hot waste gases coming from the downstream half of the cooling zone. The heat of the still hot waste gases are exchanged with cold water so that this water may be heated into hot water. On the other hand, the heat of the hottest gases is exchanged with steam so that this steam may be heated into superheated steam. Moreover, the heat of the hot waste gases obtained as a result of the second-named heat exchanging step is further exchanged with the hot water heated at the first-named heat exchanging step. Thus, it is possible to conduct the ore sintering operation of regenerative type while assuring that the boiler components in those heat exchanging operations will not be corroded by the waste gases.