| 摘要 |
<p>1531458 Utilizing waste heat in calcining process ASSOCIATED PORTLAND CEMENT MFRS Ltd 12 March 1976 [12 March 1975] 10303 /75 Heading F4B In a calcination process comprising an endothermic stage and an exothermic stage, at least part of the heat for the endothermic process is first partly used in a boiler, and part only of the heat for the endothermic stage is taken from the exothermic stage, the boiler being used for power generation and part of the heat being recovered from the endothermic stage. In a cement plant, Fig. 2, comprising a drying and preheating zone 1, a calciner 2, and a sintering kiln 3 followed by a eooler 4, air heated in the cooler 4 is supplied to the kiln at 112 to the calciner 3, and to a waste boiler 19. Fuel is fed to the kiln B and additional fuel and the gases from the kiln are fed to the calciner 2 at 120 and 13. Gases from the ealciner 2, mixed with the air from the cooler and fuel are fed to the waste heat boiler, and the drier 1 is supplied with exhaust gases from the boiler 19. The air fed to the cooler may be heated in a condenser for steam from the boiler 19. The waste heat boiler may receive only hot air from the cooler, and the waste gases from the boiler may be fed to the calciner (Fig. 1). The steam from the waste heat boiler is utilized in an electric power generating turbine, the spent steam and water from the turbine being used to heat air for the cooler, and to provide heat for mills, spray driers or other ancillary apparatus before being reheated and recycled (Figs. 4 and 5). The waste heat boiler 19, Fig. 3, receives hot gas through a duct 115, and the hot gases from the boiler are supplied to preheater 1. The steam from boiler 19 is fed to turbine 24, and may be superheated before reaching the turbine in a heat exchanger 35 in the preheater second stage 102. The effluent from the turbine passes to condenser 26 to heat air for the cooler and the first stage 101 of the preheater 1. The condensate is returned by a pump 31 through an economizer 32 in the preheater second stage 102 to a second pump 23.</p> |
