same conditions. A trndicional burner is replaced by two regeneracive one operating alcernately: one is used as a burner while ehe otlıer operaces as a chimney. Each eguipment is made ofa burner connected to a regenerator, made of piled refraccory pellecs. The flue gases flow through rhe "clıimney" burner, where heat is stored. Thcn, this burners swicches back as operating burner, and ehe combuscion air is prehearecl by ehe bot pellers. 3.METAL MELTING AND HOLDiNG From ehe rechnological evolucion for ehe last 20 years, one coulcl assume that tbe share of natura! gas in meral melring was clecreasing on behalf of elecrric power. But rhe trend is reversing, with new technologies in ehe ferrous and non ferrous melting and holding: *Beside their former advanrnges (low invescment cost, great versatility in operation), new natura! gas suppliecl furnaces can realize ebe melting of aluminium with nearly ehe same Flg.3 t - Glove Finger Recuperator DO�AL GAZ DERGİSİ SAYI. 29 98 specifıc consumpcion as wich an incluction furnace for an energy cosc 2 to 3 times lower. *Due to an evolution in clesign of ehe furnaces ancl heacing eguipmencs, ehe mernllurgical guality follows most ofup co el ate specifications reguirecl by cusromers. *At !ast, ehe emergence of incluscrial oxy-gas burners launcbecl ehe cast iron rocary furnace back in operation. 3-1. Ferroı.ıs Alloys whit ehe Rotating Kiln The rocating kiln, associatecl with an oxy-gas burner or a hot air-gas one, appears as a substitute to tbe traditional cupola for small ancl meclium size foundries and a çompetitor to electrical furnaces: irs specific consumpcion for mel ring ancl temperature buildup to 1450" C , clepending on irs size, is around 600 to 725 kWb (NCV)t. In chis furnace, shown on figure 3, tbe o x y-gas flame has a temperacure some 800° C ovcr ehe colcl air-gas flame and allows ehe manufacture of GS cast iron. Dming eheremperarure builciup, eheheat transfer by conveccion from ehe flue gases ancl by racliation from ehe wall is ,Lt irs best. When cast iron is liguicl, ehe rorntion begins, inclucing a heat transfer by concluction, which increases tlıe heacing efficiency. The dust cmissions are arouncl 300 mg/m·' at the begining ancl 120 mg/m1 at ehe enci of ehe heating operation, wbat is near ehe eclicted value of 1 5 0 mg/ml ancl are far lower tlıan those measurecl on a cupola wiclıout recainer (over 10,000 mg/m3). Available furnaces rnnge from 3 to8 merric cons ,tnd 10 to 1 2 rons will soon be pre;ented. Up ro now, some one lıundrecl such furnaces bave been solcl in wescern Europe, and 12 in France. Looking 3 or 4 years back, who coulcl have bet on this cechnology.
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