Calcining limestone and similar carbonate stone - in ring shaft furnace where combustion chambers are fed with both fuel and waste, esp. used tyres

摘要

Furnace includes combustion chambers into which solid, crushed waste forming gases and rich in energy is fed. The waste is decomposed in the combustion chambers in the absence of the limestone charge; and the decompsn. prods. of the waste are then fed sideways into the limestone charge. Any variation in the heat content of the waste to pref. counterbalanced by the addn. of known amts. of conventional fuels; and additional burners may be used to decompose the waste; and/or the waste may be decomposed with a reduced amt. of air. A conc. stream of gas may be employed to remove incombustible residues obtd. from the waste and a ring shaft furnace is pref. used for the process. Waste with a high fuel content can be used e.g. old tyres, plastics, wood shavings, paper etc. Complicated decomposition appts. is not required.