Abstract: Fine particulate solid fuel is utilized in the calcining or uniflow shaft of a uniflow regenerative shaft furnace having outlet openings of fuel lances of the furnace arranged with a uniform distribution over the cross-section of the furnace shaft in a horizontal plane between the preheating zone and the calcining zone of the furnace. The fuel feed is maintained constant with time by a dosing system through which fuel is supplied through feed lines to the fuel lances. Due to the uniform distribution of solid fuel which is accomplished, a calcined material is obtained which has a quality comparable to that which may be achieved through calcining with gaseous or liquid hydrocarbons.

Abstract: In a parallel flow regenerative shaft furnace having at least two furnace shafts and a transfer duct interconnecting the furnace shafts, limestone and similar mineral raw materials are calcined by operating the furnace shafts alternately, one as a calcining or parallel flow shaft and the other as a counterflow shaft, with burnt lime being discharged uncooled at the lower end of a calcining zone of the particular calcining shaft.

Abstract: Feed apparatus for a uniflow regenerative shaft furnace for the calcining of limestone and similar raw materials is formed with a feed container installed above each of the shafts of the furnace, each of the feed containers being arranged concentrically with the shaft axis of the respective shaft over which it is installed and constructed to be maintained in rotation during filling thereof of the material to be calcined.

Abstract: In a shaft furnace for burning limestone or similar raw materials, gaseous, liquid or solid fuels are supplied through fuel supply pipes to the burning zone of a furnace shaft. To permit the simultaneous supply of at least two different fuels, the fuel supply pipes are arranged as multiple fuel lances. The fuel lances extend inwardly from the shaft furnace wall through the preheating zone into the first part of the burning zone. The fuel lance is a double tube member made up of an inner tube laterally enclosed by an outer tube forming an inner fuel supply passageway and an outer annular fuel supply passageway. Two separate fuels can be introduced into the burning zone, one flowing through the inner passageway and the other through the outer annular passageway. The two different fuels can be supplied in varying proportions without any changeover operations.

Abstract: A calcining kiln for burning limestone or similar mineral raw material is formed with a wall structure which is gas-permeable at least in a region adjacent the openings of burners extending to the interior of the kiln with a compressed gaseous medium being supplied through the gas-permeable wall structure toward the interior of the kiln.

Abstract: A regenerative shaft furnace for burning carbonate-containing raw materials is disclosed having two or more shafts which are interconnected by ducts which operate in an alternate manner and wherein the burned raw material is cooled in the cooling zone of the shafts. Having a displacer in the cooling zone to prevent the reabsorption of carbon dioxide in the fuel gases by the burned material. A method for burning carbonate-containing raw material is also disclosed.

Abstract: Either sulphur-containing raw materials or sulphur-containing fuels may be used in the calcination of mineral raw materials in a calcining furnace, with significant desulphurization of the calcined material being achieved if, on the one hand, cooling air introduced into the cooling zone of the furnace is removed at the upper end of the cooling zone thereof through exhaust ducts and if, on the other hand, the flue gases are free of oxygen and have a carbon monoxide content of 1 to 5% by volume. In order to obtain this composition of the flue gases, the combustion process can either be performed in the calcining zone of the calcining shaft of the furnace with a deficiency of air or a gaseous, liquid or solid fuel can be supplied by means of fuel tubes located at a transfer duct between the furnace shafts.

Abstract: Coking of liquid fuel supplied through a fuel lance in a calcining furnace is prevented by surrounding a fuel tube in the fuel lance with a tubular jacket forming an annular gap between the jacket and the fuel tube for supplying a cooling medium through the lance. The jacket may be additionally provided with insulation which can be protected from damage caused by downwardly traveling bulk material by the additional provision of a protective tube.