A rotary kiln includes: a heating tube; a material feeding unit disposed on a first end of the heating tube; a material collection unit disposed on a second end of the heating tube; an inner cylinder supported at the second end of the heating tube with the inner cylinder being inserted in a central portion of the heating tube; a plurality of branch tubes disposed circumferentially on an outer circumferential surface of the inner cylinder, each of the branch tubes branching from the inner cylinder and extending in an axial direction along an inner circumferential surface of the heating tube; a hot air supply tube supported to be relatively rotatable with respect to the inner cylinder with the hot air supply tube being inserted in one end of the inner cylinder that extends outside the heating tube; and a drive mechanism that rotates the heating tube.

Method of operating a long direct-fired inclined counterflow rotary kiln for the thermal treatment of material and counterflow rotary kiln adapted for same, whereby material to be treated is introduced into the kiln at the inlet end and treated material is evacuated from the kiln at the outlet end, whereby a main combustion zone extends inside the kiln over a distance of ¼ to ⅓ of the internal length L.sub.int of the kiln, whereby a supplementary combustion zone in which supplementary combustion takes place with an oxygen-rich oxidant extends inside the kiln over a distance from the inlet end of at most ¼ of the internal length L.sub.int, and whereby no combustion takes place in a heat exchange zone located between the main combustion zone and the supplementary combustion zone.

Method of operating a long direct-fired inclined counterflow rotary kiln for the thermal treatment of material and counterflow rotary kiln adapted for same, whereby material to be treated is introduced into the kiln at the inlet end and treated material is evacuated from the kiln at the outlet end, whereby a main combustion zone extends inside the kiln over a distance of ¼ to ⅓ of the internal length L.sub.int of the kiln, whereby a supplementary combustion zone in which supplementary combustion takes place with an oxygen-rich oxidant extends inside the kiln over a distance from the inlet end of at most ¼ of the internal length L.sub.int, and whereby no combustion takes place in a heat exchange zone located between the main combustion zone and the supplementary combustion zone.

Disclosed is a method for producing sintered material from organic raw materials, implemented in an apparatus comprising, a cyclone preheater, a rotary furnace and a grate cooler, and in which the raw materials are preheated in the cyclone preheater, the preheated material is calcined and sintered in the rotary furnace, and the calcined materials are cooled by blowing cooling air in the grate cooler, producing hot air. The hot air is separated into three upstream-to-downstream fractions, the three hot air fractions being at decreasing temperatures. The first air fraction acts as combustion air in at least the combustion zone of the rotary furnace and/or of the potential precalciner of the apparatus. The second air fraction is greater than the combustion air needs to produce energy. The third air fraction is directed at least in part to the combustion zone of the apparatus, providing combustion air with the first air fraction.

Disclosed is a method for producing sintered material from organic raw materials, implemented in an apparatus comprising, a cyclone preheater, a rotary furnace and a grate cooler, and in which the raw materials are preheated in the cyclone preheater, the preheated material is calcined and sintered in the rotary furnace, and the calcined materials are cooled by blowing cooling air in the grate cooler, producing hot air. The hot air is separated into three upstream-to-downstream fractions, the three hot air fractions being at decreasing temperatures. The first air fraction acts as combustion air in at least the combustion zone of the rotary furnace and/or of the potential precalciner of the apparatus. The second air fraction is greater than the combustion air needs to produce energy. The third air fraction is directed at least in part to the combustion zone of the apparatus, providing combustion air with the first air fraction.

A rotary kiln includes a stationary fuel nozzle and a perforated flame holder positioned within an inclined rotating shell. The flame holder includes a plurality of perforations that collectively confine a combustion reaction of the burner to the flame holder to shift most heat transfer from the combustion reaction from radiation heat transfer to convective heat transfer.

A rotary kiln includes a stationary fuel nozzle and a perforated flame holder positioned within an inclined rotating shell. The flame holder includes a plurality of perforations that collectively confine a combustion reaction of the burner to the flame holder to shift most heat transfer from the combustion reaction from radiation heat transfer to convective heat transfer.

The present invention relates to a method and apparatus for producing reduced iron from ironmaking dust which contains iron oxide which is generated at an ironmaking plant, takes note of the rotary kiln reduction method which does not require pretreatment of the dust, and has as its problem the pursuit of facilities which achieve further improvement of heat efficiency and stable operation.

To solve this problem, the present invention is characterized by heating and reducing carbon-containing shaped materials in a single closed space in which an internal heat type rotary kiln and an external heat type rotary kiln are arranged in series and including at least the insides of the two rotary kilns during which making the reduced exhaust gas which is generated at the external heat type rotary kiln burn inside of the internal heat type rotary kiln.

The present invention relates to a method and apparatus for producing reduced iron from ironmaking dust which contains iron oxide which is generated at an ironmaking plant, takes note of the rotary kiln reduction method which does not require pretreatment of the dust, and has as its problem the pursuit of facilities which achieve further improvement of heat efficiency and stable operation.

To solve this problem, the present invention is characterized by heating and reducing carbon-containing shaped materials in a single closed space in which an internal heat type rotary kiln and an external heat type rotary kiln are arranged in series and including at least the insides of the two rotary kilns during which making the reduced exhaust gas which is generated at the external heat type rotary kiln burn inside of the internal heat type rotary kiln.

Provided is a system for enhancing combustion in a kiln, including a kiln combustion chamber disposed within the kiln, the kiln combustion chamber having an atmosphere therein; a main burner for heating the atmosphere; a calciner assembly for providing a substance to be heated into the kiln combustion chamber; a precalciner including a precalciner combustion chamber disposed within the precalciner for receiving a biomass fuel for combustion in the precalciner combustion chamber, the precalciner combustion chamber in communication with the kiln combustion chamber; and a precalciner oxygen injector in fluid communication with the precalciner combustion chamber for providing a first oxygen stream into the biomass fuel for the combustion. A related apparatus and method for enhancing combustion with oxygen and biomass fuel are also provided.