Processes and plants for producing cement clinker, wherein no recirculation of preheater exhaust gases occurs and the ratio of solid fed in to exhaust gas in the preheater is set to greater than 1.0 kg of solid to gas.

In a method for reducing the NOx emissions of a rotary kiln of a clinker production plant, fuel supplied through a burner of the rotary kiln is burned along with primary air fed through the burner, wherein the primary air has a lower oxygen content and the primary air has an oxygen content reduced relative to that of the ambient air and a temperature increased relative to that of the ambient air, and the primary air is obtained by mixing ambient air with exhaust gas from the rotary kiln or from a heat exchanger connected to the rotary kiln and used for preheating raw meal. The primary air is further obtained by mixing with hot air, in particular waste air from a clinker cooler.

A plant for production of cement clinker from raw meal, having a calciner for deacidification of the raw meal and a rotary furnace for sintering the deacidified raw meal to give cement clinker. The deacidified raw meal flows through a cyclone preheating stage into the rotary furnace. A reactor is provided upstream of the calciner on the flow path of the rotary furnace offgas to the calciner, to which an inlet for the rotary furnace offgas leads. A corresponding method of operating such a plant wherein fuel is added to the reactor in a superstoichiometric amount in relation to the residence time of the offgases in the reactor, such that carbon dioxide present in the offgases is reduced to carbon monoxide. At least one input air conduit for supplying input air, preferably coming from a tertiary air conduit, is provided at at least one point in the reactor.

In a method for reducing the NOx emissions of a rotary kiln of a clinker production plant, fuel supplied through a burner of the rotary kiln is burned along with primary air fed through the burner, wherein the primary air has a lower oxygen content and the primary air has an oxygen content reduced relative to that of the ambient air and a temperature increased relative to that of the ambient air, and the primary air is obtained by mixing ambient air with exhaust gas from the rotary kiln or from a heat exchanger connected to the rotary kiln and used for preheating raw meal. The primary air is further obtained by mixing with hot air, in particular waste air from a clinker cooler.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.

A cement production apparatus having: a duct 21 in which exhaust gas drained from a lower cyclone flows upward, distributes and introduces the exhaust gas to upper cyclones; material-supplying pipes 22 for supplying cement raw material connected to both side parts of one side surface of the duct 21 below a distribution part 23 among the upper cyclones; and a supply-amount controller 26 provided on an upstream position above the material-supplying pipes 22 for controlling supply-amounts of the cement raw material to the material-supplying pipes 22: and when H is a vertical distance between a horizontal surface P1 passing through centers of distribution outlets 21a of the upper cyclones and a horizontal surface P2 passing through centers of connecting ports 22a of the material-supplying pipes 22, and D is a diameter of the duct 21, a ratio H/D is set to 1.4 to 2.5.

Methods and apparatus for reducing the content of controlled acidic pollutants in clinker kiln emissions are disclosed. The methods and apparatus include introducing bypass dust produced during production of clinker into one or more locations between the preheater exhaust and the inlet to a dust filter including into a gas conditioning tower. Total bypass dust separated from the kiln exhaust gas may be used. The bypass dust can be separated into a fine and coarse portions. Fine or total bypass dust can be mixed with water to form a bypass dust slurry that can be introduced into the gas conditioning tower. Bypass dust can be used to reduce the content of acidic pollutants such as hydrogen chloride HCl and sulfur oxides SO.sub.x from clinker kiln emissions.