F. L. Smidth & Co.

Soren Bent Christiansen

A kiln plant for burning a pulverous material such as cement, which includes a preheater string for preheating raw material and a precalciner for receiving preheated raw material, the precalciner being fired with solid fuel, and a disintegrator provided adjacent the precalciner. Within the disintegrator the solid fuel, preferably coal, is crushed and mixed with a portion of the preheated raw material before passage into the precalciner. The invention also relates to a unique method for firing in the precalcining zone of the invention kiln plant.

Method and apparatus for operating a kiln plant with solid fuel firing

A method is disclosed for heat treating pulverulent or granular raw material such as cement meal. Raw material is directed to at least two multi-stage preheater strings, the first string communicating with the kiln by a smoke riser pipe and the second string having a calciner positioned at its lower end portion. The raw material directed to the first preheater string is divided into two divisional flows with the first divisional flow comprising substantially the maximum amount of material which can be substantially completely calcined by hot gases exiting the kiln. The first divisional flow of raw material is directed toward the upper material inlet end portion of the kiln so as to be entrained by the hot gases exiting the kiln, and the hot kiln gases and entrained material are directed to the first preheater string. The second divisional flow is directed to the second preheater string where it is calcined either alone or with raw material directed to the second string. The substantially completely calcined material exiting the first preheater string and at least partially calcined raw material exiting the second preheater string are directed to the upper material inlet end portion of the kiln at a location and in a manner so as to avoid entrainment by the hot exit gases and pass down through the kiln for further heat treatment. A plant is disclosed for practicing the inventive method.

Method of heat treating pulverulent or granular raw materials and kiln

A method is disclosed for heat treating granular or pulverulent raw material wherein the raw material is directed to a heat exchanger having at least two preheating units operating in parallel, each preheating unit having at least a first preheating stage and at least a lowermost calcination stage to effect a preheating and at least partial calcination of the material. The preheated, at least partially calcined material is fed from the heat exchanger into a kiln and undergoes a sintering process in the kiln. The sintered material is directed from the kiln into a cooling means in which cooling air is directed in a manner to effect a heat exchange between the material and the cooling air. The method further comprises dividing the heated cooling air exiting the cooling means and directing a portion of the heated cooling air to at least one of the calcination stages of the heat exchanger and directing a portion thereof to the kiln in excess of that required to support combustion of fuel in the kiln for the sintering process thereby intensifying the effectiveness of a material cooling zone within the kiln proper. Hot kiln exit gases are directed to at least one of the calcination stages and fuel is directed to at least one of the calcination stages to support combustion with preheated cooling air to provide supplementary heating of the material and at least partially calcining of the preheated material. An apparatus for practicing the inventive method is also disclosed.

Method of burning granular or pulverulent raw material and kiln plant

A method is disclosed for heat treating a preheated pulverous raw material containing at least a portion of lime to produce a partial calcination prior to passing the raw material down through an inclined rotary kiln for further heat treatment. Partial calcining is accomplished by introducing into at least one end of a rotary kiln an amount of fuel sufficient for preheating, at least partially calcining, and substantially completely sintering the raw material, at least part of the fuel being introduced into the lower material outlet end portion of the kiln. An amount of oxygen containing gas sufficient for substantial combustion of the fuel introduced into the kiln is introduced into the lower end portion of the kiln, and preheated raw material is introduced into the mouth of the kiln in such a manner that the material is entrained in gases exiting from the kiln mouth. The gas and entrained material exiting from the kiln are directed into a calcination chamber communicating with the upper material inlet end portion of the kiln such that the material is at least partially calcined by the contact with the kiln exit gases. The material is thereafter separated from the kiln exit gases and reintroduced into the upper end of the kiln in a manner which permits it to pass through the kiln for further heat treatment while avoiding entrainment in the kiln exit gases. A rotary kiln plant for practicing the method is also disclosed which provides for at least partial calcining of the material initially introduced into the kiln and thereafter reintroducing the partially calcined material in such a manner as to promote passage down through the kiln for further heat treatment.

Method of burning calcined and uncalcined pulverous raw material and

Improvements relating to cement manufacture wherein a unique method and a plant for practicing the method are disclosed for removing at least a portion of gaseous compounds containing alkalis, chlorine or sulphur from the exit gases of a rotary kiln in which cement raw meal is burnt to cement clinker with a view to subsequent cement manufacture. The method comprises the steps of dividing the hot exit gases from the rotary kiln into a main gas flow and a separate divisional flow and directing the main flow through a suspension preheater for preheating cement raw meal prior to feeding the raw meal into the kiln. A plurality of individual relatively cool solid condensation bodies are directed to pass through the divisional flow under the influence of gravity to permit the alkalis, chlorine or sulphur to condense on the surface of the bodies and the condensed compounds are removed from the bodies for redirecting them into the separate divisional flow. Prior to redirecting the bodies into the divisional flow they may be advantageously cooled to thereby permit lowering of the temperature of the gas flow. A plant is disclosed for practicing the method.

Cement manufacture

A method and apparatus is disclosed for burning pulverous or granular material, particularly cement raw material to cement clinker. Burning of the pulverous material is accomplished in a plant which includes a suspension preheater, a rotary kiln and a separate rotary cooler unit having an inlet end and an outlet end, for cooling the burnt material exiting from the kiln by means of air which is subsequently used for combustion and preheating purposes. The method comprises dividing the heated cooling air into at least two streams, directing the divided heat cooling air out of both ends of the rotary cooler unit in its divided streams, directing at least one stream to the rotary kiln to be used as combustion air, directing exhaust gases from the rotary kiln to the preheater to preheat the material, and directing the other stream of heated cooling air to the preheater to preheat the material prior to being burnt in the rotary kiln.

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Copenhagen, Denmark

Soren Bent Christiansen