Abstract: A method of producing cement from raw material containing a harmful substance such as sulphur, alkali and/or chlorine. In order to reduce the circulation of harmful substances a proportion of the gas or material stream is extracted from a zone in the cyclone preheater at which the desired reduction in the content of the harmful substance is achieved with minimum heat loss.

Abstract: The invention relates to a process and an installation for the heat-treatment of fine-grained material. Before the material is introduced into a precalcination zone, waste air from a cooling zone is divided into two component streams into which partial quantities of material coming from the two preheating zones are introduced. Separately measurable quantities of fuel are added to these two component streams before they are combined with one another. In this way, the material is maximally deacidified in the precalcination zone before it is introduced into the calcining zone without any danger of deposits being formed in the precalcination zone.

Abstract: The invention relates to a method of burning, calcining or sintering fine-grain material in which the burnt material separated from the gas flow is supplied to a residence container from which a part of the material is returned to the burning zone and the remainder of the material is supplied to the cooling zone. Such a method is distinguished by a low heat and energy requirement and by a simple construction of the apparatus and permits ideal adaptation of the burning conditions to the particular material.

Abstract: A process for the heat-treatment of fine-grained material which is preheated in a cyclone preheater, deacidified by additional fuel in a precalcination zone, and subsequently calcined to completion in a revolving tubular kiln. The gas temperature in the cyclone preheater and the material temperature after passage through the precalcination zone are measured, the difference between these temperatures is determined and, when the temperature difference reaches a maximum or minimum value, regulation of the fuel supply to the precalcination zone is switched to manual operation. In this way, the amount of fuel is rapidly adapted to the particular circumstances prevailing in the event of disturbances.

Abstract: A process for the heat-treatment of fine-grained material using a multistage cyclone preheater and a revolving tubular kiln, additional fuel being introduced into a stage of the preheater which is selected according to the grain size, reactivity, moisture content, and incombustible constituent content of the fuel so that most of the fuel is almost completely burnt in the lowermost stage of the preheater. In this way, it is possible to obtain a high degree of calcination of the material before it enters the revolving tubular kiln with low preparation costs.

Abstract: Processes and apparatus for the heat treatment of fine-grained material, particularly for the production of cement, wherein the material is preheated in a preheater, further heated in a precalcination zone using additional fuel, calcined to completion in a rotary kiln, and cooled in a cooler, the preheated material being introduced into a cooling air stream run off from the cooler and the resulting mixture of gas and solids being introduced from the side into a gas pipe which connects the rotary kiln to the preheater and through which the kiln exhaust gases flow in the upward direction.

Abstract: The invention relates to a shaft-type countercurrent heat exchanger in which the uppermost part of the shaft is formed by a turbulence chamber which communicates with the underlying countercurrent chamber of the shaft through a central material outlet and several gas pipes opening tangentially into the turbulence chamber, thereby improving the thermal efficiency of the heat exchanger.

Abstract: A process for producing cement wherein preheated, partially calcined powder-form raw material is finally calcined in a fluidized bed and is discharged to a cooler through which a cooling stream of air passes. A part of the cooling air passes into the fluidized bed from below and another part of the cooling air, together with the partially calcined material, passes into the fluidized bed from the side. The rates of material flow to and from the fluidized bed is regulated to maintain a substantially uniform intersticial ratio between the upper and lower regions of the fluidized bed.

Abstract: Fine solid material is preheated in a first zone, then heated to the final treatment temperature by passing it through a flame in a second zone, and then separated in a third zone from the hot exhaust gases leaving the second zone. The separated exhaust gases are led to the first zone for preheating the material. A fuel feed stock is gasified to produce a combustible gas, and such gas is burned in the second zone to produce said flame.

Abstract: Fine grained material such as raw cement meal is preheated in a preheater and discharged from the latter into a rotary kiln for calcining and through which hot exhaust gases pass in counterflow to the material. Immediately after introduction of the material to the kiln fuel is sprayed onto the surface of the material and is covered either by additional material from the preheater or by circulation of the material already in the kiln, due to rotation of the kiln at an elevated speed. The fuel is combusted virtually entirely within the kiln and substantially directly at the material without previous gasification of the fuel.

Abstract: Fine-grained material such as raw ground cement adapted to be fired in a rotary tube furnace is introduced to a vertical preheater and falls through a heating zone located at a level below the level at which the material enters the preheater. A stream of air enters the preheater at a level below the heating zone and passes upwardly at sufficient velocity to entrain the material that has passed through the heating zone, thereby causing such material to pass again through the heating zone. From the preheater the material is delivered to the furnace for final firing.

Abstract: Fine grained material such as ground raw cement is delivered in a stream from a preheater to an upright gas conduit through which furnace exhaust gases flow to the preheater. In different cross-sectional areas of the conduit the velocity of the gas differs. The stream of material falls upon a distributor in the conduit to distribute the material over the cross-sectional area of the conduit. The distributed material falls through a combustion zone and a substantial fraction of such material is entrained by the exhaust gas and passes again through the combustion zone enroute to the preheater. The distributor is adjustable to enable the concentration of material in different cross-sectional areas of the conduit to vary according to differences in the gas velocities in such cross-sectional areas.

Abstract: A chamber which forms a material inlet and an exhaust gas outlet at one end of a rotary kiln has an inclined bottom arranged to cause preheated fine material deposited thereon to slide by gravity into the end of the rotary kiln. A dense stream of fine granular material is deposited on such inclined surface, and fuel in finely divided form is introduced into the dense stream of material flowing down the inclined surface to cause the fuel to become intimately mixed with the material. Gas is discharged from the kiln in contact with the stream of material as such a velocity as to entrain a substantial proportion of such stream, the temperature and composition of the gas being such as to cause combustion of the fuel mixed with the entrained material.

Abstract: Fine-grained material such as raw ground cement adapted to be fired in a rotary tube furnace is introduced to a vertical perheater and falls through a heating zone located at a level below the level at which the material enters the preheater. A stream of air enters the preheater at a level below the heating zone and passes upwardly at sufficient velocity to entrain the material that has passed through the heating zone, thereby causing such material to pass again through the heating zone. From the preheater the material is delivered to the furnace for final firing.