A process and device separate off a volatile component from the off-gases in cement clinker production. Raw materials for cement clinker production are passed through a preheater with heat exchange with the off-gases and are then burnt in a rotary kiln. Owing to the heating in the preheater, the volatile component bound in the raw materials is vaporized and separated off. A first raw material stream having a relatively high concentration of the volatile component is applied to a first line of the preheater and a second raw material stream having a lower concentration of the volatile component is applied to a second line. The volatile component is separated off from the first substream of the off-gases. The first raw material stream heated to a temperature of at least 250 C. with the first substream of the off gases in the first line is combined with the second raw material stream.

To produce cement clinker by baking of raw meal in a kiln, use is conventionally made of a raw meal preheater in which the heat of the flue gas emerging from the kiln is transferred to the raw meal. In order to remove impurities which accumulate in circulation between the kiln and the raw meal preheater, a part of the flue gas is extracted from the kiln, bypassing the raw meal preheater. The heat generated during the baking of cement clinker can be used particularly efficiently if the flue gases extracted and diverted past the raw meal preheater are used in a boiler to generate hot steam which can subsequently be expanded in a turbine.

Systems and methods are provided for capturing CO.sub.2 from a combustion source using molten carbonate fuel cells (MCFCs). At least a portion of the anode exhaust can be recycled for use as a fuel for the combustion source. Optionally, a second portion of the anode exhaust can be recycled for use as part of an anode input stream. This can allow for a reduction in the amount of fuel cell area required for separating CO.sub.2 from the combustion source exhaust and/or modifications in how the fuel cells can be operated.

To provide a fractionating device capable of stably fractionating powders such as cement raw materials by a simple configuration. A fractionating device 1 for fractionating some of a powder (cement raw material) R falling in a chute (main body) 2, wherein the fractionating device is equipped with a screw conveyor 5 which passes through the chute, a part of a casing 5a opening inside the chute, and receives part of the powder from an opening (inlet) 5b, and a collision separation member (collision separation rod) 4 which is provided above the screw conveyor in the chute and collides with an object when an object of a predetermined size or larger falls, and prevents the object from falling directly onto the screw conveyor. A rotation shaft 5d of the screw conveyor may be inclined from 5 to 20 with respect to the horizontal plane so that the end of the discharge port side of the screw conveyor is positioned above the other end and may be equipped with a guide member 3 that guides the powder falling in the chute in the direction of the opening of the screw conveyor.

An accelerated carbonatation method including the following steps: a) providing recycled concrete granulates with a grain size smaller than or equal to a value V.sub.1 being between 1 mm and 6 mm, in other words a 0/V.sub.1 sand; b) performing on the 0/V.sub.1 sand a separation step by defining a granulometric cut of a determined value V.sub.2 being between 0.1 mm and 0.2 mm so as to obtain: a 1st fraction whose grain size is less than V.sub.2, and a 2nd fraction whose grain size is between V.sub.2 and V.sub.1; c) subjecting the 2nd fraction to an accelerated carbonatation step in a dynamic carbonator so as to obtain carbonated recycled concrete granulates. Also, a method for valorizing concrete wastes and industrial gaseous discharges implementing the accelerated carbonatation method, in particular the gaseous discharges of a cement plant.

In various aspects, systems and methods are provided for operating a molten carbonate fuel cell assembly at increased power density. This can be accomplished in part by performing an effective amount of an endothermic reaction within the fuel cell stack in an integrated manner. This can allow for increased power density while still maintaining a desired temperature differential within the fuel cell assembly.

Denitrifying bypass exhaust gases in a cement clinker producing plant. The plant comprises a rotary kiln connected to a calciner for the deacidification of raw material or to a rotary kiln riser shaft via a rotary kiln inlet chamber, and the bypass exhaust gas being drawn off in the region of the rotary kiln inlet chamber. The method comprises: cooling the bypass gas to between 260 C and 400 C in a cooling device, injecting an ammonia-, urea-, and/or ammonium-containing substance into the cooled bypass gas, introducing the cooled and mixed bypass gas into a ceramic filter system to filter out any halide and sulfate of the alkali metals and alkaline-earth metals precipitated during cooling the gas, and any nitrogen not reacted by the injected substances is chemically selectively reduced over a catalytic converter which is located in or directly downstream of the ceramic filter system.

Method for the purification of exhaust gas from the production of cement clinker in a rotary kiln, in which raw materials are ground in a mill to form raw meal, raw meal is preheated in countercurrent in a preheater with exhaust gas from the rotary kiln and optionally precalcined, preheated and optionally precalcined raw meal is supplied to the rotary kiln and burned in the rotary kiln to form cement, the exhaust gas from the rotary kiln is denitrified before entering the preheater of a selective non-catalytic nitrogen oxide reduction with a reagent which provides ammonia, and wherein, according to the invention, the exhaust gas from the preheater is subjected to gas conditioning and catalytic oxidation of ammonia. The object is further solved by means of a device for gas conditioning and catalytic oxidation which is arranged between the preheater and the mill.

In various embodiments, a process is described for the preparation of a concrete mixture in a Ready-mix or for an installation. A quantity of amorphous silica is added with an average particle size in the range of from about 1 to about 55 nanometers and/or wherein the surface area of the particles of the amorphous silica is in the range of from about 50 to about 900 m2/g. The amorphous silica may be added in colloidal form or otherwise, and is added at a particular stage to ensure efficacy.

A method and a corresponding plant for denitrifying bypass exhaust gases in a cement clinker production plant. Raw meal is sintered in a rotary kiln and deacidified in a calciner. A rotary kiln inlet chamber is connected to the calciner directly or by a riser duct. Bypass exhaust gas is drawn off near the inlet chamber. This exhaust gas is guided into a first mixing chamber, in which the exhaust gas is cooled to between 800 and 950 degrees C., then the exhaust gas is guided through a reaction pipeline segment, wherein the dwell time is between 0.5 and 3 seconds and ammonia, aqueous ammonia solution, or ammonia-releasing substances are injected for denitrification. Then the exhaust gas is guided into a second mixing chamber, in which the exhaust gas is cooled to between 150 250 degrees C. Then the exhaust gas is guided to a filter for dust removal.