Abstract: A method and plant for reducing mercury (Hg) and other metal emissions including injecting a chemical reagent into the process in such a way as to convert elemental mercury into a mercury compound that is more readily captured using normal particulate control equipment associated with kilns, smelters, furnaces, and boilers of cement plants and other industrial plants.
Abstract: A method of producing cement clinker including the steps of preheating raw meal comprising calcium carbonate in a preheating stage that is preheated by the exhaust gases of a sintering stage connected downstream in the direction of the gas flow, neutralizing the preheated raw meal, sintering the raw meal into cement clinker in a sintering stage, and cooling the cement clinker from the sintering stage in a cooling stage that cools the cement clinker with a gas. The exhaust gases of the sintering stage are combined with the exhaust gases of the neutralization, and the combined exhaust gases are conducted in an open gas circuit. The CO2 emissions are substantially reduced over known systems with CO separation, and the formation of nitrogen oxides by the combustion of atmospheric nitrogen in the oxidative environment of the sintering stage burner is almost completely prevented.
Abstract: The invention relates to a process and a plant for producing cement clinker and for purifying the off-gases formed thereby, wherein cement raw meal is preheated in a preheater by means of hot off-gases and then optionally precalcined, the preheated and optionally precalcined cement raw meal is burnt in a rotary kiln to form cement clinker, the cement clinker is cooled in a cooler, the hot off-gases used in the preheater are used in a raw mill for treating the cement raw meal, the dust content of a dust-containing mill off-gas thereby formed is reduced in a separating device to less than 5 g/Nm3, preferably less than 1 g/Nm3, alkali hydrogen carbonate and/or alkali carbonate is added to and mixed with the mill off-gas whose dust content has been reduced to less than 5 g/Nm3, and the mixed gas thereby formed is subsequently fed to a process filter for separation of dust laden with pollutants.
Abstract: The present invention relates to an apparatus and a method for the selective non-catalytic reduction (SNCR) of NOx in industrial cement production plants. In particular, the method according to the present invention provides for the atomization of an aqueous solution containing the reagent by introducing it into the gas to be treated that is at a high temperature, thus achieving the simultaneous and immediate evaporation of the water and gasification of the reagent. Thanks to this method, there is achieved improved performance of the non-catalytic reduction process of NOx while using the same reagent or, specularly, the same performance with a lesser amount of reagent being required, with consequent reduction of the costs.
Abstract: A system and method of using a double-effect-reactor to dispose incinerated flue gas and improve cement yields. The double-effect-reactor features an incinerated reaction chamber and a gas-solid suspension mixing chamber. The system includes the double-effect-reactor, a high temperature dust-arrester, a system for recovery of thermal energy and dust removal, a triple valve, and an independent chimney. Also disclosed is a method in which combines the double-effect-reactor with a cement production system.
Abstract: In accordance with the present invention, there is provide and device and method to facilitate the treatment of chlorine bypass dust while preventing increases in chemical cost and concentrations of heavy metals in clinker, and ensuring stability in quality of cement, and to treat chlorine bypass exhaust gas while avoiding coating troubles in a cement kiln etc., and preventing heat losses in a preheater etc., without degradation of clinker production amount.
Abstract: A process for the production of cement which includes the calcination of calcium carbonate-containing raw meal in a calciner heated by combustion of a carbon-containing fuel with a gas including oxygen and from 0 to 80% by volume of carbon dioxide, and substantially free of nitrogen, and isolating the gas produced by combustion and calcination in the calciner.
Abstract: A method and apparatus for reducing discharges into the atmosphere of mercury pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile mercury pollutants, such as elemental mercury and mercury oxides. Preferably, the feed meal is heated to a temperature of at least 175° C. The gases that are driven off flow are then cooled to condense the mercury pollutants causing them to be adsorbed on carbon particles injected into the gas flow. The carbon particles containing the condensed mercury pollutants are then filtered out of gas flow, for example, using a fabric filter. The gas flow may be burned to destroy other volatile pollutants such as hydrocarbons and/or ammonia.
Abstract: The present invention provides a method and an apparatus for treating a chlorine-containing waste, which can separate and recover a chlorine component from a chlorine-containing waste, and also can achieve a high chlorine removal thereby obtaining a high purity chlorine compound, and can decrease the amount of water for recovering chlorine.
October 16, 2006
Date of Patent:
November 1, 2011
Sumitomo Osaka Cement Co., Ltd., Japan Water Systems Corporation
Abstract: A cement kiln chlorine/sulfur bypass system wherein the equipment cost is suppressed and the sulfur included in a combustion gas bled from a cement kiln is separated and effectively utilized. The cement kiln chlorine/sulfur bypass system comprises an air bleed means for bleeding a kiln exhaust gas passage, which runs from the end of the cement kiln to a bottom cyclone, of a part of the combustion gas, a separating means for separating dust in the gas bled by the air bleed means into coarse particles and fine particles, and a wet dust collector for collecting dust from the gas containing the fine particles separated by the separating means. The separating means is preferably a classifier in which the cut size is changeable. The wet dust collector is preferably a mixing scrubber.
Abstract: A method to efficiently reduce lead content of cement without exerting influence upon quality of the cement. The method comprises the steps of: controlling O2 concentration of combustion gas in an inlet end of a cement kiln to 5% or lower and/or CO concentration thereof 1000 ppm or more; extracting a part of combustion gas from the cement kiln and collecting dust contained in the combustion gas; and collecting lead from the dust collected. With this, the area where raw material temperature in the cement kiln is between 800° and 1100° can be turned into reducing atmosphere to sharply increase volatilization rate of lead, and collection of lead from the dust allows lead content of cement to efficiently be reduced without exerting influence upon quality of the cement.
Abstract: A method and apparatus for reducing air pollutants associated with dry process, precalciner cement manufacturing is shown. Raw feed meal used in cement production is heated in a special heating chamber to drive off volatile compounds, such as organic materials and salts of ammonia. Preferably, the feed meal is heated to a temperature of at least 350° F. The gases that are driven off flow to the precalciner where they are combusted and rendered harmless. Heat is provided by diverting at least a portion of the exhaust gases from the cement pyroprocessing kiln to the special heater. The raw feed meal is indirectly heated using a heat exchange wall between the feed meal and the kiln exhaust gas flow. In addition, abase-containing material such as lime or precalcined feed meal, may be added to the raw feed before treatment meal to promote the breakdown of inorganic ammonium compounds, thereby releasing gaseous ammonia which is also destroyed upon subsequent combustion.
Abstract: A method for the production of cement clinker comprises the introduction of non-traditional materials into the kiln, preferably at a mid-kiln locations. The non-traditional materials are materials that are difficult, expensive or environmentally challenging for disposal. In one embodiment, weathered clinker is introduced into the kiln to admix with the raw material mix to augment clinker production. In another embodiment, bird, animal or human manure is added to the kiln so that gaseous reducing agents can be released by the manure and combine with certain noxious gases generated during the clinker production, to thereby reduce the noxious gas output. In other embodiments, other non-traditional waste-derived fuels are added to the kiln during clinker production, including railroad ties coated with creosote, industrial, commercial and consumer rubber components, such as rubber hoses, unshredded plastics, and organic materials, such as bird and animal meal.
Abstract: A process is disclosed for producing cement clinker, comprising the steps of: a) providing a mixture of ground calcareous materials and ground argillaceous materials; b) heating the mixture of step a) to a temperature sufficient to calcine and fuse the ground materials to form the cement clinker, and thereby producing an exhaust gas containing CO2; c) catalysing the hydration of at least a portion of the CO2 contained in the exhaust gas and producing a solution containing bicarbonate ions and hydrogen ions; and d) adding to the solution obtained in step c) metal ions, and adjusting the pH of the solution to precipitate a carbonate or said metal. Preferably, the metal ions are Ca++ obtained from the dissolution of a material selected from the group consisting of CaCl2, cement kiln dust and sea salts and the carbonate is CaCO3 which is advantageously recycled into the process by adding the CaCO3 to the mixture of step a). A cement plant for performing this process is also disclosed.
Abstract: A method and apparatus for heat treatment of fine-grained material. In order to reduce the nitrogen oxide content of the exhaust gas from the combustion zone, a region of the calcination zone is operated under reducing conditions and ammonia-containing additives are introduced into the calcination zone. In this case, at least the predominant proportion of the ammonia-containing additives is only added in a region of the calcination zone in which the secondary combustion of the combustion products which are formed in the section operated under reducing conditions but are not completely reacted out is largely concluded.
Abstract: In order to create a process for the economical production of cement clinker in a cement clinker production line with a raw meal preheater, a precalcination stage, a rotary tubular kiln and a clinker cooler, in which the total oxygen excess required for all firing points, i.e., the ratio of total oxygen to total fuel, also designated as &lgr; value, is to lie as low as possible, it is proposed according to the invention, to continuously measure the content of CO and/or (unburned) hydrocarbons and/or other combustion products in the exhaust gas path of the precalcination stage and, in dependence on this measurement value, to perform a regulating intervention on the amount of an oxidation agent and/or catalyst to be injected into the precalcination stage.
December 13, 2000
Date of Patent:
September 10, 2002
KHD Humboldt Wedag AG
Stepan Kuhnke, Carsten Eckert, Andreas Hand
Abstract: A method and an apparatus to reduce NOx emissions in the exhaust gas from installations that form NOx as a result of combustion processes, such as the production of cement clinker, in which the NOx decomposition occurs in the temperature range from approximately 450° C. to approximately 850° C. and in an oxidizing atmosphere with a fuel-air ratio (Lambda) approximately equal to 1.
October 22, 1998
Date of Patent:
October 2, 2001
Rheinkalk GmbH & Co. KG
Armin Fröhlich, Maria Regina Mönnig, Siegfried Happrich
Abstract: A method is provided for abating acidic contaminants, such as sulfur dioxide and hydrogen chloride, in exhaust gases while minimizing the formation of visible plumes of ammonium salts proximate to the outlet of the exhaust stack by injecting a spray of an alkaline liquid, such as sodium hydroxide or potassium hydroxide, into the contaminated exhaust gases wherein the pH of the alkaline liquid is high enough, i.e. greater than a pH of about 11, so that the acidic contaminants preferentially react with the alkaline liquid rather than the ammonia in the gases, thereby minimizing formation of visible plumes of ammonium salts.
Abstract: The invention relates to the production of cement clinker from cement raw material using a preheating zone, a calcination zone, a heating zone in which the calcined material is further heated whilst avoiding the formation of a molten phase, as well as a clinker burning zone and cooling zone from which part-quantities of the hot exhaust air are delivered as combustion air together with proportions of fuel to the clinker burning zone, the heating zone and the calcination zone. A reliable further heating while avoiding incrustations is achieved in the heating zone by constructing this zone in the manner of a flue stream reactor to which calcined material, fuel and combustion air are delivered in the lower end region of a rising first treatment zone at one point in each case and from which the heated material is precipitated essentially by the effect of gravity overlaid with centrifugal action.
January 28, 1998
Date of Patent:
February 29, 2000
Krupp Polysius AG
Wilfried Kreft, Martin Uhde, Wolfgang Rother
Abstract: The invention relates to the heat treatment of fine-grained material which is first of all preheated in a multi-stage cyclone preheater, then further heated in a calcination zone, next finally burnt in a kiln and then cooled. Preheated material and tertiary air are delivered to the reaction chamber of the calcination zone in order to maintain therein a reducing atmosphere for reduction of the NO.sub.X content in the kiln exhaust gases. For the purpose of good adjustability of the reaction temperature in the reaction chamber and for the purpose of a space-saving construction, the preheated material from the second-lowest preheating stage as well as tertiary air are introduced at the bottom into the reaction chamber and an adjustable part-quantity of the preheated material from the third-lowest preheating stage is introduced into an upper region of the calcination zone.
Abstract: Sulfur oxides are removed from a preheater waste gas stream by reacting the sulfur oxides with lime recovered from the off gas stream in a calcining furnace. The method is particularly adaptable for use in a cement manufacturing plant wherein the sulfur dioxides in the waste gases result from the combustion of fossil fuels used for process heat.
Abstract: A method and apparatus for controlling the temperature in a kiln in which cement clinker is manufactured. The temperature is controlled by controlling the fuel rate to the kiln. The fuel rate is adjusted according to a calculation that is made of the sulphur evaporation in the kiln, thereby obtaining a measure of the instantaneous temperature in the burning zone. The evaporation factor is calculated on the basis of measurements of the sulphur content in the cyclone material which passes to the kiln or a measurement of the sulphur content in the exit gases out of the kiln.
Abstract: The present invention relates to a method for dry desulfurizing flue gases from rotary cement kilns, for which additives suitable for binding SO.sub.2, such as quick lime and/or dry calcium hydroxide, are supplied to the kiln, the additive being introduced into a flue gas-carrying zone at the kiln head at a injection angle of 2.degree. to 12.degree. to the axis of the kiln and at an injection velocity of 20 to 80 m/sec.
Abstract: A method is described for manufacturing of normal as well as ultra-fine cement on the basis of cement materials, such as cement clinker, gypsum, slag, limestone, pozzolana, flyash etc. in a plant comprising at least a mill (1), a classifying separator (3), a separation cyclone (5) and a dust collector (7). By this method some of the dust-laden conveying gas which is extracted via the cyclone gas outlet duct (11) is diverted to and dedusted in the dust collector (7), and the dust from the dust collector (7) is utilized as the basis for ultra-fine cement, whereas the cyclone material from the material outlet (9) of the cyclone is utilized as normal cement. Hence it is possible to manufacture ultra-fine cement in existing grinding plants in a mechanically simple and operationally inexpensive way, while normal cement is simultaneously manufactured, without having any significant impact on the mill operation.
Abstract: Disclosed is a method and an apparatus for the heat treatment of lime sludge (CaCO.sub.3) to form burnt lime (CaO). In the method of the present invention a lime sludge feed is entrained in and thereafter dried in a gas flash dryer means to produce a dried lime sludge. The dried lime sludge is separated from the gases and thereafter is fed to a rotary kiln in which the dried lime sludge is converted to active burnt lime. In order to maintain the flow of gas in the flash dryer means at a predetermined velocity in order to entrain all the lime sludge feed in the gas flow, an adjustable portion of the separated gases are recycled through the flash dryer means.
Abstract: A bypass system is provided for a long cement kiln. The long cement kiln includes a cylindrical rotary vessel in which a kiln gas stream flows countercurrent to in-process mineral. The bypass system includes an annular bypass plenum, a port in the wall of the rotary vessel in gas flow communication with said plenum, and a draft tube for preventing passage of in-process mineral through said port. A blower fan induces flow of at least a portion of the kiln gas stream to form a bypass stream through the draft tube and the port and into the annular bypass plenum. The bypass system also includes an apparatus for mixing controlled amounts of ambient air with the bypass stream to cool the kiln gas bypass stream and to precipitate alkali fume in the kiln gas bypass stream before it passes through the draft tube and the port in the wall of the rotary vessel to reduce build up of condensed alkali inside the draft tube.
January 11, 1993
Date of Patent:
December 27, 1994
Ash Grove Cement Company, Cadence Environmental Energy, Inc.
Abstract: In a kiln plant for burning clinker from mineral raw materials, such as cement raw materials, and comprising a kiln (1), a precalciner (4), a preheater (6, 7, 8) and a flue gas filter (31), part of the kiln flue gases is diverted from the precalciner and the preheater via a bypass (20-30), the bypassed amount of flue gas being subjected to a preceding quenching in a chamber (21), humidified with water and cooled in a reactor (23), thereby causing the chlorides and alkalis in the bypassed gas to deposit upon dust particles which together with material dust in the gases are precipitated from the latter in a separator (25). The bypassed flue gas thus being almost purified of harmful compounds is then fed to the filter (31) or recirculated to the bypass in such manner that at least part of the precipitated compounds and material dust from the reactor (23) and the separator (25) is returned to the reactor for renewed treatment in same.