摘要:
In a generally known cement kiln plant which incorporates a preheater (1), a calciner (2) having a separation cyclone (3), a rotary kiln (4) and a clinker cooler (5), a decomposition chamber (10) is additionally installed for incineration of waste. Waste is introduced into the chamber at a location (12) and decomposed in the chamber by the heat from calcined raw meal which is conveyed to the chamber from the separation cyclone (3) of the calciner via a splitting gate (13) and a pipeline (14). Gaseous products are conveyed to the calciner (2) and burned there, whereas noncombustible by-products are discharged via an outlet (15) of the chamber (10). By utilizing the heat from preheated or calcined raw meal instead of, for example, hot exhaust gases to incinerate waste, any disturbance of the draught conditions of the cement kiln plant can be avoided, and the overall control of the calcining process is improved.
摘要:
In a kiln plant for burning mineral raw materials, e.g. cement raw materials, by means of nitrogen containing, solid fuel, e.g. coal, and which plant comprises a kiln (1), a material cooler (2) coupled after the kiln and a multistring, multistage preheater (18-27 and 18'-27') mounted before the kiln, the one string, the kiln string (18-27), being in direct connection with the kiln riser pipe (8) and the second string, the calcining string (18'-27'), being connected to a separate calcinator (4) to which combustion air is supplied in the form of spent cooler air through an inlet (7), an NO.sub.x -reducing zone is established in the kiln riser pipe (8) and a part of the kiln string from an inlet (13) for nitrogen containing solid fuel of a fuel duct (10) and an inlet (12) of a branch-off (14) for the supply of spent cooler air. The length of the NO.sub.x -reducing zone, the combustion in the zone of the supplied carbon containing fuel for reaction between nitrogen atoms (N) and the nitrogen oxide (NO) formed in the kiln for forming harmless nitrogen (N.sub.2) and the separation of non-combusted fuel with partially calcined raw materials from the kiln smoke gases in the cyclone stage (18), and the further treatment of said products in the calciner (4) where the combustion of the fuel supplied from the kiln riser pipe and having a reduced nitrogen content thus causing a reduction of the NO.sub.x -emission from the calciner string (18'-27'), ensure a high degree of reduction in the total NO.sub.x -emission from the plant.
摘要:
A cement clinker-producing plant has a suspension preheater (1,2,3), a calciner (4) united with a stationary reactor (6) and coolers (7,8). Air is blown up through the cooler (7) into the reactor (6) where a spouted bed, in which the clinker is burnt, is produced. The air flow is controlled so that only clinker particles which have grown to a certain size can fall through the air flow into the cooler (7).
摘要:
Described is a method as well as a plant for drying and comminution of moist, mineral raw materials, such as chalk, marl and clay, by which method the raw materials are dried and comminuted subject to simultaneous supply of hot gases in a drier crusher (8) from which the material is subsequently directed in suspended form to a separator (11) in which it is separated into a coarse fraction which is returned to the drier crusher (8) for further drying and comminution and into a fine fraction which is directed to the next stage of the process and where any hard material components such as flint, sand and marble are subjected to grinding in a separate grinding unit (16). The method and plant is peculiar in that a part quantity of the coarse fraction from the separator (11) is proportionately fed to the separate grinding unit (16) for the grinding of hard material components. Hence, it will be possible to substantially reduce the specific energy consumption and the CO2 emission from the kiln system due to the elimination of need prior to drying and comminution in the drier crusher to suspend the raw materials in water which must subsequently be removed. This is ascribable to the fact that the hard material components by the method according to this invention will be drained away from the circuit between the drier crusher and the separator A further advantage of the method according to this invention is the significant reduction achieved in the wear rate of the drier crusher and its energy consumption. Furthermore, it will be possible to produce a raw meal with excellent burning characteristics due to the reduction in the content of coarse silica particles in the raw meal, which in turn will reduce the NOx emission from the kiln.
摘要:
In a method and an apparatus for burning away organic components in raw phosphate, the burning taking place in two stages carried out in two reactors each having its separate air supply. A first suspension transport reactor (3) and a second reactor (5) are coupled in series via a separator (4), to which reactors combustion air (9), (11), preheated raw material (14), (15) and, if desired, fuel (8) are supplied separately. The reaction temperature in both reactors preferably lies in the range 700.degree.-850.degree. C. The majority of the organic components are burnt in the first stage which operates with a suspension having a density of 1-50 kg/m.sup.3. The remaining part of the organic components is burnt in the second stage which operates with a suspension density of 75-1600 kg/m.sup.3, a material retention time which is at least 4, preferably 10 times as long as the material retention time in the first stage, an air supply which is less than half the air supply for the first stage, and an oxygen percentage which is at least twice that of the first stage.
摘要:
A method of removing cadmium from raw phosphate material in an apparatus comprising a preheater section (2,13) a reactor section (3,4,5), a cooler section (7) and an exit gas cleaning section having a cadmium condenser (6,20,21), where the reactors (3,5) work in series and are formed as suspension reactors, or alternatively as a suspension reactor and a fluid-bed reactor, and where the treated raw phosphate in the first reactor having a short material retention time is suspended in a gas/fuel mixture and through a flash-process heated to a reaction temperature of 750.degree.-1050.degree. C. to be further heated subsequently in a reducing or neutral atmosphere in the second reactor which has a strongly reduced gas supply as compared with the first reactor and has at least three times as long a material retention time, by which the cadmium content is substantially expelled from the raw phosphate and carried away with the exit gas from the second reactor, while the cleaned phosphate is passed to the cooler section of the plant for further treatment.
摘要:
Raw phosphate material is calcined to remove pollutants, such as organic compounds and sulphides, by heat treatment in two suspension calciners (3,5) arranged in series. Fuel supplied at burners (8) is burnt in the calciners with air, supplied in parallel through pipes (9) from a cooler (7) for the treated material. The material is preheated in a preheater, for instance a pipe (13) and cyclone (2) by exit gases from the calciner before entering the calciners and, after leaving the calciners, is separated from the gas streams in separators (4,6).