Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
  • F27B7/20—Details, accessories or equipment specially adapted for rotary-drum furnaces
  • F27B7/2016—Arrangements of preheating devices for the charge
  • F27B7/2025—Arrangements of preheating devices for the charge consisting of a single string of cyclones
  • F27B7/2033—Arrangements of preheating devices for the charge consisting of a single string of cyclones with means for precalcining the raw material
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B7/00—Hydraulic cements
  • C04B7/36—Manufacture of hydraulic cements in general
  • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
  • C04B7/432—Preheating without addition of fuel

Definitions

• the present invention relates to a plant for manufacturing cement clinker comprising a preheater for preheating cement raw meal by contact with hot gases which preheater comprises a number of cyclone stages which are connected in series via gas ducts, a heat treatment unit which comprises at least one inlet opening for introducing preheated raw meal from at least one preheater cyclone in a selected cyclone stage, where a gas outlet of said at least one preheater cyclone in the selected cyclone stage in a vertical plane is located at a higher level than a gas/meal inlet of the preceding cyclone stage as seen in the direction of movement of the cement raw meal.
• a plant of the aforementioned kind for manufacturing cement is known for example from EP1322899.
• raw meal is introduced into the gas duct for conducting hot gases from the second cyclone of the cyclone preheater to the first cyclone.
• the raw meal is then preheated as it is led through the cyclones of the preheater in counterflow to a flow of hot exit gases from the subsequent calciner and kiln.
• the preheated raw meal is extracted from the last cyclone of the preheater and introduced into the calciner for calcination therein.
• this last cyclone of the preheater has been located at a higher level than the highest desired location of the intake point, whereas the next-to-last cyclone as seen in the direction of movement of the cement raw materials in order to keep the overall installation height of the preheater at a minimum has been located at lower level.
• the gas duct connecting the gas outlet of the last cyclone with the gas/meal inlet of the next-to-last cyclone must include a downwardly directed section.
• the selected cyclone stage comprises an additional cyclone which is placed in parallel to the other cyclone(s) in said cyclone stage and having in said vertical plane a gas outlet located at a lower level than said gas/material inlet of said preceding cyclone stage, and in that the gas ducts from the cyclones in the selected cyclone stage are merged into one single gas duct for conducting the mixed gases to said preceding cyclone stage.
• the amount of raw meal, which is lifted to a higher level may be tailored the actual quantity needed for introduction at the higher located intake point.
• a cyclone stage comprises two or more parallel cyclones of which at least one is located at a higher level
• the pressure drop over this higher located cyclone will mutatis mutandis be higher, thus demanding some kind of means for regulating the gas flows through each cyclone in said cyclone stage.
• Such means may be traditional damper devices placed in the respective gas ducts from at least some of the cyclones in said cyclone stage.
• the raw meal being introduced into the gas from said selected cyclone stage is introduced into the gas duct from the additional cyclone before the gas ducts from the cyclones in the selected cyclone stage are merged into one single gas duct. In this way, the higher pressure drop over the higher located cyclone will in at least to a certain extent be balanced.
• the heat treatment unit may be any kind of unit requiring the introduction of a certain amount of preheated raw meal.
• the heat treatment unit may be mentioned a calciner for calcination of preheated raw meal and a waste combustion apparatus, such as the Hot Disc being marketed by the applicant of the present application.
• a kiln plant for manufacturing cement clinker.
• the plant comprises a cyclone preheater 6 with four cyclone stages 1 , 2, 3 and 4, which are connected in series and fed with gas/raw meal suspension via gas ducts 7, 8, 9 and 10.
• the plant also comprises a heat treatment unit in form of a calciner 1 1 which comprises inlet openings 12 and 13 for introducing preheated raw meal from the cyclone stage 4, which calciner 1 1 is connected to a separating cyclone 5, a rotary kiln 14 and a clinker cooler 15.
• cyclone stage (4) comprises a preheater cyclone (4b), which in a vertical plane is located at a higher level than a gas/meal inlet of the preceding cyclone stage (3) as seen in the direction of movement of the cement raw meal, hence facilitating introduction of preheated raw meal into the calciner 1 1 at a higher, preferably predetermined level.
• the selected cyclone stage 4 comprises two parallel cyclones 4a and 4b, where cyclone 4a may be regarded as an additional cyclone, which has in a vertical plane a gas outlet located at a lower level than said gas/material inlet of the preceding cyclone stage 3, and that the gas ducts from the cyclones 4a and 4b in the selected cyclone stage 4 are merged into one single gas duct for conducting the mixed gases to said preceding cyclone stage 3.
• cyclone 4b may be located at an arbitrary height relative to the other cyclone 4a in cyclone stage 4, while simultaneously ensuring that raw meal from a preceding cyclone stage 2 in an optimum way may be introduced into an upwardly flowing gas stream from cyclone 4a. Preheated raw meal from the selected cyclone stage 4 can therefore be introduced at any point into the calciner 1 1 unit without any use of special lifting equipment.
• the amount of raw meal, which is lifted to a higher level may be tailored the actual quantity needed for introduction at the higher located intake point. Most often, during normal operation, only a minor part of the preheated raw meal from cyclone stage 4 needs to be lifted to a higher intake point of the calciner 1 1 , and thus cyclone 4b would normally be dimensioned relatively small compared to cyclone 4a.
• the pressure drop over cyclone 4b will be higher than over 4a.
• the raw meal from cyclone stage 2 being introduced into the gas from cyclone stage 4 is introduced into the gas duct from the cyclone 4a before the gas ducts from the cyclones 4a and 4b are merged into one single gas duct.
• some kind of damper or restriction device 16 may be fitted in the gas duct from cyclone 4a.
• the heat treatment unit is shown as a calciner 1 1 ; however it may in principle be any kind of unit requiring the introduction of a certain amount of preheated raw meal. Also, the plant may comprise more than one such unit.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Furnace Details (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

Applications Claiming Priority (2)

Publications (1)

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Cited By (1)

Citations (2)

• 2013
  • 2013-09-05 WO PCT/DK2013/050282 patent/WO2014048435A1/fr not_active Ceased

Patent Citations (2)

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