EP0000739B1 - Process and apparatus for making cement in a fluidized bed - Google Patents

Process and apparatus for making cement in a fluidized bed Download PDF

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Publication number
EP0000739B1
EP0000739B1 EP78100518A EP78100518A EP0000739B1 EP 0000739 B1 EP0000739 B1 EP 0000739B1 EP 78100518 A EP78100518 A EP 78100518A EP 78100518 A EP78100518 A EP 78100518A EP 0000739 B1 EP0000739 B1 EP 0000739B1
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EP
European Patent Office
Prior art keywords
fluidized bed
zone
air flow
fuel
precalcined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP78100518A
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German (de)
French (fr)
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EP0000739A1 (en
Inventor
Klaus Bauer
Wolf Goldmann
Horst Kretzer
Heinrich Weber
Rüdiger Beyer
Wilfried Kreft
Frank Dr. Schaberg
Rudolf Weber
Herbert Schmelter
Horst Dr. Ritzmann
Erich Schnieder
Georg Schepers
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ThyssenKrupp Industrial Solutions AG
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Krupp Polysius AG
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Publication date
Priority claimed from DE19772735140 external-priority patent/DE2735140A1/en
Priority claimed from DE19772735084 external-priority patent/DE2735084A1/en
Priority claimed from DE19782822419 external-priority patent/DE2822419A1/en
Priority claimed from DE19782822395 external-priority patent/DE2822395A1/en
Priority claimed from DE19782822377 external-priority patent/DE2822377A1/en
Application filed by Krupp Polysius AG filed Critical Krupp Polysius AG
Publication of EP0000739A1 publication Critical patent/EP0000739A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/1809—Controlling processes
    • 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
    • C04B7/44—Burning; Melting
    • C04B7/45—Burning; Melting in fluidised beds, e.g. spouted beds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00026—Controlling or regulating the heat exchange system
    • B01J2208/00035—Controlling or regulating the heat exchange system involving measured parameters
    • B01J2208/00044—Temperature measurement
    • B01J2208/00061—Temperature measurement of the reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00504—Controlling the temperature by means of a burner
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60Y—INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
    • B60Y2200/00—Type of vehicle
    • B60Y2200/10—Road Vehicles
    • B60Y2200/14—Trucks; Load vehicles, Busses
    • B60Y2200/143—Busses

Definitions

  • the invention relates to a method for producing cement by firing powdered raw material in a fluidized bed, into which preheated raw material, fuel, preheated air and a recycled part of the fired material are introduced, the material discharged from the fluidized bed subsequently being passed through a cooling zone by a Cooling air flow is cooled, and a device for performing the method.
  • a process for the production of cement is known (CH-A 292 727), in which the drying, preheating and deacidification of the raw material takes place in fluidized beds of a shaft-shaped reactor arranged one above the other, while the final firing of the material (ie the clinker formation) takes place in a funnel shape downward tapering reaction space occurs, to which fuel is fed in the lower region and the material to be burned in the upper region, a cooling zone adjoining the lower outlet end of this reaction chamber.
  • the heat treatment of the material in the drying, preheating and deacidification stage is carried out by the hot exhaust gases from the finished combustion zone and possibly by additional fuel.
  • a disadvantage of this method is above all the difficulty in precisely controlling the time the goods are in the finished firing zone and ensuring uniform heat treatment of all good particles in the finished firing zone.
  • cement-lime gypsum 1970, pp. 343 to 347, FR-A 1 192 838 and DE-B 1 433 913.
  • the disadvantages here are the effort involved in granulating the raw material and the inadequate uniformity of the heat treatment of the inner and outer material zones of the granules.
  • the fired clinker is either drawn off from the fluidized bed by an overflow or a central outlet (see DE-B 1 156 012 or CH-A 381 590) or discharged together with the gases upward from the fluidized bed reactor (see. NL-A 69 08 171).
  • the problem with the known process is still the strong alkali vaporization when burning in the fluidized bed.
  • This results in an extraordinarily high alkali content in the exhaust gases of the fluidized bed in the case of strongly alkaline raw materials, which in many cases excludes the use of these exhaust gases for preheating the raw material and thus leads to an undesirably high heat requirement.
  • the invention is therefore based on the object of avoiding these deficiencies to provide a method for firing powdered cement raw material in a fluidized bed, which is characterized by a particularly stable operation of the fluidized bed, a very evenly fired end product and a comparatively low heat consumption, and also the production permitted by cement clinker with a particularly low alkali content.
  • the fluidized bed is relieved of a large part of the heat work that would otherwise have to be done, which has substantial advantages:
  • the fluidized bed can be dimensioned smaller, requires less fuel and delivers a smaller amount of exhaust gas.
  • the substantial reduction in the amount of exhaust gas from the fluidized bed makes it possible, in the case of a particularly high alkali content of the raw material, to dispense with the use of these exhaust gases for preheating and precalcination of the raw material, in whole or in part, without significantly increasing the heat requirement.
  • the rapid and even distribution of the pre-calcined material in the fluidized bed is further promoted by the fact that the pre-calcined material is introduced into the fluidized bed from the side by part of the cooling air flow, preferably with a pulse between 49 and 98 Ns.
  • this measure achieves a very good distribution of the pre-calcined material in the fluidized bed even when the material insertion point is very deep, i.e. is just above the cooling zone.
  • the significantly improved combustion conditions in the fluidized bed due to the strong precalcination and the rapid, even distribution of pre-calcined material and fuel in the fluidized bed also ensure that the cooling zone immediately below the fluidized bed functions properly and, in particular, prevents operational disruptions due to caking of the material in the cooling zone.
  • the method according to the invention thus delivers very homogeneously fired clinker beads of approximately uniform grain size.
  • the quantity of material present in the fluidized bed is kept approximately constant irrespective of fluctuations in the quantity of material supplied and discharged.
  • the necessary constant maintenance of the quantity of material cannot be achieved by simple volumetric control of the quantity of material supplied and removed.
  • the amount of material in the fluidized bed is therefore regulated as a function of a gas pressure measured in the fluidized bed.
  • a gas pressure measured in the fluidized bed is a very sensitive and reliable measure of the amount of material present in the fluidized bed, so that the latter can be kept constant depending on the gas pressure (by either the quantity of material discharged from the fluidized bed or the cooling zone or the quantity of material introduced into the fluidized bed or both quantities of material are controlled accordingly).
  • the quantity of material located in the fluidized bed is expediently controlled as a function of the difference between a gas pressure measured in the fluidized bed and a gas pressure measured in the exhaust gas line of the fluidized bed, since an increase in the amount of exhaust gas in the fluidized bed has no influence on the setpoint value set in such a differential pressure control .
  • At least part of the fuel is expediently introduced into the fluidized bed from below from below the surface of the fluidized bed, preferably approximately at the level of the supply of the pre-calcined material. Another part of the fuel can be introduced into the fluidized bed via the surface of the fluidized bed or together with the recycled part of the fired material.
  • the part of the fuel which is pneumatically introduced into the fluidized bed from the side is preferably introduced into the fluidized bed together with the pre-calcined material, and advantageously at several locations distributed uniformly over the circumference of the fluidized bed. This results in a particularly rapid and even distribution of material and fuel in the fluidized bed.
  • the preheating and precalcination zone will An adjustable part of the exhaust gases of the fluidized bed and preferably an adjustable part of the cooling air flow are expediently supplied, while the remaining part of the exhaust gases of the fluidized bed are removed bypassing the preheating and precalcination zone.
  • the entire exhaust gases of the fluidized bed can also be removed bypassing the preheating and precalcination zone and the latter can be fed exclusively with cooling air.
  • the plant contains a preheater 1, a precalcination zone 2 and a shaft-shaped reaction chamber 3 with a fluidized bed 4 and a cooling zone 5.
  • the pulverulent raw material fed in at 6 is preheated in countercurrent by hot gases (arrow 7) and then passes (arrow 8) into the precalcination zone 2, where it is caused by the hot exhaust gases (arrow 9) the reaction chamber 3 and additional fuel (arrow 10) is pre-calcined to a degree of deacidification of 80 to 95%.
  • the pre-calcined material is then fed (arrows 11, 12) to conveying lines 13, 14, via which it is pneumatically introduced into the fluidized bed 4 along with fuel 15 or 16 at least two mutually opposite points (arrows 17).
  • the clear cross section of the reaction space 3 is narrowed in the region of the mouth of the delivery lines 13, 14 and widens conically upwards from this feed zone.
  • the cross section of the reaction chamber 3 and the flow velocities of the air are dimensioned such that in the lower region of the fluidized bed, i.e. the area intended for the introduction of the pre-calcined material, i. approximately at the level of the delivery lines 13, 14, approximately the same gap degree, preferably between 0.6 and 0.7 as in the upper region of the fluidized bed.
  • the pre-calcined material is fired into cement clinker. After reaching a certain clinker size, the fired material gels into the cooling zone 5, to which a cooling air flow (arrows 19) is fed from below through the air-permeable base 18.
  • the cooled goods are drawn off by a rotating discharge device 20 (arrow 21). Part of the material is recycled into the fluidized bed 4 as seed clinker (arrow 22).
  • a part of the cooling air flow identified by the arrows 23 is introduced into the fluidized bed 4 as loosening and combustion air from below.
  • Another part (arrow 24) is drawn off laterally on the circumference of the upper region of the cooling zone 5 by an air extraction line, possibly dedusted in a cyclone 25 and by a blower 26 to the delivery lines 13, 14 as conveying air for the pre-calcined material (arrows 11, 12) and the fuel (arrows 15, 16) supplied (arrows 27, 28).
  • blower 26 Another part of this air conveyed by the blower 26 can be usefully introduced into the fluidized bed 4 as additional side air below the level of the conveying lines 13, 14 (arrows 29, 30).
  • Another portion of the air conveyed by the blower 26 to the cooling zone 5 can be fed to the precalcination zone 2 as additional combustion air (arrow 31). Any excess air (arrow 32) can be discarded or otherwise used. Likewise, a certain proportion of the exhaust gases from the fluidized bed 4 - in particular with a high alkali content - can be branched off bypassing the precalcination zone 2 and the preheater 1 (arrow 33).
  • the system contains four pressure measuring points 34, 35, 36 and 37, of which the pressure measuring point 34 lies approximately in the area of the introduction of the material, the measuring point 35 approximately to 1/3 to 1/2 the height of the fluidized bed 4, the pressure measuring point 36 in the upper third of the fluidized bed and the pressure measuring point 37 in the exhaust pipe of the fluidized bed.
  • the four pressure measuring points are connected to a pressure transducer 38 which is connected to a regulator 39.
  • This regulator 39 acts on the one hand on the discharge device 20 (control line 40) and on the other hand on a feed metering device 41 (control line 42).
  • the controller 39 keeps the quantity of material in the fluidized bed 4 constant, for example by means of the discharge device 20 controlled by the controller 39 only discharging the quantity of material located above the setpoint from the cooling zone 5 and thus from the fluidized bed 4 or by the material feed metering device 41 In each case a quantity of good missing at the setpoint is fed.
  • a pressure value supplied by the pressure measuring points 34 to 37 is used as a measure of the quantity of material in the fluidized bed 4, for example the difference between the pressures determined at the measuring points 34 and 37.
  • the grain size of the seed clinker is 2 to 4 mm; the ratio of raw flour to seed clinker is 4: 1.
  • the preheated and pre-calcined material is placed in the at a temperature of approx. 840 ° C Fluid bed 4 introduced.
  • the temperature in this fluidized bed is between 1300 and 1350 ° C.
  • the material is cooled to a temperature of 80 to 120 ° C.
  • the loss on ignition of the raw material after the preheater is 5%.
  • the grain size of the deacidified raw material is 44%> 90 / 1m and 8.8%> 200 fl m.
  • the air volumes can be selected as follows;
  • the cooling zone 5 is fed from below 1.00 Nm 3 / kg clinker. From this, 0.33 Nm 3 / kg of KI get directly into the fluidized bed from below (arrows 23), while 0.67 Nm 3 / kg of KI are removed from the side of the cooling zone (arrow 24). From this latter part, 0.17 Nm 3 / kg KI as conveying air (arrows 27, 28) for precalcined material and fuel enter the fluidized bed 4 from the side, while 0.5 Nm 3 / kg KI directly (arrow 31) Precalcination zone 2 are supplied. An equal amount of air (0.5 Nm 3 / kg KI) reaches the precalcination zone 2 as exhaust gases from the fluidized bed (arrow 9).
  • the differential pressure measured between the pressure measuring points 34 and 37 is between 78 and 118 m bar, the differential pressure between the pressure measuring points 35 and 37 between 25 and 39 m bar.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Furnace Details (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Zement durch Brennen von pulverförmigem Rohmaterial in einer Wirbelschicht, in die vorgewärmtes Rohmaterial, Brennstoff, vorgewärmte Luft sowie ein rezyklierter Teil des gebrannten Gutes eingeführt werden, wobei das aus der Wirbelschicht ausgetragene Gut anschließend in einer Kühlzone durch einen Kühlluftstrom gekühlt wird, sowie eine Vorrichtung zur Durchführung das Verfahrens.The invention relates to a method for producing cement by firing powdered raw material in a fluidized bed, into which preheated raw material, fuel, preheated air and a recycled part of the fired material are introduced, the material discharged from the fluidized bed subsequently being passed through a cooling zone by a Cooling air flow is cooled, and a device for performing the method.

Es ist ein Verfahren zur Herstellung von Zement bekannt (CH-A 292 727), bei dem die Trocknung, Vorwärmung und Entsäuerung des Rohmateriales in übereinander angeordneten Wirbelschichten eines schachtförmigen Reaktors erfolgt, während das Fertigbrennen des Materiales (d.h. die Klinkerbildung) in einem sich trichterförmig nach unten verjüngenden Reakstionsraum geschieht, dem im unteren Bereich Brennstoff und im oberen Bereich das zu brennende Material zugeführt werden, wobei sich an das untere Auslaßende dieses Reaktionsraumes eine Kühlzone anschließt. Die Wärmebehandlung des Materiales in der Trocknungs-, Vorwärm- und Entsäuerungsstufe erfolgt durch die heißen Abgase der Fertigbrennzone sowie eventuell durch zusätzlichen Brennstoff. Nachteilig ist bei diesem Verfahren vor allem die Schwierigkeit, die Aufenthaltszeit des Gutes in der Fertigbrennzone genau zu steuern und eine gleichmäßige Wärmebehandlung aller Gutteilchen in der Fertigbrennzone zu gewährleisten.A process for the production of cement is known (CH-A 292 727), in which the drying, preheating and deacidification of the raw material takes place in fluidized beds of a shaft-shaped reactor arranged one above the other, while the final firing of the material (ie the clinker formation) takes place in a funnel shape downward tapering reaction space occurs, to which fuel is fed in the lower region and the material to be burned in the upper region, a cooling zone adjoining the lower outlet end of this reaction chamber. The heat treatment of the material in the drying, preheating and deacidification stage is carried out by the hot exhaust gases from the finished combustion zone and possibly by additional fuel. A disadvantage of this method is above all the difficulty in precisely controlling the time the goods are in the finished firing zone and ensuring uniform heat treatment of all good particles in the finished firing zone.

Es ist weiterhin bekannt, granuliertes Zementrohmaterial in einer Wirbelschicht zu brennen ("Zement-Kalk-Gips", 1970, S.343 bis 347, FR-A 1 192 838 sowie DE-B 1 433 913). Nachteilig ist hierbei der mit dem Granulieren des Rohmateriales verbundene Aufwand sowie die mangelnde Gleichmäßigkeit der Wärmebehandlung der inneren und äußeren Materialzonen der Granalien.It is also known to burn granulated cement raw material in a fluidized bed ("cement-lime gypsum", 1970, pp. 343 to 347, FR-A 1 192 838 and DE-B 1 433 913). The disadvantages here are the effort involved in granulating the raw material and the inadequate uniformity of the heat treatment of the inner and outer material zones of the granules.

Zur Vermeidung dieser Nachteile hat man ferner versucht, pulverförmiges Zementrohmaterial in einer Wirbelschicht zu brennen (DE-B 1 156012, CH-A 381 590, NL-A 69 08 171 sowie "Zement-Kalk-Gips", 1971, S.571 bis 573). Hierbei wird in die Wirbelschicht außer pulverförmigen Rohmaterial, Brennstoff, Verbrennungs- und Auflockerungsluft auch ein rezyklierter Teil des gebrannten Gutes als sog. "Saatklinker" eingeführt, so daß in der Wirbelschicht durch Anlagerung des Rohmehles ein kontinuierliches Kornwachstum der Klinkerteilchen erreicht wird. Das Rohmaterial sowie die Luft werden vor Aufgabe in die Wirbelschicht vorgewärmt. Der gebrannte Klinker wird entweder durch einem Überlauf bzw. einen zentralen Ablauf nach unten aus der Wirbelschicht abgezogen (vgl. DE-B 1 156 012 bzw. CH-A 381 590) oder zusammen mit den Gasen nach oben aus dem Wirbelschichtreaktor ausgetragen (vgl. NL-A 69 08 171).To avoid these disadvantages, attempts have also been made to burn powdered cement raw material in a fluidized bed (DE-B 1 156012, CH-A 381 590, NL-A 69 08 171 and "Zement-Kalk-Gips", 1971, p.571 to 573). Here, in addition to powdered raw material, fuel, combustion and loosening air, a recycled part of the fired material is introduced into the fluidized bed as so-called "seed clinker", so that a continuous grain growth of the clinker particles is achieved in the fluidized bed by the addition of the raw meal. The raw material and the air are preheated into the fluidized bed before being fed. The fired clinker is either drawn off from the fluidized bed by an overflow or a central outlet (see DE-B 1 156 012 or CH-A 381 590) or discharged together with the gases upward from the fluidized bed reactor (see. NL-A 69 08 171).

Bei der praktischen Durchführung dieses Verfahrens traten erhebliche Schwierigkeiten auf, die eine Realisierung im großtechnischen Maßstab bisher ausschlossen. So erwies es sich bisher vielfach als schwierig, das vorgewärmte Rohmaterial und den Brennstoff rasch und gleichmäßig in der Wirbelschicht zu verteilen und den Betrieb der Wirbelschicht einwandfrei zu stabilisieren. Durch das vorhandene Kornband stellt sich nämlich in der Wirbelschicht ein gewisser Separiereffekt und damit ein nach unten hin abnehmender Lückengrad ein (als Lückenqrad gilt das Verhältnis von Leervolumen zu Gesamtvolumen einer Wirbelschicht).In the practical implementation of this method, considerable difficulties have arisen which have hitherto ruled out implementation on an industrial scale. So far, it has often proven difficult to distribute the preheated raw material and fuel quickly and evenly in the fluidized bed and to stabilize the operation of the fluidized bed properly. Due to the existing grain belt, there is a certain separation effect in the fluidized bed and thus a decreasing gap level (the gap ratio is the ratio of empty volume to the total volume of a fluidized bed).

Problematisch ist bei dem bekannten Verfahren weiterhin die starke Alkaliverdampfung beim Brennen in der Wirbelschicht. Hierdurch ergibt sich bei stark alkalihaltigen Rohmaterialien ein außerordentlich hoher Alkaligehalt in den Abgasen der Wirbelschicht, was eine Nutzung dieser Abgase zur Vorwärmung des Rohmateriales vielfach ausschließt und damit zu einem unerwünscht großen Wärmebedarf führt. Der Erfindung liegt daher die Aufgabe zugrunde, unter Vermeidung dieser Mängel ein Verfahren zum Brennen von pulverförmigem Zementrohmaterial in einer Wirbelschicht zu schaffen, das sich durch einen besonders stabilen Betrieb der Wirbelschicht, ein sehr gleichmäßig gebranntes Endprodukt sowie einen vergleichsweise niedrigen Wärmeverbrauch auszeichnet und auch die Herstellung von Zementklinker mit besonders niedrigem Alkaligehalt gestattet.The problem with the known process is still the strong alkali vaporization when burning in the fluidized bed. This results in an extraordinarily high alkali content in the exhaust gases of the fluidized bed in the case of strongly alkaline raw materials, which in many cases excludes the use of these exhaust gases for preheating the raw material and thus leads to an undesirably high heat requirement. The invention is therefore based on the object of avoiding these deficiencies to provide a method for firing powdered cement raw material in a fluidized bed, which is characterized by a particularly stable operation of the fluidized bed, a very evenly fired end product and a comparatively low heat consumption, and also the production permitted by cement clinker with a particularly low alkali content.

Diese Aufgabe wird erfindungsgemäß durch die Kombination folgender Merkmale gelöst:

  • a) Das vorgewärmte Rohmaterial wird vor Aufgabe in die Wirbelschicht in einer Vorkalzinationszone mit zusätzlichem Brennstoff bis auf einen Entsäuerungsgrad von 80 bis 95% vorkalziniert;
  • b) aus dem unteren Bereich der Wirbelschicht gelangt das gebrannte Gut in eine Kühlzone, die von dem unmittelbar unterhalb der Wirbelschicht befindlichen Teil der Gutschüttung gebildet wird;
  • c) ein Teil des Kühlluftstromes wird von unten her und ein weiterer Teil von der Seite her in die Wirbelschicht eingeführt;
  • d) das vorkalzinierte Gut wird durch den von der Seite her in die Wirbelschicht eingeführten Teil des Kühlluftstromes in die Wirbelschicht eingetragen;
  • e) in dem zur Einführung des vorkalzinierten Gutes bestimmten unteren Bereich der Wirbelschicht wird durch eine Querschnittsverengung etwa derselben Lückengrad wie im oberen Bereich der Wirbelshicht, vorzugsweise ein Lückengrad zwischen 0,5 und 0,8 eingestellt;
  • f) die in der Wirbelschicht befindliche Gutmenge wird in Abhängigkeit von einem in der Wirbelschicht gemessenen Gasdruck geregelt.
This object is achieved according to the invention by combining the following features:
  • a) The preheated raw material is pre-calcined in a precalcination zone with additional fuel to a degree of deacidification of 80 to 95%;
  • b) from the lower region of the fluidized bed, the fired material reaches a cooling zone which is formed by the part of the bed of material located immediately below the fluidized bed;
  • c) part of the cooling air flow is introduced from below and another part from the side into the fluidized bed;
  • d) the pre-calcined material is introduced into the fluidized bed by the part of the cooling air flow introduced into the fluidized bed from the side;
  • e) in the lower region of the fluidized bed intended for the introduction of the pre-calcined material, a narrowing of the cross-section causes approximately the same degree of gap as in the upper region of the vertebral layer, preferably a gap set between 0.5 and 0.8;
  • f) the quantity of material in the fluidized bed is regulated as a function of a gas pressure measured in the fluidized bed.

Erfindungsgemäß erfolgt eine weitgehende Entsäuerung (Vorkalzination, d.h. Austreibung des CO2) des Rohmateriales vor Aufgabe in die Wirbelschicht. Dadurch wird die Wirbelschicht von einem großen Teil der sonst zu leistenden Wärmearbeit entlastet, was wessentliche Vorteile mit sich bringt: Die Wirbelschicht kann kleiner dimensioniert werden, erfordert nur eine geringere Brennstoffzufuhr und liefert eine kleinere Abgasmenge. Die wesentliche Verringerung der Abgasmenge der Wirbelschicht gestattet es, bei besonders hohem Alkaligehalt des Rohmateriales auf eine Verwertung dieser Abgase zur Vorwärmung und Vorkalzination des Rohmateriales ganz oder teilweise zu verzichten, ohne dadurch den Wärmebedarf wesentlich zu vergrößern..According to the invention, there is extensive deacidification (precalcination, ie expulsion of the CO 2 ) of the raw material before feeding it into the fluidized bed. As a result, the fluidized bed is relieved of a large part of the heat work that would otherwise have to be done, which has substantial advantages: The fluidized bed can be dimensioned smaller, requires less fuel and delivers a smaller amount of exhaust gas. The substantial reduction in the amount of exhaust gas from the fluidized bed makes it possible, in the case of a particularly high alkali content of the raw material, to dispense with the use of these exhaust gases for preheating and precalcination of the raw material, in whole or in part, without significantly increasing the heat requirement.

Indem erfindungsgemäß ein Teil des Kühlluftstromes von unten her und ein weiterer Teil von der Seite her in die Wirbelschicht eingeführt wird, erreicht man eine rasche und gleichmäßige Verteilung von vorkalziniertem Gut und Brennstoff in der Wirbelschicht, eine besonders gleichmäßige Wärmebehandlung des Gutes und einen sehr stabilen Betrieb der Wirbelschicht.By introducing part of the cooling air flow from below and a further part from the side into the fluidized bed, a rapid and uniform distribution of pre-calcined material and fuel in the fluidized bed, a particularly uniform heat treatment of the material and very stable operation are achieved the fluidized bed.

Die rasche und gleichmäßige Verteilung des vorkalzinierten Gutes in der Wirbelschicht wird ferner noch dadurch begünstigt, daß das vorkalzinierte Gut durch einen Teil des Kühlluftstromes von der Seite her, vorzugsweise mit einem Impuls zwischen 49 und 98 Ns, in die Wirbelschicht eingeführt wird.The rapid and even distribution of the pre-calcined material in the fluidized bed is further promoted by the fact that the pre-calcined material is introduced into the fluidized bed from the side by part of the cooling air flow, preferably with a pulse between 49 and 98 Ns.

Indem dabei in dem zur Einführung des vorkalzinierten Gutes bestimmten unteren Bereich der Wirbelschicht durch eine Querschnittsverengung etwa derselbe Lückengrad wie im oberen Bereich der Wirbelschicht eingestellt wird, ergibt sich eine besonders intensive Materialbewegung in dieser Einführzone, was die Gefahr von Ansatzbildungen und Agglomerationen in diesem besonders gefährdeten Bereich praktisch ausschließt. Außerdem erreicht man durch diese Maßnahme eine sehr gute Verteilung des vorkalzinierten Gutes in der Wirbelschicht auch dann, wenn die Guteinführstelle sehr tief, d.h. dicht über der Kühlzone liegt.By setting approximately the same gap level in the lower area of the fluidized bed intended for the introduction of the pre-calcined material through a cross-sectional narrowing as in the upper area of the fluidized bed, this results in a particularly intensive material movement in this insertion zone, which particularly endangered the risk of build-ups and agglomerations in this Practically excludes the area. In addition, this measure achieves a very good distribution of the pre-calcined material in the fluidized bed even when the material insertion point is very deep, i.e. is just above the cooling zone.

Die durch die starke Vorkalzination und die rasche, gleichmäßige Verteilung von vorkalziniertem Gut und Brennstoff in der Wirbelschicht wesentlich verbesserten Brennverhältnisse in der Wirbelschicht gewährleisten außerdem ein gutes Funktionieren der unmittelbar unter der Wirbelschicht angeordneten Kühlzone und schließen insbesondere Betriebsstörungen durch Zusammenbackungen von Gut in der Kühlzone aus. Das erfindungsgemäße Verfahren liefert damit sehr homogen gebrannte Klinkerkügelchen von annähernd gleichmäßiger Korngröße.The significantly improved combustion conditions in the fluidized bed due to the strong precalcination and the rapid, even distribution of pre-calcined material and fuel in the fluidized bed also ensure that the cooling zone immediately below the fluidized bed functions properly and, in particular, prevents operational disruptions due to caking of the material in the cooling zone. The method according to the invention thus delivers very homogeneously fired clinker beads of approximately uniform grain size.

Für einen stabilen Betrieb der Wirbelschicht ist es dabei wichtig, daß die jeweils in der Wirbelschicht befindliche Gutmenge unabhängig von Schwankungen der zu- und abgeführten Gutmenge annähernd konstant gehalten wird. Da jedoch in der Wirbelschicht eine wesentliche Kornvergrößerung eintritt, läßt sich die notwendige Konstanthaltung der Gutmenge nicht durch eine einfache volumetrische Steuerung der zu- und abgeführten Gutmenge erreichen. Erfindungsgemäß wird daher die in der Wirbelschicht befindliche Gutmenge in Abhängigkeit von einem in der Wirbelschicht gemessenen Gasdruck geregelt. Bei den der Erfindung zugrundeliegenden Versuchen hat sich nämlich überraschend herausgestellt, daß ein in der Wirbelschicht gemessener Gasdruck ein sehr feinfühliges und zuverlässiges Maß für die in der Wirbelschicht befindliche Gutmenge ist, so daß letztere in Abhängigkeit von dem Gasdruck konstant gehalten werden kann (indem entweder die aus der Wirbelshicht bzw. der Kühlzone ausgetragene Gutmenge oder die in die Wirbelschicht eingeführte Gutmenge oder beide Gutmengen entsprechend gesteuert werden).For stable operation of the fluidized bed, it is important that the quantity of material present in the fluidized bed is kept approximately constant irrespective of fluctuations in the quantity of material supplied and discharged. However, since a substantial increase in grain size occurs in the fluidized bed, the necessary constant maintenance of the quantity of material cannot be achieved by simple volumetric control of the quantity of material supplied and removed. According to the invention, the amount of material in the fluidized bed is therefore regulated as a function of a gas pressure measured in the fluidized bed. In the experiments on which the invention is based, it surprisingly turned out that a gas pressure measured in the fluidized bed is a very sensitive and reliable measure of the amount of material present in the fluidized bed, so that the latter can be kept constant depending on the gas pressure (by either the quantity of material discharged from the fluidized bed or the cooling zone or the quantity of material introduced into the fluidized bed or both quantities of material are controlled accordingly).

Zweckmäßig wird dabei die in der Wirbelschicht befindliche Gutmenge in Abhängigkeit von der Differenz zwischen einem in der Wirbelschicht gemessenen Gasdruck und einem in der Abgasleitung der Wirbelschicht gemessenen Gasdruck geregelt, da bei einer solchen Differenzdruckregelung eine Erhöhung der Abgasmenge der Wirbelschicht keinen Einfluß auf den eingestellten Sollwert besitzt.The quantity of material located in the fluidized bed is expediently controlled as a function of the difference between a gas pressure measured in the fluidized bed and a gas pressure measured in the exhaust gas line of the fluidized bed, since an increase in the amount of exhaust gas in the fluidized bed has no influence on the setpoint value set in such a differential pressure control .

Zumindest ein Teil des Brennstoffes wird zweckmäßig unterhalb der Oberfläche der Wirbelschicht, vorzugsweise etwa in Höhe der Zufuhr des vorkalzinierten Gutes, von der Seite her in die Wirbelschicht eingeführt. Ein weiterer Teil des Brennstoffes kann über die Oberfläche der Wirbelschicht oder zusammen mit dem rezyklierten Teil des gebrannten Gutes in die Wirbelschicht eingeführt werden.At least part of the fuel is expediently introduced into the fluidized bed from below from below the surface of the fluidized bed, preferably approximately at the level of the supply of the pre-calcined material. Another part of the fuel can be introduced into the fluidized bed via the surface of the fluidized bed or together with the recycled part of the fired material.

Der von der Seite her pneumatisch in die Wirbelschicht eingeführte Teil des Brennstoffes wird vorzugsweise zusammen mit dem vorkalzinierten Gut in die Wirbelschicht eingebracht, und zwar vorteilhaft an mehreren, gleichmäßig über den Umfang der Wirbelschicht verteilten Stellen. Dadurch erzielt man eine besonders rasche und gleichmäßige Verteilung von Gut und Brennstoff in der Wirbelschicht.The part of the fuel which is pneumatically introduced into the fluidized bed from the side is preferably introduced into the fluidized bed together with the pre-calcined material, and advantageously at several locations distributed uniformly over the circumference of the fluidized bed. This results in a particularly rapid and even distribution of material and fuel in the fluidized bed.

Für einen optimalen Betrieb der Wirbelschicht hat es sich als günstig erwiesen, wenn etwa 50 bis 90%, vorzugsweise etwa 2/3 der gesamten, der Wirbelschicht zugeführten Luft von unten her und 10 bis 50%, vorzugsweise etwa 1/3 der Luft von der Seite her in die Wirbelschicht eingeleitet werden.For optimal operation of the fluidized bed, it has proven to be advantageous if about 50 to 90%, preferably about 2/3 of the total air supplied to the fluidized bed from below and 10 to 50%, preferably about 1/3 of the air from the Be introduced into the fluidized bed.

Der Vorwärm- und Vorkalzinationszone wird zweckmäßig ein einstellbarer Teil der Abgase der Wirbelschicht sowie vorsugsweise ein einstellbarer Teil des Kühlluftstromes zugeführt, während der übrige Teil der Abgase der Wirbelschicht unter Umgehung der Vorwärm- und Vorkalzinationszone abgeführt wird. Bei besonders alkalihaltigem Rohmaterial können auch die gesamten Abgase der Wirbelschicht unter Umgehung der Vorwärm- und Vorkalzinationszone abgeführt und letztere ausschließlich mit Kühlluft gespeist werden.The preheating and precalcination zone will An adjustable part of the exhaust gases of the fluidized bed and preferably an adjustable part of the cooling air flow are expediently supplied, while the remaining part of the exhaust gases of the fluidized bed are removed bypassing the preheating and precalcination zone. In the case of raw material with a particularly high alkali content, the entire exhaust gases of the fluidized bed can also be removed bypassing the preheating and precalcination zone and the latter can be fed exclusively with cooling air.

Ein Ausführungsbeispiel einer Anlage zur Durchführung des erfindungsgemäßen Verfahrens ist in der Zeichnung veranschaulicht.An embodiment of a system for performing the method according to the invention is illustrated in the drawing.

Die Anlage enthält einen Vorwärmer 1, eine Vorkalzinationszone 2 und einen schachtförmigen Reaktionsraum 3 mit einer Wirbelschicht 4 und einer Kühlzone 5.The plant contains a preheater 1, a precalcination zone 2 and a shaft-shaped reaction chamber 3 with a fluidized bed 4 and a cooling zone 5.

Im Vorwärmer 1, der beispielsweise als mehrstufiger Zylkonwärmetauscher ausgebildet sein kann, wird das bei 6 aufgegebene pulverförmige Rohmaterial im Gegenstrom durch heiße Gase (Pfeil 7) vorgewärmt und gelangt dann (Pfeil 8) in die Vorkalzinationszone 2, wo es durch die heißen Abgase (Pfeil 9) des Reaktionsraumes 3 und zusätzlichen Brennstoff (Pfeil 10) bis auf einen Entsäuerungsgrad von 80 bis 95% vorkalziniert wird.In the preheater 1, which can be designed, for example, as a multi-stage cylinder heat exchanger, the pulverulent raw material fed in at 6 is preheated in countercurrent by hot gases (arrow 7) and then passes (arrow 8) into the precalcination zone 2, where it is caused by the hot exhaust gases (arrow 9) the reaction chamber 3 and additional fuel (arrow 10) is pre-calcined to a degree of deacidification of 80 to 95%.

Das vorkalzinierte Gut wird dann (Pfeile 11, 12) Förderleitungen 13, 14 zugeführt, über die es zusammen mit Brennstoff 15 bzw. 16 an wenigstens zwei einander gegenüberliegenden Stellen vom Umfang her pneumatisch in die Wirbelschicht 4 eingetragen wird (Pfeile 17).The pre-calcined material is then fed (arrows 11, 12) to conveying lines 13, 14, via which it is pneumatically introduced into the fluidized bed 4 along with fuel 15 or 16 at least two mutually opposite points (arrows 17).

Der lichte Querschnitt des Reaktionsraumes 3 ist im Bereich der Einmündung der Förderleitungen 13, 14 verengt und erweitert sich von dieser Guteinführzone aus nach oben hin konisch. Der Querschnitt des Reaktionsraumes 3 sowie die Strömungsgeschwindigkeiten der Luft sind so bemessen, daß sich in dem zur Einführung des vorkalzinierten Gutes bestimmten unteren Bereich der Wirbelschicht, d.h. etwa auf der Höhe der Förderleitungen 13, 14, etwa derselbe Lückengrad, vorzugsweise zwischen 0.6 und 0.7 wie im oberen Bereich der Wirbelschicht einstellt.The clear cross section of the reaction space 3 is narrowed in the region of the mouth of the delivery lines 13, 14 and widens conically upwards from this feed zone. The cross section of the reaction chamber 3 and the flow velocities of the air are dimensioned such that in the lower region of the fluidized bed, i.e. the area intended for the introduction of the pre-calcined material, i. approximately at the level of the delivery lines 13, 14, approximately the same gap degree, preferably between 0.6 and 0.7 as in the upper region of the fluidized bed.

In der Wirbelschicht 4 wird das vorkalzinierte Gut zu Zementklinker gebrannt. Nach Erreichen einer bestimmten Klinkergröße gelant das gebrannte Gut in die Kühlzone 5, der von unten her durch den luftdurchlässigen Boden 18 ein Kühlluftstrom (Pfeile 19) zugeführt wird.In the fluidized bed 4, the pre-calcined material is fired into cement clinker. After reaching a certain clinker size, the fired material gels into the cooling zone 5, to which a cooling air flow (arrows 19) is fed from below through the air-permeable base 18.

Das gekühlte Gut wird durch eine rotierende Austragseinrichtung 20 abgezogen (Pfeil 21). Ein Teil des Gutes wird als Saatklinker in die Wirbelschicht 4 rezykliert (Pfeil 22).The cooled goods are drawn off by a rotating discharge device 20 (arrow 21). Part of the material is recycled into the fluidized bed 4 as seed clinker (arrow 22).

Ein durch die Pfeile 23 gekennzeichneter Teil des Kühlluftstromes wird von unten her als Auflockerungs- und Verbrennungsluft in die Wirbelschicht 4 eingeführt. Ein weiterer Teil (Pfeil 24) wird seitlich am Umfang des oberen Bereiches der Kühlzone 5 durch eine Luftabzugsleitung abgezogen, enventuell in einem Zyklon 25 entstaubt und durch ein Gebläse 26 den Förderleitungen 13, 14 als Förderluft für das vorkalzinierte Gut (Pfeile 11, 12) und den Brennstoff (Pfeile 15, 16) zugeführt (Pfeile 27, 28).A part of the cooling air flow identified by the arrows 23 is introduced into the fluidized bed 4 as loosening and combustion air from below. Another part (arrow 24) is drawn off laterally on the circumference of the upper region of the cooling zone 5 by an air extraction line, possibly dedusted in a cyclone 25 and by a blower 26 to the delivery lines 13, 14 as conveying air for the pre-calcined material (arrows 11, 12) and the fuel (arrows 15, 16) supplied (arrows 27, 28).

Ein weiterer Teil dieser vom Gebläse 26 geförderten Luft kann-zweckmäßig unterhalb der Ebene der Förderleitungen 13, 14-als zusätzliche Seitenluft in die Wirbelschicht 4 eingeführt werden (Pfeile 29, 30).Another part of this air conveyed by the blower 26 can be usefully introduced into the fluidized bed 4 as additional side air below the level of the conveying lines 13, 14 (arrows 29, 30).

Ein weiterer Anteil der vom Gebläse 26 geförderten Luft der Kühlzone 5 kann als zusätzliche Verbrennungsluft der Vorkalzinationszone 2 zugeleitet werden (Pfeil 31). Ein eventuell überschüssiger Luftanteil (Pfeil 32) kann verworfen oder anderweitig verwertet werden. Ebenso kann ein gewisser Anteil der Abgase der Wirbelschicht 4-insbesondere bei hohem Alkaligehalt-unter Umgehung der Vorkalzinationszone 2 und des Vorwärmers 1 abgezweigt werden (Pfeil 33).Another portion of the air conveyed by the blower 26 to the cooling zone 5 can be fed to the precalcination zone 2 as additional combustion air (arrow 31). Any excess air (arrow 32) can be discarded or otherwise used. Likewise, a certain proportion of the exhaust gases from the fluidized bed 4 - in particular with a high alkali content - can be branched off bypassing the precalcination zone 2 and the preheater 1 (arrow 33).

Zur Regelung der in der Wirbelschicht 4 befindlichen Gutmenge enthält die Anlage vier Druckmeßstellen 34, 35, 36 und 37, von denen die Druckmeßstelle 34 etwa im Bereich der Guteinführung liegt, die Meßstelle 35 etwa auf 1/3 bis 1/2 der Höhe der Wirbelschicht 4, die Druckmeßstelle 36 im oberen Drittel der Wirbelschicht und die Druckmeßstelle 37 in der Abgasleitung der Wirbelschicht.To regulate the amount of material in the fluidized bed 4, the system contains four pressure measuring points 34, 35, 36 and 37, of which the pressure measuring point 34 lies approximately in the area of the introduction of the material, the measuring point 35 approximately to 1/3 to 1/2 the height of the fluidized bed 4, the pressure measuring point 36 in the upper third of the fluidized bed and the pressure measuring point 37 in the exhaust pipe of the fluidized bed.

Die vier Druckmeßstellen sind an einen Druckumformer 38 angeschlossen, der mit einem Regler 39 verbunden ist. Dieser Regeler 39 wirkt einerseits auf die Austragseinrichtung 20 (Steuerleitung 40) und andererseits auf eine Gutaufgabe-Dosiereinrichtung 41 (Steuerleitung 42).The four pressure measuring points are connected to a pressure transducer 38 which is connected to a regulator 39. This regulator 39 acts on the one hand on the discharge device 20 (control line 40) and on the other hand on a feed metering device 41 (control line 42).

Der Regler 39 hält die in der Wirbelschicht 4 befindliche Gutmenge konstant, indem beispielsweise durch die vom Regler 39 gesteuerte Austragseinrichtung 20 jeweils nur die über dem Sollwert befindliche Gutmenge aus der Kühlzone 5 und damit aus der Wirbelschicht 4 ausgetragen oder indem durch die Gutaufgabe-Dosiereinrichtung 41 jeweils eine am Sollwert fehlende Gutmenge zugeführt wird. Als Maß für die in der Wirbelschicht 4 befindlich Gutmenge wird ein von den Druckmeßstellen 34 bis 37 gelieferter Druckwert verwendet, beispielsweise die Differenz der an den Meßstellen 34 und 37 bestimmten Drücke.The controller 39 keeps the quantity of material in the fluidized bed 4 constant, for example by means of the discharge device 20 controlled by the controller 39 only discharging the quantity of material located above the setpoint from the cooling zone 5 and thus from the fluidized bed 4 or by the material feed metering device 41 In each case a quantity of good missing at the setpoint is fed. A pressure value supplied by the pressure measuring points 34 to 37 is used as a measure of the quantity of material in the fluidized bed 4, for example the difference between the pressures determined at the measuring points 34 and 37.

Zur weiteren Erläuterung der Erfindung diene folgendes Beispiel:

  • In der Wirbelschicht (einschließlich ihrer engsten Stelle im Bereich der Gut- und Brennstoffeinführung) wird eine Gasgeschwindigkeit von ca. 6 m/s und ein Lückengrad (Verhaltnis von Leervolumen zu Gesamtvolumen der Wirbelschicht) von etwa 0,65 eingestellt; in der Kühlzone beträgt die Gasgeschwindigkeit ca. 2 m/s und der Lückengrad etwa 0,4 oder weniger.
The following example serves to further explain the invention:
  • A gas velocity of about 6 m / s and a gap degree (ratio of empty volume to total volume of the fluidized bed) of about 0.65 is set in the fluidized bed (including its narrowest point in the area of the material and fuel introduction); in the cooling zone the gas velocity is approx. 2 m / s and the gap degree is approx. 0.4 or less.

Die Körnung des Saatklinkers beträgt 2 bis 4 mm; das Verhältnis Rohmehl-Saatklinker liegt bei 4:1.The grain size of the seed clinker is 2 to 4 mm; the ratio of raw flour to seed clinker is 4: 1.

Das vorgewärmte und vorkalzinierte Gut wird mit einer Temperatur von ca. 840°C in die Wirbelschicht 4 eingeführt. In dieser Wirbelschicht herrscht eine Temperatur zwischen 1300 und 1350°C. In der Kühlzone 5 wird das Gut auf eine Temperatur von 80 bis 120°C abgekühlt.The preheated and pre-calcined material is placed in the at a temperature of approx. 840 ° C Fluid bed 4 introduced. The temperature in this fluidized bed is between 1300 and 1350 ° C. In the cooling zone 5, the material is cooled to a temperature of 80 to 120 ° C.

Der Glühverlust des Rohmateriales nach dem Vorwärmer liegt bei 5%. Die Körnung des entsäuerten Rohmateriales beträgt 44% > 90/1m und 8,8% >200flm.The loss on ignition of the raw material after the preheater is 5%. The grain size of the deacidified raw material is 44%> 90 / 1m and 8.8%> 200 fl m.

Die Luftmengen können wie folgt gewählt werden; Der Kühlzone 5 werden von unten 1,00 Nm3/kg Klinker zugeführt. Hiervon gelangen 0,33 Nm3/kg KI direkt von unten her (Pfeile 23) in die Wirbelschicht, während 0,67 Nm3/kg KI seitlich (Pfeil 24) aus der Kühlzone abgezogen werden. Von diesem letzteren Teil gelangen 0,17 Nm3/kg KI als Förderluft (Pfeile 27, 28) für vorkalziniertes Gut und Brennstoff von der Seite her in die Wirbelschicht 4, während 0,5 Nm3/kg KI unmittelbar (Pfeil 31) der Vorkalzinationszone 2 zugeführt werden. Eine gleich große Luftmenge (0,5 Nm3/kg KI) gelangt als Abgase der Wirbelschicht in die Vorkalzinationszone 2 (Pfeil 9).The air volumes can be selected as follows; The cooling zone 5 is fed from below 1.00 Nm 3 / kg clinker. From this, 0.33 Nm 3 / kg of KI get directly into the fluidized bed from below (arrows 23), while 0.67 Nm 3 / kg of KI are removed from the side of the cooling zone (arrow 24). From this latter part, 0.17 Nm 3 / kg KI as conveying air (arrows 27, 28) for precalcined material and fuel enter the fluidized bed 4 from the side, while 0.5 Nm 3 / kg KI directly (arrow 31) Precalcination zone 2 are supplied. An equal amount of air (0.5 Nm 3 / kg KI) reaches the precalcination zone 2 as exhaust gases from the fluidized bed (arrow 9).

Der zwischen den Druckmeßstellen 34 und 37 gemessene Differenzdruck liegt zwischen 78 und 118 m bar, der Differenzdruck zwischen den Druckmeßstellen 35 und 37 zwischen 25 und 39 m bar.The differential pressure measured between the pressure measuring points 34 and 37 is between 78 and 118 m bar, the differential pressure between the pressure measuring points 35 and 37 between 25 and 39 m bar.

Claims (10)

1. Method of producing cement by burning pulverulent raw material in a fluidized bed into which preheated raw material, fuel, preheated air and a recycled portion of the burnt material is introduced, the material discharged from the fluidized bed being subsequently cooled in a cooling zone by a cooling air flow, characterised by the combination of the following features:
a) The preheated raw material is precalcined prior to charging into the fluidized bed in a precalcination zone with additional fuel up to a deacidification degree of 80 to 95%.
b) From the lower region of the fluidized bed the burnt material passes to a cooling zone which is formed by the part of the material pile disposed directly beneath the fluidized bed;
c) a part of the cooling air flow is introduced from below and a further part from the side into the fluidized bed;
d) the precalcined material is carried into the fluidized bed by the part of the cooling air flow introduced from the side into the fluidized bed;
e) In the lower region of the fluidized bed intended for the introduction of the precalcined material by a cross-sectional construction substantially the same void degree as in the upper region of the fluidized bed is set, preferably a void degree between 0.5 and 0.8;
f) the amount of material disposed in the fluidized bed is controlled in dependence upon a gas pressure measured in the fluidized bed.
2. Method according to claim 1, characterised in that the precalcined material is introduced into the fluidized bed with an impulse between 49 and 98 Ns.
3. Method according to claim 1, characterised in that at least a part of the fuel is introduced from the side into the fluidized bed beneath the surface of the latter, preferably substantially at the level of the supply of the precalcined material.
4. Method according to claims 1 and 3, characterised in that at least a part of the fuel is introduced into the fluidized bed from the side by a part of the cooling air flow together with the precalcined material at a plurality of points distributed preferably uniformly over the periphery of the fluidized bed.
5. Method according to claim 1, characterised in that the amount of material in the fluidized bed is controlled in dependence upon the difference between a gas pressure measured in the fluidized bed and a gas pressure measured in the exhaust gas conduit of the fluidized bed.
6. Method according to claim 1, characterised in that about 50 to 90%, preferably about 2/3, of the entire air supplied to the fluidized bed is introduced from below and about 10 to 50%, preferably about 1/3, of the air is introduced from the side into the fluidized bed.
7. Method according to claim 1, characterised in that to the preheating and precalcination zone an adjustable portion of the exhaust gases of the fluidized bed and preferably an adjustable portion of the cooling air flow are supplied whilst the remaining portion of the exhaust gases is removed from the fluidized bed bypassing the preheating and precalcination zone.
8. Apparatus for carrying out the method according to claim 1 including a shaft-like reaction chamber (3) having in the lower region a cooling zone (5) and thereabove a fluidized bed (4), furthermore a preheater (1) constructed as multi-stage couriferflow heat exchanger and having a precalcination zone (2) supplied by additional fuel (10), characterised in that at the periphery of the upper region of the cooling zone (5) at least one extraction conduit (arrow 24) is connected which via a fan (26) is connected to a pneumatic conveying conduit
(13) introducing the precalcined material from the side into the lower region of the fluidized bed (4), a conduit (arrows 29, 30) introducing a further air flow from the side into the fluidized bed (4) and preferably to a conduit (arrow 31) supplying combustion air to the precalcination zone (2) and that the clear cross-section of the reaction chamber (3) widens upwardly conically from the material introduction zone (conveying conduits 13, 14).
EP78100518A 1977-08-04 1978-07-27 Process and apparatus for making cement in a fluidized bed Expired EP0000739B1 (en)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
DE19772735140 DE2735140A1 (en) 1977-08-04 1977-08-04 Cement calcination in a fluidised bed - with outlet at the bottom and air cooled cooling zone
DE2735084 1977-08-04
DE19772735084 DE2735084A1 (en) 1977-08-04 1977-08-04 Cement calcination in a fluidised bed - with outlet at the bottom and air cooled cooling zone
DE2735140 1977-08-04
DE19782822419 DE2822419A1 (en) 1978-05-23 1978-05-23 Cement calcination in a fluidised bed - with outlet at the bottom and air cooled cooling zone
DE2822419 1978-05-23
DE2822395 1978-05-23
DE2822377 1978-05-23
DE19782822395 DE2822395A1 (en) 1978-05-23 1978-05-23 Cement calcination in a fluidised bed - with outlet at the bottom and air cooled cooling zone
DE19782822377 DE2822377A1 (en) 1978-05-23 1978-05-23 Cement calcination in a fluidised bed - with outlet at the bottom and air cooled cooling zone

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EP0000739B1 true EP0000739B1 (en) 1981-04-15

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CH381590A (en) * 1958-10-07 1964-08-31 Pyzel Robert Process for the preparation of a hydraulic cement and apparatus for its implementation
DE1767628C3 (en) * 1968-05-30 1985-03-14 Metallgesellschaft Ag, 6000 Frankfurt Process for performing endothermic processes
JPS49111926A (en) * 1973-02-26 1974-10-24
AT352430B (en) * 1975-06-17 1979-09-25 Eumig OPTICAL SIGNAL DEVICE OF ELECTRO-ACOUSTIC TRANSMISSION DEVICES
DE2528290C3 (en) * 1975-06-25 1979-09-13 Schubert & Salzer Maschinenfabrik Ag, 8070 Ingolstadt Working method and device for monitoring the spun thread on open-end rotor spinning machines

Also Published As

Publication number Publication date
JPS5434325A (en) 1979-03-13
DK347078A (en) 1979-02-05
IT7826440A0 (en) 1978-08-03
PT68379A (en) 1978-09-01
DE2860617D1 (en) 1981-05-07
CA1115297A (en) 1981-12-29
GR64304B (en) 1980-03-03
US4213790A (en) 1980-07-22
IT1097686B (en) 1985-08-31
JPS5711862B2 (en) 1982-03-06
EP0000739A1 (en) 1979-02-21

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