EP2784421B1 - Arch brick for the cylindrical inner lining of a rotary drum furnace and rotary drum furnace - Google Patents

Description

The invention relates to an arch brick according to DIN1082-4, January 2007 edition, a cylindrical inner lining of a rotary kiln, the lining containing these arching stones and a rotary kiln with the lining and the vault stones.

The warping stones, the lining and the rotary kiln are described below in a mounting / operating position of the furnace.

• eine rechteckige äußere Grundfläche AG mit den Maßen a x l
• eine rechteckige innere Grundfläche IG mit den Maßen b x l
• zwei rechteckige Seitenflächen RS1, RS2 mit den Maßen l x h
• zwei trapezförmige Stirnflächen TS1, TS 2 mit den Maßen a/b x h, wobei a/b zwei unterschiedlich lange Seiten der Stirnflächen beschreibt.

A vault stone according to standard is in FIG. 1 and has the following six areas:

• a rectangular outer base AG with the dimensions axl
• a rectangular inner base IG with the dimensions bxl
• two rectangular side surfaces RS1, RS2 with the dimensions lxh
• two trapezoidal end faces TS1, TS 2 with the dimensions a / bxh, where a / b describes two sides of the end faces of different lengths.

These vaulting stones are used for lining a rotary kiln, for example a rotary kiln for the production of cement clinker. The rectangular larger base area AG is then outside, the rotary kiln shell adjacent, while the rectangular smaller base surface IG is located inside, facing the furnace interior. The stones are arranged so that their length (I) runs in the axial direction of the furnace.

The basic installation of the vaulting stones in a rotary kiln results from the standard and the following state of the art: DE 2643412 A . DE 29921607 U1 and can be summarized as follows: The cambers are arranged in ring-like segments in the circumferential direction of the furnace next to each other. Several segments are arranged one behind the other in the axial direction of the furnace.

• eine Druckbelastung in Axialrichtung, in Richtung auf den Ofenausgang, aufgrund der Neigung des Ofens (in Richtung auf den Ofenausgang) und des Eigengewichts der Steine
• die thermische Ausdehnung des Feuerfestmaterials der Steine (am Ofeneingang eines Zement-Drehrohrofens kann die Temperatur zum Beispiel 1000°C betragen, am Ofenausgang kann sie bei ca. 1500°C liegen)
• die Rotation des Ofens
• das Gewicht und die Reibung zwischen Brenngut und Ausmauerung.

In kiln operation, the refractory bricks of the lining (brick lining) are subject to considerable mechanical stress. The following factors are important here:

• a pressure load in the axial direction, in the direction of the furnace exit, due to the inclination of the furnace (towards the furnace exit) and the dead weight of the stones
• the thermal expansion of the refractory material of the stones (at the furnace entrance of a cement rotary kiln, the temperature may be for example 1000 ° C, at the kiln outlet it may be at about 1500 ° C)
• the rotation of the furnace
• the weight and the friction between kiln and lining.

Without special measures in particular break the Wölbsteine in the furnace end facing half of the furnace. The result is frequent repair and production downtime of the furnace as well as high costs. This also applies to the rotary kiln vault in accordance with DE 2315898 A characterized in that grooves or notches are provided on the surfaces for the stone itself to decompose during use and at the operating temperature of the furnace.

The DE 299 21 607 U1 proposes to weld a metallic ring to the outer furnace shell. The ring forms a kind of counter bearing for the axial pressure described above. The ring is rectangular in cross-section, the "height" in the radial direction can be low (in practice: about 50-70mm), because the metallic material is too little temperature resistant and the temperature in the furnace increases from outside to inside.

The small contact or contact surface between ring and refractory lining stone causes a high surface pressure. The strength of the ceramic stones is often exceeded. It cracks or stones are crushed by the axial thrust within the stone lining.

According to DE 29921607U1 also counter-bearing with triangular cross-section are proposed. In this case, the associated inclined surface (which serves as a bearing surface for the vaulting stones arranged in front of it) extends from the outside (adjacent to the furnace shell) inwards and in the direction of the furnace outlet. Also, the attachments of the metal wedges are welded to the furnace shell, because screw at the high axial loads do not have sufficient strength.

Although these wedges have a larger bearing surface, the problems of insufficient temperature resistance remain. Accordingly, the inclination angle of the abutment is limited to <20 degrees, so that the metal parts can still be sufficiently protected by the radially inner adjacent refractory bricks.

The invention has for its object to offer a solution for the described axial loads in a rotary kiln, which avoids the disadvantages mentioned.

• es entfällt ein separater Montageschritt
• die Temperaturbeständigkeit der feuerfesten Auskleidung ist sehr viel größer als die der Metallteile
• die größere Feuerfestigkeit (english: refractoriness) macht es möglich, Steine beliebiger Größe und Form zu verwenden
• die Kosten des Systems sind geringer im Vergleich mit den beschriebenen Keilen und Ringen.

The invention replaces the known metallic counter bearings and alters the geometry of the refractory domes used for the refractory lining. The fact that no metal parts are necessary, there are several advantages:

• it eliminates a separate assembly step
• the temperature resistance of the refractory lining is much greater than that of the metal parts
• The greater refractoriness makes it possible to use stones of any size and shape
• the cost of the system is lower compared to the wedges and rings described.

First, it should be noted that the axial pressure within the refractory ceramic furnace liner can not be eliminated. The invention has recognized, however, that the function of an abutment (to compensate for the axial pressure within the lining) can be taken over by the refractory lining itself when the lining stones are split in the radial direction, thereby forming inclined surfaces between adjacent stone elements.

These inclined surfaces, formed almost in situ, are responsible for deflecting and distributing the axial compressive load within the refractory furnace lining at least partially in the radial and circumferential directions. This reduces the axial load on the stones behind them (towards the exit of the stove) and overall results in a much more uniform load distribution within the bricks of the lining.

By using refractory ceramic "counter bearings", there are no restrictions in terms of size and design. The stone sections can therefore be larger (deeper) than the metal rings, in particular in the radial direction. Retrofitting into existing systems is possible because the stone sections used can complement each other geometrically to a vault of conventional design and replace it completely.

In its most general embodiment, the invention relates to a vault according to DIN 1082-4, January 2007 edition, which extends along at least one parting surface which extends from the base AG to an end face TS2 or another base surface IG, in at least two discrete (separate) stone Sections is divided.

The core idea of the invention is therefore to divide a known vault in several parts (two, three or more). The parts of this set can again form-fit together to form a vault stone, namely exactly form-fitting or with (expansion) joints between the individual sections and / or so that expansion joints to adjacent vaulting arise. These expansion joints can be filled during or after the lining with seals, in particular elastic seals such as fiber materials.

Due to the described course of the "separation surface" between stone sections of a set it follows immediately that this separation surface (parting line) extends obliquely (inclined) in the radial direction of the furnace. In other words, the geometry and arrangement of at least one stone section can be similar to the geometry and arrangement of a metallic fixture according to DE 29921607 U1 be.

This inclined surface is rising (viewed from the furnace entrance to the furnace exit and from the furnace wall to the furnace interior) and also serves according to the invention as a ramp surface for the lining stones arranged in front of it (in the direction of the furnace entrance). The axial pressure of the stones is thus compensated by this "separation surface", which has the function of an abutment.

The inclined surface serves to redirect the axial thrust of the lining to a considerable extent in the radial and circumferential direction of the cylinder-like rotary kiln. This reduces the mechanical load on this stone part and at the same time there is a relatively even load distribution in the adjacent region of the furnace lining.

If cambering stones according to the invention are placed next to one another in order to form a complete lining ring, the result of the ring geometry is an introduction of the force into the metallic furnace shell and thus a further pressure relief for the refractory material.

• die sehr viel höhere Temperaturbeständigkeit
• dadurch können die Fläche und der Winkel der Schrägfläche (zum axial verlaufenden Ofenmantel) größer sein
• es entfällt die Verwendung unterschiedlicher Werkstofftypen mit völlig unterschiedlichen thermischen Ausdehnungskoeffizienten

In comparison with the metal parts according to the prior art, additional advantages arise, such as:

• the much higher temperature resistance
• As a result, the surface and the angle of the inclined surface (to the axially extending furnace shell) can be larger
• it eliminates the use of different types of materials with completely different thermal expansion coefficients

The stone sections may be made of conventional refractory materials, such as alumina, magnesia, silicon carbide, zirconia, etc. materials.

The stone section, which serves to absorb the axial thrust load, can be made of a material with particularly high compressive strength, in particular high hot compressive strength, for example from an offset (English: batch) having the following composition (all figures in% by mass) : Example A: Example B: Al ₂ O ₃ : 40-95 (85) MgO: 80-95 (90) SiO ₂ : 2 - 50 (12) Al ₂ P ₃ : 2 - 15 (4) SiC: 0-50 Cr ₂ O ₃ : 0 - 15 ZrO ₂ : 0 - 40 SiO ₂ : 0.1 - 2 (0.5) Cr ₂ O ₃ : 0-10 Fe ₂ O ₃ : 0.1-10 (4) Fe ₂ O ₃ : 0-3 (0.5) CaO: 0.1-3 (1) Other: 0 - 3 (2.5) other: 0 - 3 (0.5)

The numbers in brackets refer to a concrete possible composition.

According to one embodiment, the separating surface between adjacent stone parts extends at an angle ≥20 degrees to the outer base area AG, which angle can also be much larger, for example ≥25 degrees, ≥30 degrees or ≥40 degrees. Of course, the angle must be less than 90 degrees to fulfill the desired task as a "thrust bearing" or casserole bearing. The angle is, in one embodiment, ≤75 degrees, often ≤60 degrees or ≤45 degrees.

• Figur 2 zeigt eine Seitenansicht auf ein Set aus zwei Stein-Abschnitten, die zusammen ein Wölbstein gemäß DIN 1082-4 (Fig. 1) bilden. Der rechte Stein-Abschnitt 10 weist zwei gegenüberliegende gleiche Seitenflächen RS1, RS2 in Trapezform auf, von denen nur die eine (RS2) zu sehen ist.
  Der linke Stein-Abschnitt 12 ist korrespondierend zum Abschnitt 10 geformt, so dass sich beide Steinabschnitte 10, 12 form- und kraftschlüssig zu einem Wölbstein gemäß DIN 1082-4 (Ausgabe Januar 2007) ergänzen.
  Die Steinabschnitte 10,12 können in separaten Formen gepresst werden. Sie lassen sich auch herstellen, wenn ein konventioneller Wölbstein zwischen seinen Grundflächen AG und IG im rechten Winkel zu den Seitenflächen RS1, RS2 durchgeschnitten wird.
  Die Seitenflächen RS1, RS2 des Stein-Abschnitts 10 haben zwei rechte Winkel, einen spitzen und einen stumpfen Winkel. Die rechte trapezförmige Stirnfläche TS2 ist unverändert geblieben, eine neue trapezförmige Stirnfläche TS1* wird von der beschriebenen Trennfläche TF zwischen den Stein-Abschnitten 10, 12 gebildet. Die innere (in der Figur die untere) Grundfläche IG* und die äußere (in der Figur obere) Grundfläche AG* sind Teilflächen der entsprechenden Grundflächen AG, IG des Wölbsteins gemäß Norm. Die Schrägfläche/Trennfläche TF zwischen den Stein-Abschnitten 10,12 verläuft unter einem Winkel α von ca. 45 Grad zu den Grundflächen AG*, IG* und von einer Grundfläche AG zur anderen Grundfläche IG.
  Die linke Steinhälfte 12 ist so geformt, dass sie zusammen mit dem Teil 10 unter Formschluss einen kompletten Wölbstein ergibt.
• Fig. 3 zeigt eine Ausführungsform, bei der die Trennfuge TF zwischen zwei Stein-Abschnitten 10,12 im Wesentlichen von der äußeren Grundfläche AG zur hinteren Stirnfläche TS2 verläuft, so dass der Stein-Abschnitt 10 in der Seitenansicht angenähert ein Dreieckprofil besitzt. Die Trennfläche TF ist - wie bei Fig. 2- planar, sie könnte aber auch leicht gewölbt oder mit unterschiedlichen Neigungswinkeln ausgebildet sein. Der Winkel (α) zwischen der Grundfläche AG* des Teils 10 und der Schrägfläche/Trennfläche TF beträgt ca. 35Grad.
  Um zu verhindern, dass Kanten abplatzen, können diese abgekantet werden, wie mit K in Fig. 3 dargestellt. Die grundsätzliche Geometrie und der grundsätzliche Erfindungsgedanke ändern sich dadurch nicht.
  Wie Figur 3 zeigt weist der zweite Stein-Abschnitt 12 in der Seitenansicht die Form eines Fünfecks auf, so dass beide Teile 10,12 nach Zusammenbau wieder einen kompletten Wölbstein ergeben.
  Die in der Figur gezeigt Stirnfläche TS2** des Teils 12 ist gegenüber der Stirnfläche TS2* des Teils 10 etwas versetzt. Dadurch entsteht zu einem in Axialrichtung des Ofens benachbarten Wölbstein eine Dehnungsfuge, die mit einer Dichtung, wie einem Fasermaterial, ausgefüllt werden kann.
• Bei der Variante gemäß Figur 4 ist die Trennfuge TF abgekantet, so dass sich für den oberen rechten Teil 10 in der Seitenansicht eine Trapezform ergibt und die Seitenflächen RS1*, RS2* des korrespondierenden Teils 12 jeweils sechs Ecken haben. Ansonsten ist das Beispiel gemäß Figur 4 ähnlich dem gemäß Fig. 3.
  In Figur 4 ist eine mögliche weitere Unterteilung des Steinabschnitts 12 dargestellt, und zwar gestrichelt, wobei die dadurch gebildete Trennfläche TF* ähnlich verläuft wie die Teilung der Abschnitte 10,12 in Fig. 2.

The oblique surface within the vaulted stone format can be made by dividing a vaulted stone into 2 stone sections. However, embodiments with 3 or more stone sections are basically possible, as the following figures show, which illustrate possible geometries of stone sections and vaulting stones:

• FIG. 2 shows a side view of a set of two stone sections, which together form a vault stone according to DIN 1082-4 ( Fig. 1 ) form. The right stone section 10 has two opposite equal side surfaces RS1, RS2 in trapezoidal shape, of which only one (RS2) can be seen.
  The left-hand stone section 12 is shaped corresponding to the section 10, so that both stone sections 10, 12 complement each other positively and non-positively to form a vault in accordance with DIN 1082-4 (January 2007 edition).
  The stone sections 10, 12 can be pressed in separate molds. They can also be produced when a conventional vault is intersected between its base areas AG and IG at right angles to the side surfaces RS1, RS2.
  The side surfaces RS1, RS2 of the stone portion 10 have two right angles, one acute and one obtuse. The right trapezoidal face TS2 has remained unchanged, a new trapezoidal face TS1 * is formed by the described interface TF between the stone sections 10,12. The inner (in the figure the lower) base surface IG * and the outer (in the figure upper) base AG * are partial surfaces of the corresponding base areas AG, IG of the vault in accordance with standard. The inclined surface / separating surface TF between the stone sections 10, 12 extends at an angle α of approximately 45 degrees to the base surfaces AG *, IG * and from one base surface AG to the other base surface IG.
  The left half of the stone 12 is shaped in such a way that together with the part 10 it produces a complete arch in positive engagement.
• Fig. 3 shows an embodiment in which the parting line TF between two stone sections 10,12 substantially from the outer base surface AG extends to the rear end face TS2, so that the stone section 10 has approximately a triangular profile in the side view. The interface TF is - as in Fig. 2 - planar, but it could also be slightly curved or formed with different angles of inclination. The angle (α) between the base AG * of the part 10 and the inclined surface / separating surface TF is about 35 degrees.
  To prevent the edges from flaking off, they can be folded as with K in Fig. 3 shown. The fundamental geometry and the fundamental idea of the invention do not change as a result.
  As FIG. 3 shows the second stone section 12 in the side view in the shape of a pentagon, so that both parts 10,12 after reassembly give a complete vault.
  The end face TS2 ** of the part 12 shown in the figure is slightly offset with respect to the end face TS2 * of the part 10. As a result, an expansion joint, which can be filled with a seal, such as a fibrous material, is formed to form a vault adjacent to the axial direction of the furnace.
• In the variant according to FIG. 4 the parting line TF is bent so that a trapezoidal shape results for the upper right part 10 in the side view and the side surfaces RS1 *, RS2 * of the corresponding part 12 each have six corners. Otherwise, the example is according to FIG. 4 similar to that according to Fig. 3 ,
  In FIG. 4 a possible further subdivision of the stone portion 12 is shown, in dashed lines, wherein the separating surface formed TF * similar to the division of the sections 10,12 in Fig. 2 ,

As mentioned earlier, the axial pressure in the refractory lining increases in the direction of the furnace exit. It is therefore useful to provide in this area a ring of the invention vault stones.

• Anordnung mehrerer Ringe (Reihen) aus den neuen Wölbsteinen in Axialrichtung des Ofens hintereinander, und zwar direkt hintereinander oder mit Abstand. Im letztgenannten Fall können entweder konventionelle Ausmauerungssteine zwischen den Ringen/Reihen mit erfindungsgemäßen Wölbsteinen vorgesehen werden oder es wird eine Dehnungsfuge dazwischen angeordnet, die mit einem elastischen Fugenmaterial wie einer Fasermatte, ausgefüllt sein kann.
• Eine weitere Alternative besteht darin, hinter einer Steinreihe aus erfindungsgemäßen Wölbsteinen einen konventionellen Metallring als zusätzliche Rückhalteeinrichtung einzubauen, der dann kleiner konfektioniert werden kann, da er deutlich kleinere Kräfte aufnehmen muss.
• Ausbildung eines Rings aus Wölbsteinen, wobei die neuen (mehrteiligen) Wölbsteine mit konventionellen (einteiligen) Wölbsteinen abwechselnd verlegt sind.
• Die Steinreihen können formschlüssig oder mit Abstand zueinander, auch in Kombination mit konventionellen Steinformaten ( DE 2643412 A , DE 29921607 U1 ) verlegt werden.
• Die Steine können trocken oder mit Mörtel verlegt werden.
• Die Trennfläche zwischen benachbarten Stein-Abschnitten kann ungleich 90 Grad zu den Seitenflächen erfolgen, planar oder nicht planar sein.
• Gegenüberliegende Oberflächen (RS1, RS2; RS1*, RS2*) eines Stein-Abschnitts können eine Trapezform, eine Dreieckform, eine Fünfeckform aufweisen und gleich oder ungleich gestaltet sein.

The following variants are within the scope of the invention:

• Arrangement of several rings (rows) of the new vault in the axial direction of the furnace in a row, directly behind each other or at a distance. In the latter case, either conventional masonry blocks can be provided between the rings / rows of domes according to the invention or an expansion joint can be interposed therebetween which can be filled with an elastic jointing material such as a fiber mat.
• A further alternative is to install a conventional metal ring as an additional retaining device behind a row of stones made of vault blocks according to the invention, which can then be made smaller, since it has to absorb significantly smaller forces.
• Formation of a ring of vaulted stones, whereby the new (multipartite) arching bricks are laid alternately with conventional (one-piece) vaulting stones.
• The rows of stones can be form-fitting or spaced apart, even in combination with conventional stone formats ( DE 2643412 A . DE 29921607 U1 ).
• The stones can be laid dry or with mortar.
• The interface between adjacent stone sections may be at least 90 degrees to the side surfaces, planar or nonplanar.
• Opposite surfaces (RS1, RS2, RS1 *, RS2 *) of a stone section may have a trapezoidal shape, a triangular shape, a pentagon shape, and may be the same or different.

• die Auskleidung verläuft zwischen einem Ofeneingang an einem ersten Ende des Drehrohrofens und einem Ofenausgang an einem zweiten Ende des Drehrohrofens
• die Auskleidung besteht im Wesentlichen aus hintereinander angeordneten ringförmigen Segmenten, wobei
• mindestens ein ringförmiges Segment zumindest überwiegend aus Wölbsteinen gemäß Anspruch 1 gebildet ist, die in Umfangsrichtung mit ihren Seitenflächen RS1, RS2 aneinander und mit ihren größeren Grundflächen AG außen liegen, wobei
• die Trennflächen TF der Wölbsteine sich von der äußeren Grundfläche AG in Richtung auf die den Ofenausgang erstrecken.

Accordingly, a cylindrical inner lining of a rotary kiln generally has the following features:

• the liner extends between an oven inlet at a first end of the rotary kiln and an oven outlet at a second end of the rotary kiln
• The lining consists essentially of successively arranged annular segments, wherein
• at least one annular segment is formed at least predominantly of domes according to claim 1, which lie in the circumferential direction with their side surfaces RS1, RS2 to each other and with their larger base areas AG outside, said
• the separating surfaces TF of the cambers extending from the outer base AG in the direction of the furnace exit.

These cambers can be changed as described above.

The invention also includes an industrial rotary kiln with a cylindrical inner lining of the type described above.

FIG. 5 shows - in a highly schematic representation - a vertical longitudinal section through a cement rotary kiln with an outer furnace shell 20 and radially inside arranged, cylindrical refractory lining 30 between a furnace inlet OE and a furnace outlet OA. in the axial direction (arrow A) are consecutively several rings 30a ... 30z conventional vault stones arranged, as is known. About 1 m in front of the furnace exit OA, a ring 30w can be seen, which is formed from vaulting stones shaped according to the invention, namely vaulted stones FIG. 2 ,

The separation surface / inclined surface TF between the stone parts 10,12 assumes the function of an abutment to at least partially absorb the axial pressure (P _A ) in front of the furnace entrance OE arranged Völbsteine and divert into the furnace wall 20 and adjacent Wölbsteine.

FIG. 6 shows a perspective, partially cutaway interior view of a portion of the refractory lining 30 of a rotary kiln in the range of a stone row 30w of inventive multi-part domes analog Fig. 3 ,

In the block row 30x behind a conventional steel ring 40 is installed in accordance with the prior art as an additional restraint against the axial pressure P _A. But this is optional.

Claims (12)

1. An arch brick in accordance with DIN 1082-4, edition January 2007, which is separated into two discrete brick parts (10, 2) along at least one separation plane (TF), which extends from base (AG) to a front face (TS2) or a further base (IG).
2. The arch brick according to claim 1, the separation plane (TF) of which extends by an angle ≥20 degrees to said base (AG).
3. The arch brick according to claim 1, the separation plane (TF) of which extends by an angle ≤75 degrees to said base (AG).
4. The arch brick according to claim 1, the separation plane (TF) of which extends by an angle ≤60 degrees to said base (AG).
5. The arch brick according to claim 1, with at least one brick part (10, 12) having two opposed surfaces (RS1*, RS2*), each of trapezoidal shape.
6. The arch brick according to claim 1, with at least one brick part (10, 12) having two opposed surfaces (RS1*, RS2*), each of triangular shape.
7. The arch brick according to claim 1, with at least one brick part (10, 12) having two opposed surfaces (RS1*, RS2*), each of pentagonal shape.
8. The arch brick according to claim 5, 6 or 7, wherein the opposed surfaces (RS1*, RS2*) are Identical.
9. The arch brick according to claim 1, which separation plane (TF) being planar.
10. Cylindrical Inner lining (30) of an industrial rotary kiln with the following features:

    a) the lining (30) extends between a kiln entrance (OE) at a first end of the rotary kiln and a kiln exit (OA) at a second end of the rotary kiln,

    b) the lining (30) is substantially made of ring-like segments (30a....30z) arranged one behind the other, wherein

    c) at least one ring-like segment (30w) is made at least predominantly of arch bricks according to claim 1, which abut each other in a peripheral direction with their side faces (RS1, RS2) and which large bases AG are arranged to the outside, wherein

    d) said separation planes (TF) of said arch bricks extend from the large base (AG) towards the kiln exit (OA).
11. Lining according to claim 10 with arch bricks according to one of claims 2-9.
12. Industrial rotary kiln with a cylindrical inner lining (30) according to claim 10 or 11.

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