EP0606918A1 - Rotary drum furnace inlet - Google Patents

Abstract

In this rotary-drum furnace inlet (2), a chute-type material inlet trough (8), which is firmly attached to the inlet housing (4), projects with its front lower end into the material inlet opening (3) of an associated rotary drum. In order to construct the bottom of the material inlet trough (8) in a particularly resistant fashion, said bottom is composed of a number of hollow body segments (10, 10') which are constructed approximately in the shape of boxes, can have a cooling medium applied to them, are closely juxtaposed in the circumferential direction, are fastened to the inlet housing (4) by at least one external fastening point and have longitudinal side walls (10e, 10F) which are convex and concave in cross-section and interlock in a fitting fashion.

Description

The invention relates to a rotary kiln inlet according to the preamble of claim 1.

Rotary kiln systems are used for burning, sintering and other heat treatment of mineral goods (e.g. cement materials, lime or the like), ores and similar bulk materials. The fuel to be subjected to heat treatment in the rotary kiln is fed into the inlet end of a rotary tube rotating about its longitudinal axis at the rotary kiln inlet. In these versions, which are generally known in practice, a fixed inlet housing is arranged upstream of the rotary tube inlet end in the direction of the material to be conveyed. A chute-like material inlet trough is generally firmly attached to this inlet housing, the front, lower end of which, in the direction of the material to be conveyed, protrudes into the material inlet opening of the rotary tube or rotary tube inlet end, the bottom of this material inlet trough having a circular cross section having a small radial distance from the peripheral edge of the material inlet opening . The bottom of the material inlet troughs of these known designs is generally made in the form of a plate in a welded or cast design. In practice, it has been shown time and again that in these known rotary kiln inlets, the troughs in particular, and in particular their bottoms, are exposed to particular stresses which result from wear due to contact with the firing material and from thermal stresses and the resulting cracks.

In a largely similar known embodiment (DE-C-32 45 702) one wants an improved thermal Protection and an increased service life in the area of the outlet end of the said troughs are achieved primarily by the fact that the metallic jacket of the trough in its end region facing the rotary tube has an inwardly directed, double-walled collar composed of individual hollow body support segments, the chambers of which are formed by webs Open outside of the trough and can be cooled from the outside by introducing a cooling medium. Here, the bottom of the material inlet trough is formed in its area facing the rotary tube by the assembled support segments and in its area facing away from the rotary tube by a separate holding device, onto which the support segments are attached and which forms a separate extension of the arrangement of the support segments. The individual support segments are also fixed by means of clamp connections or wedge connections, over which the refractory lining of the material inlet trough is attached. This known design of the Guteinlaufmulde proves due to the different and precisely matched parts (support segments and multi-part holding device) as relatively complex in their construction, and in addition, the support segments in the event of wear and tear can only be relatively cumbersome and relatively time-consuming - from the rotary tube side forth - be replaced.

The invention is therefore based on the object to provide a rotary kiln inlet of the type required in the preamble of claim 1, which is characterized by a particularly robust design of the material inlet trough and its trough bottom, and also a relatively simple assembly (and thus also disassembly) of the trough bottom should be made possible.

This object is achieved by the features specified in the characterizing part of claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

In contrast to the known designs described above, in the rotary kiln inlet according to the invention the entire bottom of the material inlet trough can essentially only be composed of the box-shaped hollow body segments which are designed in the sense of unit segments for different rotary tube diameters. In this way, on the one hand, a considerable structural simplification is already achieved in that the bottom of the material inlet mule can essentially only be formed from the same hollow body segments (unit segments), which also creates a particularly good precondition for the individual hollow body segments to have an interior inside them corresponding cooling medium (e.g. cooling gas, in particular cooling air, or cooling liquid, in particular cooling water) can be acted upon in a suitable manner. On the other hand, the hollow body segments lying closely together in the circumferential direction of the approximately arc-shaped trough cross section, with suitable support on or in the fixed inlet housing, are each fastened to this inlet housing by at least one external fastening point, in such a way that they form sufficiently far into the material inlet opening while forming the trough bottom protrude at the inlet end of the rotary tube enough to accommodate the firing material flowing down the material inlet trough to be able to insert far into the rotary tube inlet end of the rotary tube furnace. Due to the outer attachment points of the hollow body segments on the inlet housing, there is also a particularly simple assembly and disassembly of individual hollow body segments from the outside.

The formation of the individual hollow body segments in the sense of unit segments for different rotary tube diameters is particularly favored by the fact that the two longitudinal side walls of each hollow body segment, which are oriented approximately in the direction of the firing material, are essentially partially cylindrical, with - viewed in cross section of the segment - one longitudinal side wall having a convex cross-sectional shape and the other longitudinal side wall has a corresponding concave cross-sectional shape such that the opposing longitudinal side walls of two adjacent hollow body segments engage in one another in a suitable manner. This results in an approximately swiveling interlocking of two adjacent hollow body segments, so that the circular arc cross-section of the bottom of the material inlet trough - with hollow body segments of the same size or the same size (unit segments) - can be adapted within relatively wide limits to different diameter sizes of rotary tubes. These options therefore not only result in a relatively simple manufacture of hollow body segments for different rotary tube diameters, but also in a simplified storage of replacement segments.

The individual hollow body segments are curved in an arc shape in the trough circumferential direction in an advantageous manner, ie they can be adapted in a suitable manner to the radius of the be adapted to approximately circular material inlet opening at the rotary tube inlet end. It is also particularly advantageous that these hollow body segments can be mounted (and thus also dismantled) from the rear of the inlet housing opposite the furnace interior. This design together with the outer fastening points of the hollow body segments create the extremely favorable possibility of being able to replace a possibly worn or otherwise damaged hollow body segment relatively easily axially from the outside (in the case of the designs which are generally known in practice, on the other hand, the plates of the bowl bottom are from the inside of the furnace assembled or disassembled, which is not only inconvenient and cumbersome, but also means working in a relatively dirty area.

In a particularly advantageous manner, the box-shaped hollow body segments are only open on their outside (rear side) axially opposite the inside of the furnace, it being possible for the cooling medium to be applied to them from this open outside. There is thus the possibility, in a particularly favorable manner, of providing forced cooling of the individual hollow body segments from the outside, for example by means of cooling air with the aid of fans or also by means of other suitable cooling media and aids, in order to cool these hollow body segments and thus the entire trough base in a suitable and appropriate manner from the inside, as opposed to the side opposite the heat from the furnace.

The hollow body segments provided according to the invention for the trough bottom can in principle be welded or be made as individual castings. In the latter case, there are particularly low manufacturing costs, especially since all hollow body segments can be designed identically using the same cast models, and even the same hollow body segment sizes can be used for different rotary kiln sizes (diameters), if appropriate.

In the practical implementation of a rotary kiln inlet, it is generally preferred to at least line the surfaces that come into contact with the firing material with refractory material. With regard to the material inlet trough, its surface, which serves as a conveying surface for the firing material and is inclined against the rotary tube, will be provided with a sufficiently thick lining layer made of refractory material. It is particularly advantageous if, on the front of each hollow body segment, approximately in extension of the lower body wall, a web-like projection pointing into the furnace interior is integrally formed and a sufficiently thick lining layer made of a suitable layer on the top of the gutter formed for the supply of fuel and on this web-like projection refractory material is provided.

Fig.1

eine Teil-Längsschnittansicht durch einen erfindungsgemäßen Drehrohrofeneinlauf;

Fig.2

eine Teil-Querschnittsansicht etwa entlang der Linie II-II in Fig.1;

Fig.3

eine Stirnansicht einer ersten Ausführungsform eines Hohlkörpersegments;

Fig.4

eine Längsschnittansicht durch das Hohlkörpersegment, etwa entlang der Linie IV-IV in Fig.3;

Fig.5

eine Stirnansicht von in Umfangsrichtung eng aneinander anliegenden Hohlkörpersegmenten, gemäß Ausführung der Fig.3 und 4;

Fig.6

eine Stirnansicht einer etwas abgewandelten zweiten Ausführungsform der Hohlkörpersegmente;

Fig.7

eine Längsschnittansicht entlang der Linie VII-VII in Fig.6.

The invention is explained in more detail below with the aid of a few exemplary embodiments illustrated in the drawing. Show in this drawing

Fig. 1

a partial longitudinal sectional view through a rotary kiln inlet according to the invention;

Fig. 2

a partial cross-sectional view taken approximately along the line II-II in Figure 1;

Fig. 3

an end view of a first embodiment of a hollow body segment;

Fig. 4

a longitudinal sectional view through the hollow body segment, approximately along the line IV-IV in Figure 3;

Fig. 5

an end view of closely adjacent hollow body segments in the circumferential direction, according to the embodiment of Figures 3 and 4;

Fig. 6

an end view of a somewhat modified second embodiment of the hollow body segments;

Fig. 7

a longitudinal sectional view along the line VII-VII in Figure 6.

1 and 2, the general structure of the rotary kiln inlet according to the invention will first be explained. This rotary kiln inlet contains a rotary tube 1, which represents an essential part of the associated rotary kiln, can be designed and arranged in a manner known per se and is accordingly driven to rotate about its longitudinal axis. This rotary tube 1 has a conically tapering inlet end 2 with an approximately circular material inlet opening 3. Furthermore, this rotary kiln inlet contains an inlet housing 4 which is only partially indicated and which is arranged upstream of the rotary tube inlet end 2 in the direction of conveyance of the kiln (arrows 5). In the illustrated embodiment, the inlet housing 4 contains an upper housing part 6 and a lower housing part formed by a type of trough 7.

A chute-like material inlet trough 8 is fixedly attached to the inlet housing 4, the front, lower end 8a of which protrudes far enough into the material inlet opening 3 of the rotary tube to convey fuel to be heat-treated in the rotary tube 1 - according to the arrows 5 - into the rotary tube inlet end 2. This material inlet trough 8 has a bottom 9 which, with an approximately circular cross-section (cf. front view of the trough bottom 9 in FIG. 2), has a small radial distance a from the peripheral edge of the material inlet opening 3.

As shown in FIGS. 1 and 2, the entire bottom 9 of the material inlet trough 8 is now preferably composed of a number of approximately box-shaped hollow body segments 10 which lie closely against one another in the circumferential direction of the circular trough bottom cross section. As will be explained in more detail in part, each hollow body segment 10 has at least one outer fastening point for fastening to the inlet housing 4. In the embodiment illustrated in FIG. 1 in longitudinal section, the hollow body segment 10 has a rear horizontal fastening tab 11, with which it is fastened, preferably screwed, to the underside of the upper housing part 6, and a rear vertical lower fastening tab 12, which is attached to a corresponding vertical outer one Wall part of the housing trough 7 attached, preferably screwed. With this attachment, each hollow body segment 10 is supported on an approximately horizontal surface of the lower housing trough 7 and projects freely from there through the Good inlet opening 3 into the rotary tube inlet end 2.

As will also be explained in more detail, all of the hollow body segments 10 can be acted upon from the outside with a suitable cooling medium, as is indicated in FIG. 1 by dashed arrows 13.

The first embodiment of the hollow body segments 10, which is also used in FIGS. 1 and 2, will be explained in more detail with reference to the individual representations in FIGS. 3 to 5.

In FIG. 3 (and partly also in FIG. 2) it can be seen that each hollow body segment 10 is curved in an arc shape in the trough circumferential direction. As the representations in FIGS. 1 and 4 show, it is generally preferred that the hollow body segments 10 are only open on their rear or outer side 10a axially opposite the furnace interior (preferably on this entire rear or outer side). In this way, the interior of each hollow body segment 10 can be exposed to an appropriate cooling medium (e.g. cooling gas, cooling air, cooling liquid or cooling water) extremely intensively, preferably by means of suitable forced cooling with the aid of a fan, blower, pump or the like as indicated by the arrows 13 in FIG.

The illustration in FIG. 1 also shows that the individual hollow body segments 10 of the trough base 8 can be assembled or disassembled relatively easily from the rear of the inlet housing 4 opposite the interior of the furnace.

The fastening tabs 11 and 12 intended for fastening the hollow body segments 10 to the inlet housing 4 are preferably cast in one piece on the hollow body segments 10 if the latter are, as is preferred, made of cast iron. Accordingly, it can be seen above all in FIGS. 1 and 4 that the upper body wall 10b of each hollow body segment 10 has at its rear edge the horizontally rearwardly projecting upper outer fastening tab 11 and the lower body wall 10c at its rear edge has an approximately vertical downward angle has lower fastening tab 12.

A web-like projection 14 pointing into the furnace interior is integrally formed on the front or front wall 10d of each hollow body segment 10 pointing into the furnace interior, approximately as an extension of the lower body wall 10c. As shown and preferred, this web-like projection 14 is made significantly thicker in material than the lower body wall 10c, as a result of which it is more resistant to abrasion. As is customary per se, the upper side of the material inlet trough 8, which is designed for supplying fuel to the rotary tube 1, is provided with a sufficiently thick lining layer 15 made of conventional refractory material. This lining layer 15 is now preferably extended to the front in the firing material conveying direction (arrows 5), in such a way that it is also applied to the previously explained projection 14 of each hollow body segment 10, so that these hollow body segments 10 offer particularly good protection both against mechanical and also have chemical wear on the part of the kiln and the furnace exhaust.

In the embodiment of the hollow body segments 10 illustrated in particular with reference to FIGS. 3 to 5 and in part also with reference to FIG. 2, the two longitudinal side walls 10e and 10f of each hollow body segment 10, which are oriented approximately in the direction of the firing material (arrows 5), are in the cross section of the segment considered - essentially designed as a partially cylindrical hollow body walls, as shown especially in Figures 3 and 5. According to this, the one, first longitudinal side wall 10e has a convex cross-sectional shape and the other, second longitudinal side wall 10f has a corresponding concave cross-sectional shape such that - cf. 5 - the opposing longitudinal side walls 10f and 10e of two adjacent hollow body segments 10 fit into one another, ie the radius of curvature of the outer circumferential side of the convex first longitudinal side wall 10e essentially corresponds to the radius of curvature of the second longitudinal side wall 10f, viewed in cross section or in the end view of the hollow body. so that these two side walls 10e and 10f each of two adjacent hollow body segments 10 can not only fit together, but also form a kind of swivel joint. If, in this embodiment, the hollow body segments 10 are in close contact with one another to form the trough base 9, then the swiveling intermeshing of two adjacent hollow body segments 10 allows the circular arc cross section of the product inlet trough or of the trough base 9 to be adjusted within wide limits to different diameter sizes of rotary tubes. In other words, this means that for rotating tubes 1 of significantly different diameters, hollow body segments 10 of the same size or of the same type are curved in the sense of unit segments (in accordance with the above explanations). can be used. This has a particularly advantageous effect both for the production (for example cast models) and for the storage of replacement segments.

The exemplary embodiment for the formation of the hollow body segments illustrated with reference to FIGS. 6 and 7 represents only a relatively minor modification of the previously described embodiment. A significant difference of this exemplary embodiment for the hollow body segments 10 ′ shown with reference to FIGS. 6 and 7 compared to the previously described in detail An example can be seen in the fact that an approximately vertically downwardly angled fastening tab 12 'is provided only at the rear edge of the lower body wall 10'c. This means that each hollow body segment 10 '- in relation to the rotary kiln inlet according to FIG. 1 - is only fastened, preferably screwed, to a vertical wall section of the lower housing pan 7 with the lower fastening tab 12', which has a sufficiently long circumferential extent. However, sufficient support should be provided for the lower body wall 10'c on the top of the tub 7.

It is sufficient for the upper body wall 10'b if it is only sufficiently supported on the corresponding underside of the upper housing part 6. So that this support can take place largely without tilting, it is preferred to provide on the upper side of the upper body wall 10'b of each hollow body segment 10 'upwardly projecting contact projections 16, which are individual, appropriately distributed small knobs or only two extending in the longitudinal direction short ribs can act, as shown in Fig. 7. By providing these contact projections 16, unevenness or inaccuracies on the underside of the upper housing part 6 can be compensated well. These contact projections 16 can be provided in one piece on the hollow body segments, preferably cast on.

It should also be mentioned in this connection that the previously described contact projections 16 can also be provided in the case of the first embodiment of the hollow body segments 10 described with reference to FIGS. 1 to 5.

Claims (10)

Including rotary kiln inlet a) a rotary tube (1) rotatable about its longitudinal axis with an inlet end (2) having an approximately circular material inlet opening (3), b) a fixed inlet housing (4) which is arranged upstream of the rotary tube inlet end in the firing material conveying direction (5), c) a chute-like material inlet trough (8) fixedly attached to the inlet housing (4), the front, lower end (8a) of which protrudes into the material inlet opening (3) of the rotary tube and whose bottom (9) has a small radial distance (a ) to the peripheral edge of the material inlet opening (3) and has a number of approximately box-shaped hollow body segments (10, 10 ') which lie closely against one another in the peripheral direction of the trough bottom cross section characterized by the following features: d) the bottom (9) of the material inlet trough (8) is essentially composed of the hollow body segments (10, 10 ') which are designed in the sense of unit segments for different rotary tube diameters and which have at least one outer fastening point for fastening to the inlet housing (4); e) the two longitudinal side walls (10e, 10f) of each hollow body segment (10), which are oriented approximately in the firing direction (5), are essentially partially cylindrical, with one longitudinal side wall (10e) having a convex cross-sectional shape and the other - viewed in cross section of the segment Long side wall (10f) has a corresponding concave cross-sectional shape such that the opposing long side walls (10e, 10f) of two adjacent hollow body segments engage in one another in a suitable manner. Rotary kiln inlet according to claim 1, characterized in that the hollow body segments (10, 10 ') are curved in an arcuate manner in the bowl circumferential direction and can be fitted from the rear of the inlet housing (4) opposite the inside of the furnace. Rotary kiln inlet according to claim 1, characterized in that the hollow body segments (10, 10 ') are only open on their outside axially opposite the inside of the furnace, wherein the cooling medium can be applied to this outside of the furnace. Rotary kiln inlet according to claim 3, characterized in that cooling gas, in particular cooling air, or cooling liquid, in particular cooling water, is provided as the cooling medium. Rotary kiln inlet according to Claim 1, characterized in that the upper body wall (10b) of each hollow body segment (10) has an outer fastening tab projecting horizontally to the rear at the rear edge (11) and the lower body wall (10c) has on its rear edge an angled down outer fastening tab (12). Rotary kiln inlet according to Claim 1, characterized in that an outer fastening tab (12 ') which is angled downwards is provided only at the rear edge of the lower body wall (10'c) of each hollow body segment (10'). Rotary kiln inlet according to claim 1, characterized in that on the front of each hollow body segment (10, 10 ') approximately in extension of the lower body wall (10c, 10'c), a web-like projection (14) pointing into the furnace interior is integrally formed and that a lining layer (15) made of refractory material is provided on the upper side of the material inlet trough (8) designed for the supply of fuel and on these web-like projections (14) Rotary kiln inlet according to claim 1, characterized in that on the upper body wall (10'b) of each hollow body segment (10 ') upwardly projecting contact projections (16) are provided, which abut the fastening side of the inlet housing (4, 6) facing this upper body wall . Rotary kiln inlet according to claim 1, characterized in that the hollow body segments are made as castings. Rotary kiln inlet according to claim 1, characterized in that the hollow body segments are made in a welded design.

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