EP0367956B1 - Lifter for cooling drums, rotary drum furnaces or similar devices - Google Patents

Abstract

In the treatment of a granular substance, which is capable of being at least partly scattered, in a cooling drum, satellite cooler, rotary drum furnace, drum-type drier or similar devices, in order to increase the thermal efficiency, such as, for example, the cooling effect, in the critical heating zone without having to tolerate a perceptible increase in the dust load of the gas flow as well as an increase in the dimensions of the rotary drum, rotary drum lifters are proposed according to the invention, which rotary drum lifters, as viewed in the drum cross-section, consist of roughly hemispherical curved elements (13) which project arch-like into the drum interior and, in their apex region at their two front edges, each have a rim (19, 20) directed towards the inner wall of the drum, reducing the free curved cross-sectional area and preventing the scattering of the lifted substance located in the curved elements. <IMAGE>

Description

The invention relates to internals for tubular coolers, satellite coolers, rotary kilns, drum dryers or the like to improve the heat transfer between a granular, at least partially scatterable material such as. B. cement clinker and a gas stream such. B. cooling air.

The task of a cooler z. B. tube cooler or satellite cooler, it is the hot product coming from an oven z. B. cement clinker to cool as much as possible and at the same time heat the cooling air flowing through the cooler as much as possible before it usually enters the furnace as so-called secondary air and is used there as combustion air. The degree of cooling depends on the heat transfer between the product and the cooling / secondary air. While the product amount, the amount of air, the product temperature, the air temperature, each time it enters the cooler, as well as the product properties such. B. the granulometry can not be influenced by the cooler, the cooler operation is essentially determined by three factors: size of the heat transfer surfaces, residence time of the product in the cooler, dust formation and dust cycles.

It is known to increase the efficiency of a tube cooler or satellite cooler by installing lifting blades or lifting strips made of wear-resistant steel, which lift the hot cement clinker and drop it into the cooling air flow, thereby achieving an intimate contact of the cooling air with the clinker. Such internals which scatter the hot material are so far only in the middle and on the discharge side End area of the cooling tube has been used. Under no circumstances should such internals be used in the hot zone of the cooler adjacent to the oven, because in this hot zone, in which the temperature difference between hot material and cooling air is also greatest, scattering of the good material by the cooling air flow must be avoided, because otherwise The cooling air is loaded with dust, which reduces the heat transfer in the cooler hot zone and which is undesirably transported back into the sintering furnace via the cooling air / secondary air, which leads to an impairment of the economy of the overall process. It is also known to improve the heat transfer by means of so-called cross fittings. These internals are preferably used for very fine material that should be spread as little as possible. The use of such cross fittings in the hot zone of a cooler would lead to mechanical problems and would be disadvantageous for the good distribution over the cross section. Therefore, in the hot zone of the cooling tube, only mushroom-shaped or conical internals have been used so far, which essentially have the task of mixing the good material kidney lying in the cooling tube without lifting action, in order to achieve better heat transfer via radiation by creating new good surfaces. The one for good heat transfer The required large good material surface area is not achieved in this way, so that the heat transfer, particularly in this hot zone of the cooler, is still in need of improvement.

The invention has for its object to increase the thermal efficiency, in particular in the critical hot zone, in the treatment of a granular at least partially scatterable material in a tube cooler, satellite cooler, rotary kiln, drum dryer or the like, without a noticeable increase in the dust load of the gas stream and an increase in the Have to accept the dimensions of the rotary tube.

This object is achieved according to the invention with rotary tube internals, which are characterized in advantageous embodiments in claims 1 to 9.

The internals attached to the inner wall of the rotary tube consist, according to the invention, of approximately semicircular, arch-like arch elements protruding into the tube inside, which in their apex region have one each directed towards the inner wall of the tube at their two end edges, narrowing the free arc cross-sectional area and spreading the lifted in the arch elements Good material prevent the edge of the board.

The rotary tube internals to be installed in particular in the hot zone of the rotary tube thus essentially have the following advantages:

By dividing the total good material kidney lying in the rotary tube into many individual good material kidneys, the number of which corresponds to the number of arch elements installed in the rotary tube, the heat-radiating material surface is enlarged and the heat transfer is thereby considerably improved. Each arch element is designed in such a way that the amount of good material that has entered at the end can initially bend freely on both sides and the amount of good material that is subsequently in the arch element remains in the arch for about half a turn of the rotary tube.

It is crucial according to the invention that the spreading of good material is effectively prevented by the fact that the arch elements in their apex area have a rim facing the inner wall of the pipe, which narrows the free arc cross-sectional area, i.e. the rim edges of each arch element on both sides prevent this in particular in the Hot zone undesirable spreading of the good material. In order to improve the accumulation effect due to the inclination of the rotary tube, according to the invention it can be used to discharge the crop the edge of the rotating pipe facing the rim of each arch element is higher in its board height, that is to say it is higher-sided than the other edge of the board (facing the good entry of the rotating pipe). After reaching the opposite side of the rotary tube after half a turn of the rotary tube, the good material runs out of the arch element, without being scattered, onto the material-free tube wall opposite the total good material kidney, which in turn leads to an enlarged good material surface area and an improved heat transfer. During about half a turn of the rotary tube, the good material is simultaneously circulated in the arch elements, which can be favored by strips which, at least in the apex area of the arch elements, are arranged approximately parallel to the axis of the rotary tube in order to constantly create new good material surfaces.

Fig. 1

in perspektivischer Darstellung ein erfindungsgemäßes, an der Innenwandung eines Drehrohres zu befestigendes Bogenelement;

Fig. 2

einen Querschnitt eines Drehrohres, z. B. Rohrkühlers, mit darin eingebauten Bogenelementen, und

Fig. 3

schematisch die Draufsicht auf eingebaute Bogenelemente gesehen in Richtung des Pfeiles III der Fig. 2.

The invention and its further features and advantages are explained in more detail with reference to the exemplary embodiments shown schematically in the figures. It shows:

Fig. 1

a perspective view of an arch element to be fastened to the inner wall of a rotary tube;

Fig. 2

a cross section of a rotary tube, for. B. tube cooler, with built-in arc elements, and

Fig. 3

schematically the top view of built-in arch elements seen in the direction of arrow III of FIG. 2nd

Fig. 2 shows the cross section through a tube cooler (10) which rotates in the direction of the arrow (11) about its axis. In the cooler (10) z. B. hot cement clinker, which comes from a cement clinker furnace upstream of the cooler, is cooled and at the same time the cooling air flowing in countercurrent to the good material is heated before it enters the furnace as so-called secondary air. 2 is directed in the main flow direction of the hot material. This hot good material lies as a so-called good material kidney (12) with an inclined surface in the lower region of the cooling tube (10) on its inner wall. According to the invention, the tube cooler (10) has internals which consist of so-called curved elements (13, 14, 15, etc.) which are attached to the inner wall of the tube in a detachable and replaceable manner. In the top view of FIG. 3, in which the arrow (11) indicate the direction of rotation of the tube cooler (10) and the arrow (16) the main flow direction of the hot material, z. B. the arch elements (13) and (14) of FIG. 2 can be seen in plan view, and it is in Fig. 2 can also be seen that the arc elements arranged in a circle of adjacent circles (a), b), c), d)) are each offset on the end face in such a way that goods transport lanes (17 ) are formed, which run obliquely to the cylinder surface lines of the rotary tube (10).

Fig. 1 shows individually drawn enlarged and in perspective an arch element, seen against the main flow direction (16) of the material to be cooled. The direction of rotation of the rotary tube is indicated here by the arrow (11). The internals fastened to the inner wall of the rotary tube (10), which consist of the arc elements (13, 14, 15, etc.) protruding in the tube cross-section as seen in the tube cross-section, each have in their apex area at their two front edges one to the tube inner wall directed, narrowing the free arch cross-sectional area and preventing the spreading of the lifted goods (18) located in the arch elements on the edge of the board. For example, the curved element (13) has at the end the rim (19) facing the product outlet of the rotary tube (10), which can be seen in FIG. 1, and the panel edge (20) which faces the product inlet of the rotary tube, can be seen in FIG. 2 to the outlet the rim (19) facing the rim (19) of each arch element can advantageously have a higher rim in its rim height than the other rim (20 facing the inlet of the rotating tube) in order to achieve a sufficient accumulation effect for the respective in despite the inclination of the rotating tube in the material flow direction (16) to achieve a higher amount of good material in the arch elements.

As is clear from Fig. 1, the arch element (13) or the other arch elements are composed of two parts, which are detachably connected to each other in the region of their crown, z. B. by simple hook connection, bolt connection or other hinge connection (21). The arch elements advantageously each consist of two halves, of which the front half (22) seen in the direction of rotation (11) of the rotary tube (10) is narrower from end to end than the other half (23) of each arch element. The narrow half (22) of each arch element has a stepped recess (24) on its end edge facing the material outlet of the rotary tube (FIG. 1), as a result of which raised material material runs out of the individual arc elements in the region of the rotary tube opposite the material element kidney (12) (10) is facilitated.

Is the arch element z. B. formed in three parts, the mechanically highly stressed middle part is advantageously interchangeable.

So that the fine material is not even lifted from the arch elements, the broad half (23) (seen in the direction of rotation (11) of the rotary tube rear half) of some or all of the arch elements can have through openings (26) such as, for. B. have slots for the passage of the fine material located in the respective arch element. At least in the apex region of the arch elements, strips extending approximately parallel to the axis of the rotary tube and circulating the good material located in the arch element can be arranged, of which the strip (27) is shown in dashed lines in FIG. 1 in the arch element (13). These strips can also have a promotional or stowage effect on the goods, e.g. B. when emptying the respective arch element.

The mode of operation of the rotary tube internals according to the invention is again illustrated as follows:
Each arch element (13, 14, 15, etc.) is designed so that the quantity of good material that has occurred z. B. (18) can initially bend freely on both sides and the amount of material thereafter located in the arch element (18a) remains in the arc element for about half a cooler revolution. Scattering of good material is effectively prevented by the onboard ends (19, 20) on both ends, the onboard edge (19), as already mentioned, pointing towards the good outlet being advantageously higher-sided due to the inclination of the cooling tube. After reaching the opposite side of the rotary tube after about half a turn of the rotary tube, the good material can run out of the narrow half (22) of each curved element. In this way, the good material, without being scattered into the cooling air flow, reaches the material-free inner wall of the rotary tube (10) opposite the good material kidney (12), which in turn leads to an enlarged material surface and thus to an improved heat transfer. During the approximately half a turn of the cooling tube (10), the material in the arch elements is simultaneously turned over by the strips (27) in order to create new heat-radiating surfaces.

The fact that the arc elements consist of two halves (22) and (23), for. B. cast from heat-resistant cast steel, assembly is facilitated and thermal expansion are controlled. The arch elements are expediently attached to the rotary tube against Wear-protected holding pieces welded into the rotary tube casing, namely at two points on the wide half (23) and at one point (28) on the narrow half of the bend (22), so that there is a 3- for the entire bend (13) Point attachment results. The arch elements themselves as well as their wear protection can consist of steel, cast iron, ceramic or the like wear-resistant material.

For all zones of the tube cooler, only a basic built-in shape, namely the curved element shape, needs to be used. Different versions are selected depending on the desired function (non-scattering / scattering). All fittings are interchangeable and can be combined with one another, taking the material qualities into account, of course. The bow element halves can be replaced individually and can also be replaced individually when worn. All fastenings (both elbow halves with each other and on the inner tube wall) are designed in the same way. At least in the hot zone of the tube cooler, the elbow elements or the associated tube wall parts can be provided with additional wear protection. The installation density of the elbow elements according to the invention in the rotary tube is variable depending on the requirement.

From the hot zone to the cold zone of the tube cooler (10), the built-in elbow elements can be designed so that they do not scatter the good material in the hot zone, but allow a gradually increasing material scatter at the transition to the cold zone, by z. B. the front side wheels of the arch elements are formed ever lower and / or an oblique arc (25) is selected. The elbow elements are fastened to the inner wall of the rotary tube on holding pieces projecting from it by means of bolts or screws. Through bolts in the pipe jacket are not necessary. Holding pieces that do not have built-in arch elements have the function of spiral strips for the good material kidney (12). The arch elements can be cylindrically or spherically curved or composed of flat surfaces.

The material dwell time in the rotary tube is essentially influenced by the density of the built-in arrangement, the height of the front-side rim wheels (19, 20) of the arch elements, the lanes formed (17) between the built-in components, the direction of spreading for the inlet or outlet, the arrangement and number of conveyor strips, etc.

The rotary tube internals according to the invention create the possibility of tube coolers, Rotary tube ovens or the like - even afterwards - easy to optimize, since the final properties of the product to be treated such as B. density, porosity, thermal conductivity, grain size distribution in advance are only predictable to a limited extent. The conception of rotary tube internals according to the invention makes it possible to favorably influence the dwell time of the good material in the rotary tube, the dust formation and dust cycles and thus ultimately also the quality of the heat transfer between good material and gas by means of a wide variety of variable arrangement, combination, exchange etc.

Claims (9)

1. Carrier elements for cooling drums, satellite coolers, rotary furnaces, drum-type dryers or the like for improving the heat transfer between a granular and at least partly scatterable material such as cement clinker and a stream of gas such as cooling air, characterised in that the carrier elements, which are secured directly or indirectly to the inner wall of the drum or tube, are arcuate elements (13, 14, 15) which project into the drum or tube and are approximately semicircular as seen in the drum or tube cross-section and which have a flange (19, 20) at each leading edge in their crown region, each flange extending towards the inner wall of the drum or tube and constricting the free cross-section of the arcuate member so as to prevent the material lifted by the arcuate elements from being scattered.
2. Carrier elements for rotary drums or tubes according to claim 1, characterised in that the flange (19) of each arcuate element facing the outlet for material from the rotary drum or tube is higher than the respective other flange (20) (facing the inlet for material into the rotary tube).
3. Carrier elements for rotary drums or tubes according to claim 1 or 2, characterised in that the arcuate elements (13, 14, 15) are uniformly distributed around the inner wall of the drum or tube and are releasably secured thereto.
4. Carrier elements for rotary drums or tubes according to claim 3, characterised in that the arcuate elements are disposed in circles with adjacent circles (a), (b), (c), (d) having their end faces offset from one another so that lanes (17) for conveying material are formed between adjacent arcuate elements in the direction of rotation (11) of the drum or tube, the lanes extending at an angle to the cylindrical generatrices of the rotary drum or tube (10).
5. Carrier elements for rotary drums or tubes according to any one of claims 1 to 4, characterised in that the arcuate elements each comprise at least two parts which are releasably interconnected in their crown region.
6. Carrier elements for rotary drums or tubes according to claim 5, characterised in that the arcuate elements each comprise two halves, the front half (22) as seen in the direction (11) of rotation of the tube (10) being narrower from end face to end face than the other half (23) of each arcuate element.
7. Carrier elements for rotary drums or tubes according to claim 6, characterised in that the narrow half (22) of each arcuate element is formed by a stepped recess (24) in its leading edge facing the outlet (16) for material from the rotary drum or tube.
8. Carrier elements for rotary drums or tubes according to claims 6 or 7, characterised in that the wide part (23) (the rear half as seen in the direction of rotation (11) of the rotary drum or tube) of some or all the arcuate elements is formed with through-apertures (26) in the inlet region so that the very fine material in the respective arcuate element can flow through.
9. Carrier elements for rotary drums or tubes according to any one of claims 1 to 8, characterised in that ridges (27) for circulating the material in the arcuate element are disposed at least in the crown region of the arcuate elements (13) and extend approximatley parallel to the axis of the rotary drum or tube.

Images