This application is a U.S. National Stage Entry of International Patent Application Serial Number PCT/EP2019/082348, filed Nov. 25, 2019, which claims priority to German Patent Application No. DE 10 2018 220 727.5, filed Nov. 30, 2018, the entire contents of both of which are incorporated herein by reference.
The present disclosure generally relates to kilns for firing cement clinker.
In a kiln for firing cement clinker, such as, for example, a rotary kiln, protective segments are usually used for sealing the kiln wall and for holding the inner lining of the kiln. Such protective segments are provided at the end region of the kiln at which the fired clinker leaves the kiln. Extremely high temperatures of approximately 1200° C. to 1450° C. prevail in this region, for which reason cooling of the protective segments is necessary. However, known air cooling systems are not sufficient in the case of protective segments made, for example, of cast steel, with the result that thermally induced abrasive wear occurs already after approximately one year and leads to a high maintenance outlay and frequent downtimes of the kiln.
A protective segment for a kiln in the cement industry is known from DE 296 18 528 U1, for example.
Thus, a need exists for a protective segment that has lower thermally induced wear, which reduces downtime and maintenance outlay of kilns.
Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents. Moreover, those having ordinary skill in the art will understand that reciting “a” element or “an” element in the appended claims does not restrict those claims to articles, apparatuses, systems, methods, or the like having only one of that element, even where other elements in the same claim or different claims are preceded by “at least one” or similar language. Similarly, it should be understood that the steps of any method claims need not necessarily be performed in the order in which they are recited, unless so required by the context of the claims. In addition, all references to one skilled in the art shall be understood to refer to one having ordinary skill in the art.
According to a first aspect, a kiln for firing cement clinker comprises a tubular rotary drum, which can be rotated about its central axis, wherein the rotary drum has a discharge end, at which the cement clinker leaves the kiln, a protective segment, which is attached at the discharge end and has an outward-facing wear surface and an inward-facing cooling surface, wherein the kiln has a cooling device for generating a cooling air flow, which flows along the cooling surface of the protective segment. The cooling surface has profile bodies which are of pin-shaped design, with the result that they preferably cause turbulence in the cooling air flow.
A burner for firing the clinker is preferably mounted in the kiln, which burner is mounted at least partially inside the rotary drum. The burner is preferably mounted in the vicinity of the discharge end of the rotary drum, and therefore the material to be fired is moved toward the burner within the rotary drum and slowly heated. At the discharge end of the rotary drum, the clinker therefore has a very high temperature of approximately 1200-1400° C.
The kiln preferably has a plurality of protective segments, which are arranged annularly adjacent to one another and preferably form the end face of the discharge end of the rotary drum. The cooling air flow is used to cool the protective segments. The cooling device preferably generates a cooling air flow which flows radially and/or in the circumferential direction of the rotary drum, in particular of the discharge end of the rotary drum. The cooling air flow preferably flows along the cooling surface of the protective segment, in particular parallel to the cooling surface.
The wear surface of the protective segment faces outward, in particular outward in the axial direction with respect to the rotary drum, and is preferably arranged in such a way that the clinker flows along the wear surface of the protective segment as it leaves the kiln. The cooling surface faces inward, in particular in the axial direction of the rotary drum, and does not come into direct contact with the clinker. The cooling surface preferably faces in the direction of the cooling device. The cooling device has, in particular, a cooling channel for directing the cooling air, wherein the cooling surface preferably faces in the direction of the cooling channel and, in particular, forms a wall surface of the cooling channel.
The cooling surface has pin-shaped profile bodies, which preferably extend orthogonally with respect to the cooling surface, in particular in the axial direction of the rotary drum. As an option, the pin-shaped profile bodies are connected to one another, for example via connecting webs, which are arranged between two adjacent profile bodies. As an example, about 20-60%, preferably 30-40%, in particular a maximum of 50%, of the cooling surface is occupied by profile bodies. The profile bodies preferably have a length which is greater than the thickness and width of the profile body.
Turbulence should be interpreted to mean regions of turbulent flow. In contrast to laminar flow, turbulent flow ensures better mixing of the flow. This has the effect that the cooling air flowing past the cooling surface can better absorb and carry away the heat emitted by the cooling surface. Overall, the pin-shaped profile bodies ensure more efficient cooling of the cooling surface of the protective segment.
According to a first embodiment, the profile bodies have an angular, in particular quadrangular, diamond-shaped or rectangular cross section. In the case of flows of cooling air along the cooling surface, profile elements having an angular cross section ensure deflection of the cooling air flow, with the result that turbulence is generated within the flow. According to a further embodiment, the profile bodies have a round, in particular circular, cross section.
According to a first embodiment, the cooling surface with the profile bodies has a surface at least twice as large, compared with a cooling surface without profile bodies. An enlarged surface of the cooling surface ensures improved heat transfer from the cooling surface to the cooling air.
According to a further embodiment, the profile bodies are uniformly spaced apart from one another. It is likewise conceivable for the profile bodies to have different spacings with respect to one another.
According to a further embodiment, the profile bodies are arranged parallel to one another. This enables the cooling surface to be produced easily and leads to small pressure losses in the gap region.
According to a further embodiment, the profile bodies are each spaced apart from one another, a gap thus being formed between two profile bodies. The cooling air preferably flows along the gaps formed between the profile bodies and is deflected within these gaps by the profile bodies, with the result that turbulence is generated within the cooling air flow.
According to a further embodiment, the gaps between the profile bodies form an undulating profile. The profile bodies are preferably arranged in such a way that the gaps between the profile bodies have an undulating shape. This enables reliable generation of turbulence within the cooling air flow.
According to a further embodiment, the cooling surface has a plurality of profile bodies, wherein some profile bodies have a round, in particular circular, cross section and some profile bodies have an angular, in particular quadrangular, diamond-shaped or rectangular cross section. The profile bodies having the angular cross section are preferably arranged offset with respect to the profile bodies having the round cross section.
According to a further embodiment, the profile bodies have an angular cross section, wherein an edge of each angular profile body points in the direction of flow of the cooling air flow. At the edge of the profile bodies, the cooling air flow is deflected, thus ensuring that an at least partially turbulent flow is produced.
According to a further embodiment, the cooling device has a cooling channel for directing the cooling air in the direction of the cooling surface. The cooling channel preferably extends in the circumferential direction of the rotary drum around the discharge end of the rotary drum and is arranged concentrically to the rotary drum. The preferably annular cooling channel borders on the cooling surface of the protective segment, in particular in the axial direction. The cooling device preferably has a fan which blows cooling air into the cooling channel.
According to a further embodiment, the cooling device has a guide element, which divides the cooling channel into a supply channel for supplying cool cooling air and a discharge channel for discharging heated cooling air. The guide element is preferably arranged at a distance from the cooling surface of the protective segment, with the result that cooling air flows from the supply channel along the cooling surface and subsequently into the discharge channel.
The protective segment preferably has a fastening region, which is fixedly connected, in particular screwed, to the discharge end of the kiln. The fastening region extends, for example, at an angle of approximately 30-90°, preferably 40-85°, in particular 50-80°, to the cooling surface.
Arranged inside the rotary drum there is, in particular, an inner lining which comprises a plurality of bricks, and wherein the fastening region rests against at least one brick and is fixedly connected to the latter.
The kiln furthermore has a cooling device 26 for cooling the discharge end 24 of the rotary drum 22. The cooling device 26 comprises a blower 28, preferably a fan, for generating cooling air. The cooling air is conducted through a line shown schematically in
During operation of the cement plant, preheated raw meal is introduced into the kiln 10 and transported therein in the direction of the discharge end 24 and the burner by the rotation of the rotary drum 22, with the result that the raw meal is preferably uniformly heated and fired to form cement clinker. The fired clinker falls via the discharge end 24 of the rotary drum 22 onto the static grate 30 of the cooler 12 arranged underneath and slides from the latter in the direction of the conveying unit 32. By means of the conveying unit 32, the clinker is transported in the conveying direction and, at the end of the conveying unit, falls from the cooler 12 into the comminuting device 34, in which the clinker is comminuted. It is likewise conceivable for a conveyor belt onto which the clinker falls to be arranged downstream of the cooler 12. The comminuting device 34 is only optional.
The discharge end 24 of the rotary drum 22 has, for example, two circumferential rows of bricks 36 which are arranged raised relative to the remaining bricks 36 of the inner lining. By way of example, a protective segment 38 is arranged between the at least one brick 36 and the rotary drum 22. The protective segment 38, in particular a plurality of protective segments, forms the discharge edge of the rotary drum 22, via which the clinker is conveyed and from which the clinker falls into the cooler 12. The kiln 10 comprises a plurality of protective segments 38, which are arranged circumferentially adjacent to one another and together form the overall discharge edge running around the circumference of the rotary drum 22. A cooling channel 40 for cooling the discharge end 24 of the rotary drum 22 is arranged around the circumference of the discharge end 24 of the rotary drum 22. The cooling channel 40 has a wall 42 which extends at a distance around the discharge end 24 of the rotary drum 22. The wall 42 extends at least partially concentrically with respect to the rotary drum 22 and has an end region 48 which extends radially outward at an angle of, for example, 20-50°, preferably 30-40°, in particular 45°, to the central axis of the rotary drum 22. The cooling channel 40 is connected to the fan 28, and therefore cooling air is conducted from the fan 28 into the cooling channel 40, for example via a line 50, preferably in the axial direction of the rotary drum 22. Each protective segment 38 has an outward-facing wear surface 44 and an inward-facing cooling surface 46. The wear surface 44 preferably faces in the direction of the burner, in particular in the direction of the outlet region 14 of the kiln 10, in which the temperatures are approximately 1200° C. to 1450° C., wherein the wear surface 44 is in direct contact with the temperatures in the outlet region 14. In particular, the clinker emerging from the rotary drum 12 flows along the wear surface 44 into the cooler 12. The wear surface 44 extends vertically, for example, in particular in the radial direction of the rotary drum 22. The protective segment preferably forms the outermost surface in the axial direction of the rotary drum 22, in particular the end face of the rotary drum 22. The cooling surface 46 faces in the direction of the cooling channel 40 and forms the end wall of the cooling channel 40, wherein the cooling air, which initially flows axially in the cooling channel 40, impinges on the cooling surface 46 of the protective segment 38 and is deflected on the latter in such a way that it flows at least partially or completely in the circumferential direction of the rotary drum 22 and preferably directly along the cooling surface 46 of the protective segment 38. In particular, the cooling air absorbs the heat of the cooling surface 46 and then flows from the cooling surface 46 out of the cooling channel 40 in the axial direction of the rotary drum 22. The protective segment 38 preferably rests with its upper end against at least one brick 36 and with its lower end against the wall 42 of the cooling channel 40, and therefore the cooling channel 40 is separated from the ambient air by the protective segment 38. The protective segment 38 is preferably fastened to the wall 42 by means of a fastening element 52. The fastening element 52 is, for example, a sleeve or a sleeve segment with a radially-inward pointing edge, wherein the fastening element 52 is screwed to the wall 42. The edge of the sleeve or sleeve segment rests against the outside of the protective segment 38 and clamps the latter between the wall 42 and the edge, thus preventing movement, in particular in the axial direction of the rotary drum 22. The protective segment 38 and the wall 42 of the cooling channel 40 are fixedly connected to the rotary drum 22, and therefore the protective segment 38 and the wall 42 of the cooling channel 40 rotate with the rotary drum 22.
The kiln 10 furthermore has, by way of example, an outer wall 54, which is preferably part of the outlet region 14 of the kiln 10 and, by way of example, extends in the vertical direction in
A second leg of the protective segment 38 extends orthogonally with respect to the fastening region 60 and rests against a brick 36 in the installed position of
The profile bodies 58 of the above-described profiles of
Number | Date | Country | Kind |
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10 2018 220 727.5 | Nov 2018 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/082348 | 11/25/2019 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2020/109199 | 6/4/2020 | WO | A |
Number | Name | Date | Kind |
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3682453 | Powell | Aug 1972 | A |
4212632 | Conrad | Jul 1980 | A |
9746243 | Devroe | Aug 2017 | B2 |
20030131973 | Nair | Jul 2003 | A1 |
20120255311 | Miyake | Oct 2012 | A1 |
20140091453 | Mori et al. | Apr 2014 | A1 |
Number | Date | Country |
---|---|---|
101 984 318 | Mar 2011 | CN |
105674730 | Dec 2017 | CN |
2229951 | Jul 1973 | DE |
296 18 528 | Jan 1997 | DE |
102018220727 | Jun 2020 | DE |
1580509 | Sep 2005 | EP |
1580509 | Sep 2005 | EP |
2315536 | Feb 1998 | GB |
WO-2004089842 | Oct 2004 | WO |
WO-2013093212 | Jun 2013 | WO |
Entry |
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English Translation of International Search Report issued in PCT/EP2019/082348, dated Feb. 12, 2020. |
Number | Date | Country | |
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20220018599 A1 | Jan 2022 | US |