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EP-4739967-A1 - COOLER FOR COOLING HOT BULK MATERIAL, IN PARTICULAR CEMENT CLINKER

EP4739967A1EP 4739967 A1EP4739967 A1EP 4739967A1EP-4739967-A1

Abstract

A device for cooling hot bulk material, in particular cement clinker, by means of a cooling gas (80). A cooling grate (3) conveys a layer of the bulk material (9) and is flowed through by cooling gas. The cooling grate comprises a number of bars (4) which are alternately moved forwards and back in the conveying direction and on which the bulk material (9) lies. Adjacent bars (4) are moved at the same time in the forward stroke and at different times in the return stroke. According to the invention, at least one bar is formed as a hybrid bar (4*) with a varying configuration of the bar surface (60), having a middle portion (42) with a smooth bar covering (6) and also a beginning portion (41) and/or end portion (42) comprising a protective layer (5) of bulk material (90) located on the bar surface (60). This provides protection from wear. This produces an increased friction coefficient for the bulk material as compared with the middle portion. Omitting the protective layer in the middle portion, which extends over at least half the length of the hybrid bar, has the effect of reducing the pressure loss for the cooling gas and reducing problematic compacting of the bulk material in the return stroke. Along with decreasing operating expenditure, the cooling effect is improved.

Inventors

  • BOCK, UWE
  • SPRINZ, UWE
  • WOLTERS-KACKMANN, Corinna

Assignees

  • Claudius Peters Projects GmbH

Dates

Publication Date
20260513
Application Date
20240703

Claims (20)

  1. 1. Device for cooling hot bulk material (9), in particular cement clinker, by means of a cooling gas (80), which has a cooling grate (3) through which cooling gas flows and conveys a layer of the bulk material from a feed end (31) in a conveying direction (14) to a discharge end (32), wherein the cooling grate (3) comprises a plurality of planks (4) which are alternately moved forwards and backwards by a stroke length in the conveying direction, the drive (37) of which is controlled in such a way that at least two adjacent planks (4) are moved simultaneously in the forward stroke and non-simultaneously in the return stroke, wherein the planks (4) form a substantially flat support surface (30) for the bulk material (9), characterized in that at least one plank is designed as a hybrid plank (4*) with a different design of the plank surface (60), which has - a central section (42) with a smooth plate covering (6), the central section (42) extending over at least half the length of the hybrid plank (4*), and - immediately adjacent to the middle section (42) a start section (41) and/or end section (42) comprising a protective layer (5) made of bulk material (90) arranged on the plank surface (60), whereby an increased coefficient of friction with the bulk material is formed compared to the middle section (42).
  2. 2. Device according to claim 1, characterized in that the initial and/or the end section (41, 42) with the protective layer (5) each has a length which is at least 0.5 times the maximum stroke length (39), in particular at least 0.9 times, and preferably at most 12 times, in particular at most 6 times, the maximum stroke length (39).
  3. 3. Device according to claim 2, characterized in that the initial section (41) has a greater length than the end section (43).
  4. 4. Device according to one of the preceding claims, characterized in that receiving troughs (45) for the protective layer (5) made of bulk material (90) are provided in the initial and/or end section (41, 42), which are preferably provided with subdivisions in the longitudinal and/or transverse direction.
  5. 5. Device according to one of the preceding claims, characterized in that the plate surface (60) in the middle section (42) is at the same level as the surface formed by the protective layer (5) in the initial and/or end section (41, 42).
  6. 6. Device according to one of the preceding claims, characterized in that planks (4) which are not hybrid planks have a smooth plate covering (6).
  7. 7. Device according to one of the preceding claims, characterized in that additional planks (4**) can be provided which are continuously provided with the protective layer (5), which are preferably arranged laterally at the edge.
  8. 8. Device according to one of the preceding claims, characterized in that at least one edge plank is designed as a hybrid plank (4*), preferably at least one plank immediately adjacent to the edge plank is not designed as a hybrid plank, but is in particular provided with a consistently smooth plate covering.
  9. 9. Device according to claim 7 or 8, characterized in that the additional plank (4**) or the hybrid plank (4*) is arranged on that lateral edge which has an increased proportion of a fine fraction of the bulk material (5), wherein preferably at least one immediately adjacent plank is not designed as a hybrid plank, but is in particular provided with a continuously smooth plate covering.
  10. 10. Device according to one of claims 7 to 9, characterized in that when the cooling grate (3) is arranged downstream of a rotary kiln (2) which rotates in a direction of rotation (21), the plank of the cooling grate (3) on the edge remote from the direction of rotation is designed as an additional plank (4**) or hybrid plank, namely the left plank in the conveying direction (14) in the case of a rotary kiln (2) rotating clockwise in the conveying direction (14) or vice versa.
  11. 11. Device according to one of the preceding claims, characterized in that a majority of the planks of the device are designed as hybrid planks (4*), preferably all of them.
  12. 12. Device according to one of the preceding claims, characterized in that grate plates (7) are provided for the plank surface (40), which have a plurality of cooling gas passage openings, in particular longitudinal slots (78) lying in the conveying direction, for a cooling gas outlet.
  13. 13. Device according to claim 4 or claim 12, characterized in that the grate plates (7) and/or receiving troughs (45) are designed as exchangeable modular units for the planks.
  14. 14. Device according to one of the preceding claims, characterized in that the cooling grate (3) in the conveyor device (14) is divided into several modular sections (I, II, III), each of which comprises a longitudinal section of the planks with its substructure and can be arranged one behind the other to form the planks.
  15. 15. Device according to claim 14, characterized in that the length of the modular sections (I, II, III) is dimensioned such that it corresponds to the length of one of the start/end sections (41, 43) or an integer multiple thereof, in particular twice.
  16. 16. Device according to one of the preceding claims, characterized in that an interchangeable extension bracket (49) is provided on the end section (43) of the respective plank, which forms an extension of the plank surface (40) for the bulk material (9) and is not ventilated.
  17. 17. Device according to one of the preceding claims, characterized in that, seen transversely to the conveying direction (14), the planks are designed differently, preferably planks with an increased coefficient of friction at least in sections on at least one of the side edges of the cooling grate (3) and planks with a smooth surface in the middle and/or on the other side edge.
  18. 18. Cooling arrangement for cooling hot bulk material (9), in particular cement clinker, by means of a cooling gas (80), which comprises a cooling section with at least two cooling grates (3, 3', 3") arranged one behind the other in a conveying direction, each of which conveys a layer of the bulk material (9) from a feed end (31) in a conveying direction (14) to a discharge end and through which cooling gas (80) flows, wherein the cooling grate (3, 3', 3") has a plurality of planks (4) which are alternately moved forwards and backwards in the conveying direction by a stroke length, the drive (37) of which is controlled in such a way that at least two adjacent planks (4) are moved simultaneously in the forward stroke and non-simultaneously in the return stroke, wherein the planks (4) form a substantially flat support surface (30) for the bulk material (9), characterized in that at least one of the cooling grates (3, 3', 3") has at least one plank at the beginning and/or end of the cooling section which is designed as a hybrid plank (4*) according to one of the preceding claims or which is continuously covered with a protective layer (5) made of bulk material (90).
  19. 19. Arrangement according to claim 18, characterized in that at least one further cooling grate (3, 3', 3") has exclusively planks with a smooth plate covering (60) with the exception of edge planks, which can be provided without or at least partially with a protective layer (5) of loose material.
  20. 20. Arrangement according to claim 18 or 19, characterized in that the cooling grates are designed according to one of claims 1 to 17.

Description

Device for cooling hot bulk material, in particular cement clinker The invention relates to a device for cooling hot bulk material, in particular cement clinker, by means of a cooling gas. The device comprises a cooling grate which conveys a layer of the bulk material from a feed end in a conveying direction to a discharge end and through which cooling gas flows, on which the bulk material to be cooled rests. The cooling grate comprises several planks which are moved forwards and backwards in the conveying direction alternately by a stroke length, the drive of which is controlled in such a way that at least two adjacent planks are moved simultaneously in the forward stroke and not simultaneously in the return stroke. Such cooling devices serve to cool bulk material using gas, in that the bulk material is placed as a bed on a cooling grate and transported along it, while gas is supplied from below the cooling grate for cooling. The cooling gas, which is typically cooling air from the lower space of the grate, rises through the cooling grate into the bulk material bed and cools it in the process. In such cooling devices, the cooling grate has three functions in relation to the bulk material. One function is to support the bulk material to form a material bed, another is the surface for introducing the cooling air, and the other is a transport function for conveying the bulk material from a feed end to a discharge end. Various basic designs have become known for implementing the functions. Of interest here is the design with several planks extending in the conveying direction, which are moved back and forth alternately. One difficulty with this conveying principle is that the planks and their surface are exposed to great stresses, namely because of the at least initially or high temperatures of the goods to be cooled and abrasion, particularly with sharp-edged goods such as clinker. This high load leads to considerable wear of the planks. It is known to form the surface of the planks using grate plates, which are relatively easy to replace. However, it is complex to design appropriate cooling gas passage openings in the grate plate, on whose surface the material bed to be cooled rests, to ensure a sufficient supply of cooling gas, to offer sufficient protection against problematic rust falling through the cooling gas passage openings and also to manufacture them efficiently. In addition, replacing the grate plates is complex because the cooler has to be shut down for this purpose. For efficient operation, on the one hand, a high cooling effect is important, which is determined, among other things, by the cooling gas throughput through the cooling grate with its cooling gas passage openings and, on the other hand, an efficient and low-wear conveying along the cooling grate by means of the movement of the planks. A design of the cooler with planks that have a smooth surface for the bulk material to rest on is known from DE 10 2007 019 530 Al. Ventilation slots are arranged in the space between the long sides of the planks, which extend over the entire length of the plank. They act as air passage openings for the cooling gas. They are provided with a special side-blow profile in order to minimize unwanted entry of bulk material and thus grate fall-through into the grate space. The surface of the planks is swept over by the escaping cooling gas. To protect the plank surface from thermal and abrasive stress caused by the bulk material, which is particularly relevant when hot clinker material is used as bulk material coming out of a kiln immediately upstream, it is known from EP 1509737 Bl to feed the planks of such a cooling grate with a large number of well-holding troughs on the surface of the planks. During operation, bulk material is deposited in the troughs and thus forms an autogenous protective layer which protects the sensitive plank surface from the high thermal and abrasive stress caused by the hot clinker material. The provision of a protective layer on the planks has the advantage that it offers good protection for the surface of the planks. This can reduce wear on the surface of the planks, particularly in the case of hot, aggressive bulk materials such as clinker. However, the protective layer has the disadvantages that it creates a flow resistance for the cooling gas flowing upwards from below through the cooling grate and that, at least on the return stroke, it generates a disruptively high frictional force on the bulk material. The latter requires different dimensions of the steel structure and a more powerful drive. This also leads to compaction of the bulk material on the return stroke, which creates additional flow resistance for the cooling gas flowing through the cooling grate, thereby increasing the inherent pressure losses in the cooling gas supply. A smooth design of the planks without a protective layer offers the advantage that only a small return stroke force is required and, due to th