Improved sintering or firing belt for sintering or pelletizing plant

Abstract

A sintering belt (10) comprising: a string of grate carriages (12); a support structure configured to support and allow movement of the string of grate carriages (12); at least two longitudinal sealing elements parallel to the direction of movement (D) of the row of grate carriages (12) along the sintering or firing zone (10); at least two transverse sealing elements (14) intersecting the row of grate carriages (12) in the direction of movement (D) of the sintering or firing zone (10) and partially obstructing the movement thereof; and at least one suction tube (16). The suction tube (16), the at least two longitudinal sealing elements, the at least two transverse sealing elements (14) and the bottom surface of the grate carriage (12) are configured to define at least one plenum (PC). The suction tube (16) is further configured to generate a low or high pressure in the plenum (PC). The transverse sealing element (14) comprises at least one sealing roller (18, 18.1-18.15), the sealing roller (18, 18.1-18.15) being configured to partially obstruct movement of a string of grate carriages (12), and the sealing roller (18, 18.1-18.15) comprising an inner roller (18a) defining an inner radius and an elastically deformable outer sleeve (18b) defining an outer radius, and the transverse sealing element (14) comprising a plurality of parallel sealing rollers (18, 18.1-18.15) to define at least one roller table (20). The roller table (20) comprises at least two joining sealing rollers (18.1-18.5) such that the distance between two adjacent joining sealing rollers (18.1-18.5) is strictly between the sum of their inner radii and the sum of their outer radii, the consecutive joining sealing rollers (18.1-18.5) defining a continuous surface (20 ') of the roller table (20).

Description

Technical Field

[0001] The present invention generally relates to sintering plants or pelletizing plants. More specifically, the present invention relates to sintering belts or roasting belts having improved durability and lower operating costs. Background Art

[0002] Sintering plants are widely used to agglomerate fine-grained materials into sinter suitable for blast furnaces.

[0003] Sintering / pelletizing plants typically include: a mixing drum and a hopper for mixing different fine-grained materials in a desired ratio; a sintering belt or a roasting belt (in the case of processing pellets, this belt is called a roasting belt) for carrying the mixture of fine-grained materials; and an ignition hood near the upstream end of the belt or strand to ignite a portion of the fine-grained materials. At the end of the belt, the resulting agglomerated material can be crushed and cooled before storage.

[0004] Traditionally, the belt includes: a series of continuous grate-type cars for carrying the mixture of fine-grained materials; a support structure for supporting and allowing a series of grate-type cars to move along the belt; at least two longitudinal sealing elements; at least two transverse sealing elements; and at least one suction pipe. The bottom surface of the cars in a series of grate-type cars is configured to prevent the fine-grained materials from passing while allowing gas flow.

[0005] The suction pipe, the longitudinal sealing elements, the transverse sealing elements, and the bottom surface of a series of grate-type cars are configured to define at least one plenum chamber. The suction pipe is further configured to create a low pressure and a high pressure in the plenum chamber. Thus, when the suction pipe creates a pressure difference, an air flow is generated through the bottom surface of a series of grate-type cars and through the mixture of fine-grained materials in a series of grate-type cars. In the case where a portion of these fine-grained materials has been previously ignited by the ignition hood, this air flow can support the spread of the flame through the mixture.

[0006] Typically, these transverse sealing elements include a plurality of adapter plates that can adjust their horizontal height to allow the incoming grate-type cars to pass through, while ensuring a minimum gap or no gap with the grate-type cars for tightness (i.e., ensuring that no air leaks into / escapes from the plenum chamber through the gap between the grate-type car and the transverse sealing element). If there is no gap, the contact pressure required to ensure tightness results in wear caused by friction between the adapter plate and these grate-type cars. This contact also tends to impede the movement of this series of grate-type cars. However, even if a small gap is formed in the adapter plate, extreme abrasive blasting wear may occur due to the high pressure difference and the presence of fine-grained materials in the air flow. The size of this gap can then increase by several orders of magnitude, resulting in a large amount of air leakage flow. Summary of the Invention

[0007] Object of the invention

[0008] An object of the present invention is to provide a sintering belt or roasting belt for a sintering plant or a pelletizing plant, which is more durable, less prone to abrasion and sandblasting wear, easier to maintain and minimizes the flow of air leakage.

[0009] This object is achieved by a sintering belt or roasting belt according to claim 1. Summary of the invention

[0011] In order to overcome the above problems, a sintering belt or roasting belt for transporting a load through a sintering plant or a pelletizing plant comprises:

[0012] - A string of grate cars having a bottom surface,

[0013] - A support structure configured to support and allow the movement of a string of grate cars,

[0014] - At least two longitudinal sealing elements, parallel to the direction of movement of a string of grate cars along the sintering belt or roasting belt,

[0015] - At least two transverse sealing elements, intersecting the direction of movement of a string of grate cars along the sintering belt or roasting belt and partially impeding its movement, and

[0016] - At least one suction pipe.

[0017] The suction pipe, at least two longitudinal sealing elements, at least two transverse sealing elements and the bottom surface of the grate cars are configured to define at least one air supply chamber. In particular, the suction pipe ensures tightness at the bottom end of the air supply chamber, the longitudinal sealing elements ensure tightness on the lateral sides, the transverse sealing elements ensure tightness at the upstream and downstream ends, and the adjacency of the grate cars ensures partial tightness at the top end.

[0018] The suction pipe is further configured to create a low pressure or a high pressure in the air supply chamber.

[0019] The transverse sealing element includes at least one sealing roller, which is configured to partially impede the movement of a string of grate cars, and the sealing roller includes an inner roller defining an inner radius and an elastically deformable outer sleeve defining an outer radius.

[0020] The advantages of using the sealing roller according to the present invention are multiple.

[0021] Firstly, the sealing roller cannot completely block the movement of the grate cars. In fact, even if the incoming grate cars are worn and their height is lower than expected, the trajectory of the grate cars will be corrected when they come into contact with the sealing roller and deform the outer sleeve of the sealing roller.

[0022] Second, the grate car is positioned in contact with the lateral sealing element by means of a sealing roller in a smaller area, thereby allowing a higher contact pressure for improved tightness. The tightness is further improved by using a soft or flexible material in the outer sleeve.

[0023] Third, since the sealing roller can rotate in response to the friction exerted by the movement of the grate car, the total wear on the lateral sealing element is reduced, even if the material is sensitive to wear. Moreover, the wear is distributed over the outer sleeve. Therefore, the sealing roller can be easily maintained by simply fitting a new outer sleeve onto its inner roller.

[0024] The lateral sealing element includes a plurality of parallel sealing rollers to define at least one roller table. The use of multiple rollers further enhances the above technical effects and allows for various configurations as described below.

[0025] According to the present invention, the roller table may include at least two engaging sealing rollers such that the distance between two adjacent engaging sealing rollers is strictly between the sum of their inner radii and the sum of their outer radii, and a plurality of consecutive engaging sealing rollers define a continuous surface of the roller table. The tightness between the engaging sealing rollers is ensured by the contact pressure between their outer sleeves or by the mutual engagement of their outer sleeves.

[0026] Preferably, the grate cars in a string of grate cars include rigid beams extending laterally on the bottom surface of the grate cars such that, in operation, when the grate cars pass over the sealing rollers, the laterally extending rigid beams contact the sealing rollers. The diameter and / or pitch of the engaging sealing rollers constituting the continuous surface are preferably selected such that a string of grate cars rotating the rollers due to friction cannot cause two or more engaging rollers to rotate in a rotational direction incompatible with their natural drive. Since adjacent engaging rollers within the continuous surface rotate in opposite directions at any given time, this configuration prevents wear between adjacent engaging rollers. Note that with this configuration, the rotation of each roller changes back and forth between two directions as the laterally rigid beam of the grate car travels through the continuous surface.

[0027] Preferably, the continuous surface includes an odd number of engaging sealing rollers. Since the rotation of each roller changes back and forth between two directions as the grate car travels through the continuous surface, having an even number of rollers may result in only a small portion of the outer sleeve repeatedly contacting these grate cars. This would leave most of the perimeter of the outer sleeve intact but cause rapid wear of a small portion of the outer sleeve.

[0028] The sintering belt or roasting belt may include complementary rotary drives to improve torque transmission between the sealing rollers. The complementary rotary drives ensure that the sealing rollers rotate in their intended directions, thereby reducing friction and wear, especially between adjacent engaging sealing rollers.

[0029] The complementary rotating driver can be selected from gears, motors, and protrusions on the inner roller.

[0030] The roller table can include at least two non-engaging sealing rollers such that the distance between two adjacent non-engaging sealing rollers is equal to or greater than the sum of their outer radii, and the continuous non-engaging sealing rollers define a discontinuous surface of the roller table. Since the non-engaging sealing rollers only have one rotation direction, multiple sealing rollers within the discontinuous surface can be driven by a single motor and belt.

[0031] Such a discontinuous surface can include complementary sealing elements configured to prevent gas from flowing through the discontinuous surface between these non-engaging sealing rollers.

[0032] Such complementary sealing elements can be selected from lateral gaskets, sealing bottom parts, and complementary sealing rollers.

[0033] Preferably, each grate car includes at least one, preferably at least two, lateral rigid beams extending laterally on the bottom surface of the grate car such that, in operation, when the grate car passes over the sealing roller, the laterally extending rigid beams contact the sealing roller. The lateral rigid beams preferably include longitudinal extrusions at their bottom ends. The lateral rigid beams can localize the force exerted by the grate car on the roller, thereby improving the tightness between the roller and the grate car. The longitudinal extrusions further improve the tightness between the roller and the grate car by ensuring contact with the roller during the entire movement of the grate car.

[0034] The outer sleeve can be made of a soft material or a flexible material, such as rubber or brush-like material. Such an outer sleeve improves the tightness between the sealing rollers of the continuous surface and generally improves the tightness between the sealing rollers and the grate car.

[0035] At least one rotation sensor can be arranged to detect the rotation of the sealing roller. By monitoring the rotation of the roller, faulty rollers can be identified and maintenance operations can be planned accordingly.

[0036] The longitudinal sealing element can be a scraping gasket.

[0037] Preferably, the bottom surface of at least one car in a string of grate cars is configured to allow gas flow and prevent the loading from passing through. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] With reference to the accompanying drawings, further details and advantages of the present invention will be apparent from the following detailed description of non-limiting embodiments, in which:

[0039] FIG. 1a and Figure 1b are cross-sections of an embodiment of a sintering belt or roasting belt according to the prior art and according to the present invention, respectively;

[0040] Figure 2a, Figure 2b , Figure 2c , Figure 2d and Figure 2e are schematic views of different stages during the movement of a grate-type trolley of an embodiment with continuous sections according to the present invention;

[0041] Figure 3a , Figure 3b , Figure 3c are schematic views of embodiments with different discontinuous sections according to the present invention. Detailed Embodiment

[0042] Figure 1a and Figure 1b respectively show cross-sections of an embodiment of a sintering or roasting belt 10 according to the prior art and according to the present invention.

[0043] In both of these embodiments, the belt 10 includes a series of grate-type trolleys 12 having a plurality of wheels 12a supported by tracks (not shown) on a support structure. These tracks support the trolleys 12 and enable them to move along the belt in the transport direction D. These grate-type trolleys have a bottom surface 12a configured to allow gas flow and prevent the load from passing through their bottom surface 12a.

[0044] In addition, longitudinal sealing elements (not shown) are arranged on both sides of the belt 10 in a vertical longitudinal plane, while the suction pipe 16 is arranged below a series of grate-type trolleys 12 and along this row of grate-type trolleys.

[0045] Figure 1a and Figure 1b differ in that in Figure 1a a plurality of adapter plates are arranged in the transport direction D. The adapter plates are configured to adjust their horizontal height to provide sufficient contact pressure or a minimum gap to manage tightness while allowing the passing of the grate-type trolleys 12 that are allowed to enter.

[0046] Meanwhile, in Figure 1b , a plurality of sealing roller tables 20 are arranged in the transport direction D. The sealing rollers 18 of the roller table 20 include an inner roller 18a and an outer sleeve 18b made of a brush-like material. A plurality of rollers 18 within the roller table 20 are arranged parallel to each other and these rollers are arranged perpendicular to the transport direction D. The outer sleeve 18b of each roller 18 engages with the outer sleeves 18b of two other rollers 18 (or a single other roller 18 in the case where the roller is at the end of the roller table 20). Thus, gas flow between the plurality of rollers 18 is prevented.

[0047] The roller table 20 is further configured to partially obstruct the path of the grate car 12 such that when the entering grate car contacts the most upstream roller of the roller table 20, the grate car 12 moves upward along the curvature of the roller 18. Eventually, the weight of the grate car 12 compresses the outer sleeve 18b of the sealing roller 18 of the roller table 20, thereby preventing gas from flowing between the grate car 12 and the roller 18.

[0048] Thus, both the plurality of adapter plates of Fig. 1a and Figure 1b the plurality of roller tables 20 act as lateral sealing elements 14 in their corresponding embodiments.

[0049] The lateral sealing element 14, the longitudinal sealing element, the suction pipe 16, and the bottom surface 12a of the plurality of grate cars 12 are arranged to define a plurality of air supply chambers PC below a string of grate cars 12. Thus, when the suction pipe 16 creates a low or high pressure in the air supply chamber PC, the only flow path available for the gas is through the bottom surface 12a of the grate car 12 and through the fine-grained material loaded in the grate car.

[0050] Figures 2a to 2e A schematic view of an embodiment according to the invention with a continuous surface 20' is shown. In particular, Figures 2a to 2e the rotational directions 18c of the engagement rollers 18.1 - 18.5 in different stages of the movement of the grate car along the roller table are shown. The grate car (not fully shown) travels along the transport direction D and has a bottom surface 12.a and a pair of transverse rigid beams 12.b that terminate in a longitudinal extrusion 12.c. As visible in Figure 2a , Figure 2c , Figure 2e when the grate car moves to the right and contacts the odd-numbered sealing rollers (sealing rollers 18.1, 18.3, 18.5), the rollers rotate clockwise, while the even-numbered sealing rollers (sealing rollers 18.2, 18.4) rotate counterclockwise. Conversely, as visible in Figure 2b , Figure 2d when the grate car moves to the right and contacts the even-numbered sealing rollers (sealing rollers 18.2, 18.4), the rollers rotate clockwise, while the odd-numbered sealing rollers (sealing rollers 18.1, 18.3, 18.5) rotate counterclockwise. Thus, the rotation of these rollers oscillates between the two directions as the grate car advances along the movement direction D. The mutual engagement of the outer sleeves 18b of the sealing rollers 18.1 - 18.5 prevents gas from flowing through the continuous surface 20', i.e., between these sealing rollers. Similarly, the longitudinal extrusion 12c of the grate car cooperates with the outer sleeves 18b of the sealing rollers 18.1 - 18.5 to prevent gas from flowing between the sealing roller table and the grate car.

[0051] Figures 3a to 3c illustrates different embodiments in accordance with the present invention having different discontinuous surfaces 20". In particular, Figure 3a illustrates a table having two sealing rollers 18.6, 18.7 and a lateral sealing gasket 22a, Figure 3b illustrates a table having four rollers 18.8 - 18.11 interconnected by a sealing bottom portion 22b, and Figure 3c illustrates a table having four rollers 18.12 - 18.15 and a complementary sealing roller 22c therebetween. Figure 3a The lateral sealing gasket 22a of Figure 3b the sealing bottom portion 22b of Figure 3c and the complementary sealing roller 22c of Figure 3c prevent gas from flowing between the sealing rollers 18.6 - 18.15 of their respective discontinuous surfaces 20". In addition, Figures 3a to 3c the complementary sealing roller 22c of Figure 3c acts as a complementary rotary drive capable of transmitting torque between the sealing rollers 18.12 - 18.15 such that all the sealing rollers 18.12 - 18.15 rotate in the same direction 18c. Figures 3a to 3c The embodiment of Figures 3a to 3c also includes a rotation sensor 24 configured to monitor the rotation of the sealing rollers.

[0052] The embodiments discussed above are merely exemplary and do not exclusively limit the scope of the present invention. In particular, it should be noted that the subject matter of the present invention includes combinations of the disclosed embodiments, such as a roller table 20 including one or more continuous surfaces 20' and one or more discontinuous surfaces 20".

Claims

1. A sintering belt or roasting belt (10) for transporting a charge through a sintering plant or a pelletizing plant, comprising: - A string of grate cars (12), said grate cars having a bottom surface (12a); - A support structure configured to support a string of said grate cars (12) and enable the string of said grate cars to move; - At least two longitudinal sealing elements, parallel to the direction of movement (D) of a string of said grate cars (12) along said sintering belt or roasting belt (10); - At least two transverse sealing elements (14), intersecting the direction of movement (D) of a string of said grate cars (12) along said sintering belt or roasting belt (10), and partially obstructing the movement of said grate cars; - At least one suction pipe (16); wherein said suction pipe (16), at least two of said longitudinal sealing elements, at least two of said transverse sealing elements (14), and the bottom surface of said grate cars (12) are configured to define at least one air supply chamber (PC); wherein said suction pipe (16) is configured to create a low pressure or a high pressure in said air supply chamber (PC); wherein said transverse sealing element (14) includes at least one sealing roller (18, 18.1 - 18.15), said sealing roller (18, 18.1 - 18.15) being configured to partially obstruct the movement of a string of said grate cars (12), and said sealing roller (18, 18.1 - 18.15) including an inner roller (18a) defining an inner radius and an elastically deformable outer sleeve (18b) defining an outer radius; wherein said transverse sealing element (14) includes a plurality of parallel sealing rollers (18, 18.1 - 18.15) to define at least one roller table (20); characterized in that the roller table (20) includes at least two engaging sealing rollers (18.1 - 18.5) such that the distance between two adjacent engaging sealing rollers (18.1 - 18.5) is strictly between the sum of the inner radii of the two adjacent engaging sealing rollers and the sum of the outer radii of the two adjacent engaging sealing rollers, and the successive engaging sealing rollers (18.1 - 18.5) define a continuous surface (20’) of the roller table (20).

2. The sintering zone or roasting zone (10) according to claim 1, wherein, The grate cars (12) in a string of said grate cars include rigid beams (12b) extending transversely on the bottom surface (12a) of said grate cars (12) such that, in operation, when said grate cars (12) pass over said sealing rollers (18.1 - 18.5), the transversely extending rigid beams (12b) contact said sealing rollers (18.1 - 18.5); and wherein the diameter and / or pitch of the engaging sealing rollers (18.1 - 18.5) constituting the continuous surface are selected such that a string of said grate cars (12) rotating the rollers due to friction cannot rotate two or more engaging rollers (18.1 - 18.5) in a rotational direction incompatible with their natural transmission.

3. The sintering belt or roasting belt (10) according to claim 1 or 2, comprising an odd number of said joint sealing rollers (18.1 - 18.5) to define said continuous surface (20’).

4. The sintering belt or roasting belt (10) according to any one of the preceding claims, further comprising complementary rotary drives to improve torque transmission between said sealing rollers.

5. The sintering zone or roasting zone (10) according to claim 4, wherein, Said complementary rotary drives are selected from gears, motors, and protrusions on the inner rollers.

6. The sintering zone or roasting zone (10) according to any one of the preceding claims, wherein, The roller table (20) comprises at least two non-joint sealing rollers (18.6 - 18.15), such that the distance between two adjacent non-joint sealing rollers (18.6 - 18.15) is equal to or greater than the sum of the outer radii of the two adjacent non-joint sealing rollers, and a plurality of said non-joint sealing rollers (18.6 - 18.15) define the discontinuous surface (20”) of the roller table (20).

7. The sintering belt or roasting belt (10) according to claim 6, further comprising complementary sealing elements (22a, 22b, 22c), said complementary sealing elements being configured to prevent gas from flowing through said discontinuous surface (22”) between said non-joint sealing rollers (18.6 - 18.15).

8. The sintering zone or roasting zone (10) according to claim 7, wherein, Said complementary sealing elements (22a, 22b, 22c) are selected from lateral gaskets (22a), sealing bottom parts (22b), and complementary sealing rollers (22c).

9. The sintering zone or roasting zone (10) according to any one of the preceding claims, wherein, Each said grate-type trolley (12) comprises at least one transverse rigid beam (12b), preferably at least two, and said transverse rigid beam (12b) extends transversely on the bottom surface (12a) of said grate-type trolley (12), such that in operation, when said grate-type trolley (12) passes over the sealing rollers (18.1 - 18.5), the transversely extending said rigid beam (12b) contacts the sealing rollers (18.1 - 18.5), and said transverse rigid beam (12b) preferably comprises a longitudinal extrusion part (12c) at the bottom end of the rigid beam.

10. The sintering zone or roasting zone (10) according to any one of the preceding claims, wherein, The outer sleeve (18b) of the sealing rollers (18, 18.1 - 18.15) is made of a soft material or a flexible material, such as rubber or brush-like material.

11. The sintering zone or roasting zone (10) according to any one of the preceding claims, wherein, At least one rotary sensor (24) is arranged to detect the rotation of the sealing rollers (18, 18.1 - 18.15).

12. The sintering zone or roasting zone (10) according to any one of the preceding claims, wherein, Said longitudinal sealing element is a scraping gasket.

13. The sintering zone or roasting zone (10) according to any one of the preceding claims, wherein, The bottom surface (12a) of at least one trolley (12) in a series of said grate-type trolleys is configured to allow gas flow and prevent the loading from passing through.

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