Kits, methods and systems for performing maintenance on bowl mill pulverizers

Abstract

The present disclosure relates to kits, systems and methods for performing maintenance on a bowl mill pulverizer. A kit comprises a lug (11) having an attachment point (26,27) for a rope (12) and connectable to a journal assembly (6) of the pulverizer; a frame configured to be attached to a portion of a housing of the pulverizer and comprising a pulley (20) configured to guide the rope; a resting bracket (13) configured to support the journal assembly after it has been tilted out / into through the opening; and a clamping element configured to keep a pivot shaft of the pulverizer in place while tilting the journal assembly.

Description

Kits, methods and systems for performing maintenance on bowl mill pulverizersTECHNICAL FIELD

[0001] The present disclosure relates to kits, methods and systems for performing maintenance on bowl mill pulverizers, for example pulverizers of coal-fired boilers. The present disclosure further relates to servicing and / or replacing journal assemblies and grinding mechanisms of bowl mill pulverizers.BACKGROUND

[0002] A coal-fired boiler is an industrial boiler that generates thermal energy by burning pulverized coal. The boiler comprises tubes through which water circulates. The coal is first grinded to a desired fineness in a pulverizer and is then blown into a firebox or furnace, where the coal is burnt. This heats the water circulating in the boiler tubes, generating steam. The steam is usually separated from the liquid water at the top of the firebox. The steam may then be carried to a steam turbine for driving the steam turbine and therefore turn an electric generator connected to the steam turbine.

[0003] Different types of pulverizers are known in the art. In a bowl mill pulverizer, raw coal is generally fed through a central coal inlet at the top of the pulverizer. The coal falls by gravity to a grinding table or bowl at the base of the mill. Grinding rollers mounted on suitable journal assemblies interact with the rotating grinding table to grind the coal. Air is used to dry the coal and to remove the finely grinded coal from the pulverizer. The grinded coal is then carried to the firebox through multiple pipes.

[0004] Bowl mill pulverizers, which are also known as vertical spindle roller mill pulverizers, may be of different types, for example suction type and pressurized type bowl mills. In suction type bowl mills, an exhauster is arranged after the bowl mill. In pressurized type bowl mills, an air fan is arranged before the bowl mill. Suction type bowl mills are sometimes designated as XRS, whereas pressurized mills are sometimes designated as XRP and HP. The “X” may refer to the frequency of the power supply, e.g. 50 Hz, and the “R” refers to Raymond, the inventor of bowl mills. The “S” and “P” may refer to suction type and pressurized type, respectively. The “H” may refer to high performance bowl mills. The high performance bowl mills may herein beregarded as a new generation of bowl mills, e.g. an updated version, of the previous pressurized type bowl mills, e.g. XRP bowl mills.

[0005] Over time, the grinding rollers of a bowl mill wear and they have to be replaced. To do so, the old grinding rollers are removed from the pulverizer and the new ones are mounted to the pulverizer. In more recent bowl mill pulverizers, e.g. HP bowl mill pulverizers, the journal assembly with the grinding roller can be rotated out of, and into, the pulverizer housing. However, in older or legacy bowl mill pulverizers, e.g. the aforementioned XRS and XRP bowl mill pulverizers, this is not currently possible. Therefore, the entire journal assemblies have to be uninstalled using a large and complex overhead crane.

[0006] For example, once the pulverizer has cooled down and the cover closing the opening giving access to the journal assembly has been removed, a chain support may be fixed in a suitable position to handle the journal assembly. Then, the shaft (trunnion shaft) of the journal assembly may be unfastened and removed from the bowl mill using the chain. Next, the journal assembly may be moved to a suitable location, e.g. to ground level or to a workshop floor, using a crane. A journal assembly with a new grinding roller may then be installed by performing the previous steps, but in a reverse order. These steps require a large amount of time.

[0007] Also, even if replacing a grinding roller or performing maintenance on the journal assembly is not required, at least one of the journal assemblies still may have to be removed to be able to access an inside of the bowl mill and perform inspection or other maintenance tasks inside the bowl mill pulverizer.

[0008] The present disclosure aims at reducing the amount of time required for performing maintenance in bowl type mills and increasing safety when handling the journal assemblies.SUMMARY

[0009] In an aspect of the disclosure, a kit for performing maintenance on a bowl mill pulverizer is provided. The kit includes a lug having an attachment point for a rope, the lug being configured to be removably attached to a journal assembly of the pulverizer. The kit further includes a frame configured to be attached to a portion of a housing of the pulverizer surrounding a top portion of an opening of the housing providing access to an inside of the pulverizer. The frame comprises a first pulley configured to guide the rope. The kit further comprises a resting bracket configured to be attached to the housing and to support the journal assembly after it has been tilted out through the opening. And the kit further comprises aclamping element configured to keep a pivot shaft of the pulverizer in place while tilting the journal assembly.

[0010] Thereby, a frame may be mounted to the housing, and the lug may be attached to the journal assembly. A rope may be passed around a pulley. The resting bracket and the clamping element may also be mounted to the housing. The clamping element can ensure that there is a pivot line around which the journal assembly can rotate. The pivot shaft may thus stay in place during all the tilting process due to the clamping element. A lifting device can then pull the rope, which tilts the journal assembly out of the housing (or into the housing). The journal assembly may rest on the resting bracket once it has been tilted out of the housing (or before it is tilted into the housing). The resting bracket may also be regarded as a safety bracket.

[0011] The resting bracket may further be configured to be attached or connected to the journal assembly to securely retain the journal assembly in place, for example using suitable mechanical fasteners.

[0012] Maintenance may therefore be performed without the need of completely removing the journal assembly from the pulverizer. Operators may gain access to an inside of the pulverizer, or the grinding mechanism may be replaced without having to further unmount the journal assembly, or the journal assembly may be repaired without having to further unmounting the journal assembly, etc. Maintenance time is reduced, and operation time of the pulverizer is increased. As the journal assembly does not need to be completely uninstalled and then lowered to the ground or transported elsewhere, associated security risks are eliminated for the operators. Also, less operators are needed.

[0013] Throughout this disclose, a rope may refer to a rope, chain, wire etc. suitable to perform the associated operations described herein.

[0014] Throughout this disclose, a lifting device may refer to any sort of suitable crane or hoist. In particular, roof mounted hoists such as monorail hoists may be used to provide the traction force necessary in the rope to be able to tilt the journal assembly about the pivot axis.

[0015] The frame may comprise more than one pulley, for example two or more pulleys. The pulleys may be arranged above each other, specifically in a front region of the frame. The frame may comprise exactly two pulleys in some examples. One of the pulleys may be used for tilting out the journal assembly, and the other pulley may be used for tilting in the journal assembly.

[0016] The frame may comprise a backplate comprising a bottom portion with a recess, for example an arc-shaped recess. The shape of the recess may be adapted to a shape and sizeof the top portion of the opening of the housing of the pulverizer to suitably and easily attach the frame. Holes around the frame previously used to secure the cover to close the opening, e.g. during operation of the pulverizer, may be re-used to attach the frame.

[0017] The kit may comprise more than one clamping element. The clamping elements may for example be substantially C-shaped clamps. The clamping elements may be used to clamp the pivot shaft to the housing. Similarly to the frame, previous existing holes of the housing may be used to attach the clamping elements. One clamping element may be attached at a corresponding end portion of the pivot shaft. Two clamping elements may be sufficient to keep the pivot shaft in place, i.e. in its seat of the pulverizer housing, during the tilting process. The C-shaped clamps may be regarded as forming half of the clamping arrangement fixing the pivot shaft in place.

[0018] The resting bracket may comprise a first segment configured to be attached to the housing of the pulverizer and a second segment configured to support the journal assembly. The first and second segments may be substantially straight. In particular, the second segment may have a size and shape adapted to the journal assembly to be supported. The second segment may be configured for mechanical attachment to the journal assembly. The journal assembly may be suitably supported by such a resting bracket.

[0019] The lug may comprise a first attachment point to attach the rope for tilting the journal assembly out of the pulverizer housing, and a second attachment point to attach the rope for tilting the journal assembly into the pulverizer housing. This may help to adjust and optimize each tilting process. The journal assembly may be suitably supported and driven during each tilting process.

[0020] In another aspect of the disclosure, a method for performing maintenance on bowl mill pulverizer is provided. Specifically, the kit of the previous aspect may be used to perform the method. The method comprises attaching a frame comprising a pulley to a portion of a housing of the pulverizer surrounding a top portion of an opening of the pulverizer providing access to an inside of the pulverizer. The method further comprises connecting, e.g. attaching, a lug to the journal assembly and passing a rope around the pulley and connecting it to the lug. The method further comprises attaching a resting bracket to the housing of the pulverizer to support a journal assembly pivotably mounted on a pivot shaft of the pulverizer. The method further comprises connecting a clamping element to the housing such that the pivot shaft is kept in place while tilting the journal assembly. Then, the rope can be pulled, thereby rotating the pivot shaft and tilting the journal assembly out of the housing of the pulverizer. And the method further comprises resting the journal assembly on the resting bracket.

[0021] Performing maintenance of a bowl mill pulverizer in this manner is faster than entirely unmounting the journal assembly and the grinding mechanism from the housing of the pulverizer.

[0022] The resting bracket may specifically be attached below the opening in the housing. This may help to effectively support the journal assembly on the resting bracket as well as to use previous attachment points, e.g. attachment points for the cover of the opening.

[0023] Depending on the maintenance necessary, the method may further comprise removing a grinding mechanism carried by the journal assembly from the pulverizer and attaching a new grinding mechanism to the journal assembly. The journal assembly may stay connected to the pulverizer housing, which may facilitate and speed up the replacement process.

[0024] The method may further comprise pulling the rope and tilting the journal assembly back into the housing of the pulverizer by rotating the pivot shaft supporting the journal assembly in the opposite direction. Le., after the journal assembly has been tilted out, it may then be tilted back in. Specifically, it may be tilted in after one or more maintenance tasks have been performed.

[0025] In some examples, the frame that is attached to an outside of the housing may comprise more than one pulley. A first pulley can be used to guide the rope to the lug for the operation of tilting out. A second pulley can be used to guide the rope to the lug for the operation of tilting back in. The relative positions of the lug and pulleys can be selected such that tilting out is achieved by applying traction on the rope. Then, by repositioning the rope along the second pulley, the direction of traction can be changed, and the journal assembly can be tilted back in.

[0026] The first pulley around which the rope for tilting out is passed may be the lowest pulley in some examples. The journal assembly may be supported and guided in an optimized manner while tilting it out of the housing.

[0027] The method may further comprise passing the rope around the second pulley before tilting the journal assembly into the housing of the pulverizer, specifically a top pulley. The tilting in process may thereby be optimized. For the same reason, the method may additionally or alternatively comprise connecting the rope to a different attachment point of the lug, e.g. an attachment point farther away from a center of the lug than the attachment point for the tilt out.

[0028] In a further aspect, a system for performing maintenance on a bowl mill pulverizer is provided. The system comprises the bowl mill pulverizer. The pulverizer comprises a housing having an opening providing access to an inside of the pulverizer and a pivot shaft supportinga journal assembly. The system further comprises a lug connected to the journal assembly. The system further comprises a frame attached to the housing of the pulverizer around a top portion of the opening providing access to the inside of the pulverizer, the frame comprising a pulley configured to guide (or already guiding) the rope. The system further comprises a resting bracket configured to support the journal assembly after it has been tilted out through the opening. And the system further comprises a clamping element configured to keep the pivot shaft of the pulverizer in place while tilting the journal assembly.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 schematically illustrates a side view of an example of a portion of a housing of a bowl mill pulverizer.

[0030] Figures 2 and 3 schematically illustrate a front view and a perspective view of an example of a frame attachable around a top portion of an opening of the housing of a bowl mill pulverizer, for example the bowl mill pulverizer of figure 1 , respectively.

[0031] Figure 4 schematically illustrates a perspective view of an example of a resting bracket attachable to the housing of a bowl mill pulverizer, for example the bowl mill pulverizer of figure 1, to support a journal assembly tilted out of the bowl mill housing or a journal assembly to be tilted into the bowl mill housing.

[0032] Figure 5 schematically illustrates a perspective view of a clamping element to keep a pivot shaft of a bowl mill pulverizer, for example the bowl mill pulverizer of figure 1 , in place.

[0033] Figure 6 schematically illustrates a front view of an example of portion of a housing of a bowl mill pulverizer, for example the bowl mill pulverizer of figure 1 , with a kit attached to the pulverizer for performing maintenance . A journal assembly which has been partially tilted outwards can be seen in the example of this figure.

[0034] Figure 7 schematically illustrates a side view of a journal assembly of a bowl mill pulverizer being tilted out of the pulverizer.

[0035] Figure 8 schematically illustrates a side view of a journal assembly of a bowl mill pulverizer being tilted into the pulverizer.

[0036] Figure 9 shows a flowchart of a method for performing maintenance on a bowl mill pulverizer.DETAILED DESCRIPTION OF EXAMPLES

[0037] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation only, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0038] Figure 1 schematically illustrates a side view of an example of a portion of a housing 2 of a bowl mill pulverizer 1. The pulverizer 1 comprises a housing 2 having an opening 3 which can provide access to an inside 5 of the pulverizer (see specifically figs. 6 - 8), and a pivot shaft 4, also known as trunnion, supporting a journal assembly 6 and connected to the pulverizer housing 2. The journal assembly 6 is pivotally mounted on the shaft 4. The journal assembly 6 carries a grinding mechanism 7, e.g. a grinding roller, mounted thereon for grinding a material. For example, raw coal may be grinded. The grinding mechanism 7 may rotate around a rotation axis (see axis 9 in figure 7), specifically a longitudinal axis of the journal assembly 6. A cover closing the opening 3 is not shown in the example of figure 1.

[0039] The raw coal or other suitable materials may be arranged on a grinding table or bowl (see the grinding table 8 in figures 7 and 8). The grinding table may be mounted on a shaft that may be operatively connected to a suitable drive mechanism. The grinding table may therefore rotate inside the housing 2 of the pulverizer.

[0040] In an aspect of the disclosure, a kit for performing maintenance on a bowl mill pulverizer is provided. The kit includes a lug 11 having an attachment point 26, 27 for a rope 12 (see specifically figure 7 for the lug). The lug 11 is configured to be removably attached to a journal assembly 6 of the pulverizer 1.

[0041] The kit further includes a frame 19 (see e.g. figure 3) configured to be attached to a portion of a housing of the pulverizer surrounding a top portion of the opening 3 of the housing 2. The frame 19 comprises at least one pulley 20 configured to guide the rope 12. The kit further comprises a resting bracket 13 configured to support the journal assembly 6 after it has been tilted out through the opening 3 (and therefore likewise to support the journal assembly 6 before the journal assembly 6 is tilted back in through the opening 3). And the kit further comprises a clamping element 10 configured to keep a pivot shaft of the pulverizer in place while tilting the journal assembly.

[0042] A front view and a perspective view of an example of a frame 19 are illustrated in figures 2 and 3, respectively. A perspective view of an example of a resting bracket 13 and of a clamping element 10 are illustrated in figures 4 and 5, respectively.

[0043] The kit may comprise a plurality of clamping elements 10 to keep the pivot shaft 4 of the pulverizer in place. The one or more clamping elements may therefore keep the pivot shaft 4 rotatably connected to the housing 2 of the pulverizer, ensuring a pivot axis for the pivot shaft 4. The pivot shaft 4 may therefore rotate out of / into the housing 2 effectively and securely.

[0044] In some examples, the clamping elements 10 may be half-clamps. A clamping element 10 may have a C-shape, a semi-circular shape or a similar shape in cross-section. A clamping element 10 may comprise a body 15, e.g. a C-shaped body, and two flanges 14, see figure 5. Suitable fasteners may be used to removably attach the clamping element 10, e.g. its flanges, to the housing 2 of the pulverizer. For example, the clamping element 10 may be bolted to the housing 2 of the pulverizer. In some examples, the kit comprises two (and no more) clamping elements. The C-shaped body, together with a rounded recess in the housing provides for a support of the pivot shaft 4.

[0045] The resting bracket 13 may similarly comprise two flanges 16, see figure 4. A first flange may be at a housing end of the bracket 13. The first flange may be configured to be removably attached, e.g. bolted, to the housing 2 of the pulverizer. A second flange may be at a journal assembly end of the bracket 13. The second flange may be configured such that the journal assembly may be rested on the second flange, specifically after tilting the journal assembly out or before tilting the journal assembly into the housing.

[0046] In some examples, the resting bracket 13 comprises a first segment 17 configured to be attached to the housing 2 of the pulverizer and a second segment 18 configured to be connected to, e.g. touch and support, the journal assembly 6. An angle between the two segments may be larger than 902and smaller than 1802. The first segment 17 may comprise the first flange and the second segment 18 may comprise the second flange.

[0047] In other examples, the resting bracket 13 may be integrally formed instead of being formed by separate pieces which have been joined, e.g. bolted. Additionally or alternatively, one or more pieces, segments or regions of the resting bracket 13 may be curved.

[0048] Figures 2 and 3 schematically illustrate a front view and a perspective view of an example of a frame 19 attachable around a top portion of an opening 3 of the housing 2 of a XRS or XRP bowl mill pulverizer, respectively.

[0049] In examples, the frame 19 may comprise more than one pulley, for example two or more pulleys 20. In the illustrated example of figures 2 and 3, a frame 19 comprises two pulleys 20.

[0050] The frame 19 may comprise a front region (the region farthest from the housing 2 when the frame 19 is mounted to the pulverizer housing 2) and a back region (the region closest to the housing 2 when the frame 19 is mounted to the pulverizer housing 2).

[0051] The frame 19 may comprise a backplate 21, see figure 3. The backplate may be configured to be removably attached, for example bolted, to the housing 2 of the pulverizer. The backplate 21 may comprise a bottom portion with a recess 23 following a contour of a top portion of an opening 3 of the pulverizer housing. For example, the recess 23 may be substantially arc-shaped. In these examples, a top portion of the opening of the housing may be arc-shaped, and the rim of the bottom portion of the backplate 21 may be arc-shaped as well. The frame 19 may therefore be easily and quickly attached to the housing of the pulverizer. It should be clear that if the housing or the opening in the housing have a different shape, the frame (and particularly the backplate) may be adapted to such a shape.

[0052] The pulleys 20 may be arranged above each other in the front region of the frame 19. The pulleys (irrespective whether there are two pulleys or more pulleys) may be radially offset. A bowl mill pulverizer may generally have a relatively cylindrical housing. The housing 2 therefore defines a radial direction, a vertical direction and a circumferential direction. When the elements of the kit are mounted to the housing, these directions may also be applicable to them. As shown in the examples of figures 3, 7 and 8, the pulleys 20 may be offset along the radial direction and along the vertical direction.

[0053] In a front view of the frame 19, see figure 2, the pulleys 20 may be seen as vertically aligned. As explained further below, the frame 19 may comprise a pulley support 24 carrying the rotational axes or shafts of the pulleys i.e. rotatably supporting the pulleys. As mentioned before, in this example, the pulley support 24 supports the pulleys 20 such that they are vertically offset and radially offset, see figures 7 and 8. Also, the pulleys 20 may be centered in the frame 19 (i.e. arranged at a middle portion of the frame) when seeing the frame 19 from the front.

[0054] The pulley support 24 may be connected to the backplate 21. The frame 19 may further comprise two intermediate plates 22 connecting the pulley support 24 and the backplate 21. In some examples, the pulley support 24 is a separate component from the intermediate plates 22. In other examples, the pulley support 24 may be integrally formed with the intermediate plates. For example, a pulley end of each intermediate plate 22 may form at leastin part the pulley support 24. The pulley support 24 may be centered with respect to the recess 23 of the backplate 21.

[0055] The pulley support 24 may be connected to a top portion of the backplate 21 through top arm 25, see figure 3. In some examples, the top arm may be separately manufactured and then connected to the backplate 21. In other examples, these elements may be integrally formed.

[0056] As shown in the examples of figures 7 and 8, a bottom pulley may be used for tilting the journal assembly 6 out of the pulverizer, and a top pulley may (mainly) be used for tilting the journal assembly 6 into the pulverizer, respectively. The bottom pulley in this example is closer to a front end of the frame 19 than the top pulley. I.e., when the frame 19 is mounted to the housing 2 of the pulverizer, the bottom pulley is further away from the housing 2 of the pulverizer in a radial direction than the top pulley.

[0057] The frame 19, the clamping elements 10 and the resting bracket 13 may be configured such that already existing attachment regions of the pulverizer housing 2 may be used for attaching these elements of the kit. For example, the pulverizer housing 2 generally comprises covers to close the openings in the housing. These covers are usually secured to the housing using e.g. bolts or other fasteners, and one or more of them may be removed for maintenance purposes. The pulverizer housing thus comprises holes, e.g. bolt holes, which are used to secure the covers to the housing. Some of these same holes may be used to removably attach, e.g. bolt, the frame 19, the clamping elements 10 and the resting bracket 13 to the housing 2.

[0058] As already mentioned, the frame 19 may be attached around a top portion of an opening 3 (see e.g. the examples of figures 6 and 7). The clamping elements 10 can be attached to the housing to retain the pivot shaft 4 in the housing. The clamping elements 10 may be attached near a side lower portion of the opening (see figure 1 ). And the resting bracket 13 may be attached below the opening 3. Holes to secure a cover for closing the opening 3 may be used to secure these elements as well.

[0059] In some examples, the lug 11, see figures 6 and 7, may comprise more than one rope attachment point for attachment to the rope 12. A first attachment point 26 may be used to attach the rope 12 for tilting the journal assembly 6 out of the pulverizer housing 2, and a second attachment point 27 may be used to attach the rope 12 for tilting the journal assembly into the pulverizer housing 2. The first attachment point 26 may be closer to a center of the lug 11 than the second attachment point 27 in some examples.

[0060] One end the rope may have a suitable ending for coupling to the lug, e.g. a suitable clip or buckle. In some examples, the lug 11 and the rope 12 may be provided already attached to the other, whereas in other examples they may be provided as separate elements still not attached to the other.

[0061] The lug 11 may be configured to be attached to the journal assembly 6. For example, a journal assembly end of the lug 11 may be attached to, e.g. bolted to the journal assembly 6. The journal assembly 6 may therefore be securely driven while tilting it out of, or into, the pulverizer housing 2.

[0062] The kit may in some examples further comprise a rope 12 connectable to the lug 11. The lug 11 and the rope 12 may be referred together as a lifting assembly. Besides having a lug end, i.e. the end connectable or connected to the lug 11, the rope 12 further comprises a lifting device end. The lifting device end may be connected to the lifting device which drives the rope 12 for tilting the journal assembly 6 out of, and into, the pulverizer housing. In some examples, the lifting device may be attached or connected to a ceiling or ceiling structure above the pulverizer. The lifting device may include a motor to drive, e.g. to coil or uncoil, the rope 12. In specific examples, the lifting device may be a hoist e.g. a monorail hoist.

[0063] The kit of this aspect may be mounted to the pulverizer housing 2 for tilting in and / or tilting out a journal assembly 6 of the pulverizer. When the kit is mounted to the pulverizer, the pulverizer and the kit may be referred to as “system”. In this manner, a system for performing maintenance on a bowl mill pulverizer may also be provided in a further aspect.

[0064] The system thus comprises a bowl mill pulverizer 1. The pulverizer comprises a housing 2 having an opening 3 providing access to an inside 5 of the pulverizer, and a pivot shaft 4 supporting a journal assembly 6. The journal assembly carries a grinding roll or other suitable griding mechanism.

[0065] The system further comprises a lug 11 connected, e.g. removably attached, to the journal assembly 6 of the pulverizer. The lug 11 is connected, e.g. removably attached, to a rope 12. The system further comprises a frame 19 attached to the housing 2 of the pulverizer around a top portion of the opening 3 providing access to the inside 5 of the pulverizer, the frame 19 comprising a pulley 20 configured to receive and guide (or already guiding) the rope 12. The system further comprises a resting bracket 13 configured to support the journal assembly 6 after it has been tilted out through the opening 3. And the system further comprises a clamping element 10 configured to keep the pivot shaft 4 of the pulverizer in place while tilting the journal assembly.

[0066] In a further aspect of the disclosure, a method for performing maintenance on a bowl mill pulverizer is provided. Specifically, the kit as hereinbefore illustrated may be used to perform the method. A flowchart of an example of the method is shown in figure 9. The method 30 comprises, at block 31 , attaching a frame 19 comprising a pulley 20 to a portion of a housing 2 of the pulverizer surrounding a top portion of an opening 3 providing access to an inside 5 of the pulverizer. Prior to this step, one or more covers closing off the opening 3 may be removed. As previously mentioned, the attachment points for the cover may in preferred examples be used to removably attach several elements of the kit.

[0067] The method further comprises, at block 32, connecting a lug 11 to the journal assembly 6 and passing a rope 12 around the first pulley 20. The lug 11 may be attached, e.g. bolted, to the journal assembly 6. The lug end of the rope may be connected to a suitable attachment point, e.g. an attachment point 26 closer to a center of the lug 11. The rope 12 and the lug 11 may be connected before or after other steps of the method. For example, the elements of the kit may be first mounted, and then the rope 12 may be connected to the lug 11.

[0068] The method further comprises, at block 33, attaching a resting bracket 13 to the housing of the pulverizer to support a journal assembly 6 pivotably mounted on a pivot shaft 4 of the pulverizer. This step may be performed after attaching the frame 19 and after connecting the lug 11 to the journal assembly 6, or it may be performed after attaching the frame 19 but before connecting the lug 11, or it may even be performed before these two other steps. The resting bracket 13 may be attached below the opening 3.

[0069] The method further comprises, at block 34, connecting a clamping element 10, e.g. two or more clamping elements, to the housing 2 such that the pivot shaft 4 is kept in place while tilting the journal assembly. The method further comprises, at block 35, pulling the rope 12, thereby rotating the pivot shaft 4 and tilting the journal assembly 6 out of the housing 2 of the pulverizer. And the method further comprises, at block 36, resting the journal assembly 6 on the resting bracket 13.

[0070] Figure 7 schematically illustrates a side view of a journal assembly of a bowl mill pulverizer being tilted out of the pulverizer. The above steps of method 30 may be schematically represented in the example of this figure. The position of the journal assembly, and specifically the lug 11 and the rope 12, can be seen at different moments during the tilting out process. The evolution of the center of gravity (C.G.) of the journal assembly can also be seen in the figure. In figure 7, the lug 11 is attached to the journal assembly 6. At the beginning, the journal assembly rests on the grinding table 8 of the pulverizer. When the rope 12 is pulled, the pivot shaft 4, the clamping element(s) 10 and the frame 19 enable the tilting of the journalassembly 6 towards and outside of the housing 2. At the end, the journal assembly 6 rests on the resting bracket 13.

[0071] In order to control the tilt out movement, traction is to be applied at all times to the rope. A final portion of the tilt out movement, the traction does not necessarily cause the movement, but rather controls the movement i.e. the journal assembly may have a tendency to pivot outwards due to its weight, whereas the traction on the rope controls such movement.

[0072] In some examples, (illustrated in dotted lines in figure 8), the end position of the tilting out movement may coincide with a substantially vertical position of the rotational axis of the grinding roll (which coincides with the symmetry axis of the journal assembly). With such an end position, the position of the journal assembly is more easily maintained since there is no tilting moment pushing the journal assembly forward or backward due to the weight of the journal assembly. The shape and size of resting bracket may be designed such that this is the end position.

[0073] The lug 11 may be removed at this moment if desired. The grinding mechanism 7, e.g. a grinding roller, may be removed or inspected and other maintenance may be performed. A new grinding roll or mechanism may be attached to the journal assembly 6 if necessary. Or maintenance operators may enter the pulverizer to perform any suitable task inside.

[0074] Once one or more maintenance operations have been performed, the journal assembly 6 may be tilted back in. In order to provide suitable traction on the rope to pull the journal assembly upwards and inwards, the rope 12 around as second pulley 20 comprised in the frame 19, e.g. a top pulley. In these or other examples, the method may further comprise connecting the rope 12 to an different attachment point 27 of the lug 11. Between tilting out and tilting in, the rope 12 may be detached from the first attachment point 26 of the lug 11 and then may be removably attached to the second attachment point 27 of the lug 11.

[0075] The method may now further comprise pulling the rope 12 and tilting the journal assembly 6 into the housing 2 of the pulverizer by rotating the pivot shaft 4 supporting the journal assembly 6. The journal assembly 6 may end up resting again on the grinding table 8.

[0076] Figure 8 schematically illustrates a side view of a journal assembly of a bowl mill pulverizer being tilted into the pulverizer. The above steps for tilting in the journal assembly 6 are represented in the example of this figure 8.

[0077] In figure 8, the lug end of the rope 12 has been attached to a different, specifically further away from the lug center, attachment point 27. Also, the rope 12 is now guided around the second pulley, specifically in this case the top pulley. The rope 12 is further guided to an extent around the bottom pulley too. At the beginning of the tilting in process, the journalassembly rests on the resting bracket 13. The rope 12 is pulled for tilting the journal assembly in.

[0078] Figure 8 shows examples of positions of the lug 11 at different moments during the tilt in process. The evolution of the center of gravity (C.G.) of the journal assembly can also be seen in the figure (indicated by the circle sector in the middle of figure 8). After an initial rotation, the journal assembly will have a tendency (due to its own weight) to rotate back into the housing. Traction in the rope is maintained to control this process.

[0079] At the end, the journal assembly 6 rests again on the grinding table 8. The rope 12 may be disconnected from the lug 11. The elements of the kit may be removed, e.g. the resting bracket 13, the clamping element(s) 10 and the frame 19 may be removed, and the cover may then be attached to close the opening 3.

[0080] Explanations and details of the previous aspects may be applied and incorporated to this aspect, and vice versa.

[0081] This written description uses examples to disclose a teaching, including the preferred embodiments, and also to enable any person skilled in the art to put the teaching into practice, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques within the scope of this disclosure. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim.

Claims

CLAIMS1. A kit for performing maintenance on a bowl mill pulverizer, the kit including:a lug having an attachment point for a rope of a lifting device, the lug being configured to be removably attached to a journal assembly of the pulverizer;a frame configured to be attached to a portion of a housing of the pulverizer surrounding a top portion of an opening in the housing providing access to an inside of the pulverizer, the frame comprising a first pulley configured to guide the rope;a resting bracket configured to support the journal assembly after it has been tilted out through the opening; anda clamping element configured to keep a pivot shaft of the pulverizer in place while tilting the journal assembly.

2. The kit of claim 1, wherein the kit comprises a plurality of clamping elements configured to keep the pivot shaft of the pulverizer in place.

3. The kit of claim 2, wherein the clamping elements are substantially C-shaped clamps.

4. The kit of any of claims 1 - 3, the frame further comprising a second pulley configured to guide the rope of the lifting device, wherein the pulleys are arranged above each other in a front region of the frame.

5. The kit of any of claims 1 - 4, wherein the frame comprises a backplate comprising a bottom portion with an arc-shaped recess.

6. The kit of any of claims 1 - 5, wherein the resting bracket comprises a first segment configured to be attached to the housing of the pulverizer and a second segment configured to be connected to the journal assembly.

7. The kit of any of claims 1 - 6, wherein the lug comprises a first attachment point to attach the rope for tilting the journal assembly out of the pulverizer housing, and a second attachment point to attach the rope for tilting the journal assembly into the pulverizer housing.8.The kit of any of claims 1 - 7, further comprising the rope connectable to the lug.

9. A method for performing maintenance on a bowl mill pulverizer, the method comprising:attaching a frame comprising a pulley to a portion of a housing of the pulverizer surrounding a top portion of an opening that provides access to an inside of the pulverizer;connecting a lug to a journal assembly and passing a rope around the pulley; attaching a resting bracket to the housing of the pulverizer to support a journal assembly pivotably mounted on a pivot shaft of the pulverizer;connecting a clamping element to the housing such that the pivot shaft is kept in place while tilting the journal assembly;pulling the rope, thereby rotating the pivot shaft and tilting the journal assembly out of the housing of the pulverizer; andresting the journal assembly on the resting bracket.

10. The method of claim 9, further comprising:pulling the rope and tilting the journal assembly into the housing of the pulverizer by rotating the pivot shaft supporting the journal assembly.11.The method of claim 9 or 10, wherein the frame comprises a plurality of pulleys.

12. The method of claim 10 and 11, wherein the rope is passed around a first pulley of the plurality of pulleys for tilting the journal assembly out of the housing, and the method further comprising passing the rope around a second pulley of the plurality of pulleys for tilting the journal assembly into the housing.

13. The method of claim 12, wherein the first pulley is arranged vertically lower than the second pulley.

14. The method of any of claims 13- 15, further comprising connecting the rope to a different attachment point of the lug for tilting the journal assembly into the housing.1715. The method of any of claims 9 - 14, wherein the resting bracket is attached to the housing below the opening.

16. The method of any of claims 9 - 15, the method further comprising removing a grinding mechanism connected to the journal assembly from the pulverizer and attaching a new grinding mechanism to the journal assembly.

17. A system comprising:a bowl mill pulverizer, including a housing having an opening providing access to an inside of the pulverizer, and a pivot shaft supporting a journal assembly;and the system further comprisinga lug connected to the journal assembly of the pulverizer;a frame attached to a portion of the housing of the pulverizer surrounding a top portion of the opening providing access to an inside of the pulverizer, the frame comprising a pulley configured to guide a rope of a lifting device;a resting bracket configured to support the journal assembly after it has been tilted out through the opening in the housing; anda clamping element configured to keep the pivot shaft of the pulverizer in place while tilting the journal assembly.

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