AU3318499A - Coal pulveriser mill high wear components - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): MAGAZINE HILL PTY LTD Invention Title: COAL PULVERISER MILL HIGH WEAR COMPONENTS The following statement is a full description of this invention, including the best method of performing it known to me/us: IP Australia Documents received on: 4 JUN 1999 Batch No: 1 2 COAL PULVERISER MILL HIGH WEAR COMPONENTS This invention relates to high wear components in coal pulveriser mills and to coal pulveriser mills including those components.

Coal pulveriser mills generally comprise a carrier wheel having beater plates which is arranged for rotation within a mill lining. The mill lining has an outlet which is arranged generally tangentially with respect to the carrier wheel. Coal enters the mill at the centre of the wheel, is pulverised by the beater plates and exits the outlet tangentially with respect to the wheel.

The pulveriser mills can be 6 metres or more in diameter and 1 metre or more in width.

In conventional pulveriser mills, the mill lining is formed from a large number of discrete elements which are arranged as a laminate in generally side by side relationship about the carrier wheel. The mill lining is generally referred to as bar armour. At the junction between a generally circumferential portion of the mill lining and a generally radially extending wall section of the outlet is a wear 25 component generally referred to as nose armour. The nose armour is critical to the overall performance of the mill in that its close proximity to the rotating carrier wheel creates an airflow within the mill which draws coal particles into the mill by suction and expels particles from the mill by air pressure. Conventional nose armour is mounted in 10 to 15 mm sections in quantities from

S

approximately 100 to 1000 across the width of the mill with comparatively large wear allowance on the surfaces facing inwardly of the mill.

The beater plates which are carried by the carrier wheel are generally designed based on the mill conditions with H: \paulad\1eep\speci\MAGAZINE-HILL-coal-Pulveriser-mil .doc 4/06/99 3 regard to the type and condition of the coal to be milled, milling operating temperature and running speed. The design is usually a compromise and a balance is generally struck between strength of the beater plates and abrasive resistance.

Conventional pulveriser mills suffer from a number of disadvantages mainly due to the wear components such as the beater plates, bar armour or nose armour wearing out. Wear of the bar armour requires replacement of the large number of individual sections which form the bar armour about the circumference of the carrier wheel. Replacement of the individual sections is both time consuming and relatively expensive. The time taken to replace worn sections therefore, apart from the expense, means a considerable down time of the mill which is obviously disadvantageous.

The conventional nose armour arrangement is also disadvantageous because of the quantity of plates which need to be fitted when nose armour is replaced. This also results in considerable down time of the mill.

Furthermore, the gap between each plate is a possible path for air to be sucked through therefore effecting mill efficiency. The same gaps can also allow erosion of the 25 supporting structure which supports the nose armour leading to possible catastrophic failure of the mill. The large wear allowance of plates which typically takes place •thereby greatly affects mill efficiency.

Wear to the beater plates of the wheel results in the balance of the wheel being increasingly adversely affected which eventually requires the mill to be shut down and beater plates replaced.

Bar armour in conventional mills generally comprises thin segments which are located about the mill lining. Thus, in order to complete the mill lining, a very large number of H: \paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-mill.doc 4/06/99 4 components is required. The components are made relatively thin because of the heavy nature of the conventional components. In order to facilitate removal and replacement, the components must be of such a weight to enable reasonably easy movement of the components and this is why the components are thin and a large number is required.

The present invention is directed and providing wear components for a coal pulveriser mill which overcomes these problems.

The invention, in a first aspect, may be said to reside in a wear component for a coal pulveriser mill, said wear component comprising: a substrate of low wear resistant material; and a layer of high wear resistant material on the substrate.

Wear components according to the invention have the advantage that much larger components can be manufactured which have a high wear resistant surface so that a single part can replace a large number of the discrete sections of the bar armour or the number of plates which make up the nose armour. Thus, less individual bar armour components are required to form the mill lining thereby decreasing down time in replacement of worn components. Similarly, the nose armour can be formed from a single piece rather than a large number of individual plates thereby overcoming problems associated with replacement and also problems associated with the gap between each plate in conventional nose armour. Furtherstill, the high wear resistant surface of the components decreases the amount of wear for any given time period thereby greatly increasing the lifespan of the components and thereby decreasing the amount of replacement required and therefore the down time of the mill.

H:\paulad\Keepspeci\MAGAZINE-HILL-coal-pulveriser-mill.doc 4/06/99 5 Preferably the layer of high wear resistant material is applied to the substrate in a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.

According to one preferred embodiment of the invention in which the wear component is a beater plate, the beater plate comprises the substrate and the high wear resistant material applied to the substrate wherein the high resistant material is of greater thickness at high wear areas of the beater plate than other areas of the beater plate. Typically, the high wear resistant material tapers from a minimum width at one edge of the beater plate to a maximum width at the opposed edge of the beater plate.

In another embodiment the wear component is a nose armour and comprises a first wall section and a second wall section arranged transverse to the first wall section, the first and second wall sections having first surfaces which, when the nose armour is in place in the mill, are directed inwardly of the mill, the first surfaces being formed from the high wear resistant material, the first and second wall S25 sections having second surfaces which face outwardly of the S mill, the second surfaces carrying connection means for connecting the nose armour to a supporting structure of the mill.

Preferably the connection means comprises a plurality of brackets arranged on the second surfaces, the brackets having a cutout for receiving the support structure so as to connect the nose armour to the support structure.

Preferably the support structure comprises an RSJ beam and the cutouts are configured to match the configuration of the RSJ beam.

H: \paulad\Keep\speci\MAGAZINE-HILL-coa-pulveriser-mil .doc 4/06/99 6 Preferably the substrate is formed from carbon steel and the high wear resistant material is white iron.

Preferably the casting process by which the high wear resistant material is cast onto the substrate is in accordance with Australian patent Nos. 562569 and/or 583655, the contents of which are incorporated in this specification by this reference.

The invention may also be said to reside in a coal pulveriser mill including a wear component described with reference to the first aspect of the inventions and the preferred forms of the first aspect of the invention.

The invention also provides nose armour for a coal pulveriser mill, including: a first wall; a second wall arranged transverse to the first wall; the first and second walls having an inner surface which is arranged inwardly with respect to the mill when the nose armour is arranged within the mill and a second surface arranged outwardly of the mill when the nose armour is arranged within the mill; the inner surface being formed from a high wear resistant material coupled to the second surface; and connecting means coupled to the second surface a.° for attaching the nose armour to a support structure of the mill.

Preferably the high wear resistant material is cast onto a substrate by a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.

H: \paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-mil.doc 4/06/99 7 Preferably the nose armour comprises a one piece nose armour.

Preferably the second surface is formed by the substrate.

Preferably the substrate is formed from carbon steel and the high wear resistant material is formed from white iron.

The invention in a further aspect may be said to reside in a beater plate for a coal pulveriser mill, including: a substrate; and a high wear resistant material coupled to the substrate.

Preferably the high wear resistant material is cast onto the substrate by a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.

Preferably the high wear resistant material tapers from a minimum thickness in low wear areas of the beater plate to a greater thickness at high wear areas of the beater plate.

Preferably the high wear resistant material tapers from a minimum thickness at one edge of the beater plate to a •maximum thickness at an opposed edge of the beater plate.

Preferably the high wear resistant material is cast as an inlay into the beater plate, the ends of the beater plate being formed by the substrate.

In a further aspect of the invention, there is provided a radial liner bar mill lining for a coal pulveriser mill, including: H:\paulad\Keep\speci\MAGAZINE-HILL-coa.-pulveriser-mill.doc 4/06/99 8 a substrate; and a high wear resistant material coupled to the substrate.

Preferably the high wear resistant material is cast onto the substrate by a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.

Preferably the width of the radial liner bar is 10 to times greater than the width of a conventional liner segment.

Preferably the substrate has a U-shaped profile in crosssection.

A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a coal pulveriser mill according to the preferred embodiment; Figure 2 is a front view of a beater plate 25 according to the preferred embodiment of the invention; Figure 3 is an end view of the beater plate of Figure 2; "*Figure 4 is a top view of the beater plate of Figure 2; Figure 5 is a perspective view of a nose armour according to the preferred embodiment of the invention; Figure 6 is a front view of a radial liner bar according to the preferred embodiment of the invention; and Figure 7 is an end view of the liner bar of Figure 6.

H:\paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-mill.doc 4/06/99 9 With reference to Figure 1, coal pulveriser mills of the present type are generally well known and therefore only schematically shown in Figure 1. The mill comprises a generally cylindrical mill lining 10 within which is arranged a beater plate carrier wheel 12. The carrier wheel 12 carries a plurality of beater plates 14 arranged circumferentially about the wheel 12. A coal outlet 16 is arranged generally tangentially with respect to the wheel 12.

As shown in Figure 1, the mill lining 10 extends about the wheel 12 and generally defines the opening 16. The lining has a generally radial segment 10a which extends radially with respect to the lining portion 10b which is arranged closest to the wheel 12. Arranged between the sections 10a and 10b of the mill lining 10 is a nose armour The nose armour 20 is supported by an RSJ beam (not shown) of the pulveriser mill.

In conventional pulveriser mills, the lining 10 is formed from a large number of individual segments which are placed in side by side relationship in the form of a laminate to define the lining 10. The nose armour 20 is typically formed from a number of plates also arranged in side by side relationship. The segments which form the laminate extend across the width of the mill from one side of the mill to the other side of the mill. The mill is typically anywhere up to 6 metres or more in diameter and of width of approximately 1 metre or more. When the mill is in use, both the individual segments of the conventional mill which make up the lining 10 and the nose armour wear out and require replacement. The beater plates 14 of the wheel 12 also wear and wear of the beater plates also creates problems with the mill as is described above.

The lining 10 of the mill according to the preferred embodiment of the invention includes a plurality of radial H: \paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-mill.doc 4/06/99 10 liner bars 30 which extend across the width of the mill.

The bars 30 may extend the entire distance across the width and be, for example, up to 1 metre in length or a number of the bars may be placed side by side to extend across the width of the mill. Even if a number of bars are used, the number is significantly less than the conventional discrete segments which are arranged in laminate fashion across the width of the mill to make up the conventional lining 10. To complete the lining 10, a plurality of the bars 10', to 0on are arranged about the circumference of the lining from the nose armour 20 to end 16' of the outlet 16 and also along the section 10a of the outlet 16.

The nose armour 20 is preferably a single piece which extends across the entire width of the mill. The radial liner bars 30, the nose armour 20 and the beater plates 14 are all formed from a substrate which has applied to it in a casting process, preferably according to the above mentioned Australian patents, of a high wear resistant component which is subject to wear during use of the mill.

The high wear resistant component decreases the amount of wear for any given time period thereby decreasing the amount of replacement of components required in the mill S"and thereby decreasing down time of the mill. Furthermore, 25 the preferred structure of the components according to this invention results in fewer wear component parts in the mill S- and thereby decreases the down time of the mill during replacement of wear components. The preferred single piece S-structure of the nose armour 20 also results in rapid 30 fitting, eliminates gaps between discrete plates of conventional nose armour and presents the high resistant rir ~layer in the mill. The elimination of gaps decreases •o possible air paths through the nose armour which would otherwise affect mill efficiency and prevents erosion of the supporting structure to which the nose armour is attached.

H:\paulad\Keep\speci\AGAZINE-HILL-coal-pulveriser-mill.doc 4/06/99 11 The preferred form of the beater plates 14 are best shown with reference to Figures 2 to 4. With reference to these figures, the beater plates 14 comprise substrate 40 which has a rear surface 42 and side edges 44. The substrate defines a recess 46. Cast within the recess 46 is high wear resistant layer 48.

As best shown in Figure 3, the high wear resistant layer extends from bottom edge 50 of the plate 14 to top edge 52 of the plate 14. Furthermore, the layer 48 increases in thickness from the bottom edge to the top edge so as to present a greater thickness adjacent the top edge where maximum wear takes place.

The side edges 44 of the plates 14 may include ledges 54 which facilitate coupling of the beater plates into the beater wheel 12.

The preferred structure of the nose armour 20 is best shown in Figure 5. The nose armour 20 preferably has a first wall 60 and the second wall 62 arranged transverse to the first wall 60. The first and second walls 60 and 62 have an inner surface 64 and an outer surface 66. The inner surface 64 is directed inwardly when the nose armour 20 is arranged within the mill and the second surface 66 is directed outwardly of the mill. The walls 60 and 62 have a substrate 70 onto which is cast high wear resistant layer 72. The high wear resistant layer 72 defines the first surface 64 and the substrate 70 defines the second surface •30 66. The second surface 66 has brackets 76 coupled to it.

The brackets 76 have cutouts 78 which match the profile of a support RSJ (not shown) of the pulveriser mill. The nose piece 20 is attached to the pulveriser mill by locating the bracket 76 onto the RSJ.

The first and second walls 60 and 62 are made separately and are fabricated together to form the nose armour shown H: \paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-mill.doc 4/06/99 12 in Figure 5. The walls 60 and 62 are fabricated together by initially clamping the components in the configuration shown in Figure 5 and tack welding the brackets 76 to the second surface of the substrates 70. The walls 60 and 62 may be then welded along gusset shown by reference numeral The brackets 76 may then be completely welded to the substrate 70. As best shown in Figure 5, the brackets 76 have a gusset or cutout 77 which facilitates the weld which connects the walls 60 and 62 together.

Figures 6 and 7 show the preferred structure of the radial liner bars 30. The bars 30 have a substrate 80 onto which is cast wear resistant material 82. As is best shown in Figures 7, the substrate 80 has a generally U-shaped crosssection.

As is clearly evident from the configuration of the substrate 80, the profile of the substrate 80 may be of generally U-shaped configuration thereby greatly reducing the weight of the substrate 80. The application of the material 82 to the substrate 80 provides the hard wear face required by the bar armour without the need for solid construction of the substrate 80. Since the weight of the obar armour 30 shown in Figures 6 and 7 is greatly reduced by the ability of the substrate 80 to be profiled as shown in Figure 7, the bar armour 30 may be much wider than conventional bar armour without increasing the actual weight of the bar armour components relative to the thin S•conventional components. Thus, because the bar armour 30 components are much wider, less are required than in conventional mills. Furthermore, because the weight has not been increased even though the width of the bar armour °o has been increased, the bar armour is no more difficult to handle and manoeuvre than conventional bar armour segments.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within H: \paulad\Keep\speci\MACAZINE-HILL-coal-pulveriser-mill.dc 4/06/99 13 the art, it is to be understood that this invention is not limited to the particular embodiments described by way of example hereinabove.

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Claims (19)

1. 2. The component of claim 1 wherein the layer of high wear resistant material is applied to the substrate in a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.
2. 3. The component of claim 1 wherein the wear component is a beater plate, the beater plate comprises the substrate and the high wear resistant material applied to the substrate wherein the high resistant material is of greater thickness at high wear areas of the beater plate than other areas of the beater plate.
3. 4. The component of claim 1 wherein the wear component is a nose armour and comprises a first wall section and a second wall section arranged transverse to the first wall section, the first and second wall sections having first surfaces which, when the nose armour is in place in the mill, are directed inwardly of the mill, the first surfaces being formed from the high wear resistant material, the first and second wall sections having second surfaces which face outwardly of the mill, the second surfaces carrying connection means for connecting the nose armour to a supporting structure of the mill. 35 5. The component of claim 4 wherein the connection means comprises a plurality of brackets arranged on the second surfaces, the brackets having a cutout for receiving H:\paulad\Keep\speci\MAGAZINE-HILL-coapulveriser-mi1.doc 4/06/99 i 15 the support structure so as to connect the nose armour to the support structure.
4. 6. The component of claim 5 wherein the support structure comprises an RSJ beam and the cutouts are configured to match the configuration of the RSJ beam.
5. 7. The component of any one of claims 1 to 6 wherein the substrate is formed from carbon steel and the high wear resistant material is white iron.
6. 8. A coal pulveriser mill including a wear component according to any one of the proceeding claims
7. 9. Nose armour for a coal pulveriser mill, including: a first wall; a second wall arranged transverse to the first wall; the first and second walls having an inner surface which is arranged inwardly with respect to the mill when the nose armour is arranged within the mill and a second surface arranged outwardly of the mill when the nose armour is arranged within the mill; 25 the inner surface being formed from a high wear resistant material coupled to the second surface; and connecting means coupled to the second surface for attaching the nose armour to a support structure of the mill. The nose armour of claim 1 wherein the high wear resistant material is cast onto a substrate by a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the 35 substrate and high wear resistant material on solidification of the high wear resistant material. H: \paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-i11 .doc 4/06/99 16
8. 11. The nose armour of claim 9 wherein the nose armour comprises a one piece nose armour.
9. 12. The nose armour of claim 9 wherein the second surface is formed by the substrate.
10. 13. The nose armour of any one of claims 9 to 12 wherein the substrate is formed from carbon steel and the high wear resistant material is formed from white iron.
11. 14. A beater plate for a coal pulveriser mill, including: a substrate; and a high wear resistant material coupled to the substrate. Preferably the high wear resistant material is cast onto the substrate by a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.
12. 15. The beater plate of claim 14 wherein the high wear resistant material tapers from a minimum thickness in low wear areas of the beater plate to a greater thickness "at high wear areas of the beater plate. *e.
13. 16. The beater plate of claim 14 wherein the high OO. wear resistant material tapers from a minimum thickness at one edge of the beater plate to a maximum thickness at an opposed edge of the beater plate.
14. 17. The beater plate of claim 14 wherein the high 35 wear resistant material is cast as an inlay into the beater a plate, the ends of the beater plate being formed by the substrate. H: \paulad\Keep\speci\MAGAZINE-HILL-coal-pulveriser-mill .doc 4/06/99 17
15. 18. A radial liner bar mill lining for a coal pulveriser mill, including: a substrate; and a high wear resistant material coupled to the substrate.
16. 19. The lining of claim 18 wherein the high wear resistant material is cast onto the substrate by a casting process whereby the high wear resistant material is cast against the substrate so as to form a bond between the substrate and high wear resistant material on solidification of the high wear resistant material.
17. 20. The lining of claim 18 wherein the width of the radial liner bar is 10 to 15 times greater than the width of a conventional liner segment.
18. 21. The lining of claim 18 wherein the substrate has a U-shaped profile in cross-section.
19. 22. A wear component substantially as hereinbefore described with reference to nay one of the embodiments shown in the accompanying drawings. i Dated this 4th day of June 1999 30 MAGAZINE HILL PTY LTD By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and 35 Trade Mark Attorneys of Australia e* H: \paulad\Keep\speci\ AGAZINE-HILL-coa-pulveriser-mi l.doc 4/06/99