EP3715715B1 - Grate bar for a furnace with a travellnig grate - Google Patents

Description

The invention relates to a grate plate for a sliding grate furnace according to the preamble of claim 1. The invention also relates to a sliding grate furnace with the features of claim 9 and a method for operating a sliding grate furnace with the features of claim 11. DE 93 12 738.3 describes a grate element for moving grates for waste incineration plants, in which a wear plate is detachably and exchangeably arranged on a step element by means of a clamping device.

EP-A1-2 381 174 A1 describes a generic grate plate with a cladding element for incinerators, in which a channel for guiding a cooling medium is formed between an upper plate provided with a weld cladding and a lower plate. The cladding element is produced as a whole as a flat object and can then be bent into a shape.

EP-A1-1 705 425 describes a grate bar of a grate covering for an incineration furnace, in which a non-metallic, in particular ceramic, layer is applied to the grate bar, the layer being attached to the grate bar by gluing, cementing or mechanical connection.

DE-C1-196 13 507 describes a grate plate for advancing grates of waste incineration plants, in which a single wear plate is prepared for a material to be fired, the wear plate being replaceable Component is arranged on a base body provided with coolant channels of the grate plate.

WO-A1-2016 / 198119 describes a grate block for a combustion grate, which is designed as a cast part made of one material, wherein a surface exposed to abrasive wear has a wear mark.

It is the object of the invention to provide a grate plate for a sliding grate furnace which has a long service life.

This object is achieved according to the invention for a grate plate mentioned at the beginning with the features of claim 1. The integral connection of the wear plate to the base body, preferably by means of welding, creates a permanent and secure unit of base body and grate plate.

In the context of the invention, an integral connection is understood to mean soldering or welding of the parts to be connected.

Depending on the design of the details, the wear plate can also have a structurally supporting function for the structure of the grate plate, so that a unit that is mechanically stable in accordance with the requirements is only created through the integral connection of the base body and wear plate.

In the context of the invention, the base body comprises parts of the grate plate that are not exposed to increased wear. Depending on requirements, these parts can be made of less wear-resistant material. At least in the area of its surface, the wear plate consists of a material that is more wear-resistant than other parts of the grate plate. Preferably, but not necessary, the surface hardness of the wear plate is at least 10 HRC greater than the surface hardness of less wear-resistant parts of the base body. In the context of the invention, the base body is not necessarily a closed or independently stable object, but can also comprise several parts that are connected to one another by the wear plate.

In particular, the base body can comprise two side plates which are oriented essentially perpendicular to the wear plate and which are each welded to the wear plate.

A sliding grate furnace in the sense of the invention has a sliding grate for the active transport of fuel lying on it. The sliding grate is made up of a plurality of grate plates which are held on brackets of the sliding grate. To transport the fuel, at least some of the grate plates are generally moved, in particular alternately.

In conventional designs of the sliding grates, several grate plates are arranged next to one another and form a row of grate plates. The grate plates in a row lie loosely on a row of grate plates that follows in the pushing direction. These rows can be shifted against each other alternately. Depending on the design, all rows can be movable, for example, or just some of the rows.

Push grate furnaces within the meaning of the invention are used in particular in firing systems of wood power plants or waste incineration systems.

Combustion air for the fuel is usually supplied from below through the sliding grate.

According to the invention, the wear plate has a support layer, preferably made of a heat-resistant alloy, and a wear-resistant layer that is firmly bonded to the support layer. This allows a particularly simple and secure material connection of the wear plate to the base body, in particular by welding the support layer. The base layer can generally preferably consist of an iron-based alloy or a steel. Other base alloys are conceivable depending on the requirements.

In a preferred development, the wear-resistant layer can be applied to the base layer by thermal deposition, preferably by means of build-up welding, particularly preferably by means of open-arc build-up welding.

Open-arc build-up welding is electrical build-up welding without the need for externally supplied shielding gas. Open-arc build-up welding is preferably carried out in conjunction with cored wire.

Wear plates with a base layer and a wear-resistant layer thermally applied to the base layer can preferably be produced on a large scale as semi-finished products. On such panels as a semi-finished product, after the hard layer has been applied, straightening measures to ensure planarity, for example mechanical straightening by means of a roller, can be carried out. Wear plates for the production of the grate plates according to the invention can then be cut out of the semifinished product. The wear plates can be cut to size by plasma cutting, laser cutting or water jet cutting can also be carried out depending on the accuracy requirements.

The wear-resistant layer applied can typically have a thickness of several millimeters. It can contain high proportions of carbon, chromium, niobium, boron, tungsten, vanadium, molybdenum, manganese, silicon and / or other elements. The application can be carried out in one or more passes, whereby welding beads can have a linear, wave-shaped, zigzag-shaped or other suitable course. In order to improve the advance of fuel on the sliding grate furnace, the welding beads are particularly preferably oriented transversely to a conveying direction of the sliding grate.

With regard to the choice of material for the wear plate, it can be provided, depending on the requirements, that the entire wear plate is heat-resistant up to at least 500 ° C., preferably up to at least 600 ° C., in continuous operation.

In the interests of a particularly long service life, it can preferably be provided that the surface of the wear plate facing the fuel has a hardness of at least 50 HRC, particularly preferably at least 56 HRC.

According to the invention, at least one second wear plate is provided, the second wear plate adjoining the first wear plate to form a surface extending over the two wear plates, one surface of the second wear plate being angled towards the surface of the first wear plate. In this way, even more complex shaped surfaces can be produced by using several pieces or adjoining wear plates. In particular, this allows complex shapes of existing grate plates without special Wear protection are reshaped so that the grate plates according to the invention can be used directly as a substitute for existing grate plates.

According to the invention, the second wear plate is cohesively connected to the first wear plate by means of welding. In this way, non-wear-resistant structures in the surface, such as webs or the like arranged between the wear plates, are avoided.

In the interest of cost-effective production of the entire grate plate, the base body can be at least partially, preferably completely, formed by means of cutouts from plate-shaped semi-finished products. The individual components of the base body or cutouts made of semi-finished products can be welded to one another. The semi-finished product can in particular consist of the same material as a base layer of the wear plates in order to ensure optimal properties and simple logistics.

In an alternative or supplementary embodiment of the invention, the base body can be designed at least partially, preferably completely, as a cast part. In particular, it can be a cast steel. Such cast parts can be produced in large numbers in a particularly cost-effective manner. If necessary, the cast part can be reworked in order to apply the wear plate in a materially bonded manner.

To improve the combustion in the sliding grate furnace, the wear plate can have at least one closed opening, preferably through hole, for the passage of combustion air. Such breakthroughs or bores are preferably made after the wear plate has been manufactured and can be in number and Arrangement be individualized. In particular, the grate plates can have different arrangements of openings depending on the intended installation location in the sliding grate.

In a further, generally advantageous embodiment of the invention, a lower wear plate is arranged on an underside of the base body not facing the fuel. The lower wear plate preferably rests on an adjacent grate plate during operation. As a result, wear caused by surfaces of two grate plates that are moved relative to one another rubbing directly against one another is reduced overall.

The object of the invention is also achieved by a sliding grate furnace, a solid fuel being conveyed on the sliding grate, comprising a grate plate according to the invention.

In a preferred development, only some of the interchangeable grate plates of the sliding grate furnace according to one of claims 1 to 8 are formed, preferably between 10% and 90% of the interchangeable grate plates. This makes it possible to replace only worn conventional grate plates for wear-resistant grate plates according to the invention when an existing furnace is being serviced. Alternatively or in addition, it is made possible that only those grate plates of the sliding grate are formed by grate plates according to the invention that are also subject to particularly high wear during operation. Overall, this can significantly optimize the costs of operating a sliding grate furnace and extend maintenance intervals.

1. a. Bestückung nur eines Teils des Schubrostes mit erfindungsgemäßen Rostplatten, wobei andere Rostplatten des Schubrostofens keine Schleißplatte aufweisen;
2. b. Aufnahme eines regulären Betriebs des Schubrostofens mit der Bestückung gemäß Schritt a.

The object of the invention is also achieved by a method for operating a sliding grate furnace according to the invention, characterized by the steps:

1. a. Equipping only part of the sliding grate with grate plates according to the invention, other grate plates of the sliding grate furnace not having a wear plate;
2. b. Start of regular operation of the sliding grate furnace with the equipment according to step a.

Fig. 1

zeigt eine seitliche Draufsicht auf eine erfindungsgemäße Rostplatte.

Fig. 2

zeigt eine Draufsicht von unten auf die Rostplatte aus Fig. 1.

Fig. 3

zeigt eine Draufsicht von unten auf eine erste Abwandlung der Rostplatte aus Fig. 1.

Fig. 4

zeigt eine Draufsicht von unten auf eine zweite Abwandlung der Rostplatte aus Fig. 1.

Fig. 5

zeigt eine Draufsicht auf einen Ausschnitt eines Schubrostes mit Rostplatten gemäß Fig. 1 bis Fig. 4.

A preferred embodiment of the invention is described below and explained in more detail with reference to the accompanying drawings.

Fig. 1

shows a side plan view of a grate plate according to the invention.

Fig. 2

shows a plan view from below of the grate plate Fig. 1 .

Fig. 3

FIG. 13 shows a plan view from below of a first modification of the grate plate from FIG Fig. 1 .

Fig. 4

FIG. 11 shows a plan view from below of a second modification of the grate plate from FIG Fig. 1 .

Fig. 5

shows a plan view of a section of a sliding grate with grate plates according to FIG FIGS. 1 to 4 .

In the Fig. 1 The grate plate 1 shown is intended for use in a sliding grate furnace. On the sliding grate 2 (see Fig. 4 ) solid fuel, for example wood or garbage, is conveyed to the sliding grate furnace. A sliding grate furnace in the sense of the invention has a sliding grate for the active transport of fuel lying on it. The sliding grate is made up of a plurality of grate plates which are held on brackets of the sliding grate. To transport the fuel, at least some of the grate plates are generally moved, in particular alternately.

In the present design of the sliding grate 2, several grate plates 1 are arranged next to one another and form a row 2a of grate plates 1. The grate plates 1 of a row 2a lie loosely on one row 2a of grate plates 1 following in the thrust direction. These rows 2a can be shifted against each other alternately. Depending on the design, all rows 2a can be movable, for example, or only some of the rows 2a.

Push grate furnaces within the meaning of the invention are used in particular in firing systems of wood power plants or waste incineration systems. Combustion air for the fuel is generally supplied from below through the sliding grate 2.

The grate plate 1 has a base body 3 for detachable attachment to a holder (not shown) of the sliding grate 2. A first wear plate 4 is arranged on the grate plate 1, the wear plate 4 having a wear-resistant surface 5 facing the fuel. In the present case, the wear plate 4 is materially connected to the base body 3 by means of welding. The integral connection of the wear plate to the base body 3 by means of welding creates a permanent and secure unit of base body 3 and grate plate 4.

In the present case, the wear plate also has a structurally supporting function for the structure of the grate plate 1, so that a mechanically stable unit is only created through the material connection of the base body 3 and wear plate 4.

The base body 3 comprises side parts 6 of the grate plate 1, which are not exposed to increased wear. In addition, the side parts 6 are connected to one another by transverse webs 11

In the area of its surface 5, the wear plate 4 consists of a material that is more wear-resistant than the side parts 6 of the grate plate 1. In the present case, the side parts are made of heat-resistant steel 16Mo3.

A surface hardness of the wear plate 4 is considerably more than 10 HRC greater than a surface hardness of the side parts 6 of the base body 3. The base body 3 comprises several parts 6 which are connected to one another by the wear plate 4. The side plates 6 of the base body 3 are oriented essentially perpendicular to the wear plate 4 and are each welded to the wear plate 4.

The wear plate 4 has a support layer 7 made of a heat-resistant alloy, in the present case the same heat-resistant steel 16Mo3 from which the side parts 6 are also made. A wear-resistant layer 8 is materially connected to the support layer 7. This allows a particularly simple and secure material-locking fixing of the wear plate 4 to the base body, in particular by welding the support layer 7.

The wear-resistant layer 8 was applied to the base layer 7 by thermal application, in the present case by means of open-arc build-up welding. Open-arc build-up welding is electrical build-up welding without the need for externally supplied shielding gas. Open-arc build-up welding is preferably carried out in conjunction with cored wire.

The wear plate 4 with the support layer 7 and the wear-resistant layer 8 thermally applied to the support layer 7 was produced in the present case on a large scale as a semi-finished product. After the hard layer 8 had been applied, straightening measures to ensure planarity, namely mechanical straightening by means of a roller, were carried out on the plates as a semi-finished product. The semi-finished product then became the Wear plate 4 cut out for the production of the grate plate 1 according to the invention. The wear plate 4 was cut to size by plasma cutting, but it can also be done by laser cutting or water jet cutting, depending on the accuracy requirements.

The applied wear-resistant layer 8 has a thickness of several millimeters. It can contain high proportions of carbon, chromium, niobium, boron, tungsten, vanadium, molybdenum, manganese, silicon and / or other elements. The application can be carried out in one or more passes, whereby welding beads can have a linear, undulating, zigzag or other suitable course. In order to improve the advance of fuel on the sliding grate furnace, the welding beads are in the present case oriented transversely to a conveying direction F of the sliding grate 2.

With regard to the choice of material for the wear plate 4, it is provided that the entire wear plate is heat resistant up to at least 600 ° C. in continuous operation. In the interest of a particularly long service life, it is also provided that the surface 5 of the wear plate 4 facing the fuel has a hardness of at least 50 HRC, particularly preferably at least 56 HRC.

The wear-resistant layer 8 was for the present embodiment with a commercially available filler wire, the product "Durmat FD 65" from Durum Verschleiss-Schutz GmbH, Carl-Friedrich-Benz-Str. 7, D-47877 Willich, Germany applied by means of open-arc build-up welding. Durmat FD 65 is an alloy with essentially the following components (mass%) in the applied weld metal: C. Si Mn Cr Mon Nb V. W. Fe 5.2 1 0.4 21 7th 7th 1 2 rest

The hardness achieved by the wear-resistant layer 8 is thus> 63 HRC at room temperature and 57 HRC at 600 ° C. The heat resistance is above 600 ° C.

In the grate plate according to the invention, a second wear plate 9 is also provided, the second wear plate 9 adjoining the first wear plate 4 to form a surface F extending over the two wear plates 4, 9. The surface of the second wear plate 9 is oriented at an angle to the surface of the first wear plate 4, in the present case at an angle of approximately 45 °. In addition, a third, end-face wear plate 10 is provided, which in turn adjoins the second wear plate 9 and whose surface is angled with respect to the second wear plate 9, namely by 45 °. The third wear plate 10 is thus aligned essentially perpendicularly with respect to the first wear plate 4.

As a result, a more complex shaped surface is produced by several pieces or mutually adjoining wear plates 4, 9, 10. In particular, a complex shape of an existing grate plate is reshaped without special wear protection, so that the grate plate 1 according to the invention can be used directly as a substitute for existing grate plates. In the present case, the grate plates to be substituted consist of one-piece cast steel parts without special wear protection elements.

The second wear plate 9 is directly connected to the first wear plate 4 in a materially bonded manner by means of welding. The third wear plate 10 is also materially bonded to the second by means of welding Wear plate 9 directly connected. In this way, non-wear-resistant structures in the surface, such as, for example, webs or the like arranged between the wear plates, are avoided.

In the present case, the structure of the second and third wear plate 9, 10 from a base layer 7 and a wear-resistant layer 8 is identical to the first wear plate 4.

In the interest of a cost-effective production of the entire grate plate 1, the base body 3 is at least partially, preferably completely, formed by means of cutouts 6, 11 from plate-shaped semi-finished product. The individual components of the base body 3 or cutouts made of semifinished product, in this case the side parts 6 and the transverse webs 11, are welded to one another. In the present case, the semi-finished product consists of the same material as the support layer 7 of the wear plates 4, 9, 10 in order to ensure optimal properties and simple logistics.

To improve the combustion in the sliding grate furnace, the wear plate 4 has a number of closed openings 12, in the present case through bores, for the passage of combustion air. Such openings or through-bores 12 are preferably made after the wear plate 4 has been manufactured and can be individualized in terms of number and arrangement.

In particular, the grate plates 1 have different arrangements of openings 12 depending on the intended installation location in the sliding grate 2 Figures 2 to 4 Views of three modifications of grate plates 1 according to the invention, which are at different positions of the sliding grate according to the occupancy plan Fig. 5 can be used. The side view of the three modifications of grate plates 1 is the same and corresponds Fig. 1

The grate plate 1 according to Fig. 2 is used as a quasi-infinite repeating unit in the middle of the respective rows 2a of grate plates 1. It has bores 12 distributed over the entire width of the first wear plate 4.

The grate plate 1 according to Fig. 3 has the same width as the grate plate after Fig. 2 , but is only provided with bores 12 over about half its width. This grate plate is used at the edge of a row 2a (see approx Fig. 5 , top row, rightmost grate plate 1.

The grate plate 1 according to Fig. 4 is only about half the width of the grate plates Fig. 2 and Fig. 3 . This grate plate 1 has no openings 12. It is used, for example, in the second row 2a from above at the left edge position, so that a lateral offset and overlap of the grate plates 1 of two successive rows 2a is achieved.

The left grate plate 1 of the top row 2a corresponds to a reflection of the grate plate 1 according to FIG Fig. 3 . The right grate plate of the second row 2a from above corresponds to a reflection of the narrow grate plate 1 Fig. 4 . A total of five structurally modified grate plates 1 are therefore used to build the sliding grate 2 Fig. 5 used.

In the case of the present sliding grate 2, every second row 2a of grate plates 1 is arranged on a stationary holder, and the row 2a of grate plates 1 lying between them is arranged on a drivably movable holder. The movable rows 2a are moved in the conveying direction F (see Fig. 5 ) moved alternately in order to transport the fuel located on the sliding grate 2. For receiving on the brackets, which are essentially as transverse to the conveying direction F Extended rods are formed, the side parts 6 have corresponding recesses 6a.

During this movement, one of the grate plates 1 slides with a lower support area on the surface of one or more grate plates 1 of the following row 2a. To reduce wear, a lower wear plate 13 is arranged on an underside of the base body 3 that is not facing the fuel. The lower wear plate 13 rests on an adjacent grate plate 1 during operation. As a result, wear caused by surfaces of two grate plates 1 that are moved towards one another, rubbing directly against one another, is reduced overall. The structure of the lower wear plate 13 from a support layer 7 and a wear-resistant layer 8 is also identical to the first wear plate 4.

In the present case, only the sliding grate 2 of a sliding grate furnace is shown, the sliding grate furnace otherwise being designed in a known manner.

List of reference symbols

1

Grate plate

2

Thrust grate

2a

Row of grate plates

3

Base body

4th

Wear plate

5

Surface of the wear plate

6th

Side part of the main body

6a

Recesses

7th

Base layer of the wear plate

8th

Wear-resistant layer of the wear plate

9

second wear plate

10

third wear plate

11

Crossbar

12th

Breakthroughs, perforations

13th

lower wear plate

F.

Conveying direction

Claims (11)

1. Grate bar for a furnace with a travelling grate,

   wherein a solid fuel is being conveyed on the travelling grate (2), comprising

   a base body (3), in particular for a releasable fixing to a holder of the travelling grate (2), and

   at least one wear plate (4, 9, 19), wherein the wear plate (4, 9, 10) has a surface (5), the surface (5) being wear-resistant and facing towards the fuel;

   wherein the wear plate (4, 9, 10) is attached to the base body (3), in particular by means of welding,

   wherein at least a second wear plate (9, 10) is being provided, wherein the second wear plate (9, 10) adjoins to the first wear plate (4) in order to form a surface extending across both of the wear plates (4, 9, 10), wherein a surface of the second wear plate (9, 10) has an angled orientation to the surface of the first wear plate (4), and

   wherein the first and the second wear plate (4, 9, 10) have a carrier layer (7), in particular consisting of a heat-resistant alloy, and a wear-resistant layer (8), the wear resistant layer (8) being materially bonded to the carrier layer (7),

   characterized in that

   the second wear plate (9, 10) is materially bonded to the first wear plate (4) by means of welding.
2. Grate bar according to claim 1, characterized in that the wear resistant layer (8) is deposited on the carrier layer (7) by means of thermal deposition, in particular by means of deposition welding, in particular by means of open-arc deposition welding.
3. Grate bar according to one of the preceding claims, characterized in that the entire wear plate (4, 9, 10) is heat resistant up to at least 500 °C, in particular up to at least 600 °C, under permanent operation.
4. Grate bar according to one of the preceding claims, characterized in that the surface of the wear plate (4, 9, 10) facing the fuel has a hardness of at least 50 HRC, in particular at least 56 HRC.
5. Grate bar according to one of the preceding claims, characterized in that the base body (3) is formed at least partially, in particular completely, by means of sections from a plate-shaped, semifinished product.
6. Grate bar according to one of claims 1 to 5, characterized in that the base body is formed at least partially, in particular completely, as a cast part.
7. Grate bar according to one of the preceding claims, characterized in that the wear plate (4, 9, 10) has at least one enclosed aperture, in particular a throughbore, for the passing of combustion air.
8. Grate bar according to one of the preceding claims, characterized in that a bottom wear plate (13) is arranged at bottom side of the base body (3), the bottom side not facing the fuel, the bottom wear plate (13) in particular resting on a neighboured grate bar (1) during operation.
9. Furnace with a travelling grate, wherein a solid fuel is being conveyed on the travelling grate (2), comprising a grate bar (1) according to one of the preceding claims.
10. Furnace with a travelling grate according to claim 9, characterized in that only a fraction of grate bars (1) that can be mutually exchanged are provided according to one of claims 1 to 8, in particular between 10% and 90% of the mutually exchangeable grate bars (1).
11. Method for the operation of a furnace with a travelling grate according to one of claims 9 or 10, characterized by the steps:

    a. Assembly of only a part of the travelling grate (2) with grate bars according to one of claims 1 to 8, wherein other grate bars of the furnace with a travelling grate do not comprise a wear plate;

    b. Starting of a regular operation of the furnace with a travelling grate with the assembly according to step a.

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