Boiler

Abstract

Boiler (1) for a solid fuel, for example pellets, comprising: a combustion unit (2) with a tilting grate (3) which can be tilted between a combustion position and a cleaning position, which has a grate surface (4) and primary air openings (16), wherein several cleaning elements (15) are movably mounted on the tilting grate (3), which are guided through the primary air openings (16) when the tilting grate (3) is tilted into the cleaning position.

Description

[0001] The invention relates to a boiler for a solid fuel, for example pellets, which has a firing unit with a tilting grate that can be tilted between a firing position and a cleaning position, which tilting grate has a grate surface and primary air openings, wherein a plurality of cleaning elements are movably mounted on the tipping grate, which are guided through the primary air openings when the tipping grate is tilted into the cleaning position, wherein a rotary shaft is provided as the tilting axis of the tipping grate, which is connected to a motor.

[0002] Furthermore, the invention relates to a method for cleaning a tilting grate of a boiler for a solid fuel, for example pellets.

[0003] Common solid-fuel boilers may be equipped with a tilting grate with grate openings. Tilting the tilting grate allows ash and slag to be removed from the grate surface. Furthermore, molten ash can stick to the grate openings during operation, potentially causing malfunctions.

[0004] In the prior art, it is known, on the one hand, to arrange stationary dies beneath the tilting grate, against which the tilting grate can be pivoted to clean the grate openings. However, a disadvantage is that cleaning the dies can be difficult. Furthermore, the dies can be exposed to different temperatures than the grate above. This can lead to the dies becoming bent and no longer fitting the primary air openings of the tilting grate, thus impeding cleaning. Another disadvantage is that the stationary dies take up a lot of space in the ash chamber beneath the tilting grate.

[0005] AT 503 043 B1 proposes a different type of forced grate cleaning. In this prior art, the grate is tilted downwards about a pivot axis on the side edge of the tilting grate. The tilting movement is limited by a stop which is adjusted so that in the lower position, movable upper grate parts are displaced. This cleans the air gaps formed between the movable upper grate parts and the fixed upper grate parts. A design with movable and fixed upper grate parts, however, is disadvantageous because the high thermal loads from the ember bed can cause the grate parts to warp. This can hinder cleaning. In one design variant of this prior art, a movable grate part in the form of a round bar is also provided, which is guided through an air opening in the center of the tilting grate during tilting.Thus, with this state-of-the-art technology, when the tipping grate is tilted, the grate sections (i.e., the parts forming the grate surface) are moved against each other, while a round bar is pushed through the central grate opening. However, this design is very complicated and also takes up a lot of space. Due to the height, deformation can also occur due to the temperature profile. This problem is further exacerbated by thermal insulation beneath the ash barrier.

[0006] EP 2 161 498 A1 discloses a boiler with a rotating grate that can be cleaned using stationary grate scraper elements.

[0007] US 422,472 A1 discloses a freestanding fire grate from the 19th century with a frame and a rotating grate section. A cleaning grid with cleaning elements is mounted on the rotating grate section via guide rails. The cleaning elements can penetrate into the gaps in the grate section as the grate section rotates.

[0008] In contrast, the invention aims to mitigate or eliminate at least some of the disadvantages of the prior art. The invention specifically aims to equip a boiler with a structurally simple and space-saving tilting grate that permanently and reliably cleans the primary air openings.

[0009] This object is achieved by a boiler having the features of claim 1 and a method having the steps of claim 15. Preferred embodiments are specified in the dependent claims.

[0010] According to the invention, the cleaning elements are designed to follow a tilting movement of the tilting grate.

[0011] In the method according to the invention for cleaning a tilting grate of a boiler for a solid fuel, for example pellets, the following step is carried out: tilting the tilting grate from a firing position into a cleaning position, wherein a rotary shaft is provided as the tilting axis of the tilting grate, which is connected to a motor, wherein cleaning elements movably mounted on the tilting grate are led out of the primary air openings by the tilting of the tilting grate, wherein the cleaning elements follow a tilting movement of the tilting grate.

[0012] By tilting the tilting grate, the cleaning elements are moved from a first end position, corresponding to the firing position of the tilting grate, to a second end position, corresponding to the cleaning position of the tilting grate. In the first end position, the upper edges of the cleaning elements are preferably substantially at the level of the grate surface or at most so far below the grate surface that the cleaning elements cannot emerge laterally from the passage openings. This can limit jamming of the cleaning elements due to thermal stress during firing operation and ensure the function of the cleaning elements. In the firing position, the cleaning elements therefore do not protrude beyond the preferably flat grate surface, which is preferably arranged substantially horizontally in the firing position. A uniform grate surface (i.e. without sections that can move relative to one another) is preferably provided.For example, the tilting grate can have a grate plate, the upper side of which forms the grate surface and which has recesses for forming the primary air openings. The cleaning elements are preferably mounted on the tilting grate in such a way that the upper edges of the cleaning elements in the firing position are essentially flush with the upper side of the grate plate, i.e. with the grate surface, or lie below it by only less than the wall thickness of the grate plate. When the tilting grate is in the cleaning position, the cleaning elements protrude upwards above the grate surface. The relative movement between the cleaning elements and the primary air openings cleans the primary air openings of deposits. By arranging several cleaning elements, the primary air openings can be freed from deposits such as ash or slag over a large area and thoroughly.Because the cleaning elements are mounted on the tilting grate, forced cleaning of the primary air openings is ensured when the tilting grate is tilted into the cleaning position. This reliably guarantees the primary air supply for operation. Tilting the tilting grate also cleans the grate surface of loose residues such as ash and slag. Because the cleaning elements are mounted on the tilting grate and follow the tilting movement of the tilting grate, no additional space is required for stationary matrices in the ash chamber below the tilting grate. This means that a larger volume of ash can be accommodated in the ash chamber. Because the cleaning elements are mounted on the tilting grate itself, the cleaning elements are essentially at the same temperature level as the grate surface with the primary air openings.This prevents deformation of the cleaning elements due to temperature differences, ensuring a precise passage of the cleaning elements through the primary air openings. Advantageously, functional impairments due to thermally induced deformation can be largely avoided. Due to the multiple cleaning elements, several primary air openings can be reliably cleaned.

[0013] All location and direction references, such as "top", "bottom", "up", "down", "vertical", "horizontal", etc., in this disclosure refer to the operating position of the boiler on a flat, horizontal base surface.

[0014] In a preferred embodiment, the tilting grate has at least three, in particular at least four, primary air openings and a corresponding number of cleaning elements. The primary air openings extend at intervals, in particular at constant intervals, from one another on the tilting grate, whereby the grate surface on the upper side of the tilting grate is divided into individual sections.

[0015] With regard to a compact design, it is advantageous if the cleaning elements are mounted on the tilting grate so that they can pivot about a pivot axis. In this design, the tilting movement of the tilting grate is converted into a pivoting movement of the cleaning elements. By pivoting the cleaning elements, the cleaning elements emerge from the primary air openings in order to clean the tilting grate. The pivot axis can be formed by an axis which is mounted in openings in the tilting grate below the grate surface (relative to the firing position). The openings can be formed on an extension which extends downwards from the grate surface. The maximum pivot angle of the cleaning elements between the first and the second end position relative to the grate surface is preferably at least 5, preferably at least 9 degrees, in particular substantially 10 degrees.

[0016] In order to enable extensive and thorough cleaning of the tipping grate, the pivot axis of the cleaning elements runs along a lateral edge area of ​​the tipping grate in a preferred design.

[0017] In a preferred embodiment, the primary air openings are designed as primary air slots and the cleaning elements as cleaning plates, in particular cleaning sheets, wherein the cleaning plates are preferably arranged upright (i.e. substantially perpendicular to the grate surface) on the tilting grate. The cleaning plates are preferably elongated, with the elongated cleaning plates preferably being arranged horizontally (i.e. along the primary air slots). This ensures a low overall height of the tilting grate with the cleaning elements. Advantageously, the cleaning elements are essentially at the same temperature level as the tilting grate during combustion. The primary air slots enable effective air supply to the combustion chamber, with the cleaning plates ensuring extensive cleaning of the grate surface.

[0018] To keep the grate surface free of deposits, it is preferably provided that the primary air slots extend over more than half the length of the grate surface, in particular over more than three-quarters of the length of the grate surface, with the cleaning plates preferably extending substantially over the entire length of the primary air slots. The cleaning plates are preferably arranged in the primary air slots with lateral and / or frontal clearance to allow the passage of the primary air.

[0019] In order to guide the cleaning elements out of the primary air openings by tilting the tilting grate, it is advantageous if the tilting grate has an actuating element, in particular an actuating rod, which is mounted so as to be movable relative to the grate surface and which is moved against a first stationary stop on the combustion unit when the tilting grate is tilted into the cleaning position. Thus, when the tilting grate is moved into the cleaning position, the actuating element is pressed against the first stationary stop (i.e. stop which does not tilt with the tilting grate) so that the cleaning elements are pushed out beyond the grate surface. Advantageously, no separate drive is required for moving the cleaning elements. Tilting the tilting grate against the first stop simultaneously forces the cleaning elements out of the grate surface.For this purpose, the actuating element can be connected to the individual cleaning elements, in particular via retaining openings. If the actuating element is designed as an actuating rod, the actuating rod can penetrate the individual cleaning elements at a distance from the pivot axis, in particular at the free end regions opposite the pivot axis of the cleaning elements. The actuating rod can have spacer rings that keep the cleaning elements at a distance. Accordingly, the pivot axis of the cleaning elements can have further spacer rings that also keep the cleaning elements at a distance.

[0020] In a preferred embodiment, the cleaning elements are mounted on the tilting grate, in particular pivotably mounted, in such a way that when the tilting grate is tilted into the cleaning position, the cleaning elements are moved, in particular pivoted, exclusively by gravity into the second end position, in which the cleaning elements protrude from the primary air openings of the tilting grate. Thus, in this embodiment, the cleaning elements can be arranged in the second end position, in particular before reaching a first stationary stop. This can be achieved by a suitable selection of the center of gravity of the cleaning elements relative to the center of gravity of the tilting grate and a corresponding arrangement of the tilting axis of the tilting grate.However, in this embodiment, too, the first stationary stop is preferably provided, which reliably brings the cleaning elements into the second end position even when the primary air openings are dirty.

[0021] To ensure that the cleaning elements are reliably returned below or at the level of the grate surface when the tilting grate is transferred, it is advantageous if the firing unit has a second stationary stop against which the actuating element is moved when the tilting grate is tilted into the firing position. When the tilting grate is tilted into the firing position, the actuating element is pushed onto the second stationary stop (i.e., one that does not tilt with the tilting grate), which pushes the cleaning elements back into their first end position—in addition to the effect of gravity. The second stationary stop ensures that the cleaning elements are fully returned, independent of gravity.

[0022] A simple design is achieved if the first and / or second stationary stop are formed on a stop plate, on which the tilting axis of the tilting grate is preferably mounted. An even more stable design is provided in which two stop plates, each with a first and a second stationary stop, are provided on opposite sides, particularly the long sides, of the tilting grate. Two opposite ends of the actuating element are pushed onto the first stationary stops upon reaching the cleaning position and onto the second stationary stops upon reaching the firing position.

[0023] In order to ensure defined end positions of the movement of the cleaning elements, the tilting grate in a preferred embodiment has a guide for the actuating element, wherein the guide limits the movement of the actuating element relative to the grate surface.

[0024] To ensure a simple, reliable design, the guide can have at least one elongated guide hole along which the actuating element is guided. The ends of the elongated guide hole define the first and second end positions of the actuating element's movement. Depending on the design, two elongated guide holes can be provided, particularly on opposite edges of the tilting grate.

[0025] A lightweight and reliable design is achieved if the actuating element extends substantially parallel to, and in particular at a distance from, the tilting axis of the tilting grate. For example, an actuating rod, preferably with a circular cross-section, can be provided as the actuating element.

[0026] In order to reliably trigger the movement of the cleaning elements when tilting the tipping grate, it is advantageous if the actuating element protrudes beyond an edge of the grate surface on at least one side, in particular in the direction of the tilting axis of the tipping grate.

[0027] In order to achieve thorough cleaning of the grate surface, it is advantageous if the tilting grate is tilted by more than 90°, for example by substantially 110°, when tilting from the firing position to the cleaning position.

[0028] A rotating shaft connected to a motor serves as the tilting axis of the tilting grate. The motor rotates the rotating shaft so that the tilting grate tilts from the firing position to the cleaning position (and vice versa).

[0029] In a preferred embodiment, the tilting axis of the tilting grate is arranged substantially centrally with respect to the grate surface.

[0030] As is known in the art, the boiler can have a combustion chamber above the tilting grate, which is preferably surrounded by a fireclay lining. The combustion chamber is preferably adjoined by a flame chamber, which is surrounded by a heat exchanger for heating a medium, in particular water. The heat exchanger can further have a flue gas duct, preferably with two flues, in particular each with several tubes.

[0031] The invention is further explained below using a preferred embodiment. Fig. 1 shows a boiler according to the invention along section II in Fig. 2 , showing a tilting grate in a horizontal firing position. Fig. 2 shows a top view of the boiler of the Fig. 1 . Fig. 3 shows a diagrammatic view of the boiler with a section along the line II in Fig. 2 . Fig. 4 a boiler according to the invention with a tilting grate, which is shown in the horizontal firing position. Fig. 5 shows the boiler according to Fig. 1 , wherein the tilting grate is shown in a tilted cleaning position, in which cleaning plates pivotably mounted on the tilting grate are pressed out of primary air slots. Fig. 6 shows a top view of the tilting grate in the firing position. Fig. 7 shows a side view of the boiler's tilting grate according to Fig. 1 . Fig. 8 shows another side view of the tilting grate in the firing position. Fig. 9 shows a diagrammatic view of the tilting grate in the firing position. Fig. 10 shows a side view of the tipping grate in the cleaning position with extended cleaning elements. Fig. 11 shows a diagrammatic view of the tipping grate in the cleaning position.

[0032] Fig. 1 shows a boiler, which will be referred to as "boiler 1" below. The boiler 1 has a combustion unit 2 for burning a solid fuel, for example, wood pellets. The combustion unit 2 has a tilting grate 3 (see in detail Fig. 4 bis 11 ) with a grate surface 4, which is fed with solid fuel via a fuel feed 5, here with a screw conveyor. In the design shown, the tilting grate 3 is free of thermal insulation below the grate surface. 4.Above the tilting grate 4, a combustion chamber 6 is formed, which is surrounded by a fireclay lining 6A. A combustion chamber 8 is connected to the top of the combustion chamber 6 via an attachment 7. This combustion chamber 8 is surrounded by a heat exchanger 9 for heating a medium, in particular water. The flue gases flow from the combustion chamber 8, assisted in particular by an induced draft fan, into the heat exchanger 9, which has a flue gas duct with two flues, each consisting of several tubes. The flue gases are finally extracted from the boiler 1 via an exhaust 10.

[0033] As from Fig. 4 and Fig. 5 As can be seen, the tilting grate 3 is between a firing position (cf. Fig. 4 ) and a cleaning position (see Fig. 5 ) can be tilted about a tilting axis 21 in order to transport combustion residues, such as ash and slag, from the grate surface 4 into an ash chamber 12 below. In the embodiment shown, the tilting grate 3 is tilted by more than 90° when transferred from the firing position to the cleaning position. In the embodiment shown, the tilting axis 21 of the tilting grate 3 runs essentially centrally between two narrow sides of the grate surface 4. In the embodiment shown, the tilting axis 21 is formed by a rotating shaft which is coupled to a motor (not shown). The cleaned residues are disposed of from the ash chamber 12 via a conveyor 13, here a screw conveyor, into an ash box 14 which is emptied manually.

[0034] As shown in detail Fig. 6 bis 11 As can be seen, several, for example four, cleaning elements 15 are movably arranged on the tilting grate 3, with which a corresponding number of primary air openings 16 running along the grate surface 4 are cleaned. In the embodiment shown, the cleaning elements 15 on the tilting grate 3 are pushed out of the primary air openings 16 by tilting the tilting grate 3 into the cleaning position in order to free the primary air openings 16 of deposits and thus ensure the primary air supply. The cleaning elements 15 therefore penetrate the primary air openings 16 on the grate surface 4.

[0035] In the illustrated embodiment, the cleaning elements 15 are pivotably mounted about a pivot axis 15A on a lateral edge region of the tilting grate 3. This allows the cleaning elements 15 to be pivoted from a position lowered below the grate surface 4 to a position projecting above the grate surface 4. The primary air openings 16 are designed as parallel primary air slots spaced apart from one another, which divide the grate surface 4 into individual grate surface sections.

[0036] Cleaning plates, here cleaning sheets, are provided as cleaning elements 15. These are arranged upright (i.e., running perpendicular to the grate surface 4) on the tilting grate 3. The primary air slots extend over more than half the length of the grate surface 4, in particular over more than three-quarters of the length of the grate surface 4. The cleaning plates extend essentially over the entire length of the primary air slots. The cleaning plates do not completely fill the primary air slots, but leave narrow air passages open along the length and at the front ends.

[0037] In the embodiment shown, the tilting of the tipping grate 3 simultaneously causes the pivoting of the cleaning elements 15. For this purpose, the tipping grate 3 has an actuating element 17 which is movably mounted relative to the grate surface 4 and which, in the embodiment shown, is formed by an actuating rod. The actuating rod extends parallel to the tilting axis 21 of the tipping grate 3 and passes through holding openings of the cleaning elements 15. In the embodiment shown, the actuating rod has individual spacer rings 17A between the cleaning elements 15. When the tipping grate 3 is tilted into the cleaning position, ends of the actuating element 17 which protrude beyond the long sides of the grate surface 4 are pushed against a first stationary stop 18 (cf. Fig. 4 ) of the firing unit 2, so that the cleaning elements 15 are pivoted - unless they have already protruded from the grate surface due to gravity. The firing unit 2 also has a second stationary stop 19 (see Fig. 5 ), against which the actuating element 17 is moved when the tilting grate 3 is tilted into the firing position in order to press the cleaning elements 15 under the grate surface 4.

[0038] As from Fig. 4 and Fig. 5 As can be seen, the first stationary stop 18 and the second stationary stop 19 are formed on a stationary stop plate 20, on which the tilting axis 21 of the tilting grate 3 is mounted. In the embodiment shown, two stop plates 20 are provided on opposite sides of the tilting grate 3, with the tilting axis 21 in the form of the rotating shaft being mounted in round holes in the stop plates 20. One end of the rotating shaft can be connected to the motor in a force-fitting manner, for example via a hexagonal part.

[0039] As shown in detail Fig. 5 As can be seen, the tilting grate 3 has a guide 22, here a curved slotted guide, for the actuating element 17. The guide 22 limits the movement of the actuating element 17 relative to the grate surface 4 to a defined first and second end position when the tilting grate 3 is tilted.

[0040] The following method for cleaning the tilting grate 3 can be carried out with the boiler 1: Tilting the tilting grate 3 from the firing position into the cleaning position, wherein cleaning elements 15 mounted on the tilting grate 3 in a movable, in particular pivotable, manner are guided out of the primary air openings 16 by the tilting of the tilting grate 3.

Claims

1. Boiler (1) for a solid fuel, for example pellets, comprising a firing unit (2) with a tilting grate which can be tilted between a firing position and a cleaning position (3), several cleaning elements (15), and a motor, which tilting grate (3) comprises a grate area (4) and primary air openings (16), wherein the cleaning elements (15) are movably mounted on the tilting grate (3) and are guided through the primary air openings (16) when the tilting grate (3) is tilted into the cleaning position, wherein a rotary shaft is provided as the tilting axis (21) of the tilting grate (3), which is connected to the motor, characterised in that the cleaning elements (15) are arranged to follow a tilting movement of the tilting grate (3).

2. Boiler (1) according to claim 1, characterised in that the cleaning elements (15) are mounted on the tilting grate (3) so as to be pivotable about a pivot axis (15A).

3. Boiler (1) according to claim 2, characterised in that the pivot axis (15A) runs along a lateral edge region of the tilting grate (3).

4. Boiler (1) according to one of the claims 1 to 3, characterised in that the primary air openings (16) are designed as primary air slots and the cleaning elements (15) are designed as cleaning plates, in particular cleaning sheets, the cleaning plates preferably being arranged upright on the tilting grate.

5. Boiler (1) according to claim 4, characterised in that the primary air slots extend over more than half the length of the grate area (4), in particular over more than three quarters of the length of the grate area, the cleaning plates preferably extending essentially over the entire length of the primary air slots.

6. Boiler (1) according to one of the claims 1 to 5, characterised in that the tilting grate (3) has an actuating element (17), in particular an actuating rod, which is moved against a first stationary stop (18) of the firing unit (2) when the tilting grate (3) is tilted into the cleaning position.

7. Boiler (1) according to one of claims 1 to 6, characterised in that the firing unit (2) comprises a second stationary stop (19) against which the actuating element (17) is moved when the tilting grate (3) is tilted into the firing position.

8. Boiler (1) according to claim 7, characterised in that the first (18) and / or the second stationary stop (19) are formed on a stop plate (20), on which preferably the tilting axis (21) of the tilting grate (3) is also mounted.

9. Boiler (1) according to one of claims 6 to 8, characterised in that the tilting grate (3) comprises a guide (22) for the actuating element (17), wherein the guide (22) limits the movement of the actuating element (17) relative to the grate area (4).

10. Boiler (1) according to claim 9, characterised in that the guide (22) comprises at least one slotted hole guide along which the actuating element (17) is guided.

11. Boiler (1) according to one of claims 6 to 10, characterised in that the actuating element (17) extends essentially parallel to the tilting axis (21) of the tilting grate (3).

12. Boiler (1) according to one of claims 6 to 11, characterised in that the actuating element (17) projects beyond an edge of the grate area (4) at least on one side, in particular in the direction of the tilting axis (21) of the tilting grate (3).

13. Boiler (1) according to one of claims 1 to 12, characterised in that the tilting grate (3) is tilted by more than 90° when tilting from the firing position to the cleaning position.

14. Boiler (1) according to one of claims 1 to 13, characterised in that the tilting axis (21) of the tilting grate (3) is arranged essentially centrally with respect to the grate area (4).

15. Method for cleaning a tilting grate (3) of a boiler (1) for a solid fuel, for example pellets, with the step: Tilting of the tilting grate (3) from a firing position into a cleaning position, wherein a rotary shaft is provided as tilting axis (21) of the tilting grate (3), which is connected to a motor, wherein cleaning elements (15) movably mounted on the tilting grate (3) are guided out of the primary air openings (16) by the tilting of the tilting grate (3), wherein the cleaning elements (15) follow a tilting movement of the tilting grate (3).

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