EP3985307A1 - Boiler - Google Patents

Abstract

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

Description

The invention relates to a boiler for a solid fuel, for example pellets, comprising:
a firing unit with a tilting grate which can be tilted between a firing position and a cleaning position and which has a grate surface and primary air openings.

The invention also relates to a method for cleaning a tilting grate of a boiler for a solid fuel, for example pellets.

In known boilers for solid fuels, a tipping grate with grate openings can be provided. Ash and slag can be removed from the grate surface by tilting the tipping grate. In addition, melted ash can cake on the grate openings during operation, which can cause malfunctions.

In the prior art, it is now known on the one hand to arrange stationary matrices under the tipping grate, against which the tipping grate can be pivoted in order to clean the grate openings. The disadvantage, however, is that cleaning the matrices can be difficult. In addition, the matrices can be exposed to different temperatures than the grate above. This can cause the dies to bend and no longer fit the primary air vents of the tipping grate, making cleaning impossible. Another disadvantage is that the stationary matrices take up a lot of space in the ash pan under the tipping grate.

the AT 503 043 B1 suggests another way of forced cleaning of the grate. In this prior art, the grate is tilted downwards about a pivot axis on the lateral edge of the tipping grate. The tilting movement is limited by a stop, which is set in such a way that the top grate parts that can be moved in the lower position are displaced. This cleans the air gaps formed between the movable upper grid parts and fixed upper grid parts. However, a design with movable and fixed upper grate parts is disadvantageous because the grate parts can warp due to the high thermal loads caused by the bed of embers. This allows cleaning be hindered. In one embodiment of this prior art, a movable grate part is also provided in the form of a round rod, which is guided through an air opening in the center of the tipping grate when tilted. Thus, in this prior art, when the tipping grate is tilted, grate parts, ie parts of the tipping grate forming the grate surface, are moved towards one another and a round rod is pushed through the central grate opening. However, this structure is very complicated and also takes up a lot of space. Due to the overall height, deformations can also occur due to the temperature profile. Thermal insulation under the ash barrier increases this problem.

In contrast, the object of the invention is to alleviate or eliminate at least individual disadvantages of the prior art. The invention aims in particular to equip a boiler with a structurally simple and space-saving tipping grate with which the primary air openings can be cleaned permanently and particularly reliably.

This object is solved by a boiler having the features of claim 1 and a method having the steps of claim 15. Preferred embodiments are given in the dependent claims.

According to the invention, several 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.

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 tipping grate from a firing position into a cleaning position, cleaning elements movably mounted on the tipping grate being guided out of the primary air openings by tilting the tipping grate.

By tilting the tipping grate, the cleaning elements are moved from a first end position, corresponding to the firing position of the tipping grate, to a second end position, corresponding to the Cleaning position of the tipping grate, moved. In the first end position, the upper edges of the cleaning elements are preferably essentially at the level of the grate surface or at most so far below the grate surface that the cleaning elements cannot laterally exit from the passage openings. As a result, jamming of the cleaning elements due to the thermal load during firing operation can be limited and the function of the cleaning elements can be ensured. Thus, in the firing position, the cleaning elements do not protrude beyond the preferably flat grate surface, which is preferably arranged essentially horizontally in the firing position. A uniform grate surface (ie 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 top of the grate plate, ie with the grate surface, or only less than the wall thickness of the grate plate underneath. When the tilting grate is in the cleaning position, the cleaning elements project upwards over the grate surface. The relative movement between the cleaning elements and the primary air openings causes the primary air openings to be cleaned of deposits. By arranging several cleaning elements, the primary air openings can be cleaned extensively and thoroughly from deposits such as ash or slag. Because the cleaning elements are mounted on the tipping grate, forced cleaning of the primary air openings is ensured when the tipping grate is tilted into the cleaning position. In this way, the primary air supply for operation can be reliably guaranteed. Tilting the tipping grate also means that the grate surface is cleaned of loose residues such as ash and slag. Since the cleaning elements are mounted on the tipping grate and participate in the tipping movement of the tipping grate, no additional space for stationary matrices in the ash space below the tipping grate is advantageously required. Thus, on the one hand, a larger volume of ash can be accommodated in the ash chamber. Since the cleaning elements are mounted on the tipping grate itself, the cleaning elements are essentially at the same temperature level as the Grate surface with the primary air openings. As a result, deformations of the cleaning elements due to temperature differences can be avoided and the passage of the cleaning elements through the primary air openings with a precise fit can thus be ensured. Functional losses due to thermally induced deformations can therefore advantageously be largely avoided. Due to the large number of cleaning elements, a number of primary air openings can be reliably cleaned.

All references to location and direction, such as "up", "down", "up", "down", "vertical", "horizontal", etc., in this disclosure relate to the operating position of the boiler on a flat, horizontal plane Floor space.

In a preferred embodiment, the tipping 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 tipping grate, as a result of which the grate surface on the upper side of the tipping grate is divided into individual sections.

With regard to a compact design, it is advantageous if the cleaning elements are mounted on the tipping grate so that they can pivot about a pivot axis. With this design, the tilting movement of the tilting grate is converted into a swiveling movement of the cleaning elements. By pivoting the cleaning elements, the cleaning elements emerge from the primary air openings in order to clean the tipping 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 may be formed on an extension extending downward from the grate surface. The maximum pivoting angle of the cleaning elements between the first and the second end position relative to the grate surface is preferably at least 5 degrees, preferably at least 9 degrees, in particular essentially 10 degrees.

The pivoting axis of the cleaning elements runs in order to enable a large-area and thorough cleaning of the tipping grate in a preferred embodiment on a lateral edge area of the tipping grate.

In a preferred embodiment, the primary air openings are designed as primary air slots and the cleaning elements as cleaning plates, in particular cleaning plates, with the cleaning plates preferably being arranged on edge (i.e. essentially perpendicular to the grate surface) on the tilting grate. The cleaning plates are preferably elongate, with the elongate cleaning plates preferably being arranged lying down (i.e. along the primary air slots). This ensures a low overall height of the tipping grate with the cleaning elements. Advantageously, the cleaning elements are essentially at the same temperature level as the tipping grate during firing operation. The primary air slots enable an effective air supply into the combustion chamber, while the cleaning plates ensure that the grate surface is cleaned over a large area.

In order 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 three quarters of the length of the grate surface, with the cleaning plates preferably extending essentially over the entire length of the primary air slots extend. The cleaning plates are preferably arranged with a lateral and/or frontal play in the primary air slots in order to allow the passage of the primary air.

In order to guide the cleaning elements out of the primary air openings by tilting the tilting grate, it is favorable if the tilting grate has an actuating element, in particular an actuating rod, which is movably mounted relative to the grate surface and which moves against a first stationary stop of the firing unit when the tilting grate is tilted into the cleaning position will. Thus, when the tilting grate is moved into the cleaning position, the actuating element is pressed against the first stationary stop (ie not tilting with the tilting grate) in such a way that the cleaning elements are pushed over the grate surface. Advantageously, no own drive required for the movement of the cleaning elements. Tilting the tilting grate against the first stop also causes the cleaning elements to be pushed out of the grate surface. For this purpose, the actuating element can be connected to the individual cleaning elements, in particular via holding 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 which keep the cleaning elements at a distance. Correspondingly, the pivot axis of the cleaning elements can have further spacer rings, which also keep the cleaning elements at a distance.

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 emerge from the primary air openings of the tipping grate protrude. Thus, in this embodiment, the cleaning elements can in particular already be arranged in the second end position before a first stationary stop is reached. This can be achieved by a suitable choice of the center of gravity of the cleaning elements relative to the center of gravity of the tipping grate and a corresponding arrangement of the tipping axis of the tipping grate. In this embodiment too, however, 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.
In order to reliably bring the cleaning elements back under or on the level of the grate surface when transferring the tipping grate, it is advantageous if the firing unit has a second stationary stop against which the actuating element is moved when the tipping grate is tilted into the firing position. When tilting the tipping grate into the firing position, the actuating element is on the second stationary (i.e. not with the Tilting grate mitkippenden) stop pushed, whereby the cleaning elements - are pushed back into the first end position - in addition to the effect of gravity. With the second stationary stop, the complete return of the cleaning elements can be ensured independently of gravity.

A simple construction is achieved if the first and/or the second stationary stop are formed on a stop plate, on which the tilting axis of the tilting grate is preferably mounted. An embodiment in which two stop plates, each with a first and a second stationary stop, are provided on opposite sides, in particular longitudinal sides, of the tipping grate is even more stable, with two opposite ends of the actuating element hitting the first stationary stops and be pushed onto the second stationary stops when the firing position is reached.

In order to ensure defined end positions of the movement of the cleaning elements, in a preferred embodiment the tilting grate has a guide for the actuating element, with the guide limiting the movement of the actuating element relative to the grate surface.

With regard to a structurally simple, reliable construction, the guide can have at least one slot guide, along which the actuating element is guided. The ends of the slot guide define the first and the second end position of the movement of the actuating element. Depending on the design, two slot guides can be provided, in particular on opposite edges of the tipping grate.

A light and reliable design is achieved if the actuating element extends essentially parallel and, in particular, at a distance from the tilting axis of the tilting grate. An actuating rod, for example, preferably with a circular cross section, can be provided as the actuating element.

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

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 essentially 110°, when tilting from the furnace into the cleaning position.

In a preferred embodiment, a rotary shaft, which is connected to a motor, is provided as the tilting axis of the tilting grate. With the help of the motor, the rotary shaft can be turned in such a way that the tilting grate is tilted from the firing to the cleaning position (and vice versa).

In a preferred embodiment, the tilting axis of the tilting grate is arranged essentially centrally with respect to the grate surface.

As is known in the prior art, the boiler can have a combustion chamber above the tilting grate, which is preferably surrounded by a fireclay lining. A flame space, which is surrounded by a heat exchanger for heating a medium, in particular water, preferably adjoins the combustion chamber. The heat exchanger can also have a flue gas duct, preferably with two passes, in particular each with a plurality of tubes.

• Fig. 1 zeigt einen erfindungsgemäßen Kessel entlang des Schnitts I-I in Fig. 2, wobei ein Kipprost in einer horizontalen Feuerungsstellung dargestellt ist.
• Fig. 2 zeigt eine Draufsicht auf den Kessel der Fig. 1.
• Fig. 3 zeigt schaubildliche Ansicht des Kessels mit einem Schnitt entlang der Linie I-I in Fig. 2.
• Fig. 4 einen erfindungsgemäßen Kessel mit einem Kipprost, welcher in der horizontalen Feuerungsstellung dargestellt ist.
• Fig. 5 zeigt den Kessel gemäß Fig. 1, wobei der Kipprost in einer gekippten Reinigungsstellung dargestellt ist, in der am Kipprost verschwenkbar gelagerte Reinigungsbleche aus Primärluftschlitzen herausgedrückt sind.
• Fig. 6 zeigt eine Draufsicht auf den Kipprost in der Feuerungsstellung.
• Fig. 7 zeigt eine Seitenansicht des Kipprosts des Kessels gemäß Fig. 1.
• Fig. 8 zeigt eine weitere Seitenansicht des Kipprosts in der Feuerungsstellung.
• Fig. 9 zeigt eine schaubildliche Ansicht des Kipprosts in der Feuerungsstellung.
• Fig. 10 zeigt eine Seitenansicht des Kipprosts in der Reinigungsstellung mit ausgefahrenen Reinigungselementen.
• Fig. 11 zeigt eine schaubildliche Ansicht des Kipprosts in der Reinigungsstellung.

The invention is explained in more detail below using a preferred exemplary embodiment.

• 1 shows a boiler according to the invention along the section II in 2 , wherein a tipping grate is shown in a horizontal firing position.
• 2 shows a plan view of the boiler 1 .
• 3 shows a perspective view of the boiler with a Section along line II in 2 .
• 4 a boiler according to the invention with a tipping grate, which is shown in the horizontal firing position.
• figure 5 shows the boiler according to 1 , wherein the tipping grate is shown in a tilted cleaning position, in which the cleaning plates pivotably mounted on the tipping grate are pressed out of primary air slots.
• 6 shows a plan view of the tipping grate in the firing position.
• 7 shows a side view of the tipping grate of the boiler according to 1 .
• 8 shows another side view of the tipping grate in the firing position.
• 9 shows a perspective view of the tipping grate in the firing position.
• 10 shows a side view of the tilting grate in the cleaning position with the cleaning elements extended.
• 11 shows a perspective view of the tipping grate in the cleaning position.

1 shows a boiler, which will be referred to as "boiler 1" for short below. The boiler 1 has a firing unit 2 for firing a solid fuel, such as wood pellets. The firing unit 2 has a tilting grate 3 (cf. in detail Figures 4 to 11 ) with a grate surface 4, which is charged with solid fuel via a fuel supply 5, here with a screw. In the embodiment shown, the tipping grate 3 is free of thermal insulation below the grate surface 4. Above the tipping grate 4, a combustion chamber 6 is formed, which is surrounded by a fireclay lining 6A. A combustion chamber 8 connects to the combustion chamber 6 on the upper side via an attachment 7 and is connected by a heat exchanger 9 for heating a medium, in particular water, is surrounded. The flue gases flow from the combustion chamber 8, supported 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 pipes. Finally, the flue gases are withdrawn from the boiler 1 via a flue 10 .

How out 4 and figure 5 visible, the tipping grate 3 is between a firing position (cf. 4 ) and a cleaning position (cf. figure 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 underneath. In the embodiment shown, the tilting grate 3 is tilted by more than 90° when transferring 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 rotary 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.

How to look in detail Figures 6 to 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 tipping grate 3 are pushed out of the primary air openings 16 by tilting the tipping grate 3 into the cleaning position in order to clear 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.

In the embodiment shown, the cleaning elements 15 are mounted on a lateral edge area of the tilting grate 3 such that they can pivot about a pivot axis 15A. As a result, the cleaning elements 15 can be lowered from below the grate surface 4 Position are pivoted in a projecting position on the grate surface 4. The primary air openings 16 are designed as primary air slits which run parallel to one another at intervals and which divide the grate surface 4 into individual grate surface sections.

Cleaning plates, here cleaning plates, are provided as cleaning elements 15, which are arranged on edge (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 on the long side and on the front sides.

In the embodiment shown, the tilting of the tilting grate 3 also causes the cleaning elements 15 to pivot. The actuating rod extends parallel to the tilting axis 21 of the tilting grate 3 and passes through holding openings in the cleaning elements 15 . In the embodiment shown, the actuating rod has individual spacer rings 17A between the cleaning elements 15. When the tilting grate 3 is tilted into the cleaning position, ends of the actuating element 17 protruding over the longitudinal sides of the grate surface 4 are pressed against a first stationary stop 18 (cf. 4 ) of the firing unit 2 is pressed, so that the cleaning elements 15—if they have not already emerged from the grate surface due to gravity—are pivoted. The firing unit 2 also has a second stationary stop 19 (cf. figure 5 ) against which the actuating element 17 is moved into the firing position when the tilting grate 3 is tilted in order to press the cleaning elements 15 under the grate surface 4 .

How out 4 and figure 5 seen, are 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 being mounted in round holes in the stop plates 20 in the form of the rotary shaft. One end of the rotary shaft can be non-positively connected to the motor, for example via a hexagonal part.

How to look in detail figure 5 As can be seen, the tipping grate 3 has a guide 22 , here a curved slot guide, for the actuating element 17 . The guide 22 limits the movement of the actuating element 17 relative to the grate surface 4 when the tilting grate 3 is tilted to a defined first and second end position.

The following procedure for cleaning the tipping grate 3 can be carried out with the boiler 1:
Tilting of the tilting grate 3 from the firing position into the cleaning position, cleaning elements 15 mounted on the tilting grate 3 that are movable, in particular pivotable, being guided out of the primary air openings 16 by the tilting of the tilting grate 3 .

Claims (15)

Boiler (1) for a solid fuel, for example pellets, comprising: a firing unit (2) with a tilting grate (3) which can be tilted between a firing position and a cleaning position and which has a grate surface (4) and primary air openings (16), characterized in that several cleaning elements (15) are movably mounted on the tipping grate (3) and are guided through the primary air openings (16) into the cleaning position when the tipping grate (3) is tilted. Boiler (1) according to Claim 1, characterized in that the cleaning elements (15) are mounted on the tilting grate (3) such that they can be pivoted about a pivot axis (15A). Boiler (1) according to Claim 2, characterized in that the pivot axis (15A) runs on a lateral edge region of the tilting grate (3). Boiler (1) according to one of Claims 1 to 3, characterized 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 plates, the cleaning plates preferably being arranged upright on the tilting grate. Boiler (1) according to Claim 4, characterized in that the primary air slots extend over more than half the length of the grate surface (4), in particular over three quarters of the length of the grate surface, with the cleaning plates preferably extending essentially over the entire Extend length of the primary air slots. Boiler (1) according to any one of claims 1 to 5, characterized in that the tilting grate (3) relative to the grate surface (4) movably mounted actuating element (17), in particular a Operating 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. Boiler (1) according to one of Claims 1 to 6, characterized in that the firing unit (2) has a second stationary stop (19) against which the actuating element (17) is moved into the firing position when the tilting grate (3) is tilted. Boiler (1) according to Claim 7, characterized in that the first (18) and/or the second stationary stop (19) are formed on a stop plate (20), on which the tilting axis (21) of the tilting grate (3) is preferably also is stored. Boiler (1) according to one of Claims 6 to 8, characterized in that the tilting grate (3) has a guide (22) for the actuating element (17), the guide (22) controlling the movement of the actuating element (17) relative to the grate surface (4) limited. Boiler (1) according to Claim 9, characterized in that the guide (22) has at least one slot guide along which the actuating element (17) is guided. Boiler (1) according to one of Claims 6 to 10, characterized in that the actuating element (17) extends essentially parallel to the tilting axis (21) of the tilting grate (3). Boiler (1) according to one of Claims 6 to 11, characterized in that the actuating element (17) projects beyond an edge of the grate surface (4) at least on one side, in particular in the direction of the tilting axis (21) of the tilting grate (3). Boiler (1) according to one of Claims 1 to 12, characterized in that the tilting grate (3) is tilted by more than 90° when tilting from the firing position into the cleaning position. Boiler (1) according to one of Claims 1 to 13, characterized in that that the tilting axis (21) of the tilting grate (3) is arranged essentially centrally with respect to the grate surface (4). Method for cleaning a tilting grate (3) of a boiler (1) for a solid fuel, for example pellets, with the step:
Tilting the tilting grate (3) from a firing position to a cleaning position, cleaning elements (15) mounted movably on the tilting grate (3) being guided out of the primary air openings (16) by tilting the tilting grate (3).

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