BIOMASS BOILER AND METHOD FOR OPERATING A BIOMASS BOILER

Description

[0001] The invention relates to a biomass boiler for a solid biomass fuel, in particular pellets and / or wood chips, comprising: a boiler casing, a combustion chamber within the boiler casing, a heat exchanger with a rising flue and / or a falling flue, a first ash chamber for collecting ash from the combustion chamber, which is preferably arranged below the combustion chamber, a second ash chamber for collecting fly ash, which is separated from the first ash chamber by a partition wall and is preferably arranged below the rising flue and / or the falling flue, a discharge device for discharging ash, which is configured to convey ash from the first or the second ash chamber through an ash passage opening in the partition wall into the second or first ash chamber and subsequently into an ash collection area, a closing element for closing the ash passage opening.

[0002] Furthermore, the invention relates to a method for operating a biomass boiler for a solid biomass fuel, in particular pellets and / or wood chips.

[0003] Biomass boilers are used for heat generation. In typical biomass boilers, the solid biomass fuel is usually conveyed from a storage room into the combustion chamber by means of a conveying system and burned there on a grate with the supply of combustion air. During combustion, ash is produced, some of which remains on the grate and some of which is deposited as fly ash elsewhere within the biomass boiler. The ash remaining on the grate can, for example, be conveyed into a first ash chamber through slot-like openings in the grate or by a tilting motion of the grate. The fly ash can be collected in a second ash chamber, separate from the first, which is preferably located within the biomass boiler at the point where the fly ash settles.For example, the second ash chamber can be located below a downdraft of a heat exchanger.

[0004] It is known from the prior art to convey the collected ash from the first and second ash chambers into a collection area using a common discharge device, from where it can be removed and subsequently disposed of. Since different pressure conditions typically prevail in the various areas of a biomass boiler for the purpose of managing flue gases and for safety reasons, precautions must be taken to ensure that these pressure conditions are not affected or can be maintained when the ash is discharged from the first and second ash chambers. Leaks would lead to an internal ingress of false air, which would negatively affect combustion quality.

[0005] From EP 2 098 783 A1, a boiler is known in which ash, collected in an ash chamber below a grate, and fly ash, collected in a deflection chamber, are discharged into a collection container by two screw conveyors arranged on a common screw shaft. A partition wall is provided between the ash chamber and the deflection chamber, which has a tubular passage containing a baffle. This creates a storage space for the fly ash, in which the fly ash accumulates and compacts, forming a sealing ash plug that prevents flow through the passage. A check valve also prevents flow when the storage space is empty of ash. However, the check valve can be opened by the overflowing fly ash. Thus, during boiler operation, the ash plug seals the tubular passage.A disadvantage of the EP 2 098 783 A1 boiler is that the ash plug's seal is not always guaranteed due to the granular nature of the ash. For example, during operation, ash chunks can partially empty the storage chamber, leading to an internal air leak. Furthermore, the non-return valve may become clogged with dirt and no longer close completely, which can also result in an air leak if an ash plug is not present.

[0006] From AT 518 671 B1, a heating device with a conveying system is known, comprising a rotary valve and two screw shafts. The conveying system can be used to remove ash from a combustion chamber and a heat exchanger, where different pressures prevail in the combustion chamber and the heat exchanger. However, a disadvantage of the ash conveying system is its very complex design and large footprint.

[0007] Other heating devices are known from EP 3 789 672 A1 and EP 2 375 154 A2.

[0008] In light of these considerations, the object of the present invention is to at least partially alleviate the disadvantages of the prior art. Preferably, the object of the present invention is to provide a biomass boiler of the type mentioned above, with which ash can be easily and compactly discharged from two areas of the biomass boiler with different pressure conditions without affecting the pressure conditions during operation of the biomass boiler.

[0009] This problem is solved by a biomass boiler according to claim 1 and by a method for operating a biomass boiler for a solid biomass fuel according to claim 13.

[0010] According to the invention, the biomass boiler of the type described above is provided in that the closing element is connected to a closing drive, which allows the closing element to be moved between a closed position, in which the ash passage opening is closed, and an open position, in which the ash passage opening is released and ash can be conveyed through the ash passage opening by the discharge device. The closing drive allows the closing element to be moved into the closed position, thereby closing the ash passage opening. An ash plug, as in EP 2 098 783 A1, is not required for this purpose. Advantageously, the closing element requires little space and has a simple design. The closing element can be actively moved between the closed and open positions by means of the closing drive, in particular by converting electrical energy into mechanical energy.To actuate the closing element, the closing actuator can apply a force, thereby moving it from the closed position to the open position and vice versa. The closing actuator can be connected to a control and / or regulating device of the biomass boiler, which controls the closing actuator. With the control and / or regulating device, the closing element can be moved to the closed or open position at predetermined times and / or in specific operating states of the biomass boiler. An active drive, preferably an electric drive, in particular a linear drive, is provided as the closing actuator. The closing actuator can be formed by an existing drive of the biomass boiler, for example, a grate drive for pivoting a combustion grate in the combustion chamber or a drive for the discharge device.In the closed position, the closing element completely covers and seals the ash passage opening. In the open position, the ash passage opening is uncovered, allowing ash to be conveyed through it. Preferably, the biomass boiler is equipped with a blower, in particular an induced draft blower, which, during operation, creates a pressure gradient along the flue gas path, thus drawing the flue gases along the flue gas path. In the closed position, the closing element covers the ash passage opening, preferably in such a way that pressure differences intended during operation of the biomass boiler, such as those resulting from the pressure gradient generated by the blower, can be maintained between the first and second ash chambers. Thus, preferably no significant [pressure] occurs through the ash passage opening. d.h. The intended operation of the biomass boiler is not impaired by the flow interference. When the closing element is in the closed position, flue gases and combustion air do not pass through the ash passage opening to any significant extent. The closing element has a larger diameter than the ash passage opening and can completely cover it in the closed position. A flat piece, particularly a plate, can be used as the closing element. In the open position, the ash passage opening is uncovered, allowing ash to be conveyed through it by the discharge device. The first and second ash chambers are separated by a partition wall, which is preferably made of metal, particularly sheet metal. The partition wall can be a single piece or consist of several parts.The first and second ash chambers can each be bounded by the partition wall and a wall of the boiler casing, which together form a container for the first and second ash chambers, respectively. Preferably, the first ash chamber is located below a grate in the combustion chamber. This allows ash that falls, for example, through openings in the grate (depending on the design), to be collected in the first ash chamber. Additionally or alternatively, ash deposited by the grate during a tilting motion can fall into the first ash chamber due to gravity. Preferably, the first ash chamber is open at the top. The second ash chamber is preferably located below a rising flue and / or a downward flue of a heat exchanger in the biomass boiler, so that fly ash can be collected after exiting the heat exchanger or before (re-)entering it.The second ash chamber is also preferably open at the top. The heat exchanger is, for example, a condensing heat exchanger. The rising flue and the downward flue are passages, in particular pipes, of the heat exchanger through which the flue gases produced by combustion pass and transfer thermal energy to a heat exchange medium, in particular water. During operation of the biomass boiler, the flue gases are directed upwards in the rising flue and downwards in the downward flue. The rising flue and the downward flue thus form part of the flue gas path. Preferably, the first and the second ash chambers are arranged at essentially the same height. Preferably, the first and the second ash chambers are arranged inside the biomass boiler, in particular inside the boiler casing. The discharge device can, for example, have at least one shaft with one or more auger threads.To discharge the ash into the ash collection area, the discharge device can convey the accumulated ash from the first ash chamber through the ash passage opening into the second ash chamber and from there transport the ash from both chambers to the ash collection area. Alternatively, the discharge device can convey the accumulated ash from the second ash chamber through the ash passage opening into the first ash chamber and from there transport the ash from both chambers to the ash collection area. The combustion chamber can be at least partially lined with stones, particularly firebricks. The combustion chamber can also be made of steel, particularly cast steel, and have no stone lining.

[0011] Location and direction specifications in this disclosure refer to the intended operating condition of a biomass boiler. "Downwards" in this context means, for example, parallel to the acceleration due to gravity.

[0012] It is particularly advantageous for space-saving design if the locking element has a plate. The plate is preferably flat. d.h. The plate is flat. It can be of any shape. For example, it can be rectangular, square, polygonal, round, oval, sector-shaped, or a combination thereof. It is particularly preferred if the closing element is formed entirely by a plate.

[0013] In one embodiment of the invention, the locking element may have a locking element opening which, in the open position, at least partially coincides with the ash passage opening in the partition and, in the closed position, is essentially completely covered by the partition. If the locking element comprises a plate or is formed by a plate, the locking element opening is preferably arranged in the plate. The shape of the locking element opening may, for example, substantially correspond to the shape of the ash passage opening. The size of the ash passage opening may substantially correspond to the size of the locking element opening or differ from it. In particular, the locking element opening may be larger than the ash passage opening.In the open position, the closing element opening and the ash passage opening are at least partially aligned, allowing ash to pass through both openings. Preferably, in the open position of the closing element, the closing element opening and the ash passage opening are aligned in such a way that the ash passage opening is completely unobstructed.

[0014] To prevent flow, it is advantageous if the closing element is pressed against the partition by at least one pressure element, in particular a spring element. Preferably, the pressure element presses the closing element against the partition in both the open and closed positions. Multiple pressure elements can also be provided to press the closing element against the partition.

[0015] In one embodiment of the invention, the biomass boiler has a grate that can be pivoted by a grate drive, and the closing drive is formed by the grate drive, so that the closing element can be moved between the open and closed positions by the grate drive. This eliminates the need for a separate drive for the closing element. The grate drive is preferably a linear drive. It is particularly preferred if the closing element is coupled to the grate drive in such a way that the closing element is moved into the open position when the grate is tilted by the grate drive to remove accumulated ash.

[0016] To protect the grate drive from high temperatures, it can be arranged in a separate area of ​​the biomass boiler, distinct from the combustion chamber. This area can be further separated from the first and / or second ash chamber by a partition wall. In one embodiment of the invention, the grate drive and the closing element are coupled via a linkage, and the linkage extends from the first or second ash chamber to the grate drive through a transition opening in the partition wall, preferably adjacent to the first and / or second ash chamber. The partition wall is preferably made of metal, in particular sheet metal. The linkage can, for example, comprise one or more shafts, one or more deflection levers, and / or one or more joints.In one embodiment of the invention, the grate drive is a linear drive, and the linkage includes a deflection lever that converts the linear movement of the grate drive into a rotational movement. To transmit the rotational movement, the linkage can have a rotary shaft connected to the deflection lever and guided through a passage in the partition wall. A conversion element can be attached to the rotary shaft, which converts the rotational movement of the shaft into a pivoting movement of the closing element. For this purpose, the conversion element can, for example, have an actuating bolt arranged between two pins attached to the closing element. Depending on the direction of rotation of the rotary shaft, the bolt presses against one of the two pins, thereby pivoting the closing element into the open or closed position.

[0017] In one embodiment of the invention, the discharge device has a shaft that passes through a shaft opening in the partition, and the closing element has a recess for the shaft. The shaft of the discharge device can be connected to a drive for the discharge device, in particular an electric drive. By passing the shaft through the partition, ash in the first and second ash chambers can be conveyed by a single common shaft. If a closing element opening is provided, it does not coincide with the recess for the shaft. In other words, the recess for the shaft is a separate recess from the closing element opening, not the closing element opening itself. The shaft opening is preferably also separate from the ash passage opening and therefore preferably does not coincide with it.The recess for the shaft can be elongated in particular to allow the closing element to be moved between the closed position and the open position, especially by pivoting.

[0018] To convey ash from the first or second ash chamber to the second or first ash chamber, respectively, and subsequently to the ash collection area, it is advantageous for the discharge device on the shaft to have a first auger for conveying ash in the first ash chamber and a second auger for conveying ash in the second ash chamber, the winding directions of the first and second augers preferably being the same. In this way, it is possible for ash to be transported through the ash passage opening between the ash chambers and then conveyed to the ash collection area. For example, the first auger can convey ash to the ash passage opening, where an accumulation of ash occurs, and the ash is then pushed by incoming ash through the ash passage opening into the second ash chamber, from where it is conveyed further to the ash collection area by the second auger.Conversely, it is also possible that the second screw feeder conveys ash to the ash passage opening, where ash accumulates and is pushed by incoming ash through the ash passage opening into the first ash chamber, from where it is conveyed further by the first screw feeder to the ash collection area. Preferably, the first and second screw feeders terminate essentially at the partition wall in order to convey the ash through the ash passage opening and from there, respectively.

[0019] A particularly space-saving design is achieved when the locking element can be moved between the open and closed positions by a rotary pivoting movement, preferably a rotary pivoting movement in a plane parallel to the partition. The rotary pivoting movement preferably takes place about an axis of rotation that is arranged essentially perpendicular to the partition. The axis of rotation can, for example, be formed by a pivot shaft or a pivot pin that is mounted in the partition. If, as described above, a pressure element is provided, this can, for example, be arranged around or on the pivot shaft or pivot pin and exert a pressure on the locking element parallel to the axis of rotation.During the pivoting movement to transfer the locking element between the open position and the closed position, the locking element is preferably pivoted by at least 10°, particularly preferably by at least 20°, particularly preferably by at least 30°, particularly preferably by at least 45°, for example substantially 50°.

[0020] A structurally simple design results if a rotational axis for the rotary pivoting movement of the closing element is oriented essentially parallel to the shaft of the discharge device.

[0021] To allow pivoting while the discharge element's shaft is present, it is advantageous if the recess of the closing element for the shaft is bent according to a bending radius that essentially corresponds to a distance between the axis of rotation and the shaft. In other words, the recess is bent along a circular segment around the axis of rotation of the closing element.

[0022] In one embodiment of the invention, the closing element in the closed position seals the ash passage opening in such a way that a pressure difference between the first and the second ash chamber, which is preferably between 0.001 bar (100 Pa) and 0.01 bar (1000 Pa), in particular between 0.0015 bar (150 Pa) and 0.003 bar (300 Pa), for example essentially 0.002 bar (200 Pa), is maintained during operation of the biomass boiler.

[0023] The problem stated above is also solved by a method for operating a biomass boiler for a solid biomass fuel, in particular pellets and / or wood chips, according to claim 13. The biomass boiler has the following features: a boiler housing, a combustion chamber within the boiler housing, a heat exchanger with a rising flue and / or a falling flue, a first ash chamber for collecting ash from the combustion chamber, which is preferably arranged below a grate of the combustion chamber, a second ash chamber for collecting fly ash, which is separated from the first ash chamber by a partition wall and is preferably arranged below the rising flue and / or the falling flue, a discharge device for discharging ash, which is configured to convey ash from the first or the second ash chamber through an ash passage opening in the partition wall into the second or first ash chamber and subsequently into an ash collection area, a closing element for closing the ash passage opening.

[0024] According to the invention, the method provides that the closing element is moved by means of a closing drive from a closed position, in which the ash passage opening is closed, to an open position, in which the ash passage opening is released, and that ash is discharged by the discharge device from the first or the second ash chamber through the ash passage opening into the second or first ash chamber and subsequently into the ash collection area. Preferably, the discharge takes place before and / or after a combustion process. d.h. The ash removal process takes place before and / or after the combustion of solid biomass fuel. During a combustion process, solid biomass fuel is burned. In particular, it can be provided that the ash is removed between two combustion processes. For example, preferably immediately after a combustion process, any ash present can be removed from the first and second ash chambers into the ash collection area as described, and the biomass boiler can then be switched off or placed in standby mode. Alternatively or additionally, for example, after the biomass boiler has been switched on (again), any ash present can preferably be removed from the first and second ash chambers into the ash collection area immediately before another combustion process.The features and advantages described above in connection with the biomass boiler are transferable to the method for operating a biomass boiler.

[0025] To remove as much or as large a portion of the ash from the biomass boiler as possible, it is advantageous for the closing mechanism to be a grate drive. When activated, this grate drive tilts the combustion grate and opens the closing element. In the tilted position, the ash on the grate falls downwards. It is particularly beneficial if the first ash chamber is located below the combustion grate to collect the falling ash. When the grate drive is activated, the grate tilts, causing the ash to fall downwards, preferably directly into the first ash chamber. From there, the discharge device conveys the ash either via the second ash chamber or, together with the ash from the second chamber, directly into the ash collection area.

[0026] The invention is explained in more detail below with reference to figures, to which it is not, however, limited.

[0027] They show: Fig. 1 a cross-section through a biomass boiler; Fig. 2 an enlarged view of a first and a second ash chamber; Fig. 3 a closing element in the first ash chamber, which is coupled to a grate drive in a closed position; Fig. 4 a closing element in the first ash chamber, which is coupled to a grate drive in an open position; Fig. 5 a cross-section of the biomass boiler with a combustion grate in a tilted position; and Fig. 6 a method for operating a biomass boiler.

[0028] Fig. 1 Figure 1 shows a biomass boiler 1 with a combustion chamber 2, within which a grate 3 is arranged for the support and combustion of a solid biomass fuel (not shown). The combustion chamber 2 is located within a boiler housing 51. The solid biomass fuel can be, for example, wood chips and / or pellets. For combustion, combustion air is supplied to the combustion chamber 2 via air inlet openings 4. The combustion air flows into the combustion chamber 2 both through the grate 3 as primary air and through the area above the grate 3 as secondary air.During the combustion of the solid biomass fuel, ash 5 is produced. Some of this ash remains on the grate 3, some falls through slot-like openings 6 in the grate 3 into a first ash chamber 7 below the grate 3, and some, as fly ash 5a, is carried along a flue gas path 8 with the flue gas 9 produced during combustion through the biomass boiler 1 and is finally collected in a second ash chamber 10. In the following, a distinction will only be made between ash 5 and fly ash 5a when necessary. Ash 5 that remains on the grate 3 and does not fall down through the slot-like openings 6 can be emptied into the first ash chamber 7 by a tilting motion of the grate, which will be explained in more detail below.During operation of the biomass boiler 1, the flue gas path 8 of the flue gas 9 initially leads from the combustion grate 3 upwards through a rising flue 11 of a heat exchanger 12 into a deflection chamber 13 above the heat exchanger 12. In the deflection chamber 13, the flue gas is deflected and then led downwards through a downward flue 14 of the heat exchanger 12 to the second ash chamber 10, in which the fly ash 5a is collected.

[0029] Finally, the flue gas 8 is routed to the outside via an exhaust pipe 15. In the illustrated embodiment, the second ash chamber 11 is located below the downdraft 14 at a point where, during operation of the biomass boiler 1, the flue gas 9 is deflected upwards towards the exhaust pipe 15 after exiting the downdraft 14. A large portion of the fly ash 5a is deposited at this point. A fan (not shown) can facilitate the exit of the flue gas 9 through the exhaust pipe 15. The first 7 and the second ash chamber 10 are separated from each other by a partition 16. In the illustration, the first 7 and the second ash chamber 10 are arranged at the same height. Both the first 7 and the second ash chamber 10 are open at the top.

[0030] To discharge collected ash from the first 7 and the second ash chamber 10 to an ash collection area 17, a discharge device 18 is provided. In the illustrated embodiment, this device is configured to discharge collected fly ash 5a from the second ash chamber 10 through an ash passage opening 19 (see Fig. 4 The discharge device 18 is designed to convey the fly ash 5 through the partition 16 into the first ash chamber 7 and from there, together with the ash 5, into the ash collection area 17. To convey the ash 5, the discharge device 18 has a shaft 20 and a first auger 21a in the first ash chamber 7 and a second auger 21b in the second ash chamber 10. Preferably, the two augers 21a, b have the same winding direction, so that the ash 5 can be conveyed from the second ash chamber 10 through the ash passage opening 19 into the first ash chamber 7 and further into the ash collection area 17. The augers 21a, b each terminate substantially at or just before the partition 16, so that the fly ash 5a can be pushed through the ash passage opening 19 and conveyed further after passing through it. To drive the shaft 20, the discharge device 18 has a drive (not shown), in particular an electric drive.The shaft 20 is guided through a shaft opening 50 in the partition wall 16 (see . Fig. 5 Due to the distance between the bottom 52 of the first 7 and second ash chambers 10 and the screw threads 21a, b, the first 7 and the second ash chambers 10 cannot be completely emptied. A small amount of ash always remains in the ash chambers 7 and 10.

[0031] During operation of the biomass boiler 1, different pressure conditions can prevail at different points within the boiler during a combustion process. To prevent these pressure conditions from being affected during operation, a pivotable closing element 22 is provided in the illustration, as shown in Fig. 2 shown. The locking element 22 can be switched between a closed position (see Fig. 2 und Fig. 3 ) and a disclosure (see Fig. 4 ) be transferable. In the open position, it is possible, as described above, to convey ash 5 from the second ash chamber 10 to the first ash chamber 7 through the ash passage opening 19. In the closed position, the ash passage opening 19 is completely covered by the closing element 22, preferably in such a way that the pressure conditions are not affected during operation of the biomass boiler. To increase the tightness of the closing element in the closed position, a pressure element 23 is preferably used (see Fig. 2 ), in particular a spring element 24 made of metal, is provided which exerts a contact force F on the closing element 22 and presses it against the partition 16. Advantageously, this seals the ash passage opening 19 in the closed position in such a way that essentially no flue gas 9 and no combustion air pass through the ash passage opening 19 and the pressure conditions within the biomass boiler 1 are not affected.

[0032] In the embodiment shown, as in Fig. 2 It is evident that the locking element 22 is a flat, d.h. uncurved, plate 25. The outer shape of plate 25 essentially corresponds to a sector of a circle, with the corners 26 being rounded. As particularly in Fig. 3 As can be seen, the closing element 22 has a closing element opening 27 and a recess 28 for the shaft 20 of the discharge device 18. The closing element 22 can be pivoted about a pivot axis 29 that runs parallel to the shaft 20. The pivot axis 29 can be formed, for example, by a pivot shaft or a pivot pin. The pressure element 23 can be arranged on the pivot axis 29. The pivoting of the closing element 22 thus occurs in a direction parallel to the partition wall 16. To enable the pivoting of the closing element 22, the recess 28 for the shaft 20 is elongated and bent according to a bending radius R1, which corresponds to the distance between the pivot axis 29 and the shaft 20. In the embodiment shown, the closing element opening 27 is also bent, namely according to a bending radius R2, which corresponds to the distance between the pivot axis 29 and the ash passage opening 19.

[0033] In the closed position (see Fig. 3 The closing element opening 27 is completely covered by the partition 16, or the ash passage opening 19 is completely covered by the closing element 22, so that no ash 5 and essentially no flue gas 9 and essentially no combustion air can pass through the ash passage opening 19. By pivoting about the axis of rotation 29, the closing element 22 can be moved from the closed position to the open position (see Fig. 4 ) are transferred. In the open position, the closing element opening 27 and the ash passage opening 19 are at least partially superimposed, so that ash 5 can be conveyed through the ash passage opening 19.

[0034] To enable the closing element 22 to be moved between the open and closed positions, the closing element 22 is connected to a closing drive 30. The closing drive 30 is an active and, in particular, regulated and / or controlled drive, especially an electric drive. In the embodiment shown, the closing drive 30 is formed by a grate drive 31. The grate drive 31 is designed to move the combustion grate 3 between a combustion position ( Fig. 3 ), in which solid fuel can be stored and burned on the fire grate, and a tilting position ( Fig. 4 ), in which the ash can be tipped from the grate 3. The closing element 22 is coupled to the grate drive 31. In the illustrated embodiment, the closing element 22 is coupled to the grate drive 31 such that when the grate 3 is moved into the tilting position by the grate drive 31, the closing element 22 is moved into the open position by the grate drive 31, and when the grate 3 is moved into the firing position by the grate drive 31, the grate 3 is moved into the closed position by the grate drive 31. The grate drive is preferably formed by an electric drive, in particular an electric linear drive 32. To protect the grate drive 31 from high temperatures, it is arranged in a section 34 separated from the combustion chamber 2 by a further partition 33. A grate shaft 36 is coupled to the grate drive 31 via a feedthrough 35.

[0035] In the illustrated embodiment, the closing element 22 is coupled to the grate drive 31 via a linkage 37. As in Fig. 3 As can be seen, the linkage 37 has a rotary shaft 38 which is guided through the further partition wall 33 via a transition opening 53 and is connected to the grate drive 31, in particular to a rotor 40 of the grate drive 31, via a deflection lever 39. The rotary shaft 38 can additionally be rotatably mounted in a bearing 41 on a wall of the biomass boiler 1, which in the illustrated embodiment is opposite the further partition wall 33. The deflection lever 39 allows a linear movement of the rotor 40 to be converted into a rotational movement of the rotary shaft 38. In the illustrated embodiment, a conversion element 42 is fixedly attached to the rotary shaft 38, with which the rotational movement of the rotary shaft 38 can be converted into a pivoting movement of the closing element 22 in order to pivot the closing element 22 between the open position and the closed position. As shown in particular in Fig. 2 As can be seen, the conversion element 42 preferably has two parallel angle elements 43, each with two legs 44a, 44b arranged at substantially 90° to each other. One leg 44a of each angle element 43 is attached to the rotating shaft 38. An actuating bolt 45, preferably rotatably mounted, is arranged between the other legs 44b. The actuating bolt 45 is located in a region between two pins 46 (see Fig. 4 The locking element 22 is mounted on pins 46, which are attached to it and are oriented essentially perpendicular to it. By rotating the rotary shaft 38, the actuating bolt 45 is moved upwards or downwards according to a radius of rotation and, depending on the direction of rotation of the rotary shaft 38, one of the pins 46 is pushed upwards or downwards by the actuating bolt 45, thereby moving the locking element 22 between the closed and open positions. The pins 46 are dimensioned with respect to their length such that the actuating bolt 45 can always press against one of the pins 46 along its radius of rotation between the open and closed positions of the locking element.

[0036] During operation of the biomass boiler 1, the closing element 22 is preferably closed during a combustion process in order to avoid affecting the pressure conditions in the biomass boiler 1. However, before and / or after a combustion process, it may be provided that the closing element 22 is moved to the open position and ash is conveyed into the ash collection area 17 by means of the discharge device 18. This is described in Fig. 6 As shown, in step 100, the grate 3 is moved into the tilting position by the grate drive 31, and simultaneously the closing element 22 is moved into the open position by the closing drive 30, which can be formed by the grate drive 31. In the tilting position, ash 5 falls from the grate 3 into the first ash chamber. 7.In step 101, the discharge device 18 is activated, conveying ash 5 into the ash collection area 17 as described above. After a predetermined period, which may depend on the duration of a previous combustion process, the discharge device 18 is deactivated again. In step 102, the grate drive returns the combustion grate 3 to the horizontal combustion position. The closing drive 30 moves the closing element 22 into the closed position. In step 103, solid biomass fuel is introduced into the combustion chamber 2, and a combustion process takes place. Such a combustion process can last several hours, and additional solid biomass fuel can be fed into the combustion chamber 2 during the combustion process.

[0037] Steps 100-102 can also be carried out additionally or alternatively following a combustion process 103, as described in Fig. 6as indicated by the dashed lines. It is therefore possible to perform steps 100-102 before and after a combustion process 103, or to perform steps 100-102 either before or after a combustion process 103.

Claims

1. Biomass heating boiler (1) for a biomass solid fuel, in particular pellets and / or wood chips, comprising: a boiler housing (51), a combustion chamber (2) within the boiler housing (51), a heat exchanger (12) with a rising flue (11) and / or a falling flue (14), a first ash chamber (7) for collecting ash (5) from the combustion chamber (2), which is preferably arranged below a fire grate (3) of the combustion chamber (2), a second ash chamber (10) for collecting fly ash (5a), which is separated from the first ash chamber (7) by a partition wall (16) and is preferably arranged below the rising flue (11) and / or the falling flue (14), a discharge device (18) for discharging ash (5, 5a), which is configured to convey ash (5, 5a) from the first (7) or the second ash chamber (10) through an ash-passage opening (19) in the partition wall (16) into the second (10) or respectively first ash chamber (7) and subsequently into an ash collection region (17), a closing element (22) for closing the ash-passage opening (19), characterized in that the biomass heating boiler (1) comprises a closing drive (30), which is connected to the closing element (22), and with which the closing element (22) is transferable between a closing position, in which the ash-passage opening (19) is closed, and an open position, in which the ash-passage opening (19) is released and in which ash (5, 5a) can be conveyed by means of the discharge device (18) through the ash-passage opening (19).

2. Biomass heating boiler (1) according to claim 1, characterized in that the closing element (22) comprises a plate.

3. Biomass heating boiler (1) according to claim 1 or 2, characterized in that the closing element (22) comprises a closing-element opening (27), which in the open position at least partially aligns with the ash-passage opening (19) in the partition wall (16) and in the closing position is substantially completely covered by the partition wall (16).

4. Biomass heating boiler (1) according to any one of claims 1 to 3, characterized in that the closing element (22) is pressed against the partition wall (16) with at least one pressing element (23), in particular a spring element (24).

5. Biomass heating boiler (1) according to any one of claims 1 to 4, characterized in that the biomass heating boiler (1) comprises a fire grate (3), which can be pivoted by means of a grate drive (31), and the closing drive (30) is formed by the grate drive (31), such that the closing element (22) is transferable by the grate drive (31) between the open position and the closing position.

6. Biomass heating boiler (1) according to claim 5, characterized in that the grate drive (31) and the closing element (22) are coupled via a linkage (37) and the linkage (37) is guided from the first (7) or the second ash chamber (10) through a transition opening (53) in a further partition wall (33), which preferably adjoins the first (7) and / or second ash chamber (10), to the grate drive (31).

7. Biomass heating boiler (1) according to any one of claims 1 to 6, characterized in that the discharge device (18) comprises a shaft (20), which is guided through a shaft opening (50) of the partition wall (16), and the closing element (22) has a recess (28) for the shaft (20).

8. Biomass heating boiler (1) according to claim 7, characterized in that the discharge device (18) comprises, on the shaft (20), a first screw thread (21a) for conveying ash (5, 5a) in the first ash chamber (7) and a second screw thread (21b) for conveying ash (5, 5a) in the second ash chamber (10), wherein the winding directions of the first (21a) and the second screw thread (21b) are preferably the same.

9. Biomass heating boiler (1) according to any one of claims 1 to 8, characterized in that the closing element (22) is transferable between the open position and the closing position by means of a rotational pivoting movement, preferably a rotational pivoting movement in a plane parallel to the partition wall (16).

10. Biomass heating boiler (1) according to claims 7 or 8 and 9, characterized in that an axis of rotation (29) for the rotational pivoting movement of the closing element (22) is oriented substantially parallel to the shaft (20) of the discharge device (18).

11. Biomass heating boiler (1) according to claim 10, characterized in that the recess (28) of the closing element (22) for the shaft (20) is curved according to a bending radius (R1), which substantially corresponds to a distance between the axis of rotation (29) and the shaft (20).

12. Biomass heating boiler (1) according to any one of claims 1 to 11, characterized in that the closing element (22) seals the ash-passage opening (19) in the closing position such that, in operation of the biomass heating boiler (1), a pressure difference between the first and the second ash chamber, which preferably amounts to between 0.001 bar and 0.01 bar, in particular between 0.0015 bar and 0.003 bar, for example substantially 0.002 bar, is maintained.

13. Method for operating a biomass heating boiler (1) for a biomass solid fuel, in particular pellets and / or wood chips, which comprises: a boiler housing (51), a combustion chamber (2) within the boiler housing (51), a heat exchanger (12) with a rising flue (11) and / or a falling flue (14), a first ash chamber (7) for collecting ash (5) from the combustion chamber (2), which is preferably arranged below a fire grate (3) of the combustion chamber (2), a second ash chamber (10) for collecting fly ash (5a), which is separated from the first ash chamber (7) by a partition wall (16) and is preferably arranged below the rising flue (11) and / or the falling flue (14), a discharge device (18) for discharging ash (5, 5a), which is configured to convey ash (5, 5a) from the first (7) or the second ash chamber (10) through an ash-passage opening (19) in the partition wall (16) into the second (10) or respectively first ash chamber (7) and subsequently into an ash collection region (17), a closing element (22) for closing the ash-passage opening (19), characterized in that the closing element (22) is transferred by means of a closing drive (30) from a closing position, in which the ash-passage opening (19) is closed, into an open position, in which the ash-passage opening (19) is released, and ash (5, 5a) is discharged with the discharge device (18) from the first (7) or the second ash chamber (10) through the ash-passage opening (19) into the second (10) or respectively first ash chamber (7) and subsequently into the ash collection region (19).

14. Method according to claim 13, characterized in that the closing drive (30) is formed by a grate drive (31) and the grate drive (31) is activated in order to bring a fire grate (3) into a tilting position and to bring the closing element (22) into the open position.