BIOMASS HEATING SYSTEM WITH IMPROVED CLEANING AND BLOCKAGE DETECTION

Description

TECHNICAL FIELD

[0001] The invention relates to a biomass heating system with improved cleaning and blockage detection.

[0002] In particular, the invention relates to a blockage detection system for cleaning combustion residues in a biomass heating system. STATE OF THE ART

[0003] EP 4 056 900 A1 discloses a biomass heating system for burning fuel in the form of pellets and / or wood chips, comprising: a boiler with a combustion device, a heat exchanger with a plurality of boiler tubes, a cleaning device comprising: a drive unit for driving the cleaning device, a crank element coupled to the drive unit via a freewheel, wherein the drive unit can drive the crank element in one direction of rotation, a thrust member provided for reciprocating movement and coupled to the crank element; at least one cleaning shaft arranged so as to be operatively connected to the thrust member, at least one cleaning element arranged so as to be operatively connected to the cleaning shaft;wherein the cleaning device is configured such that the thrust member is displaced in a thrust direction upon rotation of the crank element in the direction of rotation by the drive unit; and the thrust member is displaced in a pulse direction opposite to the thrust direction after a predetermined crank rotation position of the crank element has been exceeded.

[0004] US 2007 / 125281 A1 discloses a device for burning granular, solid fuel, for example pellets and the like, this device comprising: a combustion chamber, an air inlet for supplying air to the combustion chamber via at least one air chamber and at least one air duct for achieving an air flow through the combustion chamber, a supply and metering arrangement for supplying the fuel into the combustion chamber, an ignition device for igniting the fuel, a control unit for operating the combustion device and cooperating parts, an outlet for hot combustion gases from the combustion chamber, a movably arranged ash feeder with a drive unit controlled by the control unit for automatically supplying ash, ash, unburned fuel and slag products from the combustion chamber, wherein the ash feeder comprises a movable front part with a perforated bottom,which forms the above-mentioned inner floor, which is movable between at least one operating position, which opens up the lower end of the hearth, and an ash emptying position, wherein a first temperature sensor is positioned near the combustion chamber, the first sensor being connected to the control unit, which is arranged to enable the activation of the drive unit only when the detected temperature is below a critical value.

[0005] US 2007 / 215021 A1 discloses the following: In order for a burner pot for a grain kiln to be continuously operated, the burner pot has either: (1) an openable bottom having at least a first and a second position, one of the at least first and second positions being substantially closed to allow a body of combustible fuel to burn on its upper surface, the other of the at least first and second positions providing an opening, side wall portions of the burner pot and a top surface of the burner pot being shaped to allow a solid clinker to fall out of the opening in the openable bottom when the openable bottom is in its second position; or (2) a bottom formed as one of a series of portions of a rotatable member such that the member, upon rotation, carries ash from the bottom of the burner vessel with it.Between the openable or rotatable bottom, the side surfaces, and the top, a combustion volume is provided, which has an upper and a lower part. A fire burns on a combustion surface in the lower part upwards towards the upper part, so that combustion by-products accumulate on the combustion surface to cause burning fuel to combust at a higher level; the higher level has a smaller cross-sectional area than the lower part, allowing the combustion by-products to fall as a unit from the bottom opening of the burner pot. Easily ignitable fuel is conveyed from a hopper into the burner pot and ignited. When the temperature is high enough to ignite the less ignitable fuel, it is conveyed into the burner pot and the flow of easily ignitable fuel is stopped.

[0006] AT 13 825 U1 discloses a boiler with a combustion chamber connected to a lateral fuel conveyor and with a grate closing off the combustion chamber opposite an ash chamber. The grate has two grate sections arranged one behind the other in the conveying direction of the fuel conveyor, which are mounted for independent rotation about tilting shafts running transversely to the conveying direction of the fuel conveyor. To create potentially advantageous design conditions, it is proposed that the two grate sections be driven by means of separate actuators and be held in their rotational position, which determines the working position, exclusively by the actuators.

[0007] Biomass heating systems with outputs ranging from 20 to 500 kW are well known. Biomass can be considered an inexpensive, domestic, crisis-proof, and environmentally friendly fuel. Combustible biomass, or solid fuel, includes wood chips and pellets, for example.

[0008] Pellets usually consist of wood chips, sawdust, biomass, or other materials compressed into small discs or cylinders with a diameter of approximately 3 to 15 mm and a length of 5 to 30 mm. Wood chips (also known as wood chips, wood chips, or wood shavings) are wood that has been shredded using cutting tools.

[0009] Biomass heating systems for fuel in the form of pellets and wood chips essentially consist of a boiler with a combustion chamber and an adjoining heat exchanger. Due to stricter legal regulations in many countries, some biomass heating systems also feature a fine dust filter. Various other accessories are usually included, such as control devices, probes, safety thermostats, pressure switches, a flue gas recirculation system, and a separate fuel tank.

[0010] The combustion chamber typically includes a fuel supply system, an air supply system, and a fuel ignition device. The air supply system, in turn, typically includes a high-performance, low-pressure fan to favorably influence the thermodynamic factors during combustion in the combustion chamber. A fuel supply system can, for example, be provided with a side feed (so-called cross-feed firing). The fuel is fed into the combustion chamber from the side via a screw or piston.

[0011] The combustion chamber also typically contains a combustion grate, onto which the fuel is continuously fed and burned. This combustion grate stores the fuel for combustion and has openings that allow a portion of the combustion air to pass through as primary air to the fuel. The grate can also be rigid or movable. Movable grates typically serve to easily dispose of combustion residues created during combustion, such as ash and slag. However, these combustion residues can adhere or cake to the grate and require regular manual cleaning, which is a hassle. The ash and slag can also clog the air supply openings in the grate, thereby adversely affecting combustion efficiency.Practice shows that the combustion residues can adhere or bake, particularly in the openings of the grate, which makes cleaning the grate even more difficult.

[0012] The manner in which combustion residues form and adhere depends heavily on the various operating conditions of the boiler and, as a result, the combustion residues are very variable, which makes cleaning difficult.

[0013] As the primary air flows through the grate, the grate is also cooled, thus protecting the material. If the openings become clogged, this cooling effect is also impaired.

[0014] Furthermore, insufficient air supply on the grate can lead to increased slag formation. In particular, furnaces intended to be fed with different fuels, which is the subject of the present disclosure, have the inherent problem that the different fuels have different ash melting points, water contents, and different combustion behaviors. This makes it difficult to provide a heating system that is equally well suited to different fuels and whose grates can be cleaned accordingly.

[0015] With a rotating grate, there is the additional problem that rotation can be made more difficult or even hindered by combustion residues, which can cause the mechanics to wear out more than usual or even damage them.

[0016] The combustion chamber can also be regularly divided into a primary combustion zone (immediate combustion of the fuel on the grate) and a secondary combustion zone (afterburning of the flue gas). Drying, pyrolytic decomposition, and gasification of the fuel take place in the combustion chamber. Secondary air can also be introduced to completely combust the resulting combustible gases.

[0017] After drying, the combustion of pellets or wood chips essentially consists of two phases. In the first phase, the fuel is at least partially pyrolytically decomposed and converted into gas by high temperatures and air, which can be blown into the combustion chamber. In the second phase, the portion converted into gas is burned, as well as any remaining solids. As a result, the fuel outgasses, and the resulting gas is co-combusted.

[0018] Pyrolysis is the thermal decomposition of a solid material in the absence of oxygen. Pyrolysis can be divided into primary and secondary pyrolysis. The products of primary pyrolysis are pyrolysis coke and pyrolysis gases, with the pyrolysis gases being divided into those that are condensable and those that are non-condensable at room temperature. Primary pyrolysis takes place at roughly 250–450°C, and secondary pyrolysis at approximately 450–600°C. The subsequent secondary pyrolysis is based on the further reaction of the primary pyrolysis products. Drying and pyrolysis largely take place without the use of air, as volatile CH compounds escape from the particle, preventing air from reaching the particle surface. Gasification can be considered a part of oxidation; the solid, liquid, and gaseous products formed during pyrolytic decomposition are reacted by further heat.This occurs with the addition of a gasification agent such as air, oxygen, or even steam. The lambda value during gasification is greater than zero and less than one. Gasification takes place between approximately 300 and 850°C. Above approximately 850°C, complete oxidation occurs with excess air (lambda greater than 1). The reaction end products are essentially carbon dioxide, steam, and ash. The boundaries between all phases are not rigid, but fluid. The combustion process can be advantageously controlled using a lambda probe located at the boiler's exhaust outlet.

[0019] Generally speaking, the efficiency of combustion is increased by converting pellets into gas because gaseous fuel is better mixed with the combustion air, and lower emissions of pollutants, less unburned particles and ash are produced.

[0020] The combustion of biomass produces airborne combustion products whose main components are carbon, hydrogen and oxygen. These can be divided into emissions from complete oxidation, incomplete oxidation and substances from trace elements or contaminants. Emissions from complete oxidation are essentially carbon dioxide (CO2) and water vapor (H2O). The formation of carbon dioxide from the carbon in the biomass is the aim of combustion, as this allows the released energy to be used. The release of carbon dioxide (CO2) is largely proportional to the carbon content of the burned fuel; thus, the carbon dioxide also depends on the useful energy to be provided. A reduction can essentially only be achieved by improving efficiency.In any case, combustion residues such as ash and slag are also produced, which can adhere firmly to the grate.

[0021] Particularly in biomass heating systems designed to be suitable for various types of biofuel, the varying quality and consistency of the fuel makes it difficult to maintain consistently high efficiency, especially since ash and slag formation on the grate can occur to a very different extent. Therefore, grate cleaning is a highly variable process that depends on the specific conditions of ash and slag formation. Conventional state-of-the-art solutions involve cleaning processes and devices that are therefore significantly oversized and extensive. There is a significant need for optimization in this regard.

[0022] In addition, the biofuel may be contaminated. These contaminants can increase ash and slag formation and / or cause blockages in the grate openings and the rotating mechanism. Blockages can also occur in rotating grates.

[0023] Another disadvantage of conventional pellet biomass heating systems is that pellets falling into the combustion chamber can roll or slide off the grate and into a lower-temperature area of ​​the combustion chamber or where air flow is poor, or even fall into the lowest chamber of the boiler. Pellets that do not remain on the grate burn incompletely, resulting in poor efficiency, excessive ash, and a certain amount of unburned pollutant particles.

[0024] Biomass heating systems for pellets or wood chips have the following additional disadvantages and problems.

[0025] One problem is that incomplete combustion due to the uneven distribution of fuel on the grate and the suboptimal mixing of air and fuel promotes the accumulation and falling of unburned ash through the air inlet openings that lead directly to the combustion grate into the air ducts.

[0026] This is particularly disruptive and causes frequent interruptions for maintenance work such as cleaning the boiler in general, and the rotating grate in particular. For all these reasons, a large excess of air is normally maintained in the combustion chamber, but this reduces the flame temperature and combustion efficiency, and leads to high NOx emissions. Such excess air is undesirable. Therefore, it is also problematic that cleaning intervals are planned to be shorter than necessary purely as a precautionary measure, which results in suboptimal boiler operation.

[0027] The above problems were addressed in the (post-published) prior art of EP 3 789 676 B1 with a cleaning device for a rotating grate with a tapping effect. A drop hammer configuration ensures that a mass element strikes a stop on the respective element when the elements of the rotating grate rotate.

[0028] However, it has been shown that this state-of-the-art solution has two disadvantages. Firstly, the drop hammer configuration under the rotating grate requires a considerable amount of space, making it too large for boilers with lower outputs (and dimensions). Secondly, the cleaning efficiency of the rotating grate still needs improvement. Furthermore, even with this solution, the cleaning intervals are too short, the problem of a potential blockage in the rotation of the rotating grate elements still exists, and the cleaning processes themselves are designed to be extensive for safety reasons.

[0029] Based on the problems mentioned above, it may be an object of the present invention to provide a biomass heating system which enables optimized cleaning of the biomass heating system.

[0030] For example, easy ash removal or cleaning of the grate should be possible, as should easy maintenance of the grate of the biomass heating system.

[0031] In addition, there should be high system availability.

[0032] The following consideration could play a role in this context, both in accordance with the invention and in addition: The hybrid technology should enable the use of both pellets and wood chips with water contents between 8 and 35 percent by weight.

[0033] The above-mentioned task(s) or the potential individual problems may also relate to other aspects of the overall system, for example the combustion chamber or the air flow through the grate.

[0034] This object(s) is / are solved by the subject matter of the independent claims, which define the invention. Further aspects and advantageous developments are the subject matter of the dependent claims.

[0035] The advantages of this configuration and also the following aspects will become apparent from the following description of the associated embodiments.

[0036] According to the invention, a biomass heating system for burning biogenic fuel is disclosed, the system comprising: a boiler with a combustion device and with a heat exchanger; a control device with a storage device; at least one sensor that can detect a state of an ash removal device for cleaning combustion residues from the boiler; wherein the biomass heating system is configured such that the control device can detect a blockage of the ash removal device by means of information received from the sensor.

[0037] According to the invention, a biomass heating system is provided, this system comprising: a boiler with a combustion device and with a heat exchanger, wherein the combustion device has a rotating grate with at least one rotating grate element rotatably mounted about a rotation axis, wherein the rotating grate can be rotated in order to clean the combustion residues from the combustion surface of the rotating grate; at least one rotation angle sensor as the sensor, which can detect a rotation angle of the rotation axis and which is communicatively connected to the control device; at least one drive for rotating the rotation axis, wherein the drive is controlled by the control device; wherein the biomass heating system is configured to detect a blockage of a rotation of the at least one rotating grate element if a certain rotation speed of the at least one rotating grate element is less than a predetermined threshold value.

[0038] According to a further development of the above aspects, the following is disclosed, wherein the biomass heating system is configured to determine the rotational speed by means of a difference between two detected angles of rotation, wherein the two angles of rotation are detected at a predetermined time interval from one another.

[0039] According to a further development of the above aspects, the following is disclosed, wherein the biomass heating system is configured to detect the blockage only if the determined rotational speed is less than the predetermined threshold value in at least two consecutive determinations.

[0040] According to a further development of the above aspects, the following is disclosed, wherein the biomass heating system is configured such that, upon positive detection of the blockage of the rotation in a first direction of rotation, a breaker function is carried out, in which the at least one rotating grate element is rotated back in a second direction of rotation for a predetermined time counter to the first direction of rotation, and subsequently the at least one rotating grate element is rotated again in the first direction of rotation.

[0041] According to a further development of the above aspects, the following is disclosed, wherein the heat exchanger comprises a plurality of boiler tubes with turbulators located therein; and the sensor is a position sensor that can directly or indirectly detect a rest position of the turbulators.

[0042] According to the invention, a method for detecting a blockage of a rotating grate of a biomass heating system is disclosed, wherein the biomass heating system comprises: a boiler with a combustion device and with a heat exchanger, a control device with a storage device; at least one sensor that can detect a state of an ash removal device for cleaning combustion residues from the boiler; wherein the method comprises the following steps: detecting, by the control device, a blockage of the ash removal device by evaluating information from the sensor.

[0043] According to the invention, the biomass heating system further comprises the following: a rotating grate of the combustion device having at least one rotating grate element rotatably mounted with a rotation axis; at least one rotation angle sensor which can detect a rotation angle of the rotation axis and which is communicatively connected to the control device; at least one drive for rotating the rotation axis, wherein the drive is controlled by the control device, wherein the method comprises the following steps: determining the rotational speed of the at least one rotating grate element; comparing the determined rotational speed with a predetermined threshold value; detecting a blockage of a rotation of the at least one rotating grate element if the comparison shows that the rotational speed is lower than the threshold value.

[0044] According to a development of the above aspects, the following is disclosed, wherein determining the rotational speed comprises the following steps: detecting a first rotational angle at a first time; detecting a second rotational angle at a second time, which is set a predetermined waiting time after the first time; calculating the difference between the first rotational angle and the second rotational angle.

[0045] According to a further development of the above aspects, the following is disclosed, wherein the blockage is only detected if the determined rotational speed is less than the predetermined threshold value in at least two consecutive determinations.

[0046] According to a development of the above aspects, the following is disclosed, further comprising the following steps: carrying out a breaker function upon positive detection of the blockage of the rotation in a first direction of rotation, wherein the breaker function consists in that the at least one rotating grate element is rotated back in a second direction of rotation for a predetermined time counter to the first direction of rotation, and subsequently the at least one rotating grate element is rotated again in the first direction of rotation.

[0047] Also disclosed is a computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method of one of the above aspects.

[0048] Also disclosed is a computer-readable storage medium on which the computer program of the preceding aspect is stored.

[0049] The individual effects and advantages of these aspects are shown in the following figure description and the corresponding drawings.

[0050] "Horizontal" in this case can refer to a flat alignment of an axis or cross-section, assuming that the boiler is also installed horizontally, whereby, for example, the ground level can be the reference. Alternatively, "horizontal" in this case can mean "parallel" to the base plane of the boiler, as this is commonly defined. Further alternatively, especially in the absence of a reference plane, "horizontal" can be understood merely as at least approximately perpendicular to the direction of action of the Earth's gravitational force or acceleration.

[0051] Although all of the above individual features and details of an aspect of the invention and the developments of this aspect are described in connection with the biomass heating system, these individual features and details are also disclosed as such independently of the biomass heating system.

[0052] The biomass heating system is explained in more detail below in exemplary embodiments and individual aspects using the figures: Fig. 1 shows a three-dimensional overview view of a biomass heating system according to an embodiment of the invention; Fig. 2 shows a cross-sectional view through the biomass heating system of the Fig. 1 , which was taken along a section line SL1 and which is shown viewed from the side view S; Fig. 3 also shows a cross-sectional view through the biomass heating system of the Fig. 1 with a representation of the flow pattern, wherein the cross-sectional view was taken along a section line SL1 and is shown viewed from the side view S; Fig. 4 shows a partial view of the Fig. 2 , which has a combustion chamber geometry of the boiler of the Fig. 2 and Fig. 3 Fig. 5 shows a sectional view through the boiler or the combustion chamber of the boiler along the vertical section line A2 of the Fig. 4 ; Fig. 6 shows a three-dimensional sectional view of the primary combustion zone of the combustion chamber with the rotating grate of the Fig. 4 ; Fig. 7 shows corresponding to the Fig. 6 an exploded view of the combustion chamber stones; Fig. 8 shows a top view of the rotating grate with rotating grate elements from the viewpoint of section line A1 of the Fig. 2 ; Fig. 9 shows the rotating grate of the Fig. 2 in the closed position, i.e. in a first state, with all rotating grate elements being horizontally aligned or closed; Fig. 10 shows the rotating grate of the Fig. 9 in the state of partial cleaning, thus a second state, of the rotating grate in ember maintenance mode; Fig. 11 shows the rotating grate of the Fig. 9 in the state of universal cleaning, thus in a third state, wherein the universal cleaning is preferably carried out during a plant shutdown; Fig. 13 shows a performance diagram of an exemplary cycle of the combustion operation of the biomass heating system from ignition to burnout; Fig. 14 shows a triggering method with which a cleaning of the boiler can be triggered; Fig. 15 shows a further development of the triggering method of the Fig. 14 ; Fig. 16 shows a cleaning optimization process; Fig. 17a shows a cleaning process for the boiler; Fig. 17b shows a first anti-blockage process, which is a further development of the process of Fig. 17a Figures 17c and 17d show a second anti-blockade method in further development of the methods of Fig. 17a and / or 17b; Fig. 18 shows a blockage detection method for the rotating grate of the biomass heating system; Fig. 19 shows a diagram with the method of Fig. 18 with a temporal course of the angle of rotation without blockage, with blockage and with a breaker function on detected blockage, as well as an alternative in response to a detected blockage. DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0053] Various merely exemplary embodiments of the present disclosure are disclosed below with reference to the accompanying drawings. However, embodiments and terms used therein are not intended to limit the present disclosure to specific embodiments.

[0054] If more general terms are used in the description for features or elements shown in the figures, it is intended that not only the specific feature or element in the figures is disclosed to the person skilled in the art, but also the more general technical teaching.

[0055] With regard to the description of the figures, the same reference numerals may be used in the individual figures to refer to similar or technically corresponding elements. Furthermore, for the sake of clarity, more elements or features may be depicted with reference numerals in individual detail or partial views than in the overview views. It is assumed that these elements or features are also disclosed accordingly in the overview views, even if they are not explicitly listed there.

[0056] It should be understood that a singular form of a noun corresponding to an object may include one or more of the things, unless the context in question clearly indicates otherwise.

[0057] In the present disclosure, a term such as "A or B," "at least one of A and / or B," or "one or more of A and / or B" may include all possible combinations of features listed together. Terms such as "first," "second," "primary," or "secondary" used herein may represent various elements regardless of their order and / or meaning and do not limit corresponding elements. When an element (e.g., a first element) is described as being "operably" or "communicatively" coupled or connected to another element (e.g., a second element), the element may be connected directly to the other element or may be connected to the other element via another element (e.g., a third element).

[0058] For example, a term "configured to" (or "adapted to) used in the present disclosure may be replaced with "suitable for," "suitable for," "adapted to," "made to," "capable of," or "designed to," as technically feasible. Alternatively, in a particular situation, a term "device configured to" or "adapted to" may mean that the device can operate in conjunction with another device or component, or can perform a corresponding function.

[0059] All size specifications given in "mm" are to be understood as a size range of ±1 mm around the specified value, unless another tolerance or other ranges or range limits are explicitly stated.

[0060] It should be noted that the individual aspects at hand, for example the cleaning device, are disclosed separately from or separately from the biomass heating system as individual parts or individual devices. It is therefore clear to the person skilled in the art that individual aspects or system components are also disclosed individually. In the present case, the individual aspects or system components are disclosed in particular in the subsections marked with parentheses. It is intended that these individual aspects may also be claimed separately.

[0061] Furthermore, for the sake of clarity, not all features and elements are individually identified in the figures, especially when they are repeated. Rather, the elements and features are identified as examples. Analogous or identical elements are to be understood as such. (Biomass heating system)

[0062] First, the biomass heating system 1 of the present disclosure will be described in general in order to shed more light on the "environment" of the cleaning and in particular of the ash removal devices 7, 25, i.e. the present rotating grate 25 with its cleaning and also the ash screw 71.

[0063] Fig. 1 shows a three-dimensional overview view of the biomass heating system 1 according to an embodiment of the invention.

[0064] In the figures, the arrow V indicates the front view of the system 1, and the arrow S indicates the side view of the system 1.

[0065] The biomass heating system 1 comprises a boiler 11 mounted on a boiler base 12. The boiler 11 has a boiler housing 13, for example, made of sheet steel. Insulation of the boiler 11 is not fully illustrated.

[0066] Located in the front part of the boiler 11 is a combustion device 2 (not shown), which can be accessed via a first maintenance opening with a closure 21. A rotating mechanism holder 22 (not shown) for a rotating grate 25 supports a rotating mechanism 23, with which drive forces can be transmitted to rotating axes 81 or bearing axes 81 of the rotating grate 25. The rotating mechanism 23 can preferably have an expandable transmission element, for example a toothed belt, which transmits the drive forces of the motor 231 to the rotating axis 81. The rotating grate 25 has a dual function in this case. On the one hand, it is a grate for the fuel, and on the other hand, it also serves as an ash removal device 25, since it can remove the combustion residues by tipping them away.

[0067] In the middle part of the boiler 11 there is a heat exchanger 3 (not shown), which can be reached from above via a second maintenance opening with a closure 31.

[0068] In the rear part of the boiler 11 there is an electrostatic filter device 4 (also referred to as filter 4 for short) with an electrode 45 (cf. Fig. 2 ff.), which is suspended by an insulating electrode holder 43 and which is energized via an electrode supply line 42. The filter device 4 has a tubular internal volume 46b, which extends in a longitudinal direction of the filter device 4.

[0069] The exhaust gas from the biomass heating system 1, which has flowed through the filter device 4, is discharged via an exhaust gas outlet 41, which is arranged fluidically downstream of the filter device 4. A fan or blower can be provided here.

[0070] A recirculation device 5 is provided behind the boiler 11, which recirculates part of the flue or exhaust gas via recirculation ducts 51, 53 and 54 and flaps 52 for cooling the combustion process and reuse in the combustion process.

[0071] Furthermore, the biomass heating system 1 has a fuel feed 6, with which the fuel is conveyed in a controlled manner to the combustion device 2 in the primary combustion zone 26 from the side onto the rotating grate 25. The fuel feed 6 has a rotary valve 61 with a fuel feed opening 65, wherein the rotary valve 61 has a drive motor 66 with control electronics. An axle 62 driven by the drive motor 66 drives a transmission mechanism 63, which can drive a fuel conveyor screw 67 (not shown), so that the fuel is conveyed to the combustion device 2 in a fuel feed channel 64.

[0072] In the lower part of the biomass heating system 1, an ash removal device 7 is provided, which has an ash removal screw 71 in an ash removal channel, which is driven by a motor 72. This ash removal device 7 is preferably configured such that when the ash removal screw 71 is rotated by the motor 72, the turbulators in the heat exchanger 3 are also moved back and forth, thus cleaning the heat exchanger. Slag or other residues from combustion (e.g., nails) can become trapped in this ash removal device 7 and jam the ash removal device 7.

[0073] The biomass heating system 1 further comprises a control device 100. This control device 100 is provided with a conventional processor, volatile and non-volatile memory (e.g., (S-)RAM, ROM, flash, and / or cache memory), and various interfaces. Analog or digital inputs and outputs can be provided as interfaces. For example, CAN bus interfaces, 0-10 V analog inputs, or 4-20 mA analog inputs / outputs for sensors and actuators, and / or RS-232 interfaces can be provided. In addition, the control device preferably (optionally) comprises at least one interface with an Internet protocol (IP, Ethernet, WLAN) according to known standards. This allows the control device to communicate, preferably via the Internet, with the data processing devices installed remotely from the biomass heating system 1.

[0074] The possibility of communication with remotely located data processing facilities may be provided.

[0075] Furthermore, the control device 100 can have a keyboard and / or a display for displaying operating data. The display can also have a so-called touch function, allowing an operator to make inputs on the display.

[0076] The control device 100 may also have a voltage generation unit which generates the voltage for the operation of the filter device 4.

[0077] In addition to the control device 100, a plurality of sensors are provided for detecting physical and / or chemical variables of the biomass heating system 1. Examples of such sensors are described in relation to the Fig. 2 described in more detail.

[0078] One of the sensors that may be communicatively connected to the control device 100 may be a boiler temperature sensor 115. A combustion chamber 24 or boiler tubes 32 (see Fig. 2 ) are at least partially surrounded by a heat exchange medium 38 (cf. Fig. 2 ), for example (heating) water. The boiler temperature sensor 115 preferably measures or detects the temperature of the heat exchange medium 38 in the boiler 11 at a location that is representative of an average temperature of the heat exchange medium 38 in the boiler 11.

[0079] The temperature detected by the boiler temperature sensor 115 is communicated to the control device 100 (preferably as a signal, for example, a voltage signal, a current signal, or a digital signal), whereby the temperature (which may still need to be calculated from the signal; for example, a voltage of 1 volt could correspond to 10 degrees Celsius above zero) is available to the control device 100 for further processing. The same applies to all other sensors or detecting devices described herein.

[0080] The control device can store the temperature detected by the boiler temperature sensor 115 in a (permanent or volatile) memory. The same applies analogously to all other detected sensor data.

[0081] The above statements regarding boiler temperature sensor 115 and the detected temperature (as a detected physical quantity) can also be applied to other sensors and physical or chemical quantities, in particular to the sensors which are described with reference to Fig. 2 described. Sensors that can be used include, in particular, fuel bed height sensors or ember bed height sensors 86, the lambda probe 112, the exhaust gas temperature sensor 111, the vacuum sensor 113, and the heating water temperature sensor 114.

[0082] Furthermore, the control device 100 can have sensors with which the (target) voltage that should be applied to the electrode 45 of the filter device 100 and the current If that flows in the filter device 4 can be detected. The same applies to the various motors that are used for cleaning the boiler, i.e., the rotation of the rotating grate elements 252, 253, 254 or the ash screw 71. Thus, the control device 100 can have current detection means for detecting the current through the electrode 45 or through the various motors. Likewise, the control device 100 can have voltage detection means for detecting the filter voltage Vf that is applied to the electrode 45 or the voltage that is applied to the respective motor.

[0083] Furthermore, at least one mechanical, optical, or inductive rotation angle sensor or position sensor 259 can be provided, with which the rotational position or angle of rotation of the rotating grate elements 252, 253, 254 can be detected. Likewise, a position sensor can be provided that can detect the rotational position of the ash auger 71.

[0084] Furthermore, a limit switch can be provided with which an end stop of the rotating grate on the transition element 255 (ie the rotating grate elements 252, 253, 254 are in their horizontal working position) can be detected.

[0085] Furthermore, at least one position sensor 75 (also referred to as cleaning sensor 76), which is, for example, an inductive position switch, is provided. The position sensor 75 is provided for detecting the position or the rest or end position of the cleaning mechanism, which is driven by the motor 72, and / or the ash auger 71. In particular, the cleaning sensor 76 can be provided such that it can detect a rest position of the cleaning mechanism. For example, the cleaning sensor 76 can output a positive signal when the cleaning mechanism is in its rest position (e.g., the turbulators are in their lowest position) and is not actively deflected by the motor 72.For example, the cleaning sensor 76 can be an inductive switch, whereby the presence or position of a rod, lever, or similar mechanical coupling element between the auger 71 and the motor 72 in the rest position of the cleaning mechanism can be detected by the sensor 76 and / or the rotational position of the auger 71 and / or the height of the turbulators 36, 37. A position sensor 75 can, for example, indirectly detect the rest position of the turbulators 36, 37 by detecting the position of a coupling element of the cleaning mechanism between the motor 72 and the turbulators 36, 37. By determining the position, the status of the ash removal can be determined.

[0086] In addition, the actuators of the biomass heating system 1 can also be communicatively connected to the control device 100. For example, the air valves 52 of the recirculation device 5, the ignition device 201, the motors 231 and 66, the electrostatic filter 4 or the electrostatic precipitator 4 (e.g., its on / off state Sf,), the ash removal system 7 or its motor 72, the fuel supply system 6 with its rotary valve 61 or its drive motor 66 can be controlled by the control device 100.

[0087] The control device 100 controls the at least one motor 231 or a drive unit 231 for rotating the rotating grate elements 252, 253, 254 explained later. The control device can also detect the current flowing through the at least one motor using a current sensor. Furthermore, the voltage applied to the motor can optionally also be detected, and thus the (control) power required for motor rotation can also be calculated.

[0088] Furthermore, the filter device 4 is communicatively connected to the control device 100 such that the state, voltage, and / or current supply of the electrode 45 can be controlled. The control device 100 can be configured such that the on / off state Sf of the electrode 45 and its voltage Vf can be adjusted. For example, the voltage can be adjusted within a range of 10-80 kV, preferably within a range of 10-60 kV.

[0089] The control device 100 can thus regulate the biomass heating system 1. At least one detected physical / chemical variable and / or at least one electrical variable of at least one sensor of the biomass heating system 1 is / are communicated to the control device 100. The biomass heating system 1 uses this variable(s) to calculate a control response, which is in turn used to adjust at least one actuator of the biomass heating system 1. The adjustment of the at least one actuator, in turn, influences the physical / chemical processes in the biomass heating system 1 (in particular those of combustion), which are in turn recorded by the at least one sensor. This closes at least one control loop. Due to the multitude of possible control tasks of the control device 100, the control device 100 can also control more than one control loop of the biomass heating system simultaneously.

[0090] In particular, the control of the filter device (voltage control of the electrode 45) can be based on various detected variables.

[0091] Fig. 2 shows a cross-sectional view through the biomass heating system 1 of the Fig. 1 , which was made along a section line SL1, and which is shown viewed from the side view S. In the corresponding Fig. 3 , which has the same cut as Fig. 2 For the sake of clarity, the flue gas flows "S" and flow cross-sections are shown schematically (These flows also correspond to process steps S1...S7, from the generation of the flue gas to the outlet from the biomass heating system 11). Fig. 3 It should be noted that individual areas compared to the Fig. 2 are shown dimmed. This is only for the clarity of the Fig. 3 and the visibility of the flow arrows S5, S6 and S7.

[0092] From left to right are Fig. 2 The combustion device 2, the heat exchanger 3, and an (optional) filter device 4 of the boiler 11 are provided. The boiler 11 is mounted on the boiler base 12 and has a multi-walled boiler casing 13 in which water or another fluid heat exchange medium 38 can circulate. A water circulation device 14 with a pump, valves, pipes, etc. is provided for the supply and removal of the heat exchange medium.

[0093] The combustion device 2 has a combustion chamber 24, in which the fuel combustion process essentially takes place. The combustion chamber 24 has a multi-part rotating grate 25 on which the fuel bed 28 rests. The multi-part rotating grate 25 is rotatably mounted by means of a plurality of bearing axes 81.

[0094] Further referring to Fig. 2 and Fig. 3 The primary combustion zone 26 of the combustion chamber 24 is enclosed by (a plurality of) combustion chamber bricks 29, whereby the combustion chamber bricks 29 define the geometry of the primary combustion zone 26. The cross-section of the primary combustion zone 26 (for example) along the horizontal section line A1 is essentially oval (for example, 380 mm +- 60 mm x 320 mm ± 60 mm; it should be noted that some of the above size combinations can also result in a circular cross-section). The arrow S1 schematically represents the flow from the secondary air nozzle 291, wherein this flow (shown purely schematically) has a swirl induced by the secondary air nozzles 291 in order to improve the mixing of the flue gas.

[0095] The secondary air nozzles 291 are designed such that they introduce the secondary air (preheated by the combustion chamber bricks 29) tangentially into the oval cross-section of the combustion chamber 24. This creates a vortex- or swirling flow S1 that flows upwards in a roughly spiral or helical manner. In other words, an upward spiral flow rotating around a vertical axis is formed.

[0096] The secondary air nozzles 291 are thus oriented such that they introduce the secondary air—viewed in the horizontal plane—tangentially into the combustion chamber 24. In other words, the secondary air nozzles 291 are each provided as an inlet for the secondary air that is not aligned with the combustion chamber center. Furthermore, such a tangential inlet can also be used with a circular combustion chamber geometry.

[0097] All secondary air nozzles 291 are oriented such that they each produce either a right-handed or a left-handed flow. Thus, each secondary air nozzle 291 can contribute to the generation of vortex flows, with each secondary air nozzle 291 having a similar orientation. Regarding the above, it should be noted that in exceptional cases, individual secondary air nozzles 291 can also be arranged neutrally (oriented toward the center) or counter-rotating (in the opposite direction), although this may impair the fluidic efficiency of the arrangement.

[0098] The combustion chamber bricks 29 form the inner lining of the primary combustion zone 26, store heat, and are directly exposed to the fire. Thus, the combustion chamber bricks 29 also protect the other material of the combustion chamber 24, for example, cast iron, from the direct impact of flames in the combustion chamber 24. The combustion chamber bricks 29 are preferably adapted to the shape of the grate 25. The combustion chamber bricks 29 further comprise secondary air or recirculation nozzles 291, which recirculate the flue gas into the primary combustion zone 26 for renewed participation in the combustion process and, in particular, for cooling as required. The secondary air nozzles 291 are not aligned with the center of the primary combustion zone 26, but are aligned eccentrically to create a swirl in the flow in the primary combustion zone 26 (i.e., a swirl and vortex flow, which will be explained in more detail later). The combustion chamber bricks 29 will be explained in more detail later.An insulation 311 is provided at the boiler tube inlet. The oval cross-sectional shape of the primary combustion zone 26 (and the nozzle) as well as the length and position of the secondary air nozzles 291 advantageously promote the formation and maintenance of a vortex flow, preferably up to the ceiling of the combustion chamber 24.

[0099] A secondary combustion zone 27 adjoins the primary combustion zone 26 of the combustion chamber 26, either at the level of the combustion chamber nozzles 291 (functionally or in terms of combustion technology) or at the level of the combustion chamber nozzle 203 (purely structurally or in terms of construction), and defines the radiation part of the combustion chamber 26. In the radiation part, the flue gas produced during combustion releases its thermal energy mainly through thermal radiation, in particular to the heat exchange medium, which is located in the two left-hand chambers for the heat exchange medium 38. The corresponding flue gas flows are in Fig. 3 The flow patterns are indicated purely by way of example by arrows S2 and S3. These vortex flows may also contain slight backflows or other turbulences that are not represented by the purely schematic arrows S2 and S3. However, the basic principle of the flow pattern in the combustion chamber 24 is clear and calculable to the person skilled in the art, based on the arrows S2 and S3.

[0100] Caused by the secondary air injection, pronounced swirling, rotating, or vortex flows form in the isolated or confined combustion chamber 24. The oval geometry of the combustion chamber 24, in particular, contributes to the undisturbed and optimal development of the vortex flow.

[0101] After exiting nozzle 203, which further concentrates these vortex flows, candle-flame-shaped rotational flows S2 appear, which can advantageously extend to the combustion chamber ceiling 204, thus better utilizing the available space of the combustion chamber 24. The vortex flows are concentrated in the center of the combustion chamber and ideally utilize the volume of the secondary combustion zone 27. Furthermore, the constriction created by the combustion chamber nozzle 203 for the vortex flows reduces the rotational flows, thereby creating turbulence to improve the mixing of the air-flue gas mixture. Thus, cross-mixing occurs due to the constriction caused by the combustion chamber nozzle 203. However, the rotational momentum of the flows is at least partially retained above the combustion chamber nozzle 203, which maintains the propagation of these flows up to the combustion chamber ceiling 204.

[0102] The secondary air nozzles 291 are thus integrated into the elliptical or oval cross-section of the combustion chamber 24 in such a way that, due to their length and orientation, they induce vortex flows that set the flue gas-secondary air mixture in rotation and thereby (further improved in combination with the combustion chamber nozzle 203 positioned above) enable complete combustion with minimal excess air and thus maximum efficiency.

[0103] The secondary air supply is designed in such a way that it cools the hot combustion chamber bricks 29 by flowing around them and, in turn, the secondary air itself is preheated, whereby the burnout speed of the flue gases is accelerated and the completeness of the burnout is ensured even at extreme partial load (e.g. 30% of the nominal load).

[0104] The first maintenance opening 21 is insulated with an insulating material, such as Vermiculite™. The secondary combustion zone 27 is configured to ensure exhaustion of the flue gas. The specific geometric design of the secondary combustion zone 27 will be explained in more detail later.

[0105] After the secondary combustion zone 27, the flue gas flows into the heat exchanger device 3, which has a bundle of parallel boiler tubes 32. In the boiler tubes 32, the flue gas now flows downwards, as in Fig. 3 indicated by the arrows S4. This part of the flow can also be referred to as the convection part, since the heat transfer from the flue gas occurs primarily at the boiler tube walls via forced convection. The temperature gradients caused in the heat exchange medium, for example, in the water, in boiler 11 result in natural convection of the water, which promotes mixing of the boiler water.

[0106] Spring turbulators 36 and spiral or ribbon turbulators 37 are arranged in the boiler tubes 32 to improve the efficiency of the heat exchanger device 4. These turbulators 36, 37 are shaped metal parts located in the boiler tubes 32 of the heat exchanger 3 and can be moved back and forth in the boiler tubes 32 to clean combustion residues in these tubes 32.

[0107] The outlet of the boiler tubes 32 opens into the turning chamber 35 via the turning chamber inlet 34. The turning chamber 35 is sealed from the combustion chamber 24 in such a way that no flue gas from the turning chamber 35 can flow directly back into the combustion chamber 24. However, a common transport path is nevertheless provided for the combustion residues that can accumulate in the entire flow area of ​​the boiler 11. If the filter device 4 is not provided, the flue gas is discharged upwards again in the boiler 11. The other case of the optional filter device 4 is described in the Fig. 2 and 3. After passing through the turning chamber 35, the flue gas is fed upwards again into the filter device 4 (see arrows S5), which in this case is, by way of example, an electrostatic filter device 4. Flow baffles can be provided at the inlet 44 of the filter device 4 to even out the flow of flue gas into the filter.

[0108] Electrostatic dust filters, also known as electrostatic precipitators in science, are devices for separating particles from gases based on the electrostatic principle. These filter devices are used primarily for the electrical purification of exhaust gases. In electrostatic precipitators, dust particles are electrically charged by a corona discharge from a discharge electrode and drawn to the oppositely charged electrode (precipitation electrode). The corona discharge takes place on a suitable, charged high-voltage electrode (also called a discharge electrode) inside the electrostatic precipitator.

[0109] The (spray) electrode 45 is designed with protruding tips and possibly with sharp edges because the density of the field lines and thus also the electric field strength is greatest there and thus the corona discharge is favored.

[0110] The opposite electrode (counter electrode or collecting electrode) usually consists of a grounded exhaust pipe section or a cage-like arrangement that is mounted or provided around the electrode.

[0111] The separation efficiency of an electrostatic precipitator depends in particular on the residence time of the exhaust gases in the filter system and the voltage between the spray and separation electrodes. The necessary rectified high voltage is provided by the voltage generation unit of the control device 100 (not shown). The electrode 45 consists at least largely of high-quality spring steel or chromium steel and is held by an electrode holder 43 via an insulator 46, i.e., an electrode insulation 46.

[0112] The holder 43 for the electrode 45 and, in particular, the insulator 46 are exposed to dust and contamination, as they are located on or in the flue gas-carrying interior. Therefore, special measures are required to prevent unwanted leakage currents. The cage 48 can be moved by the cleaning system 7 to also clean the filter 4. Such movement can be accompanied by the movement of the turbulators 36, 37.

[0113] As in Fig. 2 As shown, an optimized rod-shaped electrode 45 is held approximately centrally in an approximately chimney-shaped or elongated interior of the filter device 4.

[0114] This (spray) electrode 45 hangs downwards in the interior of the filter device 4 in a manner capable of oscillating or pendulum motion. The electrode 45 can, for example, oscillate back and forth transversely to the longitudinal axis of the electrode 45.

[0115] A cage 48 serves simultaneously as a counter electrode and as a cleaning mechanism for the filter device 4. The cage 48 is connected to the ground or earth potential. The flue gas or exhaust gas flowing in the filter device 4 (see arrows S6) is filtered by the prevailing potential difference, as explained above. The arrows S6 roughly indicate the area in which a flow velocity of the flue gas is to be determined as a reference. In this area inside the tubular filter device 4, the flow velocity is in a range of 0.5 to 3 m / s, preferably in a range of 1 to 2 m / s when the biomass heating system is operated at full load. Full load operation is understood to mean operation of the biomass heating system in which at least 90% of the nominal output [kW] (for which the boiler 11 is designed and regularly certified) is delivered. Partial load operation is understood to mean operation of the boiler 11 orof the biomass heating system 1 below these 90%.

[0116] The indicator line WT3 indicates an exemplary cross-sectional line through the filter device 4, in which the flow is as homogeneous as possible or roughly evenly distributed across the cross-section of the boiler tubes 32 (due, among other things, to flow baffles at the inlet of the filter device 4 and the geometry of the turning chamber 35). A uniform flow through the filter device 3 or the last boiler pass minimizes streak formation and thus also optimizes the separation efficiency of the filter device 4 and the heat transfer in the biomass heating system 1.

[0117] When cleaning the filter device 4, the electrode 45 is de-energized. The cage 48 preferably has an octagonal, regular cross-sectional profile, as can be seen, for example, in the view of the Fig. 13 The cage 48 can preferably be laser cut during manufacture.

[0118] After leaving the heat exchanger 3 (from its outlet), the flue gas flows through the turning chamber 34 into the inlet 44 of the filter device 4.

[0119] The filter device 4 is advantageously fully integrated into the boiler 11, whereby the wall surface facing the heat exchanger 3 and flushed with the heat exchange medium is also used for heat exchange from the direction of the filter device 4, thus further improving the efficiency of the system 1. Thus, at least a portion of the wall of the filter device 4 can be flushed with the heat exchange medium, whereby at least a portion of this wall is cooled with boiler water.

[0120] At the filter outlet 47, the purified exhaust gas flows out of the filter device 4, as indicated by the arrows S7. After exiting the filter, a portion of the exhaust gas is recirculated to the primary combustion zone 26 via the recirculation device 5. This will also be explained in more detail later. This exhaust gas or flue gas intended for recirculation can also be referred to as "recirculation" or "recirculation gas" for short. The remaining portion of the exhaust gas is discharged from the boiler 11 via the exhaust outlet 41.

[0121] The arrow S8 indicates a flue gas flow or swirl, in which flue gas does not exit directly from the filter 4, but forms a reversal or vortex flow in a dead volume of the filter 4 (which is located behind the outlet 47 in terms of flow, thus not being located in the main flow S6, S7 through the filter 4), and in particular can flow past the insulator 46. In this case, soot and ash can deposit on the insulator. Thus, in addition to non-mineral combustion residues, carbonaceous combustion residues can also deposit on the insulator, impairing its function. Further details will be provided with reference to the Fig. 9 explained.

[0122] An ash removal system 7 is located in the lower part of the boiler 11. The ash separated and falling out of the combustion chamber 24, the boiler tubes 32, and the filter device 4, for example, is conveyed out of the boiler 11 via an ash removal screw 71.

[0123] In Fig. 2 and Fig. 3 Further sensors are shown that are at least communicatively connected to the control device 100. The sensors record (physical and / or chemical) variables of the biomass heating system 1.

[0124] An exhaust gas temperature sensor 111 is provided downstream of the outlet of the heat exchanger 3. This sensor measures the temperature of the exhaust gas or flue gas after it has flowed through the heat exchanger 3. This sensor 111 can preferably be used to control the temperature of the flue gas flowing into the filter 4 for filtration.

[0125] A conventional temperature sensor or a PT-100 or PT-1000 sensor can be used as the exhaust gas temperature sensor 111. This sensor is located in the wall of the exhaust duct or extends into the exhaust duct. The exhaust gas temperature can be determined in degrees Celsius using the exhaust gas temperature sensor 111.

[0126] The exhaust gas temperature sensor 111 can, for example, be provided before or after the optional filter device 4. Likewise, for example, the exhaust gas sensor 111 can be provided before the exhaust gas outlet 41. Furthermore, more than one exhaust gas temperature sensor 111 can be provided to increase measurement accuracy or to provide metrological redundancies. For example, one exhaust gas temperature sensor 111 can be provided directly after the outlet of the heat exchanger 3, and another exhaust gas temperature sensor 111 can be provided after the filter device 4.

[0127] Furthermore, at least one lambda probe 112 is provided. It serves as a sensor for the lambda control of the biomass heating system 1. The lambda probe detects at least one physical / chemical variable that enables control of the combustion process in the boiler 11. The lambda probe 112 enables an O2 content measurement or an oxygen content measurement of the exhaust gas or flue gas downstream of the combustion chamber 24.

[0128] A lambda sensor can typically compare the residual oxygen content in the exhaust gas with the oxygen content of a reference, usually the current atmospheric or ambient air. From this, the combustion air ratio λ (combustion air to fuel ratio) can be determined and adjusted. Two measurement principles can be used: voltage of a solid-state electrolyte (Nernst probe) and resistance change of a ceramic (resistance probe).

[0129] In the present application in the biomass heating system, the lambda probe 112 can measure the oxygen content of the exhaust gas (for example, in vol%), and thus an optimal mixture can be controlled at the boiler 11, preferably by means of an AI model, in order to prevent an excess of cooling supply air or carbon monoxide (with unused residual calorific value) resulting from a lack of oxygen, which would "rob" the heating system of energy.

[0130] For at least one lambda sensor 112 are in Fig. 2 Two possible installation positions are proposed. One is located adjacent to the inlet 33 of heat exchanger 3 (see Fig. 2 , top, middle) and the other is located in the exhaust gas outlet 41 and thus after the outlet of the heat exchanger 3 (cf. Fig. 2 , top right). In general, the lambda probe 112 can be provided at any position in the exhaust gas duct of the boiler 11, as long as it can measure the exhaust gas or flue gas.

[0131] However, the greater the distance between the flame in the combustion chamber 24 and the lambda probe 112, the more difficult it becomes to control the boiler 11 due to the resulting dead time. Therefore, it is preferable to mount the probe as close as possible to the combustion chamber 24. Using the signal from the lambda probe 112, the control device 100 can, for example, regulate the supply of primary air to the combustion chamber and the fuel supply quantity.

[0132] Furthermore, an (optional) vacuum sensor 113 or pressure difference sensor 113 is provided. This vacuum sensor 113 measures the (negative) pressure in the combustion chamber 24, for example, in the unit [mPas], or the differential pressure between the combustion chamber 24 and the ambient air pressure. The primary air (and optionally the secondary air) is drawn into the combustion chamber 24 for combustion via the negative pressure.

[0133] Furthermore, an (optional) return (or flow) temperature sensor 114 or a heating water temperature sensor 114 is provided. This is provided, for example, in the return or flow of a conventional water circulation system 14 and detects the temperature of the heating water in the water circuit in which the boiler 11 is provided. The heat exchange medium 38 is preferably the heating water.

[0134] Thus, the temperature of the heat exchange medium 38 in or outside the boiler can be detected with the previously explained boiler temperature sensor 115 or with the heating water temperature sensor 114 (preferably a return temperature sensor 114).

[0135] A fuel bed height sensor 116 (shown in the figures without an exemplary mechanism) detects the height of the fuel bed 28 above the grate and thus a quantity of fuel, for example wood chips, on the grate 25. An example of such a sensor in a mechanical design is described in EP 3 789 670 B1 with regard to its Fig. 17 and 18 described, reference is made to it in advance. Alternatively, the fuel bed height sensor 116 can be provided, for example, as an ultrasonic sensor.

[0136] Furthermore, a combustion chamber temperature sensor 117 is provided. This detects a temperature of the combustion chamber 24, for example, in degrees Celsius. The combustion chamber temperature sensor 117 can be provided at the outlet of the combustion chamber 24 or also in the combustion chamber 24 or on the combustion chamber wall. This combustion chamber temperature sensor 117 can detect the temperature in the combustion chamber 24, for example, as a known PT100 sensor or as an infrared measuring device. More than one combustion chamber temperature sensor 117 can also be provided, whereby, for example, an average temperature of this plurality of combustion chamber temperature sensors 117 can be determined or calculated as the combustion chamber temperature.

[0137] It should be noted that the locations of the sensors of the Fig. 2 and 3 may also deviate from the locations shown, as deemed appropriate by the expert. For example, the combustion chamber temperature may also be recorded at a different location.

[0138] The combustion chamber 24 and the geometry of the filter device 4 and the upstream reversing chamber 35 of this embodiment were calculated using CFD simulations. Furthermore, practical experiments were conducted to confirm the CFD simulations. The starting point for the considerations were calculations for a 100 kW boiler, but a power range of 20 to 500 kW was considered.

[0139] A CFD simulation (CFD = Computational Fluid Dynamics) is the spatially and temporally resolved simulation of flow and heat conduction processes. The flow processes can be laminar and / or turbulent, accompanied by chemical reactions, or the system can be multiphase. CFD simulations are therefore well suited as a design and optimization tool. In the present invention, CFD simulations were used to optimize the fluidic parameters in such a way that the aforementioned objects of the invention are achieved. In particular, the mechanical design and dimensioning of the boiler 11, the combustion chamber 24, the secondary air nozzles 291, and the combustion chamber nozzle 203 were largely defined by the CFD simulation and also by associated practical experiments. The simulation results are based on a flow simulation that takes heat transfer into account. (combustion chamber)

[0140] The following explanations regarding the design of the combustion chamber shape describe, by way of example, where the grate according to the invention can be used. The combustion chamber shape or geometry should achieve the best possible turbulent mixing and homogenization of the flow across the cross-section of the flue gas duct, minimize the combustion volume, reduce excess air and the recirculation ratio (efficiency, operating costs), reduce CO and NOx emissions, reduce temperature peaks (fouling and slagging), and reduce flue gas velocity peaks (material stress and erosion).

[0141] The Fig. 4 which is a partial view of the Fig. 2 is, and the Fig. 5 , which is a sectional view through the boiler 11 along the vertical section line A2, represents a combustion chamber geometry that meets the above-mentioned requirements for biomass heating systems over a wide power range of, for example, 20 to 500 kW.

[0142] The Figuren 3 and 4 The dimensions specified and determined through CFD calculations and practical experiments are as follows: BK 1 = 172 mm + − 40 mm , vorzugsweise + − 17 mm ; BK 2 = 300 mm + − 50 mm , vorzugsweise + − 30 mm ; BK 3 = 430 mm + − 80 mm , vorzugsweise + − 40 mm ; BK 4 = 538 mm + − 80 mm , vorzugsweise + − 50 mm ; BK 5 = BK 3 − BK 2 / 2 = bspw . 65 mm + − 30 mm , vorzugsweise + − 20 mm ; BK 6 = 307 mm + − 50 mm , vorzugsweise + − 20 mm ; BK 7 = 82 mm + − 20 mm , vorzugsweise + − 20 mm ; BK 8 = 379 mm + − 40 mm , vorzugsweise + − 20 mm ; BK 9 = 470 mm + − 50 mm , vorzugsweise + − 20 mm ; BK 10 = 232 mm + − 40 mm , vorzugsweise + − 20 mm ; BK 11 = 380 mm + − 60 mm , vorzugsweise + − 30 mm ; BK 12 = 460 mm + − 80 mm , vorzugsweise + − 30 mm .

[0143] However, these dimensions are merely exemplary and serve to clarify the present technical teaching.

[0144] Using these values, both the geometries of the primary combustion zone 26 and the secondary combustion zone 27 of the combustion chamber 24 can be optimized for a 100 kW boiler 11. The specified size ranges are ranges with which the requirements are (approximately) met, as are the specified exact values.

[0145] In this case, a chamber geometry of the primary combustion zone 26 of the combustion chamber 24 (or an internal volume of the primary combustion zone 26 of the combustion chamber 24) can preferably be defined based on the following basic parameters: A volume with an oval horizontal base area with the dimensions of 380 mm +- 60 mm (preferably +-30 mm) x 320 mm +- 60 mm (preferably +-30 mm), and a height of 538 mm +- 80 mm (preferably +- 50 mm).

[0146] As a further development of this, the above-defined volume can have an upper opening in the form of a combustion chamber nozzle 203, which opens into the secondary combustion zone 27 of the combustion chamber 24, which has a combustion chamber slope 202 projecting into the secondary combustion zone 27, which preferably contains the heat exchange medium 38. The combustion chamber slope 202 reduces the cross-section of the secondary combustion zone 27 by at least 5%, preferably by at least 15%, and even more preferably by at least 19%.

[0147] The combustion chamber slope 202 serves to homogenize the flow S3 in the direction of the heat exchanger 3 and thus the flow through the boiler tubes 32.

[0148] In the prior art, combustion chambers with rectangular or polygonal combustion chamber and nozzle are common, but the irregular shape of the combustion chamber and the nozzle represents a further obstacle to uniform air distribution and good mixing of air and fuel, as has been recognized in the present case.

[0149] Therefore, the combustion chamber 24 is provided without dead corners or dead edges.

[0150] In this case, it was recognized that the geometry of the combustion chamber (and the entire flow pattern in the boiler) plays a key role in the considerations for optimizing biomass heating system 1. Therefore, the oval or round basic geometry described here without dead corners was chosen (in contrast to the usual rectangular or polygonal shapes). Furthermore, this basic geometry of the combustion chamber and its structure were also optimized with the dimensions / dimension ranges specified above. These dimensions / dimension ranges were selected in such a way that, in particular, different fuels (wood chips and pellets) of varying quality (for example, with different water contents) can be burned with very high efficiency. This was the result of practical tests and CFD simulations.

[0151] In particular, the primary combustion zone 26 of the combustion chamber 24 may comprise a volume which preferably has an oval or approximately circular horizontal cross-section in the outer circumference (such a cross-section is shown in Fig. 2 (for example, marked A1). This horizontal cross-section can also preferably represent the base area of ​​the primary combustion zone 26 of the combustion chamber 24. Over the height indicated by the double arrow BK4, the combustion chamber 24 can have an approximately constant cross-section. In this respect, the primary combustion zone 24 can have an approximately oval-cylindrical volume. Preferably, the side walls and the base area (the grate) of the primary combustion zone 26 can be perpendicular to one another.

[0152] The term "approximately" is used above because individual notches, design-related deviations, or small asymmetries may naturally be present, for example, at the transitions between the individual combustion chamber bricks 29. However, these minor deviations play only a minor role in terms of flow.

[0153] The horizontal cross-section of the combustion chamber 24 and in particular of the primary combustion zone 26 of the combustion chamber 24 can also preferably be regular. Furthermore, the horizontal cross-section of the combustion chamber 24 and in particular of the primary combustion zone 26 of the combustion chamber 24 can preferably be a regular (and / or symmetrical) ellipse.

[0154] In addition, the horizontal cross-section (the outer circumference) of the primary combustion zone 26 can be designed to be constant over a predetermined height, for example 20 cm.

[0155] This provides an oval-cylindrical primary combustion zone 26 of the combustion chamber 24, which, according to CFD calculations, enables a significantly more uniform and better air distribution in the combustion chamber 24 than in rectangular combustion chambers of the prior art. The absence of dead spaces also prevents zones in the combustion chamber with poor airflow, which increases efficiency and reduces slag formation.

[0156] Likewise, the nozzle 203 between the primary combustion zone 26 and the secondary combustion zone 27 is designed as an oval or approximately circular constriction to optimize the flow conditions. The previously described swirl of the flow in the primary combustion zone 26 leads to a helical, upward flow path, whereby a similarly oval or approximately circular nozzle favors this flow path and does not disrupt the conventional rectangular nozzles. This optimized nozzle 203 focuses the upward-flowing air and ensures a uniform inflow into the secondary combustion zone 27. This improves the combustion process and increases efficiency.

[0157] In addition, the flow pattern in the secondary combustion zone 27 and from the secondary combustion zone 27 to the boiler tubes 32 is optimized, as explained in more detail below.

[0158] The combustion chamber slope 202 of the Fig. 4 , which without reference symbols also in the Fig. 2 and 3 can be seen and at which the combustion chamber 25 (or its cross-section) tapers at least approximately linearly from bottom to top, ensures, according to CFD calculations, a uniformity of the flue gas flow in the direction of the heat exchange device 4, which can improve its efficiency. The horizontal cross-sectional area of ​​the combustion chamber 25 tapers from the beginning to the end of the combustion chamber slope 202, preferably by at least 5%. The combustion chamber slope 202 is provided on the side of the combustion chamber 25 towards the heat exchange device 4 and is rounded at the point of maximum taper. In the prior art, parallel or straight combustion chamber walls without a taper are common (so as not to impede the flue gas flow).

[0159] The flue gas flow is diverted upstream of the tube bundle heat exchanger in such a way that uneven flow through the tubes is avoided as best as possible, thus keeping temperature peaks in individual boiler tubes 32 low. As a result, the efficiency of the heat exchange device 4 is improved.

[0160] In detail, the gaseous volume flow of the flue gas is guided through the inclined combustion chamber wall at a uniform speed (even in the case of different combustion states) to the heat exchanger tubes or the boiler tubes 32. This creates a uniform heat distribution of the individual heat exchanger surfaces of the boiler tubes 32. The exhaust gas temperature is thus reduced and the efficiency increased. The flow distribution is particularly at the Fig. 3 The indicator line WT1 shown is significantly more uniform than in the prior art. The line WT1 represents an inlet surface for the heat exchanger 3. The indicator line WT3 indicates an exemplary cross-sectional line through the filter device 4, in which the flow is arranged as homogeneously as possible (among other things due to flow baffles at the inlet of the filter device 4 and due to the geometry of the turning chamber 35).

[0161] Furthermore, an ignition device 201 is provided in the lower part of the combustion chamber 25 on the fuel bed 28. This can cause an initial ignition or a re-ignition of the fuel. The ignition device 201 can be a glow igniter. The ignition device is advantageously arranged in a stationary position and horizontally offset laterally from the location where the fuel is poured.

[0162] Furthermore, a lambda probe (not shown) can be optionally installed downstream of the flue gas outlet (i.e., after S7) from the filter system. The lambda probe allows a control system (not shown) to detect the respective calorific value. The lambda probe can thus ensure the ideal mixing ratio between the fuels and the oxygen supply. Despite varying fuel qualities, high efficiency and higher efficiency can be achieved.

[0163] The Fig. 5 The fuel bed 28 shown shows an exemplary fuel distribution due to the supply of fuel from the right side of the Fig. 5 This fuel bed 28 is supplied from below with a flue gas / fresh air mixture provided by the recirculation device 5. This flue gas / fresh air mixture is advantageously pre-tempered and has the ideal quantity (mass flow) and the ideal mixing ratio, as regulated by a system control system (not shown in detail) based on various sensor-detected measured values ​​and associated air valves 52.

[0164] Further on in the Fig. 4 and 5A combustion chamber nozzle 203 is shown, which separates the primary combustion zone 26 from the secondary combustion zone 27 and accelerates and focuses the flue gas flow. This improves the flue gas flow's mixing and allows it to burn more efficiently in the secondary combustion zone 27. The area ratio of the combustion chamber nozzle 203 ranges from 25% to 45%, but is preferably 30% to 40%, and is ideally 36% ± 1% (ratio of the measured inlet area to the measured outlet area of ​​the nozzle 203).

[0165] Thus, the above information on the combustion chamber geometry of the primary combustion zone 26 together with the geometry of the nozzle 203 represents an advantageous development of the present disclosure. (Combustion chamber stones and view of the rotating grate)

[0166] The Fig. 6 shows a three-dimensional sectional view (obliquely from above) of the primary combustion zone 26 of the combustion chamber 24 with the rotating grate 25, and in particular of the special design of the combustion chamber stones 29. The Fig. 7 shows accordingly to Fig. 6 an exploded view of the combustion chamber bricks 29. The views of the Fig. 6 and 7 can preferably be used with the dimensions listed above. Fig. 4 and 5 However, this is not necessarily the case.

[0167] The chamber wall of the primary combustion zone 26 of the combustion chamber 24 is provided with a plurality of combustion chamber bricks 29 in a modular design, which, among other things, facilitates production and maintenance. Maintenance is facilitated in particular by the possibility of removing individual combustion chamber bricks 29.

[0168] On the bearing surfaces 260 of the combustion chamber bricks 29, form-fitting grooves 261 and projections 262 (in Fig. 6 To avoid redundancies, only a few of these are shown in the figures as examples) to create a mechanical and largely airtight connection, in turn preventing the ingress of disruptive external air. Preferably, two at least largely symmetrical combustion chamber bricks (with the possible exception of the openings for the recirculation gas) each form a complete ring. Furthermore, preferably, three rings are stacked one on top of the other to form the oval-cylindrical or, alternatively, at least approximately circular (the latter is not shown) primary combustion zone 26 of the combustion chamber 24.

[0169] Three additional combustion chamber blocks 29 are provided as the upper closure, with the annular nozzle 203 being supported by two retaining blocks 264, which are placed in a form-fitting manner on the upper ring 263. Grooves 261 are provided on all support surfaces 260 either for matching projections 262 and / or for inserting suitable sealing material.

[0170] The support stones 264, which are preferably symmetrical, can preferably have an inwardly inclined slope 265 in order to simplify sweeping of fly ash onto the rotating grate 25.

[0171] The lower ring 263 of the combustion chamber stones 29 rests on a base plate 251 of the rotating grate 25. Ash accumulates on the inner edge between this lower ring 263 of the combustion chamber stones 29, thus advantageously sealing this transition during operation of the biomass heating system 1.

[0172] The (optional) openings for the recirculation nozzles 291 are provided in the middle ring of the combustion chamber stones 29.

[0173] In this case, three rings of combustion chamber bricks 29 are provided, as this represents the most efficient method of manufacture and maintenance. Alternatively, two, four, or five (2, 4, or 5) such rings may be provided.

[0174] The combustion chamber bricks 29 are preferably made of high-temperature silicon carbide, which makes them very wear-resistant.

[0175] The combustion chamber bricks 29 are provided as shaped bricks. The combustion chamber bricks 29 are shaped such that the interior volume of the primary combustion zone 26 of the combustion chamber 24 has an oval horizontal cross-section. This ergonomic design avoids dead spots or dead spaces, which are typically not optimally traversed by the primary air, resulting in suboptimal combustion of the fuel present there. Due to the shape of the combustion chamber bricks 29, the flow of primary air and, consequently, the combustion efficiency are improved.

[0176] The oval horizontal cross-section of the primary combustion zone 26 of the combustion chamber 24 is preferably a point-symmetric and / or regular oval with the smallest inner diameter BK3 and the largest inner diameter BK11. These dimensions were the result of the optimization of the primary combustion zone 26 of the combustion chamber 24 using CFD simulation and practical tests. (rotating grate)

[0177] Fig. 8 shows a top view of the rotating grate 25 from the viewpoint of the section line A1 of the Fig. 2 to illustrate various possible operating states of the rotating grate 25.

[0178] The supervision of the Fig. 8 may preferably be designed with the dimensions listed above. However, this is not mandatory.

[0179] The rotating grate 25 has the base plate 251 as its base element. A transition element 255 is provided in a roughly oval-shaped opening in the base plate 251. This transition element bridges the gap between a first rotating grate element 252, a second rotating grate element 253, and a third rotating grate element 254, which are rotatably mounted. Thus, the rotating grate 25 is provided as a rotating grate with three individual elements, i.e., it can also be referred to as a triple rotating grate. Air holes for the flow of primary air are provided in the rotating grate elements 252, 253, and 254.

[0180] The rotating grate elements 252, 253, and 254 are flat and heat-resistant metal plates, for example, made of a cast metal, which have an at least largely flat surface on their upper side and are connected to the bearing axles 81 on their underside, for example, via intermediate support elements. Viewed from above, the rotating grate elements 252, 253, and 254 have curved and complementary sides or contours.

[0181] In particular, the rotating grate elements 252, 253, 254 can have complementary and curved sides, wherein the second rotating grate element 253 preferably has concave sides toward the adjacent first and third rotating grate elements 252, 254, and preferably the first and third rotating grate elements 252, 254 each have a convex side toward the second rotating grate element 253. This improves the crushing function of the rotating grate elements, as the length of the fracture is increased and the crushing forces (similar to scissors) are applied more precisely.

[0182] The rotating grate elements 252, 253, and 254 (as well as their enclosure in the form of the transition element 255) have, when viewed together, an approximately oval outer shape, which in turn avoids dead spots or dead spaces in which suboptimal combustion could occur or ash could accumulate undesirably. The optimal dimensions of this outer shape of the rotating grate elements 252, 253, and 254 are shown in Fig. 8 denoted by the double arrows DR1 and DR2. Preferably, but not exclusively, DR1 and DR2 are defined as follows: DR 1 = 288 mm + − 40 mm , bevorzugt + − 20 mm DR 2 = 350 mm + − 60 mm , bevorzugt + − 20 mm

[0183] These values ​​have been found to be optimal values ​​(ranges) in the CFD simulations and the subsequent practical test. These dimensions correspond to those of the Fig. 4 and 5These dimensions are particularly advantageous for the combustion of different fuels, i.e. wood chips and pellets (hybrid combustion) in a power range of 20 to 200 kW.

[0184] The rotating grate 25 has an oval combustion surface 258, which is more favorable for fuel distribution, air flow through the fuel, and fuel combustion than a conventional rectangular combustion surface. The combustion surface 258 is essentially formed by the surfaces of the rotating grate elements 252, 253, and 254 (in the horizontal state). The combustion surface is thus the upward-facing surface of the rotating grate elements 252, 253, and 254. This oval combustion surface advantageously corresponds to the fuel support surface when the fuel is applied or pushed laterally onto the rotating grate 25 (cf. arrow E of the Fig. 9 , 10 and 11). In particular, the fuel supply can be effected from a direction parallel to a longer central axis (main axis) of the oval combustion surface of the rotating grate 25.

[0185] The first rotating grate element 252 and the third rotating grate element 254 can preferably be identical in their combustion surface 258. Furthermore, the first rotating grate element 252 and the third rotating grate element 254 can be identical or structurally identical to one another. This is the case, for example, in Fig. 9 can be seen, wherein the first rotating grate element 252 and the third rotating grate element 254 have the same shape.

[0186] Furthermore, the second rotating grate element 253 is arranged between the first rotating grate element 252 and the third rotating grate element 254.

[0187] Preferably, the rotating grate 25 is provided with an approximately point-symmetrical oval combustion surface 258.

[0188] Likewise, the rotating grate 25 can form an approximately elliptical or oval combustion surface 258, where DR2 is the dimension of its major axis and DR1 is the dimension of its minor axis.

[0189] Furthermore, the rotating grate 25 can have an approximately oval combustion surface 258 which is axially symmetrical with respect to a central axis of the combustion surface 258.

[0190] Furthermore, the rotating grate 25 can have an approximately circular combustion surface 258, although this results in minor disadvantages in the fuel supply and distribution.

[0191] Furthermore, two motors or drives 231 of the rotating mechanism 23 are provided, with which the rotating grate elements 252, 253 and 254 can be rotated accordingly. Rotation angle sensors 259 (shown here as separate units) are provided, preferably on the rotation axes 81, for detecting the angle of rotation or the rotational position of the rotation axes 81. The position of the rotating grate elements 252, 253, 254, for example, in relation to the horizontal or their rest position, can be determined using the rotation angle sensors 259. Further details on the special function and advantages of the present rotating grate 25 will be explained later with reference to the Figuren 9 , 10 and 11 described.

[0192] Pellet heating systems in particular can experience increased failures due to slag formation in the combustion chamber 24, particularly on the rotating grate 25. Slag is always formed during a combustion process when temperatures in the embers reach temperatures above the ash melting point. The ash then softens, sticks together, and upon cooling, forms solid, dark-colored slag. This process, also known as sintering, is undesirable in the biomass heating system 1, as the accumulation of slag in the combustion chamber 24 can lead to a malfunction: it shuts down. The combustion chamber 24 usually has to be opened, and the slag has to be removed.

[0193] The ash melting point depends largely on the fuel used. Spruce wood, for example, has an ash melting point of approximately 1200 °C. However, the ash melting point of a fuel can also fluctuate significantly. Depending on the quantity and composition of the minerals contained in the wood, the behavior of the ash during the combustion process changes.

[0194] Another factor that can influence slag formation is the transport and storage of wood pellets or wood chips. These should be as undamaged as possible when entering the combustion chamber 24. If the wood pellets are already crumbled when they enter the combustion process, this increases the density of the ember bed. This results in greater slag formation. Transport from the storage room to the combustion chamber 24 is particularly important here. Long distances, as well as bends and angles, lead to damage to the wood pellets. One problem with this is that slag formation cannot be completely avoided due to the multitude of influencing factors described above.

[0195] Another factor concerns the management of the combustion process. Until now, the goal was to keep temperatures relatively high in order to achieve the highest possible burnout and low emissions. By optimizing the combustion chamber geometry and the geometry of combustion zone 258 of rotating grate 25, it is possible to keep the combustion temperature lower, thus reducing slag formation.

[0196] In addition, the resulting slag (and also the ash) can be advantageously removed due to the special design and functionality of the present rotating grate 25. This will now be explained with reference to the Figuren 9 , 10 and 11 explained in more detail. (Cleaning the rotating grate)

[0197] The Figuren 9 , 10 and 11show a three-dimensional view of the rotating grate 25 with the base plate 251, the first rotating grate element 252, the second rotating grate element 253 and the third rotating grate element 254. The views of the Fig. 9 , 10 and 11 may preferably correspond to the dimensions listed above. However, this is not mandatory.

[0198] This view shows the rotating grate 25 as a free-standing insert part with the rotating grate mechanism 23 and drive(s) 231. The rotating grate 25 is mechanically designed in such a way that it can be individually prefabricated in a modular system and inserted and installed as an insert part into a provided elongated opening in the boiler 11. This also facilitates the maintenance of this wear-prone part. The rotating grate 25 can therefore preferably be designed in a modular manner, whereby it can be quickly and efficiently removed and reinserted as a complete part with the rotating grate mechanism 23 and drive 231. The modularized rotating grate 25 can thus also be assembled and disassembled using quick-release fasteners. In contrast, the rotating grates of the prior art are usually permanently mounted and thus difficult to maintain or assemble.

[0199] The drive 231 can have two separately controllable electric motors. These are preferably provided on the side of the rotating grate mechanism 23. The electric motors can have reduction gears. Alternatively, only a single drive 231 can be provided.

[0200] Furthermore, at least one end stop or one limit switch can be provided, which detects at least one end stop for the end position of the rotating grate elements 252, 253 and 254.

[0201] Likewise, at least one rotational position sensor or rotational angle sensor 259 or a position sensor 259 can be provided, which can detect a (rotational) position of the rotational axis 81 and thus of the rotating grate elements 252, 253, 254. The rotational position sensor 259 can, for example, be a known magnetic protractor or rotary encoder that outputs an absolute angle. These sensors have an axis whose rotation is detected, whereby, for example, a digital signal or an analog signal (for example, a linear voltage) is output depending on the detected angle. The rotational position sensor 259 can directly or indirectly detect the rotation or rotational position of the axis 81. The rotational position sensor can, for example, be mounted with its axis directly on the axis 81 in order to detect its rotation. Alternatively, the rotational position sensor can also be indirectly connected to the axis 81 via a mechanism (for example, gears).

[0202] The individual components of the rotating grate mechanism 23 are designed to be interchangeable. For example, the gears are designed to be plugged on. This facilitates maintenance and also allows for a change of the mechanism during assembly, if necessary.

[0203] The aforementioned openings 256 are provided in the rotating grate elements 252, 253, and 254 of the rotating grate 25. The rotating grate elements 252, 253, and 254 can each be rotated by at least 90 degrees, preferably at least 120 degrees, and even more preferably 170 degrees, about the respective bearing or rotation axis 81 via their respective bearing axes 81, which are driven by the drive 231, in this case the two motors 231, via the rotating mechanism 23. The maximum angle of rotation can be 180 degrees or slightly less than 180 degrees, as permitted by the grate lips 257. Free rotation by 360 degrees is also conceivable if no rotation-limiting grate lips are provided.The rotating mechanism 23 is configured such that the third rotating grate element 254 can be rotated individually and independently of the first rotating grate element 252 and the second rotating grate element 243, and such that the first rotating grate element 252 and the second rotating grate element 243 can be rotated jointly and independently of the third rotating grate element 254. The rotating mechanism 23 can be provided accordingly, for example, by means of running wheels, toothed or drive belts, and / or gears.

[0204] The rotating grate elements 252, 253, and 254 can preferably be manufactured as cast iron grates with laser cutting to ensure precise dimensional stability. This is particularly important to define the air flow through the fuel bed 28 as precisely as possible and to avoid disruptive air currents, such as air streaks at the edges of the rotating grate elements 252, 253, and 254.

[0205] The openings 256 in the rotating grate elements 252, 253 and 254 are designed such that they are small enough for the usual pellet material and / or the usual wood chips to not fall through, and that they are large enough that the fuel can be well supplied with air.

[0206] Fig. 9 now shows the rotating grate 25 in a closed position or in a working position (ie a first state), with all rotating grate elements 252, 253 and 254 aligned horizontally or closed. This is the position in normal operation. Due to the uniform arrangement of the plurality of openings 256, a uniform flow through the fuel bed 28 (this is in Fig. 9 not shown) on the rotating grate 25. In this way, the optimal combustion condition can be achieved. The fuel is applied to the rotating grate 25 from the direction of arrow E; in this way, the fuel is fed from the right side of the Fig. 9 pushed up onto the rotating grate 25.

[0207] During operation, ash and / or slag accumulate on the rotating grate 25, and in particular on the rotating grate elements 252, 253, and 254. The rotating grate 25 can be efficiently cleaned with the present rotating grate 25.

[0208] Two rotational position sensors 259 are also indicated, which can detect the rotational position of the bearing axes 81. These rotational position sensors 259 can be, for example, magnetic-inductive sensors. This serves to control the rotational position of the three rotating grate elements 252, 253, 254.

[0209] Fig. 10 shows the rotating grate in the state of partial cleaning of the rotating grate 25 in ember maintenance mode (i.e., in a second state). For this purpose, only the third rotating grate element 254 is rotated (see arrow D1). Because only one of the three rotating grate elements is rotated, the embers are maintained on the first and second rotating grate elements 252, 253, while at the same time the ash and slag can fall downwards out of the combustion chamber 24. As a result, no external ignition is required to restart operation (this saves up to 90% ignition energy). A further consequence is reduced wear on the ignition device (e.g., an ignition rod) and electricity savings. Furthermore, ash cleaning can advantageously take place during operation of the biomass heating system 1.

[0210] Fig. 10 also shows a state of ember maintenance during a (often sufficient) partial cleaning. This allows for the advantageous operation of System 1 to be carried out more continuously, eliminating the need for a lengthy, complete ignition, which can take several tens of minutes, unlike the usual full cleaning of a conventional grate.

[0211] In addition, potential slag is broken up at the two outer edges of the third rotating grate element 254 during its rotation. Due to the curved outer edges of the third rotating grate element 254, not only does the shearing occur over a greater overall length than with conventional rectangular elements of the prior art, but also with an uneven distribution of movement with respect to the outer edge (greater movement occurs in the center than at the lower and upper edges). This significantly enhances the crushing function of the rotating grate 25.

[0212] In Fig. 10 Grate lips 257 of the second rotating grate element 253 (on both sides) are visible. These grate lips 257 are configured such that the first rotating grate element 252 and the third rotating grate element 254, when closed, rest on the upper side of the grate lips 257, thus ensuring that the rotating grate elements 252, 253, and 254 are provided with no gaps between them and thus form a seal. This prevents air streams and unwanted primary air currents through the ember bed. This advantageously improves combustion efficiency.

[0213] Fig. 11 shows the rotating grate 25 in the state of universal cleaning or in an open state (i.e. a third state), which is preferably carried out during a plant shutdown. In this case, all three rotating grate elements 252, 253 and 254 are rotated, whereby the first and second rotating grate elements 252, 253 are preferably rotated in the opposite direction to the third rotating grate element 254 (cf. arrows D2). This achieves, on the one hand, a complete emptying of the rotating grate 25, and on the other hand, the slag is now broken up at four odd outer edges. In other words, an advantageous quadruple crusher function is realized. The above-mentioned with regard to Fig. 9 Explained regarding the geometry of the outer edges also applies to Fig. 10 .

[0214] In summary, the present rotating grate 25 realizes, in addition to normal operation (cf. Fig. 9 ) advantageously two different types of cleaning (cf. Fig. 10 and11 ), whereby the partial cleaning allows cleaning during operation of system 1.

[0215] In comparison, commercially available rotating grate systems are not ergonomic and, due to their rectangular geometry, have disadvantageous dead corners where the primary air cannot flow optimally through the fuel. Slag formation frequently occurs in these corners, resulting in poorer combustion and lower efficiency.

[0216] The simple mechanical design of the rotating grate 25 makes it robust, reliable and durable.

[0217] One problem with the movements indicated by arrows D1 and D2 is the possibility of blockages in the movement caused by combustion residues and also by undesirable contents in the fuel (e.g., nails, metal splinters, or similar). Such a blockage during rotation could, without the blockage detection described herein, lead to damage to the drive mechanism or the motors 231. Conversely, however, the rotating grate 25 should be able to perform its crushing function described above, i.e., break up slag, while at the same time not being damaged by "harder" or "more permanent" blockers.

[0218] Appropriate solutions to this problem are described later.

[0219] In order to illustrate the cleaning of the biomass heating system 1 in the context of its operation, the following is described with reference to Fig. 12 a combustion operation or an operating procedure of the biomass heating system 1 is explained. (Operating procedure for biomass heating system 1)

[0220] Fig. 12 shows a general operating procedure of the biomass heating system 1 for one combustion cycle.

[0221] A combustion cycle occurs during combustion operation of the biomass heating system 1. Depending on the energy demand, more than one combustion cycle can occur consecutively during combustion operation. Thus, multiple combustion cycles can be executed during combustion operation.

[0222] Furthermore, the biomass heating system 1 can also be operated in standby mode, in which no combustion takes place and the biomass heating system waits for its use.

[0223] After the combustion cycle has been started, usually by switching on the biomass heating system 1 by a user requesting active boiler operation or by an external (heating) automatic system, the combustion process can first be prepared in the optional step S50.

[0224] During preparation for step S50, the biomass heating system can be initialized mechanically and electronically. For example, the operating system of the control device 100 can be booted up, a self-test of the electronics can be performed, and / or the rotating grate elements 252, 253, 254 can be rotated (opened) by a predetermined angle to remove any deposits on the grate and test the mechanics before a combustion process. During such a mechanical test of the rotating grate 25, the rotary (encoder) sensors can be used to check whether controlling the motors 231 of the rotating mechanism leads to the desired result or whether something is blocked. Furthermore, the mechanical boiler cleaning (via tubulators), ash removal, and the optional electrostatic precipitator cleaning can be operated for a predefined time (e.g., 30 seconds). The air passages of the boiler 11 can also be flushed.To do this, the biomass heating system is purged with air by opening the primary and secondary air valves. Then, the air dampers are closed and the flue gas recirculation line is purged.

[0225] In the next step S52, the combustion chamber 24 is filled with fuel. The fuel is conveyed via the fuel feed 6 onto the rotating grate 25 until a predetermined fuel bed height is reached. For this purpose, the fuel bed height is measured using the fuel bed height sensor 116. The fuel bed height sensor 116 is, for example, a mechanical level valve 86 with a rotation angle sensor.

[0226] Next, the fuel is ignited in step S52. This can also be referred to as the ignition phase. Energy is supplied to the fuel via the ignition device 201 until it burns. Furthermore, the valves or valve positions during fuel ignition can be adjusted to promote fuel ignition. During such ignition, the fan 15 is also activated to generate a corresponding negative pressure in the combustion chamber 24. The primary air and secondary valves can be set to predefined values ​​(e.g., 60% and 15%), and a predefined negative pressure is maintained in the combustion chamber (e.g., 75 Pa).

[0227] If the biomass heating system 1 now reaches a predetermined combustion chamber temperature (e.g., 50°C) and / or a predetermined lambda (e.g., 17%), the biomass heating system 1 proceeds to step S53, the stabilization of the combustion. In this step, which is also referred to as the stabilization phase, ignition of the fuel bed is further promoted. The positions of the air valves 52, the function of the fan 15, and also the fuel supply are adjusted accordingly. In the process, the boiler 11 and the combustion chamber 24 should continue to heat up. Preferably, the combustion process should gradually transition to a steady state in which, from a thermodynamic perspective, equilibrium prevails. If the combustion temperature increases to a predetermined value, for example, 400°C, step S53 is completed.

[0228] Accordingly, the method proceeds to step S54: stabilized combustion and the actual heating operation. In this step S54, the power output or combustion intensity is controlled by means of the fuel supply 6, the fan 15, the position of the valves 52, and other actuators based on the sensor data from sensors of the biomass heating system 1, for example, based on the combustion chamber temperature, the lambda value, and / or the boiler (water or medium) temperature. Fuel-dependent power control can be used here.

[0229] Step S54 is terminated when, for example, sufficient heat output has been made available and / or complete combustion of the fuel in the boiler 11 is detected and calculated.

[0230] Subsequently, in step S55, the combustion chamber 24, and in particular the rotating grate 25, is burned out. The fuel supply is stopped, and the combustion chamber temperature drops. The fuel residues on the rotating grate 25 are burned. For this purpose, the positions of the valves 52 and the fan 15 can be adjusted accordingly. At the end of the burnout, the rotating grate 25 is cleaned by rotating or opening the rotating grate elements accordingly.

[0231] In step S55, the burnout, the primary air supply can be increased (for example, the valves for regulating the primary air supply can be fully opened) to accelerate the combustion process in the boiler, and in particular in the combustion chamber 24, and to keep this step, or phase of the boiler cycle, as short as possible. Therefore, in this step S55, the carbonaceous residues in the combustion chamber 24 should be burned as quickly and completely as possible. The temperature in the combustion chamber 24 typically rises again briefly during this time.

[0232] After completion of step S55, the process can be deactivated (END), or the process can start again (after some time) and then proceed to step S50, which begins a new combustion cycle or heating cycle.

[0233] Fig. 13 shows a performance diagram of an exemplary combustion cycle of the biomass heating system 1, from ignition (S52) to burnout (S55). For simplicity, the preparation (S50) and filling (S50) processes are omitted here.

[0234] In the performance diagram of the Fig. 13 The process of (re-)ignition of the fuel is marked by arrow S52. The fuel catches fire and the output increases rapidly due to the still unused fuel. Approximately in the area of ​​arrow S53, the combustion process stabilizes, whereby the output, after some fluctuation, is stabilized to the desired target output value. Approximately in the area of ​​arrow S54, the (stabilized) combustion process takes place, resulting in a relatively constant output of boiler 11. Approximately at S55, the biomass heating system burns out with the associated output peak, whereby the increase in the primary air supply begins in Fig. 13 indicated by "I". This increased primary air supply burns the unburned fuel residues, thus preventing unburned fuel from being cleaned from boiler 11.

[0235] After that, the combustion cycle shown finally ends, the power and the combustion chamber temperature drop.

[0236] The boiler temperature and the temperature in combustion chamber 24 increase approximately in step with the boiler output. Therefore, there are temperature peaks or maxima at the beginning and end of a combustion cycle. During burnout S55, the increased temperature in the boiler reheats and, preferably, completely burns off carbonaceous residues and deposits on the interior walls and parts of the boiler.

[0237] At temperatures below the temperature in stabilized combustion mode S54, combustion residues are produced in increased quantities and sooting can occur.

[0238] Because the ash is an amorphous, ceramic-like material mixture, it does not have a clearly defined melting point, but rather softens continuously over a wide temperature range. Viscosity decreases with increasing temperature, the ash becomes sticky, the fine ash grains agglomerate and sinter into larger lumps, and the ash begins to creep and eventually even flow.

[0239] Furthermore, slag is always formed during a combustion process when temperatures in the embers exceed the ash melting point. The ash then becomes soft and sticky, and upon cooling, forms the familiar solid, dark-colored slag, which can range in hardness from porous / brittle / crumbly to glassy.

[0240] In this respect, one can conclude from the Fig. 13 In principle, this provides information about the condition of the combustion residues, and especially the resulting slag. At low boiler outputs, the combustion residues tend to be solid and brittle, while at high temperatures, the combustion residues tend to be soft and viscous. The latter can make effective cleaning more difficult.

[0241] However, the actual temperatures and their associated viscosities can only be predicted with great accuracy, as the temperature and melting behavior of the fuel (which is highly variable) or mixture of substances used for combustion is extremely complex. Even minor changes in the proportions of the substances can have a significant impact on the softening point if the mixture forms a eutectic. In general, temperatures rise with increasing coalification. Some substances (such as some potassium, aluminum, sodium, magnesium, and silicon compounds) are known to drastically reduce the softening point. This is particularly evident in stalk-like biomasses (straw and grass), which contain such substances in elevated concentrations and are among the fuels with the lowest ash softening temperatures.

[0242] The cooling and solidification of the slag occurs not only during the temperature changes in a combustion cycle, but also spatially during the transition from the hot zone of the combustion chamber 24 to the cold peripheral areas or into the downstream heat exchanger 4 and also into the filter device 4. Caking deposits form here, which impede and impair heat transfer and increase the flue gas pressure loss of the furnace. This is referred to as "slagging" of the furnace.

[0243] In this grate firing system, slag can block the movement of the grate, or the openings for the primary air supply, i.e. the combustion air flowing through the grate from below, can become clogged. The devices for cleaning and conveying the ash can even be blocked by large, hard lumps of slag.

[0244] This demonstrates that slag is more difficult to handle during cleaning than powdered ash, especially since the consistency and quantity of slag can vary greatly, as explained. The solutions described here can address this particular problem. (Cleaning the boiler)

[0245] Fig. 14 shows a triggering procedure with which a boiler cleaning cycle can be initiated. This triggering procedure can, for example, be executed cyclically by the control device 100, or this triggering procedure can be executed automatically when the operating state of the boiler 11 transitions to state S55: Burnout.

[0246] In step S70, a determination is made as to whether or not the boiler 11 is in the burnout state S55. This can either be cyclically queried and determined ("No"), or this determination is automatically considered fulfilled upon execution of the burnout operating state S55 (initiated by the control device 100).

[0247] If the boiler 11 is in the burnout state (S70: Yes), it is determined whether the combustion chamber temperature (which is measured by the corresponding combustion chamber temperature sensor 117) is lower than a predefined threshold BTS. This threshold BTS can be set, for example, to 180 degrees Celsius. This threshold ensures that cleaning is not carried out with combustion residues that are still oxidizing. Furthermore, it ensures that the slag is less viscous or already more brittle or fragile for cleaning, thus making cleaning more efficient.

[0248] If the combustion chamber temperature is lower than the predefined threshold BTS (S71: Yes), then cleaning of the boiler 11 can be performed in step S72. Such cleaning can involve rotating the rotating grate elements 252, 253, 254 by means of the motors 231. Furthermore, such cleaning can involve moving the cleaning mechanism including the cleaning screw 71 and the turbulators 37. Thus, cleaning of the boiler 11 preferably includes cleaning the grate 25, the heat exchanger 3, the ash pan in the lower part of the boiler, and (optionally) also the electrostatic filter device 4.

[0249] Fig. 15 shows a further development of the triggering procedure of the Fig. 14 , whereby a blockage detection of the cleaning mechanism (including ash screw and preferably turbulators) controlled by the motor 72 can be detected. Regarding the method steps S70, S71 and S72, reference is made to the above explanations of Fig. 14 referred to.

[0250] After cleaning is complete, position sensor 75 detects whether the cleaning mechanism is in the rest position or not in step S73. For example, if the cleaning mechanism has become jammed or seized due to a foreign object and is blocked, it will usually not return to the rest position. Therefore, such a blockage can be detected using position sensor 75.

[0251] If the determination at step S73 is Yes, the cleaning mechanism has returned to the rest position and there is no blockage.

[0252] If the determination in step S73 is: No, the cleaning mechanism has not returned to the rest position (which it should due to the weight of the turbulators) and a blockage is positively detected or recognized (step S74).

[0253] In step S74, for example, a corresponding error message can be stored in the system, or a user can be notified of the blockage via a user interface (e.g., via a touchscreen). Likewise, the boiler 11 can stop operation for safety reasons in response to the detected blockage.

[0254] Fig. 16 shows an (optional) cleaning optimization procedure which ensures a cleaned and unblocked initial state of the boiler 11 before the start of a combustion cycle, if necessary.

[0255] In step S80, it is determined whether the start of a combustion cycle is requested or not. Such a request can, for example, be made manually by a user via input at a user interface. Such a request can also be made automatically, for example, by requesting heating power or by specifying a predefined number of heating cycles to be run consecutively.

[0256] Now, before the heating cycle begins and thus before combustion operation begins, position sensor 75 detects in step S81 whether the cleaning mechanism is in the rest position or not. For example, if the cleaning mechanism has become jammed or seized due to a foreign object and is blocked, it will usually not return to the rest position. Therefore, such a blockage can be detected using position sensor 75.

[0257] If the determination in step S81 is yes, the cleaning mechanism has returned to the rest position and there is no blockage. As a result, step S82 is executed.

[0258] If the determination in step S81 is "No," the cleaning mechanism has not returned to its rest position (which it should have done due to the weight of the turbulators), and a blockage is positively detected. Subsequently, step S83 is executed to attempt to release the blockage by driving or moving the mechanism.

[0259] In step S82, a query is made as to whether or not cleaning was already performed during the last burnout S55 of boiler 11. For this purpose, a so-called "flag" can be activated in software, for example, when cleaning the boiler during burnout. This flag is reset, for example, when steps S54 (or S53, etc.) are performed.

[0260] If boiler 11 was already cleaned during the last burnout S55 (i.e., it was already cleaned at the end of the previous combustion cycle; S82: Yes), the currently requested combustion cycle can be started (S85). This avoids unnecessary activation of the cleaning mechanism, thus saving time and wear.

[0261] If the result of step S82 is No, step S84 then queries whether the combustion chamber temperature is less than the predefined threshold BTS or not.

[0262] If the result of step S84 is No, the process proceeds to step S85. Therefore, if the temperature of the boiler 11 is too high for cleaning, the next combustion cycle is started directly, and cleaning before the combustion cycle is not performed.

[0263] If the result of step S84 is yes, the boiler is cleaned in step S83. Thus, the temperature of boiler 11 has dropped to a level that allows cleaning, and the time lost due to cleaning boiler 11 must also be accepted, since the boiler is already "colder" anyway.

[0264] After step S83, the process proceeds to step S85.

[0265] Fig. 17a shows a cleaning process of the boiler 11.

[0266] If cleaning of boiler 11 is requested (see, for example, steps S72 or S83), the cleaning process for boiler 11 is started.

[0267] In step S90, the motor 72 is energized for a predefined motor time BM, thus the cleaning mechanism is moved by the motor 72 for a specific time BM. This time (duration) is defined such that the cleaning mechanism covers a specific range of motion, for example, such that the turbulators in the heat exchanger 3 perform a sufficient stroke. The time (duration) BM can be set, for example, to 30 seconds.

[0268] In step S91 following step S90, the current supply to motor 72 is interrupted for a predefined pause time P1. This pause time P1 can be, for example, 10 seconds.

[0269] In step S92 following step S91, it is determined whether or not a predefined number WH of executions of steps S90 and S91 has occurred, i.e., whether or not a predefined number WH of iterations of the loop with steps S90 and S91 has been performed. This predefined number WH can be, for example, 5.

[0270] If the result of step S92 is No, steps S90 and S91 are repeated.

[0271] By repeatedly executing steps S90 and S91 (clean, pause, clean, pause...) the cleaning effect is improved.

[0272] If the result of step S92 is Yes, the process proceeds to step S93.

[0273] Here, analogous to what has been described above, it is detected whether the cleaning mechanism 75 has returned to its rest position after the motor 72 has been energized and after the pause P1 or not.

[0274] If the result of step S93 is Yes, the process is terminated. Blockage-free cleaning has been completed.

[0275] If the result of step S94 is no, the method continues with step S94. In the simplest case, step S94 is identical to that described with reference to step S74. Therefore, the method ends with an error message. Optionally and alternatively, however, the method can carry out an anti-blocking process 1 or a first anti-blocking process with step S94, which is described below with reference to Fig. 17b is explained in more detail.

[0276] Fig. 17b shows a first anti-blockade procedure, which is a further development of the procedure of Fig. 17a is.

[0277] If a blockage in the cleaning mechanism is detected, it must be released. To this end, in step S95, motor 72 is energized for a predefined energization time BM2 to release the blockage. The energization time BM2 is preferably longer than the energization time BM1 to increase the force acting on the blockage.

[0278] After the energization in step S95, as already explained, it is again detected whether the cleaning mechanism has returned to the rest position or not.

[0279] If this is the case (S96: Yes), the blockage has been successfully resolved and the cleaning or cleaning process of the Fig 17a and 17b be terminated.

[0280] If this is not the case (S96: No), the blockage could not be resolved or eliminated. The process then continues with step S97. Here, too, there are two alternatives: Either the process is terminated with an error message or an error, or it proceeds to an anti-blockage process 2, which is described below with regard to the Figuren 17c and 17 d is explained in more detail.

[0281] Figuren 17c and 17d show a second anti-blockade procedure in advanced training on the procedures of Fig. 17a and / or 17b.

[0282] In step S98, the motor 72 is energized again for a predefined energization time BM3. The energization time BM3 can preferably be longer than the energization time BM3. Thus, the cleaning mechanism is subjected to greater stress, but only in the case where an attempt with lower power has failed. Alternatively, BM1 = BM2 = BM3 can be used if staggering the drive time is not desired.

[0283] At step S99, the check described above is performed again.

[0284] If the result of step S99 is Yes, the blockage is released and the cleaning process is terminated.

[0285] If the result of step S99 is No, the blockage persists. Subsequently, the power supply is interrupted or paused in step S100 for a predefined pause time P2. This allows the mechanism time to return to its rest position independently.

[0286] At step 101, the check described above is performed again.

[0287] If the result of step 101 is Yes, the blockage is cleared and the cleaning process is terminated.

[0288] If the result of step S101 is No, the blockage persists. In this case, the motor is energized at short intervals BI in step S102. Such intervals can, for example, consist of 2 seconds of energization followed by 2 seconds of pause, which can be repeated multiple times, for example, two to eight times. In this case, the cleaning mechanism is moved jerkily or shaken, for example, to break up brittle slag or to release jams. It is preferable that the intervals be repeated at least twice.

[0289] In the following step 103, the check described above is carried out again.

[0290] If the result of step 103 is Yes, the blockage is cleared and the cleaning process is terminated.

[0291] If the result of step S103 is No, the blockage persists. In this case, the motor 72 is (optionally) moved for a predefined energization time BM4, for example, 2 seconds, in a second direction of rotation, which is opposite to the usual direction of rotation of the motor 72 for cleaning (i.e., the first direction of rotation of the motor 72).

[0292] Thereafter, the motor 72 is energized again at step S105 (cf. S102) at short intervals BI.

[0293] Extensive practical tests have shown that the aforementioned process steps are the most effective way to clear blockages. Applying multiple, abrupt and brief energizations to motor 72 in the first direction, followed by a single energization of motor 72 in the second (opposite) direction, followed again by multiple, abrupt and brief energizations to motor 72 in the first direction, had the greatest probability of definitively clearing the blockage, even in cases of very stubborn slagging and heavy contamination.

[0294] In the following step 106, the check described above is carried out again.

[0295] If the result of step 106 is Yes, the blockage is cleared and the cleaning process is terminated.

[0296] If the result of step S106 is No, the blockage persists. In this case, the blockage is so persistent that step S107 identifies a (non-machine-resolvable) blockage (see S74), and the method is terminated.

[0297] Please note that with "*1" in the Fig. 17d the continuation of the proceedings of Fig. 17c is specified.

[0298] Fig. 18 shows a blockage detection method for the rotating grate 25 of the biomass heating system 1.

[0299] This blockage detection process is performed when a partial or full cleaning of the rotating grate 25 is performed, i.e., when at least one of the motors 231 is energized. This is queried in step S110.

[0300] If at least one motor 231 is energized (S110: Yes), in the following step S111 a current first rotation angle Dd1 is detected (and stored) by means of the rotation position sensor 259.

[0301] In the subsequent step S112, a predefined waiting time WD is waited for. During this time, motor 231 continues to be energized, meaning that the associated rotating grate element 252, 253, 254 or the rotation axis 81 should continue to rotate, provided the rotating grate is not blocked.

[0302] In the subsequent step S113, a current second rotation angle Dd2 is detected (and stored) using the rotational position sensor 259. In other words, two rotation angles Dd1 and Dd2 are now detected and stored at a defined time interval.

[0303] In the following step D114, a check is made to determine whether one of the two end angles has been reached. The end angles are predefined end angles relating to the rotation angles of the respective rotating grate element 252, 253, 254, which represent the mechanically maximum possible end angle or end stop. For example, a rotating grate element can typically be rotated within a rotation range of 0 degrees (horizontal end position) to 170 degrees (rotated end position during cleaning).

[0304] If the detected rotation angle Dd2 matches one of the two predefined end angles (S114: Yes), the respective target end stop has been reached, there is no blockage (since the rotating grate element could rotate completely), and the process is terminated. There is no blockage.

[0305] If none of the end coils is reached, the rotating grate element 252, 253, 254 is still in mid-rotation. At this point, a blockage can be detected by comparing the detected rotation angles Dd1 and Dd2, see step 115. This comparison essentially determines whether the rotation angles Dd1 and Dd2 differ to such an extent that unblocked movement can be assumed. If the rotation angles Dd1 and Dd2 do not differ or do not differ sufficiently, then a blockage can be assumed.

[0306] This adjustment in step S115 can be determined, for example (other mathematical methods will of course also be readily apparent to those skilled in the art) using the following comparison: I Dd2-Dd1 I > threshold value Sd. The threshold value Sd is a lower rotation angle (speed) value, which is determined in advance, for example, through experiments. The threshold value Sd thus indicates a minimum movement speed at which the rotating grate element 252, 253, 254 should move (which is known, for example, from the design and electrical specifications as the minimum target value).

[0307] The difference Dd2 and Dd1 represents the sensor-detected rotational (angular) speed based on the time interval WD, which is determined by step S112. In this respect, the method of Fig. 18 a rotational speed of the rotational axis 81 ((Dd1 - Dd2) per time unit WD including the calculation time in the control device or the electronic running times. With the (optional) absolute value formation from the difference Dd2 - Dd1, it is irrelevant in which direction the rotating grate element 252, 253, 254 is rotated.

[0308] For example, if Dd2 is 66.8 degrees and Dd1 is 67 degrees, the difference is 0.2 degrees. If the predefined time WD is 0.1 second, the detected angular velocity is 0.2 degrees per 0.1 second. If the threshold value Sd is now set to 0.1 degrees per 0.1 second, it is positively detected that the rotating grate element 252, 253, 254 is moving sufficiently fast and is therefore not blocked (S115: Yes). In this case, the process runs in a loop to check the movement or blockage detection until one of the end angles is reached (S111 to S115).

[0309] However, if the comparison in step S115 has a negative result (i.e., the rotating grate element 252, 253, 254 does not move or moves too slowly), the method proceeds to step S116. This step and the following steps are optional and serve to improve the method. Alternatively (or in the simplest case), the method can be carried out instead of the Fig. 18 shown step directly into the realization "rust blocked" (cf. p118).

[0310] In step S116, an error count counter FE is incremented by +1. Subsequently, in step S117, a check is performed to determine whether the current error count FE is greater than a predefined maximum error count FEma. The predefined maximum error count FEma can be, for example, 5.

[0311] If the result of step S116 is No, the process returns to step S111.

[0312] However, if the result of step S116 is Yes, it can be assumed that the grate 25 or the rotating grate element 252, 253, 254 is blocked (step S118). The method subsequently ends with the conclusion or error message "Grate blocked." As a result, for example, an error message can be issued and / or the combustion operation of the biomass heating system can be terminated.

[0313] Likewise, following the error message "Grate blocked", the direction of rotation of the rotating grate element 252, 253, 254 can be reversed in order to release a blockage.

[0314] Furthermore, following the error message "Grate blocked," the rotation direction of the rotating grate element 252, 253, 254 can be temporarily reversed to clear a blockage, and then the rotation of the rotating grate element 252, 253, 254 can be continued in the original direction. An error counter can also be used here, allowing, for example, three attempts.

[0315] Fig. 19 shows a diagram showing the procedure of Fig. 18 with a temporal progression of the angle of rotation without blockage, with blockage and with a breaker function on detected blockage, as well as an alternative process step in response to a detected blockage.

[0316] The vertical axis of the diagram of the Fig. 19 indicates a rotation angle that is detected by the rotation position or angle sensor 259. The rotation angle can preferably be detected at regular intervals, for example, it is sampled every 0.1 seconds.

[0317] The horizontal axis represents time. The diagram of the Fig. 19 thus shows the temporal course of the rotation of the rotation axis 91 and thus of the corresponding rotating grate element 252, 253, 254.

[0318] The arrow labeled "Rotation of an axis" refers to a curve section in which the angle of axis 81 decreases. This curve section shows that a rotating grate element 252, 253, 254 is rotated back from an open position to the closed position (horizontal position). It should be noted that the method shown can, of course, also be applied when opening the rotating grate element 252, 253, 254.

[0319] During the closing movement shown, a first angle of rotation Dd1 and a second angle of rotation Dd2 are now recorded at a time interval WD (S111, S112, S113).

[0320] Initially, the final angle (in this case, the minimum angle 0) is not reached (p. 114). The procedure continues.

[0321] Since the angles Dd1 and Dd2 are sufficiently different (>Sd), the rotating grate element 252, 253, 254 is not blocked, thus no special reaction is required (S115). The further points on this curve section indicate that the detection of the rotation angle is repeated (ie, as long as the motor 231 is energized, the rotation angle is repeatedly detected). In this respect, the Fig. 19 the procedure only partially.

[0322] The arrow labeled "Blockage" indicates the beginning of a curve section where the angle of axis 81 no longer decreases. From this point on, the rotating grate element 252, 253, 254 is blocked, for example, by a hard slag lump.

[0323] Since the first rotation angle Dd1 and the second rotation angle Dd2 are now detected at a time interval WD (S111, S112, S113), the result of the calculation in step S115 falls below the threshold value Sd (S115). Therefore, the method proceeds to step S116. The error counter is incremented by 1. It should be noted that, although this is Fig. 18 and Fig. 19 not shown, the error counter is initialized to 0 at the beginning of the procedure ("Start"). At "#1" 1 error is counted or the first loop pass of the loop of the Fig. 18 with steps S111 to S117. In this example, the predefined maximum error number Fma is preset or pre-stored to "2". In this respect, the loop of the Fig. 18 with steps S111 to S117 repeated three times, resulting in Fig. 19 "#2" and "#3" represent a second and third iteration of the loop with steps S111 to S117. However, the result in step S117 in the third iteration is an exit from the loop (S117: Yes), with the result "Gratus blocked" (S118).

[0324] Following step S118, there are now three possible reactions of the system a) Error message and stop the rotation. b) .Return the grate to its original position (would be step 119). This is in Fig. 19 represented by the dashed line and the arrow "Reverse". c) Executing a breaker function. The breaker function can consist of reversing the rotation of the axis 81 for a predetermined reversal time (i.e., performing a rotation in a second direction opposite to the original direction), and then continuing the rotation of the axis 81 in the original direction until a blockage is possibly detected again (S111 to S117). This reverse-forward rotation can be performed once or repeatedly. Fig. 19 As an example, this reverse-forward rotation is performed three times until the slag is broken. This reverse-forward rotation can be used to implement a crushing function designed to break up slag and combustion residues, thus clearing the blockage. In this respect, the breaker function comprises the following additional steps, which follow or replace step S118: Reversing the axis 81 for a predetermined time; Continuing the rotation in the original direction, with the method returning to S110. It should be noted that the breaker function may also additionally comprise an additional breaker error counter, whereby a reversal is performed, for example, only for a certain number of iterations.

[0325] The procedure of Figuren 18 and 19has the following properties and advantages: A blockage of the rotating grate is reliably detected without additional sensors or special measures (e.g., an additional current sensor for the motor current supply). The time WD can be used to define the breaking force with which the rotating grate attempts to break up the slag when rotating. The longer this time WD is, the longer the motor is energized in the event of a blockage. The same applies to the error counter (S 116, S117). The maximum error count Fma defines the number of iterations of the loop S111-S117 until a reaction occurs and thus the time in which the motor counteracts the blockage. In addition, the error counter (S116, S117) prevents an overly rapid reaction to only minor movement blockages, which occur more frequently. Although the rotational movement in Fig. 19 While the speed is shown linearly, in practice it can be non-linear (depending on the type and quantity of slag). Thus, the threshold Sd can be used to very sensitively adjust which movement speeds are still permissible and which are no longer permissible. In this respect, the process can be specifically adjusted to the requirements of a rotating grate using the parameters Sd, WD, and Fma, which plays an important role in breaking up slag, without, however, itself being damaged by overloading. (Other embodiments)

[0326] In addition to the embodiments and aspects explained above, the invention allows for further design principles. Individual features of the various embodiments and aspects can also be combined with one another in any way, as long as this is evident to a person skilled in the art.

[0327] The rotating grate 25 of the Fig. 9 bis 11 Although it is shown without the cleaning device, it can be combined at any time with a cleaning device not shown.

[0328] In the present case, the rotating grate 25 is described by way of example with three rotating grate elements 252, 253, 254. However, the rotating grate 25 can also have only one rotating grate element 252, or even two rotating grate elements 252, 253. In principle, a rotating grate 25 with a plurality of rotating grate elements is conceivable. In this respect, the present disclosure is not limited to a specific number of rotating grate elements 252, 253, 254.

[0329] The rotation of the rotating grate elements can also be different in terms of cleaning than in terms of Figuren 9 bis 11 described. Therefore, the present disclosure is not limited to the specific manner of rotation (and the states created thereby) of the rotating grate elements. For example, there may also be only two states: one of a working position of the rotating grate (closed / horizontal state) and one of full cleaning of the rotating grate (fully open or non-horizontal state). Likewise, there may be further states of the rotating grate 25, insofar as this is apparent to the person skilled in the art from a combination of horizontal and non-horizontal individual states of the respective rotating grate elements. For example, only the middle rotating grate element 253 can be rotated for partial cleaning.

[0330] As regards the Fig. 9 bis 11 As explained, the rotating grate elements 252, 253, 254 can be rotated individually or together to switch between the three explained states.

[0331] It is clear that the blockage detection described is also applicable to other types of rotating grates and cleaning mechanisms.

[0332] Furthermore, each rotating grate element 252, 253, 254 can have at least one known cleaning device. Likewise, one or more rotating grate elements from the total number of rotating grate elements of the rotating grate 25 can also have no cleaning device.

[0333] For at least one rotating grate element 252, 253, 254, for example, a cleaning device can additionally be provided, as is known from the in-house prior art of EP 21 218 434.5, although this is not explained in more detail herein.

[0334] Furthermore, the method for blockage detection is described for a single axis 81. It is understood that the method can also be applied (simultaneously) to more than one axis 81.

[0335] A blockage can include a releasable or a non-releasable mechanical blockage.

[0336] A blockage may include a mechanical blockage of a movement which, for example, exceeds the available drive or torque of a drive device or which, if rotated, would result in damage to the mechanism, even though the drive or torque would be sufficient to overcome the blockage itself.

[0337] Although the methods described herein are primarily described with reference to a rotation of a rotation axis 81 of a rotating grate, the method can also be applied analogously to other types of position changes of a grate. For example, in the case of a moving grate, a linear movement can also be detected instead of a rotational movement.

[0338] Further in Fig. 19 170 degrees and 0 degrees are specified as the maximum and minimum angles, respectively. These angles can, of course, be other angles, depending on the rotating grate.

[0339] Here, the recirculation device 5 is described with a primary recirculation and a secondary recirculation. However, the recirculation device 5 can also have only a primary recirculation and no secondary recirculation in its basic configuration. With this basic configuration of the recirculation device, the components required for the secondary recirculation can be completely eliminated. For example, the recirculation inlet channel divider 532, the secondary recirculation channel 57 and an associated secondary mixing unit 5b, which will be explained, as well as the recirculation nozzles 291, can be eliminated.

[0340] Alternatively, only primary recirculation may be provided in such a way that the secondary mixing unit 5b and the associated channels are omitted, and the mixture of the primary recirculation is not only fed under the rotating grate 25, but is also fed (for example, via another channel) to the recirculation nozzles 291 provided in this variant. This variant is mechanically simpler and thus more cost-effective, but nevertheless has the recirculation nozzles 291 for swirling the flow in the combustion chamber 24.

[0341] An air flow sensor, a vacuum cell, a temperature sensor, an exhaust gas sensor and / or a lambda sensor can be provided at the inlet of the flue gas recirculation device 5.

[0342] Furthermore, instead of just three rotating grate elements 252, 253, and 254, two, four, or more rotating grate elements can be provided. For example, five rotating grate elements could be arranged with the same symmetry and functionality as the three rotating grate elements presented here. Furthermore, the rotating grate elements can also be shaped or designed differently from one another. More rotating grate elements have the advantage of enhancing the crushing function.

[0343] It should be noted that other dimensions or combinations of dimensions may be provided that deviate from these.

[0344] Instead of the convex sides of the rotating grate elements 252 and 254, concave sides can also be provided, whereby the sides of the rotating grate element 253 can subsequently have a complementary convex shape. This is functionally almost equivalent.

[0345] Other fuels than wood chips or pellets can also be used as fuels in the biomass heating system.

[0346] The rotating grate can also be called a tilting grate.

[0347] The biomass heating system disclosed here can also be fired exclusively with one type of fuel, for example only with pellets.

[0348] The combustion chamber bricks 29 may also be provided without the recirculation nozzles 291. This may apply in particular to the case where no secondary recirculation is provided.

[0349] The geometries of the rotating grate elements 252, 253, and 254 may differ from those shown in the figures. These rotating grate elements can be rectangular, square, or even round, for example.

[0350] The first and second anti-blockade procedures of the Figuren 17b bis 17d can also be executed independently of each other in response to a blockage detected elsewhere. In this respect, the procedures of the Figuren 17a not necessarily together and are each disclosed as an independent procedure. In addition, the second anti-blockade procedure of the Fig. 17c and 17d as a further development of the procedure of Fig. 17a which is the first anti-blockade procedure of the Fig. 17b can be omitted.

[0351] The methods explained herein can be implemented as a computer program or part of a computer program. The Fig. 12 The procedures described below can represent parts of an overall system control program. Fig. 12 The procedures described below can be carried out cyclically or repeatedly.

[0352] A computer program, which may also be referred to or described as a program, software, a software application, an application, a module, a software module, a script, or code, may be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages; and it may be deployed in any form, including as a specific program or as a module, component, subroutine, or other suitable unit for use in a computing environment. A program may, but need not, correspond to a file in a file system. A program may be stored in a section of a file that holds other programs or data, e.g., one or more scripts, stored in a trace language document, in a single file dedicated to the program in question, or in multiple coordinated files, e.g.,Files that store one or more modules, subroutines, or sections of code. A computer program can be designed to run on one computer or on multiple computers located at one location or distributed across multiple locations and connected by a data communications network.

[0353] The methods and logic flows described in this specification may be executed by one or more programmable computers executing one or more computer programs for performing functions by operating on input data and generating an output. The methods and logic flows may also be executed by special-purpose logic circuitry, such as an FPGA or ASIC, or by a combination of special-purpose logic circuitry and one or more programmed computers.

[0354] Suitable computers for executing a computer program may be based on general-purpose or special-purpose microprocessors, or both, or on any other type of central processing unit. Generally, a central processing unit receives instructions and data from read-only memory or random-access memory, or both. The essential elements of a computer are a central processing unit for executing instructions and one or more memory devices for storing instructions and data. The central processing unit and memory may be supplemented by or integrated with special-purpose logic circuitry. Generally, a computer also includes one or more mass storage devices for storing data, or is operatively connected to receive data therefrom or transfer data to one or more mass storage devices, e.g.Magnetic, magneto-optical, or optical disks. However, a computer need not include such devices. Furthermore, a computer may be embedded in another device, such as a mobile phone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device, such as a universal serial bus (USB) flash drive, to name a few.

[0355] Suitable computer-readable media for storing computer program instructions and data include all forms of non-volatile memory, media, and storage devices, including, by way of example, semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable storage devices; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0356] To provide interaction with a user, embodiments of the content described in this specification may be executed on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user, and a keyboard and pointing device, e.g., a mouse or tactile ball, through which the user can provide input to the computer. Other types of devices may also be used to provide interaction with a user; e.g., feedback provided to the user may be any form of sensory feedback, e.g., visual feedback, audible feedback, or tactile feedback; and input from the user may be received in any form, including auditory, verbal, or tactile input.Additionally, a computer may interact with a user by sending documents to and receiving documents from a device used by the user; for example, by sending web pages to a web browser on a user's device in response to requests received from the web browser. Furthermore, a computer may interact with a user by sending text messages or other forms of messages to a personal device, such as a smartphone running a messaging application, and receiving responsive messages from the user.

[0357] Data processing devices, e.g., the controller 100, for implementing machine learning models may also include, for example, special-purpose hardware acceleration units for processing common and computationally intensive components of machine learning training or production, e.g., interference, workloads.

[0358] The methods described herein may be executed as a (computer) program, for example on the hardware described above, but are not limited thereto.

[0359] Likewise, at least one of the present methods may be provided as a program on a computer-readable storage medium.

[0360] It is preferred that the methods described herein be performed by the controller 100.

[0361] The methods described herein can also be implemented independently or individually. It is therefore not absolutely necessary for one method to require the other. (List of reference symbols)

[0362] 1Biomass heating system 11Boiler 12Boiler base 13Boiler casing 14Water circulation system 15Blower 16Exterior cladding 100Control device / Client 111 Exhaust gas temperature sensor 112 Lambda probe 113 Vacuum sensor or pressure difference sensor 114 Return temperature sensor or heating water temperature sensor 115 Boiler temperature sensor 116 Fuel bed height sensor 117 Combustion chamber temperature sensor 2Combustion device 21First maintenance opening for the combustion device 22Rotating mechanism holder 23Rotating mechanism 24Combustion chamber 25Rotating grate 26Primary combustion zone of the combustion chamber 27Secondary combustion zone or radiation part of the combustion chamber 28Fuel bed 29Combustion chamber bricks A1First horizontal section line A2First vertical section line 201Ignition device 202Combustion chamber slope 203Combustion chamber nozzle 211Insulating material (e.g. vermiculite) 231Drive or motor(s) of the rotating mechanism 251Bottom plate of the rotating grate 252First rotating grate element 253Second rotating grate element 254Third rotating grate element 255Transition element 256Openings 257Grate lips 258Combustion surface 259Rotation position sensor 260 Contact surfaces of the combustion chamber stones 261 Groove 262 Projection 263 Ring 264 Support stones 265 Incline of the support stones 291Secondary air or recirculation nozzles 298Places with poorer cleaning performance 299Places with good cleaning performance 3Heat exchanger 31Maintenance opening for heat exchanger 32Boiler tubes 33Boiler tube inlet 34Turning chamber inlet 35Turning chamber 36Spring turbulator 37Belt or spiral turbulator 38Heat exchange medium 331Insulation at the boiler tube inlet 4Filter device 41Exhaust gas outlet 42Electrode supply line 43Electrode holder 44Filter inlet 45Electrode 46Electrode insulation 47Filter outlet 48Cage 49Flue gas condenser 5Recirculation device 50Annular channel around combustion chamber bricks 52Air valve 53Recirculation inlet 54Primary mixing channel 55Secondary mixing channel or secondary tempering channel 56Primary recirculation channel 57Secondary recirculation channel 58Primary air channel 59Secondary air channel 6Fuel supply 61Cell wheel lock 62Fuel supply axis 63Transmission mechanism 64Fuel supply channel 65Fuel supply opening 66Drive motor 67Fuel conveyor screw 7Ash removal 71Ash removal screw 711Screw axis 712Centering disc 713Heat exchanger section 714Burner section 72Ash removal motor with mechanism 73Transition auger 731Right subsection - left-rising auger 732Left subsection - right-rising auger 74Ash container / ash pan 75Transition auger housing 751Transition auger housing opening 752Border plate 753Main body section of the housing 754Fastening and separating element 755Funnel element 76Cleaning sensor 81Bearing axes 82Rotation axis of the fuel level flap 83Fuel level flap 831Main surface 832Center axis of the rotation axis or bearing shaft 81 833Surface parallel 834Openings 84Bearing notch 85Sensor flange 86Fire bed height measuring mechanism EInsertion direction of the fuel S*Flow arrows D1first direction of rotation D2,D3second directions of rotation opposite to the first direction of rotation Wkboiler output

Claims

1. Biomass heating system (1) for firing biogenic fuel, comprising: a boiler (11) having a combustion device (2) and having a heat exchanger (3); a controller (100) having a memory; at least one sensor (76, 259) capable of detecting a state of an ash removal device (7, 25) for cleaning combustion residues from the boiler (11); wherein the biomass heating system (1) is set up such that the control device (100) can detect a blockage of the ash removal device (7, 25) by means of information received from the sensor (76, 259), the biomass heating system (1) further comprising: a boiler (11) with a combustion device (2) and with a heat exchanger (3), wherein the combustion device (2) comprises a rotary grate (25) with at least one rotary grate element (252, 253, 254) rotatably mounted with an axis of rotation (81), wherein the rotary grate (25) can be rotated in order to clean the combustion residues from the combustion surface (258) of the rotary grate (25); at least one rotation angle sensor (259) as the sensor, which can detect a rotation angle of the rotation axis (81) and which is communicatively connected to the control device (100); at least one drive (231) for rotating the axis of rotation (81), wherein the drive (231) is controlled by the control device (100); wherein the biomass heating system (1) is configured to detect (S118) a blockage of a rotation of the at least one rotary grate element (252, 253, 254) if a certain rotational speed of the at least one rotary grate element (252, 253, 254) is smaller than a predetermined threshold value (Sd).

2. The biomass heating system (1) as set forth in claim 1, wherein, the biomass heating system (1) is configured to determine the rotational speed by means of a difference of two detected angles of rotation (Dd1, Dd2), wherein the two angles of rotation (Dd1, Dd2) are detected at a predetermined time interval (WD) from one another.

3. The biomass heating system (1) according to any one of the preceding claims, wherein the biomass heating system (1) is configured to detect the blockage only if the determined rotational speed is smaller than the predetermined threshold value (Sd) in at least two successive determinations.

4. The biomass heating system (1) according to any one of the preceding claims, wherein the biomass heating system (1) is set up, when the blockage of the rotation in a first direction of rotation is detected positively, a crusher function is carried out in which the at least one rotary grate element (252, 253, 254) is rotated back in a second direction of rotation counter to the first direction of rotation for a predetermined time, and as a result the at least one rotary grate element (252, 253, 254) is rotated again in the first direction of rotation.

5. The biomass heating system (1) according to any one of the preceding claims, wherein the heat exchanger (3) comprises a plurality of boiler tubes (32) with turbulators (36, 37) located therein; and the sensor is a position sensor (75) that can detect a rest position of the turbulators (36, 37) indirectly or directly.

6. A method of detecting a blockage of a rotary grate (25) of a biomass heating system (1), the biomass heating system (1) comprising: a boiler (11) with a combustion device (2) and with a heat exchanger (3), a controller (100) having a memory; at least one sensor (76, 259) capable of detecting a state of an ash removal device (7, 25) for cleaning combustion residues from the boiler (11); the method comprising the steps of: Detecting, by the control device (100), a blockage of the ash removal device (7, 25) by evaluating information from the sensor (76, 259), wherein the biomass heating system (1) further comprises: a rotary grate (25) of the combustion device (2) having at least one rotary grate element (252, 253, 254) rotatably mounted with an axis of rotation (81); at least one rotation angle sensor (259), which can detect a rotation angle (Dd1, Dd2) of the rotation axis (81) and which is communicatively connected to the control device (100); at least one drive (231) for rotating the axis of rotation (81), wherein the drive (231) is controlled by the control device (100), the method further comprising the steps of: Determining (S111-S113, S115) the rotational speed of the at least one rotary grate element (252, 253, 254); Comparing (S115) the determined rotational speed to a predetermined threshold (Sd); Detecting (S118) a blockage of a rotation of the at least one rotary grate element (252, 253, 254) if the comparison reveals that the rotational speed is smaller than the threshold value, wherein determining the rotational speed comprises the steps of: Detecting a first angle of rotation (Dd1) at a first point in time; Detecting a second angle of rotation (Dd2) at a second time, which is set a predetermined waiting time (WD) after the first time; Calculating the difference of the first angle of rotation (Dd1) and the second angle of rotation (Dd1).

7. The method for detecting a blockage of a rotary grate (25) of a biomass heating system (1) according to claim 6, wherein the blockage is detected only if the determined rotational speed is less than the predetermined threshold (Sd) in at least two consecutive determinations.

8. A method for detecting a blockage of a rotary grate (25) of a biomass heating system (1) according to claim 6 or 7, further comprising the steps of: Performing a crusher function upon positive detection of the blockage of the rotation in a first direction of rotation, wherein the crusher function consists in that the at least one rotary grate element (252, 253, 254) is rotated back a predetermined time counter to the first direction of rotation in a second direction of rotation, and as a result, the at least one rotary grate element (252, 253, 254) is rotated again in the first direction of rotation.

9. A computer program comprising instructions that, when executed by a computer, cause the program to perform the method of any one of claims 6 to 8.

10. Computer-readable storage medium on which the computer program of claim 9 is stored.