EP4375570A1 - Installation de chauffage de biomasse à nettoyage amélioré et détection de blocage de celle-ci - Google Patents

Installation de chauffage de biomasse à nettoyage amélioré et détection de blocage de celle-ci Download PDF

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Publication number
EP4375570A1
EP4375570A1 EP22209601.8A EP22209601A EP4375570A1 EP 4375570 A1 EP4375570 A1 EP 4375570A1 EP 22209601 A EP22209601 A EP 22209601A EP 4375570 A1 EP4375570 A1 EP 4375570A1
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EP
European Patent Office
Prior art keywords
rotation
rotating grate
combustion
heating system
boiler
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22209601.8A
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German (de)
English (en)
Inventor
Thilo SOMMERAUER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SL Technik GmbH
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SL Technik GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SL Technik GmbH filed Critical SL Technik GmbH
Priority to EP22209601.8A priority Critical patent/EP4375570A1/fr
Publication of EP4375570A1 publication Critical patent/EP4375570A1/fr
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B60/00—Combustion apparatus in which the fuel burns essentially without moving
    • F23B60/02—Combustion apparatus in which the fuel burns essentially without moving with combustion air supplied through a grate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23H—GRATES; CLEANING OR RAKING GRATES
    • F23H15/00—Cleaning arrangements for grates; Moving fuel along grates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J1/00—Removing ash, clinker, or slag from combustion chambers
    • F23J1/06—Mechanically-operated devices, e.g. clinker pushers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J3/00—Removing solid residues from passages or chambers beyond the fire, e.g. from flues by soot blowers
    • F23J3/02—Cleaning furnace tubes; Cleaning flues or chimneys
    • F23J3/023—Cleaning furnace tubes; Cleaning flues or chimneys cleaning the fireside of watertubes in boilers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23H—GRATES; CLEANING OR RAKING GRATES
    • F23H2700/00—Grates characterised by special features or applications
    • F23H2700/004—Rotary grates with horizontal axis
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2700/00—Ash removal, handling and treatment means; Ash and slag handling in pulverulent fuel furnaces; Ash removal means for incinerators
    • F23J2700/001—Ash removal, handling and treatment means

Definitions

  • the invention relates to a biomass heating system with improved cleaning and blockage detection.
  • the invention relates to a blockage detection system for cleaning combustion residues in a biomass heating system.
  • Biomass heating systems with an output range of 20 to 500 kW are known. Biomass can be seen as a cheap, domestic, crisis-proof and environmentally friendly fuel.
  • Combustible biomass or solid fuels include wood chips or pellets.
  • the pellets usually consist of wood chips, sawdust, biomass or other materials that have been compressed into small disks 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 chips
  • wood chips are wood that has been chopped up using cutting tools.
  • Biomass heating systems for fuel in the form of pellets and wood chips essentially have a boiler with a combustion chamber (the combustion chamber) and a heat exchanger connected to it. Due to stricter legal regulations in many countries, some biomass heating systems also have a fine dust filter. Various other accessories are usually available, such as for example, control devices, probes, safety thermostats, pressure switches, an exhaust gas or flue gas recirculation system and a separate fuel tank.
  • the combustion chamber is usually provided with a device for supplying fuel, a device for supplying air and an ignition device for the fuel.
  • the device for supplying air in turn normally has a high-performance fan with low pressure in order to have a beneficial effect on the thermodynamic factors during combustion in the combustion chamber.
  • a device for supplying fuel can, for example, be provided with a side feed (so-called cross-feed firing). The fuel is pushed into the combustion chamber from the side via a screw or a piston.
  • the combustion chamber also usually has a combustion grate on which the fuel is continuously fed and burned.
  • This combustion grate stores the fuel for combustion and has openings that allow part of the combustion air to pass through as primary air to the fuel.
  • the grate can also be rigid or movable. Movable grates usually serve to easily dispose of the combustion residues that arise during combustion, such as ash and slag.
  • these combustion residues can stick to the grate or bake on and must be cleaned off manually on a regular basis, which is disadvantageous.
  • the ash and slag can also clog the openings in the grate for the air supply with ash or slag, which has a negative impact on combustion efficiency.
  • Practice shows that the combustion residues can stick or bake on, particularly in the openings in the grate, which makes cleaning the grate even more difficult.
  • the grate When the primary air flows through the grate, the grate is also cooled, which protects the material. If the openings become blocked, this cooling effect is also impaired.
  • furnaces that are 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 behavior. It is therefore difficult to provide a heating system that is equally suitable for different fuels and whose grates can be cleaned more effectively.
  • 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).
  • a primary combustion zone immediate combustion of the fuel on the grate
  • a secondary combustion zone afterburning of the flue gas.
  • the drying, pyrolytic decomposition and gasification of the fuel take place in the combustion chamber.
  • Secondary air can also be introduced to completely burn the resulting combustible gases.
  • the combustion of the pellets or wood chips essentially has two phases.
  • 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.
  • the part converted into gas is burned, as well as any remaining solids that may be present. In this way, the fuel outgasses and the resulting gas is also burned.
  • Pyrolysis is the thermal decomposition of a solid substance 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, whereby the pyrolysis gases can be divided into gases that can be condensed at room temperature and those that cannot.
  • Primary pyrolysis takes place at roughly 250-450°C and secondary pyrolysis at around 450-600°C.
  • the secondary pyrolysis that occurs afterwards is based on the further reaction of the pyrolysis products that are primarily formed. Drying and pyrolysis take place at least largely without the use of air, since volatile CH compounds escape from the particle and therefore no air reaches the particle surface.
  • Gasification can be seen as part of oxidation; the solid, liquid and gaseous products created during pyrolytic decomposition are reacted by the application of further heat. This takes place by adding a gasifying agent such as air, oxygen or even water vapor.
  • a gasifying agent such as air, oxygen or even water vapor.
  • the lambda value during gasification is greater than zero and less than one. Gasification takes place at around 300 to 850°C. Above approximately 850°C, complete oxidation takes place with excess air (lambda greater than 1).
  • the end products of the reaction are essentially carbon dioxide, water vapor and ash. In all phases, the boundaries are not rigid, but rather fluid.
  • the combustion process can be advantageously controlled using a lambda probe provided at the exhaust gas outlet of the boiler.
  • 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.
  • the biological fuel may also be contaminated. These contaminants can increase the formation of ash and slag and/or cause blockages in the openings of the grate and the rotating mechanism. Blockages can also occur in rotating grates.
  • pellets that fall into the combustion chamber can roll or slide out of the grate and end up in an area of the combustion chamber where the temperature is lower or where the air supply is poor, or they can even fall into the lowest chamber of the boiler.
  • Pellets that do not remain on the grate burn incompletely, causing poor efficiency, excessive ash and a certain amount of unburned pollutant particles.
  • Biomass heating systems for pellets or wood chips have the following additional disadvantages and problems.
  • 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.
  • the hybrid technology should enable the use of both pellets and wood chips with water contents between 8 and 35 percent by weight.
  • the above-mentioned task(s) or 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.
  • a biomass heating system for burning biogenic fuel comprising: a boiler with a combustion device and with a heat exchanger; a control device with a memory; at least one sensor which detects a state of a Ash removal device for cleaning combustion residues from the boiler; wherein the biomass heating system is designed such that the control device can detect a blockage of the ash removal device by means of information received from the sensor.
  • a biomass heating 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 with 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 set up 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.
  • 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.
  • 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.
  • the biomass heating system is designed 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 rotates for a predetermined time against the first direction of rotation is rotated back into a second direction of rotation, and subsequently at least one rotating grate element is rotated again into the first direction of rotation.
  • the heat exchanger has a plurality of boiler tubes with turbulators located therein; and the sensor is a position sensor that can detect a rest position of the turbulators directly or indirectly.
  • a method for detecting a blockage of a rotating grate of a biomass heating system comprises the following: a boiler with a combustion device and with a heat exchanger, a control device with a memory; 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.
  • the biomass heating system further comprises the following: a rotating grate of the combustion device with 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 less than the threshold value.
  • determining the rotational speed comprises the following steps: detecting a first angle of rotation at a first point in time; detecting a second angle of rotation at a second point in time which is set a predetermined waiting time after the first point in time; calculating the difference between the first angle of rotation and the second angle of rotation.
  • the blockage is only detected if the determined rotational speed is less than the predetermined threshold value in at least two consecutive determinations.
  • 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.
  • a method for initiating a cleaning of a rotating grate of a biomass heating system comprises the following: a boiler with a combustion device and with a heat exchanger, wherein the combustion device comprises a rotating grate with at least one rotating grate element rotatably mounted with a rotation axis; a control device with a memory; 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 combustion chamber temperature sensor which can detect a temperature of the combustion chamber 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: detecting whether the boiler is in the state of burning out or not; carrying out the following steps if it is detected that the boiler is in the state of burning out: detecting the combustion chamber temperature with the Combustion chamber temperature sensor; cleaning the rotating grate by rotating at
  • 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.
  • horizontal can mean a flat alignment of an axis or a cross-section, assuming that the boiler is also set up horizontally, whereby, for example, the earth's level can be the reference.
  • horizontal can mean “parallel” to the base plane of the boiler, as this is usually defined.
  • horizontal can only be understood as at least approximately perpendicular to the direction of action of the earth's gravitational force or acceleration due to gravity.
  • an expression such as “A or B”, “at least one of A or/and B” or “one or more of A or/and B” may include all possible combinations of features listed together.
  • Expressions 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.
  • a term “configured to” (or “arranged to”) used in the present disclosure may be replaced by “suitable for”, “suitable for”, “adapted to”, “made to”, “capable of” or “designed to”, depending on what is technically possible.
  • a term “device configured to” or “arranged to” may mean that the device can work in conjunction with another device or component, or can perform a corresponding function.
  • 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 the ash removal devices 7, 25, i.e. the present rotating grate 25 with its cleaning and also the ash screw 71.
  • Fig.1 shows a three-dimensional overview view of the biomass heating system 1 according to an embodiment of the invention.
  • the arrow V indicates the front view of the system 1
  • the arrow S indicates the side view of the system 1.
  • the biomass heating system 1 has a boiler 11, which is 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 shown.
  • a combustion device 2 (not shown), which can be reached via a first maintenance opening with a closure 21.
  • a rotary mechanism holder 22 (not shown) for a rotary grate 25 supports a rotary mechanism 23, with which drive forces can be transmitted to rotary axes 81 or bearing axes 81 of the rotary grate 25.
  • the rotary mechanism 23 can preferably have an elastic transmission element, for example a toothed belt, which transmits the drive forces of the motor 231 to the rotary axis 81.
  • the rotary 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 over.
  • a heat exchanger 3 (not shown), which can be accessed from above via a second maintenance opening with a closure 31.
  • an electrostatic filter device 4 (also referred to as filter 4 for short) with an electrode 45 (cf. Fig.2 ff.), which are accompanied by a is suspended from an insulating electrode holder 43 and is energized via an electrode supply line 42.
  • the filter device 4 has a tubular inner volume 46b which extends in a longitudinal direction of the filter device 4.
  • the exhaust gas of the biomass heating system 1, which has flowed through the filter device 4, is discharged via an exhaust gas outlet 41, which is arranged downstream of the filter device 4 (fluidically).
  • a fan or a blower can be provided here.
  • a recirculation device 5 which recirculates part of the smoke or exhaust gases via recirculation channels 51, 53 and 54 and flaps 52 for cooling the combustion process and reuse in the combustion process.
  • the biomass heating system 1 also has a fuel feed 6, with which the fuel is fed 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 fed to the combustion device 2 in a fuel feed channel 64.
  • an ash removal device 7 which has an ash removal screw 71 in an ash removal channel, which is operated by a motor 72.
  • This ash removal device 7 is preferably set up in such a way 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, which cleans the heat exchanger.
  • slag or other residues from the Combustion e.g. nails
  • 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 (for example (S-)RAM, ROM, flash and/or cache memory), as well as various interfaces. Analogue or digital inputs and outputs can be provided as interfaces. For example, CAN bus interfaces, 0-10 V analogue inputs or 4-20 mA analogue inputs/outputs for sensors and actuators and/or RS-232 interfaces can be provided.
  • the control device preferably (optionally) comprises at least one interface with an Internet protocol (IP, Ethernet, WLAN) according to the known standards. This enables the control device to communicate, preferably via the Internet, with the data processing devices installed remotely from the biomass heating system 1.
  • IP Internet protocol
  • 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, with which an operator can make inputs on the display.
  • the control device 100 can also have a voltage generation unit which generates the voltage for operating the filter device 4.
  • a plurality of sensors are provided for detecting physical and/or chemical variables of the biomass heating system 1. Examples of such sensors are given in relation to the Fig. 2 described in more detail.
  • One of the sensors that may be communicatively connected to the controller 100 may be a boiler temperature sensor 115.
  • a combustion chamber 24 or boiler tubes 32 are at least partially surrounded by a heat exchange medium 38 (see. Fig.2 ), for example (heating) water.
  • the boiler temperature sensor 115 measures or detects the temperature of the heat exchange medium 38 in the boiler 11, preferably at a location that is representative of an average temperature of the heat exchange medium 38 in the boiler 11.
  • the temperature detected by the boiler temperature sensor 115 is communicated to the control device 100 (preferably as a signal, for example as a voltage signal, as a current signal or as a digital signal), whereby the temperature (which may still have to be calculated from the signal, for example the voltage of 1 volt could correspond to 10 degrees Celsius above a zero point) is available to the control device 100 for further processing.
  • the control device 100 preferably as a signal, for example as a voltage signal, as a current signal or as a digital signal
  • 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 recorded sensor data.
  • boiler temperature sensor 115 and the detected temperature may also be applied to other sensors and physical or chemical quantities, in particular to the sensors which are described with reference to Fig. 2
  • sensors for the fuel bed height or ember bed height 86, the lambda probe 112, the exhaust gas temperature sensor 111, the vacuum sensor 113, the heating water temperature sensor 114 can be used as sensors.
  • control device 100 can have sensors with which the (target) voltage that should be present at the electrode 45 of the filter device 100 and the current If that flows in the filter device 4 can be detected.
  • the control device 100 can therefore have current detection means for detecting the current through the electrode 45 or through the various motors.
  • the Control device 100 may have voltage detection means for detecting the filter voltage Vf applied to the electrode 45 or the voltage applied to the respective motor.
  • At least one mechanical, optical or inductive angle of rotation 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.
  • a position sensor can also be provided which can detect the rotational position of the ash auger 71.
  • a limit switch can be provided with which an end stop of the rotating grate on the transition element 255 (i.e. the rotating grate elements 252, 253, 254 are in their horizontal working position) can be detected.
  • 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 screw 71.
  • the cleaning sensor 76 can be provided in such a way that it can detect a rest position of the cleaning mechanism.
  • the cleaning sensor 76 can output a positive signal when the cleaning mechanism is in its rest position (for example, the turbulators are in their lowest position) and is not actively deflected by the motor 72.
  • 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 screw 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 screw 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, conclusions can be drawn about the state of the ash removal.
  • the actuators of the biomass heating system 1 can also be communicatively connected to the control device 100.
  • 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 filter 4 (e.g. its on/off state Sf,), the ash removal 7 or its motor 72, the fuel supply 6 with its rotary valve 61 or its drive motor 66 can be controlled by the control device 100.
  • 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 use a current sensor to detect the current that flows through the at least one motor.
  • the voltage applied to the motor can optionally also be detected and thus the (control) power required for the motor rotation can also be calculated.
  • the filter device 4 is communicatively connected to the control device 100 in such a way that the state, the voltage and/or the current supply to the electrode 45 can be controlled.
  • the control device 100 can be set up in such a way that the on/off state Sf of the electrode 45 and its voltage Vf can be set.
  • the voltage can be set in a range of 10-80 kV, preferably in a range of 10-60 kV.
  • the control device 100 can thus regulate the biomass heating system 1. At least one recorded physical/chemical variable and/or at least one electrotechnical 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, wherein the control response is in turn used to adjust at least one actuator of the biomass heating system 1. Due to the adjustment of the at least one actuator, the physical/chemical processes in the biomass heating system 1 (in particular those of combustion) are influenced, which in turn is controlled by the at least one Sensor is detected. This closes at least one control loop. Due to the large number of possible control tasks of the control device 100, more than one control loop of the biomass heating system can be controlled simultaneously by the control device 100.
  • control of the filter device (voltage control of the electrode 45) can be carried out based on various detected variables.
  • 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.
  • Fig.3 which has the same cut as Fig.2
  • 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 exit 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.
  • Fig.2 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 housing 13 in which water or another fluid heat exchange medium 38 can circulate.
  • a water circulation device 14 with a pump, valves, lines, etc. is provided for the supply and removal of the heat exchange medium.
  • the combustion device 2 has a combustion chamber 24 in which the combustion process of the fuel 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 arranged so as to be rotatable by means of a plurality of bearing axes 81.
  • the primary combustion zone 26 of the combustion chamber 24 is surrounded 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 shows the flow from the secondary air nozzle 291, this flow (this is shown purely schematically) having a swirl induced by the secondary air nozzles 291 in order to improve the mixing of the flue gas.
  • the secondary air nozzles 291 are designed in such a way that they introduce the secondary air (preheated by the combustion chamber bricks 29) tangentially into the combustion chamber 24 with its oval cross-section there. This creates a vortex or swirl-like flow S1 that runs upwards in a roughly spiral or helical shape. In other words, a spiral flow is formed that runs upwards and rotates about a vertical axis.
  • the secondary air nozzles 291 are thus aligned in such a way that they introduce the secondary air - viewed in the horizontal plane - tangentially into the combustion chamber 24.
  • the secondary air nozzles 291 are each provided as an inlet for the secondary air that is not aligned with the center of the combustion chamber.
  • such a tangential inlet can also be used with a circular combustion chamber geometry.
  • All secondary air nozzles 291 are aligned in such a way that they each cause either a right-handed or a left-handed flow.
  • each secondary air nozzle 291 can contribute to the creation of the vortex flows, whereby each secondary air nozzle 291 has a similar alignment.
  • individual secondary air nozzles 291 can also be arranged neutrally (aligned towards the middle) or counter-rotating (with opposite alignment), although this reduces the flow efficiency of the arrangement. can worsen.
  • the combustion chamber bricks 29 form the inner lining of the primary combustion zone 26, store heat and are directly exposed to the fire.
  • the combustion chamber bricks 29 therefore 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 also have 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 in order to cause a swirl in the flow in the primary combustion zone 26 (i.e.
  • the combustion chamber bricks 29 will be explained in more detail later.
  • 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.
  • 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.
  • 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 by the arrows S2 and S3 purely as an example. These vortex flows may also contain slight backflows or other turbulences that are not shown by the purely schematic arrows S2 and S3.
  • the basic principle of the flow characteristics in the combustion chamber 24 is clear and calculable to the person skilled in the art, based on the arrows S2 and S3.
  • candle flame-shaped rotation flows S2 appear, which can advantageously reach up to the combustion chamber ceiling 204, thus making better use of the available space in the combustion chamber 24.
  • the vortex flows are concentrated in the center of the combustion chamber and make ideal use of the volume of the secondary combustion zone 27.
  • the constriction that the combustion chamber nozzle 203 represents for the vortex flows reduces the rotation flows, thereby generating turbulence to improve the mixing of the air-flue gas mixture. Cross-mixing therefore takes place due to the constriction or narrowing by the combustion chamber nozzle 203.
  • the rotational momentum of the flows is at least partially retained above the combustion chamber nozzle 203, which maintains the spread of these flows up to the combustion chamber ceiling 204.
  • 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 their orientation, they induce vortex flows which cause the flue gas-secondary air mixture to rotate 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.
  • the secondary air supply is designed in such a way that it cools the hot combustion chamber bricks 29 by flowing around them and the secondary air itself is preheated in return, whereby the burnout speed of the flue gases is accelerated and the completeness of the burnout is ensured even at extreme partial loads (e.g. 30% of the nominal load).
  • the first maintenance opening 21 is insulated with an insulating material, for example Vermiculite TM .
  • the present secondary combustion zone 27 is designed in such a way that the flue gas is burnt out. The special geometric design of the secondary combustion zone 27 will be explained in more detail later.
  • the flue gas flows into the heat exchanger device 3, which has a bundle of parallel 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 release of the flue gas essentially takes place at the boiler tube walls via forced convection.
  • Spring turbulators 36 and spiral or band turbulators 37 are arranged in the boiler tubes 32 in order to improve the efficiency of the heat exchange device 4. These turbulators 36, 37 are shaped metal parts which are located in the boiler tubes 32 of the heat exchanger 3 and which can be moved back and forth in the boiler tubes 32 in order to clean off combustion residues in these tubes 32.
  • the outlet of the boiler tubes 32 leads into the turning chamber 35 via the turning chamber inlet 34.
  • the turning chamber 35 is sealed off from the combustion chamber 24 in such a way that no flue gas can flow directly from the turning chamber 35 back into the combustion chamber 24.
  • a common transport path is still provided for the combustion residues that can accumulate in the entire flow area of the boiler 11.
  • the filter device 4 is not provided, the flue gas is discharged upwards in the boiler 11.
  • the other case of the optional filter device 4 is described in the Fig.2 and 3
  • the flue gas is then returned to the top of the filter device 4 after the turning chamber 35. (see arrows S5), which in the present case is an electrostatic filter device 4 by way of example.
  • Flow baffles can be provided at the inlet 44 of the filter device 4, which even out the flow of the flue gas into the filter.
  • Electrostatic dust filters also known as electrostatic precipitators in science, are devices for separating particles from gases that are based on the electrostatic principle. These filter devices are used in particular for the electrical cleaning of exhaust gases.
  • electrostatic precipitators dust particles are electrically charged by a corona discharge from a spray electrode and drawn to the oppositely charged electrode (precipitation electrode). The corona discharge takes place on a suitable, charged high-voltage electrode (also known as a spray electrode) inside the electrostatic precipitator.
  • 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.
  • the opposing electrode usually consists of a grounded exhaust pipe section or a cage-like arrangement that is mounted or provided around the electrode.
  • the degree of separation 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 rectified high voltage required for this is provided by the voltage generation unit of the control device 100 (not shown).
  • the electrode 45 consists at least largely of a high-quality spring steel or chrome steel and is held by an electrode holder 43 via an insulator 46, i.e. an electrode insulation 46.
  • the holder 43 for the electrode 45 and in particular the insulator 46 are exposed to dust and dirt, as these are located on or in the flue gas-carrying are arranged in the interior. In this respect, special measures are required to avoid unwanted leakage currents.
  • the cage 48 can be moved by the cleaning device 7 in order to also clean the filter 4. Such a movement can be accompanied by the movement of the turbulators 36, 37.
  • an optimized rod-shaped electrode 45 is held approximately centrally in an approximately chimney-shaped or elongated interior of the filter device 4.
  • This (spray) electrode 45 hangs downwards in the interior of the filter device 4 in a manner capable of oscillating or pendulum-like motion.
  • the electrode 45 can, for example, oscillate back and forth transversely to the longitudinal axis of the electrode 45.
  • 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 mass or earth potential.
  • the flue gas or exhaust gas flowing in the filter device 4, see the 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 the 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 means operation of the boiler 11 or the biomass heating system 1 below these 90%.
  • the indicator line WT3 indicates an example cross-sectional line through the filter device 4, in which the flow is as homogeneous as possible or is roughly evenly distributed over the cross-section of the boiler tubes 32 (among other things due to flow orifices at the inlet of the filter device 4 and due to the geometry of the turning chamber 35).
  • a uniform flow through the filter device 3 or the The last boiler pass minimizes the formation of streaks and thus also optimizes the separation efficiency of the filter device 4 and the heat transfer in the biomass heating system 1.
  • 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 cut to size during manufacture using a laser.
  • the flue gas flows through the turning chamber 34 into the inlet 44 of the filter device 4.
  • the filter device 4 is advantageously fully integrated into the boiler 11, whereby the wall surface facing the heat exchanger 3 and flushed by the heat exchange medium is also used for heat exchange from the direction of the filter device 4, whereby the efficiency of the system 1 is further improved. At least part of the wall of the filter device 4 can thus be flushed with the heat exchange medium, whereby at least part of this wall is cooled with boiler water.
  • the cleaned exhaust gas flows out of the filter device 4, as indicated by the arrows S7.
  • part of the exhaust gas is returned 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 "Rezi” or “Rezi gas” for short.
  • the remaining part of the exhaust gas is led out of the boiler 11 via the exhaust gas outlet 41.
  • the arrow S8 indicates a flue gas flow or turbulence in which flue gas does not exit directly from the filter 4, but in a dead volume of the filter 4 (which is located behind the outlet 47 in terms of flow, so that it is not in the Main flow S6, S7 through the filter 4), a reversal or vortex flow is formed and can flow in particular over the insulator 46. Soot and ash can thereby be deposited on the insulator. In addition to non-mineral combustion residues, carbon-containing combustion residues can also be deposited on the insulator, which impairs the function of the insulator. More details on this are given in relation to the Fig.9 explained.
  • An ash removal system 7 is arranged 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 at the side via an ash removal screw 71.
  • Fig.2 and Fig.3 further sensors are shown which are at least communicatively connected to the control device 100.
  • the sensors record (physical and/or chemical) variables of the biomass heating system 1.
  • An exhaust gas temperature sensor 111 is provided downstream of the outlet of the heat exchanger 3. This measures a 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 filtering.
  • a conventional temperature sensor or a PT-100 or PT-1000 sensor can be used as the exhaust gas temperature sensor 111, which is provided in the wall of the exhaust gas duct or protrudes into the exhaust gas duct. With the help of the exhaust gas temperature sensor 111, the temperature of the exhaust gas can be determined in degrees Celsius.
  • the exhaust gas temperature sensor 111 can be provided, for example, 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 in order to ensure the accuracy of the measurement or to provide measurement redundancies. For example, an exhaust gas temperature sensor 111 can be provided directly after the outlet of the heat exchanger 3 and a further exhaust gas temperature sensor 111 can be provided after the filter device 4.
  • At least one lambda probe 112 is provided. It is intended 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 after the combustion chamber 24.
  • a lambda sensor can usually 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 ⁇ (ratio of combustion air to fuel) can be determined and adjusted. Two measuring principles can be used: voltage of a solid electrolyte (Nernst sensor) and change in resistance of a ceramic (resistance sensor).
  • the lambda probe 112 can measure the oxygen content of the exhaust gas (for example in vol%), and thus an optimal mixture can be regulated at the boiler 11, preferably by means of an AI model, in order to prevent an excess supply 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.
  • Fig. 2 Two possible installation positions are proposed. One is located next to the inlet 33 of the heat exchanger 3 (cf. 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).
  • the lambda sensor 112 can be installed at any position in the Flue gas duct of the boiler 11 must be provided as long as it can measure the exhaust gas or flue gas.
  • the signal from the lambda probe 112 can be used to control, for example, the supply of primary air to the combustion chamber and the amount of fuel supplied via the control device 100.
  • An (optional) vacuum sensor 113 or pressure difference sensor 113 is also provided.
  • This vacuum sensor 113 measures the (vacuum) pressure in the combustion chamber 24, for example in the unit [mPas], or the differential pressure of the combustion chamber 24 to the ambient air pressure.
  • the primary air (and optionally the secondary air) is sucked into the combustion chamber 24 for combustion via the vacuum.
  • 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 in the flow of a conventional water circulation device 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.
  • 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).
  • a fuel bed height sensor 116 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.
  • a quantity of fuel for example wood chips
  • An example of such a sensor in mechanical design is shown in the EP 3 789 670 B1 in relation to their Fig. 17 and 18 described, with reference Alternatively, the fuel bed height sensor 116 can be provided, for example, as an ultrasonic sensor.
  • a combustion chamber temperature sensor 117 is also 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 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.
  • the locations of the sensors of the Fig. 2 and 3 may also deviate from the locations shown, as deemed appropriate by the expert.
  • the combustion chamber temperature may also be recorded at a different location.
  • the combustion chamber 24 and also the geometry of the filter device 4 and the upstream turning chamber 35 of this embodiment were calculated using CFD simulations. Practical experiments were also carried out to confirm the CFD simulations. The starting point for the considerations were calculations for a 100 kW boiler, although a power range of 20 to 500 kW was taken into account.
  • the flow processes can be laminar and/or turbulent, accompanied by chemical reactions, or it can be a multi-phase system.
  • CFD simulations are therefore well suited as a design and optimization tool.
  • CFD simulations were used to optimize the flow parameters in such a way that the above-mentioned objects of the invention are achieved.
  • 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 defined primarily 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.
  • 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, a minimization of the combustion volume, a reduction in excess air and the recirculation ratio (efficiency, operating costs), a reduction in CO emissions and NOx emissions, a reduction in temperature peaks (fouling and slagging) and a reduction in flue gas velocity peaks (material stress and erosion).
  • 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 which meets the above-mentioned requirements for biomass heating systems over a wide power range of, for example, 20 to 500 kW.
  • 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.
  • 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 be defined based on the following basic parameters: A volume with an oval horizontal base measuring 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).
  • 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 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%.
  • 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.
  • 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 recognized in the present case.
  • combustion chamber 24 is provided without dead corners or dead edges.
  • 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 This horizontal cross-section can also preferably represent the base area of the primary combustion zone 26 of the combustion chamber 24.
  • the primary combustion zone 24 can have an approximately oval-cylindrical volume.
  • the side walls and the base area (the grate) of the primary combustion zone 26 can be perpendicular to one another.
  • 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.
  • 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.
  • the nozzle 203 between the primary combustion zone 26 and the secondary combustion zone 27 is designed as an oval or approximately circular constriction in order to optimize the flow conditions.
  • the previously explained swirl of the Flow in the primary combustion zone 26 leads to a helical upward flow path, whereby an oval or almost circular nozzle promotes this flow path and does not interfere with the usual rectangular nozzles.
  • This optimized nozzle 203 bundles the upward flowing air and ensures a uniform inflow into the secondary combustion zone 27. This improves the combustion process and increases efficiency.
  • 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, according to CFD calculations ensures an evening out 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. Parallel or straight combustion chamber walls without a taper (so as not to impede the flue gas flow) are common in the prior art.
  • the diversion of the flue gas flow in front of the tube bundle heat exchanger is designed in such a way that an uneven flow to the tubes is avoided as best as possible, whereby temperature peaks in individual boiler tubes 32 can be kept low. As a result, the efficiency of the heat exchange device 4 is improved.
  • 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.
  • the exhaust gas temperature is thus reduced and the efficiency increased.
  • the flow distribution is particularly at the Fig.3 shown indicator line WT1 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 orifices at the inlet of the filter device 4 and due to the geometry of the turning chamber 35).
  • 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 renewed ignition of the fuel.
  • the ignition device 201 can be a glow plug.
  • the ignition device is advantageously arranged in a stationary manner and horizontally offset to the side from the place where the fuel is poured in.
  • a lambda probe (not shown) can be provided (optional) after the flue gas exits the filter device (i.e. after S7).
  • the lambda probe enables 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 different fuel qualities, a high level of efficiency and a higher level of effectiveness can be achieved.
  • 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, which is 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 (not shown in detail) based on various sensor-detected measured values and associated air valves 52.
  • a combustion chamber nozzle 203 which separates the primary combustion zone 26 from the secondary combustion zone 27 and accelerates and concentrates the flue gas flow. This means that the flue gas flow is better mixed and can burn more efficiently in the secondary combustion zone 27.
  • the area ratio of the combustion chamber nozzle 203 is in a range of 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).
  • 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 made with the dimensions listed above of the Fig.4 and 5 However, this is not necessarily the case.
  • 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 structure, which, among other things, facilitates production and maintenance. Maintenance is made easier in particular by the possibility of removing individual combustion chamber bricks 29.
  • Three further combustion chamber stones 29 are provided as the upper end, with the annular nozzle 203 being supported by two support stones 264 which are placed in a form-fitting manner on the upper ring 263. All support surfaces 260 are provided with grooves 261 either for suitable projections 262 and/or for the insertion of suitable sealing material.
  • 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.
  • 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, which thus advantageously seals this transition automatically and advantageously during operation of the biomass heating system 1.
  • the (optional) openings for the recirculation nozzles 291 are provided in the middle ring of the combustion chamber stones 29.
  • three rings of combustion chamber bricks 29 are provided, as this is the most efficient way of manufacturing and maintaining them.
  • two, four or five (2, 4 or 5) such rings can be provided.
  • the combustion chamber stones 29 are preferably made of high-temperature silicon carbide, which makes them very wear-resistant.
  • the combustion chamber bricks 29 are provided as shaped bricks.
  • the combustion chamber bricks 29 are shaped in such a way that the internal volume of the primary combustion zone 26 of the combustion chamber 24 has an oval horizontal cross-section, whereby an ergonomic shape avoids dead corners or dead spaces through which the primary air usually does not flow optimally, as a result of which the fuel present there is not burned optimally. Due to the shape of the combustion chamber bricks 29, the flow of primary air and consequently the efficiency of combustion is improved.
  • the oval horizontal cross-section of the primary combustion zone 26 of the combustion chamber 24 is preferably a point-symmetrical 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 by means of CFD simulation and practical tests.
  • Fig.8 shows a top view of the rotating grate 25 from the perspective of the section line A1 of the Fig.2 to illustrate various basically possible operating states of the rotating grate 25.
  • the supervision of the Fig.8 can preferably be designed with the dimensions listed above. However, this is not necessarily the case.
  • the rotating grate 25 has the base plate 251 as a base element.
  • a transition element 255 is provided in a roughly oval-shaped opening in the base plate 251, which bridges a 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.
  • the rotating grate 25 is thus provided as a rotating grate with three individual elements, ie 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.
  • the rotating grate elements 252, 253 and 254 are flat and heat-resistant metal plates, for example made of a metal cast, 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.
  • the rotating grate elements 252, 253, 254 can have complementary and curved sides, wherein the second rotating grate element 253 preferably has concave sides towards 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 towards the second rotating grate element 253. This improves the breaking function of the rotating grate elements, since the length of the fracture is increased and the forces acting to break it (similar to a pair of scissors) act in a more targeted manner.
  • the rotating grate 25 has an oval combustion surface 258, which is more favorable for the fuel distribution, the air flow through the fuel and the combustion of the fuel 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 onto the rotating grate 25 from the side (see arrow E of the Fig.9 , 10 and 11 ).
  • the fuel supply can take place from a direction that is parallel to a longer central axis (main axis) of the oval combustion surface of the rotating grate 25.
  • the first rotary grate element 252 and the third rotary grate element 254 can preferably be designed identically in their combustion surface 258. Furthermore, the first rotary grate element 252 and the third rotary grate element 254 can be identical or structurally identical to one another. This is the case, for example, in Fig.9 , wherein the first rotating grate element 252 and the third rotating grate element 254 have the same shape.
  • the second rotating grate element 253 is arranged between the first rotating grate element 252 and the third rotating grate element 254.
  • the rotating grate 25 is provided with an approximately point-symmetrical oval combustion surface 258.
  • 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.
  • the rotating grate 25 can have an approximately oval combustion surface 258 which is axially symmetrical with respect to a center axis of the combustion surface 258.
  • the rotating grate 25 can have an approximately circular combustion surface 258, although this entails minor disadvantages in the fuel supply and distribution.
  • two motors or drives 231 of the rotary mechanism 23 are provided, with which the rotary grate elements 252, 253 and 254 can be rotated accordingly.
  • rotation angle sensors 259 (shown separately here) are provided, preferably on the rotary axes 81, for detecting the rotation angle or the rotation position of the rotary axes 81.
  • the position of the rotary grate elements 252, 253, 254, for example in relation to the horizontal or rest position thereof, can be determined using the rotation angle sensors 259. More details on the special function and the advantages of the present rotary grate 25 will be given later with reference to the Figures 9 , 10 and 11 described.
  • pellet heating systems 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 above the ash melting point. The ash then becomes soft, sticks together and forms solid, dark-colored slag after cooling. This process, also known as sintering, is undesirable in the biomass heating system 1, since the accumulation of slag in the combustion chamber 24 can lead to a malfunction: it switches off.
  • the combustion chamber 24 usually has to be opened and the slag has to be removed.
  • the ash melting point depends largely on the fuel used. Spruce wood, for example, has an ash melting point of around 1200 °C. But the ash melting point of a fuel can also vary greatly. The behavior of the ash in the combustion process changes depending on the amount and composition of the minerals contained in the wood.
  • Another factor that can influence the formation of slag is the transport and storage of the wood pellets or wood chips. These should be as undamaged as possible when they reach the combustion chamber 24. If the wood pellets have already crumbled when they enter the combustion process, this increases the density of the ember bed. This results in greater slag formation.
  • the transport from the storage room to the combustion chamber 24 is particularly important here. Particularly long distances, as well as bends and angles, lead to damage to the wood pellets.
  • One problem is that slag formation cannot be completely avoided due to the large number of influencing factors described above.
  • the Figures 9 , 10 and 11 show 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 necessarily the case.
  • This view shows the rotating grate 25 as a free-standing insert part with rotating grate mechanism 23 and drive(s) 231.
  • the rotating grate 25 is mechanically designed in such a way that it can be prefabricated individually in the manner of a modular system and inserted and installed as an insert part in a provided elongated opening of the boiler 11. This also makes it easier to maintain this part, which is susceptible to wear.
  • the rotating grate 25 can therefore preferably be designed in a modular manner, whereby it can be removed and reinserted quickly and efficiently as a complete part with rotating grate mechanism 23 and drive 231.
  • the modularized rotating grate 25 can therefore also be assembled and disassembled using quick-release fasteners.
  • the rotating grates of the state of the art are usually permanently mounted and thus difficult to maintain or assemble.
  • 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.
  • 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.
  • At least one rotational position sensor or rotation angle sensor 259 or a position sensor 259 can be provided, which can detect a (rotational) position of the rotation axis 81 and thus of the rotating grate elements 252, 253, 254.
  • the rotational position sensor 259 can, for example, be a known magnetic angle meter or rotary encoder that outputs an absolute angle. These sensors have an axis whose rotation is detected, whereby, for example, a digital signal, 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).
  • the individual components of the rotating grate mechanism 23 are designed to be exchangeable.
  • the gears are designed to be plugged on. This makes maintenance easier and also a change of side of the mechanics during assembly, if necessary.
  • 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 be rotated by at least 90 degrees, preferably at least 120 degrees, even more preferably 170 degrees around 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 designed 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 that the first rotating grate element 252 and the second rotating grate element 243 can be rotated together 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 gear wheels.
  • the rotating grate elements 252, 253 and 254 can preferably be manufactured as a cast grate with a laser cut to ensure exact shape retention. This is particularly important in order to define the air flow through the fuel bed 28 as precisely as possible and to avoid disruptive air currents, for example air streaks at the edges of the rotating grate elements 252, 253 and 254.
  • 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.
  • Fig.9 now shows the rotating grate 25 in the 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.
  • the uniform arrangement of the plurality of openings 256 ensures 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.
  • 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 in question can be efficiently cleaned.
  • Two rotation position sensors 259 are also indicated, which can detect the rotation position of the bearing axes 81. These rotation position sensors 259 can be magnetic-inductive sensors, for example. This serves to control the rotation position of the three rotating grate elements 252, 253, 254.
  • 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).
  • ember maintenance mode i.e. in a second state.
  • 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 retained 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.
  • no external ignition is required to restart operation (this saves up to 90% ignition energy).
  • a further consequence is a reduction in wear of the ignition device (for example an ignition rod) and a saving in electricity.
  • ash cleaning can advantageously take place during operation of the biomass heating system 1.
  • Fig.10 also shows a state of ember preservation during a (often sufficient) partial cleaning. This allows the operation of system 1 to be carried out more continuously, which means that, in contrast to the usual full cleaning of a conventional grate, no lengthy complete ignition is required, which can take several tens of minutes.
  • FIG.10 Grate lips 257 of the second rotating grate element 253 (on both sides) can be seen.
  • These grate lips 257 are designed in such a way that the first rotating grate element 252 and the third rotating grate element 254 rest on the top of the grate lips 257 when closed, and thus the rotating grate elements 252, 253 and 254 are provided with no gaps between them and are thus provided to seal. This prevents air streaks and undesirable primary air flows through the ember bed. This advantageously improves the efficiency of the combustion.
  • Fig. 11 shows the rotary grate 25 in the state of universal cleaning or in an open state (ie a third state), which is preferably carried out during a plant shutdown. All three rotary grate elements 252, 253 and 254 are rotated, with the first and second rotary grate elements 252, 253 preferably being rotated in the opposite direction to the third rotary grate element 254 (see arrows D2). This means that on the one hand the rotary grate 25 is completely emptied, and on the other hand the slag is now broken up at four odd outer edges. In other words, an advantageous 4-fold crusher function is realized.
  • Fig.9 on the geometry of the outer edges explained also applies to Fig.10 .
  • the present rotating grate 25 realizes, in addition to the normal operation (cf. Fig.9 ) advantageously two different types of cleaning (cf. Fig.10 and 11 ), whereby the partial cleaning is a cleaning during the operation of the system 1 allowed.
  • the simple mechanical design of the rotating grate 25 makes it robust, reliable and durable.
  • a problem with the movements shown with arrows D1 and D2 is the possibility of the movement being blocked by combustion residues and also by undesirable contents in the fuel (for example nails, metal splinters or similar). Such a blockage during rotation could, without the blockage detection described here, lead to damage to the drive mechanism or the motors 231. Conversely, however, the rotating grate 25 should be able to carry out its crushing function described above, i.e. break slag, and at the same time not be damaged by "harder” or "more permanent” blockers.
  • Fig. 12 shows a general operating procedure of the biomass heating plant 1 for one combustion cycle.
  • a combustion cycle takes place during combustion operation of the biomass heating system 1. Depending on the energy requirement, more than one combustion cycle can take place one after the other during combustion operation. In this way, several combustion cycles can be carried out during combustion operation.
  • biomass heating system 1 can also be operated in stand-by mode, in which no combustion takes place and the biomass heating system waits to be used.
  • the combustion process can first be prepared in the optional step S50.
  • the biomass heating system can be initialized mechanically and electronically.
  • the operating system of the control device 100 can be started up, a self-test of the electronics can be carried out and/or the rotating grate elements 252, 253, 254 can be turned (opened) by a predetermined angle in order to remove any deposits on the grate and to test the mechanics before a combustion process.
  • 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.
  • the mechanical boiler cleaning via tubulators), the ash removal and the optional electrostatic filter cleaning can be operated for a predefined time (e.g. 30 seconds).
  • the air paths of the boiler 11 can also be flushed.
  • the biomass heating system is flushed with air by opening the primary air and secondary air valves. Then the air dampers are closed and the flue gas recirculation line is flushed.
  • the combustion chamber 24 is filled with fuel.
  • the fuel is fed via the fuel feed 6 onto the rotating grate 25 until a predetermined fuel bed height is reached.
  • the fuel bed height is the fuel bed height sensor 116.
  • the fuel bed height sensor 116 is, for example, a mechanical level flap 86 with a rotation angle sensor.
  • step S52 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.
  • the valves or valve positions can be set when igniting the fuel in such a way that they promote the ignition of the fuel.
  • the fan 15 is also activated in order 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 regulated in the combustion chamber (e.g. 75 Pa).
  • step S53 the stabilization of the combustion.
  • the combustion process should gradually transition to a stationary state in which equilibrium prevails from a thermodynamic point of view. If the combustion temperature increases to a predetermined value, for example 400°C, step S53 is completed.
  • step S54 the stabilized combustion and the actual heating operation.
  • the power output or the combustion intensity is regulated 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.
  • a fuel-dependent Power control can be used.
  • 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.
  • step S55 the combustion chamber 24 and in particular the rotating grate 25 are burned out.
  • the fuel supply is stopped and the combustion chamber temperature drops.
  • the fuel residues on the rotating grate 25 are burned.
  • the positions of the valves 52 and the fan 15 can be adjusted accordingly.
  • the rotating grate 25 is cleaned by turning or opening the rotating grate elements accordingly.
  • step S55 the burnout, the primary air supply can be increased (for example, the valves for regulating the primary air supply can be opened completely) in order to accelerate the burning process in the boiler and in particular in the combustion chamber 24 and to keep this step, or this phase of the boiler cycle, as short as possible.
  • the carbon-containing residues in the combustion chamber 24 should therefore be burned as quickly and completely as possible.
  • the temperature in the combustion chamber 24 usually increases again briefly.
  • step S55 the process can be deactivated (END), or the process can start again (after some time) and then go to step S50, whereupon a new combustion cycle or heating cycle begins.
  • Fig. 13 shows a performance diagram of an exemplary cycle of the combustion operation of the biomass heating system 1 from ignition (S52) to burnout (S55).
  • ignition S52
  • burnout S55
  • the processes of preparation (S50) and filling (S50) are omitted here
  • the arrow S52 shows the process of (re)ignition of the fuel.
  • the fuel catches fire and the output increases quickly due to the unused fuel.
  • the combustion process is stabilized, whereby the output is stabilized to the desired target output value after some fluctuation.
  • the (stabilized) combustion process takes place, whereby a relatively constant output of the boiler 11 occurs.
  • the biomass heating system burns out with the associated output peak, whereby the start of the increase in the primary air supply in Fig. 13 is indicated with "I". This increased primary air supply burns the unburned fuel residues, thus preventing unburned fuel from being cleaned out of the boiler 11.
  • the boiler temperature and the temperature in the combustion chamber 24 increase in roughly the same way as the boiler output. In this respect, there are temperature peaks or maxima at the beginning of the combustion cycle and at the end of the combustion cycle.
  • burnout S55 the increased temperature in the boiler heats up carbon-containing residues and deposits on the inside walls and parts of the boiler again and preferably burns them off completely.
  • the ash Since the ash is an amorphous, ceramic-like material mixture, it does not have a clearly defined melting point, but softens continuously over a wide temperature range. The viscosity decreases with increasing temperature, the ash becomes sticky, the fine ash grains agglomerate and sinter into larger chunks, the ash begins to creep and finally even to flow.
  • slag is always created during a combustion process when temperatures in the embers reach above the ash melting point.
  • the ash then becomes soft, sticky and, after cooling, forms the well-known solid, dark-colored slag, which can be porous/brittle/crumbly to glassy hard.
  • temperatures and their associated viscosities can only be predicted with great uncertainty, as the temperature and melting behavior of the fuel (which is very variable) or mixture of substances for combustion is extremely complex. Even small changes in the proportions of substances can have a strong influence on the softening point if the mixture forms a eutectic. In general, temperatures increase with increasing carbonization. Some substances (such as some potassium, aluminum, sodium, magnesium and silicon compounds) are known to massively reduce the softening point. This is particularly evident in stalk-like biomasses (straw and grass), which contain such substances in increased concentrations and are among the fuels with the lowest ash softening temperatures.
  • the cooling and solidification of the slag occurs not only in terms of time when the temperature changes in a combustion cycle, but also in terms of space when it moves from the hot zone of the combustion chamber 24 into the cold edge areas or into the downstream heat exchanger 4 and also into the filter device 4.
  • caking forms which hinders and worsens the heat transfer and which increases the flue gas side pressure loss of the furnace. This is referred to as "slagging" of the furnace.
  • slag can block the movement of the grate, or the openings for the primary air supply, i.e. the combustion air that flows through the grate from below, can become clogged.
  • the devices for cleaning and transporting the ash can even be blocked by large, hard lumps of slag.
  • Fig. 14 shows a triggering process with which a cleaning of the boiler can be initiated.
  • This triggering process can, for example, be carried out cyclically by the control device 100, or this triggering process can be carried out automatically when the operating state of the boiler 11 changes to state S55: burnout.
  • step S70 a determination is made as to whether the boiler 11 is in the burnout state S55 or not. This can either be queried and determined cyclically ("No"), or this determination is automatically assessed as fulfilled when the operating state S55 burnout (which is brought about by the control device 100) is executed.
  • a predefined threshold BTS can be set to 180 degrees Celsius, for example. This threshold ensures that cleaning is not carried out with combustion residues that are still oxidizing. Furthermore, for the Cleaning ensures that the slag is less viscous or rather fragile or brittle, which makes cleaning more efficient.
  • cleaning of the boiler 11 can be carried out.
  • cleaning can include rotating the rotating grate elements 252, 253, 254 by means of the motors 231.
  • cleaning can include moving the cleaning mechanism including the cleaning screw 71 and the turbulators 37.
  • cleaning of the boiler 11 preferably includes cleaning of 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.
  • Fig. 15 shows a further development of the triggering procedure of the Fig. 14 , whereby a blockage detection of the cleaning mechanism controlled by the motor 72 (including ash screw and preferably turbulators) can be detected.
  • the cleaning mechanism controlled by the motor 72 including ash screw and preferably turbulators
  • the position sensor 75 detects in step S73 whether the cleaning mechanism is in the rest position or not. If, for example, the cleaning mechanism has become jammed or seized due to a foreign body and is blocked, it usually does not return to the rest position. In this respect, such a blockage can be detected with the position sensor 75.
  • step S73 If the determination in step S73 is Yes, the cleaning mechanism has returned to the rest position and there is no blockage.
  • step S73 If the determination in step S73 is no, the cleaning mechanism has not returned to the rest position (which it should do due to the weight of the turbulators) and a blockage is positively detected or recognized (step S74).
  • a corresponding error message can be stored in the system, or a user can be informed of the blockage via a user interface (for example via a touch screen).
  • the boiler 11 can also stop operation for safety reasons in response to the detected blockage.
  • Fig. 16 shows an (optional) cleaning optimization procedure to ensure a cleaned and unblocked initial state of the boiler 11 before the start of a combustion cycle, if necessary.
  • step S80 it is determined whether the start of a combustion cycle is requested or not.
  • a request can be made manually by a user by input at a user interface, for example.
  • Such a request can also be made automatically, for example by requesting heating power or by specifying a predefined number of heating cycles which are run one after the other.
  • the position sensor 75 detects in step S81 whether the cleaning mechanism is in the rest position or not. If, for example, the cleaning mechanism has become jammed or seized due to a foreign body and is blocked, it usually does not return to the rest position. In this respect, such a blockage can be detected with the position sensor 75.
  • step S81 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 carried out.
  • Step S81 If the determination in step S81 is no, the cleaning mechanism has not returned to the rest position (which it should have done due to the weight of the turbulators) and a blockage is positively detected or recognized. As a result Step S83 is then carried out in order to release the blockage by driving or moving the mechanism.
  • step S82 a query is made as to whether or not cleaning was already carried out during the last burnout S55 of the boiler 11.
  • a so-called “flag” can be activated in software, which is reset again, for example, when steps S54 (or S 53, etc.) are carried out.
  • step S84 queries whether the combustion chamber temperature is less than the predefined threshold BTS or not.
  • step S84 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 carried out.
  • step S84 If the result of step S84 is yes, the boiler is cleaned in step S83.
  • the temperature of the boiler 11 has therefore fallen to a level that allows cleaning, and the time loss caused by cleaning the boiler 11 must also be accepted, since the boiler is already "colder" anyway.
  • step S83 the process proceeds to step S85.
  • Fig. 17a shows a cleaning process of the boiler 11.
  • 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 certain time BM.
  • This time (duration) is defined such that the cleaning mechanism covers a certain 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 to 30 seconds, for example.
  • step S91 following step S90 the current supply to the motor 72 is interrupted for a predefined pause time P1.
  • This pause time P1 can be, for example, 10 seconds.
  • step S92 following step S91 it is determined whether or not a predefined number WH of executions of steps S90 and S91 has taken place, i.e. whether or not a predefined number WH of iterations of the loop with steps S90 and S91 has been carried out.
  • This predefined number WH can be 5, for example.
  • step S92 If the result of step S92 is No, steps S90 and S91 are repeated.
  • step S92 If the result of step S92 is Yes, the process proceeds to step S93.
  • step S93 If the result of step S93 is yes, the process is terminated. Blockage-free cleaning has been carried out.
  • step S94 is identical to that described in relation to step S74.
  • the method therefore ends with an error message.
  • 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.
  • Fig. 17b shows a first anti-blockade procedure, which is a further development of the procedure of Fig. 17a is.
  • step S95 the motor 72 is energized for a predefined energization time BM2 in order to release the blockage.
  • the energization time BM2 is preferably longer than the energization time BM1 in order to increase the force acting on the blockage.
  • step S95 After the power supply in step S95, it is again detected, as already explained, whether the cleaning mechanism has returned to the rest position or not.
  • step S97 Either the process is terminated with an error message or an error, or it is switched to an anti-blockage process 2, which is described below with regard to the Figures 17c and 17 d is explained in more detail.
  • Figures 17c and 17d show a second anti-blockade procedure in training to the procedures of Fig. 17a and/or 17b.
  • 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.
  • the cleaning mechanism is therefore subjected to greater stress, but only in the case where an attempt with lower power has failed.
  • step S99 the check described above is performed again.
  • step S99 If the result of step S99 is Yes, the blockage is released and the cleaning process is terminated.
  • step S99 If the result of step S99 is no, the blockage still exists. As a result, the power supply is interrupted or paused in step S100 for a predefined pause time P2. This gives the mechanism time to return to the rest position on its own.
  • step 101 If the result of step 101 is Yes, the blockage is cleared and the cleaning process is terminated.
  • step S101 If the result of step S101 is no, the blockage still exists.
  • the motor is energized in short intervals BI in step S102.
  • Such intervals can consist, for example, of 2 seconds of energization, 2 seconds of pause, which is repeated several times, for example two to eight times.
  • the cleaning mechanism is moved jerkily or the cleaning mechanism is shaken, for example to crumble brittle slag or to release jams. It is preferred that the intervals are repeated at least twice.
  • step 103 the check described above is carried out again.
  • step 103 If the result of step 103 is Yes, the blockage is cleared and the cleaning process is terminated.
  • step S103 If the result of step S103 is no, the blockage still exists.
  • the motor 72 is (optionally) moved for a predefined energization time BM4, for example 2 seconds, in a second direction of rotation that 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).
  • step S105 (cf. S102) in short intervals BI.
  • step 106 the check described above is carried out again.
  • step 106 If the result of step 106 is Yes, the blockage is cleared and the cleaning process is terminated.
  • step S106 If the result of step S106 is no, the blockage still exists. In this case, the blockage is so persistent that step S107 initiates a (non-automatic) resolvable) blockage is detected (see S74) and the procedure is terminated.
  • Fig. 18 shows a blockage detection method for the rotating grate 25 of the biomass heating system 1.
  • This blockage detection method is carried out when a partial or complete cleaning of the rotating grate 25 is carried out, thus when at least one of the motors 231 is energized. This is checked in step S110.
  • step S111 a current first angle of rotation Dd1 is detected (and stored) by means of the rotational position sensor 259.
  • a predefined waiting time WD is waited for.
  • the motor 231 continues to be energized, so the associated rotating grate element 252, 253, 254 or the rotation axis 81 should continue to rotate if the rotating grate is not blocked.
  • a current second angle of rotation Dd2 is detected (and stored) by means of the rotational position sensor 259.
  • two angles of rotation Dd1 and Dd2 are now detected and stored at a defined time interval.
  • step D114 it is checked whether one of the two end angles has been reached or not.
  • the end angles are predefined end angles relating to the angle of rotation of the respective rotating grate element 252, 253, 254, which represent the mechanically maximum possible end angle or end stop.
  • a rotating grate element can usually be rotated in a rotation range from 0 degrees (horizontal end position) to 170 degrees (rotated end position during cleaning).
  • the rotating grate element 252, 253, 254 is still in the middle of rotation.
  • a blockage can now be detected by comparing the detected angles of rotation Dd1 and Dd2, see step 115. This comparison essentially determines whether the angles of rotation Dd1 and Dd2 differ so much that an unblocked movement can be assumed. If the angles of rotation Dd1 and Dd2 do not differ or do not differ sufficiently, then a blockage can be assumed.
  • step S115 can be determined, for example (other mathematical methods are of course also immediately apparent to the person skilled in the art) with the following comparison: I Dd2-Dd1 I > threshold value Sd.
  • the threshold value Sd is a lower rotation angle (speed) value that is determined in advance, for example by 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 structural and electrical specifications as the minimum target value).
  • the difference Dd2 and Dd1 represents the rotational (angular) speed detected by the sensor based on the time interval WD, which is determined by step S112.
  • the method of Fig. 18 a rotational speed of the rotation axis 81 ((Dd1 - Dd2) per unit of time WD including the calculation time in the control device or the electronic running times. With the (optional) calculation of the amount from the difference Dd2 - Dd1, it is irrelevant in which direction the rotating grate element 252, 253, 254 is rotated.
  • the difference is 0.2 degrees. If the predefined time WD is now 0.1 second, the recorded 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 recorded that the rotating grate element 252, 253, 254 is moving sufficiently quickly 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).
  • step S115 if the comparison in step S115 has a negative result (ie 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.
  • the method can be carried out instead of the step in Fig. 18 shown step directly into the realization "rust blocked" (see p. 118).
  • step S116 an error count counter FE is increased by +1. Subsequently, in step S117, it is checked whether the current error count FE is greater than a predefined maximum error count FEma.
  • the predefined maximum error count FEma can be 5, for example.
  • step S116 If the result of step S116 is No, the process returns to step S111.
  • step S116 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 then 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.
  • the direction of rotation of the rotating grate element 252, 253, 254 can be reversed briefly to release 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, which allows three attempts for example.
  • Fig. 19 shows a diagram with the procedure 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 process step in response to a detected blockage.
  • 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.
  • 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.
  • the arrow labeled "rotation of an axis” refers to a curve section in which the angle of the 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 used when the rotating grate element 252, 253, 254 is opened.
  • a first angle of rotation Dd1 and a second angle of rotation Dd2 are recorded at a time interval WD (S111, S112, S113).
  • the final angle (in this case the minimum angle 0) is not reached (S 114). The procedure is continued.
  • blockage refers to the beginning of a curve section in which the angle of the axis 81 no longer decreases. From this point on, the rotating grate element 252, 253, 254 is blocked, for example, a hard lump of slag has become jammed.
  • step S115 Since the first angle of rotation Dd1 and the second angle of rotation 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). The process therefore proceeds to step S116.
  • the error count counter is increased by 1. It should be noted that, although this is in 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 run of the loop of the Fig. 18 with steps S111 to S117. In this example, the predefined maximum number of errors Fma is preset or pre-stored to "2". In this respect, the loop of the Fig.
  • step S117 in the third iteration is an exit from the loop (S117: Yes), with the result "Rust blocked” (S118).
  • a blockage of the rotating grate is reliably detected without additional sensors or special measures (for example, an additional current sensor for the current supply to the motor).
  • the time WD can be used to define the breaking force with which the Rotating grate tries to break up slag when rotating. The longer this time WD is, the longer the motor is energized in the event of a blockage.
  • the maximum number of errors Fma defines the number of iterations of the loop S111-S117 until a reaction occurs and thus the time in which the motor works against the blockage.
  • the error counter (S116, S117) prevents a too fast reaction to only minor movement blockages, which occur more frequently.
  • the rotation in Fig. 19 While the speed is shown linearly, in practice it can be non-linear (depending on the type and amount of slag).
  • the threshold Sd can therefore be used to set very sensitively which movement speed is still permissible and which is no longer permissible.
  • the process can be set specifically to the requirements of a rotating grate using the parameters Sd, WD and Fma, which has an important function in breaking up slag; however, without itself being damaged by overloading.
  • the rotating grate 25 of the Fig. 9 to 11 is shown without the cleaning device, but can be combined at any time with a cleaning device not shown.
  • the rotating grate 25 is described as having three rotating grate elements 252, 253, 254.
  • the rotating grate 25 can also have just one rotating grate element 252, or two rotating grate elements 252, 253.
  • a rotating grate 25 with a plurality of rotating grate elements is conceivable.
  • the present disclosure is not limited to a specific number of rotating grate elements 252, 253, 254.
  • the rotation of the rotating grate elements can also be done differently with regard to cleaning than with regard to Figures 9 to 11 described.
  • the present disclosure is therefore not limited to the specific manner of rotation (and the states created thereby) of the rotating grate elements.
  • only the middle rotating grate element 253 can be rotated for partial cleaning.
  • the rotating grate elements 252, 253, 254 can be rotated individually or together to switch between the three explained states.
  • each rotating grate element 252, 253, 254 can have at least one known cleaning device.
  • one rotating grate element or several rotating grate elements from the total number of rotating grate elements of the rotating grate 25 can also have no cleaning device.
  • a cleaning device can be additionally provided, as is known from the in-house state of the art of EP21 218 434.5 is known, although this is not explained in detail here.
  • 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.
  • a blockage can include a releasable or a non-releasable mechanical blockage.
  • a blockage can 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 lead to damage to the mechanism, although the drive or torque would be sufficient to overcome the blockage itself.
  • the methods described herein are primarily described with respect 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.
  • a linear movement can also be detected instead of a rotating movement.
  • the recirculation device 5 is described with a primary recirculation and a secondary recirculation.
  • the recirculation device 5 can also have only a primary recirculation and no secondary recirculation in its basic configuration.
  • the components required for the secondary recirculation can be completely omitted, for example the recirculation inlet channel divider 532, the secondary recirculation channel 57 and an associated secondary mixing unit 5b, which is explained, as well as the recirculation nozzles 291 can be omitted.
  • only a primary recirculation can 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 variant is supplied to the recirculation nozzles 291 provided.
  • 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.
  • 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.
  • rotating grate elements 252, 253 and 254 instead of just three rotating grate elements 252, 253 and 254, two, four or more rotating grate elements can be provided.
  • five rotating grate elements could be arranged with the same symmetry and functionality as the three rotating grate elements presented.
  • the rotating grate elements can also be shaped or designed differently from one another. More rotating grate elements have the advantage that the crushing function is increased.
  • convex sides of the rotating grate elements 252 and 254 concave sides of these can also be provided, whereby the sides of the rotating grate element 253 can subsequently be shaped in a complementary convex manner. This is functionally almost equivalent.
  • the rotating grate can alternatively also be called a tilting grate.
  • the biomass heating system disclosed here can also be fired exclusively with one type of fuel, for example only with pellets.
  • the combustion chamber stones 29 can also be provided without the recirculation nozzles 291. This can apply in particular to the case in which no secondary recirculation is provided.
  • the geometries of the rotating grate elements 252, 253, 254 can differ from the geometry shown in the figures.
  • These rotating grate elements can be rectangular, square or round, for example.
  • the first and second anti-blockade procedures of the Figures 17b to 17d can also be executed independently of each other in response to a blockage detected elsewhere.
  • the procedures of the Figures 17a not necessarily together and are each disclosed as an independent procedure.
  • 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 in the Fig. 17b can be omitted.
  • the methods explained herein can be implemented as a computer program or part of a computer program.
  • the Fig. 12 ff. can represent parts of an overall system control program.
  • the methods described in the Fig. 12 The procedures described below can be carried out cyclically or repeatedly.
  • 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 implemented 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, for example, one or more scripts stored in a tracking language document, in a a single file dedicated to the program in question, or in multiple coordinated files, such as files that store one or more modules, subroutines, or sections of code.
  • a computer program may be designed to run on one computer or on multiple computers located at one location or distributed over multiple locations and linked by a data communications network.
  • the methods and logic flows described in this specification may be carried out 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 carried out by a special purpose logic circuit, e.g., FPGA or ASIC, or by a combination of special purpose logic circuit and one or more programmed computers.
  • 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.
  • 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.
  • a computer also includes, or is operatively connected to, one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks for receiving data therefrom or for transferring data thereto.
  • mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks for receiving data therefrom or for transferring data thereto.
  • a computer need not include such devices.
  • 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 portable memory card.
  • PDA personal digital assistant
  • GPS global positioning system
  • portable storage device such as a portable memory card.
  • USB universal serial bus
  • 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.
  • 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 e.g., CD-ROM and DVD-ROM disks.
  • 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.
  • a display device e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor
  • keyboard and pointing device e.g., a mouse or tactile ball
  • 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, voice, or tactile input.
  • a computer may interact with a user by sending documents and receiving documents from a device used by the user; e.g., by sending web pages to a web browser on a user's device in response to requests received from the web browser.
  • 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.
  • Data processing devices such as the control device 100, for implementing machine learning models may also include, for example, special hardware acceleration units to process common and computationally intensive components of machine learning training or production, i.e. interference, workloads.
  • the methods described herein may be implemented as a (computer) program, for example on the hardware described above, but are not limited thereto.
  • At least one of the present methods may be provided as a program on a computer-readable storage medium.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Solid-Fuel Combustion (AREA)
EP22209601.8A 2022-11-25 2022-11-25 Installation de chauffage de biomasse à nettoyage amélioré et détection de blocage de celle-ci Pending EP4375570A1 (fr)

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EP22209601.8A EP4375570A1 (fr) 2022-11-25 2022-11-25 Installation de chauffage de biomasse à nettoyage amélioré et détection de blocage de celle-ci

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EP22209601.8A EP4375570A1 (fr) 2022-11-25 2022-11-25 Installation de chauffage de biomasse à nettoyage amélioré et détection de blocage de celle-ci

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070125281A1 (en) * 2005-12-01 2007-06-07 Robert Ingvarsson Device and method for the combustion of granular, solid fuel
US20070215021A1 (en) * 2003-04-09 2007-09-20 Even Temp, Inc. Apparatus and method for combustion
EP3789670B1 (fr) 2019-09-03 2021-05-26 SL-Technik GmbH Installation de chauffage à la biomasse ainsi que ses parties intégrantes
EP3789676B1 (fr) 2019-09-03 2021-06-16 SL-Technik GmbH Grille rotative dotée d'un dispositif de nettoyage pour une installation de chauffage à biomasse
EP4056900A1 (fr) * 2021-03-09 2022-09-14 SL-Technik GmbH Installation de chauffage à biomasse dotée d'un dispositif amélioré de nettoyage

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070215021A1 (en) * 2003-04-09 2007-09-20 Even Temp, Inc. Apparatus and method for combustion
US20070125281A1 (en) * 2005-12-01 2007-06-07 Robert Ingvarsson Device and method for the combustion of granular, solid fuel
EP3789670B1 (fr) 2019-09-03 2021-05-26 SL-Technik GmbH Installation de chauffage à la biomasse ainsi que ses parties intégrantes
EP3789676B1 (fr) 2019-09-03 2021-06-16 SL-Technik GmbH Grille rotative dotée d'un dispositif de nettoyage pour une installation de chauffage à biomasse
EP4056900A1 (fr) * 2021-03-09 2022-09-14 SL-Technik GmbH Installation de chauffage à biomasse dotée d'un dispositif amélioré de nettoyage

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