EP3789672B1 - Biomass heating system with secondary air conduit, and components of same - Google Patents

Description

TECHNICAL AREA

The invention relates to a biomass heating system and its components. In particular, the invention relates to a flow-optimized biomass heating system.

STATE OF THE ART

Biomass heating systems, in particular biomass boilers, in a power range from 20 to 500 kW are known. Biomass can be considered a cheap, domestic, crisis-proof and environmentally friendly fuel. There are, for example, wood chips or pellets as combustible biomass or biogenic solid fuels.

The pellets usually consist of wood shavings, sawdust, biomass or other material that has been compacted into small discs or cylinders approximately 3 to 15 mm in diameter and 5 to 30 mm long. Wood chips (also known as wood chips, woodchips or woodchips) are wood that has been crushed with cutting tools.

Biomass heating systems for fuels in the form of pellets and wood chips essentially have a boiler with a combustion chamber (the combustion chamber) and a heat exchange device connected to it. Due to the stricter legal regulations in many countries, some biomass heating systems also have a fine dust filter. Other various accessories are regularly available, such as fuel delivery devices, Control devices, probes, safety thermostats, pressure switches, flue gas recirculation, boiler cleaning and a separate fuel tank.

A device for supplying fuel, a device for supplying air and an ignition device for the fuel are regularly provided in the combustion chamber. In turn, the means for supplying the air normally comprises a low-pressure fan in order to favorably influence the thermodynamic factors of combustion in the combustion chamber. A device for supplying fuel can be provided, for example, with a lateral insert (so-called transverse insert firing). The fuel is pushed into the combustion chamber from the side via a screw or a piston.

In the combustion chamber of a fixed-bed furnace, a furnace grate is also usually provided, on which the fuel is essentially supplied and burned continuously. This grate stores the fuel for combustion and has openings, for example slots, which allow the passage of part of the combustion air as primary air to the fuel. Next, the grate can be rigid or movable. There are also grate furnaces in which the combustion air is not fed through the grate but only from the side.

When the primary air flows through the grate, the grate is also cooled, which protects the material. In addition, insufficient air supply can lead to slag formation on the grate. In particular furnaces that are to be charged with different fuels, with which the present disclosure is particularly concerned, have the inherent problem that the different fuels have different ash melting points, water contents and different combustion behavior. It is therefore problematic to provide a heating system that is equally well suited for different fuels. The combustion chamber can also be regularly divided into a primary combustion zone (immediate combustion of the fuel on the grate and in the gas space above it before additional combustion air is supplied) and a secondary combustion zone (post-combustion zone of the flue gas after another air supply) are divided. Drying, pyrolytic decomposition, gasification of the fuel and charcoal combustion take place in the combustion chamber. In order to completely burn the resulting combustible gases, additional combustion air is introduced in one or more stages (secondary air or tertiary air) at the beginning of the secondary combustion zone.

After drying, the combustion of the pellets or wood chips essentially has two phases. In the first phase, the fuel is at least partially pyrolytically decomposed and converted into gas by high temperatures and air that can be blown into the combustion chamber. In the second phase, the (partial) part that has been converted into gas is burned, as well as the burning of any remaining solids (e.g. charcoal). In this respect, the fuel outgasses, and the resulting gas and the charcoal contained therein are 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, the pyrolysis gases being divided into room temperature condensable and non-condensable gases. The primary pyrolysis takes place at roughly 250-450°C and the secondary pyrolysis at around 450-600°C. The secondary pyrolysis that subsequently occurs is based on the further reaction of the pyrolysis products that were primarily formed. The 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 can reach the particle surface. Gasification can be seen as part of oxidation; the solid, liquid and gaseous products formed during the pyrolytic decomposition are reacted by further exposure to heat. This is done by adding a gasification agent such as air, oxygen, water vapor or carbon dioxide. The lambda value during gasification is greater than zero and less than one. Gasification takes place at around 300 to 850°C or even up to 1,200°C. The complete oxidation with excess air (lambda greater than 1) takes place by adding more air to these processes. the Reaction end products are essentially carbon dioxide, water vapor and ash. In all phases, the boundaries are not rigid, but fluid. The combustion process can be advantageously regulated by means of a lambda probe provided at the exhaust gas outlet of the boiler.

Generally speaking, converting the pellets to gas increases combustion efficiency because gaseous fuel is better mixed with the combustion air and thus more completely converted, and lower emissions of pollutants, unburned particles and ash (fly ash or dust particles) are produced .

The combustion of biomass produces gaseous or airborne combustion products, the main components of which are carbon, hydrogen and oxygen. These can be divided into emissions from complete oxidation, from incomplete oxidation and substances from trace elements or impurities. The emissions from complete oxidation are essentially carbon dioxide (CO ₂ ) and water vapor (H ₂ O). The formation of carbon dioxide from the carbon in the biomass is the goal of combustion, as the released energy can be used more fully. The release of carbon dioxide (CO ₂ ) is largely proportional to the carbon content of the fuel burned; thus the carbon dioxide is also dependent on the useful energy to be provided. A reduction can essentially only be achieved by improving the efficiency.

However, the complex combustion processes described above are not easy to control. Generally speaking, there is a need for improvement with regard to the combustion processes in biomass heating systems.

In addition to the air supply to the combustion chamber, exhaust gas recirculation devices are also known, which return exhaust gas from the boiler to the combustion chamber for cooling and renewed combustion. In the prior art, there are usually openings in the combustion chamber for the supply of primary air through a primary air duct feeding the combustion chamber, and there are also peripheral openings in the combustion chamber for the supply of secondary air from a secondary air duct. Flue gas recirculation can take place below or above the grate. In addition, the flue gas can be recirculated mixed with the combustion air or separately.

The exhaust gas from combustion in the combustion chamber is fed to the heat exchanger so that the hot combustion gases flow through the heat exchanger to transfer heat to a heat exchange medium, which is normally water at around 80°C (usually between 70°C and 110°C). °C). The boiler further usually has a radiant part, which is integrated into the combustion chamber, and a convection part (the heat exchanger connected thereto).

The ignition device is mostly a hot air device or a glow device. In the first case, combustion is started by supplying hot air to the combustion chamber, the hot air being heated by an electrical resistance. In the second case, the ignition device comprises a glow plug/rod or several glow plugs to heat the pellets or wood chips by direct contact until combustion begins. The glow plugs can also be equipped with a motor to remain in contact with the pellets or wood chips during the ignition phase and then move back to avoid being exposed to the flames. This solution is subject to wear and tear and expensive.

The basic problems with conventional biomass heating systems are that the gaseous or solid emissions are too high, that the efficiency is too low and that the dust emissions are too high. Another problem is the varying quality of the fuel, due to the varying water content and the lumpiness of the fuel, which makes it difficult to burn the fuel evenly with low emissions. In particular in the case of biomass heating systems, which should be suitable for different types of biological or biogenic fuel, the varying quality and consistency of the fuel makes it difficult to achieve consistent heating maintain high efficiency of the biomass heating system. There is a considerable need for optimization in this regard.

A disadvantage of traditional pellet biomass heating systems can be that pellets falling into the combustion chamber can roll off the grid or grate, slide off, or land next to 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 bottom chamber of the boiler or the ash chute. Pellets that do not remain on the grid or grate burn incompletely, causing poor efficiency, excessive ash and a certain amount of unburned pollutant particles. This applies to pellets as well as wood chips.

For this reason, the known biomass heating systems for pellets have, for example, baffles in the vicinity of the grate and/or the outlet of the combustion gas in order to retain fuel elements in certain places. Some boilers have shoulders on the inside of the combustion chamber to prevent pellets from falling into the ash removal and/or the bottom chamber of the boiler. In turn, these baffles and ledges can trap combustion residues, making cleaning difficult and can restrict airflow in the combustion chamber, which in turn reduces efficiency. In addition, these baffles require their own production and assembly costs. This applies to pellets as well as wood chips.

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

Another problem is the non-uniform distribution of pellets in the combustion chamber and especially on the grate, which reduces combustion efficiency and increases the emission of harmful substances. This disadvantage can also impede the ignition if there is an area without fuel is near the ignition device. This applies to pellets as well as wood chips.

Baffles or ledges in the combustion chamber can limit this inconvenience and prevent the fuel from rolling or sliding off the grate or even falling into the bottom chamber of the boiler, but they impede airflow and prevent optimal mixing of air and fuel.

Another problem is that incomplete combustion as a result of non-uniform distribution of fuel from the grate and as a result of non-optimal mixing of air and fuel can lead to the accumulation and fall of unburned ash through the air intake openings leading directly to the combustion grate, or from the grate end into the air ducts or air supply area.

This is particularly annoying and causes frequent interruptions to perform maintenance such as cleaning. For all these reasons, a large excess of air is normally maintained in the combustion chamber, but this reduces flame temperature and combustion efficiency, and increases emissions of unburned gases (e.g. CO, CyHy), NOx and dust (e.g. from the increased turbulence).

The use of a low head fan does not provide a suitable swirling flow of air in the combustor and therefore does not allow for an optimal mixing of air and fuel. In general, it is difficult to form an optimal turbulent flow in conventional combustion chambers.

Another problem with the known burners without air staging is that the two phases, conversion of the pellets into gas and combustion, take place simultaneously in the entire combustion chamber by means of the same amount of air, which reduces efficiency.

Finally, there are some disadvantages related to the ignition devices. Hot air devices require high electrical power and incur high costs. Spark plugs require less power, but they require moving parts because the spark plugs must be motorized. They are expensive, complicated and can pose a problem in terms of reliability.

Furthermore, there is also a need for optimization, especially in the heat exchangers of biomass heating systems of the prior art, i.e. their efficiency could be increased. There is also a need for improvement with regard to the often cumbersome and inefficient cleaning of conventional heat exchangers.

The same applies to the usual electrostatic precipitators of biomass heating systems. Their spray and separating electrodes are regularly clogged with combustion residues, which impairs the formation of the electric field for filtering and reduces the efficiency of the filtering.

the U.S. 2,933,057 A discloses improvements in furnaces adapted for the combustion of such fuels as rubbish, refuse, refuse, rubbish and similar material having a high moisture content. One of the aims of this prior art is to provide a grate for the above type of firing, which will ensure a progressive feeding of the material from the inlet of the kiln to the back of the grate, at the same time ensuring a proper consumption of the fuel.

Another subject of U.S. 2,933,057 A is to provide means by which the grate bars are prevented from warping under the intense heat developed by the consumption of the fuel, and to provide means by which the means for preventing warping of the grate bars for heating water used for can be used for various purposes.

Another subject of U.S. 2,933,057 A is to provide means to prevent the grates of furnaces of the above type from being overheated when using high temperature preheated air and to prevent the Ash and sand that might enter the furnace with the waste to be burned would melt and form a slag that would stick to the grate.

In the embodiment of U.S. 2,933,057 A a plurality of water-cooled tubes I are provided, arranged side by side and extending from the front to the rear of the furnace. The tubes are connected at the rear of the furnace to a header 2 which extends transversely to the rear of the furnace in front of the bridge wall 3 and rests on suitable support brackets 4 fixed in any manner in the front of the bridge wall or to the side walls.

It is an object of the invention to provide a biomass heating system in hybrid technology, which is low in emissions (especially with regard to fine dust, CO, hydrocarbons, NOx), which can be operated flexibly with wood chips and pellets, and which has a high degree of efficiency.

• Die Hybridtechnologie soll sowohl den Einsatz von Pellets als auch von Hackgut mit Wassergehalten zwischen 8 und 35 Gewichtsprozent ermöglichen.
• Möglichst niedrige gasförmige Emissionen (kleiner als 50 oder 100 mg/Nm³ bezogen auf trockenes Rauchgas und 13 Volumenprozent O₂) sollen erzielt werden.
• Sehr niedrige Staubemissionen kleiner 15 mg/Nm³ ohne und kleiner 5 mg/Nm³ mit Elektrofilterbetrieb werden angestrebt.
• Ein hoher Wirkungsgrad von bis zu 98% (bezogen auf die zugeführte Brennstoffenergie (Heizwert) soll erreicht werden.

According to the invention and in addition, the following considerations can play a role:

• The hybrid technology should enable the use of both pellets and wood chips with a water content of between 8 and 35 percent by weight.
• Gaseous emissions that are as low as possible (less than 50 or 100 mg/Nm ³ based on dry flue gas and 13 percent by volume O ₂ ) should be achieved.
• Very low dust emissions of less than 15 mg/Nm ³ without and less than 5 mg/Nm ³ with electrostatic precipitator operation are aimed for.
• A high degree of efficiency of up to 98% (based on the fuel energy supplied (calorific value) should be achieved.

Furthermore, one can take into account that the operation of the system should be optimized. For example, simple ash removal, simple cleaning or simple maintenance should be made possible.

In addition, there should be high system availability.

The task mentioned above or the potential individual problems can also relate to individual partial aspects of the overall system, for example to the combustion chamber, the heat exchanger or the electrical filter device (not the subject matter of the claims).

This object(s) is/are solved by the subject matter of the independent claim. Further aspects and advantageous developments are the subject matter of the dependent claims.

According to the present disclosure of the invention, there is disclosed a biomass heating system for firing fuel in the form of pellets and/or wood chips, the system comprising: a boiler having a burner, a heat exchanger having a plurality of boiler tubes, the burner having the following comprising: a combustor having a rotary grate, having a primary combustion zone and having a secondary combustion zone; the primary combustion zone being encompassed by a plurality of combustion chamber bricks laterally and by the rotary grate from below; a plurality of secondary air nozzles being provided in the combustor bricks; the primary combustion zone and the secondary combustion zone being separated at the level of the secondary air nozzles; wherein the secondary combustion zone of the combustor is fluidly connected to an inlet of the heat exchanger.

According to the invention it is provided that the secondary air nozzles are arranged in such a way that in the secondary combustion zone of the combustion chamber eddy currents of a flue gas-air mixture of secondary air and combustion air (flue gas) arise around a vertical central axis, the Eddy currents improve the mixing of the flue gas-air mixture.

According to a development of the invention, a biomass heating system is provided, with the secondary air nozzles in the combustion chamber bricks each being designed as a cylindrical or truncated cone-shaped opening in the combustion chamber bricks with a circular or elliptical cross section, the smallest diameter of the respective opening being smaller than its maximum length.

According to one development, a biomass heating system is provided, the combustion device with the combustion chamber being set up in such a way that the turbulent flows form spiral-shaped rotational flows after exiting the combustion chamber nozzle, which reach up to a combustion chamber ceiling of the combustion chamber.

According to a development of the invention, a biomass heating system is provided, with the secondary air nozzles being arranged at least approximately at the same height in the combustion chamber; and the secondary air nozzles are arranged with their central axis and/or (depending on the type of nozzle) aligned in such a way that the secondary air is introduced acentrically to a center of symmetry of the combustion chamber.

According to a development of the invention, a biomass heating system is provided, the number of secondary air nozzles being between 8 and 14; and/or the secondary air nozzles have a minimum length of at least 50 mm with an inner diameter of 20 to 35 mm.

According to a development of the invention, a biomass heating system is provided, with the combustion chamber in the secondary combustion zone having a combustion chamber slope which reduces the cross section of the secondary combustion zone in the direction of the inlet of the heat exchanger.

According to a further development of the invention, a biomass heating system is provided, the combustion chamber in the secondary combustion zone having a combustion chamber cover which is provided inclined upwards in the direction of the inlet of the heat exchanger and which reduces the cross section of the combustion chamber in the direction of the inlet.

According to a development of the invention, a biomass heating system is provided, with the combustion chamber slope and the inclined combustion chamber ceiling forming a funnel, the smaller end of which opens into the inlet of the heat exchanger.

According to a development of the invention, a biomass heating system is provided, the primary combustion zone and at least part of the secondary combustion zone having an oval horizontal cross-section; and/or the secondary air nozzles are arranged in such a way that they introduce the secondary air tangentially into the combustion chamber.

According to a development, a biomass heating system is provided, with the average flow speed of the secondary air in the secondary air nozzles being at least 8 m/s, preferably at least 10 m/s.

According to a development of the invention, a biomass heating system is provided, with the combustion chamber bricks having a modular structure; and any two semi-circular combustor bricks form a closed ring to form the primary combustion zone and/or part of the secondary combustion zone; and at least two rings of bricks are stacked one on top of the other.

According to a development of the invention, a biomass heating system is provided, the heat exchanger having spiral turbulators arranged in the boiler tubes, which extend over the entire length of the boiler tubes; and the heat exchanger includes strip turbulators located in the boiler tubes and extending at least half the length of the boiler tubes.

According to a further aspect of the present disclosure, a biomass heating system for firing fuel in the form of pellets and/or wood chips is provided, which has the following: a boiler with a combustion device, a heat exchanger with a plurality of boiler tubes, preferably arranged in a bundle-like manner, the combustor comprising: a combustor having a rotary grate and having a primary combustion zone and a secondary combustion zone, preferably provided above the primary combustion zone; the primary combustion zone being encompassed by a plurality of combustion chamber bricks laterally and by the rotary grate from below; wherein secondary combustion zone includes a combustor nozzle or burn-through hole; wherein the secondary combustion zone of the combustor is fluidly connected to an inlet of the heat exchanger; wherein the primary combustion zone has an oval horizontal cross-section.

In the case of boiler tubes arranged in a bundle-like manner, there can be a plurality of boiler tubes which are arranged parallel to one another and have at least largely the same length. Preferably, the inlet openings and the outlet openings of all boiler tubes can each be arranged in a common plane; i.e. i.e. the inlet openings and the outlet openings of all boiler tubes are at the same level.

In the present case, "horizontal" can denote a level orientation of an axis or a cross section, assuming that the boiler is also set up horizontally, with which, for example, the ground level can be the reference. Alternatively, "horizontal" as used herein means "parallel" to the base plane of vessel 11 as commonly defined. Further alternatively, in particular if there is no reference plane, "horizontal" can be understood merely as "parallel" to the combustion plane of the grate.

Furthermore, the primary combustion zone can have an oval cross-section.

The oval horizontal cross-section has no dead corners, and thus has improved air flow and the possibility of largely unhindered vortex flow up. Consequently, the biomass heating system has improved efficiency and lower emissions. In addition, the oval cross-section is well adapted to the type of fuel distribution when it is fed in from the side and the resulting geometry of the fuel bed on the grate. An ideally "round" cross section is also possible, but not so well adapted to the geometry of the fuel distribution and also to the flow technology of the turbulent flow, with the asymmetry of the oval compared to the "ideally" circular cross-sectional shape of the combustion chamber improving the formation of a turbulent flow in the combustion chamber allows.

According to a development, a biomass heating system is provided, with the horizontal cross-section of the primary combustion zone being provided at least approximately the same over a height of at least 100 mm. This also serves to ensure the unhindered development of the flow profiles in the combustion chamber.

According to a development, a biomass heating system is provided, with the combustion chamber in the secondary combustion zone having a combustion chamber slope which narrows the cross section of the secondary combustion zone in the direction of the inlet or inlet of the heat exchanger.

According to one development, a biomass heating system is provided, with the rotary grate having a first rotary grate element, a second rotary grate element and a third rotary grate element, each of which rotates about a horizontally arranged bearing axis by at least 90 degrees, preferably at least 160 degrees, even more preferably by at least 170 degrees , are rotatably arranged; wherein the rotary grate elements form a combustion surface for the fuel; wherein the rotary grate elements have openings for the air for combustion, wherein the first rotary grate element and the third rotary grate element are identical in their combustion surface.

The openings in the rotary grate elements are preferably designed in the form of slots and in a regular pattern in order to ensure a uniform flow of air through the fuel bed.

According to a further development, a biomass heating system is provided, with the second rotary grate element being arranged in a form-fitting manner between the first rotary grate element and the third rotary grate element and having grate lips which are arranged in such a way that, when all three rotary grate elements are in the horizontal position, they at least largely form a seal on the first rotary grate element and the third rotary grate element.

According to one development, a biomass heating system is provided, with the rotary grate also having a rotary grate mechanism that is configured in such a way that it can rotate the third rotary grate element independently of the first rotary grate element and the second rotary grate element, and that this rotates the first rotary grate element and the second rotary grate element together but can rotate independently of the third rotary grate element.

According to a development, a biomass heating system is provided, with the combustion surface of the rotary grate elements being configured as an essentially oval or elliptical combustion surface.

According to a development, a biomass heating system is provided, the rotary grate elements having mutually complementary and curved sides, the second rotary grate element preferably having concave sides toward the adjacent first and third rotary grate element, and preferably the first and third rotary grate element each toward the second rotary grate element have a convex side.

According to a development, a biomass heating system is provided, with the combustion chamber bricks having a modular structure; and every two semi-circular combustor bricks form a closed ring to form the primary combustion zone; and at least two rings of bricks are stacked one on top of the other.

According to a further development, a biomass heating system is provided, the heat exchanger having spiral turbulators arranged in the boiler tubes extend along the entire length of the boiler tubes; and the heat exchanger includes strip turbulators located in the boiler tubes and extending at least half the length of the boiler tubes. The band turbulators can preferably be arranged in or inside the spiral turbulators. In particular, the band turbulators can be integrated into the spiral turbulators. The band turbulators can preferably extend over a length of 30 to 70% of the length of the spiral turbulators.

According to a development, a biomass heating system is provided, with the heat exchanger having between 18 and 24 boiler tubes, each with a diameter of 70 to 85 mm and a wall thickness of 3 to 4 mm.

According to a development, a biomass heating system is provided, the boiler having an integrated electrostatic filter device, which has a spray electrode and a precipitation electrode surrounding the spray electrode and a cage or a cage-like cleaning device; wherein the boiler further comprises a mechanically operable cleaning device with a hammer lever with a stop head; wherein the cleaning device is set up in such a way that it can hit the end of the (spray) electrode with the stop head, so that a shock wave is generated by the electrode and/or a transverse vibration of the (spray) electrode in order to remove impurities from the electrode to clean up. A steel is provided as the material for the electrode, which can be caused to oscillate (longitudinally and/or transversely and/or shock wave) by the stop head. Spring steel and/or chromium steel, for example, can be used for this purpose. The material of the spring steel can preferably be an austenitic chromium-nickel steel, for example 1.4310. Next, the spring steel can be cambered. The cage-shaped cleaning device can be further moved back and forth along the wall of the electrostatic filter device for cleaning the collecting electrode.

According to a further development, a biomass heating system is provided, with a cleaning device integrated into the boiler in the cold area being provided configured to clean the boiler tubes of the heat exchanger by moving up and down turbulators provided in the boiler tubes. The up and down movement can also be understood as the reciprocating movement of the turbulators in the boiler tubes in the longitudinal direction of the boiler tubes.

According to a development, a biomass heating system is provided, with a fire bed height measuring mechanism being arranged in the combustion chamber above the rotary grate; wherein the firebed height measurement mechanism comprises a fuel level flap mounted on a pivot and having a major surface; wherein a surface parallel of the main surface of the fuel level flap is provided at an angle to a central axis of the axis of rotation, the angle preferably being greater than 20 degrees.

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

For example, a combustion chamber slope of a secondary combustion zone of a combustion chamber with the features and properties mentioned herein is disclosed, which is (only) suitable for a biomass heating system. In this respect, a combustion chamber incline for a secondary combustion zone of a combustion chamber of a biomass heating system with the features and properties mentioned herein is disclosed.

Furthermore, for example, a rotary grate for a combustion chamber of a biomass heating system with its features and properties mentioned herein is disclosed.

Furthermore, for example, a plurality of combustion chamber bricks for a combustion chamber of a biomass heating system with the features and properties mentioned herein is disclosed.

Furthermore, for example, an integrated electrostatic filter device for a biomass heating system with the features and properties mentioned herein is disclosed.

Furthermore, for example, a plurality of boiler tubes for a biomass heating system with the features and properties mentioned herein are disclosed.

Furthermore, for example, a ember bed height measuring mechanism for a biomass heating system with the features and properties mentioned herein is disclosed.

Furthermore, for example, as such, a fuel level flap for a biomass heating system with the features and properties mentioned herein is also disclosed.

Fig. 1

zeigt eine dreidimensionale Überblicksansicht einer Biomasse-Heizanlage gemäß einer Ausführungsform der Erfindung;

Fig. 2

zeigt eine Querschnittsansicht durch die Biomasse-Heizanlage der Fig. 1, welche entlang einer Schnittlinie SL1 vorgenommen wurde und welche aus der Seitenansicht S betrachtet dargestellt ist;

Fig. 3

zeigt ebenso eine Querschnittsansicht durch die Biomasse-Heizanlage der Fig. 1 mit einer Darstellung des Strömungsverlaufs, wobei die Querschnittsansicht entlang einer Schnittlinie SL1 vorgenommen wurde und aus der Seitenansicht S betrachtet dargestellt ist;

Fig. 4

zeigt eine Teilansicht der Fig. 2, die eine Brennkammergeometrie des Kessels der Fig. 2 und Fig. 3 darstellt;

Fig. 5

zeigt eine Schnittansicht durch den Kessel bzw. die Brennkammer des Kessels entlang der Vertikalschnittlinie A2 der Fig. 4;

Fig. 6

zeigt eine dreidimensionale Schnittansicht auf die Primärverbrennungszone der Brennkammer mit dem Drehrost der Fig. 4;

Fig. 7

zeigt entsprechend zur Fig. 6 eine Explosionsdarstellung der Brennkammersteine;

Fig. 8

zeigt eine Aufsicht auf den Drehrost mit Drehrostelementen von oben aus Sicht der Schnittlinie A1 der Fig. 2;

Fig. 9

zeigt den Drehrost der Fig. 2 in geschlossener Position, wobei alle Drehrostelemente horizontal ausgerichtet bzw. geschlossen sind;

Fig. 10

zeigt den Drehrost der Fig. 9 in dem Zustand einer Teilabreinigung des Drehrosts im Gluterhaltungsbetrieb;

Fig. 11

zeigt den Drehrost der Fig. 9 im Zustand der Universalabreinigung, welche bevorzugt während eines Anlagenstillstands durchgeführt wird;

Fig. 12

zeigt eine Ausschnitt-Detailansicht der Fig. 2;

Fig. 13

zeigt eine Reinigungseinrichtung, mit der sowohl der Wärmetauscher als auch die Filtereinrichtung der Fig. 2 automatisch gereinigt werden können;

Fig. 14

zeigt eine Turbulatorhalterung in herausgestellter und vergrößerter Form;

Fig. 15

zeigt eine Abreinigungsmechanik in einem ersten Zustand, wobei sich sowohl die Turbulatorhalterungen der Fig. 14 als auch eine Käfighalterung in einer unteren Position befinden;

Fig. 16

zeigt die Abreinigungsmechanik in einem zweiten Zustand, wobei sich sowohl die Turbulatorhalterungen der Fig. 14 als auch die Käfighalterung in einer oberen Position befinden;

Fig. 17

zeigt eine freigestellte Glutbetthöhenmessmechanik mit einer Brennstoff-Niveauklappe;

Fig. 18

zeigt eine Detailansicht der Brennstoff-Niveauklappe;

Fig. 19

zeigt eine horizontale Querschnittsansicht durch die Brennkammer auf der Höhe der Sekundärluftdüsen;

Fig. 20

zeigt drei horizontale Querschnittsansichten für unterschiedliche Kesseldimensionierungen durch die Brennkammer auf der Höhe der Sekundärluftdüsen mit Angaben zu den Strömungsverteilungen in diesem Querschnitt;

Fig. 21

zeigt drei vertikale Querschnittsansichten für unterschiedliche Kesseldimensionierungen durch die Biomasse-Heizanlage entlang der Schnittlinie SL1 der Fig. 1 mit Angaben zu den Strömungsverteilungen in diesem Querschnitt.

The biomass heating system according to the invention is explained in more detail below in exemplary embodiments and individual aspects with reference to the figures of the drawing:

1

shows a three-dimensional overview of a biomass heating system according to an embodiment of the invention;

2

shows a cross-sectional view through the biomass heating system 1 , which was taken along a section line SL1 and which is shown viewed from the side view S;

3

also shows a cross-sectional view through the biomass heating system of FIG 1 with an illustration of the course of the flow, the cross-sectional view being taken along a cutting line SL1 and being viewed from the side view S;

4

shows a partial view of the 2 , which has a combustion chamber geometry of the boiler 2 and 3 represents;

figure 5

shows a sectional view through the boiler or the combustion chamber of the boiler along the vertical section line A2 of FIG 4 ;

6

shows a three-dimensional sectional view of the primary combustion zone of the combustion chamber with the rotary grate 4 ;

7

shows according to 6 an exploded view of the combustion chamber bricks;

8

shows a top view of the rotary grate with rotary grate elements seen from the section line A1 of FIG 2 ;

9

shows the rotary grate of 2 in the closed position, with all rotary grate elements aligned horizontally or closed;

10

shows the rotary grate of 9 in the state of a partial cleaning of the rotary grate in ember maintenance mode;

11

shows the rotary grate of 9 in the state of universal cleaning, which is preferably carried out during a plant standstill;

12

shows a detail view of the 2 ;

13

shows a cleaning device with which both the heat exchanger and the filter device of the 2 can be cleaned automatically;

14

shows a turbulator mount in exposed and enlarged form;

15

shows a cleaning mechanism in a first state, with both the turbulator mounts of 14 and a cage mount are in a down position;

16

shows the cleaning mechanism in a second state, with both the turbulator mounts of 14 and the cage mount are in an up position;

17

shows an isolated ember bed height measuring mechanism with a fuel level flap;

18

shows a detailed view of the fuel level flap;

19

shows a horizontal cross-sectional view through the combustion chamber at the level of the secondary air nozzles;

20

shows three horizontal cross-sectional views for different boiler dimensions through the combustion chamber at the level of the secondary air nozzles with information on the flow distributions in this cross-section;

21

shows three vertical cross-sectional views for different boiler dimensions through the biomass heating system along the section line SL1 1 with information on the flow distributions in this cross-section.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Various embodiments of the present disclosure are disclosed below with reference to the accompanying drawings, by way of example only. However, embodiments and terms used therein are not intended to limit the present disclosure to particular embodiments, and it should be construed to include various modifications, equivalents, and/or alternatives according to the embodiments of the present disclosure.

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

With respect to the description of the figures, the same reference numbers can be used in the individual figures to refer to similar or technically corresponding elements. Furthermore, for the sake of clarity, more elements or features can be shown with reference symbols in individual detailed or sectional views than in the overview views. It can be assumed that these elements or features are also disclosed accordingly in the overview presentations, even if they are not explicitly listed there.

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

In the present disclosure, an expression such as "A or B", "at least one of "A or/and B" or "one or more of A or/and B" can include any possible combination of features listed together. Expressions such as "first ", "secondary", "primary" or "secondary" used herein represent and do not limit various elements regardless of their order and/or importance. When an element (e.g., a first element) is described as being "operably" or "communicatively" coupled or connected to another element (e.g., a second element), the element may be directly connected to the other element become or are connected to the other element via another element (e.g. a third element).

For example, a phrase "configured for" (or "configured for") as used in the present disclosure may be replaced with "suitable for," "suitable for," "adapted for," "made for," "capable of," or "designed for." depending on what is technically possible. Alternatively, in a particular situation, a phrase "device configured to" or "set up to" may mean that the device can operate in conjunction with another device or component, or perform a corresponding function.

All sizes specified in "mm" are to be understood as a size range of +- 1 mm around the specified value, unless another tolerance or other ranges are explicitly stated. All dimensions and sizes are only examples.

It should be noted that the present individual aspects, for example the rotary grate, the combustion chamber or the filter device, are disclosed here separately from or separately from the biomass heating system as individual parts or individual devices. It is therefore clear to the person skilled in the art that individual aspects or parts of the system are also disclosed here on their own. In the present case, the individual aspects or parts of the system are disclosed in particular in the sub-chapters marked by brackets. It is envisaged that these individual aspects can also be claimed separately.

Furthermore, for the sake of clarity, not all features and elements are individually identified in the figures, especially if they are repeated. There are Rather, the elements and features are each designated as an example. Analogous or identical elements are then to be understood as such.

(biomass heating system)

1 shows a three-dimensional overview of the biomass heating system 1 according to an exemplary embodiment of the invention.

The arrow V in the figures indicates the front view of the plant 1, and the arrow S in the figures indicates the side view of the plant 1.

The biomass heating system 1 has a boiler 11 which is mounted on a base 12 of the boiler. The boiler 11 has a boiler housing 13, for example made of sheet steel.

In the front part of the boiler 11 there is a combustion device 2 (not shown), which can be reached via a first maintenance opening with a closure 21 . A rotary mechanism mount 22 for a rotary grate 25 (not shown) supports a rotary mechanism 23 with which drive forces can be transmitted to bearing axles 81 of the rotary grate 25 .

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

In the rear of the vessel 11 is an optional filter assembly 4 (not shown) having an electrode 44 (not shown) suspended by an insulating electrode support 43 and powered by an electrode supply line 42 . The exhaust gas from the biomass heating system 1 is discharged via an exhaust gas outlet 41 which is arranged downstream of the filter device 4 in terms of flow. A fan can be provided here.

A recirculation device 5 is provided downstream of the boiler 11, which recirculates part of the exhaust gas via recirculation channels 51, 53 and 54 and flaps 52 for cooling the combustion process and reuse in the combustion process.

Furthermore, the biomass heating system 1 has a fuel supply 6, with which the fuel is conveyed in a controlled manner to the combustion device 2 in the primary combustion zone 26 from the side onto the rotary grate 25. The fuel supply 6 has a cell wheel sluice 61 with a fuel supply opening 65, the cell wheel sluice 61 having 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 feed screw 67 (not shown) so that the fuel in a fuel feed channel 64 is fed to the combustion device 2 .

In the lower part of the biomass heating system 1 there is an ash removal device 7 which has an ash discharge screw 71 in an ash discharge channel which is operated by a motor 72 .

2 now shows a cross-sectional view through the biomass heating system 1 of FIG 1 , which was taken along a section line SL1 and which is shown viewed from the side S. In the corresponding 3 , which has the same cut as 2 represents, for the sake of clarity, the flows of the flue gas, and fluidic cross-sections are shown schematically. to 3 it should be noted that individual areas compared to the 2 are shown grayed out. This is only for clarity 3 and the visibility of the flow arrows S5, S6 and S7.

From left to right are in 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 can circulate. To the 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 takes place in the core. The combustion chamber 24 has a multi-part rotary grate 25, which will be explained in more detail later, on which the fuel bed 28 rests. The multi-part rotary grate 25 is rotatably mounted by means of a plurality of bearing axles 81 .

Further referring to 2 For example, the primary combustion zone 26 of the combustor 24 is encompassed by (a plurality of) combustor brick(s) 29 , whereby the combustor 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 substantially oval (for example 380mm +/- 60mm x 320mm +/- 60mm; it should be noted that some of the above size combinations may also result in a circular cross-section). The arrow S1 shows the flow from the secondary air nozzle 291 schematically, this flow (this is shown purely schematically) having a twist 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 (cf. 19 ). This creates a flow S1 with vortices or twists, which runs roughly spirally or helically upwards. In other words, a spiral flow running upwards and rotating about a vertical axis is formed.

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 stones 29 thus also protect the other material of the combustion chamber 24 , for example cast iron, from the direct effect of the flames in the combustion chamber 24 . The combustion chamber stones 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 acentrically in order to cause a swirl of the flow in the primary combustion zone 26 (ie a swirling and turbulent flow, which will be explained in more detail later). The combustion chamber bricks 29 will be explained in more detail later. Insulation 311 is provided at the boiler tube entrance. The oval cross-sectional shape of the primary combustion zone 26 (and the nozzle) and the length and position of the secondary air nozzles 291 favor the formation and maintenance of a turbulent 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 height of the combustion chamber nozzles 291 (from a functional or combustion technology point of view) or at the height of the combustion chamber nozzle 203 (from a purely structural or constructional point of view) and defines the radiant part of the combustion chamber 26. In the radiant part, the flue gas produced during combustion releases its thermal energy mainly through thermal radiation, in particular to the heat exchange medium, which is located in the two left-hand chambers for the heat exchange medium 38 . The corresponding flue gas flows are in 3 indicated purely by way of example by the arrows S2 and S3. These turbulent flows may also contain slight backflows or other turbulences, which are not represented by the purely schematic arrows S2 and S3. However, the basic principle of the development of the flow in the combustion chamber 24 is clear and can be calculated by a person skilled in the art based on the arrows S2 and S3.

Caused by the secondary air injection, pronounced swirling, rotating or turbulent flows are formed in the isolated or limited combustion chamber 24 (cf. 20 for the beginning of the eddy currents at the height of the secondary nozzles 291). The oval combustion chamber geometry 24 in particular contributes to the fact that the turbulent flow can develop undisturbed or optimally.

After exiting the nozzle 203, which bundles these turbulent flows again, candle-flame-shaped rotary flows S2 appear (cf. also 21 ), which can advantageously reach up to the combustion chamber ceiling 204, whereby the available space in the combustion chamber 24 is better utilized. The turbulent flows are concentrated in the center of the combustion chamber A2 and make ideal use of the volume of the secondary combustion zone 27 . Furthermore, the constriction, which represents the combustion chamber nozzle 203 for the turbulent flows, reduces the rotational flows, with which turbulences are generated to improve the mixing of the air/flue gas mixture. Cross-mixing therefore takes place through the constriction or constriction through the combustion chamber nozzle 203 . However, the rotational momentum of the flows is at least partially maintained above the combustion chamber nozzle 203, which maintains the propagation of these flows up to the combustion chamber ceiling 204.

The secondary air nozzles 291 are 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 eddy currents which cause the flue gas/secondary air mixture to rotate and thereby (again in combination with the combustion chamber nozzle 203 positioned above improved) enable complete combustion with minimal excess air and thus maximum efficiency. This is also in the Figures 19 to 21 illustrated.

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 combustion rate of the flue gases is accelerated and the complete combustion even at extreme partial load (e.g. 30% the nominal load) is ensured.

The first maintenance opening 21 is insulated with an insulating material such as Vermiculite ^™ . The present secondary combustion zone 27 is set up in such a way that burnout of the flue gas is ensured. The special geometric design of the secondary combustion zone 27 will be explained in more detail later.

After the secondary combustion zone 27, the flue gas flows into the heat exchange device 3, which has a bundle of boiler tubes 32 provided parallel to one another. The flue gas now flows downwards in the boiler tubes 32, as in 3 indicated by the arrows S4. This part of the flow can also be referred to as the convection part, since the heat dissipation of the flue gas takes place essentially on the boiler tube walls via forced convection. Due to the temperature gradients in the heat exchanger medium, for example in the water, caused in the boiler 11, natural convection of the water occurs, which promotes thorough mixing of the boiler water.

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 . This will be explained in more detail later.

The outlet of the boiler tubes 32 opens into the turning chamber 35 via the turning chamber entry 34 or inlet. If the filter device 4 is not provided, the flue gas is discharged upwards again in the boiler 11 . The other case of the optional filter device 4 is in the 2 and 3 shown. In the process, the flue gas is fed back up into the filter device 4 after the turning chamber 35 (cf. arrows S5), which in the present example is an electrostatic filter device 4. Flow screens can be provided at the inlet 44 of the filter device 4, which even out the inflow of the flue gas into the filter.

Electrostatic dust filters, also known as electrostatic precipitators, 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. With electrostatic precipitators, dust particles are electrically charged by a corona discharge of a spray electrode and drawn to the oppositely charged electrode (collecting electrode). The corona discharge takes place on a suitable, charged high-voltage electrode (also known as a discharge electrode) inside the electrostatic precipitator. The electrode is preferred with protruding tips and possibly sharp edges, because the density of the field lines and thus also the electric field strength is greatest there and the corona discharge is thus favored. The opposite electrode (precipitation electrode) usually consists of a grounded section of exhaust pipe that is mounted around the electrode. The degree of separation of an electrostatic precipitator depends in particular on the dwell 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 a high-voltage generating device (not shown). The high-voltage generation system and the holder for the electrode must be protected from dust and dirt in order to avoid unwanted leakage currents and to extend the service life of system 1.

As in 2 shown is a rod-shaped electrode 45 (which is preferably designed like an elongated, plate-shaped steel spring, cf. 15 ) held approximately centrally in an approximately chimney-shaped interior of the filter device 4. The electrode 45 consists at least largely of high-quality spring steel or chromium steel and is held by an electrode holder 43 via a high-voltage insulator, ie an electrode insulation 46 .

The (spray) electrode 45 hangs downwards into the interior of the filter device 4 so that it can vibrate. The electrode 45 can, for example, vibrate back and forth transversely to the longitudinal axis of the electrode 45 .

A cage 48 simultaneously serves as a counter-electrode and as a cleaning mechanism for the filter device 4. The cage 48 is connected to ground or earth potential. Due to the prevailing potential difference, the exhaust gas flowing in the filter device 4 is filtered, cf. the arrows S6, as explained above. In the case of cleaning of the filter device 4, the electrode 45 is switched off. The cage 48 preferably has an octagonal regular cross-sectional profile, as can be seen, for example, in FIG 13 can be taken. The cage 48 can preferably be laser cut during manufacture.

After leaving the heat exchanger 3, the flue gas flows through the turning chamber 34 into the inlet 44 of the filter device 4.

The (optional) filter device 4 is optionally provided fully integrated in the boiler 11, so that the wall surface facing the heat exchanger 3 and flushed through by the heat exchange medium is also used for heat exchange from the direction of the filter device 4, with which the efficiency of the system 1 is further improved. In this way, at least part of the wall of the filter device 4 can be flushed with the heat exchange medium, with the result that at least part of this wall is cooled with boiler water.

The cleaned exhaust gas flows out of the filter device 4 at the filter outlet 47, as indicated by the arrows S7. After leaving the filter, 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. The remaining part of the exhaust gas is conducted out of the boiler 11 via the exhaust gas outlet 41 .

An ash discharge 7 is arranged in the lower part of the boiler 11. The ash that has been separated and fallen out, for example from the combustion chamber 24, the boiler tubes 32 and the filter device 4, is discharged laterally out of the boiler 11 via an ash discharge screw 71.

The combustor 24 and boiler 11 of this embodiment were calculated using CFD simulations. Furthermore, practical experiments were carried out to confirm the CFD simulations. The starting point for the considerations were calculations for a 100 kW boiler, although a power range from 20 to 500 kW was taken into account.

A CFD simulation (CFD = Computational Fluid Dynamics = numerical fluid mechanics) is the spatially and temporally resolved simulation of flow and heat conduction processes. The flow processes can be laminar and/or turbulent, accompanied by chemical reactions, or it can be a act multi-phase system. CFD simulations are therefore well suited as a design and optimization tool. In the present invention, CFD simulations were used to optimize the fluidic parameters in such a way that the objects of the invention listed above are achieved. In particular, as a result, the mechanical design and dimensioning of the boiler 11, the combustion chamber 24, the secondary air nozzles 291 and the combustion chamber nozzle 203 were largely defined by the CFD simulation and also by associated practical experiments. The simulation results are based on a flow simulation taking heat transfer into account. Examples of results from such CFD simulations are given in 20 and 21 shown.

The components of the biomass heating system 1 and the boiler 11 listed above, which are results of the CFD simulations, are described in more detail below.

(combustion chamber)

The design of the combustor shape is important in order to be able to meet the task requirements. The shape and geometry of the combustion chamber should ensure the best possible turbulent mixing and homogenization of the flow over the cross-section of the flue gas duct, minimization of the combustion volume, as well as a reduction in the excess air and the recirculation ratio (efficiency, operating costs), a reduction in the CO and CxHx Emissions, NOx emissions, dust emissions, a reduction in local temperature peaks (fouling and slagging) and a reduction in local flue gas velocity peaks (material stress and erosion) can be achieved.

the 4 showing a partial view of the 2 is, and the figure 5 , which is a sectional view through the boiler 11 along the vertical section line A2, represent a combustion chamber geometry that meets the above-mentioned requirements for biomass heating systems over a wide power range of, for example, 20 to 500 kW will do justice. Incidentally, the vertical section line A2 can also be understood as the middle or central axis of the oval combustion chamber 24 .

$$\mathrm{BK2}=300\mathrm{mm}+-50\mathrm{mm},\mathrm{vorzugsweise}+-30\mathrm{mm};$$

$$\mathrm{BK3}=430\mathrm{mm}+-80\mathrm{mm},\mathrm{vorzugsweise}+-40\mathrm{mm};$$

$$\mathrm{BK4}=538\mathrm{mm}+-80\mathrm{mm},\mathrm{vorzugsweise}+-50\mathrm{mm};$$

$$\mathrm{BK5}=\left(\mathrm{BK3}-\mathrm{BK}2\right)/2=\mathrm{bspw}.65\mathrm{mm}+-30\mathrm{mm},\mathrm{vorzugsweise}+-20\mathrm{mm};$$

$$\mathrm{BK6}=307\mathrm{mm}+-50\mathrm{mm},\mathrm{vorzugsweise}+-20\mathrm{mm};$$

$$\mathrm{BK7}=82\mathrm{mm}+-20\mathrm{mm},\mathrm{vorzugsweise}+-20\mathrm{mm};$$

$$\mathrm{BK8}=379\mathrm{mm}+-40\mathrm{mm},\mathrm{vorzugsweise}+-20\mathrm{mm};$$

$$\mathrm{BK9}=470\mathrm{mm}+-50\mathrm{mm},\mathrm{vorzugsweise}+-20\mathrm{mm};$$

$$\mathrm{BK10}=232\mathrm{mm}+-40\mathrm{mm},\mathrm{vorzugsweise}+-20\mathrm{mm};$$

$$\mathrm{BK}11=380\mathrm{mm}+-60\mathrm{mm},\mathrm{vorzugsweise}+-30\mathrm{mm};$$

$$\mathrm{BK}12=460\mathrm{mm}+-\mathrm{8}0\mathrm{mm},\mathrm{vorzugsweise}+-30\mathrm{mm}\mathrm{.}$$

The in the Figures 3 and 4 The dimensions given and determined via CFD calculations and practical experiments for an exemplary boiler with approx. 100 kW are as follows: $$\mathrm{BK1}=172\mathrm{mm}+-40\mathrm{mm},\mathrm{preferably}+-17\mathrm{mm};$$

$$\mathrm{BK2}=300\mathrm{mm}+-50\mathrm{mm},\mathrm{preferably}+-30\mathrm{mm};$$

$$\mathrm{BK3}=430\mathrm{mm}+-80\mathrm{mm},\mathrm{preferably}+-40\mathrm{mm};$$

$$\mathrm{BK4}=538\mathrm{mm}+-80\mathrm{mm},\mathrm{preferably}+-50\mathrm{mm};$$

$$\mathrm{BK5}=\left(\mathrm{BK3}-\mathrm{<figure-callout\; id="2"\; label="BK"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">BK</figure-callout>}2\right)/2=\mathrm{e.g}.65\mathrm{mm}+-30\mathrm{mm},\mathrm{preferably}+-20\mathrm{mm};$$

$$\mathrm{BK6}=307\mathrm{mm}+-50\mathrm{mm},\mathrm{preferably}+-20\mathrm{mm};$$

$$\mathrm{BK7}=82\mathrm{mm}+-20\mathrm{mm},\mathrm{preferably}+-20\mathrm{mm};$$

$$\mathrm{BK8}=379\mathrm{mm}+-40\mathrm{mm},\mathrm{preferably}+-20\mathrm{mm};$$

$$\mathrm{BK9}=470\mathrm{mm}+-50\mathrm{mm},\mathrm{preferably}+-20\mathrm{mm};$$

$$\mathrm{BK10}=232\mathrm{mm}+-40\mathrm{mm},\mathrm{preferably}+-20\mathrm{mm};$$

$$\mathrm{<figure-callout\; id="11"\; label="BK"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">BK</figure-callout>}11=380\mathrm{mm}+-60\mathrm{mm},\mathrm{preferably}+-30\mathrm{mm};$$

$$\mathrm{<figure-callout\; id="12"\; label="BK"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">BK</figure-callout>}12=460\mathrm{mm}+-\mathrm{8th}0\mathrm{mm},\mathrm{preferably}+-30\mathrm{mm}\mathrm{.}$$

In the present case, both the geometries of the primary combustion zone 26 and the secondary combustion zone 27 of the combustion chamber 24 are optimized with these values. The specified size ranges are ranges with which the requirements are (approximately) fulfilled as well as with the specified exact values.

A chamber geometry of the primary combustion zone 26 and the combustion chamber 24 (or an inner volume of the primary combustion zone 26 of the combustion chamber 24) can preferably be defined using the following basic parameters:

A volume with an oval horizontal base measuring 380 mm +- 60 mm (preferably +-30 mm) × 320 mm +- 60 mm (preferably +-30 mm), and a height of 538 mm +- 80 mm ( preferably +- 50 mm).

The size information given above can also be applied to boilers in other output classes (e.g. 50 kW or 200 kW) scaled in relation to one another.

As a further development, the volume defined above can have an upper opening in the form of a combustion chamber nozzle 203, which is provided in the secondary combustion zone 27 of the combustion chamber 24, which has a combustion chamber slope 202 protruding into the secondary combustion zone 27, which preferably contains the heat exchange medium 38. Combustion chamber slope 202 reduces the cross section of secondary combustion zone 27. Combustion chamber slope 202 is inclined by an angle k of at least 5%, preferably by an angle k of at least 15% and even more preferably by at least an angle k of 19% with respect to an imaginary Horizontal or straight combustion chamber ceiling H (cf. the dashed horizontal line H in 4 ) intended.

In addition, a combustion chamber cover 204 is provided, likewise inclined in the direction of the inlet 33 . The combustion chamber 24 in the secondary combustion zone 27 thus has the combustion chamber ceiling 204 which is provided inclined upwards in the direction of the inlet 33 of the heat exchanger 3 . This combustion chamber ceiling 204 extends in section 2 at least largely straight or rectilinear and inclined. The angle of inclination of the straight or flat combustion chamber ceiling 204 can preferably be 4 to 15 degrees relative to the (fictitious) horizontal.

With the combustion chamber ceiling 204, a further (ceiling) slope is provided in the combustion chamber 24 in front of the inlet 33, which forms a funnel together with the combustion chamber slope 202. This funnel turns the swirl or vortex flow directed upwards to the side and directs this flow roughly into the horizontal around. Due to the already turbulent upward flow and the funnel shape in front of the inlet 33, it is ensured that all heat exchanger tubes 32 or boiler tubes 32 are flown evenly, whereby an evenly distributed flow of the flue gas in all boiler tubes 32 is ensured. This optimizes the heat transfer in the heat exchanger 3 considerably.

In particular, the combination of the vertical and horizontal inclines 203, 204 in the secondary combustion zone in combination as the inflow geometry in the convective boiler can achieve a uniform distribution of the flue gas over the convective boiler tubes.

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. This causes the flue gas to be distributed as evenly as possible to the individual boiler tubes in order to optimize the heat transfer there.

In detail, the combination of the inclines with the inflow cross section of the boiler rotates the flue gas flow in such a way that the flue gas flow or the flow rate is distributed as evenly as possible over the respective boiler tubes 32 .

In the prior art, there are often combustion chambers with a rectangular or polygonal combustion chamber and nozzle, but the irregular shape of the combustion chamber and the nozzle and their interaction represent a further obstacle to an even air distribution and a good mixture of air and fuel and thus good combustion , as recognized herein. In particular, with an angular geometry of the combustion chamber, flow threads or preferential flows arise, which disadvantageously lead to an uneven flow of the heat exchanger tubes 32 .

Therefore, in the present case, the combustion chamber 24 is provided without dead corners or dead edges.

It was thus recognized in the present case that the geometry of the combustion chamber (and the entire course of flow in the boiler) plays a decisive role in the considerations for optimizing the biomass heating system 1 . For this reason, the oval or round basic geometry described here without dead corners was chosen (in contrast to the usual rectangular or polygonal or purely cylindrical shapes). In addition, this basic geometry of the combustion chamber and its structure has been optimized with the dimensions/dimension ranges specified above. These dimensions/dimensional ranges are selected in such a way that, in particular, different fuels (wood chips and pellets) with different qualities (for example with different water contents) can be burned with a very high level of efficiency. This was the result of practical tests and CFD simulations.

In particular, the primary combustion zone 26 of the combustion chamber 24 can comprise a volume which preferably has an oval or approximately circular horizontal cross-section on the outer circumference (such a cross-section is shown in 2 marked with A1 as an example). This horizontal cross section can also preferably represent the base area of the primary combustion zone 26 of the combustion chamber 24 . The combustion chamber 24 can have an approximately constant cross section over the height indicated by the double arrow BK4. In this respect, the primary combustion zone 24 can have an approximately oval-cylindrical volume. Preferably, the side walls and base (grate) of the primary combustion zone 26 may be perpendicular to one another. The bevels 203, 204 described above can be provided as integrated walls of the combustion chamber 24, with the bevels 203, 204 forming a funnel which opens into the inlet 33 of the heat exchanger 33 and has the smallest cross section there.

The term "approximately" is used above because of course individual notches, design-related deviations or small asymmetries can be present, for example at the transitions of the individual combustion chamber bricks 29 to one another. However, these minor deviations only play a subordinate role in terms of flow technology.

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. Further, the horizontal cross-section of the combustor 24, and particularly the primary combustion zone 26 of the combustor 24, may preferably be a regular (and/or symmetrical) ellipse.

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

An oval-cylindrical primary combustion zone 26 of the combustion chamber 24 is thus provided in the present case, which, according to CFD calculations, enables a significantly more uniform and better air distribution in the combustion chamber 24 than in the case of rectangular combustion chambers of the prior art. The lack of dead spaces also avoids zones in the combustion chamber with poor air flow, which increases efficiency and reduces slag formation.

Likewise, the nozzle 203 in the combustion chamber 24 is designed as an oval or approximately circular constriction in order to further optimize the flow conditions. The swirl of the flow in the primary combustion zone 26 explained above, which is caused by the specially designed secondary air nozzles 291 according to the invention, leads to a roughly helical or spiral upward flow pattern, with an equally oval or approximately circular nozzle favoring this flow pattern, and not as usual rectangular nozzles interferes. This optimized nozzle 203 bundles the flue gas-air mixture flowing upwards rotating and ensures better mixing, preservation of the eddy currents in the secondary combustion zone 27 and thus complete combustion. This also minimizes the excess air required. This improves the combustion process and increases efficiency.

In particular, the combination of the above (and again below with reference to the 19 explained) secondary air nozzles 291 and the eddy currents induced thereby with the optimized nozzle 203 of the bundling of the upwardly rotating flue gas/air mixture. This ensures at least approximately complete combustion in the secondary combustion zone 27.

Thus, a turbulent or swirling flow is bundled through the nozzle 203 and directed upwards, with the result that this flow extends further upwards than is usual in the prior art. As can be seen by the person skilled in the art from the laws of physics relating to the angular momentum, this is due to the reduction in the distance of the swirling air flow to the rotation or swirl center axis, which is forced by the nozzle 203 (compare analogously to the physics of the pirouette effect).

In addition, the course of the flow in the secondary combustion zone 27 and from the secondary combustion zone 27 to the boiler tubes 32 is presently optimized, as explained in more detail below.

The combustion chamber slope 202 of 4 , which without a reference number in the 2 and 3 can be seen and where the combustion chamber 25 (or its cross-section) tapers at least approximately linearly from bottom to top, according to CFD calculations ensures that the flue gas flow in the direction of the heat exchange device 4 is made more uniform, which means that its efficiency can be improved. 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 to the heat exchange device 4 and is provided rounded at the point of maximum narrowing. Parallel or straight combustion chamber walls without a taper (so as not to impede the flue gas flow) are common in the prior art. In addition, there is, individually or in combination, the combustion chamber cover 204, which extends obliquely upwards towards the inlet 33 to the horizontal and diverts the turbulent flows in the secondary combustion zone 27 laterally, thereby equalizing their flow velocity distribution.

The inflow or deflection of the flue gas flow in front of the tube bundle heat exchanger is designed in such a way that an uneven flow of the tubes is avoided as far as possible, whereby temperature peaks in individual boiler tubes 32 can be kept low and thus the heat transfer in the heat exchanger 4 can be improved (best possible use of the heat exchanger surfaces). . As a result, the efficiency of the heat exchange device 4 is improved.

In detail, the gaseous volume flow of the flue gas is conducted through the inclined combustion chamber wall 203 at a uniform speed (even in the case of different combustion states) to the heat exchanger tubes or the boiler tubes 32. This effect is further intensified by the sloping combustion chamber ceiling 204, with a funnel effect being brought about. The result is a uniform heat distribution of the heat exchanger surfaces affecting the individual boiler tubes 32 and thus an improved use of the heat exchanger surfaces. The exhaust gas temperature is thus reduced and the efficiency increased. The flow distribution is particularly at the in the 3 shown indicator line WT1 much more evenly than in the prior art. The line WT1 represents an entry 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 set up as homogeneously as possible or is approximately evenly distributed over the cross-section of the boiler tubes 32 (due to of flow screens at the entrance 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 last boiler train minimizes strand formation and thereby also optimizes the separation efficiency of the filter device 4 and the heat transfer in the biomass heating system 1.

Furthermore, an ignition device 201 is provided in the lower part of the combustion chamber 25 on the fuel bed 28 . This can cause initial ignition or re-ignition of the fuel. The ignition device 201 can be a glow igniter be. The ignition device is advantageously stationary and offset horizontally to the side relative to the location at which the fuel is introduced.

Furthermore, a lambda probe (not shown) can (optionally) be provided after the exit of the flue gas (ie, after S7) from the filter device. A controller (not shown) can use the lambda probe 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, the result is high efficiency and higher efficiency.

This in figure 5 The fuel bed 28 shown shows a rough fuel distribution due to the feeding of the fuel from the right side of the figure 5 .

Next is in the 4 and 5 a combustion chamber nozzle 203 is shown in which a secondary combustion zone 27 is provided and which accelerates and focuses the flue gas flow. As a result, the flue gas flow is better mixed and can burn more efficiently in the post-combustion zone 27 or secondary combustion zone 27 . The area ratio of the combustion chamber nozzle 203 is in a range from 25% to 45%, but is preferably 30% to 40%, and is, for example for a 100 kW biomass heating system 1, ideally 36% +/- 1% (ratio of the measured input area to the measured exit area of the nozzle 203).

Consequently, the above information on the combustion chamber geometry of the primary combustion zone 26 together with the geometry of the secondary air nozzles 291 and the nozzle 203 represent an advantageous development of the present disclosure.

(combustion chamber bricks)

the 6 shows a three-dimensional sectional view (obliquely from above) of the primary combustion zone 26 and the isolated part of the secondary combustion zone 27 of the combustion chamber 24 with the rotary grate 25, and in particular the special design of the combustion chamber bricks 29. The 7 shows according to 6 one Exploded view of the combustion chamber bricks 29. The views of 6 and 7 can preferably with the dimensions listed above 4 and 5 be executed. However, this is not necessarily the case.

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

Form-fitting grooves 261 and projections 262 (in 6 to avoid redundancies in the figures, only a few of these are designated by way of example) are provided in order to create a mechanical and largely airtight connection, in order in turn to prevent the ingress of disturbing external air. Preferably, every two at least largely symmetrical combustion chamber bricks (with the possible exception of the openings for the secondary air or the recirculated flue gas) form a complete ring. Furthermore, three rings are preferably stacked on top of one another in order to form the primary combustion zone 26 of the combustion chamber 24 which is oval-cylindrical or alternatively at least approximately circular (the latter is not shown).

Three further combustion chamber bricks 29 are provided as the upper closure, with the annular nozzle 203 being supported by two retaining bricks 264 which are placed on the upper ring 263 in a form-fitting manner. All bearing surfaces 260 have grooves 261 either for mating projections 262 and/or for the insertion of suitable sealing material.

The mounting stones 264, which are preferably symmetrical, can preferably have an inwardly inclined bevel 265 in order to make it easier for fly ash to be swept away onto the rotary grate 25.

The lower ring 263 of the combustion chamber bricks 29 rests on a base plate 251 of the rotary grate 25 . Ash is increasingly deposited on the inner edge between this lower ring 263 of the combustion chamber bricks 29 , which advantageously independently and advantageously seals this transition during operation of the biomass heating system 1 .

The openings for the recirculation nozzles 291 or secondary air nozzles 291 are provided in the middle ring of the combustion chamber bricks 29 . The secondary air nozzles 291 are provided at least approximately at the same (horizontal) height of the combustion chamber 24 in the combustion chamber bricks 29 .

Three rings of combustor bricks 29 are provided here, as this represents the most efficient way of manufacture and also of maintenance. Alternatively, 2, 4 or 5 such rings can also be provided.

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

The combustion chamber bricks 29 are provided as molded bricks. The combustion chamber bricks 29 are shaped in such a way that the interior volume of the primary combustion zone 26 of the combustion chamber 24 has an oval horizontal cross-section, which means that dead corners or dead spaces, which are usually not optimally flown through by the flue gas-air mixture, are avoided by an ergonomic shape, whereby the fuel present there is not is optimally burned. Due to the present shape of the combustion chamber bricks 29, the flow of primary air through the grate 25, which also suits the distribution of the fuel over the grate 25, and the possibility of unhindered turbulent flows is improved; 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 inside diameter BK3 and the largest inside diameter BK11. These measurements were the result of the optimization of the primary combustion zone 26 of the combustor 24 by means of CFD simulation and practical tests.

(rotary grate)

8 shows a plan view of the rotary grate 25 from above seen from the section line A1 of FIG 2 .

The supervision of 8 can preferably be designed with the dimensions listed above. However, this is not necessarily the case.

The rotary 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 rotary grate element 252, a second rotary grate element 253 and a third rotary grate element 254, which are rotatably mounted. Thus, the rotary grate 25 is provided as a rotary grate with three individual elements, i. i.e. this can also be referred to as a triple rotary grate. Air holes are provided in the rotary grate elements 252, 253 and 254 for primary air to flow through.

The rotary grate elements 252, 253 and 254 are flat and heat-resistant metal plates, for example made of cast metal, which have an at least largely planar configured surface on the upper side and are connected to the bearing axles 81 on the lower side, for example via intermediate mounting elements. When viewed from above, rotating grate elements 252, 253 and 254 have curved and complementary sides or contours.

In particular, the rotating grate elements 252, 253, 254 may have complementary and curved sides, preferably the second rotating grate element 253 has concave sides to 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 crushing function of the rotary grate elements, since the length of the fracture is increased and the forces acting to break (similar to scissors) act in a more targeted manner.

$$\mathrm{DR}2=350\mathrm{mm}+-60\mathrm{mm},\mathrm{bevorzugt}+-20\mathrm{mm}$$

The rotary grate elements 252, 253 and 254 (and their enclosure in the form of the transition element 255) have an approximately oval outer shape when viewed together, which in turn avoids dead corners or dead spaces in which suboptimal combustion could take place or ash could accumulate could accumulate undesirably. The optimal dimensions of this outer shape of the rotating grate elements 252, 253 and 254 are in 8 denoted by the double arrows DR1 and DR2. Preferably, but not exclusively, DR1 and DR2 are defined as follows: $$\mathrm{<figure-callout\; id="1"\; label="DR"\; filenames="imgf0001.png,imgf0018.png"\; state="\{\{state\}\}">DR</figure-callout>}1=288\mathrm{mm}+-40\mathrm{mm},\mathrm{preferred}+-20\mathrm{<figure-callout\; id="2"\; label="mm\; DR"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">mm\; </figure-callout>}$$

$$\mathrm{DR}$$$$2=350\mathrm{mm}+-60\mathrm{mm},\mathrm{preferred}+-20\mathrm{mm}$$

These values have turned out to be optimal values (ranges) in the CFD simulations and the following practical test. These dimensions correspond to those of 4 and 5 . These dimensions are particularly advantageous for the combustion of different fuels or the fuel types wood chips and pellets (hybrid firing) in a power range of 20 to 200 kW.

The rotary grate 25 has an oval combustion surface, 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 formed at the core by the surfaces of the rotary grate members 252, 253 and 254 (in the horizontal state). The combustion surface is therefore the upward-pointing surface of the rotary grate elements 252, 253 and 254. This oval combustion surface advantageously corresponds to the fuel support surface if this is applied or pushed laterally onto the rotary grate 25 (cf. arrow E of 9 , 10 and 11 ). In particular, the fuel can be supplied from a direction that parallel to a longer central axis (main axis) of the oval combustion surface of the rotary grate 25.

The first rotary grate element 252 and the third rotary grate element 254 can preferably be configured 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. For example, this is in 9 1, with the first rotating grate element 252 and the third rotating grate element 254 having the same shape.

Furthermore, the second rotary grate element 253 is arranged between the first rotary grate element 252 and the third rotary grate element 254 .

The rotary grate 25 is preferably provided with an approximately point-symmetrical, oval combustion surface 258 .

Likewise, the rotary grate 25 can form an approximately elliptical combustion surface 258, with DR2 being the dimensions of its major axis and DR1 being the dimensions of its minor axis.

Furthermore, the rotary grate 25 can have an approximately oval combustion surface 258 which is axisymmetric with respect to a central axis of the combustion surface 258 .

Furthermore, the rotary grate 25 can have an approximately circular combustion surface 258, which entails minor disadvantages in terms of fuel supply and distribution.

Two motors or drives 231 of the rotary mechanism 23 are also provided, with which the rotary grate elements 252, 253 and 254 can be rotated accordingly. More about the special function and the advantages of the present rotary grate 25 is later with reference to the figures 9 , 10 and 11 described.

In particular in the case of pellet and wood chip heating systems (and in particular in the case of hybrid biomass heating systems), failures due to slag formation in the combustion chamber 24, in particular on the rotary grate 25, can increasingly occur. Slag is always produced during a combustion process when temperatures above the ash melting point are reached in the embers. The ash then softens, sticks together, and cools to form a solid, and often dark-colored, slag. This process, also referred to 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 itself off. The combustion chamber 24 usually has to be opened and the slag removed.

The ash melting range (this extends from the sintering point to the flow point) depends very significantly on the fuel used. Spruce wood, for example, has a critical temperature of around 1,200 °C. However, the ash melting range of a fuel can also be subject to strong fluctuations. Depending on the quantity and composition of the minerals contained in the wood, the behavior of the ash changes during the combustion process.

Another factor that can influence slag formation is the transport and storage of the wood pellets or chips. This is because they should reach the combustion chamber 24 as undamaged as possible. If the wood pellets have already crumbled when they enter the combustion process, this increases the density of the ember bed. The result is more slag formation. In particular, the transport from the storage room to the combustion chamber 24 is of importance here. Particularly long distances, as well as curves and angles, lead to damage or abrasion of the wood pellets.

Another factor relates to the control of the combustion process. So far, efforts have been made to keep the temperatures rather high in order to achieve the best possible burnout and low emissions. An optimized combustion chamber geometry and geometry of the combustion zone 258 of the rotary grate 25 makes it possible to keep the combustion temperature at the grate lower and high in the area of the secondary air nozzles 291, and thus to reduce slag formation on the grate.

In addition, the resulting slag (and also the ash) can advantageously be removed due to the special shape and the functionality of the present rotary grate 25 . This will now be related to the figures 9 , 10 and 11 explained in more detail.

the figures 9 , 10 and 11 show a three-dimensional view of the rotary grate 25 with the base plate 251, the first rotary grate element 252, the second rotary grate element 253 and the third rotary grate element 254. The views of FIG 9 , 10 and 11 can preferably correspond to the dimensions listed above. However, this is not necessarily the case.

This view shows the rotary grate 25 as a free slide-in part with rotary grate mechanism 23 and drive(s) 231. The rotary grate 25 is mechanically provided in such a way that it can be individually prefabricated in the manner of the modular system, and as a slide-in part inserted into a provided elongated opening of the boiler 11 and can be installed. This also facilitates the maintenance of this wear-prone part. The rotary grate 25 can thus preferably have a modular design, in which case it can be quickly and efficiently removed and reinserted as a complete part with rotary grate mechanism 23 and drive 231 . The modularized rotary grate 25 can thus also be assembled and disassembled using quick-release fasteners. In contrast, prior art rotary grates are typically 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. Furthermore, end stop switches can be provided which provide end stops for the end positions of the rotating grate elements 252, 253 and 254 respectively.

The individual components of the rotary grate mechanism 23 are intended to be exchangeable. For example, the gears are provided to be plugged. This facilitates maintenance and also a side change of the mechanics during assembly, if necessary.

In the rotary grate elements 252, 253 and 254 of the rotary grate 25, the openings 256 already mentioned are provided. The rotary grate elements 252, 253 and 254 can each be rotated by at least 90 degrees, preferably at least 120 degrees, even more preferably by 170 degrees, via their respective bearing axles 81, which are driven by the drive 231, in this case the two motors 231, via the rotary mechanism 23 Degrees are rotated about the respective bearing or axis of rotation 81. The maximum angle of rotation can be 180 degrees or a little less than 180 degrees, as the grate lips 257 allow. The rotary mechanism 23 is set up in such a way that the third rotary grate element 254 can be rotated individually and independently of the first rotary grate element 252 and the second rotary grate element 243, and that the first rotary grate element 252 and the second rotary grate element 243 are rotated together and independently of the third rotary grate element 254 be able. The rotary mechanism 23 can be provided accordingly, for example by means of running wheels, toothed or drive belts and/or gears.

The rotary grate elements 252, 253 and 254 can preferably be produced as a cast grate with a laser cut in order to ensure precise shape retention. This in particular in order to define the air flow through the fuel bed 28 as precisely as possible and to avoid disturbing air currents, for example strands of air 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 arranged in such a way that they are small enough for the usual pellet material and/or the usual wood chips not to fall through and large enough for the fuel to flow well with air can be. In addition, the openings 256 are dimensioned large enough that they can be blocked by ash particles or impurities (e.g. no stones in the fuel).

9 12 now shows the rotary grate 25 in the closed position, with all rotary grate elements 252, 253 and 254 being horizontally aligned or closed. This is the position in normal operation. Due to the even arrangement of the large number of Openings 256 ensure a uniform flow through the fuel bed 28 (this is shown in 9 not shown) on the rotary grate 25 ensured. In this respect, the optimal combustion state can be produced here. The fuel is applied to the rotary grate 25 from the direction of arrow E; to that extent the fuel from the right side of the 9 pushed up onto the rotary grate 25.

During operation, ash and/or slag accumulates on the rotary grate 25 and in particular on the rotary grate elements 252, 253 and 254. The rotary grate 25 can be cleaned efficiently with the present rotary grate 25 .

10 shows the rotary grate in the state of a partial cleaning of the rotary grate 25 in ember maintenance mode. To this end, only the third rotating grate element 254 is rotated. Because only one of the three rotary grate elements is rotated, the embers are retained on the first and second rotary grate elements 252, 253, while at the same time the ash and slag can fall out of the combustion chamber 24 downwards. As a result, no external ignition is required to resume operation (this saves up to 90% ignition energy). A further consequence is a reduction in wear on the ignition device (for example an ignition rod) and a saving in electricity. Ash cleaning can also advantageously take place during operation of the biomass heating system 1 .

10 also shows a state of ember maintenance during a (often already sufficient) partial cleaning. The operation of the system 1 can thus advantageously take place more continuously, which means that, in contrast to the usual full cleaning of a conventional grate, there is no need for lengthy, complete ignition, which can take several tens of minutes.

In addition, any potential slag formation or slag accumulation on the two outer edges of the third rotary grate element 254 is broken up as it rotates, with the curved outer edges of the third rotary grate element 254 not only shearing off over a greater overall length than with conventional rectangular elements of the stand of the technique, but also with an uneven distribution of movement in relation to the outer edge (in the There is more movement in the center than at the bottom and top edges). The breaker function of the rotating grate 25 is thus significantly strengthened.

In 10 grate lips 257 (on both sides) of the second rotary grate element 253 can be seen. These grate lips 257 are set up in such a way that the first rotary grate element 252 and the third rotary grate element 254 rest on the upper side of the grate lips 257 when they are closed, and the rotary grate elements 252, 253 and 254 are therefore provided without a gap and are therefore provided with a seal. This avoids strands of air and undesired uneven primary air flows through the bed of embers. This advantageously improves the efficiency of the combustion.

11 shows the rotary grate 25 in the state of universal cleaning, which is preferably carried out during a plant standstill. 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. This enables the rotary grate 25 to be completely emptied on the one hand and the ash and slag now broken up on four odd outside edges. In other words, an advantageous 4-fold breaker function is realized. The above in relation to 9 What is explained with regard to the geometry of the outer edges also applies with regard to 10 .

In summary, the present rotary grate 25 realizes in addition to normal operation (cf. 9 ) advantageously two different types of cleaning (cf. 10 and 11 ), whereby the partial cleaning allows a cleaning during the operation of the system 1.

In comparison to this, commercially available rotary grate systems are not ergonomic and, due to their rectangular geometry, have disadvantageous dead spots in which the primary air cannot optimally flow through the fuel, with the result that air strands can form. At these corners, there is also an accumulation of slag formation. These points ensure poorer combustion with poorer efficiency.

The existing simple mechanical structure of the rotary grate 25 makes it robust, reliable and durable.

(heat exchanger)

To optimize the heat exchanger 3, CFD simulations and practical tests were again carried out in synergy with the combustion chamber geometries described above. It was also checked to what extent a spring turbulator or a band turbulator or a combination of both can improve the efficiency of the heat exchange process without, however, allowing the pressure loss in the heat exchanger 3 to become too great. Turbulators increase the formation of turbulence in the boiler tubes 32, which reduces the flow rate, increases the residence time of the flue gas in the boiler tube 32 and thus increases the efficiency of the heat exchange. In detail, the boundary layer of the flow on the pipe wall is broken up, which improves heat transfer. However, the more turbulent the flow, the greater the pressure loss.

In the present case, slight soiling (so-called fouling with a thickness of 1 mm) was also taken into account for all surfaces in contact with flue gas. The emissivity of such a fouling layer was set at 0.6.

The result of this optimization is in 12 shown, which is a cut-out detail view of the 2 is.

The heat exchanger 3 has a vertically arranged bundle of boiler tubes 32, each boiler tube 32 preferably being provided with both a spring and a band or spiral turbulator. The respective spring turbulator 36 preferably extends over the entire length of the respective boiler tube 32 and is designed in the shape of a spring. The respective band turbulator 37 preferably extends over about half the length of the respective boiler tube 32 and has a spiral shape in the axial direction of the Boiler tube 32 extending band with a material thickness of 1.5 mm to 3 mm. Furthermore, the respective band turbulator 37 can also be approximately 35% to 65% of the length of the respective boiler tube 32. Each band turbulator 37 is preferably disposed with one end at the downstream end of each boiler tube 32 . The combination of spring and ribbon or spiral turbulator can also be referred to as a double turbulator. In 12 Both ribbon and spiral turbulators are shown. In the present dual turbulator, the band turbulator 37 is located within the spring turbulator 36 .

Band turbulators 37 are provided because the band turbulator 37 increases the turbulence effect in the boiler tube 32 and causes a more homogeneous temperature and velocity profile viewed over the tube cross-section, while the tube without a band turbulator preferably forms a hot streak with higher velocities in the center of the tube, which extends to the outlet of the boiler tube 32, which would adversely affect the heat transfer efficiency. The band turbulators 37 in the lower area of the boiler tubes 32 thus improve the convective heat transfer.

As an optimum example, 22 boiler tubes with a diameter of 76.1 mm and a wall thickness of 3.6 mm can be used.

The pressure loss in this case can be less than 25 Pa. In this case, the spring turbulator 36 ideally has an outer diameter of 65 mm, a pitch of 50 mm, and a profile of 10×3 mm. In this case, the band turbulator 37 can have an outer diameter of 43 mm, a pitch of 150 mm and a profile of 43×2 mm. A sheet metal thickness of the band turbulator can be 2 mm.

Good efficiency is achieved with 18 to 24 boiler tubes and a diameter of 70 to 85 mm with a wall thickness of 3 to 4.5 mm. Correspondingly adapted spring and band turbulators can be used.

However, in order to achieve sufficient efficiency, between 14 and 28 boiler tubes 32 with a diameter between 60 and 80 mm and a wall thickness of 2 to 5 mm can be used. In these cases, the pressure loss can be between 20 and 40 Pa, and can therefore be rated as positive. The outer diameter, pitch and profile of the spring and ribbon turbulators 36, 37 is provided to be adjusted accordingly.

The desired target temperature at the outlet of the boiler tubes 32 can preferably be between 100 and 160 degrees Celsius at rated output.

(cleaning device for the boiler)

13 shows a cleaning device 9 with which both the heat exchanger 3 and the filter device 4 can be cleaned (off) automatically. the 13 shows the cleaning device from the boiler 11 for the sake of clarity. The cleaning device 9 relates to the entire boiler 11 and thus relates to the convective part of the boiler 11 and also the last boiler pass, in which the electrostatic filter device 4 can optionally be integrated.

The cleaning device 9 has two cleaning drives 91, preferably electric motors, which rotatably drive two cleaning shafts 92, which in turn are mounted in a shaft holder 93. The cleaning shafts 92 can preferably also be mounted rotatably at another location, for example at the remote ends. The cleaning shafts 92 have extensions 94 to which the cage 48 of the filter device 4 and turbulator holders 95 are connected via joints or via rotary bearings.

The turbulator mount 95 is in 14 highlighted and enlarged. The turbulator mount 95 is designed in the manner of a comb and is preferably designed to be horizontally symmetrical. Furthermore, the turbulator mount 95 is a flat metal piece with a material thickness in the thickness direction D between 2 and 5 mm educated. The turbulator mount 95 has two pivot bearing mounts 951 on its underside for connection to pivot bearing journals (not shown) of the extensions 94 of the cleaning shafts 92 . The pivot mounts 951 have a horizontal clearance in which pivot pins or a pivot linkage 955 can move back and forth. Vertically protruding extensions 952 have a plurality of recesses 954 in and with which the double turbulators 36, 37 can be attached. The recesses 954 can be at a distance from one another which corresponds to the pitch of the double turbulators 36, 37. In addition, passages 953 for the flue gas can preferably be arranged in the turbulator holder 95 in order to optimize the flow from the boiler tubes 32 into the filter device 4 . Otherwise the flat metal would be at right angles to the flow and impede it too much.

In addition, when the respective spring turbulator 36 including the spiral turbulator (double turbulator) is installed, the spiral automatically rotates under its own weight into the receptacle of the turbulator holder 95 (which can also be referred to as the receiving rod) and is thus fixed and secured. This makes assembly much easier.

the figures 15 and 16 show the cleaning mechanism 9 without the cage 48 in two different states. The cage mount 481 can be seen better here.

15 shows the cleaning mechanism 9 in a first state, with both the turbulator mounts 95 and the cage mount 481 in a lower position. A two-armed hammer 96 with a stop head 97 is attached to one of the cleaning shafts 92 . Alternatively, the impact lever 96 can also be provided with one or more arms. The impact lever 96 with the stop head 97 is set up in such a way that it can be moved to the end of the (spray) electrode 45 or can strike against it.

16 shows the cleaning mechanism 9 in a second state, with both the turbulator mounts 95 and the cage mount 481 in an upper position.

During the transition from the first state to the second state (and vice versa), rotation of the cleaning shafts 92 by means of the cleaning drives 91 causes both the turbulator holder 95 and the cage holder 481 to be raised vertically via the extensions 952 (and a rotary bearing linkage 955). Thus, the double turbulators 36, 37 in the boiler tubes 32 and also the cage 48 in the chimney of the filter device 4 can be moved up and down and can correspondingly clean the respective walls of fly ash or the like.

In addition, the impact lever 96 with the stop head 97 can strike the end of the (spray) electrode 45 during the transition from the first state to the second state. This striking at the free (ie not suspended) end of the (spray) electrode 45 has the advantage over conventional vibrating mechanisms (in which the electrode is moved on its suspension) that the (spray) electrode 45 according to its vibration characteristics after the excitation the striking itself can vibrate (ideally freely). The type of impact determines the oscillations or oscillation modes of the (spray) electrode 45. The (spray) electrode 45 can be struck from below (ie from its longitudinal axis direction or from its longitudinal direction) for the excitation of a shock wave or a longitudinal oscillation will. However, the (spray) electrode 45 can also be located on the side (in the figures 15 and 16 be struck, for example, from the direction of arrow V), so that it oscillates transversely. Or it can be the (spray) electrode 45 (as present in figures 15 and 16 shown) are attached at the end from a slightly laterally offset direction from below. In the latter case, a plurality of different vibration modes are generated in the (spray) electrode 45 (by striking), which advantageously add up in the cleaning effect and improve the efficiency of the cleaning. In particular, the shearing effect of the transverse vibration on the surface of the (spray) electrode 45 can improve the cleaning effect.

In this respect, an impact or a shock wave can occur in the elastic spring electrode 45 in the longitudinal direction of the electrode 45, which is preferably designed as an elongated plate-shaped rod. It can also lead to a transverse vibration of the (Spray) electrode 45 (which are aligned transversely or at right angles to the direction of the longitudinal axis of the electrode 45) due to the acting transverse forces.

It is also possible to generate several types of vibration at the same time. In particular, a shock wave and/or longitudinal wave combined with a transverse vibration of the electrode 45 can again lead to improved cleaning of the electrode 45.

As a result, a fully automatic cleaning during the ash removal in a common ash box at the front of the heating system (not shown) can be realized via the discharge screw 71. Likewise, the spring steel electrode 48 can be cleaned without wear and with little noise.

Furthermore, the cleaning device 9 can be manufactured simply and inexpensively in the manner described and has a simple and low-wear structure.

Furthermore, the cleaning device 9 is set up with the drive mechanism in such a way that ash residues can advantageously be cleaned off by the turbulators as soon as the boiler tubes 32 are first pulled and can fall down.

In addition, the cleaning device 9 is installed in the lower, so-called "cold area" of the boiler 11, which also reduces wear, since the mechanics are not exposed to very high temperatures (i.e. the thermal load is reduced). In contrast to this, in the prior art, the cleaning mechanism is installed in the upper area of the system, which correspondingly disadvantageously increases wear.

In addition, regular automated cleaning improves the efficiency of the system 1 since the surfaces of the heat exchanger 3 are cleaner. The filter device 4 can also work more efficiently since its surfaces are also cleaner. This is also important because the electrodes of the filter device 4 become dirty faster than the convective part of the boiler 11.

In this way, cleaning of the electrodes of the filter device 4 is advantageously also possible during operation or during the operation of the boiler 11 .

(Modularization of plant and boiler components)

The biomass heating system 1 is preferably designed in such a way that the entire drive mechanism in the lower boiler area (including rotary grate mechanism including rotary grate, heat exchanger cleaning mechanism, drive mechanism for moving floor, mechanism for filter device, cleaning basket and drive shafts and ash discharge screw) can be quickly and efficiently removed and removed again using the "drawer principle". can be used. An example of this is above with the rotary grate 25 with respect to the Figures 9 to 11 illustrated. This facilitates maintenance work.

(ember bed height measurement)

17 shows an (exempted) ember bed height measuring mechanism 86 with a fuel level flap 83. 18 shows a detailed view of the fuel level flap 83 of FIG 17 .

In detail, the ember bed height measurement mechanism 86 has an axis of rotation 82 for the fuel level flap 83 . The pivot 82 has a central axis 832 and has a bearing notch 84 on one side for supporting the pivot 82 and a sensor flange 85 for mounting an angle or rotation sensor (not shown).

The axis of rotation 82 is preferably provided with a hexagonal profile. The holder of the fuel level flap 83 can be provided in such a way that it consists of two openings 834 with a hexagon socket. In this way, the fuel level flap 83 can simply be plugged onto the axis of rotation 82 and fixed. Furthermore, the fuel level flap 83 can be a simple sheet metal part.

The ember bed height measuring mechanism 86 is provided in the combustion chamber 24, preferably somewhat offset to the center, above the fuel bed 28 or the combustion surface 258, so that the fuel level flap 83 is raised depending on the fuel that may be present, depending on the height of the fuel or fuel bed 28 , whereby the axis of rotation 82 is rotated in dependence on the height of the fuel bed 28 . This rotation or also the absolute angle of the axis of rotation 82 can be detected by a non-contact rotation and/or angle sensor (not shown). In this way, an efficient and robust ember bed height measurement can be carried out.

In this case, the fuel level flap 83 is set up in such a way that it is slanted in relation to the central axis 823 of the axis of rotation 82 . In detail, a surface parallel 835 of a major surface 831 of the fuel level door 83 may be arranged to be angled with respect to the central axis 823 of the axis of rotation 82 . This angle can preferably be between 10 and 45 degrees. Regarding angle measurement, it should be noted that the surface parallel 835 and the central axis 823 are thought of in such a way that they can intersect (projected in the horizontal) in the central axis 823 to form the angle. Further, the surface parallel 835 is not normally oriented parallel to the leading edge of the fuel level door 83 .

Now, when fuel is supplied 6 into the combustion chamber 24, no planar fuel distribution is caused, but rather an elongated hill is thrown up. With an inclined fuel level flap 83 and a parallel orientation of the central axis 823 of the axis of rotation 82 to the surface of the rotary grate 25, the rather inclined distribution of the fuel is consequently taken into account in such a way that the main surface 831 of the fuel level flap 83 lies flat on the fuel hill or Fuel bed 28 can rest. This more extensive contact of the fuel level flap 83 reduces measurement errors caused by irregularities in the fuel bed 28 and the measurement accuracy and the ergonomics of the measurement are improved.

In addition, by means of the geometry of the fuel level flap shown above 83 the exact ember bed height can be determined using a non-contact rotary and/or angle sensor, even despite different or varying fuels (wood chips, pellets). The ergonomic, sloping shape adapts ideally to the fuel, which is also introduced at an angle due to the stoker screw, and ensures representative measured values.

The fuel height (and quantity) remaining on the combustion surface 258 of the rotary grate 25 can also be precisely determined by means of the ember bed height measurement, with which the fuel supply and the flow through the fuel bed 28 can be regulated in such a way that the combustion process can be optimized.

In addition, the production and assembly of this sensor is simple and inexpensive.

(Fluid design of the biomass heating system 1)

19 shows a horizontal cross-sectional view through the combustion chamber at the level of the secondary air nozzles 291 and along the horizontal section line A6 of FIG figure 5 .

The one in the 19 The dimensions given are only to be understood as examples and only serve to clarify the technical teaching, among other things 3 .

A length of a secondary air nozzle 291 can be between 40 and 60 mm, for example. A (maximum) diameter of the cylindrical or truncated cone-shaped secondary air nozzle 291 can be between 20 and 25 mm, for example.

The angle shown relates to the two secondary air nozzles 291 closest to the longer main axis of the oval. The angle, which is given as 26.1 degrees by way of example, is measured between the central axis of the secondary air nozzle 291 and the longer of the main axes of the oval of the combustion chamber 24. The angle can preferably in a range of 15 degrees to 35 degrees. The remaining secondary air nozzles 291 may further be provided with a central axis angle functionally equivalent to that of the two closest secondary air nozzles 291 to the longer major axis of the oval for effecting the swirling flow (e.g. with respect to the combustor wall 24).

In 19 10 secondary air nozzles 291 are shown, which are arranged in such a way that their central axis or orientation, which are shown with the respective dashed (center) lines, is provided acentrically to the (symmetry) center point of the oval of the combustion chamber geometry. In other words, the secondary air nozzles 291 are not aimed at the center of the oval combustion chamber 24, but at its center or center axis (in 4 labeled A2) over. Accordingly, the center axis A2 can also be understood as the axis of symmetry relating to the oval combustion chamber geometry 24 .

The secondary air nozzles 291 are aligned in such a way that they introduce the secondary air tangentially into the combustion chamber 24—viewed in the horizontal plane. In other words, 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. Incidentally, such a tangential entry 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 clockwise or a counterclockwise flow. In this respect, each secondary air nozzle 291 can contribute to the formation of the eddy currents, with each secondary air nozzle 291 having a similar orientation. In relation to the above, it should be noted that in exceptional cases individual secondary air nozzles 291 can also be arranged in a neutral (centered) or counter-rotating (opposite orientation) manner, although this may degrade the aerodynamic efficiency of the arrangement.

20 shows three horizontal cross-sectional views for different boiler dimensions (50 kW, 100 kW and 200 kW) through the combustion chamber 24 of FIG 2 and 4 at the height of the secondary air nozzles 291 with information on the flow distributions in this cross section in the respective nominal load case.

Same shades of gray in the 20 roughly indicate areas with the same flow velocity. General is from the 20 It can be seen that the secondary air nozzles 291 bring about nozzle flows tangentially or eccentrically into the combustion chamber 24 .

For clarification, the relevant flow velocities of these nozzle flows are explicitly shown as an example in 20 specified. It can be seen here that the resulting nozzle flows extend relatively far into the combustion chamber 24 , as a result of which strong turbulent flows can be brought about which cover a large part of the volume of the combustion chamber 24 .

The arrow in the combustion chamber 24 of the CFD calculation for a 200 kW boiler dimensioning indicates the twist or eddy direction of the eddy currents induced by the secondary air nozzles 291 . This also applies analogously to the other two boiler dimensions (50 kW, 100 kW). 20 . A clockwise rotating turbulent flow (viewed from above) is given as an example.

Secondary air (preferably simply ambient air) is introduced into the combustion chamber 24 via the secondary air nozzles 291 . The secondary air in the secondary air nozzles is accelerated to more than 10 m/s in the nozzle at nominal load. Compared to the secondary air openings customary in the prior art, the penetration depth of the resulting air jets in the combustion chamber 24 is increased, which is sufficient to induce an effective turbulent flow which spreads over most of the combustion chamber of the combustion chamber volume extends.

In the case of an oval (or also circular) cross section of a combustion chamber 24, a relatively undisturbed turbulent flow occurs when air enters the combustion chamber 24 tangentially, which can also be referred to as a swirl flow or as a turbulence sink flow. This creates spiral flows. These spiral flows propagate upwards in the combustion chamber 24 in a helical or spiral manner.

21 shows three vertical cross-sectional views for different boiler dimensions (50 kW, 100 kW and 200 kW) through the biomass heating system along the section line SL1 of the 1 with information on the tangential entry of the secondary nozzle flows into this cross-section.

Also in 21 equal shades of gray roughly indicate areas of equal flow velocity. General is from the 21 It can be seen that in the secondary combustion zone 27 candle-flame-shaped rotary flows S2 (cf. also 3 ) are present, which can advantageously reach up to the combustion chamber ceiling 204. It can also be seen that the boiler tubes 32 are flowed through quite evenly in the direction of the inlet 33 at approx. 1-2 m/s due to the previously explained funnel. Regarding the advantages and the technical background of the above, the explanations for the Figures 1 to 4 referred.

(Further embodiments)

In addition to the explained embodiments and aspects, the invention permits further design principles. Thus, individual features of the various embodiments and aspects can also be combined with one another as desired, as long as this is apparent to the person skilled in the art and falls within the subject matter defined in the claims.

Furthermore, instead of only three rotary grate elements 252, 253 and 254, two, four or more rotary grate elements can also be provided. With five rotary grate elements, for example, these could be arranged with the same symmetry and functionality as with the three rotary grate elements presented. In addition, the rotary grate elements can also be shaped or designed differently from one another. More rotary grate elements have the advantage that the crushing function is increased.

With regard to the specified dimensions, it should be noted that other dimensions or combinations of dimensions can also be provided that deviate from these.

Instead of the convex sides of the rotary grate elements 252 and 254, concave sides of these can also be provided, with the sides of the rotary grate element 253 being able to have a complementary convex shape as a result. This is functionally almost equivalent.

Although in 19 10 (Ten) secondary air nozzles 291 are specified, a different number of secondary air nozzles 291 can also be provided (depending on the dimensioning of the biomass heating system).

The rotational flow or turbulent flow in the combustion chamber 24 can be clockwise or counterclockwise.

The combustion chamber cover 204 can also be provided with an incline in sections, for example in a stepped manner.

The secondary air nozzles 291 are not limited to purely cylindrical bores in the combustion chamber bricks 291 . These can also be designed as frustoconical openings or tapered openings.

The secondary (re)circulation can also only be flown with secondary air or fresh air, and in this respect not recirculate the flue gas, but only supply fresh air.

The dimensions and numbers given in relation to the exemplary embodiments are to be understood only as examples. This technical teaching disclosed here is not limited to these dimensions and can be modified, for example, by modifying the dimensioning of the boiler 11 (kW).

Fuels other than wood chips or pellets can also be used as fuels in the biomass heating system.

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

The embodiments disclosed herein were provided for description and understanding of the disclosed technical matters and are not intended to limit the scope of the present disclosure.

(Reference List)

1

Biomass heating system

11

boiler

12

boiler foot

13

boiler housing

14

water circulation device

2

burner

21

first maintenance opening for burner

22

rotary mechanism mount

23

turning mechanism

24

combustion chamber

25

rotary grate

26

Primary combustion zone of the combustor

27

Secondary combustion zone or radiant part of the combustion chamber

28

fuel bed

29

combustion chamber bricks

A1

first horizontal cutting line

A2

first vertical section line and vertical central axis of the oval combustion chamber 24

201

ignition device

202

combustion chamber slope

203

combustor nozzle

204

combustor ceiling

231

Drive or motor(s) of the turning mechanism

251

bottom plate of the rotary grate

252

First rotary grate element

253

Second rotary grate element

254

Third rotary grate element

255

transition element

256

openings

257

rust lips

258

burn surface

260

Support surfaces of the combustion chamber bricks

261

groove

262

head Start

263

ring

264

bracket stones

265

slope of the support stones

3

heat exchanger

31

Maintenance opening for heat exchanger

32

boiler tubes

33

Boiler tube entry

34

reversing chamber entry

35

turning chamber

36

spring turbulator

37

Band or spiral turbulator

38

heat exchange medium

4

filter device

41

exhaust outlet

42

electrode supply line

43

electrode holder

44

filter inlet

45

electrode

46

electrode insulation

47

filter outlet

48

Cage

5

recirculation device

51, 54

Recirculation channel / recirculation channels

52

Succeed

53

recirculation entry

6

fuel supply

61

rotary valve

62

Fuel supply axis

63

translation mechanics

64

fuel supply channel

65

fuel supply opening

66

drive motor

67

fuel auger

7

ash removal

71

ash discharge screw

72

Ash removal motor with mechanics

81

bearing axles

82

axis of rotation

83

fuel level flap

831

main surface

832

center axis

835

surface parallel

84

bearing notch

85

sensor flange

86

Ember bed height measurement mechanism

9

cleaning device

91

cleaning drive

92

cleaning shafts

93

shaft mount

94

extension

95

turbulator mounts

951

Pivot bearing mount

952

appendages

953

culverts

954

recesses

955

pivot linkage

96

two-armed hammer

97

stop head

211

Insulating material such as vermiculite

291

Secondary air or recirculation nozzles

E

insertion direction of the fuel

331

Insulation at the boiler tube inlet

481

cage mount

Claims (11)

1. Biomass heating system (1) for the combustion of fuel in the form of pellets and/or chips, possessing:

   a boiler (11) with a combustion unit (2),

   a heat exchanger (3) with a plurality of boiler tubes (32),

   wherein said combustion unit (2) possesses the following:

   a combustion chamber (24) with a revolving grate (25), with a primary combustion zone (26) and with a secondary combustion zone (27);

   wherein the primary combustion zone (26) is encompassed laterally by a plurality of combustion chamber bricks (29) and from below by the revolving grate (25); wherein the fuel on the revolving grate (25) is combusted with primary air that flows through the revolving grate (25);

   wherein a plurality of secondary air nozzles (291) is provided in the combustion chamber bricks (29);

   wherein the primary combustion zone (26) and the secondary combustion zone (27) are separated at the level of the secondary air nozzles (291);

   wherein the secondary combustion zone (27) of the combustion chamber (24) is fluidically connected to an inlet (33) of the heat exchanger (3)

   characterised in that

   the secondary air nozzles (291) are arranged in such a way that in the secondary combustion zone (27) of the combustion chamber (24) eddy currents of a flue gas-air mixture of secondary air and flue gas that results from the combustion of the fuel develop about a vertical central axis (A2),

   wherein the eddy currents lead to an improvement in the mixing of the flue gas/air mixture.
2. Biomass heating system (1) according to claim 1, wherein
   the secondary air is ambient air fed to the combustion chamber (24).
3. Biomass heating system (1) according to claim 1 or 2, wherein
   the secondary air nozzles (291) in the combustion chamber bricks (29) are each designed as a cylindrical or truncated cone-shaped opening in the combustion chamber bricks (29) with a circular or elliptical cross section, wherein the smallest diameter of the respective opening is smaller than its maximum length.
4. Biomass heating system (1) according to one of the preceding claims, wherein

   the secondary air nozzles (291) are arranged in the combustion chamber (24) at at least approximately the same height; and

   the secondary air nozzles (291) are each oriented such that the secondary air is introduced peripherally with respect to the centre of symmetry of the combustion chamber (24).
5. Biomass heating system (1) according to one of the preceding claims, wherein

   the number of secondary air nozzles (291) is between 8 and 14; and/or

   the secondary air nozzles (291) have a minimum length of at least 50 mm with a minimum inner diameter of 20 to 35 mm.
6. Biomass heating system (1) according to one of the preceding claims, wherein
   the combustion chamber (24) in the secondary combustion zone (27) has a combustion chamber slope (202) that reduces the cross-section of the secondary combustion zone (27) in the direction of the inlet (33) of the heat exchanger (3).
7. Biomass heating system (1) according to one of the preceding claims, wherein
   the combustion chamber (24) in the secondary combustion zone (27) has a combustion chamber ceiling (204) that is provided to incline upwards towards the inlet (33) of the heat exchanger (3), and which reduces the cross section of the combustion chamber (24) in the direction of the inlet (33).
8. Biomass heating system (1) according to claim 6 and 7, wherein the combustion chamber slope (202) and the inclined combustion chamber ceiling (204) form a funnel, the smaller end of which ends in the inlet (33) of the heat exchanger (3).
9. Biomass heating system (1) according to one of the preceding claims, wherein

   the primary combustion zone (26) and at least part of the secondary combustion zone (27) have an oval horizontal cross-section;
   and/or

   the secondary air nozzles (291) are arranged in such a way that they introduce the secondary air tangentially into the combustion chamber (24).
10. Biomass heating system (1) according to one of the preceding claims, wherein

    the combustion chamber bricks (29) have a modular structure; and each two semi-circular combustion bricks (29) form a closed ring so as to form the primary combustion zone (26) and/or part of the secondary combustion zone (27); and

    at least two rings of combustor bricks (29) are stacked one on top of the other.
11. Biomass heating system (1) according to one of the preceding claims, wherein

    the heat exchanger (3) has spiral turbulators arranged in the boiler tubes (32) and extend over the entire length of the boiler tubes (32); and

    the heat exchanger (3) has strip turbulators which are arranged in the boiler tubes (32) and extend at least over half the length of the boiler tubes (32).

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