EP4289918A1 - Particulate matter-reducing composition and method for reducing fine dust in a fireplace - Google Patents

Abstract

The invention relates to a composition for reducing the formation of fine dust during the combustion of solids, comprising at least a first component that reduces the formation of fine dust, which is selected from a group consisting of Al₂O₃ , Al(OH)₃, bauxite, talc, kaolin, kaolinite and kaolin-containing clays, the composition comprising a second component which reduces particulate matter formation and which is selected from a group consisting of kaolin, metakaolin, thermally activated three-layer silicates, fly ash and microsilica and / or combinations of these substances. The invention further relates to a method for burning a solid fuel in a fireplace with the addition of such a composition.

Description

The present invention relates to a method for reducing fine dust in a fireplace and/or boiler system as well as a fine dust-reducing composition and its use. The invention further relates to a method for producing such a composition.

It is known from the prior art that some Al-containing compounds such as Al ₂ O ₃ , Al(OH) ₃ , bauxite, talc and/or kaolin or kaolinite (but also kaolin-containing clays) act as additives in the combustion of solids can be added and reduce the formation of fine dust

For example, this is off DE 10 2020 128 231 A1 an incineration system is known, which includes a kaolinite storage and dosing device for releasing kaolinite into the combustion process.

Out of DE 10 2014 210 614 B4 Pellets made from a pressed biomass are known which contain an aluminum-containing inorganic compound, clay and/or a clay mineral as an ash and/or fine dust reducing additive. This additive is intended to make it possible to use raw materials alternative to firewood, such as chips from short rotation plantations (SRC), straw, grain and the like, for the production of pellets for heating purposes in small combustion systems.

Scientific studies on the influence of kaolinite on combustion and the resulting fine dust were also carried out. Particularly worth mentioning are studies carried out at the TU Hamburg (TUHH), especially at the Institute for Environmental Technology and Energy Economics. For example, in the article Huelsmann, T., Mack, R., Kaltschmitt, M. et al. Influence of kaolinite on the PM emissions from small-scale combustion. Biomass Conv. Bioref. 9, 55-70 (2019) https://doi.org/10.1007/s13399-018-0316-8 Studies on the influence of kaolinite on particulate matter emissions are described. These studies show that a higher proportion by weight of the addition of kaolinite does not necessarily lead to a reduction in particulate matter emissions. For example, at the test stand in Hamburg, with an addition of 1 percent by weight (wt.%) of kaolinite in pellets with an average of 94 mg/Nm ³ , almost the same level of fine dust emissions in the exhaust gas were detected as without the addition of kaolinite (average of 98 mg/Nm ³ ). In contrast, with the addition of only 0.5% by weight of kaolinite in pellets, an average significantly reduced fine dust load in the exhaust gas of only 53 mg/Nm ³ could be measured. An analog comparative measurement at the Technology and Support Center in the Competence Center for Renewable Raw Materials in Straubing led to different results, in which the fine dust emissions in the exhaust gas when 1% by weight of kaolinite was added to pellets compared to the fine dust emissions in the exhaust gas from burning pellets with a Addition of just 0.5% by weight of kaolinite could be reduced further.

As can be seen from the above-mentioned prior art, the selection of the additive is not the only decisive factor in reducing fine dust when burning solids. There seem to be other factors, particularly with additives containing kaolin or kaolinite, that significantly influence the degree of fine dust reduction.

There is therefore a need to provide a composition that is particularly effective. There is also a need to provide a method with which the formation of fine dust during the combustion of (particularly organic) solids can be reduced particularly efficiently.

This task can be solved by the subject matter of the independent patent claims. Preferred embodiments are described below as such and/or are the subject of the dependent claims.

The invention therefore relates to a composition for reducing the formation of fine dust during the combustion of solids, comprising at least one first component that reduces the formation of fine dust, which is selected from a group consisting of Al ₂ O ₃ , Al(OH) ₃ , bauxite, talc, kaolin, Includes kaolinite and clays containing kaolin. In addition, a composition according to the invention comprises a second component that reduces particulate matter formation, which is selected from a group that includes kaolin, metakaolin, thermally activated three-layer silicates, fly ash and microsilica and / or combinations of these substances. It has been shown that the presence of the second component that reduces the formation of fine dust (hereinafter also referred to as the "second component") reduces the formation of fine dust even at very low combustion temperatures, for example ≤ 650 ° C, ≤ 600 ° C, ≤ 550 °C or even ≤ 500°C and/or in the event of incomplete combustion, for example due to low oxygen supply, can be significantly reduced. Even at high combustion temperatures and sufficient oxygen supply, the composition according to the invention has proven to be advantageous because it improves ash formation and, by avoiding clumping or at least reducing the tendency of the ash to clump together, enables a good long-term supply of oxygen through the fuel and the combustion chamber.

The second component preferably differs from the first component in at least one property. The first and second components can differ in a different chemical composition when different compounds are selected from the group of chemical compounds defined above. However, as an alternative or in addition to this, there is also the possibility that the first and second components differ from each other in at least one other property. This could be, for example, a different (crystal) water content. Another exemplary difference between the first and second components could be the (average) particle size (preferably d ₅₀ (Sedigraph)). Such differences between the first and second components preferably result in them reaching their maximum activity at different times during their use as an additive to a combustion process. For the examples mentioned above, it was shown that particles with a higher (crystalline) water content and/or particles with a larger (average) particle size reach their maximum activity at higher temperatures in the combustion chamber and/or at later times during a combustion process.

For the reasons explained above, it is particularly preferred that the second component is suitable for binding fine dust-forming Na and/or K salts at combustion temperatures ≤ 650 ° C. This enables the entire composition to reduce the formation of fine dust even at such low combustion temperatures. How an addition of the second component can lead to an improvement in the reduction of fine dust formation, which essentially corresponds to the reduction of a similar proportion of the first component at high combustion temperatures, has not yet been clarified, but it is assumed that due to the presence of the second Component uses the binding of fine dust and the larger particles formed, if necessary in interaction with the first component, catalyzes the further binding and thus reduction of fine dust.

Fine dust produced during the combustion of organic fuels, for example biomass, contains in particular alkali metal compounds, for example sodium or potassium compounds. For example, alkali metal hydroxides, chlorides and sulfates are of particular importance. Even if some of the substances formed during combustion are gaseous at the time of combustion, they can condense or precipitate as a solid during the cooling of the combustion gases, aggregate into larger particles and thus emerge as particulate matter emissions.

This process can be prevented or at least reduced by adding a composition according to the invention. This can be explained in particular by the fact that alkali compounds formed during combustion, as shown below using the example of a reaction of metakaolin with KOH, can be captured from the exhaust gas and converted into low-volatility components.

In the example mentioned, metakaolin reacts with KOH according to the following reaction equation to form a low-volatility potassium aluminum silicate and water: Al ₂ Si ₂ O ₇ + 2 KOH → 2 KAlSiO ₄ + H ₂ O

The potassium aluminum silicate is stable up to very high temperatures and can therefore be removed from the combustion chamber as ash. Furthermore, a formed potassium aluminum silicate particle - especially during the cooling of the exhaust gas, for example in a chimney or a heat exchanger - promotes the accumulation of further substances from the exhaust gas, for example further potassium aluminum silicate particles, so that the particles grow and precipitate out of the exhaust gas or can be easily separated from it (for example by centrifugation).

Other substances such as potassium sulfate or potassium chloride can also be converted into high-temperature stable substances and thus bound: 3 Al ₂ Si ₂ O ₇ + 3 K ₂ SO ₄ + 6 KOH → (K ₂ Al _2/3 SiO ₄ ) ₆ • Al ₂ (SO ₄ ) ₃ + 3 H ₂ O

The above reactions are shown using metakaolin as an example. However, the binding of the fine dust-forming substances is possible with all substances that form reaction products that are sufficiently resistant to high temperatures and can easily precipitate or be separated from the exhaust gas. Silicates, aluminosilicates and silicate-containing components have proven to be particularly suitable.

Preferably, the second component comprises one or more substances from a group including kaolin, halloysite, dickite and nacrite, at least one of these substances being thermally activated. Thermal activation has proven to be advantageous for these substances, as this results in the conversion of kaolin to metakaolin, for example, which is particularly suitable for binding fine dust at low temperatures. It is assumed that at least partial thermal activation also takes place during the combustion process in the known compositions. However, this only occurs at comparatively high combustion temperatures, which are not reached in some areas of the combustion chamber and/or the flame or fire. In the case of compositions without a second component, the formation of fine dust cannot be reliably reduced depending on the flame temperature and the location of the feed in the combustion chamber

A composition in which the second component is present as a particulate solid has proven to be particularly suitable. This configuration allows a large surface-to-volume ratio to be achieved. It is believed that such a ratio is beneficial in achieving the reactivity necessary to reduce particulate matter. In addition, the comparatively large surface area could promote the accumulation and thus binding of fine dust. However, the exact mode of action has not yet been fully analyzed.

Preferably the second component is thermally treated. It is preferably treated at a temperature in the range of approximately 600 - 900°C, preferably 650 - 800°C. At this Temperature, for example, kaolin converts to metakaolin. During this thermal treatment, a reaction is preferably brought about in which previously bound crystal water is released. In addition to or as an alternative to the treatment at the above-mentioned temperature, the thermal treatment preferably takes place over a period of 1 - 90 minutes, preferably 5 - 75 minutes, particularly preferably 10 - 60 minutes. As can be seen from these values, it takes some time until there is sufficient or (almost) complete conversion to the reactive component, which can bind and/or reduce the fine dust produced during combustion particularly effectively.

It inevitably follows that without the addition of such a second component at certain times (for example at the beginning of a combustion process and immediately after adding the fine dust reducing component known from the prior art to an ongoing combustion) there is not enough of the reactive component to be present Effectively reduce the formation of fine dust.

Experience shows that uncontrolled combustion in a combustion chamber can result in temperatures in a very wide temperature range. This temperature range usually includes temperatures of around 100 - 1000°C. In this temperature range, the temperature for forming the reactive component (for example metakaolin) which is particularly suitable for reducing fine dust may not be sufficient locally, or it may be locally too high and thus a further conversion to silicates with reduced reactivity takes place. The distribution of temperature in a combustion chamber can only be controlled to a limited extent, if at all, so that, for example, the formation of metakaolin during combustion cannot be controlled or controlled. Analogously, this often also applies to the residence time, which can last from a few seconds to several hours during a combustion. If the residence time is too short, often not enough of the reactive component can be formed, while if the residence time is too long, the reactive component (for example the metakaolin) can be deactivated.

These disadvantages can be counteracted by the prior production of the second component and its use in a composition according to the invention.

An embodiment has proven to be particularly preferred in which the particles of the second component have a particle size (Sedigraph) d ₉₅ ≤ 100 µm, preferably ≤ 50 µm, more preferably ≤ 20 µm and particularly preferably ≤ 10 µm. Additionally or alternatively, particle sizes d ₉₅ ≤ 1 µm, preferably ≥ 2 µm, more preferably ≥ 3 µm and particularly preferably ≥ 5 µm are preferred. These minimum sizes can improve handling and, in particular, prevent these particles from entering the environment as fine dust even during handling.

The particle size is preferably adjusted by grinding and, if necessary, subsequent sieving and/or sifting.

The ratio of the first component to the second component can be varied within a comparatively wide range and thus adapted to the conditions occurring during combustion. For example, in a preferred composition there may be a ratio of the first component that reduces fine dust formation to the second component that reduces fine dust formation in the range of 1:99 - 99:1. However, a ratio of the first component to the second component in the range of 50:50 - 98:2, more preferably 60:40 - 95:5 and particularly preferably 75:25 - 90:10 has proven to be preferred. In this ratio, the reduction of the fine dust produced during combustion can begin effectively at comparatively low temperatures, without disproportionately increasing the cost of the composition due to the second component - which is often more expensive, for example due to thermal activation and / or grinding.

In order to keep the costs for the second component low, the use of residues from other processes has proven to be particularly advantageous. When using fly ash, it is preferred that it comes from large-scale industrial processes such as electricity generation in coal-fired power plants. If, on the other hand, microsilica is used as a component or basis of the second component, it preferably comes from the fine dust produced during the production of Si metal.

In a preferred embodiment, the composition comprises a combustible substance. This is preferably selected from a group that includes wood, straw, husks, grass, bran, yeast cells, grain, hemp, fruit and/or vegetable seeds or peels, lignite, lignite coke, lignite powder, dry stillage (DDGS), hard coal, Hard coal coke, hard coal powder, charcoal, charcoal powder, plant fibers, cellulose fibers, paper and petroleum coke. This combustible substance can be added to the composition in a combustion chamber or mixed with the other components of the composition outside of a combustion chamber.

In this context, it is conceivable, for example, to press a fuel with other components of the composition, for example into logs, briquettes, pellets, oven lighters, grill lighters or similar forms that are easy to handle (and preferably without excessive dust formation).

Alternatively or additionally, it is also conceivable that a fuel forms a carrier and/or a coating for other components of the composition. For example, other components of the composition may be sprayed onto the fuel. It is preferred that the fuel forms a casing for the other components. For example, a fuel that burns particularly quickly and/or hot can ensure that other components of the composition are released and/or thermally activated particularly early in the combustion process. This embodiment is also preferred for supplying the composition into a combustion chamber and/or fireplace. The fuel can, for example, be designed as a bag in which a defined amount of the other components of the composition are contained. This means that even loose components can be fed into the combustion process in a metered manner. For example, the composition can be added in the form of bags made from plant fibers such as cellulose or paper. The covering or the bag burns quickly, so that the amount of components that previously contained it can be released.

Pure dosage variants as well as dosage variants in conjunction with other substances such as carrier materials have proven to be advantageous as the preferred dosage form of the composition. For pure dosage variants, the powder or granulate form has proven to be particularly suitable. A particularly suitable variant of administration in conjunction with other substances is the use of a suspension.

In addition, a dosage form in the form of compacted tablets has proven to be particularly suitable. Such a compacted compact can be in the form of a pellet, briquette and/or pressed log, for example. The first and second components can The composition can be pressed with itself or other substances such as auxiliary substances can be added. Both organic and inorganic auxiliary materials are conceivable as auxiliary materials. These can, for example, ensure that at elevated temperatures such as those in a combustion chamber, a compact disintegrates or is blown apart and thus a particularly large reactive surface is available for binding fine dust-promoting substances to the surface of the particles of the first and second components.

Depending on the application, the (weight) proportion of the auxiliary substances in the composition can be selected in a very large range of 99.9 - 0.1, preferably 99-1, more preferably 75 - 25. In particular, if an auxiliary substance is a fuel, it can be well over 75%, for example over 90%, ≥ 95% or even ≥ 98% and in particular be present in a very large excess compared to the first and / or second component.

Preferably the composition comprises a binder. Such a binder can be an auxiliary substance as mentioned above. It is particularly preferred that the composition has a binder if the composition is in the form of a pellet, briquette, granulate, oven lighter, grill lighter and/or pressed log. The binder is preferably selected from a group including hydrocarbon-based materials, oil, wax, paste and flour. These have proven to be particularly suitable for releasing the first and second components of the composition during combustion and for releasing no or only extremely small amounts of harmful substances during combustion, for example in the exhaust gas or the ash. The term “wax” represents all organic materials that can be used to support ignition. Examples of such waxes include oil, petroleum and low chain liquid hydrocarbons.

Waxes can also be used, for example, if the composition is in the form of or together with a wax paper, a wax paper bag, a wax-wood wool lighter, a compacted wood fiber-wax cube, a wax-containing lighter bar, a wax-containing lighter cube, a wax-containing pellet and/or or a wax-containing torch is used.

The composition preferably comprises a fuel. In particular, it is preferred that the composition comprises several different fuels. Preferably a fuel of the composition is zero or extremely low Fine dust formation is combustible. In addition or as an alternative to this, a fuel can preferably be burned with the formation of fine dust. This fuel, which can be burned with the formation of fine dust, is preferably the fuel whose formation of fine dust is to be reduced. As explained above, this (fine dust-forming fuel) is preferably selected from a group that includes wood (for example as pellets, logs, wood chips, shavings, pressed wood), straw, husks, grass, mulch, bran, yeast cells, grain, hemp, fruit - and/or vegetable kernels or peels, lignite, lignite coke, lignite powder, dry stillage (DDGS), hard coal, hard coal coke, hard coal powder, charcoal, charcoal powder, plant fibers, cellulose fibers, paper and petroleum coke. However, the fuel is not limited to the substances mentioned.

Regardless of the choice of fuel, it is preferred that the proportion of the second component, based on the fuel, be in the range of 0.05 - 5% by weight. It has been shown that with this proportion the amount of fine dust that would normally be produced when the fuel is burned can be reduced particularly efficiently. A proportion of 0.1 - 4% by weight, more preferably 0.15 - 3% by weight and particularly preferably 0.2 - 2.5% by weight has proven to be particularly efficient and therefore preferred.

Mixing ratios of the first to the second component of the composition in the range of 10:1 - 3:10, preferably 9:1 - 4:10, particularly preferably 8:1 - 5:10 have proven to be particularly preferred. Larger mixing ratios can be more cost-effective, whereas smaller mixing ratios already contain a larger proportion of the second component and can therefore already be active independently of any chemical conversion caused by the combustion itself.

A mixture as described above is preferably prepared together with at least one auxiliary substance, for example with a binder and a combustible substance, as a compact (for example as a briquette or pellet). A composition in the form of such a compact preferably has the first and second components in a total amount of 30 - 95%, preferably 40 - 90%, particularly preferably 50 - 80%.

If such a pellet (for example pellet or briquette) is burned in a furnace together with an additional (for example as described above) fuel, the pellet is preferably added in an amount such that the sum of the (weight) proportions of the first and second components based on the total mass used for combustion (i.e. including the fuel), preferably in the range of 0.05 - 5% by weight, since with this proportion the amount of fine dust that would otherwise be produced when the fuel is burned can be reduced particularly efficiently. In particular, a proportion of 0.1 - 4% by weight, more preferably 0.15 - 3% by weight and particularly preferably 0.2 - 2.5% by weight has proven to be particularly efficient. Using the example of a pellet as described above with, for example, 60% by weight of the first and second components, this means that approximately 1 g per 20 kg of fuel should be used in order to obtain a sum of the (weight) proportions of the first and second components to reach the total mass used for firing of 2.9% by weight.

The aforementioned preferred sum of the (weight) proportions of the first and second components based on the total mass used for firing have proven to be advantageous regardless of the packaging of the composition. For example, when using the composition as a powder or granulate, proportions in the above-mentioned range are advantageous.

Preferably, through the choice of the recipe (in particular the selection of the first and/or second component as well as the use of optional auxiliary materials) and/or the packaging (form of addition) and/or frequency, their addition to the combustion chamber of the oven/heating point and the respectively recommended The amount of fuel to be added, the proportion of the sum of the (weight) proportions of the first and second components, is kept within the above-mentioned framework throughout the entire combustion process.

• mindestens eine erste die Feinstaubbildung reduzierende Komponente, welche ausgewählt ist aus einer Gruppe, die Al₂O₃, Al(OH)₃, Bauxit, Talkum, Kaolin, Kaolinit und kaolinhaltige Tone umfasst, und
• eine zweite, die Feinstaubbildung reduzierende Komponente, welche ausgewählt ist aus einer Gruppe, die Kaolin, Metakaolin, thermisch aktivierte Dreischichtsilikate, Flugasche und Mikrosilica und/oder Kombinationen dieser Substanzen umfasst.

Another essential aspect of the present invention is a method for burning a solid fuel in a fireplace. In this case, a composition is added to the fuel to reduce the formation of fine dust. This composition includes

• at least one first component that reduces particulate matter formation, which is selected from a group that includes Al ₂ O ₃ , Al(OH) ₃ , bauxite, talc, kaolin, kaolinite and kaolin-containing clays, and
• a second component that reduces particulate matter formation and is selected from a group that includes kaolin, metakaolin, thermally activated trilayer silicates, fly ash and microsilica and/or combinations of these substances.

This process can effectively reduce the formation of fine dust when burning (solid) fuels.

Adding the particulate matter reduction composition to the fuel may occur before or during combustion of the fuel and may occur separately from the fuel or together with fuel. For example, the addition can take place when lighting and/or adding fuel. In addition or alternatively, the addition can take place outside or in the combustion chamber or combustion zone.

In a preferred variant of the process, a composition is used as described above on the product side.

In a preferred process variant, the composition is added to the fuel in an amount in which the proportion of the second component that reduces fine dust formation, based on the fuel, is in the range of 0.05 - 5% by weight, preferably 0.1 - 4% by weight. -%, more preferably 0.15 - 3% by weight and particularly preferably 0.2 - 2.5% by weight. It has been shown that a particularly efficient reduction in fine dust is possible with a proportion from this range. At the same time, the costs of the composition can be kept low.

With regard to the fireplace, there are no restrictions on using a composition as described above and/or carrying out the method described above. The composition can be used extremely flexibly. It can be used, for example, in individual fireplaces, individual room fire systems (e.g. a fireplace in the living room) or boiler systems of any size (e.g. central heating in single or multi-family houses) and in larger heating or cogeneration plants. Such a composition is also applicable and advantageous for use in outdoor fireplaces, in particular those powered by wood, coal, briquettes, pellets or other (preferably solid) fuels. Such a fireplace can, for example, be a fireplace from a group that includes a barbecue fireplace of any kind, a fire bowl, a campfire pit, a fire basket, a fire table and an outdoor fireplace.

There is also great flexibility in the manner, timing and location of adding the composition to the fuel. In particular, however, a method is preferred in which a composition as described above is used in a single-room fireplace. The composition can be used in all dosage forms described below in single-room combustion systems.

By means of a method as described above and/or a composition as described above, it is possible to reduce the amount of fine dust when a solid is burned by at least 10%, preferably at least 25%, more preferably at least 50% and in many cases are particularly preferred, even reduced by 75% or more. The percentages mentioned in this regard (like all other percentages mentioned in the context of this disclosure, unless otherwise defined) refer to percent by weight. In this case, the basic size is the amount of fine dust formed without the addition of the composition according to the invention.

• eine Ermittlung mindestens einer Eigenschaft einer Feuerstätte und
• einer Berechnung einer Menge der ersten die Feinstaubbildung reduzierende Komponente und/oder der zweiten, die Feinstaubbildung reduzierende Komponente. In die die Berechnung der Menge fließt vorzugsweise mindestens eine ermittelte Eigenschaft der Feuerstätte ein. Die berechnete Menge ist insbesondere eine Menge, der ersten die Feinstaubbildung reduzierende Komponente und/oder der zweiten, die Feinstaubbildung reduzierende Komponente, bei deren Zugabe zu einer Verbrennung in dieser Feuerstätte die Feinstaubbildung besonders effektiv reduziert ist.

The method preferably further comprises the steps of

• a determination of at least one property of a fireplace and
• a calculation of an amount of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust. At least one determined property of the fireplace is preferably taken into account when calculating the quantity. The calculated amount is in particular an amount of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust, when added to a combustion in this fireplace, the formation of fine dust is particularly effectively reduced.

It has been shown that certain properties are particularly suitable for calculating, on the basis of these properties, a particularly effective amount of the first component that reduces the formation of fine dust and/or the second component that reduces the formation of fine dust. Preferably, at least one determined property of the fireplace is selected from a group that includes a dimension of the fireplace, a dimension of a combustion chamber, a volume of the combustion chamber, a mass of the fireplace, a material of the fireplace, a material of the combustion chamber lining, a volume flow that can be fed to the combustion chamber Supply air, a volume flow of exhaust air that can be removed from the combustion chamber, a composition of a supply air flow, an air pressure, a pressure difference between supply and exhaust air flow, a height of the fireplace above a reference point (preferably a standardized reference point such as "Normalhöhenzero" (Germany, DHHN2016), "mètres au-dessus du ebene de la mer" (France, NGF-IGN69) or "metres above sea level" (United Kingdom, ODN)), a flow pattern within the combustion chamber, a temperature distribution within the combustion chamber, a type of fuel to be used , a mixing ratio of different fuel materials, a calorific value of one fuel used, a (combustion chamber) fill level, a temperature of combustion, a temperature distribution within the combustion chamber and a (combustion) material flow during combustion.

In particular, it is preferred that several properties from the group defined above are used to calculate the amount of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust. Preferably ≥ 2, preferably ≥ 3, preferably ≥ 4, more preferably ≥ 5, more preferably ≥ 8, most preferably ≥ 10 properties from the group defined above are used to calculate the amount of the first component that reduces fine dust formation and / or the second Component that reduces fine dust formation is used.

In a preferred variant, at least one property of the fireplace is determined using a sensor of the fireplace. Such a property can, for example, be a property that is selected from a group that includes a temperature, a temperature distribution, an exhaust gas composition, a supply air composition, a volume flow of supply air that can be supplied to the combustion chamber, a volume flow of exhaust air that can be removed from the combustion chamber, a mass transport, a flow pattern within the combustion chamber, a (combustion chamber) fill level, an air pressure and a pressure difference between the supply and exhaust air flow.

Other properties can of course also be determined using a sensor, but some properties do not change and/or cannot be determined sufficiently quickly with widely and/or inexpensively available sensors or cannot be determined sufficiently quickly with reasonable effort. In particular, properties that relate to the nature of the combustion chamber and/or the fireplace can often be provided more easily by a manufacturer. Accordingly, in a preferred variant it is provided that at least one property of the fireplace is determined by reading it from a database. Such a property can be, for example, a property selected from a group that includes a dimension of the fireplace, a dimension of a combustion chamber, a volume of the combustion chamber, a mass of the fireplace, a material of the fireplace, a material of the combustion chamber lining , a composition of a supply air flow, an air pressure, a height of the fireplace above a reference point (preferably a standardized reference point such as "Normalhöhennull" (Germany, DHHN2016), "mètres au-dessus du ebene de la mer" (France, NGF-IGN69) or "meters above sea level" (United Kingdom, ODN)), a type of fuel to be used, a mixing ratio of different fuel materials, a calorific value of a fuel used and a weather date.

At least some of this data could, for example, be recorded by specialist personnel/service providers, e.g. the chimney sweep and/or by the manufacturer of the (individual room) combustion system or facility, or several of them together, and made available in the database. There they are then available for later use and/or evaluation and can, for example, be incorporated into an action and/or dosage recommendation.

A database that includes a weather date is preferred, especially since predicted weather data is available at an early stage and future combustion processes can therefore also be predicted. In particular, parameters associated with weather data such as (air (and thus possibly also fuel)) humidity, air pressure (and thus possibly also gas flow volumes in the fireplace) or temperature (for example of the supply air) can be calculated or at least approximately derived from this data.

Preferably, the amount of total dust produced during combustion can also be reduced. Preferably, a reduction of at least 10%, preferably at least 25%, more preferably at least 50% and particularly preferably at least 75% is possible.

In addition to reducing the fine dust produced during combustion, a composition according to the invention can in many cases also improve the ash sintering behavior, in particular avoiding or at least reducing the sintering of the ash.

In many cases, the addition of a composition as described above also leads to a reduction in the CO content in the exhaust air. This can be attributed, among other things, to the improved ash sintering behavior and the associated better supply of fresh air and/or oxygen and the associated more complete combustion.

In a preferred variant of the method, the amount of the first component that reduces the formation of fine dust and/or the second component that reduces the formation of fine dust is calculated reducing component in a computer-implemented process step. The previously determined property of the fireplace is preferably fed to a particularly processor-based calculation device. The previously determined property is then preferably used as a basis for calculating the calculation using a machine learning model, in particular a trainable one. To generate the machine learning model, a large number of data sets that were generated at different fireplaces are preferably used. To generate the data sets, at least a quantity of the first component that reduces fine dust formation and/or the second component that reduces fine dust formation and a determined exhaust gas value were taken into account. Particularly preferably, each data set contains at least one date characteristic of a quantity of the first component reducing fine dust formation and/or a date characteristic of the quantity of the second component reducing fine dust formation and a date characteristic of an exhaust gas value.

The model preferably comprises a set of, in particular trainable, parameters which are set to values that were learned as a result of a training process. Furthermore, at least one output variable is determined (through this or through the processing), which is characteristic of a quantity of the first component reducing the formation of fine dust and/or the second component reducing the formation of fine dust, in particular for their effect in relation to the formation of fine dust during a combustion process . The calculation and/or development of the model is preferably based on parameters that are characteristic of a property of the fireplace. In particular, these are (raw) sensor data determined and/or generated by the at least one sensor device and/or data derived therefrom.

Preferably, a cost saving can be achieved by a composition as described above and/or the method described above, since exhaust gas aftertreatment or exhaust gas purification can be dispensed with or the systems and equipment necessary for this must be designed to be smaller or less complex.

Preferably, the composition is designed, suitable and/or intended to carry out a method as described above as well as all method steps described in connection with the method individually or in combination with one another or individual method steps using the composition described above.

Conversely, the method can be carried out individually or in combination with all the features described in the context of the composition.

The present invention is further directed to a fireplace in which at least some and preferably all of the method steps of the method according to the invention and preferably one of the preferred embodiments described can be carried out. Such a fireplace preferably has a device for supplying a composition as described above to a combustion chamber or a mixing chamber.

Such a sensor preferably has at least one sensor, by means of which a parameter can be determined which can be used to calculate a particularly efficient amount of the composition described above.

The present invention is further directed to a control device which is designed to control a system (for example a fireplace) so that it carries out the method or parts thereof as described above.

Such a control device preferably has a network connection by means of which it can access data from a database and/or data from a sensor of the fireplace to be controlled. The data stored in the database can contain data on the design of the fireplace and preferably also on the ambient conditions of the fireplace. This data could be provided by service companies or a manufacturer of the fireplace, for example a single-room combustion system. If necessary, people from this group can also carry out an evaluation and adjust the conditions and/or design of the fireplace based on this.

If, alternatively or in addition, sensor data is determined, for example by monitoring the firing conditions, it is possible to react in real time to the conditions in the combustion chamber and, for example, to react to them using an appropriate controller and/or installations and to readjust and, if necessary, optimize the firing conditions. Data collection is preferably carried out using real-time data collection, digital evaluation and subsequent provision of the data in a database and/or a network. Based on this data, a user and/or a control device can readjust the firing conditions (on site or via remote maintenance).

If weather data or at least one date characteristic of future weather at the location of the fireplace flow into the calculation of an amount of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust and / or another manipulated variable relevant to the combustion, this results Possibility of planning the firing conditions based on predicted weather data. This allows efficiency to be increased and early response to changing weather conditions.

Results of comparative studies are presented in the following tables.

Table 1 shows the results of fine dust measurements on a single pellet stove, manufacturer ANSELMO COLA, type URBAN, NWL 1.99-7.10kw. If a composition according to the invention (referred to as “additive” in the table) was added to the fuel, it was used in a mixing ratio of pellet (fuel) to composition of 4kg to 20g. Table 1 Measurement time fuel Description Fine dust [mg/m ³ ] 1 9:15-9:30 pellet Measurement at full load without additive 13.7 2 9:45-10:00 pellet Measurement at full load without additive 14.8 3 10:15-10:30 pellet Measurement at full load without additive 15.2 9 12:20-12:35 pellet Measurement at full load with additive 0.5% 6.4 10 12:40-12:55 pellet Measurement at full load with additive 0.5% 5.6

These results clearly show that even with the addition of 0.5% by weight of the additive (a powdered variant of the composition according to the invention), a significant reduction in the fine dust produced could be measured. The amount of fine dust could be reduced to less than 50% based on the mean value of comparative measurements 1 - 3.

Table 2 shows the results of fine dust measurements on a single fireplace for logs, manufacturer Austroflamm, type CLOU Xtra, NWL 8kw. If a composition according to the invention (referred to as "additive" in the table) was added to the firewood, it was added in a mixing ratio of approximately 1.2 - 1.4 kg of firewood to 10 g of additive. Table 2 Measurement time fuel Description Fine dust [mg/m ³ ] 4 10:40-10:55 logs 1.3 kg without additive 38.2 5 11:00-11:15 logs 1.4 kg without additive 34.2 6 11:20-11:35 logs 1.4 kg without additive 36.8 7 11:40-11:55 logs 1.3 kg with 10 g additive (pellet) 20.5 8th 12:00-12:15 1.4 kg with 10 g additive (pellet) 22.3

Unlike the measurements shown in Table 1, in the measurements shown in Table 2 the additive was used in a form pressed into a pellet. The results of these measurements also clearly show that a significant reduction in the fine dust produced could be measured with the addition of approximately 0.7 - 0.8% by weight of the additive (a variant of the composition according to the invention pressed into pellets). Although the amount of fine dust - unlike the measurements according to Table 1 - could not be reduced to less than 50% based on the mean value of comparative measurements 4 - 6, here too a reduction to well under 60% was achieved. The lower effectiveness of the additive in the tests according to Table 3 can be explained by the reduced surface area of the additive pressed into pellets.

• Fig. 1 eine Darstellung eines großformatigen Stücks einer erfindungsgemäßen Zusammensetzung;
• Fig. 2 eine Darstellung einer grob granulierten Form einer erfindungsgemäßen Zusammensetzung;
• Fig. 3 eine Darstellung einer sprühgetrockneten Form einer erfindungsgemäßen Zusammensetzung;
• Fig. 4 eine Darstellung einer pulverisierten Form einer erfindungsgemäßen Zusammensetzung;
• Fig. 5 eine Darstellung der granulierten Form einer erfindungsgemäßen Zusammensetzung aus Fig. 2 in einem Beutel brennbaren Materials;
• Fig. 6 eine Darstellung der pulverisierten Form einer erfindungsgemäßen Zusammensetzung aus Fig. 4 in einem Beutel brennbaren Materials;
• Fig. 7 eine Darstellung einer Suspension einer erfindungsgemäßen Zusammensetzung zusammen mit einer Sprühvorrichtung zu dessen Auftrag;
• Fig. 8 eine Grafik zum Vergleich der in einem Testsystem gemessenen Feinstaubmengen im Abgas bei einer Verbrennung eines Brennstoffs mit verschiedenen Zusätzen einer erfindungsgemäßen Zusammensetzung.

Further advantages and embodiments result from the attached figures:
Show in it:

• Fig. 1 a representation of a large-format piece of a composition according to the invention;
• Fig. 2 a representation of a coarsely granulated form of a composition according to the invention;
• Fig. 3 a representation of a spray-dried form of a composition according to the invention;
• Fig. 4 a representation of a powdered form of a composition according to the invention;
• Fig. 5 a representation of the granulated form of a composition according to the invention Fig. 2 in a bag of combustible material;
• Fig. 6 a representation of the powdered form of a composition according to the invention Fig. 4 in a bag of combustible material;
• Fig. 7 a representation of a suspension of a composition according to the invention together with a spray device for its application;
• Fig. 8 a graphic for comparing the amounts of fine dust in the exhaust gas measured in a test system when a fuel is burned with various additives of a composition according to the invention.

The Fig. 1 - 4 each show different dosage forms of a composition 1 according to the invention. The examples shown each contain kaolin and kaolin-containing clay as the first component. The ones in the Figures 1 - 4 The compositions 1 shown differ at least in the dosage form, the particle size and/or the water content. In order to be able to give an assessment of the size of individual particles, a scale 5 is shown in each case. In addition, the composition 1 is arranged on a grid, with the distance between two adjacent lines (horizontal and vertical) being 5 mm.

Dosage forms as in Fig. 1 shown are particularly advantageous for large combustion systems in which a reduction in the formation of fine dust is desired with only infrequent supply of the composition 1 over a long period of time. Due to the low surface-to-volume ratio of the comparatively large particles, when heat is applied in the combustion chamber, initially only the outer layers are activated. Internal areas are only exposed later when outer layers have broken down or fall off or flake off due to exposure to temperature. Only at this point are previously internal areas available to reduce fine dust formation.

In Fig. 2 A particularly preferred dosage form for single-room fireplaces and boiler systems is shown. The example of the composition 1 according to the invention shown is designed as granules. In this embodiment, due to the comparison to that in Fig. 1 illustrated embodiment larger surface-to-volume ratio With the same amount applied, a comparable surface area is quickly available on which the composition 1 can contribute to the desired reduction in the formation of fine dust. The residence time in a fireplace is comparatively long, so granules only have to be added again at reasonable time intervals in order to maintain the reduction in fine dust formation. This can be done, for example, together with the supply of fuel. In the Fig. 2 The embodiment shown is particularly preferred for pellet heating systems, since the composition 1 according to the invention can be introduced together with the fuel pellets. This configuration is also advantageous regardless of the supply of the fuel pellets, since the same feed device can be used as for the fuel pellets.

Another advantage of the dosage form as pellets is that it is easy to handle (for example, scooping is easy) and the low tendency to form dust.

3 and 4 each show a dosage form of composition 1 with a very small average particle size. A difference in the illustrations is difficult or impossible to see with the naked eye. Even if this cannot be seen based on the selected scale 5, both compositions 1 still differ in the average particle size, which is the case for the ground composition 1 Fig. 4 is slightly larger than the spray-dried composition 1, as shown in Fig. 3 is shown. Such dosage forms of composition 1 have the advantage that they are particularly reactive and quickly develop their effect. They can be distributed particularly homogeneously in a combustion chamber. This allows the formation of fine dust to be reduced particularly efficiently and evenly.

The 5 and 6 each show different dosage forms of a composition 1 according to the invention, which is arranged in a casing of a combustible material 3. This makes it possible to portion certain amounts of the composition 1 and feed it to the combustion process as one portion. Due to the loose form of the composition 1 as granules ( Fig. 5 ) or powder ( Fig. 6 ), dosing is very simple and yet it can be ensured that the composition 1 becomes active quickly and can be distributed in the combustion chamber. The distribution in the combustion chamber can be achieved, for example, by distributing the powder exposed after combustion of the casing 3 within the combustion chamber by inflow and/or exhaust gas flows. It would also be conceivable that the particles or granules evaporate, in particular fizzle out, due to what they contain and when exposed to temperature during combustion Water can be moved suddenly within the combustion chamber. This is particularly preferred when presented as granules. The water vapor that forms can also cause granular bodies to break open and thus break down into smaller fragments that have a more favorable surface-to-volume ratio and therefore greater reactivity. As can be seen from the scale 5, the size of the casing 3 can be selected in a comparatively large range according to the requirements. Volumes between 10 ml and 5 liters have proven to be advantageous. Preferably, the volume of the casing 3 is ≥ 20 ml, preferably ≥ 30 ml, preferably ≥ 50 ml and particularly preferably ≥ 100 ml. In addition or alternatively, the volume of the casing 3 is preferably ≤ 3 l, preferably ≤ 2 l, more preferably ≤ 1 l and particularly preferably ≤ 500 ml.

Fig. 7 shows a suspension of a composition 1 according to the invention together with a spray device 8 for its application. Such a suspension is particularly suitable for wetting the fuel with the composition 1 and thus preparing it for combustion. Supplying the composition 1 as a suspension is also suitable for the combustion of liquid fuels. The composition 1 is preferably not an aqueous suspension (although this is of course possible in some embodiments) but itself a suspension of a solid in a liquid fuel. In this context, it is conceivable, for example, that such a suspension could be used for exhaust gas aftertreatment. For this purpose, such a suspension could, for example, be sprayed into an exhaust gas stream and ignited.

Fig. 8 shows a graphic comparing the amounts of solids in the exhaust gas measured in a test system when burning a fuel with various additives. The curves shown in the graphic reflect the measured values as shown in Table 3: Table 3: Measurement results of fine dust in the exhaust gas when various additives were added. time [min] line 15 30 45 60 75 90 105 120 Individual measured values TPM [mg/m ³ ] O without additive 10 38 38 29 28 22 28 21 29 0.3% by mass kaolin FPK-KAF 20 29 27 25 23 16 17 16 15 21 0.3% by mass kaolin MMEF 30 26 22 24 26 27 23 27 21 25 0.3% by mass kaolinite 40 21 20 22 13 17 21 15 16 18 0.3% by mass kaolin, activated at 600°C 60 15 16 17 16 17 16 17 16 16 0.3% by mass kaolinite, activated at 400°C 50 16 17 17 17 18 18 16 16 17

The graphic shows a general trend that after a longer burning time, the amount of fine dust produced per time interval decreases. For this illustration, the fine dust levels in the exhaust gas were measured after 15 minutes. The individual measured values given represent the fine dust pollution as TPM (total particulate matter) in mg per m ³ .

The graphic shows that without additive (line 10) and with the addition of 0.3 mass percent (Ma-%) kaolin (line 30) as a second component, the fine dust pollution is significantly higher than with the other additives shown, even after a longer burning time.

Furthermore, the diagram shows that only when adding compositions that contain 0.3 mass percent (Ma-%) of thermally activated kaolin (kaolin line 50 activated at 400 ° C and kaolin line 60 activated at 600 ° C) after just 15 minutes of burning time TPM is measured, which roughly corresponds to that after 120 minutes. These compositions 1 therefore show very good fine dust reduction even at lower combustion temperatures. Surprisingly, the measurement results show that metakaolin, which was obtained by activation of kaolin at 800 ° C (line 20), causes a significantly smaller reduction in the formation of fine dust at the beginning of a combustion process. Only after a time of just over an hour could a similar reduction in fine dust be measured when using metakaolin activated at 800 ° C as with the compositions with kaolin activated at 400 ° C (line 50) and kaolin activated at 600 ° C (line 60). A possible explanation for this phenomenon could be that crystal water still contained in the compositions with the kaolin activated at 400 ° C (line 50) and kaolin activated at 600 ° C (line 60) is expelled during combustion and escaping water vapor causes the composition to decompose 1 favors, which creates a larger surface-to-volume ratio and thus increases activity.

All other compositions shown (lines 20, 30 and 40) also show a reduction in particulate matter just 15 minutes after the start of combustion, but this is lower than in those compositions (lines 50 and 60) that contain the same amount of one at 400 ° C or 600 °C thermally activated kaolin.

Several properties can contribute to this positive effect: on the one hand, thermal activation drives crystal water out of the kaolin, so that the proportion of reactive species per unit of weight increases. On the other hand, thermal activation can prevent the crystal water contained in combustion from having to be expelled first, which can lead to a reduction in the combustion temperature and thus poorer combustion.

The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they, individually or in combination, are new compared to the prior art.

Claims (15)

Composition for reducing the formation of particulate matter during the combustion of solid matter, comprising at least a first component that reduces the formation of particulate matter, which is selected from a group that includes Al ₂ O ₃ , Al(OH) ₃ , bauxite, talc, kaolin, kaolinite and kaolin-containing clays ,
characterized in that
the composition comprises a second component that reduces particulate matter formation, which is selected from a group that includes kaolin, metakaolin, thermally activated three-layer silicates, fly ash and microsilica and / or combinations of these substances. Composition according to claim 1,
characterized in that
the second component, which reduces fine dust formation, is suitable for binding fine dust-forming Na and/or K salts at combustion temperatures ≤ 650 ° C and preferably comprises one or more substances from a group that includes kaolin, halloysite, dickite and nacrite, wherein at least one of these substances is thermally activated. Composition according to one of the preceding claims,
characterized in that
the second component that reduces the formation of fine dust is present as a particulate solid, which preferably has a particle size (Sedigraph) d ₉₅ ≤ 100 µm, preferably ≤ 50 µm, more preferably ≤ 20 µm, particularly preferably ≤ 10 µm. Composition according to one of the preceding claims,
characterized in that
a ratio of the first component that reduces fine dust formation to the second component that reduces fine dust formation in the range of 1:99 - 99:1, preferably 50:50 - 98:2, more preferably 60:40 - 95:5 and particularly preferably 75:25 - 90:10. Composition according to one of the preceding claims,
characterized in that
it comprises a combustible substance, which is preferably selected from a group that includes wood, straw, husks, grass, bran, yeast cells, grain, hemp, fruit and / or vegetable seeds, lignite, lignite coke, lignite powder, dry stillage (DDGS), hard coal , hard coal coke, hard coal powder, charcoal, charcoal powder, plant fibers, cellulose fibers, paper and petroleum coke. Composition according to one of the preceding claims,
characterized in that
the composition comprises a binder and is preferably present as a pellet, briquette, granulate, oven lighter, grill lighter and/or pressed log, wherein the binder is preferably selected from a group that includes hydrocarbon-based materials, oil, wax, paste and flour. Composition according to one of the preceding claims,
characterized in that
it comprises a fuel which can be burned with the formation of fine dust, preferably the proportion of the second component which reduces the formation of fine dust, based on the fuel, in the range of 0.05 - 5% by weight, preferably 0.1 - 4% by weight, more preferably 0.15 - 3% by weight and particularly preferably 0.2 - 2.5% by weight. Method for burning a solid fuel in a fireplace,
characterized in that
a composition to reduce the formation of fine dust is added to the fuel, this composition - at least one first component that reduces fine dust formation, which is selected from a group that includes Al ₂ O ₃ , Al (OH) ₃ , bauxite, talc, kaolin, kaolinite and kaolin-containing clays, and - a second component that reduces fine dust formation, which is selected from a group that includes kaolin, metakaolin, thermally activated three-layer silicates, fly ash and microsilica and / or combinations of these substances. Method for burning a solid fuel in a fireplace according to claim 8,
characterized in that
the composition is a composition according to any one of claims 1-7 or comprises such a composition. Method for burning a solid fuel in a fireplace according to one of claims 8 - 9,
marked by a determination of at least one property of a fireplace and a calculation of an amount of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust, the at least one determined property of the fireplace being included in the calculation of the amount and when the calculated amount is added to a combustion in this fireplace, the formation of fine dust in particular is effectively reduced. Method for burning a solid fuel in a fireplace according to claim 10,
characterized by that
at least one determined property of the fireplace is selected from a group that includes a dimension of the fireplace, a dimension of a combustion chamber, a volume of the combustion chamber, a mass of the fireplace, a material of the fireplace, a material of the combustion chamber lining, a volume flow of supply air that can be supplied to the combustion chamber , a volume flow of exhaust air that can be removed from the combustion chamber, a composition of a supply air flow, an air pressure, a pressure difference between supply and exhaust air flow, a height of the fireplace above a reference point (preferably a standardized reference point such as "Normalhöhennull" (Germany, DHHN2016), " meters au-dessus du ebene de la mer" (France, NGF-IGN69) or "metres above sea level" (United Kingdom, ODN)), a flow pattern within the combustion chamber, a temperature distribution within the combustion chamber, a type of fuel to be used, a mixing ratio of different fuel materials, a calorific value of a fuel used, a temperature of the combustion, a temperature distribution within the combustion chamber and a (combustion) material flow during combustion. Method for burning a solid fuel in a fireplace according to one of claims 10 or 11,
marked by
at least one property of the fireplace is determined by means of a sensor of the fireplace and/or at least one property is read from a database, which preferably includes a weather date. Method for burning a solid fuel in a fireplace according to one of claims 8 - 12,
characterized in that
the composition is added to the fuel in an amount so that the proportion of the second component that reduces fine dust formation, based on the fuel, is in the range of 0.05 - 5% by weight, preferably 0.1 - 4% by weight, more preferably 0.15 - 3% by weight and particularly preferably 0.2 - 2.5% by weight. Method for burning a solid fuel in a fireplace according to one of claims 8 - 13,
characterized in that
the fireplace is a single-room fireplace. Method for burning a solid fuel in a fireplace according to one of claims 8 - 13,
characterized in that
the calculation of the amount of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust is carried out in a computer-implemented method step, the previously determined property of the fireplace being fed to a particular processor-based calculation device and using a, in particular, trainable one , machine learning model is used, wherein a large number of data sets are used to generate the machine learning model, which are generated at different fireplaces taking into account at least a quantity of the first component that reduces the formation of fine dust and / or the second component that reduces the formation of fine dust and an exhaust gas value became.

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