Solid biomass fuel anti-coking additive

Abstract

1. A solid biomass fuel derived from one or more biomass sources, wherein the one or more biomass sources include straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof; and the solid biomass fuel further includes one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ash, or a combination thereof.

Description

[Technical Field]

[0001] The present invention relates to the use of an additive to prevent or reduce coking during combustion of a solid biomass fuel, and to a solid biomass fuel comprising said additive. Further, the present invention relates to a combustion method comprising combusting said solid biomass fuel comprising said additive to produce energy. The present invention also relates to a method for preparing a solid biomass fuel comprising said additive. [Background technology]

[0002] Coal-fired power plants are used in power plants and industrial processes around the world. Coal and other fossil fuels are non-renewable energy sources. In recent decades, there has been a push to reduce coal consumption in coal-fired power plants and instead use renewable sources of energy.

[0003] Biomass-derived fuels are an example of a renewable energy source and can be used to replace or at least partially replace coal. Biomass-derived fuels can be burned in the presence of oxygen in a power plant's combustion process to generate energy. Biomass-derived fuels can be burned in conventional power plants originally designed for coal combustion or in power plants built specifically for biomass combustion. Certain forms of biomass can be mixed with coal and burned in the same combustion process within a power plant. This process is known as biomass-coal co-firing. To be suitable for co-firing with coal, biomass-derived fuels typically must possess certain characteristics, such as a certain level of quality and property homogeneity. For example, biomass fuels composed of particles of uniform size, density, moisture content, etc., are particularly desirable in co-firing processes. It is also desirable for biomass fuels to contain low levels of ash. The ash levels of biomass-derived fuels are typically higher than those found in coal.

[0004] Various processes for producing solid biomass fuels from biomass sources are known. International Publication Nos. WO 2016 / 056608, WO 2017 / 175733, and WO 2019 / 069849 disclose methods for forming solid biomass fuels from various wood-like biomass sources. However, those skilled in the art are aware of various problems associated with the solid biomass fuels and processes for their production discussed in these documents. For example, the wood-like biomass sources described in these documents typically only occur naturally and are not easily cultivated or harvested on a commercial scale. Furthermore, when the wood-like biomass sources described in these documents are subjected to conventional pulverization techniques, particles with low uniformity are formed, meaning that the solid biomass fuel produced from the material is not sufficiently uniform. In light of these problems, there is a need in the art for a process for producing high-performance solid biomass fuels from alternative sources of biomass (i.e., non-woody biomass sources). Specific solutions to these problems are disclosed in WO 2020 / 229824, WO 2021 / 014151, WO 2021 / 024001 and WO 2021 / 156628, which attempt to ameliorate the above-mentioned problems. Despite the solutions proposed in the above documents, there remains a need in the art for high performance solid biomass fuels.

[0005] A particular problem associated with solid biomass fuels is the frequent deposition of ash during fuel combustion in the combustion chamber and in conduits communicating with the combustion chamber, such as those used for exhaust gas evacuation. Ash is the non-combustible inorganic mineral component of solid biomass fuel that remains after complete combustion of the fuel. Ash typically contains large amounts of non-combustible alkali metal salts, particularly potassium. Alkali metal salts, such as potassium chloride, sulfates, and hydroxides, are often found in ash combustion by-products. These mineral salts typically have relatively low melting points. For example, the melting point of potassium chloride is only 770°C. Temperatures encountered in biomass combustion often exceed this temperature, causing the inorganic mineral salts to melt. Molten salts can become sticky upon cooling and adhere to various interior surfaces of the combustion chamber and the conduits communicating with it, causing problems during combustion. This process is known as slagging. Salts can also form fine aerosol particles that are emitted as undesirable pollutants in the exhaust gas. Gaseous alkali metal compounds, such as potassium chloride, hydroxides, and sulfates, can also condense and undergo undesirable reactions on metal surfaces in conduits fluidly communicating with the combustion chamber. These processes can ultimately lead to fouling of the combustion equipment. Ash-related combustion problems are typically more problematic with solid biomass fuels than with conventional coal, because biomass typically contains higher levels of inorganic salts and metal ions than coal.

[0006] A distinct problem associated with the combustion of solid biomass fuels is a phenomenon known as coking, which occurs during fuel combustion. Coking is the formation of organic combustible deposits within the combustion chamber and in conduits or chambers in fluid communication with it during the combustion of solid biomass fuels. Coking is the result of incomplete combustion of the fuel. Deposits that can form during coking include soot, which contains amorphous carbon particles and heavy hydrocarbons, such as polyaromatic hydrocarbons (PAHs). Soot often forms as solid deposits in the combustion chamber and flue gas stack. Therefore, soot can clog combustion equipment, leading to operational problems. Soot particles can also be emitted into the exhaust gas, which is highly undesirable due to its greenhouse gas effects. Soot can also be carcinogenic. Therefore, minimizing soot formation is desirable. Other deposits that can form during coking include tar, a viscous liquid containing carbon and heavy hydrocarbons, such as asphaltenes. Tar also deposits during coking in a manner similar to the soot described above, causing similar problems. Tar, soot, and other coke deposits can also be burned at temperatures found within the combustion chamber and associated conduits in a process known as secondary combustion. Such processes form undesirable polluting gaseous combustion products in the exhaust gas. The coking properties of solid biomass fuels are distinct from and unrelated to the tendency of biomass fuels to develop ash-related problems. Ash-related problems and coking are distinct phenomena that arise from different factors and proceed via different mechanisms.

[0007] The factors that determine whether a fuel will develop significant coking during combustion are diverse and complex. Coking can be caused by incomplete combustion of solid biomass fuels. Factors such as combustion temperature and the amount of oxygen successfully mixed with the fuel during combustion affect the degree of coking. Typically, lower combustion temperatures and lower air-to-fuel ratios lead to more coking and promote incomplete combustion. The composition of the fuel in question also strongly influences the extent of coking and soot formation. Coking and soot and tar formation proceed through complex chemical mechanisms that are not fully understood and can vary significantly between fuels with different chemical compositions. For example, in fossil fuels, naphthalene tends to form more soot than benzene, which forms more soot than aliphatic fuels. The coking properties of coal and solid biomass fuels differ due to differences in the chemical nature of the fuels. For example, in fossil fuels such as coal, the majority of the fuel is hydrocarbon (e.g., aromatics, alkanes, alkenes, etc.). In biomass-derived fuels, heteroatom-containing compounds, such as oxygenates, are more prevalent. This is because compounds containing such heteroatoms are abundant in nature. For example, the major components of certain forms of biomass are the polymers cellulose and lignin. Cellulose is a polysaccharide and therefore contains a large number of oxygen atoms. Lignin also contains a large number of oxygen atoms. Therefore, fuels produced from biomass typically contain larger amounts of oxygen-containing compounds than fossil fuels. This chemical difference causes differences in the coking properties of the fuels. The coking properties of different solid biomass fuels, such as those derived from different types of biomass sources, can vary significantly due to differences in the chemistry of different types of biomass (e.g., differences in the amount of lignin and cellulose present in different types of biomass).

[0008] There remains a need in the art for methods to reduce coking during combustion of solid biomass fuels, and in particular for additives that can effectively reduce coking in solid biomass fuels derived from a variety of different biomass sources. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2016 / 056608 Brochure [Patent Document 2] International Publication No. 2017 / 175733 Brochure [Patent Document 3] International Publication No. 2019 / 069849 Brochure [Patent Document 4] International Publication No. 2020 / 229824 Brochure [Patent Document 5] International Publication No. 2021 / 014151 Brochure [Patent Document 6] International Publication No. 2021 / 024001 Brochure [Patent Document 7] International Publication No. 2021 / 156628 Brochure Summary of the Invention

[0010] The present invention is based on the surprising discovery that the incorporation of certain additives into solid biomass fuel can improve the coking properties of the solid fuel. The inventors have surprisingly found that an additive comprising one or more aluminosilicate clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof, when incorporated into solid biomass fuel, can improve the coking properties of the solid biomass fuel. It was previously unknown that such additives can improve the coking properties of solid biomass fuel when incorporated into the fuel, and this was a surprising discovery by the inventors. It has surprisingly been found that the additives described above, when combusted, reduce the tendency of the solid biomass fuel to deposit coke (i.e., deposits of solid and / or liquid combustible organic matter) on the surfaces of the combustion chamber and conduits communicating therewith. Furthermore, it has been advantageously found that the additives inhibit the secondary combustion of coke deposits once they have formed, which means that emissions of harmful, polluting gaseous secondary combustion products of coke are reduced.

[0011] Surprisingly, it has been found that the above-described additives can improve the coking properties of solid biomass fuels derived from a variety of different types of biomass, which is surprising given the chemical differences between solid fuels derived from different types of biomass.

[0012] However, the use of the above-described additives as anti-coking additives has been found to be particularly effective with certain types of non-woody biomass (as opposed to woody-type biomass sources such as those taught in WO 2016 / 056608, WO 2017 / 175733, and WO 2019 / 069849). Without being limited by theory, it is believed that this is because certain non-woody types of biomass can be more effectively crushed and pulverized by conventional techniques known in the art, resulting in pulverized biomass particles having a smaller particle size distribution (e.g., as discussed in detail in WO 2020 / 229824, WO 2021 / 014151, WO 2021 / 024001, and WO 2021 / 156628). It has been discovered that the finer the particle size distribution of the pulverized biomass, the more uniformly the anti-coking additives described above can be incorporated into the solid biomass fuel, which has been surprisingly discovered by the inventors to result in a greater improvement in the coking properties of the solid biomass fuel compared to biomass fuels that form a larger particle size distribution when pulverized, such as solid fuels derived from wood-like biomass sources.

[0013] According to a first aspect of the present invention, there is provided a solid biomass fuel derived from one or more biomass sources, wherein the one or more biomass sources comprise straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calothyrsus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof, and the solid biomass fuel further comprises one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ash, or a combination thereof.

[0014] The solid biomass fuel has improved coking properties when compared to a similar solid biomass fuel that is identical to the fuel of the present invention except that it does not contain one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ash, or combinations thereof.

[0015] Preferably, the one or more biomass sources comprise straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof in an amount of at least 50% by weight, preferably at least 75% by weight, more preferably at least 90% by weight.

[0016] More preferably, the one or more biomass sources consist essentially of straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof.

[0017] In some examples, the one or more biomass sources comprise or consist essentially of straw, wherein the straw is selected from rice straw, tobacco straw, sesame straw, chili pepper straw, eggplant straw, cotton straw, sorghum straw, sunflower stalk, wheat stalk, corn stalk, rapeseed stalk, tapioca straw, bean stalk, or any combination thereof.

[0018] In some examples, the one or more biomass sources comprise or consist essentially of palm-derived material, where the palm-derived material is selected from palm trunks, palm fronds, palm empty fruit bunches (EFBs), palm kernel shells (PKSs), palm oil residue, palm husks, palm shells, palm fiber, or any combination thereof.

[0019] In some examples, the one or more biomass sources comprise or consist essentially of nut shells, wherein the nut shells are selected from cashew nut shells, peanut shells, chestnut shells, pistachio shells, sunflower seed shells, walnut shells, pine cone shells, or any combination thereof.

[0020] In some examples, the one or more biomass sources comprise or consist essentially of hemp, where the hemp is selected from ramie, jute, green hemp, flax, robin, hibiscus, or any combination thereof.

[0021] In some examples, the one or more biomass sources comprise or consist essentially of bamboo, wherein the bamboo is selected from Moso bamboo, Psammophila bamboo, Yatake bamboo, or any combination thereof.

[0022] In some examples, the one or more biomass sources comprise or consist essentially of fruit shells, wherein the fruit shells are selected from coconut shells, lychee shells, cinnamon (longan) shells, snake skin fruit shells, mangosteen shells, durian shells, or any combination thereof.

[0023] In some examples, the one or more biomass sources comprise or consist essentially of crop residues, wherein the crop residues are selected from wheat husks, bagasse, okara, peanut residues, cassava residues, sweet potato residues, coffee bean residues, or any combination thereof.

[0024] In some examples, the one or more biomass sources include or consist essentially of grasses, and the grasses are selected from plants of the Penisetum genus, such as Penisetum sinese Roxb.

[0025] Typically, the material derived from one or more biomass sources is present in the solid biomass fuel in an amount of at least 80% by weight. Preferably, the material derived from one or more biomass sources is present in the solid biomass fuel in an amount of at least 90% by weight. More preferably, the material derived from one or more biomass sources is present in the solid biomass fuel in an amount of at least 95% by weight.

[0026] Typically, when the solid biomass fuel comprises one or more aluminosilicate-containing clays, the one or more aluminosilicate-containing clays comprise kaolin.

[0027] Typically, when the solid biomass fuel comprises one or more aluminosilicates, the one or more aluminosilicates comprise one or more aluminosilicate minerals, one or more zeolites, one or more feldspars, one or more aluminosilicate glasses, or any combination thereof.

[0028] The one or more aluminosilicate minerals may include any suitable mineral, such as andalusite, kyanite, sillimanite, or combinations thereof.

[0029] The one or more aluminosilicate glasses may include any suitable aluminosilicate glass, such as an alkali metal or alkaline earth metal aluminosilicate glass.

[0030] Typically, the total amount of one or more aluminosilicate clays, one or more aluminosilicates, one or more pulverized fuel ashes, or combinations thereof present in the solid biomass fuel is 0.1% to 10% by weight of the solid biomass fuel, for example, 0.1% to 5% by weight of the solid biomass fuel. Preferably, the total amount of one or more aluminosilicate clays, one or more aluminosilicates, one or more pulverized fuel ashes, or combinations thereof present in the solid biomass fuel is 0.1% to 1% by weight of the solid biomass fuel. More preferably, the total amount of one or more aluminosilicate clays, one or more aluminosilicates, one or more pulverized fuel ashes, or combinations thereof present in the solid biomass fuel is 0.1% to 0.8% by weight of the solid biomass fuel, and most preferably, 0.5% to 0.8% by weight of the solid biomass fuel.

[0031] Preferably, the solid biomass fuel comprises one or more aluminosilicate clays in a total amount of 0.3% to 0.5% by weight based on the solid biomass fuel, one or more aluminosilicates in a total amount of 0.1% to 0.2% by weight based on the solid biomass fuel, and one or more finely divided fuel ashes in an amount of 0.1% to 0.2% by weight based on the solid biomass fuel. Preferably, the one or more aluminosilicate clays comprise kaolin.

[0032] Preferably, the one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof are uniformly dispersed in the solid biomass fuel along with the biomass-derived material.

[0033] Typically, the bulk density of the solid biomass fuel, determined in accordance with DIN EN 15103, is between 0.50 kg / l and 0.8 kg / l, preferably between 0.60 kg / l and 0.75 kg / l, more preferably between 0.60 and 0.70 kg / l.

[0034] Typically, the mechanical durability of solid biomass fuels, determined in accordance with DIN EN 15210-1, is greater than or equal to 97%.

[0035] Typically, (i) the biomass solid fuel has a total dry sulfur content of 0.5 wt% or less, preferably 0.45 wt% or less, and most preferably 0.40 wt% or less, where the total dry sulfur content is determined in accordance with DIN EN 15289.

[0036] Typically, (ii) the total dry hydrogen content of the biomass solid fuel is 3 wt% or more, preferably 5 wt% to 10 wt%, more preferably 5 wt% to 7 wt%, where the total dry hydrogen content is determined in accordance with DIN EN 15104.

[0037] Typically, (iii) the total dry oxygen content of the biomass solid fuel is 20 wt% or more, preferably 25 wt% to 42 wt%, more preferably 28 wt% to 40 wt%, where the total dry oxygen content is determined in accordance with DIN EN 15296.

[0038] Typically, (iv) the total dry carbon content of the biomass solid fuel is 40 wt% or more, preferably 45 wt% to 65 wt%, more preferably 50 wt% to 60 wt%, the total dry carbon content being determined in accordance with DIN EN 15104.

[0039] Typically, (v) the biomass solid fuel has a total dry nitrogen content of less than 5.0 wt%, preferably less than 3.0 wt%, more preferably less than 2.5 wt%, where the total dry nitrogen content is determined in accordance with DIN EN 15104.

[0040] The solid biomass fuel may typically be as defined in any one or more of options (i) to (v) above. Preferably, the solid biomass fuel is as defined in any three or more of options (i) to (v) above. More preferably, the solid biomass fuel is as defined in all of options (i) to (v) above.

[0041] Typically, (vi) the chemical oxygen demand (COD) of the solid biomass fuel when immersed in water is 5000 ppm or less, preferably 4000 ppm or less, and most preferably 3200 ppm or less, where the COD is determined in accordance with GB / 11914-89.

[0042] Typically, (vii) the solid biomass fuel has a fixed carbon content of 20 wt% or more, preferably 25 wt% to 45 wt%, the fixed carbon content being determined in accordance with DIN EN 51734.

[0043] Typically, (viii) the ash content of the solid biomass fuel is less than 20 wt%, preferably less than 18 wt%, the ash content being determined according to EN 14775 at 550°C.

[0044] Typically, (ix) the volatile matter content of the solid biomass fuel is between 35 wt% and 80 wt%, more preferably between 40 wt% and 75 wt%, the volatile matter content being determined in accordance with DIN EN 15148.

[0045] Typically, (x) the solid biomass fuel has an internal moisture content of less than 8 wt%, preferably less than 6 wt%, more preferably less than 5 wt%, where the internal moisture content is determined in accordance with DIN EN 14774.

[0046] The solid biomass fuel may typically be as defined in any one or more of options (vi) to (x) above. Preferably, the solid biomass fuel is as defined in any three or more of options (vi) to (x) above. More preferably, the solid biomass fuel is as defined in all of options (vi) to (x) above.

[0047] Typically, biomass solid fuels have a calorific value of 4300 kcal / kg to 6750 kcal / kg, the calorific value being determined in accordance with DIN EN 14918.

[0048] Typically, the biomass solid fuel has a base moisture content of less than 10 wt%, preferably less than 8 wt%, and most preferably less than 6 wt%, where the base moisture content is determined in accordance with GB / T211-2017.

[0049] Typically, solid biomass fuel has a pH of 4-10.

[0050] Typically, the solid biomass fuel is water resistant for up to 20 days, preferably up to 30 days, and more preferably up to 40 days.

[0051] Typically, solid biomass fuels have PM1.0 emissions of less than 175 mg / kg, preferably less than 150 mg / kg, when burned.

[0052] Typically, the coke index of the solid biomass fuel when burned is 1.5 or less, preferably 0.3 to 1.5, and the coke index is determined in accordance with GB / T8727-2008.

[0053] Typically, the solid biomass fuel is obtained or obtainable by a method according to the fourth aspect of the invention, as described in more detail below.

[0054] According to a second aspect of the present invention, there is provided a method for combusting a solid biomass fuel according to the first aspect of the present invention.

[0055] Typically, solid biomass fuel is co-combusted and burned together with a fossil fuel such as coal.

[0056] Typically, the process has PM1.0 emissions of less than 175 mg / kg, preferably less than 150 mg / kg.

[0057] According to a third aspect of the present invention, there is provided the use of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof, as an anti-coking additive in solid biomass fuel.

[0058] Preferably, the use comprises using the anti-coking additive to reduce or prevent the formation of solid and / or liquid combustible organic deposits during the combustion of solid biomass fuel, more preferably the solid and / or liquid combustible organic deposits build up on surfaces of the combustion chamber used in the combustion of the solid biomass fuel and / or in conduits in fluid communication therewith.

[0059] Preferably, the use involves the use of an anti-coking additive to prevent or reduce the secondary combustion of deposits of solid and / or liquid combustible organic matter.

[0060] Typically, the solid and / or liquid combustible organic matter includes soot, tar, or a combination thereof.

[0061] Typically, the solid biomass fuel is derived from one or more biomass sources, including straw, palm-derived materials, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof.

[0062] Preferably, the solid biomass fuel, the biomass source, the one or more aluminosilicate-containing clays, the one or more aluminosilicates and / or the one or more finely divided fuel ashes are as described above in the context of the first aspect of the invention.

[0063] According to a fourth aspect of the present invention, there is provided a method for producing a solid biomass fuel according to the first aspect of the present invention, comprising the steps of: (i) providing a biomass composition comprising biomass particles having an average particle size (D50) of 1,000 μm to 75,000 μm; (ii) pulverizing the biomass composition to provide a pulverized biomass powder having an average particle size (D50) of 500 μm to 10,000 μm; (iii) drying the finely divided biomass powder to provide a dried finely divided biomass powder; (iv) shaping the dried, finely divided biomass powder to provide a shaped biomass product, wherein the dried, finely divided biomass powder is shaped with one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ash, or a combination thereof to provide the shaped biomass product; (v) heating the formed biomass product to a temperature of 110°C to 500°C for a period of 0.2 to 6 hours to provide a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel; A method is provided which includes:

[0064] Typically, the biomass composition comprises one or more biomass sources including straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof. Preferably, the one or more biomass sources are as described above in the context of the first aspect of the invention.

[0065] Preferably, the solid biomass fuel, the biomass source, the one or more aluminosilicate-containing clays, the one or more aluminosilicates and / or the one or more finely divided fuel ashes are as described above in the context of the first aspect of the invention.

[0066] Typically, adapting the compacting step to control the density of the compacted biomass product comprises controlling the compression ratio of a mold used in the compacting step. Typically, step (iv) of compacting the dried, finely ground biomass powder to provide the compacted biomass product comprises compacting the dried, finely ground biomass powder using a compaction mold having a compression ratio of less than 6, for example less than 5. Preferably, step (iv) of compacting the dried, finely ground biomass powder to provide the compacted biomass product comprises compacting the finely ground biomass powder using a compaction mold having a compression ratio of 3.5 or less, more preferably 3 or less, and most preferably 1 to 3.

[0067] Typically, the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more finely pulverized fuel ash, or a combination thereof are compacted together with the dried, finely pulverized biomass powder in a mass ratio to provide a solid biomass fuel comprising a total of 0.1% to 10% by weight of the solid biomass fuel, preferably 0.1% to 5% by weight of the solid biomass fuel, more preferably 0.1% to 1% by weight of the solid biomass fuel, even more preferably 0.1% to 0.8% by weight of the solid biomass fuel, and most preferably 0.5% to 0.8% by weight of the solid biomass fuel.

[0068] In one highly preferred example, dried, finely divided biomass powder is compacted together with one or more aluminosilicate clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof, in a mass ratio to provide a solid biomass fuel comprising one or more aluminosilicate clays in an amount of 0.3% to 0.5% by weight based on the solid biomass fuel, one or more aluminosilicates in a total amount of 0.1% to 0.2% by weight based on the solid biomass fuel, and one or more finely divided fuel ashes in an amount of 0.1% to 0.2% by weight based on the solid biomass fuel. [Brief explanation of the drawings]

[0069] [Figure 1] 1 is a photograph of an apparatus known in the art that can be used to chip one or more biomass sources. [Figure 2] 1 is a diagram of a typical compression mold that may be used in accordance with the present invention, showing the compression ratios used in the molding step. [Figure 3] FIG. 1 shows the coke properties of various biomass fuels of the present invention as determined by GB / T212-2008. [Figure 4] FIG. 1 shows the coking properties of various comparative biomass fuels without anti-coking additives as determined by GB / T212-2008. DETAILED DESCRIPTION OF THE INVENTION

[0070] Biomass Sources Any plant-derived biomass source can be used in the present invention. Preferably, the one or more biomass sources from which the solid biomass fuel is derived are as described above.

[0071] Preferably, the one or more biomass sources include non-woody biomass sources. As noted above, it has surprisingly been found that the additives for use in the present invention more effectively impart anti-coking properties to solid biomass fuels derived from non-woody biomass sources. This is believed to be because the additive can be more uniformly incorporated into the solid biomass fuel than into fuels derived from woody biomass sources. Surprisingly, it has been found that this results in a greater improvement in the coking properties of the solid biomass fuel. In other words, the anti-coking additives for use in the present invention may still be effective when used with woody biomass sources, but the improvement in coking properties when the additive is incorporated into the fuel is less than when the fuel is derived from a non-woody biomass source.

[0072] As used herein, the terms "wood," "woody biomass," or "wood-like biomass" refer to the tough, fibrous material, primarily xylem, that typically comprises the majority of the stems, branches, and roots beneath the bark of trees and shrubs. Wood is found to a limited extent in herbaceous plants. This definition of the term "wood" is consistent with the definition commonly understood in the art.

[0073] Preferably, the one or more biomass sources from which the solid biomass fuel is derived contain less than 50% by weight woody biomass, more preferably less than 20% by weight, and most preferably less than 10% by weight.

[0074] Preferably, as described above, the one or more biomass sources include straw, palm-derived materials, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof. Unlike wood-like biomass sources, these biomass sources can be grown and harvested on a commercial scale, providing greater control over the quality and specific characteristics of the biomass source compared to wood-like materials. The use of such biomass sources also avoids the environmental damage associated with the use of trees, such as unavoidable deforestation. The use of these biomass sources is also easier to grind than wood-like materials, thereby reducing the cost of the grinding process. Furthermore, the use of these materials provides a more uniform particle size mixture upon grinding, resulting in a final solid biomass fuel product with improved uniformity.

[0075] More preferably, the one or more biomass sources include rice straw, tobacco straw, chili straw, eggplant straw, cassava straw, yellow bean straw, chickpea straw, soybean straw, palm leaves, cashew nut shells, Chinese chestnut shells, pistachio shells, sunflower seed shells, walnut shells, pine nut shells, hemp, moso bamboo, rachis bamboo, Yamtake mushroom, lychee shells, cinnamon (longan) shells, snakeskin fruit shells, mangosteen shells, durian shells, soybean residue, peanut residue, cassava residue, sweet potato residue, coffee bean residue, or a combination thereof. Even more preferably, the one or more biomass sources comprise these materials in an amount of 80% to 100% by weight. Most preferably, the one or more biomass sources consist essentially of the above materials. The use of these materials is particularly preferred because they have surprisingly been found to all provide solid biomass fuels with unexpectedly high mechanical durability, greater than 97%. This can even be achieved while using lower compression ratios of less than 3.6 when forming the solid biomass fuel into pellets. Typically, higher compression ratios are required when using other biomass sources to obtain solid fuels with high mechanical durability (as discussed in more detail below). When possible, using lower compression ratios is preferred because they result in higher biomass fuel yields when forming the fuel into pellets. High mechanical durability of 97% or greater for solid biomass fuels is advantageous because it has been found that highly durable fuels can be stored outdoors for as long as two months without being damaged by rain or other adverse weather conditions. High mechanical durability is also desirable because highly durable fuels are less likely to break down and generate dust during processing, transportation, or storage.

[0076] The biomass sources used in accordance with the present invention may be generated as agricultural waste as a by-product of agricultural operations. Alternatively, these biomass sources may be specifically grown for the purpose of being a feedstock for the preparation of biomass solid fuel. Each of the one or more biomass sources described above can be obtained or harvested by conventional methods known in the art. Many of the biomass sources described above for use in accordance with the present invention may be agricultural waste. As used herein, the term "agricultural waste" refers to plant-based waste products typically generated as a by-product of agricultural operations. For example, agricultural waste may include leftovers of harvested plant-based products or unwanted portions of harvested plant-based products.

[0077] As used herein, the term "comprising" is used to mean that any additional, undefined components may be present. As used herein, the term "consisting" is used to mean that no additional components other than those specifically listed may be present. As used herein, the term "consisting essentially of" is used to mean that additional, undefined components may be present, but that these components do not materially affect the essential properties of the composition.

[0078] Anti-caking additives The solid biomass fuel of the present disclosure includes at least one anti-coking additive, which may include one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof.

[0079] Examples of aluminosilicate-containing clays that can be used include any such clays known in the art. For example, clays that can be used include kaolin, montmorillonite clay, and illite clay. Preferably, the clay comprises kaolin.

[0080] Examples of aluminosilicates that can be used include any such materials known in the art. Specific examples of aluminosilicates that can be used include one or more aluminosilicate minerals, one or more zeolites, one or more feldspars, one or more aluminosilicate glasses, or any combination thereof.

[0081] The one or more aluminosilicate minerals may include any suitable mineral, such as andalusite, kyanite, sillimanite, or combinations thereof.

[0082] The one or more aluminosilicate glasses may include any suitable aluminosilicate glass, such as an alkali metal or alkaline earth metal aluminosilicate glass.

[0083] The one or more pulverized fuel ash may include any suitable known type of pulverized fuel ash. For example, fly ash produced from the combustion of coal may be used. The one or more pulverized fuel ash typically includes a mixture of silicon dioxide, aluminum oxide, and calcium oxide, which are the primary mineral compounds present in coal-bearing rock formations.

[0084] The solid biomass fuel of the present disclosure may contain any suitable amount of the above-mentioned additives to achieve a coking prevention effect. Preferably, the coking prevention additive is present in the amount described above. Surprisingly, it has been found that the coking prevention additive is effective when included in the solid biomass fuel in very small amounts (e.g., less than 1% by weight of the solid biomass fuel). This is particularly true when the solid biomass fuel is derived from the non-woody type biomass described above. Without being limited by theory, this is believed to be because the additive can be more effectively and uniformly dispersed in the solid biomass fuel when the solid biomass fuel is derived from the preferred non-woody type biomass, as explained in more detail above.

[0085] Therefore, it is preferred that the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ash, or a combination thereof be substantially uniformly dispersed in the solid biomass fuel along with the biomass-derived material. More preferably, the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ash, or a combination thereof be uniformly dispersed in the solid biomass fuel along with the biomass-derived material. The inventors have found that this uniform dispersion of the additive enhances the additive's anti-coking effect and the benefits described above.

[0086] In a highly preferred example, the solid biomass fuel comprises one or more aluminosilicate clays in a total amount of 0.3% to 0.5% by weight of the solid biomass fuel, one or more aluminosilicates in a total amount of 0.1% to 0.2% by weight of the solid biomass fuel, and one or more pulverized fuel ashes in an amount of 0.1% to 0.2% by weight of the solid biomass fuel.

[0087] As used herein, the term anti-coking additive refers to an additive that imparts anti-coking benefits to solid biomass fuels upon combustion. As used herein, the term anti-coking benefit refers to the ability of an additive to reduce or eliminate the tendency of solid biomass fuels to deposit coke upon combustion. As used herein, the term coke refers to liquid or solid deposits containing combustible organic matter that accumulate on the surfaces of a combustion chamber or conduit and other chambers in communication with it during combustion of a solid biomass fuel. Preferably, the combustible organic matter comprises carbon, hydrocarbons, oxygen-containing hydrocarbon compounds, or any combination thereof. The deposits are preferably solid. Solid coke is sometimes referred to as soot, and liquid coke is sometimes referred to as tar. Coke deposits differ from ash deposits in that coke is related to combustible organic matter formed from the incomplete combustion of solid biomass fuels. In contrast, the term ash refers to the non-combustible inorganic residue formed from the complete combustion of solid biomass fuels. As noted above, factors affecting ash-related operational issues and coking during the combustion of solid biomass fuels are different. Coking during combustion occurs through a different mechanism than ash-related operational problems such as slag formation and slag fouling.

[0088] In addition to preventing coke buildup on the interior surfaces of the combustion chamber and conduits and other associated chambers, the anti-coking additives described above have been found to also reduce the tendency of the deposited coke to undergo secondary combustion, resulting in the formation of polluting gaseous secondary combustion products that are typically formed and emitted into the exhaust gas. This is a secondary benefit in addition to its primary effect of reducing coke buildup. In other words, the formation of secondary combustion products is reduced not only because the additive prevents coke buildup in the first place, but also because it reduces the tendency of the deposited coke to undergo secondary combustion and form polluting gases.

[0089] solid biomass fuel The solid biomass fuel product may have any of the physical properties described above.

[0090] The biomass solid fuel of the present disclosure preferably comprises pellets. The pellets may be of any suitable size. Preferably, the pellets have a diameter of 3 mm to 100 mm, more preferably 5 mm to 8 mm. Preferably, the pellets have a length of 20 mm to 60 mm, more preferably 30 mm to 50 mm.

[0091] The biomass fuel of the present invention is sufficiently water-resistant for up to 20 days, preferably up to 30 days, and more preferably up to 40 days. The water-resistant properties of solid biomass fuel can be determined according to standard tests from the Energy Research Centre of the Netherlands (ECN).

[0092] The moisture content of the biomass solid fuel of the present disclosure can also be determined according to the standard ECN test method. The internal moisture content of the solid biomass composition fuel of the present invention is typically less than 8 wt%, preferably less than 6 wt%, and more preferably less than 5 wt%, and the internal moisture content is determined according to DIN EN 14774.

[0093] Biomass composition solid fuels typically have a base moisture content of less than 10 wt%, preferably less than 8 wt%, and most preferably less than 6 wt%, where the base moisture content is determined in accordance with GB / T211-2017.

[0094] Typically, other fuel sources are not included in solid biomass fuels, in addition to additives such as the coking inhibitor additives described above. Thus, solid biomass fuels usually contain only biomass-derived materials as the fuel source in the solid biomass fuel. For example, when the heated biomass composition product is formed into pellets, typically no other fuel sources are added to the biomass source before forming, so that the solid biomass fuel pellets contain only biomass-derived fuel sources.

[0095] Thus, preferably, the solid biomass fuel comprises at least 50% by weight of the total fuel content of the fuel, such as at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, preferably at least 95% by weight of biomass-derived material.

[0096] The solid biomass fuel preferably comprises biomass-derived material in an amount of at least 75% by weight, preferably at least 80% by weight, more preferably at least 90% by weight.

[0097] Method for producing solid biomass fuel Preferably, the method for preparing a solid biomass fuel involves pulverizing, forming, and then torrefying, or pulverizing, torrefying, and then forming, one or more biomass sources. The anti-coking additive is typically added during the step of forming the biomass. It is highly preferred that the anti-coking additive be effectively dispersed in the solid biomass fuel so that it is substantially uniformly dispersed throughout the solid biomass fuel.

[0098] Preferably, the solid biomass fuel is produced by a method for producing a solid biomass fuel, comprising: (i) providing a biomass composition comprising biomass particles having an average particle size (D50) of 1,000 μm to 75,000 μm; (ii) pulverizing the biomass composition to provide a pulverized biomass powder having an average particle size (D50) of 500 μm to 10,000 μm; (iii) drying the finely divided biomass powder to provide a dried finely divided biomass powder; (iv) shaping the dried, finely divided biomass powder to provide a shaped biomass product, wherein the dried, finely divided biomass powder is shaped with one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ash, or a combination thereof to provide the shaped biomass product. (v) heating the formed biomass product to a temperature of 110°C to 500°C for a period of 0.2 to 6 hours to provide a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel; The method is obtained or obtainable by a method comprising:

[0099] Further explanation of each of these steps is included below.

[0100] Providing biomass compositions The method may include step (i) of providing a biomass composition comprising biomass particles having an average particle size (D50) of 1,000 μm to 75,000 μm. Preferably, the biomass composition comprises biomass particles having an average particle size (D50) of 1,000 μm to 60,000 μm. For example, in some instances, the biomass composition comprises biomass particles having an average particle size (D50) of 30,000 μm to 60,000 μm, such as an average particle size of 40,000 μm to 50,000 μm.

[0101] The biomass composition can be provided as particles having the above-mentioned size ranges by introducing one or more biomass sources into a conventional chipping apparatus, although this will of course depend on the particular biomass source. For example, if the biomass source naturally exists as particles having the above-mentioned size ranges, chipping is not necessary. Thus, the methods of the present invention can include chopping one or more biomass sources to provide a biomass composition comprising biomass particles having an average particle size (D50) of 1,000 μm to 75,000 μm, or any of the other size ranges described above.

[0102] The step of providing a biomass composition having an average particle size (D50) of 1,000 μm to 75,000 μm can include harvesting one or more biomass sources using a conventional combine. The combine process involves chopping and reducing the biomass to particles of a desired size.

[0103] The step of providing a biomass composition may further include reducing the moisture content of the biomass to less than 50% by weight. Such a step may include compressing the biomass composition. This compressing step typically involves squeezing water from the biomass composition such that the moisture content of the biomass composition is reduced to less than 50% by weight. Thus, in some examples, the step of providing a biomass composition having the particle size described above includes compressing a biomass composition having a moisture content of greater than 70% by weight such that, after compression, the moisture content of the biomass composition is less than 50% by weight.

[0104] Providing a biomass composition having a particle size as described above may include compressing the biomass and further chopping the biomass.

[0105] The chopping step and the compacting step (if included) may be performed using separate equipment. Alternatively, these steps may be performed in a single device configured for both chipping and compacting the biomass. For example, a motorized rolling device suitable for compacting the biomass can be placed on a conveyor belt feeding a conventional chipping device. In this regard, the biomass source is compacted before entering the chipper. Suitable equipment for performing the compacting and chipping steps of one or more biomass sources is known in the art.

[0106] An example of an apparatus used for chipping is shown in Figure 1. Chipping machines such as that shown in Figure 1 typically operate on the principle that material enters the chipper via a conveying system, such as a conveyor belt, which feeds the material through a feed inlet. The material is then cut into chips by a high-speed rotating blade (not shown) and a blade (not shown) attached to the base of the machine. The function of this and similar chipping mechanisms is known to those skilled in the art.

[0107] Biomass fine grinding Step (ii) may include pulverizing the biomass composition to provide a pulverized biomass powder having an average particle size (D50) of between 500 μm and 10,000 μm.

[0108] The biomass composition can be pulverized into biomass powder by standard techniques known in the art. The biomass composition may be pulverized so that the biomass powder has an average particle size (D50) of 500 μm to 10,000 μm. Preferably, the biomass composition is pulverized to have an average particle size of 1,000 μm to 8,000 μm, more preferably 1,000 to 5,000 μm. As noted above, it has been found that pulverizing non-woody biomass sources, such as the specific biomass sources described above, can advantageously produce biomass powders having a smaller particle size distribution than can be obtained by pulverizing previously known wood-like biomass sources.

[0109] Additionally, it has been found that the narrower the particle size distribution of the pulverized biomass powder, the higher the quality and performance characteristics of the biomass solid fuel product. Without being limited by theory, this is believed to be due to greater uniformity and homogeneity of the final solid biomass fuel product. It is believed that the smaller particle size of the powder and the greater uniformity and homogeneity of the final fuel product also lead to improved fuel performance characteristics during combustion and improved water resistance of the solid fuel product.

[0110] As mentioned above, greater uniformity means that the anti-coking additive is more effectively and uniformly dispersed throughout the solid biomass fuel, which means better anti-coking properties and that lower concentrations of additive can provide more effective anti-coking properties.

[0111] The biomass composition before pulverization typically contains less than 50% moisture by weight.

[0112] For different biomass sources containing different moisture contents, different comminution processes are preferred. For example, when the moisture content of the biomass composition is 20% by weight or less, the step of comminuting the biomass preferably involves the use of a negative pressure pneumatic conveying device. Such negative pressure pneumatic conveying devices are known in the art.

[0113] When the moisture content of the biomass composition is 20% by weight or more, the biomass composition may be directly pulverized without using a negative pressure air conveying device.

[0114] The average particle size (D50) of the biomass particles described above in the context of steps (i) and (ii) of the disclosed method can be determined using techniques known to those skilled in the art. For example, standard tests ISO 17827-1 and / or ISO 17827-2 can be used to calculate the D50 of the biomass particles.

[0115] Drying of finely ground biomass powder The biomass can be dried in step (iii) of the method. Step (iii) of drying the finely divided biomass powder to provide a dried finely divided biomass powder typically involves drying the finely divided biomass powder so that the dried finely divided biomass powder has a moisture content of 10% to 18% by weight, preferably 12% to 15% by weight. However, it will be appreciated that it is not necessary for the dried finely divided biomass powder to have a moisture content within this range.

[0116] The step of drying the biomass powder can also include mixing the finely ground biomass powder. If one biomass source is used in the method, this single biomass source may be mixed. Alternatively, if two or more biomass sources are used in the method, the drying step may involve mixing the finely ground biomass powder with one or more additional biomass sources. For example, if the solid biomass fuel is formed from at least two biomass sources, the two or more biomass sources may be mixed during any step of the disclosed method; preferably, the biomass sources are mixed during the drying step of the disclosed method. Thus, the finely ground biomass powder may be mixed with an additional biomass source that is also a finely ground biomass powder prepared using the method steps described herein. Alternatively, the one or more additional biomass sources mixed with the finely ground biomass powder during the drying step are not processed as described herein. For example, the finely ground biomass powder prepared as described herein may be mixed with one or more additional biomass sources prepared by a different method.

[0117] At this stage in the process, the anti-coking additive may also be mixed with the biomass-derived material.

[0118] The finely ground biomass powder can be dried using any suitable method, such as using standard drying cylinders known in the art. For example, the drying step may be carried out in a drying apparatus comprising a rotary drying drum. Rotation of the rotary drying drum can be used to mix the finely ground biomass powder with one or more additional biomass sources, as described above. Typically, the rotary drying drum comprises a lifting plate, which continuously lifts the material while the drying cylinder rotates.

[0119] When the pulverized biomass powder has a moisture content of less than 20 wt%, the pulverized biomass powder is typically dried in a single drying cylinder. Thus, in such cases, the methods of the present disclosure include drying the pulverized biomass powder in only a single drying cylinder.

[0120] When the finely ground biomass powder has a moisture content greater than 20 wt%, the finely ground biomass powder is typically dried in multiple drying cylinders. Thus, in such cases, the method of the present disclosure includes drying the finely ground biomass powder in two or more drying cylinders. For example, the method may include drying the finely ground biomass powder in two or more, three or more, four or more, or five or more, or five or six or more drying cylinders.

[0121] Molding of dried, finely ground biomass powder The dried, finely ground biomass powder can be shaped to provide a shaped biomass product. The shaping step can be carried out in any shaping device known in the art and according to biomass shaping techniques known in the art, and can include an extrusion molding system. Preferably, the shaping step is carried out in a compression mold. Preferably, the compression mold includes a shaped product discharge hole. The shaping step can be carried out using an apparatus such as that described in CN105435708.

[0122] Preferably, the forming step comprises forming the dried, finely divided biomass powder into pellets. Thus, preferably, the formed biomass product and the solid biomass fuel product comprise biomass pellets.

[0123] It has been found that adapting the molding step to control the density of the resulting molded biomass product to be within a specific range can impart certain advantageous properties to the final solid biomass fuel product. Specifically, controlling the molding step to provide a density of the molded biomass product within a range of 1.0 to 1.35 kg / L can impart advantageous properties to the final biomass fuel product. Preferably, the molding step is controlled to provide a density of the molded biomass product between 1.0 kg / L and 1.35 kg / L. Typically, the aforementioned density is determined in accordance with NY / T 1881.7-2010. Thus, preferably, the molding step is controlled to provide a density of the molded biomass product between 1.0 kg / L and 1.35 kg / L, the density being determined in accordance with NY / T 1881.7-2010.

[0124] The molding step can be controlled in various ways. When the molding method involves the use of a compression mold, the density is typically controlled by using a compression ratio of less than 8, for example less than 7, less than 6, less than 5, or less than 4. Preferably, a compression ratio of 3.5 or less, more preferably 3 or less, and most preferably 1 to 3 is used.

[0125] The inventors have found that these compression ratios are preferred for shaping finely divided biomass containing anti-coking additives for use in the present invention.

[0126] The compression ratio of a compression mold having a formed product discharge hole can be defined as the ratio of the length of the formed product discharge hole to its diameter. Figure 2 shows an example of a compression mold that can be used in accordance with the present invention. After dry, finely ground biomass powder is inserted into the interior of the mold, it is squeezed out of the mold by pressure so that it exits through the formed product discharge hole shown in the figure. The compression ratio is shown in the figure as the ratio of the length of the product discharge hole to its diameter.

[0127] Typically, the lower the compression ratio, the lower the density of the molded biomass product. A higher density of the molded biomass product, such as within the above range, is desirable because the inventors believe that increased bulk density, increased water resistance, and increased uniformity of the solid fuel product, along with increased durability of the final solid biomass fuel product, are associated with this. Therefore, a higher compression ratio is often desirable to provide a final solid biomass fuel product with desired properties. However, the higher the compression ratio, the lower the yield of the molded biomass product. Higher compression ratios also typically increase process costs due to the increased pressure involved in molding the biomass. Therefore, a balance should be struck between a compression ratio that is high enough to provide the desired fuel properties, but not too high, which reduces process yield or increases process costs. When the anti-coking additive of the present disclosure is included in a solid biomass fuel composition, the above-mentioned compression ratios have been found to be preferred to provide a balance between process yield and desirable solid fuel properties.

[0128] Preferably, a molding additive is added to the dried, finely ground biomass powder prior to step (iv) of molding the dried, finely ground biomass powder. The additive is believed to improve the molding process and increase the yield of molded biomass product produced from the molding step. Suitable molding additives are known in the art and include, but are not limited to, starch or starch derivatives.

[0129] Typically, other than the molding additives described above, no other fuel source is added to the dried, pulverized biomass powder during the molding step. Thus, the molded biomass product of the molding step typically contains only biomass-derived materials as the fuel source for the solid biomass fuel. For example, when the dried, pulverized biomass powder is molded into pellets, typically no other fuel source is added to the dried, pulverized biomass product before molding, so that the solid biomass fuel pellets produced at the end of the process contain only biomass-derived fuel sources. Thus, preferably, the solid biomass fuel contains at least 50% by weight, e.g., at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, and preferably at least 95% by weight, of the total fuel content of the fuel.

[0130] As used herein, the term total fuel content of a solid fuel is intended to refer to the components of the solid fuel that are combustible materials, such as biomass-derived materials, coal, etc. The term fuel content with respect to a solid fuel is not intended to encompass additives that may be present in the solid fuel pellets that do not themselves combust to produce energy.

[0131] The molding step has also been found to improve the water resistance of the final biomass solid fuel product: an increase in density occurs during the molding step, meaning that water is less likely to penetrate the denser molded biomass product particles.

[0132] Furthermore, in denser products, more of the biomass is concentrated inside the molded product and therefore does not come into direct contact with water.

[0133] One or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof, and dried, finely divided biomass powder are compacted together in a mass ratio to provide a solid biomass fuel containing a desired amount of anti-coking additive.

[0134] As mentioned above, the anti-coking additive is preferably added to the biomass particles prior to shaping and mixed as uniformly as possible with the biomass particles prior to shaping.

[0135] Heating of molded biomass products The formed biomass product can be heated to produce solid biomass fuel. Heating is carried out at a temperature of 110°C to 500°C for a period of 0.2 to 6 hours. Preferably, the step of heating the formed biomass product is carried out for a period of 0.3 to 2.5 hours. Preferably, the step of heating the formed biomass product includes heating the formed biomass product to a temperature of 220°C to 350°C, more preferably to a temperature of 220°C to 320°C.

[0136] Preferably, step (v) of heating the formed biomass product comprises heating the formed biomass product under conditions that induce torrefaction of the formed biomass product. Torrefaction is a process of mild pyrolysis in which heating is carried out in a low-oxygen atmosphere, for example, an atmosphere containing less than 10% oxygen. Suitable torrefaction conditions and processes are known in the art. Thus, preferably, step (v) of heating the formed biomass product comprises torrefaction.

[0137] The heating step can be carried out in any suitable apparatus known in the art for heating formed biomass products, for example, the heating step may be carried out using the apparatus and process conditions as disclosed in EP 3287509.

[0138] Preferably, step (v) of heating the formed biomass product is adapted to control the uniformity of the solid biomass fuel, and wherein adapting step (v) to control the uniformity of the solid biomass fuel may include performing step (v) in an apparatus that rotates the formed biomass product while heating it, and adapting step (v) to control the uniformity of the solid biomass fuel may include controlling the rotation speed or direction of the formed biomass product, and may rotate the formed biomass product in both counterclockwise and clockwise directions in the apparatus. The uniformity of the solid biomass fuel is also optimized by the heating temperature and heating time described above.

[0139] The method of the present disclosure may include a step of cooling the solid biomass fuel after heating. When the method of the present disclosure includes a cooling step after the step of heating the biomass, the cooling step may include rotating the solid biomass fuel. The biomass may be rotated in a suitable apparatus such as that disclosed in EP 3287509 A1. Preferably, both the heating step (v) and the step of cooling the biomass include rotating the biomass. If the biomass is rotated in either the cooling step or the heating step, the biomass may be rotated in different directions, for example, both clockwise and counterclockwise in successive cycles.

[0140] The term "uniformity" of a solid biomass product is used to refer to a solid biomass fuel or formed biomass product having constant or similar properties across each particle of the solid biomass fuel or formed biomass product, and across multiple particles in a bulk sample of the solid biomass fuel product or formed biomass product, such as, but not limited to, particle density, particle combustibility, particle chemical composition, particle water resistance, etc. Uniformity is a highly desirable property for biomass fuels used in combustion processes.

[0141] The inventors have also found that controlling the heating step as described above further helps provide a solid biomass fuel product with improved water resistance. During the heating step, hydrophilic compounds present in the biomass powder that absorb water are decomposed. Furthermore, the heating step causes oils present in the biomass powder to migrate to the outside of the biomass powder particles, increasing the hydrophobicity of the particles.

[0142] Removal of dust particles from solid biomass fuels. The method of the present disclosure may include a step of removing dust particles from the solid biomass fuel. The inventors of the present invention have found that in biomass solid fuel production processes known in the art, a significant amount of dust adheres to the solid biomass fuel. This dust is problematic because it can pollute the air during transportation and packaging of the solid biomass fuel. The dust can also pollute the surrounding environment. Furthermore, when stored outdoors, the dust particles can cause mold, which affects the performance and quality of the solid biomass fuel. Therefore, it is beneficial to remove dust from the particle surface of the solid biomass fuel.

[0143] The inventors have discovered that dust on the surface of biomass solid fuel particles can be removed by inducing friction between the particles. For example, dust attached to the particles can be removed by inducing friction by means such as vibrating or rotating the solid biomass fuel particles. Thus, step (vi) of removing dust from the solid biomass particles can include inducing friction between the particles of the solid biomass fuel. For example, step (vi) of removing dust from the solid biomass particles can include subjecting the particles to vibration, rotation, tumbling, or any combination thereof. Suitable devices for tumbling, rotating, and vibrating solid biomass fuel particles are known to those skilled in the art. An example of a device that can be used to remove dust from the particles is a rotary drum sieve.

[0144] Step (vi) of removing dust particles from the solid biomass fuel may include using a screen to remove the dust particles from the solid biomass fuel. Typically, the screen has a pore size of 2 mm to 10 mm, preferably 2 mm to 8 mm, more preferably 2 mm to 5 mm, and most preferably 2 mm to 3 mm. Dust particles mixed with the solid biomass fuel particles can be separated from the solid biomass fuel by passing through the screen. Larger solid biomass fuel particles do not pass through the screen and are therefore separated from the dust particles. Suitable devices and methods for performing the screening step are known to those skilled in the art, and any of the suitable devices can be used. For example, a device that screens, tumbles, or rotates the solid biomass fuel can be used to remove dust particles from the solid biomass fuel. In using such a device, the solid biomass fuel may be placed on the screen, and the screen may be driven to tumble and rotate around its axis by the operation of a motor. While the screen is rolling / tilting or rotating, the material on the sieving surface of the screen is inverted. Some material passes through the screen and is separated from material that does not pass through the screen. The rolling and rotation of the screen causes material stuck in the screen holes to fall, thus preventing clogging of the screen holes. Alternatively, a device for vibrating and screening the solid biomass fuel particles can be used. In this case, a motor can be used to vibrate the screen, which can cause material to bounce up onto the screen surface. This process dislodges small particles that are attached to larger particles, allowing them to pass through the screen holes. An example of a device using a screen and vibration to separate larger particles from smaller particles, which may or may not be attached to the larger particles, is the device taught in CN201324717.

[0145] Therefore, the method of the present disclosure can include subjecting the solid biomass fuel particles to one or more of tumbling, rotating, and vibrating to induce friction between the solid biomass fuel particles, which causes dust particles adhering to the solid biomass fuel particles to be removed from the particles. The method then preferably includes subjecting the mixture of solid biomass fuel particles and dust particles to the above-mentioned screening step to remove the dust particles from the solid biomass fuel particles. Therefore, the removal step (vi) is an effective post-treatment for removing dust from the particles of solid biomass fuel. [Example]

[0146] Various solid biomass fuels of the present invention were produced using the method of the present invention. The molding step involved the use of a compression die having a compression ratio of 3. An anti-coking additive was added to the biomass material prior to the molding step. Prior to the molding step, the biomass particles and the anti-coking additive were mixed to form a uniform mixture, which was then molded into pellets. During the heating step, the molded pellets were heated to a temperature of 320°C for 1.8 hours.

[0147] The anti-coking additives used were kaolin in an amount of 0.4 wt.% based on the solid biomass fuel, aluminosilicate in an amount of 0.1 wt.% based on the solid biomass fuel, and pulverized coal fuel ash in an amount of 0.1 wt.% based on the solid biomass fuel. Thus, each solid fuel product contained 0.6 wt.% of the anti-coking additive.

[0148] The biomass source materials used are detailed in Table 1 below. [Table 1]

[0149] The bulk density of each solid biomass fuel ranged from 0.6 to 0.7 kg / L.

[0150] The mechanical durability of each solid biomass fuel was in the range of 95% to 98%. The mechanical durability of each of fuels A to F, H, and I was 97% or higher.

[0151] The dry sulfur content of each solid biomass fuel ranged from 0.02 wt% to 0.25 wt%.

[0152] The dry hydrogen content of each solid fuel ranged from 5 wt% to 6 wt%.

[0153] The dry oxygen content of each solid biomass fuel ranged from 30 wt% to 38 wt%.

[0154] The dry carbon content of each solid biomass fuel ranged from 50 wt% to 58 wt%.

[0155] The dry nitrogen content of each solid biomass fuel ranged from 0.5 wt% to 1.6 wt%.

[0156] The chemical oxygen demand of each solid biomass fuel ranged from 1100 to 2700.

[0157] The fixed carbon content of each solid biomass fuel ranged from 27 wt% to 40 wt%.

[0158] The ash content of each solid biomass fuel ranged from 4 wt% to 16 wt%.

[0159] The internal moisture content of each solid biomass fuel ranged from 0.4 wt% to 2.8 wt%.

[0160] The volatile matter content of each solid biomass fuel ranged from 48% to 67%.

[0161] The PM1.0 emissions from each solid biomass fuel ranged from 129 to 145 mg / kg.

[0162] The calorific value of each solid biomass fuel ranged from 5000 to 6200 kcal / kg.

[0163] The moisture content of each solid biomass fuel on an as-received basis ranged from 1.5% to 4.5%.

[0164] The pH of each solid biomass fuel ranged from 4.5 to 8.6.

[0165] Thus, the solid biomass fuels of Examples A to M have desirable high-performance fuel properties, such as high bulk density, mechanical durability, energy content, and water resistance, which are comparable to the solid biomass fuels produced in the prior art publications WO 2020 / 229824, WO 2021 / 014151, WO 2021 / 024001, and WO 2021 / 156628.

[0166] Comparative Example Compositions A-K were also prepared using the same method as the Example compositions, with the only difference between Example Compositions A-K and Comparative Example Compositions A-K being that the Comparative Example compositions did not contain an anti-coking additive.

[0167] The coke properties of the solid biomass fuels produced in Examples A to M, as determined according to GB / T8727-2008, are shown in Figure 3. The coke properties of the comparative example compositions A to K are shown in Figure 4.

[0168] It can be seen that each of the inventive example compositions had a lower coke property score than all of the comparative example compositions, indicating that the inventive compositions produced fewer coke deposits and emitted fewer secondary combustion products upon combustion. Thus, a comparison of these figures demonstrates that the coking inhibitor additives used in the present invention effectively improve the coke properties of solid biomass fuels derived from a variety of different biomass sources.

Claims

1. 1. A solid biomass fuel derived from one or more biomass sources, wherein the one or more biomass sources include straw, palm-derived materials, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof; and the solid biomass fuel further comprises one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ash, or a combination thereof.

2. 2. The solid biomass fuel of claim 1, wherein the one or more biomass sources comprise straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof in an amount of at least 50% by weight, preferably at least 75% by weight, more preferably at least 90% by weight.

3. 3. The solid biomass fuel of claim 1 or 2, wherein the one or more biomass sources consist essentially of straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof.

4. 4. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of straw, and the straw is selected from rice straw, tobacco straw, sesame straw, chili straw, eggplant straw, cotton straw, sorghum straw, sunflower stalk, wheat stalk, corn stalk, rapeseed stalk, tapioca straw, bean stalk, or any combination thereof.

5. 4. The solid biomass fuel of any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of palm-derived material, and the palm-derived material is selected from palm trunks, palm fronds, palm empty fruit bunches (EFB), palm kernel shells (PKS), palm oil residue, palm husks, coconut shells, coconut fiber, or any combination thereof.

6. 4. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of nut shells, and the nut shells are selected from cashew nut shells, peanut shells, chestnut shells, pistachio shells, sunflower seed shells, walnut shells, pine cone shells, or any combination thereof.

7. 4. The solid biomass fuel of any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of hemp, and the hemp is selected from ramie, jute, green hemp, flax, robin, hibiscus, or any combination thereof.

8. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of bamboo, and the bamboo is selected from Moso bamboo, Manchuria bamboo, Yatake bamboo, or any combination thereof.

9. 4. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of fruit shells, the fruit shells being selected from coconut shells, lychee shells, cinnamon (longan) shells, snakeskin fruit shells, mangosteen shells, durian shells, or any combination thereof.

10. 4. The solid biomass fuel of any of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of crop residues, said crop residues being selected from wheat husk, bagasse, okara, peanut residue, cassava residue, sweet potato residue, coffee bean residue, or any combination thereof.

11. 4. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise or consist essentially of grass, and the grass is selected from plants of the genus Pennisetum, such as Pennisetum sinense roxb.

12. 12. A solid biomass fuel according to any preceding claim, wherein the material derived from one or more biomass sources is present in the solid biomass fuel in an amount of at least 80% by weight.

13. 13. A solid biomass fuel according to any preceding claim, wherein material derived from one or more biomass sources is present in the solid biomass fuel in an amount of at least 90% by weight.

14. 14. A solid biomass fuel according to any preceding claim, wherein the material derived from one or more biomass sources is present in the solid biomass fuel in an amount of at least 95% by weight.

15. 15. The solid biomass fuel according to any one of claims 1 to 14, wherein the one or more aluminosilicate-containing clays comprise kaolin.

16. 16. The solid biomass fuel according to any one of claims 1 to 15, wherein the one or more aluminosilicates comprise one or more aluminosilicate minerals, one or more zeolites, one or more feldspars, one or more aluminosilicate glasses, or any combination thereof.

17. 17. A solid biomass fuel according to any one of the preceding claims, wherein the total amount of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof present in the solid biomass fuel is from 0.1% to 10% by weight of the solid biomass fuel, preferably from 0.1% to 5% by weight of the solid biomass fuel.

18. 18. A solid biomass fuel according to any one of claims 1 to 17, wherein the total amount of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof present in the solid biomass fuel is from 0.1% to 1% by weight of the solid biomass fuel.

19. 19. A solid biomass fuel according to any one of the preceding claims, wherein the total amount of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof present in the solid biomass fuel is from 0.1% to 0.8% by weight of the solid biomass fuel, preferably from 0.5% to 0.8% by weight of the solid biomass fuel.

20. 20. The solid biomass fuel of claim 19, wherein the solid biomass fuel comprises one or more aluminosilicate-containing clays in a total amount of 0.3% to 0.5% by weight, based on the solid biomass fuel, one or more aluminosilicates in a total amount of 0.1% to 0.2% by weight, based on the solid biomass fuel, and one or more finely divided fuel ashes in an amount of 0.1% to 0.2% by weight, based on the solid biomass fuel.

21. 21. The solid biomass fuel of claim 20, wherein the one or more aluminosilicate-containing clays comprise kaolin.

22. 22. The solid biomass fuel of any one of claims 1 to 21, wherein the one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof are uniformly dispersed in the solid biomass fuel along with biomass-derived material.

23. 23. The solid biomass fuel according to any one of the preceding claims, wherein the bulk density of the solid biomass fuel, determined in accordance with DIN EN 15103, is from 0.50 kg / l to 0.8 kg / l, preferably from 0.60 kg / l to 0.75 kg / l, more preferably from 0.60 to 0.70 kg / l.

24. 24. The solid biomass fuel according to any one of claims 1 to 23, wherein the mechanical durability of the solid biomass fuel, determined in accordance with DIN EN 15210-1, is 97% or more.

25. (i) the total dry sulfur content of the solid biomass fuel is 0.5 wt% or less, preferably 0.45 wt% or less, most preferably 0.40 wt% or less, wherein the total dry sulfur content is determined in accordance with DIN EN 15289; (ii) the total dry hydrogen content of the biomass solid fuel is 3 wt% or more, preferably 5 wt% to 10 wt%, more preferably 5 wt% to 7 wt%, wherein the total dry hydrogen content is determined in accordance with DIN EN 15104; (iii) the total dry oxygen content of the biomass solid fuel is 20 wt% or more, preferably 25 wt% to 42 wt%, more preferably 28 wt% to 40 wt%, wherein the total dry oxygen content is determined in accordance with DIN EN 15296; (iv) the total dry carbon content of the biomass solid fuel is 40 wt% or more, preferably 45 wt% to 65 wt%, more preferably 50 wt% to 60 wt%, wherein the total dry carbon content is DIN EN 15296; 25. The solid biomass fuel according to any one of claims 1 to 24, wherein (v) the total dry nitrogen content of the biomass solid fuel is less than 5.0 wt. %, preferably less than 3.0 wt. %, more preferably less than 2.5 wt. %, wherein the total dry nitrogen content is determined in accordance with DIN EN 15104.

26. (i) the chemical oxygen demand (COD) of the solid biomass fuel when immersed in water is 5000 ppm or less, preferably 4000 ppm or less, most preferably 3200 ppm or less, wherein the chemical oxygen demand is determined in accordance with GB / 11914-89; (ii) the fixed carbon content of the solid biomass fuel is 20 wt % or more, preferably 25 wt % to 45 wt %, wherein the fixed carbon content is determined in accordance with DIN EN 51734; (iii) the ash content of the solid biomass fuel is less than 20 wt %, preferably less than 18 wt %, wherein the ash content is determined at 550°C in accordance with EN 14775; (iv) the volatile matter content of the solid biomass fuel is 35 wt % to 80 wt %, more preferably 40 wt % to 75 wt %, wherein the volatile matter content is determined in accordance with DIN EN 51734. 15148, and / or (v) the internal moisture content of the solid biomass fuel is less than 8 wt. %, preferably less than 6 wt. %, more preferably less than 5 wt. %, wherein the internal moisture content is determined in accordance with DIN EN 14774.

27. 27. The solid biomass fuel according to any one of claims 1 to 26, wherein the solid biomass fuel has a calorific value of 4300 kcal / kg to 6750 kcal / kg, said calorific value being determined in accordance with DIN EN 14918.

28. 28. A solid biomass fuel according to any preceding claim, wherein the solid biomass fuel has a reference moisture content of less than 10 wt%, preferably less than 8 wt%, most preferably less than 6 wt%, wherein the reference moisture content is determined in accordance with GB / T 211-2017.

29. The solid biomass fuel according to any one of claims 1 to 28, wherein the solid biomass fuel has a pH of 4 to 10.

30. 30. A solid biomass fuel according to any preceding claim, wherein the solid biomass fuel has a coke index of 1.5 or less, preferably 0.3 to 1.5, when burned, said coke index being determined in accordance with GB / T 8727-2008.

31. A solid biomass fuel according to any preceding claim, wherein the solid biomass fuel is water resistant for up to 20 days, preferably up to 30 days, more preferably up to 40 days.

32. A solid biomass fuel according to any one of claims 1 to 31, wherein the PM1.0 emissions when the solid biomass fuel is burned are less than 175 mg / kg, preferably less than 150 mg / kg.

33. 33. A method of combustion comprising combusting a solid biomass fuel according to any of claims 1 to 32 to produce energy.

34. 34. The method of claim 33, wherein the solid biomass composition fuel is co-combusted and combusted with a fossil fuel, such as coal.

35. 35. The method according to claim 33 or 34, wherein the PM1.0 emissions of the method are less than 175 mg / kg, preferably less than 150 mg / kg.

36. 1. Use of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more finely divided fuel ashes, or combinations thereof, as an anti-coking additive in solid biomass fuel.

37. 37. The use of claim 36, comprising using the anti-coking additive to reduce or prevent the formation of solid and / or liquid combustible organic deposits during the combustion of solid biomass fuel.

38. 38. The use of claim 37, wherein deposits of solid and / or liquid combustible organic matter accumulate on surfaces of a combustion chamber used to combust the solid biomass fuel and / or on conduits in fluid communication therewith.

39. 39. Use according to claim 37 or 38, comprising using the anti-coking additive to prevent or reduce the secondary combustion of deposits of solid and / or liquid combustible organic matter.

40. 40. The use according to any one of claims 37 to 39, wherein the solid and / or liquid combustible organic matter comprises soot, tar, or a combination thereof.

41. 41. The use of any of claims 36 to 40, wherein the solid biomass fuel is derived from one or more biomass sources, and the one or more biomass sources comprise straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, residues, seaweed, Calliandra calochylus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof.

42. 42. Use according to any one of claims 36 to 41, wherein the solid biomass fuel is as defined in any one or more of claims 2 to 32.

43. A method for producing a solid biomass fuel according to any one of claims 1 to 32, comprising: (i) providing a biomass composition comprising biomass particles having an average particle size (D50) of 1,000 μm to 75,000 μm; (ii) pulverizing the biomass composition to provide a pulverized biomass powder having an average particle size (D50) of 500 μm to 10,000 μm; (iii) drying the finely divided biomass powder to provide a dried finely divided biomass powder; (iv) shaping the dried, finely divided biomass powder to provide a shaped biomass product, wherein the dried, finely divided biomass powder is shaped with one or more aluminosilicate-containing clays, one or more aluminosilicates, pulverized fuel ash, or a combination thereof to provide the shaped biomass product; (v) heating the formed biomass product to a temperature of 110°C to 500°C for a period of 0.2 to 6 hours to provide a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel; The method comprising:

44. 44. The method of claim 43, wherein the biomass composition comprises one or more biomass sources comprising straw, palm-derived material, nut shells, hemp, bamboo, corn cobs, rice husks, fruit husks, crop residues, seaweed, Calliandra calochysus, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof, wherein the one or more biomass sources may be as defined in any of claims 2 to 11.

45. 45. The method of claim 43 or 44, wherein the solid biomass fuel, the one or more aluminosilicate-containing clays, the one or more aluminosilicates and / or the pulverized fuel ash are as defined in any of claims 2 to 32.

46. 46. ​​The method of any of claims 43-45, wherein adapting the shaping step to control the density of the shaped biomass product comprises controlling the compression ratio of a mold used in the shaping step.

47. 47. The method of any of claims 43 to 46, wherein step (iv) of shaping the dried, finely ground biomass powder to provide a shaped biomass product comprises shaping the dried, finely ground biomass powder using a compression die having a compression ratio of less than 6, preferably less than 5.

48. 48. The method of any of claims 43 to 47, wherein step (iv) of shaping the dried, finely divided biomass powder to provide a shaped biomass product comprises shaping the finely divided biomass powder using a compression die having a compression ratio of 3.5 or less, preferably 3 or less, more preferably 1 to 3.

49. 49. A method according to any one of claims 43 to 48, wherein the one or more aluminosilicate-containing clays, the one or more aluminosilicates, the one or more finely divided fuel ash, or a combination thereof, and the dried, finely divided biomass powder are compacted together in a mass ratio to provide a solid biomass fuel comprising a total amount of the one or more aluminosilicate-containing clays, the one or more aluminosilicates, the one or more finely divided fuel ash, or a combination thereof, of from 0.1% to 10% by weight of the solid biomass fuel, preferably from 0.1% to 5% by weight of the solid biomass fuel, more preferably from 0.1% to 1% by weight of the solid biomass fuel, and most preferably from 0.1% to 0.8% by weight of the solid biomass fuel.

50. 50. A method according to any one of claims 44 to 49, wherein the one or more aluminosilicate-containing clays, the one or more aluminosilicates, the one or more finely divided fuel ash, or a combination thereof, and the dried, finely divided biomass powder are compacted together in a mass ratio to provide a solid biomass fuel comprising a total amount of the one or more aluminosilicate-containing clays, the one or more aluminosilicates, the one or more finely divided fuel ash, or a combination thereof, of from 0.5% to 0.8% by weight of the solid biomass fuel.

51. 51. The method of claim 50, wherein the one or more aluminosilicate-containing clays, the one or more aluminosilicates, the one or more finely divided fuel ashes, or combinations thereof, are compacted together with dried, finely divided biomass powder in a mass ratio to provide a solid biomass fuel comprising one or more aluminosilicate clays in an amount of 0.3% to 0.5% by weight based on the solid biomass fuel, one or more aluminosilicates in a total amount of 0.1% to 0.2% by weight based on the solid biomass fuel, and one or more finely divided fuel ashes in an amount of 0.1% to 0.2% by weight based on the solid biomass fuel.

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