Anti-coking additive for solid biomass fuel

Abstract

The invention relates to a solid biomass fuel derived from one or more biomass sources, wherein the one or more biomass sources comprise straws, palm derived materials, nutshells, hemp plants, bamboos, corncobs, rice husks, shells, crop residues, seaweed, albizia albizzia, acacia mangium, albizia chinensis, Brazil hevea brasiliensis, grass or any combination thereof; wherein the solid biomass fuel further includes one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof.

Description

Technical Field

[0001] The present invention relates to the use of an additive for preventing or reducing coking during the combustion of solid biomass fuels, and to solid biomass fuels comprising said additive. Furthermore, the present invention relates to a combustion method comprising combusting said solid biomass fuel comprising said additive to generate energy. The present invention also relates to a method for preparing a solid biomass fuel comprising said additive. Background Art

[0002] Coal-fired power generation is used in power plants and industrial processes around the world. Coal and other fossil fuels are non-renewable energy sources. In the past few decades, there has been a call to reduce coal consumption in coal-fired power plants and switch to using renewable resources as energy sources.

[0003] Fuels derived from biomass are a renewable energy source that can be used to replace or at least partially replace coal. During combustion, fuels derived from biomass can be burned in the presence of oxygen in a power plant to generate energy. Fuels derived from biomass can be burned in traditional power plants originally designed for coal combustion, or fuels derived from biomass can be burned in power plants dedicated to 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 called co-firing of biomass with coal. In order to be suitable for co-firing with coal, fuels derived from biomass usually must have certain properties, such as a certain level of quality and homogeneity. For example, it is particularly desirable for fuels derived from biomass to consist of particles of uniform size, density, moisture content, etc. during co-firing. It is also desirable for biomass fuels to contain a low ash content. The ash content in fuels derived from biomass is generally higher than the ash content in coal.

[0004] There are known various methods for preparing solid biomass fuels from biomass sources. WO2016 / 056608, WO2017 / 175733, and WO2019 / 069849 disclose methods for forming solid biomass fuels from various lignocellulosic biomass sources. However, those skilled in the art are aware that the solid biomass fuels and their production methods discussed in these documents have various problems associated therewith. For example, the lignocellulosic biomass sources described in the above documents typically only occur naturally and are not easily grown and harvested on a commercial scale. In addition, the lignocellulosic biomass sources described in these documents form particles with relatively low uniformity after being treated by conventional comminution techniques, which means that the solid biomass fuels produced from such materials are not sufficiently uniform. In view of these problems, there is a need in the art for a method for producing high-performance solid biomass fuels from alternative biomass sources (i.e., non-lignocellulosic biomass sources). Specific solutions to these problems are disclosed in WO2020 / 229824, WO2021 / 014151, WO2021 / 024001, and WO2021 / 156628, which are aimed at ameliorating the above problems. Despite the solutions proposed in the above documents, there is still a need in the art for high-performance solid biomass fuels.

[0005] A specific problem associated with solid biomass fuels is that, during fuel combustion, ash often deposits in the combustion chamber and in pipes in fluid communication with the combustion chamber, such as pipes for discharging flue gas. Ash is the non-combustible inorganic mineral component remaining after complete combustion of the solid biomass fuel. Ash typically contains a large amount of non-combustible alkali metal salts (especially potassium). Alkali metal salts are often found in the ash combustion by-products, such as potassium chloride, potassium sulfate, and hydroxides. These mineral salts typically have relatively low melting points. For example, the melting point of potassium chloride is only 770 °C, and the temperature during biomass combustion often exceeds this temperature, causing the inorganic mineral salts to melt. Molten salts can cause problems during combustion because they become sticky upon cooling and adhere to the various inner surfaces of the combustion chamber and the pipes in fluid communication with the combustion chamber. This process is called slagging. These salts also form fine aerosol particles that are emitted as harmful pollutants in the flue gas. Gaseous alkali metal compounds (such as potassium chloride, potassium hydroxide, and potassium sulfate) may also condense on the metal surfaces of the pipes in fluid communication with the combustion chamber and react adversely therewith. These processes ultimately lead to fouling of the combustion equipment. Compared with conventional coal, the combustion problems associated with ash in solid biomass fuels are generally more severe because biomass typically contains higher levels of inorganic salts and metal ions than coal.

[0006] Another problem associated with the combustion of solid biomass fuels is a phenomenon called coking that occurs during fuel combustion. Coking refers to the formation of organic combustible deposits in the combustion chamber and in pipes or chambers in fluid communication therewith during the combustion of solid biomass fuels. Coking is a result of incomplete fuel combustion. Deposits that may form during the coking process include soot. Soot includes amorphous carbon particles and heavy hydrocarbons such as polycyclic aromatic hydrocarbons (PAHs). Soot typically exists as a solid deposit in the combustion chamber and the flue gas chimney. Thus, soot can clog combustion equipment, leading to operational problems. Smoke particles may also be emitted in the flue gas, which is highly undesirable due to their greenhouse gas effects. Soot may also be carcinogenic. Therefore, it is desirable to minimize the formation of soot. Other deposits that may form during the coking process include tar, which is a viscous liquid composed of carbon and heavier hydrocarbons such as asphaltenes. Tar is also deposited in a manner similar to the above-mentioned soot during the coking process and causes similar problems. The deposited coke (such as tar and soot) may also burn at the temperatures in the combustion chamber and associated pipes, a process called afterburning. Such a process forms undesirable polluting gaseous combustion products in the flue gas. The coking characteristics of solid biomass fuels are different from and unrelated to the tendency of biomass fuels to exhibit ash-related problems during combustion. Ash-related problems and coking are different phenomena that are caused by different factors and propagate through different mechanisms.

[0007] The factors that determine whether a large amount of coking occurs during fuel combustion are diverse and complex. Coking may be caused by incomplete combustion of solid biomass fuels. Factors such as combustion temperature and how much oxygen successfully mixes into the fuel during combustion will affect the degree of coking. Generally, lower combustion temperatures and lower air-fuel ratios will result in more coking and promote incomplete combustion. The composition of the fuel also severely affects the degree of coking and soot formation. Coking and the formation of soot and tar occur through complex chemical mechanisms that are not yet fully understood and may vary greatly between different fuels with different chemical compositions. For example, in the case of fossil fuels, naphthalene tends to form more soot than benzene, and benzene in turn forms more soot than aliphatic fuels. Due to the different chemical properties of fuels, the coking characteristics of coal and solid biomass fuels are also different. For example, in fossil fuels such as coal, the vast majority of fuels are hydrocarbons (such as aromatic hydrocarbons, alkanes, alkenes, etc.). In fuels derived from biomass, there are a larger number of compounds containing heteroatoms (such as oxygen-containing compounds). This is because compounds containing such heteroatoms are abundant in nature. For example, the main parts of some forms of biomass are the polymers cellulose and lignin. Cellulose is a polysaccharide and thus contains a large number of oxygen atoms. Lignin also contains a large number of oxygen atoms. Therefore, fuels produced from biomass generally contain more oxygen-containing compounds than fossil fuels. These chemical differences result in differences in the coking characteristics of fuels. Due to the different chemical properties of different types of biomass (for example, the content of lignin and cellulose in different types of biomass is different), the coking characteristics of different solid biomass fuels (such as fuels from different types of biomass sources) may also vary greatly.

[0008] There is still a need in the art for methods to reduce coking during the combustion of solid biomass fuels. Specifically, there is still a need in the art for additives that can effectively reduce coking in solid biomass fuels from various different biomass sources. Summary of the Invention

[0009] The present invention is based on a surprising finding that the coking characteristics of solid biomass fuels can be improved when certain additives are added to the solid biomass fuels. The inventors have unexpectedly found that the coking characteristics of solid biomass fuels can be improved when an additive comprising one or more clays containing aluminosilicates, one or more aluminosilicates, one or more pulverized fuel ashes or a combination thereof is added. The inventors have surprisingly found that when the additive is added to the solid biomass fuel, the additive can improve the coking characteristics of the solid biomass fuel. Surprisingly, we have found that the above additives can reduce the tendency of solid biomass fuels to deposit coke (i.e., combustible solid and / or liquid organic deposits) on the surfaces of the combustion chamber and the pipes connected thereto during combustion. In addition, advantageously, it has been found that the additive can inhibit the secondary combustion of coke deposits, which means a reduction in the emissions of harmful polluting gaseous secondary combustion products of coke.

[0010] Surprisingly, it has been found that the additives discussed above can improve the coking characteristics of solid biomass fuels derived from various different types of biomass. This is surprising considering the chemical differences between the solid fuels produced from different types of biomass.

[0011] However, it has been found that the use of the additives discussed above as anti-coking additives is particularly effective for certain types of non-woody biomass (as opposed to woody biomass sources, such as those disclosed in WO2016 / 056608, WO2017 / 175733 and WO2019 / 069849). Without being bound by theory, it is believed that this is because certain non-woody biomass can be more effectively ground and pulverized by conventional techniques known in the art, resulting in pulverized biomass particles with a smaller particle size distribution (as detailed in, for example, WO2020 / 229824, WO2021 / 014151, WO2021 / 024001 and WO2021 / 156628). It has been found that the smaller the particle size distribution of the pulverized biomass, the more uniformly the above anti-coking additive can be incorporated into the solid biomass fuel. The inventors have surprisingly found that this can improve the coking characteristics of the solid biomass fuel to a greater extent compared to biomass fuels that form a larger particle size distribution during pulverization (such as solid fuels derived from woody biomass sources).

[0012] A first aspect of the present invention provides 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, jute plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweeds, Calliandra Calothyrsus, Acacia Mangium, Albizia Chinensis, Hevea Brasiliensis, grasses or any combination thereof; wherein the solid biomass fuel further includes one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes or a combination thereof.

[0013] Compared with a similar solid biomass fuel that is the same as the fuel of the present invention but does not include one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes or a combination thereof, this solid biomass fuel has improved coking characteristics.

[0014] Preferably, the one or more biomass sources include straw, palm-derived materials, nut shells, jute plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweeds, Calliandra Calothyrsus, Acacia Mangium, Albizia Chinensis, Hevea Brasiliensis, grasses or any combination thereof, and their content is at least 50% by weight, preferably at least 75%, more preferably at least 90%.

[0015] More preferably, the one or more biomass sources consist essentially of straw, palm-derived materials, nut shells, jute plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweeds, Calliandra Calothyrsus, Acacia Mangium, Albizia Chinensis, Hevea Brasiliensis, grasses or any combination thereof.

[0016] In some cases, the one or more biomass sources include straw or consist essentially of straw; wherein the straw is selected from rice straw, tobacco straw, sesame straw, pepper straw, eggplant straw, cotton straw, sorghum straw, sunflower straw, wheat straw, corn straw, rapeseed straw, cassava straw, bean straw or any combination thereof.

[0017] In some cases, the one or more biomass sources include palm-derived materials or consist essentially of palm-derived materials; wherein the palm-derived materials are selected from palm trunks, palm leaves, empty fruit bunches (EFB), palm kernel shells (PKS), palm oil press cakes, palm outer skins, palm shells, palm fibers or any combination thereof.

[0018] In some cases, the one or more biomass sources include nut shells 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, pinecone shells or any combination thereof.

[0019] In some cases, one or more biomass sources include or consist essentially of hemp plants; wherein the hemp plants are selected from ramie, jute, green jute, flax, apocynum, hibiscus or any combination thereof.

[0020] In some cases, one or more biomass sources include or consist essentially of bamboo; wherein the bamboo is selected from phyllostachys edulis, dendrocalamus latiflorus, fargesia spathacea or any combination thereof.

[0021] In some cases, one or more biomass sources include or consist essentially of fruit shells; wherein the fruit shells are selected from coconut shells, litchi shells, longan shells, salak shells, mangosteen shells, durian shells or any combination thereof.

[0022] In some cases, one or more biomass sources include or consist essentially of crop residues; wherein the crop residues are selected from wheat husks, bagasse, soybean dregs, peanut dregs, cassava dregs, sweet potato dregs, coffee bean dregs or any combination thereof.

[0023] In some cases, one or more biomass sources include or consist essentially of grass; wherein the grass is selected from the genus pennisetum, such as pennisetum hydridum.

[0024] Typically, the content of the material derived from one or more biomass sources in the solid biomass fuel is at least 80% by weight. Preferably, the content of the material derived from one or more biomass sources in the solid biomass fuel is at least 90% by weight. More preferably, the content of the material derived from one or more biomass sources in the solid biomass fuel is at least 95% by weight.

[0025] Typically, when the solid biomass fuel includes one or more aluminosilicate clays, the one or more aluminosilicate clays include kaolin.

[0026] Typically, when the solid biomass fuel includes one or more aluminosilicates, the one or more aluminosilicates include one or more aluminosilicate minerals, one or more zeolites, one or more feldspars, one or more aluminosilicate glasses or any combination thereof.

[0027] One or more aluminosilicate minerals can include any suitable minerals, such as andalusite, kyanite, sillimanite or combinations thereof.

[0028] One or more aluminosilicate glasses can include any suitable aluminosilicate glasses, such as alkali metal or alkaline earth metal aluminosilicate glasses.

[0029] 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 from 0.1% to 10% by weight of the solid biomass fuel, such as from 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 from 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 from 0.1% to 0.8% by weight of the solid biomass fuel; and most preferably from 0.5% to 0.8% by weight of the solid biomass fuel.

[0030] Preferably, the solid biomass fuel comprises: one or more aluminosilicate clays in an amount of from 0.3% to 0.5% by weight of the solid biomass fuel; one or more aluminosilicates in an amount of from 0.1% to 0.2% by weight of the solid biomass fuel; and one or more pulverized fuel ashes in an amount of from 0.1% to 0.2% by weight of the solid biomass fuel. Preferably, the one or more aluminosilicate clays include kaolin.

[0031] Preferably, the one or more aluminosilicate clays, one or more aluminosilicates, one or more pulverized fuel ashes or combinations thereof and the material derived from the biomass source are uniformly dispersed in the solid biomass fuel.

[0032] Typically, the bulk density of the solid biomass fuel determined according to 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 kg / l to 0.70 kg / l.

[0033] Typically, the mechanical durability of the solid biomass fuel determined according to DIN EN 15210-1 is 97% or higher.

[0034] Typically, (i) the total dry sulfur content of the solid biomass fuel is 0.5% or less by weight, preferably 0.45% or less, most preferably 0.40% or less, wherein the total dry sulfur content is determined according to DIN EN 15289.

[0035] Typically, (ii) the total dry hydrogen content of the solid biomass fuel is 3% or more by weight, preferably from 5% to 10%, more preferably from 5% to 7%, wherein the total dry hydrogen content is determined according to DIN EN 15104.

[0036] Typically, (iii) the total dry oxygen content of the solid biomass fuel is 20% or higher by weight, preferably 25% to 42%, more preferably 28% to 40%, wherein the total dry oxygen content is determined according to DIN EN 15296.

[0037] Typically, (iv) the total dry carbon content of the solid biomass fuel is 40% or higher by weight, preferably 45% to 65%, more preferably 50% to 60%, wherein the total dry carbon content is determined according to DIN EN 15104.

[0038] Typically, (v) the total dry nitrogen content of the solid biomass fuel is less than 5.0% by weight, preferably less than 3.0%, more preferably less than 2.5%, wherein the total dry nitrogen content is determined according to DIN EN 15104.

[0039] The solid biomass fuel can generally be defined as any one or more of (i) to (v) above. Preferably, the solid biomass fuel is defined as any three or more of (i) to (v) above. More preferably, the solid biomass fuel is defined as all of the above options (i) to (v).

[0040] Typically, (vi) the chemical oxygen demand (COD) of the solid biomass fuel when immersed in water is 5000 ppm or lower, preferably 4000 ppm or lower, most preferably 3200 ppm or lower, wherein the chemical oxygen demand is determined according to GB / 11914-89.

[0041] Typically, (vii) the fixed carbon content of the solid biomass fuel is 20% or higher by weight, preferably 25% to 45%, wherein the fixed carbon content is determined according to DIN EN 51734.

[0042] Typically, (viii) the ash content of the solid biomass fuel is less than 20% by weight, preferably less than 18%, wherein the ash content is determined according to EN 14775 at 550 °C.

[0043] Typically, (ix) the volatile matter content of the solid biomass fuel is 35% to 80% by weight, more preferably 40% to 75%, wherein the volatile matter content is determined according to DIN EN 15148.

[0044] Typically, (x) the internal moisture content of the solid biomass fuel is less than 8% by weight, preferably less than 6%, more preferably less than 5%, wherein the internal moisture content is determined according to DIN EN 14774.

[0045] Solid biomass fuels can generally be defined as any one or more of the above (vi) to (x). Preferably, the solid biomass fuel is defined as any three or more of the above (vi) to (x). More preferably, the solid biomass fuel is defined as all of the above options (vi) to (x).

[0046] Typically, the calorific value of the solid biomass fuel is 4300 kcal / kg to 6750 kcal / kg, where the calorific value is determined according to DIN EN 14918.

[0047] Typically, the basic moisture content of the solid biomass fuel is less than 10% by weight, preferably less than 8%, and most preferably less than 6%, where the basic moisture content is determined according to GB / T 211-2017.

[0048] Typically, the pH value of the solid biomass fuel is 4 to 10.

[0049] Typically, the solid biomass fuel has a waterproof time of up to 20 days, preferably up to 30 days, and more preferably up to 40 days.

[0050] Typically, the PM1.0 emission during the combustion of the solid biomass fuel is less than 175 mg / kg, preferably less than 150 mg / kg.

[0051] Typically, the coking characteristic value during the combustion of the solid biomass fuel is less than or equal to 1.5, preferably 0.3 to 1.5, where the coking characteristic value is determined according to GB / T 8727-2008.

[0052] Typically, the solid biomass fuel is obtained or can be obtained by the method according to the fourth aspect of the present invention, as discussed in further detail below.

[0053] The second aspect of the present invention provides a method for burning the solid biomass fuel according to the first aspect of the present invention.

[0054] Typically, the solid biomass fuel is co-fired and burned with fossil fuels such as coal.

[0055] Typically, the PM1.0 emission of this method is less than 175 mg / kg, preferably less than 150 mg / kg.

[0056] The third aspect of the present invention provides the use of one or more aluminosilicate clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof as an anti-coking additive in solid biomass fuels.

[0057] Preferably, the use includes using an anti-coking additive to reduce or prevent the formation of deposits of solid and / or liquid combustible organic materials during the combustion of solid biomass fuels. More preferably, the deposits of solid and / or liquid combustible organic materials are deposited on the surface of a combustion chamber for burning solid biomass fuels and / or on the surface of a pipe in fluid communication therewith.

[0058] Preferably, the use includes using an anti-coking additive to prevent or reduce the secondary combustion of deposits of solid and / or liquid combustible organic materials.

[0059] Typically, the solid and / or liquid combustible organic materials include soot, tar, or a combination thereof.

[0060] Typically, the solid biomass fuel is derived from one or more biomass sources; wherein the one or more biomass sources include straw, palm-derived materials, nut shells, ramie plants, bamboo, corncobs, rice husks, fruit shells, residues, seaweeds, Acacia farnesiana, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grasses, or any combination thereof.

[0061] Preferably, the solid biomass fuel, the biomass source, one or more aluminosilicate clays, one or more aluminosilicates, and / or one or more pulverized fuel ashes are as described above in the context of the first aspect of the present invention.

[0062] The fourth aspect of the present invention provides a method for preparing a solid biomass fuel according to the first aspect of the present invention, wherein the method comprises the following steps: (i) providing a biomass composition comprising biomass particles having an average particle size (D 50 ) of 1000 μm to 75000 μm; (ii) pulverizing the biomass composition to obtain a pulverized biomass powder having an average particle size (D 50 ) of 500 μm to 10000 μm; (iii) drying the pulverized biomass powder to obtain a dried pulverized biomass powder; (iv) shaping the dried pulverized biomass powder to obtain a shaped biomass product; wherein the dried pulverized biomass powder is shaped together with one or more aluminosilicate clays, one or more aluminosilicates, pulverized fuel ash, or a combination thereof to obtain a shaped biomass product; (v) heating the shaped biomass product to 110°C to 500°C for 0.2 to 6 hours to obtain a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel.

[0063] Typically, the biomass composition includes one or more biomass sources, which include straw, palm-derived materials, nut shells, ramie, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweeds, Acacia glauca, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof. Preferably, the one or more biomass sources are as described above in the context of the first aspect of the present invention.

[0064] Preferably, the solid biomass fuel, the biomass source, one or more aluminosilicate-containing clays, one or more aluminosilicates, and / or one or more pulverized fuel ashes are as described above in the context of the first aspect of the present invention.

[0065] Typically, adjusting the forming step such that the density of the formed biomass product is controlled includes: controlling the compression ratio of the mold used in the forming step. Typically, the step (iv) of forming the dry pulverized biomass powder to obtain the formed biomass product includes: forming the dry pulverized biomass powder with a compression mold having a compression ratio of less than 6, for example, a compression ratio of less than 5. Preferably, the step (iv) of forming the dry pulverized biomass powder to obtain the formed biomass product includes: forming the pulverized biomass powder with a compression mold having a compression ratio of less than or equal to 3.5, more preferably a compression ratio of less than or equal to 3, and most preferably a compression ratio of 1 to 3.

[0066] Typically, one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof are formed together with the dry pulverized biomass powder at a certain mass ratio to obtain a solid biomass fuel, and the total amount of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof in the solid biomass fuel is 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; more preferably 0.1% to 0.8% by weight of the solid biomass fuel; most preferably 0.5% to 0.8% by weight of the solid biomass fuel.

[0067] In a highly preferred embodiment, one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof are formed together with the dry pulverized biomass powder at a certain mass ratio to obtain a solid biomass fuel, wherein the content of one or more aluminosilicate-containing clays in the solid biomass fuel is 0.3% to 0.5% by weight of the solid biomass fuel, the total amount of one or more aluminosilicates is 0.1% to 0.2% by weight of the solid biomass fuel, and the content of one or more pulverized fuel ashes is 0.1% to 0.2% by weight of the solid biomass fuel. Description of the Drawings

[0068] Figure 1 It is a photograph of a device known in the art that can be used to shred one or more biomass sources.

[0069] Figure 2 It is a schematic diagram of a typical compression mold that can be used according to the present invention, showing the compression ratio used in the molding step.

[0070] Figure 3 It is the coking characteristic value of various biomass fuels of the present invention determined according to GB / T212 - 2008.

[0071] Figure 4 It is the coking characteristic value of various comparative biomass fuels without adding anti - coking additives determined according to GB / T212 - 2008. Detailed implementation mode

[0072] biomass source

[0073] The present invention can use any plant - derived biomass source. Preferably, one or more biomass sources from which the solid biomass fuel is derived are as described above.

[0074] Preferably, one or more biomass sources include non - woody biomass sources. As described above, surprisingly, the additives used in the present invention can more effectively impart anti - coking properties to solid biomass fuels derived from non - woody biomass sources. It is believed that this is because the additives are incorporated into the solid biomass fuel more uniformly than into woody biomass fuels. Surprisingly, this can greatly improve the coking characteristics of the solid biomass fuel. In other words, although the anti - coking additives used in the present invention are still effective when used with woody biomass sources, the improvement in the coking characteristics of the fuel after adding the additives is smaller compared to fuels from non - woody biomass sources.

[0075] The terms "wood", "woody biomass" or "woody - like biomass" used herein generally refer to a hard fibrous material mainly composed of xylem, which constitutes most of the stems, branches and roots of trees or shrubs under the bark. Wood is only present in herbaceous plants to a limited extent. This definition of the term "wood" is consistent with the definition commonly understood in the art.

[0076] Preferably, one or more biomass sources from which the solid biomass fuel is derived include less than 50% by weight of woody biomass, more preferably less than 20%, and most preferably less than 10%.

[0077] Preferably, as described above, one or more biomass sources include: straw, palm-derived materials, nut shells, hemp plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweed, Albizia julibrissin, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof. Different from woody biomass sources, these biomass sources can be planted and harvested on a commercial scale, and the quality and specific characteristics of the biomass sources can be better controlled compared to woody materials. Using the above biomass sources can also avoid environmental damage caused by using trees, such as deforestation. Compared with woody materials, these biomass sources are also easier to grind, thereby reducing the cost of the grinding process. When using these materials, a more uniform mixture of particle sizes can also be provided by grinding, thus providing better uniformity for the final solid biomass fuel product.

[0078] More preferably, one or more biomass sources include rice straw, tobacco straw, pepper straw, eggplant straw, cassava straw, soybean straw, chickpea straw, soyabean straw, palm leaves, cashew nut shells, chestnut shells, pistachio nut shells, sunflower seed shells, walnut shells, pine nut shells, hemp plants, Phyllostachys edulis, Dendrocalamus latiflorus, Fargesia spathacea, litchi shells, cinnamon (longan) shells, salak shells, mangosteen shells, durian shells, bean dregs, peanut dregs, cassava dregs, sweet potato dregs, coffee bean dregs, or a combination thereof. More preferably, one or more biomass sources include 80% to 100% by weight of these materials. Most preferably, one or more biomass sources consist essentially of the above materials. Using these materials is particularly preferred because these materials can all provide solid biomass fuels with a surprisingly high mechanical durability of over 97%. When forming solid biomass fuel pellets, this can be achieved even when using a lower compression ratio of less than 3.6. Generally, when using other biomass sources, a higher compression ratio is required to obtain solid fuels with high mechanical durability (discussed in detail below). If possible, it is preferred to use a lower compression ratio because it can provide a higher biomass fuel yield when forming the fuel into pellets. It is very advantageous for solid biomass fuels to have a high mechanical durability of over 97% because fuels with high durability can be stored outdoors for up to two months without being damaged and are not damaged by rainfall and other adverse weather conditions. High mechanical durability is also desirable because durable fuels are less likely to decompose, break, or form dust during processing, transportation, or storage.

[0079] The biomass sources used according to the present invention can be agricultural wastes generated as by-products of agricultural operations. Alternatively, these biomass sources can be specifically grown for use as raw materials for preparing biomass solid fuels. Each of the one or more biomass sources discussed above can be obtained or harvested by conventional methods known in the art. Many of the above-mentioned biomass sources used according to the present invention can be agricultural wastes. The term "agricultural waste" as used herein generally refers to plant-based waste generated as a by-product of agricultural operations. For example, agricultural waste may include plant products remaining after harvesting, or unwanted components in harvested plant products.

[0080] The term "comprising" as used herein is used to indicate that any further undefined components may be present. The term "consisting of" as used herein is used to indicate that no other components can be present except those specifically listed. The term "consisting essentially of" as used herein means that other undefined components may be present, but these components do not materially affect the basic properties of the composition.

[0081] anti-coking additive

[0082] The solid biomass fuel of the present disclosure includes at least one anti-caking additive. The at least one anti-caking additive can include one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or combinations thereof.

[0083] 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 includes kaolin.

[0084] 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.

[0085] One or more aluminosilicate minerals can include any suitable minerals, such as andalusite, kyanite, sillimanite, or combinations thereof.

[0086] One or more aluminosilicate glasses can include any suitable aluminosilicate glasses, such as alkali metal or alkaline earth metal aluminosilicate glasses.

[0087] One or more pulverized fuel ashes can include any suitable known types of pulverized fuel ashes. For example, fly ash generated from coal combustion can be used. One or more pulverized fuel ashes typically include a mixture of silica, alumina, and calcium oxide, which are the main mineral compounds in coal-bearing strata.

[0088] The solid biomass fuel of the present disclosure may contain any suitable amount of the above additives to achieve an anti-coking effect. Preferably, the anti-coking additive is present in the amount described above. Surprisingly, it is effective when the anti-coking additive is included in the solid biomass fuel in a very low amount (e.g., an amount less than 1% of the weight of the solid biomass fuel). This is especially true when the solid biomass fuel is derived from the non-woody biomass discussed above. Without being limited by theory, it is believed that this is because the additive can be more effectively and uniformly dispersed in the solid biomass fuel, where the fuel is derived from the preferred non-woody biomass as discussed in more detail above.

[0089] Therefore, it is preferred that one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof are substantially uniformly dispersed in the solid biomass fuel with the biomass-derived material. More preferably, one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof are uniformly dispersed in the solid biomass fuel with the biomass-derived material. The inventors have found that this uniform dispersion of the additive enhances the anti-coking effect of the additive and the above advantages.

[0090] In a highly preferred case, the solid biomass fuel comprises: one or more aluminosilicate-containing clays in a total amount of 0.3% to 0.5% of the weight of the solid biomass fuel; one or more aluminosilicates in a total amount of 0.1% to 0.2% of the weight of the solid biomass fuel; and one or more pulverized fuel ashes in an amount of 0.1% to 0.2% of the weight of the solid biomass fuel.

[0091] As used herein, the term "anti-coking additive" refers to an additive that imparts an anti-coking effect to the solid biomass fuel during combustion. As used herein, the term "anti-coking effect" refers to the ability of the additive to reduce or eliminate the tendency of the solid biomass fuel to form coke during combustion. As used herein, the term "coke" refers to a liquid or solid deposit containing combustible organic materials that deposits on the surface of the combustion chamber or pipes and other chambers communicating therewith during the combustion of the solid biomass fuel. Preferably, the combustible organic materials include carbon, hydrocarbons, oxygenated hydrocarbons, or any combination thereof. The deposit is preferably solid. Solid coke may be referred to as soot, and liquid coke may be referred to as tar. Coke deposits are different from ash deposits because coke involves combustible organic substances formed by incomplete combustion of the solid biomass fuel. In contrast, ash refers to the non-combustible inorganic residue formed after complete combustion of the solid biomass fuel. As described above, the factors affecting ash-related operational problems and coking during the combustion of solid biomass fuel are different. The mechanism of coke formation during combustion is different from ash-related operational problems such as slag formation and slag fouling.

[0092] In addition to preventing coke deposition on the inner surfaces of the combustion chamber, ducts, and other chambers associated therewith, the anti-coking additives discussed above also reduce the tendency of the deposited coke to undergo secondary combustion, thereby reducing the tendency of gaseous pollutant secondary combustion products, which are typically formed and emitted in the flue gas. This is a secondary effect in addition to the primary effect of reducing coke deposition. In other words, the formation of secondary combustion products is reduced because the additives first reduce coke deposition and also because they reduce the tendency of the deposited coke to undergo secondary combustion to form pollutant gases.

[0093] solid biomass fuel

[0094] Solid biomass fuel products can have any of the physical properties discussed above.

[0095] The solid biomass fuel of the present disclosure preferably comprises pellets. The pellets can be of any suitable size. Preferably, the diameter of the pellets is from 3 mm to 100 mm, more preferably from 5 mm to 8 mm. Preferably, the length of the pellets is from 20 mm to 60 mm, more preferably from 30 mm to 50 mm.

[0096] The biomass fuel of the present invention is sufficiently water-proof for up to 20 days, preferably 30 days, more preferably 40 days. The water-proof performance of the solid biomass fuel is determined according to the standard test of the Energy Research Centre of the Netherlands (ECN).

[0097] The moisture content of the solid biomass fuel of the present invention can also be determined by the standard test method of the ECN. The moisture content of the solid biomass fuel of the present invention is generally less than 8% by weight, preferably less than 6% by weight, more preferably less than 5% by weight, wherein the internal moisture content is determined according to DIN EN 14774.

[0098] The basic moisture content of the biomass solid fuel is generally 10% or less by weight, preferably 8% or less by weight, most preferably 6% or less by weight, wherein the basic moisture content is determined according to GB / T211-2017.

[0099] Typically, in addition to additives such as the anti-coking additives discussed above, the solid biomass fuel does not contain any other fuel source. Thus, the solid biomass fuel typically contains only biomass-derived materials as the fuel source in the solid biomass fuel. For example, when forming heated biomass products into pellets, generally no other fuel source is added to the biomass source before forming, such that the solid biomass fuel pellets contain only biomass-derived fuel sources.

[0100] Preferably, the solid biomass fuel comprises at least 50% by weight of the total fuel components of the fuel of biomass-derived materials, such as at least 60%, at least 70%, at least 80%, at least 90%, preferably at least 95%.

[0101] The solid biomass fuel preferably contains at least 75% by weight of biomass-derived materials, preferably at least 80%, more preferably at least 90%.

[0102] method for preparing solid biomass fuel

[0103] Preferably, the method for preparing the solid biomass fuel includes a method of crushing, forming and then baking one or more biomass sources; or a method of crushing, baking and then forming. The anti-caking additive is usually added in the biomass forming step. Highly preferably, the anti-caking additive is effectively dispersed within the solid biomass fuel such that the additive is substantially uniformly dispersed within the fuel.

[0104] Preferably, the solid biomass fuel is obtained by a method for producing a solid biomass fuel, wherein the method comprises the following steps: (i) providing a biomass composition comprising biomass particles having an average particle size (D 50 ) of 1000 μm to 75000 μm; (ii) crushing the biomass composition to obtain a crushed biomass powder having an average particle size (D 50 ) of 500 μm to 10000 μm; (iii) drying the crushed biomass powder to obtain a dried crushed biomass powder; (iv) forming the dried crushed biomass powder to obtain a formed biomass product; wherein the dried crushed biomass powder is formed together with one or more aluminosilicate clays, one or more aluminosilicates, crushed fuel ash or a combination thereof to obtain a formed biomass product; (v) heating the formed biomass product to 110°C to 500°C for 0.2 to 6 hours to obtain a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel.

[0105] Each step will be discussed further below.

[0106] Providing the biomass composition

[0107] The method may include step (i) of providing a biomass composition comprising biomass particles having an average particle size (D 50 ) of 1000 μm to 75000 μm. Preferably, the biomass composition comprises biomass particles having an average particle size (D 50 ) of 1000 μm to 60000 μm. For example, in some cases, the biomass composition comprises biomass particles having an average particle size (D 50) Biomass particles with a size ranging from 30,000 μm to 60,000 μm, such as biomass particles with an average particle size ranging from 40,000 μm to 50,000 μm.

[0108] By introducing one or more biomass sources into a conventional chopping device, the biomass composition can be provided as particles with sizes within the above ranges, although this of course depends on the specific biomass source. For example, if the biomass source occurs naturally and the particle size is within the above ranges, no chopping is required. Thus, the method of the present invention may include chopping one or more biomass sources to provide a biomass composition comprising biomass particles with an average particle size (D 50 ) ranging from 1,000 μm to 75,000 μm or any other size range as described above.

[0109] The step of providing a biomass composition with an average particle size (D 50 ) ranging from 1,000 μm to 75,000 μm may include harvesting one or more biomass sources using a conventional combine harvester. The combining process includes chopping and breaking down one or more biomass sources into particles of the desired size.

[0110] The step of providing the biomass composition may further include reducing the moisture content (by weight) of the biomass to less than 50%. Such a step may include compressing the biomass composition. Typically, this compression step squeezes out moisture from the biomass composition such that the moisture weight content of the biomass composition is reduced to less than 50%. Thus, in certain cases, the step of providing a biomass composition with the above particle sizes includes compressing a biomass composition with a moisture weight content greater than 70% such that after compression, the moisture weight content of the biomass composition is less than 50%.

[0111] The step of providing a biomass composition with the above particle sizes includes a step of compressing the biomass and a step of chopping the biomass.

[0112] The chopping step and the compression step (if included) can be carried out using separate equipment. Alternatively, these steps can be carried out in a single device configured for chopping and compressing biomass. For example, a motorized rolling device suitable for compressing biomass can be placed on a conveyor belt feeding a conventional chopping device. In this regard, the biomass source is compressed before entering the chopping device. Devices suitable for carrying out the compression and chopping steps on one or more biomass sources are known in the art.

[0113] Figure 1 Examples of devices for chopping are shown. As Figure 1The typical working principle of the shredder device shown is that the material enters the shredder device through a conveying system (such as a conveyor belt), and the conveyor belt feeds the material through the feed port. The material is then shredded into pieces by a high-speed rotating blade (not shown) and a blade (not shown) mounted on the base of the machine. The function of the mechanism and similar shredder mechanisms are known to those skilled in the art.

[0114] Biomass pulverization

[0115] Step (ii) may include pulverizing the biomass composition to obtain an average particle size (D 50 ) is a pulverized biomass powder of 500 μm to 10000 μm.

[0116] The biomass composition can be pulverized into biomass powder by standard techniques known in the art. The biomass composition can be pulverized so that the biomass powder has an average particle size (D) of 500 μm to 10000 μm. 50 ). Preferably, the biomass composition is pulverized to have an average particle size of 1000 μm to 8000 μm, more preferably 1000 to 5000 μm. As described above, it has been found that pulverizing a non-woody biomass source (such as the specific biomass source described above) can provide a biomass powder having a smaller particle size distribution than pulverizing an existing known woody biomass source.

[0117] We have also found that the smaller the particle size distribution of the pulverized biomass powder, the better the quality and performance characteristics of the solid biomass fuel product. Without being limited by theory, this is due to better uniformity and homogeneity of the final solid biomass fuel product. It is believed that the smaller particle size, better uniformity and homogeneity of the powder of the final fuel product is related to the improvement of the performance characteristics of the fuel when burned, and is also related to the improvement of the water resistance characteristics of the solid fuel product.

[0118] As mentioned above, higher uniformity also means that the anti-coking additive is more effectively and evenly dispersed in the solid biomass fuel, which means that better anti-coking performance can be provided and more effective anti-coking performance can be provided at lower additive concentrations.

[0119] Prior to comminution, biomass compositions typically contain less than 50% moisture by weight.

[0120] For different biomass sources with different moisture contents, different comminution processes are preferably used. For example, when the moisture content of the biomass composition is below 20% by weight, preferably, the step of comminuting the biomass includes using a negative pressure pneumatic conveying device. Such negative pressure pneumatic conveying devices are known in the art.

[0121] When the moisture weight content of the biomass composition is 20% or more, the biomass composition can be directly pulverized without using a negative pressure pneumatic conveying device.

[0122] Techniques known to those skilled in the art can be used to determine the average particle size (D 50 ) of the biomass particles relevant in steps (i) and (ii) of the methods disclosed herein. For example, standard tests ISO 17827-1 and / or ISO 17827-2 can be used to calculate D 50 of the biomass particles.

[0123] Drying of the pulverized biomass powder

[0124] The biomass can be dried in step (iii) of the method. The step (iii) of drying the pulverized biomass powder to obtain a dried pulverized biomass powder typically includes drying the pulverized biomass powder to obtain a dried pulverized biomass powder having a moisture content by weight of 10% to 18%, preferably 12% to 15%. However, it should be understood that the moisture content of the dried pulverized biomass powder is not necessarily within this range.

[0125] The step of drying the biomass powder can also include mixing the pulverized biomass powder. If one biomass source is used in the method, the single biomass source can be mixed. Alternatively, if multiple biomass sources are used in the method, the drying step can include mixing the pulverized biomass powder with one or more additional biomass sources. For example, when the solid biomass fuel is formed from at least two biomass sources, although two or more biomass sources can be mixed during any step of the methods disclosed herein, it is preferred to mix the biomass sources during the drying step of the methods disclosed herein. Thus, the pulverized biomass powder can be mixed with an additional biomass source, which is also a pulverized biomass powder prepared using the process steps described herein. Or, one or more additional biomass sources mixed with the pulverized biomass powder in the drying step are not processed as described herein. For example, the pulverized biomass powder prepared as described herein can be mixed with one or more additional biomass sources prepared in a different manner.

[0126] An anti-coking additive can also be mixed with the biomass-derived material at this stage of the method.

[0127] The pulverized biomass powder can be dried using any suitable method, such as using a standard drying cylinder known in the art. For example, the drying step can be carried out in a drying device including a rotary drying cylinder. The pulverized biomass powder can be mixed with the above one or more additional biomass sources by the rotation of the rotary drying cylinder. Typically, the rotary drying cylinder includes lifting plates. The lifting plates continuously lift the material while the drying cylinder rotates.

[0128] When the moisture weight content of the pulverized biomass powder is less than 20%, typically, the pulverized biomass powder is dried in a single drying cylinder. Thus, in these cases, the method of the present disclosure includes drying the pulverized biomass powder in only a single drying cylinder.

[0129] When the moisture weight content of the pulverized biomass powder is greater than 20%, typically, the pulverized biomass powder is dried in multiple drying cylinders. Thus, in these cases, the method of the present disclosure includes drying the pulverized biomass powder in multiple drying cylinders. For example, the method may include drying the pulverized biomass powder in more than two, more than three, more than four, or more than five drying cylinders.

[0130] Shaping of the dried biomass powder

[0131] The dried pulverized biomass powder can be shaped to provide a shaped biomass product. The shaping step can be carried out in any shaping equipment known in the art and according to biomass shaping techniques known in the art, and may include an extrusion system. Preferably, the shaping step is carried out in a compression mold. Preferably, the compression mold includes a die product outlet hole. The equipment described in CN105435708 can be used to carry out the shaping step.

[0132] Preferably, the shaping step includes shaping the dried pulverized biomass powder into pellets. Thus, preferably, the shaped biomass product and the solid biomass fuel product include biomass pellets.

[0133] It has been found that adjusting the shaping step such that the density of the shaped biomass product produced by the step is controlled within a certain range confers certain favorable properties on the final solid biomass fuel product. Specifically, it has been found that controlling the shaping step such that the density of the shaped biomass product is in the range of 1.0 to 1.35 kg / L can confer favorable properties on the final biomass fuel product. Preferably, the shaping step is controlled such that the density of the shaped biomass product is 1.0 kg / L to 1.35 kg / L. Typically, the above density is determined according to NY / T 1881.7 - 2010. Thus, preferably, the shaping step is controlled such that the density of the shaped biomass product is 1.0 kg / L to 1.35 kg / L, where the density is determined according to NY / T 1881.7 - 2010.

[0134] The shaping step can be controlled in a variety of ways. In cases where the shaping process includes using a compression mold, the density is typically controlled by using a compression ratio less than 8 (such as less than 7, less than 6, less than 5, or less than 4). Preferably, a compression ratio less than or equal to 3.5 is employed, more preferably a compression ratio less than or equal to 3 is employed, and most preferably a compression ratio of 1 to 3 is employed.

[0135] The present inventors have found that these compression ratios are preferred for the shaping of the comminuted biomass with the anti-coking additive of the present invention.

[0136] The compression ratio of a compression die having a die product outlet hole can be defined as the ratio of the length to the diameter of the die product outlet hole. Figure 2 An example of a compression die that can be used according to the present invention is shown. The dry comminuted biomass powder is inserted into the interior of the die and then extruded from the interior of the die by pressure so as to be discharged from the shaped product outlet hole in the figure. The compression ratio shown in the figure is the ratio of the length of the product outlet hole to its diameter.

[0137] Generally, the smaller the compression ratio, the lower the density of the shaped biomass product. A higher density of the shaped biomass product is desired, for example within the above range, because the inventors believe this is related to the high durability of the final solid biomass fuel product, while increasing the bulk density, improving the waterproofing ability and enhancing the uniformity of the solid fuel product. Therefore, in order to provide a final solid biomass fuel product with the desired properties, a higher compression ratio is generally required. However, the higher the compression ratio, the lower the yield of the shaped biomass product. Due to the higher pressure required for shaping the biomass, a higher compression ratio generally also increases the process cost. Therefore, a balance needs to be achieved between a compression ratio high enough to provide the desired fuel properties and a compression ratio not too high that results in a reduction in process yield or an increase in process cost. It has been found that when the anti-coking additive of the present disclosure is included in the solid biomass fuel composition, the above-discussed compression ratios are preferred to provide a balance between process yield and the desired solid fuel properties.

[0138] Preferably, before step (iv) of shaping the dry comminuted biomass powder, a shaping additive is added to the dry comminuted biomass powder. The additive is considered to improve the shaping process and increase the yield of the shaped biomass product produced in the shaping step. Suitable shaping additives are known in the art and include, but are not limited to, starch or starch derivatives.

[0139] Generally, in addition to the shaping additives discussed above, no other fuel source is added to the dry comminuted biomass powder during the shaping step. Therefore, the shaped biomass product of the shaping step generally contains only biomass-derived materials as the fuel source in the solid biomass fuel. For example, when shaping dry comminuted biomass powder into pellets, generally no other fuel source is added to the dry comminuted biomass product before shaping, such that the solid biomass fuel pellets obtained at the end of the process contain only biomass-derived fuel sources. Preferably, the solid biomass fuel thus comprises at least 50%, such as at least 60%, at least 70%, at least 80%, at least 90%, preferably at least 95% of biomass-derived materials by weight of the total fuel components of the fuel.

[0140] As used herein, the term "total fuel content of solid fuel" refers to the components of solid fuel that are combustible materials, such as biomass-derived materials and coal. The term fuel content in relation to solid fuel is not intended to include additives that may be present in solid fuel particles and that do not themselves burn to produce energy.

[0141] It has been found that the forming step can improve the water resistance of the final solid biomass fuel product. The increase in density during the forming step means that water is more difficult to penetrate into the denser formed biomass product particles.

[0142] In addition, as the density of the product increases, more biomass will be concentrated inside the formed product and thus will not be in direct contact with water.

[0143] One or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes or combinations thereof, and dried pulverized biomass powder are formed together by mass ratio to provide a solid biomass fuel containing a desired amount of anti-caking additive.

[0144] As described above, the anti-caking additive is preferably added to the biomass particles before forming and mixed with the biomass particles in as uniform a manner as possible before forming.

[0145] Heating of the formed biomass product

[0146] The formed biomass product can be heated to produce a solid biomass fuel. The heating temperature is from 110 °C to 500 °C, and the heating time is from 0.2 to 6 hours. Preferably, the step of heating the formed biomass product is carried out for 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 heating to a temperature of 220 °C to 320 °C.

[0147] Preferably, the step (v) of heating the formed biomass product includes heating the formed biomass product under certain conditions to bake the formed biomass product. Baking is a mild pyrolysis process in which the heating is carried out in a low oxygen atmosphere (such as an oxygen content of less than 10%). Suitable conditions and processes for baking are known in the art. Therefore, preferably, the step (v) of heating the formed biomass product includes baking.

[0148] The heating step can be carried out in any suitable equipment known in the art for heating the formed biomass product. For example, the heating step can be carried out under the equipment and process conditions disclosed in EP3287509A1.

[0149] Preferably, step (v) of heating and forming the biomass product is adjusted to control the uniformity of the solid biomass fuel. Optionally, adjusting step (v) to control the uniformity of the solid biomass product includes: performing step (v) in a device in which the formed biomass product rotates while being heated. Optionally, adjusting step (v) to control the uniformity of the solid biomass product includes: controlling the rotation speed or rotation direction of the solid biomass product; optionally, the formed biomass product rotates in the counterclockwise and clockwise directions in the device. The uniformity of the solid biomass fuel can also be optimized by the above heating temperature and duration.

[0150] 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 step of cooling after the step of heating the biomass, the cooling step may include rotating the solid biomass fuel. The biomass can be rotated in a suitable device, such as the device disclosed in EP3287509A1. Preferably, both the heating step (v) and the step of cooling the biomass include rotating the biomass. When the biomass is rotated during the cooling step or the heating step, the biomass can be rotated in different directions, such as clockwise and counterclockwise in a continuous cycle.

[0151] The term "uniformity" of the solid biomass product refers to that each particle of the solid biomass fuel product or the formed biomass product and multiple particles in a bulk sample of the solid biomass fuel product or the formed biomass product have constant or similar properties. Such as, but not limited to, the density of the particles, the flammability of the particles, the chemical composition of the particles, and the water resistance of the particles. Uniformity is a highly desirable property for biomass fuels used in combustion methods.

[0152] The inventors also found that controlling the heating step in the above manner also helps to obtain a solid biomass fuel product with enhanced waterproof performance. During the heating step, the water-absorbing hydrophilic compounds present in the biomass powder are degraded. In addition, the heating step causes the oil present in the biomass powder to migrate to the outside of the biomass powder particles, increasing the hydrophobicity of the particles.

[0153] Removal of dust particles from solid biomass fuel

[0154] 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 found that during the production process of solid biomass fuels known in the art, a large amount of dust adheres to the solid biomass fuel. This dust is problematic because it may pollute the air during the transportation and packaging of the solid biomass fuel. The dust may also pollute the local environment. In addition, when stored outdoors, the dust particles will form molds, affecting the performance and quality of the solid biomass fuel. Therefore, it is beneficial to remove the dust on the surface of the solid biomass fuel particles.

[0155] The present inventor has found that the dust on the surface of solid biomass fuel particles can be removed by generating friction between the particles. For example, friction can be induced by vibrating or rotating the solid biomass fuel particles to remove the dust adhering to the particles. Therefore, step (vi) of removing the dust particles from the solid biomass fuel may include inducing friction between the solid biomass fuel particles. For example, step (vi) of removing the dust particles from the solid biomass fuel may include vibrating, rotating, rolling the particles, or any combination thereof. Suitable devices for rolling, 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 screen.

[0156] Step (vi) of removing the dust particles from the solid biomass fuel may include removing the dust particles from the solid biomass fuel using a sieve. Generally, the aperture of the sieve is 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. The dust particles mixed with the solid biomass fuel particles can be separated from the solid biomass fuel through the sieve. The larger solid biomass fuel particles cannot pass through the sieve and thus are separated from the dust particles. Suitable devices and methods for performing the screening step are known to those skilled in the art, and any suitable device can be used. For example, devices for screening, rolling, and rotating solid biomass fuel can be used to remove the dust particles from the solid biomass fuel. When using this device, the solid biomass fuel can be placed on the sieve, and the sieve is driven to roll and rotate around its axis by the operation of a motor. During the rolling / tilting and rotation of the sieve, the materials on the sieve surface are turned over. Some materials pass through the sieve and are separated from the materials that do not pass through the sieve. The rolling and rotation of the sieve cause the materials stuck in the pores of the sieve to fall, thus preventing the clogging of the pores of the sieve. Alternatively, a device for vibrating and screening solid biomass fuel particles can also be used. In this case, a motor can be used to vibrate the sieve to lift the materials on the sieve surface. This process may loosen the small particles adhering to the larger particles, and then they pass through the pores in the sieve. An example of a device that uses a sieve and vibration to separate larger particles from smaller particles is the device taught in CN201324717, where the smaller particles may or may not be attached to the larger particles.

[0157] Accordingly, the method of the present disclosure may include subjecting solid biomass fuel particles to one or more of rolling, rotation, and vibration to cause friction between the solid biomass fuel particles and remove dust particles adhered to the solid biomass fuel particles. Then, the method preferably includes subjecting the mixture of solid biomass fuel particles and dust particles to the sieving step as described above to remove the dust particles from the solid biomass fuel particles. Accordingly, the removal step (vi) is an effective post-treatment for removing dust in the solid biomass fuel.

[0158] example

[0159] The various solid biomass fuels of the present invention are produced by the method of the present invention. The forming step involves using a compression mold with a compression ratio of 3. An anti-coking additive is added to the biomass material before the forming step. Before the forming step, the biomass particles and the anti-coking additive are mixed to form a uniform mixture, which is then formed into pellets. The heating step includes heating the formed pellets to 320 °C for 1.8 hours.

[0160] The anti-coking additive used is kaolin, with a content of 0.4% by weight of the solid biomass fuel; aluminosilicate, with a content of 0.1% by weight of the solid biomass fuel; pulverized coal fuel ash, with a content of 0.1% by weight of the solid biomass fuel. Accordingly, each solid fuel product contains 0.6% by weight of the anti-coking additive.

[0161] The biomass source materials used are detailed in Table 1 below. Table 1 example source material A tobacco straw B palm leaf C cashew nut shell D hemp plant (flax) E arrow bamboo F rice husk G corn cob H litchi shell I peanut residue J seaweed K Albizia julibrissin M palm leaf and cashew nut shell

[0162] The bulk density of each solid biomass fuel is in the range of 0.6 to 0.7 kg / L.

[0163] The mechanical durability of each solid biomass fuel is in the range of 95% to 98%. The mechanical durability of fuels A to F, H, and I is 97% or higher.

[0164] The dry sulfur content of each solid biomass fuel is in the range of 0.02% to 0.25% by weight.

[0165] The dry hydrogen content of each solid fuel is in the range of 5% to 6% by weight.

[0166] The dry oxygen content of each solid biomass fuel is in the range of 30% to 38% by weight.

[0167] The dry carbon content of each solid biomass fuel is in the range of 50% to 58% by weight.

[0168] The dry nitrogen content of each solid biomass fuel is in the range of 0.5% to 1.6% by weight.

[0169] The chemical oxygen demand of each solid biomass fuel is in the range of 1100 to 2700.

[0170] The fixed carbon content of each solid biomass fuel is in the range of 27% to 40% by weight.

[0171] The ash content of each solid biomass fuel is in the range of 4% to 16% by weight.

[0172] The internal moisture content of each solid biomass fuel is in the range of 0.4% to 2.8% by weight.

[0173] The volatile matter content of each solid biomass fuel is in the range of 48% to 67%.

[0174] The PM1.0 emission of each solid biomass fuel is in the range of 129 to 145 mg / kg.

[0175] The calorific value of each solid biomass fuel is in the range of 5000 to 6200 kcal / kg.

[0176] The received basis moisture content of each solid biomass fuel is in the range of 1.5% to 4.5%.

[0177] The pH value of each solid biomass fuel is in the range of 4.5 to 8.6.

[0178] Therefore, the solid biomass fuels of Examples A to M have appropriate high-performance fuel characteristics, such as high bulk density, mechanical durability, energy content, and water resistance. The properties of this fuel are comparable to those of the solid biomass fuels produced in the prior art documents WO2020 / 229824, WO2021 / 014151, WO2021 / 024001, and WO2021 / 156628.

[0179] Comparative example compositions A to K were also prepared using the same method as the example compositions. The only difference between example compositions A to K and comparative example compositions A to K is that the comparative example compositions do not contain any anti-coking additives.

[0180] The coking characteristics of the solid biomass fuels prepared in Examples A to M were determined in accordance with GB / T8727-2008 as Figure 3 shown. The coking characteristics of comparative example compositions A to K are as Figure 4 shown.

[0181] It can be seen that the example compositions of the present invention each have a lower coking characteristic score than all the comparative example compositions. This indicates that the compositions of the present invention produce less coke deposits and less secondary combustion product emissions when burned. Therefore, the comparison of these figures shows that the anti-coking additive employed in the present invention can effectively improve the coking characteristics of solid biomass fuels derived from various different biomass sources.

Claims

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 plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweed, Albizia julibrissin, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof; wherein the solid biomass fuel further comprises one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof.

2. The solid biomass fuel according to claim 1, wherein the one or more biomass sources comprise straw, palm-derived materials, nut shells, hemp plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweed, Albizia julibrissin, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof, and the content thereof is at least 50% by weight, preferably at least 75%, more preferably at least 90%.

3. The solid biomass fuel according to claim 1 or 2, wherein the one or more biomass sources consist essentially of straw, palm-derived materials, nut shells, hemp plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweed, Albizia julibrissin, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass, or any combination thereof.

4. The solid biomass fuel according to any one of the preceding claims, wherein the one or more biomass sources comprise straw or consist essentially of straw; wherein the straw is selected from rice straw, tobacco straw, sesame straw, pepper straw, eggplant straw, cotton straw, sorghum straw, sunflower straw, wheat straw, corn straw, rapeseed straw, cassava straw, bean straw, or any combination thereof.

5. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise palm-derived materials or consist essentially of palm-derived materials; wherein the palm-derived materials are selected from palm trunks, palm leaves, empty fruit bunches (EFB), palm kernel shells (PKS), palm oil press cakes, palm outer skins, palm shells, palm fibers, or any combination thereof.

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

7. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise hemp plants or consist essentially of hemp plants; wherein the hemp plants are selected from ramie, jute, green hemp, flax, apocynum venetum, 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 bamboo or consist essentially of bamboo; wherein the bamboo is selected from Phyllostachys edulis, Dendrocalamus latiflorus, Fargesia nitida, or any combination thereof.

9. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources comprise fruit shells or consist essentially of fruit shells; wherein the fruit shells are selected from coconut shells, lychee shells, longan shells, snake fruit shells, mangosteen shells, durian shells, or any combination thereof.

10. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources include crop residues or consist essentially of crop residues; wherein the crop residues are selected from wheat husks, bagasse, soybean residue, peanut residue, cassava residue, sweet potato residue, coffee bean residue, or any combination thereof.

11. The solid biomass fuel according to any one of claims 1 to 3, wherein the one or more biomass sources include grass or consist essentially of grass; wherein the grass is selected from the genus Pennisetum, such as Pennisetum hydridum.

12. The solid biomass fuel according to any of the preceding claims, wherein the content of the material derived from the one or more biomass sources in the solid biomass fuel is at least 80% by weight.

13. The solid biomass fuel according to any of the preceding claims, wherein the content of the material derived from the one or more biomass sources in the solid biomass fuel is at least 90% by weight.

14. The solid biomass fuel according to any of the preceding claims, wherein the content of the material derived from the one or more biomass sources in the solid biomass fuel is at least 95% by weight.

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

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

17. The solid biomass fuel according to any of the preceding claims, wherein the total amount of the one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof present in the solid biomass fuel is 0.1% to 10% of the weight of the solid biomass fuel, preferably 0.1% to 5%.

18. The solid biomass fuel according to any of the preceding claims, wherein the total amount of the one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof present in the solid biomass fuel is 0.1% to 1% of the weight of the solid biomass fuel.

19. The solid biomass fuel according to any of the preceding claims, wherein the total amount of the one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes, or a combination thereof present in the solid biomass fuel is 0.1% to 0.8% of the weight of the solid biomass fuel, preferably 0.5% to 0.8%.

20. The solid biomass fuel according to claim 19, wherein the solid biomass fuel comprises: one or more aluminosilicate-containing clays, the total amount of which is 0.3% to 0.5% of the weight of the solid biomass fuel; one or more aluminosilicates, the total amount of which is 0.1% to 0.2% of the weight of the solid biomass fuel; and one or more pulverized fuel ashes, the content of which is 0.1% to 0.2% of the weight of the solid biomass fuel.

21. The solid biomass fuel according to claim 20, wherein the one or more aluminosilicate clays comprise kaolin.

22. The solid biomass fuel according to any one of the preceding claims, wherein the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ashes or combinations thereof and the material derived from the biomass source are uniformly dispersed in the solid biomass fuel.

23. The solid biomass fuel according to any one of the preceding claims, wherein the solid biomass fuel has a bulk density of 0.50 kg / l to 0.8 kg / l, preferably 0.60 kg / l to 0.75 kg / l, more preferably 0.60 kg / l to 0.70 kg / l as measured according to DIN EN 15103.

24. The solid biomass fuel according to any one of the preceding claims, wherein the solid biomass fuel has a mechanical durability of 97% or higher as measured according to DIN EN 15210-1.

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

26. The solid biomass fuel according to any one of the preceding claims, wherein: (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 measured according to GB / 11914-89; (ii) the fixed carbon content of the solid biomass fuel is 20% or more by weight, preferably 25% to 45%, wherein the fixed carbon content is measured according to DIN EN 51734; (iii) the ash content of the solid biomass fuel is less than 20% by weight, preferably less than 18%, wherein the ash content is measured according to EN 14775 at 550 °C. (iv) The volatile matter content of the solid biomass fuel is 35% to 80% by weight, more preferably 40% to 75% by weight, wherein the volatile matter content is determined according to DIN EN 15148; and / or (v) The internal moisture content of the solid biomass fuel is less than 8% by weight, preferably less than 6% by weight, more preferably less than 5% by weight, wherein the internal moisture content is determined according to DIN EN 14774.

27. The solid biomass fuel according to any one of the preceding claims, wherein the calorific value of the solid biomass fuel is 4300 kcal / kg to 6750 kcal / kg, wherein the calorific value is determined according to DIN EN 14918.

28. The solid biomass fuel according to any one of the preceding claims, wherein the basic moisture content of the solid biomass fuel is less than 10% by weight, preferably less than 8% by weight, most preferably less than 6% by weight, wherein the basic moisture content is determined according to GB / T 211-2017.

29. The solid biomass fuel according to any one of the preceding claims, wherein the pH value of the solid biomass fuel is 4 to 10.

30. The solid biomass fuel according to any one of the preceding claims, wherein the coking characteristic value during the combustion of the solid biomass fuel is less than or equal to 1.5, preferably 0.3 to 1.5, wherein the coking characteristic value is determined according to GB / T 8727-2008.

31. The solid biomass fuel according to any one of the preceding claims, wherein the solid biomass fuel is waterproof for up to 20 days, preferably up to 30 days, more preferably up to 40 days.

32. The solid biomass fuel according to any one of the preceding claims, wherein the PM1.0 emission during the combustion of the solid biomass fuel is less than 175 mg / kg, preferably less than 150 mg / kg.

33. A combustion method comprising the step of burning the solid biomass fuel according to any one of the preceding claims to generate energy.

34. The method according to claim 33, wherein the solid biomass fuel is co-fired and burned with fossil fuels such as coal.

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

36. Use of one or more aluminosilicate-containing clays, one or more aluminosilicates, one or more pulverized fuel ashes or combinations thereof as anti-coking additives in solid biomass fuels.

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

38. The use according to claim 37, wherein the solid and / or liquid combustible organic material deposits on the surface of the combustion chamber for burning the solid biomass fuel and / or on the surface of the pipes in fluid communication therewith.

39. The use according to claim 37 or 38, wherein the use comprises using the anti-coking additive to prevent or reduce secondary combustion of the deposits of the solid and / or liquid combustible organic materials.

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

41. The use according to any one of claims 36 to 40, wherein the solid biomass fuel is derived from one or more biomass sources; wherein the one or more biomass sources comprise straw, palm-derived materials, nut shells, ramie plants, bamboo, corncobs, rice husks, fruit shells, residues, seaweeds, Albizia julibrissin, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass or any combination thereof.

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

43. A method for preparing the solid biomass fuel according to any one of claims 1 to 32, wherein the method comprises the following steps: (i) Provide a biomass composition comprising biomass particles having an average particle size (D 50 ) of 1000 μm to 75000 μm; (ii) pulverizing the biomass composition to obtain an average particle size (D 50 ) is a pulverized biomass powder of 500 μm to 10000 μm; (iii) drying the pulverized biomass powder to obtain a dried pulverized biomass powder; (iv) shaping the dried pulverized biomass powder to obtain a shaped biomass product; wherein the dried pulverized biomass powder is shaped together with one or more aluminosilicate-containing clays, one or more aluminosilicates, pulverized fuel ash or a combination thereof to obtain a shaped biomass product; (v) heating the shaped biomass product to 110 °C to 500 °C for 0.2 to 6 hours to obtain a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel.

44. The method according to claim 43, wherein the biomass composition comprises one or more biomass sources, the biomass sources comprising straw, palm-derived materials, nut shells, ramie plants, bamboo, corncobs, rice husks, fruit shells, crop residues, seaweeds, Albizia julibrissin, Acacia mangium, Albizia chinensis, Hevea brasiliensis, grass or any combination thereof; optionally, wherein the one or more biomass sources are defined as in any one of claims 2 to 11.

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

46. The method according to any one of claims 43 to 45, wherein adjusting the shaping step such that the density of the shaped biomass product is controlled comprises: Controlling the compression ratio of the mold used in the shaping step.

47. The method according to any one of claims 43 to 46, wherein step (iv) of shaping the dried and pulverized biomass powder to obtain a shaped biomass product comprises: Shaping the dried pulverized biomass powder with a compression mold at a compression ratio of less than 6, preferably at a compression ratio of less than 5.

48. The method according to any one of claims 43 to 47, wherein step (iv) of shaping the dried and pulverized biomass powder to obtain a shaped biomass product comprises: Shaping the pulverized biomass powder with a compression mold at a compression ratio of less than or equal to 3.5, preferably at a compression ratio of less than or equal to 3, more preferably at a compression ratio of 1 to 3.

49. The method according to any one of claims 43 to 48, wherein the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ashes or combinations thereof are formed together with the dry pulverized biomass powder in a certain mass ratio to obtain a solid biomass fuel, and the total amount of the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ashes or combinations thereof in the solid biomass fuel is 0.1% to 10% by weight of the solid biomass fuel, preferably 0.1% to 5%, more preferably 0.1% to 1%, and most preferably 0.1% to 0.8%.

50. The method according to any one of claims 44 to 49, wherein the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ashes or combinations thereof are formed together with the dry pulverized biomass powder in a certain mass ratio to obtain a solid biomass fuel, and the total amount of the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ashes or combinations thereof in the solid biomass fuel is 0.5% to 0.8% by weight of the solid biomass fuel.

51. The method according to claim 50, wherein the one or more aluminosilicate clays, the one or more aluminosilicates, the one or more pulverized fuel ashes or combinations thereof are formed together with the dry pulverized biomass powder in a certain mass ratio to obtain a solid biomass fuel, the content of the one or more aluminosilicate clays in the solid biomass fuel is 0.3% to 0.5% by weight of the solid biomass fuel, the total amount of the one or more aluminosilicates is 0.1% to 0.2% by weight of the solid biomass fuel, and the content of the one or more pulverized fuel ashes is 0.1% to 0.2% by weight of the solid biomass fuel.

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