Method for producing solid biomass fuel

Abstract

SOLUTION: To provide a method for producing a solid biomass fuel from rice hulls, alone or in combination with other materials such as Caryoandra carotis or wood, and to provide the solid biomass fuel produced by the method.EFFECT: A fixed and constant source of biomass can be provided in the growth cycle for the production of fuel. When sources of biomass are grown and harvested on a commercial scale, the quality and uniformity of the biomass source can be controlled, for example, by cultivation and breeding techniques. Certain sources of biomass do not require pulverization prior to processing into a solid biomass fuel, thus reducing costs associated with processing.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing solid biomass fuel and to the solid biomass fuel produced by said method. Furthermore, the present invention relates to a combustion method comprising the step of combusting said solid biomass fuel to produce energy. [Background technology]

[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 resources. Over recent decades, there has been a demand to reduce coal consumption in coal-fired power plants and instead use renewable resources for energy.

[0003] Biomass-derived fuels are an example of a renewable energy source that can be used to replace, or at least partially replace, coal. Biomass-derived fuels can be burned in the presence of oxygen in a combustion process to produce energy in a power plant. Biomass-derived fuels can be burned in traditional power plants originally designed for coal combustion, or they can be burned 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 uniformity in properties. For example, biomass fuels containing particles of uniform size, density, moisture content, etc., are particularly desirable for co-firing processes. It is also desirable for biomass fuels to contain low levels of ash. The ash level in biomass-derived fuels is typically higher than that found in coal.

[0004] Various methods are known for producing solid biomass fuel from biomass sources. WO 2014 / 087949 discloses a method for producing solid biomass fuel in which a biomass source is steam exploded and then molded into biomass blocks, which are then heated to form biomass fuel. The aim of this method is to produce a solid biomass fuel that has sufficient handleability during storage and has a low chemical oxygen demand (COD) in the wastewater during storage. The goal of this method is to produce biomass fuel with reduced oxygen demand. The biomass source used in this method is palm kernel shell.

[0005] WO 2016 / 056608 A1 discloses a method for producing solid biomass fuel that builds on the teachings of WO 2014 / 087949 A1 and does not require a steam explosion step to produce the fuel. The method includes pulverizing a biomass source, compressing it, and molding it into biomass blocks, followed by heating the biomass blocks. Biomass sources taught for use in the method include Douglas fir, Western hemlock, Japanese cedar, Japanese cypress, Scots pine, old almond trees, almond shells, acacia wood, acacia bark, walnut shells, sago palm, empty fruit bunches, meranti, and rubber trees.

[0006] WO 2017 / 175733 discloses a similar method that includes a molding step in which a biomass source is crushed and then compressed into biomass blocks, followed by heating the biomass blocks. The method of WO 2017 / 175733 is directed to providing a biomass fuel that exhibits low disintegration properties and achieves reduced COD in wastewater when exposed to stormwater. The biomass used in this method The source of is selected from rubber tree, acacia, meranti, eucalyptus, teak, and a mixture of larch, spruce, and birch.

[0007] WO 2019 / 069849 aims to provide a biomass fuel that is easy to transport and store and resistant to spontaneous combustion during storage. The biomass fuel is produced by a process that includes crushing a biomass source, compressing it, and molding it into biomass blocks, followed by heating the biomass blocks. The biomass source for producing the fuel is selected from rubber tree, acacia tree, radiata pine, a mixture of larch, spruce, and birch, as well as spruce, pine, and fir.

[0008] WO 2019 / 069860 discloses an apparatus for producing biomass solid fuel. The apparatus includes a carbonization furnace for carbonizing a molded biomass product to obtain a biomass solid fuel. The apparatus further includes a yield calculation unit, a temperature measurement unit, and a control unit. The control unit controls the heat applied to the carbonization furnace based on the spontaneous combustion characteristics of the biomass fuel. The molded biomass product is formed by pulverizing a biomass source into pellets and then molding the pellets into molded biomass fuel. The biomass source is selected from rubber tree, acacia, dipterocarp, radiata pine, a mixture of larch, spruce, and birch, or a mixture of spruce and pine. It is selected from mixtures with fir.

[0009] WO 2018 / 181919 discloses a different method for producing solid biomass fuel than those discussed above. This method involves hydrothermal carbonization of a biomass source, in which the biomass source is pressurized in hot water to carbonize the biomass. This method is reported to provide biomass fuel with high pulverizability at high yields and reduced production costs. The biomass source is selected from husks, palm kernel shells, coconut, bamboo, empty fruit bunches, apricots, and eggplants.

[0010] WO 2017 / 175737 discloses a cooling device for cooling carbonized biomass. The device improves the cooling efficiency of torrefied molded biomass. The device cools the biomass by spraying water. The cooler includes a vibrating plate and a spray section for spraying water onto the plate. Biomass fuel is produced by the same method as discussed above. Sources of biomass for producing biomass fuel include Douglas fir, Western hemlock, Japanese cedar, Japanese cypress, Scots pine, old almond trees, almond shells, acacia wood, acacia bark, walnut shells, sago palm, empty fruit bunches, meranti, and rubber tree.

[0011] Finally, WO 2014 / 050964 discloses a method for improving the pulverizability of biomass so that it can be pulverized with coal. This method involves increasing the moisture content of pulverized woody biomass to 10-50% and reducing the moisture content to 0.55 g / cm 3 This involves densifying the biomass to have a density equal to or greater than 1000 kJ / g, and then subjecting the biomass to torrefaction. Sources of biomass include wood chips, bark, wood shavings, and sawdust. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] International Publication No. 2014 / 087949 Brochure [Patent Document 2] International Publication No. 2016 / 056608 Brochure [Patent Document 3] International Publication No. 2017 / 175733 Brochure [Patent Document 4] International Publication No. 2019 / 069849 Brochure [Patent Document 5] International Publication No. 2019 / 069860 Brochure [Patent Document 6] International Publication No. 2018 / 181919 Brochure [Patent Document 7] International Publication No. 2017 / 175737 Brochure [Patent Document 8] International Publication No. 2014 / 050964 Brochure Summary of the Invention [Problem to be solved by the invention]

[0013] The present inventors have recognized that the solid biomass fuels and methods for their production discussed in the above documents have various problems associated with them. For example, all of the biomass sources described in the above documents are plants and trees that typically only occur in nature and are not easily cultivated and harvested on a commercial scale. The present inventors have recognized that it would be advantageous to have a source of biomass that can be easily grown and harvested on a commercial scale. It would also be advantageous to have a source of biomass that can be grown and harvested so that the quality and specific characteristics of the biomass source can be controlled.

[0014] Additionally, the inventors have found that the biomass sources described in the above documents, all of which include wood or similar materials, form particles with low uniformity when subjected to conventional pulverization techniques known in the art. Furthermore, pulverizing biomass sources is expensive due to the difficult nature of wood and wood-like materials. The inventors have recognized that it would be advantageous to have a source of biomass that is more easily pulverized by conventional pulverization techniques known in the art and that forms particles of a more uniform size when pulverized, or that does not require pulverization prior to conversion to solid biomass fuel.

[0015] In addition, the present inventors have found that solid biomass fuels prepared from the biomass sources discussed in the above literature and prepared by the methods therein do not have sufficient waterproofing characteristics. Waterproofing characteristics are important for solid biomass fuels because they must be dry (or at least sufficiently dry) at the time of use in a combustion process (either alone or when co-firing with coal). Biomass fuels are frequently exposed to moisture (e.g., from rainwater) during storage or transportation. Therefore, biomass fuels with increased waterproofing capabilities are desirable.

[0016] The inventors have also recognized that the biomass fuel production methods described in the above documents do not provide fuel of sufficient quality and uniformity. In particular, the methods discussed above do not provide sufficient control of the density of the biomass during the molding step. [Means for solving the problem]

[0017] The present invention addresses the problems discussed above with respect to previous methods. It has surprisingly been discovered that certain biomass sources useful for providing solid biomass fuels can be grown and harvested on a commercial scale. In doing so, a defined and consistent source of biomass can be provided in a growth cycle for the production of fuel. Additionally, growing and harvesting the biomass source on a commercial scale allows for control of the quality and uniformity of the biomass source, for example, through cultivation and breeding techniques.

[0018] Additionally, it has been found that, advantageously, certain biomass sources do not require pulverization prior to processing into solid biomass fuel, thus reducing costs associated with processing.

[0019] In addition to the above, the inventors of the present invention also found that the molding step and / or the processing step in the method It has been discovered that by modifying the heating step, biomass fuels with improved waterproofing characteristics can be provided. It has also been discovered that adaptation and control of the shaping and heating steps in the methods of the present invention improves the quality and uniformity of the solid biomass fuel product and imparts certain physical properties to the solid biomass fuel product that are highly desirable for use in combustion processes. Furthermore, it has been discovered that adapting the shaping and heating steps increases the yield of solid biomass fuel and imparts properties to the fuel that facilitate transportation and storage. The inventors have discovered that the properties of the biomass source and the specific characteristics of the shaping and heating steps work together to provide superior biomass fuel products for use in combustion processes beyond those known in the art.

[0020] According to a first aspect of the present invention, there is provided a method for producing solid biomass fuel, comprising the steps of: (i) providing one or more biomass powders having a particle size between 1000 μm and 10,000 μm; (ii) heating the one or more biomass powders to a temperature of between 160°C and 420°C for a period of between 0.25 and 5 hours to provide a heated biomass product; and (iii) molding the heated biomass product to provide a solid biomass fuel. Including, The method is provided wherein the one or more biomass powders are derived from one or more biomass sources, and the one or more biomass sources (i) consist of or consist essentially of rice husks; (ii) include or consist essentially of a mixture of rice husks and wood, such as mixed wood; (iii) consist of or consist essentially of a mixture of rice husks and Calliandra callothyrsus; or (iv) include rice husks and Calliandra callothyrsus in an amount of at least 15% by weight; and when the one or more biomass sources consist of or consist essentially of rice husks, the biomass-derived material is present in the solid biomass fuel in an amount of at least 95% by weight of the total fuel content of the solid biomass fuel.

[0021] In an embodiment, the one or more sources of biomass consist of or consist essentially of rice husks.

[0022] In another embodiment, the one or more biomass sources further comprise wood, such as mixed wood, Calliandra carotylus, or a combination thereof. Preferably, the one or more biomass sources comprise (i) rice husks and Calliandra carotylus, or (ii) wood, such as rice husks and mixed wood. In an embodiment, the one or more biomass sources consist of, or consist essentially of, a mixture of rice husks and wood, such as mixed wood. In another embodiment, the one or more biomass sources consist of, or consist essentially of, a mixture of rice husks and Calliandra carotylus. In another embodiment, the one or more biomass sources comprise rice husks and Calliandra carotylus in an amount of at least 15% by weight.

[0023] In an embodiment, the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight. In one embodiment, the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and wood, such as mixed wood, in an amount of 20% to 80% by weight. Preferably, the one or more biomass sources do not comprise coconut husks or straw. In an embodiment, the one or more biomass sources consist essentially of rice husks and wood, such as mixed wood, and the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and wood, such as mixed wood, in an amount of 20% to 80% by weight. In another embodiment, the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and Calliandra carotylus in an amount of 20% to 80% by weight. In an embodiment, the one or more biomass sources comprise The biomass source consists essentially of rice husks and Calliandra carotylus, and the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and Calliandra carotylus in an amount of 20% to 80% by weight.

[0024] The step of heating the one or more biomass powders is preferably carried out for a period of 0.4 to 3 hours, such as 0.4 to 2 hours, or 0.5 to 3 hours, such as 0.4 to 2 hours.

[0025] The step of heating the one or more biomass powders comprises heating the one or more biomass powders to a temperature between 180°C and 350°C, preferably between 210°C and 280°C.

[0026] Preferably, step (ii) of heating the one or more biomass powders comprises heating the one or more biomass powders under conditions to induce torrefaction of the molded biomass product.

[0027] Preferably, the method further comprises, prior to step (iii) of shaping the heated biomass product: Further comprising cooling the heated biomass product.

[0028] The step (i) of providing one or more biomass powders may include pulverizing one or more sources of biomass and / or blending one or more biomass powders.

[0029] Typically, the method may include the step of drying the one or more biomass powders prior to step (ii) of heating the one or more biomass powders.

[0030] The step (iii) of molding the heated biomass product may be carried out by adjusting the density of the solid biomass fuel. Preferably, adapting the molding step to control the density of the solid biomass fuel comprises controlling the compression ratio of a mould used in said molding step.

[0031] Preferably, the method further comprises, prior to step (iii) of shaping the heated biomass product: The method includes adding an additive to the heated biomass product, preferably the additive is added to increase the yield of solid biomass fuel.

[0032] Step (ii) of heating one or more biomass powders is typically adapted to control the uniformity of the heated biomass product. Preferably, adapting step (ii) to control the uniformity of the heated biomass product comprises performing step (ii) in an apparatus that rotates the one or more biomass powders while heating them. More preferably, adapting step (ii) to control the uniformity of the heated biomass product comprises controlling the speed or direction of rotation of the one or more biomass powders. Most preferably, the one or more biomass powders are rotated in the apparatus in both counterclockwise and clockwise directions.

[0033] The bulk density of the solid biomass fuel, as determined by DIN EN 15103, is typically between 0.40 kg / l and 0.65 kg / l, preferably between 0.45 kg / l and 0.60 kg / l, most preferably between 0.50 and 0.60 kg / l.

[0034] The mechanical durability of solid biomass fuels, determined according to DIN EN 15210-1, is typically 95% or more, 96% or more, 97% or more, or 98% or more.

[0035] In some embodiments of this method, the one or more sources of biomass and solid biomass fuel are: (i) the one or more biomass sources include or consist essentially of rice husks, the solid biomass fuel has a bulk density of 0.40 kg / L to 0.48 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; (ii) the one or more biomass sources include a mixture of rice husk and wood, such as mixed wood, and the solid biomass fuel has a bulk density of 0.50 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; or (iii) One or more biomass sources are rice husk and Calliandra carothyrus and a mixture thereof, wherein the solid biomass fuel has a bulk density of 0.45 kg / L to 0.60 kg / L, and the mechanical durability of the solid biomass fuel is 95% or more; The bulk density is determined according to DIN EN 15103 and the mechanical durability according to DIN EN 15210-1.

[0036] Typically, the total dry sulfur content of the resulting biomass solid fuel is 0.05 wt. % or less, preferably 0.04 wt. % or less, most preferably 0.03 wt. % or less, the total dry sulfur content being determined according to DIN EN 15289.

[0037] Typically, the total dry hydrogen content of the resulting biomass solid fuel is 5 wt.% or more, preferably 5 wt.% to 10 wt.%, more preferably 5 wt.% to 7 wt.%, the total dry hydrogen content being determined according to DIN EN 15104.

[0038] Typically, the total dry oxygen content of the resulting biomass solid fuel is 34% by weight or more, preferably 34% to 40% by weight, more preferably 34% to 38% by weight, the total dry oxygen content being determined according to DIN EN 15296.

[0039] Typically, the total dry carbon content of the resulting biomass solid fuel is 40% by weight or more, preferably 45% to 55% by weight, more preferably 50% to 52% by weight, the total dry carbon content being determined according to DIN EN 15104.

[0040] Typically, the total dry nitrogen content of the resulting biomass solid fuel is less than 0.5 wt.%, preferably less than 0.4 wt.%, more preferably less than 0.3 wt.%, the total dry nitrogen content being determined according to DIN EN 15104.

[0041] Typically, the resulting solid biomass fuel is waterproof for up to 20 days, preferably up to 30 days, and more preferably up to 40 days.

[0042] Typically, the chemical oxygen demand (COD) of the resulting solid biomass fuel when immersed in water is 5000 ppm or less, preferably 4000 ppm or less, and most preferably 3000 ppm or less, where COD is determined by GB / 11914-89.

[0043] Typically, the fixed carbon content of the solid biomass fuel is 28% by weight or more, preferably 28% to 35% by weight, more preferably 30% to 33% by weight, the fixed carbon content being determined according to DIN EN 51734.

[0044] Typically, the ash content of the solid biomass fuel is less than 25 wt%, preferably less than 20 wt%, most preferably less than 18 wt%, the ash content being determined according to EN 14775 at 550°C.

[0045] Typically, the volatile matter content of the solid biomass fuel is between 40% and 65% by weight, more preferably between 45% and 60% by weight, the volatile matter content being determined according to DIN EN 15148.

[0046] Typically, the moisture content of the resulting solid biomass fuel is less than 8 wt.%, preferably less than 6 wt.%, most preferably less than 5 wt.%, moisture content as determined by DIN EN 14774.

[0047] Typically, the calorific value of the resulting solid biomass fuel is between 4300 kcal / kg dry mass and 6500 kcal / kg dry mass, the calorific value being determined according to DIN EN 14918.

[0048] Typically, the bulk density of the molded biomass product is A and the bulk density of the solid biomass fuel is B, with B / A being 0.55 to 1, the bulk density being determined according to DIN EN 15103.

[0049] Preferably, the method does not include adding coal, an oxidizer, an ignition agent, or a combination thereof to the heated biomass product prior to the shaping step, and the solid biomass fuel does not include coal, an oxidizer, an ignition agent, or a combination thereof.

[0050] In an embodiment, step (ii) of heating the one or more biomass powders comprises heating the one or more biomass powders for a period of from 30 minutes to 5 hours, optionally from 1 hour to 5 hours.

[0051] According to a second aspect of the present invention there is provided a solid biomass fuel obtainable or obtained by a method according to the first aspect of the present invention.

[0052] According to a third aspect of the present invention, there is provided a solid biomass fuel derived from one or more biomass sources, the one or more biomass sources (i) consisting of or consisting essentially of rice husks; (ii) comprising or consisting essentially of a mixture of rice husks and wood, such as mixed wood; or (iii) a mixture of rice husks and Calliandra carothyrus. or (iv) comprising rice husks and Calliandra carotylus in an amount of at least 15% by weight, wherein when one or more biomass sources consist of or consist essentially of rice husks, the biomass-derived material is present in the solid biomass fuel in an amount of at least 95% by weight of the total fuel content of the solid biomass fuel.

[0053] In an embodiment, the one or more biomass sources comprise rice husks and wood, such as mixed wood. Typically, the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and wood, such as mixed wood, in an amount of 20% to 80% by weight. Preferably, the one or more biomass sources do not comprise coconut husks or straw. In an embodiment, the one or more biomass sources consist essentially of rice husks and wood, such as mixed wood, and the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and wood, such as mixed wood, in an amount of 20% to 80% by weight.

[0054] In another embodiment, the one or more biomass sources comprise a mixture of rice husks and Calliandra carotylus, wherein the rice husks are present in an amount of at least 15% by weight of the total weight of the one or more biomass sources. Preferably, the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and Calliandra carotylus in an amount of 20% to 80% by weight. In an embodiment, the one or more biomass sources comprise a mixture of rice husks and and Calliandra carotylus, wherein the one or more biomass sources comprise rice husks in an amount of 20% to 80% by weight and Calliandra carotylus in an amount of 20% to 80% by weight.

[0055] The bulk density of the solid biomass fuel, as determined by DIN EN 15103, is typically between 0.40 kg / l and 0.65 kg / l, preferably between 0.45 kg / l and 0.60 kg / l, most preferably between 0.50 and 0.60 kg / l.

[0056] The mechanical durability of solid biomass fuels, determined according to DIN EN 15210-1, is typically 95% or more, 96% or more, 97% or more, or 98% or more.

[0057] In some embodiments of this method, the one or more sources of biomass and solid biomass fuel are: (i) the one or more biomass sources include or consist essentially of rice husks, the solid biomass fuel has a bulk density of 0.40 kg / L to 0.48 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; (ii) the one or more biomass sources include a mixture of rice husk and wood, such as mixed wood, and the solid biomass fuel has a bulk density of 0.50 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; or (iii) One or more biomass sources are rice husk and Calliandra carothyrus and a mixture thereof, wherein the solid biomass fuel has a bulk density of 0.45 kg / L to 0.60 kg / L, and the mechanical durability of the solid biomass fuel is 95% or more; The bulk density is determined according to DIN EN 15103 and the mechanical durability according to DIN EN 15210-1.

[0058] Typically, the total dry sulfur content of the resulting biomass solid fuel is 0.05 wt. % or less, preferably 0.04 wt. % or less, most preferably 0.03 wt. % or less, the total dry sulfur content being determined according to DIN EN 15289.

[0059] Typically, the total dry hydrogen content of the resulting biomass solid fuel is 5 wt.% or more, preferably 5 wt.% to 10 wt.%, more preferably 5 wt.% to 7 wt.%, the total dry hydrogen content being determined according to DIN EN 15104.

[0060] Typically, the total dry oxygen content of the resulting biomass solid fuel is 34% by weight or more, preferably 34% to 40% by weight, more preferably 34% to 38% by weight, the total dry oxygen content being determined according to DIN EN 15296.

[0061] Typically, the total dry carbon content of the resulting biomass solid fuel is 40% by weight or more, preferably 45% to 55% by weight, more preferably 50% to 52% by weight, the total dry carbon content being determined according to DIN EN 15104.

[0062] Typically, the total dry nitrogen content of the resulting biomass solid fuel is less than 0.5 wt.%, preferably less than 0.4 wt.%, more preferably less than 0.3 wt.%, the total dry nitrogen content being determined according to DIN EN 15104.

[0063] Typically, the resulting solid biomass fuel is waterproof for up to 20 days, preferably up to 30 days, and more preferably up to 40 days.

[0064] Typically, the chemical oxygen demand (COD) of the resulting solid biomass fuel when immersed in water is 5000 ppm or less, preferably 4000 ppm or less, and most preferably 3000 ppm or less. 000ppm or less, and the chemical oxygen demand is determined by GB / 11914-89.

[0065] Typically, the fixed carbon content of the solid biomass fuel is 28% by weight or more, preferably 28% to 35% by weight, more preferably 30% to 33% by weight, the fixed carbon content being determined according to DIN EN 51734.

[0066] Typically, the ash content of the solid biomass fuel is less than 25 wt%, preferably less than 20 wt%, most preferably less than 18 wt%, the ash content being determined according to EN 14775 at 550°C.

[0067] Typically, the volatile matter content of the solid biomass fuel is between 40% and 65% by weight, more preferably between 45% and 60% by weight, the volatile matter content being determined according to DIN EN 15148.

[0068] Typically, the moisture content of the resulting solid biomass fuel is less than 8 wt.%, preferably less than 6 wt.%, most preferably less than 5 wt.%, moisture content as determined by DIN EN 14774.

[0069] Typically, the calorific value of the resulting solid biomass fuel is between 4300 kcal / kg dry mass and 6500 kcal / kg dry mass, the calorific value being determined according to DIN EN 14918.

[0070] According to a fourth aspect of the present invention there is provided a method of combustion comprising combusting a solid biomass fuel according to the second and third aspects of the present invention to produce energy.

[0071] In one embodiment, the solid biomass fuel is co-fired and combusted with a fossil fuel, preferably comprising coal.

[0072] In one embodiment, the method has PM1.0 emissions of less than 175 mg / kg, preferably less than 150 mg / kg.

[0073] According to a fifth aspect of the present invention there is provided the use of a solid biomass fuel according to the second and third aspects of the present invention as a fuel in a combustion process.

[0074] Preferably, the combustion method comprises co-firing a solid biomass fuel together with a fossil fuel, preferably the fossil fuel being coal.

[0075] In one embodiment, the method has PM1.0 emissions of less than 175 mg / kg, preferably less than 150 mg / kg.

[0076] According to a sixth aspect of the present invention, there is provided a use of one or more sources of biomass for producing solid biomass fuel, wherein the one or more sources of biomass (i) consist of or consist essentially of rice husks; (ii) comprise or consist essentially of a mixture of rice husks and wood, such as mixed wood; or (iii) consist essentially of a mixture of rice husks and Calliandra caroti. or (iv) comprising rice husks in an amount of at least 15% by weight and Calliandra carotylus; or (iv) comprising rice husks and Calliandra carotylus, and when the one or more biomass sources consist of or consist essentially of rice husks, the biomass-derived material is present in the solid biomass fuel in an amount of at least 95% by weight of the total fuel content of the solid biomass fuel.

[0077] Preferably, the one or more sources of biomass are as described above in accordance with the first and third aspects of the present invention.

[0078] Preferably, the use comprises using one or more sources of biomass in a method according to the first aspect of the invention.

[0079] Preferably, the solid biomass fuel is as described above in accordance with the first and third aspects of the present invention. [Brief explanation of the drawings]

[0080] The invention will now be described, by way of example only, with reference to the accompanying figures. [Figure 1] This is a photo of rice husks. [Figure 2] 1 is a graph illustrating the difference in production yield during the molding step, where the biomass source consists of rice husk. [Figure 3] 1 is a graph illustrating productivity on the Y-axis against compression ratio on the X-axis for molded biomass product produced according to the method of the present invention, where the biomass source consists of rice husk. [Figure 4] 1 is a graph illustrating density on the y-axis (kg / L) against compression ratio on the x-axis for molded biomass product produced according to the method of the present invention, the biomass source consisting of rice husk. [Figure 5] 1 is a photograph of a biomass fuel product of the present invention. [Figure 6] 1 is a graph illustrating the bulk density of several products of the present invention. [Figure 7] 1 is a graph illustrating the durability of several products of the present invention. [Figure 8] 1 is a graph illustrating the sulfur content of several products of the present invention. [Figure 9] 1 is a graph illustrating the oxygen content of several products of the present invention. [Figure 10] 1 is a graph illustrating the carbon content of several products of the present invention. [Figure 11] 1 is a graph illustrating the nitrogen content of several products of the present invention. [Figure 12] 1 is a graph illustrating the fixed carbon content of several products of the present invention. [Figure 13] 1 is a graph illustrating the ash content of several products of the present invention. [Figure 14] 1 is a graph illustrating the moisture content of several products of the present invention. [Figure 15] 1 is a graph illustrating the volatile content of several products of the present invention. [Figure 16] 1 is a graph illustrating PM1.0 emissions for several products of the present invention. [Figure 17] 1 is a graph showing the results of testing products of the present invention in a climate chamber. [Figure 18] 1 is a graph showing the results of another test of a product of the present invention in a climate chamber. [Figure 19] 1 is a graph showing the results of another test of a product of the present invention in a climate chamber. [Figure 20] 1 is a graph showing the surface moisture regain results of several products of the present invention after testing in a climate chamber. [Figure 21] 2 is a schematic representation of a compression mold that can be used in the molding step of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0081] Biomass Sources The one or more biomass sources used in accordance with the present invention may be any of those described above. In a preferred embodiment, the one or more biomass sources comprise, consist essentially of, or consist of rice husks. When the one or more biomass sources comprise rice husks and one or more additional biomass sources, the one or more biomass sources may contain any particular amount of rice husks, such as from 5% to 95% by weight. Typically, when the one or more biomass sources include rice husks and one or more additional biomass sources, the rice husks are present in an amount of 10% to 90%, 20% to 80%, 30% to 70%, or 40% to 60% by weight of the total amount of the one or more biomass sources.

[0082] When the one or more biomass sources include or consist of a mixture of rice husks and Calliandra carotylus, the rice husks are typically present in an amount of at least 15% by weight of the total weight of the one or more biomass sources. Preferably, the rice husks are present in an amount of 20% to 80% by weight of the total weight of the one or more biomass sources present. When the one or more biomass sources include or consist of a mixture of rice husks and wood, such as mixed wood, the rice husks are typically present in an amount of at least 15% by weight of the total weight of the one or more biomass sources present. Preferably, the rice husks are present in an amount of 20% to 80% by weight of the total weight of the one or more biomass sources present.

[0083] Each of the one or more sources of biomass described above can be obtained or harvested by conventional methods known in the art.

[0084] As used herein, the term "wood" typically refers to a hard, fibrous body consisting essentially of the xylem beneath the bark that occupies the majority of the trunk, branches, and roots of a tree or shrub. Wood is found only to a limited extent in foliose plants. This definition of the term "wood" is consistent with the definition generally understood in the art. As used herein, the term "mixed wood" refers to a mixture of two or more types of wood. The two or more types of wood may be present in the mixed wood in any amount, as long as the mixed wood contains at least two types of wood.

[0085] As used herein, the term "comprising" is used to mean that any additional, unspecified 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, unspecified components may be present, but , is used to mean that these ingredients do not substantially affect the essential characteristics of the composition.

[0086] As described above, the one or more biomass sources used in the present invention can be grown and harvested on a commercial scale and have been found to provide increased control over the quality and specific properties of the biomass source compared to materials used in the prior art. The use of such materials also avoids the environmental damage associated with using trees, such as the necessary felling. The above advantages are particularly relevant to the use of rice husk and Calliandra carotylus.

[0087] It has also been surprisingly found that the one or more biomass sources used in the present invention are easier to mill than previously used materials. For some materials, milling is not even necessary, thereby reducing the cost of the milling process. In particular, rice husks generally do not require milling. While Calliandra carotidus does require milling, it has been found to be easier to mill than previously used materials.

[0088] The use of the materials of the present invention also provides a more homogeneous particle size mix when pulverized than previously used materials. Without being limited by theory, this may result in improved final solid fuel quality, including greater uniformity and continuity of the biomass fuel product. It is believed that this imparts advantageous properties to the product, which is desirable in combustion processes for several reasons.

[0089] Rice husks may also be particularly useful as a source of biomass due to the abundance of rice in certain regions of the world. Currently, the area used for rice cultivation worldwide is approximately 155 million hectares, with China alone using 31 million hectares, accounting for approximately 20% of the world's surface area used for rice cultivation. China ranks first in total rice production, accounting for 31% of global production. Rice husks (shown in Figure 1) are the primary by-product generated during rice processing. They are clean and a renewable resource with abundant reserves. Rice husks are also inexpensive because they are an abundant by-product of the rice production process.

[0090] However, rice husks have a low packing density and, for at least this reason, are inconvenient to transport. Furthermore, when rice husks are directly incinerated in agriculture and forestry, the dust can cause air pollution. An advantage of using rice husks compared to other previously used biomass raw materials is that rice husks do not need to undergo expensive pulverization processing. However, a disadvantage of rice husks is that when fuel is made from rice husks using conventional biomass fuel production methods, the resulting fuel does not produce sufficient energy per unit volume. Therefore, there is a need in the art for a method for producing solid biomass fuel from rice husks that alleviates the above-mentioned drawbacks. The method of the present invention has been found to alleviate the above drawbacks.

[0091] Other advantages associated with the use of rice husks include the uniformity in size and density of rice husks as a starting material, which means that the rice husks can be directly torrefied without prior molding, as described in more detail below. Solid biomass fuel produced from rice husks has also been found to have increased waterproofing characteristics when compared to biomass solid fuels derived from different starting materials.

[0092] As used herein, the term rice husk is used interchangeably with the term rice hull.

[0093] Biomass Blending & Pulverization Step (i) of providing one or more biomass powders having a particle size of between 1000 μm and 10000 μm may comprise micronising one or more sources of biomass.

[0094] The biomass source can be micronized into biomass powder by standard techniques known in the art. The biomass source can be micronized so that the biomass powder has an average particle diameter (D50) of 1000 μm to 10,000 μm. Typically, one or more biomass sources are micronized to have an average particle diameter of 1000 μm to 8000 μm, 2000 μm to 8000 μm, or 2000 μm to 6000 μm. As described above, micronizing certain biomass sources for use in the present invention has been found to provide biomass powders with advantageous particle size distributions that are smaller than those provided by milling previously known biomass sources. This is particularly true for Calliandra carotylus.

[0095] In an embodiment, the method includes the step of micronizing the rice husks. In an alternative embodiment, the method does not include the step of micronizing the rice husks. As noted above, an advantage of using rice husks is that due to their naturally occurring particle size, micronization is not necessarily required.

[0096] Step (i) of preparing one or more biomass powders may also include blending rice husks with one or more other sources of biomass. Blending may be performed using standard techniques known in the art. In an embodiment, the one or more sources of biomass in addition to the rice husks are micronized to have a particle size of 1000 μm to 10,000 μm. In another embodiment, the one or more additional sources of biomass may have a naturally occurring particle size of 1000 μm to 10,000 μm and therefore do not need to be micronized.

[0097] Heating of biomass powder The one or more biomass powders are heated to produce a heated biomass product. Heating is carried out at a temperature of 160°C to 420°C for a period of 0.25 to 5 hours. Preferably, the step of heating the molded biomass product is carried out for a period of 0.4 to 2 hours. Preferably, the step of heating the one or more biomass powders includes heating the one or more biomass powders to a temperature of 180°C to 350°C, more preferably to a temperature of 210°C to 280°C.

[0098] Preferably, step (ii) of heating the one or more biomass powders comprises heating the one or more biomass powders under conditions to induce torrefaction of the one or more biomass powders. Torrefaction is a mild pyrolysis process in which heating is carried out in a low-oxygen atmosphere, such as an atmosphere with an oxygen content of less than 10%. Suitable conditions and processes for torrefaction are known in the art. Thus, preferably, step (ii) of heating the one or more biomass powders comprises torrefaction.

[0099] The heating step can be carried out in any apparatus known in the art suitable for heating one or more biomass powders, for example, the heating step can be carried out in the apparatus and using the process conditions disclosed in EP 3287509 A1.

[0100] Preferably, step (ii) of heating one or more biomass powders is adapted to control the uniformity of the heated biomass product; optionally, adapting step (ii) to control the uniformity of the heated biomass product comprises performing step (ii) in an apparatus that rotates the one or more biomass powders while heating them; optionally, adapting step (ii) to control the uniformity of the heated biomass product comprises controlling the speed or direction of rotation of the one or more biomass powders; optionally, rotating the one or more biomass powders in the apparatus in both counterclockwise and clockwise directions. The uniformity of the heated biomass product is also optimized by the heating temperature and duration described above. Without being limited by theory, it is believed that the greater uniformity in the heated biomass product is transferred to the solid biomass fuel product once formed, resulting in a more uniform solid biomass fuel.

[0101] When the method of the present invention includes a step of cooling the biomass after the step of heating the biomass, the cooling step may include rotating the biomass. The biomass may be rotated in a suitable apparatus such as that disclosed in EP 3287509 A1. Preferably, both the heating step (ii) 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, such as both clockwise and counterclockwise, in successive cycles.

[0102] The term "homogeneity" of solid biomass products refers to the homogeneity of solid biomass fuel or heated biomass. Uniformity is used to refer to a solid biomass fuel or heated biomass product having consistent or similar properties down to each particle of the mass product, and down to multiple particles within a bulk sample of the solid biomass fuel or heated biomass product. For example, but not limited to, particle density, particle ease of combustion, particle chemical composition, and particle water resistance properties. Uniformity is a highly desirable property for biomass fuels for use in combustion processes.

[0103] The inventors have also found that controlling the heating step as described above further assists in providing a solid biomass fuel product with enhanced waterproofing properties compared to prior art biomass fuels. During the heating step, water-absorbing hydrophilic compounds present in the biomass powder are decomposed. Furthermore, the heating step causes oils present in the biomass powder to migrate to the exterior of the biomass powder particles, increasing the hydrophobicity of the particles.

[0104] Molding of heated biomass products The biomass powder is molded to provide a solid biomass fuel. The molding step may be carried out in any molding device known in the art according to biomass molding techniques known in the art, and may include an extrusion molding system. Preferably, the molding step is carried out in a compression mold. Preferably, the compression mold includes a molded product exit hole. The molding step may be carried out using the device described in Chinese Patent No. 105435708.

[0105] Preferably, the shaping step comprises shaping the biomass powder into pellets. Thus, in a preferred embodiment, the solid biomass fuel product comprises biomass pellets.

[0106] While molding biomass powder to produce a molded biomass product is known, the present inventors have surprisingly discovered that adapting the molding step to control the density of the resulting molded biomass product within a specific range can impart certain advantageous properties to the final solid biomass fuel product. In particular, controlling the molding step to provide a molded biomass product with a density within the range of 0.60 to 1.30 kg / L has been found to impart advantageous properties to the final biomass fuel product. Preferably, the molding step is controlled to provide a molded biomass product with a density within the range of 0.70 kg / L to 1.25 kg / L.

[0107] The molding step can be controlled in a variety of ways. When the molding process involves the use of a compression mold, density is controlled by using a compression ratio of 3.8 to 6.5. Typically, a lower compression ratio results in a lower density molded biomass product. However, a higher compression ratio results in a lower yield of molded biomass product.

[0108] The compression ratio for a compression mold having a molded product exit hole can be defined as the ratio of the length to the diameter of the molded product exit hole.

[0109] Figure 21 shows an example of a compression mold that can be used in accordance with the present invention. After the heated biomass product is inserted into the mold, it is forced out of the mold by pressure, exiting the molded product exit hole shown in the figure. The pressure ratio is shown in the figure as the ratio of the length to the diameter of the molded product exit hole.

[0110] In the method of the present invention, preferably, the step (iii) of molding the biomass powder comprises: The molding step is adapted so that the density of the molded biomass product is controlled within the range of 0.70 kg / L to 1.25 kg / L. Preferably, the density is controlled by using a compression mold and controlling the compression ratio of the compression mold. More preferably, the compression ratio is is 3.8 to 6.5.

[0111] It has been surprisingly found that controlling the density of the molded biomass product during the molding step provides the final biomass fuel product with increased waterproofing capabilities. Preferably, solid biomass fuel products produced from molded biomass products having densities in the range of 0.70 kg / L to 1.25 kg / L are sufficiently waterproof for up to 20 days, preferably up to 30 days.

[0112] Preferably, prior to step (iii) of shaping the heated biomass product, the heated biomass product is Additives are added to the molding product, which are believed to improve the molding process and increase the yield of molded biomass product produced from the molding step. Suitable additives are known in the art and include, but are not limited to, starch or starch derivatives.

[0113] Figure 2 shows the difference in yield after the extrusion step when additives are included in the extrusion step versus when no additives are included, and one or more biomass sources consist of rice husks. It can be seen that higher yields are obtained when additives are added to the cooked biomass product before extrusion.

[0114] 3 is a graph illustrating productivity on the Y-axis against compression ratio on the X-axis for molded biomass product produced according to the methods of the present invention, where the biomass source consists of rice husks.

[0115] FIG. 4 is a graph illustrating density on the y-axis (kg / L) against compression ratio on the x-axis for a molded biomass product produced according to the method of the present invention, where the biomass source consists of rice husk.

[0116] In the method of the present invention, once the shaping step (iii) has been carried out, several In embodiments, the direct product of the molten step (referred to herein as molten biomass product) may be used directly as a solid biomass fuel in a combustion process. In alternative embodiments, the molten biomass product may be further processed to provide a solid biomass fuel product. Thus, in some embodiments, the methods of the present invention further comprise processing the direct product of the molten step (molded biomass product) to form a solid biomass fuel.

[0117] The present invention involves heating biomass powder before molding the heated biomass particles. This contrasts with known methods in which molding is performed before torrefaction of the biomass. The advantage of torrefaction before molding is that the torrefaction process is easier and requires less energy due to the small particle size and large surface area of ​​biomass powder compared to large-sized molded pellets. In some methods, torrefaction after molding effectively torrefies only the exterior of the molded pellets, not the interior. Furthermore, torrefaction of molded pellets can lead to cracking of the pellets during the heating step. Therefore, molding after torrefaction has been found to be advantageous.

[0118] However, known methods involve shaping prior to torrefaction, as shaping is necessary to provide a uniform, homogeneous shaped pellet product. It is highly desirable that the biomass particles subjected to torrefaction be of uniform size. For previously known biomass starting materials, such as various types of wood, shaping prior to torrefaction is necessary because the milling process used to break the wood into small particles does not provide a sufficiently uniform pulverized product. Therefore, to provide a uniform product for torrefaction, the pulverized particles are required to be shaped into pellets. In contrast, when using rice hulls as the biomass starting material, roasting may be advantageously carried out before molding, since rice hull particles naturally occur in small, uniform sizes, and either no or only minimal grinding is required to produce a uniform product with a large surface area. The product can be roasted without molding, thus providing the advantages described above.

[0119] Typically, other than additives such as those described above, no other fuel source is added to the heated biomass product during the molding step. Thus, the molded biomass product (i.e., solid biomass fuel) of the molding step contains only biomass-derived materials as the fuel source in the solid biomass fuel. For example, when the heated biomass product is molded into pellets, no other fuel source is typically added to the heated biomass product before molding, so that the solid biomass fuel pellets produced by the molding step contain only biomass-derived fuel sources. Thus, in preferred embodiments, the solid biomass fuel constitutes at least 50% by weight of the total fuel content of the fuel, e.g., at least 60%, at least 70%, at least 80%, at least 90%, and preferably at least 95% by weight of biomass-derived materials. When one or more biomass sources consist of, or consist essentially of, rice husks, the biomass solid fuel constitutes at least 95% by weight of the total fuel content of the fuel of biomass-derived materials.

[0120] This is in contrast to certain methods known in the art where solid fuel pellets are produced in a molding step during which biomass-derived material is mixed with an alternative fuel source, such as coal, such that the pellets contain biomass-derived material and also an additional fuel source, such as coal.

[0121] When the term total fuel content of a solid fuel is used herein, it is intended to refer to the components of the solid fuel that are combustible materials, such as biomass-derived materials and coal. The term fuel content for a solid fuel is not intended to encompass additives that may be present in the solid fuel pellets that do not produce energy by their own combustion.

[0122] The molding step has also been found to enhance the waterproof properties of the final biomass solid fuel product. The increase in density that occurs during the molding step means that water is less likely to penetrate the denser molded biomass product particles. Furthermore, as the product densifies, more of the biomass is concentrated inside the molded body and is no longer in direct contact with water.

[0123] Solid Biomass Fuel Products The solid biomass fuel product can have any of the physical properties described above.

[0124] As described above, the biomass solid fuel of the present invention 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. As discussed above, it has surprisingly been found that the solid biomass fuel product of the present invention has enhanced waterproof characteristics compared to solid biomass fuel products made by prior art methods. This is believed to be due to the molding and / or heating steps being controlled as described above. The inventors have found that prior art biomass fuels are only sufficiently waterproof for a maximum of 10 days. In contrast, the solid biomass fuel product of the present invention has been found to be sufficiently waterproof for a maximum of 20 days, preferably 30 days, and more preferably 40 days.

[0125] The waterproofing properties of solid biomass fuel are determined by a standard test from the Energy Research Centre of the Netherlands (ECN), described in more detail below.

[0126] The moisture content of the biomass solid fuel of the present invention can also be determined by the standard ECN test method. The moisture content of the solid biomass fuel of the present invention is typically 5 to 9 wt %, preferably 6 to 8 wt %, and more preferably 6 to 7 wt %.

[0127] The solid biomass fuel of the present invention has also been found to have unexpectedly high mechanical durability. The mechanical durability is typically greater than 95%. This is advantageous because it has been found that biomass pellets with a mechanical durability of 95% or greater can be stored outdoors for as long as two months without damage. In contrast, biomass pellets with a mechanical durability of less than 95% are typically damaged by rainfall and cannot be stored outdoors. Thus, high mechanical durability is a further advantage of the biomass pellets of the present invention.

[0128] An additional benefit associated with the high durability of solid biomass fuel particles is that if the pellets are somehow broken by force, they will break down into larger pieces than pellets with lower mechanical durability, thereby minimizing the risk of dust explosions, if any.

[0129] As described above, in preferred embodiments, other than additives such as those described above, typically no other fuel source is added to the heated biomass product during the molding step. Thus, the solid biomass fuel typically contains only biomass-derived materials as fuel sources in the solid biomass fuel. For example, when the heated biomass product is molded into pellets, typically no other fuel source is added to the heated biomass product prior to molding, such that the solid biomass fuel pellets produced by the molding step contain only biomass-derived fuel sources.

[0130] Thus, in a preferred embodiment, the solid biomass fuel constitutes at least 50% by weight of the total fuel content of the fuel, for example at least 60%, at least 70%, at least 80%, at least 90%, preferably at least 95% by weight of biomass-derived material. When one or more biomass sources consist of or consist essentially of rice husks, the biomass solid fuel constitutes at least 95% by weight of the total fuel content of the fuel of biomass-derived material.

[0131] Typically, solid biomass fuel does not include an oxidizer, an ignition agent, or any combination thereof. For example, when formed into pellets, the solid biomass fuel pellets preferably do not include an ignition agent or an oxidizer, examples of which are known in the art, such as potassium permanganate. An advantage associated with the present invention is that solid biomass fuel does not require said ignition agent or oxidizer to burn effectively. Previously, when rice husks were used as a source of biomass in fuel products, it was necessary to include an ignition agent or oxidizer in the fuel to burn sufficiently.

[0132] Additionally, as noted above, preferably, the solid biomass fuel product of the present invention does not include an additional source of fuel, such as a fossil fuel, for example, coal. Previously, when rice husks were used as a source of biomass for fuel, the rice husks were combined with coal to effectively burn and provide sufficient energy during the combustion process. An unexpected advantage of the present invention is that the solid biomass fuel product does not need to include coal or any other additives to effectively burn or to provide sufficient energy during the combustion process.

[0133] Without being limited by theory, it is believed that the control of density during the molding step and the control of uniformity during the heating step discussed above provide the biomass solid fuel product of the present invention with superior performance characteristics, such that the product can be effectively combusted without the need to add oxidizer or igniter compound and coal during the molding step, such that the final biomass solid fuel pellets contain the coal and oxidizer or igniter compound along with the biomass.

[0134] Combustion method The products of the present invention can be used in a variety of different combustion processes. The suitability of the products for use in a particular process will be apparent to those skilled in the art. For example, the biomass fuels of the present invention may be used alone in a combustion process in a power plant or industrial process. Alternatively, the biomass products of the present invention may be used in a combustion process with additional fuel, such as coal, in a co-firing process.

[0135] Advantageously, the products of the present invention have been found to provide significantly lower PM1.0 emissions when compared to other biomass fuels known in the art. Additionally, the PM1.0 emissions of this process are lower than processes involving the combustion of coal.

[0136] Advantageously, it has been found that the improved physical properties of the biomass fuel of the present invention make the biomass particularly suitable for co-firing with coal. For example, the improved quality and uniformity of the product makes the biomass fuel of the present invention particularly well-suited for co-firing with coal. The improved waterproof properties of the biomass fuel of the present invention also mean that the biomass is particularly suitable for co-firing with coal, making it easier to store and transport due to its waterproof properties. [Example]

[0137] The method according to the present invention was carried out. The source of biomass was rice husks only. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated rice husks were cooled and then molded to obtain solid biomass fuel.

[0138] A photograph of the solid product is shown in FIG. [Example]

[0139] A method according to the present invention was carried out. The source of biomass was 75% by weight rice husk and 25% by weight mixed wood. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated biomass product was cooled and then molded to obtain solid biomass fuel. [Example]

[0140] A method according to the present invention was carried out. The biomass source was 50% by weight rice husk and 50% by weight mixed wood. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated biomass product was cooled and then molded to obtain solid biomass fuel. [Example]

[0141] A method according to the present invention was carried out. The source of biomass was 25% by weight rice husk and 75% by weight mixed wood. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated biomass product was cooled and then molded to obtain solid biomass fuel. [Example]

[0142] A method according to the present invention was carried out. The biomass source was 75% by weight rice husk and 25% by weight Calliandra carotylus. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated biomass product was cooled and then molded to obtain solid biomass fuel. [Example]

[0143] A method according to the present invention was carried out. The biomass source was 50% rice husk and 50% Calliandra carotylus by weight. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated biomass product was cooled and then molded to obtain solid biomass fuel. [Example]

[0144] A method according to the present invention was carried out. The biomass source was 25% by weight rice husk and 75% by weight Calliandra carotylus. The temperature of the heating step was 220°C to 280°C for a period of 0.4 to 2 hours. After the heating step, the heated biomass product was cooled and then molded to obtain solid biomass fuel.

[0145] Characterization of solid biomass fuels produced in Examples 1 to 7 The bulk densities (kg / L) of the solid biomass fuels prepared in Examples 1 to 7 were measured using DIN EN 15103 and are shown in FIG.

[0146] The durability of the solid biomass fuels prepared in Examples 1 to 7 was determined according to DIN EN 15210-1 and is shown in FIG.

[0147] The sulfur content of the solid biomass fuels prepared in Examples 1 to 7 is shown in Figure 8. The sulfur content is determined in accordance with DIN EN 15289.

[0148] The oxygen content of the solid biomass fuels prepared in Examples 1 to 7 is shown in Figure 9. The oxygen content was determined according to DIN EN 15296.

[0149] The carbon contents of the biomass solid fuels prepared in Examples 1 to 7 are shown in Figure 10. The carbon contents are determined in accordance with DIN EN 15104.

[0150] The nitrogen contents of the biomass solid fuels prepared in Examples 1 to 7 are shown in Figure 11. The nitrogen contents are determined in accordance with DIN EN 15104.

[0151] The fixed carbon contents of the biomass solid fuels prepared in Examples 1 to 7 are shown in Figure 12. The fixed carbon contents are determined in accordance with DIN EN 51734.

[0152] The ash contents of the biomass solid fuels prepared in Examples 1 to 7 are shown in Figure 13. The ash contents were determined according to DIN EN 14775 at 550°C.

[0153] The moisture content of the biomass solid fuels prepared in Examples 1 to 7 is shown in Figure 14. The water content was determined in accordance with DIN EN 14774-2.

[0154] The volatile matter contents of the solid biomass fuels prepared in Examples 1 to 7 are shown in Figure 15. The PM1.0 emissions of the biomass solid fuels produced in Examples 1 to 7 are shown in Figure 16. The PM1.0 emissions were determined by the standard method of the German ECN Testing Institute.

[0155] In the above diagram, the product of Example 1 is represented as A, the product of Example 2 is represented as B, the product of Example 3 is represented as C, the product of Example 4 is represented as D, the product of Example 5 is represented as E, the product of Example 6 is represented as F, and the product of Example 7 is represented as G. [Example]

[0156] The solid biomass fuel of Example 1 was tested in a climate experiment, exposing it to a climate chamber for 10 days, which is an ECN standard test for assessing the moisture content of biomass fuel particles.

[0157] The results of this test are shown in Figure 17. The results in Figure 17 show that the equilibrium moisture uptake of the biomass particles stabilized at 6-7 wt% after approximately 14 days of exposure at 27°C and 90% relative humidity. This indicates a low moisture content of the biomass fuel particles, which are very hydrophobic and highly water resistant compared to biomass solid fuels known in the art.

[0158] In a second experiment in a climatic chamber, biomass solid fuel was immersed in water at a temperature of 27°C for 15 minutes and exposed to the climatic chamber. After immersion in water, the moisture content of the sample was 90% by weight. After 10 days of exposure in the climatic chamber, the moisture content of the fuel stabilized at around 7.6%. The results are shown in Figures 18 and 19. Immersion of the particles had no effect on the equilibrium moisture content achieved after 10 days. [Example]

[0159] The climatic chamber experiments were repeated for the products of Examples 1-7.

[0160] Figure 20 shows the surface moisture content of the products of Examples 1 to 7. It can be seen that the surface moisture content of the biomass particles and the actual moisture content are very close.

[0161] In Figures 17-20, the values ​​on the y-axis are the weight percent of moisture in the biomass particles.

Claims

[Claim 1] 1. A method for producing solid biomass fuel, comprising: (i) providing one or more biomass powders having a particle size between 1000 μm and 10,000 μm; (ii) heating the one or more biomass powders to a temperature of from 160°C to 420°C for a period of from 0.25 to 5 hours to provide a heated biomass product; and (iii) molding the heated biomass product to provide a solid biomass fuel. P Including, The one or more biomass powders are derived from one or more biomass sources, the one or more biomass sources (i) consisting of or consisting essentially of rice husks; (ii) comprising or consisting essentially of a mixture of rice husks and wood, such as mixed wood; (iii) consisting of a mixture of rice husks and Calliandra carotylus; or (iv) comprising rice husks and Calliandra carotylus in an amount of at least 15% by weight; and when the one or more biomass sources consist of or consist essentially of rice husks, biomass-derived material is present in the solid biomass fuel in an amount of at least 95% by weight of the total fuel content of the solid biomass fuel.

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