Method for producing solid biomass fuel

Abstract

The present invention relates to a method for producing solid biomass fuel and the solid biomass fuel produced by said method. Additionally, the present invention relates to a combustion method comprising combusting said solid biomass fuel to produce energy.

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. Accordingly, 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, then formed into biomass blocks, which are then heated to form a biomass fuel. The aim of this method is to produce a biomass fuel that has sufficient handling properties during storage and has reduced chemical oxygen demand (COD) in the wastewater during storage. The biomass source used in this method is palm kernel shells.

[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 forming 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 shaping step in which a biomass source is crushed, then compressed and formed 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 and achieves reduced COD in wastewater when exposed to stormwater. The biomass source used in this method 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 shaped 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 heat applied to the carbonization furnace based on the spontaneous combustion characteristics of the biomass fuel. The shaped biomass product is formed by pulverizing a biomass source into pellets and then molding the pellets into a shaped 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, pine, and 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 inventors of the present invention recognize 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 inventors recognize that it would be advantageous to have a source of biomass that can be easily grown and harvested, or that can be utilized 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. It would also be advantageous to have an alternative biomass source that does not require large-scale logging to provide a sufficient amount of biomass for use as a fuel.

[0014] Additionally, the present 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 micronization techniques known in the art. Furthermore, micronizing biomass sources is expensive due to the difficult nature of wood and wood-like materials. The present inventors have recognized that it would be advantageous to have a biomass source that is more easily micronized by conventional micronization techniques known in the art and that forms particles of a more uniform size when micronized.

[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. The inventors of the present invention have surprisingly 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, the present inventors have also discovered that certain sources of biomass, which are agricultural waste products, can be used to produce solid biomass fuel.

[0019] In addition to the above, the present inventors have also discovered that by modifying the pulverizing, shaping, and / or heating steps of the method, biomass fuels with improved water resistance characteristics can be provided. It has also been discovered that adapting and controlling the pulverizing, shaping, and heating steps of the method of the present invention improves the quality and uniformity of the solid biomass fuel product and imparts certain physical characteristics to the solid biomass fuel product that are highly desirable for use in combustion processes. Furthermore, adapting the shaping and heating steps has been found to increase the yield of solid biomass fuel and to impart characteristics 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 pulverizing, 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 sources of biomass having an average particle diameter (D50) of 30,000 μm to 60,000 μm; (ii) micronizing one or more sources of biomass to provide a micronized biomass powder having an average particle diameter (D50) of 1000 μm to 10,000 μm; (iii) drying the micronized biomass powder to provide a dried micronized biomass powder; (iv) shaping the dried, micronized biomass powder to provide a shaped biomass product; (v) heating the formed biomass product to a temperature of 160°C to 420°C for 0.25 to 5 hours to provide a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel; Including, Methods are provided wherein the one or more sources of biomass include bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof.

[0021] Preferably, the one or more sources of biomass consist essentially of, or consist of, bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof.

[0022] Typically, step (i) of providing one or more sources of biomass having an average particle diameter (D50) of between 30,000 μm and 60,000 μm comprises chopping the one or more sources of biomass so as to have an average particle diameter (D50) of between 30,000 μm and 60,000 μm.

[0023] In an embodiment, step (ii) of micronizing one or more sources of biomass to provide a micronized biomass powder having an average particle diameter (D50) of 1000 μm to 10,000 μm comprises: (a) comminuting the one or more sources of biomass by a process involving the use of a negative pressure pneumatic conveying device, wherein the moisture content of the one or more sources of biomass is 20% by weight or less.

[0024] Typically, step (iii) of drying the micronized biomass powder to provide a dried micronized biomass powder comprises drying the micronized biomass in a drying cylinder.

[0025] In some embodiments, the pulverized biomass powder has a moisture content of 20% by weight or greater, and the method comprises drying the pulverized biomass in a plurality of drying cylinders.

[0026] In some embodiments, step (iii) of drying the micronized biomass powder to provide a dried micronized biomass powder further comprises mixing the micronized biomass powder particles while drying.

[0027] Typically, step (iv) of shaping the dry, finely divided biomass powder comprises adapting the shaping step to control the density of the shaped biomass product, and optionally, adapting the shaping step to control the density of the shaped biomass product comprises controlling the compression ratio of a mold used in said shaping step.

[0028] Typically, an additive is added to the dried compressed biomass powder prior to step (iv) of shaping the dry, micronized biomass powder. Preferably, the additive increases the yield of shaped biomass product.

[0029] Typically, the step (v) of heating the formed biomass product is carried out for a period of 0.4 to 2.5 hours, and / or the step of heating the formed biomass product comprises heating the formed biomass product to a temperature of from 180° C. to 350° C., optionally from 210° C. to 280° C. Preferably, the step (v) of heating the formed biomass product comprises heating the formed biomass product under conditions to induce torrefaction of the formed biomass product.

[0030] Typically, step (v) of heating the formed biomass product is adapted to control the uniformity of the solid biomass fuel, and optionally, adapting step (v) to control the uniformity of the solid biomass fuel comprises performing step (v) in an apparatus that rotates the formed biomass product while heating it, and optionally, adapting step (v) to control the uniformity of the solid biomass fuel comprises controlling the speed or direction of rotation of the formed biomass product, and optionally, rotating the formed biomass product in the apparatus in both counterclockwise and clockwise directions.

[0031] Preferably, the method further comprises the step of cooling the solid biomass fuel after the heating step (v) and before the step (vi) of removing dust particles from the solid biomass fuel.

[0032] Typically, step (vi) of removing dust particles from the solid biomass fuel comprises using a screen to remove the dust particles from the solid biomass fuel. Typically, the screen has a pore size of 2 mm to 8 mm, preferably the screen has a pore size of 2 mm to 5 mm, and more preferably the screen has a pore size of 2 mm to 3 mm. In some embodiments, a drum sieve is used as the screening device for removing dust particles from the solid biomass fuel, and preferably the drum sieve comprises a rotary drum sieve.

[0033] Alternatively, or in addition, step (vi) of removing dust particles from the solid biomass fuel comprises subjecting the solid biomass fuel to vibration, rotation, rolling, or any combination thereof. In some embodiments, step (vi) of removing dust particles from the solid biomass fuel comprises using a vibrating screen, wherein the vibrating screen has a pore size of 2 mm to 8 mm, preferably the screen has a pore size of 2 mm to 5 mm, and more preferably the screen has a pore size of 2 mm to 3 mm.

[0034] Typically, the bulk density of the solid biomass fuel, as determined by DIN EN 15103, is between 0.55 kg / l and 0.8 kg / l, preferably between 0.60 kg / l and 0.75 kg / l, more preferably between 0.60 and 0.70 kg / l.

[0035] Typically, the mechanical durability of solid biomass fuels, as determined by DIN EN 15210-1, is 90% or more, 93% or more, or 95% or more.

[0036] 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 bagasse, and the solid biomass fuel has a bulk density of 0.60 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; (ii) the one or more biomass sources include or consist essentially of sunflower stalks, and the solid biomass fuel has a bulk density of 0.60 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; (iii) the one or more biomass sources include or consist essentially of wheat stalk, and the solid biomass fuel has a bulk density of 0.58 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; (iv) the one or more biomass sources include or consist essentially of cornstalk, and the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 96% or greater; (v) the one or more biomass sources include or consist essentially of sorghum stalk, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 97% or greater; (vi) the one or more biomass sources include or consist essentially of soybean stalk, and the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 96% or greater; (vii) the one or more biomass sources include or consist essentially of peanut stalks, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.68 kg / L, and the mechanical durability of the solid biomass fuel is 97% or greater; (viii) the one or more biomass sources include or consist essentially of cotton stalk, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.68 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; (ix) the one or more biomass sources include or consist essentially of rapeseed stalk, the solid biomass fuel has a bulk density of 0.58 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; (x) the one or more biomass sources comprise or consist essentially of coconut husks, the solid biomass fuel has a bulk density of 0.62 kg / L to 0.72 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; (xi) the one or more biomass sources comprise or consist essentially of palm shells, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.70 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; (xii) the one or more biomass sources include or consist essentially of seaweed, and the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 96% or greater; (xiii) the one or more biomass sources include or consist essentially of peanut skins, the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 97% or greater; The bulk density is determined according to DIN EN 15103 and the mechanical durability according to DIN EN 15210-1.

[0037] Typically, the total dry sulfur content of the biomass solid fuel is 0.5 wt.% or less, preferably 0.45 wt.% or less, more preferably 0.40 wt.% or less, and most preferably 0.15% to 0.20%, the total dry sulfur content being determined according to DIN EN 15289.

[0038] Typically, the total dry hydrogen content of the biomass solid fuel is 3 wt.% or more, preferably 5 wt.% to 10 wt.%, more preferably 5 wt.% to 7 wt.%, the total dry hydrogen content being determined according to DIN EN 15104.

[0039] Typically, the total dry oxygen content of the biomass solid fuel is 20% by weight or more, preferably 25% to 42% by weight, more preferably 28% to 40% by weight, the total dry oxygen content being determined according to DIN EN 15296.

[0040] Typically, the total dry carbon content of the biomass solid fuel is 40% by weight or more, preferably 45% to 65% by weight, more preferably 50% to 60% by weight, the total dry carbon content being determined according to DIN EN 15104.

[0041] Typically, the total dry nitrogen content of the biomass solid fuel is less than 5.0 wt. %, preferably less than 3.0 wt. %, more preferably less than 2.5 wt. %, the total dry nitrogen content being determined according to DIN EN 15104.

[0042] Typically, the chemical oxygen demand (COD) of the solid biomass fuel when immersed in water is 5000 ppm or less, preferably 4000 ppm or less, and most preferably 3200 ppm or less, where the chemical oxygen demand is determined by GB / 11914-89.

[0043] Typically, the fixed carbon content of solid biomass fuel is 20% by weight or more, preferably 25% to 45% 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 20% by weight, preferably less than 18% by weight, more preferably less than 10% by weight, 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 35% and 80% by weight, more preferably between 40% and 80% by weight, and most preferably between 50% and 80% by weight, the volatile matter content being determined according to DIN EN 15148.

[0046] Typically, the internal moisture content of the solid biomass fuel is less than 8 wt.%, preferably less than 6 wt.%, more preferably less than 5 wt.%, the internal moisture content being determined according to DIN EN 14774.

[0047] Typically, the biomass solid fuel has a calorific value of 4300 kcal / kg to 6500 kcal / kg, preferably 4800 kcal / kg to 5800 kcal / kg, the calorific value being determined in accordance with DIN EN 14918.

[0048] Typically, the biomass solid fuel has a base moisture content of less than 10% by weight, preferably less than 8% by weight, and most preferably less than 6% by weight, the base moisture content being determined by GB / T 211-2017.

[0049] Typically, solid biomass fuels have a pH of 4-10.

[0050] Typically, the coke residue upon combustion of solid biomass fuel is 1-4, preferably 2-3.

[0051] Typically, the solid biomass fuel is water resistant for up to 20 days, preferably up to 30 days, and more preferably up to 40 days.

[0052] Typically, PM1.0 emissions when burning solid biomass fuels are less than 175 mg / kg, preferably less than 150 mg / kg.

[0053] Typically, the bulk density of the shaped biomass product is A and the bulk density of the biomass solid fuel is B, with B / A being 0.55 to 1, the bulk densities being determined according to DIN EN 15103.

[0054] Preferably, 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.

[0055] According to a second aspect of the present invention there is provided a solid biomass fuel obtainable or obtained by a method according to any of the preceding claims.

[0056] According to a third aspect of the present invention, there is provided a solid biomass fuel derived from one or more sources of biomass, the one or more sources of biomass comprising: (i) comprising, consisting of, or consisting essentially of bagasse; (ii) comprising, consisting of, or consisting essentially of sunflower stalks; (iii) comprising, consisting of, or consisting essentially of wheat stalk; (iv) comprising, consisting of, or consisting essentially of cornstalk; (v) comprising, consisting of, or consisting essentially of soybean stalk; (vi) comprising, consisting of, or consisting essentially of sorghum stalk; (vii) comprising, consisting of, or consisting essentially of peanut stalks; (viii) comprising, consisting of, or consisting essentially of cotton stalk; (ix) containing, consisting of, or consisting essentially of rapeseed stalk; (x) comprising, consisting of, or consisting essentially of coconut shell; (xi) Containing, consisting of, or consisting essentially of palm shells; (xii) Containing, consisting of, or consisting essentially of seaweed; or (xiii) Containing, consisting of, or consisting essentially of peanut skins; A solid biomass fuel is provided.

[0057] Preferably, the one or more sources of biomass or solid biomass fuel in the second and third aspects of the invention are as defined above according to the first aspect of the invention.

[0058] 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 or third aspects of the present invention to produce energy.

[0059] Preferably, the solid biomass fuel is co-fired and combusted together with a fossil fuel such as coal.

[0060] Preferably, the PM1.0 emissions of the method are less than 175 mg / kg, preferably less than 150 mg / kg.

[0061] Preferably, the coke residue upon combustion of the solid biomass fuel is 1-4, preferably 2-3.

[0062] According to a fifth aspect of the present invention there is provided the use of a solid biomass fuel according to the second or third aspect of the present invention as a fuel in a combustion process, optionally comprising using the solid biomass fuel in a method according to the fourth aspect of the present invention, optionally wherein the combustion method comprises co-firing the solid biomass fuel together with a fossil fuel such as coal.

[0063] Preferably, the PM1.0 emissions of the method are less than 175 mg / kg, preferably less than 150 mg / kg.

[0064] Preferably, the coke residue upon combustion of the solid biomass fuel is 1-4, preferably 2-3.

[0065] According to a sixth aspect of the present invention, there is provided use of one or more sources of biomass for producing solid biomass fuel, the one or more sources of biomass (i) comprising, consisting of or consisting essentially of bagasse, (ii) comprising, consisting of or consisting essentially of sunflower stalks, (iii) comprising, consisting of or consisting essentially of wheat stalks, (iv) comprising, consisting of or consisting essentially of corn stalks, (v) comprising, consisting of or consisting essentially of soybean stalks, (vi) comprising, consisting of or consisting essentially of sorghum stalks, or (vii) comprising, consisting of or consisting essentially of sorghum stalks. (vii) comprising, consisting of, or consisting essentially of peanut stalks; (viii) comprising, consisting of, or consisting essentially of cotton stalks; (ix) comprising, consisting of, or consisting essentially of rapeseed stalks; (x) comprising, consisting of, or consisting essentially of coconut shells; (xi) comprising, consisting of, or consisting essentially of palm shells; (xii) comprising, consisting of, or consisting essentially of seaweed; or (xiii) comprising, consisting of, or consisting essentially of peanut shells.

[0066] Preferably, the use comprises using one or more sources of biomass in a method according to the first aspect of the invention, and / or the solid biomass fuel is according to the second or third aspect of the invention.

[0067] According to a seventh aspect of the present invention there is provided a pretreatment method for pretreating one or more sources of biomass for use in producing solid biomass fuel, the method comprising: (i) providing one or more sources of biomass having an average particle diameter (D50) of between 30,000 μm and 60,000 μm; (ii) micronizing one or more sources of biomass to provide a micronized biomass powder having an average particle diameter (D50) of 1000 μm to 10,000 μm; (iii) drying the micronized biomass powder to provide a dried micronized biomass powder. Including, the one or more sources of biomass include bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof; A pretreatment method is provided.

[0068] Typically, step (i) of providing one or more sources of biomass having an average particle diameter (D50) of between 30,000 μm and 60,000 μm comprises chopping the one or more sources of biomass so as to have an average particle diameter (D50) of between 30,000 μm and 60,000 μm.

[0069] Typically, step (ii) of micronizing one or more sources of biomass to provide a micronized biomass powder having an average particle diameter (D50) of 1000 μm to 10,000 μm comprises: (a) comminuting the one or more sources of biomass by a process involving the use of a negative pressure pneumatic conveying device, wherein the moisture content of the one or more sources of biomass is 20% by weight or less.

[0070] Typically, step (iii) of drying the micronized biomass powder to provide a dried micronized biomass powder comprises drying the micronized biomass in a drying cylinder. Typically, if the moisture content of the micronized biomass powder is 20% by weight or less, the method comprises drying the micronized biomass in a single drying cylinder. Typically, if the moisture content of the micronized biomass powder is 20% by weight or more, the method comprises drying the micronized biomass in multiple drying cylinders.

[0071] Typically, step (iii) of drying the micronized biomass powder to provide a dried micronized biomass powder further comprises mixing the micronized biomass powder particles while drying.

[0072] Preferably, the one or more sources of biomass are as defined above according to the first aspect of the present invention.

[0073] Typically, the pretreatment method is carried out before the method of producing solid biomass fuel, which method comprises shaping or heating one or more sources of biomass, optionally the method being as defined above according to the first aspect of the present invention.

[0074] According to an eighth aspect of the present invention, there is provided a method for post-treating solid biomass fuel, comprising the step of removing dust particles from the solid biomass fuel, wherein the solid biomass fuel is derived from one or more sources of biomass, and the one or more sources of biomass comprise bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof.

[0075] Preferably, the step of removing dust particles from the solid biomass fuel comprises removing dust particles from the solid biomass fuel using a screen. Preferably, the screen has a pore size of 2mm to 8mm, preferably, the screen has a pore size of 2mm to 5mm, more preferably, the screen has a pore size of 2mm to 3mm.

[0076] Typically, a drum sieve is used as a screening device to remove dust particles from the solid biomass fuel, and preferably the drum sieve comprises a rotating drum sieve.

[0077] Additionally or alternatively, removing dust particles from the solid biomass fuel comprises subjecting the solid biomass fuel to vibration, rotation, rolling, or any combination thereof. In some embodiments, removing dust particles from the solid biomass fuel comprises using a vibrating screen, wherein the vibrating screen has a pore size of 2 mm to 8 mm, preferably, the screen has a pore size of 2 mm to 5 mm, and more preferably, the screen has a pore size of 2 mm to 3 mm.

[0078] Typically, the post-treatment method of the present invention is carried out after a method of producing solid biomass fuel, which method comprises shaping or heating one or more sources of biomass, optionally a method as defined above according to the first aspect of the present invention. [Brief explanation of the drawings]

[0079] The invention will now be described, by way of example only, with reference to the accompanying figures. [Figure 1] FIG. 1 shows the bulk density of various solid biomass fuels of the present invention as determined by DIN EN ISO 17828. [Figure 2] FIG. 1 shows the mechanical durability of various solid biomass fuels of the present invention as determined according to DIN EN 15210-1. [Figure 3] FIG. 1 shows the sulfur content of various biomass fuels of the present invention as determined according to DIN EN 15289. [Figure 4] FIG. 1 shows the dry hydrogen content of various biomass fuels of the present invention as determined according to DIN EN 15104. [Figure 5] FIG. 1 shows the dry oxygen content of various biomass fuels of the present invention as determined according to DIN EN 15296. [Figure 6] FIG. 1 shows the dry carbon content of various biomass fuels of the present invention as determined according to DIN EN 15104. [Figure 7]FIG. 1 shows the dry nitrogen content of various biomass fuels of the present invention as determined according to DIN EN 15104. [Figure 8] FIG. 1 shows the chemical oxygen demand (COD) of various biomass fuels of the present invention determined by GB11914-89. [Figure 9] FIG. 1 shows the fixed carbon content of various biomass fuels of the present invention as determined according to DIN EN 51734. [Figure 10] FIG. 1 shows the ash content of various biomass fuels of the present invention determined according to DIN EN 14775 at 550° C. [Figure 11] FIG. 1 shows the internal moisture content of various biomass fuels of the present invention as determined according to DIN EN 14774-2. [Figure 12] FIG. 1 shows the volatile matter content of various biomass fuels of the present invention as determined according to DIN EN 15148. [Figure 13] FIG. 1 shows PM1.0 emissions of various biomass fuels of the present invention as determined by the standard method of the German ECN Testing Institute. [Figure 14] FIG. 1 shows the calorific values ​​of various biomass fuels of the present invention as determined according to DIN EN 14918. [Figure 15] FIG. 1 shows the received base moisture content of various biomass fuels of the present invention as determined by GB / T 211-2017. [Figure 16] FIG. 1 shows the particle density of various biomass fuels of the present invention as determined according to DIN EN 18847. [Figure 17] FIG. 1 shows the pH of various biomass fuels of the present invention as determined by GB / T7702.16-1997. [Figure 18] FIG. 1 shows the coke slag characteristics of various biomass fuels of the present invention as determined by GB / T212-2008. [Figure 19]FIG. 1 shows the total moisture content of various biomass fuels of the present invention after soaking in water for 20 days, as determined by GB / T211-2017. [Figure 20] 1 is a photograph of an apparatus known in the art that can be used to chip one or more sources of biomass. [Figure 21] 1 is a photograph of an apparatus known in the art that can be used to compress one or more sources of biomass. [Figure 22] 1 is a photograph of an apparatus known in the art that can be used to compress one or more sources of biomass. [Figure 23] 1 is a photograph of an apparatus known in the art that can be used to compress one or more sources of biomass. [Figure 24] 1 is a schematic diagram of a typical compression mold that may be used in accordance with the present invention. [Figure 25] ~ [Figure 26] FIG. 1 illustrates an apparatus that can be used in vibrating, rolling, or rotating the biomass solid fuel product of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0080] Biomass Sources The one or more sources of biomass used in accordance with the present invention may be any of those discussed above. Typically, the one or more sources of biomass include agricultural waste. Many of the sources of biomass described above for use in accordance with the present invention may be agricultural waste. As used herein, the term "agricultural waste" refers to plant-based waste products that are typically generated as a by-product of agricultural operations. For example, agricultural waste may include harvested plant-based products or unwanted components of harvested plant-based products.

[0081] The biomass sources used in accordance with the present invention may be generated as agricultural waste, as a by-product of agricultural operations. Alternatively, these biomass sources may be grown specifically for the purpose of serving as feedstock for the preparation of biomass solid fuels. Corn stalks are a specific example of a material that may be generated as agricultural waste. For example, corn may be grown and harvested for human consumption. When processing corn plants for human consumption, processing may involve removing the edible corn from the inedible corn cob. Thus, corn cobs and stalks are agricultural waste products. In some embodiments, the one or more biomass sources comprise, consist of, or consist essentially of bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof. In a preferred embodiment, the one or more sources of biomass consist essentially of, or consist of, bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm husks, seaweed, peanut skins, or combinations thereof.

[0082] Each of the one or more sources of biomass discussed above can be obtained or harvested by conventional methods known in the art.

[0083] 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 that these components do not substantially affect the essential characteristics of the composition.

[0084] As discussed 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 characteristics 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.

[0085] The use of one or more biomass sources for use in the present invention has also surprisingly been found to be easier to mill than previously used materials such as wood, thereby reducing the cost of the milling process.

[0086] 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, it is believed that this imparts advantageous properties to the final solid fuel product, such as greater uniformity and continuity of the biomass fuel product. This is desirable in combustion processes for several reasons.

[0087] Preparation of one or more sources of biomass As discussed above, the methods of the present invention involve providing one or more sources of biomass having a mean particle diameter (D50) of between 30,000 μm and 60,000 μm.

[0088] One or more sources of biomass may be size reduced by standard techniques known in the art. The biomass may be size reduced so that the biomass has an average particle diameter (D50) of 30,000 μm to 60,000 μm, for example, an average particle diameter of 40,000 μm to 50,000 μm.

[0089] In some embodiments, one or more biomass sources are prepared into particles having a size in the above range by introduction into conventional chipping equipment, although this will, of course, depend on the particular biomass source. For example, if the biomass source is naturally occurring and the particles have a size in the above range, chipping would not be necessary. Thus, in some embodiments, the methods of the present invention may include chopping one or more biomass sources to have an average particle diameter (D50) of 30,000 μm to 60,000 μm.

[0090] In some embodiments, the step of providing one or more biomass sources having an average particle diameter (D50) of 30,000 μm to 60,000 μm may include harvesting the one or more biomass sources with a conventional combine. The combining process involves chopping and breaking down the one or more biomass sources into particles of a desired size.

[0091] The step of providing one or more biomass sources having an average particle diameter (D50) of 30,000 μm to 60,000 μm may further include reducing the moisture content of the biomass to less than 50% by weight. Such a step may include compressing the one or more biomass sources. This compressing step typically involves squeezing water from the one or more biomass sources such that the moisture content of the one or more biomass sources is reduced to less than 50% by weight. Thus, in some embodiments, providing biomass having the particle sizes discussed above includes compressing one or more biomass sources having a moisture content of greater than 70% by weight such that, after compression, the moisture content of the one or more biomass sources is less than 50% by weight.

[0092] In some embodiments, the step of providing biomass having the particle sizes discussed above includes both compressing the biomass and also chopping the biomass.

[0093] The chopping step and the compression step (if included) may be performed using separate equipment. Alternatively, these steps may be performed in a single device configured for both chipping and compressing biomass. For example, a motorized rolling device suitable for compressing biomass may be mounted on a conveyor belt feeding a conventional chipping device. In this regard, the biomass source is compressed before entering the chipper. Suitable devices for performing the steps of compressing and chipping one or more biomass sources are known in the art. An example of an apparatus used for chipping is shown in FIG. 20. Chipping devices such as that shown in FIG. 20 typically operate on the principle that material enters the chipper via a conveying system, such as a conveyor belt, which feeds the material through a feed port. The material is then cut into chips by high-speed rotating blades (not shown) and blades (not shown) attached to the base of the machine. The function of these and similar chipping mechanisms is known to those skilled in the art.

[0094] An example of the apparatus used for the compression step is shown in FIG.

[0095] As discussed above, in some embodiments, a rolling device such as that shown in FIG. 21 can be placed on a conveyor belt to compress the source material before it enters a chipping device such as that shown in FIG. 20.

[0096] In other embodiments, the step of providing the one or more sources of biomass does not include compressing the one or more sources of biomass and / or does not include reducing the moisture content of the one or more sources of biomass.

[0097] Biomass pulverization Step (ii) involves micronizing one or more sources of biomass to provide a micronized biomass powder having a mean particle diameter (D50) of between 1000 μm and 10,000 μm.

[0098] 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. Preferably, one or more biomass sources are micronized to have an average particle diameter of 1000 μm to 8000 μm, more preferably 1000 to 5000 μm. As discussed above, it has been found that micronizing certain biomass sources for use in the present invention provides biomass powders with advantageous particle size distributions that are smaller than those provided by milling previously known biomass sources.

[0099] It has further been found that smaller particles of pulverized biomass powder improve the quality and performance characteristics of the biomass solid fuel product. Without being limited by theory, this is believed to be due to greater uniformity and homogeneity of the final solid biomass fuel product. It is believed that the smaller powder particle size and greater uniformity and homogeneity of the final fuel product leads to improved performance characteristics during fuel combustion and improved waterproofing characteristics of the solid fuel product.

[0100] Prior to micronization, the one or more biomass sources having a mean particle diameter (D50) of 30,000 μm to 60,000 μm typically contain less than 50% moisture by weight.

[0101] For different biomass sources having different moisture contents, different pulverization methods are preferred. For example, when one or more biomass sources have a moisture content of 20% by weight or less, the step of pulverizing the biomass preferably involves the use of a negative pressure pneumatic conveying device. Such negative pressure pneumatic conveying devices are known in the art.

[0102] If the moisture content of the one or more biomass sources is 20% by weight or greater, the one or more biomass sources may be pulverized directly without the use of a negative pressure pneumatic conveying device.

[0103] After micronizing one or more sources of biomass to provide a micronized biomass powder having an average particle diameter (D50) of 1000 μm to 10,000 μm, in some embodiments, the methods of the present invention may include compressing the biomass powder prior to the drying step, discussed in more detail below. For example, compressing the biomass after micronization may be desirable if the biomass powder has a moisture content greater than 30% by weight, although compression may also be performed on biomass powders having lower moisture contents.

[0104] The compacting step can involve compacting the biomass powder using suitable equipment known in the art. An example of such equipment is shown in Figure 22. Such equipment operates by compacting the biomass powder with a hydraulic compacting device. The material can be inserted into a meshed container as shown in Figure 22. The material can then be subjected to hydraulic compaction with the hydraulic compacting device, with water exiting the meshed container through the holes in the mesh.

[0105] Another device that can be used to compress biomass powder is the screw water press, shown in Figure 23. The material to be compressed is introduced into a spiral extrusion vessel. The water from the material is squeezed through a screen mesh by the rotation of a motor-driven spiral screw.

[0106] It has been found that performing the compression step after pulverizing the biomass as discussed above provides a compressed biomass powder with a lower moisture content. Typically, the moisture content of the compressed biomass powder is less than 30% by weight, for example, less than 25% by weight, or less than 20% by weight. Reducing the moisture content of the biomass during the compression step may be desirable so that the biomass has a lower moisture content at the start of the subsequent drying step. This speeds up the drying step because less moisture needs to be removed from the biomass. However, as discussed above, it will be understood that it is not necessary to compress the pulverized biomass powder before drying.

[0107] In other embodiments, the methods of the present invention do not include compressing the finely pulverized biomass powder and / or do not include reducing the moisture content of the finely pulverized biomass powder.

[0108] Thus, in some embodiments, the methods of the present invention do not include any compression step. Advantageously, it has been found that no compression step is necessary during the formation of solid biomass fuel from one or more sources of biomass, where the one or more sources of biomass are as defined above. This is in contrast to other sources of biomass that can be used to produce biomass solid fuel, such as grasses, which typically require compression to reduce the moisture content during processing into solid biomass fuel.

[0109] Washing of pulverized biomass powder Optionally, after pulverizing one or more biomass sources to form a pulverized biomass powder, the pulverized biomass powder can be washed. Any suitable washing liquid can be used. Examples of washing liquids include aqueous washing liquids such as water. The inventors have found that washing steps are advantageous in removing minerals from the biomass, such as salts containing potassium, sodium, chlorine, calcium, and phosphorus. A reduced mineral content in the biomass powder facilitates the heating (torrefaction) process described below and the combustion of the solid biomass fuel after formation. Examples of washing steps that can be used include the pre-washing steps discussed in WO 2013 / 162355.

[0110] Drying of pulverized biomass powder In step (iii) of this method, the biomass is dried. Step (iii) of drying the micronized biomass powder to provide a dry micronized biomass powder typically involves drying the micronized biomass powder so that the dry micronized biomass powder has a moisture content of 10% to 18% by weight, preferably 12% to 15% by weight. However, it will be understood that it is not necessary for the dry micronized biomass powder to have a moisture content within this range.

[0111] The step of drying the biomass powder may also include mixing the micronized biomass powder. If the method uses one type of biomass source, the single biomass source may be mixed. Alternatively, if the method uses two or more biomass sources, the drying step can involve mixing the micronized biomass powder with one or more additional biomass sources. For example, if the one or more biomass sources include at least two biomass sources, two or more biomass sources can be mixed during any step of the method of the invention, but preferably, the one or more biomass sources are mixed during the drying step of the method of the invention. In some embodiments, the micronized biomass powder is mixed with an additional biomass source that is also a micronized biomass powder prepared using the method steps described herein. In other embodiments, the one or more additional biomass sources are not processed as described herein. For example, micronized biomass powder prepared as described herein may be mixed with one or more additional sources of biomass prepared by different methods.

[0112] The pulverized biomass powder may be dried using any suitable method, such as using a standard drying cylinder known in the art. For example, in some embodiments, the drying step is carried out in a drying apparatus including a rotary drying drum. Rotation of the rotary drying drum can be used to mix the pulverized biomass powder with one or more additional biomass sources described above. Typically, the rotary drying drum includes a lifting plate, which continuously lifts materials while rotating the drying cylinder. Surprisingly, the inventors of the present invention have found that using a rotary drying cylinder with a lifting plate to dry one or more biomass powders with additional materials or to mix two or more biomass powders improves mixing of the one or more biomass powders.

[0113] In embodiments where the finely divided biomass powder has a moisture content of less than 20% by weight, the finely divided biomass powder is typically dried in a single drying cylinder. Thus, in these embodiments, the method of the present invention involves drying the finely divided biomass powder in only one single drying cylinder.

[0114] In embodiments where the finely divided biomass powder has a moisture content of greater than 20% by weight, the finely divided biomass powder is typically dried in multiple drying cylinders. Thus, in these embodiments, the method of the invention includes drying the finely divided biomass powder in two or more drying cylinders. For example, the method may include drying the finely divided biomass powder in two or more, three or more, four or more, four or five, or five or six drying cylinders.

[0115] Molding of dried pulverized biomass powder The dried, pulverized biomass powder is shaped to provide a shaped biomass product. The shaping step may be carried out in any shaping device known in the art, according to biomass shaping techniques known in the art, and may include an extrusion molding system. Preferably, the shaping step is carried out in a compression mold. Preferably, the compression mold includes a molded product exit hole. The shaping step may be carried out using the device described in Chinese Patent No. 105435708.

[0116] Preferably, the shaping step comprises shaping the dry pulverized biomass powder into pellets. Thus, in a preferred embodiment, the shaped biomass product and the solid biomass fuel product comprise biomass pellets.

[0117] While forming biomass powder to produce a formed biomass product is known, the present inventors have surprisingly discovered that adapting the forming step to control the density of the formed biomass product produced therefrom within a specific range can impart certain advantageous properties to the final solid biomass fuel product. In particular, controlling the forming step to provide a formed biomass product with a density within a range of 1.0 to 1.35 kg / L can impart advantageous properties to the final biomass fuel product. Preferably, the forming step is controlled to provide a formed biomass product with a density within a range of 1.0 to 1.35 kg / L. Typically, the density is determined in accordance with NY / T 1881.7-2010. Accordingly, in some embodiments, the forming step is controlled to provide a formed biomass product with a density within a range of 1.0 to 1.35 kg / L, the density being determined in accordance with NY / T 1881.7-2010.

[0118] The shaping step can be controlled in a variety of ways. When the shaping process involves the use of a compression mold, density is typically controlled by using a compression ratio of less than 8, preferably less than 7, and more preferably less than 6. In a highly preferred embodiment, a compression ratio of 3.8 to 6.5 is used. Typically, the lower the compression ratio, the lower the density of the shaped biomass product. However, the higher the compression ratio, the lower the yield of the shaped biomass product.

[0119] The compression ratio for a compression mold having a compaction exit hole can be defined as the ratio of the length to the diameter of the compaction exit hole.

[0120] Figure 24 shows an example of a compression mold that can be used in accordance with the present invention. After the dry pulverized biomass product is inserted into the mold, it is forced out of the mold by pressure, exiting the mold exit holes shown in the figure. The pressure ratio is shown in the figure as the ratio of the length to the diameter of the mold exit holes.

[0121] In the method of the present invention, step (iv) of compacting the dried pulverized biomass powder preferably includes adapting the compacting step so that the density of the compacted biomass product is controlled within the range of 1.1 kg / L to 1.35 kg / L, typically determined according to NY / T 1881.7-2010. Preferably, the density is controlled using a compaction mold and by controlling the compaction ratio of the compaction mold. More preferably, the compaction ratio is 3.8 to 6.5.

[0122] Controlling the density of the molded biomass product during the molding step has surprisingly been found to provide the final biomass fuel product with increased water resistance. Preferably, solid biomass fuel products produced from molded biomass products having densities in the range of 1.1 kg / L to 1.35 kg / L are sufficiently water resistant for up to 20 days, preferably up to 30 days.

[0123] Preferably, an additive is added to the dry, micronized biomass powder prior to shaping the dry, micronized biomass powder in step (iv). The additive is believed to improve the shaping process and increase the yield of shaped biomass product produced from the shaping step. Suitable additives are known in the art and include, but are not limited to, starch or starch derivatives.

[0124] Typically, other than additives such as those discussed above, no other fuel source is added to the dry pulverized biomass powder during the shaping step. Thus, the shaped biomass product of the shaping step typically contains only biomass-derived materials as the fuel source in the solid biomass fuel. For example, when shaping dry pulverized biomass powder into pellets, typically no other fuel source is added to the dry pulverized biomass product before shaping, so that the solid biomass fuel pellets produced at the end of the method 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.

[0125] 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.

[0126] The shaping step has also been found to enhance the water-resistant properties of the final biomass solid fuel product: the increase in density that occurs during the shaping step means that water is less likely to penetrate the denser shaped biomass product particles.

[0127] Furthermore, as the product densifies, more biomass is concentrated inside the extrusion and is no longer in direct contact with water.

[0128] Heating of molded biomass products The formed biomass product is heated to produce a solid biomass fuel. Heating is carried out for 0.25 to 5 hours at a temperature of 160°C to 420°C. Preferably, the step of heating the formed biomass product is carried out for 0.4 to 2 hours. Preferably, the step of heating the formed biomass product includes heating the formed biomass product to a temperature of 180°C to 350°C, more preferably to a temperature of 210°C to 280°C.

[0129] Preferably, step (v) of heating the formed biomass product comprises heating the formed biomass product under conditions to induce torrefaction of the formed biomass product. 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 (v) of heating the formed biomass product comprises torrefaction.

[0130] The heating step may be carried out in any apparatus known in the art suitable for heating shaped biomass products, for example, the heating step may be carried out in the apparatus and using the process conditions disclosed in EP 3287509 A1.

[0131] Preferably, step (v) of heating the formed biomass product is adapted to control the uniformity of the solid biomass fuel, and optionally, adapting step (v) to control the uniformity of the solid biomass fuel comprises performing step (v) in an apparatus that rotates the formed biomass product while heating it, and optionally, adapting step (v) to control the uniformity of the solid biomass fuel comprises controlling the speed or direction of rotation of the formed biomass product, and optionally, rotating the formed biomass product in both counterclockwise and clockwise directions in the apparatus. The uniformity of the solid biomass fuel is also optimized by the heating temperature and duration discussed above.

[0132] In some embodiments, the method of the present invention may include a step of cooling the solid biomass fuel after heating. When the method of the present invention includes a cooling step after the step of heating the biomass, the cooling step may include rotating the solid biomass fuel. The biomass may be rotated in a suitable apparatus, such as that disclosed in EP 3287509 A1. Preferably, both the heating step (v) and the step of cooling the biomass include rotating the biomass. If the biomass is rotated in either the cooling step or the heating step, the biomass may be rotated in different directions, such as both clockwise and counterclockwise, in successive cycles.

[0133] The term "uniformity" of a solid biomass product is used to refer to a solid biomass fuel or formed biomass product having constant or similar properties across each particle of the solid biomass fuel or formed biomass product, and across multiple particles within a bulk sample of the solid biomass fuel product or formed 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.

[0134] The inventors have also discovered that controlling the heating step as discussed above further assists in providing a solid biomass fuel product with enhanced water-resistant 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 said particles.

[0135] Removal of dust particles from solid biomass fuels. The method of the present invention involves removing dust particles from solid biomass fuel. The inventors of the present invention have found that in biomass solid fuel production methods known in the art, a significant amount of dust adheres to the solid biomass fuel. This dust is problematic because it can pollute the atmosphere during transportation and packaging of the solid biomass fuel. The dust can also pollute the local environment. Furthermore, when stored in the open air, the dust particles can form mildew, affecting the performance and quality of the solid biomass fuel. Therefore, it would be beneficial to remove dust from the surface of the particles of the solid biomass fuel.

[0136] The inventors have found that dust on the surface of biomass solid fuel particles can be removed by inducing friction between the particles. For example, dust adhering to the particles can be removed by inducing friction by means of vibrating or rotating the solid biomass fuel particles. Thus, step (vi) of removing dust from the solid biomass particles may include inducing friction between the particles of the solid biomass fuel. For example, step (vi) of removing dust from the solid biomass particles may include subjecting the particles to vibration, rotation, rolling, or any combination thereof. Suitable devices for performing rolling, rotation, and vibration of solid biomass fuel particles are known to those skilled in the art and are shown in Figures 25 and 26. One example of a device that can be used to remove dust from particles is a rotary drum sieve.

[0137] Step (vi) of removing dust particles from the solid biomass fuel may include using a screen to remove the dust particles from the solid biomass fuel. Typically, the screen has a pore size of 2 mm to 10 mm, preferably 2 mm to 8 mm, more preferably 2 mm to 5 mm, and most preferably 2 mm to 3 mm. Dust particles mixed with the solid biomass fuel particles can be separated from the solid biomass fuel by passing through the screen. Larger solid biomass fuel particles do not pass through the screen and are therefore separated from the dust particles. Suitable devices and methods for performing the screening step are known to those skilled in the art, and any of the suitable devices may be used. For example, a device that uses screening, rolling, and rotation of the solid biomass fuel may be used to remove dust particles from the solid biomass fuel. In using such a device, the solid biomass fuel may be placed on the screen, and the screen may be driven by the operation of a motor to roll and rotate on an axis. During the rolling / tilting and rotation of the screen, material on the sieving surface of the screen is turned over. Some material passes through the screen and is separated from material that does not pass through the screen. The rolling and rotation of the screen causes material trapped in the gaps in the screen to fall, thereby preventing clogging of the gaps in the screen. Alternatively, a device for vibrating and screening solid biomass fuel particles can be used. In this case, a motor can be used to vibrate the screen, which throws up material on the screen surface. This process loosens small particles that are attached to larger particles, which can then pass through the gaps in the screen. An example of a device that uses a screen and vibration to separate large particles from small particles, which may or may not be attached to the larger particles, is the device taught in China Utility Model Registration No. 201324717.

[0138] Therefore, the method of the present invention may include a step of subjecting the solid biomass fuel particles to one or more of rolling, rotating, and vibrating so as to induce friction between the solid biomass fuel particles, thereby removing dust particles adhering to the solid biomass fuel particles from the particles. The method then preferably includes subjecting the mixture of solid biomass fuel particles and dust particles to the screening step discussed above to remove the dust particles from the solid biomass fuel particles. Therefore, the removal step (vi) is an effective post-treatment for removing dust from the solid biomass fuel particles.

[0139] Pre- and post-treatment Steps (iv) and (v), discussed above, of shaping and heating to form a solid biomass fuel, can typically be considered the primary production steps that convert one or more sources of biomass into a solid biomass fuel.

[0140] In contrast, steps (i)-(iii) of preparing, pulverizing, and drying biomass can be considered a method of pretreating one or more sources of biomass prior to converting said one or more sources of biomass (in processed form as dried, pulverized biomass powder) into solid biomass fuel through shaping and heating. Accordingly, the present invention provides a pretreatment method as discussed above. The pretreatment method comprises steps (i)-(iii) of preparing, pulverizing, and drying biomass. These steps may be the same as steps (i)-(iii) discussed above in the context of the method of the present invention for producing solid biomass fuel.

[0141] The pretreatment method of the present invention is preferably carried out before steps (iv)-(vi) discussed above, which are the methods for making solid biomass fuel. However, this is not required, and the pretreatment method of the present invention may be carried out before any method for converting one or more sources of biomass into solid biomass fuel. Preferably, the pretreatment method is carried out before a method for producing solid biomass fuel that includes a shaping step, a heating step, or both a shaping and heating step.

[0142] As used herein, the term "pretreatment" refers to a process performed to condition a starting material in a process for converting one or more sources of biomass into a solid biomass fuel. Preferably, the term "pretreatment" refers to treating a biomass source starting material prior to a process for converting the biomass source into a solid biomass fuel, wherein the process involves a shaping or heating step.

[0143] The above-discussed step (vi) of removing dust particles from the solid biomass fuel can be considered a post-treatment step of the solid biomass fuel. Accordingly, the present invention provides the above-discussed post-treatment method.

[0144] The post-processing method of the present invention preferably occurs after steps (iv)-(v) or steps (i)-(v) discussed above, which are the methods for making solid biomass fuel. However, this is not required, and the post-processing method of the present invention may occur after any method for converting one or more sources of biomass into solid biomass fuel. Preferably, the post-processing method occurs after a method for producing solid biomass fuel that includes a shaping step, a heating step, or both a shaping and heating step.

[0145] As used herein, the term "post-processing" refers to processes performed on a solid biomass fuel after it has been produced from one or more biomass sources. Preferably, the term "post-processing" refers to treating a solid biomass fuel starting material after a process that converts a biomass source into said solid biomass fuel, where said process involves a shaping step or a heating step.

[0146] Solid Biomass Fuel Products The solid biomass fuel product can have any of the physical properties discussed above.

[0147] As discussed 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 water resistance characteristics compared to solid biomass fuel products made by prior art methods. This is believed to be due to the fact that the pulverizing, molding, and / or heating steps are controlled as discussed above. The inventors have found that prior art biomass fuels are only sufficiently water-resistant for a maximum of 10 days. In contrast, the solid biomass fuel product of the present invention has been found to be sufficiently water-resistant for a maximum of 20 days, preferably 30 days, and more preferably 40 days.

[0148] The water resistance properties of solid biomass fuels can be determined by standard tests from the Energy Research Centre of the Netherlands (ECN).

[0149] The moisture content of the biomass solid fuel of the present invention can also be determined by the standard ECN test method. The internal moisture content of the solid biomass fuel of the present invention is typically less than 8 wt%, preferably less than 6 wt%, more preferably less than 5 wt%, the internal moisture content being determined according to DIN EN 14774.

[0150] Biomass solid fuels typically have a base moisture content of less than 10% by weight, preferably less than 8% by weight, and most preferably less than 6% by weight, as determined by GB / T211-2017.

[0151] 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 90%, preferably 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 90% are typically damaged by rain and cannot be stored outdoors. Thus, high mechanical durability is a further advantage of the biomass pellets of the present invention.

[0152] 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.

[0153] As discussed above, in preferred embodiments, other fuel sources are typically not added to the heated biomass product during the shaping step, other than additives such as those discussed above. 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 shaped into pellets, other fuel sources are typically not added to the heated biomass product prior to shaping, such that the solid biomass fuel pellets produced by the shaping step contain only biomass-derived fuel sources.

[0154] Thus, in preferred embodiments, the solid biomass fuel constitutes at least 50% by weight of the total fuel content of the fuel, for example at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, preferably at least 95% by weight of biomass-derived material.

[0155] 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.

[0156] 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.

[0157] 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 water resistance 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 water-resistant nature. [Example]

[0158] A method according to the present invention was carried out. The source of biomass was bagasse alone. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.60 to 0.65 kg / L as determined by DIN EN 15103. [Example]

[0159] The method according to the present invention was carried out. The source of biomass was sunflower stalks only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.60 to 0.65 kg / L as determined by DIN EN 15103. [Example]

[0160] The method according to the present invention was carried out. The source of biomass was wheat stalks only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.58 to 0.65 kg / L as determined by DIN EN 15103. [Example]

[0161] The method according to the present invention was carried out. The source of biomass was corn stalk only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.61 to 0.66 kg / L as determined by DIN EN 15103. [Example]

[0162] The method according to the present invention was carried out. The source of biomass was sorghum stalk only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.62 to 0.66 kg / L as determined by DIN EN 15103. [Example]

[0163] The method according to the present invention was carried out. The source of biomass was soybean stalks only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.61 to 0.66 kg / L as determined by DIN EN 15103. [Example]

[0164] A method according to the present invention was carried out. The source of biomass was peanut stalks only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.62 to 0.68 kg / L as determined by DIN EN 15103. [Example]

[0165] The method according to the present invention was carried out. The source of biomass was cotton stalk only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.62 to 0.68 kg / L as determined by DIN EN 15103. [Example]

[0166] The method according to the present invention was carried out. The source of biomass was rapeseed stalk only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.58 to 0.65 kg / L as determined by DIN EN 15103. [Example]

[0167] The method according to the present invention was carried out. The source of biomass was coconut shells only. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.62 to 0.72 kg / L as determined by DIN EN 15103. [Example]

[0168] A method according to the present invention was carried out. The biomass source was palm shells only. The heating step temperature was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.62 to 0.70 kg / L as determined by DIN EN 15103. [Example]

[0169] A method according to the present invention was carried out. The source of biomass was seaweed alone. The temperature of the heating step was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.61 to 0.66 kg / L as determined by DIN EN 15103. [Example]

[0170] A method according to the present invention was carried out. The source of biomass was peanut skins only. The heating step temperature was 220°C to 280°C for 0.4 to 2 hours. After the heating step, the solid biomass fuel product was cooled. The solid biomass fuel had a bulk density of 0.61 to 0.66 kg / L as determined by DIN EN 15103.

[0171] Characterization of the solid biomass fuel products produced in Examples 1-13 is shown in Figures 1-18. In these figures, A corresponds to the product of Example 1, B corresponds to the product of Example 2, C corresponds to the product of Example 3, D corresponds to the product of Example 4, E corresponds to the product of Example 5, F corresponds to the product of Example 6, G corresponds to the product of Example 7, H corresponds to the product of Example 8, I corresponds to the product of Example 9, J corresponds to the product of Example 10, K corresponds to the product of Example 11, L corresponds to the product of Example 12, and M corresponds to the product of Example 13.

[0172] FIG. 19 shows the total moisture content of the biomass fuel of the example after immersion in water for 20 days.

Claims

1. 1. A method for producing solid biomass fuel, comprising: (i) providing one or more sources of biomass having an average particle diameter (D50) of 30,000 μm to 60,000 μm; (ii) micronizing the one or more sources of biomass to provide a micronized biomass powder having an average particle diameter (D50) of 1000 μm to 10,000 μm; (iii) drying the micronized biomass powder to provide a dried micronized biomass powder; (iv) compacting the dried, pulverized biomass powder using a compaction mold to provide a compacted biomass product having a bulk density of 1.1 kg / L to 1.35 kg / L, wherein the density of the compacted biomass product is controlled by using a compaction ratio of the compaction mold of 3.8 to 6.5; (v) heating the formed biomass product to a temperature of 160°C to 420°C for 0.25 to 5 hours to provide a solid biomass fuel; and (vi) removing dust particles from the solid biomass fuel; Including, The method, wherein the one or more sources of biomass comprise bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof.

2. 10. The method of claim 1, wherein the one or more sources of biomass consist essentially of, or consist of, bagasse, sunflower stalks, wheat stalks, corn stalks, sorghum stalks, soybean stalks, peanut stalks, cotton stalks, rapeseed stalks, coconut shells, palm shells, seaweed, peanut skins, or combinations thereof.

3. 10. The method of claim 1, wherein step (i) of providing one or more sources of biomass having an average particle diameter (D50) of 30,000 μm to 60,000 μm comprises chopping the one or more sources of biomass to have an average particle diameter (D50) of 30,000 μm to 60,000 μm.

4. drying the micronized biomass powder to provide a dried micronized biomass powder; 10. The method of claim 1, wherein iii) comprises drying the pulverized biomass in a drying cylinder, (i) the pulverized biomass powder has a moisture content of 20% by weight or less, and the method comprises drying the pulverized biomass in a single drying cylinder; or (ii) the pulverized biomass powder has a moisture content of 20% by weight or greater, and the method includes drying the pulverized biomass in a plurality of drying cylinders; The method.

5. 10. The method of claim 1, wherein the step (v) of heating the formed biomass product is carried out for 0.4 to 2.5 hours, and wherein heating the formed biomass product comprises heating the formed biomass product to a temperature of 180°C to 350°C.

6. 10. The method of claim 1, wherein step (v) of heating the formed biomass product is adapted to control the uniformity of the solid biomass fuel, and wherein adapting step (v) to control the uniformity of the solid biomass fuel comprises performing step (v) in an apparatus that rotates the formed biomass product while heating it.

7. 7. The method of claim 6, wherein adapting step (v) to control the uniformity of the solid biomass fuel comprises controlling a speed or direction of rotation of the shaped biomass product.

8. 10. The method of claim 1, wherein the step (vi) of removing dust particles from the solid biomass fuel comprises removing dust particles from the solid biomass fuel using a screen having a pore size of between 2 mm and 8 mm.

9. 9. The method of claim 8, wherein step (vi) of removing dust particles from the solid biomass fuel comprises subjecting the solid biomass fuel to vibration, rotation, rolling, or any combination thereof.

10. 2. The method of claim 1, wherein the bulk density of the solid biomass fuel, determined according to DIN EN 15103, is between 0.55 kg / l and 0.8 kg / l, and / or the mechanical durability of the solid biomass fuel, determined according to DIN EN 15210-1, is 90% or more.

11. (i) the one or more biomass sources comprise or consist essentially of bagasse, and the solid biomass fuel has a bulk density of 0.60 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; (ii) the one or more biomass sources comprise or consist essentially of sunflower stalks, and the solid biomass fuel has a bulk density of 0.60 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; or (iii) the one or more biomass sources include or consist essentially of wheat stalk, and the solid biomass fuel has a bulk density of 0.58 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 95% or greater; or (iv) the one or more biomass sources include or consist essentially of cornstalk, and the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 96% or greater; or (v) the one or more biomass sources include or consist essentially of sorghum stalk, and the solid biomass fuel has a yield of between 0.62 kg / L and 0.66 kg / L. L bulk density, and the mechanical durability of the solid biomass fuel is 97% or more; (vi) the one or more biomass sources include or consist essentially of soybean stalk, and the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 96% or greater; (vii) the one or more biomass sources include or consist essentially of peanut stalks, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.68 kg / L, and the mechanical durability of the solid biomass fuel is 97% or greater; (viii) the one or more biomass sources include or consist essentially of cotton stalk, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.68 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; or (ix) the one or more biomass sources comprise or consist essentially of rapeseed stalk, and the solid biomass fuel has a bulk density of 0.58 kg / L to 0.65 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; (x) one or more biomass sources comprise or consist essentially of coconut husks, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.72 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; or (xi) the one or more biomass sources comprise or consist essentially of palm shells, and the solid biomass fuel has a bulk density of 0.62 kg / L to 0.70 kg / L, and the mechanical durability of the solid biomass fuel is 98% or greater; (xii) the one or more biomass sources comprise or consist essentially of seaweed, and the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 96% or greater; or (xiii) the one or more biomass sources comprise or consist essentially of peanut skins, the solid biomass fuel has a bulk density of 0.61 kg / L to 0.66 kg / L, and the mechanical durability of the solid biomass fuel is 97% or greater; 2. The method of claim 1, wherein the bulk density is determined according to DIN EN 15103 and the mechanical durability is determined according to DIN EN 15210-1.

12. (i) the total dry sulfur content of the biomass solid fuel is less than or equal to 0.5% by weight, the total dry sulfur content being determined according to DIN EN 15289; (ii) the total dry hydrogen content of the biomass solid fuel is greater than or equal to 3% by weight, the total dry hydrogen content being determined according to DIN EN 15289; (iii) the total dry oxygen content of the biomass solid fuel is equal to or greater than 20% by weight, the total dry oxygen content being determined in accordance with DIN EN 15296; (iv) the total dry carbon content of the biomass solid fuel is equal to or greater than 40% by weight, the total dry carbon content being determined in accordance with DIN EN 15104; (v) the total dry nitrogen content of the biomass solid fuel is less than 5.0% by weight, the total dry nitrogen content being less than 5.0% by weight, the total dry nitrogen content being less than 5.0% by weight, the total dry carbon ... carbon content being less than 5.0% by weight, the total dry carbon content being less than 5.0% by weight, the total dry carbon content being less than 5.0% by weight, the total dry carbon content being less than 5.0% by weight, the total dry nitrogen content being less than 5.0% by weight, the total dry carbon content being less than 5.0% by weight, the total dry (vi) the chemical oxygen demand (COD) of the solid biomass fuel is not more than 5000 ppm when immersed in water, the COD being determined in accordance with GB / 11914-89; (vii) the fixed carbon content of the solid biomass fuel is not less than 20% by weight, the fixed carbon content being determined in accordance with DIN EN 51734; (viii) the ash content of the solid biomass fuel is less than 20% by weight, the ash content being determined in accordance with EN 14775 at 550°C; (ix) the volatile matter content of the solid biomass fuel is between 35% and 80% by weight, the volatile matter content being determined in accordance with DIN EN 15148; (x) the internal moisture content of the solid biomass fuel is less than 8% by weight, the internal moisture content being determined in accordance with DIN EN 14775. (xi) the biomass solid fuel has a calorific value of 4300 kcal / kg to 6500 kcal / kg, said calorific value being determined in accordance with DIN EN 14918; 10. The method of claim 1, wherein: (xii) the biomass solid fuel has a base moisture content of less than 10% by weight, the base moisture content being determined by GB / T 211-2017; (xiii) the pH of the solid biomass fuel is between 4 and 10; and / or (xiv) the solid biomass fuel is water-resistant for up to 20 days.

13. 10. The method of claim 1, wherein 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.

14. A solid biomass fuel obtained by the method according to any one of claims 1 to 13.

15. 15. A method of combustion comprising combusting the solid biomass fuel of claim 14 to produce energy.

16. 16. The method of claim 15, wherein the solid biomass fuel is co-fired and combusted together with a fossil fuel such as coal, and / or the method has PM1.0 emissions of less than 175 mg / kg.

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