A low-slagging biomass briquette and a method for producing the same
Patent Information
- Application Number
- CN202611055783.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-16
- Publication Date
- 2026-09-22
AI Technical Summary
现有低共熔溶剂处理生物质的研究和专利多以脱木质素、纤维素糖化或组分分离为目标，未针对秸秆灰分中的碱金属和氯进行协同去除，也未建立低共熔溶剂预处理、灰熔融特性改善与燃料压制成型之间的完整技术方案
[0023]本发明提供的低结渣生物质成型燃料的制备方法，采用低共熔溶剂对生物质原料进行预处理，并将生物质脱灰处理与后续压制成型相结合。一方面，低共熔溶剂能够优先去除生物质中的钾、钠和氯等易形成低熔点盐、碱金属硅酸盐及共熔化合物的灰分形成组分，降低残余灰分中低熔点组分的含量，使残余灰分由富钾、富氯体系向二氧化硅相对富集的耐火体系转变，从而抑制燃烧过程中低熔点液相的形成，提高灰熔融温度并降低成型燃料的结渣和沾污倾向；另一方面，低共熔溶剂能够适度破坏生物质中的半纤维素、木质素-碳水化合物复合结构及纤维间连接，使生物质纤维表面形成裂纹、孔隙和粗糙结构，增加压制过程中颗粒之间的有效接触面积，促进木质素等组分在纤维孔隙和颗粒界面之间发挥黏结作用，进而提高成型燃料的密度、机械稳定性和耐水性能。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of biomass solid fuel preparation and clean combustion technology, specifically a low-slagging biomass briquettes fuel and its preparation method. Background Technology
[0002] Agricultural wastes such as straw are widely available, renewable, and have low carbon emission intensity, making them important raw materials for producing solid biomass fuels. However, herbaceous biomass typically suffers from low bulk density, loose structure, poor storage and transportation stability, and complex ash composition. Direct combustion or simple molding can still easily lead to slagging, contamination, ash accumulation, and high-temperature corrosion.
[0003] Corn stalk ash typically contains high proportions of potassium, sodium, and chlorine. During combustion, these components can form low-melting-point salts such as potassium chloride and sodium chloride, which react with silica to form low-melting-point alkali metal silicates or eutectics, leading to a decrease in ash melting temperature. Molten or semi-molten ash particles easily adhere to the grate, bed material, and heat exchange surfaces, causing coking and blockage, reduced heat transfer efficiency, and equipment corrosion.
[0004] Existing methods for reducing biomass caking tendency mainly include blending with high ash melting point fuels, adding kaolin or calcium-magnesium-aluminum mineral additives, water washing, and acid washing. Blending or additive methods alter fuel composition and increase ash content; water washing primarily removes water-soluble salts, offering limited improvement to the structure and molding properties of lignocellulose; conventional strong acid or alkali treatments may lead to corrosion, wastewater treatment, and safety issues. Therefore, a pretreatment method is needed that can simultaneously control inorganic ash composition and organic fiber structure, and possesses solvent recovery potential.
[0005] Eutectic solvents are typically formed by hydrogen bond acceptors and donors through hydrogen bonding, and are characterized by simple preparation, low vapor pressure, adjustable composition, and recyclability. Existing research and patents on eutectic solvent treatment of biomass primarily focus on delignification, cellulose saccharification, or component separation, without addressing the synergistic removal of alkali metals and chlorine from straw ash, nor have they established a complete technical solution integrating eutectic solvent pretreatment, ash melting characteristic improvement, and fuel compression molding.
[0006] Therefore, it is necessary to provide a method for preparing low-slagging biomass briquettes through eutectic solvent pretreatment, which significantly reduces the ash content and low-melting-point ash content of biomass, increases the ash melting temperature, and improves the density, mechanical strength, and water resistance of the resulting briquettes without relying on external inorganic anti-slagging agents. Summary of the Invention
[0007] The purpose of this invention is to provide a low-caking biomass briquettes fuel and its preparation method, so as to solve the problems mentioned in the background art.
[0008] To achieve the above objectives, the present invention provides the following technical solution:
[0009] A method for preparing low-slagging biomass briquettes includes the following steps:
[0010] The hydrogen bond acceptor and hydrogen bond donor were mixed and then heated to obtain a eutectic solvent.
[0011] Biomass feedstock is mixed with a eutectic solvent and pretreated under heating conditions to obtain a pretreated mixture; the eutectic solvent can remove alkali metals and chlorine from the biomass feedstock, while regulating the structure of lignocellulose in the biomass feedstock.
[0012] The pretreated mixture is subjected to solid-liquid separation, and the resulting solid phase is washed and dried to obtain pretreated biomass;
[0013] The moisture content of the pretreated biomass is adjusted, and then it is pressed, shaped, and dried to obtain low-slagging biomass briquettes.
[0014] Furthermore, the hydrogen bond acceptor is choline chloride; the hydrogen bond donor is selected from organic acids or urea; the organic acid includes one or more of lactic acid, formic acid, and oxalic acid.
[0015] Furthermore, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(0.5-1.5); the mixing temperature of the hydrogen bond acceptor and the hydrogen bond donor is 70-90℃.
[0016] Furthermore, the biomass raw material is agricultural waste such as straw; the biomass raw material is dried, crushed and screened to a particle size of no more than 250 μm, and then mixed with a eutectic solvent.
[0017] Furthermore, the mass ratio of the biomass raw material to the eutectic solvent is 1:(10-20); the pretreatment temperature is 90-110℃.
[0018] Furthermore, the obtained solid phase is repeatedly washed with deionized water until the washing solution is neutral; the washed solid phase is dried at 50-70°C; the liquid phase obtained from solid-liquid separation is centrifuged to remove suspended solids, and then subjected to reduced pressure rotary evaporation at 40-60°C to remove water and volatile components from the liquid phase, thereby recovering the eutectic solvent.
[0019] Furthermore, the moisture content of the pretreated biomass is adjusted to 15-25 wt%; the pressing pressure is 15-25 MPa.
[0020] Another object of the present invention is to provide a low-slagging biomass pellet fuel prepared by the above-described preparation method.
[0021] Furthermore, the ash content of the low-slagging biomass briquettes is not higher than 5 wt%, the total content of K2O, Na2O, and Cl in the ash is not higher than 5 wt%, and the ash fusion deformation temperature is not lower than 1200℃; the density of the low-slagging biomass briquettes is not lower than 1400 kg / m³. 3 .
[0022] Another object of the present invention is to provide an application of the above-mentioned low-slagging biomass briquettes in direct heating, steam production or combined heat and power.
[0023] The method for preparing low-slagging biomass briquettes provided by this invention employs a eutectic solvent to pretreat biomass raw materials and combines biomass deashing treatment with subsequent pressing. On one hand, the eutectic solvent can preferentially remove ash-forming components in biomass, such as potassium, sodium, and chlorine, which easily form low-melting-point salts, alkali metal silicates, and eutectic compounds, reducing the content of low-melting-point components in the residual ash. This transforms the residual ash from a potassium- and chlorine-rich system to a silica-rich refractory system, thereby inhibiting the formation of low-melting-point liquid phases during combustion, increasing the ash melting temperature, and reducing the slagging and fouling tendency of the briquettes. On the other hand, the eutectic solvent can moderately disrupt the hemicellulose, lignin-carbohydrate complex structure, and inter-fiber connections in biomass, causing cracks, pores, and rough structures to form on the surface of biomass fibers. This increases the effective contact area between particles during pressing, promoting the bonding effect of lignin and other components between fiber pores and particle interfaces, thereby improving the density, mechanical stability, and water resistance of the briquettes. Attached Figure Description
[0024] Figure 1 This is a schematic flowchart of a method for preparing low-slagging biomass briquettes provided in an embodiment of the present invention.
[0025] Figure 2 The diagram shows the ash melting temperature of the shaped fuel ash samples obtained in Examples 1-5. Detailed Implementation
[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0027] In one embodiment of the present invention, a method for preparing low-slagging biomass briquettes is provided, comprising the following steps:
[0028] S1. Crush and sieve the dried biomass raw materials (such as corn stalks and other straw-based agricultural waste) to a particle size of no more than 250μm, and set aside for later use.
[0029] S2. Mix the hydrogen bond acceptor and hydrogen bond donor in a molar ratio of 1:(0.5-1.5), heat at 70-90℃ and stir continuously until a clear and homogeneous liquid is formed, thus obtaining a eutectic solvent.
[0030] S3. The above-mentioned crushed and sieved biomass raw materials are mixed with the above-mentioned eutectic solvent at a mass ratio of 1:(10-20), and pretreated at 90-110℃ for 2-4 hours to obtain a pretreated mixture. The eutectic solvent can remove alkali metals and chlorine from the biomass raw materials, and at the same time regulate the structure of lignocellulose in the biomass raw materials.
[0031] S4. The above pretreated mixture is subjected to solid-liquid separation (such as centrifugation or filtration). The resulting solid phase is repeatedly washed with deionized water until the washing liquid is neutral. The washed solid phase is dried at 50-70℃ to obtain pretreated biomass. The liquid phase obtained from solid-liquid separation is centrifuged to remove suspended solids and then subjected to vacuum rotary evaporation at 40-60℃ to remove water and volatile components from the liquid phase, recovering the eutectic solvent, which can be used for the pretreatment of the next batch of biomass feedstock.
[0032] S5. Adjust the moisture content of the pretreated biomass to 15-25 wt%, then place the pretreated biomass in a mold for pressing and molding. After demolding, dry it at 50-70℃ to constant weight to obtain low-slagging biomass briquettes.
[0033] Preferably, the hydrogen bond acceptor is choline chloride; the hydrogen bond donor is selected from organic acids or urea; the organic acids include one or more of lactic acid, formic acid, and oxalic acid. The mold used is a cylindrical mold with a diameter of 20-40 mm, and the amount of material fed in each pressing is 2-4 g; the pressing pressure is 15-25 MPa, and the holding time is 1-3 min.
[0034] In this embodiment of the invention, the use of eutectic solvent pretreatment promotes the migration of ash-forming components such as potassium, sodium, and chlorine in biomass feedstocks to the liquid phase, reducing the ash content of biomass and the content of low-melting-point components in residual ash, thereby increasing the relative proportion of silica in the residual ash. Simultaneously, eutectic solvent pretreatment can regulate the structure of lignocellulose in biomass feedstocks, causing cracks, pores, and a rough structure to form on the surface of biomass fibers. This increases the contact area between particles during pressing, promotes interparticle bonding, and thus improves the density and mechanical stability of the shaped fuel.
[0035] In another embodiment of the present invention, a low-slagging biomass briquettes prepared by the above-described method are also provided. The low-slagging biomass briquettes have an ash content not exceeding 5 wt%, a total ash content of K₂O, Na₂O, and Cl not exceeding 5 wt%, an ash fusion deformation temperature not lower than 1200℃, and a density not lower than 1400 kg / m³. 3 .
[0036] The preferred ash content of low-slagging biomass briquettes is 1.63 wt%, the preferred K₂O content in the ash is 1.23 wt%, the Cl content is below the detection limit, and the preferred total content of K₂O, Na₂O, and Cl is 1.98 wt%. The preferred deformation temperature of the low-slagging biomass briquettes is 1312℃, the preferred softening temperature is 1408℃, the preferred hemispherical temperature is 1450℃, and the preferred flow temperature is above 1500℃; the preferred density of the low-slagging biomass briquettes is 1848.25 kg / m³. 3 It showed no obvious damage after being dropped from a height of 1m more than 30 times.
[0037] In another embodiment of the present invention, the application of the above-mentioned low-slagging biomass briquettes is also provided in direct heating, steam production, or combined heat and power (CHP). The low-slagging biomass briquettes are fed into a biomass boiler, a fixed-bed combustion furnace, or a fluidized-bed combustion device for combustion, utilizing the heat generated for direct heating, steam production, or CHP. Specifically, the low-slagging biomass briquettes can reduce the formation of low-melting-point molten ash phases and reduce the adhesion and slagging tendency of ash on the grate, furnace wall, and heat exchange surfaces.
[0038] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products and can be purchased through commercial channels. The invention will be described in detail below through specific embodiments in practical applications.
[0039] Example 1: This example provides a low-slagging biomass briquettes pretreated with choline chloride / lactic acid eutectic solvent. The preparation method includes the following steps:
[0040] Choline chloride and lactic acid were mixed in a 1:1 molar ratio and stirred continuously at 80°C until a clear and homogeneous liquid was formed, thus obtaining a choline chloride / lactic acid eutectic solvent.
[0041] Air-dried corn stalks were crushed and sieved to a particle size of less than 250 μm. The corn stalks were added to a reaction vessel at a mass ratio of 1:15 to a eutectic solvent, and the mixture was stirred at 100 °C for 3 h. After the reaction, the mixture was centrifuged, and the resulting solid phase was repeatedly washed with deionized water until the supernatant was neutral. The supernatant was then dried at 60 °C for 12 h to obtain pretreated corn stalks.
[0042] Water was added to the dried pretreated corn stalks to bring the moisture content to 20 wt%. Approximately 3 g of sample was added to a cylindrical mold with a diameter of 30 mm, and the mold was held under pressure at 20 MPa for 2 min. After demolding, the sample was dried at 60 °C to constant weight to obtain choline chloride / lactic acid pretreated corn stalk pellet fuel.
[0043] like Figure 2 As shown in Table 1, the deformation temperature DT, softening temperature ST, hemispherical temperature HT, and flow temperature FT of the obtained briquetted fuel ash samples are approximately 1280℃, 1350℃, 1400℃, and 1430℃, respectively; the density of the obtained briquetted fuel is 1524.55 kg / m³. 3 After being dropped 26 times from a height of 1 meter, obvious cracks or damage appeared. Its heating value is 17.9 MJ / kg, and its water permeability is approximately 73.1%. The initial water contact angle of the resulting briquetted fuel is 100.6°, which further decreases to 31.5° after 4 seconds.
[0044] Example 2: This example provides a low-slagging biomass briquettes pretreated with a choline chloride / formic acid eutectic solvent. The preparation method includes the following steps:
[0045] Choline chloride and formic acid were mixed in a 1:1 molar ratio and stirred continuously at 80°C until a clear and homogeneous liquid was formed, thus obtaining a choline chloride / formic acid eutectic solvent.
[0046] Air-dried corn stalks were crushed and sieved to a particle size of less than 250 μm. The corn stalks were added to a reaction vessel at a mass ratio of 1:15 to a eutectic solvent, and the mixture was stirred at 100 °C for 3 h. After the reaction, the mixture was centrifuged, and the resulting solid phase was repeatedly washed with deionized water until the supernatant was neutral. The supernatant was then dried at 60 °C for 12 h to obtain pretreated corn stalks.
[0047] Water was added to the dried pretreated corn stalks to bring the moisture content to 20 wt%. Approximately 3 g of sample was added to a cylindrical mold with a diameter of 30 mm, and the mold was held under pressure at 20 MPa for 2 min. After demolding, the sample was dried at 60 °C to constant weight to obtain choline chloride / formic acid pretreated corn stalk briquettes.
[0048] like Figure 2 As shown in Table 1, the DT, ST, and HT of the obtained briquetted fuel ash samples reached 1312℃, 1408℃, and 1450℃, respectively, and the FT exceeded 1500℃; the density of the obtained briquetted fuel was 1848.25 kg / m³. 3 It showed no obvious damage after being dropped freely from a height of 1m more than 30 times. Its calorific value is 17.7MJ / kg, its water permeability is lower than that of samples from other embodiments, its initial water contact angle is 92.1°, and it still maintains 70.1° after 4s.
[0049] Example 3: This example provides a low-slagging biomass briquettes pretreated with choline chloride / oxalic acid eutectic solvent. The preparation method includes the following steps:
[0050] Choline chloride and oxalic acid were mixed in a 1:1 molar ratio and stirred continuously at 80°C until a clear and homogeneous liquid was formed, thus obtaining a choline chloride / oxalic acid eutectic solvent.
[0051] Air-dried corn stalks were crushed and sieved to a particle size of less than 250 μm. The corn stalks were added to a reaction vessel at a mass ratio of 1:15 to a eutectic solvent, and the mixture was stirred at 100 °C for 3 h. After the reaction, the mixture was centrifuged, and the resulting solid phase was repeatedly washed with deionized water until the supernatant was neutral. The supernatant was then dried at 60 °C for 12 h to obtain pretreated corn stalks.
[0052] Water was added to the dried pretreated corn stalks to bring the moisture content to 20 wt%. Approximately 3 g of sample was added to a cylindrical mold with a diameter of 30 mm, and the mold was held under pressure at 20 MPa for 2 min. After demolding, the sample was dried at 60 °C to constant weight to obtain choline chloride / oxalic acid pretreated corn stalk pellet fuel.
[0053] like Figure 2 As shown in Table 1, the deformation temperature DT, softening temperature ST, hemispherical temperature HT, and flow temperature FT of the obtained briquetted fuel ash samples are approximately 1260℃, 1290℃, 1360℃, and 1400℃, respectively; the density of the obtained briquetted fuel is 1612.46 kg / m³. 3 The material underwent more than 30 free drops from a height of 1 meter without showing any obvious cracking or damage. Its higher heating value is 18.5 MJ / kg, and its water permeability is approximately 53.5%. The initial water contact angle of the resulting briquetted fuel is 68.2°, and it reaches 40.8° at 4 seconds.
[0054] Example 4: This example provides a low-slagging biomass briquettes pretreated with choline chloride / urea eutectic solvent. The preparation method includes the following steps:
[0055] Choline chloride and urea were mixed in a 1:1 molar ratio and stirred continuously at 80°C until a clear and homogeneous liquid was formed, thus obtaining a choline chloride / urea eutectic solvent.
[0056] Air-dried corn stalks were crushed and sieved to a particle size of less than 250 μm. The corn stalks were added to a reaction vessel at a mass ratio of 1:15 to a eutectic solvent, and the mixture was stirred at 100 °C for 3 h. After the reaction, the mixture was centrifuged, and the resulting solid phase was repeatedly washed with deionized water until the supernatant was neutral. The supernatant was then dried at 60 °C for 12 h to obtain pretreated corn stalks.
[0057] Water was added to the dried pretreated corn stalks to bring the moisture content to 20 wt%. Approximately 3 g of sample was added to a cylindrical mold with a diameter of 30 mm, and the mold was held under pressure at 20 MPa for 2 min. After demolding, the sample was dried at 60 °C to constant weight to obtain choline chloride / urea pretreated corn stalk pellet fuel.
[0058] like Figure 2 As shown in Table 1, the deformation temperature DT, softening temperature ST, hemispherical temperature HT, and flow temperature FT of the obtained briquetted fuel ash samples are approximately 1240℃, 1300℃, 1390℃, and 1410℃, respectively; the density of the obtained briquetted fuel is 1718.64 kg / m³. 3 After being dropped 27 times from a height of 1 meter, obvious cracks or damage appeared. Its heating value is 18.5 MJ / kg, and its water permeability is approximately 94.3%. The initial water contact angle of the obtained briquetted fuel was 106.9°, which decreased to 60.1° after 4 seconds.
[0059] Example 5: This example provides corn stalk pellet fuel without pretreatment with a eutectic solvent. The preparation method includes the following steps:
[0060] The same corn stalk powder as in Example 1 was directly adjusted to a moisture content of 20 wt%, pressed at 20 MPa for 2 min and dried to constant weight to obtain untreated corn stalk briquettes.
[0061] like Figure 2 As shown in Table 1, the deformation temperature DT, softening temperature ST, hemispherical temperature HT, and flow temperature FT of the obtained briquetted fuel ash samples were 910℃, 1011℃, 1126℃, and 1164℃, respectively. The density of the obtained briquetted fuel was 1248.21 kg / m³, and it showed obvious cracking or breakage after 25 free drops from a height of 1 m. Its higher heating value was 16.5 MJ / kg, and its water permeability was approximately 125.7%. The initial water contact angle of the obtained briquetted fuel was 80.1°, which further decreased to 39.5° at 1.558 s.
[0062] Table 1
[0063] sample Ash content (%) <![CDATA[SiO2(%)]]> <![CDATA[K2O(%)]]> Cl（%） <![CDATA[density (kg / m 3 )]]> Drop performance Example 1 3.08 83.60 1.22 0.08 1524.55 26 times, obvious damage Example 2 1.63 84.21 1.23 Not detected 1848.25 >30 times, no obvious damage. Example 3 4.25 70.42 0.98 1.09 1612.46 >30 times, no obvious damage. Example 4 5.45 68.43 1.53 0.57 1718.64 27 times, obvious damage Example 5 9.32 27.66 22.63 10.06 1248.21 25 times, obvious damage
[0064] Example 6: This example provides a method for the recovery and recycling of eutectic solvents, including the following steps:
[0065] The supernatant obtained from the solid-liquid separation process in Example 2 was collected, centrifuged to remove suspended solids, and then rotary evaporated under reduced pressure at 50°C to remove water and volatile components, recovering the eutectic solvent. The recovered eutectic solvent was weighed, and without adding fresh eutectic solvent, a new batch of corn stalks was directly treated under the same conditions as in Example 2. The recovery and pretreatment were repeated five times.
[0066] After the first treatment, the ash content of corn stalks was 1.63 wt%, and the deashing rate was 82.56%. After the fifth treatment, the ash content was 3.23 wt%, and the deashing rate was still 65.41%. As the number of cycles increased, the ash melting temperature gradually decreased, but the characteristic ash melting temperatures of the sample from the fifth cycle were still significantly higher than those of the untreated corn stalks.
[0067] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.
Claims
1. A method for preparing low-slagging biomass briquettes, characterized in that, Includes the following steps: The hydrogen bond acceptor and hydrogen bond donor were mixed and then heated to obtain a eutectic solvent. Biomass feedstock is mixed with a eutectic solvent and pretreated under heating conditions to obtain a pretreated mixture; the eutectic solvent can remove alkali metals and chlorine from the biomass feedstock, while regulating the structure of lignocellulose in the biomass feedstock. The pretreated mixture is subjected to solid-liquid separation, and the resulting solid phase is washed and dried to obtain pretreated biomass; The moisture content of the pretreated biomass is adjusted, and then it is pressed, shaped, and dried to obtain low-slagging biomass briquettes.
2. The method for preparing low-slagging biomass briquettes according to claim 1, characterized in that, The hydrogen bond acceptor is choline chloride; the hydrogen bond donor is selected from organic acids or urea; the organic acid includes one or more of lactic acid, formic acid, and oxalic acid.
3. The method for preparing low-slagging biomass briquettes according to claim 1 or 2, characterized in that, The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:(0.5-1.5); the mixing temperature of the hydrogen bond acceptor and the hydrogen bond donor is 70-90℃.
4. The method for preparing low-slagging biomass briquettes according to claim 1, characterized in that, The biomass raw material is agricultural waste such as straw; the biomass raw material is dried, crushed and screened to a particle size of no more than 250 μm, and then mixed with a eutectic solvent.
5. The method for preparing low-slagging biomass briquettes according to claim 1 or 4, characterized in that, The mass ratio of the biomass raw material to the eutectic solvent is 1:(10-20); the pretreatment temperature is 90-110℃.
6. The method for preparing low-slagging biomass briquettes according to claim 1, characterized in that, The obtained solid phase is repeatedly washed with deionized water until the washing solution is neutral; the washed solid phase is dried at 50-70℃; the liquid phase obtained from solid-liquid separation is centrifuged to remove suspended solids, and then subjected to reduced pressure rotary evaporation at 40-60℃ to remove water and volatile components from the liquid phase, and the eutectic solvent is recovered.
7. The method for preparing low-slagging biomass briquettes according to claim 1, characterized in that, The moisture content of the pretreated biomass is adjusted to 15-25 wt%; the pressing pressure is 15-25 MPa.
8. A low-slagging biomass pellet fuel prepared by the preparation method according to any one of claims 1-7.
9. The low-slagging biomass briquettes according to claim 8, characterized in that, The low-slagging biomass briquettes have an ash content of no more than 5 wt%, a total ash content of K₂O, Na₂O, and Cl of no more than 5 wt%, and an ash fusion deformation temperature of no less than 1200℃; the density of the low-slagging biomass briquettes is no less than 1400 kg / m³. 3 .
10. The application of a low-slagging biomass briquettes fuel as described in claim 8 or 9 in direct heating, steam production, or combined heat and power.