Environment-friendly bio-pellet fuel and preparation method thereof

Abstract

The present application relates to the technical field of biomass fuel, and relates to an environment-friendly biomass pellet fuel and a preparation method thereof.The biomass pellet fuel comprises the following raw materials in parts by weight: 65-78 parts of biomass raw material, 25-36 parts of modified fiber, 3-5 parts of moisture-proof agent, 2-5 parts of modified ash, 6-12 parts of polyvinyl alcohol, 12-25 parts of combustion-supporting agent and 0.5-2.0 parts of silane coupling agent.The biomass raw material comprises the following raw materials in parts by weight: 10-36 parts of corn straw, 12-18 parts of wheat straw, 3-15 parts of apple residual branches, 4-9 parts of pear residual branches and 32-45 parts of mushroom waste sticks.The prepared biomass pellet fuel replaces fossil fuel, reduces greenhouse gas emission, utilizes agricultural and forestry waste and realizes resource utilization.The biomass pellet fuel has the properties of moisture absorption resistance and mildew resistance and is suitable for use in high-humidity areas.

Description

Technical Field

[0001] This invention relates to the field of biomass fuel technology, and more specifically, to an environmentally friendly biomass pellet fuel and its preparation method. Background Technology

[0002] Biomass fuel mainly refers to the use of biomass materials as fuel, primarily agricultural waste, discarded bark and tree trunks, etc. Due to increased environmental awareness and a desire to reduce the consumption of non-renewable energy, biomass fuel has experienced unprecedented development.

[0003] The main components of biomass fuels are agricultural crops, tree trunks, wood chips, and other materials, which contain large amounts of elements such as potassium, sulfur, and chlorine. If burned directly, they will produce a large amount of dust and toxic gases, which will harm the environment and human health. In addition, binders are often added during the preparation process to shape the fuel, which increases the types and contents of chemical elements in the product. After combustion, the types of gases volatilized are more complex, and more ash is produced, which has a negative impact on environmental governance. Summary of the Invention

[0004] This invention provides an environmentally friendly biomass pellet fuel and its preparation method. The resulting biomass pellet fuel replaces fossil fuels, reduces greenhouse gas emissions, utilizes agricultural and forestry waste, and achieves resource utilization. It possesses moisture-resistant and mildew-resistant properties, making it suitable for high-humidity areas.

[0005] In a first aspect, the present invention provides an environmentally friendly biomass pellet fuel, comprising the following raw materials by weight: 65-78 parts of biomass raw material, 25-36 parts of modified fiber, 3-5 parts of moisture-proofing agent, 2-5 parts of modified ash, 6-12 parts of polyvinyl alcohol, 12-25 parts of combustion aid, and 0.5-2.0 parts of silane coupling agent.

[0006] Preferably, the biomass raw materials include the following raw materials by weight: 10-36 parts corn stalks, 12-18 parts wheat stalks, 3-15 parts apple branches, 4-9 parts pear branches, and 32-45 parts spent mushroom substrate.

[0007] Preferably, the waste mushroom substrate comprises bamboo shavings and waste mushroom substrate, wherein the mass ratio of the bamboo shavings to the waste mushroom substrate is 1~4:6~10.

[0008] Preferably, the modified fiber is prepared by blending alkylated lignin with cellulose, wherein the mass ratio of alkylated lignin to cellulose is 1~5:2~3.

[0009] Preferably, the modified ash comprises kaolin, alumina, and zinc oxide, wherein the mass ratio of kaolin, alumina, and zinc oxide is 3~5:1~2:1.

[0010] Preferably, the moisture-proofing agent is selected from at least one of nano-silica, talc, oxidized starch, or stearic acid.

[0011] Preferably, the combustion aid is selected from at least one of ferric oxide, manganese dioxide, calcium carbonate, or red mud.

[0012] Secondly, the present invention provides a method for preparing environmentally friendly biomass pellet fuel, comprising the following steps: (1) Add the dried biomass raw materials, modified fiber, modified ash and combustion aid into a high-speed mixer and mix for 5-10 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 3-5 minutes, then add polyvinyl alcohol and moisture-proofing agent, mix until loose aggregated state, with a water content of 12-16%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill, and then shaped and dried to obtain cylindrical environmentally friendly biomass fuel with a diameter of 6~12 mm and a length of 15~30 mm.

[0013] Preferably, in step (3), the molding temperature is 90~135℃ and the pressure is 90~180 MPa; the drying temperature is 65~95℃ and the drying time is 2~6h.

[0014] Preferably, the moisture content of the environmentally friendly biomass pellet fuel is <8%.

[0015] In summary, the present invention has the following beneficial effects: 1. The high calorific value and high lignin content of fruit tree branches, a biomass raw material in this invention, compensate for the low calorific value and high ash content of straw. The high volatility of straw promotes rapid ignition, while fruit trees provide sustained and stable combustion. Apple / pear branches and bamboo shavings are rich in Ca, Mg, and Al, which can neutralize the activity of alkali metals and increase the ash melting point. The mycelial residues in shiitake mushroom substrate contain organic acids or chelates, which help fix metal ions. Fruit tree branches and bamboo shavings provide a natural binding framework; the residual polysaccharides and proteins in the substrate have a certain degree of viscosity, and the finely broken straw fibers fill the pores, improving particle density.

[0016] 2. The lignin in this invention possesses a three-dimensional aromatic network structure, rich in phenolic and alcoholic hydroxyl groups. Alkylation-modified lignin is achieved through chemical reactions such as with haloalkanes and epoxides, introducing alkyl groups (e.g., methyl, ethyl, long-chain alkyl) onto the active hydroxyl groups of lignin, thereby reducing its polarity and enhancing its hydrophobicity. This weakens intermolecular hydrogen bonds, improving thermoplasticity and increasing compatibility with cellulose, thus strengthening interfacial bonding. Alkylated lignin exhibits thermoplastic-like behavior under heating and pressure, acting as a natural "bonding phase" to encapsulate cellulose fibers. After blending, it forms an interpenetrating network structure, enhancing cohesion. The alkyl chains impart a hydrophobic surface to lignin, reducing water permeation through capillary pores. Alkylated lignin exhibits more stable pyrolysis, reducing tar formation, and its aromatic structure promotes char skeleton formation, facilitating subsequent carbon burnout. The blended system releases volatiles more uniformly, preventing deflagration and improving combustion efficiency, thus reducing CO and particulate emissions.

[0017] 3. The alkylated lignin in this invention is inherently hydrophobic. When combined with plant oils or kaolin-based moisture-proofing agents, it can form a double moisture-proof layer by sealing the fiber interface and surface micropores within the particles. The silane coupling agent further enhances the bonding between the inorganic moisture-proofing agent SiO2, kaolin, and the organic matrix, preventing moisture absorption channels caused by phase separation. This method can efficiently utilize high-ash, high-alkali, and low-calorific-value agricultural / forestry / edible fungi waste. The resulting environmentally friendly bio-pellet fuel has a 20-30% shorter ignition time, reduced CO emissions, and no significant black smoke.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of protection of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.

[0020] Example Example 1 An environmentally friendly biomass pellet fuel comprises the following raw materials by weight: 65 parts biomass raw material, 25 parts modified fiber, 3 parts moisture-proofing agent, 2 parts modified ash, 6 parts polyvinyl alcohol, 12 parts combustion improver, and 0.5 parts silane coupling agent.

[0021] The biomass raw materials include the following raw materials by weight: 10 parts corn stalks, 12 parts wheat stalks, 3 parts apple branches, 4 parts pear branches, and 32 parts spent mushroom substrate; wherein, the spent mushroom substrate includes bamboo shavings and spent mushroom substrate, and the mass ratio of bamboo shavings to the spent mushroom substrate is 1:6.

[0022] The modified fiber was prepared by blending alkylated lignin with cellulose, with a mass ratio of alkylated lignin to cellulose of 1:2.

[0023] The moisture-proofing agent is selected from nano-silica; the combustion aid is selected from ferric oxide.

[0024] A method for preparing environmentally friendly biomass pellet fuel includes the following steps: (1) Add the dried biomass raw materials, modified fiber, modified ash and combustion aid into a high-speed mixer and mix for 5 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 3 min, then add polyvinyl alcohol and moisture-proofing agent, mix until loose agglomerate state, with a water content of 12%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill for molding and drying to obtain cylindrical environmentally friendly biomass fuel with a diameter of 6 mm and a length of 15 mm. The molding temperature is 90℃ and the pressure is 90 MPa; the drying temperature is 75℃ and the drying time is 3 h. The moisture content of the environmentally friendly biomass fuel is 6%.

[0025] Example 2 An environmentally friendly biomass pellet fuel comprises the following raw materials by weight: 68 parts biomass raw material, 27 parts modified fiber, 4 parts moisture-proofing agent, 3 parts modified ash, 8 parts polyvinyl alcohol, 15 parts combustion improver, and 1.2 parts silane coupling agent.

[0026] The biomass raw materials include the following raw materials by weight: 15 parts corn stalks, 14 parts wheat stalks, 6 parts apple branches, 6 parts pear branches, and 38 parts spent mushroom substrate; wherein, the spent mushroom substrate includes bamboo shavings and spent mushroom substrate, and the mass ratio of bamboo shavings to the spent mushroom substrate is 2:7.

[0027] The modified fiber was prepared by blending alkylated lignin with cellulose, with a mass ratio of alkylated lignin to cellulose of 3:2.

[0028] The moisture-proofing agent is selected from nano-silica; the combustion aid is selected from ferric oxide.

[0029] A method for preparing environmentally friendly biomass pellet fuel includes the following steps: (1) The dried biomass raw materials, modified fiber, modified ash and combustion aid are put into a high-speed mixer and mixed for 6 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 5 min, then add polyvinyl alcohol and moisture-proofing agent, mix until loose aggregated state, with a water content of 13%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill for molding and drying to obtain cylindrical environmentally friendly biomass fuel with a diameter of 8 mm and a length of 20 mm. The molding temperature is 105℃ and the pressure is 100 MPa; the drying temperature is 80℃ and the drying time is 2 hours. The moisture content of the environmentally friendly biomass fuel is 7.1%.

[0030] Example 3 An environmentally friendly biomass pellet fuel comprises the following raw materials by weight: 70 parts biomass raw material, 30 parts modified fiber, 4 parts moisture-proofing agent, 3 parts modified ash, 8 parts polyvinyl alcohol, 15 parts combustion improver, and 1.0 part silane coupling agent.

[0031] The biomass raw materials include the following raw materials by weight: 18 parts corn stalks, 14 parts wheat stalks, 12 parts apple branches, 5 parts pear branches, and 36 parts spent mushroom substrate; wherein, the spent mushroom substrate includes bamboo shavings and spent mushroom substrate, and the mass ratio of bamboo shavings to the spent mushroom substrate is 1:7.

[0032] The modified fiber was prepared by blending alkylated lignin with cellulose, with a mass ratio of alkylated lignin to cellulose of 4:3.

[0033] The moisture-proofing agent is selected from nano-silica; the combustion aid is selected from ferric oxide.

[0034] A method for preparing environmentally friendly biomass pellet fuel includes the following steps: (1) The dried biomass raw materials, modified fiber, modified ash and combustion aid are put into a high-speed mixer and mixed for 10 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 5 min, then add polyvinyl alcohol and moisture-proofing agent, mix until loose aggregated state, with a water content of 13%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill for molding and drying to obtain cylindrical environmentally friendly biomass pellet fuel with a diameter of 8 mm and a length of 18 mm. The molding temperature is 102℃ and the pressure is 110 MPa; the drying temperature is 65℃ and the drying time is 3 hours. The moisture content of the environmentally friendly biomass pellet fuel is 6.5%.

[0035] Example 4 An environmentally friendly biomass pellet fuel comprises the following raw materials by weight: 72 parts biomass raw material, 32 parts modified fiber, 5 parts moisture-proofing agent, 4 parts modified ash, 10 parts polyvinyl alcohol, 20 parts combustion improver, and 1.5 parts silane coupling agent.

[0036] The biomass raw materials include the following raw materials by weight: 32 parts corn stalks, 15 parts wheat stalks, 12 parts apple branches, 8 parts pear branches, and 40 parts spent mushroom substrate; wherein, the spent mushroom substrate includes bamboo shavings and spent mushroom substrate, and the mass ratio of bamboo shavings to the spent mushroom substrate is 3:10.

[0037] The modified fiber was prepared by blending alkylated lignin with cellulose, with a mass ratio of alkylated lignin to cellulose of 5:2.

[0038] The moisture-proofing agent is selected from nano-silica; the combustion aid is selected from ferric oxide.

[0039] A method for preparing environmentally friendly biomass pellet fuel includes the following steps: (1) The dried biomass raw materials, modified fiber, modified ash and combustion aid are put into a high-speed mixer and mixed for 10 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 5 min, then add polyvinyl alcohol and moisture-proofing agent, mix until loose agglomerate state, with a water content of 15%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill for molding and drying to obtain cylindrical environmentally friendly biomass fuel with a diameter of 10 mm and a length of 28 mm. The molding temperature is 120℃ and the pressure is 150 MPa; the drying temperature is 85℃ and the drying time is 4 hours. The moisture content of the environmentally friendly biomass fuel is 7.2%.

[0040] Example 5 An environmentally friendly biomass pellet fuel comprises the following raw materials by weight: 78 parts biomass raw material, 36 parts modified fiber, 5 parts moisture-proofing agent, 5 parts modified ash, 12 parts polyvinyl alcohol, 25 parts combustion improver, and 2.0 parts silane coupling agent.

[0041] The biomass raw materials include the following raw materials by weight: 36 parts corn stalks, 18 parts wheat stalks, 15 parts apple branches, 9 parts pear branches, and 45 parts spent mushroom substrate; wherein, the spent mushroom substrate includes bamboo shavings and spent mushroom substrate, and the mass ratio of bamboo shavings to the spent mushroom substrate is 4:9.

[0042] The modified fiber was prepared by blending alkylated lignin with cellulose, with a mass ratio of alkylated lignin to cellulose of 5:3.

[0043] The moisture-proofing agent is selected from nano-silica; the combustion aid is selected from ferric oxide.

[0044] A method for preparing environmentally friendly biomass pellet fuel includes the following steps: (1) The dried biomass raw materials, modified fiber, modified ash and combustion aid are put into a high-speed mixer and mixed for 10 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 5 min, then add polyvinyl alcohol and moisture-proofing agent, mix until loose aggregated state, with water content of 16%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill for molding and drying to obtain cylindrical environmentally friendly biomass fuel with a diameter of 12 mm and a length of 30 mm. The molding temperature is 135℃ and the pressure is 180 MPa; the drying temperature is 95℃ and the drying time is 6h. The moisture content of the environmentally friendly biomass fuel is 6.9%.

[0045] Comparative Example 1 The only difference from Example 1 is that no modified fibers were added.

[0046] Comparative Example 2 The only difference from Example 1 is that no modified ash was added.

[0047] Comparative Example 3 The only difference from Example 1 is that no combustion improver was added.

[0048] Comparative Example 4 The only difference from Example 1 is that no desiccant was added.

[0049] Performance testing: The biomass pellet fuels prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to performance tests. The moisture content of the biomass fuels was determined under a relative humidity of 80%. The results are shown in Table 1.

[0050] The above description is merely an exemplary embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An environmentally friendly biomass pellet fuel, characterized in that, The raw materials include the following by weight: 65-78 parts biomass raw materials, 25-36 parts modified fiber, 3-5 parts moisture-proofing agent, 2-5 parts modified ash, 6-12 parts polyvinyl alcohol, 12-25 parts combustion aid, and 0.5-2.0 parts silane coupling agent. The biomass raw materials include the following raw materials by weight: 10-36 parts corn stalks, 12-18 parts wheat stalks, 3-15 parts apple branches, 4-9 parts pear branches, and 32-45 parts spent mushroom substrate. The waste mushroom substrate includes bamboo shavings and waste mushroom substrate, and the mass ratio of the bamboo shavings to the waste mushroom substrate is 1~4:6~10; The modified fiber is prepared by blending alkylated lignin with cellulose, wherein the mass ratio of alkylated lignin to cellulose is 1~5:2~3.

2. The environmentally friendly biomass pellet fuel according to claim 1, characterized in that, The modified ash comprises kaolin, alumina, and zinc oxide, wherein the mass ratio of kaolin, alumina, and zinc oxide is 3~5:1~2:

1.

3. The environmentally friendly biomass pellet fuel according to claim 1, characterized in that, The moisture-proofing agent is selected from at least one of nano-silica, talc, oxidized starch, or stearic acid.

4. The environmentally friendly biomass pellet fuel according to claim 1, characterized in that, The combustion aid is selected from at least one of ferric oxide, manganese dioxide, calcium carbonate, or red mud.

5. The method for preparing environmentally friendly biomass pellet fuel according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Add the dried biomass raw materials, modified fiber, modified ash and combustion aid into a high-speed mixer and mix for 5-10 minutes to obtain a mixture; (2) Add silane coupling agent solution to the mixture, mix for 3-5 minutes, then add polyvinyl alcohol and moisture-proofing agent, mix until loose aggregated state, with a water content of 12-16%, to obtain the mixture; (3) The mixture is fed into a ring die or flat die pellet mill, shaped and dried to obtain cylindrical environmentally friendly biomass fuel with a diameter of 6~12 mm and a length of 15~30 mm.

6. The method for preparing environmentally friendly biomass pellet fuel according to claim 5, characterized in that, In step (3), the molding temperature is 90~135℃ and the pressure is 90~180 MPa; the drying temperature is 65~95℃ and the drying time is 2~6h.

7. The method for preparing environmentally friendly biomass pellet fuel according to claim 5, characterized in that, The moisture content of the environmentally friendly biomass pellet fuel is <8%.

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