A high-energy composite matrix fuel with pine wood as the main component, mixed with plastic film and walnut shell, and its preparation method.

Abstract

This invention discloses a high-energy composite matrix fuel made primarily of pine wood, incorporating mulch film and walnut shells, and its preparation method. The method includes the following steps: pre-treating pine waste wood, waste walnut shells, and waste agricultural mulch film to obtain pine wood pellets, walnut shell pellets, and mulch film fragments; mixing the three materials uniformly at a mass ratio of (70-90):(5-10):(5-20) to obtain a mixture; feeding the mixture into a ring die pellet mill, extruding and cutting it under molding pressure and ring die compression ratio conditions to obtain rod-shaped composite matrix fuel pellets. This invention achieves the resource utilization of agricultural waste, and the resulting fuel meets the first-class indicators for wood-based biomass pellet fuel, with dioxin emissions meeting national standard limits, demonstrating good environmental and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of composite matrix fuel preparation technology, specifically relating to a high-energy composite matrix fuel with pine wood as the main component and incorporating mulch film and walnut shells, and its preparation method. Background Technology

[0002] Agricultural mulch film is mainly composed of polyethylene, and its widespread use in agriculture results in a large amount of residue on farmland. Currently, the main methods for recycling agricultural mulch film include: 1. Physical recycling: 1) Melt granulation: The cleaned mulch film is crushed and melted to process into plastic granules for the production of low-requirement plastic products (such as flower pots, garbage cans, drainage pipes, etc.); 2) Direct pressing: It is made into plastic sheets or gaskets for use in construction, logistics, and other fields. 2. Chemical treatment: 1) Pyrolysis refining: The mulch film is converted into fuel oil, fuel gas, or carbon black through high-temperature pyrolysis technology; 2) Chemical degradation: It is decomposed into monomers using catalysts or solvents and resynthesized into plastics. 3. Energy recovery (incineration): Mulch film can be used as a high-calorific-value fuel with extremely high combustion calorific value and great potential for heat recovery. If it is not burned harmlessly in professional incineration equipment, ordinary open-air burning will produce toxic and harmful substances such as dioxins, directly polluting the soil and air, endangering human health, and negatively impacting the surrounding agricultural environment.

[0003] Wood-based biomass fuels are made from wood-based raw materials such as sawdust, fruit tree branches, and forestry residues. These fuels have good compositional uniformity, extremely low impurity and heavy metal content, good thermal stability, are not prone to slagging, have high combustion efficiency, and produce very low CO and nitrogen oxide emissions. However, the raw materials rely on forestry resources, resulting in high raw material screening costs, and large-scale production may put some pressure on timber supply.

[0004] Non-timber biomass fuels mainly consist of non-timber raw materials such as straw, rice husks, bagasse, and agricultural waste. These fuels have extremely low raw material costs, but the raw materials are scattered and vary widely in type, resulting in poor consistency of the finished product. They also tend to have higher alkali metal and chlorine content, making them more prone to slagging during combustion. The generation of nitrogen oxides is higher than that of wood fuels, and direct combustion can easily produce black smoke, thus requiring more stringent anti-slagging designs for combustion equipment.

[0005] Waste agricultural mulch film, wood biomass, and non-wood biomass each have their advantages and disadvantages as fuels. If these three are combined to develop a high-calorific-value, non-slagging, and low-emission high-energy clean fuel, it will greatly reduce the pressure on forestry resources, reduce my country's high dependence on foreign oil and gas, significantly reduce pollutant emissions, and alleviate the greenhouse effect. Summary of the Invention

[0006] The purpose of this invention is to develop a high-energy composite matrix fuel with pine wood as the main component and mulch film and walnut shells as the additives. Under the premise of meeting the "Quality Classification of Biomass Pellets" indicators and the mandatory standards for solid waste incineration in China, this invention improves the overall calorific value of fuel pellets, makes up for the shortcomings of pure pine wood pellets which have low calorific value and high volatile matter content, and realizes the resource utilization of waste mulch film and walnut shells.

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0008] A method for preparing a high-energy composite matrix fuel with pine wood as the main component and incorporating mulch film and walnut shells includes the following steps:

[0009] S1. Pine waste wood, waste walnut shells and waste agricultural mulch film are pretreated to obtain pine wood pellets, walnut shell pellets and mulch film fragments respectively;

[0010] S2. Mix the pine wood particles, walnut shell particles and plastic film fragments evenly at a mass ratio of (70-90):(5-10):(5-20) to obtain a mixture.

[0011] S3. The mixture is fed into a ring die pellet mill, extruded and cut under molding pressure and ring die compression ratio to obtain rod-shaped composite matrix fuel pellets.

[0012] Preferably, in step S1, the pine wood particles have a particle size of ≤5 mm and a moisture content of 12%-15%; the walnut shell particles have a particle size of 2-5 mm and a moisture content of 12%-15%; and the plastic film fragments have a particle size of 1-3 cm.

[0013] Preferably, in step S1, the pine waste wood is processed by removing impurities, chipping, crushing, and drying to obtain the pine wood particles; the waste walnut shells are processed by removing impurities, crushing, and drying to obtain the walnut shell particles; and the waste agricultural mulch film is processed by removing impurities, crushing, washing, and drying to obtain the mulch film fragments.

[0014] Preferably, in step S2, the pine wood particles, walnut shell particles and mulch film fragments are mixed evenly in a mass ratio of (80-90):(5-10):(5-10).

[0015] Preferably, in step S3, the molding pressure is 50-100 MPa; and the ring die compression ratio is 1:6.

[0016] Preferably, in step S3, the mixture is first extruded into long strip-shaped particles, and then cut into rod-shaped particles, the length of which is 8-12 mm.

[0017] The present invention also provides a high-energy composite matrix fuel prepared according to the above preparation method.

[0018] Preferably, the high-energy composite matrix fuel has an as-received lower heating value ≥16 MJ / kg, a sulfur content ≤0.07%, a chlorine content ≤0.07%, a nitrogen content ≤0.5%, and an ash content ≤3%.

[0019] Preferably, the dry basis moisture content of the high-energy composite matrix fuel is ≤8% and the volatile matter content is <75%.

[0020] Preferably, the dioxin emission of the high-energy composite matrix fuel is ≤0.1 ng TEQ / m³. 3 .

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention proposes a high-energy composite matrix fuel based on pine wood, incorporating waste agricultural mulch film and walnut shells, and its preparation method. The high-energy composite matrix fuel is prepared under high pressure by incorporating waste agricultural mulch film and waste walnut shells into pine biomass. When the amount of black mulch film incorporated is ≤20%, the high-energy composite matrix fuel developed by this invention meets the indicators of the "Quality Classification of Biomass Pellets" and the mandatory standards for solid waste incineration in China, with the overall calorific value of the fuel pellets increasing by up to approximately 17.11%. When the amount of black mulch film incorporated is ≤10% and the amount of walnut shells incorporated is ≥5%, the calorific value of the high-energy composite matrix fuel developed by this invention is effectively increased while the volatile matter content is effectively reduced, and its finished product quality grade is Grade 1 briquetted fuel.

[0023] 2. This invention can, to some extent, compensate for the shortcomings of pure pine wood pellets, which have low calorific value and high volatile matter content. Simultaneously, it converts waste plastic film and walnut shells into usable fuel, realizing the resource utilization of solid waste and reducing the processing costs of waste plastic film and walnut shells. Furthermore, the procurement cost of waste plastic film and walnut shells is far lower than that of pine wood raw materials. Their inclusion directly reduces the production cost of fuel pellets, resulting in a lower selling price compared to pure pine wood pellets, thus better meeting the production and sales needs of small and medium-sized enterprises for fuel pellets. Detailed Implementation

[0024] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0025] Example 1

[0026] A method for preparing a high-energy composite matrix fuel with pine wood as the main component, mixed with plastic film and walnut shells, comprising the following steps:

[0027] S1. Pre-treatment of pine waste wood: Sorting and removing non-combustible impurities such as metal, stones, and soil; using a crusher and chipper to cut large pieces of pine waste wood into wood chips 2-5 cm long and ≤1 cm thick; then using a high-efficiency pulverizer to further pulverize the wood chips into wood chips ≤5 mm; and finally using a drum dryer to adjust the moisture content of the wood chips to 12%-15%.

[0028] Walnut shell pretreatment: Vibrating screen removes soil and broken shell fragments, then magnetic separator removes metal impurities, jaw crusher crushes large walnut shells into coarse material with a particle size ≤5 cm, drum dryer adjusts the moisture content of coarse material to 12%-15%, and then hammer mill crushes coarse material into fine powder with a particle size of 2-5 mm.

[0029] Pre-treatment of waste agricultural mulch film (PE black mulch film): Screen out large pieces of soil, stones, crop roots and other impurities adhering to the surface of the waste agricultural mulch film. Cut the large pieces of mulch film into 5-10 cm pieces using a plastic crusher. The mulch film fragments are then crushed into small pieces. The coarsely crushed mulch film pieces are sent to a washing tank to wash away residual soil and impurities. After being drained, the washed small pieces are further crushed into 1-3 cm fragments using a fine crushing device.

[0030] S2. Pine sawdust is the main component, mixed with fine walnut shell powder and plastic film fragments, in a mass percentage ratio of pine wood: walnut shell: plastic film = 90%: 5%: 5%.

[0031] S3. A mixture of pine sawdust, walnut shell powder, and plastic film fragments is fed into a ring die pellet mill. Under high pressure of 50-100 MPa and a ring die compression ratio of 1:6, it is extruded into high-density strip-shaped pellets, which are then cut into rod-shaped pellets of 8-12 mm.

[0032] The prepared high-energy composite matrix fuel particles were tested for their received lower heating value, sulfur content, chlorine content, nitrogen content, and ash content, as well as their dry basis moisture content, volatile matter content, and dioxin emissions.

[0033] Low heating value test upon receipt: Refer to GB / T 30727-2014 "Determination of heating value of solid biomass fuels", oxygen bomb calorimetry;

[0034] Sulfur content detection: Refer to GB / T 35816-2018 "Determination of Sulfur and Chlorine in Solid Biomass Fuels", ion chromatography method;

[0035] Chlorine content detection: Refer to GB / T 35816-2018 "Determination of Sulfur and Chlorine in Solid Biomass Fuels", oxygen bomb combustion-ion chromatography method;

[0036] Nitrogen content determination: Refer to GB / T 28731-2012 "Analytical Methods for Solid Biomass Fuel Industry", Kjeldahl method;

[0037] Ash content detection: Refer to GB / T 28731-2012 "Analytical Methods for Solid Biomass Fuel Industry", high-temperature calcination gravimetric method;

[0038] Moisture content determination on desiccated basis: Refer to GB / T 28731-2012 "Analytical Methods for Solid Biomass Fuel Industry", oven drying constant weight method;

[0039] Volatile matter content detection: Refer to GB / T 212-2008 "Industrial Analysis Methods for Coal";

[0040] Dioxin emission detection: Refer to HJ 77.2-2008 "Determination of Dioxins in Ambient Air", Isotope dilution high-resolution gas chromatography-high-resolution mass spectrometry Kjeldahl method.

[0041] Example 2

[0042] This embodiment is basically the same as Embodiment 1, except that the raw material mixing ratio is pine wood: walnut shell: mulch film = 80%: 10%: 10% (mass percentage).

[0043] Example 3

[0044] This embodiment is basically the same as Embodiment 1, except that the raw material mixing ratio is pine wood: walnut shell: mulch film = 75%: 10%: 15% (mass percentage).

[0045] Example 4

[0046] This embodiment is basically the same as Embodiment 1, except that the raw material mixing ratio is pine wood: walnut shell: mulch film = 70%: 10%: 20% (mass percentage).

[0047] Example 5

[0048] This embodiment is basically the same as Embodiment 1, except that the raw material mixing ratio is pine wood: walnut shell: mulch film = 70%: 5%: 25% (mass percentage).

[0049] Example 6

[0050] This embodiment is basically the same as embodiment 1, except that the raw materials do not contain walnut shells, and the raw material mixing ratio is pine wood: mulch film = 95%: 5% (mass percentage).

[0051] Example 7

[0052] This embodiment is basically the same as embodiment 1, except that the raw materials do not contain walnut shells, and the raw material mixing ratio is pine wood: mulch film = 90%: 10% (mass percentage).

[0053] Example 8

[0054] This embodiment is basically the same as embodiment 1, except that the raw materials do not contain walnut shells, and the raw material mixing ratio is pine wood: mulch film = 85%: 15% (mass percentage).

[0055] Example 9

[0056] This embodiment is basically the same as embodiment 1, except that the raw materials do not contain walnut shells, and the raw material mixing ratio is pine wood: mulch film = 80%: 20% (mass percentage).

[0057] Example 10

[0058] This embodiment is basically the same as embodiment 1, except that the raw materials do not contain mulch film, and the raw material mixing ratio is pine wood: walnut shell = 95%: 5% (mass percentage).

[0059] Table 1. Detection indicators of pine wood, walnut shells, black plastic film, and fuel particles obtained in Examples 1-10

[0060] According to the domestic biomass briquette fuel quality index system NB / T 34024-2015 "Quality Grading of Biomass Briquette Fuels", the indicators for Grade 1 (high-quality) wood-based biomass briquette fuel are as follows: net calorific value ≥16 MJ / kg (as received), moisture content ≤8% (dry basis), sulfur content ≤0.07%, chlorine content ≤0.07%, nitrogen content ≤0.5%, ash content ≤3%, and volatile matter content <75%. The indicators for Grade 2 (qualified) fuel are as follows: net calorific value ≥14 MJ / kg (as received), moisture content ≤10% (dry basis), sulfur content ≤0.1%, chlorine content ≤0.1%, nitrogen content ≤0.5%, ash content ≤8%, and volatile matter content <80%. According to the unified requirements of domestic mandatory standards for solid waste incineration, the dioxin emission limit is ≤0.1 ng TEQ / m³. 3 .

[0061] Pine wood belongs to the high-calorific-value category of woody biomass fuels, with a net calorific value (LCV) of 16.97 MJ / kg, far exceeding the 15.05-16.73 MJ / kg of ordinary wood fuels, placing it among the top-performing categories in terms of calorific value. Walnut shells also belong to the high-calorific-value category of non-woody biomass fuels, with an LCV of 16.70 MJ / kg, far exceeding the 12.96-15.05 MJ / kg of ordinary non-woody fuels, placing them among the top-performing categories in terms of calorific value. It is worth noting that compared to biomass fuels, plastic film has a much higher calorific value (31.49 MJ / kg), but due to poor processing adaptability, high emission control difficulty, and poor equipment compatibility, it cannot be directly used as fuel. To compensate for the relatively low calorific value of pure pine pellets and to convert waste plastic film into usable fuel, thus achieving the resource utilization of solid waste, this study aims to address these issues. This invention uses pine wood as the main component, incorporating plastic film (and walnut shells) to prepare a high-energy composite matrix fuel. As shown in Table 1, since the calorific value of walnut shells is the lowest among the three raw materials, the incorporation of walnut shells reduces the calorific value of the biomass fuel pellets prepared in the examples. For example, the calorific values ​​of the biomass fuel pellets obtained in Example 1 (pine wood: walnut shells: plastic film = 90%: 5%: 5%) and Example 10 (pine wood: walnut shells = 95%: 5%) are 17.68 MJ / kg and 16.96 MJ / kg, respectively, but both are lower than the calorific value of the biomass fuel pellets obtained in Example 6 (pine wood: plastic film = 95%: 5%) (17.70 MJ / kg). This indicates that the incorporation of walnut shells does not improve the calorific value of the composite matrix fuel prepared in the examples. Conversely, due to the high calorific value of black mulch film, the calorific value of the composite matrix fuel produced by incorporating black mulch film, regardless of whether walnut shells are added, is higher than that of pine pellets. For example, the net calorific value (NDV) of the composite matrix fuels obtained in Examples 1-9 ranged from 17.68-20.59 MJ / kg to >16.97 MJ / kg (NDV of pine pellets), significantly exceeding the Grade 1 (high-quality) standard for woody biomass briquettes in the "Quality Classification of Biomass Briquette Fuels": NDV ≥ 16 MJ / kg. Furthermore, in the examples, the calorific value of the resulting composite matrix fuel increased with increasing black mulch film content. This indicates that incorporating black mulch film can effectively improve the calorific value of composite matrix fuel. Although incorporating black mulch film can effectively improve the calorific value of composite matrix fuel, it is not permitted to incorporate it without limitation. For instance, in Example 5, with a black mulch film content of 25%, the dioxin emission of the resulting composite matrix fuel was 0.107 ng TEQ / m³. 3 >0.1 ngTEQ / m 3This does not meet the unified requirements of the mandatory standards for solid waste incineration in China. Therefore, the amount of black plastic film added should be controlled at ≤20%. When the amount of black plastic film added is 20%, the received basis lower heating values ​​of the composite matrix fuels obtained in Examples 4 (pine wood: walnut shell: plastic film = 70%:10%:20%) and 9 (pine wood: plastic film = 80%:20%) are 19.85 MJ / kg and 19.87 MJ / kg, respectively, which increases the overall calorific value of the fuel by 16.95% and 17.11%, respectively.

[0062] Because the dry basis moisture content of pine wood and walnut shell shaped fuel pellets is low, at 4.72% and 6.20% respectively. In addition, the finished PE black mulch film itself contains almost no free water, only a trace amount of adsorbed water, and its dry basis moisture content is extremely low (1.27%). Therefore, the dry basis moisture content of the composite matrix fuel pellets obtained in Examples 1-10 ranges from 3.93% to 4.79%, all of which are far below the first-level index of wood biomass shaped fuel in the "Quality Grading of Biomass Pellet Fuel": dry basis moisture content ≤8%.

[0063] The waste agricultural black mulch film used in this invention is made of PE material and is chlorine-free. The production process basically does not add sulfur-containing additives or nitrogen-containing additives. As a result, the chlorine (0%), sulfur (0.002%) and nitrogen (0.12%) content of the black mulch film is very low. In addition, pine wood is a clean fuel with low chlorine (0.005%), low sulfur (0.020%) and low nitrogen (0.430%), and walnut shells are also a clean fuel with low chlorine (0.031%), low sulfur (0.038%) and low nitrogen (0.320%). Therefore, the sulfur content (0.016%-0.021%), chlorine content (0.004%-0.007%), and nitrogen content (0.347%-0.425%) of the composite matrix fuel pellets obtained in Examples 1-10 are all far lower than the first-level indicators for woody biomass briquettes in the "Quality Classification of Biomass Briquettes": sulfur content ≤0.07%, chlorine content ≤0.07%, and nitrogen content ≤0.5%.

[0064] As is well known, the ash content of wood-based biomass fuels is much lower than that of straw-based biomass fuels. Among various wood-based biomass, pine has the lowest ash content, at only 0.43%. Walnut shell biomass fuel has a relatively low ash content among non-wood-based biomass fuels (10%-18%), at 4.1%. The ash content of commercial PE black mulch film mainly comes from carbon black (used for coloring) and processing aid residues, and its ash content is theoretically not high. However, this invention uses recycled waste agricultural black mulch film. Although it is washed during the fuel pellet preparation process, some soil and dust may still adhere to the surface of the film, resulting in a higher ash content of 19.36%. Therefore, the ash content of the composite matrix fuel prepared in this example is mainly determined by the amount of recycled mulch film incorporated. When the amount of black plastic film added is ≤10% (Examples 1, 2, 6 and 7), the ash content of the finished fuel pellets (1.377%-2.69%) is lower than the first-level indicator of wood biomass briquettes in the "Quality Grading of Biomass Briquettes": ash content ≤3%. However, when the amount of black plastic film added is >10% (Examples 3-5, 8 and 9), the ash content of the finished fuel pellets (3.27%-5.346%) no longer meets the first-level indicator requirement of the "Quality Grading of Biomass Briquettes", and the quality grade drops to second-level (qualified product) (ash content ≤8%).

[0065] Pine wood is a high-volatile fuel, with a volatile content of 78%. Furthermore, the recycled waste agricultural black plastic film used in this invention also has a high volatile content of 78.37%. The volatile content of both pine wood and black plastic film is higher than the first-level index (<75%) for wood-based biomass briquettes in the "Quality Classification of Biomass Briquettes," but lower than the second-level index (<80%). Therefore, if the fuel raw materials are only pine wood and black plastic film, regardless of the mixing ratio (Examples 6-9), the volatile content of the finished fuel pellets (78.02%-78.07%) is higher than the first-level index but lower than the second-level index, and the finished product can only be classified as second-level briquettes. To reduce the volatile content of the finished fuel pellets to meet the first-level index requirements of the "Quality Classification of Biomass Briquettes," this invention adds a low-volatile fuel raw material: walnut shells, with a volatile content of 7.18%. As long as the amount of walnut shells added is ≥5%, the volatile matter content of the composite matrix fuel particles obtained in Examples 1-5 and Example 10 is 70.99%-74.55%, which is lower than the first-level index. This shows that the addition of walnut shells can effectively reduce the volatile matter content of the composite matrix fuel prepared in the examples, so that the finished product quality grade is first-level molded fuel.

[0066] While PE black mulch film itself does not contain dioxins, PE has a low melting point and easily melts and clumps when burned directly, making it difficult to burn completely and thus increasing the generation of dioxins. This results in relatively high dioxin emissions (0.3 ng TEQ / m³). 3However, the raw materials, pine wood and walnut shells, have few impurities and a loose structure that makes them easy to burn. Under complete combustion conditions, the dioxin production is extremely low, with dioxin emissions of 0.042 ngTEQ / m³. 3 and 0.052 ng TEQ / m 3 When the amount of black plastic film incorporated is ≤20%, the dioxin emissions of biomass fuel pellets obtained in Examples 1-4 and 6-9 are 0.055-0.095 ng TEQ / m³. 3 All emissions are below the unified requirements of the mandatory national standards for solid waste incineration, with dioxin emission limits of ≤0.1 ng TEQ / m³. 3 However, when the amount of black plastic film incorporated is >20%, the dioxin emission of the biomass fuel pellets obtained in Example 5 is 0.107 ng TEQ / m³. 3 >0.1 ng TEQ / m 3 It does not meet the unified requirements of the mandatory standards for solid waste incineration in China.

[0067] In summary, this invention proposes a high-energy composite matrix fuel based on pine wood mixed with waste agricultural mulch film and walnut shells, and its preparation method. The high-energy composite matrix fuel is prepared under high pressure by mixing pine biomass as the main component with waste agricultural mulch film and waste walnut shells. When the amount of black mulch film mixed in is ≤20%, the high-energy composite matrix fuel developed by this invention meets the indicators of the "Quality Classification of Biomass Pellets" and the mandatory standards for solid waste incineration in China, with the overall calorific value of the fuel pellets increasing by up to approximately 17.11%. When the amount of black mulch film mixed in is ≤10% and the amount of walnut shells mixed in is ≥5%, the calorific value of the high-energy composite matrix fuel developed by this invention is effectively increased while the volatile matter content is effectively reduced, and its finished product quality grade is Grade 1 briquetted fuel. This invention can, to a certain extent, compensate for the shortcomings of low calorific value and high volatile matter content in pure pine wood pellets, while converting waste agricultural mulch film and walnut shells into usable fuel, realizing the resource utilization of solid waste, and reducing the processing cost of waste agricultural mulch film and walnut shells. In addition, the purchase cost of waste plastic film and walnut shells is much lower than that of pine wood raw materials. When mixed in, they can directly reduce the production cost of fuel pellets and have a lower selling price than pure pine wood pellets, thus better meeting the needs of small and medium-sized enterprises for the production and sales of fuel pellets.

[0068] The above detailed description is a specific description of the embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. A method for preparing a high-energy composite matrix fuel consisting mainly of pine wood mixed with plastic film and walnut shells, characterized in that, Includes the following steps: S1. Pine waste wood, waste walnut shells and waste agricultural mulch film are pretreated to obtain pine wood pellets, walnut shell pellets and mulch film fragments respectively; S2. Mix the pine wood particles, walnut shell particles and plastic film fragments evenly at a mass ratio of (70-90):(5-10):(5-20) to obtain a mixture. S3. The mixture is fed into a ring die pellet mill, extruded and cut under molding pressure and ring die compression ratio to obtain rod-shaped composite matrix fuel pellets.

2. The preparation method according to claim 1, characterized in that, In step S1, the pine wood particles have a particle size of ≤5mm and a moisture content of 12%-15%; the walnut shell particles have a particle size of 2-5mm and a moisture content of 12%-15%; and the plastic film fragments have a particle size of 1-3cm.

3. The preparation method according to claim 1, characterized in that, In step S1, the pine waste wood is processed by removing impurities, chipping, crushing, and drying to obtain the pine wood particles; the waste walnut shells are processed by removing impurities, crushing, and drying to obtain the walnut shell particles; and the waste agricultural mulch film is processed by removing impurities, crushing, washing, and drying to obtain the mulch film fragments.

4. The preparation method according to claim 1, characterized in that, In step S2, the pine wood particles, walnut shell particles and plastic film fragments are mixed evenly in a mass ratio of (80-90):(5-10):(5-10).

5. The preparation method according to claim 1, characterized in that, In step S3, the molding pressure is 50-100 MPa; the ring die compression ratio is 1:

6.

6. The preparation method according to claim 1, characterized in that, In step S3, the mixture is first extruded into long strip-shaped particles, and then cut into rod-shaped particles with a length of 8-12 mm.

7. The high-energy composite matrix fuel prepared by the preparation method according to any one of claims 1-6.

8. The high-energy composite matrix fuel according to claim 7, characterized in that, The high-energy composite matrix fuel has an as-received lower heating value ≥16 MJ / kg, sulfur content ≤0.07%, chlorine content ≤0.07%, nitrogen content ≤0.5%, and ash content ≤3%.

9. The high-energy composite matrix fuel according to claim 7, characterized in that, The high-energy composite matrix fuel has a dry basis moisture content of ≤8% and a volatile matter content of <75%.

10. The high-energy composite matrix fuel according to claim 7, characterized in that, The dioxin emissions of the high-energy composite matrix fuel are ≤0.1 ng TEQ / m³. 3 .

Images