A biomass pellet fuel with low water content and a preparation method thereof

Abstract

The present invention relates to the field of biomass fuel preparation, and more specifically, to a low-moisture biomass pellet fuel and its preparation method. The present invention provides a method for preparing low-moisture biomass pellet fuel. By utilizing a moisture method and enhanced solidification of biomass pellets, the method effectively improves the pellets' moisture resistance, reduces moisture content, increases storage stability, and improves combustion efficiency. This method is not only environmentally friendly and cost-effective, but also widely adaptable and has promising industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the field of biomass fuel preparation, and in particular to a biomass pellet fuel with low water content and a preparation method thereof. Background Art

[0002] Biomass energy, a renewable, environmentally friendly, and clean energy source, has garnered widespread attention and research worldwide in recent years. It not only helps alleviate fossil fuel depletion but also plays a significant role in reducing greenhouse gas emissions. Among various biomass energy sources, bamboo and wood biomass pellets have become a major research hotspot in the biomass energy field due to their significant advantages, including widespread availability, low production costs, and strong sustainability.

[0003] However, in practical applications, the storage and use of bamboo and wood biomass pellets face a major challenge: hygroscopicity. Especially in high-humidity environments, biomass pellets readily absorb moisture, which not only degrades the pellets' quality, such as reduced hardness and increased brittleness, but also seriously affects their storage stability. Furthermore, hygroscopic biomass pellets often produce increased smoke and harmful gases during combustion, reducing combustion efficiency and increasing the risk of environmental pollution.

[0004] To address this issue, several studies have attempted to enhance the moisture resistance of biomass pellets through physical or chemical methods. While these approaches have achieved some success, most still fail to fundamentally address the moisture absorption and storage stability issues of biomass pellets in humid environments. Furthermore, many existing curing enhancement methods often rely on chemical additives, which not only increases production costs but also poses potential negative impacts on the environment and human health, thus limiting their widespread application.

[0005] Therefore, it is necessary to invent a new method that can effectively improve the moisture resistance of bamboo and wood biomass particles while avoiding the environmental burden and safety hazards brought about by traditional curing technology. Summary of the Invention

[0006] To address the above-mentioned existing technical problems, the present invention provides a low-moisture biomass pellet fuel and a method for its preparation. This method utilizes a moisture-curing method and enhanced solidification of biomass pellets to effectively improve the pellets' moisture resistance, reduce moisture content, increase storage stability, and enhance combustion efficiency. This method is not only environmentally friendly and cost-effective, but also widely adaptable and has promising industrial application prospects.

[0007] The present invention discloses a method for preparing a biomass pellet fuel with low water content, comprising the following preparation steps:

[0008] S1 Raw material pretreatment: After removing impurities from the bamboo wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the screened raw material particles is 3-5 mm; the raw material particles are evenly laid in a wet environment box, and the humidity, temperature and time of the wet environment box are set to perform moisture pretreatment on the raw material particles;

[0009] S2 curing treatment: The raw material particles that have undergone moisture pretreatment in step S1 are taken out of the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution for heating and soaking. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity and temperature of the enhanced curing box are set, and the particles are subjected to enhanced curing treatment. After the curing is completed, cured biomass particles are obtained;

[0010] S3 Particle Forming and Drying: The solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 100 to 500 μm, and then placed in a drying oven for low-temperature drying treatment. After the treatment is completed, a biomass pellet fuel with a low water content is obtained.

[0011] Preferably, in the raw material pretreatment step S1, the humidity of the wet environment box is 70-80%.

[0012] Preferably, in the S1 raw material pretreatment step, the temperature of the wet environment box is 50-80°C.

[0013] Preferably, in the S1 raw material pretreatment step, the moisture pretreatment time is 12 to 15 hours.

[0014] Preferably, in the S2 solidification treatment step, the mass fraction of the sodium silicate solution is 23-38%.

[0015] Preferably, in the S2 solidification treatment step, the heating and soaking temperature in the sodium silicate solution is 45 to 55° C., and the soaking time is 1 to 2 hours.

[0016] Preferably, in the S2 curing treatment step, the humidity of the enhanced curing box is 50-60%.

[0017] Preferably, in the S2 curing treatment step, the temperature of the enhanced curing box is 50-60° C.; and the time of the enhanced curing treatment is 8-12 hours.

[0018] Preferably, in the S3 particle forming and drying step, the drying temperature of the drying oven is 35-45° C.; and the drying time is 6-8 hours.

[0019] A low-moisture biomass pellet fuel is prepared by any of the above-mentioned methods for preparing a low-moisture biomass pellet fuel.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for preparing a low-moisture biomass pellet fuel. Through moisture pretreatment and enhanced curing steps, the cross-linked structure formed on the surface of bamboo wood pellets can effectively reduce moisture absorption, greatly improving the moisture resistance of the pellets; while ensuring the strength of the pellets, the moisture content can be effectively reduced and the storage stability can be improved; no chemical additives are required, and the method is more environmentally friendly than traditional chemical curing methods, avoiding potential negative impacts on the environment; after the moisture content of the pellets is effectively controlled, the combustion process is more stable, the combustion efficiency is higher, and less smoke and exhaust gas are generated, meeting environmental protection requirements; the wet gas treatment process is simple, easy to industrialize, and relatively low in cost, making it suitable for large-scale production and application.

[0022] The biomass pellet fuel prepared by the preparation method provided by the present invention has low water content, high moisture resistance, good storage stability and combustion efficiency. DETAILED DESCRIPTION

[0023] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0024] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0025] Example 1: A method for preparing biomass pellet fuel with low water content, comprising the following steps:

[0026] S1 Raw material pretreatment: After removing impurities from the bamboo and wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the raw material particles after screening is 5 mm; the raw material particles are evenly laid in a moisture environment box, and the humidity of the moisture environment box is set to 70%, and the temperature of the moisture environment box is set to 50°C. The raw material particles are moisture pretreated for 12 hours.

[0027] S2 curing treatment: The raw material particles that have been moisture pretreated in step S1 are taken out of the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution heated to 45°C and soaked for 1 hour. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity of the enhanced curing box is set to 50%, and the temperature of the enhanced curing box is set to 50°C. The particles are subjected to enhanced curing treatment for 8 hours. After the curing is completed, cured biomass particles are obtained.

[0028] S3 particle forming and drying: The solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 500 μm, and then placed in a drying oven for low-temperature drying treatment at a temperature of 35°C and a drying time of 6 hours. After the treatment is completed, a biomass pellet fuel with a low moisture content is obtained.

[0029] Example 2: A method for preparing biomass pellet fuel with low water content, comprising the following steps:

[0030] S1 Raw material pretreatment: After removing impurities from the bamboo and wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the raw material particles after screening is 4.5 mm; the raw material particles are evenly laid in a moisture environment box, and the humidity of the moisture environment box is set to 72%, and the temperature of the moisture environment box is set to 60°C. The raw material particles are moisture pretreated for 12.5 hours.

[0031] S2 curing treatment: The raw material particles that have undergone moisture pretreatment in step S1 are taken out from the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution and heated to 47°C for soaking for 1.2 hours. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity of the enhanced curing box is set to 52%, and the temperature of the enhanced curing box is set to 52°C. The particles are subjected to enhanced curing treatment for 9 hours. After the curing is completed, cured biomass particles are obtained.

[0032] S3 particle forming and drying: The solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 400 μm, and then placed in a drying oven for low-temperature drying treatment at a temperature of 37°C and a drying time of 6.5 hours. After the treatment is completed, a biomass pellet fuel with a low moisture content is obtained.

[0033] Example 3: A method for preparing biomass pellet fuel with low water content, comprising the following steps:

[0034] S1 Raw material pretreatment: After removing impurities from the bamboo and wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the raw material particles after screening is 4 mm; the raw material particles are evenly laid in a moisture environment box, and the humidity of the moisture environment box is set to 75%, and the temperature of the moisture environment box is set to 65°C. The raw material particles are moisture pretreated for 13 hours.

[0035] S2 curing treatment: The raw material particles that have undergone moisture pretreatment in step S1 are taken out from the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution, heated to 50°C and soaked for 1.5 hours. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity of the enhanced curing box is set to 55%, and the temperature of the enhanced curing box is set to 55°C. The particles are subjected to enhanced curing treatment for 10 hours. After the curing is completed, cured biomass particles are obtained.

[0036] S3 particle forming and drying: the solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 300 μm, and then placed in a drying oven for low-temperature drying treatment at a temperature of 40°C and a drying time of 7 hours. After the treatment is completed, a biomass pellet fuel with a low moisture content is obtained.

[0037] Example 4: A method for preparing biomass pellet fuel with low water content, comprising the following steps:

[0038] S1 Raw material pretreatment: After removing impurities from the bamboo and wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the raw material particles after screening is 3.5 mm; the raw material particles are evenly laid in a moisture environment box, and the humidity of the moisture environment box is set to 77%, and the temperature of the moisture environment box is set to 70°C. The raw material particles are moisture pretreated for 14 hours.

[0039] S2 curing treatment: The raw material particles that have undergone moisture pretreatment in step S1 are taken out from the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution and heated to 52°C for soaking for 1.7 hours. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity of the enhanced curing box is set to 57%, and the temperature of the enhanced curing box is set to 57°C. The particles are subjected to enhanced curing treatment for 11 hours. After the curing is completed, cured biomass particles are obtained.

[0040] S3 particle forming and drying: The solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 200 μm, and then placed in a drying oven for low-temperature drying treatment at a temperature of 42°C and a drying time of 7.5 hours. After the treatment is completed, a biomass pellet fuel with a low moisture content is obtained.

[0041] Example 5: A method for preparing biomass pellet fuel with low water content, comprising the following steps:

[0042] S1 Raw material pretreatment: After removing impurities from the bamboo and wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the raw material particles after screening is 3 mm; the raw material particles are evenly laid in a moisture environment box, and the humidity of the moisture environment box is set to 80%, and the temperature of the moisture environment box is set to 80°C. The raw material particles are moisture pretreated for 15 hours.

[0043] S2 curing treatment: The raw material particles that have undergone moisture pretreatment in step S1 are taken out from the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution heated to 55°C and soaked for 2 hours. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity of the enhanced curing box is set to 60%, and the temperature of the enhanced curing box is set to 60°C. The particles are subjected to enhanced curing treatment for 12 hours. After the curing is completed, cured biomass particles are obtained.

[0044] S3 particle forming and drying: the solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 100 μm, and then placed in a drying oven for low-temperature drying treatment at a temperature of 45°C and a drying time of 8 hours. After the treatment is completed, a biomass pellet fuel with a low moisture content is obtained.

[0045] Example 6: The step of hot soaking in sodium silicate solution in the preparation method is removed, and the remaining preparation steps and parameters are the same as those in Example 4.

[0046] The performance of the biomass pellet fuels prepared in Examples 1 to 6 was tested, and the test results are shown in the following table:

[0047]

[0048]

[0049] From the experimental data described in the above table, it can be seen that: as the moisture pretreatment time and temperature of the biomass pellet fuel prepared in Examples 1 to 5 increase, the moisture content of the biomass pellets gradually decreases and tends to be stable; the density increases with the change of treatment conditions; as the humidity and temperature of the curing treatment increase, the calorific value of the pellets gradually increases, the volatile matter content gradually decreases, and the fixed carbon content gradually increases; the compressive strength of the pellets increases with the optimization of the moisture pretreatment and curing process.

[0050] This is because the biomass pellets are soaked in a silicon solution for hot soaking and then cured using a moisture method. By controlling the humidity and temperature, the silicon-based material is promoted to combine with the bamboo wood fiber, forming a stable three-dimensional network structure. The synergistic effect of the silicon-based reinforcing agent and the moisture method causes the bamboo wood pellets to form a moisture-proof silicon-based protective film during the curing process, which can significantly improve the pellets' moisture resistance and reduce the biomass pellets' moisture absorption in humid environments. This improves the storage stability of the biomass pellets, extends the storage period, reduces the risk of the fuel getting damp during transportation and storage, and enhances combustion efficiency.

[0051] Example 7: To investigate the effects of different mass fractions of sodium silicate solution on the properties of biomass pellet fuel, the mass fractions of the screened sodium silicate solutions were 23%, 27%, 30%, 35%, and 38%, respectively. The remaining raw material ratios and experimental procedures were the same as in Example 4. The experimental results are shown in the following table:

[0052]

[0053]

[0054] The experimental data in the table above show that as the mass fraction of the sodium silicate solution increases, the moisture content of the particles gradually decreases and stabilizes; as the mass fraction of the sodium silicate solution increases, the mass fraction of the particles changes little; and as the mass fraction of the sodium silicate solution increases, the calorific value of the particles increases slightly, and the compressive strength of the particles also increases. The optimal mass fraction of the sodium silicate solution is 35%.

[0055] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing biomass pellet fuel with low water content, characterized in that: The following steps are involved: S1 Raw material pretreatment: After removing impurities from the bamboo wood raw materials, put them into a grinder for crushing, cutting and screening. The diameter of the screened raw material particles is 3-5 mm. The raw material particles are evenly laid in a wet environment box, and the humidity, temperature and time of the wet environment box are set to perform moisture pretreatment on the raw material particles. S2 curing treatment: The raw material particles that have undergone moisture pretreatment in step S1 are taken out of the moisture environment box, shaken to remove surface moisture, and then placed in a sodium silicate solution for heating and soaking. After the soaking is completed, the solid particles are filtered and collected and placed in an enhanced curing box. The humidity and temperature of the enhanced curing box are set, and the particles are subjected to enhanced curing treatment. After the curing is completed, cured biomass particles are obtained; S3 Particle Forming and Drying: The solidified biomass particles obtained in step S2 are placed in a press to be pressed into biomass particles with a diameter of 100-500 μm, and then placed in a drying oven for low-temperature drying treatment. After the treatment is completed, a biomass pellet fuel with a low water content is obtained; The mass fraction of the sodium silicate solution is 23-38%.

2. The method for preparing a low-water content biomass pellet fuel according to claim 1, characterized in that: In the S1 raw material pretreatment step, the humidity of the wet environment box is 70-80%.

3. The method for preparing a low-water content biomass pellet fuel according to claim 1, characterized in that: In the S1 raw material pretreatment step, the temperature of the wet environment box is 50-80°C.

4. The method for preparing a biomass pellet fuel with low water content according to claim 1, characterized in that: In the S1 raw material pretreatment step, the moisture pretreatment time is 12 to 15 hours.

5. The method for preparing a biomass pellet fuel with low water content according to claim 1, characterized in that: In the S2 solidification treatment step, the heating and soaking temperature in the sodium silicate solution is 45-55° C. and the soaking time is 1-2 hours.

6. The method for preparing a biomass pellet fuel with low water content according to claim 1, characterized in that: In the S2 curing treatment step, the humidity of the enhanced curing box is 50-60%.

7. The method for preparing a biomass pellet fuel with low water content according to claim 1, characterized in that: In the S2 curing treatment step, the temperature of the enhanced curing box is 50-60° C.; and the enhanced curing treatment time is 8-12 hours.

8. The method for preparing a biomass pellet fuel with low water content according to claim 1, characterized in that: In the S3 particle forming and drying step, the drying temperature of the drying oven is 35-45° C. and the drying time is 6-8 hours.

9. A low-moisture biomass pellet fuel prepared by the method for preparing a low-moisture biomass pellet fuel according to any one of claims 1 to 8.

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