Biomass pellet fuel with low water content and preparation method thereof

Abstract

The invention relates to the field of biomass fuel preparation, in particular to low-water-content biomass pellet fuel and a preparation method thereof. According to the preparation method of the low-water-content biomass granular fuel, the moisture resistance of the granules can be effectively improved, the water content can be reduced, the storage stability can be improved, and the combustion efficiency can be improved by utilizing a moisture method and reinforcing and solidifying the biomass granules. The method is environment-friendly, low in cost and wide in adaptability, and has a good industrial application prospect.

Description

Technical Field

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

[0002] Biomass energy, as a renewable and environmentally friendly clean energy, has received extensive attention and research around the world in recent years. It not only helps to alleviate the depletion of fossil fuels, but also plays an important role in reducing greenhouse gas emissions. Among the many forms of biomass energy, bamboo and wood biomass pellets have become a major research hotspot in the field of biomass energy due to their significant advantages such as wide sources, low preparation 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 environments with high humidity, biomass pellets are very easy to absorb moisture, which not only leads to a decrease in the quality of the pellets themselves, such as reduced hardness and increased fragility, but also seriously affects their storage stability. In addition, biomass pellets that have absorbed moisture tend to produce more smoke and harmful gases during the combustion process, thereby reducing combustion efficiency and increasing the risk of environmental pollution.

[0004] In response to this problem, some studies have emerged in the prior art that attempt to enhance the moisture resistance of biomass particles through physical or chemical methods. Although these methods have achieved certain results to a certain extent, most of them still fail to fundamentally solve the problems of moisture absorption and storage stability of biomass particles in a humid environment. More importantly, many existing curing enhancement methods often rely on the use of chemical additives, which not only increases production costs, but may also have potential negative impacts on the environment and human health, thereby limiting the widespread application of these methods.

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

[0006] In view of the above existing technical problems, the present invention aims to provide a biomass pellet fuel with low water content and a preparation method thereof. The biomass pellet fuel prepared by the method utilizes a moisture method and enhanced solidification of biomass particles, which can effectively improve the moisture resistance of the particles, reduce the moisture content, increase storage stability and improve combustion efficiency. The method is not only environmentally friendly and low-cost, but also has wide adaptability and good industrial application prospects.

[0007] The present invention discloses a method for preparing a biomass pellet fuel with a 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 crusher 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 wet environment box, and the humidity, temperature and time of the wet environment box are set to perform wet pretreatment on the raw material particles;

[0009] S2 curing treatment: the raw material particles that have been pre-treated with moisture in step S1 are taken out from 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, and after the treatment is completed, a biomass particle fuel with a low water content is obtained.

[0011] Preferably, in the S1 raw material pretreatment step, 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 curing 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 biomass pellet fuel with low water content is prepared by any one of the above-mentioned methods for preparing a biomass pellet fuel with low water content.

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

[0021] The present invention provides a method for preparing a biomass pellet fuel with low water content. Through the wet gas pretreatment and enhanced curing steps, the cross-linked structure formed on the surface of the bamboo wood pellets can effectively reduce the absorption of water, 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, which is more environmentally friendly than the traditional chemical curing method and avoids 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, which meets environmental protection requirements; the wet gas treatment process is simple, easy to industrialize and apply, and the cost is relatively low, which is suitable for large-scale production and application.

[0022] The biomass particle fuel prepared by the preparation method provided by the present invention has lower water content, higher moisture resistance, and better storage stability and combustion efficiency. DETAILED DESCRIPTION

[0023] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope 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 the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

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

[0026] 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 raw material particles after screening is 5mm; the raw material particles are evenly laid in a moisture environment box, the humidity of the moisture environment box is set to 70%, the temperature of the moisture environment box is set to 50°C, and the raw material particles are moisture pretreated for 12 hours.

[0027] S2 curing treatment: take out the raw material particles that have been moisture pretreated in step S1 from the moisture environment box, shake to remove surface moisture, then put them into a sodium silicate solution and heat to 45°C to soak for 1 hour. After the soaking is completed, filter and collect the solid particles and put them into an enhanced curing box. Set the humidity of the enhanced curing box to 50% and the temperature of the enhanced curing box to 50°C. Perform enhanced curing treatment on the particles for 8 hours. After the curing is completed, solidified 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 for 6 hours. After the treatment, a biomass particle fuel with a low water content is obtained.

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

[0030] 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 raw material particles after screening is 4.5mm; the raw material particles are evenly laid in a moisture environment box, the humidity of the moisture environment box is set to 72%, the temperature of the moisture environment box is set to 60°C, and the raw material particles are moisture pretreated for 12.5h.

[0031] S2 curing treatment: the raw material particles that have been moisture pretreated 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 for 6.5 hours. After the treatment, a biomass particle fuel with a low water content is obtained.

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

[0034] 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 raw material particles after screening is 4mm; the raw material particles are evenly laid in a moisture environment box, the humidity of the moisture environment box is set to 75%, the temperature of the moisture environment box is set to 65°C, and the raw material particles are moisture pretreated for 13h.

[0035] S2 curing treatment: the raw material particles that have been moisture pretreated 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 50°C for soaking 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 for 7 hours. After the treatment, a biomass particle fuel with a low water content is obtained.

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

[0038] 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 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 been moisture pretreated 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 for 7.5 hours. After the treatment, a biomass particle fuel with a low water content is obtained.

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

[0042] 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 raw material particles after screening is 3mm; the raw material particles are evenly laid in a moisture environment box, the humidity of the moisture environment box is set to 80%, the temperature of the moisture environment box is set to 80℃, and the raw material particles are moisture pretreated for 15h.

[0043] S2 curing treatment: the raw material particles that have been moisture pretreated 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 55°C for soaking 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 for 8 hours. After the treatment, a biomass particle fuel with a low water 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] It can be seen from the experimental data described in the above table 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 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 particles are soaked in silicon solution and then cured by the moisture method. By controlling the humidity and temperature, the silicon-based material and bamboo wood fiber are combined to form a stable three-dimensional network structure. The synergistic effect of the silicon-based reinforcing agent and the moisture method enables the bamboo wood particles to form a moisture-proof silicon-based protective film during the curing process, which can significantly improve the moisture resistance of the particles and reduce the moisture absorption of biomass particles in a humid environment. This improves the storage stability of biomass particles, prolongs the storage period, reduces the risk of fuel getting damp during transportation and storage, and enhances combustion efficiency.

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

[0052]

[0053]

[0054] From the experimental data in the above table, it can be seen that as the mass fraction of sodium silicate solution increases, the moisture content of the particles gradually decreases and tends to be stable; when the mass fraction of sodium silicate increases, the mass fraction of the particles does not change much; as the mass fraction of sodium silicate increases, the calorific value of the particles increases slightly, and the compressive strength of the particles increases. The optimal mass fraction of sodium silicate solution is 35%.

[0055] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the 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 crusher 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 wet environment box, and the humidity, temperature and time of the wet environment box are set to perform wet pretreatment on the raw material particles; S2 curing treatment: the raw material particles that have been pre-treated with moisture in step S1 are taken out from 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 to 500 μm, and then placed in a drying oven for low-temperature drying treatment, and after the treatment is completed, a biomass particle fuel with a low water content is obtained.

2. 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 humidity of the wet environment box is 70-80%.

3. 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 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 mass fraction of the sodium silicate solution is 23-38%.

6. 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 to 55° C. and the soaking time is 1 to 2 hours.

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 humidity of the enhanced curing box is 50-60%.

8. 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.; the time of the enhanced curing treatment is 8-12 hours.

9. 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.

10. The biomass pellet fuel with low moisture content prepared by the method for preparing a biomass pellet fuel with low moisture content as claimed in any one of claims 1 to 9.

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