Crosslinking modified biomass solid fuel and preparation method thereof

Abstract

The invention relates to the field of biomass fuel preparation, in particular to a crosslinking modified biomass solid fuel and a preparation method thereof. According to the preparation method of the cross-linked modified biomass solid fuel, through combination of physical and chemical pretreatment and cross-linked modification, the calorific value and combustion performance of the biomass fuel are remarkably improved, emission of harmful gas is reduced, and the good environment-friendly effect is achieved. The method is simple and easy to implement, is suitable for large-scale production, can be widely applied to the fields of energy, environmental protection, agriculture and the like, and has important market application prospects.

Description

Technical Field

[0001] The present invention relates to the field of biomass fuel preparation, and particularly to a crosslinked modified biomass solid fuel and a preparation method thereof. Background Art

[0002] With the continuous growth of the global economy and the ever-expanding population, the demand for energy shows an unprecedented upward trend. At the same time, the awakening of environmental protection awareness has made the global call for reducing greenhouse gas emissions and protecting the natural ecology increasingly louder. Against this background, due to the non-renewability and environmental pollution problems of traditional fossil energy, its over-reliance has gradually caused deep concerns in all sectors of society, which in turn has prompted people to turn their attention to the development and utilization of renewable energy.

[0003] Biomass fuel, as a clean and renewable energy form bestowed by nature, has increasingly attracted the attention of governments and enterprises of various countries with its rich sources and low environmental impact. Among them, waste paper resource biomass has become a bright star in the field of biomass fuel due to its abundance and easy availability. However, despite the many advantages of waste paper resource biomass, it has a relatively low calorific value itself, which to a certain extent limits its wide application as an efficient fuel.

[0004] At present, common biomass fuel treatment technologies in the market, such as direct compression and pyrolysis, although to a certain extent realize the resource utilization of waste paper resource biomass, these methods are often accompanied by problems such as poor combustion performance, low calorific value, and possible secondary pollution, thus affecting their market promotion and long-term application. Therefore, how to overcome these technical bottlenecks, improve the performance of waste paper resource biomass fuel through scientific methods, and enhance its calorific value, combustion stability, and environmental protection characteristics has become an urgent technical problem to be solved in the current biomass energy field and is also the key to promoting the sustainable and healthy development of the biomass fuel industry. Summary of the Invention

[0005] Aiming at the above existing technical problems, the present invention aims to provide a crosslinked modified biomass solid fuel and a preparation method thereof. The biomass solid fuel prepared by this method combines physical and chemical pretreatment with crosslinked modification, significantly improving the calorific value and combustion performance of the biomass fuel, and reducing the emission of harmful gases, with good environmental protection effects. This method is simple and easy to operate, suitable for large-scale production, and can be widely applied in fields such as energy, environmental protection, and agriculture, with important market application prospects.

[0006] The present invention discloses a preparation method of a crosslinked modified biomass solid fuel, including the following preparation steps:

[0007] S1 Biomass material pretreatment: The biomass material is crushed into fragments with a size of 2 - 4 cm, and then the fragments are soaked in hot water with a water temperature of 80 - 100 °C. After the soaking is completed, they are washed, dehydrated, and dried. The dried fragments are added to an alkali solution for decomposition reaction. After the reaction is completed, they are filtered and washed. After being washed to neutrality, they are dehydrated and dried to obtain modified biomass fragments;

[0008] S2 Crosslinking reaction: The crosslinking agent is dissolved in a mixed solution of deionized water and ethanol to obtain a crosslinking solution. The modified biomass fragments obtained in step S1 are added to the above crosslinking solution, and the temperature is raised to carry out the crosslinking reaction. After the reaction is completed, the temperature is immediately lowered, filtered, and washed. The filter cake is collected and dried to obtain crosslinked modified biomass;

[0009] S3 Compression molding and heat treatment: The crosslinked modified biomass obtained in step S2 is placed in a briquetting machine. The temperature of the briquetting machine is set to 100 - 150 °C, and the pressure is 50 - 80 MPa for briquetting. After the briquetting is completed, the formed briquette is heat-treated. After the heat treatment is completed, crosslinked modified biomass solid fuel is obtained.

[0010] Preferably, in the S1 biomass material pretreatment step, the soaking time is 1 - 3 h.

[0011] Preferably, in the S1 biomass material pretreatment step, the alkali solution is a sodium hydroxide solution; the mass fraction of the alkali solution is 2 - 10%.

[0012] Preferably, in the S1 biomass material pretreatment step, the reaction temperature of the decomposition reaction is 60 - 90 °C.

[0013] Preferably, in the S1 biomass material pretreatment step, the reaction time of the decomposition reaction is 1 - 5 h.

[0014] Preferably, in the S1 biomass material pretreatment step, the reaction time of the decomposition reaction is 2 - 3 h.

[0015] Preferably, in the S2 crosslinking reaction step, the crosslinking agent is melamine, epoxy resin, or isocyanate; the mass fraction of the crosslinking agent is 2 - 8%.

[0016] Preferably, in the S2 crosslinking reaction step, the reaction temperature of the crosslinking reaction is 50 - 80 °C, and the reaction time is 2 - 4 h.

[0017] Preferably, in the S3 compression molding and heat treatment step, the temperature of the heat treatment is 150 - 200 °C, and the time of the heat treatment is 1 - 2 h.

[0018] A crosslinked modified biomass solid fuel, which is prepared by any of the above - mentioned preparation methods of crosslinked modified biomass solid fuel.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The present invention provides a crosslinked modified biomass solid fuel, which is a biomass processed into a dense formed fuel. According to the chemical characteristics of the biomass, an appropriate crosslinking agent is selected, such as melamine, epoxy resin, isocyanate. The crosslinking agent reacts with the hydroxyl group (–OH) or aldehyde group (–CHO) in the biomass to form a crosslinked network structure. The structure of the biomass after crosslinking modification is more dense and stable, has a higher calorific value, burns more fully, and can improve the combustion efficiency; the volatile content of the solid fuel prepared from the crosslinked modified biomass is moderate, burns more completely, and can reduce the emission of harmful gases (such as carbon monoxide, nitrogen oxides, etc.), meeting the environmental protection requirements; the mechanical strength of the solid fuel prepared from the biomass after crosslinking treatment is improved, it is not easy to break, and the loss during storage and transportation is small; the present invention improves the combustion performance of the biomass through physical and chemical modification, avoids excessive dependence on fossil fuels such as petroleum and coal, and has strong environmental protection benefits. It can be widely applied in the fields of energy, environmental protection, agriculture, etc., and has important market application prospects.

[0021] The present invention also provides a preparation method of the crosslinked modified biomass solid fuel. This method is simple to operate, the reaction conditions are easy to control, and it is suitable for large-scale industrial production. Specific embodiments

[0022] The following embodiments are provided to better understand the present invention further. They are not limited to the best embodiment, and do not constitute a limitation to the content and protection scope of the present invention. Any product that is the same as 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 art features falls within the protection scope of the present invention.

[0023] For those not specifying specific experimental steps or conditions in the embodiments, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments not specifying the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.

[0024] Example 1: A preparation method of a crosslinked modified biomass solid fuel, characterized by comprising the following steps:

[0025] S1 Biomass material pretreatment: The biomass material is crushed into fragments of 4 cm, and then the fragments are soaked in hot water at a water temperature of 100 °C for 3 h. After the soaking is completed, washing, dehydration, and drying are carried out. The dried fragments are added to a sodium hydroxide solution with a mass fraction of 10% for decomposition reaction. The temperature of the decomposition reaction is 90 °C, and the reaction time is 5 h. After the reaction is completed, filtration is carried out and washed with deionized water until the eluate is neutral, and then dehydration and drying are carried out to obtain modified biomass fragments.

[0026] S2 Crosslinking reaction: The crosslinking agent is dissolved in a mixed solution of deionized water and ethanol to obtain a crosslinking solution, where the crosslinking agent is melamine with a mass fraction of 8%. The volume ratio of deionized water to ethanol is 1:0.5. The modified biomass fragments obtained in step S1 are added to the above crosslinking solution, and the mass ratio of the modified biomass fragments to the crosslinking solution is 1:5. The temperature is raised to 80 °C for crosslinking reaction, and the crosslinking reaction time is 4 h. After the reaction is completed, the temperature is immediately lowered, filtered, and washed, and the filter cake is collected and dried to obtain crosslinked modified biomass.

[0027] S3 Compression molding heat treatment: The crosslinked modified biomass obtained in step S2 is placed in a briquetting machine, the temperature of the briquetting machine is set to 150 °C, and the pressure is 80 MPa for briquetting. After the briquetting is completed, heat treatment is carried out on the formed briquette. The temperature of the heat treatment is 200 °C, and the heat treatment time is 2 h. After the heat treatment is completed, the temperature is lowered to obtain crosslinked modified biomass solid fuel.

[0028] Example 2: A preparation method of crosslinked modified biomass solid fuel, characterized by comprising the following steps:

[0029] S1 Biomass material pretreatment: The biomass material is crushed into fragments of 3 cm, and then the fragments are soaked in hot water at a water temperature of 90 °C for 2 h. After the soaking is completed, washing, dehydration, and drying are carried out. The dried fragments are added to a sodium hydroxide solution with a mass fraction of 7% for decomposition reaction. The temperature of the decomposition reaction is 80 °C, and the reaction time is 4 h. After the reaction is completed, filtration is carried out and washed with deionized water until the eluate is neutral, and then dehydration and drying are carried out to obtain modified biomass fragments.

[0030] S2 Crosslinking reaction: The crosslinking agent is dissolved in a mixed solution of deionized water and ethanol to obtain a crosslinking solution, where the crosslinking agent is melamine with a mass fraction of 6%. The volume ratio of deionized water to ethanol is 1:0.5. The modified biomass fragments obtained in step S1 are added to the above crosslinking solution, and the mass ratio of the modified biomass fragments to the crosslinking solution is 1:5. The temperature is raised to 70 °C for crosslinking reaction, and the crosslinking reaction time is 3.5 h. After the reaction is completed, the temperature is immediately lowered, filtered, and washed, and the filter cake is collected and dried to obtain crosslinked modified biomass.

[0031] S3 Compression Molding Heat Treatment: Place the crosslinked and modified biomass obtained in step S2 into a feeding machine, set the temperature of the feeding machine to 140 °C and the pressure to 70 MPa for feeding. After the feeding is completed, heat-treat the formed block. The heat treatment temperature is 180 °C and the heat treatment time is 1.5 h. After the heat treatment is completed, cool down to obtain crosslinked and modified biomass solid fuel.

[0032] Example 3: A preparation method of crosslinked and modified biomass solid fuel, characterized by comprising the following steps:

[0033] S1 Biomass Material Pretreatment: Crush the biomass material into 3 cm fragments, then soak the fragments in hot water with a water temperature of 80 °C for 1 h. After the soaking is completed, carry out cleaning, dehydration and drying. Add the dried fragments to a sodium hydroxide solution with a mass fraction of 5% for decomposition reaction. The decomposition reaction temperature is 70 °C and the reaction time is 3 h. After the reaction is completed, filter and wash with deionized water until the eluate is neutral, and then dehydrate and dry to obtain modified biomass fragments.

[0034] S2 Crosslinking Reaction: Dissolve the crosslinking agent in a mixed solution of deionized water and ethanol to obtain a crosslinking solution, where the crosslinking agent is melamine with a mass fraction of 4%, and the volume ratio of deionized water to ethanol is 1:0.5. Add the modified biomass fragments obtained in step S1 to the above crosslinking solution, and the mass ratio of the modified biomass fragments to the crosslinking solution is 1:5. Raise the temperature to 60 °C for crosslinking reaction, and the crosslinking reaction time is 3 h. After the reaction is completed, immediately cool down, filter and wash, and collect the filter cake and dry to obtain crosslinked and modified biomass;

[0035] S3 Compression Molding Heat Treatment: Place the crosslinked and modified biomass obtained in step S2 into a feeding machine, set the temperature of the feeding machine to 130 °C and the pressure to 60 MPa for feeding. After the feeding is completed, heat-treat the formed block. The heat treatment temperature is 160 °C and the heat treatment time is 1 h. After the heat treatment is completed, cool down to obtain crosslinked and modified biomass solid fuel.

[0036] Example 4: A preparation method of crosslinked and modified biomass solid fuel, characterized by comprising the following steps:

[0037] S1 Biomass Material Pretreatment: Crush the biomass material into 3 cm fragments, then soak the fragments in hot water with a water temperature of 80 °C for 1 h. After the soaking is completed, carry out cleaning, dehydration and drying. Add the dried fragments to a sodium hydroxide solution with a mass fraction of 3% for decomposition reaction. The decomposition reaction temperature is 60 °C and the reaction time is 2 h. After the reaction is completed, filter and wash with deionized water until the eluate is neutral, and then dehydrate and dry to obtain modified biomass fragments.

[0038] S2 Crosslinking reaction: Dissolve the crosslinking agent in a mixed solution of deionized water and ethanol to obtain a crosslinking solution, where the crosslinking agent is melamine with a mass fraction of 2%, and the volume ratio of deionized water to ethanol is 1:0.5; add the modified biomass fragments obtained in step S1 to the above crosslinking solution, and the mass ratio of the modified biomass fragments to the crosslinking solution is 1:5; raise the temperature to 65 °C for crosslinking reaction, and the time of the crosslinking reaction is 2 h. Immediately cool down, filter and wash after the reaction ends, and collect the filter cake and dry it to obtain crosslinked modified biomass;

[0039] S3 Compression molding heat treatment: Place the crosslinked modified biomass obtained in step S2 into a briquetting machine, set the temperature of the briquetting machine to 100 °C and the pressure to 50 MPa for briquetting. After the briquetting ends, perform heat treatment on the formed briquette. The temperature of the heat treatment is 150 °C, and the time of the heat treatment is 1 h. Cool down after the heat treatment ends to obtain crosslinked modified biomass solid fuel.

[0040] Example 5: A preparation method of crosslinked modified biomass solid fuel, characterized by comprising the following steps:

[0041] S1 Biomass material pretreatment: Crush the biomass material into fragments of 3 cm, then soak the fragments in hot water with a water temperature of 80 °C for 1 h. After the soaking ends, wash, dehydrate and dry. Add the dried fragments to a sodium hydroxide solution with a mass fraction of 2% for decomposition reaction. The temperature of the decomposition reaction is 75 °C, and the reaction time is 1 h. After the reaction ends, filter and wash with deionized water until the eluate is neutral, then dehydrate and dry to obtain modified biomass fragments.

[0042] S2 Crosslinking reaction: Dissolve the crosslinking agent in a mixed solution of deionized water and ethanol to obtain a crosslinking solution, where the crosslinking agent is melamine with a mass fraction of 2%, and the volume ratio of deionized water to ethanol is 1:0.5; add the modified biomass fragments obtained in step S1 to the above crosslinking solution, and the mass ratio of the modified biomass fragments to the crosslinking solution is 1:5; raise the temperature to 50 °C for crosslinking reaction, and the time of the crosslinking reaction is 2 h. Immediately cool down, filter and wash after the reaction ends, and collect the filter cake and dry it to obtain crosslinked modified biomass;

[0043] S3 Compression molding heat treatment: Place the crosslinked modified biomass obtained in step S2 into a briquetting machine, set the temperature of the briquetting machine to 100 °C and the pressure to 50 MPa for briquetting. After the briquetting ends, perform heat treatment on the formed briquette. The temperature of the heat treatment is 150 °C, and the time of the heat treatment is 1 h. Cool down after the heat treatment ends to obtain crosslinked modified biomass solid fuel.

[0044] Example 6: Replace the crosslinking agent melamine in Example 4 with epoxy resin, and the remaining preparation method steps are the same as those in Example 4.

[0045] Example 7: Replace the crosslinking agent melamine in Example 4 with isocyanate, and the remaining preparation method steps are the same as those in Example 4.

[0046] Example 8: Do not add a crosslinking agent in Example 4, and the remaining preparation method steps are the same as those in Example 4.

[0047] Example 9: A preparation method of crosslinked modified biomass solid fuel, characterized by comprising the following steps:

[0048] S1 Biomass material pretreatment: Crush the biomass material into fragments of 3 cm to obtain modified biomass fragments.

[0049] S2 Crosslinking reaction: Dissolve the crosslinking agent in a mixed solution of deionized water and ethanol to obtain a crosslinking solution, wherein the crosslinking agent is melamine with a mass fraction of 2%, and the volume ratio of deionized water to ethanol is 1:0.5; Add the biomass fragments obtained in step S1 to the above crosslinking solution, and the mass ratio of the modified biomass fragments to the crosslinking solution is 1:5; Raise the temperature to 65 °C for crosslinking reaction, and the crosslinking reaction time is 2 h. Immediately cool, filter and wash after the reaction ends, and collect the filter cake and dry it to obtain crosslinked modified biomass;

[0050] S3 Compression molding heat treatment: Place the crosslinked modified biomass obtained in step S2 into a briquetting machine, set the temperature of the briquetting machine to 100 °C and the pressure to 50 MPa for briquetting. After the briquetting ends, perform heat treatment on the formed briquette. The heat treatment temperature is 150 °C and the heat treatment time is 1 h. After the heat treatment ends, cool down to obtain crosslinked modified biomass solid fuel.

[0051] Perform property tests on the crosslinked modified biomass solid fuels prepared in the above Examples 1-9, and the test methods are as follows:

[0052] (1) Moisture content: Weigh a certain mass of the biomass sample and place it in an oven at 105 °C to dry to a constant weight. Measure the mass difference of the sample before and after drying, and calculate the moisture content. Moisture content = [(initial mass of the sample - mass after drying) / initial mass of the sample] × 100%.

[0053] (2) Density: Use a standard cylindrical densitometer to measure the mass and volume of each sample. Calculate the density of the sample. Density = mass / volume.

[0054] (3) Calorific value: Use a bomb calorimeter to test the calorific value of each group of samples. By burning the sample and measuring the released heat, obtain its calorific value (MJ / kg).

[0055] (4) Ash content: Place the biomass sample in a high-temperature furnace and heat it to constant weight at 550 °C to obtain the mass of the residue. Calculate the ash content. Ash content = (ash mass / sample mass) × 100%.

[0056] (5) Combustion performance: Under controlled conditions, use a standard combustion device to test the ignition time, combustion rate, and flame stability of each group of samples. Record the changes during combustion, measure the fuel consumption, and calculate the combustion rate per unit time.

[0057] (6) Compressive strength: Use a compression testing machine to measure the compressive strength of the fuel under different pressures. Record the maximum pressure that each sample can withstand before rupture.

[0058] (1)-(6) The experimental data are shown in the following table:

[0059]

[0060] From the data in the above table, it can be seen that the properties of the crosslinked modified biomass solid fuels prepared in Examples 1-5 are significantly better than those in Examples 8-9. In particular, the properties of the crosslinked modified biomass solid fuel prepared in Example 4 are the best.

[0061] Example 4 (6.2%) performs the best. A lower moisture content helps to improve the combustion efficiency of the fuel; with the use of the crosslinking agent, the density of the samples gradually increases. Example 4 (1.12 g / cm3) has the highest density, indicating that it has a higher energy density and mechanical strength; the crosslinking treatment significantly improves the calorific value of the fuel. In particular, Example 4 (24.5 MJ / kg) has a significant improvement compared to Examples 8-9, indicating that the crosslinking modification improves the energy release ability of the fuel; Example 4 (3.8%) has the lowest ash content, which means that the residue left after the combustion of this sample is the least and the combustion efficiency is relatively high; the ignition time of Example 4 is the shortest (22 seconds), indicating that the crosslinking modification helps the fuel to be quickly ignited; the combustion rate of Example 4 is the highest (5.0 g / min), indicating that it consumes relatively fast during combustion; the combustion duration of Example 4 is the longest (22 minutes), indicating that the crosslinking modification helps to extend the combustion time; the compressive strength of Example 4 is the highest (15 MPa), indicating that the crosslinking modification improves the mechanical strength of the fuel, making it more suitable for long-term storage and transportation.

[0062] In summary: Crosslinking modification can significantly improve the physical and chemical properties of biomass solid fuels, especially in terms of increasing density, calorific value, compressive strength, and combustion performance. Example 4 (crosslinked modified biomass solid fuel) performs the best in various performance tests, has significant advantages, and is suitable for use as an efficient fuel.

[0063] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or alterations derived therefrom still fall within the protection scope of the present invention.

Claims

1. A preparation method of cross-linked modified biomass solid fuel, characterized in that, It includes the following steps: S1 Biomass material pretreatment: Crush the biomass material into fragments with a size of 2 - 4 cm, then soak the fragments in hot water with a water temperature of 80 - 100 °C. After the soaking ends, conduct cleaning, dehydration, and drying. Add the dried fragments to an alkali solution for decomposition reaction. After the reaction ends, filter and wash. After washing until neutral, conduct dehydration and drying to obtain modified biomass fragments; S2 Crosslinking reaction: Dissolve the crosslinking agent in a mixed solution of deionized water and ethanol to obtain a crosslinking solution. Add the modified biomass fragments obtained in step S1 to the above crosslinking solution, raise the temperature to conduct the crosslinking reaction. After the reaction ends, immediately cool down, filter, and wash. Collect the filter cake and dry to obtain crosslinked and modified biomass; S3 Compression molding and heat treatment: Place the crosslinked and modified biomass obtained in step S2 into a briquetting machine, set the temperature of the briquetting machine to 100 - 150 °C and the pressure to 50 - 80 MPa for briquetting. After the briquetting ends, conduct heat treatment on the formed briquette. After the heat treatment ends, obtain crosslinked and modified biomass solid fuel.

2. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, characterized in that In the S1 biomass material pretreatment step, the soaking time is 1 - 3 h.

3. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, wherein, In the S1 biomass material pretreatment step, the alkali solution is a sodium hydroxide solution; the mass fraction of the alkali solution is 2 - 10%.

4. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, characterized in that In the S1 biomass material pretreatment step, the reaction temperature of the decomposition reaction is 60 - 90 °C.

5. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, characterized in that, In the S1 biomass material pretreatment step, the reaction time of the decomposition reaction is 1 - 5 h.

6. The preparation method of a cross-linked modified biomass solid fuel according to claim 1, characterized in that, In the S1 biomass material pretreatment step, the reaction time of the decomposition reaction is 2 - 3 h.

7. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, characterized in that, In the S2 crosslinking reaction step, the crosslinking agent is melamine, epoxy resin, or isocyanate; the mass fraction of the crosslinking agent is 2 - 8%.

8. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, characterized in that, In the S2 crosslinking reaction step, the reaction temperature of the crosslinking reaction is 50 - 80 °C, and the reaction time is 2 - 4 h.

9. The preparation method of a crosslinked modified biomass solid fuel according to claim 1, characterized in that, In the S3 compression molding and heat treatment step, the temperature of the heat treatment is 150 - 200 °C, and the heat treatment time is 1 - 2 h.

10. The crosslinked and modified biomass solid fuel prepared by the preparation method of a crosslinked and modified biomass solid fuel according to any one of claims 1 - 9.

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