Chicken manure biochar formed fuel and preparation method therefor

Abstract

A chicken manure biochar formed fuel and a preparation method therefor. The raw materials used by the formed fuel comprise chicken manure and wood chips, wherein the adding amount of wood chips is less than or equal to 40 wt% calculated on the basis of dry weight. The preparation method for the formed fuel is as follows: raw material pretreatment: naturally airing fresh chicken manure until the water content is less than 20%, then drying same until the water content is 3-12%, sieving wood chips through a 7-mesh sieve, and then drying same until the water content is 3-12%; and crushing the chicken manure having a water content of 3-12%, and then sieving same through a 10- to 40-mesh sieve, so as to obtain undersize chicken manure; stirring and mixing: mechanically stirring and uniformly mixing the undersize chicken manure and the wood chips having a water content of 3-12% for 10-40 min, so as to obtain a mixture; fuel rod hot extrusion forming: subjecting the mixture to hot extrusion forming at a temperature of 190-320ºC, and drying same, so as to obtain a fuel rod; and pyrolysis: subjecting the obtained fuel rod to heat preservation for 20-120 minutes at a heating rate of 3-10 min / ºC and a pyrolysis temperature of 400-800ºC under the condition of the protective gas being argon, so as to obtain a chicken manure biochar formed fuel. The fuel has high mechanical strength, a high density, is easy to store and transport, has a high calorific value and a low ash content, is odorless during a combustion process and has low flue gas.

Description

Chicken manure biochar briquette fuel and preparation method thereof Technical Field

[0001] The invention relates to a chicken manure biochar shaped fuel and a preparation method thereof, and belongs to the field of biomass fuel technology and environmental protection technology. Background Art

[0002] Energy and environmental issues have become the focus of global attention. With the continuous consumption of fossil energy and the increasingly serious environmental problems, the development and utilization of clean and renewable energy has become a research hotspot. The amount of agricultural and forestry waste biomass generated in my country each year is large and comes from a wide range of sources. If it is prepared into biomass solid molded fuel, it has the advantages of being clean, environmentally friendly, renewable, easy to transport, and easy to use. It can replace traditional fossil energy such as coal and oil, and reduce dependence on non-renewable energy. As my country's livestock and poultry farming industry develops towards scale and intensiveness, it brings huge economic benefits while also generating a large amount of livestock and poultry manure. The traditional way of utilizing livestock and poultry manure is to ferment the manure and sell it as fertilizer. This utilization method is relatively simple, and coupled with the influence of regionality and seasonality, it has resulted in a large amount of livestock and poultry manure being stored on farms, which not only wastes resources but also pollutes the environment.

[0003] At present, the existing technology is to prepare livestock manure (such as pig manure, cow manure, chicken manure, etc.) into fine biochar particles or powder for soil improvement and remediation, or to adsorb and remove pollutants in water, soil, atmosphere and other environments. For example, the invention patent (CN113860931B) discloses an aerobic composting method for removing antibiotics from manure using chicken manure biochar and the application of chicken manure biochar in removing antibiotics. Carbonized chicken manure biochar powder is used as a substrate and mixed with animal manure and crop straw to reduce the residual amount of antibiotics in livestock manure during aerobic composting fermentation. The added amount of chicken manure biochar accounts for 10-20wt% of the aerobic composting fermentation raw materials, and the composting fermentation time is not less than 7 days.

[0004] As we all know, livestock manure contains a certain amount of combustible organic matter. Therefore, another important application of livestock manure is to make fuel. One way is to use livestock manure directly as fuel, and the other is to make it into biomass pellet fuel.

[0005] The invention patent (CN112662445A) discloses a method for burning chicken manure and rice husk mixture in a biomass boiler. To meet the combustion requirements of the boiler, the chicken manure and rice husk mixture is mixed with coarse limestone powder outside the furnace before being mixed with other biomass fuels. The amount of chicken manure and rice husk mixture is controlled to be less than 45% of the total weight of the combustion materials. The calorific value of the resulting mixed fuel is Q net，arThe content of chicken manure and rice husk in the biomass boiler mixed with chicken manure and rice husk is less than 50%, and the calorific value of the chicken manure and rice husk mixture is low.

[0006] Patent CN106244278B discloses a method for producing biomass fuel using fresh chicken manure as the primary raw material. This method uses fresh chicken manure as the primary raw material, along with discarded mushroom sticks, high-temperature calcined shell powder, and tea stems as supplementary ingredients. Two composite microorganisms are added, and the mixture is composted and fermented sequentially. Finally, the biomass pellets are extruded and produced. This fuel has a calorific value of 22.82 to 24.96 MJ / kg. The mushroom sticks and tea stems increase the viscosity of the material, facilitating pelletization. However, the composting and fermentation process takes a relatively long time, at 3-5 days. Furthermore, this method contains numerous additives, making it susceptible to regional restrictions.

[0007] Compared to directly burning livestock manure, biomass pellet fuel offers advantages such as high energy density and ease of transportation. However, biomass pellet fuel easily absorbs moisture, which reduces its strength and makes it prone to breakage, reducing fuel utilization. It also has a persistent foul odor, limiting its application. Furthermore, to increase the pellet forming efficiency, adhesives are often added. To reduce slagging and ash accumulation during combustion, as well as flue gas corrosion, additives are often added, increasing production costs.

[0008] Due to the complexity of livestock manure, the calorific value of biomass solid briquette fuel prepared from it is generally low and the ash content is high. Moreover, because livestock manure contains a certain amount of heavy metals, the ash from the combustion of the fuel poses a risk of soil contamination. Chicken farming is particularly unique in that chicken feed contains stone powder (the main component is CaCO3), and the stone powder content in the feed during peak egg production can be as high as 8.5% or more. Therefore, the ash content of biochar fuel prepared from chicken manure will be higher, resulting in low combustion efficiency. Finding a new, environmentally friendly chicken manure biochar fuel with a simple preparation process, low cost, high calorific value, and low ash content is of great significance for solving the environmental pollution problems caused by livestock manure and replacing fossil energy to reduce CO2 emissions. Summary of the Invention

[0009] To address the above-mentioned problems and shortcomings of the existing technology, the present invention provides a chicken manure biochar briquette fuel and its preparation method. This method uses fresh chicken manure from laying hen farms as raw material, and adds sawdust (fir wood chips) from wood processing waste as an auxiliary raw material to produce the chicken manure biochar briquette fuel via a pyrolysis process. This fuel has the advantages of high calorific value, low ash content, low cost, easy storage and transportation, and environmental friendliness. While addressing the environmental pollution problem caused by chicken manure, it also provides a path for the energy utilization of poultry and livestock manure and other abundant agricultural and forestry waste in mountainous areas.

[0010] To achieve the purpose of the present invention, the technical solutions adopted are as follows:

[0011] A chicken manure biochar briquette fuel, wherein raw materials used in the briquette fuel include chicken manure and sawdust, wherein the added amount of sawdust calculated by dry weight is ≤40wt%.

[0012] The wood chips are fir sawdust.

[0013] A method for preparing chicken manure biochar briquette fuel specifically comprises the following steps:

[0014] S1, raw material pretreatment:

[0015] S1.1. Air-dry fresh chicken manure until the moisture content is less than 20%, then dry it to a moisture content of 3%-12%; sieve sawdust through a 7-mesh sieve and dry it to a moisture content of 3%-12%;

[0016] S1.2, crushing the chicken manure with a moisture content of 3%-12% after the treatment in step S1.1 and passing it through a 10-40 mesh sieve to obtain undersize chicken manure;

[0017] S2, stirring and mixing: mechanically stirring and uniformly mixing the undersized chicken manure obtained in step S1.2 and the sawdust processed in step S1.1 for 10-40 minutes to obtain a mixture;

[0018] S3, hot extrusion molding of firewood sticks: hot extrusion molding the mixture obtained in step S2 at a temperature of 190-320°C, and then drying it in a blast drying oven to obtain firewood sticks;

[0019] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as a protective gas, with a heating rate of 3-10 min / °C, a pyrolysis temperature of 400-800°C, and a heat preservation time of 20-120 min to obtain chicken manure biochar briquette fuel.

[0020] The crushing speed in step S1.2 is 8000-32000 r / min.

[0021] In step S2, the moisture content of the mixture is controlled at 3-12%.

[0022] In step S3, the fuel rod is a square column with a through hole of about 15 mm in diameter formed in the middle thereof and an external size of 50×50×450 mm.

[0023] The beneficial effects of the present invention are:

[0024] 1. This invention uses fresh chicken manure and sawdust, both agricultural and forestry waste, as raw materials. A clean and renewable chicken manure biochar briquette fuel is produced through a briquetting-first, then carbonizing process. This briquette fuel exhibits advantages such as high mechanical strength, high density, easy storage and transportation, high calorific value, low ash content, and odorless combustion with low smoke emissions. The calorific value (calorific value) of this fuel can reach over 20 MJ / kg, significantly exceeding the A1 grade (≥15.5 MJ / kg) specified in the domestic agricultural industry standard NY / T 2909-2016, "Quality Classification of Biomass Solid Briquettes." It can be used for urban centralized heating and power generation, as well as for cooking and heating in rural areas.

[0025] 2. By coordinating and controlling the process parameters of chicken manure during the drying, crushing, and screening steps, the chicken manure raw material has a certain moisture content, which is convenient for subsequent molding. The chicken manure is crushed while minimizing the damage to the stone powder in the crushing process. The chicken manure is then screened through a sieve with an appropriate aperture. This achieves a high utilization rate of the chicken manure raw material and effectively removes the stone powder, which is beneficial to reducing the ash content and increasing the calorific value of the chicken manure biochar fuel.

[0026] 3. The mixture is formed by hot extrusion. By adjusting the shape and extrusion space of the spiral extruder, the lignin in the material is softened under high temperature extrusion, acting as a bonding agent. At the same time, the high pressure and the moisture contained in the material promote the formation of the fuel sticks. No binder is required during the forming process. The synergistic combination of high temperature, high pressure and moisture increases the forming rate of large fuel sticks, reduces fuel stick cracking, and improves the quality, mechanical strength and density of the biochar fuel.

[0027] 4. Biochar fuel and its combustion ash after pyrolysis and carbonization are low in heavy metals, sulfur, arsenic, and mercury, making them suitable as a clean alternative to fossil fuels such as coal. The residual rock dust (primarily composed of CaCO3) in the biochar fuel increases the ash melting point and reduces slagging and ash accumulation during use. Furthermore, the combustion ash of chicken manure biochar briquette is rich in potassium, phosphorus, and trace elements, making it suitable for use as fertilizer in farmland.

[0028] 5. The present invention has a simple preparation process, low cost and strong practicality. In industrial production, the combustible gas generated during the pyrolysis process and the firewood residues during the molding process can be returned to the material drying system to reduce fuel consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic diagram of the process flow for preparing chicken manure biochar briquette fuel in the present invention;

[0030] FIG2 is a schematic diagram of the equipment flow for preparing chicken manure biochar briquette fuel in the present invention;

[0031] FIG3 is a SEM photograph of the chicken manure biochar briquette fuel prepared in Example 3 of the present invention;

[0032] FIG4 is an XRD pattern of the stone powder in the chicken manure raw material ( FIG4a ) and the combustion ash of the chicken manure biochar briquette fuel ( FIG4b ) in Example 3 of the present invention. Implementation Method

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0034] This chicken manure biochar briquette uses chicken manure and sawdust as raw materials (the industrial analysis and calorific value analysis of chicken manure and sawdust are shown in Table 1). The sawdust is added in an amount of 10wt% (calorific value) based on dry weight; the sawdust is fir sawdust. As Table 1 shows, the ash content in the chicken manure raw material is significantly higher than that in the sawdust, and the calorific value is lower.

[0035] Table 1

[0036]

[0037] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0038] S1, raw material pretreatment:

[0039] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 6%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 6%.

[0040] S1.2, crushing the chicken manure with a moisture content of 6% after the treatment in step S1.1 (crushing speed of 20,000 r / min) and passing it through a 20-mesh sieve to obtain undersize chicken manure;

[0041] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 0.56 kg of sawdust obtained in step S1.1 for 30 minutes to obtain a mixture, and controlling the average moisture content of the mixture to be 6%;

[0042] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 280°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are square cylinders with a through hole of about 15 mm in diameter formed in the middle, and have an external dimension of 50 × 50 × 450 mm. The formed firewood sticks are shortened to about 30 mm in length;

[0043] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as protective gas, with a heating rate of 3 min / °C, a pyrolysis temperature of 400°C, and a heat preservation time of 120 min to obtain chicken manure biochar briquette fuel.

[0044] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2. The yield of the biochar fuel is calculated by the ratio of the mass of the biochar obtained by pyrolysis to the mass of the firewood dried before pyrolysis.

[0045] Table 2

[0046]

[0047] Example 2

[0048] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 20wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0049] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0050] S1, raw material pretreatment:

[0051] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 12%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 12%.

[0052] S1.2, crushing the chicken manure with a moisture content of 12% after the treatment in step S1.1 (crushing speed of 32000 r / min) and passing it through a 30-mesh sieve to obtain undersize chicken manure;

[0053] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 1.25 kg of sawdust obtained in step S1.1 for 40 minutes to obtain a mixture, and controlling the average moisture content of the mixture to be 12%;

[0054] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 190°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are square cylinders with a through hole of approximately 15 mm in diameter formed in the middle, and have an external dimension of 50×50×450 mm. The formed firewood sticks are shortened to approximately 30 mm in length;

[0055] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as the protective gas, with a heating rate of 8 min / °C, a pyrolysis temperature of 600°C, and a heat preservation time of 90 min to obtain chicken manure biochar briquette fuel.

[0056] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2. Example 3

[0057] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 30wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0058] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0059] S1, raw material pretreatment:

[0060] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 3%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 3%.

[0061] S1.2, crushing the chicken manure with a moisture content of 3% after the treatment in step S1.1 (crushing speed of 8000 r / min) and passing it through a 30-mesh sieve to obtain undersize chicken manure;

[0062] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 2.14 kg of sawdust obtained in step S1.1 for 10 minutes to obtain a mixture, and controlling the average moisture content of the mixture to be 3%;

[0063] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 230°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are square cylinders with a through hole of approximately 15 mm in diameter formed in the middle, and have an external dimension of 50 × 50 × 450 mm. The formed firewood sticks are shortened to approximately 30 mm in length;

[0064] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as the protective gas, with a heating rate of 5 min / °C, a pyrolysis temperature of 500°C, and a heat preservation time of 40 min to obtain chicken manure biochar briquette fuel.

[0065] The SEM photograph of the chicken manure biochar briquette fuel of the present invention is shown in Figure 3. It can be seen from Figure 3 that the wood chips inside the biochar fuel retain the fibrous structure due to the cracks generated by hot extrusion and pyrolysis, while the chicken manure is in a clumping or granular form after pyrolysis, with a dense interior and tightly combined with the carbonized charcoal, indicating that the prepared chicken manure biochar briquette fuel has a high density and high mechanical strength.

[0066] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2.

[0067] The chicken manure biochar briquette fuel in this embodiment was fully burned to obtain combustion ash. The chicken manure biochar briquette fuel and the combustion ash were analyzed for heavy metal content. The analysis results are shown in Table 3.

[0068] Table 3 Heavy metal element content in chicken manure biochar briquette fuel and its combustion ash (unit: mg / kg)

[0069]

[0070] It can be seen from Table 3 that the content of heavy metal elements in the combustion ash obtained by the chicken manure biochar briquette fuel of the present invention is low, which meets the agricultural land soil pollution risk screening value (pH>7.5) in the GB 15618-2018 standard.

[0071] The XRD pattern of the stone powder in the chicken manure raw material of this example is shown in Figure 4(a), and the XRD pattern of the ash from the chicken manure biochar briquette fuel combustion is shown in Figure 4(b). The combustion ash was subjected to XRF analysis, and the test results are shown in Table 4.

[0072] Table 4 XRF results of the combustion ash of chicken manure biochar briquette fuel

[0073]

[0074] As shown in Figure 4(a), the primary component of the stone powder in the chicken manure raw material is CaCO₃, crystallized as calcite, followed by MgO and SiO₂. The stone powder remaining in the biochar fuel after chicken manure pretreatment can increase the ash melting point and reduce slagging and ash accumulation in the equipment during the combustion process. Analysis of Figure 4(b) shows that the XRD patterns of the biochar ash and stone powder are significantly different. The main components, in addition to CaO, SiO₂, and MgO, include KCl, K₂SO₄, CaSO₄, Ca₃(PO₄)₂, and CaMnO₃. The results in Tables 3 and 4, as well as Figure 4, indicate that the ash from biochar combustion is rich in the nutrients K and P, as well as trace elements. Therefore, biochar combustion ash can be considered a good fertilizer for crops and plants. Example 4

[0075] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 40wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0076] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0077] S1, raw material pretreatment:

[0078] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 9%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 9%.

[0079] S1.2, crushing the chicken manure with a moisture content of 9% after the treatment in step S1.1 (crushing speed of 20,000 r / min) and passing it through a 10-mesh sieve to obtain undersize chicken manure;

[0080] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 3.33 kg of sawdust obtained in step S1.1 for 20 minutes to obtain a mixture, and controlling the average moisture content of the mixture to be 9%;

[0081] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 230°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are square cylinders with a through hole of approximately 15 mm in diameter formed in the middle, and have an external dimension of 50 × 50 × 450 mm. The formed firewood sticks are shortened to approximately 30 mm in length;

[0082] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as a protective gas, with a heating rate of 10 min / °C, a pyrolysis temperature of 700°C, and a heat preservation time of 20 min to obtain chicken manure biochar briquette fuel.

[0083] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2. Example 5

[0084] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 30wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0085] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0086] S1, raw material pretreatment:

[0087] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 6%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 6%.

[0088] S1.2, crushing the chicken manure with a moisture content of 6% after the treatment in step S1.1 (crushing speed of 8000 r / min) and passing it through a 40-mesh sieve to obtain undersize chicken manure;

[0089] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 2.14 kg of sawdust obtained in step S1.1 for 20 minutes to obtain a mixture, and controlling the average moisture content of the mixture to be 6%;

[0090] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 320°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are rectangular prisms with a through hole of approximately 15 mm in diameter formed in the middle and external dimensions of 50 × 50 × 450 mm. The formed firewood sticks are shortened to approximately 30 mm in length;

[0091] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as a protective gas, with a heating rate of 10 min / °C, a pyrolysis temperature of 600°C, and a heat preservation time of 60 min to obtain chicken manure biochar briquette fuel.

[0092] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2. Example 6

[0093] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 40wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0094] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0095] S1, raw material pretreatment:

[0096] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 5%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 5%.

[0097] S1.2, crushing the chicken manure with a moisture content of 5% after the treatment in step S1.1 (crushing speed of 8000 r / min) and passing it through a 40-mesh sieve to obtain undersize chicken manure;

[0098] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 3.33 kg of sawdust obtained in step S1.1 for 10 minutes to obtain a mixture, and controlling the average moisture content of the mixture to be 5%;

[0099] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 280°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are square cylinders with a through hole of about 15 mm in diameter formed in the middle, and have an external dimension of 50 × 50 × 450 mm. The formed firewood sticks are shortened to about 30 mm in length;

[0100] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as the protective gas, with a heating rate of 5 min / °C, a pyrolysis temperature of 600°C, and a heat preservation time of 60 min to obtain chicken manure biochar briquette fuel.

[0101] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2. Example 7

[0102] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 40wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0103] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0104] S1, raw material pretreatment:

[0105] S1.1. Air-dry fresh chicken manure until its moisture content is less than 20%, then dry it in a forced air drying oven at 105°C to a moisture content of 6%. Sawdust is sieved through a 7-mesh sieve and then dried at 105°C to a moisture content of 6%.

[0106] S1.2, crushing the chicken manure with a moisture content of 6% after the treatment in step S1.1 (crushing speed of 32000 r / min) and passing it through a 30-mesh sieve to obtain undersize chicken manure;

[0107] S2, stirring and mixing: mechanically stirring and uniformly mixing 5 kg of undersized chicken manure obtained in step S1.2 and 3.3 g of sawdust obtained in step S1.1 for 30 min to obtain a mixture, and controlling the average moisture content of the mixture to 6%;

[0108] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 320°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are rectangular prisms with a through hole of approximately 15 mm in diameter formed in the middle and external dimensions of 50 × 50 × 450 mm. The formed firewood sticks are shortened to approximately 30 mm in length;

[0109] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as the protective gas, with a heating rate of 3 min / °C, a pyrolysis temperature of 800°C, and a heat preservation time of 20 min to obtain chicken manure biochar briquette fuel.

[0110] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2.

[0111] Comparative Example 1

[0112] The chicken manure biochar briquette fuel uses raw materials including chicken manure and sawdust (the industrial analysis and calorific value analysis of the chicken manure and sawdust are shown in Table 1), wherein the added amount of sawdust is 10wt% calculated on a dry weight basis; the sawdust is fir sawdust.

[0113] As shown in Figures 1 and 2, the method for preparing the chicken manure biochar briquette fuel specifically includes the following steps:

[0114] S1, raw material pretreatment: fresh chicken manure is naturally air-dried to a moisture content of less than 20%, and then dried in a forced air drying oven at 105°C to a moisture content of 6%; sawdust is passed through a 7-mesh sieve and dried at 105°C to a moisture content of 6%;

[0115] S2, stirring and mixing: 5 kg of chicken manure with a moisture content of 6% obtained in step S1 is simply crushed at a low speed or manually crushed, and then mechanically stirred and uniformly mixed with 0.56 kg of sawdust obtained in step S1 for 30 minutes to obtain a mixture, wherein the average moisture content of the mixture is controlled to be 6%;

[0116] S3, hot extrusion molding of firewood sticks: The mixture obtained in step S2 is hot extruded at 280°C using a screw extruder, and dried to obtain firewood sticks; the firewood sticks are square cylinders with a through hole of about 15 mm in diameter formed in the middle, and have an external dimension of 50 × 50 × 450 mm. The formed firewood sticks are shortened to about 30 mm in length;

[0117] S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as protective gas, with a heating rate of 3 min / °C, a pyrolysis temperature of 400°C, and a heat preservation time of 120 min to obtain chicken manure biochar briquette fuel.

[0118] The performance test of the chicken manure biochar briquette fuel prepared in this example is shown in Table 2.

[0119] As can be seen from Table 2, the calorific value of the chicken manure biochar briquette fuel prepared in Example 6 of the present invention reached more than 20 MJ / kg, which is much higher than the A1 grade (≥15.5 MJ / kg) in the domestic agricultural industry standard NY / T 2909-2016 "Quality Grading of Biomass Solid Briquette Fuels". Compared with the calorific value of the sawdust raw material in Table 1 of 18.91 MJ / kg, the calorific value has been significantly improved.

[0120] In Comparative Example 1, unscreened chicken manure was used to prepare chicken manure biochar briquette fuel. Except for the unscreened and crushed methods, the ash content of the chicken manure biochar briquette fuel in Comparative Example 1 was 59.09%, which was 15.83% higher than the ash content of 43.26% in Example 1. The calorific value of the chicken manure biochar briquette fuel in Comparative Example 1 was lower than that of the chicken manure raw material. Therefore, the ash content of the biochar fuel of the present invention was significantly reduced, and the calorific value was improved.

[0121] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A chicken manure biochar briquette fuel, characterized in that: The raw materials used for the molded fuel include chicken manure and sawdust, wherein the amount of sawdust added calculated by dry weight is ≤40wt%.

2. The chicken manure biochar briquette fuel according to claim 1, characterized in that: The wood chips are fir sawdust.

3. A method for preparing chicken manure biochar briquette fuel according to claim 1, characterized in that: The specific steps include: S1, raw material pretreatment: S1.

1. Dry the fresh chicken manure to less than 20% moisture content, and then dry it to 3%-12% moisture content; sieve the sawdust through a 7-mesh sieve and dry it to 3%-12% moisture content; S1.2, crushing the chicken manure with a moisture content of 3%-12% after the treatment in step S1.1 and passing it through a 10-40 mesh sieve to obtain the chicken manure under the sieve; S2, stirring and mixing: mechanically stirring and mixing the chicken manure obtained in step S1.2 and the sawdust obtained in step S1.1 for 10-40 minutes to obtain a mixture; S3, hot extrusion molding of firewood sticks: hot extrusion molding the mixture obtained in step S2 at a temperature of 190-320° C., and obtaining firewood sticks after drying; S4, pyrolysis: the firewood obtained in step S3 is subjected to argon as protective gas, with a heating rate of 3-10 min / °C, a pyrolysis temperature of 400-800°C, and a heat preservation time of 20-120 min to obtain chicken manure biochar shaped fuel.

4. The method for preparing chicken manure biochar briquette fuel according to claim 3, characterized in that: The crushing speed in step S1.2 is 8000-32000 r / min.

5. The method for preparing chicken manure biochar briquette fuel according to claim 3, characterized in that: In step S2, the moisture content of the mixture is controlled at 3-12%.

6. The method for preparing chicken manure biochar briquette fuel according to claim 3, characterized in that: In step S3, the fuel rod is a square column, a through hole with a diameter of about 15 mm is formed in the middle, and the external dimensions are 50×50×450 mm.

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