Method for preparing briquetted fuel by mixing semi-dried sludge and oil-tea camellia fruit hulls

Abstract

The application discloses a method for preparing formed fuel by mixing semi-dried sludge and oil-tea camellia fruit hulls, and the method comprises the following steps: (1) washing and drying the oil-tea camellia fruit hulls, then crushing and sieving the oil-tea camellia fruit hulls to obtain oil-tea camellia fruit hull powder; drying high-moisture sludge to obtain semi-dried sludge; (2) baking the oil-tea camellia fruit hull powder under a mixed atmosphere of oxygen and nitrogen to obtain baked oil-tea camellia fruit hulls, or pyrolyzing the oil-tea camellia fruit hull powder under a nitrogen atmosphere to obtain oil-tea camellia fruit hull biochar; (3) mixing and stirring the semi-dried sludge and the baked oil-tea camellia fruit hulls or the oil-tea camellia fruit hull biochar, uniformly placing water, and then preparing formed fuel. The method is simple, easy to operate and low in cost, the prepared formed fuel particles can realize rapid reduction of urban sludge and recycling of energy, and the method has the advantages of low energy consumption, high particle strength, no pollution and the like when the formed particles are prepared.

Description

Technical Field

[0001] This invention belongs to the fields of solid waste resource utilization technology, environmental protection technology and energy conservation technology, and specifically relates to a method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail. Background Technology

[0002] Dewatered sludge can be used as biomass fuel, but as a byproduct of wastewater treatment, it is an extremely complex heterogeneous body composed of organic matter, metals, inorganic particles, and colloidal particles. The main characteristics of sludge are high water content (even exceeding 90%), high organic matter content, easy decay and foul odor, fine particles, low specific gravity, and a colloidal liquid state. It contains various toxic and harmful substances, such as heavy metals, toxic pollutants, pathogens, microorganisms, and salts, leading to air, surface water, and food pollution. While incineration can significantly reduce its volume, thermally destroy toxic organic components and pathogens, stabilize heavy metals, and recover energy, it still causes air pollution. Biomass is a carbon-neutral fuel; mixing dewatered sludge and biomass to form pellets can reduce carbon dioxide emissions and save China a significant amount of money spent annually on sludge treatment and disposal. Therefore, using sludge mixed with biomass to prepare briquettes can reduce and effectively utilize the generated waste. In recent years, my country has mainly focused on preparing briquettes by mixing sludge with coal and agricultural waste straw, and preparing coal-water slurry fuel by mixing sludge with coal.

[0003] However, the existing technology still has the following technical problems:

[0004] 1) When sludge is mixed with straw or coal to prepare sludge briquettes, the sludge has a high moisture content and needs to be dried to a very low moisture content before use. Since straw is a high-fiber material with a high moisture content, it must first be sun-dried or oven-dried, then crushed into fine powder, and finally mixed with sludge or coal and pressurized to prepare briquettes or pellet fuel. This results in a large consumption of heat energy required for sludge drying, and the sludge mixed with straw or coal also has problems such as low forming rate, low strength, lack of water resistance, and easy pulverization during transportation and use.

[0005] 2) When sludge is mixed with coal to prepare coal-water slurry, the high viscosity, high water holding capacity and low calorific value of sludge cause problems such as low sludge addition (generally not exceeding 10%), poor slurry formation, low concentration, high viscosity and low calorific value when sludge is directly mixed with coal.

[0006] 3) Research results on sludge blending technology for biomass fuel preparation are only at the laboratory stage and semi-industrial test stage. The preparation of sludge into briquettes and sludge-coal slurries on industrial production lines and the combustion of these products are basically nonexistent.

[0007] Chinese patent document application number 201510507637.4 discloses a sludge-biomass briquettes fuel and its preparation method. The raw materials are sludge particles and straw powder. The preparation method involves first extruding sludge to obtain sludge particles with a particle size of 2-4 cm, then mixing the sludge particles and straw powder at a mass ratio of 2-10:10, and finally pressing the mixture into briquettes to obtain sludge-biomass briquettes fuel. However, this method requires sludge to account for ≤50% of the fuel, necessitates extruding the sludge into sludge particles, requires the addition of stabilizers and dispersants, and the ash residue after combustion of the briquettes can easily cause soil pollution.

[0008] Chinese patent document application number 201410046446.8 discloses a method for manufacturing densely packed biomass fuel from sludge, comprising the following steps: selecting domestic sewage sludge as the main raw material, piling the mixture in a fermentation site to form a heap, spraying the surface of the heap with a deodorizing and decomposition-promoting fermentation bacterial solution, spraying the surface of the heap with a white-rot fungal solution, and deeply turning the heap until the moisture content of the material in the heap drops to 30%, thus ending the fermentation process; and then thoroughly mixing the fermented and dried material with lignocellulosic biomass material with a mixture moisture content of 18% and extruding it into shape. This method requires sludge composting, adding bacterial solution for deodorization, spraying with white-rot fungal solution, and turning the heap, making the process complex, time-consuming, and resulting in a low moisture content in the mixture.

[0009] Chinese patent document application number 201510050628.7 discloses a method and system for preparing biomass pellet fuel, including the following steps: 1) Drying biomass raw materials and sludge raw materials separately with high-temperature steam at 160℃~200℃ until the moisture content of the biomass raw materials is ≤10% and the moisture content of the sludge raw materials is 25%~35%; 2) Crushing: Crushing the dried sludge raw materials until the particle size of the crushed sludge raw materials is ≤5mm, and coarsely grinding the dried biomass raw materials until the particle size of the coarsely ground biomass raw materials is 5mm~20mm; 3) [The text abruptly ends here, likely due to an incomplete sentence or missing information.] The biomass raw materials are roasted using high-temperature flue gas at 220℃~300℃. The inlet temperature of the biomass roasting device is controlled at 200℃~280℃, and the outlet temperature at 150℃~200℃. Roasting is carried out for 10min~40min under anaerobic conditions, followed by cooling. 4) The roasted and cooled biomass raw materials are finely ground, with a particle size ≤3mm. 5) The sludge additives, pulverized sludge raw materials, and finely ground biomass raw materials are mixed evenly, and the moisture content of the mixed raw materials is adjusted to 12%~18%. Then, the mixture is extruded to obtain biomass pellet fuel. This method suffers from several drawbacks: excessively high temperatures can kill microorganisms in the sludge, leading to spoilage; high energy consumption; sludge requires drying and pulverization; low sludge moisture content necessitates the addition of additives; and the low moisture content of the mixed raw materials, coupled with a high proportion of dried sludge, hinders pellet formation. Summary of the Invention

[0010] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art, especially the problems of air pollution (CO, NOx) and odor of sludge caused by the direct disposal and incineration of large quantities of camellia oleifera fruit and cattail in the prior art. This invention provides a simple, convenient, easy-to-operate, and low-cost method for preparing shaped fuel by mixing semi-dried sludge with camellia oleifera fruit and cattail. The shaped fuel pellets prepared by this method can realize the rapid reduction of urban sludge and the recovery and utilization of energy. The energy consumption of preparing shaped fuel pellets is low, the pellet strength is high, and there is no pollution.

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0012] A method for preparing molded fuel by mixing semi-dried sludge with camellia oleifera fruit and cattail includes the following steps:

[0013] (1) Wash and dry the camellia fruit and cattail, then crush and sieve to obtain camellia fruit and cattail powder; dry the high-moisture sludge until the moisture content is 50% to 55% to obtain semi-dried sludge;

[0014] (2) The tea oil fruit powder is heated to 270℃~300℃ in a mixed atmosphere of oxygen and nitrogen to obtain baked tea oil fruit powder;

[0015] (3) Mix the semi-dried sludge with roasted camellia fruit and stir, let it stand at 4℃~5℃ to make the moisture uniform, and then extrude it into shape under 2kN~4kN pressure and 100℃~110℃ to obtain shaped fuel.

[0016] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia fruit and cattail, preferably, in step (2), the baking time is 1h to 2h, the volume fraction of oxygen in the mixed atmosphere is 15% to 17%, the volume fraction of nitrogen is 83% to 85%, the heating rate is 5℃ / min to 10℃ / min, and the gas flow rate is 200mL / min ± 2mL / min.

[0017] In the above-mentioned method for preparing briquettes by mixing semi-dried sludge with camellia oleifera fruit and cattail, preferably, in step (3), the amount of semi-dried sludge and roasted camellia oleifera fruit and cattail is configured according to the national first-grade standard calorific value of 16.9±0.5MJ / kg; the calorific value of the semi-dried sludge is 5887J / g~10668J / g, and the calorific value of the roasted camellia oleifera fruit and cattail is 20000J / g~26000J / g.

[0018] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail, preferably, in step (1), the moisture content of the semi-dried sludge is 50%.

[0019] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail, preferably, in step (1), the drying temperature is 105℃~110℃, the particle size of the camellia and cattail powder is 40 mesh~120 mesh, the moisture content of the high-moisture sludge is 80%~90%, and the drying temperature is 40℃±2℃.

[0020] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia fruit and cattail, preferably, in step (3), the extrusion movement rate during the extrusion stage is 5 mm / min to 8 mm / min, and the pushing movement rate during the extrusion stage is 2 mm / min to 3 mm / min.

[0021] In the above-mentioned method for preparing granulated fuel by mixing semi-dried sludge with camellia and cattail, preferably, the granulated fuel is in granular form and the particle size of the granulated fuel is 6.8 mm to 7.2 mm.

[0022] As a general technical concept, the present invention also provides a method for preparing briquettes by mixing semi-dried sludge with camellia oleifera fruit and cattail, comprising the following steps:

[0023] (1) Wash and dry the camellia fruit and cattail, then crush and sieve to obtain camellia fruit and cattail powder; dry the high-moisture sludge until the moisture content is 50% to 55% to obtain semi-dried sludge;

[0024] (2) Pyrolysis of Camellia oleifera fruit powder at 500℃~700℃ under nitrogen atmosphere to obtain Camellia oleifera fruit biochar.

[0025] (3) Mix the semi-dried sludge with camellia and cattail biochar, place it at 4℃~5℃ to make the moisture uniform, and then extrude it into shape under a pressure of 2kN~4kN and a temperature of 100℃~110℃ to obtain shaped fuel.

[0026] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia fruit and cattail, preferably, in step (2), the pyrolysis time is 1h to 2h, the heating rate is 5℃ / min to 10℃ / min, and the gas flow rate is 200mL / min ± 2mL / min.

[0027] In the above-mentioned method for preparing briquettes by mixing semi-dried sludge with camellia and cattail, preferably, in step (3), the amount of semi-dried sludge and camellia and cattail biochar is configured according to the national first-grade standard calorific value of 16.9±0.5MJ / kg for briquettes, the calorific value of the semi-dried sludge is 5887J / g~10668J / g, and the calorific value of the camellia and cattail biochar is 28000J / g~31000J / g.

[0028] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail, preferably, in step (1), the moisture content of the semi-dried sludge is 50%.

[0029] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail, preferably, in step (1), the drying temperature is 105℃~110℃, the particle size of the camellia and cattail powder is 40 mesh~120 mesh, the moisture content of the high-moisture sludge is 80%~90%, and the drying temperature is 40℃±2℃.

[0030] In the above-mentioned method for preparing molded fuel by mixing semi-dried sludge with camellia fruit and cattail, preferably, in step (3), the extrusion movement rate during the extrusion stage is 5 mm / min to 8 mm / min, and the pushing movement rate during the extrusion stage is 2 mm / min to 3 mm / min.

[0031] In the above-mentioned method for preparing granulated fuel by mixing semi-dried sludge with camellia and cattail, preferably, the granulated fuel is in granular form and the particle size of the granulated fuel is 6.8 mm to 7.2 mm.

[0032] In this invention, the calorific value of semi-dried sludge refers to the heat generated by burning semi-dried sludge after it is completely dried. Sludge also generates heat by burning after it is completely dried. When the calorific value of semi-dried sludge is low, the mass fraction of semi-dried sludge is 17% to 56%. When the calorific value of semi-dried sludge is high, the mass fraction of semi-dried sludge is 24% to 65.5%.

[0033] Camellia oleifera fruit shell: also known as camellia oleifera fruit shell, is a residual product from the processing of camellia oleifera into tea oil. It includes cellulose, hemicellulose, lignin, polysaccharides, flavonoids, saponins, tannins and other active ingredients.

[0034] Compared with the prior art, the advantages of the present invention are as follows:

[0035] (1) The method of the present invention is simple, easy to operate, and low in cost. The resulting molded fuel pellets can achieve rapid reduction of urban sludge and energy recovery and utilization. The molded pellets have the advantages of low energy consumption, high particle strength, and no pollution when preparing them.

[0036] This invention involves baking or pyrolyzing Camellia oleifera fruit, which can reduce moisture content, increase the energy density of biomass, reduce the content of S and Cl, improve the performance in the thermochemical conversion process, increase the energy density and calorific value of Camellia oleifera fruit, increase the mixing amount of semi-dried sludge, and reduce energy loss during sludge drying and gas emissions after combustion of shaped pellets.

[0037] In this invention, sludge is used as an additive to facilitate the preparation of granulated fuel. It also increases the mixing volume of sludge, reduces energy loss during sludge drying, solves the pollution problems caused by direct sludge combustion, and mitigates the drawbacks of high energy consumption and high cost associated with direct sludge combustion. Semi-drying the sludge, reducing its moisture content to only 50%–55%, allows the microorganisms in the sludge to contribute to pellet formation. This process is energy-efficient, requires no other additives, and ensures a high proportion of sludge with a moisture content of 50%–55% in the mixture, which is beneficial for pellet formation.

[0038] This invention utilizes a semi-dried sludge mixture with camellia and cattail shoots, roasted or pyrolyzed to prepare briquettes, enabling rapid sludge reduction and resource recovery for increased profits. The resulting briquettes have low water absorption, are easy to store, and have a long shelf life. The briquettes formed by adding sludge have low energy consumption, high quality, and produce fewer pollutants during combustion, thus contributing to PM2.5 control. The roasting or pyrolysis of biomass reduces S and Cl content, resulting in less pollution and less slag formation during briquette combustion.

[0039] (2) In the research and development process, the effects of sludge addition on energy consumption and fuel quality analysis during the molding process were studied. The effects of different proportions of sludge mixed with Camellia oleifera fruit, roasted Camellia oleifera fruit, and Camellia oleifera fruit biochar on energy consumption and particle properties during molding were investigated. The combustion behavior and gas emission characteristics of biomass granules mixed with different proportions of sludge were analyzed. It was found that the method of the present invention can rapidly reduce and recycle sludge, kill pathogens, bacteria, antibiotic resistance genes, etc. in sludge, solve the air pollution (CO, NOx) problems caused by direct incineration of large quantities of Camellia oleifera fruit, and solve the odor problem of sludge. Compared to existing technologies, this invention only requires semi-drying the high-moisture sludge at around 40°C, retaining more microorganisms in the sludge, which helps in granulation and increases the mixing volume of sludge. It does not require extrusion into sludge granules, nor does it require the addition of stabilizers or dispersants. The addition of sludge also controls the gases produced by the combustion of the granules. Camellia oleifera fruit itself contains high levels of lignin, so there is no need to add other substances. The mixed materials do not require composting. It is time-saving, simple, convenient, and effective. Attached Figure Description

[0040] Figure 1 The following are flowcharts illustrating the specific experimental steps of Embodiments 1-5 of the present invention.

[0041] Figure 2 The diagram shows the calorific value of the raw materials used in Examples 1-5 of this invention.

[0042] Figure 3 The images show actual particle images of the shaped fuels prepared in Examples 1-5 of this invention.

[0043] Figure 4 The diagram shows the extrusion energy consumption of the shaped fuels prepared in Examples 1-5 of this invention.

[0044] Figure 5 The diagram shows the extrusion energy consumption of the molded fuels prepared in Examples 1-5 of this invention.

[0045] Figure 6 Density diagrams of the shaped fuels prepared in Examples 1-5 of this invention.

[0046] Figure 7 The diagram shows the water absorption rate of the molded fuels prepared in Examples 1-5 of this invention.

[0047] Figure 8 The diagram shows the combustion particle emission of the shaped fuels prepared in Examples 1-2 of this invention.

[0048] Figure 9 The diagram shows the combustion particle emission of the shaped fuels prepared in Examples 3-5 of this invention. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. The materials and instruments used in the following embodiments are commercially available, and the moisture content of the high-moisture sludge is 80%–90%.

[0050] Example 1

[0051] A method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to the present invention, such as... Figure 1 As shown, it includes the following steps:

[0052] (1) Wash the Camellia oleifera fruit and put it into an oven at 105℃ to dry. Take out the Camellia oleifera fruit and put it into a pulverizer to crush and sieve to obtain Camellia oleifera fruit powder. The particle size range of the Camellia oleifera fruit powder is 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ for drying until the sludge moisture content is 50%, and obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0053] (2) The camellia fruit powder was placed in a rotary tube furnace, and a mixed atmosphere of oxygen and nitrogen was introduced. The temperature was raised to 270℃ and baked for 2 hours to obtain roasted camellia fruit, with a calorific value of 24.2 MJ / kg. Figure 2 As shown; in the mixed atmosphere, the volume fraction of oxygen is 15%, the volume fraction of nitrogen is 85%, the gas flow rate is 200 mL / min, and the heating rate is 10 °C / min.

[0054] (3) The semi-dried sludge was mixed with roasted camellia oleifera fruit and stirred. A sample was prepared using the national standard first-grade calorific value of 16.9 MJ / kg for briquetted fuel, i.e., the mass ratio of semi-dried sludge to roasted camellia oleifera fruit at 270℃ was 40:60 (STCs1). The mixture was placed in a beaker and stirred for 1 hour, then placed in a refrigerator at 4-5℃ and allowed to stand for 48 hours to ensure uniform moisture content. Finally, it was extruded into briquettes at 4 kN pressure and 110℃. The extrusion speed during the extrusion stage was 5 mm / min, and the pushing speed during the extrusion stage was 2 mm / min, resulting in briquetted fuel in granular form with a particle size of 6.8 mm to 7.2 mm. Figure 3 STCs1 in the image. A physical image of the shaped fuel pellets is shown below. Figure 3 As shown, the extrusion energy consumption and blasting energy consumption of the formed pellet are as follows: Figure 4 , Figure 5 As shown.

[0055] Example 2

[0056] A method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to the present invention, such as... Figure 1 As shown, it includes the following steps:

[0057] (1) Wash the Camellia oleifera fruit and put it into an oven at 105℃ to dry. Take out the Camellia oleifera fruit and put it into a pulverizer to crush and sieve to obtain Camellia oleifera fruit powder. The particle size range of the Camellia oleifera fruit powder is 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ for drying until the sludge moisture content is 50%, and obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0058] (2) The camellia fruit powder was placed in a rotary tube furnace, and a mixed atmosphere of oxygen and nitrogen was introduced. The temperature was raised to 300℃ and baked for 2 hours to obtain roasted camellia fruit, with a calorific value of 25.8 MJ / kg. Figure 2 As shown; in the mixed atmosphere, the volume fraction of oxygen is 15%, the volume fraction of nitrogen is 85%, the gas flow rate is 200 mL / min, and the heating rate is 10 °C / min.

[0059] (3) The semi-dried sludge was mixed with roasted camellia oleifera fruit and stirred. A sample was prepared using the national standard first-grade calorific value of 16.9 MJ / kg for briquetted fuel, i.e., the mass ratio of semi-dried sludge to roasted camellia oleifera fruit at 300℃ was 45:55 (STCs²). The mixture was placed in a beaker and stirred for 1 hour, then placed in a refrigerator at 4-5℃ and allowed to stand for 48 hours to ensure uniform moisture content. Finally, it was extruded into briquettes under a pressure of 4 kN and a temperature of 110℃. The extrusion speed was 5 mm / min during the extrusion stage and 2 mm / min during the pushing speed during the extrusion stage, resulting in briquetted fuel in granular form with a particle size of 6.8 mm to 7.2 mm. A picture of the briquetted fuel granules is shown below. Figure 3As shown, the extrusion energy consumption and blasting energy consumption of the formed pellet are as follows: Figure 4 , Figure 5 As shown.

[0060] Example 3

[0061] A method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to the present invention, such as... Figure 1 As shown, it includes the following steps:

[0062] (1) Wash the Camellia oleifera fruit and put it into an oven at 105℃ to dry. Take out the Camellia oleifera fruit and put it into a pulverizer to crush and sieve to obtain Camellia oleifera fruit powder. The particle size range of the Camellia oleifera fruit powder is 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ for drying until the sludge moisture content is 50%, and obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0063] (2) The powdered Camellia oleifera fruit was placed in a tube furnace, a nitrogen atmosphere was introduced, and the temperature was raised to 500℃ for 2 hours for pyrolysis. The heating rate was 10℃ / min, and the gas flow rate was 200mL / min. Camellia oleifera fruit biochar was obtained with a calorific value of 29.3MJ / kg. Figure 2 As shown;

[0064] (3) The semi-dried sludge was mixed with Camellia oleifera and Camellia oleifera biochar at 500℃. A sample was prepared using the national standard for briquette fuel, with a calorific value of 16.9 MJ / kg, i.e., semi-dried sludge : 500℃ Camellia oleifera and Camellia oleifera biochar = 53 : 47 (SCsb1). The mixture was placed in a beaker and stirred for 1 hour, then placed in a refrigerator at 4-5℃ for 48 hours to ensure uniform moisture content. Finally, it was extruded into briquettes at 4 kN pressure and 110℃. The extrusion speed was 5 mm / min during the extrusion stage and 2 mm / min during the pushing speed during the extrusion stage, resulting in briquettes with a particle size of 6.8 mm to 7.2 mm. A picture of the briquettes is shown below. Figure 3 As shown, the extrusion energy consumption and blasting energy consumption of the formed pellet are as follows: Figure 4 , Figure 5 As shown.

[0065] Example 4

[0066] A method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to the present invention, such as... Figure 1 As shown, it includes the following steps:

[0067] (1) Wash the Camellia oleifera fruit and put it into an oven at 105℃ to dry. Take out the Camellia oleifera fruit and put it into a pulverizer to crush and sieve to obtain Camellia oleifera fruit powder. The particle size range of the Camellia oleifera fruit powder is 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ for drying until the sludge moisture content is 50%, and obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0068] (2) The powdered Camellia oleifera fruit was placed in a tube furnace, a nitrogen atmosphere was introduced, and the temperature was raised to 600℃ for pyrolysis for 2 hours. The heating rate was 10℃ / min, and the gas flow rate was 200mL / min. Camellia oleifera fruit biochar was obtained with a calorific value of 29.7MJ / kg. Figure 2 As shown;

[0069] (3) The semi-dried sludge was mixed with Camellia oleifera and Camellia oleifera biochar at 600℃. A sample was prepared using the national standard for briquette fuel, with a calorific value of 16.9 MJ / kg, i.e., semi-dried sludge : 600℃ Camellia oleifera and Camellia oleifera biochar = 54 : 46 (SCsb2). The mixture was placed in a beaker and stirred for 1 hour, then placed in a refrigerator at 4-5℃ for 48 hours to ensure uniform moisture content. Finally, it was extruded into briquettes at 4 kN pressure and 110℃. The extrusion speed was 5 mm / min, and the pushing speed was 2 mm / min, resulting in briquettes with a particle size of 6.8 mm to 7.2 mm. A picture of the briquettes is shown below. Figure 3 As shown, the extrusion energy consumption and blasting energy consumption of the formed pellet are as follows: Figure 4 , Figure 5 As shown.

[0070] Example 5

[0071] A method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to the present invention, such as... Figure 1 As shown, it includes the following steps:

[0072] (1) Wash the camellia fruit and put it into an oven at 105℃ to dry. Take out the camellia fruit and put it into a pulverizer to crush and sieve to obtain camellia fruit powder with a particle size of 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ to dry until the sludge moisture content is 50% to obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0073] (2) The powdered Camellia oleifera fruit was placed in a tube furnace, and a nitrogen atmosphere was introduced. The heating rate was 10℃ / min, the gas flow rate was 200mL / min, and the temperature was raised to 700℃ for pyrolysis. The temperature was maintained at 700℃ for 2 hours to obtain Camellia oleifera fruit biochar with a calorific value of 30.8MJ / kg. Figure 2 As shown.

[0074] (3) The semi-dried sludge was mixed with Camellia oleifera and Camellia oleifera biochar at 700℃. A sample was prepared using the national standard for briquette fuel, with a calorific value of 16.9 MJ / kg, i.e., semi-dried sludge : 700℃ Camellia oleifera and Camellia oleifera biochar = 56 : 44 (SCsb3). The mixture was placed in a beaker and stirred for 1 hour, then placed in a refrigerator at 4-5℃ for 48 hours to ensure uniform moisture content. Finally, it was extruded into briquettes at 4 kN pressure and 110℃. The extrusion speed was 5 mm / min, and the pushing speed was 2 mm / min, resulting in briquettes with a particle size of 6.8 mm to 7.2 mm. A picture of the briquettes is shown below. Figure 3 As shown, the extrusion energy consumption and blasting energy consumption of the formed pellet are as follows: Figure 4 , Figure 5 As shown.

[0075] Comparative Example 1

[0076] A method for preparing briquettes from semi-dried sludge mixed with camellia oleifera fruit and cattail, such as Figure 1 As shown, it includes the following steps:

[0077] (1) Wash the camellia fruit and put it into an oven at 105℃ to dry. Take out the camellia fruit and put it into a pulverizer to crush and sieve to obtain camellia fruit powder with a particle size of 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ to dry until the sludge moisture content is 50% to obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0078] (2) The camellia fruit powder was placed in a rotary tube furnace, and a mixed atmosphere of oxygen and nitrogen was introduced. The temperature was raised to 210℃ and baked for 2 hours to obtain roasted camellia fruit, with a calorific value of 20.8 MJ / kg. Figure 2 As shown; in the mixed atmosphere, the volume fraction of oxygen is 15%, the volume fraction of nitrogen is 85%, the gas flow rate is 200 mL / min, and the heating rate is 10 °C / min.

[0079] (3) The semi-dried sludge was mixed with roasted camellia fruit and stirred. A sample was prepared using the national standard first-grade calorific value of 16.9 MJ / kg for briquetted fuel. The sample was placed in a beaker and stirred for 1 hour, then placed in a 4-5℃ refrigerator for 48 hours to ensure uniform moisture content. The briquetted fuel was then extruded into shape under a pressure of 4 kN and a temperature of 110℃. The extrusion speed during the extrusion stage was 5 mm / min, and the pushing speed during the extrusion stage was 2 mm / min. Briquetted fuel with a particle size of 6.8 mm to 7.2 mm was obtained. A picture of the briquetted fuel particles is shown below. Figure 3 As shown.

[0080] Comparative Example 2

[0081] A method for preparing briquettes from semi-dried sludge mixed with camellia oleifera fruit and cattail, such as Figure 1 As shown, it includes the following steps:

[0082] (1) Wash the camellia fruit and put it into an oven at 105℃ to dry. Take out the camellia fruit and put it into a pulverizer to crush and sieve to obtain camellia fruit powder with a particle size of 40-120 mesh. Put the high-moisture sludge into an oven at 40℃ to dry until the sludge moisture content is 50% to obtain semi-dried sludge with a calorific value of 5.9 MJ / kg.

[0083] (2) The camellia fruit powder was placed in a rotary tube furnace, and a mixed atmosphere of oxygen and nitrogen was introduced. The temperature was raised to 240℃ and baked for 2 hours to obtain roasted camellia fruit, with a calorific value of 22.3 MJ / kg. Figure 2 As shown; in the mixed atmosphere, the volume fraction of oxygen is 15%, the volume fraction of nitrogen is 85%, the gas flow rate is 200 mL / min, and the heating rate is 10 °C / min.

[0084] (3) The semi-dried sludge was mixed with roasted camellia fruit and stirred. A sample was prepared using the national standard first-grade calorific value of 16.9 MJ / kg for briquetted fuel. The sample was placed in a beaker and stirred for 1 hour, then placed in a 4-5℃ refrigerator for 48 hours to ensure uniform moisture content. The briquetted fuel was then extruded into shape under a pressure of 4 kN and a temperature of 110℃. The extrusion speed during the extrusion stage was 5 mm / min, and the pushing speed during the extrusion stage was 2 mm / min. Briquetted fuel with a particle size of 6.8 mm to 7.2 mm was obtained. A picture of the briquetted fuel particles is shown below. Figure 3 As shown.

[0085] Performance characterization:

[0086] Examples 1-5 can prepare shaped fuel pellets, with the following mass ratios of semi-dried sludge to treated Camellia oleifera fruit and tamarisk: semi-dried sludge : 270℃ roasted Camellia oleifera fruit and tamarisk = 40 : 60 (STCs1), semi-dried sludge : 300℃ roasted Camellia oleifera fruit and tamarisk = 45 : 55 (STCs2), semi-dried sludge : 500℃ Camellia oleifera fruit and tamarisk biochar = 53 : 47 (SCsb1), semi-dried sludge : 600℃ Camellia oleifera fruit and tamarisk biochar = 54 : 46 (SCsb2), and semi-dried sludge : 700℃ roasted Camellia oleifera fruit and tamarisk = 56 : 44 (SCsb3). Figure 4-6 It can be seen that the shaped fuel prepared by the present invention has low energy consumption and a density greater than 1, which meets the national standard for shaped fuel. The water absorption rate of the shaped pellets tends to saturate more quickly.

[0087] Figure 7 This shows the moisture absorption rate of the formed granules. For example... Figure 7As shown, the water absorption rate of STCs1, STCs2, SCsb1, SCsb2, and SCsb3 was measured every half hour. Between 3 and 5 hours, the moisture absorption rates of STCs1, STCs2, SCsb1, SCsb2, and SCsb3 approached saturation, with absorption rates of 6.7%, 7%, 8.1%, 8.3%, and 11.2%, respectively. After 48 hours, the average water absorption rates of STCs1, STCs2, SCsb1, SCsb2, and SCsb3 were 6.8%, 7.2%, 8.2%, 8.3%, and 11.1%, respectively, showing little change and facilitating storage and transportation.

[0088] Depend on Figure 8 The analysis yielded Table 1, from which... Figure 9 Table 2 shows the results. Compared to shaped fuel pellets (SCs) made from semi-dried sludge and unbaked (or unpyrolyzed) camellia fruit, STCs1 shaped pellets reduced PM1 by 59.78% after combustion. 10 A 35.25% reduction; After combustion of STCs2 molded particles, PM1 decreased by 41.54%, PM2.5% 10 The PM1 content was reduced by 35.63%; after combustion of SCsb1 molded particles, the PM1 content was reduced by 18.18%, and PM2.5 content was reduced by 35.63%. 10 The PM1 content was reduced by 13.16% after the combustion of SCsb2 shaped particles, and the PM2.5 content was reduced by 18.41%. 10 The PM1 content was reduced by 14.78% after the combustion of SCsb3 shaped particles, and the PM2.5 content was reduced by 20.43%. 10 The emissions were reduced by 20.46%. This indicates that the gas emissions from the combustion of semi-dried sludge mixed with Camellia oleifera fruit pellets significantly reduced PM1 and PM2.5 levels. 10 The yield has decreased significantly, reducing environmental pollution.

[0089] Table 1 PM Yields from Combustion of SCs, STCs1, and STCs2 Molded Fuel Particles

[0090]

[0091] Table 2 PM Yields from Combustion of SCs, SCsb1, SCsb2, and SCsb3 Molded Fuel Particles

[0092]

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing molded fuel by mixing semi-dried sludge with camellia oleifera fruit and cattail, characterized in that, Includes the following steps: (1) Wash and dry the camellia fruit and cattail, then crush and sieve to obtain camellia fruit and cattail powder; dry the high-moisture sludge until the moisture content is 50% to 55% to obtain semi-dried sludge; the drying temperature is 40℃±2℃. (2) The camellia fruit powder is heated to 270℃~300℃ in a mixed atmosphere of oxygen and nitrogen to obtain baked camellia fruit powder; (3) Mix the semi-dried sludge with roasted camellia fruit and stir, let it stand at 4℃~5℃ to make the moisture uniform, and then extrude it into shape under a pressure of 2kN~4kN and a temperature of 100℃~110℃ to obtain shaped fuel; the amount of semi-dried sludge and roasted camellia fruit and stir is configured according to the national first-grade standard calorific value of 16.9±0.5MJ / kg for shaped fuel; the calorific value of the semi-dried sludge is 5887J / g~10668J / g, and the calorific value of the roasted camellia fruit and stir is 20000J / g~26000J / g; when the calorific value of the semi-dried sludge is low, the mass fraction of the semi-dried sludge is 17%~56%, and when the calorific value of the semi-dried sludge is high, the mass fraction of the semi-dried sludge is 24%~65.5%.

2. The method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail as described in claim 1, characterized in that, In step (2), the baking time is 1h to 2h, the volume fraction of oxygen in the mixed atmosphere is 15% to 17%, the volume fraction of nitrogen is 83% to 85%, the heating rate is 5℃ / min to 10℃ / min, and the gas flow rate is 200mL / min ± 2mL / min.

3. The method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to any one of claims 1 to 2, characterized in that, In step (1), the moisture content of the semi-dried sludge is 50%; In step (1), the drying temperature is 105℃~110℃, the particle size of the camellia fruit powder is 40 mesh~120 mesh, and the moisture content of the high-moisture sludge is 80%~90%. In step (3), during the extrusion molding, the extrusion moving speed in the extrusion stage is 5 mm / min to 8 mm / min, and the pushing moving speed in the extrusion stage is 2 mm / min to 3 mm / min. The shaped fuel is in granular form, and the particle size of the shaped fuel is 6.8 mm to 7.2 mm.

4. A method for preparing molded fuel by mixing semi-dried sludge with camellia oleifera fruit and cattail, characterized in that, Includes the following steps: (1) Wash and dry the camellia fruit and cattail, then crush and sieve to obtain camellia fruit and cattail powder; dry the high-moisture sludge until the moisture content is 50% to 55% to obtain semi-dried sludge; the drying temperature is 40℃±2℃. (2) Pyrolysis of Camellia oleifera fruit powder at 500℃~700℃ under nitrogen atmosphere to obtain Camellia oleifera fruit biochar; (3) Mix and stir the semi-dried sludge with camellia and cattail biochar, place it at 4℃~5℃ to make the moisture uniform, and then extrude it into shape under a pressure of 2kN~4kN and a temperature of 100℃~110℃ to obtain shaped fuel; the amount of semi-dried sludge and camellia and cattail biochar is configured according to the national first-grade standard calorific value of 16.9±0.5MJ / kg, the calorific value of the semi-dried sludge is 5887J / g~10668J / g, and the calorific value of the camellia and cattail biochar is 28000J / g~31000J / g; when the calorific value of the semi-dried sludge is low, the mass fraction of the semi-dried sludge is 17%~56%, and when the calorific value of the semi-dried sludge is high, the mass fraction of the semi-dried sludge is 24%~65.5%.

5. The method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail according to claim 4, characterized in that, In step (2), the pyrolysis time is 1h to 2h, the heating rate is 5℃ / min to 10℃ / min, and the gas flow rate is 200mL / min ± 2mL / min.

6. The method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail according to any one of claims 4 to 5, characterized in that, In step (1), the moisture content of the semi-dried sludge is 50%.

7. The method for preparing molded fuel by mixing semi-dried sludge with camellia and cattail according to any one of claims 4 to 5, characterized in that, In step (1), the drying temperature is 105℃~110℃, the particle size of the camellia fruit powder is 40 mesh~120 mesh, and the moisture content of the high-moisture sludge is 80%~90%.

8. The method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to any one of claims 4 to 5, characterized in that, In step (3), during the extrusion molding, the extrusion movement speed in the extrusion stage is 5 mm / min to 8 mm / min, and the pushing movement speed in the extrusion stage is 2 mm / min to 3 mm / min.

9. The method for preparing briquettes from semi-dried sludge mixed with camellia and cattail shoots according to any one of claims 4 to 5, characterized in that, The shaped fuel is in granular form, and the particle size of the shaped fuel is 6.8 mm to 7.2 mm.

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