Preparation process of RDF fuel
Through the improvement of the traditional RDF fuel preparation process, the use of shredding and temperature-controlled forming processes and the combination of calcium-containing sludge has been solved, and the problem of high emission of flue gas pollutants in the traditional process has been achieved, which has achieved a significant reduction in pollutants during combustion and efficient utilization of resources.
Patent Information
- Application Number
- CN202510707372.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-06-27
AI Technical Summary
The traditional RDF fuel preparation process lacks source control of flue gas pollutants, resulting in more emissions of pollutants such as carbon dioxide, nitrogen oxides, and particulate matter in the exhaust gas during combustion.
By collecting and classifying various general solid waste, including combustible solid waste, non-combustible impurities and flue gas control agent solid waste, the shredding and temperature-controlled molding process is adopted, and calcium-containing sludge is used to achieve solid sulfur, nitrogen and chlorine, and reduce pollutant emissions during combustion.
It has achieved full utilization of combustible solid waste, reduced pollutant emissions during combustion, reduced governance costs, conformed to the concept of circular economy, and adapted to a variety of combustion equipment, broadened application scenarios.
Smart Images
Figure CN120209906A_ABST
Abstract
Description
Technical Field
[0001] The present invention mainly relates to the technical field of solid waste treatment and energy utilization, and particularly relates to a preparation process of RDF fuel. Background Art
[0002] With the acceleration of the global industrialization and urbanization processes, the generation amount of general solid wastes such as waste paper, waste plastics, agricultural straws, and waste textiles shows an increasing trend year by year. Traditional treatment methods such as landfilling and incineration not only occupy a large amount of land resources, but also easily cause secondary pollution of soil, groundwater, and the atmosphere, and the long-term operation and maintenance costs are high. Landfilling treatment requires supporting complex facilities such as anti-seepage and leachate treatment, while incineration faces the problem of controlling toxic gases. In the energy field, the consumption structure with coal as the dominant energy has not been fundamentally changed, but the pollutants such as sulfur dioxide, nitrogen oxides, and particulate matter released by its combustion have become the main sources of air pollution. Developing clean and renewable alternative energy, RDF fuel, with its stable calorific value and easy storage and transportation characteristics, has become an important bridge connecting solid waste treatment and energy transformation. However, traditional RDF fuel preparation processes mostly focus on the treatment of single combustible solid waste and lack source control of flue gas pollutants.
[0003] It should be noted that the above content belongs to the technical cognition scope of the inventor. Due to the vast and extremely complex technical content in this field, the above content of this application does not necessarily constitute the prior art. Summary of the Invention
[0004] 1. Technical problems to be solved by the invention: The present invention provides a preparation process of RDF fuel to solve the technical problems existing in the above background art.
[0005] 2. Technical solutions: To achieve the above object, the technical solution provided by the present invention is: a preparation process of RDF fuel, including the following steps: Step 1: Collect various general solid wastes and classify them. The general solid wastes include combustible solid wastes, non-combustible impurities, and solid wastes of flue gas control agents. Remove non-combustible impurities such as metals and glass through manual sorting and mechanical screening; Step 2: Tear the classified large solid wastes to make their particle sizes reach a suitable range; for solid wastes with high water content, use a drying device for preliminary dehydration to reduce their water content; Step 3: Mix and formulate combustible solid waste and solid waste of flue gas control agent type proportionally. Generally, solid waste sludge is used as the flue gas control agent, and the formulation ratio is adjusted according to the indexes of various materials measured by laboratory sampling. At the same time, according to the laboratory measurement data, calcium-containing solid waste sludge is added during the formulation process to achieve waste treatment with waste and reduce the emissions of pollutants such as carbon dioxide, nitrogen oxides, and particulate matter in the exhaust gas during combustion; Step 4: Feed the formulated materials into a shredder and go through two or three shredding processes to make their particle size reach the appropriate range; Step 5: Feed the shredded materials into a molding machine and extrude them into RDF fuel of a specific shape under certain pressure and temperature. The specific shape includes granular and rod-shaped. During the molding process, an appropriate amount of water and sludge is added as needed; Step 6: Conduct quality inspection on the RDF fuel. The inspection indexes include calorific value, moisture content, ash content, sulfur content, chloride ion content, etc.; Step 7: Transport the qualified fuel to the combustion equipment to replace coal combustion and optimize the combustion process parameters.
[0006] Further, in the above Step 1, the combustible solid waste includes agricultural straws, general solid waste sludge, waste textiles, waste leather products, waste paper, waste wood products, waste rubber products, waste plastics and resin products, waste composite packaging, waste fiberglass reinforced plastics, glass fibers, rock wool, and mixed combustibles after screening of decoration types.
[0007] Further, in the above Step 2, the materials after preliminary dehydration include agricultural straws, waste wood products, and plant residues with high water content, and the water content after preliminary dehydration is reduced to 10%-20%.
[0008] Further, in the above Step 3, the material indexes include sulfur content, halogen content, and lower calorific value.
[0009] Further, in the above Step 3, the calcium-containing general solid waste sludge contains calcium carbonate and calcium oxide, which are used for sulfur fixation, nitrogen fixation, and chlorine fixation to reduce the generation of exhaust gas.
[0010] Further, in the above Step 4, the first shredder shreds the materials to a larger particle size, and the second or third shredder shreds the materials to the required appropriate particle size, and the appropriate particle size is determined according to the requirements of the molding machine.
[0011] Further, in the above Step 5, the addition amounts of water and sludge are determined according to the characteristics of the materials and the requirements of the molding quality to improve the molding quality and stability of the fuel and reduce the flue gas emissions.
[0012] Further, in the above Step 7, the combustion process parameters include the air supply chain, combustion temperature, and combustion time. By optimizing the parameters, full combustion of the fuel is achieved and the emissions of pollutants are reduced.
[0013] 3. Beneficial effects: Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects: Through the precise separation of three types of solid waste, the full utilization of combustible solid waste, zero landfill of non-combustible impurities, and resource utilization of solid waste in flue gas control agents are realized, which conforms to the concept of circular economy; Utilize the chemical reactions of calcium components with sulfur, nitrogen, and chlorine elements in general solid waste sludge to reduce the generation of pollutants during the combustion stage, replace traditional flue gas end-treatment equipment, treat waste with waste, and reduce the treatment cost; The shredding and temperature-controlled forming processes ensure the uniformity of fuel particle size and the stability of density, adapt to a variety of combustion equipment, and broaden the application scenarios.
[0014] It should be noted that the structures not introduced in the present invention are the same as the prior art or can be implemented using the prior art because they do not involve the design key points and improvement directions of the present invention, and will not be elaborated here. Description of the drawings
[0015] Figure 1 It is the process flow chart of the preparation of the present invention. Detailed implementation manners
[0016] To facilitate the understanding of the present invention, the present invention will be described more comprehensively with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.
[0017] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "page", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.
[0018] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.
[0019] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "linkage", "fixation", "provided with", "arranged on" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0020] Referring to the attached Figure 1 , a preparation process for RDF fuel, the core steps are as follows: Step 1: Collection and classification of general solid waste Collect various general solid wastes including combustible solid wastes (agricultural straws, general solid waste sludge, waste textiles, waste leather products, waste paper, waste wood products, waste rubber products, waste plastic and resin products, waste composite packaging, waste fiberglass reinforced plastics, fiberglass, rock wool and mixed combustibles after screening of decoration waste), incombustible impurities (metals, glass, stones, etc.) and solid wastes of flue gas control agents (such as general solid waste sludge containing calcium carbonate and calcium oxide); through manual sorting combined with mechanical screening (such as magnetic separation and screening equipment), separate the incombustible impurities and retain the combustible solid wastes and solid wastes of flue gas control agents.
[0021] Step 2: Crushing and pretreatment Feed the classified large-sized combustible solid wastes (such as waste wood and straw bales) into a slicing machine and cut them to a particle size of 5 - 10 cm; for high-moisture solid wastes with a water content ≥ 30% (such as kitchen waste and wet wood chips), use a drum dryer to dry them to a water content of 10% - 20% to provide conditions for subsequent forming. Step 3: Batching and mixing According to the indexes of combustible solid wastes measured in the laboratory (sulfur content, halogen content, lower calorific value, etc.), mix and formulate the combustible solid wastes and solid wastes of flue gas control agents (general solid waste sludge) at a mass ratio of 5:1 - 10:1. For materials with a sulfur content > 1%, additionally add sludge with a calcium content ≥ 30% (mainly composed of calcium carbonate and calcium oxide), and achieve sulfur fixation, nitrogen fixation and chlorine fixation through chemical reactions (such as CaO + SO2 + 0.5O2 → CaSO4) to reduce the generation of combustion waste gas from the source.
[0022] Step 4: Shredding Adopt a shredding process: the primary shredder crushes the mixed materials to 2 - 5 cm, and the secondary or tertiary shredder further crushes them to a uniform particle size of 8 - 4 cm to meet the feeding requirements of the forming machine. Step 5: Extrusion forming Feed the shredded materials into an extrusion molding machine and extrude them into granular (φ3 - 6 cm) or rod-shaped (φ5 - 10 mm) fuels under the conditions of a pressure of 5 - 15 MPa and a temperature of 80 - 150 °C. During the molding process, 5% - 30% of the total mass of water and sludge can be added to increase the fuel density to 1.1 - 1.3 g / cm³ and the molding stability. Step Six: Quality Inspection Conduct multi-index inspections on the formed fuels: Calorific value: Measured using an oxygen bomb calorimeter, required to be ≥15 MJ / kg; Moisture content: Measured by the drying method, controlled at 10% - 20%; Sulfur content / chloride ion: Measured by chemical titration method, respectively ≤0.8%, ≤0.5%; Ash content: Measured by the muffle furnace burning method, ≤15%. Step Seven: Combustion Application Transport the qualified fuels to a circulating fluidized bed boiler or a cement rotary kiln, and achieve full combustion by optimizing the combustion parameters (excess air coefficient 1.2 - 1.5, combustion temperature 800 - 950 °C, residence time ≥2 s). The measured results show that the SO2 emissions are reduced by 60% - 70% compared with coal combustion, NOx is reduced by 40% - 50%, and the particulate matter emissions comply with the "Emission Standard of Air Pollutants for Boilers" GB13271 - 2014.
[0023] Example 1: Preparation of RDF from Typical Municipal Solid Wastes (Sludge Compatibility) 1. Solid Waste Collection and Classification Combustible solid wastes: 200 kg of waste textiles, 100 kg of waste composite packaging, 100 kg of straw, 200 kg of waste plastics and resins, 20 kg of plant residues (after dehydration), 100 kg of waste leather products, 80 kg of waste paper; Solid wastes of flue gas control agent type: 200 kg of calcium-containing sludge from a sewage treatment plant (CaO content 40%); Incombustible impurities: 50 kg of separated metals and glass (removal rate 98%).
[0024] 2. Pretreatment Cut the straw / waste packaging into pieces of 3 - 5 cm, and dry the plant residues (original moisture content 60%) to a moisture content of 18%.
[0025] 3. Batching and Mixing Compatibility ratio: Combustible solid waste: sludge = 8:2 (mass ratio); Laboratory inspection: The sulfur content of the raw materials is 0.7%, the halogen content is 0.6%, and the target sulfur content is ≤0.6% after adding sludge.
[0026] 4. Shredding and Molding After secondary shredding, the particle size is 0.8 cm, the forming pressure is 12 MPa, the temperature is 130 °C, and φ8 mm pellet fuel is produced.
[0027] 5. Quality Inspection
[0028] 6. Combustion Test Boiler type: 10 t / h chain grate boiler; Emission data: SO2 = 90 mg / m³ (compared with 250 mg / m³ for coal combustion), NOx = 180 mg / m³ (compared with 300 mg / m³ for coal combustion), and the compliance rate is 100%.
[0029] Example 2: Treatment of high-sulfur industrial solid waste (coordination and blending of steel slag) 1. Composition of solid waste Combustible solid waste: 300 kg of waste rubber (sulfur content 1.2%), 200 kg of waste paper, and 100 kg of rice husk; Solid waste of flue gas control agent type: 200 kg of steel slag from steel plant (CaO content 50%); Treatment target: Reduce the sulfur emission during combustion to ≤100 mg / m³.
[0030] 2. Key process parameters Moisture content after drying: 15% for rice husk, and waste rubber is crushed to 2 cm; Blending ratio: Combustible solid waste: steel slag = 7:3, and the calcium-sulfur molar ratio is 1.5:1.
[0031] 3. Forming and combustion effects Fuel density: 1.25 g / cm³, calorific value 16.8 MJ / kg; Sulfur fixation efficiency: 78%, SO2 emission 85 mg / m³, superior to the "Pollution Control Standard for Municipal Solid Waste Incineration" (GB18485-2020).
[0032] Example 3: Comparative experiment on complex solid waste blending
[0033] To sum up, through the blending of solid waste of flue gas control agent type, the sulfur emission is reduced by 40% - 43% compared with the traditional process; the co-treatment of multiple solid wastes significantly reduces the calorific value, and the forming qualification rate is increased by 10% - 13%, verifying the process stability; different flue gas control agents (sludge, steel slag) are suitable for different highly polluting solid wastes, reflecting the process flexibility.
[0034] The above-described embodiments merely represent certain implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.
Claims
1. A preparation process of RDF fuel, characterized in that, It includes the following steps: Step 1: Collect various types of general solid wastes and classify them. The general solid wastes include combustible solid wastes, non-combustible impurities, and flue gas control agent solid wastes. Remove non-combustible impurities such as metals, stones, glass, etc. through manual sorting and mechanical screening; Step 2: Tear up the classified large solid wastes to make their particle size reach a suitable range; for solid wastes with high water content, use a drying device for preliminary dehydration to reduce their water content; Step 3: Mix and formulate the combustible solid wastes and flue gas control agent solid wastes in proportion. The general solid waste sludge is used as a flue gas control agent, and the formulation ratio is adjusted according to various material indexes measured by laboratory sampling. At the same time, according to the laboratory measurement data, add calcium-containing general solid waste sludge during the formulation process to achieve waste treatment with waste and reduce the emissions of pollutants such as carbon dioxide, nitrogen oxides, and particulate matter in the exhaust gas during combustion; Step 4: Feed the formulated materials into a shredder and go through two or three shredding processes to make their particle size reach a suitable range; Step 5: Feed the shredded materials into a forming machine (briquetting machine), and under certain pressure and temperature, extrude and form them into RDF fuels with specific shapes. The specific shapes include granular and rod-shaped. During the forming process, add an appropriate amount of water and sludge as needed; Step 6: Conduct quality inspection on the RDF fuels. The inspection indexes include calorific value, moisture content, ash content, sulfur content, chloride ion content, etc.; Step 7: Transport the qualified fuels to combustion equipment to replace coal combustion and optimize the combustion process parameters.
2. The RDF fuel preparation process according to claim 1, characterized in that: In the said Step 1, the combustible solid wastes include agricultural straws, general solid waste sludge, waste textiles, waste leather products, waste paper, waste wood products, waste rubber products, waste plastic and resin products, waste composite packaging, waste fiberglass, fiberglass, rock wool, and mixed combustibles after screening of decoration types.
3. The RDF fuel preparation process according to claim 1, characterized in that: In the said Step 2, the materials after preliminary dehydration include agricultural straws, waste wood products, and plant residues with high water content, and the water content after preliminary dehydration is reduced to 10%-20%.
4. A process for preparing RDF fuel according to claim 1, characterized in that: In the said Step 3, the material indexes include sulfur content, halogen content, and lower calorific value.
5. A process for preparing RDF fuel according to claim 1, characterized in that: In the said Step 3, the calcium-containing general solid waste sludge contains calcium carbonate and calcium oxide, which are used for sulfur fixation, nitrogen fixation, and chlorine fixation to reduce the generation of exhaust gas.
6. The RDF fuel preparation process according to claim 1, wherein: In the said Step 4, the first shredder tears up the materials to a larger particle size, and the second or third shredder tears up the materials to the required suitable particle size, and the suitable particle size is determined according to the requirements of the forming machine.
7. A process for preparing RDF fuel according to claim 1, characterized in that: In the said Step 5, the addition amounts of water and sludge are determined according to the characteristics of the materials and the requirements of forming quality to improve the forming quality and stability of the fuels and reduce the flue gas emissions.
8. A process for preparing RDF fuel according to claim 1, characterized in that: In the said Step 7, the combustion process parameters include air supply chain, combustion temperature, and combustion time. By optimizing the parameters, the fuels can be fully combusted and the emissions of pollutants can be reduced.