A pretreatment process for preparing a new energy fuel derived from county life garbage

Abstract

The application discloses a kind of county life garbage preparation derived new energy fuel pretreatment process, it is related to fuel pretreatment technical field, including the following steps: life garbage breaks bag, single-shaft high-speed bag breaker, garbage only breaks bag and does not break up;Pretreatment sorting, large piece of garbage and recyclable are separated by artificial and intelligent sorting combination;Multi-stage separation, after magnetic separation, screening, air separation separates light plastic film, heavy derivative fuel raw material and heavy inorganic matter;Multi-stage crushing, crushing by two-stage crusher;Composite modification pretreatment inhibits stench diffusion, adds biomass charcoal-based adsorbent, composite modification additive, turns over operation;Microorganism-membrane synergistic dewatering, after 48h fermentation at 50-60 DEG C, extrusion dewatering;Homogenization forming, into fuel stick.The application is applied by whole-process synergistic design and multiple modification additives, effectively improves fuel heat value and forming stability, comprehensively controls stench pollution, energy consumption and cost reduction, realizes county life garbage low-cost harmless.

Description

Technical Field

[0001] This invention relates to the field of fuel pretreatment technology, specifically to a pretreatment process for preparing new energy fuels derived from municipal solid waste in a county. Background Technology

[0002] With the acceleration of urbanization, the amount of municipal solid waste has surged. Traditional landfill and incineration methods have drawbacks such as land occupation, environmental pollution, and energy waste. Waste-to-fuel pretreatment has become a key direction for resource utilization. However, existing technologies still have many shortcomings in terms of improving fuel calorific value, controlling pollutants, and improving resource recovery efficiency.

[0003] For example, in the patent application document with patent publication number CN106623339A and patent name "Method for Fueling Treatment of Municipal Solid Waste and Additives Applied to the Treatment", it is mentioned that a fueling additive composition is combined with nano-mist microbial spraying to achieve dehydrated fueling of waste, which can treat waste with high water content and recover leachate. However, the additive composition of this technology is complex and mainly consists of natural substances, with a single function and lack of a targeted removal mechanism for heavy metals. At the same time, the nano-mist generating device relies on electromagnetic wave technology, which has high energy consumption, and the fuel has insufficient stability after molding and is prone to moisture absorption and deterioration during storage.

[0004] For example, in the patent application document with patent publication number CN111872046A and patent title "A Homogenization Process, System and Application for Municipal Solid Waste Fuel Production", it is mentioned that waste-derived fuel is prepared through multi-stage crushing, sorting and homogenization treatment. The additives can fix sulfur and chlorine. However, the additives in this process are only composed of quicklime, fly ash and wood chips. They do not involve the functions of promoting organic matter degradation and heavy metal chelation. Moreover, the homogenization treatment relies on medium and low temperature heating, which has high energy consumption. The leachate is simply treated and reused without realizing energy recovery. At the same time, there is a lack of effective purification measures for exhaust gas, which can easily cause secondary pollution.

[0005] In addition, the patent application document with patent publication number CN101565647B and patent title "Pretreatment method and equipment for using municipal solid waste as fuel" mentions reducing the moisture and inorganic matter content of waste through air suspension separation and air drying processes to improve the calorific value of fuel. However, this technology mainly relies on air drying for dehydration, which is inefficient. Furthermore, it does not use composite modification methods to optimize fuel performance, and harmful elements such as sulfur and chlorine in the fuel are not effectively controlled, resulting in a high risk of pollutant emissions during incineration. At the same time, the process lacks a directional conversion mechanism for complex organic matter in waste, resulting in limited improvement in fuel calorific value and making it difficult to meet the high-efficiency combustion requirements of industrial boilers.

[0006] Furthermore, existing technologies generally suffer from problems such as poor process integration, incomplete resource recovery, and limited pollutant control. Some technologies focus only on fuel molding, neglecting the risks of secondary pollution from heavy metals and harmful gases. Others have high energy consumption and operating costs, making large-scale promotion difficult. Therefore, there is an urgent need to develop a pretreatment process for preparing new energy fuels from municipal solid waste in counties that features strong process synergy, diverse additive functions, comprehensive pollutant control, and efficient resource recovery, in order to address the shortcomings of existing technologies. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] In view of the shortcomings of existing technologies, such as single-function additives, insufficient control of heavy metals and harmful elements such as sulfur and chlorine, lack of leachate and exhaust gas recovery and utilization, poor fuel calorific value and storage stability, and high process energy consumption, this invention provides a pretreatment process for the preparation of new energy fuels derived from municipal solid waste in county areas.

[0009] (II) Technical Solution

[0010] A pretreatment process for preparing new energy fuels from municipal solid waste in a county includes the following steps:

[0011] S1. Household waste bag breaking: Collect household waste in the county and use a single-shaft high-speed bag breaking machine to break the bags, with a speed of 700-800 r / min;

[0012] S2. Pre-treatment and sorting: After the county's waste is broken open, it is sorted by a combination of manual sorting and intelligent sorting equipment to separate bulky waste and recyclables. The remaining mixed waste has an organic content of ≥70%. The bulky waste is crushed to a particle size of ≤300mm and then returned to the mixed waste. Recyclables are sorted and recycled.

[0013] S3. Multi-stage sorting: After the bags are broken, the waste is first separated from the ferrous metals by an electromagnetic self-unloading magnetic separator with a magnetic separation intensity of 10000-12000Gs and a separation efficiency of ≥95%. Then, it is screened by a drum screen with a screen aperture of 10-25mm to separate biodegradable organic impurities and inert inorganic impurities with a particle size <25mm. Subsequently, it is sent to an air-flow suspension separator with an air separation velocity of 8-15m / s to separate lightweight plastic film, medium and heavy derivative fuel raw materials, and heavy inorganic matter according to density. The moisture content of the lightweight plastic film is ≤30%, and the moisture content of the medium and heavy derivative fuel raw materials is ≤55%.

[0014] S4. Multi-stage crushing: The medium and heavy derivative fuel raw materials after S3 treatment are crushed sequentially through a first-stage twin-shaft shear crusher and a second-stage high-speed impact crusher. The first-stage crushing speed is 300-500 r / min, and the crushed particle size is ≤100 mm. The second-stage crushing speed is 800-1200 r / min, and the crushed particle size is ≤50 mm.

[0015] S5. Composite Modification Pretreatment to Inhibit Odor Diffusion: By weight, add 8-15 parts of composite modification additive to the organic mixture separated in S3, mix evenly, and then turn over at 25-35℃ for 30-60 minutes; the composite modification additive includes 3-5 parts of biochar-based adsorbent, 1-2 parts of disodium EDTA, 0.5-1 part of composite probiotic agent, 2-3 parts of calcium oxide, 1-2 parts of fly ash, and 0.5-1 part of sodium lignosulfonate; among which, disodium EDTA undergoes a chelation reaction with heavy metals in the waste. Taking Pb²+ as an example, the reaction molecular formula is C 10 H 14 N₂Na₂O₈・₂H₂O + Pb² + →C 10 H 12 N₂O₈Pb・2H₂O+2Na + +2H + The compound probiotic agent is composed of Bacillus subtilis, Saccharomyces cerevisiae, and lactic acid bacteria in a mass ratio of 2:1:1.

[0016] S6. Microbial-membrane co-dehydration: The material treated in S5 is fed into a membrane bio-drying channel, oxygen is introduced, the oxygen content is controlled at 18-22%, the temperature is 50-60℃, and the fermentation time is 48h, during which the material is turned over every 2h; after fermentation, the material is dehydrated by an extrusion dehydrator at a pressure of 0.8-1.2MPa, and the moisture content of the dehydrated material is ≤20%;

[0017] S7. Homogenization molding: The composite modified and bio-dried material is fed into a two-roll extrusion molding machine with a molding pressure of 15-25MPa and a holding time of 10-20s to produce rod-shaped fuel with a particle size of 30-50mm. After molding, the material is naturally cooled to room temperature for 30-60min.

[0018] Furthermore, the process also includes a leachate recovery and treatment step: the leachate generated during the S5 dehydration process is collected, first filtered through a grid to remove suspended impurities, and then sent to an anaerobic fermentation tank. 5-8 parts of compound fermentation agent are added, the temperature is controlled at 35-38℃, and the fermentation time is 7-10 days. The biogas produced is desulfurized and dehydrated and then used as an auxiliary energy source for S6 microbial-membrane co-dehydration. The fermented biogas residue is dried and then returned to S5 to mix with the organic matter mixture. The biogas slurry is biochemically treated to meet the standards and then used within the plant area.

[0019] Furthermore, it also includes exhaust gas purification and recovery steps: collecting exhaust gas from S1 municipal solid waste bag breaking, S5 composite modification pretreatment, and S6 microbial-membrane synergistic dehydration, first passing it through a scrubbing tower to remove particulate matter and acidic / alkaline substances, then sending it to an activated carbon adsorption tower to adsorb odor substances at an adsorption temperature of 20-30℃ and a space velocity of 500-800h⁻¹, and finally recovering carbon dioxide through a membrane separation device. The recovered carbon dioxide has a purity of ≥95% and can be used for subsequent fuel storage and preservation or industrial utilization.

[0020] Furthermore, the intelligent sorting equipment in S3 includes an infrared spectral sorter, an electromagnetic separator, an intelligent robotic arm, and an eddy current sorter. The infrared spectral sorter has an identification accuracy of ≥97%, the electromagnetic separator has an efficiency of ≥95% in separating ferrous metals, the intelligent robotic arm has an identification accuracy of ≥90%, and the eddy current sorter has an efficiency of ≥90% in separating non-ferrous metals. Recyclable materials include plastics, ferromagnetic metals, glass, paper, and non-ferrous metals.

[0021] Furthermore, the biomass-based adsorbent in S4 is prepared by anaerobic carbonization of corn stalks at 400-500℃ for 2-3 hours, with a specific surface area ≥500m² / g and a pore size of 2-50nm; calcium oxide purity ≥90% and particle size ≤5μm; fly ash specific surface area ≥300m² / g; and sodium lignosulfonate molecular weight of 20000-50000Da.

[0022] Furthermore, the live bacteria count of the compound probiotic agent in S4 is ≥10. 9 The CFU / g ratio of live bacteria of Bacillus subtilis, Saccharomyces cerevisiae, and lactic acid bacteria is 2:1:1. The survival rate is ≥90% in an environment of 35-45℃, which can promote the degradation of organic matter and the release of water.

[0023] Furthermore, the screw speed of the extrusion dewatering machine in S6 is 50-80 r / min, the filter screen aperture is 0.5-1 mm, the solid recovery rate of the dewatered material is ≥90%, and the leachate generation is ≤0.2 m³ / t of waste.

[0024] Furthermore, the S6 medium-membrane bio-drying channel uses a smart molecular membrane with expanded polytetrafluoroethylene composite membrane as its core material. The pore size is 0.025μm-10μm, the air permeability is about 8-9m³ / (㎡·h), and it can withstand composting temperatures of 55-70℃ or higher. The micropores can effectively block the diffusion of malodorous gases such as ammonia and hydrogen sulfide, as well as pathogens.

[0025] Furthermore, the roller surface temperature of the S7 twin-roll extrusion molding machine is 60-80℃, the compressive strength of the formed particles is ≥1.5MPa, the water absorption rate is ≤10%, the bulk density is 800-1000kg / m³, and the lower heating value is ≥18MJ / kg.

[0026] Furthermore, the waste reduction rate of the entire pretreatment process is ≥70%, the organic matter conversion rate is ≥85%, the sulfur content of the prepared pellet fuel is ≤0.3%, the chlorine content is ≤0.5%, and the heavy metal content meets the requirements of GB / T31856-2015 standard, and can be directly used for industrial boiler combustion or gasification power generation.

[0027] (iii) Beneficial technical effects

[0028] Compared with existing technologies, the beneficial effects of this invention are:

[0029] In terms of process design, this invention adopts an integrated process for municipal solid waste bag breaking, pretreatment sorting, multi-stage sorting, multi-stage crushing, composite modification, composite modification pretreatment to suppress odor diffusion, microbial-membrane synergistic dehydration, and homogenization molding. Each step is closely integrated and synergistically enhances efficiency. The intelligent sorting equipment combining multi-stage sorting and crushing significantly improves the removal efficiency of inorganic matter, laying a solid foundation for subsequent modification treatment. Compared to single dehydration methods, microbial-membrane synergistic dehydration utilizes microorganisms to promote the degradation of organic matter and release water, while also accelerating water separation through membrane action, resulting in superior dehydration performance and effectively reducing energy consumption.

[0030] In terms of additive innovation, the composite modified additive integrates the adsorption function of biomass char-based adsorbents, the heavy metal chelating function of disodium EDTA, the degradation function of composite probiotic agents, and the sulfur and chlorine fixation functions of calcium oxide and fly ash. This multi-functional synergistic effect not only improves fuel quality but also specifically removes harmful components such as heavy metals, sulfur, and chlorine from waste, avoiding secondary pollution during incineration and solving the problem of single-function additives. In particular, the chelation reaction of disodium EDTA with heavy metals can significantly reduce the heavy metal content in fuel, ensuring environmentally friendly combustion.

[0031] In terms of resource recycling and environmental control, the leachate is recycled and treated, and the biogas produced by the anaerobic fermentation of the leachate is used as an auxiliary energy source. The biogas residue is recycled and reused, and the biogas slurry is reused after meeting the standards, realizing the full-process resource utilization of leachate. The exhaust gas purification and recycling step effectively removes particulate matter and odor substances and recovers carbon dioxide, comprehensively controlling secondary pollution and making up for the shortcomings of existing technologies in leachate and exhaust gas treatment.

[0032] In terms of energy consumption and cost control, the membrane bio-drying process does not require high-temperature heating and generates heat through microbial fermentation, which significantly reduces energy consumption. The homogenized fuel has good stability, is not prone to moisture absorption and deterioration during storage, and has excellent combustion performance. The entire process has a high volume reduction rate, a high organic matter conversion rate, and excellent fuel quality. Moreover, the equipment investment and operating costs are low, making it easy to promote and apply on a large scale. It truly realizes the coordinated development of harmlessness, volume reduction, and resource utilization of municipal solid waste. Attached Figure Description

[0033] Figure 1 This is a flow chart of the pretreatment process for preparing new energy fuels from municipal solid waste in county-level areas, as proposed in this invention.

[0034] Figure 2 This is a bar chart comparing the lower heating values ​​of each embodiment and the comparative example;

[0035] Figure 3 These are line graphs showing the storage stability of each embodiment and the comparative example;

[0036] Figure 4 This is a radar chart showing the overall performance of each embodiment and comparative example. Detailed Implementation

[0037] according to Figures 1 to 4 The specific embodiments of the present invention are as follows:

[0038] The following describes in detail the pretreatment process for preparing new energy fuels from municipal solid waste in counties according to the present invention, using three embodiments and one comparative example. All operations are carried out in a waste treatment workshop that meets environmental standards, with the workshop temperature controlled at 25-30℃ and the relative humidity at 40-60%. All raw materials used meet industrial-grade standards, and equipment parameters are strictly set according to the scope of the claims to ensure the repeatability and practicality of the technical solution.

[0039] General Raw Material and Equipment Parameter Specifications

[0040] Regarding the core raw material parameters, the biomass char-based adsorbent in the composite modified additive has a specific surface area ≥500m² / g and a pore size of 2-50nm; the EDTA disodium purity is ≥99% and the molecular weight is 372.24; the composite probiotic agent has a live bacteria count ≥10 9 The cFU / g concentration of the compound fermentation agent for leachate treatment includes methanogens, cellulose-decomposing bacteria, and other microorganisms in a 2:1:1 ratio; calcium oxide purity ≥90% and particle size ≤5μm; fly ash specific surface area ≥300m² / g; and sodium lignosulfonate molecular weight 20000-50000Da. 8 CFU / mL.

[0041] Key equipment parameters are as follows: Single-shaft high-speed bag-breaking machine: speed 700-800 r / min, feed inlet size 500×1200 mm; First-stage twin-shaft shear crusher: speed 300-500 r / min, feed inlet size 500×1000 mm, discharge particle size adjustment range 50-100 mm; Second-stage high-speed impact crusher: speed 800-1200 r / min, hammer material high manganese steel, discharge particle size adjustment range 5-20 mm; Permanent magnet self-unloading magnetic separator: magnetic separation intensity 10000-12000 Gs, processing capacity 10-20 t / h, magnetic field gradient ≥500 T / m; Airflow suspension... The wind separator has an adjustable wind speed range of 5-20 m / s, a cavity diameter of 1.2 m, and a grading efficiency of ≥90%. The intelligent molecular membrane has an ePTFE (expanded polytetrafluoroethylene) composite membrane as its core material, with a pore size of 0.025 μm-10 μm, an air permeability of approximately 8-9 m³ / (㎡·h), and can withstand composting temperatures of 55-70℃ or higher. The extrusion dewatering machine has a screw speed of 50-80 r / min, a filter screen pore size of 0.5-1 mm, and a working pressure of 0.5-1.5 MPa. The twin-roll extrusion molding machine has a roller surface temperature adjustable range of 50-100℃, a molding pressure of 10-30 MPa, and a holding time adjustable range of 5-30 s.

[0042] Example 1

[0043] Process parameter settings

[0044] The process parameters are set as follows: For household waste bag breaking, the single-shaft high-speed bag breaking machine rotates at 750 r / min; in the pre-treatment sorting stage, the intelligent sorting equipment uses an infrared spectral separator with a recognition accuracy of 98%, an electromagnetic iron separator with an iron metal separation efficiency of 96%, an intelligent robotic arm with a recognition accuracy of ≥91%, an eddy current separator with a separation efficiency of 91%, and the remaining mixed waste has an organic matter content of 75%; in the multi-stage sorting stage, the magnetic separation intensity is 11000 Gs, the drum screen aperture is 20 mm, and the airflow suspension classifier has an air velocity of 12 m / s; in the multi-stage crushing stage, the first-stage crushing speed is 400 r / min, the output particle size is ≤90 mm, and the second-stage crushing speed is 100 r / min. 0 r / min, discharge particle size ≤40mm; composite modification to inhibit odor diffusion, 10 parts of composite modification additive added, turning temperature 25℃, continuous turning for 50min; microbial-membrane synergistic dehydration, fermentation temperature 55℃, fermentation time 48h, dehydration pressure 1.0MPa; homogenization and molding, molding pressure 20MPa, holding time 15s, rod-shaped fuel particle size 40mm, cooling time 45min; leachate treatment, anaerobic fermentation temperature 36℃, fermentation time 8 days; tail gas purification, activated carbon adsorption tower space velocity 600h⁻¹, membrane separation device carbon dioxide recovery purity ≥96%.

[0045] Preparation process

[0046] S1. Household waste bag breaking: Collect 1000kg of household waste from the county and break the bags using a single-shaft high-speed bag breaking machine;

[0047] S2. Pre-processing and sorting: After the county's waste is broken open, it is sorted by a combination of manual sorting and intelligent sorting equipment to separate 50kg of bulky waste and 300kg of recyclables, leaving 650kg of mixed waste. The organic content is tested to be 75%. The bulky waste is crushed to a particle size of ≤300mm and then returned to the mixed waste. The recyclables are sorted and recycled.

[0048] S3. Multi-stage sorting: The bagged waste is first separated from the ferrous metal by an electromagnetic self-unloading magnetic separator, which separates 25 kg of ferrous metal with a separation efficiency of 96%. Then, it is screened by a drum screen with a screen aperture of 20 mm, separating 50 kg of biodegradable organic impurities and inert inorganic impurities with a particle size <20 mm. Subsequently, it is sent to an air-flow suspension classifier with an air separation velocity of 12 m / s, which separates 100 kg of lightweight plastic film, 325 kg of medium and heavy derivative fuel raw materials, and 150 kg of heavy inorganic matter according to density.

[0049] S4. Multi-stage crushing: The medium and heavy derivative fuel raw materials after S3 treatment are sequentially passed through a first-stage twin-shaft shear crusher at a speed of 400 r / min, with a particle size of 90 mm after crushing; then they are fed into a second-stage high-speed impact crusher at a speed of 1000 r / min, with a particle size of ≤40 mm after crushing.

[0050] S5. Composite Modification to Inhibit Odor Diffusion: Add 10 parts by weight of composite modifier to 425 kg of organic matter mixture, mix thoroughly, and then turn over at 25-35℃ for 30-60 min. During this period, disodium EDTA undergoes a chelation reaction with heavy metals in the waste, and the composite probiotic agent promotes the initial degradation of organic matter.

[0051] S6. Microbial-membrane co-dehydration: The mixture is fed into a membrane bio-drying channel, oxygen is introduced, the oxygen content is controlled at 20%, the temperature is 55℃, and the fermentation time is 48 hours. The mixture is turned over every 2 hours for 50 minutes. After fermentation, it is fed into a screw extruder for dehydration at a pressure of 1.0 MPa. The moisture content of the dehydrated material is 18%, and 55 kg of leachate and 370 kg of solid material are collected.

[0052] S7. Homogenization Molding: The modified material is fed into a two-roll extrusion molding machine with a roll surface temperature of 70℃, a molding pressure of 20MPa, and a holding time of 15s to produce rod-shaped fuel with a particle size of 40mm. After molding, it is naturally cooled to room temperature for 45 minutes to obtain 337kg of rod-shaped fuel.

[0053] S8. Leachate Recovery and Treatment: 55 kg of leachate generated during the S6 dehydration process is collected. 1 kg of suspended impurities are removed by filtration through a screen, and the leachate is sent to an anaerobic digester. Five parts of compound fermentation agent are added, and the temperature is controlled at 36℃ for 8 days. 12 m³ of biogas is produced, which, after desulfurization and dehydration purification, is used as auxiliary energy for the S6 microbial-membrane co-dehydration process. 10 kg of fermented biogas residue is dried at 80℃ for 2 hours and then returned to S5 to mix with the organic matter mixture. 45 kg of biogas slurry is biochemically treated to meet standards and then used within the plant.

[0054] S9. Exhaust Gas Purification and Recovery: Collect 1500 m³ of exhaust gas generated during the processes of S1 (household waste bag breaking), S5 (composite modification pretreatment), and S6 (microbial co-dehydration). First, remove particulate matter and acidic / alkaline substances through a scrubbing tower, then send it to an activated carbon adsorption tower at an adsorption temperature of 25℃ and a space velocity of 600 h⁻¹ to adsorb odor substances. Finally, recover carbon dioxide through a membrane separation device, with a recovery volume of 280 m³ and a purity of ≥96%, for use in fuel storage and preservation.

[0055] Example 2

[0056] Process parameter settings

[0057] The process parameters are set as follows: For household waste bag breaking, the single-shaft high-speed bag breaker rotates at 750 r / min; in the pre-treatment sorting stage, the intelligent sorting equipment uses an infrared spectral separator with a recognition accuracy of 97%, an electromagnetic iron separator with an iron metal separation efficiency of 95%, an intelligent robotic arm with a recognition accuracy of 90%, and an eddy current separator with a separation efficiency of 90%, resulting in an organic matter content of 70% for the remaining mixed waste; in the multi-stage sorting stage, the magnetic separation intensity is 10000 Gs, the drum screen aperture is 15 mm, and the airflow suspension classifier has an air velocity of 8 m / s; in the multi-stage crushing stage, the primary crusher rotates at 300 r / min, and the output particle size is ≤100 mm. mm, secondary crushing speed 800r / min, discharge particle size ≤40mm; composite modification to inhibit odor diffusion stage, composite modification additive added 8 parts, turning temperature 35℃, continuous turning for 30min; microbial-membrane synergistic dehydration stage, fermentation temperature 50℃, fermentation time 24h, dehydration pressure 0.8MPa; homogenization and molding stage, molding pressure 15MPa, holding time 10s, rod fuel 30mm, cooling time 30min; leachate treatment stage, anaerobic fermentation temperature 35℃, fermentation time 7 days; tail gas purification stage, activated carbon adsorption tower space velocity 500hh - ¹, The purity of carbon dioxide recovery from the membrane separation unit is ≥95%.

[0058] Preparation process

[0059] S1. Household waste bag breaking: Collect 1000kg of household waste in the county and break the bags using a single-shaft high-speed bag breaking machine;

[0060] S2. Pre-processing and sorting: After the county's waste is broken open, it is sorted by a combination of manual sorting and intelligent sorting equipment to separate 50kg of bulky waste and 290kg of recyclables, leaving 660kg of mixed waste. The organic content is tested to be 70%. The bulky waste is crushed to a particle size of ≤280mm and then returned to the mixed waste. The recyclables are sorted and recycled.

[0061] S3. Multi-stage sorting: The bagged waste is first separated into ferrous metals by an electromagnetic self-unloading magnetic separator with a magnetic separation intensity of 10000Gs, separating 22kg of ferrous metals; then it is screened by a drum screen with a screen aperture of 15mm, separating 55kg of biodegradable organic impurities and inert inorganic impurities with a particle size <15mm; then it is sent to an air-flow suspension classifier with an air separation velocity of 8m / s, separating 90kg of lightweight plastic film, 338kg of medium and heavy derivative fuel raw materials and 155kg of heavy inorganic matter according to density.

[0062] S4. Multi-stage crushing: The medium and heavy derivative fuel raw materials after S3 treatment are sequentially passed through a first-stage twin-shaft shear crusher at a speed of 300 r / min, with a particle size ≤100 mm after crushing; then fed into a second-stage high-speed impact crusher for further crushing at a speed of 800 r / min, with a particle size ≤50 mm after crushing.

[0063] S5. Composite Modification to Inhibit Odor Diffusion: By weight, add 8 parts of composite modification additive to 428 kg of organic matter mixture, mix evenly, and then turn over at 35℃ for 30 min. During this period, disodium EDTA undergoes a chelation reaction with heavy metals in the waste, and the composite probiotic agent promotes the initial degradation of organic matter.

[0064] S6. Microbial-membrane co-dehydration: The mixture is fed into a membrane bio-drying channel, oxygen is introduced, the oxygen content is controlled at 18%, the temperature is 50℃, and the fermentation time is 36 hours. The mixture is turned over every 2 hours for 30 minutes. After fermentation, it is fed into a screw extruder dehydrator at a dehydration pressure of 0.8 MPa. The moisture content of the dehydrated material is 19%, and 50 kg of leachate and 378 kg of solid material are collected.

[0065] S7. Homogenization Molding: The modified material is fed into a two-roll extrusion molding machine with a roll surface temperature of 70℃, a molding pressure of 15MPa, and a holding time of 10s to produce rod-shaped fuel with a particle size of 50mm. After molding, it is naturally cooled to room temperature for 30 minutes to obtain 340kg of rod-shaped fuel.

[0066] S8. Leachate Recovery and Treatment: Collect 50 kg of leachate generated during the S6 dehydration process, remove 2 kg of suspended impurities by filtration through a screen, and send it to an anaerobic digester. Add 5 parts of compound fermentation agent, control the temperature at 35℃, and ferment for 7 days. 10 m³ of biogas is produced, which, after desulfurization and dehydration purification, is used as auxiliary energy for the S6 microbial-membrane co-dehydration process. 5 kg of fermented biogas residue is dried at 80℃ for 2 hours and then returned to S5 to mix with the organic matter mixture. 43 kg of biogas slurry is biochemically treated to meet standards and then used within the plant.

[0067] S9. Exhaust Gas Purification and Recovery: Collect 1400 m³ of exhaust gas generated during the processes of S1 (household waste bag breaking), S5 (composite modification pretreatment), and S6 (microbial co-dehydration). First, remove particulate matter and acidic / alkaline substances through a scrubbing tower, then send it to an activated carbon adsorption tower at an adsorption temperature of 25℃ and a space velocity of 600 h⁻¹ to adsorb odor substances. Finally, recover carbon dioxide through a membrane separation device, with a recovery volume of 250 m³ and a purity of ≥95%, for use in fuel storage and preservation.

[0068] Example 3

[0069] Process parameter settings

[0070] The process parameters are set as follows: For household waste bag breaking, the single-shaft high-speed bag breaking machine rotates at 800 r / min; in the pre-treatment sorting stage, the intelligent sorting equipment uses an infrared spectral separator with a recognition accuracy of 99%, an electromagnetic iron separator with an iron metal separation efficiency of 97%, an intelligent robotic arm with a recognition accuracy of ≥92%, an eddy current separator with a separation efficiency of 92%, and the remaining mixed waste has an organic matter content of 75%; in the multi-stage sorting stage, the magnetic separation intensity is 12000 Gs, the drum screen aperture is 25 mm, and the airflow suspension classifier has an air velocity of 15 m / s; in the multi-stage crushing stage, the first-stage crushing speed is 500 r / min, the discharge particle size is ≤80 mm, and the second-stage crushing speed is 120 r / min. 0 r / min, discharge particle size ≤30mm; composite modification to inhibit odor diffusion, 15 parts of composite modification additive added, turning temperature 35℃, continuous turning for 60min; microbial-membrane synergistic dehydration, fermentation temperature 60℃, fermentation time 48h, dehydration pressure 1.2MPa; homogenization and molding, molding pressure 25MPa, holding time 20s, rod-shaped fuel particle size 30mm, cooling time 60min; leachate treatment, anaerobic fermentation temperature 38℃, fermentation time 9 days; tail gas purification, activated carbon adsorption tower space velocity 700h⁻¹, membrane separation device carbon dioxide recovery purity ≥97%.

[0071] Detailed preparation process

[0072] S1. Household waste bag breaking: Collect 1000kg of household waste in the county and break the bags using a single-shaft high-speed bag breaking machine;

[0073] S2. Pre-processing and sorting: After the county's waste is broken open, it is sorted by a combination of manual sorting and intelligent sorting equipment to separate 50kg of bulky waste and 310kg of recyclables, leaving 640kg of mixed waste. The organic content is 78% after testing. The bulky waste is crushed to a particle size of ≤310mm and then returned to the mixed waste. The recyclables are sorted and recycled.

[0074] S3. Multi-stage sorting: The bagged waste is first separated from the ferrous metal by an electromagnetic self-unloading magnetic separator, which separates 28 kg of ferrous metal with a separation efficiency of 97%. Then, it is screened by a drum screen with a screen aperture of 25 mm, separating 55 kg of biodegradable organic impurities and inert inorganic impurities with a particle size <25 mm. Subsequently, it is sent to an air-flow suspension classifier with an air separation velocity of 15 m / s, which separates 103 kg of lightweight plastic film, 327 kg of medium and heavy derivative fuel raw materials, and 145 kg of heavy inorganic matter according to density.

[0075] S4. Multi-stage crushing: The medium and heavy derivative fuel raw materials after S3 treatment are sequentially passed through a first-stage twin-shaft shear crusher at a speed of 500 r / min, with a particle size of 80 mm after crushing; then they are fed into a second-stage high-speed impact crusher for further crushing at a speed of 1200 r / min, with a particle size of ≤30 mm after crushing.

[0076] S5. Composite Modification to Inhibit Odor Diffusion: By weight, add 15 parts of composite modification additive to 430 kg of organic matter mixture, mix evenly, and then turn over at 35℃ for 60 min. During this period, disodium EDTA undergoes a chelation reaction with heavy metals in the waste, and the composite probiotic agent promotes the initial degradation of organic matter.

[0077] S6. Microbial-membrane co-dehydration: The mixture is fed into a membrane bio-drying channel, oxygen is introduced, the oxygen content is controlled at 22%, the temperature is 60℃, and the fermentation time is 48 hours. The mixture is turned over every 2 hours for 60 minutes. After fermentation, it is fed into a screw extruder dehydrator at a dehydration pressure of 1.2 MPa. The moisture content of the dehydrated material is 17%, and 65 kg of leachate and 365 kg of solid material are collected.

[0078] S7. Homogenization molding: The modified material is fed into a two-roll extrusion molding machine with a roll surface temperature of 70℃, a molding pressure of 20MPa, and a holding time of 15s to produce pellet fuel with a particle size of 20mm. After molding, it is naturally cooled to room temperature for 45 minutes to obtain 336kg of pellet fuel.

[0079] S8. Leachate Recovery and Treatment: A total of 65 kg of leachate generated during the S6 dehydration process is collected. 4 kg of suspended impurities are removed by filtration through a screen, and the leachate is sent to an anaerobic digester. Six parts of a compound fermentation agent are added, and the temperature is controlled at 38℃ for 10 days. 15 m³ of biogas is produced, which, after desulfurization and dehydration purification, is used as auxiliary energy for the S6 microbial-membrane co-dehydration process. 13 kg of fermented biogas residue is dried at 80℃ for 2 hours and then returned to S5 to mix with the organic matter mixture. 48 kg of biogas slurry is treated biochemically to meet standards and then used within the plant.

[0080] S9. Exhaust Gas Purification and Recovery: Collect 1600m³ of exhaust gas generated during the processes of S1 (household waste bag breaking), S5 (composite modification pretreatment), and S6 (microbial co-dehydration). First, remove particulate matter and acidic / alkaline substances through a scrubbing tower, then send it to an activated carbon adsorption tower at an adsorption temperature of 25℃ and a space velocity of 600h⁻¹ to adsorb odor substances. Finally, recover carbon dioxide through a membrane separation device with a recovery volume of 320m³ and a purity of ≥97%, which will be used for fuel storage and preservation.

[0081] Comparative Example

[0082] Process parameter settings

[0083] The process parameters are set as follows: pretreatment sorting is done manually only to remove large pieces of waste; there is no intelligent sorting equipment; the remaining mixed waste has an organic matter content of 65%. The crushing stage only involves primary crushing at a speed of 400 r / min, with a discharge particle size ≤100 mm. The sorting stage only involves magnetic separation and screening, without air suspension separation; the magnetic separation intensity is 10000 Gs, and the screen aperture is 15 mm. There is no composite modification stage. The dewatering stage only uses extrusion dewatering, without microbial fermentation; the dewatering pressure is 1.0 MPa. The molding pressure is 20 MPa, and the holding time is 15 s. There are no leachate recovery and treatment or exhaust gas purification stages.

[0084] Detailed preparation process

[0085] S1. Household waste bag breaking: Collect 1000kg of household waste in the county and break the bags using a single-shaft high-speed bag breaking machine;

[0086] S2. Pre-processing and sorting: After the bags are opened, the county's waste is manually sorted to separate 45kg of bulky waste and 275kg of recyclables, leaving 680kg of mixed waste. The organic matter content is 65% after testing.

[0087] S3. Sorting: The bagged waste is first separated into ferrous metals by an electromagnetic self-unloading magnetic separator with a magnetic separation intensity of 10000Gs, which separates 22kg of ferrous metals; then it is screened by a drum screen with a screen aperture of 15mm, which separates 55kg of biodegradable organic impurities and inert inorganic impurities with a particle size <15mm; finally, it is separated by air-free suspension air separation, which directly yields 603kg of mixed organic matter;

[0088] S4. Crushing: The mixed waste is fed into a single-stage twin-shaft shear crusher at a speed of 400 r / min. The crushed particle size is ≤100 mm and the moisture content of the waste is 45%.

[0089] S5. Dehydration: The mixed organic matter is fed into a screw extruder for dehydration at a pressure of 1.0 MPa. The moisture content of the material after dehydration is 30%, and 133 kg of leachate and 470 kg of solid material are collected.

[0090] S6. Molding: The dehydrated material is directly fed into a twin-shaft extrusion molding machine with a molding pressure of 20MPa, a holding time of 15s, a fuel particle size of 50mm, and a cooling time of 45min to obtain 410kg of fuel pellets.

[0091] Performance Indicator Comparison Table

[0092] Lower heating value (MJ / kg) 22.5 20.8 23.2 16.3 Moisture content (%) 18 19 17 25 Sulfur content (%) 0.22 0.25 0.20 0.58 Chlorine content (%) 0.35 0.38 0.32 0.85 Heavy metals (Pb) (mg / kg) 0.008 0.009 0.007 0.035 Particle compressive strength (MPa) 2.1 1.8 2.3 1.2 Bulk density (kg / m³) 920 880 950 750

[0093] This table presents the core performance differences among the experimental groups. The lower heating values ​​of Examples 1-3 were significantly higher than those of the comparative example, with Example 3 reaching 23.2 MJ / kg, a 42.3% increase compared to the comparative example. This is attributed to the combined effects of composite modification and microbial-membrane synergistic drying, which promoted the reconstruction of organic molecules and increased energy density. Regarding pollutant control, the sulfur, chlorine, and heavy metal (Pb) contents of the examples were far lower than those of the comparative example. In particular, Example 3 had a sulfur content of only 0.20% and a heavy metal (Pb) content of 0.007 mg / kg, demonstrating the chelating function of disodium EDTA and the sulfur and chlorine fixation effects of calcium oxide and fly ash. In terms of molding performance, the compressive strength and bulk density of the fuel strips in the examples were superior to those in the comparative example, indicating that the homogenization molding process and the bonding effect of the composite modified additives effectively improved the structural stability of the fuel.

[0094] Storage stability comparison table

[0095] 0 18.0 19.0 17.0 25.0 30 18.5 19.8 17.3 28.6 60 19.2 20.5 17.8 32.4 90 19.8 21.2 18.2 36.8

[0096] This table shows the moisture content change trend of each experimental group during the 90-day storage period, directly reflecting storage stability. The moisture content of Examples 1-3 increased slowly, reaching a maximum of only 21.2% after 90 days (Example 2), and as low as 18.2% in Example 3, with almost no obvious moisture absorption. This is because the biomass char-based adsorbent in the composite modified additive forms a hydrophobic protective film with sodium lignosulfonate, which, combined with the dense structure after homogenization, effectively blocks the intrusion of moisture from the air. In contrast, the comparative examples, due to the lack of modification treatment, had a loose molding structure, resulting in a rapid and continuous increase in moisture content, reaching 36.8% after 90 days, exhibiting severe moisture absorption and partial pulverization, failing to meet the requirements for long-term storage and transportation. These results fully demonstrate that the process of this invention can significantly improve fuel storage stability and extend product shelf life.

[0097] Comprehensive Results Analysis

[0098] Examples 1-3 strictly follow the technical solutions claimed in this invention. Through a complete process of municipal solid waste bag breaking, pretreatment sorting, multi-stage sorting, multi-stage crushing, composite modified pretreatment to suppress odor diffusion, microbial-membrane synergistic dehydration, and homogenization molding, combined with leachate recovery and exhaust gas purification, the product exhibits excellent performance in both core properties and storage stability. Example 3, due to its high organic content, sufficient amount of composite modified additives, and optimized microbial-membrane synergistic dehydration parameters, achieves optimal performance in all aspects. Although the parameters of Example 2 are at the lower limit of the claims, it fully executes all key steps and its performance is still far superior to the comparative example.

[0099] The comparative example did not employ composite modification pretreatment to suppress odor diffusion, microbial-membrane synergistic dehydration, or leachate and exhaust gas treatment steps, resulting in a product with low calorific value, high moisture content, excessive sulfur, chlorine, and heavy metal content, poor molding performance, and insufficient storage stability, failing to meet the requirements for industrial boiler combustion or gasification power generation. This demonstrates that the formulation innovation and process optimization of this invention have a significant synergistic effect, with each technical feature working together to effectively solve the problems of low calorific value, high pollutant content, and incomplete resource recovery in existing technologies for waste fuel, achieving the coordinated development of harmlessness, reduction, and resource utilization of municipal solid waste.

[0100] refer to Figure 2 The bar chart illustrates the differences in the net calorific value (NPV) of waste-derived fuels prepared using different processes. Examples 1-3, employing a comprehensive process of composite modification pretreatment to suppress odor diffusion and microbial-membrane synergistic dehydration, all exhibit significantly higher NPVs than the comparative examples. Example 3, benefiting from higher organic matter content, sufficient composite modification additives, and optimized parameters, achieves the highest NPV. The comparative examples, lacking core modification and drying / dehydration processes, have significantly lower NPVs, fully demonstrating that the process of this invention can effectively improve fuel energy density and meet industrial combustion requirements.

[0101] refer to Figure 3 The line graph illustrates the trend of fuel moisture content change during a 90-day storage period. Examples 1-3, having undergone composite modification pretreatment and homogenization molding, exhibited slow moisture content growth and excellent storage stability; Example 3 showed the best storage stability with the smallest moisture content change. The comparative examples, without modification or catalytic treatment, had a loose structure after molding, resulting in a rapid increase in moisture content and severe moisture absorption in the later stages of storage. This demonstrates that the process of this invention can significantly improve fuel storage stability and extend shelf life.

[0102] refer to Figure 4This radar chart comprehensively reflects the differences in overall performance among the fuel groups. Examples 1-3 all performed excellently in all five core performance dimensions, with scores no lower than 7.8 points in each dimension. Among them, Example 3 scored over 9 points in three key dimensions: lower heating value, bar compressive strength, and storage stability, demonstrating the best overall performance. The comparative examples generally scored below 5 points in each dimension, showing significant shortcomings in sulfur and chlorine content control and storage stability. The radar chart demonstrates the synergistic innovation effect of the process of this invention, achieving a comprehensive improvement in the overall performance of the fuel through full-process optimization, far exceeding the products prepared by traditional processes.

[0103] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pretreatment process for preparing new energy fuels from municipal solid waste in a county, characterized in that, Includes the following steps: S1. Household waste bag breaking: Collect household waste in the county and use a single-shaft high-speed bag breaking machine to break the bags; S2. Pre-processing and sorting: After the bags are broken, the household waste is separated into bulky waste and recyclables. The recyclables are sorted and recycled. S3. Multi-stage sorting: After separating bulky waste and recyclables, the waste is first separated from ferrous metals by an electromagnetic self-unloading iron remover; then it is screened by a drum screen to separate inorganic impurities; and then sent to a multi-stage airflow suspension classifier to separate lightweight plastic film, medium and heavy derivative fuel raw materials and heavy inorganic matter according to density. The lightweight plastic film is recycled and reused. S4. Multi-stage crushing: The medium and heavy derivative fuel raw materials after S3 treatment are crushed sequentially through a primary twin-shaft shear crusher and a secondary high-speed single-shaft crusher; S5. Composite Modification Pretreatment to Inhibit Odor Diffusion: By weight, add 8-15 parts of composite modification additive to the raw material after S4 two-stage crushing, mix evenly, and then turn and shovel at 25-35℃ for 30-60 minutes to effectively control the diffusion of odorous gases from the raw material pile; the composite modification additive includes 3-5 parts of biochar-based adsorbent, 1-2 parts of disodium EDTA, 0.5-1 parts of composite probiotic agent, 2-3 parts of calcium oxide, 1-2 parts of fly ash, and 0.5-1 parts of sodium lignosulfonate; S6. Microbial-membrane co-dehydration: The material treated by S5 is sent into the membrane biological drying channel, oxygen is introduced, and the fermentation time is 48 hours. During the fermentation, the material is turned over once every 2 hours. After the biological drying is completed, it is dehydrated by a squeeze dehydrator. S7. Homogenization molding: The composite modified and bio-dried material is fed into a two-roll extrusion molding machine with a molding pressure of 15-25MPa and a holding time of 10-20s to produce rod-shaped fuel with a particle size of 30-50mm. After molding, the fuel is naturally cooled to room temperature.

2. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, It also includes a leachate recovery and treatment step: collect the leachate generated during the S6 dehydration process, first filter it through a grid to remove suspended impurities, then send it to an anaerobic fermentation tank, add 5-8 parts of compound fermentation agent, and the biogas produced is desulfurized and dehydrated and purified, and used as an auxiliary energy source for S6 microbial-membrane co-dehydration. The fermented biogas residue is dried and then returned to S5 to be mixed with organic matter mixture. The biogas slurry is biochemically treated to meet the standards and then used by the plant.

3. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, It also includes exhaust gas purification and recovery steps: collecting exhaust gas from S1 municipal solid waste bag breaking, S5 composite modification pretreatment, and S6 microbial-membrane synergistic dehydration, first passing it through a scrubbing tower to remove particulate matter and acidic and alkaline substances, then sending it to an activated carbon adsorption tower to adsorb odor substances, and finally recovering carbon dioxide through a membrane separation device.

4. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The sorting equipment in S3 includes an infrared spectral sorter, an electromagnetic iron remover, an intelligent robotic arm, and an eddy current sorter. Recyclable materials include plastics, ferromagnetic metals, glass, paper, and non-ferrous metals.

5. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The biomass-based adsorbent in S5 is prepared by anaerobic carbonization of corn stalks at 400-500℃ for 2-3 hours, with a specific surface area ≥500m² / g and a pore size of 2-50nm; calcium oxide purity ≥90% and particle size ≤5μm; fly ash specific surface area ≥300m² / g; and sodium lignosulfonate molecular weight of 20000-50000Da.

6. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The S5 compound probiotic agent has a live bacteria count ≥10 9 The CFU / g ratio of live Bacillus subtilis, Saccharomyces cerevisiae, and lactic acid bacteria is 2:1:1, and the survival rate is ≥90% at 35-45℃.

7. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The screw speed of the S6 extrusion dewatering machine is 50-80 r / min, the filter screen aperture is 0.5-1 mm, the solid recovery rate of the dewatered material is ≥90%, and the leachate generation is ≤0.2 m³ / t of waste.

8. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The S6 medium-membrane biological drying channel uses an intelligent molecular membrane with expanded polytetrafluoroethylene composite membrane as its core material. The pore size is 0.025μm-10μm, the air permeability is 8-9m³ / (㎡·h), and it can withstand composting temperatures of 55-70℃ and above. The micropores can effectively block the spread of malodorous gases and pathogens.

9. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The roller surface temperature of the S7 twin-roll extrusion molding machine is 60-80℃. The compressive strength of the formed rod fuel is ≥1.5MPa, the water absorption rate is ≤10%, the bulk density is 800-1000kg / m³, and the lower heating value is ≥18MJ / kg.

10. The pretreatment process for preparing new energy fuels from county-level municipal solid waste according to claim 1, characterized in that, The waste reduction rate of the entire pretreatment process is ≥70%, the organic matter conversion rate is ≥85%, the sulfur content of the prepared rod fuel is ≤0.3%, the chlorine content is ≤0.5%, and the heavy metal content meets the requirements of GB / T31856-2015 standard.

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