Kitchen waste biogas liquid backflow device and energy negative carbonization process thereof

Abstract

This invention relates to a food waste biogas slurry recirculation device and its energy-negative carbonization process, including an intelligent control box, a biogas slurry treatment tank, an elastic brush-type drive mechanism, a dynamic recirculation system, and multi-stage wastewater treatment equipment. The device achieves dynamic optimization of process parameters through online detection of oil content and prediction using an LSTM model. It uses hydrolyzed acidified liquid as a denitrification carbon source and utilizes the waste heat from incineration flue gas to dry the biogas residue, thereby increasing the biogas production rate of the system and reducing dioxin emissions. This solves the technical problems of oil accumulation, high energy consumption, and secondary pollution in traditional processes.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a kitchen waste biogas slurry recirculation device and its energy negative carbonization process. Background Technology

[0002] How to improve biogas production rate and biogas quality, how to avoid secondary pollution of biogas slurry and biogas residue, how to improve the recycling rate of biogas slurry and biogas residue, and how to achieve near-zero emissions of biogas residue incineration power generation and biogas slurry? Through research on key technologies for integrated co-processing of kitchen waste and waste incineration, we can maximize the potential for energy utilization of kitchen waste, realize the shared treatment of kitchen waste anaerobic biogas water and landfill leachate, and achieve energy utilization of biogas residue through waste incineration power generation, thereby reducing input and treatment costs and achieving a win-win situation for economic and environmental benefits. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by using hydrolyzed acidified liquid as an external carbon source for wastewater treatment, and by implementing measures such as fermentation liquid and biogas slurry recirculation. This reduces the amount of biogas slurry to be treated, lowers treatment costs, increases the gas production and efficiency of the anaerobic digestion system, and achieves near-zero biogas slurry emissions in conjunction with municipal solid waste incineration power generation. This solves the technical problem that existing technologies cannot maximize the energy utilization of waste resources.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A food waste biogas slurry return device includes an intelligent control box. The right side of the intelligent control box is connected to a biogas slurry treatment tank. The upper end of the biogas slurry treatment tank is equipped with a drive mechanism, and the right side of the biogas slurry treatment tank is connected to a return mechanism. The right side of the return mechanism is connected to a sewage treatment device. The lower end of the sewage treatment device is connected to a return main pipe, and the other end of the return main pipe is connected to the biogas slurry treatment tank. The lower ends of both the biogas slurry treatment tank and the sewage treatment device are fixedly connected to the ground.

[0006] As a preferred embodiment, the intelligent control box includes a PLC control unit module, which is connected to an online oil content detection module and a reflux control module, which is connected to a reflux mechanism.

[0007] As a preferred embodiment, the reflux mechanism includes a main circulation pipe, one end of which is connected to the wastewater treatment equipment, and the other end is connected to a reflux lift pump. The left side of the reflux lift pump is fixedly connected to a biogas slurry treatment tank, and a reflux thin pipe is connected above the front end of the reflux lift pump. The upper end of the reflux thin pipe is connected to the biogas slurry treatment tank. One end of the main circulation pipe connected to the wastewater treatment equipment is connected to a corrugated expansion pipe, which can be extended to the four vertices of the wastewater treatment equipment. The lower end of the corrugated expansion pipe is connected to a sealing cap, which seals the connection to the wastewater treatment equipment.

[0008] As a preferred embodiment, the drive mechanism includes a reducer, an output shaft at the lower end of the reducer, a rotating shaft fixedly connected to the lower end of the output shaft, a protective cover fixedly connected to the lower end of the reducer, a biogas slurry treatment tank fixedly connected to the lower end of the protective cover, support columns fixedly connected to the left and right sides of the lower end of the rotating shaft, a spring fixedly connected to the other side of the support column, a fixed support block fixedly connected to the other side of the spring, three identical movable blocks movably connected to the fixed support block, a brush connecting block movably connected to the other end of the movable block, a brush fixing block fixedly connected to the brush fixing block, and brush bristles evenly fixedly connected to the brush fixing block on opposite sides.

[0009] As a preferred embodiment, a circular connecting block is fixedly connected to the lower end of the rotating shaft, and four stirring blades are evenly fixedly connected to the outer side of the circular connecting block. A filter screen is connected between each stirring blade, and a circulation chamber is provided at the lower end of the filter screen. The outer side of the stirring blade is embedded in and slidably connected to the inner wall of the biogas slurry treatment tank.

[0010] As a preferred embodiment, the wastewater treatment equipment includes a mounting frame, the lower end of which is fixedly connected to the mounting ground, and a filtration structure is fixedly connected to each of the four vertices of the upper end of the mounting frame. The filtration structure includes a C-shaped frame with its opening facing downwards, and two identical telescopic cylinders are fixedly connected to the inner side of the upper end of the C-shaped frame. The lower end of each telescopic cylinder is connected to a recovery valve, and the recovery valve is provided with sealing rubber strips on its left, right, and lower sides, and the outer side of the recovery valve is sealed to the treatment box.

[0011] As a preferred embodiment, the processing chamber includes uniformly distributed filter chambers, with filter screens installed at interconnected locations within each chamber. The filter screens are made of oleophobic glass fiber, and the porosity of each layer of the filter screen increases progressively from front to back, with the porosity of the frontmost filter screen being 90%. Each filter chamber has an identical sealing movable plate at its upper end, which is movably and sealingly connected to the processing chamber. A circular ring is fixedly connected to the center of each sealing movable plate, and a telescopic rod is fixedly connected to the upper end of the circular ring. An adjusting cylinder is connected to the upper end of the telescopic rod, and a bracket is fixedly connected to the upper end of the adjusting cylinder. Mounting brackets are fixedly connected to the lower ends of the left and right sides of the bracket.

[0012] A food waste biogas slurry recycling device and its energy-negative carbonization process include the following steps:

[0013] S1: The kitchen waste is treated with wet heat at a temperature of 85±5℃ for 40±10min and then transported to the anaerobic digester.

[0014] S2: Two-stage anaerobic fermentation is adopted: the pH of the primary acid-producing phase is controlled at 5.5±0.3, and the pH of the secondary methanogenic phase is controlled at 7.2±0.3;

[0015] S3: The biogas slurry is returned to the wastewater treatment equipment through the biogas slurry treatment tank, and the return ratio is dynamically adjusted;

[0016] S4: Waste heat from biogas residue is dried, and the waste gas from the incinerator at 120-150℃ is then co-incinerated with municipal solid waste at a mass ratio of 1:4±0.5.

[0017] As a preferred option, in step S3, a portion of the biogas slurry is diverted to the wastewater treatment equipment as a denitrification carbon source, with a dosage of COD:N=100:5±1. The remaining biogas slurry is co-treated with the leachate from domestic waste, using a combined UASB+MBR+NF process.

[0018] As another preferred option, the intelligent control box monitors the entire process in real time, and the monitoring data includes pH, ORP, VFA, and ammonia nitrogen data. It also predicts the gas production rate through an LSTM model and dynamically optimizes the process parameters.

[0019] The beneficial effects of this invention are:

[0020] (1) In this invention, by setting up intelligent biogas slurry reflux control and multi-stage separation technology, the energy conversion efficiency of kitchen waste treatment is significantly improved. The innovative closed-loop control system realizes accurate monitoring and dynamic adjustment of oil content, avoiding equipment blockage and system acidification problems caused by oil accumulation in traditional processes.

[0021] (2) In this invention, the synergistic design of cascade utilization of biogas carbon source and recovery of flue gas waste heat has achieved a breakthrough in the environmental friendliness of the treatment process. The dioxin emission value is stably controlled below 0.05 ng TEQ / m³, reaching the international advanced standard. The unique hydrolysis acidification liquid diversion technology and UASB+MBR+NF combined process have increased the biogas slurry reuse rate to 95%, truly achieving the environmental protection goal of "near-zero emissions".

[0022] (3) In this invention, the cost per ton of processing is reduced and the investment recovery period is shortened by sharing equipment and using energy in a tiered manner. The oil retention rate is improved by the progressively increasing porosity combination structure. The online oil content detector with an accuracy of ±0.5% and the variable frequency reflux pump achieve dynamic and precise adjustment of the reflux ratio of 15-30%. The stirring plate and filter screen, together with the elastic brush, play a good cleaning role on the inner wall of the biogas slurry treatment tank, preventing large particles of kitchen waste from sticking to the wall, extending the maintenance cycle and service life.

[0023] In summary, this equipment has the advantages of long service life, long maintenance cycle, reduced biogas slurry treatment volume, lower treatment cost, increased gas production and efficiency of anaerobic digestion system, and near-zero biogas slurry discharge, making it particularly suitable for the field of solid waste resource utilization technology. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the PLC control unit module connection in this invention.

[0027] Figure 3 This is a schematic diagram of the speed reducer in this invention.

[0028] Figure 4 This is a schematic diagram of the rotating shaft in this invention.

[0029] Figure 5 This is a schematic diagram of the processing box in this invention.

[0030] Figure 6 This is a schematic diagram of the filter screen in this invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0032] Example 1

[0033] like Figures 1 to 6 As shown, the present invention provides a kitchen waste biogas slurry return device, including an intelligent control box 1. The right side of the intelligent control box 1 is connected to a biogas slurry treatment tank 2. The upper end of the biogas slurry treatment tank 2 is provided with a drive mechanism 3, and the right side of the biogas slurry treatment tank 2 is connected to a return mechanism 4. The right side of the return mechanism 4 is connected to a sewage treatment device 5. The lower end of the sewage treatment device 5 is connected to a return main pipe 6, and the other end of the return main pipe 6 is connected to the biogas slurry treatment tank 2. The lower ends of both the biogas slurry treatment tank 2 and the sewage treatment device 5 are fixedly connected to the ground 10.

[0034] The integrated layout of the intelligent control box 1 and the biogas slurry treatment tank 2 shortens the pipeline distance, significantly reduces fluid resistance and improves energy efficiency. The closed-loop connection structure between the return main pipe 6 and the biogas slurry treatment tank 2 ensures the stability of biogas slurry return. The rotating filter assembly of the drive mechanism 3 increases the continuous operation time of the system. The entire equipment is fixedly installed on the ground 10 to form a rigid support system, which improves the vibration resistance by 3 times and effectively solves the sealing failure problem caused by long-term loosening of traditional equipment.

[0035] Furthermore, the intelligent control box 1 includes a PLC control unit module 11, which is connected to the online oil content detection module 12 and the reflux control module 13. The reflux control module 13 is connected to the reflux mechanism 4. The PLC control unit module 11 uses a high-performance PLC controller to collect and process sensor data in real time to ensure the stability of system operating parameters such as reflux ratio, pH value, and OR oil content. The PLC control unit module 11 receives real-time data from the online oil content detection module 12 and the reflux control module 13, calculates the optimal reflux ratio through preset logic, and outputs control signals to the reflux mechanism 4 to ensure stable operation of biogas slurry reflux.

[0036] The online oil content detection module 12 uses near-infrared spectroscopy with a detection accuracy of ±0.5%, avoiding the errors of traditional manual sampling and detection. It continuously monitors the oil content of biogas slurry to prevent oil accumulation from causing equipment blockage. The online oil content detection module 12 is installed on the biogas slurry return pipeline to detect the oil content in biogas slurry in real time and transmits the data to the PLC control unit module 11 as the basis for adjusting the return ratio.

[0037] The reflux control module 13 automatically adjusts the reflux ratio to 15%-30% based on the oil content and pH value parameters, thereby improving the anaerobic digestion efficiency, optimizing the operating frequency of the reflux pump, reducing energy consumption, and, combined with intelligent control, preventing the pipes from scaling due to the reflux of high-oil biogas slurry. The reflux control module 13 receives instructions from the PLC control unit module 11 to adjust the operating status of the reflux mechanism 4, such as the speed of the variable frequency reflux pump 42 and the valve opening, to ensure that the biogas slurry is refluxed back to the biogas slurry treatment tank 2 in the optimal ratio.

[0038] The modular design of the reflux mechanism 4 includes a main circulation pipe 41, a reflux booster pump 42, and a reflux capillary pipe 43, which facilitates maintenance and upgrades. The main circulation pipe 41 with a large diameter and wear-resistant materials are used to reduce grease deposition. The variable frequency reflux pump 42 can automatically adjust the flow rate according to system requirements to improve energy utilization. Under the control of PLC, the reflux mechanism 4 uses the reflux booster pump 42 to pump the biogas slurry from the sewage treatment equipment 5 back to the biogas slurry treatment tank 2. At the same time, some biogas slurry is finely refluxed through the reflux capillary pipe 43 to ensure stable system operation.

[0039] Furthermore, the reflux mechanism 4 includes a main circulation pipe 41, one end of which is connected to the wastewater treatment equipment 5, and the other end is connected to a reflux lift pump 42. The left side of the reflux lift pump 42 is fixedly connected to the biogas slurry treatment tank 2, and a reflux thin pipe 43 is connected above the front end of the reflux lift pump 42. The upper end of the reflux thin pipe 43 is connected to the biogas slurry treatment tank 2. A corrugated expansion pipe 96 is connected to one end of the main circulation pipe 41 connected to the wastewater treatment equipment 5. The corrugated expansion pipe 96 can be extended to the four vertices of the wastewater treatment equipment 5, and a sealing cap 97 is connected to the lower end of the corrugated expansion pipe 96. Cover 97 seals the connection to the sewage treatment equipment 5. The circulation main pipe 41 is made of large-diameter stainless steel, which has the advantage of reducing fluid resistance and preventing grease deposition. During operation, it serves as the main return channel, transporting the treated biogas slurry from the sewage treatment equipment 5 to the return lift pump 42. The return lift pump 42 is made of variable frequency explosion-proof pump body, which has the advantage of being able to precisely adjust the flow rate according to system requirements. During operation, it receives PLC control signals and transports the treated biogas slurry that meets the standards from the sewage treatment equipment 5 to the return lift pump 42. Its large-diameter design (DN150) can ensure a maximum flow rate of 50m³ / h.

[0040] The return lift pump 4 is a variable frequency explosion-proof centrifugal pump equipped with a mechanical seal system to ensure flow regulation accuracy. It allows solid particles with a diameter of ≤8mm to pass through. During operation, it receives control signals from the PLC and automatically adjusts the speed according to the COD value of the biogas slurry. The return capillary tube 43 is connected to the corrugated expansion tube 96. The lining of the return capillary tube 43 and the corrugated expansion tube 96 is coated with PTFE to prevent grease adhesion. Moreover, the 45° inclined installation avoids sedimentation. The corrugated expansion tube 96 adopts a multi-layer corrugated structure and is fixedly and sealed with the sealing cover 97, which facilitates precise docking with the filter chamber 91 of the sewage treatment equipment 5.

[0041] The sealing cover 97 has a built-in fluororubber sealing ring and a gas pressure detection sensor. During operation, it forms an airtight connection with the filter chamber 91 to prevent the leakage of biogas evaporation gas. Moreover, the upper end of the filter chamber 91 that is not connected to the corrugated expansion tube 96 is equipped with a fully sealed cover. The material is the same as the sealing cover 97, and it can be adapted to each filter chamber 91, with a good sealing effect.

[0042] Furthermore, the drive mechanism 3 includes a reducer 31, with an output shaft at its lower end. A rotating shaft 32 is fixedly connected to the lower end of the output shaft. A protective cover 33 is fixedly connected to the lower end of the reducer 31, and a biogas slurry treatment tank 2 is fixedly connected to the lower end of the protective cover 33. Support columns 34 are fixedly connected to the left and right sides of the lower end of the rotating shaft 32. A spring 35 is fixedly connected to the other side of the support column 34. A fixed support block 36 is fixedly connected to the other side of the spring 35. Three identical movable blocks 37 are movably connected to the fixed support block 36. A brush connecting block 38 is movably connected to the other end of each movable block 37. The brush connecting block 38 is fixedly connected to a brush fixing block. Block 39, the brush fixing blocks 39 are evenly fixed to the brush bristles 40 on one side away from each other, the reducer 31 adopts a helical gear reduction structure, the transmission efficiency is over 95%, the noise is less than 65dB, it receives the motor power and reduces the speed to 15-20rpm, and transmits the torque to the rotating shaft 32 through the output shaft. The rotating shaft is made of 40CrNiMoA alloy steel, with a torsional strength ≥800MPa, and rotates at a uniform speed inside the protective cover 33, driving all the actuators connected to the lower end. The protective cover 33 adopts a 304 stainless steel sealed structure, with a protection level of IP65, which can isolate external corrosive gases and prevent biogas slurry splashing and damaging the reduction mechanism;

[0043] The combined elastic support of the support column 34 and spring 35 allows for a radial float of ±5mm, automatically compensating for tank roundness errors during rotation and maintaining constant contact pressure on the brush bristles 40. The movable block 37 and brush connecting block 38 have a ball joint structure with a free swing angle of ±15°, allowing the brush bristles 40 to adapt to changes in the inner wall curvature of the tank. The brush fixing block 39 and brush bristles 40 are made of nylon bristles, which are heat resistant to 120℃ and continuously scrape away tank wall deposits with a contact pressure of 8-12N. The elastic support system reduces the wear rate of the brush bristles and extends their service life. The multi-degree-of-freedom movable connection structure ensures high tank wall cleaning coverage, and the low-speed design reduces biogas slurry disturbance and improves gas production stability.

[0044] Furthermore, a circular connecting block 7 is fixedly connected to the lower end of the rotating shaft 32. Four stirring blades 71 are evenly fixedly connected to the outer side of the circular connecting block 7. A filter screen 72 is connected between each stirring blade 71. A circulation chamber 73 is provided at the lower end of the filter screen 72. The outer side of the stirring blades 71 is embedded in and slidably connected to the inner wall of the biogas slurry treatment tank 2. The rotating shaft 32 is made of 40CrNiMoA alloy steel with a torsional strength ≥800MPa. It is driven by a reducer 31 to rotate at a uniform speed of 15-20rpm, transmitting power to the actuator. The circular connecting block 7 is made of 316L stainless steel and is integrally cast with a dynamic balance accuracy of G6.3. As a core connecting component, it connects the rotating shaft 32 to the biogas slurry treatment tank 2. The torque of shaft 32 is evenly distributed to four stirring blades 71. The stirring blades 71 have a fan-shaped structure with tungsten carbide wear-resistant strips embedded at their leading edges. They agitate the biogas slurry at a linear velocity of 2.5-3.0 m / s while scraping off sediment from the tank wall. The filter screen 72 has a gradient pore design with an uppermost pore size of 80 mesh and a lowermost pore size of 100 mesh. During rotation, it achieves dynamic solid-liquid separation, and large particles are intercepted on the screen surface. The circulation chamber 73 has a conical structure with an inclination angle of 45±2°. It collects the filtered biogas slurry and achieves forced circulation through the bottom opening. The symmetrical layout of the four stirring blades 71 improves the uniformity of the flow field and enhances the efficiency of anaerobic reaction. The dynamic filtration design increases the solids retention rate and extends the filter screen cleaning cycle.

[0045] Furthermore, the wastewater treatment equipment 5 includes a mounting frame 51. The lower end of the mounting frame 51 is fixedly connected to the mounting ground 10, and the four vertices of the upper end of the mounting frame 51 are all fixedly connected to the filtration treatment structure 8. The filtration treatment structure 8 includes a C-shaped frame 81 with its opening facing downwards. Two identical telescopic cylinders 82 are fixedly connected to the inner side of the upper end of the C-shaped frame 81. The lower end of the telescopic cylinders 82 is connected to a recovery valve 83. The recovery valve 83 is provided with sealing rubber strips on its left, right, and lower sides, and the outer side of the recovery valve 83 is sealed to the treatment box 9. The mounting frame 51 adopts a Q355B steel welded frame structure with hot-dip galvanized surface treatment, which has excellent corrosion resistance and a load-bearing capacity of more than 5 tons, providing stable support for the entire equipment and ensuring that each component remains aligned under vibration.

[0046] The filter treatment structure 8 can be independently disassembled and maintained without affecting system operation. During operation, it can be quickly connected to the treatment box 9 via the C-frame 81. The C-frame 81 is made of special stainless steel and is formed by one-time stamping. The opening angle is 120±2°, which ensures the sealing pressure while allowing an installation error of ±3mm. It is the mounting base for the pneumatic actuator. The telescopic cylinder 82 is a double-acting hydraulic buffer cylinder with a stroke of 150mm and high repeatability. It drives the recovery valve 83 to complete the opening and closing action with a pressure of 0.6MPa. The recovery valve 83 is a hard-seal triple eccentric butterfly valve with a leakage level of ANSVI / FCI 70-2 Class VI. It has a long service life and can achieve rapid opening and closing in 0.5 seconds under cylinder drive.

[0047] The sealing rubber strip is made of fluororubber with a Shore hardness of 75±5, can withstand high temperatures of 200℃, and has an oil resistance of ΔV<5%, forming a triple sealing line to ensure no leakage. The treatment tank has a wall thickness of 12mm, a pressure resistance of 0.8MPa, and a 2mm thick PTFE anti-corrosion layer, completing the functions of solid-liquid separation and grease recovery. The modular filter unit improves the system's capacity expansion and reduces maintenance downtime. The hard-seal valve structure ensures a low leakage rate, meeting chemical-grade sealing standards. The hydraulic buffer cylinder reduces the impact of valve operation and extends the equipment's lifespan.

[0048] Furthermore, the processing chamber 9 includes uniformly distributed filter chambers 91, with filter screens 92 arranged at interconnected positions within each chamber. The filter screens 92 are made of oleophobic glass fiber, and the porosity of each layer of the filter screen 92 increases progressively from front to back, with the porosity of the frontmost filter screen 92 reaching 90%. Each filter chamber 91 has an identical sealing movable plate 93 at its upper end. The sealing movable plate 93 is movably and sealingly connected to the processing chamber 9, and a ring is fixedly connected to the center of the sealing movable plate 93. A telescopic rod is fixedly connected to the upper end of the ring, and an adjusting cylinder 94 is connected to the upper end of the telescopic rod. The upper end of the throttle cylinder 94 is fixedly connected to the bracket 95, and the lower ends of the bracket 95 are fixedly connected to the mounting bracket 6. The filter chamber 91 adopts a 316L stainless steel split design with a single chamber volume of 0.5m³. Its advantage lies in its modular structure, which facilitates independent maintenance and replacement. During operation, it achieves gradient filtration of biogas slurry. The front section intercepts large particles of impurities, and the rear section completes fine separation. The filter screen 92 is made of oleophobic glass fiber material with a porosity gradient change of 90%→80%→70%. This reduces the oil adsorption rate and maintains a stable flux, forming a three-stage filtration barrier to remove solid particles of different sizes in sequence.

[0049] The sealing movable plate 93 features a quick-release structure with a fluororubber sealing ring, an opening pressure of 0.4MPa, and one-button opening and closing via cylinder control, ensuring the sealing of the filter chamber. The adjusting cylinder 94 is a servo electric cylinder with a stroke of 300mm and a positioning accuracy of ±0.05mm, precisely controlling the opening and closing angle of the movable plate. The bracket 95 uses a Q355B steel welded frame with a static load capacity of 3 tons and a natural frequency >50Hz to avoid resonance, providing rigid support for the entire filtration system. The gradient filtration design improves the SS removal rate and extends the filter screen's service life. The quick-release sealing structure improves maintenance efficiency. The modular chamber layout allows for flexible expansion of processing capacity and reduces expansion costs. The fully automatic control system enables unattended operation, reducing labor costs. The oleophobic filter screen ensures high purity of recovered grease.

[0050] A food waste biogas slurry recycling device and its energy-negative carbonization process include the following steps:

[0051] S1: The kitchen waste is treated with wet heat at a temperature of 85±5℃ for 40±10min and then transported to the anaerobic fermentation tank. Precise temperature control improves the oil separation rate and kills pathogenic microorganisms. The kitchen waste is then conveyed into the wet heat reactor via a screw conveyor and the oil liquefaction and separation are completed in a saturated steam environment.

[0052] S2: Two-stage anaerobic fermentation is adopted: the pH of the primary acid-producing phase is controlled at 5.5±0.3, and the pH of the secondary methanogenic phase is controlled at 7.2±0.3. The phase separation technology improves the methanogenic efficiency. The primary reactor completes hydrolysis and acidification, and the secondary reactor maintains the optimal methanogenic environment through an automatic pH adjustment system.

[0053] S3: The biogas slurry is returned to the sewage treatment equipment 5 through the biogas slurry treatment tank 2. The return ratio is dynamically adjusted. The dynamic control based on the LSTM model improves the stability of the system. Online sensors monitor parameters such as VFA and ammonia nitrogen in real time, and the PLC automatically adjusts the return ratio.

[0054] S4: Waste heat drying of biogas residue. After the flue gas from the incinerator is heated to 120-150℃, it is co-incinerated with domestic waste at a mass ratio of 1:4±0.5. The utilization of waste heat from the flue gas reduces the energy consumption of drying. The dried biogas residue is mixed with domestic waste through the feeding system and fully burned in the furnace at a temperature above 850℃.

[0055] The innovative wet heat-anaerobic-incineration coupled process improves energy recovery rate, the dynamic intelligent control system keeps gas production fluctuation within ±3%, dioxin emission concentration is stabilized in the range of 0.038-0.042 ngTEQ / m³, the biogas slurry reuse rate is high, and near-zero wastewater discharge is achieved. It is the first time that energy and mass coupling of anaerobic digestion and incineration processes has been realized.

[0056] Furthermore, in step S3, a portion of the biogas slurry is diverted to wastewater treatment equipment 5 as a denitrification carbon source, with a dosage of COD:N = 100:5±1. The remaining biogas slurry is co-treated with leachate from municipal solid waste using a UASB+MBR+NF combined process. An online COD / N monitor is used to achieve precise control of the carbon-to-nitrogen ratio, with an error range of ±2%. Based on real-time monitoring data, an electric regulating valve automatically distributes the biogas slurry flow, diverting 20-30% to wastewater treatment equipment 5. The denitrification carbon source is added in a hydrolyzed acidified liquid rich in VFA. It has high bioavailability. When added to the anoxic tank at a ratio of COD:N=100:5±1, the denitrification rate is increased to 0.35kgN / (m³·d). The UASB-MBR-NF three-stage combination makes the effluent COD<50mg / L. The remaining biogas slurry is mixed with leachate and then passed through the UASB reactor in sequence. The HRT=24h, OLR=8kgCOD / (m³·d), the MBR membrane system flux is 15LMH, the pump-stop ratio is 8:2, and the NF nanofiltration unit has a molecular weight cutoff of 200Da.

[0057] Furthermore, the intelligent control box 1 provides real-time monitoring throughout the entire process, including data on pH, ORP, VFA, and ammonia nitrogen. It predicts gas production using an LSTM model, dynamically optimizes process parameters, and employs industrial-grade sensors with pH detection accuracy of ±0.1, ORP resolution of 1mV, VFA detection error of <5%, and ammonia nitrogen detection range of 0-500mg / L. Based on the LSTM neural network model, the gas production prediction accuracy is ≥95%, and it can provide early warning of abnormal operating conditions up to 6 hours in advance. It also adjusts parameters such as reflux ratio and stirring frequency in real time to improve the stability of the anaerobic system.

[0058] Working process: First, the kitchen waste enters the wet heat treatment system and is treated at 85±5℃ for 40±10 minutes to achieve oil separation and pathogen inactivation. The pretreated material is then transported to a two-stage anaerobic fermentation system. The first-stage acid-producing phase is controlled at pH 5.5±0.3, and the second-stage methanogenic phase is controlled at pH 7.2±0.3, completing the degradation of organic matter and biogas production. The intelligent control system monitors the biogas slurry parameters in real time, predicts the biogas production using an LSTM model, and dynamically adjusts 15-30% of the biogas slurry to be returned to the acid-producing phase. The remaining biogas slurry is used as carbon. The source is used for wastewater treatment, and part of it is co-treated with leachate. It adopts a UASB+MBR+NF combined process. The biogas residue is dried using the waste heat of flue gas at 120-150℃ in the incinerator. After controlling the moisture content to ≤30%, it is co-incinerated with domestic waste at a ratio of 1:4±0.5. The incineration system is equipped with a secondary air injection device with an air velocity of 22±2m / s. With 10-15% flue gas recirculation, it ensures that dioxin emissions are <0.05ngTEQ / m³. The entire process is controlled in a closed loop by PLC, and the operation data of each link is uploaded to the central monitoring system.

[0059] In the description of this invention, it should be understood that the terms "front and back", "left and right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0060] Of course, those skilled in the art should understand that the term "a" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple. The term "a" should not be understood as a limitation on the quantity.

[0061] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art under the technical guidance of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A food waste biogas slurry recirculation device, characterized in that: The system includes an intelligent control box (1), with a biogas slurry treatment tank (2) connected to the right side of the intelligent control box (1). The biogas slurry treatment tank (2) is equipped with a drive mechanism (3) at the upper end, and a return mechanism (4) is connected to the right side of the biogas slurry treatment tank (2). The wastewater treatment equipment (5) is connected to the right side of the return mechanism (4). The wastewater treatment equipment (5) is connected to the return main pipe (6) at the lower end, and the other end of the return main pipe (6) is connected to the biogas slurry treatment tank (2). The lower ends of the biogas slurry treatment tank (2) and the wastewater treatment equipment (5) are both fixedly connected to the installation ground (10).

2. The kitchen waste biogas slurry recirculation device according to claim 1, characterized in that, The intelligent control box (1) includes a PLC control unit module (11), which is connected to an online oil content detection module (12) and a return flow control module (13), which is connected to a return flow mechanism (4).

3. The kitchen waste biogas slurry recirculation device according to claim 1, characterized in that, The reflux mechanism (4) includes a circulation main pipe (41), one end of which is connected to the sewage treatment equipment (5), and the other end is connected to the reflux lift pump (42). The left side of the reflux lift pump (42) is fixedly connected to the biogas slurry treatment tank (2), and the front end of the reflux lift pump (42) is connected to the reflux thin pipe (43). The upper end of the reflux thin pipe (43) is connected to the biogas slurry treatment tank (2). One end of the circulation main pipe (41) connected to the sewage treatment equipment (5) is connected to a corrugated expansion pipe (96). The corrugated expansion pipe (96) can be stretched to the four vertices of the sewage treatment equipment (5), and the lower end of the corrugated expansion pipe (96) is connected to a sealing cap (97). The sealing cap (97) seals the connection to the sewage treatment equipment (5).

4. The kitchen waste biogas slurry recirculation device according to claim 1, characterized in that, The drive mechanism (3) includes a reducer (31), the lower end of the reducer (31) is provided with an output shaft, the lower end of the output shaft is fixedly connected to a rotating shaft (32), the lower end of the reducer (31) is fixedly connected to a protective cover (33), the lower end of the protective cover (33) is fixedly connected to a biogas slurry treatment tank (2), the lower end of the rotating shaft (32) is fixedly connected to a support column (34) on the left and right sides, the other side of the support column (34) is fixedly connected to a spring (35), the other side of the spring (35) is fixedly connected to a fixed support block (36), the fixed support block (36) is movably connected to three identical movable blocks (37), the other end of the movable block (37) is movably connected to a brush connecting block (38), the brush connecting block (38) is fixedly connected to a brush fixing block (39), and the brush fixing blocks (39) are evenly fixedly connected to bristles (40) on one side away from each other.

5. The kitchen waste biogas slurry recirculation device according to claim 4, characterized in that, The lower end of the rotating shaft (32) is fixedly connected to a circular connecting block (7), and four stirring blades (71) are evenly fixedly connected to the outer side of the circular connecting block (7). A filter screen (72) is connected between each stirring blade (71), and a circulation chamber (73) is provided at the lower end of the filter screen (72). The outer side of the stirring blade (71) is embedded in the inner wall of the biogas slurry treatment tank (2).

6. The kitchen waste biogas liquid reflux device according to claim 1, characterized in that, The wastewater treatment equipment (5) includes a mounting frame (51), the lower end of which is fixedly connected to the mounting ground (10), and the four vertices of the upper end of the mounting frame (51) are all fixedly connected to a filter treatment structure (8). The filter treatment structure (8) includes a C-shaped frame (81), the opening of the C-shaped frame (81) is downward, and two identical telescopic cylinders (82) are fixedly connected to the inner side of the upper end of the C-shaped frame (81). The lower end of the telescopic cylinder (82) is connected to a recovery valve (83). The recovery valve (83) is provided with sealing rubber strips on the left, right and lower sides, and the outer side of the recovery valve (83) is sealed to the treatment box (9).

7. The kitchen waste biogas liquid reflux device according to claim 6, characterized in that, The processing box (9) includes uniformly distributed filter chambers (91). The filter chambers (91) are connected to each other and are provided with filter screens (92). The filter screens (92) are made of oleophobic glass fiber material, and the porosity of each layer of the filter screens (92) increases from front to back. The porosity of the frontmost filter screen (92) is 90%. The upper end of each filter chamber (91) is provided with the same sealing movable plate (93). The sealing movable plate (93) is connected to the processing box (9) in a sealed and movable manner. The center of the sealing movable plate (93) is fixedly connected to a ring. The upper end of the ring is fixedly connected to a telescopic rod. The upper end of the telescopic rod is connected to an adjusting cylinder (94). The upper end of the adjusting cylinder (94) is fixedly connected to a bracket (95). The lower ends of the left and right sides of the bracket (95) are fixedly connected to mounting brackets (6).

8. The energy-negative carbonization process of a kitchen waste biogas slurry recirculation device according to any one of claims 1-7, characterized in that, Includes the following steps: S1: The kitchen waste is treated with wet heat at a temperature of 85±5℃ for 40±10min and then transported to the anaerobic digester. S2: Two-stage anaerobic fermentation is adopted: the pH of the primary acid-producing phase is controlled at 5.5±0.3, and the pH of the secondary methanogenic phase is controlled at 7.2±0.3; S3: The biogas slurry is returned to the sewage treatment equipment (5) through the biogas slurry treatment tank (2), and the return ratio is dynamically adjusted; S4: Waste heat from biogas residue is dried, and the waste gas from the incinerator at 120-150℃ is then co-incinerated with municipal solid waste at a mass ratio of 1:4±0.

5.

9. The kitchen waste biogas slurry recirculation device and its energy-negative carbonization process according to claim 8, characterized in that, In step S3, a portion of the biogas slurry is diverted to the wastewater treatment equipment (5) as a denitrification carbon source, with an addition amount of COD:N=100:5±1. The remaining biogas slurry is treated in conjunction with the leachate from domestic waste, using a combined UASB+MBR+NF process.

10. The kitchen waste biogas slurry recirculation device and its energy-negative carbonization process according to claim 8, characterized in that, The intelligent control box (1) monitors the entire process in real time. The monitoring data includes pH, ORP, VFA, and ammonia nitrogen data. The gas production is predicted by the LSTM model, and the process parameters are dynamically optimized.

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