A medium-concentration anaerobic treatment device for a kitchen waste fermentation system and a method of using the same
By combining a spiral mixer and an online detector with a PLC controller, the problem of uneven mixing in medium-concentration anaerobic treatment was solved, achieving efficient anaerobic reaction of kitchen waste, increasing gas production rate and digestate concentration, and reducing wastewater generation and energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 中核第七研究设计院有限公司
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-09
Smart Images
Figure CN122168401A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of food waste treatment technology, and in particular to a medium-concentration anaerobic treatment device for a food waste fermentation system and its usage method. Background Technology
[0002] Currently, anaerobic fermentation technology is commonly used for the treatment of food waste. Anaerobic technology includes two types: wet and dry.
[0003] Building upon anaerobic digestion technology for food waste, many large environmental protection companies have introduced low-concentration anaerobic technology and equipment tailored to their specific needs, but these are primarily focused on low concentration. To develop medium-concentration anaerobic digestion, industry professionals have also conducted related research, primarily addressing the flow pattern and mixing issues of the slurry within the tank. Studies have explored hydraulic mixing and biogas mixing in anaerobic reactors. While these methods can achieve rapid local mixing at the feed front, they suffer from uneven vertical material and temperature distribution within the reactor, resulting in localized mixing without a standardized flow pattern. Furthermore, hydraulic mixing introduces a large amount of circulating water, diluting the digestate and affecting the gas production rate, while also generating significant amounts of high-concentration wastewater, leading to poor slurry mixing. Some researchers have proposed installing a mixing device in the bottom reaction zone of the medium-concentration anaerobic reactor and using an external circulation pump to return the slurry to the top. However, engineering tests have shown that this mixing method does not achieve good uniformity; the temperature and slurry concentration within the tank vary significantly at different heights and cross-sections, and the material is prone to short-circuiting and uneven concentration within the reactor, resulting in unsatisfactory engineering application results. Some industry professionals have also studied dry anaerobic processes and proposed a mixed dry waste dry anaerobic fermentation treatment system. This technology is suitable for kitchen waste with high solids content. However, this method is not applicable to the characteristics of kitchen waste in China.
[0004] In summary, low-concentration anaerobic processes are currently the primary method, while medium-concentration anaerobic technology is still in the research stage. Many experts are studying medium-concentration anaerobic processes and mixing methods, attempting to develop an efficient mixing facility, but none of these efforts have been entirely satisfactory, failing to achieve overall mixing and uniform flow. Therefore, a solution is urgently needed. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a medium-concentration anaerobic treatment device for a food waste fermentation system and its usage method. The device can continuously feed and discharge, and the concentration of the feed slurry is controlled at a solid content of about 12%. After 15 days of full anaerobic reaction, the concentration of the digestate in the tank can reach about 8% through the anaerobic device and stirring method of this process, thus realizing medium-concentration anaerobic fermentation.
[0006] To achieve the aforementioned objective, the technical solution of the present invention is as follows: a medium-concentration anaerobic treatment device for a food waste fermentation system and its method of use, comprising a reactor cylinder, a stirrer, and a drive unit; the reactor cylinder is provided with a cavity for providing food waste slurry for anaerobic reaction; the drive unit is connected to the stirrer arranged in the cavity and drives the stirrer to rotate, and the rotating stirrer is used to drive the slurry in the cavity to flow from the bottom to the top of the cavity.
[0007] Preferably, it also includes a heating unit, which is disposed on the reactor cylinder and is used to heat the slurry inside the reactor cylinder.
[0008] Preferably, it also includes an online monitoring instrument, which is installed inside the reactor cylinder and used to monitor the pH value, temperature and biogas production rate of the slurry inside the reactor cylinder cavity in real time.
[0009] Preferably, the agitator includes a spiral cylinder and a spiral stirrer; the spiral cylinder is vertically installed in the cavity of the reactor cylinder and is fitted onto the spiral stirrer; the top end of the spiral stirrer is connected to the drive shaft.
[0010] Preferably, the spiral agitator is provided with spiral blades; the spiral blades are right-handed spirals with equal pitch, and the ratio of the diameter of the reactor cylinder to the diameter of the spiral shaft is 20:1.
[0011] Preferably, it also includes connecting rods; one end of the connecting rod is connected to the outer wall of the spiral cylinder, and the other end is connected to the inner wall of the reactor cylinder cavity, and there are multiple connecting rods, which are evenly distributed along the circumferential and vertical directions of the spiral cylinder.
[0012] Preferably, the drive unit includes a stirring motor and a PLC controller; the stirring motor is a variable frequency motor and is electrically connected to the PLC controller.
[0013] Preferably, it also includes a drain valve; the bottom of the reactor cylinder cavity is set as a cone, and the bottom of the spiral cylinder extends into the cone at the bottom of the reactor cylinder cavity; the drain valve is located at the bottom of the reactor cylinder.
[0014] Preferably, it also includes a computer; the computer is electrically connected to the heating unit, the online detector, and the PLC controller.
[0015] Preferably, the method of using the above-mentioned medium-concentration anaerobic treatment device for a food waste fermentation system includes the following steps: 1) The kitchen waste is pre-treated to form kitchen waste slurry, and the kitchen waste slurry is pumped into the cavity of the reactor cylinder; 2) The computer starts the stirring motor, and the spiral stirrer rotates to lift the slurry at the bottom of the spiral barrel to the top of the spiral barrel, and flows out from the top of the spiral barrel, forming a circulation flow from bottom to top in the cavity of the reactor barrel; 3) The online detector detects the temperature of the slurry inside the reactor cylinder cavity and transmits the temperature information to the computer for data analysis. If the computer determines that the detected temperature is lower than the temperature required for the slurry inside the reactor cylinder cavity to undergo anaerobic reaction, it turns on the heating unit. The heating unit heats the outer wall of the reactor cylinder and controls the PLC controller to increase the operating power of the stirring motor. The spiral stirrer accelerates the stirring of the slurry until the online detector detects that the temperature of the slurry in multiple places inside the reactor cylinder meets the temperature required for anaerobic reaction, at which point the heating unit is turned off. 4) The online detector detects the pH of the slurry at different locations within the reactor cylinder cavity and transmits the detected pH values to the computer for data analysis. The computer determines that the pH values of the slurry at different locations within the reactor cylinder are different. The computer then controls the PLC controller to increase the operating power of the stirring motor and accelerate the stirring of the slurry with the spiral stirrer until the online detector detects that the pH values of the slurry at different locations within the reactor cylinder cavity are the same, at which point the rated operating power is restored. 5) The online detector detects the gas flow rate at the exhaust port of reactor cylinder 11 and transmits the detected gas flow rate to the computer for data analysis. The computer determines that the gas flow rate at the exhaust port of reactor cylinder has decreased, and the computer controls the PLC controller to increase the operating power of the stirring motor and the spiral stirrer to accelerate the stirring of the slurry until the online detector detects that the gas flow rate at the exhaust port of reactor cylinder 11 has reached the standard flow rate, at which point the rated operating power is restored.
[0016] The beneficial effects of this invention are: (1) The device provided by the present invention is an anaerobic reactor. The outer side of the stirring spiral shaft in the reactor is surrounded by a spiral cylinder, and the conveying shaft is placed inside the spiral cylinder. When it is running, the flow state of the slurry in the tank is forcibly divided. From the perspective of the flow state space, the inner side of the spiral cylinder is the rising zone and the outer side of the spiral cylinder is the falling zone, and the slurry is circulated in a large manner. The stirrer in the reactor can realize the whole-body stirring of the tank from top to bottom. During the stirring process, the slurry is forcibly raised and lowered. The flow state in the tank is upward in the middle and downward around the periphery, so as to achieve overall mixing and regular flow state, and can achieve good stirring effect.
[0017] (2) The present invention sets up a heating part outside the device and an online detector inside the device. The computer adjusts the operating power of the stirring motor by using the PLC controller based on the information such as the temperature, pH and gas flow rate of the slurry detected by the online detector. This adjusts the stirring speed of the slurry inside the anaerobic reactor and the speed of slurry circulation. This allows for rapid adjustment of the temperature and pH of the slurry, achieving precise regulation of the anaerobic reaction, making the entire anaerobic reaction more complete and improving the reaction efficiency.
[0018] (3) The device provided by the present invention can improve the main process control parameters. Its anaerobic feed concentration can reach 11-12%, and the digestion concentration in the reaction can reach 7%-8%. Compared with the conventional 2-3%, it is 5% higher, realizing the medium-concentration anaerobic reaction condition. The maximum value of biogas production rate (in VS) in the experimental stage is 0.95 m3 / kgVS. The biogas production per ton of kitchen waste is close to 100m3, which is higher than the technical index of conventional biogas production of 70m3. The treatment efficiency of the anaerobic digestion system can be increased by 40%, the amount of high-concentration wastewater generated per ton of kitchen waste can be reduced by 20%, the one-time construction investment can be reduced by 20%, and the energy consumption of the heating system can be reduced by 20%. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the structure of the present invention.
[0021] Figure labels and descriptions: 11. Reactor shell; 12. Conical body; 13. Connecting rod; 14. First drain valve; 15. Second drain valve; 16. Third drain valve; 21. Spiral cylinder; 22. Spiral agitator; 23. Spiral blades; 31. Agitator motor; 32. Mounting frame. Detailed Implementation
[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] Example 1 See Figure 1 As shown: The present invention provides a medium-concentration anaerobic treatment device for a food waste fermentation system and its usage method, including a reactor cylinder 11, a stirrer and a drive unit; the reactor cylinder 11 is provided with a cavity for providing food waste slurry for anaerobic reaction; the drive unit is connected to the stirrer arranged in the cavity and drives the stirrer to rotate, and the rotating stirrer is used to drive the slurry in the cavity to flow from the bottom to the top of the cavity.
[0024] It also includes a heating unit, which is installed on the reactor shell 11 and is used to heat the slurry inside the reactor shell 11. The heating unit is generally selected as electric heating, and electric heating wires are provided on the outer wall of the reactor shell 11.
[0025] It also includes online monitoring instruments, installed inside the reactor body 11, for real-time monitoring of the pH value, temperature, and biogas production rate of the slurry within the reactor body 11 cavity. The online monitoring instruments include an electronic pH online monitor, an electronic temperature monitor, and a gas flow meter. Multiple electronic pH and electronic temperature monitors are present, each positioned at a different location within the reactor body 11 cavity. The gas flow meter is located at the exhaust port of the reactor body 11.
[0026] The agitator includes a spiral barrel 21 and a spiral stirrer 22; the spiral barrel 21 is vertically installed in the cavity of the reactor body 11, and the spiral barrel 21 is fitted onto the spiral stirrer 22; the top end of the spiral stirrer 22 is connected to the drive shaft.
[0027] The spiral stirrer 22 is equipped with spiral blades 23; the spiral blades 23 adopt right-handed generatrix equal pitch spiral.
[0028] In practical applications, with 50m 3 Taking the reactor cylinder 11 as an example, the spiral conveying height of the spiral agitator 22 is H=5200~5500mm, the spiral shaft diameter D1=200~250mm, the outer diameter of the spiral cylinder D2=600~650mm, the screw pitch is 520~550mm, the effective working screw pitch number Z=10~15, and the ratio of the reactor cylinder diameter to the spiral shaft diameter is 20:1~25:1.
[0029] It also includes connecting rods 13; one end of the connecting rod 13 is connected to the outer wall of the spiral cylinder 21, and the other end is connected to the inner wall of the cavity of the reactor cylinder 11. There are multiple connecting rods 13, which are evenly distributed along the circumferential and vertical directions of the spiral cylinder 21 to ensure that the spiral cylinder 21 can remain stable during operation.
[0030] The drive unit includes a stirring motor 31, a mounting bracket 32, and a PLC controller; the stirring motor 31 is a variable frequency motor and is electrically connected to the PLC controller. The mounting bracket 32 is located at the top of the reactor shell 11, and the stirring motor 31 is mounted on the mounting bracket 32.
[0031] It also includes a drain valve; the bottom of the cavity of the reactor shell 11 is set as a cone 12, and the included angle of the inclined surface of the cone 12 is 37.5 degrees. The bottom of the spiral drum 21 extends to the region of the cone 12 at the bottom of the cavity of the reactor shell 11, so that the slurry accumulated in the cone 12 can be continuously transported to the top of the spiral drum 21; the drain valve is set at the bottom of the reactor shell 11. The drain valve is set on the drain pipe communicating with the cone 12, and the drain valve includes a first drain valve 14, a second drain valve 15 and a third drain valve 16; the cone 12 facilitates the smooth discharge of the slurry after the anaerobic reaction is completed, and the three valves prevent the slurry from leaking from the bottom of the reactor shell 11 during the reaction, thereby improving the stability of the equipment operation.
[0032] It also includes a computer; the computer is electrically connected to the heating unit, the online detector and the PLC controller.
[0033] Example 2 A method for using a medium-concentration anaerobic treatment device for a food waste fermentation system. In practical applications, the main process control parameters of the medium-concentration anaerobic treatment device are as follows: anaerobic feed solid content 10-12%, digestion concentration during reaction can reach 7%-8%, residence time 15-20 days, mesophilic anaerobic temperature 35-37℃, and pH value 7-8.
[0034] The method includes the following steps: 1) The kitchen waste is pre-treated to form kitchen waste slurry, and the kitchen waste slurry is pumped into the cavity of the reactor cylinder 11; 2) The computer starts the stirring motor 31, and the spiral stirrer 22 rotates to lift the slurry at the bottom of the spiral barrel 21 to the top of the spiral barrel 21, and flows out from the top of the spiral barrel 21, forming a circulation flow from bottom to top in the cavity of the reactor barrel 11; 3) The online detector detects the temperature of the slurry inside the cavity of the reactor shell 11 and transmits the temperature information to the computer for data analysis. If the computer determines that the detected temperature is lower than the temperature required for the slurry inside the cavity of the reactor shell 11 to carry out anaerobic reaction, the heating unit is turned on. The heating unit heats the outer wall of the reactor shell 11 and controls the PLC controller to increase the operating power of the stirring motor 31. The spiral stirrer 22 accelerates the stirring of the slurry until the online detector detects that the temperature of the slurry in multiple places inside the reactor shell 11 meets the temperature required for anaerobic reaction, at which point the heating unit is turned off. 4) The online detector detects the pH of the slurry at different locations within the cavity of the reactor cylinder 11 and transmits the detected pH values to the computer for data analysis. The computer determines that the pH values of the slurry at different locations within the reactor cylinder 11 are different. The computer controls the PLC controller to increase the operating power of the stirring motor 31 and accelerate the stirring of the slurry by the spiral stirrer 22 until the online detector detects that the pH values of the slurry at different locations within the cavity of the reactor cylinder 11 are the same, at which point the rated operating power is restored. 5) The online detector detects the gas flow rate at the exhaust port of reactor shell 11 and transmits the detected gas flow rate to the computer for data analysis. The computer determines that the gas flow rate at the exhaust port of reactor shell 11 has decreased. The computer controls the PLC controller to increase the operating power of the stirring motor 31 and the spiral stirrer 22 to accelerate the stirring of the slurry until the online detector detects that the gas flow rate at the exhaust port of reactor shell 11 has reached the standard flow rate, at which point the rated operating power is restored.
[0035] During operation, the slurry is conveyed from the upper part of the reactor cylinder 11 into the spiral cylinder 21 of the spiral stirring center via the feed screw. The slurry enters from top to bottom. When the spiral stirrer 22 rotates, the slurry flowing into the spiral cylinder 21 is continuously pushed and lifted by the spiral blades 23 inside the cylinder. The slurry at the bottom can be forcibly lifted from the spiral cylinder 21 to the top of the central cylinder and forcibly flowed out from the top of the spiral cylinder 21 into the cavity of the reactor cylinder 11. That is, the rising zone inside the spiral cylinder 21 and the descending zone outside the spiral cylinder 21 work together to achieve a large-scale circulation of the slurry. This ensures that the slurry is homogeneous, without dead corners, without sedimentation, and without clogging in the cavity of the reactor cylinder 11. It also ensures that the slurry temperature and pH are balanced at each point in the tank, the biogas produced is easily discharged, and the COD degradation rate is fast.
[0036] Comparative Example 1: Anaerobic fermentation was carried out using traditional methods, and data from completing one fermentation cycle were recorded and compared with data from Example 2. See the table below for details:
[0037] Through the above method, reactor cylinder 11 can be continuously fed and discharged. The concentration of the feed slurry in reactor cylinder 11 is controlled at a solids content of about 12%. After 15 days of sufficient anaerobic reaction, through the anaerobic device and stirring method of this process, the concentration of digestate in reactor cylinder 11 can reach about 8%, achieving medium-concentration anaerobic fermentation. The anaerobic environment inside reactor cylinder 11 is mesophilic. Temperature monitoring instruments are installed at different heights and positions in reactor cylinder 11. The heating devices evenly distributed on the outer wall of reactor cylinder 11 can achieve mesophilic anaerobic conditions in the range of 35-37℃, and due to the continuous circulation of the internal slurry, the slurry is heated evenly.
[0038] Furthermore, the anaerobic efficiency of this application can reach 95%, resulting in a high biogas production rate. The generated biogas is output through a three-phase separator at the top of the reactor cylinder 11, and an online gas flow monitoring instrument is installed at the exhaust port. The biogas production per ton of kitchen waste is close to 100 m³. 3 Meanwhile, the pH monitoring of the slurry inside the reactor cylinder 11 is also monitored by online monitoring instruments at different heights and positions, both at the top, middle, and bottom. All of the above data can be observed in real time and cumulatively on a computer, which facilitates real-time adjustments.
[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A medium-concentration anaerobic treatment device for a food waste fermentation system, comprising a reactor cylinder (11), a stirrer, and a drive unit; the reactor cylinder (11) is provided with a cavity for providing food waste slurry for anaerobic reaction; the drive unit is connected to the stirrer arranged in the cavity and drives the stirrer to rotate, and the rotating stirrer is used to drive the slurry in the cavity to flow from the bottom to the top of the cavity.
2. The medium-concentration anaerobic treatment device for a food waste fermentation system as described in claim 1, characterized in that, It also includes a heating unit, which is disposed on the reactor cylinder (11) and is used to heat the slurry inside the reactor cylinder (11).
3. The medium-concentration anaerobic treatment device for a food waste fermentation system as described in claim 2, characterized in that, It also includes an online detector, which is installed inside the reactor cylinder (11) and is used to detect the pH value, temperature and biogas production rate of the slurry in the cavity of the reactor cylinder (11) in real time.
4. The medium-concentration anaerobic treatment device for a food waste fermentation system and its method of use as described in claim 1, characterized in that, The agitator includes a spiral cylinder (21) and a spiral stirrer (22); the spiral cylinder (21) is vertically installed in the cavity of the reactor cylinder (11), and the spiral cylinder (21) is fitted onto the spiral stirrer (22); the top end of the spiral stirrer (22) is connected to the drive shaft.
5. The medium-concentration anaerobic treatment device for a food waste fermentation system and its method of use as described in claim 4, characterized in that, The spiral stirrer (22) is provided with spiral blades (23); the spiral blades (23) adopt right-handed generatrix equal pitch spiral, and the ratio of the diameter of the reactor cylinder (11) to the diameter of the spiral shaft is 20:1~25:
1.
6. A medium-concentration anaerobic treatment device for a food waste fermentation system as described in claim 4 or 5, and its method of use, characterized in that, It also includes connecting rods (13); one end of the connecting rod (13) is connected to the outer wall of the spiral cylinder (21), and the other end is connected to the inner wall of the cavity of the reactor cylinder (11). There are multiple connecting rods (13), and the multiple connecting rods (13) are evenly distributed along the circumferential and vertical directions of the spiral cylinder (21).
7. The medium-concentration anaerobic treatment device for a food waste fermentation system and its method of use as described in claim 3, characterized in that, The drive unit includes a stirring motor (31) and a PLC controller; the stirring motor (31) is a variable frequency motor and is electrically connected to the PLC controller.
8. The medium-concentration anaerobic treatment device for a food waste fermentation system and its method of use as described in claim 4, characterized in that, It also includes a drain valve; the bottom of the cavity of the reactor cylinder (11) is set as a cone (12), and the bottom of the spiral cylinder (21) extends into the cone (12) at the bottom of the cavity of the reactor cylinder (11); the drain valve is set at the bottom of the reactor cylinder (11).
9. The medium-concentration anaerobic treatment device for a food waste fermentation system and its method of use as described in claim 7, characterized in that, It also includes a computer; the computer is electrically connected to the heating unit, the online detector and the PLC controller.
10. A method of using a medium-concentration anaerobic treatment device for a food waste fermentation system as described in any one of claims 1-9, characterized in that, The method includes the following steps: 1) The kitchen waste is pre-treated to form kitchen waste slurry, and the kitchen waste slurry is pumped into the cavity of the reactor cylinder (11); 2) The computer starts the stirring motor (31), and the spiral stirrer (22) rotates to lift the slurry at the bottom of the spiral barrel (21) to the top of the spiral barrel (21), and flows out from the top of the spiral barrel (21), forming a circulation flow from bottom to top in the cavity of the reactor body (11); 3) The online detector detects the temperature of the slurry in the cavity of the reactor cylinder (11) and transmits the temperature information to the computer for data analysis. The computer determines that the detected temperature is lower than the temperature required for the slurry in the cavity of the reactor cylinder (11) to carry out anaerobic reaction. The heating part is turned on, and the heating part heats the outer wall of the reactor cylinder (11). The PLC controller is controlled to increase the operating power of the stirring motor (31), and the spiral stirrer (22) accelerates the stirring of the slurry until the online detector detects that the temperature of the slurry in multiple places in the reactor cylinder (11) meets the temperature required for anaerobic reaction. Then the heating part is turned off. 4) The online detector detects the pH of the slurry at different locations in the cavity of the reactor cylinder (11) and transmits the detected pH value to the computer for data analysis. The computer determines that the pH value of the slurry at different locations in the reactor cylinder (11) is different. The computer controls the PLC controller to increase the operating power of the stirring motor (31) and the spiral stirrer (22) to accelerate the stirring of the slurry until the online detector detects that the pH value of the slurry at different locations in the cavity of the reactor cylinder (11) is the same, and then restores the rated operating power. 5) The online detector detects the gas flow rate at the exhaust port of the reactor shell (11) and transmits the detected gas flow rate to the computer for data analysis. The computer determines that the gas flow rate at the exhaust port of the reactor shell (11) has decreased. The computer controls the PLC controller to increase the operating power of the stirring motor (31) and the spiral stirrer (22) to accelerate the stirring of the slurry until the online detector detects that the gas flow rate at the exhaust port of the reactor shell (11) has reached the standard flow rate and then restores the rated operating power.