Device for producing methane from high-concentration manure and straw under partitioned temperature control

Abstract

The utility model discloses a device for producing methane from high-concentration manure straws under zoned temperature control. Comprising a fermentation tank body, a first temperature maintaining unit and a second temperature maintaining unit which are respectively coated on the outer wall of the fermentation tank body, and a temperature buffering unit which is coated on the outer wall of the fermentation tank body and is positioned between the first temperature maintaining unit and the second temperature maintaining unit, the second temperature maintaining unit corresponds to a methane reaction area at the lower part of the fermentation tank body; and the temperature buffering unit is positioned at the junction of the acidification reaction area and the methane reaction area. The device realizes zoned temperature control of the fermentation tank body, is beneficial to providing respective appropriate temperatures for different strains in each reaction stage, improves the hydrolytic acidification efficiency of fermentation materials, improves the efficiency of methanogens and the yield of methane, can avoid excessive acidification of a fermentation system, and reduces the production cost. The feeding and discharging balance of the anaerobic fermentation system is maintained, and the efficiency of the whole material fermentation process is improved.

Description

Technical Field

[0001] This utility model relates to the technical field of methane production equipment, specifically to a high-concentration manure-straw methane production device with zoned temperature control. Background Technology

[0002] Currently, in the anaerobic digestion and methanogenesis technology of high-concentration manure (such as straw, livestock and poultry manure, etc.), some studies have achieved functional zoning and efficient methanogenesis of the fermentation system by controlling the stirring mode. However, there is still considerable room for improvement in the hydrolysis and acidification efficiency of the material. Other studies have shown that increasing the fermentation temperature is beneficial to the hydrolysis and acidification of lignocellulosic materials. However, existing high-concentration manure methanogenesis devices and traditional CSTR reactors maintain a constant temperature of the fermentation material through an integrated heating device, which cannot simultaneously meet the optimal temperature requirements for efficient metabolism of acidifying bacteria and methanogenic archaea. Furthermore, high-concentration manure is prone to excessive acid production at a single temperature, resulting in an excessively low pH of the fermentation system, which in turn inhibits the metabolic activity of methanogenic bacteria.

[0003] Currently, there is a lack of a zoned temperature control structure that can simultaneously meet the optimal temperature requirements of both the acidification zone and the methanogenic zone, while also being energy-efficient, cost-effective, and easy to operate. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a high-concentration manure-straw methanogenizing device with zoned temperature control.

[0005] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A high-concentration manure straw methanogenization device with zoned temperature control includes a fermentation tank, a first temperature maintenance unit and a second temperature maintenance unit respectively covering the outer wall of the fermentation tank, a temperature buffer unit covering the outer wall of the fermentation tank and located between the first temperature maintenance unit and the second temperature maintenance unit, and a heating mechanism respectively disposed in the first temperature maintenance unit and the second temperature maintenance unit.

[0006] The first temperature maintenance unit corresponds to the acidification reaction zone at the top of the fermenter, the second temperature maintenance unit corresponds to the methane reaction zone at the bottom of the fermenter, and the temperature buffer unit is located at the junction of the acidification reaction zone and the methane reaction zone.

[0007] Furthermore, both the first temperature maintaining unit and the second temperature maintaining unit include an annular jacket with an inner cavity and an outer cavity. The inner cavity of the annular jacket is fitted with the outer wall of the fermentation tank. The inner cavity is filled with a first liquid heating medium layer, and the outer cavity is filled with a second liquid heating medium layer. The heating mechanism is disposed within the jacket of the annular jacket.

[0008] Furthermore, the temperature buffer unit includes a buffer shell disposed on the outer wall of the fermenter, and the buffer shell is filled with a layer of solid filler.

[0009] Furthermore, temperature sensors are installed in the acidification reaction zone and the methane reaction zone of the fermenter, and the temperature sensors and the heating mechanism are respectively connected to the control unit.

[0010] Furthermore, a stirring assembly is installed inside the fermentation tank;

[0011] The stirring assembly includes a drive unit located at the top of the fermentation tank, a stirring shaft connected to the output end of the drive unit and extending into the interior of the fermentation tank, and stirring blades mounted on the stirring shaft. The stirring blades are non-uniformly distributed along the axial direction of the stirring shaft, forming an upper high-density stirring zone and a lower low-density stirring zone.

[0012] Furthermore, the top of the fermentation tank is equipped with an oxygen delivery pipe, a feed inlet, and a biogas outlet.

[0013] Furthermore, an oxygen concentration detector is installed on the top of the fermentation tank to detect oxygen concentration.

[0014] The present invention has the following beneficial effects: The present invention provides a high-concentration manure-straw methanogenizing device with zoned temperature control. This device realizes zoned temperature control, optimizes the distribution of microbial communities, improves reaction efficiency, promotes the efficient conversion of methanogens into biogas, reduces the risk of acidification, improves system stability, and allows the VFA produced by rapid hydrolysis and acidification in the high-temperature zone to be consumed in time in the medium-temperature zone, avoiding the accumulation of VFA that leads to a drop in pH. At the same time, it is more energy-efficient and reduces consumption compared with the traditional method, and optimizes the utilization rate of thermal energy. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model;

[0016] Figure 2 This is a cross-sectional view of the temperature maintenance unit in this utility model;

[0017] Figure 3 This is a top view of the temperature maintenance unit in this utility model;

[0018] Figures 1 to 3 The reference numerals in the attached drawings are as follows: 1-fermentation tank, 2-first temperature maintenance unit, 3-second temperature maintenance unit, 4-temperature buffer unit, 10-acidification reaction zone, 11-methane reaction zone, 20-annular jacket, 21-first liquid heating medium layer, 22-second liquid heating medium layer, 40-buffer shell, 41-solid packing layer, 12-drive component, 13-stirring shaft, 14-stirring blades, 15-oxygen delivery pipe, 16-feed inlet, 17-biogas outlet, 18-oxygen concentration detector. Detailed Implementation

[0019] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0020] like Figures 1 to 3 As shown, a high-concentration manure-straw methanogenic device with zoned temperature control is characterized by comprising a fermentation tank 1, a first temperature maintenance unit 2 and a second temperature maintenance unit 3 respectively covering the outer wall of the fermentation tank 1, a temperature buffer unit 4 covering the outer wall of the fermentation tank 1 and located between the first temperature maintenance unit 2 and the second temperature maintenance unit 3, and heating mechanisms respectively disposed within the first temperature maintenance unit 2 and the second temperature maintenance unit 3. The fermentation tank 1 contains high-concentration manure-straw raw materials (straw / livestock manure), providing anaerobic fermentation space for an acidification reaction zone 10 (upper part) and a methanogenic reaction zone 11 (lower part), realizing stratified material reaction and avoiding metabolic inhibition caused by mixed fermentation.

[0021] The first temperature maintenance unit 2 corresponds to the acidification reaction zone 10 at the top of the fermenter 1. It maintains a constant temperature environment of 35-42℃ (optimal 40℃) through an internal heating mechanism, promoting the rapid decomposition of organic matter by hydrolytic acidifying bacteria to generate volatile fatty acids (VFA). The second temperature maintenance unit 3 corresponds to the methane reaction zone 11 at the bottom of the fermenter 1. It maintains a constant temperature environment of 25-35℃ (optimal 30℃) through an independent heating mechanism, optimizing the activity of methanogenic bacteria and accelerating the conversion of VFA to methane. The temperature buffer unit 4 is located at the boundary between the acidification reaction zone 10 and the methane reaction zone 11. It forms a non-linear temperature gradient transition zone (see the measured temperature curve below), slowing down the heat transfer rate.

[0022] The heating mechanism of the first temperature maintenance unit 2 can use a spiral electric heating tube for rapid heating and adaptability to high-load acidification. The heating mechanism of the second temperature maintenance unit 3 uses a flat plate heater for uniform heat dissipation and protection of the activity of thermophilic bacteria. Temperature sensors are respectively installed in the acidification reaction zone 10 and the methane reaction zone 11 of the fermentation tank 1, and the temperature sensors and heating mechanisms are respectively connected to the control unit. The control unit can use an STM32 microcontroller or PLC control system, and the temperature sensors can use existing ones that can realize temperature acquisition and feedback. During use, the temperature sensors collect the temperature data of the reaction zone and transmit the temperature data to the control unit. The control unit analyzes the data, and when the preset temperature value is not reached, the control unit controls the heating mechanism to heat; when the temperature exceeds the preset threshold, the heating mechanism stops heating. By using independent temperature control in different zones, the limitation of uniform temperature in the heating jacket of the traditional CSTR reactor is overcome.

[0023] In this embodiment, both the first temperature maintaining unit 2 and the second temperature maintaining unit 3 include an annular jacket 20 with an inner cavity and an outer cavity. The inner cavity of the annular jacket 20 is fitted against the outer wall of the fermentation tank 1. The inner cavity is filled with a first liquid heating medium layer 21, and the outer cavity is filled with a second liquid heating medium layer 22. The heating mechanism is disposed within the jacket of the annular jacket 20. The first liquid heating medium layer 21 uses mineral oil or synthetic heat transfer oil, and the second liquid heating medium layer 22 uses water. The temperature buffer unit 4 includes a buffer shell 40 disposed on the outer wall of the fermentation tank 1. The buffer shell 40 is filled with a solid filler layer 41, which uses quartz sand or silica sand. Specifically, a water layer is injected on the outside of the fermentation tank 1, and an oil layer is injected on the inside of the fermentation tank 1. By injecting water of different temperatures from the top and bottom, the effect of zoned temperature control is achieved. The oil layer on the inside serves as insulation to reduce temperature loss. A sand layer is added at 1 / 3 of the fermentation tank 1 to allow for a gradual temperature reduction between the acidification and fermentation processes.

[0024] In this embodiment, a stirring assembly is provided inside the fermentation tank 1. The stirring assembly includes a drive component 12 located at the top of the fermentation tank 1, a stirring shaft 13 connected to the output end of the drive component 12 and extending into the interior of the fermentation tank 1, and stirring blades 14 disposed on the stirring shaft 13. The stirring blades 14 are non-uniformly distributed along the axial direction of the stirring shaft 13, forming a high-density stirring zone at the top and a low-density stirring zone at the bottom. This forms an intermittent stirring structure with a denser top and a sparser bottom, thereby enhancing the acidification and anaerobic fermentation processes, better achieving the reaction conditions of low oxygen at the top and anaerobic conditions at the bottom, and preventing clumping at the top, resulting in a better acidification process and thus improving the efficiency of methanogenesis.

[0025] Specifically, the drive component 12 (such as a motor) provides power to drive the stirring shaft 13 to rotate, achieving the stirring function. Through frequency conversion or intermittent control, it adapts to the different stirring requirements of the acidification and methanogenesis stages. The stirring shaft 13 transmits driving force, supporting the stirring blades 14, ensuring their uniform distribution within the tank and extending to the bottom, guaranteeing effective stirring in both the upper and lower areas. The stirring blades 14 (non-uniformly distributed) form a high-density stirring zone at the top, where dense blades enhance shear force on the surface material, preventing scum agglomeration, promoting gas-liquid mixing during the acidification stage, and maintaining a micro-aerobic environment. The lower low-density stirring zone has sparse blades that reduce disturbance to the bottom sludge, protecting the stability of the anaerobic granular sludge, preventing the redissolution of tiny biogas bubbles, and improving methane collection efficiency. Furthermore, the intermittent stirring method dynamically adapts to the aerobic characteristics of different reaction stages. During the acidification stage (requiring trace amounts of oxygen), short-duration stirring promotes mixing and avoids excessive local acidification; during the methanogenesis stage (strictly anaerobic), the stirring frequency is reduced to maintain an anaerobic environment, which is beneficial for the slow-growing methanogenic bacteria.

[0026] In this embodiment, oxygen supply pipes 15 are respectively installed at the top of the fermenter 1. The oxygen supply pipes 15 are used to regulate the micro-oxygen environment in the acidification zone. In the early stage of the acidification reaction (hydrolysis stage), a small amount of oxygen is introduced to promote the activity of facultative hydrolytic bacteria, accelerate the decomposition of macromolecular organic matter (such as cellulose and protein), and improve the subsequent acidification efficiency. Furthermore, by controlling the oxygen content, it is ensured that oxygen only acts on the upper acidification zone and avoids diffusion to the lower methanogenic zone, which would disrupt the strict anaerobic conditions.

[0027] The fermentation tank 1 is equipped with a feed inlet 16 and a biogas outlet 17 at the top. Pretreated manure-straw mixture is fed into the tank through the feed inlet 16. A flange or quick-connect interface is used at the top of the tank to prevent material from directly entering the methanogenic zone and to maintain an anaerobic environment within the tank, preventing air infiltration. The feed inlet 16 can be designed with multiple points or equipped with a dispersion device to ensure uniform material coverage of the acidification zone and prevent localized accumulation leading to incomplete acidification. The biogas outlet 17 collects the biogas (mainly composed of methane and carbon dioxide) generated in the methanogenic reaction zone 11 and transports it to the purification and storage system via pipeline.

[0028] An oxygen concentration detector 18 is installed at the top of the fermenter 1 to detect oxygen concentration. The oxygen concentration detector 18 monitors the oxygen concentration within the fermenter 1 in real time to ensure strict anaerobic conditions during the methanogenesis stage. Simultaneously, it controls the oxygen supply pipe 15, which is connected to a control unit (such as a PLC) to dynamically adjust the oxygen input and prevent excessive oxygen leakage into the lower methanogenesis zone. When an abnormal oxygen concentration is detected (such as a sudden increase), an alarm is triggered or the oxygen supply is automatically shut off to prevent the inactivation of methanogenic bacteria. The oxygen concentration detector 18 can be a German WTW Oxi 3310 (optical principle) or an American Hach LDO101 (fluorescence method), with a detection range of 0–20 mg / L and an accuracy of ±0.05 mg / L.

[0029] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A high-concentration manure-straw methanogenizing device with zoned temperature control, characterized in that, It includes a fermentation tank (1), a first temperature maintaining unit (2) and a second temperature maintaining unit (3) respectively covering the outer wall of the fermentation tank (1), a temperature buffer unit (4) covering the outer wall of the fermentation tank (1) and located between the first temperature maintaining unit (2) and the second temperature maintaining unit (3), and a heating mechanism respectively disposed in the first temperature maintaining unit (2) and the second temperature maintaining unit (3); The first temperature maintenance unit (2) corresponds to the acidification reaction zone (10) at the top of the fermentation tank (1), the second temperature maintenance unit (3) corresponds to the methane reaction zone (11) at the bottom of the fermentation tank (1), and the temperature buffer unit (4) is located at the junction of the acidification reaction zone (10) and the methane reaction zone (11).

2. The high-concentration manure-straw methanogenizing device with zoned temperature control according to claim 1, characterized in that, The first temperature maintenance unit (2) and the second temperature maintenance unit (3) both include an annular jacket (20) with an inner cavity and an outer cavity. The inner cavity of the annular jacket (20) is in contact with the outer wall of the fermentation tank (1). The inner cavity is filled with a first liquid heating medium layer (21), and the outer cavity is filled with a second liquid heating medium layer (22). The heating mechanism is disposed in the jacket of the annular jacket (20).

3. The high-concentration manure-straw methanogenizing device with zoned temperature control according to claim 1, characterized in that, The temperature buffer unit (4) includes a buffer shell (40) disposed on the outer wall of the fermentation tank (1), and the buffer shell (40) is filled with a solid filler layer (41).

4. The high-concentration manure-straw methanogenizing device with zoned temperature control according to claim 1, characterized in that, Temperature sensors are provided in the acidification reaction zone (10) and methane reaction zone (11) of the fermentation tank (1), and the temperature sensors and the heating mechanism are respectively connected to the control unit.

5. The high-concentration manure-straw methanogenizing device with zoned temperature control according to claim 1, characterized in that, The fermentation tank (1) is equipped with a stirring assembly; The stirring assembly includes a drive unit (12) set on the top of the fermentation tank (1), a stirring shaft (13) connected to the output end of the drive unit (12) and extending into the interior of the fermentation tank (1), and stirring blades (14) set on the stirring shaft (13). The stirring blades (14) are non-uniformly distributed along the axial direction of the stirring shaft (13) and have a dense upper and sparse lower structure, forming a high-density stirring zone in the upper part and a low-density stirring zone in the lower part.

6. The high-concentration manure-straw methanogenizing device with zoned temperature control according to claim 1, characterized in that, The top of the fermentation tank (1) is provided with an oxygen delivery pipe (15), a feed inlet (16) and a biogas outlet (17).

7. The high-concentration manure-straw methanogenizing device with zoned temperature control according to claim 6, characterized in that, The top of the fermentation tank (1) is equipped with an oxygen concentration detector (18) for detecting oxygen concentration.

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