Straw high-temperature solid two-phase anaerobic fermentation system

Abstract

The invention relates to a straw high-temperature solid two-phase anaerobic fermentation system which comprises an acid phase fermentation part and a methane phase fermentation part, the acid phase fermentation part comprises a vertical fermentation bin, the vertical fermentation bin is provided with a stirrer and a liquid adding pipe, and the bottom of the vertical fermentation bin is connected with the methane phase fermentation part through a conveying pipe provided with a material pump; the methane phase fermentation part comprises a horizontal fermentation bin, the interior of the horizontal fermentation bin is divided into a fermentation chamber and a liquid storage chamber by a chain scraper device up and down, an exhaust port provided with a valve is formed in the top of the fermentation chamber, and a plurality of gas pulse devices used for blowing and stirring materials are communicated above the chain scraper device; a discharging device for discharging solid materials is also arranged on one side of the bottom of the fermentation room. The system can realize the separation operation of acid phase fermentation and methane phase fermentation of straws, obviously reduces the inhibition effect of the acid phase fermentation on the methane phase fermentation, simultaneously adopts biogas pulse to replace mechanical stirring to reduce the operation energy consumption of the system, guarantees the stable operation of the anaerobic fermentation system, and improves the proportion of methane in the obtained biogas.

Description

Technical Field

[0001] The invention belongs to the technical field of biomass anaerobic fermentation, and in particular relates to a straw high-temperature solid two-phase anaerobic fermentation system. Background Art

[0002] At present, the anaerobic fermentation technology of biomass is basically divided into two methods: wet anaerobic fermentation and high-temperature solid fermentation. The former has a higher moisture content in the fermentation substrate and requires a larger reactor volume and higher energy consumption to heat the substrate. Therefore, it is subject to more restrictions in the actual application process. At the same time, the process will also produce more biogas slurry, further increasing the cost investment in the treatment of fermentation waste liquid; the latter has a fermentation material solid content of more than 15%, and the overall flowing water content is extremely low and fermented in a high-temperature fermentation environment above 45°C. It has the advantages of higher gas production per unit volume, less energy consumption required for heating, less reactor volume and less biogas slurry to be treated, and can also achieve a higher organic load rate. At the same time, the biogas residue produced by the high-temperature solid anaerobic fermentation process is suitable for use as fertilizer or fuel due to its lower moisture content, which can also generate economic benefits.

[0003] However, no matter which method is used, a mixed fermentation mode of materials and microorganisms is adopted, and the anaerobic fermentation of straw includes acid phase fermentation and methane phase fermentation. The former is that microorganisms convert organic matter into organic acids and alcohols, while the latter is that microorganisms convert organic acids and alcohols into methane. However, acid phase fermentation will significantly inhibit the effect of methane phase fermentation, resulting in a lower methane yield in the overall fermentation.

[0004] At the same time, the existing anaerobic fermentation process is difficult to separate and treat the biogas slurry and biogas residue in the later stage, and the direct discharge or treatment of the biogas residue and biogas slurry also leads to the continuous loss of bacterial colonies in the fermentation system, so it is necessary to continuously add inoculum to maintain the continuous operation of the fermentation, thereby increasing the comprehensive management cost of the system operation. In addition, the high-temperature solid fermentation itself has poor fluidity, and the energy consumption of relying solely on mechanical stirring is very high, resulting in a low overall net work output of the system. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a straw high-temperature solid two-phase anaerobic fermentation system. The system can realize the separation of acid phase fermentation and methane phase fermentation of straw, replace the traditional mixed single-phase fermentation mode, and significantly reduce the inhibitory effect of acid phase fermentation on methane phase fermentation. At the same time, the use of a gas jet stirring device for biogas reflux can reduce the energy consumption of system operation, ensure the smooth operation of the anaerobic fermentation system and increase the proportion of methane content in the obtained biogas.

[0006] To achieve the above object, the present invention provides the following technical solutions: A straw high-temperature solid two-phase anaerobic fermentation system, the system comprising an acid phase fermentation section and a methane phase fermentation section, the acid phase fermentation section comprising a vertical fermentation bin provided with a stirrer, the bottom of the vertical fermentation bin being connected to the methane phase fermentation section via a feed pipe provided with a material pump, the interior of the vertical fermentation bin being further connected with a liquid adding pipe, the outlet of the liquid adding pipe being arranged above the material level inside the vertical fermentation bin; The methane phase fermentation section includes a horizontal fermentation bin, and the interior of the horizontal fermentation bin is divided into a fermentation room and a liquid storage room by a chain scraper device at the upper and lower parts. The outlet of the feed pipe is arranged at the same height as the material level of the fermentation room. An exhaust port equipped with a valve is arranged at the top of the fermentation room. Several gas pulse devices for air blowing and stirring materials are connected to the fermentation room above the chain scraper device. A discharge device for discharging solid materials is also arranged at one side of the bottom of the fermentation room. The liquid storage room is used to receive the biogas slurry discharged from the fermentation room and a heating device is arranged in the liquid storage room. The liquid storage room is connected with the fermentation room and the liquid adding pipe respectively through a pump group.

[0007] The chain scraper device in the horizontal fermentation bin can prevent solid materials from entering the liquid storage room from the fermentation room, but the biogas slurry in the fermentation room can pass through the transmission device and enter the liquid storage room. At the same time, the biogas slurry in the fermentation room can carry microorganisms through the pump group to enter the vertical fermentation bin and the horizontal fermentation bin respectively. The vertical fermentation bin mainly carries out acid phase fermentation, and the product after acid phase fermentation enters the horizontal fermentation bin for methane phase fermentation. In this way, the two-phase fermentation is separated, which greatly increases the methane gas production. The reflux stirring of the biogas airflow can increase the proportion of methane production in the final biogas.

[0008] Preferably, the discharge device comprises a discharge bin connected to the fermentation room and isolated from the liquid storage room, the discharge bin inlet is not higher than the chain scraper device, and a shaftless screw conveyor arranged horizontally and perpendicular to the chain scraper device is provided above the discharge bin feed port; The discharge device also includes an inclined screw extruder, and the feed port of the screw extruder is arranged at the discharge port of the discharge bin. The discharge bin is not connected to the liquid storage room to prevent the biogas slurry in the liquid storage room from being discharged through the discharge bin, but some of the biogas slurry in the fermentation room will flow into the discharge bin, and the materials entering the discharge bin will also carry some biogas slurry, so the staff can set a biogas slurry collection device at the bottom of the discharge bin according to actual application, which can be discharged back into the heating space after subsequent treatment, or it can be used as an organic fertilizer raw material with biogas residue.

[0009] Preferably, the pump group includes a reflux pipe connecting the fermentation room and the liquid storage room, the reflux pipe is equipped with a reflux pump and an electromagnetic flowmeter, and the top of the reflux pipe is arranged in the fermentation room and is located above the material level. A plurality of spray ports are opened on the pipe body; The pump group also includes a liquid adding pump arranged on the liquid adding pipe.

[0010] Preferably, the heating device is an electric heating rod powered by green energy and / or a heat exchange tube structure into which a heat medium is introduced. The green energy includes but is not limited to electricity converted from clean energy such as light energy and wind energy; the heat medium can be geothermal water or hot wastewater generated in other production process links.

[0011] Preferably, the gas pulse device comprises a plurality of bronchi extending from a parallel transmission device, wherein the bronchi are arranged below the material level and are arranged from high to low relative to each other.

[0012] Preferably, the bronchus is provided with an air jet hole exposed to the fermentation room, and one end of the bronchus located outside is provided with a ball valve and connected to one end of the main air pipe respectively; The other end of the main air pipe is sequentially provided with a solenoid valve and a supercharger and is connected to an air source, and the air source is connected to the exhaust port.

[0013] The working principle of the present invention is as follows: First, acid phase fermentation of materials is carried out in the vertical fermentation bin, and the acid phase fermentation products and materials are pumped into the horizontal fermentation bin through the material pump as fermentation substrate for methane phase fermentation. The biogas slurry produced in the horizontal fermentation bin passes through the chain scraper device and enters the liquid storage room at the bottom. The biogas slurry in the liquid storage room is heated to 50-60°C by the heating device, and then pumped into the vertical fermentation bin through the liquid adding pipe equipped with a liquid adding pump and pumped into the horizontal fermentation bin through the reflux pipe equipped with a reflux pump, so that the high-temperature biogas slurry carrying microorganisms can be sprayed on the corresponding materials, so that the fermentation environment meets the high temperature requirement of solid anaerobic fermentation.

[0014] The biogas produced by the methane phase fermentation in the horizontal fermentation chamber is discharged and collected as the gas source for pulse air blowing. The main air pipe pressurizes the biogas and blows the pulse air through the bronchial jet holes to stir the materials in the fermentation room, thereby achieving disturbed mixed fermentation of the materials in the fermentation room. The chain scraper device transmits the material at the bottom of the fermentation room to the shaftless screw conveyor, which transmits the material to the discharge bin and the material is extruded and drained by the screw extruder before being transported to the outside and used as biogas residue. Part of the biogas residue can be used as a carrier of microorganisms to enter the vertical fermentation bin and horizontal fermentation bin again and participate in fermentation, and part of it can also be used as raw material for subsequent organic fertilizer preparation.

[0015] Compared with the prior art, the present invention has the following advantages: 1) This system can realize the separation of acid phase fermentation and methane phase fermentation of straw, replacing the traditional mixed single-phase fermentation mode, significantly reducing the inhibitory effect of acid phase fermentation on methane phase fermentation, and at the same time, it can reasonably arrange the acid phase hydrolysis rate of the material in combination with the methane phase anaerobic fermentation rate to achieve automatic control.

[0016] 2) The heating load of the whole machine is small: Temperature is one of the important factors affecting the activity of microbial enzymes, and the processing capacity of anaerobic fermentation will decrease significantly with the decrease in temperature. Therefore, in order to maintain a high fermentation efficiency, the temperature of the fermentation environment needs to be kept above 45°C. This application adopts the method of heating the circulating biogas slurry separately instead of heating the entire reaction substrate, which greatly reduces the heat load and energy consumption of the whole machine; at the same time, the biogas slurry rich in microorganisms can be sprayed and efficiently contact the material, thereby achieving the effect of high temperature and efficient fermentation. Moreover, the heating energy can adopt a variety of green energy or industrial waste heat, which is very friendly to the environment.

[0017] 3) High dynamic fermentation efficiency and low loss of microorganisms: The biogas slurry in this application can be recycled, and the discharged biogas residue will also serve as a component of the subsequent fermentation substrate and will carry the microorganisms to participate in the fermentation again, thereby achieving the enrichment and domestication of the anaerobic fermentation flora, promoting the efficient fermentation, and eliminating the need to add microorganisms multiple times, thereby reducing the overall management cost.

[0018] 4) Dynamic fermentation quickly separates slag and liquid: The biogas slurry generated by the substrate in the fermentation room can be immediately discharged into the liquid storage room, thereby realizing the separation of solid materials and biogas slurry. At the same time, the biogas slurry will also be circulated and sprayed on the solid materials. Therefore, on the basis of ensuring the humidity demand of the fermentation environment, the humidity balance of the discharged materials is ensured, thereby reducing the difficulty of squeezing and separating the subsequent materials from the biogas slurry.

[0019] 5) The mixed disturbance effect of pulse air blowing and transmission device has low energy consumption and good effect: The present application blows the biogas generated by fermentation to the material in pulses after pressurization. On the one hand, the oxygen introduced in the dynamic feeding process can be discharged to ensure an anaerobic environment. On the other hand, the high-pressure pulse gas can effectively impact the material to achieve disturbed mixing of the material. At the same time, the present application sets a chain scraper device at the bottom of the fermentation room to discharge the fermented material at the bottom, which can also achieve disturbed mixing of the material. The present application has no mechanical stirring operation as a whole, which improves the stability of the system operation.

[0020] 6) The circulating gas blowing of biogas in the methane phase fermentation section can increase the methane content in the final gas: The pulse air blowing of the present application adopts the biogas obtained from the horizontal fermentation bin as the gas source, and realizes its circulation flow in the horizontal fermentation bin. In this way, the gas source can make the fermentation material adsorb gases such as carbon dioxide in the gas source on the basis of sufficient contact with the fermentation material, and finally carry the gas to the outside in the form of biogas residue, thereby achieving the effect of purifying the gas source, that is, increasing the methane content in the final biogas obtained, thereby reducing the subsequent biogas purification and processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the straw high-temperature solid two-phase anaerobic fermentation system described in the specific implementation method. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] like Figure 1 As shown, a straw high temperature solid two-phase anaerobic fermentation system, A straw high-temperature solid two-phase anaerobic fermentation system, the system comprising an acid phase fermentation section and a methane phase fermentation section: The methane phase fermentation section includes a horizontal fermentation bin 13, and the interior of the horizontal fermentation bin 13 is divided into a fermentation room 12 and a liquid storage room 10 at the upper and lower parts by a chain scraper device 11 extending horizontally. An exhaust port 14 equipped with a valve is provided at the top of the fermentation room 12; The horizontal fermentation bin 13 is provided with a plurality of bronchial pipes 16 extending from parallel transmission devices at a position between the chain scraper device 11 and the high point of the material level. The bronchial pipes 16 are arranged from high to low with respect to each other. The bronchial pipes 16 are provided with air injection holes exposed to the fermentation room, and one end of the bronchial pipe 16 located to the outside is provided with a ball valve and is respectively connected to one end of the main air pipe 17, and the other end of the main air pipe 17 is sequentially provided with a solenoid valve and a supercharger and connected to the air source.

[0024] The liquid storage room 10 is used to receive the biogas slurry discharged from the fermentation room 12 and is provided with an electric heating rod and a heat exchange pipe structure 20 for introducing a heat medium. A reflux pipe 15 equipped with a reflux pump and an electromagnetic flowmeter connects the fermentation room 12 and the liquid storage room 10, and the top of the reflux pipe 15 is arranged in the fermentation room 12 and is located above the material level. A plurality of spray ports are opened on the pipe body.

[0025] A discharge device for discharging solid materials is also provided on one side of the bottom of the fermentation room 12, including a discharge bin connected to the fermentation room 12 and isolated from the liquid storage room 10, the inlet of the discharge bin is not higher than the chain scraper device 11, and a shaftless screw conveyor 18 is provided above the feed inlet of the discharge bin and is arranged horizontally and vertically to the chain scraper device 11; The discharge device further comprises a screw extruder 19 which is arranged obliquely, and the feed port of the screw extruder 19 is arranged at the discharge port of the discharge bin.

[0026] The acid phase fermentation section includes a vertical fermentation bin 5 provided with a stirrer 4 and a temperature monitor 6. A valve is provided at the feed port 2 of the vertical fermentation bin 5 and the feed port 2 is connected to the output end of the belt conveyor 1. The discharge port 7 at the bottom of the vertical fermentation bin 5 is connected to the horizontal fermentation bin 13 through a feed pipe equipped with a material pump 8, and the outlet of the feed pipe is arranged at the same height as the material level of the fermentation room 12. A liquid adding pipe 3 is also connected to the interior of the vertical fermentation bin 5, and the outlet of the liquid adding pipe 3 is arranged above the material level inside the vertical fermentation bin 5. The inlet of the liquid adding pipe 3 is connected to the liquid storage room 10 and a liquid adding pump 9 is arranged on the liquid adding pipe; The working principle of the present invention is as follows: First, acid phase fermentation of materials is carried out in the vertical fermentation bin 5, and the acid phase fermentation products and materials are pumped into the horizontal fermentation bin 13 through the material pump 8 as fermentation substrates for methane phase fermentation. The biogas slurry produced in the horizontal fermentation bin 13 passes through the chain scraper device 11 and enters the liquid storage room 10 at the bottom. The biogas slurry in the liquid storage room 10 is heated to 50-60°C by the heating device 20, and then pumped into the vertical fermentation bin 5 through the liquid adding pipe 3 equipped with a liquid adding pump 9 and pumped into the horizontal fermentation bin 13 through the reflux pipe 15 equipped with a reflux pump, so that the high-temperature biogas slurry carrying microorganisms can be sprayed on the corresponding materials, so that the fermentation environment meets the high temperature requirement of solid anaerobic fermentation.

[0027] The biogas produced by the methane phase fermentation in the horizontal fermentation bin 13 is discharged and collected as the gas source for pulse air blowing. The main air pipe 17 pressurizes the biogas and passes it through the air jet holes of the bronchial pipe 16 to perform pulse air blowing and stirring on the materials in the fermentation room at a pressure of 0.1-0.6MPa, thereby achieving disturbed mixed fermentation of the materials in the fermentation room. The chain scraper device 11 transmits the material at the bottom of the fermentation room 12 to the shaftless screw conveyor 18, and the shaftless screw conveyor 18 transmits the material to the discharge bin, and the material is extruded and drained by the screw extruder 19 and then transported to the outside and used as biogas residue. A part of the biogas residue can be used as a carrier of microorganisms to enter the vertical fermentation bin 5 and the horizontal fermentation bin 13 again and participate in fermentation, and a part of it can also be used as a raw material for subsequent organic fertilizer preparation.

Claims

1. A straw high temperature solid two-phase anaerobic fermentation system, characterized in that: The system comprises an acid phase fermentation section and a methane phase fermentation section: The acid phase fermentation part includes a vertical fermentation bin equipped with a stirrer, the bottom of the vertical fermentation bin is connected to the methane phase fermentation part through a feed pipe equipped with a material pump, and the interior of the vertical fermentation bin is also connected to a liquid adding pipe, and the outlet of the liquid adding pipe is arranged above the material level inside the vertical fermentation bin; The methane phase fermentation section includes a horizontal fermentation bin, and the interior of the horizontal fermentation bin is divided into a fermentation room and a liquid storage room by a chain scraper device at the upper and lower parts. The outlet of the feed pipe is arranged at the same height as the material level of the fermentation room. An exhaust port equipped with a valve is arranged at the top of the fermentation room. Several gas pulse devices for air blowing and stirring materials are connected to the fermentation room above the chain scraper device. A discharge device for discharging solid materials is also arranged at one side of the bottom of the fermentation room. The liquid storage room is used to receive the biogas slurry discharged from the fermentation room and a heating device is arranged in the liquid storage room. The liquid storage room is connected with the fermentation room and the liquid adding pipe respectively through a pump group.

2. The straw high temperature solid two-phase anaerobic fermentation system according to claim 1, characterized in that: The discharge device comprises a discharge bin connected to the fermentation room and isolated from the liquid storage room, the discharge bin inlet is not higher than the chain scraper device, and a shaftless screw conveyor arranged horizontally and vertically to the chain scraper device is provided above the discharge bin feed port; The discharge device also includes a screw extruder that is arranged obliquely, and the feed port of the screw extruder is arranged at the discharge port of the discharge bin.

3. The straw high temperature solid two-phase anaerobic fermentation system according to claim 1, characterized in that: The pump group includes a reflux pipe connecting the fermentation room and the liquid storage room, the reflux pipe is equipped with a reflux pump and an electromagnetic flowmeter, and the top of the reflux pipe is arranged in the fermentation room and is located above the material level. A plurality of spray ports are opened on the pipe body; The pump group also includes a liquid adding pump arranged on the liquid adding pipe.

4. The straw high temperature solid two-phase anaerobic fermentation system according to claim 1, characterized in that: The heating device is an electric heating rod powered by green energy and / or a heat exchange pipe structure into which a heat medium is passed.

5. The straw high temperature solid two-phase anaerobic fermentation system according to claim 1, characterized in that: The gas pulse device comprises a plurality of bronchial tubes extending from a parallel transmission device, wherein the bronchial tubes are arranged below the material level and are arranged from high to low.

6. The straw high temperature solid two-phase anaerobic fermentation system according to claim 7, characterized in that: The bronchus is provided with a jet hole exposed to the fermentation room, and the pressure of the biogas discharged from the jet hole is 0.1-0.6MPa; and a ball valve is provided at one end of the bronchus located outside and connected to one end of the main air pipe respectively; The other end of the main air pipe is sequentially provided with a solenoid valve and a supercharger and is connected to an air source, and the air source is connected to the exhaust port.

7. Application of the straw high temperature solid two-phase anaerobic fermentation system according to any one of claims 1 to 4, characterized in that: The heating device maintains the temperature of the biogas slurry in the heating space at 50-60°C.

8. Application of the straw high temperature solid two-phase anaerobic fermentation system according to any one of claims 1 to 6, characterized in that: The gas injection hole injects biogas with a pressure of 0.1-0.6 MPa toward the fermentation room.

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