A gas-liquid expansion self-stirring vacuum negative pressure biochemical tower and a straw pretreatment system

Abstract

The utility model provides a kind of gas-liquid expansion self-stirring vacuum negative pressure biochemical tower and straw pretreatment system, the vacuum negative pressure biochemical tower, including tower body, feed inlet and air outlet are set on upper portion of tower body, lower portion is set discharge port;The water bath heating coil of water circulation hot water is provided on the outer wall of the tower body, the tower body inner wall is provided with the flow guide rib plate that spirals upwards from below.The vacuum negative pressure biochemical tower of the utility model is provided with vacuum pump and flow guide rib plate, the change of internal air pressure of tower body makes material gas-liquid expansion to generate vortex, forms self-stirring function, the vacuum negative pressure biochemical tower does not need mechanical stirring mechanism, and energy consumption and failure rate can be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of biogas fermentation technology, and in particular relates to a gas-liquid expansion self-stirring vacuum negative pressure biochemical tower and a straw pretreatment system. Background Technology

[0002] my country produces approximately 800 million tons of straw annually. Traditional disposal methods (such as burning and indiscriminate dumping) easily lead to air pollution and resource waste. Anaerobic fermentation can convert cellulose and hemicellulose in straw into biogas. The remaining fermentation residue (biogas residue and biogas slurry) is a high-quality organic fertilizer, rich in nitrogen, phosphorus, potassium, and organic matter. It can be directly returned to the field to improve soil fertility or processed into commercial organic fertilizer for sale, forming an agricultural circular chain of "straw → biogas → organic fertilizer → crops".

[0003] Lignin, cellulose, and hemicellulose in straw are not easily degraded during anaerobic fermentation. To improve the degradation rate of these substances and increase the biogas production per ton of straw, pretreatment of the straw is necessary. This involves using chemicals (such as quicklime water or sodium hydroxide solution) to break down the lignin, cellulose, and hemicellulose structures within the straw. Current technologies often employ mechanically stirred reactors for straw pretreatment. The straw is immersed in the reactor, and during pretreatment, a mechanical stirring device continuously agitates the mixture, while a heating device raises the temperature to improve reaction efficiency. However, these mechanically stirred reactors have high energy consumption for mechanical stirring and heating functions, with mechanical stirring power exceeding 5.5 kW / ton of material and a transmission structure failure rate exceeding 15%, resulting in high straw treatment costs and low cost-effectiveness in biogas production. Summary of the Invention

[0004] This invention addresses the technical problem of high energy consumption in mechanically stirred reaction tanks for straw pretreatment by proposing a gas-liquid expansion self-stirring vacuum negative pressure biochemical tower that relies on pressure changes to cause material volume expansion, forming vortices that tumble and stir the material.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A gas-liquid expansion self-stirring vacuum negative pressure biochemical tower includes a tower body, with an inlet and an exhaust port at the top and an outlet at the bottom; the outer wall of the tower body is provided with a water bath heating coil for hot water flow, and the inner wall of the tower body is provided with a guide rib plate spiraling upward from bottom to top.

[0006] Preferably, the angle between the lower surface of the guide rib and the tower wall is 10-20°.

[0007] Preferably, the lower surface of the guide rib plate forms an angle of 15° with the tower wall.

[0008] Preferably, the pitch of the guide rib is 25cm.

[0009] Preferably, the tower body is provided with an insulation layer covering the water bath heating coil.

[0010] Preferably, the air extraction port is connected to an extraction pipe, and an arc-shaped separation plate is provided inside the extraction pipe. A gap is provided between the edge of the arc-shaped separation plate and the extraction pipe to allow airflow.

[0011] A straw pretreatment system includes the aforementioned vacuum negative pressure biochemical tower, and further includes a gas-liquid separation device and a water storage tank. The gas-liquid separation device includes a cyclone separator and a wire mesh liquid trapping device. The exhaust port of the vacuum negative pressure biochemical tower is connected to the air inlet of the cyclone separator via an exhaust pipe. The exhaust port of the cyclone separator is connected to the wire mesh liquid trapping device. The lower ends of both the cyclone separator and the wire mesh liquid trapping device are connected to the water storage tank. The exhaust end of the wire mesh liquid trapping device is connected to a vacuum pump.

[0012] Preferably, the water storage tank is connected to the tower body via a liquid delivery pipe, a water pump, and a solenoid valve. A capacitive liquid level sensor is installed in the water storage tank. When the liquid level reaches a set value, the liquid in the water storage tank is pumped into the tower body for reuse.

[0013] Preferably, the outlet of the vacuum pump is connected to a deodorization tower.

[0014] Preferably, the air inlet of the vacuum pump is connected to multiple sets of vacuum negative pressure biochemical towers and gas-liquid separation devices via pipelines, and the vacuum is alternately applied to different vacuum negative pressure biochemical towers.

[0015] Compared with the prior art, the advantages and positive effects of this utility model are as follows: 1. The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower of this utility model is equipped with a vacuum pump and a flow guide rib. It uses the change of gas pressure inside the tower to cause the material to expand gas and liquid, thereby generating vortex and forming a self-stirring function. This vacuum negative pressure biochemical tower does not require a mechanical stirring mechanism, which can reduce energy consumption and failure rate.

[0016] 2. The vacuum negative pressure biochemical tower is equipped with an arc-shaped separation plate inside the exhaust pipe, which can prevent a large number of small straws from being carried out of the exhaust pipe with the airflow, and can also intercept some large droplets to prevent moisture and chemicals inside the tower from being carried out.

[0017] 3. The straw pretreatment system of this utility model connects the exhaust port of the vacuum negative pressure biochemical tower to a gas-liquid separation device through an exhaust pipe. The exhaust end of the gas-liquid separation device is connected to a vacuum pump. The gas-liquid separation device further separates the liquid in the gas flow to prevent the agent from being carried out by the gas flow and affecting the reaction effect.

[0018] 4. Set up a shared vacuum pump to achieve multiple uses of one pump and reduce system configuration costs. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the structure of the straw pretreatment system of this utility model; Figure 2 This is a schematic diagram of the internal structure of the vacuum negative pressure biochemical tower of this utility model; Figure 3 This is a schematic diagram of the arc-shaped separation plate of the vacuum negative pressure biochemical tower of this utility model.

[0020] In the above figures: 1. Tower body; 2. Feed inlet; 3. Exhaust port; 4. Discharge port; 5. Guide ribs; 6. Water bath heating coil; 7. Water inlet; 8. Water outlet; 9. Arc-shaped separation plate; 10. Cyclone separator; 11. Wire mesh liquid trap; 12. Water storage tank; 13. Vacuum pump; 14. Deodorization tower; 15. Liquid delivery pipe; 16. Water pump; 17. Support frame; 18. Exhaust pipe. Detailed Implementation

[0021] To better understand this utility model, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0022] Example: Figure 1 As shown, a straw pretreatment system includes a gas-liquid expansion self-stirring vacuum negative pressure biochemical tower, a gas-liquid separation device, a water storage tank 12, and a vacuum pump 13.

[0023] like Figure 2 As shown, the vacuum negative pressure biochemical tower includes a tower body 1. The upper part of the tower body 1 is equipped with a feed inlet 2, an exhaust port 3, and a pressure gauge for detecting internal pressure. An exhaust pipe is connected to the exhaust port 3, and a discharge port 4 is located at the lower part of the tower body 1. The inner wall of the tower body 1 is provided with a spirally upward-flowing guide rib 5. The guide rib 5 is made of stainless steel, and its outer surface is coated with a carbide coating to increase its corrosion resistance. The lower surface of the guide rib 5 forms a 15° angle with the inner wall of the tower body 1, and the pitch of the guide rib 5 is 25 cm. During the tumbling and stirring process, the material located at the edge of the tower body 1 moves upward along the guide rib 5, eliminating dead flow angles. As a transverse ring rib, the guide rib 5 can increase the critical buckling pressure of the shell. Simultaneously, the guide rib 5 indirectly restricts axial deformation by constraining the radial displacement of the shell.

[0024] The outer wall of the tower body 1 is equipped with a water bath heating coil 6, which includes an inlet 7 and an outlet 8. Constant temperature water at 50-70 degrees Celsius flows within the water bath heating coil 6 to heat the materials inside the vacuum negative pressure biochemical tower, maintaining the materials at 40-50 degrees Celsius to improve the pretreatment effect. To reduce heat loss, the tower body 1 is equipped with an insulation layer covering the water bath heating coil 6.

[0025] like Figure 3As shown, to prevent a large amount of fine straw from being carried out of the extraction pipe 18 by the airflow, an arc-shaped separation plate 9 is installed inside the extraction pipe 18 via a bracket 17. During installation, the concave surface of the arc-shaped separation plate 9 faces downwards, and a gap is provided between its edge and the wall of the extraction pipe 18 to allow airflow. The radius of curvature R of the arc-shaped separation plate 9 is 1.5D, where D is the diameter of the extraction pipe 18. The lower surface of the arc-shaped separation plate 9 is coated with a tungsten carbide coating. When air is extracted by the vacuum pump 13, the airflow enters the extraction pipe 18 through the extraction port 3. Upon encountering the arc-shaped separation plate 9, the airflow changes direction and flows upwards through the gap at its edge. Solid substances and some liquid droplets in the airflow collide with the lower surface of the arc-shaped separation plate 9, accumulate, and fall back into the vacuum negative pressure biochemical tower, preventing excessive removal of reagents from the biochemical tower. The lower surface of the arc-shaped separation plate 9 is coated with a tungsten carbide coating to increase its wear resistance and corrosion resistance.

[0026] The extraction pipe 18 is connected to a gas-liquid separation device, and the outlet of the gas-liquid separation device is connected to a vacuum pump 13. The gas-liquid separation device further separates the liquid in the gas flow to prevent the reagent from being carried out by the gas flow and affecting the reaction effect.

[0027] The gas-liquid separation device includes a cyclone separator 10 and a wire mesh liquid trapping device 11. The exhaust port 3 of the vacuum negative pressure biochemical tower is connected to the inlet of the cyclone separator 10 via an exhaust pipe 18. The exhaust port of the cyclone separator 10 is connected to the inlet of the wire mesh liquid trapping device 11. The outlet of the wire mesh liquid trapping device 11 is connected to a vacuum pump 13. Both the lower ends of the cyclone separator 10 and the wire mesh liquid trapping device 11 are connected to a water storage tank 12. After the gas flow is extracted through the exhaust pipe 18, it undergoes gas-liquid separation in the cyclone separator 10. The separated liquid flows into the water storage tank 12 for storage. The gas flow further passes through the wire mesh liquid trapping device 11, where fine droplets are further captured by the wire mesh. The collected droplets then flow into the water storage tank 12. The outlet of the vacuum pump 13 is connected to a deodorization tower 14. Finally, the gas is treated by the deodorization tower 14 before being discharged to prevent environmental pollution.

[0028] The water storage tank is connected to the tower body 1 via the infusion pipe 15, the water pump 16 and the solenoid valve. A capacitive liquid level sensor is installed in the water storage tank. The water pump 16, the solenoid valve and the capacitive liquid level sensor are all electrically connected to the control device of the straw pretreatment system. When the liquid level reaches the set value, the liquid in the water storage tank is transported to the tower body 1 by the water pump 16 for reuse.

[0029] To improve the utilization rate of vacuum pump 13 and reduce the system configuration cost, the inlet end of vacuum pump 13 can be connected to multiple sets of vacuum negative pressure biochemical towers via pipelines, and vacuuming can be carried out alternately for different vacuum negative pressure biochemical towers.

[0030] The working process of this straw pretreatment system is as follows: The crushed straw is added into tower body 1 through inlet 2, along with sodium hydroxide solution and a certain amount of water, to achieve a material filling rate of 50%-65% and a moisture content of 60%-75% in tower body 1. Inlet 2 is then closed. Vacuum pump 13 is started, initiating a three-gradient pressurization process. First, a vacuum is drawn until the pressure gauge reading reaches -0.09 MPa, and this pressure is maintained for 30 minutes. Then, the pressure is reduced to -0.07 MPa and maintained for 30 minutes. Finally, the pressure is reduced to -0.06 MPa and maintained for 30 minutes. According to Henry's Law and the Clausius-Clapeyron equation, a 40% volume expansion of the material under negative pressure can create self-circulating turbulent flow. When the material filling rate inside tower 1 is 50%-65% and the moisture content is 60%-75%, and the internal pressure of tower 1 is reduced from atmospheric pressure to -0.09MPa to -0.06MPa, the dissolved gas in the material expands, driving a vortex that causes the material to tumble and stir. During this process, the hot water in the water bath heating coil 6 heats the material to 40-50 degrees Celsius, accelerating the reaction rate. During the vacuuming process, the gas-liquid separation device continuously operates to separate and recover moisture from the gas flow, preventing the reagent from being carried out by the gas flow. If it is necessary to stir the material again, the internal pressure of tower 1 is restored to atmospheric pressure, and the above process is repeated.

[0031] The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower of this utility model is equipped with a vacuum pump 13 and a flow guide rib 5. It utilizes the change in air pressure inside the tower body 1 to cause gas-liquid expansion of the material, thereby generating vortices and forming a self-stirring function. This vacuum negative pressure biochemical tower eliminates the need for a mechanical stirring mechanism, reducing energy consumption and failure rate. An arc-shaped separation plate 9 is installed inside the extraction pipe 18 to prevent a large amount of fine straw from being carried out by the airflow from the extraction pipe 18, and can also initially intercept some large droplets, preventing liquid and chemicals from being carried out.

[0032] The straw pretreatment system connects the exhaust port 3 of the vacuum negative pressure biochemical tower to a gas-liquid separation device via an exhaust pipe 18. The outlet of the gas-liquid separation device is connected to a vacuum pump 13. The gas-liquid separation device further separates the liquid in the gas flow to prevent the reagent from being carried out by the gas flow and affecting the reaction effect. A shared vacuum pump 13 is set up to achieve multiple uses of one pump and reduce the system construction cost.

[0033] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the present invention.

Claims

1. A gas-liquid expansion self-stirring vacuum negative pressure biochemical tower, characterized in that: The tower includes a tower body with a feed inlet and an exhaust outlet at the top and a discharge outlet at the bottom. The outer wall of the tower body is equipped with a water bath heating coil for hot water flow, and the inner wall of the tower body is equipped with guide ribs spiraling upwards from bottom to top.

2. The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower according to claim 1, characterized in that: The angle between the lower surface of the flow guide rib and the tower wall is 10-20°.

3. The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower according to claim 1, characterized in that: The angle between the lower surface of the flow guide rib and the tower wall is 15°.

4. The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower according to claim 1, characterized in that: The pitch of the guide rib is 25cm.

5. The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower according to claim 1, characterized in that: The tower body is equipped with an insulation layer covering the water bath heating coil.

6. The gas-liquid expansion self-stirring vacuum negative pressure biochemical tower according to claim 1, characterized in that: An air extraction pipe is connected to the air extraction port, and an arc-shaped separation plate is installed inside the air extraction pipe. A gap is provided between the edge of the arc-shaped separation plate and the air extraction pipe to allow airflow.

7. A straw pretreatment system, characterized in that: The vacuum negative pressure biochemical tower according to any one of claims 1-6 further includes a gas-liquid separation device and a water storage tank. The gas-liquid separation device includes a cyclone separator and a wire mesh liquid trapping device. The exhaust port of the vacuum negative pressure biochemical tower is connected to the inlet of the cyclone separator via an exhaust pipe. The outlet of the cyclone separator is connected to the wire mesh liquid trapping device. The lower ends of both the cyclone separator and the wire mesh liquid trapping device are connected to the water storage tank. The outlet of the wire mesh liquid trapping device is connected to a vacuum pump.

8. The straw pretreatment system according to claim 7, characterized in that: The water storage tank is connected to the tower body via a delivery pipe, a water pump, and a solenoid valve. A capacitive liquid level sensor is installed inside the water storage tank. When the liquid level reaches a set value, the liquid in the water storage tank is pumped into the tower body for reuse.

9. The straw pretreatment system according to claim 7, characterized in that: The outlet of the vacuum pump is connected to a deodorization tower.

10. The straw pretreatment system according to claim 7, characterized in that: The inlet of the vacuum pump is connected to multiple sets of vacuum negative pressure biochemical towers and gas-liquid separation devices via pipelines, and the vacuum is alternately drawn for different vacuum negative pressure biochemical towers.

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