Anaerobic reactor and method for rapid sludge degassing

Abstract

The application discloses an anaerobic reactor and a method for rapid sludge degassing. The anaerobic reactor comprises a shell with an open top, a water distribution device, a sludge-water lifting device and a biogas flow guide device are sequentially and spacedly arranged in the shell from bottom to top. The water distribution device is connected with a water inlet pipe. The sludge-water lifting device comprises a gas collecting hood and an upward flow pipe connected with the center of the top of the gas collecting hood. The biogas flow guide device comprises a three-phase separator and an exhaust pipe connected with the center of the top of the three-phase separator. The exhaust pipe is connected with a biogas tank. The upward flow pipe extends upward in a spiral shape. The total amount of sludge-water lifted by the sludge-water lifting device is more than 3 times of the water inlet amount. The anaerobic reactor can realize rapid sludge degassing under high load conditions, effectively prevent sludge running of the anaerobic reactor, keep sufficient sludge in the reactor and provide support for efficient and stable operation of the reactor.

Description

Technical Field

[0001] This invention relates to the field of anaerobic reactor technology, and in particular to an anaerobic reactor and method for rapid degassing of sludge. Background Technology

[0002] Sufficient sludge volume is a key factor for the rapid start-up and efficient and stable operation of anaerobic reactors.

[0003] Currently, mainstream anaerobic reactors such as IC, EGSB, and UASB typically operate with bottom inlet and top outlet, and both water and air flow within the reactor are in an upward flow state.

[0004] In anaerobic reactors, biogas exists in the form of bubbles, which vary in size. Large biogas bubbles are typically formed by the merging of multiple smaller bubbles. When anaerobic microorganisms decompose organic matter, the initial biogas produced is small-bubble biogas, which is usually tightly bound to the sludge and difficult to separate. In contrast, large-bubble biogas is more easily released from the sludge. When biogas and sludge are combined, the combined effect of rising water flow and biogas buoyancy within the anaerobic reactor easily leads to sludge runoff. This problem is particularly severe when the anaerobic reactor operates under high load conditions due to the high biogas production intensity. If the sludge runoff problem cannot be effectively solved, the anaerobic reactor will be unable to operate efficiently and stably due to insufficient sludge volume.

[0005] Therefore, rapidly achieving anaerobic sludge degassing is of great significance for effectively alleviating sludge loss in anaerobic reactors and ensuring their efficient and stable operation. Summary of the Invention

[0006] The purpose of this invention is to provide an anaerobic reactor for rapid sludge degassing and its usage method, thereby addressing the problems existing in the prior art. By rapidly degassing the sludge and utilizing the downward flow formed around the sludge lifting device, the lifted sludge is quickly returned, and the bottom sludge layer is pushed up to float, effectively suppressing sludge runoff and providing support for the efficient and stable operation of the anaerobic reactor.

[0007] The objective of this invention is achieved as follows: an anaerobic reactor for rapid degassing of sludge includes a shell with an open top. Inside the shell, a water distribution device, a sludge-water lifting device, and a biogas guiding device are arranged sequentially from bottom to top. The water distribution device is connected to an inlet pipe. The sludge-water lifting device includes a gas collection hood and an ascending pipe connected to the center of the top of the gas collection hood. The biogas guiding device includes a three-phase separator and an exhaust pipe connected to the center of the top of the three-phase separator. The exhaust pipe is connected to a biogas tank. The ascending pipe extends upward in a spiral shape. The total sludge-water lifting capacity of the sludge-water lifting device is more than three times the inlet water volume.

[0008] In an anaerobic reactor where both water and air flow are in an upward flow state and the flow velocity is the same in all parts, this invention uses a specially designed mud-water lifting device to change the mud-water flow state and velocity in different parts of the anaerobic reactor. For example, in addition to the original mud-water upward flow state, a self-circulating flow state and a downward flow state (outside the mud-water lifting device) are also formed. The upward flow velocity of mud, air and water in the upward flow pipe is faster than the flow velocity in other parts.

[0009] Specifically, the anaerobic reactor for rapid sludge degassing of the present invention includes a specially designed sludge-water lifting device installed between the anaerobic reactor's water distribution device and biogas guiding device. Biogas below the sludge-water lifting device is guided into it. Using the density difference formed during the biogas's ascent within the lifting device as power, the sludge-water below the lifting device is lifted to below the three-phase separator, achieving a self-circulation of the lifted sludge-water centered on the lifting device. This achieves two key benefits: first, the strong disturbance generated during the rapid ascent of the sludge-water within the lifting device enables primary separation of sludge and gas; second, the reverse flow of sludge and gas around the lifting device enables secondary separation. By rapidly removing biogas bound to the sludge, sludge runoff is effectively prevented even under high gas production conditions.

[0010] Compared to rod-shaped riser pipes, spiral riser pipes, at the same vertical height, can extend the flow distance of sludge and water within the riser, accelerating the upward flow velocity and enabling regular rotation during the rise. This strengthens the disturbance effect of airflow and water flow on the sludge within the riser pipe, improving degassing efficiency. Even under high-load conditions, when a large amount of biogas is produced within the anaerobic reactor, efficient and stable operation of the reactor can still be achieved.

[0011] In summary, the anaerobic reactor of the present invention can also achieve rapid degassing of anaerobic sludge when operating under high load conditions, effectively preventing sludge loss from the anaerobic reactor, and retaining a sufficient amount of sludge in the reactor, thus providing support for the efficient and stable operation of the reactor.

[0012] As a further improvement of the present invention, the inner diameter of the riser pipe does not exceed 100mm, the vertical height of the riser pipe is more than 1 / 4 of the height of the shell, and the sludge flow velocity in the riser pipe is controlled at more than 30m / h, thereby ensuring that the total sludge lifting volume of the sludge lifting device reaches more than 3 times the inlet water volume, and ensuring the sludge degassing effect.

[0013] As a further improvement of the present invention, the height-to-diameter ratio of the shell is 4 or higher. Compared with reactors with a low height-to-diameter ratio, anaerobic reactors with a high height-to-diameter ratio have better automatic sludge washing and pre-granulation efficiency, and can significantly improve the treatment effect.

[0014] As a further improvement of the present invention, there are several sludge-water lifting devices. The number of sludge-water lifting devices can be increased or decreased according to the size of the effective area of ​​the anaerobic reactor. A first guide vane is provided between the gas collection hoods of the sludge-water lifting device, and a second guide vane is provided between the gas collection hood and the inner wall of the shell, so as to guide the biogas generated below the gas collection hood into the sludge-water lifting device.

[0015] As a further improvement of the present invention, a third guide vane is provided between the three-phase separator and the inner wall of the shell to intercept fine sludge and prevent sludge from escaping.

[0016] This invention also provides a method for rapid degassing of sludge using the above-mentioned anaerobic reactor, comprising the following steps: (1) Add seed sludge into the anaerobic reactor. The amount of seed sludge added is 1 / 3 of the effective volume of the anaerobic reactor, and the gas collection hood is submerged in the seed sludge. (2) The wastewater to be treated is fed into the anaerobic reactor in a continuous flow manner. The anaerobic reactor is started under the condition that the initial influent load is above 0.25 kg COD / (kg VS.d); (3) When the COD removal rate of the anaerobic reactor reaches a stable level of 80% or more, increase the influent load by more than 20% until the design load is reached.

[0017] Based on the structure of the anaerobic reactor of this invention, this method can start the anaerobic reactor under a relatively high initial influent load, and subsequently, as the wastewater treatment efficiency of the anaerobic reactor improves, the influent load can be continuously increased, thereby increasing the gas production intensity of the anaerobic reactor. As the gas production intensity of the anaerobic reactor increases, the total amount of sludge lifted by the sludge-water lifting device also increases. When the gas production intensity of the anaerobic reactor reaches a certain value, the total amount of sludge lifted by the sludge-water lifting device exceeds the influent volume. The portion of the sludge-water lifted by the sludge-water lifting device that exceeds the influent volume forms a downflow around the sludge-water lifting device and flows back into the sludge-water lifting device, forming a self-circulation centered on the sludge-water lifting device. When the influent load reaches the design load, the total amount of sludge lifted by the sludge lifting device is more than three times the influent volume. The strong disturbance generated during the regular and rapid rotation and ascent of the sludge in the spiral upward flow pipe achieves rapid separation of sludge and gas. At the same time, the portion of sludge exceeding the influent volume forms a self-circulation in a local area of ​​the anaerobic reactor, centered on the sludge lifting device, from the inside (rising) to the outside (falling). Utilizing the downward flow formed around the sludge lifting device, the lifted sludge is rapidly returned, and the bottom sludge layer is pushed up and floated, which can effectively suppress sludge loss and provide support for the efficient and stable operation of the anaerobic reactor.

[0018] In summary, this invention effectively prevents sludge runoff by rapidly removing biogas bound to sludge, even under high biogas production conditions. Even under high load conditions, when a large amount of biogas is generated within the anaerobic reactor, the reactor can still operate efficiently and stably.

[0019] In an anaerobic reactor where both water and air flow are in an upward flow state and the flow velocity is the same in all parts, this invention uses a specially designed mud-water lifting device to change the mud-water flow state and velocity in different parts of the anaerobic reactor. For example, in addition to the original mud-water upward flow state, a self-circulating flow state and a downward flow state (outside the mud-water lifting device) are also formed. The upward flow velocity of mud, air and water in the upward flow pipe is faster than the flow velocity in other parts.

[0020] As a further improvement of the present invention, during the start-up and operation of the anaerobic reactor, the gas collection hood is always kept submerged in the seed sludge to ensure the reaction effect.

[0021] As a further improvement of the present invention, the amount of seed sludge added in step (1) is 1 / 3 of the effective volume of the anaerobic reactor to ensure the reaction effect. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the anaerobic reactor for rapid sludge degassing according to the present invention.

[0023] Among them, 1 is the water inlet pipe, 2 is the water distribution device, 3 is the first guide vane, 4 is the second guide vane, 5 is the gas collection hood, 6 is the rising flow pipe, 7 is the third guide vane, 8 is the three-phase separator, 9 is the biogas box, 10 is the water outlet weir, 11 is the seed sludge, and 12 is the included angle of the inclined surface of the gas collection hood. Detailed Implementation

[0024] like Figure 1 The anaerobic reactor for rapid sludge degassing shown includes a shell with an open top. The height-to-diameter ratio of the shell is greater than 4. Compared with reactors with a low height-to-diameter ratio, anaerobic reactors with a high height-to-diameter ratio have better automatic sludge washing and pre-granulation efficiency, which can significantly improve the treatment effect. Inside the shell, from bottom to top, there are water distribution devices 2, sludge-water lifting devices, and biogas guiding devices arranged at intervals. There are several sludge-water lifting devices; the number can be increased or decreased depending on the effective area of ​​the anaerobic reactor. Seed sludge 11 is introduced into the shell.

[0025] The water distribution device 2 is connected to the inlet pipe 1 to introduce the wastewater to be treated. The water distribution device 2 makes the inlet water distribution more uniform, so that the wastewater can react evenly with the seed sludge 11 at the bottom of the anaerobic reactor, reducing the organic matter content in the wastewater. An outlet weir 10 is provided on the top side of the anaerobic reactor to discharge the supernatant after separation.

[0026] The sludge lifting device includes a gas collection hood 5 and an ascending pipe 6 connected to the center of the top of the gas collection hood 5. The gas collection hood has a gradually tapering shape from bottom to top, like an inverted funnel, with an incline angle of less than 60°. A first guide vane 3 is provided between the gas collection hoods 5, and a second guide vane 4 is provided between the gas collection hoods 5 and the inner wall of the shell, to guide the biogas generated below the gas collection hoods 5 into the sludge lifting device. The outlet of the ascending pipe 6 is located below the biogas guiding device and is spaced at a certain distance to prevent fine sludge from being swept into the biogas guiding device by the airflow. The ascending pipe 6 extends upward in a spiral shape. Compared with a rod-shaped ascending pipe, with the same vertical height, the spiral ascending pipe 6 can extend the flow distance of the sludge and water in the ascending pipe, which can accelerate the upward flow velocity of the sludge and water, and achieve regular rotation during the upward process of the sludge and water, thereby strengthening the disturbance effect of the airflow and water flow on the sludge in the ascending pipe.

[0027] The biogas diversion device includes a three-phase separator 8 and an exhaust pipe connected to the center of the top of the three-phase separator 8. The exhaust pipe is connected to the biogas box 9. A third guide vane 7 is provided between the three-phase separator 8 and the inner wall of the shell to intercept fine sludge and prevent sludge from escaping.

[0028] When the gas production intensity remains constant, reducing the inner diameter of the riser pipe 6 can increase the slurry flow velocity within the riser pipe, thereby increasing the total amount of slurry lifted by the slurry lifting device, and vice versa. Similarly, when the gas production intensity remains constant, increasing the vertical height or length of the riser pipe 6 can also increase the slurry flow velocity within the riser pipe, thereby increasing the total amount of slurry lifted by the slurry lifting device, and vice versa. In this embodiment, the inner diameter of the riser pipe 6 does not exceed 100 mm, the vertical height of the riser pipe 6 is more than 1 / 4 of the height inside the shell, and the slurry flow velocity within the riser pipe 6 is controlled at more than 30 m / h, thereby ensuring that the total amount of slurry lifted by the slurry lifting device is controlled at more than 3 times the inlet water volume.

[0029] The rapid degassing method for sludge in the anaerobic reactor of this embodiment includes the following steps: (1) Seed sludge is added to the anaerobic reactor. The amount of seed sludge added is about 1 / 3 of the effective volume of the anaerobic reactor, and the gas collection hood 5 is submerged in the seed sludge during the start-up and operation of the anaerobic reactor. (2) The wastewater to be treated is fed into the anaerobic reactor in a continuous flow manner, with an initial influent load of 0.25 kg COD / (kgVS.d) or higher, and the anaerobic reactor is started. (3) When the COD removal rate of the anaerobic reactor reaches a stable level of over 80%, increase the influent load by more than 20% until the design load is reached.

[0030] Based on the structure of the anaerobic reactor in this embodiment, this method can start the anaerobic reactor under a relatively high initial influent load, and subsequently, as the wastewater treatment efficiency of the anaerobic reactor improves, the influent load can be continuously increased, thereby increasing the gas production intensity of the anaerobic reactor. As the gas production intensity of the anaerobic reactor increases, the total amount of sludge lifted by the sludge-water lifting device also increases. When the gas production intensity of the anaerobic reactor reaches a certain value, the total amount of sludge lifted by the sludge-water lifting device exceeds the influent volume. The portion of the sludge-water lifted by the sludge-water lifting device that exceeds the influent volume forms a downflow around the sludge-water lifting device and flows back into the sludge-water lifting device, forming a self-circulation centered on the sludge-water lifting device. When the influent load reaches the design load, the total amount of sludge lifted by the sludge lifting device is more than three times the influent volume. The strong disturbance generated during the regular and rapid rotation and ascent of the sludge in the spiral rising pipe 6 achieves rapid separation of sludge and gas. At the same time, the portion of sludge exceeding the influent volume forms a self-circulation in the local area of ​​the anaerobic reactor, centered on the sludge lifting device, from the inside (rising) to the outside (falling). Utilizing the descending water flow formed around the sludge lifting device, the lifted sludge is rapidly returned, and the bottom sludge layer is pushed up and floated up, which can effectively suppress sludge loss and provide support for the efficient and stable operation of the anaerobic reactor.

[0031] The rapid sludge degassing method for the anaerobic reactor in this embodiment includes the following sludge degassing pathway: First, the strong disturbance generated during the regular and rapid rotation and ascent of the mud and water within the spiral-shaped ascending pipe 6 is used to achieve the separation of sludge and gas in one step.

[0032] Secondly, by utilizing the reverse flow of sludge descending and gas rising around the sludge lifting device, a secondary separation of sludge and gas is achieved.

[0033] This invention effectively prevents sludge runoff by rapidly removing biogas bound to sludge, even under high biogas production conditions. Even under high load conditions, when a large amount of biogas is generated within the anaerobic reactor, efficient and stable operation of the reactor can be achieved.

[0034] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. An anaerobic reactor for rapid sludge degassing, comprising a shell with an open top, wherein a water distribution device, a sludge-water lifting device, and a biogas guiding device are arranged sequentially from bottom to top within the shell; the water distribution device is connected to an inlet pipe; the sludge-water lifting device includes a gas collection hood and an ascending flow pipe connected to the center of the top of the gas collection hood; the biogas guiding device includes a three-phase separator and an exhaust pipe connected to the center of the top of the three-phase separator; the exhaust pipe is connected to a biogas tank, characterized in that: The rising pipe extends upward in a spiral shape, the total amount of mud and water lifted by the mud and water lifting device is more than 3 times the amount of water entering the tank, the inner diameter of the rising pipe does not exceed 100mm, the vertical height of the rising pipe is more than 1 / 4 of the height of the shell, the mud and water flow velocity in the rising pipe is controlled at more than 30m / h, and the height-to-diameter ratio of the shell is more than 4.

2. The anaerobic reactor for rapid sludge degassing according to claim 1, characterized in that: The mud and water lifting device comprises several units, and a first guide vane is provided between the air collection hoods of the mud and water lifting device, and a second guide vane is provided between the air collection hood and the inner wall of the shell.

3. The anaerobic reactor for rapid sludge degassing according to claim 1, characterized in that: A third guide vane is provided between the three-phase separator and the inner wall of the housing.

4. A method for rapid degassing of sludge, using an anaerobic reactor as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Add seed sludge into the anaerobic reactor. The amount of seed sludge added is more than 1 / 4 of the effective volume of the anaerobic reactor, and the gas collection hood is submerged in the seed sludge. (2) The wastewater to be treated is fed into the anaerobic reactor in a continuous flow manner. The anaerobic reactor is started under the condition that the initial influent load is above 0.25 kg COD / (kgVS.d); (3) When the COD removal rate of the anaerobic reactor reaches a stable level of 80% or more, increase the influent load by more than 20% until the design load is reached.

5. The rapid sludge degassing method according to claim 4, characterized in that: During the start-up and operation of the anaerobic reactor, the gas collection hood was kept submerged in the seed sludge.

6. The rapid degassing method for sludge according to claim 4, characterized in that: In step (1), the amount of seed sludge added is 1 / 3 of the effective volume of the anaerobic reactor.

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