A drainage device and a drainage method

Abstract

The present invention discloses a drainage device, which includes a liquid level control tank, an effluent weir tank, a siphon drain pipe, a high-level effluent pipe and a low-level effluent pipe. Through this drainage device, the present invention realizes the advantages of simultaneous water inlet and outlet without rotating equipment, and can lower the liquid level after the water inlet and outlet are completed. The drainage operation is jointly realized by the drainage weir tank and the siphon drain pipe. By using the change of the liquid level in the liquid level control tank to change the liquid level difference between the inlet and outlet of the siphon drain pipe, the drainage volume of the siphon drain pipe under the liquid surface in the pool body can be automatically adjusted, so as to selectively discharge most of the effluent from the drainage weir tank above the liquid surface in the pool body, thereby optimizing the effluent quality. The drainage volume of the low-level drain pipe can be adjusted by the regulating valve installed on the low-level drain pipe, so as to change the speed of the liquid level change in the liquid level control tank, and flexibly match the drainage volume of the siphon drain pipe to meet the operation requirements of different water inflows.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and particularly relates to a drainage device and a drainage method. Background Art

[0002] The Sequencing Batch Reactor (SBR) is an activated sludge sewage treatment technology that operates in an intermittent aeration mode. The SBR process layout is compact, combining the biochemical reaction tank and the secondary sedimentation tank into one, without the need for sludge return, and has certain technical and economic advantages. When the SBR operates, sewage enters intermittently according to the time sequence, and the reactor operates in a cycle. The cycle is usually set in four stages: influent, aeration, sedimentation, and effluent. In recent years, there have been new application developments in the SBR process. Through the optimization of the operation mode and the regulation of the operation parameters, aerobic granular sludge different from traditional flocculent sludge can be cultivated in the SBR system. The research and application of the aerobic granular sludge (AGS) process have given full play to the technical advantages of the intermittent operation reactor. The excellent sedimentation performance of AGS enables the influent and effluent stages in the SBR operation cycle to be combined and carried out simultaneously. The original cycle setting can be adjusted to simultaneous influent / effluent, aeration, and sedimentation in 3 stages, reducing the non-aeration time and improving the biochemical reaction efficiency within the cycle. The original SBR process first discharges water after the sedimentation stage and then enters water from the top of the reactor; AGS enters water from the bottom of the reactor to the sludge layer after sedimentation, and the treated supernatant is pushed out to the effluent weir at the top of the pool through uniform water distribution for drainage, without taking out the sludge at the same time, realizing simultaneous influent and effluent.

[0003] Simultaneous influent and effluent can also save the decanter used in the drainage stage of the original SBR process, reducing the investment cost and the number of operating equipment. However, after the simultaneous influent and effluent stage of the AGS process is completed, the liquid level in the reactor is at the effluent position of the top effluent weir. The air-lift effect generated during the subsequent aeration stage in the operation cycle will cause the liquid level to rise, resulting in the loss of the unprocessed muddy water mixture from the top effluent weir of the pool, which cannot meet the operation and treatment requirements. Therefore, although the AGS process reduces the decanter of the conventional SBR, an electric decanter device with a relatively shallow decanting depth still needs to be added below the effluent weir to drain the water volume above the air-lift height at the top. In this way, the number of operating equipment and its required electrical control system in the AGS process are not completely reduced, and the operation failure rate is not further reduced.

[0004] To solve the above problems and without adding power equipment, the present invention provides a new drainage device and a drainage method, which have no power equipment, uniform water discharge, and can lower the liquid level to a lower level after the water discharge is completed, so that there will be no loss of muddy water mixture from the top effluent weir during the subsequent aeration stage in the operation cycle. Summary of the Invention

[0005] The object of the present invention is to provide a drainage device without a power-driven device, which is used to achieve the effect that water can be simultaneously introduced from the bottom and discharged from the top, and the liquid level can be reduced to a certain height.

[0006] To achieve the above object, the present invention provides the following technical solution: A drainage device, comprising:

[0007] A liquid level control tank fixedly installed on the inner side wall of the pool body, and a drainage weir tank is fixedly installed on the top of the liquid level control tank; a siphon drainage pipe is communicated with the bottom of one side of the liquid level control tank, and a high-level drainage pipe and a low-level drainage pipe are respectively communicated with one side of the pool body, and the high-level drainage pipe and the low-level drainage pipe are communicated with the liquid level control tank, and the siphon drainage pipe, the high-level drainage pipe and the low-level drainage pipe are interconnected through the liquid level control tank;

[0008] Preferably, the water inlet end of the high-level drainage pipe is communicated with the inside of the liquid level control tank;

[0009] Preferably, the water inlet end of the low-level drainage pipe is communicated with the inside of the liquid level control tank;

[0010] Preferably, the siphon drainage pipe is located inside the pool body;

[0011] Preferably, a water inlet pipe is communicated with the bottom of one side of the pool body;

[0012] Preferably, a regulating valve is fixedly installed on the low-level drainage pipe;

[0013] A drainage method, comprising the following steps:

[0014] Step 1: Place or install the drainage device at the top inside the water treatment pool;

[0015] Step 2: Continuously introduce water into the pool body through the bottom water inlet pipe until the liquid level in the pool body rises to the height of L2 to form a siphon, and the water is discharged into the liquid level control tank through the siphon drainage pipe. When the liquid level in the liquid level control tank reaches the height of L3, start to drain water through the low-level drainage pipe;

[0016] Step 3: The water inflow of the bottom water inlet pipe is greater than the drainage volume of the siphon drainage pipe. Continuously introduce water to make the liquid level in the pool body continue to rise after reaching the height of L2. When the liquid level in the pool body reaches the height of L4, and the liquid level in the liquid level control tank is still L3, the liquid level difference before and after the siphon drainage pipe is the largest, and the siphon drainage volume also reaches the highest value. After the liquid level in the pool body reaches the height of L4, the drainage weir tank also starts to drain water, and the sum of the drainage volumes of the siphon drainage pipe and the drainage weir tank is greater than the drainage volume of the low-level drainage pipe. The liquid level in the liquid level control tank starts to rise, and as the liquid level difference between it and L4 decreases, the drainage volume of the siphon drainage pipe also decreases, and the liquid level in the liquid level control tank gradually rises;

[0017] Step 3: When the liquid level in the liquid level control tank rises to the liquid level height of L5, the high-level drain pipe also starts to drain water, jointly realizing the drainage operation with the low-level drain pipe. The liquid level difference between the pool body and the inside of the liquid level control tank (i.e., before and after the siphon drain pipe) reaches the lowest. At this time, the drainage volume of the siphon drain pipe located below the liquid surface is reduced to the minimum, and the water outlet mainly discharges from the drainage weir trough on the liquid surface, ensuring that during the process of simultaneous water inlet and outlet, as much water as possible is evenly discharged through the highest liquid level with relatively best water quality, maximizing the treatment effect of the reaction device;

[0018] Step 4: When the water inlet is completed, the liquid level in the pool body starts to drop. After the liquid level height is lower than L5, the water outlet from the drainage weir trough stops, and the siphon drain pipe drains water alone. The liquid level in the liquid level control tank also starts to drop until the liquid level height of L3. When the liquid level in the pool body continues to drop to the liquid level height of L1, the siphon is broken and the drainage stops, and the entire water inlet and outlet process is completed.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] Through the setting of this drainage device, the present invention realizes the advantages of meeting the requirements of simultaneous water inlet and outlet without moving equipment, and can lower the liquid level after the water inlet and outlet are completed, without affecting the subsequent treatment process, and without the loss of single-phase electricity and power equipment. At the same time, it can also reduce the capital cost required for equipment, thereby reducing the investment and operation costs of water treatment. Through the joint realization of the drainage operation by the drainage weir trough and the siphon drain pipe, the liquid level difference between the inlet and outlet of the siphon drain pipe is changed by using the change of the liquid level in the liquid level control tank, and the drainage volume of the siphon drain pipe below the liquid surface in the pool body can be automatically adjusted, realizing the selective discharge of most of the water outlet from the drainage weir trough on the liquid surface in the pool body, thereby optimizing the water outlet quality. The drainage volume can be adjusted by the control valve installed on the low-level drain pipe, changing the speed of the liquid level change in the liquid level control tank to meet the operation requirements of different water inlet volumes.

[0021] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures pointed out in the specification and the drawings. Brief Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the present invention;

[0023] Figure 2 It is a schematic diagram of the initial liquid level L1 liquid level height of the present invention;

[0024] Figure 3 It is a schematic diagram of the liquid level rising to the liquid level heights of L2 and L3 of the present invention;

[0025] Figure 4Schematic diagram of the liquid level of the present invention rising to the liquid level heights of L3 and L4;

[0026] Figure 5 Schematic diagram of the liquid level of the present invention rising to the liquid level height of L4;

[0027] Figure 6 Schematic diagram of the liquid level of the present invention rising to the liquid level heights of L4 and L5;

[0028] Figure 7 Schematic diagram of the liquid level height when the liquid level of the present invention drops;

[0029] Figure 8 Schematic diagram of the liquid level of the present invention dropping to the liquid level height of L3;

[0030] Figure 9 Schematic diagram of the liquid level of the present invention dropping to the liquid level height of L1.

[0031] In the figure: 1, drainage weir trough; 2, siphon drainage pipe; 3, liquid level control trough; 4, high-level drainage pipe; 5, low-level drainage pipe; 6, regulating valve; 7, pool body; 8, water inlet pipe. Detailed implementation manner

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0033] The present invention provides a drainage device, which includes a liquid level control trough 3 fixedly installed on the inner side wall of the pool body 7, a water inlet pipe 8 is connected to the bottom on one side of the pool body 7, and a drainage weir trough 1 is fixedly installed on the top of the liquid level control trough 3; a siphon drainage pipe 2 is connected to the bottom on one side of the liquid level control trough 3, a high-level drainage pipe 4 and a low-level drainage pipe 5 are respectively connected to one side of the pool body 7, and the high-level drainage pipe 4 and the low-level drainage pipe 5 are connected to the liquid level control trough 3, and the siphon drainage pipe 2, the high-level drainage pipe 4 and the low-level drainage pipe 5 are interconnected in pairs through the liquid level control trough 3; a regulating valve 6 is fixedly installed in the low-level drainage pipe 5.

[0034] This drainage device realizes the advantages of meeting the requirements of simultaneous water inlet and outlet without moving equipment, and can lower the liquid level after the water inlet and outlet are completed, without affecting the subsequent process; for example, the air-lift effect generated during the aeration process causes the liquid level to rise, resulting in the muddy water mixture flowing out from the water outlet channel and causing non-compliant discharge. At the same time, during the drainage process, most of the effluent can be selectively discharged from the drainage weir trough on the liquid surface in the pool body, and the effluent quality can be optimized through high-(liquid)-level drainage.

[0035] Among them, the water inlet end of the high-level drain pipe 4 is communicated with the inside of the liquid level control tank 3, and the water inlet end of the low-level drain pipe 5 is communicated with the inside of the liquid level control tank 3, which facilitates the drainage treatment of the water entering the liquid level control tank 3 by using the low-level drain pipe 5 and the high-level drain pipe 4.

[0036] The liquid level control tank 3 is used to collect the water discharged from the drainage weir tank 1 and the siphon drain pipe 2. During the drainage process, as the liquid level in the liquid level control tank 3 rises, the liquid level difference between the inlet and outlet of the siphon drain pipe 2 is reduced. Thus, during the drainage process, the amount of water discharged from the siphon drain pipe 2 with a relatively low liquid level is automatically reduced, and most of the discharged water is discharged from the drainage weir tank 1 with a uniformly distributed highest liquid level point. Since the bottom water inlet method is adopted during the water inlet and outlet process, the sludge layer deposited at the bottom will gradually rise due to the disturbance of the inlet water. The higher the liquid level of the discharged water, the less interference from the suspended sludge, and the relatively better the water quality. Therefore, increasing the proportion of the drainage volume at the highest liquid level point of the discharged water can effectively improve the water quality of the discharged water;

[0037] The drainage weir tank 1 uniformly collects the discharged water that needs to be discharged, avoiding short-circuit flow, and discharges the discharged water from the top of the tank to the liquid level control tank 3;

[0038] The high-level drain pipe 4 can also play an overflow role. If the low-level drain pipe 5 is blocked, all the discharged water will be discharged from the high-level drain pipe 4. Therefore, when designing the high-level drain pipe 4, its pipe diameter should be designed with the maximum drainage volume to ensure that the device will not overflow during operation.

[0039] In addition, the siphon drain pipe 2 is located inside the pool body 7, and one end of the drainage weir tank 1 is inclined. The main function of the siphon drain pipe 2 is to perform drainage operations using the siphon principle, and the inclined setting of the drainage weir tank 1 can ensure the directional diversion effect when the liquid level overflows the inside of the drainage weir tank 1.

[0040] Based on the above, the drainage device of the present invention is mainly applied in the field of water treatment, and is used for a water treatment pool or reaction device that can simultaneously perform bottom water inlet and top water outlet, and needs to lower the liquid level to a certain height after the water inlet is completed; and is particularly suitable for an aerobic granular sludge reaction device with simultaneous bottom water inlet and top water outlet. Its main advantage is that the drainage device can meet the requirements of simultaneous water inlet and outlet without rotating equipment, and can lower the liquid level after the water inlet and outlet are completed, without affecting the subsequent process (such as the liquid level rising caused by aeration, resulting in the muddy water mixture flowing out from the water outlet channel and causing non-compliant discharge).

[0041] The drainage process of the drainage device of the present invention is specifically as follows:

[0042] Through the liquid level difference formed by the change of the liquid level in the liquid level control tank 3, the drainage volume of the siphon drain pipe 2 can be automatically adjusted, so that most of the discharged water is discharged from the top of the tank through the more uniformly distributed drainage weir tank 1, improving the water quality of the discharged water;

[0043] By adjusting the opening degree of the regulating valve 6, the rate of change of the drainage volume of the siphon drain pipe 2 can be adjusted, so as to adapt to the size of different water inflows, and make as much effluent as possible drain out from the drainage weir trough 1;

[0044] By adjusting the opening degree of the regulating valve 6, the drainage volume of the low-level drain pipe 5 can be controlled, and then the rising and falling speeds of the liquid level in the liquid level control tank 3 can be changed. According to the needs of the process operation, it can be in Figure 6 , Figure 7 and Figure 8 During the operation process (i.e., when the liquid level in the liquid level control tank drops) when there is sufficient time, the regulating valve is closed slightly, such as Figure 3 , Figure 4 and Figure 5 During the process (i.e., when the liquid level in the liquid level control tank rises), the time is as short as possible, and the effect that the effluent can quickly flow out from the top drainage weir trough 1 of the pool can be achieved, thereby improving the effluent quality.

[0045] The specific usage method is as follows:

[0046] During the entire water inlet and outlet process as Figure 2 shown, the drainage device is placed in the water treatment pool or reactor.

[0047] As Figure 2 shown, the initial liquid level in the pool body 7 is at the L1 height, and bottom water inlet starts from the water inlet pipe 8, and the liquid level in the pool body gradually rises accordingly;

[0048] As Figure 3 shown, when the liquid level in the pool body 7 rises to the L2 height, siphon formation occurs, and the effluent is discharged to the liquid level control tank 3 by the siphon drain pipe 2 and then discharged through the low-level drain pipe 5. At this time, the liquid level height of the liquid level control tank 3 is L3;

[0049] As Figure 4 shown, the liquid level in the pool body 7 continues to rise to the L4 height. Due to the increase in the liquid level, the liquid level difference before and after the siphon drain pipe 2 also increases, and the amount of effluent discharged to the liquid level control tank 3 increases. At the same time, the drainage weir trough 1 starts to drain water;

[0050] As Figure 5 shown, the liquid level in the pool body 7 continues to remain at the L4 height. The sum of the drainage volumes of the siphon drain pipe 2 and the drainage weir trough 1 is greater than the drainage capacity of the low-level drain pipe 5. The liquid level in the liquid level control tank 3 starts to rise, and the liquid level difference between it and L4 starts to decrease, and the drainage volume of the siphon drain pipe 2 decreases accordingly;

[0051] As Figure 6As shown, the liquid level in the pool body 7 continues to remain at the height of L4. The liquid level in the liquid level control tank 3 begins to rise to the height of L5, and the high-level drain pipe 4 starts to discharge water. At this time, the liquid level difference between L5 and L4 is the lowest, the drainage volume of the siphon drain pipe 2 is reduced to the minimum, and the water outlet mainly discharges from the drainage weir tank 1, ensuring that the water outlet is evenly discharged through the highest liquid level to the greatest extent;

[0052] As Figure 7 shown, after the water inlet is completed, the liquid level in the pool body 7 begins to drop, the water outlet of the drainage weir tank 1 stops discharging, and the water is drained through the siphon drain pipe 2. The liquid level in the liquid level control tank 3 also begins to drop;

[0053] As Figure 8 shown, the liquid level in the pool body 7 continues to drop, and continues to be drained through the siphon drain pipe 2. The liquid level in the liquid level control tank 3 drops to the liquid level of L3;

[0054] As Figure 9 shown, the liquid level in the pool body 7 drops to the position of the pipe orifice of the siphon inlet pipe 2 (i.e., L1), the siphon is broken, and the drainage stops. The entire water inlet and outlet process is completed.

[0055] Based on the above, it is possible to meet the requirements of simultaneous water inlet and outlet without power-driven equipment, and it has the advantages of being able to lower the liquid level after the water inlet and outlet are completed, without affecting the subsequent process (such as the liquid level rising caused by aeration, resulting in the muddy water mixture flowing out from the water outlet channel and causing non-compliant discharge.

[0056] At the same time, during the drainage process, most of the water outlet is selectively discharged from the drainage weir tank on the liquid surface in the pool body, and the water quality of the water outlet is optimized through high-(liquid) level drainage.

[0057] A drainage method includes the following steps:

[0058] Step 1: Place or install the drainage device at the top in the water treatment pool;

[0059] Step 2: Continuously introduce water into the pool body through the bottom water inlet pipe until the liquid level in the pool body rises to the height of L2 and then a siphon is formed. The water outlet is discharged into the liquid level control tank through the siphon drain pipe. When the liquid level in the liquid level control tank reaches the height of L3, the low-level drain pipe starts to drain water;

[0060] Step 3: The water inflow of the bottom water inlet pipe is greater than the water discharge of the siphon drain pipe. Continuous water inflow causes the liquid level in the tank to reach and then rise above the L2 height. When the liquid level in the tank reaches the L4 height and the liquid level in the liquid level control tank remains at L3, the liquid level difference before and after the siphon drain pipe is the largest, and the siphon water discharge also reaches the highest value. After the liquid level in the tank reaches the L4 height, the drainage weir tank also starts to drain water, and the sum of the water discharges of the siphon drain pipe and the drainage weir tank is greater than the water discharge of the low-position drain pipe. The liquid level in the liquid level control tank starts to rise. As the liquid level difference between it and L4 decreases, the water discharge of the siphon drain pipe also decreases, and the liquid level in the liquid level control tank gradually rises;

[0061] Step 3: When the liquid level in the liquid level control tank rises to the L5 height, the high-position drain pipe also starts to drain water, jointly realizing the drainage operation with the low-position drain pipe. The liquid level difference between the tank and the inside of the liquid level control tank (i.e., before and after the siphon drain pipe) reaches the lowest. At this time, the water discharge of the siphon drain pipe under the liquid surface is reduced to the minimum, and the water outlet mainly discharges from the drainage weir tank above the liquid surface, ensuring that during the simultaneous water inflow and outflow process, as much water as possible is evenly discharged through the highest liquid level with relatively the best water quality, maximizing the treatment effect of the reaction device;

[0062] Step 4: When the water inflow is completed, the liquid level in the tank starts to drop. After the liquid level height is lower than L5, the water discharge from the drainage weir tank stops, and the siphon drain pipe drains water alone. The liquid level in the liquid level control tank also starts to drop until it reaches the L3 height. When the liquid level in the tank continues to drop to the L1 height, the siphon is broken and the drainage stops, and the entire water inflow and outflow process is completed.

[0063] The core of siphon drainage lies in using the height difference at the connection and the gravitational potential energy of the falling water with the height difference to create a local vacuum in the pipeline, enabling the water flow in the pipe to obtain additional pressure and form a siphon phenomenon. This way of utilizing the siphon effect greatly speeds up the water flow rate in the drain pipe, thus achieving rapid drainage;

[0064] The application of siphon drainage not only improves the drainage efficiency but also simplifies the installation process, meeting the requirements of modern water treatment and should be widely applied. Since the water inlet is facing downwards, the sludge precipitated after aeration will not accumulate in the siphon pipe, ensuring the stability of the effluent water quality. In addition, compared with the traditional siphon drainage method, in addition to the function of reducing the liquid level after simultaneous water inflow and outflow, the drainage device of the present invention, through the settings of the liquid level control tank, high-position drain pipe and low-position drain pipe, can also use the drainage weir tank and the siphon drain pipe to drain water simultaneously, and can automatically adjust the water discharges of the water outlet weir tank and the siphon drain pipe, realizing that as much water as possible is discharged from the liquid surface of the tank with the best water quality through the water outlet weir tank during the entire drainage process, improving the effluent water quality of the reactor.

[0065] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A drainage device, characterized in that: include: A liquid level control groove (3) fixedly mounted on the inner wall of the tank body (7), wherein a drainage weir groove (1) is fixedly mounted on the top of the liquid level control groove (3); The bottom of one side of the liquid level control tank (3) is connected to a siphon drain pipe (2), and one side of the tank body (7) is respectively connected to a high-level drain pipe (4) and a low-level drain pipe (5), and the high-level drain pipe (4) and the low-level drain pipe (5) are connected to the liquid level control tank (3), and the siphon drain pipe (2), the high-level drain pipe (4) and the low-level drain pipe (5) are mutually connected in pairs through the liquid level control tank (3); The water inlet end of the high-level drainage pipe (4) is in communication with the interior of the liquid level control tank (3); The water inlet end of the low-level drainage pipe (5) is in communication with the interior of the liquid level control tank (3); The siphon drain pipe (2) is located inside the pool body (7); The bottom of one side of the pool body (7) is connected to a water inlet pipe (8); A regulating valve (6) is fixedly installed on the low-level drainage pipe (5); The water inflow of the water inlet pipe (8) is greater than the water discharge of the siphon discharge pipe (2); After the liquid level in the tank body (7) reaches the liquid level height L4, the drainage weir (1) starts to drain water, and the sum of the drainage volume of the siphon drainage pipe (2) and the drainage weir (1) is greater than the drainage volume of the low-level drainage pipe (5); The liquid level control trough (3) is used to collect the outflow water from the drainage weir trough (1) and the siphon drainage pipe (2). During the drainage process, the liquid level of the liquid level control trough (3) is increased to reduce the liquid level difference between the inflow and outflow water of the siphon drainage pipe (2), thereby automatically reducing the amount of water discharged from the siphon drainage pipe (2) with a relatively low liquid level during the drainage process, and allowing most of the outflow water to be discharged from the drainage weir trough (1) where the liquid level is evenly distributed at the highest point.

2. A drainage method, according to the drainage device of claim 1, comprising the following steps: Step 1: Install the drainage device at the top of the pool body (7); Step 2: water is continuously introduced into the tank body (7) through the water inlet pipe (8); when the liquid level in the tank body (7) gradually rises to a liquid level height of L2, a siphon is formed; the water to be discharged from the tank body (7) is discharged into the liquid level control tank (3) through the siphon drainage pipe (2); when the liquid level in the liquid level control tank (3) reaches a liquid level height of L3, the water is discharged to the outside of the tank body (7) through the low-level drainage pipe (5); Step 3: the water inflow of the water inlet pipe (8) is greater than the water discharge of the siphon drainage pipe (2), and the water continues to flow in until the liquid level in the tank body (7) reaches the liquid level height L2 and then continues to rise. When the liquid level in the tank body (7) reaches the liquid level height L4 and the liquid level in the liquid level control tank (3) is still at the liquid level height L3, the liquid level difference before and after the siphon drainage pipe (2) is the largest, and the siphon drainage volume also reaches the maximum value; After the liquid level in the tank body (7) reaches the liquid level height L4, the drainage weir (1) starts to drain water, and the sum of the drainage volume of the siphon drainage pipe (2) and the drainage weir (1) is greater than the drainage volume of the low-level drainage pipe (5); The liquid level in the liquid level control tank (3) begins to rise. As the liquid level difference between the liquid level in the liquid level control tank (3) and the liquid level height of L4 decreases, the drainage volume of the siphon drainage pipe (2) also decreases, and the liquid level in the liquid level control tank (3) gradually increases. Step 4: When the liquid level in the liquid level control tank (3) rises to the liquid level height L5, the high-level drainage pipe (4) also starts to drain water, and together with the low-level drainage pipe (5) realizes the drainage operation. The difference between the liquid level of the tank body (7) and the liquid level in the liquid level control tank (3) reaches the minimum. At this time, the drainage volume of the siphon drainage pipe (2) located below the liquid surface is reduced to the minimum, and the outflow water is mainly discharged from the drainage weir groove (1) above the liquid surface. Step 5: After the water is inletted, the liquid level in the tank body (7) begins to drop, the water outflow from the drainage weir (1) stops, and the siphon drainage pipe (2) drains water independently; The liquid level in the liquid level control tank (3) also starts to drop until it reaches the liquid level height L3. When the liquid level in the tank body (7) continues to drop to the liquid level height L1, the siphon is destroyed, drainage stops, and the entire water inlet and outlet process is completed.

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