Nitrification and denitrification system

Abstract

The utility model relates to the technical field of sewage treatment systems, solves the problem that sludge accumulated in a plate heat exchanger is inconvenient to treat in the prior art, and discloses a nitrification and denitrification system which comprises a nitrification tank, a denitrification tank, a plate heat exchanger and a cooling tower, the nitrification tank is provided with a liquid inlet pipe, and the liquid inlet pipe is provided with a first valve body; the denitrification tank is provided with a liquid discharge pipe; the cooling tower is provided with a cold water pipe and a return pipe; wherein the cold water pipe is communicated with a branch pipe, the branch pipe is communicated with the liquid inlet pipe, a second valve body is arranged at the joint of the cold water pipe and the branch pipe, and a third valve body is arranged at the joint of the branch pipe and the liquid inlet pipe. According to the application, the cooling liquid can enter the plate heat exchanger to wash sludge deposited in the plate heat exchanger. Therefore, the tedious process of disassembling and cleaning the plate sheets of the plate heat exchanger is avoided, the labor cost is reduced, the maintenance cost is reduced, and the maintenance efficiency of the plate heat exchanger is improved.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment systems, and in particular to a nitrification and denitrification system. Background Art

[0002] The AO process is also called the anaerobic-aerobic process. A (Anaerobic) is the anaerobic section, which is used for nitrogen and phosphorus removal; O (Oxic) is the aerobic section, which is used to remove organic matter from water. The AO process usually carries out an anoxic biological treatment process before the aerobic activated sludge treatment system. In the aerobic section, aerobic microorganisms oxidize and decompose BOD5 in the sewage, and at the same time carry out nitrification reaction. Organic nitrogen and ammonia nitrogen are converted into nitrified nitrogen in the aerobic section and flow back to the anoxic section. The denitrifying bacteria use the combined nitrogen and the organic carbon in the sewage to carry out denitrification reaction, turning the combined nitrogen into molecular nitrogen, and removing carbon and hydrogen at the same time. Because the nitrification reaction generally occurs at a lower temperature, it is easy to release heat and the reaction is difficult to control.

[0003] In the prior art, plate heat exchangers are used to cool down the water body of the nitrification reaction. Plate heat exchangers are new high-efficiency heat exchangers made of stacked metal plates with a certain corrugated shape. The structural components include plates, gaskets, clamping plates, frames, and clamping bolts. Thin rectangular channels are formed between the plates. The plates are sealed and guided by sealing gaskets to separate the cold and hot fluid channels. The cold and hot heat exchange media flow through their respective channels and exchange heat with the separated plates to reach the temperature required by the user.

[0004] Regarding the above-mentioned related technologies, plate heat exchangers are used for cooling in nitrification and denitrification reactions. Since the reaction will produce sludge, the plate heat exchanger will be blocked by sludge after long-term use, resulting in poor heat exchange effect. The plates need to be disassembled for cleaning, which is time-consuming and labor-intensive. Utility Model Content

[0005] In order to improve the problem of inconvenience in treating sludge accumulated in a plate heat exchanger in the prior art, the present application provides a nitrification and denitrification system.

[0006] The following technical solutions are adopted:

[0007] A nitrification and denitrification system comprises a nitrification tank, a denitrification tank, a plate heat exchanger and a cooling tower, wherein the nitrification tank delivers water into the plate heat exchanger through a liquid inlet pipe, and the liquid inlet pipe is provided with a first valve body; the denitrification tank is connected to the water discharge part of the plate heat exchanger through a liquid discharge pipe; the cooling tower delivers cooling liquid into the plate heat exchanger through a cold water pipe, and refluxes the cooling liquid from the plate heat exchanger into the tower through a reflux pipe; wherein the cold water pipe is connected with a branch pipe, the branch pipe is connected with the liquid inlet pipe, a second valve body is provided at the connection between the cold water pipe and the branch pipe, and a third valve body is provided at the connection between the branch pipe and the liquid inlet pipe.

[0008] By adopting the above technical solution, several valve bodies are controlled to connect the cold water pipe, branch pipe and liquid inlet pipe, the coolant is output from the cooling tower, the branch pipe inputs the coolant into the liquid inlet pipe, and enters the plate heat exchanger to flush the sludge accumulated in the plate heat exchanger. The sludge and cooling water mixture after flushing is discharged into the denitrification tank through the drain pipe, and the sludge is denitrified. In this way, the cumbersome process of disassembling the plate heat exchanger and taking out the plates for cleaning is avoided, the labor cost is reduced, the maintenance cost is reduced, and the maintenance efficiency of the plate heat exchanger is improved.

[0009] Optionally, a pressure pump is provided on the cold water pipe.

[0010] By adopting the above technical solution, when the branch pipe flushes the plate heat exchanger, the water pressure is higher, thereby increasing the maintenance efficiency of the plate heat exchanger.

[0011] Optionally, the cooling tower is provided with a water increase pipe, the water increase pipe is connected to the cold water pipe, and a fourth valve body is provided on the water increase pipe.

[0012] By adopting the above technical solution, when the branch pipe flushes the plate heat exchanger, the water pressure is higher, thereby increasing the maintenance efficiency of the plate heat exchanger.

[0013] Optionally, a filter is provided on the liquid inlet pipe.

[0014] By adopting the above technical solution, sludge is prevented from entering the plate heat exchanger.

[0015] Optionally, the nitrification tank is provided with a liquid outlet pipe, one end of the liquid outlet pipe is connected to the nitrification tank, and the other end is connected to the water discharge part of the plate heat exchanger, a fifth valve body is provided on the liquid outlet pipe, the drain pipe is connected to the liquid outlet pipe, and the drain pipe is provided with a sixth valve body.

[0016] By adopting the above technical solution, the water in the plate heat exchanger is returned to the nitrification tank to adjust the temperature of the nitrification tank.

[0017] Optionally, a plurality of injection pipes are provided in the denitrification pool, and the plurality of injection pipes are all connected to the drainage pipe, and a plurality of spray holes are arranged in an array on the injection pipes.

[0018] By adopting the above technical solution, the bottom of the denitrification area is hydraulically disturbed through the injection pipe to reduce the sludge deposition rate.

[0019] Optionally, the injection pipe is provided with a plurality of reducing pipes connected to the corresponding injection holes.

[0020] By adopting the above technical solution, the denitrification bottom is hydraulically disturbed by using the injection pipe in combination with the reducer to reduce the sludge deposition rate.

[0021] Optionally, the second valve body is a three-way valve.

[0022] In summary, the present application includes at least one of the following beneficial effects:

[0023] 1. Control several valves to allow coolant to enter the plate heat exchanger to flush out the sludge accumulated in the plate heat exchanger. This avoids the tedious process of disassembling and cleaning the plates of the plate heat exchanger, reduces labor costs, reduces maintenance costs, and improves the maintenance efficiency of the plate heat exchanger;

[0024] 2. Use the injection pipe to hydraulically disturb the bottom of the denitrification system to reduce the sludge deposition rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the overall structure of this embodiment;

[0026] Figure 2 It is a schematic diagram of the enlarged structure at A;

[0027] Figure 3 The schematic diagram of the injection pipe cross-section structure.

[0028] Explanation of the reference numerals: 1. nitrification tank; 11. liquid inlet pipe; 111. first valve body; 112. filter; 12. liquid outlet pipe; 121. fifth valve body; 2. denitrification tank; 21. liquid discharge pipe; 211. sixth valve body; 22. injection pipe; 221. spray hole; 222. reducer; 3. plate heat exchanger; 4. cooling tower; 41. cold water pipe; 411. second valve body; 42. booster pump; 43. branch pipe; 431. third valve body; 44. water increase pipe; 441. fourth valve body; 45. reflux pipe. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1 To Attachment Figure 3 This application is described in further detail.

[0030] Reference Figure 1 The embodiment of the present application discloses a nitrification and denitrification system, including a nitrification tank 1, a denitrification tank 2, a plate heat exchanger 3 and a cooling tower 4.

[0031] Nitrification tank 1 is a tank body with nitrifying agents. Nitrifying agents are generally selected from autotrophic microorganisms nitrite bacteria and nitrate bacteria (hereinafter collectively referred to as nitrifying bacteria). Under aerobic conditions, ammonia nitrogen in wastewater is converted into NO2 and NO3 under the action of nitrifying bacteria. It is worth noting that the nitrification tank 1 should maintain an appropriate temperature of 20~35℃.

[0032] Denitrification pool 2 is a pool body with denitrification agents, which are heterotrophic microorganisms (hereinafter referred to as denitrifying bacteria). In the anoxic state, NO2 and NO3 in the wastewater are reduced to N2 under the action of denitrifying bacteria. In the denitrification process of biological denitrification, a certain amount of carbon source is required to ensure a certain carbon-nitrogen ratio so that the denitrification reaction can proceed smoothly. The most suitable pH value for denitrification is 8~8.6. If the pH value is higher than 8.6 or lower than 6, the denitrification rate will drop significantly. It is worth noting that the most suitable temperature for denitrification is 20~40℃. If it is lower than 5℃ or higher than 40℃, the denitrification effect will almost stop.

[0033] The plate heat exchanger 3 is an existing technology, which is generally made of stacked metal plates with a certain corrugated shape. The structural components include plates, gaskets, clamping plates (movable clamping plates and fixed clamping plates), frames (upper and lower guide rods, front pillars), and clamping bolts. Thin rectangular channels are formed between the plates. The plates are sealed and diverted by sealing gaskets to separate the cold and hot fluid channels. The cold and hot heat exchange media flow through their respective channels and exchange heat with the separated plates to achieve the temperature required by the user. The plate heat exchanger is made of many thin plates with special corrugated shapes at a certain interval, sealed by gaskets on all sides, and overlapped and compressed with frames and compression spirals. The four corner holes of the plates and gaskets form the distribution pipes and collection pipes of the fluid, and at the same time, the cold and hot fluids are reasonably separated so that they flow in the flow channels on both sides of each plate respectively, and heat exchange is carried out through the plates.

[0034] Reference Figure 1 and Figure 2 The nitrification tank 1 is provided with an inlet pipe 11, and a first valve body 111 is provided at one end of the inlet pipe 11 close to the nitrification tank 1. The inlet pipe 11 is connected to the hot water flow channel inlet of the plate heat exchanger 3. A filter 112 is provided on the inlet pipe 11, and the filter 112 is a prior art and will not be described here. The filter 112 is used to block most of the sludge from entering the plate heat exchanger 3 to extend the service life of the plate heat exchanger 3. The denitrification tank 2 is provided with a drain pipe 21, and the drain pipe 21 is connected to the hot water flow channel outlet of the plate heat exchanger 3. The inlet pipe 11 is connected to a lifting water pump, and the inlet pipe 11 sends the water in the nitrification tank 1 into the plate heat exchanger 3. After the water is cooled by the plate heat exchanger 3, the water is discharged to the denitrification tank 2 through the drain pipe 21. The cooling tower 4 is provided with a cold water pipe 41 and a reflux pipe 45, and the cooling tower 4 is provided with a lifting pump for lifting and outputting the coolant. The cold water pipe 41 is connected to the cold water flow channel inlet of the plate heat exchanger 3, and the return pipe 45 is connected to the cold water flow channel outlet of the plate heat exchanger 3. The coolant is input into the plate heat exchanger 3 through the cold water pipe 41, and heat exchange is performed through the plates, thereby reducing the water temperature. The coolant is preferably water. The coolant after heat exchange is returned to the cooling tower 4 through the return pipe 45 for reuse.

[0035] Reference Figure 1 and Figure 2 Furthermore, a branch pipe 43 is connected to the cold water pipe 41, and one end of the branch pipe 43 away from the cold water pipe 41 is connected to the liquid inlet pipe 11, and a second valve body 411 for controlling the opening and closing of the branch pipe 43 is provided at the connection between the cold water pipe 41 and the branch pipe 43. The second valve body 411 is a three-way valve, and a third valve body 431 for controlling the opening or closing of the branch pipe 43 is provided at the connection between the liquid inlet pipe 11 and the branch pipe 43. The second valve body 411 and the third valve body 431 are initially in a closed state. When the nitrification tank 1 is shut down, the first valve body 111 is closed to cut off the connection between the liquid inlet pipe 11 and the nitrification tank 1, the third valve body 431 is opened, the second valve body 411 is connected to the cold water pipe 41 and the branch pipe 43, the coolant is output from the cooling tower 4, and is redirected by the second valve body 411 through the cold water pipe 41, and enters the branch pipe 43, the branch pipe 43 inputs the coolant into the liquid inlet pipe 11, and enters the plate heat exchanger 3, and the sludge accumulated in the plate heat exchanger 3 is flushed. The sludge and cooling water mixture after flushing is discharged into the denitrification tank 2 through the drain pipe 21, and the sludge is denitrified. In this way, the cumbersome process of disassembling the plate heat exchanger 3 and taking out the plates for cleaning is avoided, and the maintenance efficiency of the plate heat exchanger 3 is improved.

[0036] Reference Figure 1 and Figure 2 Further, the cold water pipe 41 is provided with a booster pump 42, and the booster pump 42 increases the water pressure, so that when the branch pipe 43 flushes the plate heat exchanger 3, the water pressure is higher, thereby increasing the maintenance efficiency of the plate heat exchanger 3. In the initial state, the booster pump 42 does not operate.

[0037] Reference Figure 1 and Figure 2 Furthermore, the cooling tower 4 is provided with a water increase pipe 44, which is connected to the cold water pipe 41, and a fourth valve body 441 is provided on the water increase pipe 44 for controlling the opening or closing of the water increase pipe 44. When the plate heat exchanger 3 needs to be flushed, the fourth valve body 441 is opened to connect the water increase pipe 44 with the cold water pipe 41, thereby increasing the water flow in the cold water pipe 41, so that the branch pipe 43 has a higher water volume when flushing the plate heat exchanger 3, thereby increasing the maintenance efficiency of the plate heat exchanger 3.

[0038] Reference Figure 1 and Figure 2Furthermore, the nitrification tank 1 is also provided with a liquid outlet pipe 12, one end of the liquid outlet pipe 12 is connected to the nitrification tank 1, and the other end is connected to the hot water flow channel outlet of the plate heat exchanger 3. The nitrification tank 1 returns the water from the plate heat exchanger 3 to the tank through the liquid outlet pipe 12. The liquid outlet pipe 12 is provided with a fifth valve body 121 for controlling its opening or closing, and the fifth valve body 121 is arranged at one end of the liquid outlet pipe 12 close to the nitrification tank 1. The drain pipe 21 in the denitrification tank 2 is connected to the liquid outlet pipe 12, and the denitrification tank 2 is connected to the hot water flow channel outlet of the plate heat exchanger 3 through the drain pipe 21 and the liquid outlet pipe 12. The drain pipe 21 is provided with a sixth valve body 211 for controlling its opening or closing, and the sixth valve body 211 is arranged at one end of the drain pipe 21 close to the denitrification tank 2. In the initial state, the fifth valve body 121 is closed so that the connection between the liquid outlet pipe 12 and the nitrification tank 1 is closed, and the water flows into the denitrification tank 2. When the temperature of the nitrification tank 1 needs to be adjusted, the fifth valve body 121 is opened and the sixth valve body 211 is closed. At this time, the water is discharged from the plate heat exchanger 3 and directly enters the nitrification tank 1 through the liquid outlet pipe 12 to adjust the temperature of the nitrification tank 1.

[0039] Reference Figure 1 and Figure 3 Furthermore, a plurality of injection pipes 22 are arranged along the length direction in the denitrification tank 2, and the plurality of injection pipes 22 are arranged parallel to the plane where the inner wall of the bottom of the denitrification tank 2 is located. One end of the plurality of injection pipes 22 is connected to the drainage pipe 21, and the other end extends in a direction away from the drainage pipe 21. A plurality of spray holes 221 are arranged in an array at the bottom of the injection pipe 22, and water enters the denitrification tank 2 through the spray holes 221. In this way, the water or backwash water is used to hydraulically disturb the bottom of the denitrification tank 2 to reduce the sludge deposition rate.

[0040] Reference Figure 1 and Figure 3 Furthermore, each of the spray holes 221 of the injection pipe 22 is connected to a reducer 222. One end of the reducer 222 is connected to the injection pipe 22, and the other end extends downward. The diameter of the reducer 222 decreases from near the injection pipe 22 to the far side. By reducing the diameter of the concentric reducer 222, the flow rate is ensured while the outlet water pressure is increased, the bottom of the denitrification tank 2 is hydraulically disturbed, the sludge deposition rate of the denitrification tank 2 is reduced, and the system operation condition is ensured.

[0041] The implementation principle of a nitrification and denitrification system in the present application embodiment is:

[0042] The initial state is the original working state. At this time, the nitrification tank 1 sends the water into the plate heat exchanger 3 through the liquid inlet pipe 11. After the water is cooled by the plate heat exchanger 3, the water is discharged into the denitrification tank 2 through the liquid outlet pipe 12 and the liquid discharge pipe 21 in turn. Among them, the cooling tower 4 inputs the coolant into the plate heat exchanger 3 through the cold water pipe 41, and performs heat exchange through the plates, thereby reducing the temperature of the water. The coolant after heat exchange flows back to the cooling tower 4 through the reflux pipe 45 for reuse. Since the injection pipe 22 is installed at the bottom of the denitrification tank 2, the water body hydraulically disturbs the bottom of the denitrification tank, reducing the sludge deposition rate.

[0043] The regulating state is used to regulate the temperature in the nitrification pool 1. A number of valve bodies are controlled so that the drain pipe 21 is closed, the outlet pipe 12 is connected to the nitrification pool 1, and the rest remains unchanged. The water is discharged from the plate heat exchanger 3 and directly enters the nitrification pool 1 through the outlet pipe 12 to regulate the temperature of the nitrification pool 1.

[0044] The backwash state is used to flush the sludge in the plate heat exchanger 3. Several valve bodies are controlled so that the branch pipe 43 is connected to the liquid inlet pipe 11, and the water increase pipe 44 is connected to the cold water pipe 41, the booster pump 42 is started, the liquid inlet pipe 11 is disconnected from the nitrification tank 1, and the liquid outlet pipe 12 and the liquid discharge pipe 21 are connected to the denitrification tank 2. At this time, the cooling tower 4 sends the coolant to the booster pump 42 through the water increase pipe 44 and the cold water pipe 41 in turn, and the pressurized coolant is sent to the plate heat exchanger 3 through the liquid inlet pipe 11 to clean the sludge in the plate heat exchanger 3, and the sludge and cooling water mixture is sent to the denitrification tank 2 through the liquid outlet pipe 12, the liquid discharge pipe 21 and the injection pipe 22 in turn.

[0045] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A nitrification and denitrification system, comprising a nitrification tank (1), a denitrification tank (2), a plate heat exchanger (3) and a cooling tower (4), characterized in that: The nitrification tank (1) delivers water into the plate heat exchanger (3) via a liquid inlet pipe (11), and the liquid inlet pipe (11) is provided with a first valve body (111); The denitrification tank (2) is connected to the water discharge part of the plate heat exchanger (3) via a liquid discharge pipe (21); The cooling tower (4) delivers the cooling liquid into the plate heat exchanger (3) through a cold water pipe (41), and refluxes the cooling liquid from the plate heat exchanger (3) into the tower through a reflux pipe (45); The cold water pipe (41) is connected to a branch pipe (43), the branch pipe (43) is connected to the liquid inlet pipe (11), a second valve body (411) is provided at the connection between the cold water pipe (41) and the branch pipe (43), and a third valve body (431) is provided at the connection between the branch pipe (43) and the liquid inlet pipe (11).

2. A nitrification and denitrification system according to claim 1, characterized in that: The cold water pipe (41) is provided with a pressure pump (42).

3. A nitrification and denitrification system according to claim 1, characterized in that: The cooling tower (4) is provided with a water increase pipe (44), the water increase pipe (44) is in communication with the cold water pipe (41), and a fourth valve body (441) is provided on the water increase pipe (44).

4. A nitrification and denitrification system according to claim 1, characterized in that: The liquid inlet pipe (11) is provided with a filter (112).

5. A nitrification and denitrification system according to claim 1, characterized in that: The nitrification tank (1) is provided with a liquid outlet pipe (12), one end of the liquid outlet pipe (12) is connected to the nitrification tank (1), and the other end is connected to the water discharge part of the plate heat exchanger (3), a fifth valve body (121) is provided on the liquid outlet pipe (12), the liquid discharge pipe (21) is in communication with the liquid outlet pipe (12), and a sixth valve body (211) is provided on the liquid discharge pipe (21).

6. A nitrification and denitrification system according to claim 1, characterized in that: A plurality of injection pipes (22) are arranged in the denitrification pool (2), the plurality of injection pipes (22) are all connected to the drainage pipe (21), and a plurality of injection holes (221) are arranged in an array on the injection pipe (22).

7. A nitrification and denitrification system according to claim 6, characterized in that: The injection pipe (22) is provided with a plurality of reducing pipes (222) connected to corresponding injection holes (221).

8. A nitrification and denitrification system according to claim 1, characterized in that: The second valve body (411) is a three-way valve.

Images