Filter capable of accurately controlling backwashing drainage liquid level

Abstract

The filter is characterized in that a perforated plate is arranged at the middle lower part in a barrel, water caps are uniformly distributed on the perforated plate, an upper drainage pipe is further arranged on the barrel, a water inlet at one end of the upper drainage pipe is positioned below the perforated plate, the other end of the upper drainage pipe extends out of the barrel, and a water outlet of the upper drainage pipe is horizontally positioned above a filter layer interface of the barrel; the tail end of the upper drainage pipe is connected with an atmosphere communicating pipe and a downpipe through a tee joint, the upward extending height of the atmosphere communicating pipe exceeds the horizontal highest position of the upper body pipeline, the downpipe extends downwards to the connector height of the lower body pipeline, and an upper drainage valve is arranged on the upper drainage pipe between the barrel and the tee joint. The water inlet of the upper drainage pipe is arranged below the perforated plate, drainage is not affected by debris pollutants and broken filter materials in water, blockage is avoided, filter material loss is avoided, and the height of the water level above the interface of a filter layer in the filter can be accurately guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of boiler feed water treatment for chemical water treatment in power plants, and in particular relates to a filter for accurately controlling the backwashing water discharge level. Background Art

[0002] The filter is usually scrubbed with air first and then backwashed with water. To ensure the air scrubbing effect, a certain water level needs to be maintained above the filter layer during air scrubbing. The prior art practice is to drain water from the drain pipe at the bottom of the filter or the positive wash drain pipe, observe the water level through a sight glass, or calculate the water level height according to the drain time. There are visual errors in observing the water level through a sight glass, especially when the water quality is poor and the sight glass is difficult to see clearly; there are calculation errors in calculating the water level height according to the drain time, and the drain time often changes. Both methods can easily cause the water level to be too high or below the filter layer interface, which will affect the gap scrubbing. Another method is to set an upper drain outlet 40 at a certain water level above the filter layer, see Figure 1 , drain from this drain outlet until no water comes out, but each time backwashing, part of the filter material will enter the upper drain outlet and the upper drain pipe, and the next time the water is released, this part of the filter material will be discharged with the water, causing filter material loss. Based on this, some people set filters or screens at the upper drain outlet or the upper drain pipe, but the debris-like pollutants and broken filter material in the water will block the filters or screens, making them ineffective. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention provides a filter for accurately controlling the backwash water level.

[0004] The object of the present invention is achieved in the following way: a filter for accurately controlling the backwashing water discharge level, comprising a cylinder, an upper body pipe interface, a lower body pipe interface, an exhaust pipe and a manhole are arranged on the cylinder, the upper body pipe interface is connected to the water inlet and the backwashing outlet respectively through the upper body pipe and the tee, the lower body pipe interface is connected to the water outlet, the backwashing water inlet, the backwashing air inlet and the forward washing outlet through the lower body pipe and the pipe connector, each water inlet and outlet, the air inlet and outlet are provided with a valve, and an upper cloth is arranged on the top of the cylinder. A water plate, a porous plate is arranged in the middle and lower part of the cylinder, water caps are evenly distributed on the porous plate, an upper drainage pipe is also arranged on the cylinder, a water inlet at one end of the upper drainage pipe is located below the porous plate, and the other end extends out of the cylinder, a water outlet level of the upper drainage pipe is located above the filter layer interface of the cylinder, the ends of the upper drainage pipe are respectively connected to the air pipe and the downpipe through a tee, the air pipe extends upward to a height exceeding the highest horizontal point of the upper main body pipe, the downpipe extends downward to the interface height of the lower main body pipe, and an upper drainage valve is arranged on the upper drainage pipe between the cylinder and the tee.

[0005] The upper drainage pipe extends out of the cylinder body and extends upward outside the cylinder body to a required height, or the upper drainage pipe extends upward inside the cylinder body to a required height and then extends out of the cylinder body.

[0006] Install a flow switch on the downpipe.

[0007] The outlet level of the upper drainage pipe is 200-250mm above the filter layer interface of the cylinder.

[0008] The perforated plate is an arc-shaped perforated plate with the arc facing upward.

[0009] The arc height of the perforated plate is 7-8% of its diameter.

[0010] A dome-shaped porous plate is arranged at the lower head of the cylinder, the diameter of the dome-shaped porous plate is 40-50% of the diameter of the cylinder, and the opening rate is ≥50%.

[0011] Compared with the prior art, the present invention sets the water inlet of the upper drainage pipe below the porous plate. Its drainage is not affected by debris pollutants and broken filter media in the water, will not be blocked, will not cause filter media loss, and can accurately ensure the water level above the interface of the filter layer inside the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the filter structure in the prior art.

[0013] Figure 2 It is a structural schematic diagram of the present invention.

[0014] Figure 3 It is another structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present invention.

[0016] like Figure 2 or Figure 3As shown, a filter for accurately controlling the backwashing water discharge level comprises a cylinder 1, on which an upper body pipe 2, a lower body pipe 3, an exhaust pipe 4 and a manhole are arranged, the upper body pipe interface 2 is connected to a water inlet 22 and a backwashing drain port 23 respectively through an upper body pipe 21 and a tee, and a water inlet valve and a backwashing drain valve are respectively arranged at the water inlet 22 and the backwashing drain port 23; the lower body pipe interface 3 is connected to a water outlet 32, a backwashing water inlet 33, a backwashing air inlet 34 and a forward wash drain port 35 through a lower body pipe 31 and a pipe connector, and corresponding water outlet valves, backwashing water inlet valves, backwashing air valves and forward wash drain valves; an exhaust valve is arranged on the exhaust pipe 4, and the manhole comprises a side manhole 18 and a lower manhole 1 7, a hand hole 19, a lifting lug 30, a sight glass 41 and a leg 42 are also provided on the cylinder body; an upper water distribution plate 5 is provided on the top of the cylinder body 1, a porous plate 6 is provided in the middle and lower part of the cylinder body, and a water cap 20 is evenly distributed on the porous plate 6. An upper drainage pipe 7 is also provided on the cylinder body 1, and a water inlet at one end of the upper drainage pipe 7 is located below the porous plate 6, and the other end extends out of the cylinder body. The water outlet level of the upper drainage pipe 7 is located above the cylinder body filter layer interface, and the end of the upper drainage pipe 7 is connected to the air pipe 8 and the downpipe 9 respectively through a tee. The air pipe 8 extends upward to a height exceeding the highest level of the upper body pipe 2, and the downpipe 9 extends downward to the interface height of the lower body pipe 3. An upper drainage valve 10 is provided on the upper drainage pipe 7 between the cylinder body and the tee. The water inlet of the upper drainage pipe 7 is located below the porous plate, and its drainage is not affected by debris pollutants and broken filter materials in the water, will not be blocked, and will not cause filter material loss, and can accurately ensure the water level above the filter layer interface in the filter.

[0017] The upper drain pipe 7 extends out of the cylinder body and extends upward outside the cylinder body to a desired height, or the upper drain pipe 7 extends upward inside the cylinder body to a desired height and then extends out of the cylinder body. In the second case, the portion of the upper drain pipe 7 between the upper drain valve 10 and the water inlet needs to be treated with rubber lining for corrosion protection on both the inner and outer walls. In the first case, the inner wall of the upper drain pipe 7 between the upper drain valve 10 and the water inlet needs to be treated with rubber lining for corrosion protection, and the outer wall can be treated with ordinary anti-rust paint for corrosion protection.

[0018] A flow switch is installed on the downpipe 9. When the upper drain pipe 7 is manually controlled to drain, it can be judged whether the liquid level in the cylinder has reached a position above the filter layer interface by observing whether there is a continuous water flow in the downpipe 9 with human eyes. When the upper drain pipe 7 is automatically controlled to drain, a flow switch (not shown in the figure) needs to be installed on the downpipe 9. The flow switch detects the water flow in the downpipe 9 to judge whether the liquid level in the cylinder has reached a position above the filter layer interface, and further controls the opening and closing of the upper drain valve 10 on the upper drain pipe 7.

[0019] Furthermore, the liquid level in the cylinder is generally controlled at 200-250 mm above the filter layer interface. Therefore, the outlet level of the upper drainage pipe 7 is located 200-250 mm above the cylinder filter layer interface, and the communicating vessel principle is used to achieve liquid level control in the cylinder.

[0020] The porous plate 6 is an arc-shaped porous plate with the arc facing upward. The arc-shaped porous plate is placed on a horizontal plane with the arc arched upward. The height between the highest point of the arc and the horizontal plane is the arc arch height. The arc arch height of the porous plate 6 is designed to be 7-8% of its diameter. The filter is generally designed to have a pressure of 0.6MPa, and the actual operating pressure is generally <0.3MPa. The normal operating pressure difference is 0.02-0.05MPa. In the case of poor water quality, the normal operating pressure difference is 0.1-0.2MPa. If the operating pressure difference reaches 0.35MPa, coupled with the water hammer effect generated when the automatic valve is quickly opened and closed, the flat-plate porous plate with a normal thickness of 20-25mm made of Q235B material will begin to deform, and then pull the weld between the porous plate and the filter cylinder, causing tearing, or even the porous plate falling off. Improve the flat porous plate into an arc-shaped porous plate. Under the same material and thickness or 2-4mm thickness reduction, the arc-shaped porous plate with the ratio of arc height to its diameter of 7-8% can still withstand pressure difference > 0.6Mpa and water hammer. The arc of the arc-shaped porous plate is facing upward, just like the effect of the "prefabricated plate" with a slight arch, which can improve the deformation resistance of the porous plate.

[0021] Furthermore, in order to improve the strength of the porous plate 6, a plurality of support columns 11 may be provided between the porous plate 6 and the lower end cover of the cylinder.

[0022] The existing domestic media filters, whether the filter media is a single medium such as quartz sand, manganese sand, anthracite, activated carbon, fiber bundles, etc., or a combination of multiple media, have two forms of water distribution: one is a dome-shaped porous plate with a cushion layer, and the other is a flat porous plate with a water cap. The dome-shaped porous plate with a cushion layer is used less and less because the backwash intensity of the center area is higher than that of the edge area when the backwash water and air pass through the dome-shaped porous plate. When the water distribution is very uneven, it directly acts on the cushion layer, causing the cushion layer to be unstable, the center area to penetrate, and funnels to form and filter layer leakage. The application of a flat porous plate with a water cap has greatly improved the phenomenon of filter layer funnels and filter layer leakage, but this phenomenon is still unavoidable when using compressed air for backwashing. In the case of poor water quality, the flat porous plate will deform and sink when subjected to a large pressure difference, causing the welds between the porous plate and the cylinder, the rubber lining layer to tear and fall off, and even the supporting columns under the porous plate to bend and deform. The current practice is to increase the thickness of the porous plate and make more supporting columns under the porous plate, but this is bound to increase investment.

[0023] A dome-shaped porous plate 12 is provided at the lower end of the cylinder, the diameter of which is 40-50% of the diameter of the cylinder, and the opening rate is ≥50%. The dome-shaped porous plate 12 is designed as a split structure, divided into two or more pieces, and the size of each piece must ensure that it can be entered and exited from the lower manhole 17 during maintenance.

[0024] The present invention forms a primary water collecting and distributing device by arranging a dome-shaped porous plate 12 at the lower end of the cylinder, and forms a secondary water collecting and distributing device by arranging an arc-shaped porous plate and a water cap in the middle and lower part of the cylinder, thereby finally realizing two-stage water distribution. When the filter is backwashed, the primary water collecting and distributing device performs the first energy dissipation on the backwash water and the backwash air, especially reducing the impact of the backwash water and the backwash air on the central area of ​​the secondary water collecting and distributing device, so that the water or air is relatively mixed and evenly rises after passing through the primary water collecting and distributing device, and then passes through the secondary water collecting and distributing device, and the water distribution is more uniform, which can effectively prevent the phenomenon of funnel formation in the filter layer caused by the high backwashing intensity in the central area when the porous plate water cap is used alone.

[0025] Working process: When the filter is running, the water inlet valve and the water outlet valve are opened and other valves are closed.

[0026] To backwash the filter, follow these steps: The first step is to close the water inlet valve and outlet valve, and open the exhaust valve; The second step is to open the backwash drain valve and the upper drain valve 10, and observe whether there is continuous water flow in the downpipe 9 by human eyes, or judge the liquid level in the filter cylinder by the flow switch on the downpipe 9. When the liquid level in the cylinder reaches 200-250mm above the filter layer, the upper drain valve 10 is closed by interlock control; The third step is to open the backwash air valve, and after air backwashing for 3-5 minutes, close the backwash air valve; Step 4: Open the backwash water inlet valve. After 8-10 minutes of backwashing, close the backwash water inlet valve and backwash drain valve. Step 5: Open the water inlet valve and the positive wash drain valve, close the exhaust valve, and positive wash until the water is clear or the turbidity is appropriate; Step 6. Close the positive wash drain valve, open the outlet valve, and run.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. A filter for accurately controlling the backwashing water discharge level, comprising a cylinder (1), an upper body pipe interface (2), a lower body pipe interface (3), an exhaust pipe (4) and a manhole are arranged on the cylinder (1), the upper body pipe interface (2) is connected to a water inlet (22) and a backwashing outlet (23) respectively through an upper body pipe (21) and a tee, the lower body pipe interface (3) is connected to a water outlet (32), a backwashing water inlet (33), a backwashing air inlet (34) and a forward wash outlet (35) through a lower body pipe (31) and a pipe connector, valves are arranged at each water inlet and outlet, and each air inlet and outlet, an upper water distribution plate (5) is arranged at the top of the cylinder (1), a porous plate (6) is arranged at the middle and lower part of the cylinder, and water caps are evenly distributed on the porous plate (6), characterized in that: An upper drainage pipe (7) is also provided on the cylinder (1). A water inlet at one end of the upper drainage pipe (7) is located below the porous plate (6), and the other end extends out of the cylinder. The water outlet of the upper drainage pipe (7) is located above the cylinder filter layer interface. The ends of the upper drainage pipe (7) are respectively connected to an atmospheric pipe (8) and a downpipe (9) through a tee. The atmospheric pipe (8) extends upward to a height exceeding the highest horizontal point of the upper main body pipe (2). The downpipe (9) extends downward to the interface height of the lower main body pipe (3). An upper drainage valve (10) is provided on the upper drainage pipe (7) between the cylinder and the tee.

2. The filter for accurately controlling the backwash water level according to claim 1, characterized in that: The upper drainage pipe (7) extends out of the cylinder body and extends upward outside the cylinder body to a required height, or the upper drainage pipe (7) extends upward inside the cylinder body to a required height and then extends out of the cylinder body.

3. The filter for accurately controlling the backwash water level according to claim 1, characterized in that: A flow switch is installed on the downpipe (9).

4. The filter for accurately controlling the backwash water level according to claim 1, characterized in that: The outlet of the upper drainage pipe (7) is located at a level 200-250 mm above the filter layer interface of the cylinder.

5. The filter for accurately controlling the backwash water level according to claim 1, characterized in that: The porous plate (6) is an arc-shaped porous plate with the arc facing upward.

6. A filter for accurately controlling the backwash water level according to claim 5, characterized in that: The arc height of the porous plate (6) is 7-8% of its diameter.

7. The filter for accurately controlling the backwash water level according to claim 5, characterized in that: A dome-shaped porous plate (12) is arranged at the lower end cover of the cylinder. The diameter of the dome-shaped porous plate (12) is 40-50% of the diameter of the cylinder, and the opening rate is ≥50%.

Images