JPS6130809B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called backwash water self-containing type filtration device capable of backwashing at an appropriate backwash rate.

A conventional device of this type is shown in FIG. In the figure, 1 is a so-called backwash water self-contained filtration device (hereinafter simply referred to as "filtration device"), 2 is a filtration tank, 3 is a backwash tank installed at the top of the filtration tank 2, 2a is a raw water inlet, and 3a is a This is the water outlet. Further, 4 is a purification chamber provided in the overtank 2, and the purification chamber 4 is divided into a raw water chamber 5, an overlayer 6, and a water chamber 7 in order from above.
A is a trough provided at an inclined inner end of the upper longitudinal direction of the raw water chamber 5. 8 is a communication pipe for communicating the backwash tank 3 and the water chamber 7, and 9 is the overtank 2.
A backwash drain valve is attached to 10, and 10 is a drain. In such a filtration device 1, raw water is supplied to the raw water inlet 2a.
After being led into the overlayer tank 2, the water is purified in the overlayer 6 while passing through the purification chamber 4 from above, and then ascends from the water chamber 7 through the communication pipe 8 and is led into the backwash tank 3. When the water level reaches a certain level, the water is discharged from the water outlet 3a. Therefore, water at a constant level is always held in the backwash tank 3, and this held water is used as backwash water during backwashing. That is, when the backwash drain valve 9 is opened during backwashing, retained water (hereinafter referred to as "backwash water") R
The water flows down the communication pipe 8, flows into the water chamber 7, and further rises (that is, flows backward) through the overlayer 6, thereby cleaning the overlayer 6. This wash water overflows from the upper raw water chamber 5 into the inclined trough 5a, flows down from the wash water outlet 5a', and is further discharged from the backwash drain valve 9 to the external drain tank 10.

The conventional filtration device uses the water purified by the device 1 as backwash water as described above, and
Since the backwash water is stored in the upper part of the overtank 2 and the water head at the time of holding is used to wash the overlayer 6 in the overtank 2, a separate backwashing device is not required and it is economical. It is. However, there were also major drawbacks as described below. Since backwashing simply utilizes backwash water due to water head, if the water level changes, the speed at which backwash water passes through the overlayer 6 (hereinafter referred to as "backwash speed") will change. Particularly in the initial stage of backwashing, the water level is high, so the water head is large, and therefore the backwashing speed is too high than the appropriate backwashing speed, and the material of the overlayer 6 flows out of the purification chamber 4. On the other hand, at the end of backwashing, the water level is low, so the water head is small, and therefore the backwashing speed is too low than the appropriate backwashing speed, and the overlayer 6 cannot be sufficiently purified. Since the inclined trough 5a, which serves as a passage for backwash water that has purified the overlayer 6, is provided inside the upper part of the raw water chamber 5, the material in the area corresponding to the planar area of the trough 5a is effectively purified. Therefore, the backwashing efficiency decreases accordingly.

The present invention has been made in view of these circumstances, and its purpose is to provide a filtration device with excellent backwash performance that can appropriately control the backwash speed.

However, the filtration device of the present invention that has achieved these objectives is a filtration tank that is formed from above into a raw water chamber, an overlayer, and a water chamber in order, and a backwash tank is provided on the upper part of the filtration tank. A backwash drain valve is provided near the outside of the raw water chamber and communicates the raw water chamber with the outside, and by opening and closing the drain valve, backwash water is transferred into the backwash tank into the overtank. In a filtration device that backwashes the superlayer by introducing water into the filtration tank and allowing it to pass through, the backwash drain valve outlet side is provided outside the filtration tank for pressure regulation of a water-sealed pressure regulation tank. While connected to the air chamber, a compressed air pipe connected to an external compressed air source and opened at the bottom of the backwash tank is provided inside the backwash tank, and the compressed air pipe and the water seal pressure regulation tank are connected to each other. The gist lies in that the pressure regulating air chamber is configured to communicate with the pressure regulating air chamber.

An embodiment of the present invention will be described below based on the drawings. FIG. 2 is a schematic explanatory diagram of a filtration device according to the present invention. In this figure, 11 is a filtration device, 12 is a filtration tank, 13 is a backwash tank provided at the upper part of the filtration tank 12, 12a is a raw water inlet, 13a is a water outlet. Further, the overtank 12 is defined in order from above into a raw water chamber 15, an overlayer 16, and a water chamber 17. 18 is the backwash tank 13 and water chamber 17
It is a communication pipe for communicating. Further, a water collection pipe 21 communicating with the outside is disposed in the upper part of the raw water chamber 15, and a plurality of strainers 22 are attached to the water collection pipe 21 at appropriate intervals. Furthermore, in the water collection pipe 21, a backwash drain valve 19 is installed near the outside of the raw water chamber 15.
At the same time, the outlet pipe 23 of the drain valve 19 is connected to the side surface of a pressure regulating tank 24 provided outside. The pressure regulating tank 24 is sealed with water inside a drainage tank 25. Further, inside the backwash tank 13, a compressed air pipe 27 is provided which is connected to an air compressor 26 and opens at the bottom of the backwash tank 13. Further, the pipe 27 and the upper surface of the pressure regulating tank 24 are communicated with each other by a communication pipe 28. Further, 29 is a guide plate for making it easier for backwash water overflowing from the drain tank 25 to flow down, 20
is a drainage ditch. The pressure regulating air chamber 29 and water seal chamber 30 of the pressure regulating tank 24 are set at the maximum immersion depth of the compressed air pipe 27 into the backwash tank 13, that is, the backwash tank 13.
The depth is the same as when the water surface is at its highest.

The over-washing operation in the overwashing device 11 constructed in this way is similar to the conventional example shown in FIG. 1, and the characteristic backwashing operation will be explained below. For backwashing, the air compressor 26 is operated, valves 30 and 31 are opened, and valve 32 is closed. Next, when the backwash drain valve 19 is opened, the backwash water R descends through the communication pipe 18 and enters the water chamber 17.
The backwashing speed after the start of backwashing is properly controlled by the unique structure and operation of the present invention as described below. That is, the backwash tank 18
The opening surface of the compressed air pipe 27 inside the reference position L
From this level, the inlet 24 of the pressure regulating tank 24
Let Ho be up to the level L ₁ of a, and h be the arbitrary level L ₂ of the backwash water R in the backwash tank 13.
Since the inside of the pressure regulating tank 24 receives a back pressure corresponding to the water head h, the water head at the inlet 24a of the pressure regulating tank 24 is total water head (Ho+h) - back pressure h=Ho (constant). That is, until the water level in the backwash tank 13 drops to the reference level L, a constant water head always acts in the pressure regulating tank 24, so the amount of backwash water overflowing from the drain tank 25 to the drain groove 20 is also constant. . In this way, the backwash speed remains constant regardless of fluctuations in the water level in the backwash tank 13. Now, backwashing is performed by backwashing water R descending down the communication pipe 18 and flowing into the water chamber 17, and then rising up the overlayer 16 and washing the overlayer 16. As mentioned above, the rising speed of the washing water is constant from the beginning of backwashing to the end of backwashing.
Therefore, the outflow phenomenon of material at the beginning of backwashing does not occur as in the conventional case, nor does a significant decrease in backwashing performance at the end of backwashing occur. The backwash water used to wash the overlayer 16 is separated into fine materials by the strainer 22, and then passes through the water collection pipe 21 to the raw water chamber 15.
led to the outside of In other words, the passage of the backwash water that purified the overlayer 16 was achieved through the water collection pipe 21 installed at the top of the raw water chamber 15, which saved the over-effective area that would have occurred when using a conventional inclined trough. It is possible to prevent a decrease in equipment efficiency due to the decrease. By appropriately performing backwashing using the above device, a stable filtration product could be obtained for a long period of time.

The filtering device of the present invention has a configuration as described above, but the key point is that a water-sealed pressure regulating tank is provided on the outlet side of the backwashing drain valve and communicates with the backwashing tank, and the pressure regulating tank is provided with a type of flow control valve. The backwashing speed can now be controlled appropriately. Therefore, it became possible to prevent the material from flowing out at the beginning of backwashing and the reduction in backwashing speed at the end of backwashing, making it possible to provide a filtration device with excellent backwashing performance.

[Brief explanation of the drawing]

FIG. 1 is a schematic illustration of a conventional filtering device, and FIG. 2 is a schematic illustration of a filtering device according to the present invention. 11... filtration device, 12... filtration tank, 13... backwash tank, 15... raw water chamber, 16... superlayer, 17...
Water chamber, 18...Communication pipe, 19...Backwash drain valve, 21
... Water collection pipe, 24 ... Pressure regulation tank, 26 ... Air compressor, 27 ... Compressed air piping, 28 ... Communication pipe.

Claims (1)

[Claims] 1. A backwash tank is provided at the top of a filtration tank which is defined from above into a raw water chamber, a filtration layer, and a filtration chamber, and the tank and the filtration chamber are communicated, and near the outside of the raw water chamber. A backwash drain valve communicating with the raw water chamber and the outside is provided, and the backwash water in the backwash tank is introduced into and passed through the filtration tank by opening and closing the drain valve, thereby backwashing the filtration layer. In a filtration device configured to perform A compressed air piping connected to a compressed air source and opening at the bottom of the backwash tank is provided to communicate the compressed air piping with the pressure regulating air chamber of the water seal pressure regulating tank, and the water seal pressure regulating tank The pressure regulating air chamber and the water seal chamber provided on the outlet side of the air chamber are each configured to have a height exceeding the maximum immersion depth of the compressed air piping into the backwash tank. over device.