JPS6254521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a filtration device with a filter media backwashing function, and more specifically, when the filter media in the filtration tank becomes clogged and requires cleaning, the filter media can be removed from the filtration tank. This invention relates to a filtration device with a filter media backwashing function that allows automatic backwashing (cleaning performed by flowing wash water in the opposite direction to the flow direction of raw water during normal filtration) without removing the filter.

Porous filter media used in filtration devices include porous porcelain, foamed resin, natural or synthetic fibers, metal mesh, sintered metal, etc. These filter media have a pore size of 1
It is adjusted to a range of ~100μ, has high stability, and is widely used in general. Such porous filter media are
If suspended solids (hereinafter abbreviated as SS) in raw water adhere to the filter media and the filtration ability decreases due to clogging, the filter must be replaced with a new one or cleaned and reused. Some conventional filtration devices are known that allow backwashing of the filter media without removing it from the filtration tank. It was necessary to provide a water flow path and cut off the raw water supply and switch to the wash water supply when backwashing was required, which not only made the overall structure of the filtration device extremely complicated, but also required washing water to be supplied separately from the raw water. It had the necessary flaws.

Furthermore, conventional filtration devices generally use forced pressure filtration, in which raw water is supplied under pressure to a filtration tank and passed through a filter medium.
SS will adhere firmly to the filter media, and in order to backwash the filter media, it is not only necessary to supply cleaning water at an equivalent or higher pressure, but it is also difficult to obtain a sufficient cleaning effect. Ta. Furthermore, in order to automatically start cleaning the filter medium, it is necessary to detect with high precision changes in the pressure of raw water due to clogging of the filter medium, which also poses a problem in terms of automatic control.

The present invention provides a filtration device with a filter media backwashing function that can solve all of the above-mentioned problems, and embodiments thereof will be described below with reference to the attached illustrative drawings.

FIG. 1 shows a multi-tube type filtration device, and FIG. 2 shows a single-tube type filtration device. Both filter devices basically have the same structure, and corresponding parts are given the same reference numerals. In the figure, 1 is a filter tank,
2 is a water purification tank connected to the upper part of the filtration tank 1, 3 is a raw water tank arranged at a higher place than the water purification tank 2, 4 is a deceleration tank, and 5 is the lower end of the rising pipe part 5a of the filtration tank 1 an inverted U-shaped pipe for a siphon connected to the raw water supply section 1a;
Reference numeral 6 designates an automatic opening/closing means connected to the lower end of the descending pipe portion 5b of the inverted U-shaped pipe 5, and 7 designates a cylindrical filter medium (hereinafter abbreviated as a filter cylinder) installed vertically within the filter tank 1. . The upper U-turn portion 5c of the inverted U-shaped pipe 5 is located higher than the upper end of the water purification tank 2, and the upper portion of the upper U-turn portion 5c and the bottom portion of the water purification tank 2 are connected to each other by the communication pipe 8. It is connected by a wire.

As shown in FIGS. 3 and 4, the filter tube 7 is loosely fitted into the porous tube 9 in a concentric manner with a certain annular space in between, and is fitted with an upper end cover plate 10a and a lower end cover plate 10b. It is held in place. The porous pipe 9 is
The upper end is a partition wall 1 between the filtration tank 1 and the water purification tank 2.
1 and opens into the water purification tank 2, and the lower end opening is closed by a cap 12. Reference numeral 13 denotes an outer cylinder which is fitted concentrically to the filter cylinder 7 with a certain annular space 14 in between.The upper end of the outer cylinder 13 is attached to the upper end cover plate 10a, and the lower end is open.
In the single-tube filtration device shown in FIG. 2, the surrounding wall of the filtration tank 1 also serves as the outer cylinder 13.

Details of the automatic opening/closing means 6 are shown in FIG. As shown in the figure, the automatic opening/closing means 6 includes an upper main opening/closing valve 15, a lower auxiliary opening/closing valve 16, and a water tank 18 in which a float 17 is installed.
The main opening/closing valve 15 includes a valve case 20 which is provided with a conical valve seat 19 and whose upper end communicates with the descending pipe portion 5b of the inverted U-shaped pipe 5, and which is movable up and down within the valve case 20. a conical movable valve body 22 with a through passage 21 in the direction, and the conical valve seat 1
9, the movable valve body 2 is located at the lower limit position.
A valve hole 23 is provided which is closed by 2. Reference numeral 24 denotes a water discharge tank in which the upper and lower valves 15 and 16 are housed, and is provided with a water discharge pipe 25 and communicates with the valve hole 23.

The auxiliary opening/closing valve 16 includes a needle valve element 27 that opens and closes a valve hole 26 formed at the bottom of the valve case 20 at a position concentric with the movable valve element 22 by vertical movement.
The needle valve body 27 has an upper shaft portion 27a that passes through the movable valve body 22 so as to be relatively vertically movable, and can push up the movable valve body 22 by upward movement. A space 28 below the valve hole 26 that is opened and closed by the needle valve body 27 is connected to a communication hole 29.
It communicates with the water tank 24 through a hole 30, and with the water tank 18 through a communication hole 30.

The float 17 in the water tank 18 moves the needle valve body 27 of the sub-opening/closing valve 16 by upward movement.
It can be pushed up via its upwardly protruding shaft portion 17a. 31 is a small-diameter siphon tube for draining water from the water tank 18. 32 is a communication pipe that communicates the inside of the water tank 18 with the upper part of the upper end U-turn portion 5c of the inverted U-shaped pipe 5.

Next, the method of use and effect will be explained. Water with low suspended solids (SS), such as river water, industrial sewage, and general wastewater, or pretreated water (hereinafter referred to as raw water) is supplied to the raw water tank 3 through the raw water supply pipe 33, and is supplied to the raw water tank 3 through the overflow pipe 34. The water flows into the deceleration tank 4 through the water supply pipe 35 while being maintained at a constant water level. Here, the flow rate is reduced, and the water enters the filtration tank 1 from the bottom opening of the filtration tank 1, that is, the raw water supply section 1a, via the water supply pipe 36 and the flow rate adjustment valve 37. The purified water after being filtered by the filter tube 7 in the filter tank 1 enters the water purification tank 2, and the inside of the water purification tank 2 is kept at a certain level L1.
After the water is filled to the maximum, it overflows from the water outlet pipe 38 at the upper end of the water purification tank and is used as water supply. 39 is an air vent pipe from inside the water purification tank 2. A portion of the raw water supplied to the raw water supply section 1a of the filtration tank 1 enters the rising pipe section 5a of the inverted U-shaped pipe 5 and naturally rises due to water pressure. The flow rate regulating valve 37 in the water supply pipe 36 is adjusted and fixed so that the amount of water coming out from the water outlet pipe 38 is a specified amount. The raw water level in the rising pipe section 5a of the inverted U-shaped pipe 5 at this time
The water level difference between L2 and the purified water level L1 in the water purifying tank 2 becomes the filtration start water head H1 of this device.

SS that adheres to the filter tube 7 as the filtration operation progresses
As the amount of filtered water increases, the water flow resistance in this filter tube 7 increases, and the amount of filtered water decreases. On the other hand, since the amount of raw water supplied is constant, the level of raw water in the rising pipe section 5a will rise, and a portion of the raw water will eventually exceed the U-turn section 5c at the upper end of the inverted U-shaped pipe 5 and reach the descending pipe section. 5b
begins to flow into At this time, as shown in FIG.
7 is at the lower limit position, and these valve bodies 22, 27
Since the valve holes 23 and 26, which are opened and closed by the downcomer pipe 5b, are closed, raw water is stored in the downcomer pipe portion 5b. The air inside the inverted U-shaped pipe 5 is transferred to a communication pipe 32, a water tank 18, communication holes 30, 29, and a water discharge tank 2.
4 and is discharged via the water discharge pipe 25.

The raw water that flows into the downcomer pipe section 5b and gradually rises finally reaches a level L3 where the entire inverted U-shaped pipe 5, including the upper end U-turn section 5c, is filled, and as a result, the inside of the upper end U-turn section 5c. Connecting pipe 3 from the top of
The raw water flows into the water tank 18 via 2. As a result of the raw water flowing into this water tank 18 lifting the float 17, its upper end protruding shaft portion 17a
pushes up the needle valve body 27 of the sub-opening/closing valve 16 and opens the valve hole 26. Subsequently, the rising needle valve body 27 touches the movable valve body 22 of the main opening/closing valve 15.
, the valve hole 23 is opened. Therefore, the raw water in the downcomer pipe section 5b flows through the valve box 20, the valve hole 23,
and is rapidly discharged from the water discharge pipe 25 via the water discharge tank 24, and as a result, the siphon action is started,
Raw water is continuously released. By making the amount of water discharged per unit time due to this siphon action sufficiently larger than the amount of water supplied per unit time of raw water supplied from the water supply pipe 36, the water absorption power of the high water head due to the siphon action is It acts on the purified water in the water purification tank 2 via the filtration tank 1, and the purified water in the water purification tank 2 passes through the filtration tank 1 and the inverted U-shaped pipe 5.
The raw water is continuously discharged from the discharge pipe 25 along with the raw water supplied from the water supply pipe 36. This becomes high water head backwash water for the filter cylinder 7.

That is, the water level difference between the raw water level L3 that has reached the upper end of the inverted U-shaped pipe 5 and the purified water level L1 in the water purification tank 2 becomes the backwashing start water head H2 for the filter cylinder 7,
As a result of the start of the backwashing action as described above, the range from the filtration start water head H1 to the backwash start water head H2 is low to
SS attached to the front side of the filter tube 7 under pressure corresponding to a medium level water head becomes high water head backwash water and flows backward through the filter tube 7 in the filtration tank 1 from the back side to the front side.Purified water It is washed and removed by purified water in tank 2.

When the purified water level in the water purification tank 2 reaches the lower limit level L4, which is equal to the opening level of the communication pipe 8, air flows into the upper U-turn portion 5c of the inverted U-shaped pipe 5 via this communication pipe 8. Therefore, the siphon action is stopped, the raw water supplied from the supply pipe 36 flows into the filtration tank 1 again, and the desired filtration action is started. At the same time, the raw water in the rising pipe section 5a of the inverted U-shaped pipe 5 is at a level L2 corresponding to the filtration start water head H1.
Go back to.

In addition, during the filter cylinder backwashing action based on the above-mentioned siphon action, the water tank 18 in the automatic opening/closing means 6
The water inside is gradually discharged from the siphon pipe 31, but a larger amount of water than this discharged water flows into the communication pipe 32,
Since the water continuously flows into the water tank 18 from the valve hole 26 of the sub-opening/closing valve 16 and the water discharge tank 24, the float 17 is maintained in a floating state to a required level. Furthermore, when the backwashing action is completed due to the inflow of air into the inverted U-shaped pipe 5, the water in the descending pipe section 5b is completely drained from the valve hole 23 of the main opening/closing valve 15 and the valve hole 26 of the sub opening/closing valve 16. After that, the water in the water tank 18 is discharged by the siphon pipe 31, and as a result, the float 17 descends, and as a result, the needle valve body 27 and the movable valve body 22 reach their lower limit due to gravity. The valve holes 23 and 26 are respectively closed. In this way, preparations for the next backwashing operation are completed.

The filtration device with a filter medium backwashing function of the present invention can be implemented and used as described above, and its characteristic point is that purified water that has passed through a filtration tank using a porous filter medium is transferred to the filtration tank. In a filtration device that allows water to flow out through a water purification tank formed at the top, the raw water supply section of the filtration tank has an upper end U-turn section that is lower than the purified water level (L1 in the embodiment) in the water purification tank. One end of the inverted U-shaped pipe for the high siphon is connected to the other end of the inverted U-shaped pipe, and the circuit is switched to open when the inverted U-shaped pipe is full of water, and the purified water level in the water purification tank is kept constant. The point is that an automatic opening/closing means is connected which switches the circuit to closed when the voltage drops below the level (L4 in the embodiment).

According to the filtration device of the present invention, the level of raw water at the riser section of the inverted U-shaped pipe at the start of filtration operation is slightly higher (for example, about 10 cm) than the level of purified water in the water purification tank. , if you adjust the amount and pressure of raw water supplied to the filtration tank,
A low water head (in the example, L2-L1 in the example) corresponds to the water level difference between the raw water level and the purified water level above (L2-L1 in the example).
Based on the pressure difference corresponding to H1), the water level difference (L3-
The filtration action is performed within the range up to the pressure difference corresponding to the medium water head (H2 in the example) corresponding to L1), and if a pressure difference corresponding to the medium water head occurs due to clogging of the filter medium, automatic The siphon action is started immediately to cause the purified water in the water purification tank to flow back with a pressure difference in the opposite direction corresponding to the high water head, thereby making it possible to backwash the filter medium in the filtration tank. Moreover, when a predetermined amount of purified water flows back and the backwashing is completed, the original filtration operation state can be automatically restored.

Therefore, unlike conventional equipment, there is no need to provide a wash water flow path for filter medium backwashing separately from the raw water flow path, and to cut off the raw water supply and switch to the wash water supply when backwashing is required. Not only is the structure extremely simple, but it also eliminates the need to prepare washing water separately from raw water. Furthermore, as mentioned above, the pressure difference of the raw water passing through the filter media is kept very low, so SS in the raw water will lightly adhere to the surface of the filter media, and therefore the purified water in the water purification tank at the top of the filter tank will be reduced. Even though the siphon effect only causes the water to flow backwards, a sufficient cleaning effect can be obtained.

In addition, in order to automatically start backwashing and restart filtration operation, there is no need to detect subtle changes in raw water pressure due to filter media clogging, and the level of raw water in the inverted U-shaped pipe or purified water in the water purification tank can be adjusted automatically. Since the automatic opening/closing means can be opened and closed based on changes in the temperature, the control system is simple and highly accurate automatic control can be performed.

Furthermore, the structure inside the filter tank is not limited to the structure that uses a filter tube as shown in the example, but as shown in the example, the filter tube is arranged vertically so that the raw water flows from below in the filter tank. When configuring a filtration tank that passes through the filter cylinder while flowing upward, if the flow of raw water in the filtration tank during filtration operation becomes a so-called short-circuit flow or a biased flow, the whole filter cylinder will be completely drained. The raw water no longer flows uniformly on the surface of the effective filter medium, and the flow rate of raw water is high at the points on the surface of the effective filter medium of the filter tube (areas where the flow rate of raw water is high, and it gradually migrates due to clogging of the filter medium). The penetration depth of the SS into the filter medium increases, and overall, the adhesion force of the SS to the filter medium increases compared to the case where the raw water flows evenly over the entire effective surface of the filter cylinder. This has an adverse effect on the backwashing action of the filter medium, which is performed by causing purified water to flow back through the siphon action. Furthermore, during backwashing, if the wash water flowing back in the filter tank (purified water in the water purification tank) becomes short-circuited or drifts, only the surface of the filter medium where the wash water flows will be backwashed. If the water flow resistance is partially lowered due to partial cleaning, the cleaning water will flow concentrated only to that area, making it impossible to evenly clean the entire effective filter media surface of the filter cylinder. It becomes possible.

In view of the above points, consider the arrangement of the inlet and outlet of raw water to the filter tank 1 in which the filter tube 7 is arranged vertically as shown in FIGS. 1 and 2, and the arrangement of the inlet and outlet of raw water to the filter tube 7. By doing so, the flow path of the raw water is adjusted so as not to cause short-circuit flow or uneven flow.In addition, in the multi-tube filter tank shown in Fig. 1, for each filter cylinder 7 as shown in Fig. 4, Outer cylinder 1 that acts as a water guide
3, all filter cylinders 7,
Raw water or purified water during backwashing is made to distribute evenly over the entire surface of the effective filter medium.

FIG. 3 shows a filter tank 1 that experimentally uses both a filter tube 7 with an outer tube 13 attached and a filter tube 7 without an outer tube 13 attached, and in the figure, the filter tubes 7 are placed at positions C to E. Filter tube 7 installed, that is, filter tube 7 with outer tube 13 attached
As shown in FIG. 4, a slow flow or a stationary state of flow occurs only on the outer periphery of the outer cylinder 13 as indicated by XXX, and in the raw water circulation space 14 between the filter cylinder 7 and the outer cylinder 13. As shown by the arrow, raw water flows at the desired flow rate over the entire length and around the filter tube 7, whereas the flow around the filter tube 7 at the A position and B position where the outer tube 13 is not attached. In this case, a slow flow or a stationary state of flow occurs at the point in contact with the surrounding wall of the filter tank, indicated by ×××, and a slow flow indicated by △△△ and a drifted flow indicated by diagonal arrows occur between the filter tubes 7. It can be understood that in the filter tubes 7 that are not provided with the outer tube 13 located at the A position and the B position, the raw water cannot be distributed evenly over the entire surface of the effective filter medium.

By attaching the outer tube 13 to the filter tube 7 as described above, raw water can be distributed evenly over all the effective filter media surfaces of all the filter tubes 7, increasing filtration efficiency and reducing the SS for the filter media. The adhesion can be easily removed by backwashing. Furthermore, during backwashing, the entire surface of the effective filter medium can be reliably washed, and the desired backwashing effect can be expected.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of a multi-tube filtration device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the configuration of the same single-tube filtration device, and FIG. 3 shows details of the inside of the filtration tank in FIG. 1. FIG. 4 is an enlarged vertical side view of the main part of FIG. 3, and FIG. 5 is a vertical side view showing an embodiment of the automatic opening/closing means. DESCRIPTION OF SYMBOLS 1...Filtering tank, 1a...Raw water supply part, 2...Water purification tank, 3...Raw water tank, 5...Inverted U-shaped pipe for siphon, 5a...Rising pipe part, 5b...Descent pipe part, 5
c... Upper end U-turn part, 6... Automatic opening/closing means, 7
...Filter cylinder, 8,32...Communication pipe, 9...Porous,
13...Outer cylinder for water guiding, 15...Upper main opening/closing valve, 16...Lower auxiliary opening/closing valve, 17...Float, 18...Water tank, 19...Conical valve seat, 21...
...Through passage, 22... Conical movable valve body, 23, 26
... Valve hole, 24 ... Water tank, 25 ... Water pipe, 2
7... Needle valve body, 31... Small diameter siphon pipe, 33... Raw water supply pipe, 34... Overflow pipe, 35, 36... Water supply pipe, 37... Flow rate adjustment valve.

Claims (1)

[Claims] 1. In a filtration device that allows purified water that has passed through a filtration tank using a porous filter medium to flow out via a water purification tank formed at the top of the filtration tank, the raw water supply section of the filtration tank is provided with the Connect one end of the inverted U-shaped pipe for the siphon whose upper end U-turn is higher than the purified water level in the water purification tank, connect a water tank with a water discharge pipe to the other end of this inverted U-shaped pipe, and drain water below the water tank. A water tank with a mouth is arranged, the water tank and the upper part of the upper U-turn part are communicated with each other by a communication pipe, a float is installed inside the water tank so as to be able to rise and fall freely, and an inverted U-shaped pipe is installed in the water discharge tank in a downward state. A movable valve body is arranged to be able to move up and down freely to separate the water discharge pipe and the water discharge pipe and to release the separation when the float is pushed up by the rise of the float, and the bottom part in the water purification tank and the top part in the upper U-turn part are disposed. A filtration device with a backwashing function that connects the filter media.