AU2016240897B2 - Pressure-type filtration device - Google Patents

Abstract

This pressure-type filtration device comprises: a plurality of filtration chambers (70) arranged in a circular shape, each filtration chamber including a filtration material therein; a raw water chamber (71) arranged in the center of the plurality of filtration chambers (70); a flow path system that can take a first state for connecting the raw water chamber (71) and respective raw water inlets (70a) of the plurality of filtration chambers (70) wherein raw water in the raw water chamber (71) is distributed and supplied to the respective raw water inlets of the plurality of filtration chambers (70), and a second state in which the raw water inlet of the filtration chamber (70) to be backwashed and a water drainage pipe are connected and raw water in the raw water chamber (71) is distributed and supplied only to the respective raw water inlets of the filtration chambers (70) other than the filtration chamber (70) to be backwashed; and a clean water chamber (73) capable of functioning as a filtered water path through which filtered water from the filtration chambers (70) other than the filtration chamber (70) to be backwashed is introduced to a filtered water outlet of the filtration chamber (70) to be backwashed.

Description

PRESSURE-TYPE FILTRATION DEVICE

[Field]

[0001]

The present invention relates to a pressure-type

filtration device.

[Background]

[0002] A pressure-type filtration device (closed type

filtration device) is known as a filtration device to purify

water by filtering raw water. In order to keep performance of

the pressure-type filtration device, it is necessary to

periodically perform water discarding which is for cleaning of

filtering material and for stabilization of filtering material

particles. One of the washing methods of filtering material is

backwashing.

[0003] A system (see e.g., PTL1) has been therefore

developed which includes a plurality of pressure-type

filtration devices and which is configured in such a manner

that each pressure-type filtration device can be backwashed by

filtered water obtained by the other pressure-type filtration

devices.

[Citation List]

[Patent Literature]

[0004]

[PTL 1] Japanese patent laid-open publication No. 2003-93808.

[0005] To the above-described system, configuration is

adopted in which a plurality of pressure filters that are

arranged in a line are connected by a plurality of header

pipes (raw water main pipe, communication pipes, etc.).

However, with the configuration, it is difficult to

approximately uniform quantity of raw water to be supplied to

each pressure filter device in the filtration step.

[00061 Any discussion of documents, acts, materials,

devices, articles or the like which has been included in the

present specification is not to be taken as an admission that

any or all of these matters form part of the prior art base or

were common general knowledge in the field relevant to the

present disclosure as it existed before the priority date of

each of the appended claims.

[0006A] Throughout this specification the word "comprise",

or variations such as "comprises" or "comprising", will be

understood to imply the inclusion of a stated element, integer

or step, or group of elements, integers or steps, but not the

exclusion of any other element, integer or step, or group of

elements, integers or steps.

[Summary]

[0007] According to an aspect of the present disclosure,

there is provided a pressure-type filtration device which

comprises: a plurality of filtration chambers each of which has

filtering material therein and which are arranged

concentrically; a raw water distribution part which is arranged

at a center part of the plurality of filtration chambers in a

plan view and to which raw water to be filtered is supplied from

the outside; a flow channel system which connects raw water

introducing ports of the plurality of filtration chambers and

the raw water distribution part and is capable of attaining a

first state and a second state, the first state being a state in

which the raw water in the raw water distribution part is

distributed to the raw water introducing ports of the plurality

of filtration chambers, and the second state being a state in

which a raw water introducing port of a backwash target

filtration chamber and a waste water pipe are connected and raw

water in the raw water distribution part is distributed only to

the raw water introducing ports of the filtration chambers other

than the backwash target filtration chamber; and a purified water chamber into which filtered water from the filtered water outlets of the plurality of filtration chambers flows, and which act as a filtered water path which guides the filtered water from the plurality of filtration chambers other than the backwash target filtration chamber to the filtered water outlet of the backwash target filtration chamber, wherein the plurality of filtration chambers, the raw water distribution part and the purified water chamber are provided in a filtration body, and the plurality of filtration chambers have shapes formed by equally dividing an inner part of the filtration body excluding the raw water distribution part and the purified water chamber along radial directions from the center of the filtration body.

[00081 According to this aspect, the pressure-type

filtration device has such configuration that the plurality of

filtration chambers are arranged concentrically centering on

the center part of the raw water chamber. Therefore, "the

channel system" in the pressure-type filtration device can be

designed and manufactured easily so that the channel

resistance of the raw water channel between each filtration

chamber and the raw water chamber becomes approximately equal.

Accordingly, by adopting the above configuration, it is

possible to easily realize a pressure-type filtration device

where the quantity of raw water to be supplied to each

filtration chamber in the filtration step is approximately

uniform.

[00091 Note that the plurality of filtration chambers in

the pressure-type filtration device are not necessarily arranged

in a perfect circle so long as they are arranged concentrically.

Therefore, a pressure-type filtration device may be realized as

a device where distances between some filtration chambers and

the raw water distribution part are longer/shorter than

distances between the other filtration chambers and the raw water

distribution part. Further, the plurality of filtration

chambers in the pressure-type filtration device are not necessarily arranged with a constant angular space. Therefore, the pressure-type filtration device may be realized, for example, as a device in which the plurality of filtration chambers are arranged in an approximately semicircular shape.

[0010] As the channel system in the pressure-type

filtration device, various systems with different specific

configurations can be adopted. For example, it is possible to

adopt a channel system which includes discrete channel systems

which are provided to each filtration chamber and each of

which has one or more valve devices to alternatively connect

the raw water introducing port of the filtration chamber to

the raw water distribution part and the waste water pipe.

[0011] To reduce the size, in this aspect, as indicated

above, in the pressure-type filtration device, "the plurality

of filtration chambers, the raw water distribution part and

the purified water chamber are provided in a filtration body,

and the plurality of filtration chambers have shapes formed by

equally dividing an inner part of the filtration body

excluding the raw water distribution part and the purified

water chamber along radial directions from the center of the

filtration body." Note that, when this constitution is

adopted, it is desirable to adopt a filtration body, the cross

section shape of which is polygonal or circular in a plan

view.

[0012] Further, the pressure-type filtration device may be

realized as a device in which the channel system is a one

valve device which is capable of attaining the first state and

the second state by moving a valve element in a valve box."

[0013] The number of the filtration chambers in the

pressure-type filtration device and the number of the

filtration chambers to be backwashed (backwash target

filtration chambers) are not particularly limited. It is

available to determine the number of the filtration chambers

and the number of the filtration chambers to be backwashed from a backwashing step flow velocity which is defined as a flow velocity required for backwashing and the filtering speed. For example, when the filtration speed is 200 m/day and the backwashing flow velocity is 1,000 m/day, the number of the filtration chambers may be six and the number of the filtration chambers to be backwashed may be one. Further, when the filtration speed is 300 m/day, and the backwashing flow velocity is 900 m/day, the number of filtration chambers may be four and the number of filtration chambers to be backwashed may be one. Moreover, when the filtration speed is 120-150 m/day, and the backwashing flow velocity is 840-1050 m/day, the number of filtration chambers may be eight and the number of filtration chambers to be backwashed may be one.

[0014] Further, when the backwashing step flow velocity is

almost twice of the filtration flow quantity, the number of

filtration chambers may be three and the number of filtration

chambers to be backwashed may be one, or also the number of

filtration chambers may be six and the number of filtration

chambers to be backwashed may be two.

[0015] According to the present disclosure, it is possible

to realize a pressure-type filtration device where the

quantity of raw water to be supplied to each filtration

chamber in the filtration step is approximately uniform.

[Brief Description of Drawings]

[0016]

FIG. 1 is a top plan view of the pressure-type filtration

device according to a first embodiment of the present

invention.

FIG. 2 is a front view of the pressure-type filtration

device according to the first embodiment.

FIG. 3 is an explanatory drawing of the internal

structure of the pressure-type filtration device according to

the first embodiment.

FIG. 4 is a sectional view of the selector valve cut by a

plane passing through the center of the selector valve.

FIG. 5A is a plane view of a valve element in the selector

valve.

FIG. 5B is a side view of the valve element.

FIG. 6 is a development view of a shaft part which is a

component of the selector valve.

FIG. 7 is an explanatory drawing of position relations

that the valve element and the raw water outlet of the

selector valve can take.

FIG. 8 is a section view of the valve element along the

VIII-VIII line of Fig. 7 viewing from the arrow direction.

FIG. 9 is an explanatory drawing of the constitution of

the selector valve.

FIG. 10A is an explanatory drawing of paths of raw water

and so on in the filtration step of the pressure-type

filtration device according to the first embodiment.

FIG. 10B is an explanatory drawing of paths of raw water

and so on in the backwashing step of the pressure-type

filtration device according to the first embodiment.

FIG. 10C is an explanatory drawing of paths of raw water

and so on in the water discarding step of the pressure-type

filtration device according to the first embodiment.

FIG. 11 is a sectional view of the pressure-type

filtration device according to a second embodiment of the

present invention.

FIG. 12 is a top plan view of the pressure-type

filtration device according to the second embodiment.

FIG. 13 is an explanatory drawing of the raw water paths

and so on in the filtration step of the pressure-type

filtration device according to the second embodiment.

FIG. 14 is an explanatory drawing of raw water paths and

so on in the backwashing step of the pressure-type filtration

device according to the second embodiment.

FIG. 15 is an explanatory drawing of raw water paths and

so on in the water discarding step of the pressure-type

filtration device according to the second embodiment.

FIG. 16A is a plane view to explain a variation of the

valve element in the selector valve of the pressure-type

filtration device according to the first embodiment.

FIG. 16B is an explanatory drawing of the constitution of

the valve element shown in FIG. 16A.

FIG. 17 is an explanatory drawing of a variation of the

pressure-type filtration device according to the second

embodiment.

FIG. 18 is an explanatory drawing of other variations of

the pressure-type filtration device according to the second

embodiment.

[Description of Embodiments]

[0017] The embodiments will now be described with reference

to the accompanying drawings.

[0018] <<First Embodiment>>

FIG. 1 is a top plan view of a pressure-type filtration

device 1 according to a first embodiment of the present

invention. Further, FIG. 2 is a front view of the pressure

type filtration device 1 and FIG. 3 is an explanatory drawing

of the internal structure of the pressure-type filtration

device 1.

[0019] The pressure-type filtration device 1 according to

the present embodiment is a pressure-type filtration device to

which the principle of the self-backwashing equipment is

applied. As illustrated in FIGs. 1 through 3, the pressure

type filtration device 1 comprises a filtration device main

body 10, a raw water pipe 20, filtered water pipes 22a - 22c,

a water discarding pipe 23, and so on.

[0020] The raw water pipe 20 (FIG. 3) is a pipe to supply

water to be purified by the filtration device main body 10

(which will be denoted hereinafter as raw water) to the

filtration device main body 10. The filtration device main

body 10 is a device that filters raw water supplied through

the raw water pipe 20 and output filtration result of raw

water (which will be denoted hereinafter as filtered water)

from a filtered water outlet 22d (FIG. 2) which is an open end

of the filtered water pipe 22a. As illustrated in FIGS. 1 and

3, in the filtration device main body 10, a raw water chamber

11, six filtration chambers 12 and a purified water chamber 13

are arranged. Moreover, a selector valve 30 is attached to the

central part of the upper surface central part of the

filtration device main body 10.

[0021] The selector valve 30 is a six-way valve that is

developed for the pressure-type filtration device 1 (the

filtration device main body 10). As illustrated in FIG. 3, the

selector valve 30 is formed by a selector valve body part 30a

that is housed in an outer shell 10a of the filtration device

main body 10 and a drive part 30b that protrudes from the

outer shell 10a.

[0022] The selector valve body part 30a is a unit (valve

device) where a cylindrical valve element 40 moves vertically

and rotates in a cylindrical valve box having an upper lid and

a bottom lid. As shown in FIG. 3, at the upper part of the

side surface of the valve box of the selector valve body part

a, six raw water inlets 32a are arranged with a constant

angular space. Further, at the part of the side surface of the

valve box of the selector valve body part 30a lower than each

raw water inlet 32a, six raw water outlets 32b are arranged

with a constant angular space. Moreover, an opening 32c, which

acts as an outlet of washing waste water (details will be

discussed later), is formed on the lower surface of the

selector valve body part 30a, and the opening 32c is connected

to a waste water pipe 24 extending vertically downward to the

outside of the outer shell 10a of the filtration device main body 10.

[0023] Before explaining the details of the selector valve

(the selector valve body part 30a and the drive part 30b),

constitution of the pressure-type filtration device 1 other

than the selector valve 30 will be discussed.

[0024] The raw water chamber 11 (FIG. 3) is a part

(vessel) into which raw water is supplied through the raw

water pipe 20. The shape of the raw water chamber 11 (shapes

of partitions which are components of the raw water chamber 11

and to which the selector valve body part 30a is fitted, and

so on) is determined in such a manner that the raw water inlet

32a of the selector valve body part 30a acts as an outlet of

the raw water supplied through the raw water pipe 20.

Furthermore, it is determined that only six raw water outlets

32b of the selector valve body part 30a act as outlets of raw

water supplied to the selector valve body part 30a from the

raw water inlets 32a.

[0025] Each filtration chamber 12 (FIG. 3) is a unit where

filtering material 12a is arranged on a water collection board

(partition plate formed by strainer and the like for

supporting the filtering material 12a, collecting filtered

water and scattering backwashing water). Note that, the

filtration chamber 12 according to the present embodiment is a

unit of which the water collection board 15 functions as the

filtered water outlet. Further, although anthracite, manganese

sand and filtration gravel are depicted as the filtering

materials 12a in FIG. 3, the filtering material 12a is for

removing impurities included in raw water, and, kind, particle

diameter and uniformity coefficient of the filtering material

12a are determined based on components and density of the

removal object.

[0026] As illustrated in FIG. 1, each filtration chamber

12 has shape obtained by the shape dividing the principal part

of the inner space of the filtration device main body 10

(outer shell 10a) into six in radial directions from the

center of the filtration device main body 10. The selector

valve 30 is attached to the filtration device main body 10 in

such a manner that raw water can be supplied to each

filtration chamber 12 through only corresponding raw water

outlet 32b.

[0027] The purified water chamber 13 (FIG. 3) is space in

the filtration device main body 10 lower than water collection

boards 15 in six filtration chambers 12. As shown in the

Figure, in the purified water chamber 13, one end of a

filtered water pipe 22b is inserted which extends to the lower

surface of the selector valve body part 30a in the form of

accommodating the waste water pipe 24 therein. To the part of

this filtered water pipe 22b higher than the upper surface of

the filtering material 12a, one end of a filtered water pipe

22c which extends approximately horizontally to the outside of

the outer shell 10a of the filtration device main body 10 is

connected. A filtered water pipe 22a is connected to the other

end of the filtered water pipe 22c, and the filtered water

supplied to the purified water chamber 13 from each filtration

chamber 12 passes the filtered water pipes 22b, 22c and 22a in

this order and then flows out from the filtered water outlet

22d.

[0028] Note that, purpose of raising the filtered water to

a position above the upper surface of the filter material 12a

before flowing out the filtered water is so that there is an

amount of water covering the filter material 12a in each

filtration chamber 12, even if a supply of raw water decreases

by some kind of factors.

[0029] As illustrated in FIG. 2, at a part of the filtered

water pipe 22a near the filtered water outlet 22d, a filtered

water valve 27 to permit or stop the outflow of filtered water

from the filtered water outlet 22d is arranged. The filtered

water pipe 22a is connected to the waste water pipe 24 in the part upstream from the filtered water valve 27 via the water discarding pipe 23. The water discarding valve 28 is mounted on the way of the water discarding pipe 23, which is opened when filtered water flowing within the filtered water pipe 22a is drained from the waste water pipe 24.

[00301 Constitution of the selector valve 30 will be

described with reference to FIGS. 4 to 8. Note that, FIG. 4 is

a sectional view of the selector valve 30 cut by a plane

passing through the center of the selector valve 30. However,

hatching is omitted in this sectional view. (A) and (B) in

FIG. 5 are a plane view and a side view of the valve element

, respectively. FIG. 6 is a development view of a shaft part

which is a component of the selector valve 30. FIG. 7 is an

explanatory drawing of position relations that the valve

element 40 and the raw water outlet 32b of the selector valve

can take, and FIG. 8 is a section view of the valve element 30

along the VIII-VIII line of Fig. 7 viewing from the arrow

direction. FIG. 9 is an explanatory drawing of the

constitution of the selector valve 30.

[0031] As illustrated in FIG. 4, the selector valve 30 is

divided into a selector valve body part 30a and a drive part

b by an isolation plate 38.

[0032] To start with, constitution of the selector valve

body part 30a is described. The selector valve body part 30a

comprises the isolation plate 38, a housing 31, the valve

element 40 and so on.

[00331 The housing 31 is a member functioning as a valve

box of the selector valve body part 30a by being fixed to the

isolation plate 38.

[0034] At the upper part of the side surface of the

housing 31, six circular raw water inlets 32a having the same

diameter are arranged with a constant angular space. At the

part of the side surface of the housing 31 lower than the each

raw water inlet 32a, six circular raw water outlets 32b having the same diameter are arranged with a constant angular space.

The diameter of this raw water outlet 32b is bigger than the

diameter of the raw water inlet 32a (in the present embodiment

approximately 2.5 times of the diameter of raw water inlet

32a). Further, the housing 31, as shown in the Figure, has the

shape that allows the valve element 40 therein to be lowered

down to a position where the top surface of the valve element

is lower than the lower end of each raw water outlet 32b.

[00351 The valve element 40 is a member having a shape

shown in FIG. 5 (A) and 5 (B). That is, the valve element 40 is

a substantially columnar member. Further, five raw water

channels 41a communicating between the top and side surfaces

of the valve element 40 and a washing waste water channel 41b

communicating between the bottom and side surfaces of the

valve element 40 are formed in the valve element 40.

Hereinafter, the openings of the raw water channel 41a on the

side surface and on the top surface of the valve element 40

are referred to as the side surface opening and the upper

surface opening of the raw water channel 41a, respectively.

Similarly, the openings of the washing waste water channel 41b

on the side surface and on the bottom surface of the valve

element 40 are referred to as the side surface opening and the

lower surface opening of the washing waste water channels 41b,

respectively.

[00361 Each raw water channel 41a formed in the valve

element 40 is a channel having approximately the same diameter

(inner diameter) as the raw water inlet 32a. Further, five raw

water channel 41a are in the same shape as shown in FIGs 5(A)

and 5(B).

[0037] The washing waste water channel 41b formed in the

valve element 40 is a channel the cross sectional area of

which is larger than that of the raw water channel 41a (in the

present embodiment, a circular channel the inner diameter of

which is substantially 2.5 times larger than that of the raw water channel 41a). The six channels (five raw water channels

41a and one washing waste water channel 41b) in the valve

element 40 are formed in such a manner that center intervals

between every two adjacent side surface openings are

equiangular intervals (that is, 60 degrees intervals).

Further, on the side surface of the valve element 40, 0-ring

grooves (which has dovetail groove shape) each surrounding the

surface side opening are formed, and the valve element 40 is

placed within the housing 31 in a condition where an 0-ring is

inserted in each 0-ring groove.

[00381 As illustrated in FIG, 4, a stem 45 for rotating

and vertically moving the valve element 40 in the housing 31

is provided at the center part of the valve element 40. The

stem 45 extends into the drive part 30b through an opening

(bearing part) of the isolation plate 38, and the opening of

the isolation plate 38 is configured in such a manner that

allows the stem 45 to be rotated and vertically moved while

ensuring airtightness and watertightness.

[00391 Hereinafter, the drive part 30b of the selector

valve 30 will be described. The drive part 30b of the selector

valve 30 is a unit for vertically moving and rotating the

valve element 40 in the selector valve body part 30a (housing

31). As shown in FIG. 4, the drive part 30b comprises a

housing 50, a piston 53 and a shaft part 60.

[0040] The housing 50 is formed by a cylindrical cylinder

part 52 and a top cover 51 covering the upper end of the

cylinder part 52, and so on. The top cover 51 is provided with

a compressed air introducing port 51a from which compressed

air is introduced when the piston 53 is moved downward.

Further, the isolation plate 38 constituting the bottom

surface of the drive part 30b is provided with a compressed

air introducing port 38a from which compressed air is

introduced when the piston 53 is moved upward.

[0041] The piston 53 is formed by sealing a lower end of a cylindrical member 53b having outer diameter slightly smaller than the inner diameter of the cylinder part 52 by a disc shaped member 53a. Around the upper and lower sides of the member 53b of the piston 53, 0-ring grooves are formed, and the piston 53 is inserted into the housing 50 (cylinder part

52) in a condition where an 0-ring is fitted in each 0-ring

groove.

[0042] Near the upper end of the piston 53 (member 53b), a

plurality of (in the present embodiment, six number of) cam

followers 54 are attached at equal angular intervals.

[0043] The shaft part 60 is a cylindrical member that is

fixed to the housing 50 (top cover 51). A cam groove 61 having

the shape shown in FIG. 6 is formed on the outside surface of

the shaft part 60.

[0044] Namely, the cam groove 61 on the outside surface of

the shaft part 60 has a shape that allows a relative angle of

the cam follower 54 to the shaft part 60 to be changed for 30

degrees in a certain direction when the cam follower 54

positioned at the lower end of the cam groove 61 reaches the

upper end of the cam groove 61 along the cam groove 61.

Further, the cam groove 61 has a shape that allows the

relative angle of the cam follower 54 to the shaft part 60 to

be changed for 30 degrees in the same direction when the cam

follower 54 positioned at the upper end of the cam groove 61

reaches the lower end of the cam groove 61 along the cam

groove 61.

[0045] Moreover, the selector valve 30 is configured in

such a manner that sizes of each part (length in the vertical

direction of the cam groove 61, installation angle of the

valve element 40 to the stem 45, etc.) satisfies the following

conditions.

(1) The upper surface of the valve element 40 becomes a

position lower than the lower end of each raw water outlet 32b

formed in the housing 31 when the cam follower 54 is positioned at the lower end of the cam groove 61(see. FIG. 4).

(2) States shown in FIGS. 7 to 9, namely, states where the

side surface openings of the channels 41a and 41b in the valve

element 40 are respectively opposed to the raw water outlets

32b of the selector valve body part 30a, are provided when the

cam follower 54 is positioned at the upper end of the cam

groove 61.

[0046] Hereinafter, function of the pressure-type

filtration device 1 will be discussed. Note that, in the

following discussion, a control device is defined as a device

(a kind of computer) to control the filtered water valve 27,

the water discarding valve 28 and the selector valve 30 of the

pressure-type filtration device 1. The normal position is a

position of the valve element 40 in the housing 31 when the

cam follower 54 is positioned at the lower end of the cam

groove 61 (see FIG. 4). The backwashing position is a position

of the valve element 40 in the housing 31 when the cam

follower 54 is positioned at the upper end of the cam groove

61 (see FIG. 9). The backwashing position of a filtration

chamber 12 is defined as the backwashing position, among six

backwashing positions where the orientations (rotary angles in

the housing 31) of the valve element 40 are different, to

which the side surface opening of the washing waste water

channel 41b is directed.

[0047] In the filtering step of raw water by the pressure

type filtration device 1, the filtered water valve 27, the

water discarding valve 28 and the selector valve 30 are

controlled by the control device in such a manner that the

filtered water valve 27 is opened, the water discarding valve

28 is closed and the valve element 40 is positioned in the

normal position. The state where the filtered water valve 27

is opened, the water discarding valve 28 is closed and the

valve element 40 is positioned in the normal position will be

denoted hereinafter as the filtering state.

[0048] The upper surface of the valve element 40

positioned in the normal position is lower than the lower end

of each raw water outlet 32b of the housing 31 (FIG. 4).

Further, the shape of each raw water outlet 32b is the same.

Accordingly, when the filtering state is formed, raw water

flowing into the selector valve body part 30a through the six

raw water inlets 32a from the raw water chamber 11 is equally

distributed to the six filtration chambers 12 through the six

raw water outlets 32b.

[0049] Further, the filtering state is the state where the

filtered water valve 27 is opened and the water discarding

valve 28 is closed, and therefore filtered water supplied to

the purified chamber 13 from each filtration chamber 12 flows

out from the filtered water outlet 22d through the filtered

water pipe 22 (filtered water pipes 22b, 22c and 22a).

[0050] When a predetermined backwashing start condition,

e.g., a backwashing start condition such as "filtration of raw

water is performed for a prescribed time(e.g., 24 to 48

hours)" or "filtration resistance rises and reaches the set

value" is satisfied, the control device performs backwashing

step of the following contents.

[0051] The control device, to start with, performs a first

control processing to form "a backwashing state where the

filtered water valve 27 is closed, and water discarding valve

28 is closed, and the valve element 40 is positioned in the

backwashing position for a certain filtration chamber 12". The

control performed to the selector valve 30 in the first

control processing is control to rotate the valve element 40,

which is positioned in the normal position, 30 degrees and

thereby raise it to the backwashing position (that is, control

to raise the piston 53 positioned at the lower end to the

upper end). The control performed to the selector valve 30 in

the first control processing may be control in which the

rotation angle of the valve body 40 is not 30 degrees, so long as it can move the valve element 40 to the backwashing position.

[0052] When the valve element 40 is positioned in the

backwashing position for a filtration chamber 12 (which will

be hereinafter denoted as the backwash target filtration

chamber 12), the side surface opening of each channel 41a, 41b

in the valve element 40 is opposed to each raw water outlet

32b of the housing 31 (see FIG. 9). Further, the raw water

channel 41a, the washing waste water channel 41b communicates

between the side and upper surfaces of the valve element 40,

between the side and lower surfaces of the valve element 40,

respectively, and each raw water channel 41a has approximately

the same shape.

[0053] Therefore, when the valve element 40 is positioned

in the backwashing position for the backwash target filtration

chamber 12, the raw water flowing into the selector valve body

part 30a from the raw water chamber 11 is evenly distributed

to five filtration chambers 12 other than the backwash target

filtration chamber 12 through five raw water channels 41a of

the valve element 40.

[0054] Further, when the valve element 40 is positioned in

the backwashing position for the backwash target filtration

chamber 12, the raw water introducing port of the backwash

target filtration chamber 12 (the raw water outlet 32b from

which raw water is supplied to the backwash target filtration

chamber 12) is communicated with the waste water pipe 24 by

the washing waste water channel 41b of the valve element 40.

That is, the backwash target filtration chamber 12 goes into a

state where water can flow from the lower part to the upper

part because the raw water introducing port is open (raw water

is not introduced from the raw water introducing port).

Further, when both of the filtered water valve 27 and the

water discarding valve 28 are closed, the filtrated water in

the purified water chamber 13 cannot flow out to the filtered water pipe 22b.

[00551 Therefore, when the above backwashing state, as

schematically shown in FIG. 10B, the backwash target

filtration chamber 12 is backwashed with filtered water from

five filtration chambers 12 other than the backwash target

filtration chamber 12, and washing waste water from the

backwash target filtration chamber 12 flows out to the outside

through the washing waste water channel 41b (see FIG. 9) and

the waste water pipe 24.

[00561 The control device which finished the first control

processing of the above contents waits until a backwashing

time (e.g., 6 to 7 minutes) passes which is set beforehand as

time to perform backwashing.

[0057] When the backwashing time passes, the control

device performs control to the selector valve 30 (drive part

b), the control being to lower the piston 53 positioned at

the upper end to the lower end and then raise it to the upper

end. When this control (which will be referred to as backwash

target change control) is performed, the valve element 40 is

positioned in the backwashing position for the filtration

chamber 12 next to the filtration chamber 12 that is

backwashed, and therefore the control device waits until the

backwashing time passes.

[00581 When the backwashing time passes, the control

device performs the backwash target change control again, and

then waits until the backwashing time passes.

[00591 The control device repeats the above control until

backwashing of every filtration chambers 12 is completed. When

backwashing of every filtration chamber 12 is completed, the

control device performs control to the selector valve 30

(drive part 30b), the control being to lower the piston 53

positioned at the upper end to the lower end, and controls the

water discarding valve 28 so as to open.

[00601 When the above control is performed to the selector valve 30 and the water discarding valve 28, "a state where the filtered water valve 27 is closed, the water discarding valve

28 is opened and the valve element 40 is positioned in the

normal position" is formed. Therefore, it follows that

filtered water from six filtration chambers 12 flows out from

the waste water pipe 24 through the water discarding pipe 23

as schematically shown in FIG. 10C.

[0061] The control device that forms the above state

(which will hereinafter be termed the water discarding state)

by controlling the selector valve 30 and the water discarding

valve 28 waits until a time (e.g., ten minutes) set beforehand

passes. When that time passes, the control device controls the

filtered water valve 27 and the water discarding valve 28 such

that the filtered water valve 27 is opened and the water

discarding valve 28 is closed. Namely, the control device

performs control to restore the pressure-type filtration

device 1 to the state where raw water is filtered (state where

filtered water from six filtration chambers is flowed out from

the filtered water outlet 22d). Then, the control device

having finished the control enters a state of monitoring

whether the backwashing start condition is satisfied.

[0062] As discussed above, the pressure-type filtration

device 1 according to the present embodiment includes six

filtration chambers 12 arranged concentrically and the raw

water chamber 11 arranged in the central part of the

filtration chambers 12. Moreover, in the pressure-type

filtration device 1, raw water is supplied to each filtration

chambers 12 from each of the raw water outlets 32b having the

same shape provided in the selector valve body part 30a (see

FIG. 4). Accordingly, in the pressure-type filtration device

1, substantially uniform amount of raw water is supplied to

each filtration chamber 12 in the filtration step.

[0063] Further, the pressure-type filtration device 1

includes the purified water chamber 13 which can act as the filtered water path that introduces filtered water from the filtration chambers 12 other than the backwash target filtration chamber 12 to the filtered water outlet (the water collection board 15) of the backwash target filtration chamber

12. Moreover, this purified water chamber 13 is provided at

the central part (just below six filtration chambers 12, see

FIG. 3) of six filtration chambers 12. Therefore, in the

pressure-type filtration device 1, a total of water filtered

in the filtration chambers 12 other than the backwash target

filtration chamber 12 is supplied to the backwash target

filtration chamber 12 in the backwashing step.

[0064] Furthermore, the filtration device main body 10 of

the pressure-type filtration device 1 has such constitution

that the raw water chamber 11, a plurality of filtration

chambers 12, and so on are placed in one outer shell 10 with

no gaps therebetween. Accordingly, the pressure-type

filtration device 1 can be installed in a smaller area than

the pressure-type filtration device to which other

constitution is adopted to equalize filtered water supplied to

each filtration chamber (the pressure-type filtration device 2

which will be discussed later and the like).

[0065] <<Second Embodiment>>

FIG. 11 is a sectional view of the pressure-type

filtration device 2 according to a second embodiment of the

present invention, and FIG. 12 is a top plan view of the

pressure-type filtration device 2.

[0066] The pressure-type filtration device 2 according to

the present embodiment is an device to which the principle of

the self backwashing equipment is applied as with the

pressure-type filtration device 1.

[0067] As illustrated in FIG. 11 and FIG. 12, the

pressure-type filtration device 2 includes six filtration

chambers 70, a raw water chamber 71, a waste water chamber 72,

a purified water chamber 73, a raw water pipe 80 for supplying raw water to the raw water chamber 71, and so on. Further, the pressure-type filtration device 2 (FIG. 11) has such constitution that the raw water chamber 71, the waste water chamber 72 and the purified water chamber 73 are lined up to the vertical direction in FIG. 11.

[00681 Each filtration chamber 70 of the pressure-type

filtration device 2 is a filtration chamber (filter) having

the same configuration, which includes a water collection

board 70c and filtering material (in FIG. 11, anthracite,

manganese sand and filtration gravel) arranged on the water

collection board 70c. As shown in FIG. 12, six filtration

chambers 70 of the pressure-type filtration device 2 is

arranged concentrically centering on the part consisting of

the raw water chamber 71, the waste water chamber 72 and so

on.

[00691 As shown in FIG. 11, a raw water introducing port

a of each filtration chamber 70 is connected to the raw

water chamber 71 and the waste water chamber 72 by a pipe

system of the same constitution including a three-way valve

75. Note that the pipe system connecting each filtration

chamber 70 to the raw water chamber 71 and the waste water

chamber 72 may be the pipe system constituted by using pipes

having the same inner diameter or the pipe system constituted

by using pipes having pipes having different inner diameters

as pipes constituting the pipe system (a pipe connecting the

three-way valve 75 to the raw water introducing port 70a, and

so on) so long as it allows a required quantity of filtered

water to be flowed back in the filtration chamber 70 in the

backwashing step.

[0070] The filtered water outlet 70b of each filtration

chamber 70 is connected to the purified water chamber 73. The

pipe of the approximately same shape (inner diameter, length)

is used for connection between the filtered water outlet 70b

of each filtration chamber 70 and the purified water chamber

73.

[0071] To the waste water chamber 72, a waste water pipe

83 is attached, which extends vertically downward from the

center part of the lower surface of the waste water chamber 72

and penetrates the purified water chamber 73. In the purified

water chamber 73, one end of a filtered water pipe 81a is

inserted which extends to the lower surface of the waste water

chamber 72 in the form of accommodating the waste water pipe

83 therein. To the part of the filtered water pipe 81a higher

than the upper surface of the filtering material in each

filtration chamber 70, one end of a filtered water pipe 81b

the other end of which functions as a filtered water outlet

81d. At the part of the filtered water pipe 81b near the

filtered water outlet 81d, a filtered water valve 76 is

provided, and the part of the filtered water pipe 81b upstream

from the filtered water valve 76 and the waste water pipe 83

are connected via a water discarding pipe 82 provided with a

water discarding valve 77.

[0072] A function of pressure-type filtration device 2 will

be explained.

At the time of the filtration step of raw water by the

pressure-type filtration device 2, the valves 75-77 are

controlled by a control device for the pressure-type

filtration device 2, and "a filtering state where the filtered

water valve 76 is opened, the water discarding valve 77 is

closed, and each three-way valve 75 communicates the

filtration chamber 70 with the raw water chamber 71" is

formed.

[0073] As already explained, each pipe system connecting

the filtration chamber 70 with the raw water chamber 71 and

waste water chamber 72 has the same constitution. Therefore,

when each three-way valve 75 connects the filtration chamber

with the raw water chamber 71, raw water supplied from the

outside through raw water pipe 80 is equally distributed to the six filtration chambers 70 through the raw water chamber

71 as schematically shown in FIG. 13. The filtration state is

a state where each filtration chamber 70 is communicated with

the raw water chamber 71 by each three-way valve 75, the

filtered water valve 76 is opened and water discarding valve

77 is closed. Accordingly, it flows that, when the filtering

state is formed, filtered water from each filtration chamber

, to which the same quantity of raw water is supplied, flows

out from the filtered water outlet 81d of the filtered water

pipe 81b through the purified water chamber 73 and filtered

water pipe 81a.

[0074] Moreover, when the predetermined backwashing

condition is satisfied, the control device performs control

processing for backwashing of the following contents.

[0075] The control device having started the control

processing for backwashing, to begin with, performs a first

control processing to form "a backwashing state where the

filtered water valve 76 and the water discarding valve 77 are

closed, one three-way valve 75 communicates the filtration

chamber 70 with the waste water chamber 72, and each of the

other three-way valves 75 communicates the filtration chamber

with the raw water chamber 71."

[0076] When the above backwashing state is formed, the

filtration chamber 70 (denoted hereinafter as the backwash

target filtration chamber 70) that is communicated with the

waste water chamber 72 through the three-way valve 75 goes

into a state where water can flow from the lower part to the

upper part. Also, it comes to raw water in the raw water

chamber 71 to be equally distributed to only five filtration

chambers 70 other than the backwash target filtration chamber

70. Therefore, it follows that, when the above backwashing

state is formed, the backwash target filtration chamber 70

(the left side filtration chamber 70 in FIG. 11) is backwashed

with filtered water from five filtration chamber 70 other than the backwash target filtration chamber 70, and washing waste water flows out to the outside through the waste water chamber

72 and the waste water pipe 83 as schematically shown in FIG.

14.

[0077] The control device having finished the first

control processing waits until a backwashing time set

beforehand as an execution time of backwashing passes. Then,

when the backwashing time passes, the control device performs

the first control processing again in the form that the

filtration chamber 70 communicating with the waste water

chamber 72 is changed to another filtration chamber 70 to

which backwashing is not carried out, and thereafter waits

until the backwashing time passes.

[0078] The control device repeats the above processing

until backwashings of all filtration chamber 70 are completed.

When backwashings of all filtration chamber 70 are completed,

the control device forms "a water discarding state where the

filtered water valve 76 is closed, the water discarding valve

77 is opened, and each three-way valve 75 communicates the

filtration chamber 70 with the raw water chamber 71" by

controlling valves 75-77. When the water discarding state is

formed, it follows that filtered water from six filtering

chambers 70 of the pressure-type filtration device 2 flows out

from the waste water pipe 83 through the water discarding pipe

82 as shown in FIG. 15.

[0079] Thereafter, the control device waits until a preset

time (e.g., ten minutes) passes, and controls the filtered

water valve 76 and the water discarding valve 77 such that the

filtered water valve 76 is opened and the water discarding

valve 77 is closed when the preset time passes. That is, the

control device performs control to restore the pressure-type

filtration device 2 to the state where raw water is filtered

(state where filtered water from six filtration chambers 70 is

flowed out from the filtered water outlet 81a). Then, the control device having finished the control terminates the backwashing control processing and enters into the status of monitoring whether the backwashing start condition is satisfied.

[00801 As discussed above, the pressure-type filtration

device 2 according to the present embodiment includes six

filtration chambers 70 arranged concentrically and the raw

water chamber 71 arranged in the central part of the

filtration chambers 70. Moreover, in the pressure-type

filtration device 2, raw water in the water chamber 71 is

supplied to the raw water introducing port 70a of each

filtration chambers 70 by the pipe system having the same

constitution. Accordingly, in the pressure-type filtration

device 2, substantially uniform amount of raw water is

supplied to each filtration chamber 70 in the filtration step.

[0081] Further, the pressure-type filtration device 2

includes the purified water chamber 73 which can act as the

filtered water path that introduces filtered water from the

filtration chambers 70 other than the backwash target

filtration chamber 70 to the filtered water outlet 70b of the

backwash target filtration chamber 70. This purified water

chamber 73 is provided at the central part of six filtration

chambers 70, and the filtered water outlet 70b of each

filtration chamber 70 is connected to the purified water

chamber 73 by the pipe having the same shape. Therefore, it

follows that, in the backwashing step of the pressure-type

filtration device 2, substantially uniform amount of raw water

is supplied to each filtration chamber 70.

[0082] <<Modified Mode>> The reason why the pressure-type filtration device of

each embodiment is configured as a device where the number of

the filtration chambers is six and one filtration chamber is

backwashed in the backwashing step is that it is assumed that

the flow velocity required for backwashing (hereinafter, backwashing step flow velocity) is 1,000 m/day and the filtration speed in the backwashing step (hereinafter, backwashing step filtration speed) is 200 m/day during development of each pressure-type filtration device. That is, when the backwashing flow velocity and the backwashing step filtration speed are the above values, the flow velocity

(filtered water quantity) required to backwash one filtration

chamber 70 can be covered by filtered water from five

filtration chambers 70. The pressure-type filtration device of

each embodiment is therefore configured as a device where the

number of the filtration chambers is six and one filtration

chamber is backwashed in the backwashing step. However, the

number of filtration chambers may not necessarily be six, and

the number of filtration chambers that are backwashed in the

backwashing step may not necessarily be one.

[00831 Specifically, the value of "the backwashing flow

velocity / backwashing step filtration speed" varies according

to the application (filtering material in each filtration

chamber) of the pressure-type filtration device. Therefore,

for example, when the backwashing flow velocity is 1,000 m/day

and the backwashing step filtration speed is 500 m/day, the

number of the filtration chambers that act as raw water supply

sources for the backwashing and the number of the filtration

chambers that are backwashed in the backwashing step may be 2N

(in N is natural number) and N, respectively. Further, when

the value of "the backwashing flow velocity / backwashing step

filtration speed" is approximately three, the number of the

filtration chambers that act as raw water supply sources for

the backwashing and the number of the filtration chambers that

are backwashed in the backwashing step may be 3N and N,

respectively.

[0084] Note that the pressure-type filtration device 2

according to the second embodiment can be operated in such a

manner that two filtration chambers 70 are simultaneously backwashed in the backwashing step by altering control to six three-way valves 75 without changing the constitution.

Further, the pressure-type filtration device 1 according to

the first embodiment can be modified to the device of which

two filtration chambers 70 are simultaneously backwashed in

the backwashing step by changing the valve element 40 to the

valve element 40' shown in FIGS. 16A and 16B, namely, the

valve element 40' provided with four raw water channels 41a

and two washing waste water channels 41b therein.

[00851 As described above, in the pressure-type filtration

device 1, the selector valve 30 where the diameter of the raw

water outlet 32b is approximately 2.5 times larger than the

diameter of the raw water inlet 32a and the inner diameter of

the washing waste water channel 41b of the valve element 40 is

approximately 2.5 times larger than the inner diameter of the

raw water channel 41a, is used. Purpose of using the selector

valve 30 having such constitution in the pressure-type

filtration device 1 is to prevent that filtered waste quantity

that flows backward in the backwash target filtration chamber

is limited by channel resistance of the washing waste water

channels 41b and the raw water outlets 32b (see FIG. 9).

Further, in order to cause the required amount of filtered

water to flow backward in the filtration chamber 12, the

cross-section ratio of the washing waste water 41b and the raw

water channel 41a may be larger/smaller than the above

mentioned value.

[00861 The pressure-type filtration device 2 according to

the second embodiment may be modified into the pressure-type

filtration device 2' having constitution shown in FIG. 17.

That is, the pressure-type filtration device 2 may be modified

into the pressure-type filtration device 2' in which two two

way valves 75a and 75b are used instead of each three-way

valve 75.

[0087] The pressure-type filtration device 1, 2 may be modified into such devices where the waste water pipe 24 and the filtered water pipe 22b, the waste water pipe 83 and the filtered water pipe 81a does not constitutes a double pipe.

[00881 The pressure-type filtration device 2 may be

modified into such devices in which the selector valve 30 is

used instead of six three-way valves 75 and the waste water

chamber 72. Note that modification of the pressure-type

filtration device 2 into such devices can be made, for

example, by adopting configuration where raw water in the raw

water chamber 71 flows into the selector valve body part 30a

through each raw water inlet 32a, each raw water outlet 32b of

the selector valve body part 30a is connected to the raw water

inlet 70a of each filtration chamber 70 by pipe, and the

opening 32c is connected to waste water pipe 83 by pipe, as

shown in FIG, 18.

[00891 The plurality of filtration chambers (12, 70) in the

pressure-type filtration device 1, 2 are not necessarily

arranged in a perfect circle so long as they are arranged

concentrically. Therefore, the filtration device main body 10

(see FIG. 2) of the pressure-type filtration device 1 may be

modified into a unit comprising outer shell 10a having

noncylindrical shape. The pressure-type filtration device 2 may

be modified into such devices where distances between some

filtration chambers 70 and the raw water chamber 71 are

longer/shorter than distances between the other filtration

chambers 70 and the raw water chamber 71. Further, the plurality

of filtration chambers in the pressure-type filtration device 1,

2 are not necessarily arranged with a constant angular space.

Therefore, the pressure-type filtration device 1 may be modified

into such devices having a semicircle shape or a fan shape in a

top view. Also, the pressure-type filtration device 2 may be

modified into such devices where a plurality of filtration

chambers 70 is arranged along an arc such as a semicircle.

[Description of the Reference Numerals]

[0090] 1, 2 pressure-type filtration device

filtration device main body

a outer shell

11, 71 raw water chamber

12a filtering material

12, 70 filtration chamber

13, 73 purified water chamber

water collection board (filtered water outlet)

18 maintenance port

, 80 raw water pipe

22a - 22c, 81a, 81b filtered water pipe

22d filtered water outlet

23, 82 water discarding pipe

24, 83 waste water pipe

27, 76 filtered water valve

28, 77 water discarding valve

selector valve

a selector valve body part

b drive part

31, 50 housing

32a raw water inlet

32b raw water outlet

32c opening

38a, 51a pressurized air introducing port

38 isolation plate

valve element

41a raw water channel

41b washing waste water channel

stem

52 cylinder part

53 piston

54 cam follower shaft part

61 cam groove

a raw water introducing port

b filtered water outlet

c water collection board

72 waste water chamber

three-way valve

a, 75b two-way valve

Claims (3)

1. A pressure-type filtration device comprising:

a plurality of filtration chambers each of which has

filtering material therein and which are arranged

concentrically;

a raw water distribution part which is arranged at a

center part of the plurality of filtration chambers in a plan

view and to which raw water to be filtered is supplied from

the outside;

a flow channel system which connects raw water

introducing ports of the plurality of filtration chambers and

the raw water distribution part and is capable of attaining a

first state and a second state, the first state being a state

in which the raw water in the raw water distribution part is

distributed to the raw water introducing ports of the

plurality of filtration chambers, and the second state being a

state in which a raw water introducing port of a backwash

target filtration chamber and a waste water pipe are connected

and raw water in the raw water distribution part is

distributed only to the raw water introducing ports of the

filtration chambers other than the backwash target filtration

chamber; and

a purified water chamber into which filtered water from

the filtered water outlets of the plurality of filtration

chambers flows, and which act as a filtered water path which

guides the filtered water from the plurality of filtration

chambers other than the backwash target filtration chamber to

the filtered water outlet of the backwash target filtration

chamber, wherein the plurality of filtration chambers, the raw

water distribution part and the purified water chamber are

provided in a filtration body, and

the plurality of filtration chambers have shapes formed

by equally dividing an inner part of the filtration body excluding the raw water distribution part and the purified water chamber along radial directions from the center of the filtration body.

2. The pressure-type filtration device according claim 1,

wherein the flow channel system includes discrete channel

systems which are provided to each filtration chamber and each

of which has one or more valve devices to alternatively

connect the raw water introducing port of the filtration

chamber to the raw water distribution part and the waste water

pipe.

3. The pressure-type filtration device according claim 1,

wherein the filtration body is circular in cross-section view.