AU2016240897A1

AU2016240897A1 - Pressure-type filtration device

Info

Publication number: AU2016240897A1
Application number: AU2016240897A
Authority: AU
Inventors: Masanobu Sakurai
Original assignee: Hitachi Zosen Corp
Current assignee: Hitachi Zosen Corp
Priority date: 2015-03-31
Filing date: 2016-03-30
Publication date: 2017-11-16
Anticipated expiration: 2036-03-30
Also published as: WO2016159080A1; PH12017501794A1; JP6569272B2; JP2016193382A; CN107614082A; AU2016240897B2; CN107614082B; PH12017501794B1

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]

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. [Summary] [Technical Problem] [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.

[0006] It is therefore the object of the present invention to provide a pressure-type filtration device, which includes a plurality of filtration chambers, where each filtration chamber can be cleaned individually and quantity of raw water to be supplied to each filtration chamber in the filtration step can be made approximately uniform.

[Solution to Problem] [0007] To accomplish the above object, a pressure-type filtration device according to the present invention 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 to the raw water introducing ports 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.

[0008] Namely, the pressure-type filtration device of the present invention 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 of the present invention 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 the pressure-type filtration device where quantity of raw water to be supplied to each filtration chamber in the filtration step is approximately uniform.

[0009] Note that the plurality of filtration chambers in the pressure-type filtration device of the present invention are not necessarily arranged in a perfect circle so long as they are arranged concentrically. Therefore, the pressure-type filtration device of the present invention may be realized as an 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 chamber in the pressure-type filtration device of the present invention are not necessarily arranged with a constant angular space. Therefore, the pressure-type filtration device of the present invention may be realized, for example, as an device of which filtration chambers are arranged in an approximately semicircular shape.

[0010] As the channel system in the pressure-type filtration device of the present invention, various systems with different specific configurations can be adopted. For example, it is possible to adopt the 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, the pressure-type filtration device of the present invention may be realized as the device "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." Note that, when this constitution is adopted, it is desirable to adopt the filtration body, the cross section shape of which is polygonal or circular.

[0012] Further, the pressure-type filtration device of the present invention may be realized as the device "wherein the channel system is 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 of the pressure-type filtration device of the present invention 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 to backwashing and a 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 chamber 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.

[Advantageous Effects of Invention] [0015] According to the present invention, it is possible to easily realize the pressure-type filtration device where 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. 1QA 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. IOC 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 Embodiments 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 30a, 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 30 (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 outlet 32b of the selector valve body part 30a are 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 15 (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 chamber 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.

[0030] 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 40, respectively. FIG. 6 is a development view of a shaft part 60 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 30b 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.

[0033] 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 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 is lower than the lower end of each raw water outlet 32b.

[0035] 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 top surface of the valve element 40 are referred to as the side surface opening and the upper surface opening of the washing waste water channel 41b, respectively.

[0036] Each raw water channel 41a formed in the valve element 40 is a channel having approximately the same diameter (in 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 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, O-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 O-ring is inserted in each O-ring groove.

[0038] 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 watertightness and airtightness .

[0039] 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 in 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, O-ring grooves are formed, and the piston 53 is inserted into the housing 50 (cylinder part 52) in a condition where an O-ring is fitted in each O-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 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 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 selector valve 30 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 selector valve 30 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 chamber 12 through the six raw water outlets 32b in the selector valve body part 30a.

[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 washing 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 chamber 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.

[0055] 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 chamber 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 and the waste water pipe 24.

[0056] 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 30b), 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.

[0058] When the backwashing time passes, the control device performs the backwash target change control again, and then waits until the backwashing time passes.

[0059] The control device repeats the above control processing 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 then raise it to the upper end, and controls the water discarding valve 28 so as to open.

[0060] When the above control is performed to 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 chamber 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 and a plurality of filtration chambers 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 chamber 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.

[0068] 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.

[0069] As shown in FIG. 11, a raw water introducing port 70a 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 so long as it allows a required quantity of filtered water to be flowed back in the filtration chamber 70.

[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 from the center art 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. As shown in FIG. 11, a raw water introducing port 70a of each filtration chamber 70 is connected to the raw water chamber 71 and the waste water chamber 72 by a pipe system having 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 so long as it allows a required quantity of filtered water to be flowed back in the filtration chamber 70. Therefore, when each three-way valve 75 connects the filtration chamber 70 with the raw water chamber 71, raw water supplied from the outside through raw water pipe 80 is equally distributed to the six filtration chamber 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 7 6 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 70, 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 7 6 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 70 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 7 5 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 from the backwash target filtration chamber 70 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 backwashing target filtration chamber 70 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 7 5 communicates the filtration chamber 70 with the raw water chamber 71" by controlling valves 75-77. When the backwashing state is formed, it follows that filtered water from six filtering chamber 70 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 7 6 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 chamber 70 is flowed out from the filtered water outlet 81a) . Then, the control device having finished the control enters a state of monitoring whether the backwashing start condition is satisfied. 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.

[0080] 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 backwash target filtration chamber 70 is connected to the purified water chamber 7 3 by the pipe having the same shape. Therefore, it follows that, in the backwashing step of the pressure-type filtration device 1, 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 an 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. 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 an 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.

[0083] 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 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 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 chamber 70 are 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 chamber 70 are 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 channel 41a and two washing waste water channel 41b therein.

[0085] 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 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.

[0086] 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.

[0088] The pressure-type filtration device 2 may be modified into such devices in which the selector valve 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.

[0089]

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

[DESCRIPTION OF THE REFERENCE NUMERALS] [0090] I, 2 pressure-type filtration device 10 filtration device main body 10a outer shell II, 71 raw water chamber 12a filtering material 12, 70 filtration chamber 13, 73 purified water chamber 15 water collection board (filtered water outlet) 18 maintenance port 20, 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 30 selector valve 30a selector valve body part 30b drive part 31, 50 housing 32a raw water inlet 32b raw water outlet 32c opening 38a, 51a pressurized air introducing port 38 isolation plate 40 valve element 41a raw water channel 41b washing waste water channel 45 stem 52 cylinder part 53 piston 54 cam follower 60 shaft part 61 cam groove 70a raw water introducing port 70b filtered water outlet 70c water collection board 72 waste water chamber 75 three-way valve 75a, 75b two-way valve

Claims

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 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.

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

3. 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.

4. The pressure-type filtration device according claim 2, wherein the filtration body is circular in cross-section view.