Title of Invention	SOLID-LIQUID SEPARATION SYSTEM
Abstract	Certain embodiments include a flocculation vessel having an array of stage plates parallel-arranged therein, and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough and outlet raw water with floes formed therein, the water circumventing route including a passage defined by and between paired stage plates, and a passage defined by and between a wall of the flocculation vessel and a stage plate end spaced therefrom at distances smaller than a spacing between the paired stage plates, and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces.

Title of Invention

SOLID-LIQUID SEPARATION SYSTEM

Abstract

Certain embodiments include a flocculation vessel having an array of stage plates parallel-arranged therein, and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough and outlet raw water with floes formed therein, the water circumventing route including a passage defined by and between paired stage plates, and a passage defined by and between a wall of the flocculation vessel and a stage plate end spaced therefrom at distances smaller than a spacing between the paired stage plates, and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces.

Full Text	SOLID-LIQUID SEPARATION SYSTEM CROSS-REFERENCE TO RELATED APPLICATION This application is based upon and claims the benefit of priority from the Japanese Patent Application No. 2009-238689, filed on October 15,2009; the entire contents of which are incorporated herein by reference. FIELD Embodiments described herein relate generally to a solid-liquid separation system adapted to separate solids from solid-containing raw water in a course of water treatment such as effluent treatment or water purification. BACKGROUND For water treatments in processes for separating solids such as suspended matters or turbidity components, there has been frequent use of solid-liquid separation systems including a flocculation promoted by injection of an aggregating agent and an aggregation aid, and combined with a settling separation employing a gravity settling vessel. For instance, there was a solid-liquid separation system including a raw water pump adapted to send treating raw water to an admixing vessel. At the admixing vessel, there was an aggregating agent injected by an aggregating agent injector, and admixed to raw water by an admixer. Raw water admixed with the aggregating agent at the admixing vessel was sent to a reaction vessel. At the reaction vessel, there was an aggregation aid injected by an aggregation aid injector, and mixed with raw water by a mixer. Raw water mixed with the aggregation aid at the reaction vessel was sent to a flocculation vessel. At the flocculation vessel, raw water underwent a promoted aggregation by a floccultor to grow floes. Raw water containing floes formed at the flocculation vessel was sent to a gravity settling vessel. In the gravity settling vessel, raw water was let to stagnate for a required residence time or more, for causing floccs of solids of large specific gravities to settle out by differences in specific gravity between floccs and water, to separate floccs from raw water. In the solid-liquid separation system, after settling of floccs, the gravity settling vessel had a clear supernatant liquid as treated water to be taken out. For the settling employing the gravity, such solid-liquid separation systems have been configured for using an aggregating agent to cluster suspended matters in raw water to grow as floes, to make use of differences in specific gravity relative to water, for causing floes of suspended matters having larger specific gravities than water to settle out, to obtain a clear supernatant as treated water, thus achieving a separation (gravity settling) of raw water into solids (suspended matters) and liquid (treated water). Such solid-liquid separation systems have been bound to letting raw water stagnate in the gravity settling vessel for residence times to be long as necessary to cause floes to settle out, with the needs for an enlarged capacity of gravity settling vessel. In some recent systems there has been use of an inclined plate or inclined pipes aiming at increasing the efficiency of separation to minimize the capacity of gravity settling vessel, and affording to have an improved treating rate, but with limitations in reduction in time of treatment and minimization in capacity of gravity settling vessel. As an alternate solution to the employment of gravity settling accompanied by such issues as the time of treatment to be reduced and the capacity of gravity settling vessel to be minimized, there has been use of centrifugal separators including liquid cyclones. Those centrifugal separators have been adapted to cause sand-containing raw water to swirl therein, making use of centrifugal forces to separate sandy particles with larger diameters than specified from raw water. Employing centrifugal forces greater in acceleration than the gravity, such the centrifugal separators have enabled separating sandy particles as solids within shorter periods than by the gravity, affording to reduce capacities of centrifugal separators relative to capacities of gravity settling vessels. However, in any centrifugal separator configured to swirl raw water at high speeds to produce centrifugal forces, causing incoming floes to spin at high speeds, if floes having been grown for separation were weak-bonded, they would be torn into pieces sometimes too small for the centrifugal separator to work as necessary. Accordingly, for treatments of raw water to separate such substances as floes easy to break, there has been unavoidable use of gravity settling vessels with great capacities accommodating long treatment times. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a solid-liquid separation system according to a first embodiment. Fig. 2 is a longitudinal section of a flocculation vessel in the solid-liquid separation system of Fig. 1. Fig. 3 is a sectional illustration of stage plates and side walls built in the flocculation vessel in the solid-liquid separation system of Fig. 1. Fig. 4 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a second embodiment Fig. 5 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a third embodiment. Fig. 6 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a modification of the third embodiment. Fig. 7 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a fourth embodiment. Fig. 8 is a combination of perspective illustrations of lugs in the flocculation vessel of Fig. 7. Fig. 9 is a fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a modification of the fourth embodiment. Fig. 10 is a longitudinal section of a flocculation vessel in a solid-liquid separation system according to a fifth embodiment. Fig. 11A and Fig. 11B are combination of longitudinal section and cross sections of a flocculation vessel in a solid-liquid separation system according to a sixth embodiment DETAILED DESCRIPTION There will be described solid-liquid separation systems according to embodiments, with reference to the drawings. According to the embodiments, the solid-liquid separation systems are each adapted to work for water treatment such as effluent treatment or water purification of raw water containing solids such as suspended matters or turbidity components, to separate raw water into solids and liquid, like solid-liquid separation systems in the past. Like elements are designated by like reference signs, for description with eliminated redundancy. According to certain embodiments, there is a solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water. The solid-liquid separation system includes a flocculation vessel, and a solid-liquid separator. The flocculation vessel has an array of stage plates parallel-arranged therein, and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with flocs formed therein, the water circumventing route including a passage defined by and between paired stage plates, and a passage defined by and between a stage plate end and a wall of the flocculation vessel. The stage plate end is spaced from the wall of the flocculation vessel at distances smaller than a spacing between the paired stage plates. The solid-liquid separator is configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces. (First embodiment) Referring now to Fig. 1, there is a solid-liquid separation system la according to a first embodiment that includes: an admixing vessel 11, to which raw water to be treated is inlet through a raw water pump 10; an aggregating agent injector 12 which injects an aggregating agent into raw water in the admixing vessel 11, where raw water is agitated with the aggregating agent injected therein; a reaction vessel 13, to which raw water is inlet from the admixing vessel 11; an aggregation aid injector 14 which injects an aggregation aid into raw water in the reaction vessel 13, where raw water is agitated together with the aggregation aid injected therein; a flocculation vessel 14 which serves, as raw water is inlet from the reaction vessel 13, to have solids therein grow into floes, so outlet raw water contains grown floes; and a solid-liquid separator 17 which serves, as raw water outlet from the flocculation vessel 14 is inlet through a water pump 16, to separate inlet raw water into flocs as solids and treated water. The aggregating agent injector 12 is configured for injection of an aggregating agent adapted to aggregate or flocculate suspended solids in raw water inlet from a water line LI to the admixing vessel 11. The aggregating agent injector 12 is adapted to inject a controlled dose of an adequate kind of aggregating agent selective from among inorganic fiocculants, such as poly aluminum chloride, alum or aluminum sulfate, ferric chloride, and poly iron sulfate, in accordance with the nature or properties of solids in raw water. The admixing vessel 11 has an admixer 111 for admixing particles of aggregating agent with raw water therein. The admixer 111 is configured to agitate raw water and aggregating agent particles, to have agent particles evenly admixed and distributed in raw water, providing flocs with increased tendencies to grow in the flocculation vessel 15a. The aggregation aid injector 14 is configured to inject, into raw water inlet from the admixing vessel 11 to the reaction vessel 13, an aggregation aid adapted to provide flocs in raw water with increased tendencies to cluster to get harder or enlarge, in order for the collection to be easy. The aggregation aid injector 14 is adapted to inject a controlled dose of an adequate kind of aggregation aid selective from among organic high-molecular fiocculants such as polyacrylamide and inorganic high-molecular fiocculants such as poly silica, in accordance with the nature or properties of solids in raw water. The reaction vessel 13 has a mixer 131 for mixing particles of aggregation aid with raw water therein. The mixer 131 is configured to agitate raw water and aggregation aid particles, to have aid particles evenly mixed and distributed in raw water, providing floes with increased tendencies to get denatured for easier collection at the flocculation vessel 15a. The flocculation vessel 15a is shaped in the form of e.g. a cuboid or rectangular parallelpiped, as illustrated in Fig. 2, and accommodates therein an array of stage plates 152 constituting obstacles of flowing raw water, cooperating with a vessel wall to define a water circumventing route working to conduct or guide raw water inlet from the reaction vessel 13, to circumvent (cause to meander) along surfaces and ends of stage plates 152. In other words, as illustrated in Fig. 2, the stage plates 152 are each fixed tight at either end thereof to joint to one of "a first side wall 151a and a second side wall 151b" (referred herein sometimes collectively to as "side walls 151") being vertical lateral parts of the vessel wall of the flocculation vessel 15a. Among the stage plates 152, those (152) in every pair of neighboring ones 152 are joined to different ones (151a, 151b) of the side walls 151, respectively. That is, the stage plates 152 are alternately joined to the first side wall 151a, or to the second side wall 151b, vice versa, so each stage plate 152 joined to the first side wall 151a, not to the second side wall 151b, is followed by a stage plate 152 joined to the second side wall 151b, not to the first side wall 151a Accordingly, raw water being inlet through a water inlet 153 is circumvented to meander rightwards and leftwards, alternately striking on the second side wall 151b and the first side wall 151a, to go through passages between stage plates 152, till it outflows at a water outlet 154. In the flocculation vessel 15a having the stage plates 152 arrayed as illustrated in Fig. 2, raw water is guided at any stage to flow through a vertical flexed passage defined by and between an edge end of a stage plate 152 and a facing region of a side wall 152, where raw water has increased flow velocities. As a result, at the next passage that is defined by and between a pair of horizontal stage plates 152, inflowing raw water has increased tendencies to undergo flow separation, meandering to flow, causing flocs formed in raw water to collide on the paired stage plates 152 by increased numbers of times. As flocs being formed have increased frequencies of collision on respective stage plates 152, they are the more toughened with internal voids tightened, thus getting stronger. As floes formed are subjected to increased frequencies of collision on stage plates 152, they have increased specific gravities, allowing for an increased efficiency of solid-liquid separation at the solid-liquid separator 17. As illustrated in Fig. 3, at any stage, the stage plate 152 installed to define a flexed passage has one end thereof spaced (for a necessary gap) at a distance 'a' from a corresponding region of the first side wall 151a or the second side wall 151b, and at the next passage, the paired stage plates 152 are spaced from each other with a secured interval 'b' (for a necessary pitch). Preferably, the interval 'b' should be greater than the distance 'a', such that b > a, for flocs to be formed stronger with increased frequencies of collision on stage plates 152. There is no limitation to the number of stage plates 152 to be installed, which may be increased or decreased as necessary. It is noted that the number of stages may well be increased with a commensurate increase in number of flexed passages, affording to have floes in raw water collide on wall surfaces (at side walls 151 and stage plates 152) by the more increased numbers of times. The flocculation vessel 15a may be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs or solids from adhering on stage plates 152 or side walls 151 of flocculation vessel 15a, with enhanced effects of flocculation. For instance, if the aggregating agent injector 12 injects a high-molecular aggregating agent, raw water has ion bonds formed therein by the aggregation effect. Principally, ion bonds have tendencies to adhere to submerged structures, so there may be flocs formed with increased tendencies to adhere to the side walls 151, the stage plates 152, and the like. Further, for instance, given flaws, if any, side walls 151 or stage plates 152 may tend to have flocs adhering to the spots. For such the interior of flocculation vessel 15a, there may be use of structural members made of inactive materials or covered with a coating, to prevent adhesion of flocs due to ion bonds or adhesion of flocks at flawed spots. For the flocculation vessel 15a, the structural or coating material used may well be Teflon ®, polyvinyl chloride, amorphous carbon, ceramics, glass, titanium oxide, or the like. The flocculation vessel 15a described has the water inlet 153 disposed at the top and the water outlet 154 disposed at the bottom, to conduct raw water from a top level of the flocculation vessel 15a to a bottom level of the flocculation vessel 15a, circumventing in horizontal or right-and-left directions, while such the mode of implementation is not restrictive subject to the provision of a water circumventing route. There may be an example of flocculation vessel implemented with a water inlet formed through a left (or right) lateral wall and a water outlet formed through a right (or left) lateral wall, to conduct raw water in between, circumventing in vertical or up-and-down directions. The solid-liquid separator 17 is configured to make inlet raw water swirl in spin therein, having developed centrifugal forces acting on flocs, as accelerations greater than the gravity, thereby spinning down floes at enhanced settling rates, for separation of raw water into flocs and treated water. The solid-liquid separator 17 in use may be a liquid cyclone. The solid-liquid separator 17 is configured to accelerate inlet raw water to swirl at adequate flow velocities for enhanced flocculation, as well as for enhanced separation of floes from raw water swirling at high speeds. Preferably, the water pump 16 should be adapted to send streams of raw water to the solid-liquid separator 17, with sufficient momenta for the solid-liquid separator 17 to have raw water swirl at adequate velocities for floc formation as well as for floc separation. According to the first embodiment described, there is a solid-liquid separation system la including a flocculation vessel 15a affording to form floes with increased strength and increased density. The solid-liquid separation system la according to the first embodiment permits employing a solid-liquid separator 17 adapted to make use of centrifugal forces and down-scaled relative to gravity settling equipment, allowing for a saved space for system installation. In the solid-liquid separation system la according to the first embodiment, the solid-liquid separator 17 is adapted to make use of centrifugal forces combined with the gravity to spin down floes. Accordingly, the solid-liquid separation system la permits floes to be settled out within shorter periods than in systems simply using the gravity, thus allowing for an enhanced efficiency of separation. (Second embodiment) Referring now to Fig. 4, according to a second embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15b substituting for the flocculation vessel 15a. Fig. 4(a) is a section of the flocculation vessel 15b, and Fig. 4(b), a perspective view in part of the flocculation vessel 15b including stage plates 152b. As illustrated in Fig. 4, the flocculation vessel 15b also accommodates therein an array of stage plates 152b cooperating with a vessel wall to define a water circumventing route, while being different in shape and arrangement of stage plates 152b from the flocculation vessel 15a described with reference to Fig. 2 and Fig. 3. In the flocculation vessel 15a illustrated in Fig. 2 and Fig. 3, at any stage, the stage plate 152 is fixed to join at an upstream end or edge thereof to one side wall 151, to be water-tight over width of that edge, and spaced at a downstream end or edge thereof from the opposite side wall 151 (for a necessary gap in between), to define a water-communicating area over width of this edge. Instead, in the flocculation vessel 15b shown in Fig. 4, at any stage there is a stage plate 152b fixed to join at either end or edge thereof to both side walls 151. In other words, the stage plate 152b is formed at an upstream end thereof with a plain edge for a water-tight joint, and has at a downstream end or edge thereof a cutout portion 152c partially cut out to provide an array of water-communicating slots. In the flocculation vessel 15b, such stage plates 152b are oriented to have their cutout portions 152c alternately joined to either side wall 151. In Fig. 4, the flocculation vessel 15b has a water inlet 153 at the top and a water outlet 154 at the bottom, to conduct raw water in between, along the water circumventing route that includes every stage a horizontal passage between paired stage plates 152b and a vertical flexed passage through a cutout portion 152c of a corresponding stage plate 152b. In the flocculation vessel 15b, at any stage, raw water flows through a vertical flexed passages including slots of cutout portion 152c, where raw water has an unbalanced distribution of streams, getting turbulent, so at the next passage, given rotational momenta about flow direction, eddy currents develop, causing flocs to collide on surfaces of e.g. paired stage plates 152b by increased numbers of times, with grown densities of flocs. It is noted that alternate stage plates 152b have their cutout portions 152c close to either side wall 151, which preferably should have an array pitch 'c' substantially equal to a spacing 'b' between neighboring stage plates 152b times two or times a multiple number of two. At any cutout portion 152c, the slot shape is not limited to a rectangular form as illustrated in Fig. 4(b), and may be formed in a triangular shape, or curved like a semi-circle or such. The flocculation vessel 15b may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent floes from adhering on stage plates 152b or side walls 151 of flocculation vessel 15b, with enhanced effects of flocculation, like the flocculation vessel 15a. According to the second embodiment described, there is a solid-liquid separation system including a flocculation vessel 15b adapted for flocs to have increased frequencies of collision on stage plates 152b, affording to form floes with increased strength and increased density, thus permitting employment of a solid-liquid separator making use of centrifugal forces, allowing for a saved space for system installation, and an enhanced efficiency of solid-liquid separation. (Third embodiment) Referring now to Fig. 5, according to a third embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15c substituting for the flocculation vessel 15a. Fig. 5(a) is a section of the flocculation vessel 15c, and Fig. 5(b), a perspective view in part of the flocculation vessel 15c including stage plates 152. As illustrated in Fig. 5, the flocculation vessel 15c is different from the flocculation vessel 15a described with reference to Fig. 2 and Fig. 3, in that it has an array of stage plates 152 each provided with a set of baffle plates 155. More specifically, in the flocculation vessel 15c shown in Fig. 5, at any stage, the stage plate 152 is spaced from a side wall 151, at a downstream end or edge thereof, which has a set of aligned baffle plates 155 fixed thereto. Each baffle plate 155 is oriented to extend in a flow direction of raw water of an associated vertical flexed passage (where raw water vertically turns). Through the passage provided with baffle plates 155, flowing raw water has an unbalanced distribution of streams, getting turbulent, so at the next passage, raw water has swirling streams about flow direction of raw water. Those flocs failing to follow such swirling streams are caused to collide on surfaces of e.g. paired stage plates 152 by increased numbers of times, so they are toughened with internal voids tightened, getting stronger. At any set of baffle plates 155, the plate shape is not limited to a triangular form as illustrated in Fig. 5(b), and may be formed in a rectangular shaped, or curved like a semi-circle or such. Swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, so at any stage plate 152 provided with baffle plates 155 aligned along an edge thereof as illustrated in Fig. 5(b), preferably the baffle plates 155 should be arrayed by a center pitch 'd' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two. The flocculation vessel 15c may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs from adhering on stage plates 152 or side walls 151 of flocculation vessel 15c, with enhanced effects of flocculation, like the flocculation vessel 15a. According to the third embodiment described, there is a solid-liquid separation system including a flocculation vessel 15c adapted for floes to have increased frequencies of collision on stage plates 152, affording to form floes with increased strength and increased density, thus permitting employment of a solid-liquid separator making use of centrifugal forces, allowing for a saved space for system installation, and an enhanced efficiency of solid-liquid separation. (Modification) Fig. 6 illustrates an example of flocculation vessel 15d in a solid-liquid separation system according to a modification of the third embodiment. Fig. 6(a) is a section of the flocculation vessel 15d, and Fig. 6(b), a perspective view in part of the flocculation vessel 15d including stage plates 152. In the flocculation vessel 15c shown in Fig. 5, at any stage, the stage plate 152 is spaced from a corresponding side wall 151, at a downstream end or edge thereof, which has a set of aligned baffle plates 155 fixed thereto, the baffle plate 155 being oriented to extend in a flow direction of raw water of an associated vertical flexed passage (where raw water vertically turns). In the flocculation vessel 15d shown in Fig. 6, at any stage, there is another set of aligned baffle plates 155 fixed at an upstream end or edge of one of paired stage plates 152 and oriented to extend in opposition to a set of aligned baffle plates 155 fixed like the third embodiment to a downstream end or edge of the other of the paired stage plates 152 spaced from a corresponding side wall 151. Like the third embodiment, swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, so at each stage plate 152 provided with baffle plates 155 aligned along an edge thereof as illustrated in Fig. 6(b), preferably the baffle plates 155 should be arrayed by a center pitch 'd' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two. According to this modification also, there is a solid-liquid separation system including a flocculation vessel 15d adapted for flocs to have increased frequencies of collision on stage plates 152, affording to form flocs with increased strength and increased density, thus allowing for an enhanced efficiency of solid-liquid separation. (Fourth embodiment) Referring now to Fig. 7, according to a fourth embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15e substituting for the fiocculation vessel 15a. Fig. 7(a) is a section of the fiocculation vessel 15e, and Fig. 7(b), a perspective view in part of the fiocculation vessel 15e including stage plates 152. As illustrated in Fig. 7, the fiocculation vessel 15e is different from the fiocculation vessel 15a described with reference to Fig. 2 and Fig. 3, in that it has an array of stage plates 152 each provided with a set of lugs 156 configured as small pieces fixed thereto. Each stage plate 152 has on the upside a set of lugs 156 standing with their normals oriented in a flow direction of the passage to face coming-up streams of raw water, and arrayed in a matrix with rows or columns aligned in the flow direction. In the fiocculation vessel 15e, at any stage, the lugs 156 work to cause swirling streams of raw water about flow direction in the passage between paired stage plates 152, having flocs therein collide on surfaces of e.g. paired stage plates 152 by increased numbers of times. Swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, and preferably, lugs 156 on each stage plate 152 should be passage-transversely arrayed by a geometrical-center or gravity-center pitch or pitches 'e' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two. Further, those lugs 156 neighboring in the raw water flow direction should be passage-longitudinally arrayed by a geometrical-center or gravity-center pitch or pitches 'f substantially equal to a spacing 'a' between a stage plate end and a wall of the fiocculation vessel. At any stage, the shape of any lug 156 is not limited to a cuboid or rectangular parallelepiped as illustrated in Fig. 7, and may well be formed triangular or cylindrical as shown in Fig. 8, for instance. Lug shapes shown in Fig. 8(a) and Fig. 8(b) are both effective to prevent floes or solids in raw water from stagnating about lugs 156. The fiocculation vessel 15e may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs from adhering on stage plates 152 or side walls 151 of fiocculation vessel 15e, with enhanced effects of fiocculation, like the fiocculation vessel 15a. According to this embodiment also, there is a solid-liquid separation system including a flocculation vessel 15e adapted for flocs to have increased frequencies of collision on stage plates 152, affording to form flocs with increased strength and increased density, thus permitting employment of a solid-liquid separator making use of centrifugal forces, allowing for a saved space for system installation, and an enhanced efficiency of solid-liquid separation. (Modification) Fig. 9 illustrates an example of modification of the flocculation vessel 15e in the solid-liquid separation system according to the fourth embodiment In the flocculation vessel 15e shown in Fig. 7, lugs 156 arrayed on a stage plate 152 are oriented in a direction according to a raw water flow direction. In Fig. 9, lugs 156 set on a stage plate 152 are oriented to have their longitudinal directions offset from a raw water flow direction. These lugs 156 are each elongate in a direction inclined at an angle relative to the raw water flow direction, affording to prevent floes or solids in raw water from stagnating about lugs 156. Among the lugs 156, neighboring ones in passage-transversely rows are not all inclined at an angle, but inclined in a staggered manner as illustrated in Fig. 9, affording for increased tendencies to develop swirling streams of raw water. Like the fourth embodiment, swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, and preferably, lugs 156 on each stage plate 152 should be passage-transversely arrayed by a geometrical-center or gravity-center pitch or pitches 'e' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two. According to this modification, even with lugs 156 having longitudinal directions inclined relative to a raw water flow direction, there is a solid-liquid separation system adapted for floes to have increased frequencies of collision on stage plates 152, affording to form floes with increased strength and increased density, thus allowing for an enhanced efficiency of solid-liquid separation. (Fifth embodiment) Referring now to Fig. 10, according to a fifth embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15f substituting for the flocculation vessel 15a As illustrated in Fig. 10, the flocculation vessel 15f is configured with a first flocculator portion 157a and a second flocculator portion 157b. The first flocculator portion 157a and the second flocculator portion 157b accommodate therein their arrays of stage plates 152, while the stage plates 152 in the first flocculator portion 157a are arrayed by a pitch 'bl' different from a pitch 'b2' by which the stage plates 152 in the second flocculator portion 157b are arrayed. Generally, the wider the pitch of stage plates 152, the more moderate the flow velocity of raw water, with flocs subjected decreased frequencies of collision on stage plates 152. On the hand, the narrower the pitch of stage plates 152, the faster the flow velocity of raw water, with flocs subjected increased frequencies of collision on stage plates 152. If the frequency of collision on stage plates 152 is increased before floes get hard, there come up anxieties about possible rupture of flocs due to the impact of collision on stage plates 152. To this point, the first flocculator portion 157a is configured to have floes therein moderately collide on stage plates 152, causing floes to gradually grow to get larger, before raw water flows into the second flocculator portion 157b configured to have floes collide on stage plates 152 by increased numbers of times, to toughen flocs. In the example of Fig. 10, the flocculation vessel 15f is composed of two flocculator portions being the first flocculator portion 157a having stage plates 152 arrayed with a spacing 'bl' and the second flocculator portion 157b having stage plates 152 arrayed with a spacing 'b2' different from the spacing 'bl', while the spacing between stage plates is not limited to the two. Also the proportion of flocculator portions 157a and 157b different in stage plate spacing is not limited. For instance, there may be combination of a moderate flocculator portion responsible for a beginning quarter of flocculation, and a fast flocculator portion responsible for the remaining three quarters of flocculation. There may be a repeated flocculation implemented with a flocculator sequence including in order a moderate flocculator, a fast flocculator, a moderate flocculate, and a fast flocculator. There may also be a rate of flocculation gradually changed from a moderate to a fast. The flocculation vessel 15f may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs from adhering on stage plates 152 or side walls 151 of flocculation vessel 15f, with enhanced effects of flocculation, like the flocculation vessel 15a. According to this modification, even in use of the flocculation vessel 15f, there is a solid-liquid separation system adapted for flocs to have increased frequencies of collision on stage plates 152, affording to form flocs with increased strength and increased density, thus allowing for an enhanced efficiency of solid-liquid separation. There is use of moderate water flows permitting floes to be grown large, combined with fast water flows permitting floes to be toughened, thus affording to form large and hard flocs easy to separate at a solid-liquid separator. This permits employment of a solid-liquid separator adapted for centrifugal separation, allowing for a saved space for system installation, and an enhanced efficiency of separation. (Sixth embodiment) Referring now to Fig. 11A and Fig. 11B, according to a sixth embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15g substituting for the flocculation vessel 15a. Fig. 11A is a section of the flocculation vessel 15g, and Fig. 11B, a combination of sectional top views in part of the flocculation vessel 15g including stage plates 152b and 152c. As illustrated in Fig. 11A and Fig. 11B, the flocculation vessel 15g has a cylindrical vessel wall accommodating an array of annular first stage plates 152c and circular second stage plates 152d alternately fit in the vessel wall. The first stage plates 152c each have an outer circumference with a diameter matching a diameter of an inner circumference of the wall of flocculation vessel 15g. The second stage plates 152d each have an outer circumference with a diameter smaller than the diameter of the inner circumference of the wall of flocculation vessel 15g. The first stage plates 152c and the second stage plates 152d are supported by pillars 157, and have their pillar insertion holes h1 and h2. In the flocculation vessel 15g, the first stage plates 152c and the second stage plates 152d are alternately supported by the pillars 157. At the flocculation vessel 15g, inlet raw water is guided to flow through a water passage defined by a central hole of a first stage plate 152c, and a water passage defined by and between an outer periphery as an outer end of a second stage plate 152d and a corresponding region of the wall flocculation vessel 15g. After that, raw water is likewise guided to alternately pass water passages provided through first stage plates 152c and passages provided outside second stage plates 152d. At each first stage plate 152c, the passage provided through the central hole has a passage area SI, and at each second stage plate 152d, the passage provided outside the outer periphery has a passage area S2. As the passage area SI is set to be equal to the passage area S2, i.e. SI = S2, raw water has an equivalent flow in travel from any first stage plate 152c to the next second stage plate 152d, and in travel from any second stage plate 152d to the next first stage plate 152c. The stage plates 152c and 152d may be arrayed with a retained spacing, or may have varied spacing distances to change the flow velocity, as described in conjunction with the fifth embodiment. According to this embodiment, even in use of the cylindrical flocculation vessel 15g, there is a solid-liquid separation system adapted to develop swirling streams of raw water, having floes collide on stage plates 152c and 152d, affording to form large and hard floes. Further, the cylindrical configuration permits withstanding pressures in a facilitated manner relative to using typical cuboid flocculation vessels, affording to reduce vessel wall thickness. The flocculation vessel 15g may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent floes from adhering on side walls 151, stage plates 152c or 152d, or pillars 157 of flocculation vessel 15g, with enhanced effects of flocculation, like the flocculation vessel 15a. According to this embodiment, even in use of the cylindrical flocculation vessel 15g, there is a solid-liquid separation system adapted to have floes collide on stage plates 152c and 152d by increased numbers of times, affording to provide floes with increased strength and increased densities, permitting employment of a solid-liquid separator adapted for centrifugal separation, allowing for a saved space for system installation, and an enhanced efficiency of separation. Further, the employment of a cylindrical flocculation vessel 15g allows for a facilitated design of flocculation vessel 15g in view of working environment under pressure. While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms: furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. What is claimed is: 1. A solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising: a flocculation vessel comprising: an array of stage plates parallel-arranged therein; and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with flocs formed therein, the water circumventing route comprising: a passage defined by and between paired stage plates; and a passage defined by and between a wall of the flocculation vessel and a stage plate end spaced therefrom at distances smaller than a spacing between the paired stage plates; and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces. 2. A solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising: a flocculation vessel comprising: an array of stage plates parallel-arranged therein; and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with floes formed therein, the water circumventing route comprising: a passage defined by and between paired stage plates; and a passage defined by and between a wall of the flocculation vessel and a stage plate end cut out in part; and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate floes as solids from raw water, making use of centrifugal forces. 3. The solid-liquid separation system according to claim 2, wherein the stage plate end constitutes part of one of the paired stage plates, and has an array of cutouts formed by a pitch or pitches substantially equal to a spacing between the paired stage plates times two or times a multiple number of two. 4. A solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising: a flocculation vessel comprising: an array of stage plates parallel-arranged therein; and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with floes formed therein, the water circumventing route comprising: a passage defined by and between paired stage plates provided at a plate end thereof with a buffle plate set arranged to have a normal at a baffling side of any buffle plate therein in a raw water flow direction of the passage; and a passage defined by and between a wall of the flocculation vessel and a stage plate end; and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces. 5. The solid-liquid separation system according to claim 4, wherein the plate end provided with the buffle plate set constitutes part of one of the paired stage plates, and the other of the paired stage plates has another buffle plate set arranged at an end portion thereof opposing the plate end in the raw water flow direction and extending in parallel with the plate end. 6. The solid-liquid separation system according to claim 4 or 5, wherein the plate end provided with the buffle plate set constitutes part of one of the paired stage plates, and the buffle plate set comprises a set of buffle plates arrayed at an interval or intervals substantially equal to a spacing between the paired stage plates times two or times a multiple number of two. 7. A solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising: a flocculation vessel comprising: an array of stage plates parallel-arranged therein; and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with floes formed therein, the water circumventing route comprising: a passage defined by and between paired stage plates provided with a lug set configured to obstruct streams of raw water; and a passage defined by and between a wall of the flocculation vessel and a stage plate end; and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate floes as solids from raw water, making use of centrifugal forces. 8. The solid-liquid separation system according to claim 7, wherein the lug set is provided on one of the paired stage plates, and comprises a set of lugs arrayed at an interval or intervals substantially equal to a spacing between the paired stage plates times two or times a multiple number of two. 9. The solid-liquid separation system according to claim 7, wherein the lug set is provided on the paired stage plates, and comprises a set of lugs each elongate in a direction inclined relative to a raw water flow direction of the passage between the paired stage plates. 10. The solid-liquid separation system according to claim 9, wherein the set of lugs comprises subsets thereof each composed of neighboring lugs elongate in directions inclined relative to the raw water flow direction at angles meeting a prescribed relationship. 11. The solid-liquid separation system according to claim 10, wherein the subsets of the set of lugs each comprise a group of neighboring lugs arrayed along the raw water flow direction by a gravity center pitch substantially equal to a spacing between the wall of the flocculation vessel and the stage plate end. 12. A solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising: a flocculation vessel comprising: a cylindrical vessel wall; an array of annular first stage plates and circular second stage plates alternately fit in the vessel wall, the first stage plates each having an outer circumference thereof matching an inner circumference of the vessel wall, the second stage plates each having an outer circumference thereof smaller than the inner circumference of the vessel wall; and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water through a sequence of passages therein, and outlet raw water with floes formed therein, the sequence of passages alternately including: a passage defined by a central hole of a corresponding one of the first stage plates; and a passage defined by and between an outer end of a corresponding one of the second stage plates and a corresponding region of the vessel wall; and a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces. 13. The solid-liquid separation system according to claim 1,2,3,4,5,6,7,8,9,10,11, or 12, wherein the array of stage plates has stage plates therein arrayed by pitches including a pitch for stage plates defining anterior passages of the water circumventing route near to an inlet of the flocculation vessel, set larger than a pitch for stage plates defining posterior passages of the water circumventing route.

Full Text

SOLID-LIQUID SEPARATION SYSTEM

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the Japanese Patent Application No. 2009-238689, filed on October 15,2009; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a solid-liquid separation system adapted to separate solids from solid-containing raw water in a course of water treatment such as effluent treatment or water purification.

BACKGROUND

For water treatments in processes for separating solids such as suspended matters or turbidity components, there has been frequent use of solid-liquid separation systems including a flocculation promoted by injection of an aggregating agent and an aggregation aid, and combined with a settling separation employing a gravity settling vessel.

For instance, there was a solid-liquid separation system including a raw water pump adapted to send treating raw water to an admixing vessel. At the admixing vessel, there was an aggregating agent injected by an aggregating agent injector, and admixed to raw water by an admixer. Raw water admixed with the aggregating agent at the admixing vessel was sent to a reaction vessel. At the reaction vessel, there was an aggregation aid injected by an aggregation aid injector, and mixed with raw water by a mixer. Raw water mixed with the aggregation aid at the reaction vessel was sent to a flocculation vessel. At the flocculation vessel, raw water underwent a promoted aggregation by a floccultor to grow floes. Raw water containing floes formed at the flocculation vessel was sent to a gravity settling vessel. In the gravity settling vessel, raw water was let to stagnate for a required residence time or more, for causing floccs of solids of large specific gravities to settle out by differences in specific gravity between floccs and water, to separate floccs from raw water. In the solid-liquid separation system, after settling of floccs, the gravity settling vessel had a clear supernatant liquid as treated water to be taken out.

For the settling employing the gravity, such solid-liquid separation systems have been configured for using an aggregating agent to cluster suspended matters in raw water to grow as floes, to make use of differences in specific gravity relative to water, for causing floes of suspended matters having larger specific gravities than water to settle out, to obtain a clear supernatant as treated water, thus achieving a separation (gravity settling) of raw water into solids (suspended matters) and liquid (treated water).

Such solid-liquid separation systems have been bound to letting raw water stagnate in the gravity settling vessel for residence times to be long as necessary to cause floes to settle out, with the needs for an enlarged capacity of gravity settling vessel.
In some recent systems there has been use of an inclined plate or inclined pipes aiming at increasing the efficiency of separation to minimize the capacity of gravity settling vessel, and affording to have an improved treating rate, but with limitations in reduction in time of treatment and minimization in capacity of gravity settling vessel.

As an alternate solution to the employment of gravity settling accompanied by such issues as the time of treatment to be reduced and the capacity of gravity settling vessel to be minimized, there has been use of centrifugal separators including liquid cyclones. Those centrifugal separators have been adapted to cause sand-containing raw water to swirl therein, making use of centrifugal forces to separate sandy particles with larger diameters than specified from raw water. Employing centrifugal forces greater in acceleration than the gravity, such the centrifugal separators have enabled separating sandy particles as solids within shorter periods than by the gravity, affording to reduce capacities of centrifugal separators relative to capacities of gravity settling vessels.

However, in any centrifugal separator configured to swirl raw water at high speeds to produce centrifugal forces, causing incoming floes to spin at high speeds, if floes having been grown for separation were weak-bonded, they would be torn into pieces sometimes too small for the centrifugal separator to work as necessary. Accordingly, for treatments of raw water to separate such substances as floes easy to break, there has been unavoidable use of gravity settling vessels with great capacities accommodating long treatment times.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram of a solid-liquid separation system according to a first embodiment.

Fig. 2 is a longitudinal section of a flocculation vessel in the solid-liquid separation system of Fig. 1.

Fig. 3 is a sectional illustration of stage plates and side walls built in the flocculation vessel in the solid-liquid separation system of Fig. 1.

Fig. 4 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a second embodiment

Fig. 5 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a third embodiment.

Fig. 6 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a modification of the third embodiment.

Fig. 7 is a combination of longitudinal section and fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a fourth embodiment.

Fig. 8 is a combination of perspective illustrations of lugs in the flocculation vessel of Fig. 7.

Fig. 9 is a fragmentary perspective illustration of a flocculation vessel in a solid-liquid separation system according to a modification of the fourth embodiment.

Fig. 10 is a longitudinal section of a flocculation vessel in a solid-liquid separation system according to a fifth embodiment.

Fig. 11A and Fig. 11B are combination of longitudinal section and cross sections of a flocculation vessel in a solid-liquid separation system according to a sixth embodiment

DETAILED DESCRIPTION

There will be described solid-liquid separation systems according to embodiments,
with reference to the drawings. According to the embodiments, the solid-liquid separation
systems are each adapted to work for water treatment such as effluent treatment or water
purification of raw water containing solids such as suspended matters or turbidity components, to separate raw water into solids and liquid, like solid-liquid separation systems in the past. Like elements are designated by like reference signs, for description with eliminated redundancy.

According to certain embodiments, there is a solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water. The solid-liquid separation system includes a flocculation vessel, and a solid-liquid separator. The flocculation vessel has an array of stage plates parallel-arranged therein, and a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with flocs formed therein, the water circumventing route including a passage defined by and between paired stage plates, and a passage defined by and between a stage plate end and a wall of the flocculation vessel. The stage plate end is spaced from the wall of the flocculation vessel at distances smaller than a spacing between the paired stage plates. The solid-liquid separator is configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces.

(First embodiment)

Referring now to Fig. 1, there is a solid-liquid separation system la according to a first embodiment that includes: an admixing vessel 11, to which raw water to be treated is inlet through a raw water pump 10; an aggregating agent injector 12 which injects an aggregating agent into raw water in the admixing vessel 11, where raw water is agitated with the aggregating agent injected therein; a reaction vessel 13, to which raw water is inlet from the admixing vessel 11; an aggregation aid injector 14 which injects an aggregation aid into raw water in the reaction vessel 13, where raw water is agitated together with the aggregation aid injected therein; a flocculation vessel 14 which serves, as raw water is inlet from the reaction vessel 13, to have solids therein grow into floes, so outlet raw water contains grown floes; and a solid-liquid separator 17 which serves, as raw water outlet from the flocculation vessel 14 is inlet through a water pump 16, to separate inlet raw water into flocs as solids and treated water.

The aggregating agent injector 12 is configured for injection of an aggregating agent adapted to aggregate or flocculate suspended solids in raw water inlet from a water line LI to the admixing vessel 11. The aggregating agent injector 12 is adapted to inject a controlled

dose of an adequate kind of aggregating agent selective from among inorganic fiocculants, such as poly aluminum chloride, alum or aluminum sulfate, ferric chloride, and poly iron sulfate, in accordance with the nature or properties of solids in raw water.
The admixing vessel 11 has an admixer 111 for admixing particles of aggregating agent with raw water therein. The admixer 111 is configured to agitate raw water and aggregating agent particles, to have agent particles evenly admixed and distributed in raw water, providing flocs with increased tendencies to grow in the flocculation vessel 15a.

The aggregation aid injector 14 is configured to inject, into raw water inlet from the admixing vessel 11 to the reaction vessel 13, an aggregation aid adapted to provide flocs in raw water with increased tendencies to cluster to get harder or enlarge, in order for the collection to be easy. The aggregation aid injector 14 is adapted to inject a controlled dose of an adequate kind of aggregation aid selective from among organic high-molecular fiocculants such as polyacrylamide and inorganic high-molecular fiocculants such as poly silica, in accordance with the nature or properties of solids in raw water.

The reaction vessel 13 has a mixer 131 for mixing particles of aggregation aid with raw water therein. The mixer 131 is configured to agitate raw water and aggregation aid particles, to have aid particles evenly mixed and distributed in raw water, providing floes with increased tendencies to get denatured for easier collection at the flocculation vessel 15a.

The flocculation vessel 15a is shaped in the form of e.g. a cuboid or rectangular parallelpiped, as illustrated in Fig. 2, and accommodates therein an array of stage plates 152 constituting obstacles of flowing raw water, cooperating with a vessel wall to define a water circumventing route working to conduct or guide raw water inlet from the reaction vessel 13, to circumvent (cause to meander) along surfaces and ends of stage plates 152. In other words, as illustrated in Fig. 2, the stage plates 152 are each fixed tight at either end thereof to joint to one of "a first side wall 151a and a second side wall 151b" (referred herein sometimes collectively to as "side walls 151") being vertical lateral parts of the vessel wall of the flocculation vessel 15a. Among the stage plates 152, those (152) in every pair of neighboring ones 152 are joined to different ones (151a, 151b) of the side walls 151, respectively. That is, the stage plates 152 are alternately joined to the first side wall 151a, or to the second side wall 151b, vice versa, so each stage plate 152 joined to the first side wall 151a, not to the second side wall 151b, is followed by a stage plate 152 joined to the second side wall 151b, not to the first side wall 151a Accordingly, raw water being inlet through a water inlet 153 is circumvented to meander rightwards and leftwards, alternately striking on the second side wall 151b and the first side wall 151a, to go through passages between stage plates 152, till it outflows at a water outlet 154.
In the flocculation vessel 15a having the stage plates 152 arrayed as illustrated in Fig. 2, raw water is guided at any stage to flow through a vertical flexed passage defined by and between an edge end of a stage plate 152 and a facing region of a side wall 152, where raw water has increased flow velocities. As a result, at the next passage that is defined by and between a pair of horizontal stage plates 152, inflowing raw water has increased tendencies to undergo flow separation, meandering to flow, causing flocs formed in raw water to collide on the paired stage plates 152 by increased numbers of times. As flocs being formed have increased frequencies of collision on respective stage plates 152, they are the more toughened with internal voids tightened, thus getting stronger. As floes formed are subjected to increased frequencies of collision on stage plates 152, they have increased specific gravities, allowing for an increased efficiency of solid-liquid separation at the solid-liquid separator 17.

As illustrated in Fig. 3, at any stage, the stage plate 152 installed to define a flexed passage has one end thereof spaced (for a necessary gap) at a distance 'a' from a corresponding region of the first side wall 151a or the second side wall 151b, and at the next passage, the paired stage plates 152 are spaced from each other with a secured interval 'b' (for a necessary pitch). Preferably, the interval 'b' should be greater than the distance 'a', such that b > a, for flocs to be formed stronger with increased frequencies of collision on stage plates 152. There is no limitation to the number of stage plates 152 to be installed, which may be increased or decreased as necessary. It is noted that the number of stages may well be increased with a commensurate increase in number of flexed passages, affording to have floes in raw water collide on wall surfaces (at side walls 151 and stage plates 152) by the more increased numbers of times.

The flocculation vessel 15a may be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs or solids from adhering on stage plates 152 or side walls 151 of flocculation vessel 15a, with enhanced effects of flocculation. For instance, if the aggregating agent injector 12 injects a high-molecular aggregating agent, raw water has ion bonds formed therein by the aggregation effect. Principally, ion bonds have tendencies to adhere to submerged structures, so there may be flocs formed with increased tendencies to adhere to the side walls 151, the stage plates 152, and the like. Further, for instance, given flaws, if any, side walls 151 or stage plates 152 may tend to have flocs adhering to the spots. For such the interior of flocculation vessel 15a, there may be use of structural members made of inactive materials or covered with a coating, to prevent adhesion of flocs due to ion bonds or adhesion of flocks at flawed spots. For the flocculation vessel 15a, the structural or coating material used may well be Teflon ®, polyvinyl chloride, amorphous carbon, ceramics, glass, titanium oxide, or the like.

The flocculation vessel 15a described has the water inlet 153 disposed at the top and the water outlet 154 disposed at the bottom, to conduct raw water from a top level of the flocculation vessel 15a to a bottom level of the flocculation vessel 15a, circumventing in horizontal or right-and-left directions, while such the mode of implementation is not restrictive subject to the provision of a water circumventing route. There may be an example of flocculation vessel implemented with a water inlet formed through a left (or right) lateral wall and a water outlet formed through a right (or left) lateral wall, to conduct raw water in between, circumventing in vertical or up-and-down directions.

The solid-liquid separator 17 is configured to make inlet raw water swirl in spin therein, having developed centrifugal forces acting on flocs, as accelerations greater than the gravity, thereby spinning down floes at enhanced settling rates, for separation of raw water into flocs and treated water. The solid-liquid separator 17 in use may be a liquid cyclone. The solid-liquid separator 17 is configured to accelerate inlet raw water to swirl at adequate flow velocities for enhanced flocculation, as well as for enhanced separation of floes from raw water swirling at high speeds.

Preferably, the water pump 16 should be adapted to send streams of raw water to the solid-liquid separator 17, with sufficient momenta for the solid-liquid separator 17 to have raw water swirl at adequate velocities for floc formation as well as for floc separation.

According to the first embodiment described, there is a solid-liquid separation system la including a flocculation vessel 15a affording to form floes with increased strength and increased density. The solid-liquid separation system la according to the first embodiment

permits employing a solid-liquid separator 17 adapted to make use of centrifugal forces and down-scaled relative to gravity settling equipment, allowing for a saved space for system installation.

In the solid-liquid separation system la according to the first embodiment, the solid-liquid separator 17 is adapted to make use of centrifugal forces combined with the gravity to spin down floes. Accordingly, the solid-liquid separation system la permits floes to be settled out within shorter periods than in systems simply using the gravity, thus allowing for an enhanced efficiency of separation.

(Second embodiment)

Referring now to Fig. 4, according to a second embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15b substituting for the flocculation vessel 15a. Fig. 4(a) is a section of the flocculation vessel 15b, and Fig. 4(b), a perspective view in part of the flocculation vessel 15b including stage plates 152b.

As illustrated in Fig. 4, the flocculation vessel 15b also accommodates therein an array of stage plates 152b cooperating with a vessel wall to define a water circumventing route, while being different in shape and arrangement of stage plates 152b from the flocculation vessel 15a described with reference to Fig. 2 and Fig. 3. In the flocculation vessel 15a illustrated in Fig. 2 and Fig. 3, at any stage, the stage plate 152 is fixed to join at an upstream end or edge thereof to one side wall 151, to be water-tight over width of that edge, and spaced at a downstream end or edge thereof from the opposite side wall 151 (for a necessary gap in between), to define a water-communicating area over width of this edge. Instead, in the flocculation vessel 15b shown in Fig. 4, at any stage there is a stage plate 152b fixed to join at either end or edge thereof to both side walls 151. In other words, the stage plate 152b is formed at an upstream end thereof with a plain edge for a water-tight joint, and has at a downstream end or edge thereof a cutout portion 152c partially cut out to provide an array of water-communicating slots. In the flocculation vessel 15b, such stage plates 152b are oriented to have their cutout portions 152c alternately joined to either side wall 151. In Fig. 4, the flocculation vessel 15b has a water inlet 153 at the top and a water outlet 154 at the bottom, to conduct raw water in between, along the water circumventing route that includes every stage a horizontal passage between paired stage plates 152b and a vertical flexed passage through a cutout portion 152c of a corresponding stage plate 152b.

In the flocculation vessel 15b, at any stage, raw water flows through a vertical flexed passages including slots of cutout portion 152c, where raw water has an unbalanced distribution of streams, getting turbulent, so at the next passage, given rotational momenta about flow direction, eddy currents develop, causing flocs to collide on surfaces of e.g. paired stage plates 152b by increased numbers of times, with grown densities of flocs. It is noted that alternate stage plates 152b have their cutout portions 152c close to either side wall 151, which preferably should have an array pitch 'c' substantially equal to a spacing 'b' between neighboring stage plates 152b times two or times a multiple number of two.

At any cutout portion 152c, the slot shape is not limited to a rectangular form as illustrated in Fig. 4(b), and may be formed in a triangular shape, or curved like a semi-circle or such.

The flocculation vessel 15b may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent floes from adhering on stage plates 152b or side walls 151 of flocculation vessel 15b, with enhanced effects of flocculation, like the flocculation vessel 15a.

According to the second embodiment described, there is a solid-liquid separation system including a flocculation vessel 15b adapted for flocs to have increased frequencies of collision on stage plates 152b, affording to form floes with increased strength and increased density, thus permitting employment of a solid-liquid separator making use of centrifugal forces, allowing for a saved space for system installation, and an enhanced efficiency of solid-liquid separation.

(Third embodiment)

Referring now to Fig. 5, according to a third embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15c substituting for the flocculation vessel 15a. Fig. 5(a) is a section of the flocculation vessel 15c, and Fig. 5(b), a perspective view in part of the flocculation vessel 15c including stage plates 152.

As illustrated in Fig. 5, the flocculation vessel 15c is different from the flocculation vessel 15a described with reference to Fig. 2 and Fig. 3, in that it has an array of stage plates 152 each provided with a set of baffle plates 155. More specifically, in the flocculation vessel 15c shown in Fig. 5, at any stage, the stage plate 152 is spaced from a side wall 151, at a downstream end or edge thereof, which has a set of aligned baffle plates 155 fixed thereto. Each baffle plate 155 is oriented to extend in a flow direction of raw water of an associated vertical flexed passage (where raw water vertically turns). Through the passage provided with baffle plates 155, flowing raw water has an unbalanced distribution of streams, getting turbulent, so at the next passage, raw water has swirling streams about flow direction of raw water. Those flocs failing to follow such swirling streams are caused to collide on surfaces of e.g. paired stage plates 152 by increased numbers of times, so they are toughened with internal voids tightened, getting stronger.

At any set of baffle plates 155, the plate shape is not limited to a triangular form as illustrated in Fig. 5(b), and may be formed in a rectangular shaped, or curved like a semi-circle or such.

Swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, so at any stage plate 152 provided with baffle plates 155 aligned along an edge thereof as illustrated in Fig. 5(b), preferably the baffle plates 155 should be arrayed by a center pitch 'd' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two.

The flocculation vessel 15c may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs from adhering on stage plates 152 or side walls 151 of flocculation vessel 15c, with enhanced effects of flocculation, like the flocculation vessel 15a.

According to the third embodiment described, there is a solid-liquid separation system including a flocculation vessel 15c adapted for floes to have increased frequencies of collision on stage plates 152, affording to form floes with increased strength and increased density, thus permitting employment of a solid-liquid separator making use of centrifugal forces, allowing for a saved space for system installation, and an enhanced efficiency of solid-liquid separation.

(Modification)

Fig. 6 illustrates an example of flocculation vessel 15d in a solid-liquid separation system according to a modification of the third embodiment. Fig. 6(a) is a section of the flocculation vessel 15d, and Fig. 6(b), a perspective view in part of the flocculation vessel 15d including stage plates 152.

In the flocculation vessel 15c shown in Fig. 5, at any stage, the stage plate 152 is spaced from a corresponding side wall 151, at a downstream end or edge thereof, which has a set of aligned baffle plates 155 fixed thereto, the baffle plate 155 being oriented to extend in a flow direction of raw water of an associated vertical flexed passage (where raw water vertically turns). In the flocculation vessel 15d shown in Fig. 6, at any stage, there is another set of aligned baffle plates 155 fixed at an upstream end or edge of one of paired stage plates 152 and oriented to extend in opposition to a set of aligned baffle plates 155 fixed like the third embodiment to a downstream end or edge of the other of the paired stage plates 152 spaced from a corresponding side wall 151.

Like the third embodiment, swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, so at each stage plate 152 provided with baffle plates 155 aligned along an edge thereof as illustrated in Fig. 6(b), preferably the baffle plates 155 should be arrayed by a center pitch 'd' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two.

According to this modification also, there is a solid-liquid separation system including a flocculation vessel 15d adapted for flocs to have increased frequencies of collision on stage plates 152, affording to form flocs with increased strength and increased density, thus allowing for an enhanced efficiency of solid-liquid separation.

(Fourth embodiment)

Referring now to Fig. 7, according to a fourth embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15e substituting for the fiocculation vessel 15a. Fig. 7(a) is a section of the fiocculation vessel 15e, and Fig. 7(b), a perspective view in part of the fiocculation vessel 15e including stage plates 152.

As illustrated in Fig. 7, the fiocculation vessel 15e is different from the fiocculation vessel 15a described with reference to Fig. 2 and Fig. 3, in that it has an array of stage plates 152 each provided with a set of lugs 156 configured as small pieces fixed thereto. Each stage plate 152 has on the upside a set of lugs 156 standing with their normals oriented in a flow direction of the passage to face coming-up streams of raw water, and arrayed in a matrix with rows or columns aligned in the flow direction. In the fiocculation vessel 15e, at any stage, the lugs 156 work to cause swirling streams of raw water about flow direction in the passage between paired stage plates 152, having flocs therein collide on surfaces of e.g. paired stage plates 152 by increased numbers of times.

Swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, and preferably, lugs 156 on each stage plate 152 should be passage-transversely arrayed by a geometrical-center or gravity-center pitch or pitches 'e' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two.

Further, those lugs 156 neighboring in the raw water flow direction should be passage-longitudinally arrayed by a geometrical-center or gravity-center pitch or pitches 'f substantially equal to a spacing 'a' between a stage plate end and a wall of the fiocculation vessel.

At any stage, the shape of any lug 156 is not limited to a cuboid or rectangular parallelepiped as illustrated in Fig. 7, and may well be formed triangular or cylindrical as shown in Fig. 8, for instance. Lug shapes shown in Fig. 8(a) and Fig. 8(b) are both effective to prevent floes or solids in raw water from stagnating about lugs 156.

The fiocculation vessel 15e may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs from adhering on stage plates 152 or side walls 151 of fiocculation vessel 15e, with enhanced effects of fiocculation, like the fiocculation vessel 15a.

According to this embodiment also, there is a solid-liquid separation system including
a flocculation vessel 15e adapted for flocs to have increased frequencies of collision on stage plates 152, affording to form flocs with increased strength and increased density, thus permitting employment of a solid-liquid separator making use of centrifugal forces, allowing for a saved space for system installation, and an enhanced efficiency of solid-liquid separation.

(Modification)

Fig. 9 illustrates an example of modification of the flocculation vessel 15e in the solid-liquid separation system according to the fourth embodiment In the flocculation vessel 15e shown in Fig. 7, lugs 156 arrayed on a stage plate 152 are oriented in a direction according to a raw water flow direction. In Fig. 9, lugs 156 set on a stage plate 152 are oriented to have their longitudinal directions offset from a raw water flow direction. These lugs 156 are each elongate in a direction inclined at an angle relative to the raw water flow direction, affording to prevent floes or solids in raw water from stagnating about lugs 156. Among the lugs 156, neighboring ones in passage-transversely rows are not all inclined at an angle, but inclined in a staggered manner as illustrated in Fig. 9, affording for increased tendencies to develop swirling streams of raw water.

Like the fourth embodiment, swirling streams develop eddies with sizes depending on a spacing between paired stage plates 152, and preferably, lugs 156 on each stage plate 152 should be passage-transversely arrayed by a geometrical-center or gravity-center pitch or pitches 'e' substantially equal to a spacing 'b' between neighboring stage plates 152 times two or times a multiple number of two.

According to this modification, even with lugs 156 having longitudinal directions inclined relative to a raw water flow direction, there is a solid-liquid separation system adapted for floes to have increased frequencies of collision on stage plates 152, affording to form floes with increased strength and increased density, thus allowing for an enhanced efficiency of solid-liquid separation.

(Fifth embodiment)

Referring now to Fig. 10, according to a fifth embodiment there is a solid-liquid
separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15f substituting for the flocculation vessel 15a

As illustrated in Fig. 10, the flocculation vessel 15f is configured with a first flocculator portion 157a and a second flocculator portion 157b. The first flocculator portion 157a and the second flocculator portion 157b accommodate therein their arrays of stage plates 152, while the stage plates 152 in the first flocculator portion 157a are arrayed by a pitch 'bl' different from a pitch 'b2' by which the stage plates 152 in the second flocculator portion 157b are arrayed.

Generally, the wider the pitch of stage plates 152, the more moderate the flow velocity of raw water, with flocs subjected decreased frequencies of collision on stage plates 152. On the hand, the narrower the pitch of stage plates 152, the faster the flow velocity of raw water, with flocs subjected increased frequencies of collision on stage plates 152. If the frequency of collision on stage plates 152 is increased before floes get hard, there come up anxieties about possible rupture of flocs due to the impact of collision on stage plates 152. To this point, the first flocculator portion 157a is configured to have floes therein moderately collide on stage plates 152, causing floes to gradually grow to get larger, before raw water flows into the second flocculator portion 157b configured to have floes collide on stage plates 152 by increased numbers of times, to toughen flocs.

In the example of Fig. 10, the flocculation vessel 15f is composed of two flocculator portions being the first flocculator portion 157a having stage plates 152 arrayed with a spacing 'bl' and the second flocculator portion 157b having stage plates 152 arrayed with a spacing 'b2' different from the spacing 'bl', while the spacing between stage plates is not limited to the two. Also the proportion of flocculator portions 157a and 157b different in stage plate spacing is not limited. For instance, there may be combination of a moderate flocculator portion responsible for a beginning quarter of flocculation, and a fast flocculator portion responsible for the remaining three quarters of flocculation. There may be a repeated flocculation implemented with a flocculator sequence including in order a moderate flocculator, a fast flocculator, a moderate flocculate, and a fast flocculator. There may also be a rate of flocculation gradually changed from a moderate to a fast.

The flocculation vessel 15f may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent flocs from adhering on stage plates 152 or side walls 151 of flocculation vessel 15f, with enhanced effects of flocculation, like the flocculation vessel 15a.

According to this modification, even in use of the flocculation vessel 15f, there is a solid-liquid separation system adapted for flocs to have increased frequencies of collision on stage plates 152, affording to form flocs with increased strength and increased density, thus allowing for an enhanced efficiency of solid-liquid separation. There is use of moderate water flows permitting floes to be grown large, combined with fast water flows permitting floes to be toughened, thus affording to form large and hard flocs easy to separate at a solid-liquid separator. This permits employment of a solid-liquid separator adapted for centrifugal separation, allowing for a saved space for system installation, and an enhanced efficiency of separation.

(Sixth embodiment)

Referring now to Fig. 11A and Fig. 11B, according to a sixth embodiment there is a solid-liquid separation system different from the solid-liquid separation system la according to the first embodiment described with reference to Fig. 1, in that it employs a flocculation vessel 15g substituting for the flocculation vessel 15a. Fig. 11A is a section of the flocculation vessel 15g, and Fig. 11B, a combination of sectional top views in part of the flocculation vessel 15g including stage plates 152b and 152c.

As illustrated in Fig. 11A and Fig. 11B, the flocculation vessel 15g has a cylindrical vessel wall accommodating an array of annular first stage plates 152c and circular second stage plates 152d alternately fit in the vessel wall. The first stage plates 152c each have an outer circumference with a diameter matching a diameter of an inner circumference of the wall of flocculation vessel 15g. The second stage plates 152d each have an outer circumference with a diameter smaller than the diameter of the inner circumference of the wall of flocculation vessel 15g. The first stage plates 152c and the second stage plates 152d are supported by pillars 157, and have their pillar insertion holes h1 and h2.

In the flocculation vessel 15g, the first stage plates 152c and the second stage plates 152d are alternately supported by the pillars 157. At the flocculation vessel 15g, inlet raw
water is guided to flow through a water passage defined by a central hole of a first stage plate 152c, and a water passage defined by and between an outer periphery as an outer end of a second stage plate 152d and a corresponding region of the wall flocculation vessel 15g. After that, raw water is likewise guided to alternately pass water passages provided through first stage plates 152c and passages provided outside second stage plates 152d.
At each first stage plate 152c, the passage provided through the central hole has a passage area SI, and at each second stage plate 152d, the passage provided outside the outer periphery has a passage area S2. As the passage area SI is set to be equal to the passage area S2, i.e. SI = S2, raw water has an equivalent flow in travel from any first stage plate 152c to the next second stage plate 152d, and in travel from any second stage plate 152d to the next first stage plate 152c. The stage plates 152c and 152d may be arrayed with a retained spacing, or may have varied spacing distances to change the flow velocity, as described in conjunction with the fifth embodiment.

According to this embodiment, even in use of the cylindrical flocculation vessel 15g, there is a solid-liquid separation system adapted to develop swirling streams of raw water, having floes collide on stage plates 152c and 152d, affording to form large and hard floes. Further, the cylindrical configuration permits withstanding pressures in a facilitated manner relative to using typical cuboid flocculation vessels, affording to reduce vessel wall thickness.

The flocculation vessel 15g may also be implemented with, among others, installation of an interior coating or selection of materials used therein, alone or in combination, to prevent floes from adhering on side walls 151, stage plates 152c or 152d, or pillars 157 of flocculation vessel 15g, with enhanced effects of flocculation, like the flocculation vessel 15a.

According to this embodiment, even in use of the cylindrical flocculation vessel 15g, there is a solid-liquid separation system adapted to have floes collide on stage plates 152c and 152d by increased numbers of times, affording to provide floes with increased strength and increased densities, permitting employment of a solid-liquid separator adapted for centrifugal separation, allowing for a saved space for system installation, and an enhanced efficiency of separation. Further, the employment of a cylindrical flocculation vessel 15g allows for a facilitated design of flocculation vessel 15g in view of working environment under pressure.

While certain embodiments have been described, these embodiments have been
presented by way of example only, and are not intended to limit the scope of inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms: furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

What is claimed is:

1. A solid-liquid separation system adapted to work, as raw water containing solids
inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising:

a flocculation vessel comprising:

an array of stage plates parallel-arranged therein; and

a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with flocs formed therein, the water circumventing route comprising:

a passage defined by and between paired stage plates; and

a passage defined by and between a wall of the flocculation vessel and a stage plate end spaced therefrom at distances smaller than a spacing between the paired stage plates; and

a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces.

2. A solid-liquid separation system adapted to work, as raw water containing solids
inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising:

a flocculation vessel comprising:

an array of stage plates parallel-arranged therein; and

a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with floes formed therein, the water circumventing route comprising:

a passage defined by and between paired stage plates; and a passage defined by and between a wall of the flocculation vessel and a stage plate end cut out in part; and

a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate floes as solids from raw water, making use of centrifugal forces.

3. The solid-liquid separation system according to claim 2, wherein the stage plate end constitutes part of one of the paired stage plates, and has an array of cutouts formed by a pitch or pitches substantially equal to a spacing between the paired stage plates times two or times a multiple number of two.

4. A solid-liquid separation system adapted to work, as raw water containing solids inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising:
a flocculation vessel comprising:

an array of stage plates parallel-arranged therein; and

a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with floes formed therein, the water circumventing route comprising:

a passage defined by and between paired stage plates provided at a plate end thereof with a buffle plate set arranged to have a normal at a baffling side of any buffle plate therein in a raw water flow direction of the passage; and

a passage defined by and between a wall of the flocculation vessel and a stage plate end; and

a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces.

5. The solid-liquid separation system according to claim 4, wherein the plate end provided with the buffle plate set constitutes part of one of the paired stage plates, and the other of the paired stage plates has another buffle plate set arranged at an end portion thereof opposing the plate end in the raw water flow direction and extending in parallel with the plate end.

6. The solid-liquid separation system according to claim 4 or 5, wherein the plate end provided with the buffle plate set constitutes part of one of the paired stage plates, and the buffle plate set comprises a set of buffle plates arrayed at an interval or intervals substantially equal to a spacing between the paired stage plates times two or times a multiple number of two.

7. A solid-liquid separation system adapted to work, as raw water containing solids
inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising:
a flocculation vessel comprising:

an array of stage plates parallel-arranged therein; and

a water circumventing route configured to work, as raw water is inlet, to circumvent raw water therethrough, and outlet raw water with floes formed therein, the water circumventing route comprising:

a passage defined by and between paired stage plates provided with a lug set configured to obstruct streams of raw water; and

a passage defined by and between a wall of the flocculation vessel and a stage plate end; and

a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate floes as solids from raw water, making use of centrifugal forces.

8. The solid-liquid separation system according to claim 7, wherein the lug set is provided on one of the paired stage plates, and comprises a set of lugs arrayed at an interval or intervals substantially equal to a spacing between the paired stage plates times two or times a multiple number of two.

9. The solid-liquid separation system according to claim 7, wherein the lug set is provided on the paired stage plates, and comprises a set of lugs each elongate in a direction inclined relative to a raw water flow direction of the passage between the paired stage plates.

10. The solid-liquid separation system according to claim 9, wherein the set of lugs comprises subsets thereof each composed of neighboring lugs elongate in directions inclined relative to the raw water flow direction at angles meeting a prescribed relationship.

11. The solid-liquid separation system according to claim 10, wherein the subsets of
the set of lugs each comprise a group of neighboring lugs arrayed along the raw water flow direction by a gravity center pitch substantially equal to a spacing between the wall of the flocculation vessel and the stage plate end.

12. A solid-liquid separation system adapted to work, as raw water containing solids
inflows, to inject into raw water a chemical for flocculation of solids to separate raw water into solids and treated water, the solid-liquid separation system comprising:

a flocculation vessel comprising: a cylindrical vessel wall;

an array of annular first stage plates and circular second stage plates alternately fit in the vessel wall, the first stage plates each having an outer circumference thereof matching an inner circumference of the vessel wall, the second stage plates each having an outer circumference thereof smaller than the inner circumference of the vessel wall; and

a water circumventing route configured to work, as raw water is inlet, to circumvent raw water through a sequence of passages therein, and outlet raw water with floes formed therein, the sequence of passages alternately including:

a passage defined by a central hole of a corresponding one of the first stage plates; and

a passage defined by and between an outer end of a corresponding one of the second stage plates and a corresponding region of the vessel wall; and

a solid-liquid separator configured to work, as raw water outlet from the flocculation vessel is inlet, to separate flocs as solids from raw water, making use of centrifugal forces.

13. The solid-liquid separation system according to claim 1,2,3,4,5,6,7,8,9,10,11,
or 12, wherein the array of stage plates has stage plates therein arrayed by pitches including a pitch for stage plates defining anterior passages of the water circumventing route near to an inlet of the flocculation vessel, set larger than a pitch for stage plates defining posterior passages of the water circumventing route.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=6e0CDOdrgILhYOoZVVbcAA==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

278288

Indian Patent Application Number

3017/CHE/2010

PG Journal Number

53/2016

Publication Date

23-Dec-2016

Grant Date

20-Dec-2016

Date of Filing

12-Oct-2010

Name of Patentee

KABUSHIKI KAISHA TOSHIBA

Applicant Address

1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001

Inventors:

#	Inventor's Name	Inventor's Address
1	FUKUDA, MII	C/O INTELLECTUAL PROPERTY DIVISION, TOSHIBA CORPORATION, 1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001
2	MENJU, TAKASHI	C/O INTELLECTUAL PROPERTY DIVISION, TOSHIBA CORPORATION, 1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001
3	YAMAMOTO, YASUSHI	C/O INTELLECTUAL PROPERTY DIVISION, TOSHIBA CORPORATION, 1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001
4	HAYAMI, TOKUSUKE	C/O INTELLECTUAL PROPERTY DIVISION, TOSHIBA CORPORATION, 1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001
5	UCHIMURA, TAIZO	C/O INTELLECTUAL PROPERTY DIVISION, TOSHIBA CORPORATION, 1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001

PCT International Classification Number

C02F1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2009-238689	2009-10-15	Japan