WO2014097317A2

WO2014097317A2 - Integrated multiple-stage auto-self-cleaning filter

Info

Publication number: WO2014097317A2
Application number: PCT/IN2013/000777
Authority: WO
Inventors: Srinivasan Ramachandran Puddukarai
Original assignee: Srinivasan Ramachandran Puddukarai
Priority date: 2012-12-20
Filing date: 2013-12-18
Publication date: 2014-06-26
Also published as: EP2948232A4; EP2948232A2; WO2014097317A3

Abstract

A bolted integrated equipment with low footprint comprising of first stage and second stage filtration with automatic self cleaning and efficient backwash, with continuous output and zero downtime, the first stage apparatus comprising of a bottom chamber with an inlet pipe; a conical screen, a rotatable movable arm for slurry discharge and a constantly open drain nozzle; the second stage apparatus comprising a body with multiple filtration modules located in diametrically opposing manner containing filtration elements and a top chamber for filtrate collection comprising an outlet and a rotatable T shaped pipe arm sealing two diametrically opposing filtration modules during backwash; wherein the said T shaped pipe arm being connected to the movable arm by means of a shaft; wherein the filtrate of the first stage is the input for the second stage and the filtrate of one module acts as the Backwash fluid for the other module undergoing backwash.

Description

INTEGRATED MULTIPLE-STAGE AUTO-SELF-CLEANING FILTER

FIELD OF INVENTION

[0001] The invention relates to an integrated multi-stage auto-self cleaning filter assembly to separate solid particles from ballast or sea water, or other low-viscosity liquid. The invention aims at providing a continuous output with zero downtime, wherein the filtrate of the first stage automatically becomes the input for the second stage filtration.

BACKGROUND OF THE INVENTION

[0002] Separating suspended solids and organic matter from large quantities of low viscosity fluids like sea water or fluids used in cooling towers, with a filter which occupies small footprint of space, permitting easy and quick installation in tightly enclosed spaces and which requires no manual labour for maintenance and cleaning operations, has always been a challenge. Several prior art systems currently available meet these needs in varying degrees, however not all criteria are met along with supreme filtration efficiency. The present invention meets on all these needs, with automatic self-cleaning of both stages, bolted construction and total volume of space occupied being a fraction of the space occupied by prior art devices serving the same purposes, for equivalent flow rate and filtrate quality.

[0003] Most prior art systems provide all the features of the present invention in multiple stages which are housed separately, and are connected by channels to convey filtered/ treated fluid to the next stage. Most prior art filters have at least one of the multiple stages constructed in a manner that it requires periodic manual clean-up to evacuate the trapped solids from at least one of the stages.

[0004] Most prior art filters having backwash facility have relatively poor efficacy of the backwash. The second stage of the present device is designed in a manner that it has far superior backwash efficiency and backwash fluid velocity being higher than the normal working velocity due to its unique construction, wherein the filtrate is used as the liquid for backwash and the same is drained out. At no point of time does the system stop producing the filtrate as at given point of time only two filter elements are shut off, when the backwash procedure is being carried out. Prior art filters with similar functionality do not feature a dedicated backwash fluid channel to clean each module, and in several prior art filters, the backwash fluid pressure is not high enough to be as efficacious as the backwash arrangement in the current device because the chamber/ channel through which the backwash fluid. flows also has other opening(s) that are open while the backwash is in progress.

[0005] Generally prior art filters comprise of the filter element which either use a flat element or bend and curve flat panels into cylindrical element(s) with large diameters (usually upwards of 300mm). Flat sheets of the wire mesh are placed above flat sheets of the triangular wire profiles. These are then sintered and fused to each other at multiple points to eliminate mesh migration or distortion during filtration or backwash. This sintered flat sheet is either used as in a plate filter, or is bent and welded together longitudinally, to form a cylindrical filtration element. However manufacturing using the described method is not suitable to manufacture cylinders of less that 300 mm in diameter. If it is attempted, the chances are high that the bond formed between the woven wire mesh and the triangular wires sheet by sintering would be sheared.

[0006] Some prior art claims show the multi-layered sintered woven wire mesh welded to the wedge-shaped side of the wedge wire support plate or cylinder, which means that very small proportion of the area of the sintered mesh is in contact with the wedge wire screen. This increases the chances of the mesh disengaging from the cylindrical support candle. Some other prior art filters have the sintered wire mesh attached to the flat side (inside) of the triangular wire screen, but support rods of the cylindrical element made out of triangular wire profiles prevent complete bonding of the sintered wire mesh with the triangular wire screen.

[0007] The filter in the present invention relates to the filtrate moving from out to in and the velocity of the filtrate is constant even during backwash time. This novel feature of the filtrate velocity being almost constant even during backwash, is due to the fact that >a pair of filter modules diagonally opposite to each other are sealed on the top and the filter module undergoing backwash is sealed at the bottom also, thus forcing the input liquid into the remaining filter elements at a higher pressure, which results in a better flow of the filtrate.

[0008] , Accordingly, the objects of this invention include provision of:

a) A filtration assembly which houses all stages of filtration in a single, integrated housing, doing away with the need for providing for channels for fluid to flow from one unit to the next, thus saving space with regard to the systems used in multiple locations for multiple levels of filtration. The flow of fluid between the first and second stage of filtration is in such tight integration that the outlet of the first stage is the inlet of the second stage without any means of conveying.

b) The Filtration assembly features a tangential inflow for the first stage, which is configured to fall on a conical screen which is placed at an incline which works on the principle of Hydrocylone due to its angle of incline, which ensures that the solids which are accumulated on the screen are continuously evacuated due to the Coanda Effect from the first stage through an open drain nozzle at the bottom thereby eliminating the need for manual evacuation of solids in the first stage of filtration. c) The filtration assembly discloses the specific use of surface filter with Out to In Flow mechanism by the placement of the wire mesh layers on the outer side of the filter element. The filter element consists of the inner core screen made of triangular wire with support rods; completely draped by a multi-layered sintered mesh as the outer layer, when the outer layer is welded permanently at regular intervals to the inner core screen, which is configured to bear much stress and strain due to minimal displacement of the wire mesh layers.

d) The filter assembly features a movable T Shaped arm that caps the top of two independent filtration modules positioned diametrically opposite each other and where with the filtrate of the one module backwashes the other. The increased efficiency of the back wash is due to combination of three factors - differential pressure between the module undergoing back wash and outside atmosphere; increased flow velocity during back wash and venturi effect of the wedge shaped surfaces on the inside of the cylindrical filter.

PRIOR ART

[0009] EP 1470080 Al titled "Apparatus and method for separating and filtering particles and organisms from flowing liquids" provides for a device for separating and filtering particles and organisms from a high volume flowing liquid operating under low pressure. The device includes a conical or cylindrical shape inlet chamber were liquids enter tangentially creating a circular flow without creating a vortex, the liquids accelerate into a separation and filter chamber where the liquids spin around a longitudinally disposed filter element in the centre of the chamber , with the centrifugal forces separating out larger and heavier particles towards the perimeter of the separation and filter chamber, and where smaller particles having a specific gravity closer to that of the liquid are filtered when the liquid penetrates through the filter element wall into the centre of the filter element and flows out one of the longitudinal outlets of the unit. Ultraviolet light irreparably damages bacteria, microorganisms and pathogens contained in processed ballast water and may be incorporated as part of the system. ' ,

[0010] US 8146662 B2 titled "Well screen assembly with multi-gage wire wrapped layer" provides for a well screen assembly includes an elongate base pipe and a wire wrap layer. The wire wrap layer includes a wire wrapped around support ribs. The wire wrap layer has an axial end section wrapped at a first gage and an intermediate section wrapped at a second, larger gage. A mesh layer is provided around the wire wrap layer. An outer shroiid is provided around the mesh layer, the outer shroud sealed to the wire wrap layer.

[00111 US 4059518 A titled "Filter with axially shiftable rotating backwash selector"

provides Tor a filter assembly including a housing with a plurality of individual filter units circumferentially arranged within the housing. The housing is compartmented to channel a contaminated fluid to be filtered in a filtering direction through the filter units, from one end thereof to the other. A rotatable, conduit-like backwash arm is disposed in at least one end of the housing for sealed engagement with the contaminated fluid inlet, end of a filter unit and for receiving a backwashing fluid flow therefrom. A rotatable discharge pipe connects to the outlet end of the arm and extends from the housing through a rotaiy-axial bearing and seal unit thereon, and is coaxially arranged with respect to the circumferential array of filter units. A rotation indexing unit adjacent the housing engages the discharge pipe for angularly shifting said backwash arm from filter unit to filter unit and thereby for backwashing of said filter units in a desired sequence. An axial shift unit engages the discharge pipe for axially shifting the backwash arm away from the filter units preparatory to each angular shift, and for axially shifting the backwash arm into sealed engagement with a new filter unit following such an angular shift. A control coordinates actuation of the rotational indexing unit and axial shift unit for sequentially backwashing filter units of the array. In a modification, a rotatable backwash arm is provided at each end of the array of filter units, movement of the arms being synchronized and the arms being axially opposed for sequentially backwashing the filter unit with a backwashing fluid other than the filtered fluid. In a further modification, the axial shift unit comprises a camming device directly responsive to rotation of the discharge pipe for carrying out the axial shifting of the backwash arm. SUMMARY OF THE INVENTION

[0012] The present invention aims at providing a single filter equipment with a small footprint, bolted down, which provides for two stage filtration with automatic self- cleaning and zero downtime. The invention aims at providing a continuous output with zero downtime. The unique design provides for efficient back washing, using a rotating arm which locks two diametrically opposite filter elements simultaneously in such a manner that the filtrate of one candle is utilised as the backwash liquid of the other candle and the backwashed liquid is flushed out from the bottom of the filter element by means of a drain which rotates in tandem with the arm and is connected to the arm by means of a shaft. The said drain is engaged to the module to which the backwash is to be done and moves from one module to another. When the said drain is engaged to on the module, the upward velocity is increased in all open filtration modules include the module that is dedicated to supply backwash filtrate. The increased velocity contributes to the efficient back wash. During backwash the common chamber stops receiving filtered fluids from the pair of modules that are capped with the T shaped arm, but the remaining modules continue to discharge filtered fluid into the common chamber thereby providing a continuous output with zero downtime.

[0013] The seamless integration without any wall or housing separating the first stage filter from the second stage filter forms an integrated two stage filtration system within a compact single housing with a low foot-print thus making it cost effective. The filtrate of stage 1 which contains suspended solids between 200 to 400 μ is used as the input for stage 2, thus reaching a filtration of solid not more than 30 μ level in a single unit. The constant drain being open in the stage 1 filter results in the solids being drained out simultaneously from the stage 1 filter, without any manual interference to clean the same, resulting in zero downtime for stage 1 filtration,

[0014] The body comprises of even numbered plurality of filtration modules wherein each filtration module comprises a plurality of surface filtration filter elements. The novelty lies in the arrangement of a movable T shaped arm that caps the top of two independent filtration modules positioned diagonally opposite each other.^'

[0015] The movable T shaped pipearm is connected to the movable pipe arm via a shaft such that the pipe arm becomes the discharge route for the slurry from each of the plurality of the module during back wash cycle. Novelty lies in the auto cleaning first stage filter integrated with the second stage filter in a single housing with continuous fluid flow contact between first and second stage, with no manual interference to clean the filter elements in either stage, wherein the direction of the filtrate is always out to in.

[0016] Furthermore, the back wash cleaning is triggered by the differential pressure between the inlet and outlet port of the second stage and the self-cleaning is done within 15 to 20seconds/cycle, each cycle comprising of all the filter elements. The backwash process is completed with zero downtime and the filter is designed for continuous output. It is further the object of the present invention to utilize the filtrate of one independent filtration module to backwash the diagonally opposite filtration module. This leads to greater velocity of fluid flow resulting in greater back wash efficiency and at the same time retaining a constant output of the filtrate from the 2^nd Stage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 provides for the front view of the preferred embodiment

[0018] Figure 2 provides for the Front view of the bottom chamber

[0019] Figure 3 provides for the Cross Sectional Top View of the Bottom Chamber

[0020] Figure 4 provides front view of the bottom chamber along with the conical screen placed at an incline

[0021 ] Figure 5 provides for the Front view of the Moving Arm (back wash slurry discharge arm)

[0022] Figure 6 provides for the Cross sectional top view of the backwash slurry discharge arm

[0023] Figure 7 provides for the front view of the intersection between the Bottom Chamber and Main Body

[0024] Figure 8 provides for the top cross sectional view of the intersection between the

Bottom Chamber and Main body

[0025] Figure 9 provides for the front view of a single Filtration Module

[0026] Figure 10 provides for the Cross sectional top view of the Single Filiation Module [0027] Figure 11 illustrates the front view of the top chamber

[0028] Figure 12 provides for the cross sectional top view of the top chamber

[0029] Figure 13 provides for the Front view of the T Shaped Arm (back wash cleaning arm) [0030] Figure 14 illustrates the Front view of the gland assembly

[0031 ] Figure 15 illustrates the front and cross sectional top view of the Collor used for the sealing system between the T shaped pipearm and the filtration module

[0032] Figure 16 illustrates the front and cross sectional top view of the plate used for the sealing system between the T shaped pipe arm and the filtration module

[0033] Figure 17 explicates the isometric view of the conical screen.

[0034] Figure 18 explicates the isometric view of the cylindrical screen

[0035] Figure 19 provides for the schematic figure illustrating the filtration cycle during normal operation of the filter giving the position of the top T shaped pipe arm.

[0036] Figure 20 provides for the schematic figure illustrating the backwash process elucidating the position of the T shaped pipe arm along with the bottom slurry drain arm.

DETAILED DESCRIPTION

[0037] The integrated two-stage auto self-cleaning filtration device of the present invention is in a single housing wherein the inlet is sea water or any other low- viscosity, free flowing fluid containing organic and inorganic solids of varying, uncontrolled size ranges upto ό,ΟΟΟμπι; and the output is the fluid containing solids no more than 30μηι in the preferred embodiment of the present invention, though certain embodiments of the present disclosed invention could provide output fluid containing solids of no more than ΙΟμηι in size.

Construction Features

[0038] Referring to Fig 1, the device is intended to be built almost entirely using stainless steel or rust and corrosion-resistant material. The entire device is of bolted

3

construction, and if designed for a flow output of no less than 125 m per hour, the height of the entire device would not exceed 1.5 metres, which makes it suitable for installation in small spaces like the conditions found in ocean-going ships. The footprint of the preferred embodiment of the entire device is no more than a few square feet, varying with flow output. The device can be manufactured in any size, and can be designed with finer (as low as ΙΟμπι) or coarser filtration tolerances than 30μπι. [0039] The device has a bottom chamber (21), a body (22) and a top chamber (23). The body is separated from the bottom chamber by a conical screen (3) bolted circumferentially to the top inside surface of the housing of the bottom chamber as well as to the floor of the bottom chamber.

The Bottom Chamber

[0040] Referring to Fig 2 and Fig 3, the bottom chamber (21) is substantially cylindrical in shape from the outside, and conical in shape from the inside (described in detail in next paragraph). The bottom chamber comprises of an inlet opening (1), a drain nozzle (2) of appropriate circumference in the floor of the bottom chamber that always remains open and a slurry drain (19) of appropriate diameter suitable to seal to the backwash slurry discharge arm.^'

[0041] Referring to Fig 4, the inside of the bottom chamber (21), there is a substantially conical screen (3) placed at a sharp incline to the vertical; and bolted to the top inside surface of the bottom chamber circumferentially. This screen serves four purposes: it acts as the barrier that separates the first-stage filtration from the second; it also acts as the floor of the second stage; as the inner housing of the first stage; and as a filter element.

[0042] Referring to Fig 5 and Fig 6, the bottom chamber also contains a movable pipe arm

(17). During the backwash process the movable pipe arm (17) caps and completely stops the ingress of filtered fluid from the first stage into any one of the plurality of filtration modules (7) in the second stage filter of the device, from the bottom. The movable pipe arm (17) then becomes the discharge route for the slurry that is dislodged from each one of the plurality of cylindrical screens within that module during the backwash cycle.

[0043] Referring to Fig 7 and Fig 8, is the front view and the top cross sectional view of the intersection between the bottom chamber and the body. The annular seal member has a substantial circular shaped cross section confirming to the cross section of the open end of the bottom chamber (24) and is fixed securely by any convenient means such as push bearings. This is also the intersection between the body and the movable arm during backwash. The Body

[0044] The body (22) commences from the other side of the conical screen (3) featured in the bottom chamber. The body comprises of an even numbered plurality of filtration modules (6)(i.e., alternative embodiments of the device may have 4, 6, 8 filtration modules) such that pairs of filtration modules are placed diametrically opposite to each other. Referring to Fig 9 and Fig 10, each filtration module comprises a plurality of surface filtration filter elements (7), and is substantially cylindrical in shape. Each module (6) is open at the bottom during filtration. All the filtration filter elements (7) in all the filtration module pairs are permanently closed at the bottom, and are permanently open at the top. The filter element is welded on to a flange at the top and supported by a cap affixed to a plate at the bottom. The cap at the bottom ensures a upward flow of the fluid during filtration in the 2^nd Stage. The body is integrated to the bottom chamber such that the filtrate output of the bottom chamber acts as the input of the body.

The Top Chamber

[0045] Referring to Fig 11 and Fig 12, the top chamber (23) acts as the receiver of all the filtrate that emerges from the top and interior of all the filter elements. The Top Chamber (23) comprises of a filtrate chamber (1 1) which collect all the filtrate after 2^nd stage filtration. The top chamber also comprises of a circumferentially placed outlet (12) that remains permanently opened for the filtrate to be removed.

[0046] Referring to Fig 13, the top chamber also contains a T-shaped pipe arm (10) at the top, powered by a motor and gearbox (13) affixed to the top chamber by means of a stuffing box (14). During backwash the T- Shaped Arm (10) caps each pair of independent filtration modules (6) which are placed diametrically opposite to each other. The T-shaped pipe arm of the top chamber is connected to the moving arm present in the bottom chamber via a shaft (15). The T shaped pipe arm caps the diametrically opposing pair of filtration modules at the top and seals the same from any further filtrate entering the filtration module. Simultaneously, the moving arm connects one of the pair of the filtration modules which is to be backwashed, by means of unique and effective sealing system. [0047] Referring to Fig 14 , the moving arm(17) connects to the slurry drain (19) through the gland assembly (20) such that the opening of the gland assembly is slightly smaller than the slot opening at the bottom.

[0048] Referring to Fig 15 and Fig 16, the necessary sealing between the module and the moving arm is provided by a collar and a plate (25). The collar sits on the sealing plate and the gap between collar and the plate is less than the size of the suspended solid in the filtrate. The plate comprises of two rings which helps in the sealing of the T shaped pipe arm to the filtration module. The sealing is slightly less than the slot opening at the bottom.

Constructional Features of the Filter Elements

Conical Screen of the first stage filtration

[0049] Referring to Fig 18, the conical screen (7) is comprised of substantially vertically placed triangular profile wires with the flat surface facing the inner side of the outer housing of the bottom chamber of the present disclosed invention, and the wedge- shaped two faces facing the inside of the body of the device. The substantially vertical orientation of the regularly spaced triangular wires, with the flat face of the wires tilted with a view to slightly blocking and changing the direction of flow of fluid that flows onto it, ensures that fluid is forced into the second stage. The sharp tilt to the vertical ensures that any solids remaining after the cyclone separation gets trapped and, in spite of being less dense than the fluid, eventually drop to the floor of the bottom chamber, to be evacuated eventually through the drain nozzle. Thus, this filter Using a conical screen can be called as genuinely self-cleaning, requiring no manual intervention at any stage to evacuate solids trapped.

[0050] Besides being a filter element, the conical screen serves three other functional purposes: It acts as the barrier that separates the 1^st stage filtration from the 2^nd stage; also acts as the inner housing of the first stage and integrates the 1^st stage and the 2^nd Stage by acting as the floor of the second stage.

The Cylindrical filtration filter elements of the Second Stage Filtration

[0051] Referring to Fig 19, the cylindrical filter elements are made of sintered woven wire mesh wrapped around, and structurally^" supported by a cylinder made of stainless steel triangular wire profiles, with the wedge-shaped portion inside and the smooth, flat surface outside and in contact with the woven wire mesh; [0052] Each cylindrical filter element consists of:

• the core, or innermost, layer being constituted of a cylindrical screen comprised of triangular wire profiles, with the flat surface facing outside and the wedge shape facing inwards.

• the gap between adjacent edges of the outward-facing sides of consecutive spirals of the triangular wire, is maintained at levels that are appropriate to give sufficient structural support to the multi-layered sintered woven wire mesh screen while still reaping the advantage of superior backwash (explained in next paragraph).

[0053] The two faces of the spirally wound triangular wire form a slit which widens radially inwardly between adjacent, substantially parallel triangular wire portions; with the inward apex of said triangular wire being welded to the projecting portion of support rods at crossing points. These rods act as structural support and ensure that the accurate standard distance between adjacent spirals of the triangular wire profiles is maintained strictly at all times. The design (widening radially inwardly) gives an effect analogous to pinching the nozzle of a pipe, imparting higher pressure and velocity of the fluid as it exits the cylinder during a backwash.

[0054] The cylindrical core is tightly covered on the outside by a sleeve of multi-layered sintered woven wire mesh. The wire mesh screen is not structurally strong, as it is made of very fine woven wire that is prone to both, medium migration and distortion. This mesh would be welded in place both, longitudinally and circumferentially, to the cylindrical welded wedge wire mesh screen, to provide excellent, even structural support and strength to the sintered mesh screen both, during filtration and backwash.

[0055] The outer layer of the cylindrical filter screen referred to in the preceding paragraph comprises a plurality of layers of plain woven square wire mesh of varying fineness, sintered (ie, thermally bonded) together. The multi-layer mesh screen provides high permeability, minimal resistance and very high flow rate. Sintering ensures that the meshes in different layers' bond at every contact point; and hence reduces chances of migration of the medium. This helps to consistently maintain the micron rating of the each mesh layer, and hence makes for higher reliability of the filtration process.

[0056] In an alternative embodiment of the present disclosed invention, a protective mesh layer at the top is added, which gives the mesh slightly more structural strength. The multi-layered mesh also ensures that fibrous solids that would tend to choke a filter element made out of triangular wire alone would be filtered out. [0057] The advantage that a plurality of smaller diameter filter elements offers is much higher available surface area for filtration in the same volume of space occupied, as compared with one single, large diameter filter element. This is of great commercial value when the present disclosed invention is used as a component of a ballast water filtration system fitted on ocean-going ships, where on-board space is at a premium.

[0058] When the triangular wire profile is manufactured by the above described method, it forms a perfect cylindrical candle, with the triangular wire rolled spirally, and with support rods welded at all contact points on the inside. This makes the candle perfectly suited to not only support the woven mesh sleeve with a smooth outer surface, but also makes it perfectly suited for the Out-to-In fluid flow design.

Working of the Present Invention

[0059] This invention works in two stages, the filtrate of the first stage is the input for the filtrate that comes out in the second stage.

1^st Stage Filtration

[0060] Referring to Fig 1 and Fig 20, the liquid sought to be filtered enters tangentially from a inlet pipe (1) located near the top of the bottom chamber. The tangential entry of the pumped fluid ensures that the fluid flows rapidly in circular motion, creating a vortex. The rapid flow of the fluid causes the denser solids to slow down and fall lower in the vortex until they drop to the floor of the bottom chamber.

[0061] The floor of the bottom chamber (4) has a drain nozzle (2) of appropriate circumference at the bottom of the bottom chamber that remains open always. The solids that precipitate and fall to the bottom are pushed along around the floor of the chamber by some of the fluid that reaches the floor, till they slip out of the drain nozzle (2) along with some fluid. Thus, build-up of solids in the bottom chamber is contained, and auto-cleaning effect is achieved.

[0062] Lighter solids batter around in the vortex created by the spinning fluid, till they encounter the conical screen that forms the inner housing of the bottom chamber.

The conical screen, placed at a sharp incline to the vertical and bolted to the top inside surface of the bottom chamber circumferentially, serves two purposes: it acts as the barrier that separates the first-stage filtration from the second; and as the inner housing of the first stage. The conical screen (3) is comprised of triangular wires, with one of the flat faces substantially facing the inside of the bottom chamber, albeit with a slight incline such that when viewed in profile, adjacent triangular rods would appear to present a saw-tooth appearance. This arrangement forces the fluid that touches its surface, outwards and into the second stage (called the Coanda effect). When this happens, the gap in the triangular wires comprising the conical screen (3) stop the lighter solids from exiting the first stage. These solids are pushed circumferentially and slightly downwards by the fluid spinning in a vortex. Thus the solids notwithstanding the lower density, are pushed to exit through the drain nozzle (2).

[0063] The two other faces of the vertical triangular wire portions form a slit which widens radially inwardly between adjacent triangular wire portions; with the inward apex of said triangular wire being welded to the projecting portion of support rods at crossing points. These rods, that end up in a circular formation, act as structural support to the vertically placed triangular wire portions, and ensure that the accurate standard distance between successive vertical triangular rods is maintained strictly at all times. The filtrate of the 1^st stage filtration enters the body of the 2^nd stage filtration chamber (5).

2^nd Stage Filtration

[0064] Referring to Fig 1 and Fig 20, a plurality of pairs of independent filtration modules (6), each module being substantially cylindrical in shape, comprise the second stage of filtration where solids of particle size mostly between 300μιη and 30μπι in size (or as fine as ΙΟμπι in certain embodiments of the present disclosed invention) are filtered out. Modules diametrically facing each other form a pair for the purposes of management of backwash. Multiple module pairs are arranged such that they appear substantially annular in arrangement.

[0065] Each filtration module (6) is open at the bottom at all times except when it is undergoing backwash. This enables the filtrate emerging from the first stage to move upwards and onto the sides of multiple filter elements (7). The flow direction of the fluid in the second stage is Out-to-In during filtration and In-to-Out during backwash.

[0066] Each filter element (7) is permanently closed at the bottom, and permanently open at the top, being welded on to a flange at the top that only permits filtrate pushing upwards from the inside of each candle, to reach the top chamber that is shared by all filter elements and modules. The filtrate then exits the top chamber from a cylindrical outlet that is permanently open, placed circumferentially near the top of the top chamber.

[0067] Normally once ΔΡ is reached, the system needs to shut down to be cleaned. The present invention does away with this downtime in such a manner that once ΔΡ is reached, a diametrically opposite pair of filtration modules are shut down by means of capping of the top portion of the pair of module and sealing the filtration module that is being backwashed at the bottom (24) by means of the moving arm, for automatic backwashing, in which case, the fluid coming in from the bottom chamber (5) of the device cannot enter that particular filtration module (6) from the bottom during backwashing. The filtrate that emerges from the other filtration module in that pair acts as the backwashing liquid. Thus yet another feature of this invention is that once Δ P is reached, the system does not shut down for cleaning but only a pair of the filtration modules is shut off at the top by means of a rotatable T shaped pipe arm (10) and a moving arm (17) connected to the filtration module (6) undergoing backwash at the bottom, which acts as a drain nozzle (19) and the remaining modules continue to process the filtrate with better output. The flow velocity of the filtrate increases as the entire volume of fluid available to be filtered is same but the number of filtration modules are less, it is ensure that the remaining filtration modules filter the fluid at an enhanced rate. Furthermore, the filtered output is even though gets reduced for few seconds due to the fact the filtrate from one of the module is used as a backwashing liquid for the filtration module undergoing backwash. The design of the filter element also contributes to the velocity of the backwash fluid as the pointed wedge surfaces act in accordance to the Venturi Effect. The slurry is drained through the drain nozzle of the moving arm and each filtration module is backwashed in a few seconds and the T shaped pipe arm moves onto the next filtration module at a pre-determined angle and rate. The T shaped pipe arm is placed , in between two adjacent modules when not in use. Self cleaning and zero downtime is achieved in this manner in the 2^nd stage also.

[0068] The filtrate from the bottom chamber i.e. 1^st stage filtration is pushed inwards and upwards into the plurality of filtration modules (6) that are open at any given time hits the outside surface of the plurality of cylindrical filter elements (7). This results in further filtration of particles of size lower than 30μ. Over a period, these particles will form a cake on the outside surface of each element. The filtered fluid that passes through the cylindrical screens (7) within all the filtration modules emerges out of the device from the to of each filtration module into a common filtrate chamber (1 1) . for all modules. The Out-to-In fluid flow design of the second stage has the commercial advantage of making it cheaper to manufacture the filter elements, which is also an embodiment of this invention. Furthermore, it is possible to manufacture filter elements which are very small in diameter through this design as under normal manufacturing process, the sintered sheets are generally welded to the triangular wedge wire and then bent. In the present invention, the triangular welded wedge wire is first manufactured in a cylindrical form & then "the sintered wire mesh is wrapped on the cylindrical element tightly & welded in the longitudinal & circumferential direction to give a compete sealing. This manner of manufacture enables the wire mesh to withstand migration and manufacturing of small diameter filter elements which are not only cost effective but also space effective in usage and directly result in low foot print size. .

Automatic backwashing

[0069] The unfiltered particles deposited on the filter element are back washed with filtrate water based on the ΔΡ principle. The backwash cleaning is triggered by the differential pressure between the inlet and outlet port of the second stage and the backwash cleaning is done between diametrically opposing pairs of filtration modules within 3 to 4 seconds/module. The backwash process is completed with zero downtime and the filter is designed for continuous output at any point of time. When cleaning is taking place, it is only two of the filtration modules that are shut off and the remaining filtration modules continue to work with an increased flow of the fluid as compared to normal flow. The sealed filtration module at both ends which is undergoing backwash, results in more filtrate from the bottom chamber being available for the remaining filtration modules and thus level of the output gets reduced only partially, resulting in a continuous flow of the filtrate from the top chamber. The novel T-shaped pipe arm (10) present in the top chamber enables superior back wash by using the filtrate from one of the module as the backwash liquid for the opposite pair of filtration module.

[0070] Referring to Fig 1 and Fig 21, the T shaped pipe arm (10) that caps the tops of any pair of individual filtration modules (6) placed diametrically opposite each other moves at a pre determined rate in a predetermined angle. This movement is synchronised with the movement of the movable arm (17), such that the inward flow from the bottom for one of the modules of the duplex pair is stopped completely, and instead, the movable arm (17) acts as the backwash slurry discharge channel (19) for that module. Thus, one filtration module (6) in the duplex pair effectively becomes positioned to receive the filtered fluid output of the other module and due to the moving arm one end is opened to a atmospheric pressure through the drain nozzle free flow of back wash slurry takes place without any restriction The necessary sealing to prevent leakage during backwash is provided by the unique and effective system. Thus begins the timed backwash cycle for one of the filtration modules. The moving T shaped pipe arm at the top (10) and the moving arm at the bottom (17) are so arranged that by rotating them to the predetermined degree, it can ensure the backwash of all the filtration modules, by pairing each module of all the duplex pairs (6) constituting the main body (22) of the device in turn.

During backwash the common chamber stops receiving filtered fluids from the pair of modules that are capped with the T shaped arm (10), but the remaining modules continue to discharge filtered fluid at a higher rate, into the common chamber (1 1) thereby providing a continuous output with zero downtime. Thus the cumulative effective of the following three factors contribute to efficient backwash.

a. Once the differential pressure between inlet & outlet is triggers for the movement of top T arm & bottom discharge arm one end of the bottom discharge arm is open to atmosphere. The bottom arm capping the inlet of one of the module of bottom end acts as a drain nozzle which is open to atmosphere. The pressure difference between inside the vessel & the atmospheric pressure will cause the fluid to rush through the element towards the drain nozzle at the bottom, thus effectively & efficiently causing reversal in the direction of the flow of liquid.

b. Dedicated flow of filtrate from one module into the module being backwashed, which renders one filtration module less to perform the filtration but the volume to be processed remains constant. As fluid that was rising upwards info all modules, rises through one module less during backwash, the velocity of flow of fluid through the remaining module is slightly higher than when v backwash is not in progress.

c. The filter elements are made up of triangular wire with two inner faces of the spirally wound triangular wire profiles that support the filter element made of multi-layered sintered woven wire mesh. The wedge-shaped surfaces of the triangular wires form a slit which widens radially inwardly between adjacent triangular wire spirals; this creates an effect analogous to the effect of pinching the mouth/ nozzle of a garden hose, thus speeding up the backwash fluid just before it hits the inside of the multi-layered sintered woven wire mesh element, known as the Venturi effect.

Although embodiments of this invention have been shown and described, it is to be understood that various modifications and substitutions, as well as rearrangements of parts and components can be made by those skilled in the art without departing from the novel spirit and scope of the invention.

Claims

A bolted down single integrated housing equipment of two filters with a small footprint, comprising of first stage and second stage filtration apparatus with automatic self cleaning of filtration modules of both stages, resulting in continuous output with zero downtime; the first stage apparatus comprising of a bottom chamber with an inlet pipe; a conical screen; a rotatable movable pipe arm and a constantly open drain nozzle; the second stage apparatus comprising a body in which are housed multiple filtration modules in diametrically opposing manner containing the filtration elements welded to a flange at the top and supported by a plate at the bottom; a top chamber to collect the filtrate; an outlet for discharge of the filtrate; a rotatable T shaped pipe arm to seal two diametrically opposing filtration modules during backwash; the filtrate of one module acting as the Backwash fluid for the other module undergoing backwash; the said T shaped pipe arm being connected to the moving slurry discharge arm by means of a shaft; all designed in such a manner that the output of the first stage filter is the input for the second stage filter on an average; the filtrate in the first stage is lower than 400μ and the filtrate of the second stage is lower than 30μ; flow of the filtrate is always from out to in except in the filtration module being backwashed wherein it is in to out; with efficient backwash due to increased backwashing fluid velocity. ¹ The bottom chamber of the first stage filter as claimed in Claim 1 comprises of a substantially cylindrical shape on the outside and a conical screen being placed on the inside at a sharp inclination to a vertical; the said conical screen being bolted to the top and bottom side inside the housing circumferentially and acts as a filtration element in the first stage. The drain nozzle as claimed in Claim 1 being located on the bottom floor of the first stage filter between the conical screen and the outer wall of the bottom chamber, constantly evacuating the solids that are filtered by the first stage filter.

The conical screen as claimed in Claim 1 comprising of substantially placed triangular profile wires with the flat surface facing the inner side of the bottom chamber; the said profile wire opposite end of the flat surface being welded to support rods at all contact points; the profile wire wedge shaped two faces due to the substantial tilt to the vertical direction enabling the liquid containing the solids less than the slot opening to pass to the other side much easier and the unfiltered solid to drop down to the floor of the bottom chamber easily; the flat surface of the wedge wire is positioned at a slight incline in such a manner so as to trap solids of less density, forcing the fluid that touches its surface outwards and into the second stage; the vortex of the incoming fluid pushing the less dense solids of higher size than the slot opening downwards, thus enabling the solids of all densities to be flushed from the bottom chamber through the drain nozzle.

5. The movable pipe arm at the bottom chamber during back wash mode as claimed in Claim caps_any one of the plurality of filtration modules once ΔΡ levels are reached, completely stopping the entrance of the first stage fluid from entering the said module paving the way for discharge route for the slurry from that module.

6. The moveable pipe arm as claimed in Claim 1 opens out into atmospheric pressure, giving a free passage during the reversal of the flow of the filtrate from top to bottom at a greater velocity; thus resulting in efficient backwash.

7. The filtration element as claimed in Claim 1 comprising of a cylindrical core constituted of triangular welded wedge wire profiles with the flat surface facing outside and the wedge surface facing inside; two faces of the spirally wound triangular wedge wire forming a slit widening radially inwards, giving rise to the Venturi Effect; the apex of the triangular wedge wire being welded to the projection portion of the support rods at contact points; covered on the outside by a sleeve of multi-layered sintered woven mesh, welded in place both longitudinally and circumferentially over the cylindrical core, enabling filtrate flow from out to in at all times except during backwash.

8. The filtration element claimed in Claim 7, can be manufactured from as low as 32 mm diameter & upwards, making the element both low cost and low footprint.

9. The moving pipe arm during backwash mode as claimed in Claim 1 caps any one of the plurality of the filtration module once ΔΡ levels are reached completely stopping the entrance of the first stage fluid from entering the said module from the bottom thus paving a way for the complete liquid to pass through the remaining module upward with a higher velocity with a larger flow rate, resulting in the movable T shaped pipe arm in the top chamber during back wash receiving the high flow rate filtrate with a higher velocity.

10. A method of filtering particles of less than 30 μ from low viscosity liquids using an integrated two stage filter housed in a single equipment having a bottom chamber which is substantially cylindrical on the outside and conical on the inside with a tangentially mounted inlet pipe having a conical screen fixed circumferentially to the bottom chamber, having a continuously open drain nozzle located between the conical screen and the outer wall of the bottom chamber, draining out the solids greater than 400μ particle size; using both the Hydrocyclone and the Coanda effect; resulting in filtrate with particle size lower than 400μ; which is the input for the second stage filter comprising the steps of:

Allowing the filtrate from 1^st stage to enter the body of 2^nd stage which houses multiple filtration modules, arranged in such a manner that the filtrate of the 2ⁿ . stage is pushed from bottom upwards to the top chamber; and direction of the filtrate flow is from outside to inside of the filter elements;

Collecting the filtrate at the top chamber and discharging the same through an outlet pipe located at the top of the top chamber;

Automatically triggering for rotation the T shaped pipe arm on reaching present ΔΡ levels to cap two diametrically opposite filtration modules located in the top chamber for a predetermined time for the back wash cleaning.

Simultaneously sealing the bottom of one of the said pair of filtration modules by means of the movable arm located in the bottom chamber for the same time as the T shaped pipe arm; The full flow of filtrate from one module acting as the backwash liquid for the other module for efficient back wash.

The sealing of the two modules on the top and one module at the bottom resulting in higher filtrate flow in the remaining filtration modules enabling higher flow rate in each module at an increased velocity of the backwash fluid as the flow increases due to absence of one of the filtration modules for filtration;

As a result of one end of the moving arm into the atmospheric area the backwash slurry flows in the drain from top. to bottom without any obstacle from bottom;

the design of the filter element contributing to the Venturi Effect, which also contributes to the increased velocity of the backwash fluid;

the said T shaped pipe arm and movable arm moving from one pair of filtration module to the next till one complete cycle is completed;

the said T shaped pipe arm and movable arm being non functional till ΔΡ levels are once again reached;

the remaining filtration modules continuing to produce the filtrate, resulting in continuous outflow with zero downtime.