WO2013014475A1 - Apparatus for fluid sample filtration - Google Patents

Apparatus for fluid sample filtration Download PDF

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Publication number
WO2013014475A1
WO2013014475A1 PCT/HU2011/000131 HU2011000131W WO2013014475A1 WO 2013014475 A1 WO2013014475 A1 WO 2013014475A1 HU 2011000131 W HU2011000131 W HU 2011000131W WO 2013014475 A1 WO2013014475 A1 WO 2013014475A1
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WO
WIPO (PCT)
Prior art keywords
hollow shaft
rotor
plastic plug
hollow
slit
Prior art date
Application number
PCT/HU2011/000131
Other languages
French (fr)
Inventor
Tamás CSERFALVI
Original Assignee
Aqua-Concorde Kft.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aqua-Concorde Kft. filed Critical Aqua-Concorde Kft.
Publication of WO2013014475A1 publication Critical patent/WO2013014475A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/27—Filters with filtering elements which move during the filtering operation with rotary filtering surfaces, which are neither cylindrical nor planar, e.g. helical surfaces
    • B01D33/275—Filters with filtering elements which move during the filtering operation with rotary filtering surfaces, which are neither cylindrical nor planar, e.g. helical surfaces using contiguous impervious surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/44—Regenerating the filter material in the filter
    • B01D33/48—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/44—Regenerating the filter material in the filter
    • B01D33/52—Regenerating the filter material in the filter by forces created by movement of the filter element
    • B01D33/56—Regenerating the filter material in the filter by forces created by movement of the filter element involving centrifugal force
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/34—Purifying; Cleaning

Definitions

  • the object of the present invention is an apparatus for fluid sample filtration with stator and rotor parts, the rotor comprises slit filtering unit.
  • the undissolved components of a raw wastewater sample can be sorted into the following 3 fractions:
  • the entering of the fraction c into the measuring system has to be blocked.
  • the fractions a and b which contain the polluting components have to reach the measuring system.
  • the fundamental points of longterm and reliable operation of the water analyzer monitors are that the sample treating process should not remove the fine fraction of the suspended matter and the sample components should not damage the measuring system.
  • the fraction b usually contains inorganic particles, in wastewaters these are mostly fine quarz crystal particles. These generate abrasive effects and in longterm operation they damage certain parts of the measuring system, like pumps, valves, stirrers and the optical windows contacting the sample stream. To avoid the excessive wearings in the analysers (to ensure the longterm reliability of the monitor operation) these abrasive particles should be removed from the fraction b during the sampling or sample treating steps.
  • the characteristic sample amount required by the analytical processes for a measurement are relatively small, 1-50 cm 3 volume or 1-50 cm 3 /min flow rate.
  • centrifugation (economically applicable only at high concentrations and in case of particles of higher specific densities)
  • the 2 method is applied ( analytical filter papers, filter membranes, sintered filter layers) and the filtration efficiency is controlled by the selection of filter of proper porus size.
  • the sintered filter layers have the mechanical rigidity required for regenerations made by chemical washing or fluid backwashing.
  • the surface-filtration is possible on filtering layers with definit porus geometry which excludes the filtered materials from entering the particles into the bulk filter material. Since the filtered particles are collected on the surface of the filter layer, these can be removed by some physical method for cleaning (regeneration) the filter. For example the surface filters can be continuously self-cleaned by a strong tangential flow of the fluid along the active side of the filter layer (so called tangential flow filtration or crossflow filtration).
  • the DDS JET 2000 (5 - 5000 m 3 /h) filration equipment (Dango & Dienenthal Filtertechnik GmbH, D) applies filtering slits width of 100 micrometer and strong fluid stream to remove the particles from the filter surface.
  • the DDF slit-filter from the same manufacturer has 25 micrometer slits and applies the continuous tangential flow and the programmed back flushing for sustain the performance of the filter unit.
  • the DELTA-STRAIN filtration equipment (DELTAFILTER Filtrationssysteme GmbH, Speyer, D ) applies a spiral slits on rotating cylinder structure to achieve 100-150 micrometer particle separation size in water at 20-250 m 3 /h production rate.
  • the cleaning is made by pushing a long metal edge against the rotating cylindrical surface (razor effect).
  • One of the most widely used filtration technique in monitors is the filter with moving filter strip (for example PROTOC WEB, PPM Ltd, GB).
  • a filter paper strip of 25 mm width from a feeding roller is stepped through upon the underwater smooth filter manifold surface which has a suction hole connected to the filter pump.
  • One position of the filter paper strip can be used to produce 1-10 cm 3 filtrate then the strip is stepped to replace the used section with a new section at the filtrating position.
  • the advantage of this technique is its simple mechanical structure and the high and reliable filtration efficiency. Considering the analysis of the fine fraction of the suspended matter in water sample, the method removes most of the fraction b.
  • the SKALAR On-line Filtration System (Skalar Analytical B.V., Breda, The Netherlands) is an aggregated filtermembrane tube system with strong tangential flow. Additional cleaning is applied by a backflow stream chemical washing in the dual channel equipment (one channel is operating while the other is under regeneration). Production rate is 1 dm 3 /min at 2.5 bar pressure difference on the filter membrane. This filter system removes all suspended and colloidal components from the water sample.
  • the WTW PurCon (WTWijnlich-Technische psychologyen GmbH, Weilheim, D) also removes all particles (including bacteria) by a membrane filter and produces 3,6 dm 3 /h clear filtrate for monitors.
  • the fine filtering unit developed by the Endress+Hauser (Endress+Hauser Instruments International AG, Reinach, Switzerland) for the TOCII CA72TOC total organic carbon monitor is a rotating slit filter system and belongs to the surface filtration method.
  • the slit of annular shape is 100 micrometer wide and performs a good particle size separation which allows the organic fine suspendede matter to reach the measuring cell.
  • the rotor with 50-60 rev/min helps the continuous removal of the exiuded particles by the sample flow.
  • a great disadvantage of this system is that the abrasive particles of less than 100 micrometer reach the toe bearing of the axial shaft rotor. Because this part can not be protected in this system, the lifetime of the filtration unit is seriously limited and requires frequent replacement to keep the monitor performance.
  • the surface filters can not separate the quartz particles within the fraction b particles, furthermore, this fraction is usually removed from the water sample (membrane filters).
  • Present invention describes an apparatus for fluid filtration which overcomes the disadvantages of the known techniques regarding no separation performance on the fine fraction of the suspended matter against the quartz or other (heavy) abrasive particles, by offering an extra separation effect for the abrazive (heavy) particles from the ⁇ 0.3 mm particle fraction required by the wastewater monitors for total organic carbon or heavy metal pollution.
  • the invention is based on the recognition that the combination of the slit filtration with a centrifugal counter-force acting on the particles to be removed, the numeric concentration of the heavier abrazive particles (inorganic particles with higher specific densities) can be effectively reduced in the filtrate.
  • the apparatus of the invention contains a cylindrical filter rotor constructed from coaxial discs slits and this rotor unit is rotated and the resulted centrifugal force counteracts to the radially applied filtration flow within each slit.
  • the above separation effect against the heavier particles depends on the size of the individual slits and on the rotation speed generating the centrifugal force. This latter factor can be set at any value within the technical limits, therefore the separation efficiency against the heavier particles can conveniently be adjusted even during the operation.
  • a self-cleaning effect is also generated by the rotation of the slits of the cylindrical rotor body.
  • the tangential shearing rate in the surrounding fluid is in the 1-10 m/s range, which effectively removes the excluded particles of the coarse components.
  • An advantageous construction of the apparatus of the invention applies a rotor with a hollow shaft equipped with two holding discs, a cylindrical slit system between these holding discs, a protruding hollow end- plug closing the hollow end of the hollow shaft, a stator frame, a sucking tube in the borehole of the end plug of the rotor which tube is protruding from the stator frame, on the stator frame a supporting part which surrounds the sucking tube, in the shallow borehole of the supporting part an elastic part pushing a flat plate to the face of the end body of the hollow shaft, and the hollow shaft is equipped with collecting slots and radial holes in the range of the cylindrical slit system.
  • Another advantageous construction of the apparatus of the invention applies a cylindrical rotor with a slit system built from separated thin discs arranged with radial symmetry and the size of the slits is set to the minimal size of the particles to be separated from the fluid, the sucking tube is loosely fitting into the borehole of the hollow rotor shaft and its closing part is a plastic plug.
  • a further advantageous construction of the apparatus of the invention applies a rotor rotation speed range of 100 - 3000 rev/min with the preferable range between 500-1500 rev/min and is equipped with a programmed backwashing system for the filtering slits.
  • FIG 1 is the scheme of the apparatus. of the invention
  • Figure 2 shows the filtration and backwashing arrangement of the apparatus in Figure 1.
  • the apparatus in Figure 1 has two main units, a rotor and a stator.
  • the 4 cylindrical part is built from thin discs which are piled up in a radially symmetrical arrangement with gaps between them.
  • the slit size resulted on the cylindric surface by the gaps between the thin discs determines the minimal size of the separated particles.
  • the 1 hollow shaft has an axial borehole from its end being below the 3 holding disc up to the position between 2 and 4 parts.
  • the 6 radial borehole boreholes are connecting the volumes of the 5 collecting slots to the sad axial borehole in the 1 hollow shaft.
  • the open end of the 1 hollow shaft is equipped by the 7 tight fitting bored plastic plug which is axially supported by a diameter stepdown of the bore in the hollow shaft. This plug protrudes from the hollow shaft and has a fine machined end in contact with the 8 sliding sealing plate part.
  • the 11 axial tubeshaft has a loose position in the borehole of the 7 plastic plug part and tight position in the 10 supporting part.
  • the 9 tube is sitting on the 10 part and pushes up the 8 changeable sliding sealing part to the machined end of the 7 plastic plug part.
  • the 13 part is the holding frame of the apparatus.
  • the 11 axial tube shaft goes through the 10 supporting part and protrudes from 13 frame
  • the 8 sliding sealing plate, the 9 part, the 11 tubeshaft together with the 13 frame build up the stator unit of the apparatus.
  • the operation of the apparatus is the following:
  • the assembled apparatus is submerged into the unfiltered (raw) fluid to a position where the 2 part is already well covered by the fluid.
  • the 11 tubeshaft is connected to an inlet port of a pump and by operating this pump the suction is shown by the 12 arrow.
  • Driving the 1 hollow shaft by a rotating motor with 100-3000 rev/min speed according to the 14 sign.
  • the rotor unit consisted of the 1-7 parts is rotating in the fluid and the 12 suction force acts back to 4 slits through the 11 tubeshift, the 6 radial boreholes and the 5 collecting slots.
  • the fluid Due to the radial suction force the fluid enters the slits and the gaps behind them and carries all those suspended particles which on one side are smaller than the slit size and on the other side those have low mass and can travel together with the fluid against the centrifugal force radially directed outward to the bulk fluid around the rotor unit.
  • the fluid containing the fine particles without the heavy ones travels through the gaps to the 5 collecting slots then enters the axial hole in the 1 hollow shaft, then through the 11 tubeshaft the filtrate moves to the 12 direction.
  • the sliding sealing between the 7 and 8 parts, pressed together by the 9 part is the main contact between the rotor and stator units which is lubricated by the fluid itself. Here there are only a very thin fluid layer and the suspended particles are exluded completely.
  • a continuous self-cleaning effect is generated by the high tangential shear force at the 4 cylindrical slit surface which prevents the build up of a secondary deep filtering layer from the excluded particles on the openings of the slits.
  • the filtration and backwashing processes can be together described on the scheme shown in Figure 2 where the 14 part is the whole filtering system shown in Figure 1.
  • the 15 shaft of the rotor is connected to the 16 driving motor.
  • the 14 filtration unit is submerged below the level of the 18 fluid controlled by the 19 overflow tube in the 17 vessel and its output tube is connected, in one direction, through the 20 valve to the 21 vessel containing washing-flushing fluid, in the other direction to the 22 sample sucking pump which produces the filtered sample on the 23 output flow.
  • the 17 vessel is filled continuously or periodically with the raw fluid to be sampled.
  • the process starts with the opening of the 20 valve after the 16 motor is switched on.
  • the pressure depression caused by the rotation in the 14 unit sucks in the 21 washing solution and this solution will go through the filtering slits in the rotor unit described in Figure 1.
  • the 21 backwashing fluid can be the ambient air or a suitable washing solution (prepared with acidic, alkalic and detergent components) or the mixture of these.
  • the stopping of the 22 sample sucking pump is not required but it should be off if the entering of the washing fluid into the output sample carrying tube causes interferences in the futher process.
  • the cleaning efficiency can be increased by the lowering the 18 liquid level in the 17 vessel below the position of the filter rotor of the 14 unit by opening the 25 draining valve and , if necessary, stopping the 24 inflow stream. Then the operation according to the process A can be started.
  • the increased backwashing effect is caused by the increased outward flow rate in the slits due to the removal of the static and dynamic counterpressure caused by the fluid level of the 17 vessel at the rotor surface.
  • the 4 part in Figure 1 was built with 33 pieces of celluloid discs of 33 mm diameter and 0.3 mm thickness, the slit value was 0.2-0.3 mm.
  • the 17 water vessel was filled with 20 dm 3 tap water and compressed air mixing was applied through a submerged pipe.
  • the 14 filter apparatus was mounted onto the water vessel according to Figure 2, and its rotor was driven with 1400 /min rotation speed by an electrical motor, the 22 sample sucking pump worked with 9 cm 3 /min volumetric flow rate
  • the water was loaded with clay colloids and cellulose fibers by pouring a bentonite slurry (prepared from 20 g bentonite in 100 cm 3 tap water) and a dilute pulp of cellulose fibers prepared from 2 g paper napkin piece desintegrated in 25 cm 3 tap water by an ultrasonic head (fiber lengths were in the 1-3 mm range), and mixing thoroughly with air bubbling.
  • a bentonite slurry prepared from 20 g bentonite in 100 cm 3 tap water
  • a dilute pulp of cellulose fibers prepared from 2 g paper napkin piece desintegrated in 25 cm 3 tap water by an ultrasonic head (fiber lengths were in the 1-3 mm range), and mixing thoroughly with air bubbling.

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Abstract

The object of the invention is an apparatus for filtration of fluid sample having a stator and a rotor part, latter contains a slit filter system. The rotating part of the apparatus of the invention comprises a hollow shaft (1), holding discs (2, 3) mounted onto the hollow shaft (1), a cylindrical part (4) equipped with a slit system, a hollow plastic plug (7) closing the hollow shaft (1) and it protrudes from the end of the hollow shaft (1), a stator frame (13), a sucking tube (11) which is positioned in the bore of the hollow plastic plug (7) and it portrudes from the stator frame (13), a supporting part (10) mounted on the frame (13), an elastic part (9) which fits into the end bore of the supporting part (10) and pushes a sliding sealing plate (8) to the front face of the hollow plastic plug (7) of the rotor, and the hollow shaft of the rotor part is equipped with collecting slots (5) and radial boreholes (6) in the range of the cylindrical part (4).

Description

Apparatus for fluid sample filtration
Technical field
The object of the present invention is an apparatus for fluid sample filtration with stator and rotor parts, the rotor comprises slit filtering unit.
Background art
Many water analyzer instruments, for example wastewaster monitors, have the scope to determinate the sum amount of the polluting component concentration carried by the dissolved fraction and by the fine suspended matter in the fluid sample. To achieve this goal these instruments require such sample which contains only the size fraction of <0.3 mm of the suspended matter. The chemical reason is that the heavy metals are mostly precipitated into the fine fraction of the suspended matter in wastewaters, therefore the filtering out of the fine fraction in the sample treatment process must be avoided to perform reliable analysis.
The undissolved components of a raw wastewater sample can be sorted into the following 3 fractions:
a/ colloids
b/ fine suspended matter with particle size below 0.3 mm
c / coarse supended and fibrous matters.
In order to avoid the clogging of the tubings and the measuring cell itself, the entering of the fraction c into the measuring system has to be blocked. At the same time the fractions a and b which contain the polluting components (for example Zn, Cd, Cu, Ni, Pb ) have to reach the measuring system. The fundamental points of longterm and reliable operation of the water analyzer monitors are that the sample treating process should not remove the fine fraction of the suspended matter and the sample components should not damage the measuring system.
The fraction b usually contains inorganic particles, in wastewaters these are mostly fine quarz crystal particles. These generate abrasive effects and in longterm operation they damage certain parts of the measuring system, like pumps, valves, stirrers and the optical windows contacting the sample stream. To avoid the excessive wearings in the analysers (to ensure the longterm reliability of the monitor operation) these abrasive particles should be removed from the fraction b during the sampling or sample treating steps. The characteristic sample amount required by the analytical processes for a measurement are relatively small, 1-50 cm3 volume or 1-50 cm3/min flow rate.
In case of fluids the removal of the suspended matter is based on one of the following methods:
1. sedimentation aided by coagulation and flocculation, for example surface water clarification, economic only for technologies of high production rate, removes 90-95% of the fraction b
2. filtration (deep filtration in thick filter bed, surface filtration on filter layer)
3. centrifugation (economically applicable only at high concentrations and in case of particles of higher specific densities)
In the general chemical laboratory practice the 2 method is applied ( analytical filter papers, filter membranes, sintered filter layers) and the filtration efficiency is controlled by the selection of filter of proper porus size. Among the above filter materials the sintered filter layers have the mechanical rigidity required for regenerations made by chemical washing or fluid backwashing.
Due to economic consideration the filtration is generally used in the sample treating units of the analytical monitors as this method can apply cheap and dispensable filter matters.
The surface-filtration is possible on filtering layers with definit porus geometry which excludes the filtered materials from entering the particles into the bulk filter material. Since the filtered particles are collected on the surface of the filter layer, these can be removed by some physical method for cleaning (regeneration) the filter. For example the surface filters can be continuously self-cleaned by a strong tangential flow of the fluid along the active side of the filter layer (so called tangential flow filtration or crossflow filtration).
Large technology fine filters for example:
The DDS JET 2000 (5 - 5000 m3/h) filration equipment (Dango & Dienenthal Filtertechnik GmbH, D) applies filtering slits width of 100 micrometer and strong fluid stream to remove the particles from the filter surface. The DDF slit-filter from the same manufacturer has 25 micrometer slits and applies the continuous tangential flow and the programmed back flushing for sustain the performance of the filter unit.
The DELTA-STRAIN filtration equipment (DELTAFILTER Filtrationssysteme GmbH, Speyer, D ) applies a spiral slits on rotating cylinder structure to achieve 100-150 micrometer particle separation size in water at 20-250 m3/h production rate. The cleaning is made by pushing a long metal edge against the rotating cylindrical surface (razor effect).
Filtration methods applied in the sample treatment processes of the analytical monitors:
One of the most widely used filtration technique in monitors is the filter with moving filter strip (for example PROTOC WEB, PPM Ltd, GB). A filter paper strip of 25 mm width from a feeding roller is stepped through upon the underwater smooth filter manifold surface which has a suction hole connected to the filter pump. One position of the filter paper strip can be used to produce 1-10 cm3 filtrate then the strip is stepped to replace the used section with a new section at the filtrating position. The advantage of this technique is its simple mechanical structure and the high and reliable filtration efficiency. Considering the analysis of the fine fraction of the suspended matter in water sample, the method removes most of the fraction b. The SKALAR On-line Filtration System (Skalar Analytical B.V., Breda, The Netherlands) is an aggregated filtermembrane tube system with strong tangential flow. Additional cleaning is applied by a backflow stream chemical washing in the dual channel equipment (one channel is operating while the other is under regeneration). Production rate is 1 dm3/min at 2.5 bar pressure difference on the filter membrane. This filter system removes all suspended and colloidal components from the water sample.
The WTW PurCon (WTW Wissenschaftlich-Technische Werkstatten GmbH, Weilheim, D) also removes all particles (including bacteria) by a membrane filter and produces 3,6 dm3/h clear filtrate for monitors.
The fine filtering unit developed by the Endress+Hauser (Endress+Hauser Instruments International AG, Reinach, Switzerland) for the TOCII CA72TOC total organic carbon monitor is a rotating slit filter system and belongs to the surface filtration method. The rotating slit is set between a vertically positioned stainless steel cylinder rotor (d= 5 mm) and a stainless steel sleeve in the stator body. The slit of annular shape is 100 micrometer wide and performs a good particle size separation which allows the organic fine suspendede matter to reach the measuring cell. The rotor with 50-60 rev/min helps the continuous removal of the exiuded particles by the sample flow. A great disadvantage of this system is that the abrasive particles of less than 100 micrometer reach the toe bearing of the axial shaft rotor. Because this part can not be protected in this system, the lifetime of the filtration unit is seriously limited and requires frequent replacement to keep the monitor performance.
In general the surface filters can not separate the quartz particles within the fraction b particles, furthermore, this fraction is usually removed from the water sample (membrane filters).
Disclosure of invention
Present invention describes an apparatus for fluid filtration which overcomes the disadvantages of the known techniques regarding no separation performance on the fine fraction of the suspended matter against the quartz or other (heavy) abrasive particles, by offering an extra separation effect for the abrazive (heavy) particles from the <0.3 mm particle fraction required by the wastewater monitors for total organic carbon or heavy metal pollution.
The invention is based on the recognition that the combination of the slit filtration with a centrifugal counter-force acting on the particles to be removed, the numeric concentration of the heavier abrazive particles (inorganic particles with higher specific densities) can be effectively reduced in the filtrate.
The apparatus of the invention contains a cylindrical filter rotor constructed from coaxial discs slits and this rotor unit is rotated and the resulted centrifugal force counteracts to the radially applied filtration flow within each slit. The greater the density of the particle the greater the centrifugal force affecting on it, and this effect hinders the inward radial motion of the small heavy particles in the slits. The above separation effect against the heavier particles depends on the size of the individual slits and on the rotation speed generating the centrifugal force. This latter factor can be set at any value within the technical limits, therefore the separation efficiency against the heavier particles can conveniently be adjusted even during the operation.
A self-cleaning effect is also generated by the rotation of the slits of the cylindrical rotor body. The tangential shearing rate in the surrounding fluid is in the 1-10 m/s range, which effectively removes the excluded particles of the coarse components.
An advantageous construction of the apparatus of the invention applies a rotor with a hollow shaft equipped with two holding discs, a cylindrical slit system between these holding discs, a protruding hollow end- plug closing the hollow end of the hollow shaft, a stator frame, a sucking tube in the borehole of the end plug of the rotor which tube is protruding from the stator frame, on the stator frame a supporting part which surrounds the sucking tube, in the shallow borehole of the supporting part an elastic part pushing a flat plate to the face of the end body of the hollow shaft, and the hollow shaft is equipped with collecting slots and radial holes in the range of the cylindrical slit system.
Another advantageous construction of the apparatus of the invention applies a cylindrical rotor with a slit system built from separated thin discs arranged with radial symmetry and the size of the slits is set to the minimal size of the particles to be separated from the fluid, the sucking tube is loosely fitting into the borehole of the hollow rotor shaft and its closing part is a plastic plug.
A further advantageous construction of the apparatus of the invention applies a rotor rotation speed range of 100 - 3000 rev/min with the preferable range between 500-1500 rev/min and is equipped with a programmed backwashing system for the filtering slits.
Brief description of drawings
The detailed description of the apparatus of the invention is based on the attached drawing schemes where
Figure 1 is the scheme of the apparatus. of the invention
Figure 2 shows the filtration and backwashing arrangement of the apparatus in Figure 1.
Best mode of carrying out the invention
The apparatus in Figure 1 has two main units, a rotor and a stator.
Between the detachable 2 and 3 holding discs on the 1 hollow shaft of the rotor unit the 4 cylindrical part is built from thin discs which are piled up in a radially symmetrical arrangement with gaps between them. The slit size resulted on the cylindric surface by the gaps between the thin discs determines the minimal size of the separated particles. In the region where the 1 shaft holds the 4 cylindrical part there are the 5 collecting slots and the 6 radial boreholes in these collecting slots. The 1 hollow shaft has an axial borehole from its end being below the 3 holding disc up to the position between 2 and 4 parts. The 6 radial borehole boreholes are connecting the volumes of the 5 collecting slots to the sad axial borehole in the 1 hollow shaft.
The open end of the 1 hollow shaft is equipped by the 7 tight fitting bored plastic plug which is axially supported by a diameter stepdown of the bore in the hollow shaft. This plug protrudes from the hollow shaft and has a fine machined end in contact with the 8 sliding sealing plate part.
The above mentioned parts build up the rotor unit of the apparatus.
The 11 axial tubeshaft has a loose position in the borehole of the 7 plastic plug part and tight position in the 10 supporting part. The 9 tube is sitting on the 10 part and pushes up the 8 changeable sliding sealing part to the machined end of the 7 plastic plug part. The 13 part is the holding frame of the apparatus. The 11 axial tube shaft goes through the 10 supporting part and protrudes from 13 frame
The 8 sliding sealing plate, the 9 part, the 11 tubeshaft together with the 13 frame build up the stator unit of the apparatus.
The operation of the apparatus is the following:
The assembled apparatus is submerged into the unfiltered (raw) fluid to a position where the 2 part is already well covered by the fluid. The 11 tubeshaft is connected to an inlet port of a pump and by operating this pump the suction is shown by the 12 arrow. Driving the 1 hollow shaft by a rotating motor with 100-3000 rev/min speed according to the 14 sign. The rotor unit consisted of the 1-7 parts is rotating in the fluid and the 12 suction force acts back to 4 slits through the 11 tubeshift, the 6 radial boreholes and the 5 collecting slots. Due to the radial suction force the fluid enters the slits and the gaps behind them and carries all those suspended particles which on one side are smaller than the slit size and on the other side those have low mass and can travel together with the fluid against the centrifugal force radially directed outward to the bulk fluid around the rotor unit. The fluid containing the fine particles without the heavy ones travels through the gaps to the 5 collecting slots then enters the axial hole in the 1 hollow shaft, then through the 11 tubeshaft the filtrate moves to the 12 direction. The sliding sealing between the 7 and 8 parts, pressed together by the 9 part is the main contact between the rotor and stator units which is lubricated by the fluid itself. Here there are only a very thin fluid layer and the suspended particles are exluded completely.
A continuous self-cleaning effect is generated by the high tangential shear force at the 4 cylindrical slit surface which prevents the build up of a secondary deep filtering layer from the excluded particles on the openings of the slits.
Within the filtrate flow system, from the rotor slits to the suction pump (4,5,6,11 parts) a pressure depression of 100-1000 Pa develops due to the centrifugal force acting on the fluid filling the 4 rotor slits, the 11 tube shaft and gap system. This negative pressure provides possibility of programmable backwashing of the filtering slits
The filtration and backwashing processes can be together described on the scheme shown in Figure 2 where the 14 part is the whole filtering system shown in Figure 1. The 15 shaft of the rotor is connected to the 16 driving motor. The 14 filtration unit is submerged below the level of the 18 fluid controlled by the 19 overflow tube in the 17 vessel and its output tube is connected, in one direction, through the 20 valve to the 21 vessel containing washing-flushing fluid, in the other direction to the 22 sample sucking pump which produces the filtered sample on the 23 output flow. The 17 vessel is filled continuously or periodically with the raw fluid to be sampled.
The programmable backwashing:
Execution A
The process starts with the opening of the 20 valve after the 16 motor is switched on. The pressure depression caused by the rotation in the 14 unit sucks in the 21 washing solution and this solution will go through the filtering slits in the rotor unit described in Figure 1. The 21 backwashing fluid can be the ambient air or a suitable washing solution (prepared with acidic, alkalic and detergent components) or the mixture of these. During the backwashing process the stopping of the 22 sample sucking pump is not required but it should be off if the entering of the washing fluid into the output sample carrying tube causes interferences in the futher process.
Execution B
The cleaning efficiency can be increased by the lowering the 18 liquid level in the 17 vessel below the position of the filter rotor of the 14 unit by opening the 25 draining valve and , if necessary, stopping the 24 inflow stream. Then the operation according to the process A can be started. The increased backwashing effect is caused by the increased outward flow rate in the slits due to the removal of the static and dynamic counterpressure caused by the fluid level of the 17 vessel at the rotor surface.
The separating effect on the abbrazive (heavy) particles is increasing by the rotation speed of the rotor, however, the cavitation is also increasing with the higher tangential speed and it may destroy the filter slits above 1500 rev/min. Due to this reason the upper rotation speed is practically 1500/min for continuous operation.
One application method of the apparatus of the invention together with its operation parameters are described in the following example.
The 4 part in Figure 1 was built with 33 pieces of celluloid discs of 33 mm diameter and 0.3 mm thickness, the slit value was 0.2-0.3 mm.
The 17 water vessel was filled with 20 dm3 tap water and compressed air mixing was applied through a submerged pipe.
The 14 filter apparatus was mounted onto the water vessel according to Figure 2, and its rotor was driven with 1400 /min rotation speed by an electrical motor, the 22 sample sucking pump worked with 9 cm3/min volumetric flow rate
The water was loaded with clay colloids and cellulose fibers by pouring a bentonite slurry (prepared from 20 g bentonite in 100 cm3 tap water) and a dilute pulp of cellulose fibers prepared from 2 g paper napkin piece desintegrated in 25 cm3 tap water by an ultrasonic head (fiber lengths were in the 1-3 mm range), and mixing thoroughly with air bubbling.
After 8 minutes operation of the filter apparatus 20 cm3 metal salt solution 5000 mg Cd / dm3 was mixed into the water, this addition produced a 5 mg/dm3 Cd pollution step in the investigated water.
Between the 10th-15th minutes of the operation 3 samples of 10 cm3 volume were taken at the 23 output flow and same amount from the 18 water as reference samples, the filtrate turbidimetric measurements resulted 94-96 % colloidal concentration compared to the water samples, and optical microscopic investigations (16 x magnification) resulted 1-3 % fiber content in the filtrate.
Determined by atomic emission analysis method the above filtrate samples had 91-96 % Cd concentration compared to the calculated value.
To the remained water int he 17 vessel (approximately 19 dm3) a suspended fine sand fraction was added and mixed to reach about 50 particles observable in the microscopic image field.
In the filtrate samples taken after this addition step the number of the sand particles oberved in microscopic field was 3-5% compared the water samples Based on the above figures the apparatus of the invention removed 95-97% of the sand particles while the colloidal particles of lower density were removed only by less than 10% and the metal hydroxide particles together with the dissolved metal fraction were decreased by less than 10% of the original content. List of numerical symbols
1 hollow shaft
2 holding disc
3 holding disc
4 cylindrical part
5 collecting slot
6 radial borehole
7 plastic plug
8 sliding sealing plate
9 elastic part
10 supporting part
11 sucking tube
12 suction
13 supporting frame
14 filter unit
15 driving shaft
16 motor
17 vessel
18 fluid
19 overflow
20 valve
21 washing/flushing fluid vessel
22 sample sucking pump
23 output flow
24 inflow stream
25 draining valve

Claims

1. Apparatus for sample filtration with stator and rotor containing a slit filter unit, which comprises a hollow shaft (1), holding discs (2, 3) mounted onto the hollow shaft(1), between the holding discs (2, 3) a cylindrical part with slit system (4), a hollow plastic plug (7) closing the bore in the hollow shaft (1) and protruding from the hollow shaft (1), a stator frame (13), a sucking tube (11) inserted into the plastic plug (7) and protruding of the frame (13), the supporting part (10) coaxial with the sucking tube (11), an elastic part (9) sitting in the pit on the end of the supporting part (10) which pushes up the sliding sealing plate (8) to the end of the hollow plastic plug (7), and the hollow shaft (1) equipped with collecting slots (5) and radial boreholes (6) in the range of the cylindric part (4).
2. Apparatus as defined in claim 1 , where the slit system of the cylindrical part (4) comprises disc shaped gaps between thin discs arranged with radial symmetry.
3. Apparatus as defined in claim 2, where the distance of the gaps in the slit system of the cylindrical part (4) is set to the minimal size of the particles to be separated.
4. Apparatus as defined in any of claims 1-3, where the sucking tube (11) of the stator is loosely fitted in the plastic plug (7) of the rotor.
5. Apparatus as defined in any of claims 1-4, where hollow plastic plug (7) is made of plastic material.
6. Apparatus as defined in any of claims 1-5, where sliding sealing plate (8) and the hollow plastic plug (7) works as sliding sealing.
7. Apparatus as defined in any of claims 1-6, where the rotor revolution speed is in the 100 - 3000 rev/min range, preferably between 500- 1500 rev/min.
8. Apparatus as defined in any of claims 1-7, where the slit system of the cylindrical part (4) is equipped with an auxiliary system for programmed backwash ing.
PCT/HU2011/000131 2011-07-27 2011-12-30 Apparatus for fluid sample filtration WO2013014475A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
HUP-1100411 2011-07-27
HUP1100411 2011-07-27

Publications (1)

Publication Number Publication Date
WO2013014475A1 true WO2013014475A1 (en) 2013-01-31

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103900891A (en) * 2014-04-10 2014-07-02 秦秀燕 Quick clarifying device for turbid water sample

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442234A (en) * 1944-05-11 1948-05-25 Russell P Dunmire Process of and apparatus for filtering materials
GB1261228A (en) * 1967-02-15 1972-01-26 Gino Maestrelli Improvements in or relating to self-cleaning solvent filters
US4177148A (en) * 1978-03-03 1979-12-04 Hach Chemical Company Mechanical strainer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442234A (en) * 1944-05-11 1948-05-25 Russell P Dunmire Process of and apparatus for filtering materials
GB1261228A (en) * 1967-02-15 1972-01-26 Gino Maestrelli Improvements in or relating to self-cleaning solvent filters
US4177148A (en) * 1978-03-03 1979-12-04 Hach Chemical Company Mechanical strainer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103900891A (en) * 2014-04-10 2014-07-02 秦秀燕 Quick clarifying device for turbid water sample

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