Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/10—Supported membranes; Membrane supports
  • B01D69/108—Inorganic support material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
  • B01D63/08—Flat membrane modules
  • B01D63/082—Flat membrane modules comprising a stack of flat membranes
  • B01D63/084—Flat membrane modules comprising a stack of flat membranes at least one flow duct intersecting the membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/39—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with hollow discs side by side on, or around, one or more tubes, e.g. of the leaf type
  • B01D29/41—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with hollow discs side by side on, or around, one or more tubes, e.g. of the leaf type mounted transversely on the tube
• • 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
  • B01D33/15—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces
  • B01D33/21—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with hollow filtering discs transversely mounted on a hollow rotary shaft
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/10—Supported membranes; Membrane supports
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/02—Inorganic material
  • B01D71/0215—Silicon carbide; Silicon nitride; Silicon oxycarbide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
  • B01D71/02—Inorganic material
  • B01D71/024—Oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2321/00—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
  • B01D2321/20—By influencing the flow
  • B01D2321/2033—By influencing the flow dynamically
  • B01D2321/2041—Mixers; Agitators
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/02—Details relating to pores or porosity of the membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2325/00—Details relating to properties of membranes
  • B01D2325/24—Mechanical properties, e.g. strength
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W10/00—Technologies for wastewater treatment
  • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

• TITLE DYNAMIC FILTRATION DEVICE WITH POROUS PLATE
• the invention relates to the field of filtration devices comprising an enclosure into which is injected a liquid to be filtered set in rotation, under vacuum or under pressure, said enclosure comprising at least one porous filtering plate made of a ceramic material in order to separate said liquid of its particles or molecules or even its microorganisms.
• the present invention particularly finds its application in the treatment of liquids from processes in the chemical or pharmaceutical industry, the food or agrifood industry, or in the field of energy, in particular in the treatment of production water from the mining, oil and gas industry.
• the injection of gas preferably air or even oxygen, is more particularly suited to the field of bioreactors in which the purification of the polluted liquid involves, in addition to filtration, a purification or a decomposition of the pollutants by microorganisms.
• Filters have been known for a long time from monolithic structures or supports of tubular geometry with or without membrane, formed of walls of a porous inorganic material delimiting one or more longitudinal channels parallel to the axis of said support.
• front filters typically comprising a portion of the channels blocked on their front face and a portion of the channels blocked on their rear face, in order to provide inlet channels and outlet channels separated by filtering walls through which must pass the liquid to be filtered.
• This is discharged by the passage of its molecules or particles or even of its microorganisms through the walls and the membrane, thus forming the retentate which then accumulates in the inlet channels while the purified liquid escapes through the output channels or even in part through the periphery of the filter if the latter is free.
• This technique is limited by the formation of a cake on the surface of the filter medium.
• non-monolithic filtering devices consist of a succession of porous plates within an enclosure, in which the liquid to be filtered is most often agitated so as to promote a turbulent regime. These devices promote the shearing forces within the liquid in contact with the porous plates and are more efficient for the depollution of highly charged or viscous liquids.
• Publication DE3814373A1 discloses, for example, a device provided with mobile porous discs preferably made of corundum or silicon carbide, materials more mechanically resistant so as to allow regeneration unlike filters in the form of mat.
• the publication DE19513759A1 also proposes a filtration module in which the parallel filtering discs are fixed in leaktight manner to a hollow mobile axis which collects the filtrate having passed through the porous material of the discs.
• the publication DE202004001955U1 also proposes a spring system placed on the axis to compensate for the expansion of the filter material which occurs during the high speed rotation of the filter elements in order to reduce the risk of breakage.
• International application W02009 / 039861A1 proposes a device for treating wastewater comprising an enclosure and a set of parallel plates, including fixed filter plates permeable to liquid and permeable aeration plates in order to inject air into the reactor, the said plates having a central cavity in which rotates an axis on which is fixed at least one rotating disc between the filtration plates and the aeration plates so as to agitate the liquid to be filtered.
• plates for example hollow ceramic plates comprising internal passages through which the filtrate can more easily be removed, as for example according to FIG. 7 of WO2009 / 039861A1 or even as proposed in publication EP2543420A1.
• Such plates can also have a membrane deposited on the largest faces of the filter plate as described for example DE202010015318U1.
• a filtration device comprising a porous ceramic filter plate which is more mechanically robust while retaining an acceptable filtration efficiency, that is to say having an optimized and maximized flow of the filtrate, with equal bulk and which can preferably be easily cleaned, that is to say periodically washed off the impurities collected by backwashing.
• the present invention is based on the principle of establishing a particular selection of ranges of said geometric characteristics and certain specific characteristics of the microstructure of the filter plate. Such a relationship, with the aim of solving the previously exposed problem, had never been described until now for such a device.
• the present application relates to a device for filtering a liquid loaded with mineral, inorganic and / or organic pollutants comprising:
• said plate having two opposite main faces separated by an average thickness e, said plate comprising in its center a through opening of greater width Z between the two main faces,
• At least the two main faces of the filter plate (s) are in contact with the liquid to be filtered in the enclosure and the filter plate is in fluid communication with the discharge means, on a portion of its surface which is otherwise insulated in a leaktight manner from the liquid to be filtered in the enclosure, so that the liquid passes through said plate, from the enclosure towards said evacuation means.
• said filter plate comprises a support made of a solid porous ceramic material and at least one porous separating layer covering at least partly, and preferably entirely, the surface portion of the support placed in contact with the liquid to be filter, said material comprises silicon carbide and its open porosity of said material is greater than 15% and less than 55% by volume and its pore volume distribution has a median pore diameter greater than 10 micrometers and less than 100 micrometers.
• the separating layer has an open porosity of between 10% and 70%, preferably between 30% and 50% by volume and a median pore diameter in number of between 5 nanometers and 5000 nanometers, preferably between 100 nanometers and 3000 nanometers , more preferably between 300 nanometers and 1000 nanometers.
• the thickness e of the filter plate is between 3mm and 20 mm, preferably between 4mm and 15 mm, more preferably between 5mm and 10 mm and the difference between the greatest length L of the filter plate and the largest width / of its central orifice is between 50mm and 700mm, preferably between 50mm and 600mm, more preferably between 75mm and 500mm.
• the device has one or more of the following characteristics, which can of course be combined if necessary:
• the plate has substantially the shape of a disc, its diameter D being equal to L.
• the orifice is substantially circular, its diameter d being equal to /.
• the filtration device comprises a plurality of filter plates, in particular between 2 and 200 filter plates.
• the filtration device also comprises at least one ventilation plate.
• the filter plate (s) are fixed, and comprising a system for stirring and / or rotating the liquid in the enclosure, in particular a propeller, a turbine or an axis provided with fins.
• the filter plate or plates are integral with a movable hollow axis constituting a means of evacuation of the filtered liquid, the said filter plate or plates being in fluid communication with the cavity of the axis.
• the longest length of the filter plate is between 100mm and 800mm, preferably between 300mm and 600mm.
• the largest width Z of the central opening is between 30mm and 200mm, preferably between 50mm and 150mm.
• the average thickness of the separating layer is between 1 micrometer and 100 micrometers, preferably between 20 micrometers and 80 micrometers.
• the separating layer is made of a material chosen from the group consisting of SiC, in particular recrystallized SiC, SiC linked by S13N4, or by S12ON2 or by SiAlON, or also by BN or a mixture of at least two of these compounds.
• the supply pressure of the liquid to be filtered is between 0.1 and 0.5 MPa.
• the filtration device further comprises means for pressurizing the liquid upstream of said enclosure supply means.
• the filtration device further comprises means for placing under vacuum, in particular means for sucking the liquid downstream of said means for evacuating the enclosure.
• said plate meets at least one of the following criteria:
• a support or substrate made of a solid porous ceramic material and at least one porous separating layer covering at least a portion of the surface of the support,
• said material comprises silicon carbide and preferably consists essentially of silicon carbide
• the open porosity of said material constituting the substrate is greater than 26% by volume, the open porosity of said material constituting the substrate / support is less than 45% by volume, more preferably is less than 40% by volume.
• the volume distribution of pores of said material constituting the substrate / support has a median pore diameter greater than 10 micrometers
• the volume distribution of pores of said material constituting the substrate / support has a pore diameter of less than 100 micrometers, preferably less than 40 micrometers, or even less than 30 micrometers,
• the separating layer has an open porosity of between 10 and 70%, preferably between 30 and 50%,
• the separating layer has a median pore diameter, in number, of between 5 nanometers and 5000 nanometers, preferably between 100 nanometers and 3000 nanometers, in particular between 100 nanometers and 1000 nanometers,
• the thickness e of the plate is between 3mm and 20 mm, preferably between 4mm and 15 mm, more preferably between 5mm and 10 mm, the difference between the longest length of the plate and the diameter of its central orifice is between 50mm and 700mm, preferably between 50mm and 600mm, more preferably between 75mm and 500mm. More preferably still, said difference is greater than 150 mm, or even greater than or equal to 200 mm, and in particular between 200 mm and 700 mm.
• the median pore diameter of said material is greater than the median pore diameter of the membrane separating layer (in number and / or in volume),
• the open porosity of said material is less than the open porosity of the membrane separating layer.
• the invention naturally also relates to the filtering plate as described above.
• a filter plate according to the invention obviously also has all the preferred characteristics described above in relation to the filtration device.
• the invention relates to the use of said device for the treatment of liquids from processes in the chemical or pharmaceutical industry, the food or agrifood industry, or in the field of energy, in particular the treatment of production water from the mining, oil and gas industry.
• support made from a solid porous ceramic material means that this support does not include any internal cavity (ies), apart of course from its intrinsic porosity.
• the open porosity and the median diameter of the pores of the support filter plate according to the present invention are determined in known manner by mercury porosimetry.
• the porosity corresponding to the overall pore volume, is measured by intrusion of Mercury at 2000 bars using a mercury porosimeter such as the Autopore IV 9500 Micromeritics porosimeter, on a 1 cm 3 sample taken from a block. of the support, the sampling region excluding the skin typically extending up to 500 microns from the surface of the block.
• the applicable standard is ISO 15901-1.2005 part 1.
• the increase in pressure until high pressure leads to "pushing" the mercury into pores of increasingly smaller size.
• the mercury intrusion is conventionally done in two stages.
• a mercury intrusion is carried out at low pressure up to 44 psia (approximately 3 bar), using air pressure to introduce the mercury into the larger pores (greater than 4 micrometers).
• a high pressure intrusion is carried out with oil up to the maximum pressure of 30,000 psia (approximately 2,000 bar).
• a mercury porosimeter thus makes it possible to establish a pore size distribution by volume.
• the median pore diameter of the support plate corresponds to the threshold of 50% of the population by volume.
• the porosity of the separating layer, corresponding to the total volume of pores in said layer, and the median pore diameter of the layer are advantageously determined according to the invention using a scanning electron microscope.
• the porosity obtained by this method can be assimilated to open porosity.
• sections of a wall of the support are made in cross section, so as to display the entire thickness of the coating over a cumulative length of at least 1.5 cm.
• the acquisition of the images is carried out on a sample of at least 50 grains, preferably of at least 100 grains.
• the area and the equivalent diameter of each of the pores are obtained from the photographs by conventional image analysis techniques, possibly after a binarization of the image aimed at increasing the contrast.
• a distribution of diameters equivalents from which the median pore diameter is extracted.
• the porosity of the layer is obtained by integrating the distribution curve of equivalent pore diameters.
• a median size of the particles constituting the separating layer can be determined by this method.
• An example of determining the median diameter of pores constituting the separating layer comprises the succession of the following steps, conventional in the field:
• a series of SEM photographs is taken from the support with its membrane separating layer observed in a cross section (that is to say throughout the thickness of a wall). For greater clarity, the photographs are taken on a polished section of the material.
• the acquisition of the image is carried out on a cumulative length of the membrane layer at least equal to 1.5 cm, in order to obtain values representative of the entire sample.
• the images are preferably subjected to binarization techniques, well known in image processing techniques, to increase the contrast of the contour of the particles or pores.
• pore diameter size distribution is thus obtained according to a conventional number distribution curve and a median diameter of pores constituting the membrane layer are thus determined, this median diameter corresponding respectively to the equivalent diameter dividing said number distribution into a first population. having only pores of equivalent diameter greater than or equal to this median diameter and a second population comprising only pores of equivalent diameter less than this median diameter.
• the support is formed from a porous ceramic material of SiC, see SiC linked by S1 3 N4, S12ON2, SiAlON or BN or a combination of these, preferably recrystallized SiC.
• the separating layer is formed from a porous inorganic material, in particular a non-oxide ceramic material, such as SiC, in particular recrystallized SiC, S1 3 N4, S12ON2, SiAlON, BN or a combination thereof.
• a porous inorganic material in particular a non-oxide ceramic material, such as SiC, in particular recrystallized SiC, S1 3 N4, S12ON2, SiAlON, BN or a combination thereof.
• Its porosity is typically 10 at 70% and the median pore diameter from 10 nm to 5 ⁇ m.
• the permeability of the membrane K m is preferably from 10 19 to 10 14 m 2 , preferably between 1.0.10 17 and 1.0.10 16 m 2 .
• the filter plate according to the invention can be obtained by any technique well known to those skilled in the art.
• a conventional manufacturing process generally comprises the main stages of manufacturing the support and then depositing the filtration membrane comprising or consisting of the filtering separating layer.
• the support for the plate is preferably obtained by pouring a slip or pressing a semi-dry mixture, or even by extruding a paste through a die. This step is followed by drying and baking to sinter the material. A particular choice of powders of the mixture before shaping and the maximum baking temperature and the time to plateau at this maximum temperature making it possible to obtain the optimum porosity and mechanical strength characteristics.
• the mixture also includes additives such as a dispersant or even a PH regulator in the case of a slip; organic binders, for example of the cellulose derivative type, or even lubricants and plasticizers, in the case of a pressing or extrusion mixture. Water is added, typically between 5 and 40% of the mass of inorganic powders and kneaded until a homogeneous mixture is obtained.
• a dispersant such as sodium hydroxide can be added in order to correct the PH between 8.5 and 10, preferably between 9.0 and 9.5.
• drying step can be preceded by a hardening step, in particular before demolding in the case of shaping by casting. drying of the raw supports, for example in an oven and / or by microwave, for a time sufficient to bring the water content which is not chemically bound to less than 1% by mass,
• the material obtained has an open porosity of 15 to 55%, preferably 20 to 45% by volume and a median pore diameter of the order of 10 micrometers to 100 micrometers, preferably from 15 micrometers to 40 micrometers, more preferably from 20 to 30 micrometers.
• the support is then coated with a membrane.
• This membrane comprises or consists of the separating layer according to the invention.
• the membrane comprises, in addition to the separating layer, a bonding primer disposed between the surface of the support and the separating layer, most often whose porosity is intermediate between that of the support and that of said separating layer .
• the various layers of the membrane, in particular the separating layer can be deposited according to various techniques known to those skilled in the art: deposition from suspensions or slips, chemical vapor deposition (CVD) or deposition by thermal spraying, for example plasma spraying.
• the membrane layers are deposited by coating from slips or suspensions.
• the membrane can be obtained by depositing several successive layers.
• the membrane advantageously comprises a first layer, called the primer, deposited in direct contact with the substrate. The primary plays the role of bonding layer.
• the slip used for the deposition of the primer preferably comprises between 30 and 70% by mass of SiC grains having a median diameter of 1 to 40 mhi, the complement being for example a powder of metallic silicon, of silica and / or a carbon powder.
• 100% by mass of SiC grains are mixed, including 30 to 70% of a first fraction of one or more SiC powders which has a median diameter between 1 and 40 mhi and 70 to 30% d '' a second fraction of one or more SiC powders which has a median diameter between 0.2 and 5 mhi, the first fraction having a diameter at least twice, even three times or even five times greater than the diameter of the second .
• the mass ratio of water added to the total of SiC varies from 0.8 to 1.2.
• the slip may include adjuvants such as lubricants, temporary binders, plasticizers, defoamers.
• the membrane also includes a separating layer deposited on the primer layer. It is in this separating layer that the porosity is controlled in order to give the filter its selectivity.
• the slip used for depositing the separating layer can comprise between 30 and 70% by mass of SiC grains having a median diameter of 0.5 to 20 mhi or between 30 and 70% by mass, in total, of a mixture metallic silicon, silica and carbon, the balance being deionized water.
• the slip only has a mineral component in the form of an SiC powder having a median diameter between 0.1 and 11 micrometers.
• the mass ratio of water added to the total SiC varies from 0.8 to 1.2.
• slips can typically comprise from 0.1 to 1% of the water mass of thickening agents preferably chosen from cellulose derivatives. They can typically comprise from 0.1 to 5% of the mass of SiC powder of binding agents preferably chosen from poly (vinyl alcohol) (PVA) or and acrylic derivatives.
• PVA poly (vinyl alcohol)
• the slip can also comprise from 0.01 to 1% of the mass of SiC powder of dispersing agents preferably chosen from ammonium polymethacrylate.
• One or more layers of slip can be deposited to form the membrane.
• the deposition of a slip layer typically makes it possible to obtain a membrane with a thickness of 2 to 80 ⁇ m, but thicker membranes typically of 100 to 300 ⁇ m can be obtained by the deposition of several successive layers of slip.
• the coated product is then dried at room temperature typically for at least 30 minutes and then at 60 ° C for at least 6 hours.
• the supports thus dried are sintered at a cooking temperature typically between 1200 ° C. and 2200 ° C., preferably between 1500 ° C. and 2000 ° C., under a non-oxidizing atmosphere, preferably under argon so as to obtain a membrane porosity measured by image analysis of 10 to 70% by volume and an equivalent median pore diameter measured by image analysis of 5 nm to 5 pm, preferably between 100 nanometers and 3000 nanometers .
• the filter plate according to the invention can be used for various applications for purifying liquids and / or separating particles or molecules or microorganisms from a liquid.
• the filter plate according to the invention can be used in particular for various liquid purification applications and makes it possible to maximize the flow of filtrate independently of the viscosity of the liquid to be filtered. It can be used to filter liquids having for example a dynamic viscosity of 100 to 5000 mPa.s, or even up to 10000 mPa.s.
• the dynamic viscosity of the fluid to be filtered can be measured at 20 ° C, under a shear gradient of 1 s 1 according to DIN 53019-1: 2008.
• the present invention relates in particular to the use of a filtering plate as described above for the purification of production water from petroleum extraction or shale gas. It also finds its application in various industrial processes for the purification and / or separation of liquids in the chemical, pharmaceutical, food, agrifood or bioreactor fields, as well as in swimming pool water.
• the invention also relates to a device which may further comprise one or more ventilation plates.
• the aeration plate or plates are in fluid communication with means for supplying the aeration gas over a portion of its surface which is otherwise sealed in a sealed manner from the liquid to be filtered in the enclosure, so that the liquid to be filtered cannot pass between said aeration plate and said means for supplying aeration gas.
• the aeration gas can be air, or even oxygen, in particular to act on the biological activity in the case of a membrane bioreactor. It can also be a gas in order to chemically treat the liquid to be filtered, for example by reduction or by oxidation.
• the said ventilation plate (s) can be fixed or mobile, just like the filtration plate.
• Each ventilation plate can advantageously be interposed between two filter plates. It can include silicon carbide. It can have substantially the same material characteristics as the filter plate. According to a possible embodiment, a filtering plate can also constitute an aeration plate, the means for supplying the aeration gas then being able to be or not connected to the means for evacuating the filtrate or permeate, the plate operating from alternatively in filtration mode or in ventilation mode.
• FIG. 1 illustrates a sectional view of a filtering device 1 according to the invention comprising an enclosure 2 surrounded by walls (not shown in the figure) supplied by a tube 3 with liquid to be filtered, a typical path of which in the enclosure is symbolized by the arrows 5.
• the liquid to be filtered is put into turbulence by means 4 which can be a propeller, a turbine or an axis provided with fins.
• the means 4 passes through the filter plate 6, the support 7a of which is coated with a membrane comprising a separating layer 7b of the type previously described.
• the filtration plate according to the invention as shown in FIG. 1 is a disc of diameter D and of thickness e, pierced in its center with an orifice of diameter d.
• the plate 6 is substantially identical to that described in relation to Example 1.
• FIG. 2 illustrates a sectional view of another filtering device 11 according to the invention incorporating a filtration plate 16 and comprising an enclosure 12 supplied by a tube 13 with liquid to be filtered, a typical path of which in the enclosure is illustrated by the arrows 15.
• the plate 16 comprises a porous support 17a coated with a filtration membrane 17b comprising a separating layer
• the filtration plate is integral with a hollow axis 14, the two elements being movable in rotation in the enclosure.
• the liquid to be filtered is put into turbulence this time by means of the movable hollow axis 14 and the plate, itself driven in rotation with the axis.
• the liquid to be filtered passes through the filter plate and the filtrate 18 obtained progresses through the thickness of the filter plate and joins the evacuation means in the hollow axis 14.
• the sealed contact between the axis 14 and the filter plate 16 being ensured by a seal 19.
• the filtering plate in both cases must be able to withstand varying degrees of high mechanical stresses due to the highly turbulent regime of the liquid to be filtered which can be particularly viscous or even abrasive.
• Substrates or supports were obtained by casting a slip in a plaster mold.
• the different basic compositions of the mixture of grains making up the pouring slip and the dimensions of the plates obtained for each example are described in Table 1.
• the supports were then dried at 110 ° C./ 12h then cooked under Argon at 2200 ° C in a 6h stage.
• the porosity and the median pore diameter of the substrates are obtained by adapting the particle size composition of the mixture of grains of the slip.
• a series of five supports has been produced, for example.
• the substrates all have the shape of a disc of diameter D pierced in its center with an orifice of diameter d.
• a filtration membrane was then deposited on the surface of the supports except the peripheral thickness which was masked (evacuation face).
• the membrane is deposited by coating with slip. For this, a primary bonding of the membrane is formed first, from a slip whose formulation is specified in Table 1 below.
• a separating layer is then deposited on the primer layer from a slip whose formulation is specified in Table 1 below.
• the viscosity of the slip measured at 22 ° C. under a shear gradient of 1 s 1 according to standard DINC33-53019-1: 2008, is adjusted to 0.1 Pa.s using well-known additives of l skilled in the art.
• the primer and the separating layer are deposited according to the same process.
• the slip is introduced into a tank with stirring at 20 revolutions / min.
• a modulus of rupture in bending at 20 ° C. was determined according to a test No. 1. (MOR 20 ° C), measured in air on a test piece with dimensions (in mm 3 ) of 80x20xthickness of the plate.
• the 3-point bending assembly is carried out with a distance of 60 mm between the two lower supports and the speed of descent of the punch is equal to 0.5 mm / min.
• the value is an average resulting from three successive measurements. The results are reported in Table 3 below.
• a plate flexion test No. 2 was also carried out in order to measure the load leading to failure, thus determining the strength at failure.
• a punch with a diameter greater than the internal diameter of the disc with lower supports is applied to the plate maintained at its periphery on a circular support with upper supports as shown diagrammatically in FIG. 3.
• a force is applied to the upper face of the punch with the using a press at a substantially constant speed (100 Kg / min) until breaking.
• the failure load expressed as a percentage relative to Example 2 according to the invention, for which the value of 100% has been assigned, is reported in Table 3.
• the filtration capacity was evaluated by flow measurement by placing a filter plate in an enclosure as described in Figure 1.
• the fluid consists of demineralized and deionized water at a temperature of 25 ° vs. It is injected into the enclosure at a pressure of 2 bars and at a rotation speed of 350 rpm in order to ensure a transmembrane pressure of 1.5 bars.
• the seal between the recovery means at the periphery and the peripheral evacuation face of each plate is ensured by an O-ring with a thickness of 13mm.
• the flow characteristic of the plate of the example in percentage as compared to Example 1 according to the invention is reported in Table 3 for which an efficiency of 100% has been assigned.
• the resistance to intensive backwashing is evaluated consists in subjecting the filter to 1000 pulses of water under a pressure of 3 bars for 1 second every minute so that the liquid crosses the porous walls at countercurrent.
• the increase in permeability which may result from degradation of the membrane is measured.
• Example 2 is taken as a reference (a value of 100 is assigned to it).
• a value lower than 100, for example 80, means a relative loss of permeability more low by 20% compared to the reference (and therefore better resistance to mechanical stresses induced by backwashing).
• Comparative examples 1 to 3 show that a porosity of 13% (comparative example 2) or 55% (comparative example 1) of the support or a difference between the maximum length and the diameter of the central orifice too great (comparative example 3) lead to a bad compromise between filtration capacity and mechanical properties (MOR mechanical strength and / or flexural strength).
• the filter plates of Examples 1 and 2 according to the invention present the best compromise in terms of filtration capacity and mechanical properties with regard to the comparative examples.
• the filter of Example 3 according to the invention is characterized by good mechanical properties but, however, lower filtration capacities than Examples 1 and 2, although these remain acceptable. According to the invention, such an embodiment will be favored in a purification device in which the filter plates are subjected to high mechanical stresses.
• the filter according to example 4 is characterized by very high filtration capacities but lower mechanical properties, although these remain entirely acceptable for use in a purification device, requiring a very high flow and constraints. weaker mechanical.
• the importance of the porosity of the layer of the separating layer is demonstrated by the comparison of Example 2 according to the invention, by comparison with Comparative Examples 4 and 5. For these three examples, the characteristics of the supports are identical, but the porosity characteristics of the separating layer are varied.
• Example 2 according to the invention shows that a porosity of the separating layer greater than that of the support advantageously makes it possible to obtain very satisfactory filtration properties while preserving an acceptable mechanical strength. for the application.
• the comparison of Example 2 according to the invention with Comparative Examples 4 and 5 shows that a porosity of the separating layer of between 30 and 50%, combined with the characteristics of geometry and porosity of the support as claimed leads to the best overall performance, in particular in terms of compromise between mechanical strength (tests 1 and 2), filtration capacity (test 3) and backwashing capacity (test 4).

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Filtering Materials (AREA)
• Ceramic Products (AREA)

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• 2018
  • 2018-11-30 FR FR1872171A patent/FR3089131B1/fr active Active
• 2019
  • 2019-11-28 WO PCT/FR2019/052829 patent/WO2020109731A1/fr unknown
  • 2019-11-28 EP EP19835691.7A patent/EP3887025A1/de active Pending

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