Classifications

• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D15/00—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used
  • D03D15/20—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the material of the fibres or filaments constituting the yarns or threads
  • D03D15/283—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the material of the fibres or filaments constituting the yarns or threads synthetic polymer-based, e.g. polyamide or polyester fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/08—Filter cloth, i.e. woven, knitted or interlaced material
  • B01D39/083—Filter cloth, i.e. woven, knitted or interlaced material of organic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D25/00—Filters formed by clamping together several filtering elements or parts of such elements
  • B01D25/12—Filter presses, i.e. of the plate or plate and frame type
  • B01D25/176—Filter presses, i.e. of the plate or plate and frame type attaching the filter element to the filter press plates, e.g. around the central feed hole in the plates
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D15/00—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used
  • D03D15/30—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the fibres or filaments
  • D03D15/37—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the fibres or filaments with specific cross-section or surface shape
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D15/00—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used
  • D03D15/40—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the yarns or threads
  • D03D15/41—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the yarns or threads with specific twist
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D9/00—Open-work fabrics
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/04—Additives and treatments of the filtering material
  • B01D2239/0464—Impregnants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
  • B01D2239/065—More than one layer present in the filtering material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
  • B01D2239/065—More than one layer present in the filtering material
  • B01D2239/0659—The layers being joined by needling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/12—Special parameters characterising the filtering material
  • B01D2239/1216—Pore size
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2321/00—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D10B2321/02—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins
  • D10B2321/021—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins polyethylene
  • D10B2321/0211—Fibres made from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds polyolefins polyethylene high-strength or high-molecular-weight polyethylene, e.g. ultra-high molecular weight polyethylene [UHMWPE]
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2401/00—Physical properties
  • D10B2401/10—Physical properties porous
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2505/00—Industrial
  • D10B2505/04—Filters

Definitions

• the invention lies in the field of filter cloths.
• a filtering unit for instance a so-called "plate filter”, which comprises at least one filter cloth.
• This filter cloth is placed under strain of pressure by throughput of the mass with force, whereby tensile forces occur in the cloth.
• the cloth must further be very well able to withstand the heavy mechanical influence of grains being partly held back and partly allowed through. It has not proved possible up until now to design a cloth sufficiently capable of withstanding the forces which occur.
• the filter cloths according to the prior art are insufficiently wear-resistant.
• the existing filters are therefore subject to a capacity loss increasing with use, a certain material loss as a result of the unintended passage of solids to be held back, whereby an environmental problem can then occur as the filtrate still contains particles with dimensions above the norm.
• the invention has for its object to provide a solution for the stated problems according to the prior art and provides for this purpose a filter cloth comprising a fabric of yarns consisting of polymer material and consisting of filaments/fibres with a parallel orientation of at least 80%.
• Claims 2, 3 and 4 give increasing degrees of preference.
• the invention further provides a cloth of the stated type wherein the degree of crystallization of the polymer material amounts to at least 60%.
• Claims 6, 7 and 8 give degrees of increasing preference.
• Suitable materials are for instance polyethylene, copolymer with ethylene, polyalkylketone. It will be apparent that the invention is not limited to these materials.
• the cloth can in particular be of the type with flat pattern design.
• the cloth according to the invention has the special feature that the fabric threads define pores with dimensions in the order of a maximum of 20 x 20 ⁇ m. Claims 18, 19 and 20 give increasing degrees of preference.
• the invention also relates to the use of filaments/fibres of the Dyneema type (mark of the Dutch concern DSM) for the above specified cloth according to the invention.
• the cloth according to the invention will generally be very fine-mesh and based on overstretched filaments/fibres.
• the stretching of the filaments/fibres will preferably go so far that amorphous portions substantially no longer occur therein.
• Such an impregnation has the advantage of providing sealing of the filament bundles in the yarn. This prevents adhesion, penetration into or even through by the material for filtering. A more permanent result of the calendering treatment is also obtained in this manner.
• the calendering treatment itself contributes toward discharge of the filter mass held back by the cloth because the cloth has a smoother surface.
• the fused material can be present in some abundance in the yarn which has for instance a substantially round sectional form.
• the setting of the calendering device which can be characterized by temperature, pressure and through feed speed, is such that the fibres remain unaffected but the impregnate melts and can rearrange itself in the yarn flattened by the pressure. Due to the effective squeezing the even nature of the impregnation is improved. The shearing strength of warp and weft is also improved, which results in retaining of the adjusted filter apertures or pores.
• the calendering treatment further contributes to an increase in the wear resistance.
• the cloth deficit can be calculated using goniometric calculations.
• a cloth according to the invention which for use in the plate filter comprises two cloth layers sewn to each other by sewing thread in an overlapping (filling) collar zone, can advantageously have the special feature according to the invention that the sewing thread consists of filaments/fibres of the Dyneema type (mark of the Dutch concern DSM) (Mm 52.5/3dr can for instance be envisaged) and use of so-called SPI needles.
• substantially rectan- gular pores can be envisaged with dimensions of 20 x 20 ⁇ m. Smaller pores have even been contemplated since the invention offers the option of manufacturing such pores with a large degree of accuracy and stability. It would nevertheless appear probable that in order to filter products with particles having diameters of less than 5 ⁇ m it is necessary to work with relatively elongate openings. As stated in claim 19, such elongate openings can preferably amount to 5-2 x 60-300 ⁇ m. Smaller pores of for example 5-20 x 5-20 ⁇ m are found to be insufficiently permeable.
• the dominant relevant parameters are the degree of twisting, the warp density, the weft density, the washing shrink, impregnation, calendering treatment and stretch during use.
• Applicable twistings vary between around 60 and 100 twists per metre in the case of multifilament yarn DTex 440. With regard to the occurrence of stretch and resulting loss of strength, data above 100 twists per metre is less significant. At less than 60 twists per metre the yarn is more difficult or even impossible to process in warp direction on the weaving machine.
• Choice of the correct setting of the density of the warp results in an approximation of the filterability on the basis of particle size.
• the set density of the weft determines the effective permeability.
• the intermediate measured settings shift by 0.5 threads per cm and give more or less proportional values (17 threads, 50 ⁇ m, 1 min. 15 s.). Due to the above described impregnation the entire amount of liquid, in particular water, runs through the openings between warp and weft. In a test on the mentioned installation it was found that cloth with a throughfeed time amounting to more than 2 minutes 30 seconds is insufficiently permeable.
• Yarns of substantially round filaments have larger openings than yarns with an at least more or less rectangular cross section, this of course with corresponding cross- sectional area. A better sealing contributes to closing of the cloth against penetrating filter particles. This also reduces the dependency on the quality of the impregnation.
• known aramide fibres have a round cross-sectional form.
• Dyneema fibres are supplied with an at least more or less rectangular cross sectional form. It should be understood in this respect that the designation "rectangular" is of rather qualitative character and should not be interpreted too absolutely. It is important to note that the thickness of the fibres is small relative to the dimension lying more or less perpendicularly thereof, wherein it is noted that Dyneema fibres have a more or less kidney- shaped cross section.
• Figure 1 shows a perspective view of a plate filter
• Figure 2 is a partly cut away top view of the plate filter according to figure 1;
• Figure 3 is a perspective view of a plate with a double filter cloth according to the invention
• Figure 4 shows in perspective view the plate and the filter cloth of figure 3 in assembled state
• Figure 5 shows a detail cross section through two assembled filter plates with a filter cloth according to the invention in assembled state
• Figure 6 is a perspective view of a part of a filter cloth with a pleated edge
• Figure 7 is a perspective view of a variant of a double filter cloth with pleated edges
• Figure 8 is a partly broken away perspective view of a detail of the filter cloth according to figure 3.
• Figure 9 is a cross-sectional view of a double filter cloth according to yet another embodiment.
• Figure 1 shows a plate filter 1 in which a number of filter cloths according to the invention are applied.
• a plate filter is generally known per se. The description of the filter 1 will therefore be kept brief.
• a frame 2 comprises two supporting rods 3, 4. These supporting rods support filter plates 5 which will be further discussed hereinafter.
• Plate 1 . 5 are provided with carrier supports 7, 8 (see also figure 3) which also serve as handles such that the plates 5 can be placed from above into the space between the rods 3, 4 to then be supported by the rods 3, 4 via the carrier supports 7, 8.
• Respective filter cloths are added beforehand to the plates 5. After placing of all plates a hydraulic cylinder 6 is energized to press the plates with great force against each other, whereby these latter, by interposing of the filter cloths (see for instance figure 5) , press substantially sealingly against each other.
• the plate filter 1 comprises a feed pipe 9 and four discharge pipes, all designated with 10 for the sake of convenience.
• FIG 2 shows a plate filter 11 of the same type as in figure 1 in partly broken away top view.
• the plates 5 have central passages 12 through which the liquid for filtering can enter the filter via the feed 9 and pass through respective filter cloths 13 in this filter, whereafter the filtrate can be guided via passages 14 to the discharges 10.
• each filter cloth 13 is embodied such that it as it were wholly encloses the filter plate 15 and covers all surfaces thereof, including the inner surface of passage 12. Passages 14 are open.
• FIG. 3 shows a filter plate 5.
• This comprises a peripheral edge 15 in which the four passages 14 debouch.
• the edge 15 bounds a recessed portion 16 in which regularly grouped elevations 17 are arranged which serve to support the filter cloth 19 in order to preserve therebehind a space through which filtrate can flow.
• Nine broader elevations 18 have the same height as the peripheral edge 15 and serve for the pressure-transmitting contact with a subsequent plate, this all with interposing of the filter cloth 19.
• the filter cloth 19 consists of two cloth parts 20, 21 which are mutually connected by a cloth tube through sewing. Reference is made in this respect to figures 5, 8 and 9.
• the cloth part 20 is carried through the passage 21 in the manner indicated with arrows 23, whereafter the peripheral edges of cloth parts 20, 21 protruding outside the plate 5 are mutually connected by tacking loops via the registered eyes 25 in the peripheral edges of the cloth parts 20, 21. A simple fixation of cloth 19 to filter plate 5 is thus obtained.
• Figure 5 shows two plates 5 with associated cloths 19 which are placed against each other and form part of a plate filter 1 or 11.
• FIG 5 shows that cloth 19 is supported in recess 16 by the outer surfaces of elevations 17. Connecting onto the bottom of this recess 16 are filtrate outlets 26 which debouch into the passages 14 for discharge of filtrate. The solid fraction of the liquid for filtering is held back by cloth 19.
• the tube 22 which covers the inner surface of passage 12 mutually joins the cloth parts 20 and 21. In the manner shown in figure 5 the tube 22 is joined to the cloth parts 20 and 21 by means of a number of layers placed one on top of another which are sewn together by Dyneema yarns.
• Figure 8 shows this structure in more detail. Also shown schematically in figure 8 are the lock stitches 27 of the Dyneema yarns.
• the entire filter cloth 19 consists of Dyneema material. As this material exhibits very little stretch while adaptation to the form shown in figure 5 must be obtained, it is necessary to give the filter cloth parts 20, 21 a certain space so that they can move freely to some extent without coming under strain of stretch.
• Figure 6 shows the manner in which this can be achieved.
• This figure shows the peripheral edge 28 of cloth part 20.
• the outer zone 29 is given a reinforced form in the manner shown and provided with a strip 29 drawn in stretched position which is shorter than the zone 30 of cloth part 20 joining thereto in the stretched situation.
• "Space" is thus obtained in the cloth as shown schematically in figures 3 and 4.
• the cloth can thus display a certain concave or convex form such that it can adapt to the form of the plates 5 as shown in figure 5.
• FIG 7 shows an alternative cloth 31 which is likewise provided with the pleated zones 32 of the type as shown in figure 6 and explained with reference thereto.
• the cloth 31 comprises only one cloth part and tube 22 is omitted.
• the filter plates are embodied such that they co-act sealingly with the zone round the holes 32 arranged in the region of the passages 12 in cloth 31.
• fastening of the cloth parts to each other by means of the eyes 25 and tacking loops 24 as shown in figure 4 and figure 5 can be omitted in this embodiment.
• Figure 8 has already been discussed with reference to figure 5.
• figure 9 shows in cross section a cloth 33 wherein the respective cloth parts 34, 35 are mutually joined by means of a tube 36 which is connected to cloth parts 34 and 35 in the manner shown.
• the lock stitches are once again designated with the reference numeral 27.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Woven Fabrics (AREA)
• Filtering Materials (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=26647205

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (2)

Family Cites Families (6)

• 1994
  • 1994-10-20 NL NL9401746A patent/NL9401746A/nl not_active Application Discontinuation
• 1995
  • 1995-04-13 AU AU21495/95A patent/AU2149595A/en not_active Abandoned
  • 1995-04-13 EP EP95914577A patent/EP0758262A1/en not_active Withdrawn
  • 1995-04-13 WO PCT/NL1995/000136 patent/WO1995028216A1/en not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events